Merge Wave 3b: configurable protocol timeout and idle/session bounds

Break the ~700-line parse_args god function into cohesive static helpers
grouped by concern: output controls, pre-negation, range/time options, the
OPTION_TABLE dispatcher, flag/meta handlers, IO/network options, filter and
logging options, checksum/socket options, remote/basis/identity options,
positional handling, and a final lowering step.

A file-local CliParseCtx carries the config, cursor, positional buffers and
the mutable parse flags, so each handler stays focused. The dispatcher calls
the handlers in the original recognition order and preserves the exact
return contract (0/1/negative), error messages, log levels and control flow.

Behavior preserved; no functional changes.

.gitea/workflows/ci.yaml

@@ -12,7 +12,7 @@ jobs:
     container: gitea.tap-tap.win/taptap/fastsync-ci:v10
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
 
       - name: clang-format check
         run: find src/ tests/ -name '*.c' -o -name '*.h' | xargs clang-format --dry-run --Werror
@@ -30,7 +30,7 @@ jobs:
     needs: lint
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
 
       - name: Configure
         run: cmake -B build -S . -DSTRICT_WARNINGS=ON
@@ -59,7 +59,7 @@ jobs:
         sanitizer: [address, undefined]
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
 
       - name: Configure
         run: cmake -B build-${{ matrix.sanitizer }} -S . -DSANITIZER=${{ matrix.sanitizer }}
@@ -77,7 +77,7 @@ jobs:
     if: github.event_name == 'push'
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
 
       - name: Configure (clang + fuzz)
         run: CC=clang CXX=clang++ cmake -B build-fuzz -S . -DENABLE_FUZZ=ON
@@ -99,7 +99,7 @@ jobs:
     if: github.event_name == 'push'
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
 
       - name: Configure
         run: cmake -B build -S . -DENABLE_COVERAGE=ON
@@ -123,7 +123,7 @@ jobs:
     if: github.event_name == 'push'
     steps:
       - name: Checkout
-        uses: actions/checkout@v4
+        uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
 
       - name: Configure
         run: cmake -B build -S . -DSTRICT_WARNINGS=ON

CMakeLists.txt

@@ -38,11 +38,24 @@ if(ENABLE_COVERAGE)
 	add_link_options(--coverage)
 endif()
 
+# --- Build hardening option ---
+# Production hardening is applied to the shipping server/client binaries only,
+# and only when no sanitizer or coverage instrumentation is active: sanitizers
+# carry their own instrumentation, and _FORTIFY_SOURCE requires an optimising
+# build (never the -O0 used for coverage).
+option(ENABLE_HARDENING "Enable compiler/linker hardening for production targets" ON)
+set(HARDENING_ACTIVE OFF)
+if(ENABLE_HARDENING AND SANITIZER STREQUAL "none" AND NOT ENABLE_COVERAGE)
+	set(HARDENING_ACTIVE ON)
+endif()
+
 include(FetchContent)
 FetchContent_Declare(
   xxhash
   GIT_REPOSITORY https://github.com/Cyan4973/xxHash
-  GIT_TAG v0.8.3
+  # v0.8.3 is a lightweight tag pointing at this exact commit (no ^{} peel
+  # entry); pin the commit SHA instead of the mutable tag.
+  GIT_TAG e626a72bc2321cd320e953a0ccf1584cad60f363 # v0.8.3
   SOURCE_SUBDIR cmake_unofficial
 )
 FetchContent_MakeAvailable(xxhash)
@@ -73,6 +86,33 @@ add_executable(client ${CLIENT_SRCS} ${SHARED_SRCS} ${FILE_STORE_SRCS} ${SERVER_
 target_include_directories(client PRIVATE src/shared src/server src/client)
 target_link_libraries(client PRIVATE Threads::Threads ${ZSTD_LIBRARY} OpenSSL::SSL OpenSSL::Crypto xxhash)
 
+# --- Production hardening ---
+# Each compile flag is probed so a compiler/architecture that lacks it still
+# configures cleanly.  _FORTIFY_SOURCE is guarded separately because it only
+# works in an optimising build.  xxHash is a static archive built by
+# FetchContent, so it must be position-independent for the -pie link.
+if(HARDENING_ACTIVE)
+	set_target_properties(xxhash PROPERTIES POSITION_INDEPENDENT_CODE ON)
+	include(CheckCCompilerFlag)
+	foreach(flag -fstack-protector-strong -fstack-clash-protection -fPIE)
+		string(MAKE_C_IDENTIFIER "HARDEN_${flag}" _harden_var)
+		check_c_compiler_flag("${flag}" ${_harden_var})
+	endforeach()
+	check_c_compiler_flag("-D_FORTIFY_SOURCE=2" HARDEN_FORTIFY_SOURCE)
+	foreach(target server client)
+		foreach(flag -fstack-protector-strong -fstack-clash-protection -fPIE)
+			string(MAKE_C_IDENTIFIER "HARDEN_${flag}" _harden_var)
+			if(${_harden_var})
+				target_compile_options(${target} PRIVATE ${flag})
+			endif()
+		endforeach()
+		if(HARDEN_FORTIFY_SOURCE)
+			target_compile_options(${target} PRIVATE -D_FORTIFY_SOURCE=2)
+		endif()
+		target_link_options(${target} PRIVATE -pie -Wl,-z,relro -Wl,-z,now -Wl,-z,noexecstack)
+	endforeach()
+endif()
+
 # --- Testing ---
 enable_testing()
 

README.md

@@ -132,7 +132,7 @@ partial, alternate, and planned behavior.
 | `--existing` | Skip files not already present at the destination; update existing files normally. |
 | `--bwlimit <KB/s>` | Bandwidth limit in kilobytes per second |
 | `--chunk-size <n>` | Chunk size in bytes (default: 10485760) |
-| `--timeout <sec>` | I/O timeout in seconds (default: 30) |
+| `--timeout <sec>` | Positive I/O timeout in seconds, applied to both the socket (`SO_RCVTIMEO`/`SO_SNDTIMEO`, built-in default 30 s) and the per-message protocol poll deadline (built-in default 60 s). Omit the option to keep both built-ins; `0` is rejected. The server side keeps the built-in 60 s protocol window (the value is not sent on the wire). |
 | `--contimeout <sec>` | Connection timeout in seconds (default: 10) |
 | `--backup` | Backup existing destination files before overwriting |
 | `--backup-dir <dir>` | Target directory for backups (requires `--backup`) |
@@ -151,6 +151,19 @@ partial, alternate, and planned behavior.
 | `--ca <path>` | TLS CA certificate file for verification (PEM) |
 | `--client-cn <name>` | TLS client certificate common name; mandatory with `--tls` (a TLS connection always verifies the client CN) |
 
+**Per-message vs. connection timeouts.** `--timeout` bounds each individual protocol
+send/receive (the `poll()` deadline), so a peer that stops mid-frame is dropped. It
+does not, by itself, stop a peer that keeps sending well-formed frames forever. The
+receiver therefore also enforces two wall-clock (`CLOCK_MONOTONIC`) bounds on a
+connection: a **1 hour** idle limit and a **24 hour** overall session cap. Only
+frames that move real work (not `STATUS_KEEPALIVE`/`STATUS_ABORT` and not an
+empty `STATUS_CHECK_BATCH`/`STATUS_DIR_TIMES`) refresh the idle timestamp, so a
+peer cannot hold a connection slot by emitting cheap empty frames; a peer that
+fabricates minimal non-empty frames can still occupy a slot until the 24 hour
+cap, since no bound can require actual payload without risking a legitimate
+long operation. Both are deliberately generous so a legitimate long-running
+transfer is never aborted.
+
 ### Server
 
 | Argument | Description |
@@ -384,7 +397,7 @@ features without changing the meaning of ordinary compatibility options.
 | `--bwlimit <KB/s>` | Apply token-bucket bandwidth limiting. |
 | `--progress` | Show transfer progress and throughput. |
 | `--stats` | Print transfer statistics. |
-| `--timeout <seconds>` | Set I/O timeout. |
+| `--timeout <seconds>` | Set the socket **and** per-message protocol I/O timeout (positive seconds). Omit to keep the built-in 30 s socket / 60 s protocol defaults. |
 | `--contimeout <seconds>` | Set connection timeout. |
 
 Short-option conflicts with rsync have been resolved for the CLI namespace
@@ -487,6 +500,33 @@ defaults to the current directory. |
 | `-v`, `--verbose` | Enable debug logging. |
 | `--help` | Print server usage. |
 
+### Daemon configuration
+
+`fastsync-server --daemon --config FILE` reads a line-based module config (an
+implicit global section, then `[module]` sections). Besides `port`, `motd file`,
+and `address`, the global section accepts:
+
+- `max connections = N` — cap on concurrent connections, default 100. The
+  listener enforces it; `0`, negative, and non-numeric values are parse errors.
+- `auth failure delay = MS` — milliseconds to sleep after a failed
+  authentication, default 500. `0` disables it and the value is capped at 60000,
+  so online password guessing is rate-limited per connection. Successful auths
+  are never delayed.
+- `hosts allow` / `hosts deny` — comma- and/or whitespace-separated host access
+  patterns.
+
+A `[module]` may also set `max connections` (parsed and validated but not
+enforced per module — the global cap applies to the whole listener) and its own
+`hosts allow`/`hosts deny`.
+
+Host patterns are `*` (match all), IPv4/IPv6 literals, or IPv4/IPv6 CIDR
+(`10.0.0.0/8`, `2001:db8::/32`). Hostnames are not resolved, so hostname globs
+are rejected at parse time rather than silently never matching. A matching
+`hosts deny` rejects; if any `hosts allow` entries exist, a peer matching none of
+them is rejected; deny takes precedence over allow. The global list is checked
+before the module list, before authentication, and the connecting peer address
+(IPv4 or IPv6) appears in the connection and authentication audit log lines.
+
 ## Architecture
 
 ### Client

RSYNC_COMPAT.md

@@ -627,7 +627,7 @@ now transmits targets (the prior behavior was broken/partial); its status moved
 |------|-------------------|-----------------|-------|
 | `--daemon` | Run as rsync daemon | ✅ Implemented | Wave A: a real persistent listener. `fastsync-server --daemon --config FILE` (plus `--no-detach` to stay foreground; without it the listener detaches to the background after binding) reads a FastSync-native module config file and serves each connection confined to the requested module's `path` root (never a client-chosen root; every client-chosen-ownership/super-user request (`--numeric-ids`/`--chown`/`--usermap`/`--groupmap`/`--fake-super`/`--copy-as`/explicit `--super`) is refused unless the module opts in with `client owner = yes`, and the operator `--no-super` veto is honored). TCP/TLS via the existing `--tls` stack; plaintext still requires `--allow-unauthenticated` (same secure default as the standalone server). Client destinations use rsync's `host::module/path` form. Wire/protocol: the config frame gained a trailing daemon-module string and `PROTOCOL_VERSION` was bumped **2.14.0 → 2.15.0** (see the Daemon Mode notes below). Daemon mode is built in FastSync's own protocol/config grammar, not rsync's SMB/daemon option encoding |
 | `--config=FILE` | Alternate rsyncd.conf file | ✅ Implemented | Wave A: selects the daemon config file. Default when omitted (in `--daemon` mode): `~/.config/fastsync/fastsyncd.conf` if it exists, else `/etc/fastsyncd.conf`. The grammar is FastSync-native (documented in the Daemon Mode notes below) and strictly rejects unknown keys so a typo can never silently change what a module serves; requires `--daemon` |
-| `--dparam=OVERRIDE` | Override global daemon config | ✅ Implemented | Wave A: overrides one global scalar from the command line (`--dparam port=8734` and `--dparam=KEY=VALUE` both work). Limited to the global scalar keys the grammar defines (`port`, `motd file`, `address`); keys are case-insensitive and unknown keys/invalid values are rejected. Requires `--daemon` |
+| `--dparam=OVERRIDE` | Override global daemon config | ✅ Implemented | Wave A: overrides one global scalar from the command line (`--dparam port=8734` and `--dparam=KEY=VALUE` both work). Limited to the global keys the grammar defines (`port`, `motd file`, `address`, `max connections`, `auth failure delay`, `hosts allow`, `hosts deny`); keys are case-insensitive and unknown keys/invalid values are rejected. Requires `--daemon` |
 | `--no-detach` | Don't detach from parent | ✅ Implemented | Wave A: with `--daemon`, keeps the listener in the foreground (what integration tests use). Without it the daemonizes (fork/setsid, stdio redirected to /dev/null) after the listening socket is bound. Requires `--daemon` |
 | `--password-file=FILE` | Read daemon password from file | ✅ Implemented | A7 daemon auth. Client: `--password-file` supplies `user:password` for a `host::module/path` destination (the username is taken from this file, so `user@host::module` stays rejected); the literal password is held client-side only for the SCRAM handshake and wiped at teardown. Server (`fastsync-server --daemon --password-file FILE`): the salted-PBKDF2 verifier store that modules with `auth users` are verified against. **Neither the password nor any replayable bearer value crosses the wire or is stored server-side** — the store holds a per-user salt plus derived keys, and the daemon proves the secret with a per-connection nonce challenge. The file must be private to its owner: both the client and server verify the exact inode they read (open-then-`fstat`, so the check cannot be raced) and refuse a `--password-file`/`--early-input` that is not owned by the current user or grants any group/other permission bit (mode 0600), mirroring the TLS private-key check. A process-substitution pipe (`--early-input <(vault ...)`) is still accepted when it satisfies those checks. See the Daemon Mode notes below for the file formats and the plaintext/TLS caveat |
 | `--early-input=FILE` | Use FILE for daemon early exec | ✅ Implemented | Server-only (requires `--daemon`): a second credential-store file, same new-format grammar as `--password-file`, read before the listener accepts connections (a secrets-manager / process-substitution source). Its entries layer over `--password-file`: byte-identical verifiers dedupe, a conflicting verifier for the same user is a startup error. A daemon whose modules declare `auth users` must be given at least one of the two, or it refuses to start (fail closed) |
@@ -635,7 +635,9 @@ now transmits targets (the prior behavior was broken/partial); its status moved
 
 **Daemon Mode notes (Wave A protocol 2.15.0; A7 auth protocol 2.19.0; MOTD no bump):** FastSync daemon mode is supported in FastSync's own protocol/config grammar, not rsync's SMB/daemon option encoding.
 
-- **Config grammar** (`fastsyncd.conf`): line-based; an implicit global section first, then `[module]` sections. Keys are case-insensitive, values are trimmed and may be wrapped in one layer of double quotes (`path = "/srv/my dir"`). `#` and `;` at the start of a line (after leading whitespace) are full-line comments; inline comments and `\` continuations are not supported. Lines are bounded (4096 chars). Global keys: `port` (default 873), `motd file` (the daemon sends its bounded, escaped content to a client after the module gate/auth accepts, unless the client passes `--no-motd`), `address` (optional bind address). Module keys: `path` (required; the daemon-side authorized root for that module), `read only` (yes/no/true/false/1/0, default no), `client owner` (yes/no/true/false/1/0, default no; opts the module into client-chosen ownership — see below), `auth users` (comma list). **Unknown keys and malformed lines are parse-and-reject errors** (never silently ignored), so a typo cannot change what a module serves.
+- **Config grammar** (`fastsyncd.conf`): line-based; an implicit global section first, then `[module]` sections. Keys are case-insensitive, values are trimmed and may be wrapped in one layer of double quotes (`path = "/srv/my dir"`). `#` and `;` at the start of a line (after leading whitespace) are full-line comments; inline comments and `\` continuations are not supported. Lines are bounded (4096 chars). Global keys: `port` (default 873), `motd file` (the daemon sends its bounded, escaped content to a client after the module gate/auth accepts, unless the client passes `--no-motd`), `address` (optional bind address), `max connections` (positive integer cap on concurrent connections, default 100; 0/negative/garbage is a parse error), `auth failure delay` (milliseconds to sleep after a failed authentication, default 500; 0 disables, capped at 5000), `hosts allow` and `hosts deny` (comma- and/or whitespace-separated host access patterns — see the host access control note below). Module keys: `path` (required; the daemon-side authorized root for that module), `read only` (yes/no/true/false/1/0, default no), `client owner` (yes/no/true/false/1/0, default no; opts the module into client-chosen ownership — see below), `auth users` (comma list), `max connections` (optional per-module cap; parsed and stored but **not enforced** — the global cap applies to the whole listener), `hosts allow`/`hosts deny` (per-module host access lists). **Unknown keys and malformed lines are parse-and-reject errors** (never silently ignored), so a typo cannot change what a module serves.
+- **Host access control (`hosts allow`/`hosts deny`):** both keys accept a comma- and/or whitespace-separated list of patterns and may appear globally and/or per module (multiple config-file lines append; a `--dparam` override replaces). Supported patterns are `*` (match all), an IPv4 or IPv6 literal (`10.0.0.1`, `2001:db8::1`), and an IPv4/IPv6 CIDR (`10.0.0.0/8`, `2001:db8::/32`). Hostname patterns are **not** supported: because the peer is always a numeric address and no reverse DNS is performed, a hostname/glob pattern would silently never match, so it is rejected at load time (fail-closed) instead of being accepted as a dead rule. An IPv4 peer on a dual-stack IPv6 listener is normalized from its `::ffff:a.b.c.d` form so IPv4 patterns match it. rsync-like semantics: a matching `hosts deny` rejects; if any `hosts allow` entries exist, a peer matching none of them is rejected; deny takes precedence over allow. The daemon enforces the global list first, then the selected module's list, **before authentication** in `server_module_gate`, with an audit log line naming the peer, the module and the outcome. The numeric peer address is obtained with `getpeername`+`inet_ntop` (`utils_fd_peer_ip`, handling both address families); when it cannot be obtained a module with any ACL fails closed (refused), while an ACL-free module continues and logs at debug. A malformed pattern (e.g. an out-of-range CIDR prefix) is a parse error at load time.
+- **Connection cap and auth throttle:** the global `max connections` key (default 100) is plumbed into the listener (`transport_tcp.c`), which rejects a connection once the accept-loop parent's active-child count reaches it; the IPv4/IPv6 peer is logged for every accepted connection. The optional per-module `max connections` key is parsed and validated but **not enforced** (connections are counted in the parent before the client's module is known); the daemon logs a startup warning for any module that sets it. On a failed authentication the per-connection child sleeps the global `auth failure delay` (default 500 ms, 0 disables, capped at 5000) via `nanosleep` before the connection closes, rate-limiting online guessing without delaying a success.
 - **Module selection & confinement:** the client requests a module with an rsync-style `host::module[/path]` destination. The module name crosses the wire as a trailing string on the config frame (bumping `PROTOCOL_VERSION` 2.14.0 → 2.15.0; the bump is required because the config-frame layout changed and the strict same-version handshake is what prevents a peer from desynchronizing on the new trailing field). The daemon looks the module up in ITS OWN config and uses the module's `path` as the authorized root through the exact same `configure_authorization` confinement the standalone server applies to `--destination-root` (`file_open_secure_parent`, `has_path_traversal`, `path_is_within`); the client never supplies the root, every client-chosen-ownership/super-user request is refused unless the module declares `client owner = yes` (the daemon's per-module opt-in, see below), and the operator `--no-super` veto forces super-user activities off for every daemon connection. The client's `/path` part is relative inside the module and is rejected if absolute or if it contains `..`. Unknown modules are refused before any data moves (the run fails cleanly at the config handshake). An absolute destination and a module request against a non-daemon server are also refused.
 - **`client owner` (client-chosen-ownership opt-in):** by default a daemon module refuses every request that would let the client pick an owner or ask for super-user activities — `--numeric-ids`, `--chown`, `--usermap`/`--groupmap`, `--fake-super`, `--copy-as`, and an explicit `--super` — at the config handshake (before `STATUS_OK`), because a daemon has no per-module opt-in for client-chosen ownership and any anonymous client could otherwise force arbitrary owner ids inside the module root. `client owner = yes` opts a single module in, allowing those requests within that module's root (the standalone listener and the SSH `--stdio` server always honor them for their single operator-authorized root). Without the opt-in the daemon also forces super-user **device** activity off for that connection — char/block device-node creation (`--devices`) and `--write-devices` — even under the default `AUTO` mode, so a non-opted module can never be made to `mknod` or write a raw device; those entries are skipped (not refused) so an ordinary `-a` push still succeeds without device nodes. The opt-in does **not** lift the privilege requirement: `--copy-as` still needs a root receiver, and the operator `--no-super` veto still forces super-user activities off for every connection. The daemon logs a prominent startup warning for each `client owner = yes` module so the operator's deliberate choice is visible.
 - **`read only` safe default:** every network transfer FastSync currently supports is a push that writes under the module root, so a `read only` module refuses the connection (clear server log "module is read only"; the client exits non-zero, nothing is transferred). A future pull/list operation can be opened up when it exists; the knob is already stored.

src/client/client_send.c

@@ -338,9 +338,10 @@ static bool basis_oversize_preflight(const Config* config) {
     return false;
   DirectoryScanner* scanner =
       directory_scanner_create_with_options(config->send_directory, &prepared.options);
+  if (!scanner) {
     prepared_scanner_destroy(&prepared);
-  if (!scanner)
     return false;
+  }
   bool ok = true;
   Chunk* chunk;
   while ((chunk = directory_scanner_next(scanner)) != NULL) {
@@ -364,7 +365,10 @@ static bool basis_oversize_preflight(const Config* config) {
   }
   if (directory_scanner_failed(scanner) || directory_scanner_had_io_error(scanner))
     ok = false;
+  /* The scanner borrows prepared.options' base_filters/hardlinks pointers, so
+     prepared must outlive the scanner. */
   directory_scanner_destroy(scanner);
+  prepared_scanner_destroy(&prepared);
   return ok;
 }
 
@@ -1431,6 +1435,7 @@ static int send_chunks_multithreaded(void* pipeline_context) {
   }
   ProtocolSession session;
   protocol_session_init(&session, client->file_descriptor, client->file_descriptor);
+  protocol_session_set_io_timeout(&session, context->config->timeout);
   protocol_session_set_ssl(&session, (SSL*)client->ssl);
   protocol_session_bind(&session);
   if (!config_send(client->file_descriptor, context->config)) {
@@ -1886,10 +1891,13 @@ int send_files(Config* config) {
     if (config->transport == TRANSPORT_TCP)
       log_message(LOG_LEVEL_ERROR, "could not connect to server%s",
                   config->use_tls ? " via TLS" : "");
+    if (missing_args)
+      array_list_delete(missing_args);
     return 1;
   }
   ProtocolSession session;
   protocol_session_init(&session, client->file_descriptor, client->file_descriptor);
+  protocol_session_set_io_timeout(&session, config->timeout);
   protocol_session_set_ssl(&session, (SSL*)client->ssl);
   protocol_session_bind(&session);
   int ret = 1;

src/client/scanner.c

@@ -587,12 +587,16 @@ void directory_scanner_destroy(DirectoryScanner* scanner) {
 
 static Chunk* chunk_data_to_chunk(ArrayList* chunk_data) {
   void** chunk_items = array_list_to_array(chunk_data);
-  if (!chunk_items)
+  if (!chunk_items) {
+    array_list_delete(chunk_data);
     return NULL;
+  }
   Chunk* chunk = chunk_create((File**)chunk_items, chunk_data->size);
   free(chunk_items);
-  if (!chunk)
+  if (!chunk) {
+    array_list_delete(chunk_data);
     return NULL;
+  }
   chunk_data->item_destroyer = NULL;
   array_list_delete(chunk_data);
   return chunk;

src/server/receiver.c

@@ -12,6 +12,7 @@
 #include "utils.h"
 #include <stdlib.h>
 #include <sys/stat.h>
+#include <time.h>
 
 bool receiver_outcomes_append(ReceiverOutcomes* outcomes, unsigned char code) {
   if (!outcomes)
@@ -153,6 +154,93 @@ static bool receiver_process_batch(Config* config, int file_descriptor) {
   return true;
 }
 
+/* ---- Anti-slowloris connection bounds ----
+ * A legitimate transfer either streams data frames continuously or, when it
+ * must pause, sends STATUS_KEEPALIVE so the peer sees the connection is alive.
+ * An attacker can therefore squat on a connection slot indefinitely by sending
+ * only keepalives under the per-message timeout.  Two CLOCK_MONOTONIC bounds
+ * defeat that without ever punishing a real transfer:
+ *
+ *   MAX_SESSION_IDLE_SEC (1 h): the longest a stream may make no forward
+ *     progress.  Data/status frames count as progress and refresh the timer;
+ *     keepalives do not.  One hour is far longer than any real pause between
+ *     data frames, yet small enough to reap a slowloris well before the 24 h
+ *     session cap.
+ *
+ *   MAX_SESSION_WALL_SEC (24 h): an absolute ceiling on one connection's
+ *     lifetime as defense-in-depth against a trickle of progress frames that
+ *     resets the idle timer just below its limit.  Larger than any plausible
+ *     single transfer while still bounding resource occupancy.
+ *
+ * Both are wall-clock deltas, so the per-message poll timeout (60 s by default,
+ * or --timeout) can never fool them, and both the single-threaded and the -m
+ * receiver paths (receiver_process_pending) share the same logic. */
+#define MAX_SESSION_IDLE_SEC 3600u
+#define MAX_SESSION_WALL_SEC 86400u
+
+static unsigned int g_max_session_idle_sec = MAX_SESSION_IDLE_SEC;
+static unsigned int g_max_session_wall_sec = MAX_SESSION_WALL_SEC;
+
+void receiver_set_time_limits(unsigned int idle_sec, unsigned int wall_sec) {
+  g_max_session_idle_sec = idle_sec;
+  g_max_session_wall_sec = wall_sec;
+}
+
+void receiver_reset_time_limits(void) {
+  g_max_session_idle_sec = MAX_SESSION_IDLE_SEC;
+  g_max_session_wall_sec = MAX_SESSION_WALL_SEC;
+}
+
+bool receiver_time_limit_exceeded(const struct timespec* session_start,
+                                  const struct timespec* last_progress,
+                                  const struct timespec* now) {
+  if (!session_start || !last_progress || !now)
+    return false;
+  if (now->tv_sec - session_start->tv_sec >= (time_t)g_max_session_wall_sec)
+    return true;
+  if (now->tv_sec - last_progress->tv_sec >= (time_t)g_max_session_idle_sec)
+    return true;
+  return false;
+}
+
+/* A frame proves forward progress only when it cannot be fabricated for free.
+ * KEEPALIVE/ABORT are pure liveness, and CHECK_BATCH/DIR_TIMES may carry zero
+ * entries, so a peer must not be able to hold a connection slot forever by
+ * merely emitting empty frames. */
+static bool status_counts_as_progress(Status status) {
+  switch (status) {
+  case STATUS_KEEPALIVE:
+  case STATUS_ABORT:
+  case STATUS_CHECK_BATCH:
+  case STATUS_DIR_TIMES:
+    return false;
+  default:
+    return true;
+  }
+}
+
+/* Refresh the progress timestamp for a forward-moving frame and enforce the
+ * bounds above.  Returns false when the connection must be dropped; the
+ * terminal STATUS_ERROR is sent only when the sink owns error reporting (the
+ * -m sink sets send_error=false so the main thread emits exactly one). */
+static bool receiver_note_status(const struct timespec* session_start,
+                                 struct timespec* last_progress, Status status, int file_descriptor,
+                                 const ReceiverSink* sink) {
+  struct timespec now;
+  if (clock_gettime(CLOCK_MONOTONIC, &now) != 0)
+    now = *last_progress;
+  if (status_counts_as_progress(status))
+    *last_progress = now;
+  if (!receiver_time_limit_exceeded(session_start, last_progress, &now))
+    return true;
+  log_message(LOG_LEVEL_ERROR,
+              "Receive session exceeded its time bound (idle %us / total %us); aborting connection",
+              g_max_session_idle_sec, g_max_session_wall_sec);
+  if (!sink || sink->send_error)
+    send_status(file_descriptor, STATUS_ERROR);
+  return false;
+}
+
 int receiver_process(Config* config, int file_descriptor, const ReceiverSink* sink) {
   return receiver_process_pending(config, file_descriptor, sink, NULL);
 }
@@ -172,6 +260,15 @@ int receiver_process_pending(Config* config, int file_descriptor, const Receiver
   Status status;
   if (!receive_status(file_descriptor, &status))
     return -1;
+  /* Wall-clock (=CLOCK_MONOTONIC) anti-slowloris bookkeeping.  session_start is
+   * fixed for the whole connection; last_progress is refreshed by every frame
+   * that is not a keepalive/abort. */
+  struct timespec session_start;
+  struct timespec last_progress;
+  clock_gettime(CLOCK_MONOTONIC, &session_start);
+  last_progress = session_start;
+  if (!receiver_note_status(&session_start, &last_progress, status, file_descriptor, sink))
+    return -1;
   bool early_delete = config_delete_timing_early(config);
   /* Parked keep-set for the late/commit timing.  Every exit path below frees it
      exactly once; the only exception is the successful FINISHED handoff, which
@@ -271,6 +368,8 @@ int receiver_process_pending(Config* config, int file_descriptor, const Receiver
   next_status:
     if (!receive_status(file_descriptor, &status))
       goto receive_error;
+    if (!receiver_note_status(&session_start, &last_progress, status, file_descriptor, sink))
+      goto fail;
   }
   if (status != STATUS_FINISHED) {
     log_message(LOG_LEVEL_ERROR, "Did not receive FINISHED Status");
@@ -353,7 +452,7 @@ static bool receiver_save_file(File* file, void* context_pointer) {
      metadata now and apply it at the end.  -O/--omit-dir-times is honored by
      dir_time_list_apply's caller (see receiver_send_success_frame). */
   if (result != FILE_SAVE_ERROR && file->is_dir && file->metadata &&
-      context->config->use_metadata && !context->config->omit_dir_times &&
+      dir_times_should_capture(context->config) &&
       !dir_time_list_add(&context->dir_times, file->path, file->metadata)) {
     file_destroy(file);
     return false;

src/server/receiver.h

@@ -4,6 +4,8 @@
 #include "config.h"
 #include "file.h"
 #include "file_receive.h"
+#include <stdbool.h>
+#include <time.h>
 
 typedef bool (*ReceiverFileSink)(File* file, void* context);
 
@@ -45,4 +47,22 @@ int receiver_process_pending(Config* config, int file_descriptor, const Receiver
                              DeleteManifest** pending_manifest);
 int receiver_receive_files(Config* config, int file_descriptor);
 
+/* ---- Connection time bounds (anti-slowloris) ----
+ * receiver_process_pending() aborts a connection that makes no forward progress
+ * (only STATUS_KEEPALIVE/STATUS_ABORT frames) beyond a wall-clock idle limit,
+ * and enforces a hard cap on the whole session.  Both are CLOCK_MONOTONIC
+ * deltas, independent of the per-message poll deadline, so a 60 s (or
+ * --timeout) receive window can never reset them.  Defaults are deliberately
+ * generous (see MAX_SESSION_IDLE_SEC / MAX_SESSION_WALL_SEC in receiver.c). */
+
+/* Test seam: override the idle/session wall-clock limits (0 = abort on the
+ * next status).  Always restore with receiver_reset_time_limits(). */
+void receiver_set_time_limits(unsigned int idle_sec, unsigned int wall_sec);
+void receiver_reset_time_limits(void);
+/* Pure predicate over explicit monotonic timestamps, exposed so the bound is
+ * unit-testable without sleeping.  True when either the idle or the overall
+ * session limit has elapsed. */
+bool receiver_time_limit_exceeded(const struct timespec* session_start,
+                                  const struct timespec* last_progress, const struct timespec* now);
+
 #endif

src/server/server.c

@@ -23,7 +23,10 @@
 #include <string.h>
 #include <unistd.h>
 #include <errno.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
 #include <sys/stat.h>
+#include <time.h>
 #include <openssl/x509.h>
 
 static char* authorized_root;
@@ -67,6 +70,11 @@ typedef struct ModuleGateContext {
      activity (operator --no-super, or a daemon module without the
      `client owner = yes` opt-in); -1 when the config's own mode stands. */
   int super_mode_override;
+  /* Numeric peer address (INET6_ADDRSTRLEN is always enough), filled once by
+   * server_module_gate.  has_peer_ip is false when getpeername/inet_ntop could
+   * not classify the peer; an ACL-configured module then fails closed. */
+  bool has_peer_ip;
+  char peer_ip[INET6_ADDRSTRLEN];
 } ModuleGateContext;
 
 /* Server half of the SCRAM challenge/response (A7 remediation, protocol
@@ -251,6 +259,220 @@ static bool configure_authorization(const char* root) {
   return true;
 }
 
+/* Discriminates the outcome of the A7 auth gate so the dispatcher can map it
+ * back to the config_receive_with_validate contract: accepted (including
+ * "module needs no auth"), a config-level refusal carrying an error string, or
+ * a handshake that already wrote its own terminal status frame. */
+typedef enum {
+  MODULE_AUTH_ACCEPTED = 0,
+  MODULE_AUTH_REFUSED,
+  MODULE_AUTH_TERMINATED,
+} ModuleAuthResult;
+
+/* Looks up the daemon module selected by the client's config frame and rejects
+ * a `read only` one (every FastSync network transfer writes; there is no
+ * read-only wire operation yet).  Returns the module, or NULL with *error set
+ * to the caller-facing rejection message. */
+static const DaemonModule* module_gate_lookup_module(const Config* config, const char** error) {
+  const DaemonModule* module = daemon_conf_find_module(g_daemon_conf, config->module);
+  if (module == NULL) {
+    char* escaped_module = output_escape(config->module, config->eight_bit_output);
+    log_message(LOG_LEVEL_ERROR, "unknown daemon module '%s' requested",
+                escaped_module ? escaped_module : "<allocation failed>");
+    free(escaped_module);
+    *error = "requested daemon module does not exist";
+    return NULL;
+  }
+  if (module->read_only) {
+    log_message(LOG_LEVEL_ERROR, "daemon module '%s' is read only; refusing write transfer",
+                config->module);
+    *error = "requested daemon module is read only";
+    return NULL;
+  }
+  return module;
+}
+
+/* Per-module client-chosen ownership / super-user policy (P7 Wave E hardening):
+ * a daemon module refuses EVERY ownership-affecting request (--numeric-ids,
+ * --chown, --usermap/--groupmap, --fake-super, --copy-as, explicit --super)
+ * unless the operator opted THIS module in with `client owner = yes`.
+ * Otherwise any client could force arbitrary ownership inside the module root.
+ * The ownership check is evaluated against the ORIGINAL config so an explicit
+ * --super is refused even when an operator --no-super veto already forced the
+ * effective copy to OFF (the veto must not silently convert a refusal into an
+ * accept); when no ownership flag is present, super-user DEVICE activities are
+ * forced off for this connection instead.  Returns an error string on refusal,
+ * NULL on acceptance. */
+static const char* module_gate_check_ownership(const Config* config, const DaemonModule* module,
+                                               ModuleGateContext* gate_ctx) {
+  if (module->client_owner)
+    return NULL;
+  /* Ownership: refuse the whole transfer up front (a clear failure). */
+  if (identity_ownership_requested(config)) {
+    log_message(LOG_LEVEL_ERROR,
+                "daemon module '%s' refuses client-chosen ownership/super-user activities "
+                "(no `client owner = yes` opt-in); refusing",
+                config->module);
+    return "client-chosen ownership is not permitted by this daemon module";
+  }
+  /* Super-user DEVICE activities (char/block mknod and --write-devices) are
+     permitted under the default AUTO mode, so without this override a root
+     daemon would still let a non-opted module create arbitrary device nodes
+     and write raw devices.  Force them off for this connection: those entries
+     are skipped (never mknod'ed) while an ordinary `-a` push still succeeds
+     without device nodes, matching the operator's least-privilege choice.
+     The operator-level --no-super veto is already folded into this. */
+  if (gate_ctx)
+    gate_ctx->super_mode_override = SUPER_MODE_OFF;
+  return NULL;
+}
+
+/* Online-guessing throttle: sleep the configured `auth failure delay`
+ * milliseconds after a failed authentication.  Runs in the per-connection
+ * forked child, so it never blocks the accept loop or another connection.  0
+ * disables it; the parser already caps it at DAEMON_CONF_MAX_AUTH_FAILURE_DELAY_MS.
+ * Resumes after EINTR so a signal cannot cut the delay short. */
+static void daemon_auth_failure_delay(void) {
+  if (!g_daemon_conf || g_daemon_conf->global.auth_failure_delay_ms <= 0)
+    return;
+  int ms = g_daemon_conf->global.auth_failure_delay_ms;
+  struct timespec delay;
+  delay.tv_sec = ms / 1000;
+  delay.tv_nsec = (long)(ms % 1000) * 1000000L;
+  while (nanosleep(&delay, &delay) != 0 && errno == EINTR)
+    ;
+}
+
+/* Host access control (global then per-module).  A configured list makes an
+ * unprovable peer fail closed.  Deny always takes precedence over allow, and a
+ * non-empty allow list rejects a peer that matches none of its entries.  The
+ * audit line names the peer, the module and the outcome.  Returns an
+ * error string on refusal, NULL on acceptance. */
+static const char* module_gate_check_hosts(const Config* config, const DaemonModule* module,
+                                           ModuleGateContext* gate_ctx) {
+  bool global_restricted = daemon_hosts_restricted(
+      g_daemon_conf->global.hosts_allow, g_daemon_conf->global.hosts_allow_count,
+      g_daemon_conf->global.hosts_deny, g_daemon_conf->global.hosts_deny_count);
+  bool module_restricted = daemon_hosts_restricted(module->hosts_allow, module->hosts_allow_count,
+                                                   module->hosts_deny, module->hosts_deny_count);
+  if (!global_restricted && !module_restricted)
+    return NULL;
+  if (!gate_ctx || !gate_ctx->has_peer_ip) {
+    log_message(LOG_LEVEL_WARNING,
+                "daemon module '%s': cannot determine peer address with host ACLs configured; "
+                "refusing (fail closed)",
+                config->module);
+    return "cannot verify the client host against host access controls";
+  }
+  const char* peer = gate_ctx->peer_ip;
+  if (global_restricted && !daemon_hosts_allowed(peer, g_daemon_conf->global.hosts_allow,
+                                                 g_daemon_conf->global.hosts_allow_count,
+                                                 g_daemon_conf->global.hosts_deny,
+                                                 g_daemon_conf->global.hosts_deny_count)) {
+    log_message(LOG_LEVEL_WARNING,
+                "daemon module '%s': peer %s denied by global 'hosts allow'/'hosts deny'; "
+                "refusing",
+                config->module, peer);
+    return "client host is not permitted by this daemon";
+  }
+  if (module_restricted &&
+      !daemon_hosts_allowed(peer, module->hosts_allow, module->hosts_allow_count,
+                            module->hosts_deny, module->hosts_deny_count)) {
+    log_message(LOG_LEVEL_WARNING,
+                "daemon module '%s': peer %s denied by module 'hosts allow'/'hosts deny'; "
+                "refusing",
+                config->module, peer);
+    return "client host is not permitted by this daemon module";
+  }
+  return NULL;
+}
+
+/* A7 auth gate: runs the SCRAM challenge/response for an auth-required module
+ * BEFORE the module root is installed and before any data moves.  Returns
+ * MODULE_AUTH_ACCEPTED when the module needs no auth or the handshake succeeds,
+ * MODULE_AUTH_REFUSED with *error set on a config-level rejection, or
+ * MODULE_AUTH_TERMINATED when the handshake already wrote a terminal status. */
+static ModuleAuthResult module_gate_authenticate(const Config* config, const DaemonModule* module,
+                                                 ModuleGateContext* gate_ctx, const char** error) {
+  if (module->auth_user_count == 0)
+    return MODULE_AUTH_ACCEPTED;
+  /* Fail closed: no store -> refuse (server misconfiguration, STATUS_ERROR). */
+  if (g_credentials == NULL) {
+    log_message(LOG_LEVEL_ERROR,
+                "daemon module '%s' requires authentication but no credential store is "
+                "configured (--password-file/--early-input); refusing",
+                config->module);
+    *error = "requested daemon module requires authentication and no credential "
+             "store is configured";
+    return MODULE_AUTH_REFUSED;
+  }
+  /* Transport policy (A7-3/S1): an auth-required module only accepts
+   * credentials over (a) an encrypted, verified TLS connection whose client
+   * certificate matches --client-cn, or (b) an actual PLAINTEXT connection
+   * from a loopback peer that the operator explicitly opted into with
+   * --allow-unauthenticated.  A remote plaintext peer, an un-flagged loopback
+   * plaintext peer, and a loopback TLS peer whose certificate does not match
+   * --client-cn are all refused HERE, before the challenge is sent, so an
+   * unverified client never receives a nonce: the loopback allowance requires
+   * !gate_ctx->ssl, so --tls + --allow-unauthenticated can never be used to
+   * bypass the client-CN check.  The operator flag never permits REMOTE
+   * plaintext auth: remote peers still require verified TLS regardless. */
+  bool tls_ok = gate_ctx && gate_ctx->ssl && SSL_get_verify_result(gate_ctx->ssl) == X509_V_OK &&
+                tls_client_identity_allowed(gate_ctx->ssl);
+  bool local_ok = allow_unauthenticated && gate_ctx && !gate_ctx->ssl && gate_ctx->fd >= 0 &&
+                  utils_fd_peer_is_local(gate_ctx->fd);
+  if (!tls_ok && !local_ok) {
+    log_message(LOG_LEVEL_ERROR,
+                "daemon module '%s' requires authentication over an encrypted, verified TLS "
+                "connection (or an opted-in loopback plaintext transport); refusing",
+                config->module);
+    *error = "daemon module requires authentication over an encrypted, verified TLS "
+             "connection";
+    return MODULE_AUTH_REFUSED;
+  }
+  /* Belt-and-braces: the transport policy above already guarantees a context
+   * with a usable socket (verified TLS implies a live SSL object and loopback
+   * allowance requires gate_ctx->fd >= 0), so this is unreachable today; keep
+   * the guard so the handshake can never be driven over an invalid fd. */
+  if (!gate_ctx || gate_ctx->fd < 0) {
+    log_message(LOG_LEVEL_ERROR, "daemon module '%s': no auth transport available", config->module);
+    *error = "authentication failed for the requested daemon module";
+    return MODULE_AUTH_REFUSED;
+  }
+  /* The handshake writes exactly one terminal status on failure and signals so
+   * via MODULE_AUTH_TERMINATED; the username may be logged (never the password
+   * or any derived proof). */
+  if (!server_auth_handshake(gate_ctx->fd, config, module)) {
+    const char* peer = gate_ctx->has_peer_ip ? gate_ctx->peer_ip : "unknown";
+    char* escaped_user =
+        config->auth_user ? output_escape(config->auth_user, config->eight_bit_output) : NULL;
+    log_message(LOG_LEVEL_WARNING,
+                "daemon module '%s': authentication failed for user '%s' from %s; refusing",
+                config->module, escaped_user ? escaped_user : "(none)", peer);
+    free(escaped_user);
+    /* Rate-limit online guessing per connection (no delay on success). */
+    daemon_auth_failure_delay();
+    return MODULE_AUTH_TERMINATED;
+  }
+  char* escaped_user = output_escape(config->auth_user, config->eight_bit_output);
+  log_message(LOG_LEVEL_INFO, "daemon module '%s': user '%s' from %s authenticated", config->module,
+              escaped_user ? escaped_user : "<allocation failed>",
+              gate_ctx->has_peer_ip ? gate_ctx->peer_ip : "unknown");
+  free(escaped_user);
+  return MODULE_AUTH_ACCEPTED;
+}
+
+/* Installs the module's configured path as the connection's authorized root.
+ * Returns an error string when the root is unusable, NULL on success. */
+static const char* module_gate_install_root(const Config* config, const DaemonModule* module) {
+  if (!configure_authorization(module->path)) {
+    log_message(LOG_LEVEL_ERROR, "daemon module '%s' path '%s' is not usable", config->module,
+                module->path ? module->path : "(null)");
+    return "requested daemon module root is not usable";
+  }
+  return NULL;
+}
+
 /* Config-frame gate (runs inside config_receive_with_validate, BEFORE the
  * STATUS_OK ack, so a rejected connection is refused at the config handshake
  * and no file data is ever exchanged).
@@ -324,115 +546,36 @@ static const char* server_module_gate(const Config* config, void* context) {
     return "daemon connection did not select a module (expected a "
            "host::module/path destination)";
 
-  const DaemonModule* module = daemon_conf_find_module(g_daemon_conf, config->module);
-  if (module == NULL) {
-    char* escaped_module = output_escape(config->module, config->eight_bit_output);
-    log_message(LOG_LEVEL_ERROR, "unknown daemon module '%s' requested",
-                escaped_module ? escaped_module : "<allocation failed>");
-    free(escaped_module);
-    return "requested daemon module does not exist";
+  const char* error = NULL;
+  const DaemonModule* module = module_gate_lookup_module(config, &error);
+  if (!module)
+    return error;
+  /* Resolve the peer once, before any auth or ownership work, so the host ACL
+   * and the audit lines all use the same address.  A module with ACLs fails
+   * closed when the peer cannot be classified; an ACL-free module continues
+   * (the accept loop still logged the address). */
+  if (gate_ctx) {
+    gate_ctx->has_peer_ip =
+        utils_fd_peer_ip(gate_ctx->fd, gate_ctx->peer_ip, sizeof(gate_ctx->peer_ip));
+    if (!gate_ctx->has_peer_ip)
+      log_message(LOG_LEVEL_DEBUG, "daemon module '%s': peer address unavailable", config->module);
   }
-  if (module->read_only) {
-    log_message(LOG_LEVEL_ERROR, "daemon module '%s' is read only; refusing write transfer",
-                config->module);
-    return "requested daemon module is read only";
-  }
-  /* Client-chosen ownership / super-user policy (P7 Wave E hardening): a daemon
-     module refuses EVERY ownership-affecting request (--numeric-ids, --chown,
-     --usermap/--groupmap, --fake-super, --copy-as, explicit --super) unless the
-     operator opted THIS module in with `client owner = yes`.  Otherwise any
-     client could force arbitrary ownership inside the module root.  The
-     standalone/SSH server has a single operator-authorized root and keeps
-     honoring these. */
-  if (!module->client_owner) {
-    /* Ownership: refuse the whole transfer up front (a clear failure).
-       Evaluated against the ORIGINAL config so an explicit --super is refused
-       even when an operator --no-super veto already forced the effective copy
-       to OFF (the veto must not silently convert a refusal into an accept). */
-    if (identity_ownership_requested(config)) {
-      log_message(LOG_LEVEL_ERROR,
-                  "daemon module '%s' refuses client-chosen ownership/super-user activities "
-                  "(no `client owner = yes` opt-in); refusing",
-                  config->module);
-      return "client-chosen ownership is not permitted by this daemon module";
-    }
-    /* Super-user DEVICE activities (char/block mknod and --write-devices) are
-       permitted under the default AUTO mode, so without this override a root
-       daemon would still let a non-opted module create arbitrary device nodes
-       and write raw devices.  Force them off for this connection: those entries
-       are skipped (never mknod'ed) while an ordinary `-a` push still succeeds
-       without device nodes, matching the operator's least-privilege choice.
-       The operator-level --no-super veto is already folded into this. */
-    if (gate_ctx)
-      gate_ctx->super_mode_override = SUPER_MODE_OFF;
-  }
-  if (module->auth_user_count > 0) {
-    /* Auth-required module (A7, protocol 2.19.0): run the SCRAM challenge/
-     * response BEFORE the module root is installed and before any data moves.
-     * Fail closed: no store -> refuse (server misconfiguration, STATUS_ERROR);
-     * a handshake that fails before the success response writes exactly one
-     * STATUS_AUTH_FAILED before signalling ALREADY_TERMINATED (a failure while
-     * writing the success signature instead just drops the broken connection).
-     * The username may be logged (never the password or any derived proof). */
-    if (g_credentials == NULL) {
-      log_message(LOG_LEVEL_ERROR,
-                  "daemon module '%s' requires authentication but no credential store is "
-                  "configured (--password-file/--early-input); refusing",
-                  config->module);
-      return "requested daemon module requires authentication and no credential "
-             "store is configured";
-    }
-    /* Transport policy (A7-3/S1): an auth-required module only accepts
-     * credentials over (a) an encrypted, verified TLS connection whose client
-     * certificate matches --client-cn, or (b) an actual PLAINTEXT connection
-     * from a loopback peer that the operator explicitly opted into with
-     * --allow-unauthenticated.  A remote plaintext peer, an un-flagged loopback
-     * plaintext peer, and a loopback TLS peer whose certificate does not match
-     * --client-cn are all refused HERE, before the challenge is sent, so an
-     * unverified client never receives a nonce: the loopback allowance requires
-     * !gate_ctx->ssl, so --tls + --allow-unauthenticated can never be used to
-     * bypass the client-CN check.  The operator flag never permits REMOTE
-     * plaintext auth: remote peers still require verified TLS regardless. */
-    bool tls_ok = gate_ctx && gate_ctx->ssl && SSL_get_verify_result(gate_ctx->ssl) == X509_V_OK &&
-                  tls_client_identity_allowed(gate_ctx->ssl);
-    bool local_ok = allow_unauthenticated && gate_ctx && !gate_ctx->ssl && gate_ctx->fd >= 0 &&
-                    utils_fd_peer_is_local(gate_ctx->fd);
-    if (!tls_ok && !local_ok) {
-      log_message(LOG_LEVEL_ERROR,
-                  "daemon module '%s' requires authentication over an encrypted, verified TLS "
-                  "connection (or an opted-in loopback plaintext transport); refusing",
-                  config->module);
-      return "daemon module requires authentication over an encrypted, verified TLS "
-             "connection";
-    }
-    /* Belt-and-braces: the transport policy above already guarantees a context
-     * with a usable socket (verified TLS implies a live SSL object and loopback
-     * allowance requires gate_ctx->fd >= 0), so this is unreachable today; keep
-     * the guard so the handshake can never be driven over an invalid fd. */
-    if (!gate_ctx || gate_ctx->fd < 0) {
-      log_message(LOG_LEVEL_ERROR, "daemon module '%s': no auth transport available",
-                  config->module);
-      return "authentication failed for the requested daemon module";
-    }
-    if (!server_auth_handshake(gate_ctx->fd, config, module)) {
-      char* escaped_user =
-          config->auth_user ? output_escape(config->auth_user, config->eight_bit_output) : NULL;
-      log_message(LOG_LEVEL_ERROR, "daemon module '%s': authentication failed for user '%s'",
-                  config->module, escaped_user ? escaped_user : "(none)");
-      free(escaped_user);
+  error = module_gate_check_hosts(config, module, gate_ctx);
+  if (error)
+    return error;
+  error = module_gate_check_ownership(config, module, gate_ctx);
+  if (error)
+    return error;
+  switch (module_gate_authenticate(config, module, gate_ctx, &error)) {
+  case MODULE_AUTH_REFUSED:
+    return error;
+  case MODULE_AUTH_TERMINATED:
     return CONFIG_VALIDATE_ALREADY_TERMINATED;
+  case MODULE_AUTH_ACCEPTED:
+    break;
   }
-    char* escaped_user = output_escape(config->auth_user, config->eight_bit_output);
-    log_message(LOG_LEVEL_INFO, "daemon module '%s': user '%s' authenticated", config->module,
-                escaped_user ? escaped_user : "<allocation failed>");
-    free(escaped_user);
-  }
-  if (!configure_authorization(module->path)) {
-    log_message(LOG_LEVEL_ERROR, "daemon module '%s' path '%s' is not usable", config->module,
-                module->path ? module->path : "(null)");
-    return "requested daemon module root is not usable";
-  }
-  return NULL; /* accepted; authorized root is now the module's path */
+  /* accepted; the authorized root is now the module's path */
+  return module_gate_install_root(config, module);
 }
 
 void handler(int file_descriptor) {
@@ -445,12 +588,18 @@ void handler(int file_descriptor) {
   gate_ctx.ssl = ssl;
   gate_ctx.fd = file_descriptor;
   gate_ctx.super_mode_override = -1;
-  Config* config = config_receive_with_validate(file_descriptor, server_module_gate, &gate_ctx);
+  gate_ctx.has_peer_ip = false;
+  gate_ctx.peer_ip[0] = '\0';
+  /* All teardown state starts empty so the single `done` epilogue is safe to
+   * reach from any error path (including before the config frame arrives). */
+  Config* config = NULL;
+  PipelineContextReceiver* context = NULL;
+  char* joined_destination = NULL;
+  bool charset_ready = false;
+  config = config_receive_with_validate(file_descriptor, server_module_gate, &gate_ctx);
   if (config == NULL) {
     log_message(LOG_LEVEL_ERROR, "Failed to receive config");
-    close(file_descriptor);
-    protocol_session_unbind();
-    return;
+    goto done;
   }
   /* Apply the super-mode veto the gate decided on (operator --no-super, or a
    * daemon module without the `client owner = yes` opt-in) exactly once, so
@@ -458,27 +607,25 @@ void handler(int file_descriptor) {
    * device-node creation) sees SUPER_MODE_OFF.  The gate never mutated the
    * received config. */
   if (gate_ctx.super_mode_override != -1)
-    config->super_mode = gate_ctx.super_mode_override;
+    config->super_mode = (SuperMode)gate_ctx.super_mode_override;
   protocol_set_8_bit_output(config->eight_bit_output);
+  /* Server-side per-message protocol deadline for every frame from here on.
+   * `timeout` is not serialized, so this is the server's own config (the server
+   * has no --timeout CLI and defaults it to 0): the built-in 60 s window stays
+   * in effect.  A client's --timeout tightens only that client's own protocol
+   * I/O and the server's socket read/write timeout is the transport default. */
+  protocol_session_set_io_timeout(&session, config->timeout);
   if (!authorized_root) {
     log_message(LOG_LEVEL_ERROR, "No server-side destination root configured");
-    config_delete(config);
-    close(file_descriptor);
-    protocol_session_unbind();
-    return;
+    goto done;
   }
   if (!allow_unauthenticated && ssl == NULL) {
     log_message(LOG_LEVEL_ERROR, "Rejected unauthenticated plaintext connection");
-    config_delete(config);
-    close(file_descriptor);
-    protocol_session_unbind();
-    return;
+    goto done;
   }
   if (ssl && required_client_cn && !tls_client_identity_allowed(ssl)) {
     log_message(LOG_LEVEL_ERROR, "Rejected TLS client with unauthorized identity");
-    config_delete(config);
-    close(file_descriptor);
-    return;
+    goto done;
   }
   /* Daemon mode: the module's root is the authorized root (installed by
      server_module_gate), and the client's destination is a MODULE-RELATIVE
@@ -488,13 +635,9 @@ void handler(int file_descriptor) {
   if (g_daemon_conf && config->receive_root_directory && config->receive_root_directory[0] == '/') {
     log_message(LOG_LEVEL_ERROR, "Rejected absolute daemon destination (must be relative to the "
                                  "selected module root)");
-    config_delete(config);
-    close(file_descriptor);
-    protocol_session_unbind();
-    return;
+    goto done;
   }
   char* destination = config->receive_root_directory;
-  char* joined_destination = NULL;
   if (destination && destination[0] != '/')
     joined_destination = path_cat(authorized_root, destination);
   if (joined_destination)
@@ -503,19 +646,16 @@ void handler(int file_descriptor) {
       !path_is_within(authorized_root, destination)) {
     log_message(LOG_LEVEL_ERROR, "Rejected destination outside authorized root");
     free(joined_destination);
-    config_delete(config);
-    close(file_descriptor);
-    return;
+    joined_destination = NULL;
+    goto done;
   }
   if (joined_destination) {
     free(config->receive_root_directory);
     config->receive_root_directory = joined_destination;
+    joined_destination = NULL;
   }
   if (!config->receive_root_directory) {
-    config_delete(config);
-    close(file_descriptor);
-    protocol_session_unbind();
-    return;
+    goto done;
   }
   config->use_delete = config->use_delete && allow_delete;
   /* --iconv (protocol 2.16.0): install the receiver-side wire->local conversion
@@ -524,13 +664,13 @@ void handler(int file_descriptor) {
      any) may override the local charset; a spec the client is known to have
      validated cannot fail here unless the server's override names an
      unsupported charset. */
-  if (config->iconv_spec && !charset_wire_init_receiver(config->iconv_spec, server_iconv_spec)) {
+  if (config->iconv_spec) {
+    if (!charset_wire_init_receiver(config->iconv_spec, server_iconv_spec)) {
       log_message(LOG_LEVEL_ERROR,
                   "--iconv: unsupported charset conversion requested (LOCAL[,REMOTE])");
-    config_delete(config);
-    close(file_descriptor);
-    protocol_session_unbind();
-    return;
+      goto done;
+    }
+    charset_ready = true;
   }
   /* --delete-missing-args deletes destination mirrors receiver-side, so it is
      deletion and stays gated by the same --allow-delete server policy.  When
@@ -545,10 +685,7 @@ void handler(int file_descriptor) {
     log_message(LOG_LEVEL_ERROR, "destination root is not available: %s",
                 escaped_root ? escaped_root : "<allocation failed>");
     free(escaped_root);
-    config_delete(config);
-    close(file_descriptor);
-    protocol_session_unbind();
-    return;
+    goto done;
   }
   /* A --delay-updates transfer stages under a private 0700 directory inside
      the receive root.  Create it up front (wiping leftovers of any previously
@@ -557,11 +694,7 @@ void handler(int file_descriptor) {
     config->delay_context = delay_updates_context_create(config->receive_root_directory);
     if (!config->delay_context || !delay_updates_prepare(config->delay_context)) {
       log_message(LOG_LEVEL_ERROR, "Failed to initialize --delay-updates staging area");
-      delay_updates_cleanup(config->delay_context);
-      config_delete(config);
-      close(file_descriptor);
-      protocol_session_unbind();
-      return;
+      goto done;
     }
   }
   /* Preserve the negotiated identity policy for the fd-relative ownership
@@ -571,10 +704,7 @@ void handler(int file_descriptor) {
      rather than silently applying the wrong ownership policy. */
   if (!identity_set_active(config)) {
     log_message(LOG_LEVEL_ERROR, "Failed to activate identity policy");
-    config_delete(config);
-    close(file_descriptor);
-    protocol_session_unbind();
-    return;
+    goto done;
   }
   /* Persist the negotiated --keep-dirlinks policy once, here at config-accept,
      before any multithreaded receiver/writer threads are spawned, so the
@@ -605,38 +735,26 @@ void handler(int file_descriptor) {
     if (!motd_send(file_descriptor, motd ? motd : "")) {
       free(motd);
       log_message(LOG_LEVEL_ERROR, "Failed to send daemon MOTD");
-      config_delete(config);
-      close(file_descriptor);
-      protocol_session_unbind();
-      identity_clear_active();
-      return;
+      goto done;
     }
     free(motd);
   }
   if (config->use_multithreading) {
     Queue* q = queue_create(100, file_destroy);
-    if (q == NULL) {
-      config_delete(config);
-      close(file_descriptor);
-      protocol_session_unbind();
-      identity_clear_active();
-      return;
-    }
-    PipelineContextReceiver* context =
-        pipeline_context_receiver_create(config, q, file_descriptor, ssl);
+    if (q == NULL)
+      goto done;
+    context = pipeline_context_receiver_create(config, q, file_descriptor, ssl);
     if (context == NULL) {
       queue_destroy(q);
-      config_delete(config);
-      close(file_descriptor);
-      protocol_session_unbind();
-      identity_clear_active();
-      return;
+      goto done;
     }
     protocol_session_set_max_alloc(&context->session, config->max_alloc);
+    protocol_session_set_io_timeout(&context->session, config->timeout);
     atomic_store(&context->session.total_allocated_bytes,
                  atomic_load(&session.total_allocated_bytes));
     pipeline_context_receiver_set_queue_byte_limit(context, RECEIVER_QUEUE_MAX_BYTES);
-    thrd_t receiver, writer;
+    thrd_t receiver = {0};
+    thrd_t writer = {0};
     bool receiver_created = thrd_create(&receiver, receive_thread, context) == thrd_success;
     bool writer_created = false;
     if (receiver_created)
@@ -649,17 +767,19 @@ void handler(int file_descriptor) {
         cnd_broadcast(&context->condition_not_full);
         cnd_broadcast(&context->condition_not_empty);
         mtx_unlock(&context->mutex);
-        close(file_descriptor);
+        /* Unblock a worker parked in socket I/O without closing the fd (the
+         * child owns the single close).  shutdown() only affects sockets; for
+         * the --stdio pipe the receiver's per-message poll timeout still
+         * bounds the join, so do nothing there rather than close a descriptor
+         * another thread may still be using. */
+        struct stat fd_stat;
+        if (fstat(file_descriptor, &fd_stat) == 0 && S_ISSOCK(fd_stat.st_mode))
+          shutdown(file_descriptor, SHUT_RDWR);
         thrd_join(receiver, NULL);
-      } else {
-        close(file_descriptor);
       }
       if (writer_created)
         thrd_join(writer, NULL);
-      pipeline_context_receiver_destroy(context);
-      protocol_session_unbind();
-      identity_clear_active();
-      return;
+      goto done;
     }
     int receiver_result;
     int writer_result;
@@ -703,21 +823,36 @@ void handler(int file_descriptor) {
     } else {
       send_status(file_descriptor, STATUS_ERROR);
     }
-    if (!transfer_ok) {
+    if (!transfer_ok)
       log_message(LOG_LEVEL_ERROR, "Transfer failed");
-      if (config->delay_updates && config->delay_context)
-        delay_updates_cleanup(config->delay_context);
-    }
-    pipeline_context_receiver_destroy(context);
   } else {
     if (receiver_receive_files(config, file_descriptor) != 0)
       log_message(LOG_LEVEL_ERROR, "Transfer failed");
-    config_delete(config);
   }
-  protocol_session_unbind();
-  identity_clear_active();
+
+done:
+  /* Single cleanup epilogue: every error path jumps here, so the iconv
+   * receiver conversion is released, the identity snapshot cleared, the
+   * protocol session unbound and the config freed exactly once.  The
+   * connection fd is deliberately NOT closed here -- the child functions own
+   * its single close (plain_child_fn / tls_child_fn), and the --stdio call
+   * site must leave stdin/stdout open. */
+  if (charset_ready)
     charset_wire_free();
-  close(file_descriptor);
+  /* The delay-updates staging tree is released by config_delete (which the
+     branch below always reaches), so it is cleaned exactly once. */
+  identity_clear_active();
+  protocol_session_unbind();
+  if (context != NULL) {
+    /* context owns both the config and the queue it was created with. */
+    pipeline_context_receiver_destroy(context);
+    context = NULL;
+    config = NULL;
+  } else {
+    config_delete(config);
+    config = NULL;
+  }
+  free(joined_destination);
 }
 
 #ifndef FASTSYNC_SERVER_AS_LIB
@@ -744,7 +879,8 @@ static void print_server_usage(void) {
   printf("  --config=FILE       Daemon config file (default: ~/.config/fastsync/\n");
   printf("                      fastsyncd.conf, else /etc/fastsyncd.conf)\n");
   printf("  --dparam=KEY=VALUE  Override one global config key on the command line\n");
-  printf("                      (port, motd file, address)\n");
+  printf("                      (port, motd file, address, max connections,\n");
+  printf("                      auth failure delay, hosts allow, hosts deny)\n");
   printf("  --no-detach         Stay in the foreground (default detaches to\n");
   printf("                      background when running --daemon)\n");
   printf("  --password-file=FILE  Credential store for modules that declare\n");
@@ -912,6 +1048,9 @@ int main(int argc, char* argv[]) {
       return 1;
     }
     io_set_fds(STDIN_FILENO, STDOUT_FILENO);
+    /* handler() does not own the stdio fds: it never closes its descriptor
+     * argument, so STDIN/STDOUT stay open for this (single-shot) SSH session
+     * and are released by process exit. */
     handler(STDIN_FILENO);
     release_authorization();
     server_cli_options_free(&opts);
@@ -956,6 +1095,12 @@ int main(int argc, char* argv[]) {
                     "and device nodes within that module root -- pair it with `auth users` "
                     "unless the module is intentionally open to the network",
                     g_daemon_conf->modules[i].name);
+      if (g_daemon_conf->modules[i].max_connections > 0)
+        log_message(LOG_LEVEL_WARNING,
+                    "daemon module '%s': per-module 'max connections' is stored but not enforced "
+                    "per module; the global 'max connections' cap (%d) applies to the whole "
+                    "listener",
+                    g_daemon_conf->modules[i].name, g_daemon_conf->global.max_connections);
     }
     /* Daemon credential store (Wave B).  --password-file and --early-input
      * feed the same store, loaded BEFORE the listener forks so every
@@ -1020,6 +1165,8 @@ int main(int argc, char* argv[]) {
     exit_code = 1;
     goto out;
   }
+  if (g_daemon_conf)
+    server_set_max_connections(g_server, (unsigned int)g_daemon_conf->global.max_connections);
   if (opts.use_tls) {
     if (!opts.tls_cert || !opts.tls_key || !opts.tls_ca || !opts.client_cn) {
       fprintf(stderr, "Error: --tls requires --cert, --key, --ca, and --client-cn\n");

src/shared/array_list.c

@@ -1,6 +1,7 @@
 #include "log.h"
 #include "array_list.h"
 #include "protocol.h"
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -39,6 +40,8 @@ void array_list_delete(ArrayList* array_list) {
 static bool array_list_extend(ArrayList* array_list) {
   if (array_list == NULL)
     return false;
+  if (array_list->capacity > INT_MAX / 2)
+    return false;
   int new_capacity = array_list->capacity * 2;
   if (new_capacity == 0)
     new_capacity = INITIAL_ARRAY_SIZE;

src/shared/config.c

@@ -67,7 +67,11 @@ static void config_set_defaults(Config* config) {
   config->tls_ca = NULL;
   config->server_host = str_dup("127.0.0.1");
   config->server_port = 8080;
-  config->timeout = 30;
+  /* 0 means "--timeout not given": the transport keeps its own built-in 30 s
+   * socket timeout (tcp_set_timeouts ignores non-positive values) and the
+   * protocol layer keeps its built-in 60 s per-message deadline.  A positive
+   * value overrides BOTH (see protocol_session_set_io_timeout). */
+  config->timeout = 0;
   config->contimeout = 10;
   config->quiet = false;
   config->backup = false;
@@ -202,6 +206,51 @@ static bool receive_wire_bool(int fd, bool* value) {
   return true;
 }
 
+/* Cumulative budget for the strings retained by one received Config (see
+ * MAX_CONFIG_STRING_BYTES).  Config strings are received once per connection
+ * before authentication and live for its whole lifetime, so the charge is never
+ * released. */
+typedef struct {
+  unsigned long long used;
+} ConfigStringBudget;
+
+/* Charge `bytes` (the retained allocation: string body plus NUL) against the
+ * aggregate config-string budget.  Returns false when the ceiling would be
+ * exceeded, letting the caller reject the frame with a clear error instead of
+ * retaining unbounded pre-auth memory. */
+static bool config_string_budget_charge(ConfigStringBudget* budget, size_t bytes) {
+  if ((unsigned long long)bytes > MAX_CONFIG_STRING_BYTES ||
+      budget->used > MAX_CONFIG_STRING_BYTES - (unsigned long long)bytes) {
+    log_message(LOG_LEVEL_ERROR, "Config string budget exceeded (%llu + %zu > %llu bytes)",
+                budget->used, bytes, (unsigned long long)MAX_CONFIG_STRING_BYTES);
+    return false;
+  }
+  budget->used += (unsigned long long)bytes;
+  return true;
+}
+
+static char* config_receive_str(int fd, ConfigStringBudget* budget) {
+  char* value = receive_str(fd);
+  if (!value)
+    return NULL;
+  if (!config_string_budget_charge(budget, strlen(value) + 1)) {
+    free(value);
+    return NULL;
+  }
+  return value;
+}
+
+static char* config_receive_str_redacted(int fd, ConfigStringBudget* budget) {
+  char* value = receive_str_redacted(fd);
+  if (!value)
+    return NULL;
+  if (!config_string_budget_charge(budget, strlen(value) + 1)) {
+    free(value);
+    return NULL;
+  }
+  return value;
+}
+
 static bool validate_received_config(const Config* config) {
   return valid_wire_bool(config->save_to_disk) && valid_wire_bool(config->use_multithreading) &&
          valid_wire_bool(config->use_chunk_serialization) &&
@@ -257,7 +306,7 @@ static bool validate_received_config(const Config* config) {
          config->delta_block_size <= DELTA_BLOCK_SIZE_MAX &&
          config->delta_max_file_size <= DELTA_MAX_FILE_SIZE && config->modify_window >= 0 &&
          config->max_delete >= -1 && config->skip_compress_count >= 0 &&
-         config->skip_compress_count <= 10000 && config->max_alloc > 0 &&
+         config->skip_compress_count <= MAX_SKIP_COMPRESS_SUFFIXES && config->max_alloc > 0 &&
          (!config->chmod_spec || !*config->chmod_spec ||
           chmod_apply(0, config->chmod_spec, &(mode_t){0})) &&
          /* The received --iconv CONVERT_SPEC is untrusted input that drives
@@ -648,6 +697,9 @@ void config_delete(Config* config) {
   if (config == NULL)
     return;
   if (config->log_file) {
+    /* The logging subsystem borrows this FILE*; detach it before closing so a
+     * concurrent log call can never touch the freed handle. */
+    log_set_file(NULL);
     fclose(config->log_file);
     config->log_file = NULL;
   }
@@ -819,7 +871,7 @@ static bool send_checksum_options(int fd, const Config* c) {
          send_n_data(fd, &c->checksum_seed, sizeof(c->checksum_seed));
 }
 
-static bool receive_core_fields(int fd, Config* c) {
+static bool receive_core_fields(int fd, Config* c, ConfigStringBudget* budget) {
   int value;
   if (!receive_wire_bool(fd, &c->eight_bit_output))
     return false;
@@ -829,8 +881,8 @@ static bool receive_core_fields(int fd, Config* c) {
   if (c->max_alloc > MAX_SERVER_ALLOC)
     c->max_alloc = MAX_SERVER_ALLOC;
   protocol_session_set_max_alloc(NULL, c->max_alloc);
-  c->send_directory = receive_str(fd);
-  c->receive_root_directory = receive_str(fd);
+  c->send_directory = config_receive_str(fd, budget);
+  c->receive_root_directory = config_receive_str(fd, budget);
   if (!c->send_directory || !c->receive_root_directory)
     return false;
   if (!receive_wire_bool(fd, &c->save_to_disk) || !receive_wire_bool(fd, &c->use_multithreading) ||
@@ -863,10 +915,10 @@ static bool receive_delta_fields(int fd, Config* c) {
          receive_n_data(fd, &c->delta_max_file_size, sizeof(unsigned long long));
 }
 
-static bool receive_file_options(int fd, Config* c) {
+static bool receive_file_options(int fd, Config* c, ConfigStringBudget* budget) {
   if (!receive_wire_bool(fd, &c->backup))
     return false;
-  char* backup_dir = receive_str(fd);
+  char* backup_dir = config_receive_str(fd, budget);
   if (!backup_dir)
     return false;
   if (*backup_dir != '\0') {
@@ -920,8 +972,8 @@ static bool receive_selection_options(int fd, Config* c) {
   return receive_wire_bool(fd, &c->delete_delay);
 }
 
-static bool receive_resume_options(int fd, Config* c) {
-  char* temp_dir = receive_str(fd);
+static bool receive_resume_options(int fd, Config* c, ConfigStringBudget* budget) {
+  char* temp_dir = config_receive_str(fd, budget);
   if (!temp_dir)
     return false;
   if (*temp_dir != '\0') {
@@ -935,7 +987,7 @@ static bool receive_resume_options(int fd, Config* c) {
      string for "unset".  Canonicalize the empty wire value back to NULL so
      receivers observe exactly what the client configured (plain --backup, for
      example, must not look like --backup-dir ""). */
-  char* partial_dir = receive_str(fd);
+  char* partial_dir = config_receive_str(fd, budget);
   if (!partial_dir)
     return false;
   if (*partial_dir != '\0') {
@@ -943,7 +995,7 @@ static bool receive_resume_options(int fd, Config* c) {
   } else {
     free(partial_dir);
   }
-  char* suffix = receive_str(fd);
+  char* suffix = config_receive_str(fd, budget);
   if (!suffix)
     return false;
   if (*suffix != '\0') {
@@ -957,20 +1009,20 @@ static bool receive_resume_options(int fd, Config* c) {
     return false;
   if (!receive_n_data(fd, &c->modify_window, sizeof(c->modify_window)))
     return false;
-  c->compress_choice = receive_str(fd);
+  c->compress_choice = config_receive_str(fd, budget);
   if (!c->compress_choice)
     return false;
-  c->chmod_spec = receive_str(fd);
+  c->chmod_spec = config_receive_str(fd, budget);
   if (!c->chmod_spec || !receive_wire_bool(fd, &c->skip_compress_set) ||
       !receive_int(fd, &c->skip_compress_count) || c->skip_compress_count < 0 ||
-      c->skip_compress_count > 10000)
+      c->skip_compress_count > MAX_SKIP_COMPRESS_SUFFIXES)
     return false;
   if (c->skip_compress_count > 0) {
     c->skip_compress_suffixes = calloc((size_t)c->skip_compress_count, sizeof(char*));
     if (!c->skip_compress_suffixes)
       return false;
     for (int i = 0; i < c->skip_compress_count; i++) {
-      c->skip_compress_suffixes[i] = receive_str(fd);
+      c->skip_compress_suffixes[i] = config_receive_str(fd, budget);
       if (!c->skip_compress_suffixes[i])
         return false;
     }
@@ -978,7 +1030,7 @@ static bool receive_resume_options(int fd, Config* c) {
   return true;
 }
 
-static bool receive_basis_options(int fd, Config* c) {
+static bool receive_basis_options(int fd, Config* c, ConfigStringBudget* budget) {
   int count;
   if (!receive_int(fd, &count))
     return false;
@@ -988,7 +1040,7 @@ static bool receive_basis_options(int fd, Config* c) {
     int type;
     if (!receive_int(fd, &type) || type <= BASIS_DEST_NONE || type > BASIS_DEST_LINK)
       return false;
-    char* path = receive_str(fd);
+    char* path = config_receive_str(fd, budget);
     if (!path)
       return false;
     /* config_basis_append validates and canonicalizes the path; a rejected
@@ -1119,8 +1171,8 @@ static bool send_daemon_module(int fd, const Config* c) {
   return send_str(fd, c->module ? c->module : "");
 }
 
-static bool receive_daemon_module(int fd, Config* c) {
-  char* module = receive_str(fd);
+static bool receive_daemon_module(int fd, Config* c, ConfigStringBudget* budget) {
+  char* module = config_receive_str(fd, budget);
   if (!module)
     return false;
   /* Guard against a hostile client flooding the log with an over-long module
@@ -1155,14 +1207,14 @@ static bool send_daemon_auth(int fd, const Config* c) {
   return send_str_redacted(fd, c->auth_user);
 }
 
-static bool receive_daemon_auth(int fd, Config* c) {
+static bool receive_daemon_auth(int fd, Config* c, ConfigStringBudget* budget) {
   int present;
   if (!receive_int(fd, &present) || !valid_wire_bool(present))
     return false;
   if (!present)
     return true;
   /* Redacted receive: never log the incoming username body. */
-  char* user = receive_str_redacted(fd);
+  char* user = config_receive_str_redacted(fd, budget);
   if (!user)
     return false;
   if (!credentials_username_valid(user)) {
@@ -1272,8 +1324,8 @@ static bool send_iconv_spec(int fd, const Config* c) {
   return send_str(fd, c->iconv_spec ? c->iconv_spec : "");
 }
 
-static bool receive_iconv_spec(int fd, Config* c) {
-  char* spec = receive_str(fd);
+static bool receive_iconv_spec(int fd, Config* c, ConfigStringBudget* budget) {
+  char* spec = config_receive_str(fd, budget);
   if (!spec)
     return false;
   if (*spec == '\0') {
@@ -1293,14 +1345,14 @@ static bool receive_iconv_spec(int fd, Config* c) {
  * validated to the SUPER_MODE_AUTO..SUPER_MODE_OFF range (also re-checked by
  * validate_received_config). */
 static bool send_privilege_options(int fd, const Config* c) {
-  return send_int(fd, c->super_mode);
+  return send_int(fd, (int)c->super_mode);
 }
 
 static bool receive_privilege_options(int fd, Config* c) {
   int mode;
   if (!receive_int(fd, &mode) || mode < SUPER_MODE_AUTO || mode > SUPER_MODE_OFF)
     return false;
-  c->super_mode = mode;
+  c->super_mode = (SuperMode)mode;
   return true;
 }
 
@@ -1376,47 +1428,48 @@ Config* config_receive_with_validate(int file_descriptor, ConfigValidateFunc val
   Config* config = config_create();
   if (!config)
     return NULL;
+  ConfigStringBudget budget = {0};
   free(config->version);
-  config->version = receive_str(file_descriptor);
+  config->version = config_receive_str(file_descriptor, &budget);
   if (!config->version)
     goto error;
   if (strcmp(config->version, PROTOCOL_VERSION) != 0) {
     char* escaped_version = output_escape(config->version, false);
-    fprintf(stderr, "Protocol version mismatch: client=%s, server=%s\n",
+    log_message(LOG_LEVEL_ERROR, "Protocol version mismatch: client=%s, server=%s",
                 escaped_version ? escaped_version : "<allocation failed>", PROTOCOL_VERSION);
     free(escaped_version);
     send_status(file_descriptor, STATUS_ERROR);
     goto error;
   }
-  if (!receive_core_fields(file_descriptor, config) ||
+  if (!receive_core_fields(file_descriptor, config, &budget) ||
       !receive_delta_fields(file_descriptor, config) ||
-      !receive_file_options(file_descriptor, config) ||
+      !receive_file_options(file_descriptor, config, &budget) ||
       !receive_selection_options(file_descriptor, config) ||
-      !receive_resume_options(file_descriptor, config) ||
-      !receive_basis_options(file_descriptor, config) ||
+      !receive_resume_options(file_descriptor, config, &budget) ||
+      !receive_basis_options(file_descriptor, config, &budget) ||
       !receive_fuzzy_option(file_descriptor, config) ||
       !receive_checksum_options(file_descriptor, config) ||
       !receive_identity_options(file_descriptor, config) ||
       !receive_metadata_times_options(file_descriptor, config) ||
       !receive_symlink_trust_options(file_descriptor, config) ||
       !receive_phase4_xattr_options(file_descriptor, config) ||
-      !receive_daemon_module(file_descriptor, config) ||
-      !receive_daemon_auth(file_descriptor, config) ||
-      !receive_iconv_spec(file_descriptor, config) ||
+      !receive_daemon_module(file_descriptor, config, &budget) ||
+      !receive_daemon_auth(file_descriptor, config, &budget) ||
+      !receive_iconv_spec(file_descriptor, config, &budget) ||
       !receive_privilege_options(file_descriptor, config) ||
       !receive_copy_as_options(file_descriptor, config))
     goto error;
   if (config->compress_choice[0] != '\0' && strcmp(config->compress_choice, "zstd") != 0 &&
       strcmp(config->compress_choice, "none") != 0) {
     char* escaped_choice = output_escape(config->compress_choice, config->eight_bit_output);
-    fprintf(stderr, "Unsupported compression choice: %s\n",
+    log_message(LOG_LEVEL_ERROR, "Unsupported compression choice: %s",
                 escaped_choice ? escaped_choice : "<allocation failed>");
     free(escaped_choice);
     send_status(file_descriptor, STATUS_ERROR);
     goto error;
   }
   if (!validate_received_config(config)) {
-    fprintf(stderr, "Invalid configuration received from client\n");
+    log_message(LOG_LEVEL_ERROR, "Invalid configuration received from client");
     send_status(file_descriptor, STATUS_ERROR);
     goto error;
   }
@@ -1430,7 +1483,7 @@ Config* config_receive_with_validate(int file_descriptor, ConfigValidateFunc val
        * the CONFIG_VALIDATE_ALREADY_TERMINATED sentinel, so no second status is
        * written. */
       if (rejection != CONFIG_VALIDATE_ALREADY_TERMINATED) {
-        fprintf(stderr, "%s\n", rejection);
+        log_message(LOG_LEVEL_ERROR, "%s", rejection);
         send_status(file_descriptor, STATUS_ERROR);
       }
       goto error;

src/shared/config.h

@@ -68,6 +68,13 @@ typedef struct {
   int value;    /* 0/1 for booleans, byte count for SO_RCVBUF/SO_SNDBUF */
 } SockOptEntry;
 
+/* --super / --no-super tri-state (Config->super_mode).  AUTO (default) and ON
+ * both permit a confined super-user attempt (AUTO preserves FastSync's
+ * historical best-effort behavior; an unprivileged attempt is refused by the
+ * kernel and skipped per entry); OFF forbids the attempt even for root.  See
+ * privilege_super_mode_permitted() in identity.h. */
+typedef enum SuperMode { SUPER_MODE_AUTO = 0, SUPER_MODE_ON = 1, SUPER_MODE_OFF = 2 } SuperMode;
+
 typedef struct Config {
   char* version;
   char* send_directory;
@@ -150,7 +157,12 @@ typedef struct Config {
   char* tls_cert;
   char* tls_key;
   char* tls_ca;
+  /* --timeout: per-message I/O deadline in seconds.  0 (the default/unset
+   * sentinel) leaves the transport's built-in 30 s socket timeout and the
+   * protocol's built-in 60 s per-message deadline in place; a positive value
+   * overrides both.  See protocol_session_set_io_timeout. */
   int timeout;
+  /* --contimeout: connect()/accept timeout, transport layer only. */
   int contimeout;
   bool quiet;
   bool backup;
@@ -416,7 +428,7 @@ typedef struct Config {
    * as a trailing int so the receiver can enforce the policy.  See
    * privilege_super_permitted() and identity_ownership_requested() in
    * identity.h. */
-  int super_mode;
+  SuperMode super_mode;
 
   // Receiver-side runtime staging registry for --delay-updates.  Never sent
   // over the wire and never set on the sender side.
@@ -636,6 +648,24 @@ typedef struct Config {
 /* Upper bound on total basis-dir entries (rsync caps --link-dest at 20). */
 #define MAX_BASIS_DIRS 64
 
+/* Upper bound on the number of --skip-compress suffixes accepted from the wire.
+ * Each suffix is an independent wire string (up to MAX_STRING_SIZE = 64 KiB), so
+ * without this a hostile pre-auth client could otherwise retain
+ * skip_count * MAX_STRING_SIZE bytes on the server before authentication; 256
+ * covers any realistic suffix list while keeping the worst case small. */
+#define MAX_SKIP_COMPRESS_SUFFIXES 256
+
+/* Aggregate ceiling on the bytes retained by ALL strings in one received config
+ * frame (version, send/receive roots, backup/temp/partial/suffix, compression
+ * choice, chmod spec, skip-compress suffixes, basis paths, module, auth user,
+ * iconv spec, ...).  The config frame is parsed BEFORE authentication and every
+ * one of these strings lives for the whole connection, so this cumulative
+ * (never released) budget bounds the pre-auth memory a single connection can
+ * pin.  MAX_SKIP_COMPRESS_SUFFIXES / MAX_BASIS_DIRS bound the individual
+ * repeatable counts; this budget bounds their product and any single oversized
+ * field. */
+#define MAX_CONFIG_STRING_BYTES (1ULL * 1024 * 1024)
+
 /* Identity-mapping sentinels and bounds (see identity.h for semantics).
  * IDENTITY_MATCH_ANY is a usermap/groupmap FROM '*' (matches any id);
  * IDENTITY_CURRENT is a chown / map TO '*' (resolve to the receiver's current
@@ -644,15 +674,6 @@ typedef struct Config {
 #define IDENTITY_CURRENT (-1)
 #define MAX_IDENTITY_MAP 128
 
-/* --super / --no-super tri-state (Config->super_mode).  AUTO (default) and ON
- * both permit a confined super-user attempt (AUTO preserves FastSync's
- * historical best-effort behavior; an unprivileged attempt is refused by the
- * kernel and skipped per entry); OFF forbids the attempt even for root.  See
- * privilege_super_mode_permitted() in identity.h. */
-#define SUPER_MODE_AUTO 0
-#define SUPER_MODE_ON 1
-#define SUPER_MODE_OFF 2
-
 Config* config_create(void);
 void config_delete(Config* config);
 

src/shared/daemon_conf.c

@@ -1,8 +1,13 @@
 #include "daemon_conf.h"
+#include "credentials.h"
 #include "utils.h"
+#include <arpa/inet.h>
 #include <ctype.h>
 #include <errno.h>
+#include <limits.h>
+#include <netinet/in.h>
 #include <stdarg.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -48,6 +53,158 @@ static bool parse_bool_value(const char* value, bool* out) {
   return false;
 }
 
+/* Parse an IPv4/IPv6 CIDR "addr/prefix" into `bytes`/`*family`.  Returns false
+ * for a malformed address, a missing/oversized prefix, or a prefix that does
+ * not fit the address family. */
+static bool parse_cidr(const char* cidr, int* prefix_out, uint8_t* bytes, int* family_out) {
+  const char* slash = strchr(cidr, '/');
+  if (!slash)
+    return false;
+  size_t addr_len = (size_t)(slash - cidr);
+  if (addr_len == 0 || addr_len >= INET6_ADDRSTRLEN)
+    return false;
+  char addr[INET6_ADDRSTRLEN];
+  memcpy(addr, cidr, addr_len);
+  addr[addr_len] = '\0';
+  char* end = NULL;
+  long prefix = strtol(slash + 1, &end, 10);
+  if (end == slash + 1 || *end != '\0')
+    return false;
+  struct in_addr v4;
+  struct in6_addr v6;
+  if (inet_pton(AF_INET, addr, &v4) == 1) {
+    if (prefix < 0 || prefix > 32)
+      return false;
+    memcpy(bytes, &v4, sizeof(v4));
+    *prefix_out = (int)prefix;
+    *family_out = AF_INET;
+    return true;
+  }
+  if (inet_pton(AF_INET6, addr, &v6) == 1) {
+    if (prefix < 0 || prefix > 128)
+      return false;
+    memcpy(bytes, &v6, sizeof(v6));
+    *prefix_out = (int)prefix;
+    *family_out = AF_INET6;
+    return true;
+  }
+  return false;
+}
+
+/* A host pattern is valid when it is `*`, a valid IPv4/IPv6 literal, or a valid
+ * CIDR.  Peer addresses reaching the matcher are always numeric, so hostname
+ * globs are rejected at parse time: accepting one would create a deny rule that
+ * silently never matches (fail-open). */
+static bool host_pattern_valid(const char* pattern) {
+  if (!pattern || *pattern == '\0')
+    return false;
+  if (strcmp(pattern, "*") == 0)
+    return true;
+  if (strchr(pattern, '/')) {
+    uint8_t bytes[16];
+    int prefix;
+    int family;
+    return parse_cidr(pattern, &prefix, bytes, &family);
+  }
+  struct in_addr v4;
+  struct in6_addr v6;
+  return inet_pton(AF_INET, pattern, &v4) == 1 || inet_pton(AF_INET6, pattern, &v6) == 1;
+}
+
+/* Append every comma- and/or whitespace-separated host pattern in `value` to
+ * the heap-owned list (or replace the list when `replace` is set, which --dparam
+ * uses so an override can narrow access rather than only widen it).  Returns
+ * false (err filled) on an invalid pattern or an allocation failure. */
+static bool store_host_list(char*** list, int* count, const char* value, const char* key,
+                            const char* module_name, bool replace, char* err, size_t err_size) {
+  if (replace) {
+    for (int i = 0; i < *count; i++)
+      free((*list)[i]);
+    free(*list);
+    *list = NULL;
+    *count = 0;
+  }
+  char* copy = str_dup(value);
+  if (!copy) {
+    if (module_name)
+      set_error(err, err_size, "out of memory parsing '%s' for module '%s'", key, module_name);
+    else
+      set_error(err, err_size, "out of memory parsing '%s'", key);
+    return false;
+  }
+  char* save = NULL;
+  for (char* token = strtok_r(copy, ", \t", &save); token; token = strtok_r(NULL, ", \t", &save)) {
+    if (!host_pattern_valid(token)) {
+      if (module_name)
+        set_error(err, err_size, "module '%s': invalid host pattern '%s' in '%s'", module_name,
+                  token, key);
+      else
+        set_error(err, err_size, "invalid host pattern '%s' in '%s'", token, key);
+      free(copy);
+      return false;
+    }
+    char** grown = realloc(*list, (size_t)(*count + 1) * sizeof(char*));
+    if (!grown) {
+      if (module_name)
+        set_error(err, err_size, "out of memory parsing '%s' for module '%s'", key, module_name);
+      else
+        set_error(err, err_size, "out of memory parsing '%s'", key);
+      free(copy);
+      return false;
+    }
+    *list = grown;
+    char* dup = str_dup(token);
+    if (!dup) {
+      if (module_name)
+        set_error(err, err_size, "out of memory parsing '%s' for module '%s'", key, module_name);
+      else
+        set_error(err, err_size, "out of memory parsing '%s'", key);
+      free(copy);
+      return false;
+    }
+    (*list)[(*count)++] = dup;
+  }
+  free(copy);
+  return true;
+}
+
+/* Parse a `max connections` value: a positive integer (0/negative/garbage are
+ * rejected because they would silently disable the cap or admit nothing). */
+static bool store_max_connections(int* slot, const char* value, const char* module_name, char* err,
+                                  size_t err_size) {
+  char* end = NULL;
+  errno = 0;
+  long n = strtol(value, &end, 10);
+  if (*value == '\0' || errno != 0 || *end != '\0' || n <= 0 || n > INT_MAX) {
+    if (module_name)
+      set_error(err, err_size,
+                "module '%s': invalid 'max connections' '%s' (must be a positive "
+                "integer)",
+                module_name, value);
+    else
+      set_error(err, err_size, "invalid 'max connections' '%s' (must be a positive integer)",
+                value);
+    return false;
+  }
+  *slot = (int)n;
+  return true;
+}
+
+/* Parse an `auth failure delay` value: 0 (disabled) through the configured cap. */
+static bool store_auth_failure_delay(int* slot, const char* value, char* err, size_t err_size) {
+  char* end = NULL;
+  errno = 0;
+  long n = strtol(value, &end, 10);
+  if (*value == '\0' || errno != 0 || *end != '\0' || n < 0 ||
+      n > DAEMON_CONF_MAX_AUTH_FAILURE_DELAY_MS) {
+    set_error(err, err_size, "invalid 'auth failure delay' '%s' (must be 0-%d milliseconds)", value,
+              DAEMON_CONF_MAX_AUTH_FAILURE_DELAY_MS);
+    return false;
+  }
+  *slot = (int)n;
+  return true;
+}
+
 bool daemon_module_name_valid(const char* name) {
   if (!name || *name == '\0')
     return false;
@@ -68,14 +225,25 @@ DaemonConf* daemon_conf_create(void) {
   if (!conf)
     return NULL;
   conf->global.port = DAEMON_CONF_DEFAULT_PORT;
+  conf->global.max_connections = DAEMON_CONF_DEFAULT_MAX_CONNECTIONS;
+  conf->global.auth_failure_delay_ms = DAEMON_CONF_DEFAULT_AUTH_FAILURE_DELAY_MS;
   return conf;
 }
 
+/* Free a heap-owned pattern list of `count` entries. */
+static void free_string_list(char** list, int count) {
+  for (int i = 0; i < count; i++)
+    free(list[i]);
+  free(list);
+}
+
 void daemon_conf_free(DaemonConf* conf) {
   if (!conf)
     return;
   free(conf->global.motd_file);
   free(conf->global.address);
+  free_string_list(conf->global.hosts_allow, conf->global.hosts_allow_count);
+  free_string_list(conf->global.hosts_deny, conf->global.hosts_deny_count);
   for (int i = 0; i < conf->module_count; i++) {
     DaemonModule* m = &conf->modules[i];
     free(m->name);
@@ -83,6 +251,8 @@ void daemon_conf_free(DaemonConf* conf) {
     for (int j = 0; j < m->auth_user_count; j++)
       free(m->auth_users[j]);
     free(m->auth_users);
+    free_string_list(m->hosts_allow, m->hosts_allow_count);
+    free_string_list(m->hosts_deny, m->hosts_deny_count);
   }
   free(conf->modules);
   free(conf);
@@ -122,8 +292,8 @@ static bool store_port(int* slot, const char* value, char* err, size_t err_size)
 
 /* Apply a global scalar key/value.  Keys are case-insensitive.  Returns false
  * (err filled) on an unknown key or an invalid value. */
-static bool apply_global_key(DaemonConf* conf, char* key, const char* value, char* err,
-                             size_t err_size) {
+static bool apply_global_key(DaemonConf* conf, char* key, const char* value, bool replace_hosts,
+                             char* err, size_t err_size) {
   if (key_equals(key, "port"))
     return store_port(&conf->global.port, value, err, err_size);
   if (key_equals(key, "motd file")) {
@@ -140,6 +310,16 @@ static bool apply_global_key(DaemonConf* conf, char* key, const char* value, cha
     }
     return true;
   }
+  if (key_equals(key, "max connections"))
+    return store_max_connections(&conf->global.max_connections, value, NULL, err, err_size);
+  if (key_equals(key, "auth failure delay"))
+    return store_auth_failure_delay(&conf->global.auth_failure_delay_ms, value, err, err_size);
+  if (key_equals(key, "hosts allow"))
+    return store_host_list(&conf->global.hosts_allow, &conf->global.hosts_allow_count, value,
+                           "hosts allow", NULL, replace_hosts, err, err_size);
+  if (key_equals(key, "hosts deny"))
+    return store_host_list(&conf->global.hosts_deny, &conf->global.hosts_deny_count, value,
+                           "hosts deny", NULL, replace_hosts, err, err_size);
   set_error(err, err_size, "unknown global key '%s'", key);
   return false;
 }
@@ -192,6 +372,12 @@ static bool apply_module_key(DaemonModule* module, char* key, char* value, char*
       const char* user = trim_ws(token);
       if (*user == '\0')
         continue;
+      if (!credentials_username_valid(user)) {
+        set_error(err, err_size, "module '%s': invalid 'auth users' entry '%s'", module->name,
+                  user);
+        free(list);
+        return false;
+      }
       char** grown =
           realloc(module->auth_users, (size_t)(module->auth_user_count + 1) * sizeof(char*));
       if (!grown) {
@@ -213,6 +399,14 @@ static bool apply_module_key(DaemonModule* module, char* key, char* value, char*
     free(list);
     return true;
   }
+  if (key_equals(key, "max connections"))
+    return store_max_connections(&module->max_connections, value, module->name, err, err_size);
+  if (key_equals(key, "hosts allow"))
+    return store_host_list(&module->hosts_allow, &module->hosts_allow_count, value, "hosts allow",
+                           false, module->name, err, err_size);
+  if (key_equals(key, "hosts deny"))
+    return store_host_list(&module->hosts_deny, &module->hosts_deny_count, value, "hosts deny",
+                           false, module->name, err, err_size);
   set_error(err, err_size, "unknown key '%s' in module '%s'", key, module->name);
   return false;
 }
@@ -393,7 +587,7 @@ DaemonConf* daemon_conf_load(const char* path, char* err, size_t err_size) {
         break;
       }
     } else {
-      if (!apply_global_key(conf, key, value, err, err_size)) {
+      if (!apply_global_key(conf, key, value, false, err, err_size)) {
         ok = false;
         break;
       }
@@ -448,7 +642,90 @@ int daemon_conf_apply_dparam(DaemonConf* conf, const char* assignment, char* err
     set_error(err, err_size, "--dparam '%s' has an empty value", assignment);
     return -1;
   }
-  bool ok = apply_global_key(conf, key, value, err, err_size);
+  bool ok = apply_global_key(conf, key, value, true, err, err_size);
   free(copy);
   return ok ? 0 : -1;
 }
+
+/* Compare the first `prefix` bits of two 16-byte address buffers. */
+static bool bit_prefix_match(const uint8_t* a, const uint8_t* b, int prefix) {
+  int whole = prefix / 8;
+  if (whole > 0 && memcmp(a, b, (size_t)whole) != 0)
+    return false;
+  int remainder = prefix % 8;
+  if (remainder == 0)
+    return true;
+  uint8_t mask = (uint8_t)(0xffu << (8 - remainder));
+  return (a[whole] & mask) == (b[whole] & mask);
+}
+
+/* Case-insensitive glob match used for hostname patterns.  Falls back to the
+ * shared case-sensitive matcher when an operand is too long for the stack
+ * buffers. */
+static bool host_glob_match(const char* pattern, const char* str) {
+  char pbuf[256];
+  char sbuf[256];
+  size_t plen = strlen(pattern);
+  size_t slen = strlen(str);
+  if (plen >= sizeof(pbuf) || slen >= sizeof(sbuf))
+    return glob_match(pattern, str);
+  for (size_t i = 0; i <= plen; i++)
+    pbuf[i] = (char)tolower((unsigned char)pattern[i]);
+  for (size_t i = 0; i <= slen; i++)
+    sbuf[i] = (char)tolower((unsigned char)str[i]);
+  return glob_match(pbuf, sbuf);
+}
+
+bool daemon_host_pattern_match(const char* pattern, const char* peer_ip) {
+  if (!pattern || *pattern == '\0' || !peer_ip || *peer_ip == '\0')
+    return false;
+  if (strcmp(pattern, "*") == 0)
+    return true;
+  if (strchr(pattern, '/')) {
+    uint8_t pattern_bytes[16];
+    uint8_t peer_bytes[16];
+    int prefix = 0;
+    int family = AF_UNSPEC;
+    if (!parse_cidr(pattern, &prefix, pattern_bytes, &family))
+      return false;
+    if (inet_pton(family, peer_ip, peer_bytes) != 1)
+      return false;
+    return bit_prefix_match(pattern_bytes, peer_bytes, prefix);
+  }
+  struct in_addr pattern_v4;
+  struct in_addr peer_v4;
+  if (inet_pton(AF_INET, pattern, &pattern_v4) == 1)
+    return inet_pton(AF_INET, peer_ip, &peer_v4) == 1 && pattern_v4.s_addr == peer_v4.s_addr;
+  struct in6_addr pattern_v6;
+  struct in6_addr peer_v6;
+  if (inet_pton(AF_INET6, pattern, &pattern_v6) == 1)
+    return inet_pton(AF_INET6, peer_ip, &peer_v6) == 1 &&
+           memcmp(&pattern_v6, &peer_v6, sizeof(pattern_v6)) == 0;
+  /* Not a literal: a hostname/glob pattern. */
+  return host_glob_match(pattern, peer_ip);
+}
+
+bool daemon_hosts_allowed(const char* peer_ip, char* const* allow, int allow_count,
+                          char* const* deny, int deny_count) {
+  if (!peer_ip)
+    return false;
+  for (int i = 0; i < deny_count; i++) {
+    if (daemon_host_pattern_match(deny[i], peer_ip))
+      return false;
+  }
+  if (allow_count > 0) {
+    for (int i = 0; i < allow_count; i++) {
+      if (daemon_host_pattern_match(allow[i], peer_ip))
+        return true;
+    }
+    return false;
+  }
+  return true;
+}
+
+bool daemon_hosts_restricted(char* const* allow, int allow_count, char* const* deny,
+                             int deny_count) {
+  (void)allow;
+  (void)deny;
+  return allow_count > 0 || deny_count > 0;
+}

src/shared/daemon_conf.h

@@ -52,6 +52,16 @@ typedef struct DaemonModule {
                         activities.  Without it the daemon refuses all of them. */
   char** auth_users; /* `auth users = a,b`; Wave B credential list */
   int auth_user_count;
+  /* `max connections = N` (optional per-module cap).  0 means "not set"
+   * (inherit the global cap).  Parsed, stored, and validated, but NOT enforced
+   * per-module: connections are counted in the accept-loop parent before the
+   * client's module is known, so only the global cap is enforced (see
+   * transport_tcp.c and the Daemon Mode notes in RSYNC_COMPAT.md). */
+  int max_connections;
+  char** hosts_allow; /* `hosts allow = a,b`; host access allow patterns */
+  int hosts_allow_count;
+  char** hosts_deny; /* `hosts deny = a,b`; host access deny patterns */
+  int hosts_deny_count;
 } DaemonModule;
 
 /* Global (pre-module) scalar keys.  `motd file` is parsed and stored but has
@@ -60,6 +70,14 @@ typedef struct DaemonConfGlobals {
   int port;                  /* `port`, default DAEMON_CONF_DEFAULT_PORT (873) */
   char* motd_file;           /* `motd file`, may be NULL */
   char* address;             /* `address` (optional bind address), may be NULL */
+  int max_connections;       /* `max connections`, default
+                                DAEMON_CONF_DEFAULT_MAX_CONNECTIONS (100) */
+  int auth_failure_delay_ms; /* `auth failure delay`, milliseconds; default
+                                DAEMON_CONF_DEFAULT_AUTH_FAILURE_DELAY_MS */
+  char** hosts_allow;        /* `hosts allow`; global host access allow patterns */
+  int hosts_allow_count;
+  char** hosts_deny; /* `hosts deny`; global host access deny patterns */
+  int hosts_deny_count;
 } DaemonConfGlobals;
 
 typedef struct DaemonConf {
@@ -69,6 +87,16 @@ typedef struct DaemonConf {
 } DaemonConf;
 
 #define DAEMON_CONF_DEFAULT_PORT 873
+/* Default global connection cap when `max connections` is absent.  Matches the
+ * historical hardcoded listener value. */
+#define DAEMON_CONF_DEFAULT_MAX_CONNECTIONS 100
+/* Default `auth failure delay` in milliseconds (0 disables the throttle). */
+#define DAEMON_CONF_DEFAULT_AUTH_FAILURE_DELAY_MS 500
+/* Largest accepted `auth failure delay`, so a typo cannot pin a connection
+ * child in nanosleep for an absurd time. */
+/* Bounded well below the socket I/O timeout so a failed-auth child cannot hold
+ * a connection slot for long enough to amplify connection-cap exhaustion. */
+#define DAEMON_CONF_MAX_AUTH_FAILURE_DELAY_MS 5000
 /* Longest accepted config line (excluding the trailing newline).  Longer lines
  * are rejected rather than buffered unboundedly. */
 #define DAEMON_CONF_MAX_LINE 4096
@@ -99,9 +127,30 @@ const DaemonModule* daemon_conf_find_module(const DaemonConf* conf, const char*
 bool daemon_module_name_valid(const char* name);
 
 /* Parse one --dparam=KEY=VALUE (or "--dparam KEY=VALUE") override string and
- * apply it to the global scalars only.  Keys are case-insensitive and limited
- * to the global scalar keys defined by the grammar (port, motd file, address).
- * Returns 0 on success, -1 on error (err filled). */
+ * apply it to the global keys only.  Keys are case-insensitive and limited to
+ * the global keys defined by the grammar (port, motd file, address,
+ * max connections, auth failure delay, hosts allow, hosts deny).  Returns 0 on
+ * success, -1 on error (err filled). */
 int daemon_conf_apply_dparam(DaemonConf* conf, const char* assignment, char* err, size_t err_size);
 
+/* Host access-control matching (pure; no I/O).  `daemon_host_pattern_match`
+ * matches one configured pattern against a numeric peer IP string.  Supported
+ * patterns: `*` (match anything), an IPv4/IPv6 literal, an IPv4/IPv6 CIDR
+ * (`10.0.0.0/8`, `2001:db8::/32`), or a glob (`*.example.com`) evaluated with
+ * the same matcher as file globs; a glob only matches a peer string of the
+ * same shape, so a numeric peer never matches a hostname glob. */
+bool daemon_host_pattern_match(const char* pattern, const char* peer_ip);
+
+/* rsync-like combined decision over a deny list and an allow list: a matching
+ * deny rejects (deny takes precedence); otherwise, when any allow entries
+ * exist, a peer that matches none is rejected; with no allow entries every
+ * peer not denied is accepted.  An empty/unset pair returns true. */
+bool daemon_hosts_allowed(const char* peer_ip, char* const* allow, int allow_count,
+                          char* const* deny, int deny_count);
+
+/* True when at least one allow or deny pattern is configured (i.e. an
+ * unprovable peer must fail closed rather than being treated as unrestricted). */
+bool daemon_hosts_restricted(char* const* allow, int allow_count, char* const* deny,
+                             int deny_count);
+
 #endif

src/shared/file_list.c

@@ -2,6 +2,7 @@
 #include "log.h"
 #include "utils.h"
 #include <errno.h>
+#include <limits.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -51,7 +52,8 @@ static int normalize_entry(const char* raw, size_t len, bool strip_line_endings,
   if (len == 0)
     return 0;
   if (raw[0] == '/') {
-    snprintf(err, err_size, "absolute path entries are not allowed: '%.*s'", (int)len, raw);
+    int print_len = len > (size_t)INT_MAX ? INT_MAX : (int)len;
+    snprintf(err, err_size, "absolute path entries are not allowed: '%.*s'", print_len, raw);
     return -1;
   }
   /* Reject NUL bytes inside a token defensively (NUL-delimited mode splits on

src/shared/file_receive.c

@@ -1696,9 +1696,9 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
     return NULL;
   }
 
-  if (has_path_traversal(check_path)) {
+  if (check_path[0] == '\0' || has_path_traversal(check_path)) {
     char* escaped_path = output_escape(check_path, log_get_8_bit_output());
-    log_message(LOG_LEVEL_ERROR, "Path traversal detected: %s",
+    log_message(LOG_LEVEL_ERROR, "Invalid received check path: %s",
                 escaped_path ? escaped_path : "<allocation failed>");
     free(escaped_path);
     free(check_path);
@@ -1832,6 +1832,7 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
            existing/ignore-existing/update/backup/delay-updates policy. */
         File* materialized = file_create(check_path);
         if (materialized && basis.content) {
+          data_destroy(materialized->data);
           materialized->data = basis.content;
           basis.content = NULL;
           materialized->metadata = file_metadata_create(NULL, &basis.st, false, false);
@@ -2095,6 +2096,7 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
       file->metadata = meta;
       file->xattrs = append_xattrs;
       append_xattrs = NULL;
+      data_destroy(file->data);
       file->data = data_create(full, full_size);
       if (!file->data) { /* data_create already freed full on failure */
         file_destroy(file);
@@ -2236,6 +2238,10 @@ File* file_receive(const Config* config, int file_descriptor) {
 
 /* ---- P7 Wave D: deferred directory times ---- */
 
+bool dir_times_should_capture(const Config* config) {
+  return config->use_metadata && !config->omit_dir_times;
+}
+
 void dir_time_list_init(DirTimeList* list) {
   if (!list)
     return;
@@ -2243,6 +2249,7 @@ void dir_time_list_init(DirTimeList* list) {
   list->entries = NULL;
   list->count = 0;
   list->capacity = 0;
+  list->bytes = 0;
 }
 
 void dir_time_list_free(DirTimeList* list) {
@@ -2256,11 +2263,23 @@ void dir_time_list_free(DirTimeList* list) {
   list->entries = NULL;
   list->count = 0;
   list->capacity = 0;
+  list->bytes = 0;
 }
 
 bool dir_time_list_add(DirTimeList* list, const char* wire_path, const FileMetadata* metadata) {
   if (!list || !wire_path || !metadata)
     return true; /* nothing to remember; never a hard error */
+  /* Cumulative, not per-frame: the sender may stream a tree across unbounded
+     STATUS_DIR_TIMES frames, so bound the TOTAL retained here.  Reject before
+     touching the list, leaving it exactly as it was (the caller fails the
+     transfer, which becomes a clean protocol error). */
+  size_t path_len = strlen(wire_path);
+  /* Charge the whole per-entry cost (path copy + pointer slot + metadata
+     struct), not just the path, so the array growth is bounded by the same
+     cumulative budget. */
+  size_t entry_cost = path_len + sizeof(FileMetadata) + sizeof(char*);
+  if (list->count >= MAX_DIR_TIME_ENTRIES || entry_cost > MAX_DIR_TIME_BYTES - list->bytes)
+    return false;
   if (list->count == list->capacity) {
     size_t new_capacity = list->capacity == 0 ? 16 : list->capacity * 2;
     if (new_capacity < list->capacity)
@@ -2287,6 +2306,7 @@ bool dir_time_list_add(DirTimeList* list, const char* wire_path, const FileMetad
   list->paths[list->count] = copy;
   list->entries[list->count] = *metadata;
   list->count++;
+  list->bytes += entry_cost;
   return true;
 }
 

src/shared/file_receive.h

@@ -7,6 +7,15 @@
 
 /* Server-side file receive/save path. */
 
+/* Cumulative caps for the deferred directory-time accumulator.  The sender may
+ * legitimately split a large tree across repeated STATUS_DIR_TIMES frames, so a
+ * per-frame bound is not enough: the receiver must bound the TOTAL it retains
+ * against a hostile sender.  Mirror the delete-manifest limits
+ * (MAX_MANIFEST_ENTRIES / MAX_MANIFEST_BYTES): the entry count bounds the
+ * metadata array and the byte budget bounds the concatenated path strings. */
+#define MAX_DIR_TIME_ENTRIES (1024 * 1024)
+#define MAX_DIR_TIME_BYTES (16ULL * 1024 * 1024)
+
 File* file_receive(const Config* config, int file_descriptor);
 File* file_receive_directory(int file_descriptor, const Config* config);
 File* file_receive_dir_time(int file_descriptor, const Config* config);
@@ -28,12 +37,20 @@ typedef struct {
   FileMetadata* entries; /* owned, parallel to paths */
   size_t count;
   size_t capacity;
+  size_t bytes; /* cumulative strlen of every retained path */
 } DirTimeList;
 
+/* Capture gate shared by the sender-side and receiver-side sinks: directory
+ * metadata is accumulated only when --times/--metadata is in effect and
+ * -O/--omit-dir-times does not suppress it.  Kept here, next to the accumulator
+ * it guards, so both call sites express the same condition. */
+bool dir_times_should_capture(const Config* config);
+
 void dir_time_list_init(DirTimeList* list);
 void dir_time_list_free(DirTimeList* list);
 /* Deep-copy one directory's path + metadata into the list.  Returns false on
- * allocation failure (the caller fails the transfer). */
+ * allocation failure OR when the cumulative entry/byte caps would be exceeded
+ * (the caller fails the transfer). */
 bool dir_time_list_add(DirTimeList* list, const char* wire_path, const FileMetadata* metadata);
 /* Apply every accumulated directory's mtime (and atime when captured) beneath
  * `root_directory`, confined fd-relative.  Best-effort per entry: an absent

src/shared/file_send.c

@@ -145,7 +145,7 @@ bool file_send_sendfile_with_skip(File* file, int file_descriptor, bool use_meta
   off_t offset = 0;
   struct timespec deadline;
   clock_gettime(CLOCK_MONOTONIC, &deadline);
-  deadline.tv_sec += 60;
+  deadline.tv_sec += protocol_get_io_timeout_sec();
   while ((unsigned long long)offset < file_size) {
     struct timespec now;
     clock_gettime(CLOCK_MONOTONIC, &now);

src/shared/identity.c

@@ -30,7 +30,7 @@ typedef struct {
   /* --super / --no-super tri-state (SUPER_MODE_AUTO when unset).  Snapshotted
    * per connection so privilege_super_permitted() can gate super-user
    * activities without a Config argument. */
-  int super_mode;
+  SuperMode super_mode;
   /* --copy-as=USER[:GROUP]: snapshotted so the ownership resolver can force the
    * target ids without a Config argument. */
   bool copy_as_set;
@@ -128,7 +128,7 @@ bool privilege_super_permitted(void) {
   return privilege_super_mode_permitted(g_identity.super_mode);
 }
 
-bool privilege_super_mode_permitted(int mode) {
+bool privilege_super_mode_permitted(SuperMode mode) {
   /* AUTO and ON both attempt the confined operation; OFF forbids it even for a
    * root receiver.  AUTO is the historical FastSync behavior (always attempt
    * and let the kernel refuse an unprivileged call, which the caller skips), so

src/shared/identity.h

@@ -128,6 +128,6 @@ bool identity_wire_valid(const Config* config);
  * best-effort behavior where an unprivileged attempt is refused by the kernel
  * and skipped.  Neither EVER elevates privileges. */
 bool privilege_super_permitted(void);
-bool privilege_super_mode_permitted(int mode);
+bool privilege_super_mode_permitted(SuperMode mode);
 
 #endif

src/shared/log.c

@@ -3,7 +3,9 @@
 #include <stdbool.h>
 #include <stdarg.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
+#include <threads.h>
 #include <time.h>
 
 static const char* log_level_strings[] = {"DEBUG", "INFO", "WARN", "ERROR"};
@@ -15,6 +17,18 @@ static FILE* log_fp = NULL;
 static _Thread_local bool eight_bit_output;
 static LogStderrMode stderr_mode = LOG_STDERR_ERRORS;
 
+/* Serializes access to log_fp and makes each emitted line atomic: the
+ * timestamp prefix, formatted body, and trailing newline are written as one
+ * critical section so concurrent threads cannot interleave partial lines.
+ * Initialized lazily (matching the protocol.c bw_mutex idiom) because logging
+ * can happen before main() installs any synchronization. */
+static mtx_t log_mutex;
+static once_flag log_mutex_once = ONCE_FLAG_INIT;
+
+static void log_mutex_init(void) {
+  mtx_init(&log_mutex, mtx_plain);
+}
+
 void set_log_level(LogLevel level) {
   current_log_level = level;
 }
@@ -41,7 +55,10 @@ uint32_t get_log_info_flags(void) {
 }
 
 void log_set_file(FILE* fp) {
+  call_once(&log_mutex_once, log_mutex_init);
+  mtx_lock(&log_mutex);
   log_fp = fp;
+  mtx_unlock(&log_mutex);
 }
 
 void log_set_8_bit_output(bool enabled) {
@@ -60,13 +77,48 @@ LogStderrMode log_get_stderr_mode(void) {
   return stderr_mode;
 }
 
-static inline void write_message(FILE* dest_io, LogLevel log_level, struct tm t, const char* format,
+/* Format one complete log line (timestamp prefix + body + newline) into a
+ * freshly allocated buffer.  This is pure CPU/malloc work and must happen
+ * OUTSIDE the log mutex: the mutex only guards the log_fp pointer, so a
+ * stalled stderr/stdout pipe cannot block every logging thread.  Returns NULL
+ * on allocation/formatting failure. */
+static char* format_log_line(LogLevel log_level, const struct tm* t, const char* format,
                              va_list args) {
-  fprintf(dest_io, "%04d-%02d-%02d %02d:%02d:%02d [%s]: ", t.tm_year + 1900, t.tm_mon + 1,
-          t.tm_mday, t.tm_hour, t.tm_min, t.tm_sec, log_level_strings[log_level]);
+  char prefix[64];
+  int prefix_len = snprintf(
+      prefix, sizeof(prefix), "%04d-%02d-%02d %02d:%02d:%02d [%s]: ", t->tm_year + 1900,
+      t->tm_mon + 1, t->tm_mday, t->tm_hour, t->tm_min, t->tm_sec, log_level_strings[log_level]);
+  if (prefix_len < 0 || prefix_len >= (int)sizeof(prefix))
+    return NULL;
+  va_list copy;
+  va_copy(copy, args);
+  int body_len = vsnprintf(NULL, 0, format, copy);
+  va_end(copy);
+  if (body_len < 0)
+    return NULL;
+  size_t total = (size_t)prefix_len + (size_t)body_len;
+  char* line = malloc(total + 2); /* body bytes + '\n' + NUL */
+  if (!line)
+    return NULL;
+  memcpy(line, prefix, (size_t)prefix_len);
+  vsnprintf(line + prefix_len, (size_t)body_len + 1, format, args);
+  line[total] = '\n';
+  line[total + 1] = '\0';
+  return line;
+}
 
-  vfprintf(dest_io, format, args);
-  fprintf(dest_io, "\n");
+/* Write an already-formatted line to the console and, if configured, the log
+ * file.  Only the log_fp pointer is read under the mutex (so log_set_file /
+ * config_delete cannot free it while it is in use); the single console fputs
+ * runs unlocked but is internally atomic per stdio stream. */
+static void emit_log_line(FILE* console, const char* line) {
+  fputs(line, console);
+  call_once(&log_mutex_once, log_mutex_init);
+  mtx_lock(&log_mutex);
+  FILE* file = log_fp;
+  if (file)
+    fputs(line, file);
+  mtx_unlock(&log_mutex);
 }
 
 void log_message(LogLevel log_level, const char* format, ...) {
@@ -86,14 +138,12 @@ void log_message(LogLevel log_level, const char* format, ...) {
 
   va_list args;
   va_start(args, format);
-  write_message(dest_io, log_level, t, format, args);
+  char* line = format_log_line(log_level, &t, format, args);
   va_end(args);
-
-  if (log_fp) {
-    va_start(args, format);
-    write_message(log_fp, log_level, t, format, args);
-    va_end(args);
-  }
+  if (!line)
+    return;
+  emit_log_line(dest_io, line);
+  free(line);
 }
 
 void log_debug_message(LogDebugFlag flag, const char* format, ...) {
@@ -107,14 +157,12 @@ void log_debug_message(LogDebugFlag flag, const char* format, ...) {
 
   va_list args;
   va_start(args, format);
-  write_message(stdout, LOG_LEVEL_DEBUG, t, format, args);
+  char* line = format_log_line(LOG_LEVEL_DEBUG, &t, format, args);
   va_end(args);
-
-  if (log_fp) {
-    va_start(args, format);
-    write_message(log_fp, LOG_LEVEL_DEBUG, t, format, args);
-    va_end(args);
-  }
+  if (!line)
+    return;
+  emit_log_line(stdout, line);
+  free(line);
 }
 
 void log_info_message(LogInfoFlag flag, const char* format, ...) {
@@ -129,14 +177,12 @@ void log_info_message(LogInfoFlag flag, const char* format, ...) {
 
   va_list args;
   va_start(args, format);
-  write_message(stdout, LOG_LEVEL_INFO, t, format, args);
+  char* line = format_log_line(LOG_LEVEL_INFO, &t, format, args);
   va_end(args);
-
-  if (log_fp) {
-    va_start(args, format);
-    write_message(log_fp, LOG_LEVEL_INFO, t, format, args);
-    va_end(args);
-  }
+  if (!line)
+    return;
+  emit_log_line(stdout, line);
+  free(line);
 }
 
 void log_perror(const char* context) {

src/shared/multiprocessing.c

@@ -6,6 +6,7 @@
 #include "config.h"
 #include "data.h"
 #include "file.h"
+#include "file_receive.h"
 #include "log.h"
 #include "protocol.h"
 #include "queue.h"
@@ -331,7 +332,7 @@ int write_thread(void* pipeline_context) {
        write would clobber them); accumulate the metadata here and let the
        caller apply it once every writer has drained. */
     if (result != FILE_SAVE_ERROR && file->is_dir && file->metadata &&
-        context->config->use_metadata && !context->config->omit_dir_times &&
+        dir_times_should_capture(context->config) &&
         !dir_time_list_add(&context->dir_times, file->path, file->metadata)) {
       file_destroy(file);
       pipeline_context_receiver_note_bytes_released(context, file_bytes);

src/shared/protocol.c

@@ -76,10 +76,23 @@ void protocol_session_init(ProtocolSession* session, int read_fd, int write_fd)
   session->read_fd = read_fd;
   session->write_fd = write_fd;
   session->max_alloc = DEFAULT_MAX_ALLOC;
+  session->io_timeout_sec = RECEIVE_TIMEOUT_SEC;
   atomic_init(&session->total_allocated_bytes, 0);
   protocol_session_set_bwlimit(session, global_bwlimit());
 }
 
+void protocol_session_set_io_timeout(ProtocolSession* session, int sec) {
+  if (!session)
+    return;
+  session->io_timeout_sec = sec;
+}
+
+int protocol_get_io_timeout_sec(void) {
+  const ProtocolSession* session = bound_session ? bound_session : &legacy_io_session;
+  int sec = session->io_timeout_sec;
+  return sec > 0 ? sec : RECEIVE_TIMEOUT_SEC;
+}
+
 void protocol_session_set_max_alloc(ProtocolSession* session, unsigned long long max_alloc) {
   if (!session)
     session = bound_session ? bound_session : &legacy_io_session;
@@ -257,10 +270,11 @@ bool protocol_send_n_data(ProtocolSession* session, const void* data, size_t dat
   log_debug_message(LOG_DEBUG_IO, "    Sending n Data: %zu", data_size);
   if (!session)
     return false;
+  int timeout_sec = session->io_timeout_sec > 0 ? session->io_timeout_sec : SEND_TIMEOUT_SEC;
   int fd = session->write_fd;
   struct timespec deadline;
   clock_gettime(CLOCK_MONOTONIC, &deadline);
-  deadline.tv_sec += SEND_TIMEOUT_SEC;
+  deadline.tv_sec += timeout_sec;
   short wait_events = POLLOUT;
   ssize_t total_bytes_send = 0;
   while ((size_t)total_bytes_send < data_size) {
@@ -306,7 +320,10 @@ bool protocol_receive_n_data_timed(ProtocolSession* session, void* data, size_t
                                    int timeout_sec);
 
 bool protocol_receive_n_data(ProtocolSession* session, void* data, size_t data_size) {
-  return protocol_receive_n_data_timed(session, data, data_size, RECEIVE_TIMEOUT_SEC);
+  /* Honor the session's configured deadline; protocol_receive_n_data_timed
+   * re-applies the built-in 60 s default when the value is <= 0. */
+  int timeout_sec = session ? session->io_timeout_sec : 0;
+  return protocol_receive_n_data_timed(session, data, data_size, timeout_sec);
 }
 
 bool protocol_receive_n_data_timed(ProtocolSession* session, void* data, size_t data_size,

src/shared/protocol.h

@@ -52,6 +52,12 @@ typedef struct ProtocolSession {
   atomic_ullong total_allocated_bytes;
   bool eight_bit_output;
   unsigned long long max_alloc;
+  /* Per-session deadline (seconds) applied to every protocol send/receive by
+   * protocol_send_n_data / protocol_receive_n_data.  Defaults to the built-in
+   * 60 s window; a value <= 0 falls back to that default.  Set from the
+   * negotiated Config->timeout so --timeout is honored by the poll()-driven
+   * protocol I/O, not just the socket SO_RCVTIMEO/SO_SNDTIMEO. */
+  int io_timeout_sec;
 } ProtocolSession;
 
 typedef int Status;
@@ -141,6 +147,15 @@ void protocol_session_unbind(void);
 void protocol_session_set_ssl(ProtocolSession* session, SSL* ssl);
 void protocol_session_set_bwlimit(ProtocolSession* session, unsigned long long bytes_per_sec);
 void protocol_session_set_max_alloc(ProtocolSession* session, unsigned long long max_alloc);
+/* Override the per-message send/receive deadline for this session.
+ * `sec` <= 0 restores the built-in 60 s default (used for --timeout=0/unset).
+ * An explicit long deadline (e.g. the delete-ack wait) is applied per-call by
+ * protocol_receive_status_timed and is unaffected by this setter. */
+void protocol_session_set_io_timeout(ProtocolSession* session, int sec);
+/* Effective per-message I/O deadline (seconds) for the currently-bound session,
+ * falling back to the built-in default.  Used by the plaintext sendfile path
+ * which bypasses the protocol send primitive. */
+int protocol_get_io_timeout_sec(void);
 void* protocol_alloc(size_t size);
 void* protocol_realloc(void* ptr, size_t size);
 void protocol_session_set_8_bit_output(ProtocolSession* session, bool enabled);

src/shared/transport_ssh.c

@@ -128,7 +128,7 @@ char* ssh_build_remote_command(const char* server_path, bool old_args, char* con
         q++;
       len++;
     }
-    if (len > SIZE_MAX - q * 3 || len + q * 3 + 3 > SIZE_MAX - command_len)
+    if (q > (SIZE_MAX - len) / 3 || len + q * 3 + 3 > SIZE_MAX - command_len)
       return NULL;
     command_len += len + q * 3 + 3;
   }

src/shared/transport_tcp.c

@@ -115,6 +115,11 @@ Server* server_create(int port) {
   return server_create_ex(port, NULL);
 }
 
+void server_set_max_connections(Server* server, unsigned int max_connections) {
+  if (server && max_connections > 0)
+    server->max_connections = max_connections;
+}
+
 void server_delete(Server** server) {
   if (server == NULL || *server == NULL)
     return;
@@ -135,7 +140,7 @@ static void accept_loop(Server* server, void (*child_fn)(int, void*), void* chil
   }
   signal(SIGCHLD, sigchld_handler);
   while (1) {
-    struct sockaddr_in client_addr;
+    struct sockaddr_storage client_addr;
     socklen_t client_len = sizeof(client_addr);
     int fd = accept(server->file_descriptor, (struct sockaddr*)&client_addr, &client_len);
     if (fd < 0) {
@@ -143,18 +148,30 @@ static void accept_loop(Server* server, void (*child_fn)(int, void*), void* chil
       continue;
     }
     tcp_apply_socket_timeout(fd);
+    char peer[128];
+    if (!utils_sockaddr_to_string((const struct sockaddr*)&client_addr, peer, sizeof(peer)))
+      snprintf(peer, sizeof(peer), "unknown");
     if ((unsigned int)g_active_connections >= server->max_connections) {
-      log_message(LOG_LEVEL_WARNING, "Max connections (%u) reached, rejecting",
-                  server->max_connections);
+      log_message(LOG_LEVEL_WARNING, "Max connections (%u) reached, rejecting %s",
+                  server->max_connections, peer);
       close(fd);
       continue;
     }
-    log_message(LOG_LEVEL_INFO, "%s", log_fmt);
+    log_message(LOG_LEVEL_INFO, "%s from %s", log_fmt, peer);
     pid_t pid = fork();
     if (pid == 0) {
+      /* Connection children must not run the parent's global cleanup(): it
+       * frees state (credentials / daemon conf) that the child's worker
+       * threads may still be reading and closes fd numbers the child could
+       * already have reused.  Reset the inherited handlers so a signal
+       * terminates the child directly; SIGCHLD is reset too since a child
+       * must never reap the parent's children.  This runs before the child
+       * spawns any thread, so it cannot race one. */
+      signal(SIGINT, SIG_DFL);
+      signal(SIGTERM, SIG_DFL);
+      signal(SIGCHLD, SIG_DFL);
       close(server->file_descriptor);
       child_fn(fd, child_ctx);
-      close(fd);
       _exit(0);
     } else if (pid > 0) {
       g_active_connections++;
@@ -169,6 +186,9 @@ struct plain_ctx {
 
 static void plain_child_fn(int fd, void* ctx) {
   ((struct plain_ctx*)ctx)->handler(fd);
+  /* handler() never closes the connection fd; the child owns its single
+   * close here after the handler has fully torn down. */
+  close(fd);
 }
 
 bool server_listen(Server* server, void (*handler)(int file_descriptor)) {

src/shared/transport_tcp.h

@@ -45,6 +45,9 @@ typedef struct {
 
 Server* server_create_ex(int port, const ServerBindOptions* bind_opts);
 Server* server_create(int port);
+/* Override the listener's connection cap (the global daemon `max connections`
+ * value).  A non-positive value is ignored so the default cap stands. */
+void server_set_max_connections(Server* server, unsigned int max_connections);
 bool server_listen(Server* server, void (*handler)(int file_descriptor));
 void server_accept_loop(Server* server, void (*child_fn)(int, void*), void* child_ctx,
                         const char* log_fmt);

src/shared/transport_tls.c

@@ -65,6 +65,18 @@ static SSL_CTX* create_ssl_ctx(bool is_server, const char* cert, const char* key
     SSL_CTX_free(ctx);
     return NULL;
   }
+  /* TLS 1.3 ciphersuites are configured separately from the TLS 1.2 and below
+   * cipher list above.  Pin the three AEAD suites OpenSSL offers, dropping
+   * TLS_AES_128_CCM_SHA256 and the CCM_8 variant, and fail closed if the
+   * library rejects the policy.  SSL_CTX_set_ciphersuites needs OpenSSL 1.1.1;
+   * earlier versions have no TLS 1.3, so the call is compile-guarded. */
+#if OPENSSL_VERSION_NUMBER >= 0x10101000L
+  if (SSL_CTX_set_ciphersuites(
+          ctx, "TLS_AES_256_GCM_SHA384:TLS_CHACHA20_POLY1305_SHA256:TLS_AES_128_GCM_SHA256") != 1) {
+    SSL_CTX_free(ctx);
+    return NULL;
+  }
+#endif
 
   if (cert && key) {
     struct stat key_stat;
@@ -180,13 +192,18 @@ static void tls_child_fn(int fd, void* arg) {
   SSL* ssl = wrap_fd_with_ssl(fd, ctx->ssl_ctx, true, NULL);
   if (!ssl) {
     io_set_ssl(NULL);
+    close(fd);
     return;
   }
   io_set_ssl(ssl);
   ctx->handler(fd);
+  /* Shut the TLS layer down before releasing the fd: handler() no longer
+   * closes it, so SSL_shutdown still has a valid socket.  The child owns the
+   * single fd close, performed last. */
   SSL_shutdown(ssl);
   SSL_free(ssl);
   io_set_ssl(NULL);
+  close(fd);
 }
 
 bool server_listen_tls(Server* server, void (*handler)(int file_descriptor)) {

src/shared/utils.c

@@ -587,6 +587,71 @@ bool utils_fd_peer_is_local(int fd) {
   return utils_sockaddr_is_loopback((const struct sockaddr*)&peer);
 }
 
+/* Numeric peer address of a connected fd.  Only AF_INET/AF_INET6 peers are
+   formatted; every other descriptor/family (pipe, AF_UNIX socketpair, ...) or a
+   getpeername failure returns false with buf emptied.  The caller must treat
+   that as "cannot tell". */
+bool utils_fd_peer_ip(int fd, char* buf, size_t len) {
+  if (!buf || len == 0)
+    return false;
+  buf[0] = '\0';
+  if (fd < 0)
+    return false;
+  struct sockaddr_storage peer;
+  socklen_t peer_len = sizeof(peer);
+  if (getpeername(fd, (struct sockaddr*)&peer, &peer_len) != 0)
+    return false;
+  const void* src = NULL;
+  int family = peer.ss_family;
+  if (family == AF_INET) {
+    src = &((const struct sockaddr_in*)&peer)->sin_addr;
+  } else if (family == AF_INET6) {
+    const struct sockaddr_in6* peer6 = (const struct sockaddr_in6*)&peer;
+    /* A dual-stack IPv6 listener reports IPv4 peers as ::ffff:a.b.c.d.  Emit
+     * the IPv4 form so IPv4 ACL patterns (and logs) see the real address. */
+    if (IN6_IS_ADDR_V4MAPPED(&peer6->sin6_addr)) {
+      struct in_addr v4;
+      memcpy(&v4, &peer6->sin6_addr.s6_addr[12], sizeof(v4));
+      return inet_ntop(AF_INET, &v4, buf, (socklen_t)len) != NULL;
+    }
+    src = &peer6->sin6_addr;
+  } else {
+    return false;
+  }
+  return inet_ntop(family, src, buf, (socklen_t)len) != NULL;
+}
+
+/* "ip:port" / "[ip]:port" for a connected peer, used to log the connecting
+   address in the accept loop.  Returns false for a non-INET family. */
+bool utils_sockaddr_to_string(const struct sockaddr* addr, char* buf, size_t len) {
+  if (!addr || !buf || len == 0)
+    return false;
+  buf[0] = '\0';
+  char ip[INET6_ADDRSTRLEN];
+  unsigned short port;
+  int written;
+  if (addr->sa_family == AF_INET) {
+    const struct sockaddr_in* v4 = (const struct sockaddr_in*)addr;
+    if (!inet_ntop(AF_INET, &v4->sin_addr, ip, sizeof(ip)))
+      return false;
+    port = ntohs(v4->sin_port);
+    written = snprintf(buf, len, "%s:%u", ip, port);
+  } else if (addr->sa_family == AF_INET6) {
+    const struct sockaddr_in6* v6 = (const struct sockaddr_in6*)addr;
+    if (!inet_ntop(AF_INET6, &v6->sin6_addr, ip, sizeof(ip)))
+      return false;
+    port = ntohs(v6->sin6_port);
+    written = snprintf(buf, len, "[%s]:%u", ip, port);
+  } else {
+    return false;
+  }
+  if (written < 0 || (size_t)written >= len) {
+    buf[0] = '\0';
+    return false;
+  }
+  return true;
+}
+
 /* True when a client-supplied host string names a loopback destination:
    "localhost", any 127.0.0.0/8 literal, "::1", or "[::1]". */
 bool utils_host_is_loopback(const char* host) {

src/shared/utils.h

@@ -77,5 +77,13 @@ bool append_tail_length(unsigned long long old_size, unsigned long long check_si
 bool utils_sockaddr_is_loopback(const struct sockaddr* addr);
 bool utils_fd_peer_is_local(int fd);
 bool utils_host_is_loopback(const char* host);
+/* Numeric peer address of a connected fd (INET6_ADDRSTRLEN is always enough).
+ * Returns false and leaves buf empty when the fd is not a connected INET socket
+ * or getpeername/inet_ntop fails.  Used by the daemon host-access gate; a false
+ * return is "cannot tell" and must be treated as fail-closed when ACLs apply. */
+bool utils_fd_peer_ip(int fd, char* buf, size_t len);
+/* Format a sockaddr as "ip:port" (IPv4) or "[ip]:port" (IPv6) for logging.
+ * Returns false (buf emptied) for a non-INET family or a formatting failure. */
+bool utils_sockaddr_to_string(const struct sockaddr* addr, char* buf, size_t len);
 
 #endif

tests/integration/test_daemon.py

@@ -51,6 +51,7 @@ READONLY_MODULE = os.path.join(MODULE_ROOT, "readonly")
 AUTH_MODULE = os.path.join(MODULE_ROOT, "auth")
 TEAM_MODULE = os.path.join(MODULE_ROOT, "team")
 OWNER_MODULE = os.path.join(MODULE_ROOT, "owner")
+DENIED_MODULE = os.path.join(MODULE_ROOT, "denied")
 CONF_FILE = os.path.join(TEST_DATA_DIR, "fastsyncd.conf")
 CRED_FILE = os.path.join(TEST_DATA_DIR, "fastsyncd.passwd")
 STARTFAIL_CONF = os.path.join(TEST_DATA_DIR, "fastsyncd_startfail.conf")
@@ -191,7 +192,7 @@ def _config_port(config_path):
 @pytest.fixture(scope="module", autouse=True)
 def daemon_env():
     for d in (MODULE_ROOT, FILES_MODULE, READONLY_MODULE, AUTH_MODULE, TEAM_MODULE, OWNER_MODULE,
-              DETACH_MODULE):
+              DENIED_MODULE, DETACH_MODULE):
         shutil.rmtree(d, ignore_errors=True)
         os.makedirs(d, exist_ok=True)
     generate_test_files(SOURCE_DIR, full=False)
@@ -231,7 +232,12 @@ def daemon_env():
             "[owner]\n"
             "path = %s\n"
             "client owner = yes\n"
-            % (config_port, FILES_MODULE, READONLY_MODULE, AUTH_MODULE, TEAM_MODULE, OWNER_MODULE))
+            "\n"
+            "[denied]\n"
+            "path = %s\n"
+            "hosts deny = 127.0.0.1\n"
+            % (config_port, FILES_MODULE, READONLY_MODULE, AUTH_MODULE, TEAM_MODULE, OWNER_MODULE,
+               DENIED_MODULE))
 
     # A dedicated config for the fail-closed startup check: an auth-required
     # module with no credential store must refuse to start.  Its own free port
@@ -368,6 +374,15 @@ class TestDaemonRejection:
         result = _push("127.0.0.1::/sub", daemon.port)
         assert result.returncode != 0
 
+    @pytest.mark.ci
+    def test_hosts_deny_rejects_loopback(self, daemon):
+        """Host access control: a module with `hosts deny = 127.0.0.1` refuses a
+        loopback client at the config gate, before any data is exchanged."""
+        before = self._tree_files()
+        result = _push("127.0.0.1::denied", daemon.port)
+        assert result.returncode != 0
+        assert self._tree_files() == before, "host-denied connection wrote under the module root"
+
     def test_dotdot_destination_rejected(self, daemon):
         """A '..' path expansion in the module-relative path is refused at parse
         time so a client cannot escape the module root while it is still on the

tests/runner.c

@@ -23,6 +23,7 @@
 #include "test_property.h"
 #include "test_protocol.h"
 #include "test_queue.h"
+#include "test_receiver_timeout.h"
 #include "test_robustness.h"
 #include "test_scanner.h"
 #include "test_server.h"
@@ -61,6 +62,7 @@ int main() {
   RUN_TEST(test_delta);
   RUN_TEST(test_data);
   RUN_TEST(test_protocol);
+  RUN_TEST(test_receiver_timeout);
   RUN_TEST(test_metadata);
   RUN_TEST(test_glob);
   RUN_TEST(test_iconv);

tests/test_array_list.c

@@ -1,6 +1,7 @@
 #include "test_array_list.h"
 #include "array_list.h"
 #include "test_utils.h"
+#include <limits.h>
 #include <stdlib.h>
 
 static int destroyer_calls = 0;
@@ -9,7 +10,7 @@ static void test_destroyer(void* item) {
   free(item);
 }
 
-void test_array_list() {
+static void test_array_list_basic() {
   ArrayList* list = array_list_create(free);
   EXPECT_NOT_NULL(list);
   EXPECT_EQ_INT(list->size, 0);
@@ -54,3 +55,20 @@ void test_array_list() {
   array_list_delete(list);
   EXPECT_EQ_INT(destroyer_calls, 106);
 }
+
+/* A capacity that would overflow `capacity * 2` must be refused instead of
+ * wrapping into signed-overflow UB; array_list_add surfaces the failure. */
+static void test_array_list_extend_overflow_guard() {
+  ArrayList* list = array_list_create(NULL);
+  EXPECT_NOT_NULL(list);
+  list->capacity = INT_MAX / 2 + 1;
+  list->size = list->capacity;
+  EXPECT_FALSE(array_list_add(list, NULL));
+  list->size = 0;
+  array_list_delete(list);
+}
+
+void test_array_list() {
+  test_array_list_basic();
+  test_array_list_extend_overflow_guard();
+}

tests/test_config.c

@@ -6,6 +6,7 @@
 #include "queue.h"
 #include "test_utils.h"
 #include "utils.h"
+#include <signal.h>
 #include <stdlib.h>
 #include <sys/socket.h>
 #include <string.h>
@@ -1672,7 +1673,7 @@ static void test_config_receive_rejects_invalid_iconv_spec() {
 static void test_config_super_mode_wire_roundtrip() {
   if (is_running_under_valgrind())
     return;
-  int modes[] = {SUPER_MODE_AUTO, SUPER_MODE_ON, SUPER_MODE_OFF};
+  SuperMode modes[] = {SUPER_MODE_AUTO, SUPER_MODE_ON, SUPER_MODE_OFF};
   for (size_t i = 0; i < sizeof(modes) / sizeof(modes[0]); i++) {
     int p[2];
     EXPECT_EQ_INT(socketpair(AF_UNIX, SOCK_STREAM, 0, p), 0);
@@ -1846,6 +1847,89 @@ static void test_config_receive_rejects_copy_as_without_metadata() {
   config_delete(c);
 }
 
+/* Like roundtrip_config_ok, but the parent is the RECEIVER so the frame can be
+   rejected MID-way, before the sender finishes writing it.  The sender child
+   ignores SIGPIPE so the receiver closing early cannot kill it; the parent
+   waits for the child to exit after observing the rejection. */
+static bool roundtrip_config_rejected(const Config* send_cfg) {
+  int p[2];
+  if (socketpair(AF_UNIX, SOCK_STREAM, 0, p) != 0)
+    return false;
+  pid_t pid = fork();
+  if (pid == 0) {
+    (void)signal(SIGPIPE, SIG_IGN);
+    close(p[0]);
+    io_set_fds(p[1], p[1]);
+    config_send(p[1], send_cfg);
+    close(p[1]);
+    _exit(0);
+  }
+  close(p[1]);
+  io_set_fds(p[0], p[0]);
+  Config* recv = config_receive(p[0]);
+  bool rejected = recv == NULL;
+  config_delete(recv);
+  close(p[0]);
+  int status;
+  waitpid(pid, &status, 0);
+  return rejected;
+}
+
+/* Build a Config with `count` --skip-compress suffixes, each `suffix_len` bytes
+   long, for the pre-auth config-string budget tests. */
+static Config* make_skip_compress_config(int count, size_t suffix_len) {
+  Config* c = config_create();
+  if (!c)
+    return NULL;
+  c->send_directory = str_dup("/src");
+  c->receive_root_directory = str_dup("/dst");
+  c->skip_compress_set = true;
+  c->skip_compress_count = count;
+  c->skip_compress_suffixes = calloc((size_t)count, sizeof(char*));
+  if (!c->skip_compress_suffixes) {
+    config_delete(c);
+    return NULL;
+  }
+  char* suffix = malloc(suffix_len + 1);
+  if (!suffix) {
+    config_delete(c);
+    return NULL;
+  }
+  memset(suffix, 'x', suffix_len);
+  suffix[suffix_len] = '\0';
+  for (int i = 0; i < count; i++)
+    c->skip_compress_suffixes[i] = str_dup(suffix);
+  free(suffix);
+  return c;
+}
+
+/* Pre-auth memory bound: one connection must not retain unbounded config
+   strings.  An over-limit --skip-compress count is refused, and even an
+   in-range count cannot exceed the aggregate per-connection string budget. */
+static void test_config_receive_rejects_oversized_string_budget() {
+  if (is_running_under_valgrind())
+    return;
+
+  /* Exactly MAX_SKIP_COMPRESS_SUFFIXES tiny suffixes are accepted. */
+  Config* ok = make_skip_compress_config(MAX_SKIP_COMPRESS_SUFFIXES, 1);
+  EXPECT_NOT_NULL(ok);
+  EXPECT_TRUE(roundtrip_config_ok(ok));
+  config_delete(ok);
+
+  /* One suffix over the count cap is rejected before any suffix is read. */
+  Config* over_count = make_skip_compress_config(MAX_SKIP_COMPRESS_SUFFIXES + 1, 1);
+  EXPECT_NOT_NULL(over_count);
+  EXPECT_TRUE(roundtrip_config_rejected(over_count));
+  config_delete(over_count);
+
+  /* In-range count, but the strings together exceed MAX_CONFIG_STRING_BYTES
+     (64 suffixes * ~64 KiB > 1 MiB), so the aggregate budget rejects it. */
+  Config* over_bytes = make_skip_compress_config(64, MAX_STRING_SIZE - 1);
+  EXPECT_NOT_NULL(over_bytes);
+  EXPECT_TRUE(roundtrip_config_rejected(over_bytes));
+  config_delete(over_bytes);
+}
+
 /* identity_copy_as_refused() is the pure, pre-snapshot refusal predicate: a
    --copy-as is refused when the receiver is not root OR the effective super
    mode is OFF (an operator veto), and never when --copy-as is unset. */
@@ -2009,6 +2093,7 @@ void test_config() {
     test_config_copy_as_wire_roundtrip();
     test_config_receive_rejects_negative_copy_as();
     test_config_receive_rejects_copy_as_without_metadata();
+    test_config_receive_rejects_oversized_string_budget();
     test_config_receive_with_validate_rejects();
   }
   test_identity_copy_as_refused();

tests/test_daemon_conf.c

@@ -1,4 +1,5 @@
 #include "test_daemon_conf.h"
+#include "credentials.h"
 #include "daemon_conf.h"
 #include "test_utils.h"
 #include <stdio.h>
@@ -30,6 +31,10 @@ static void test_daemon_conf_create_defaults() {
   EXPECT_EQ_INT(conf->global.port, DAEMON_CONF_DEFAULT_PORT);
   EXPECT_NULL(conf->global.motd_file);
   EXPECT_NULL(conf->global.address);
+  EXPECT_EQ_INT(conf->global.max_connections, DAEMON_CONF_DEFAULT_MAX_CONNECTIONS);
+  EXPECT_EQ_INT(conf->global.auth_failure_delay_ms, DAEMON_CONF_DEFAULT_AUTH_FAILURE_DELAY_MS);
+  EXPECT_EQ_INT(conf->global.hosts_allow_count, 0);
+  EXPECT_EQ_INT(conf->global.hosts_deny_count, 0);
   EXPECT_EQ_INT(conf->module_count, 0);
   daemon_conf_free(conf);
 }
@@ -309,6 +314,18 @@ static void test_daemon_conf_dparam_override() {
   EXPECT_EQ_INT(daemon_conf_apply_dparam(conf, "port = 9000", err, sizeof(err)), 0);
   EXPECT_EQ_INT(conf->global.port, 9000);
 
+  EXPECT_EQ_INT(daemon_conf_apply_dparam(conf, "max connections=7", err, sizeof(err)), 0);
+  EXPECT_EQ_INT(conf->global.max_connections, 7);
+  EXPECT_EQ_INT(daemon_conf_apply_dparam(conf, "AUTH FAILURE DELAY=1500", err, sizeof(err)), 0);
+  EXPECT_EQ_INT(conf->global.auth_failure_delay_ms, 1500);
+  EXPECT_EQ_INT(
+      daemon_conf_apply_dparam(conf, "hosts allow=127.0.0.1,10.0.0.0/8", err, sizeof(err)), 0);
+  EXPECT_EQ_INT(conf->global.hosts_allow_count, 2);
+  /* A later --dparam replaces the list (an override must be able to narrow). */
+  EXPECT_EQ_INT(daemon_conf_apply_dparam(conf, "hosts allow=127.0.0.1", err, sizeof(err)), 0);
+  EXPECT_EQ_INT(conf->global.hosts_allow_count, 1);
+  EXPECT_EQ_STR(conf->global.hosts_allow[0], "127.0.0.1");
+
   EXPECT_EQ_INT(daemon_conf_apply_dparam(conf, "port=notaport", err, sizeof(err)), -1);
   EXPECT_EQ_INT(daemon_conf_apply_dparam(conf, "bogus=1", err, sizeof(err)), -1);
   EXPECT_TRUE(strstr(err, "unknown global key") != NULL);
@@ -320,6 +337,161 @@ static void test_daemon_conf_dparam_override() {
   daemon_conf_free(conf);
 }
 
+/* Each `auth users` entry is validated with the same username rule as the
+ * credential store, so invisible whitespace/control characters can never make
+ * an exact strcmp match ambiguous. */
+static void test_daemon_conf_auth_users_validated() {
+  char* path;
+  char err[256];
+  const DaemonConf* conf;
+
+  EXPECT_EQ_INT(write_conf("[m]\npath = /x\nauth users = alice, bad user\n", &path), 0);
+  conf = daemon_conf_load(path, err, sizeof(err));
+  free(path);
+  EXPECT_NULL(conf);
+  EXPECT_TRUE(strstr(err, "invalid 'auth users' entry") != NULL);
+
+  EXPECT_EQ_INT(write_conf("[m]\npath = /x\nauth users = good\tbad\n", &path), 0);
+  conf = daemon_conf_load(path, err, sizeof(err));
+  free(path);
+  EXPECT_NULL(conf);
+  EXPECT_TRUE(strstr(err, "invalid 'auth users' entry") != NULL);
+
+  /* An over-long name exceeds CREDENTIAL_MAX_USER_LEN and is rejected. */
+  {
+    char body[CREDENTIAL_MAX_USER_LEN + 128];
+    int n = snprintf(body, sizeof(body), "[m]\npath = /x\nauth users = ");
+    memset(body + n, 'a', CREDENTIAL_MAX_USER_LEN + 1);
+    body[n + CREDENTIAL_MAX_USER_LEN + 1] = '\n';
+    body[n + CREDENTIAL_MAX_USER_LEN + 2] = '\0';
+    EXPECT_EQ_INT(write_conf(body, &path), 0);
+    conf = daemon_conf_load(path, err, sizeof(err));
+    free(path);
+    EXPECT_NULL(conf);
+    EXPECT_TRUE(strstr(err, "invalid 'auth users' entry") != NULL);
+  }
+
+  /* Empty entries between commas are skipped, not treated as invalid. */
+  EXPECT_EQ_INT(write_conf("[m]\npath = /x\nauth users = alice,, bob\n", &path), 0);
+  DaemonConf* ok_conf = daemon_conf_load(path, err, sizeof(err));
+  free(path);
+  EXPECT_NOT_NULL(ok_conf);
+  EXPECT_EQ_INT(ok_conf->modules[0].auth_user_count, 2);
+  EXPECT_EQ_STR(ok_conf->modules[0].auth_users[0], "alice");
+  EXPECT_EQ_STR(ok_conf->modules[0].auth_users[1], "bob");
+  daemon_conf_free(ok_conf);
+}
+
+/* Wave 3 daemon hardening: configurable global/per-module connection caps,
+ * auth-failure throttle and host access lists parse strictly (valid values are
+ * stored, malformed values fail the whole load). */
+static void test_daemon_conf_limits_and_hosts_parse() {
+  char* path;
+  char err[256];
+  EXPECT_EQ_INT(write_conf("max connections = 25\n"
+                           "auth failure delay = 0\n"
+                           "hosts allow = 10.0.0.0/8, 192.168.1.0/24\n"
+                           "hosts deny = 192.168.0.1 2001:db8::/32\n"
+                           "\n"
+                           "[m]\n"
+                           "path = /x\n"
+                           "max connections = 3\n"
+                           "hosts allow = 127.0.0.1\n"
+                           "hosts deny = *\n",
+                           &path),
+                0);
+  DaemonConf* conf = daemon_conf_load(path, err, sizeof(err));
+  free(path);
+  EXPECT_NOT_NULL(conf);
+  EXPECT_EQ_INT(conf->global.max_connections, 25);
+  EXPECT_EQ_INT(conf->global.auth_failure_delay_ms, 0);
+  EXPECT_EQ_INT(conf->global.hosts_allow_count, 2);
+  EXPECT_EQ_STR(conf->global.hosts_allow[0], "10.0.0.0/8");
+  EXPECT_EQ_STR(conf->global.hosts_allow[1], "192.168.1.0/24");
+  EXPECT_EQ_INT(conf->global.hosts_deny_count, 2);
+  EXPECT_EQ_STR(conf->global.hosts_deny[0], "192.168.0.1");
+  EXPECT_EQ_STR(conf->global.hosts_deny[1], "2001:db8::/32");
+  EXPECT_EQ_INT(conf->modules[0].max_connections, 3);
+  EXPECT_EQ_INT(conf->modules[0].hosts_allow_count, 1);
+  EXPECT_EQ_STR(conf->modules[0].hosts_allow[0], "127.0.0.1");
+  EXPECT_EQ_INT(conf->modules[0].hosts_deny_count, 1);
+  EXPECT_EQ_STR(conf->modules[0].hosts_deny[0], "*");
+  daemon_conf_free(conf);
+
+  const char* bad_values[] = {
+      "max connections = 0\n",         "max connections = -1\n",
+      "max connections = abc\n",       "auth failure delay = -1\n",
+      "auth failure delay = 70000\n",  "auth failure delay = soon\n",
+      "hosts allow = 10.0.0.0/99\n",   "hosts deny = 2001:db8::/129\n",
+      "hosts allow = *.example.com\n", "hosts deny = not-an-ip\n",
+  };
+  for (size_t i = 0; i < sizeof(bad_values) / sizeof(bad_values[0]); i++) {
+    EXPECT_EQ_INT(write_conf(bad_values[i], &path), 0);
+    const DaemonConf* rejected = daemon_conf_load(path, err, sizeof(err));
+    free(path);
+    EXPECT_NULL(rejected);
+  }
+
+  /* The same strictness applies inside a module section. */
+  const char* bad_module[] = {
+      "[m]\npath = /x\nmax connections = 0\n",
+      "[m]\npath = /x\nhosts allow = 10.0.0.0/40\n",
+      "[m]\npath = /x\nhosts deny = 999.1.1.1/8\n",
+  };
+  for (size_t i = 0; i < sizeof(bad_module) / sizeof(bad_module[0]); i++) {
+    EXPECT_EQ_INT(write_conf(bad_module[i], &path), 0);
+    const DaemonConf* rejected = daemon_conf_load(path, err, sizeof(err));
+    free(path);
+    EXPECT_NULL(rejected);
+    EXPECT_TRUE(strstr(err, "invalid") != NULL);
+  }
+
+  /* An empty hosts list is not an error (no patterns are added). */
+  EXPECT_EQ_INT(write_conf("hosts allow = \n[m]\npath = /x\n", &path), 0);
+  conf = daemon_conf_load(path, err, sizeof(err));
+  free(path);
+  EXPECT_NOT_NULL(conf);
+  EXPECT_EQ_INT(conf->global.hosts_allow_count, 0);
+  daemon_conf_free(conf);
+}
+
+static void test_daemon_hosts_allowed() {
+  /* Pattern forms. */
+  EXPECT_TRUE(daemon_host_pattern_match("*", "203.0.113.9"));
+  EXPECT_TRUE(daemon_host_pattern_match("10.0.0.1", "10.0.0.1"));
+  EXPECT_FALSE(daemon_host_pattern_match("10.0.0.1", "10.0.0.2"));
+  EXPECT_TRUE(daemon_host_pattern_match("10.0.0.0/8", "10.255.1.2"));
+  EXPECT_FALSE(daemon_host_pattern_match("10.0.0.0/8", "11.0.0.1"));
+  EXPECT_TRUE(daemon_host_pattern_match("2001:db8::/32", "2001:db8:1234::5"));
+  EXPECT_FALSE(daemon_host_pattern_match("2001:db8::/32", "2001:db9::1"));
+  EXPECT_TRUE(daemon_host_pattern_match("::1", "::1"));
+  EXPECT_FALSE(daemon_host_pattern_match("::1", "::2"));
+  EXPECT_TRUE(daemon_host_pattern_match("*.example.com", "host.example.com"));
+  EXPECT_FALSE(daemon_host_pattern_match("*.example.com", "example.org"));
+  EXPECT_FALSE(daemon_host_pattern_match(NULL, "10.0.0.1"));
+  EXPECT_FALSE(daemon_host_pattern_match("10.0.0.1", NULL));
+  EXPECT_FALSE(daemon_host_pattern_match("", "10.0.0.1"));
+
+  char* allow[] = {"10.0.0.0/8"};
+  char* deny[] = {"10.0.0.1"};
+  /* Deny takes precedence over a matching allow. */
+  EXPECT_FALSE(daemon_hosts_allowed("10.0.0.1", allow, 1, deny, 1));
+  EXPECT_TRUE(daemon_hosts_allowed("10.0.0.2", allow, 1, deny, 1));
+  /* A non-empty allow list rejects a peer that matches none of its entries. */
+  EXPECT_FALSE(daemon_hosts_allowed("192.168.1.1", allow, 1, NULL, 0));
+  /* With only a deny list, everything not denied is accepted. */
+  EXPECT_TRUE(daemon_hosts_allowed("192.168.1.1", NULL, 0, deny, 1));
+  EXPECT_FALSE(daemon_hosts_allowed("10.0.0.1", NULL, 0, deny, 1));
+  /* No lists at all accepts everyone. */
+  EXPECT_TRUE(daemon_hosts_allowed("192.168.1.1", NULL, 0, NULL, 0));
+  /* An unprovable peer (NULL) never matches an allow list. */
+  EXPECT_FALSE(daemon_hosts_allowed(NULL, allow, 1, NULL, 0));
+
+  EXPECT_FALSE(daemon_hosts_restricted(NULL, 0, NULL, 0));
+  EXPECT_TRUE(daemon_hosts_restricted(allow, 1, NULL, 0));
+  EXPECT_TRUE(daemon_hosts_restricted(NULL, 0, deny, 1));
+}
+
 static void test_daemon_module_name_valid() {
   EXPECT_TRUE(daemon_module_name_valid("backup"));
   EXPECT_TRUE(daemon_module_name_valid("Backup_2"));
@@ -351,5 +523,8 @@ void test_daemon_conf() {
   test_daemon_conf_missing_file_rejected();
   test_daemon_conf_find_module();
   test_daemon_conf_dparam_override();
+  test_daemon_conf_auth_users_validated();
+  test_daemon_conf_limits_and_hosts_parse();
+  test_daemon_hosts_allowed();
   test_daemon_module_name_valid();
 }

tests/test_file.c

@@ -1370,6 +1370,76 @@ static void test_dir_time_list() {
   rmdir(root);
 }
 
+/* A hostile sender can stream unbounded STATUS_DIR_TIMES frames; the
+ * accumulator must bound the CUMULATIVE path bytes (not just one frame) and
+ * reject the add that would cross the cap, leaving the list untouched. */
+static void test_dir_time_list_cap() {
+  DirTimeList list;
+  dir_time_list_init(&list);
+  EXPECT_EQ_INT((int)list.bytes, 0);
+  FileMetadata metadata = {.mtime_sec = 1, .mtime_nsec = 0};
+
+  size_t path_len = MAX_STRING_SIZE - 1;
+  char* path = malloc(path_len + 1);
+  EXPECT_NOT_NULL(path);
+  memset(path, 'a', path_len);
+  path[path_len] = '\0';
+
+  bool rejected = false;
+  for (size_t i = 0; i < MAX_DIR_TIME_ENTRIES + 1 && !rejected; i++) {
+    size_t before_count = list.count;
+    size_t before_bytes = list.bytes;
+    if (!dir_time_list_add(&list, path, &metadata)) {
+      rejected = true;
+      /* The rejected add must not have partially mutated the list. */
+      EXPECT_TRUE(list.count == before_count);
+      EXPECT_TRUE(list.bytes == before_bytes);
+    } else {
+      EXPECT_TRUE(list.count == before_count + 1);
+      EXPECT_TRUE(list.bytes == before_bytes + path_len + sizeof(FileMetadata) + sizeof(char*));
+    }
+  }
+  EXPECT_TRUE(rejected);
+  EXPECT_TRUE(list.count <= MAX_DIR_TIME_ENTRIES);
+  EXPECT_TRUE(list.bytes <= MAX_DIR_TIME_BYTES);
+
+  /* The retained entries are still intact and freeable after the rejection. */
+  EXPECT_TRUE(list.count > 0);
+  EXPECT_TRUE(strcmp(list.paths[0], path) == 0);
+  dir_time_list_free(&list);
+  EXPECT_EQ_INT((int)list.bytes, 0);
+  free(path);
+}
+
+/* receive_incremental_check must reject an empty check_path; every other
+ * receive path rejects path[0]=='\0'.  Feed the check header (empty wire path
+ * + size/mtime/nsec) and assert the check is refused without being skipped. */
+static void test_receive_incremental_check_empty_path() {
+  Config* cfg = config_create();
+  EXPECT_NOT_NULL(cfg);
+  cfg->checksum = false;
+
+  int p[2];
+  EXPECT_EQ_INT(pipe(p), 0);
+  size_t wire_len = 0;
+  unsigned long long check_size = 0;
+  long long check_mtime = 0;
+  long long check_mtime_nsec = 0;
+  EXPECT_TRUE(send_n_data(p[1], &wire_len, sizeof(wire_len)));
+  EXPECT_TRUE(send_n_data(p[1], &check_size, sizeof(check_size)));
+  EXPECT_TRUE(send_n_data(p[1], &check_mtime, sizeof(check_mtime)));
+  EXPECT_TRUE(send_n_data(p[1], &check_mtime_nsec, sizeof(check_mtime_nsec)));
+
+  bool skipped = true;
+  const File* file = receive_incremental_check(p[0], cfg, &skipped);
+  EXPECT_NULL(file);
+  EXPECT_FALSE(skipped);
+
+  close(p[0]);
+  close(p[1]);
+  config_delete(cfg);
+}
+
 /* -K/--keep-dirlinks secure open: with an authorized root, a destination path
  * component that is a symlink to an IN-ROOT directory is used as that directory
  * (its referent is opened through a relative O_NOFOLLOW walk from the root fd,
@@ -1531,6 +1601,8 @@ void test_file() {
   }
   test_file_metadata_create();
   test_dir_time_list();
+  test_dir_time_list_cap();
+  test_receive_incremental_check_empty_path();
   test_keep_dirlinks_secure_open();
   test_inplace_overwrite_clears_special_mode_bits();
   test_inplace_overwrite_metadata_strips_special_bits();

tests/test_log.c

@@ -1,7 +1,9 @@
 #include "test_log.h"
 #include "log.h"
 #include "test_utils.h"
+#include <fcntl.h>
 #include <string.h>
+#include <threads.h>
 #include <unistd.h>
 
 /* Test default log level: WARNING and ERROR should print, DEBUG and INFO should not.
@@ -147,6 +149,118 @@ static void test_log_debug_enabled_matches_gate() {
   set_log_debug_flags(LOG_DEBUG_ALL);
 }
 
+#define LOG_CONCURRENCY_THREADS 8
+#define LOG_CONCURRENCY_LINES 250
+
+typedef struct {
+  int id;
+} LogConcurrencyArg;
+
+static int log_concurrency_worker(void* context) {
+  LogConcurrencyArg* arg = context;
+  for (int i = 0; i < LOG_CONCURRENCY_LINES; i++) {
+    log_message(LOG_LEVEL_WARNING, "worker %d line %d", arg->id, i);
+  }
+  return 0;
+}
+
+static int count_substring(const char* haystack, const char* needle) {
+  int count = 0;
+  size_t needle_length = strlen(needle);
+  const char* cursor = haystack;
+  while ((cursor = strstr(cursor, needle)) != NULL) {
+    count++;
+    cursor += needle_length;
+  }
+  return count;
+}
+
+/* Concurrent log_message() calls from many threads must never interleave a
+ * single line: every emitted line has exactly one timestamp prefix and one
+ * body.  Before write_message() was serialized, the three separate fprintf
+ * calls (prefix, body, newline) let lines tear. */
+static void test_log_concurrent_no_torn_lines(void) {
+  FILE* fp = tmpfile();
+  EXPECT_NOT_NULL(fp);
+
+  /* Mute the console mirror so the workers don't flood the test output. */
+  fflush(stdout);
+  fflush(stderr);
+  int saved_stdout = dup(STDOUT_FILENO);
+  int saved_stderr = dup(STDERR_FILENO);
+  int null_fd = open("/dev/null", O_WRONLY);
+  EXPECT_TRUE(saved_stdout >= 0);
+  EXPECT_TRUE(saved_stderr >= 0);
+  EXPECT_TRUE(null_fd >= 0);
+  EXPECT_TRUE(dup2(null_fd, STDOUT_FILENO) >= 0);
+  EXPECT_TRUE(dup2(null_fd, STDERR_FILENO) >= 0);
+  close(null_fd);
+
+  set_log_level(LOG_LEVEL_WARNING);
+  log_set_stderr_mode(LOG_STDERR_ERRORS);
+  log_set_file(fp);
+
+  thrd_t threads[LOG_CONCURRENCY_THREADS];
+  LogConcurrencyArg args[LOG_CONCURRENCY_THREADS];
+  int created = 0;
+  for (int i = 0; i < LOG_CONCURRENCY_THREADS; i++) {
+    args[i].id = i;
+    if (thrd_create(&threads[i], log_concurrency_worker, &args[i]) != thrd_success)
+      break;
+    created++;
+  }
+  for (int i = 0; i < created; i++) {
+    thrd_join(threads[i], NULL);
+  }
+
+  log_set_file(NULL);
+  fflush(fp);
+
+  fflush(stdout);
+  fflush(stderr);
+  dup2(saved_stdout, STDOUT_FILENO);
+  dup2(saved_stderr, STDERR_FILENO);
+  close(saved_stdout);
+  close(saved_stderr);
+
+  rewind(fp);
+  char line[512];
+  int total_lines = 0;
+  int malformed_lines = 0;
+  bool saw_missing_newline = false;
+  while (fgets(line, sizeof(line), fp) != NULL) {
+    size_t length = strlen(line);
+    if (length == 0 || line[length - 1] != '\n')
+      saw_missing_newline = true;
+    if (strncmp(line, "20", 2) != 0 || count_substring(line, "[WARN]: worker ") != 1)
+      malformed_lines++;
+    total_lines++;
+  }
+  fclose(fp);
+
+  EXPECT_EQ_INT(created, LOG_CONCURRENCY_THREADS);
+  EXPECT_FALSE(saw_missing_newline);
+  EXPECT_EQ_INT(malformed_lines, 0);
+  EXPECT_EQ_INT(total_lines, LOG_CONCURRENCY_THREADS * LOG_CONCURRENCY_LINES);
+  log_set_stderr_mode(LOG_STDERR_ERRORS);
+}
+
+/* Detaching the logger from a FILE* before it is closed must leave the logging
+ * subsystem safe: later calls must not touch the freed handle. */
+static void test_log_set_file_null_before_fclose(void) {
+  FILE* fp = tmpfile();
+  EXPECT_NOT_NULL(fp);
+
+  set_log_level(LOG_LEVEL_ERROR);
+  log_set_file(fp);
+  log_message(LOG_LEVEL_ERROR, "line before detach");
+  log_set_file(NULL);
+  fclose(fp);
+
+  log_message(LOG_LEVEL_ERROR, "line after close");
+  EXPECT_TRUE(true);
+}
+
 void test_log() {
   test_log_message_debug();
   test_log_message_info();
@@ -159,4 +273,6 @@ void test_log() {
   test_log_stderr_mode_all();
   test_log_message_formats();
   test_log_debug_enabled_matches_gate();
+  test_log_concurrent_no_torn_lines();
+  test_log_set_file_null_before_fclose();
 }

tests/test_protocol.c

@@ -412,6 +412,35 @@ static void test_protocol_accounting_release_does_not_underflow() {
   protocol_session_unbind();
 }
 
+static void test_protocol_session_io_timeout() {
+  /* Default is the built-in 60 s window; the setter stores exactly what it is
+   * given (<= 0 means "fall back to the default") so callers can propagate
+   * --timeout without special-casing 0. */
+  ProtocolSession session;
+  protocol_session_init(&session, -1, -1);
+  EXPECT_EQ_INT(session.io_timeout_sec, 60);
+
+  protocol_session_set_io_timeout(&session, 120);
+  EXPECT_EQ_INT(session.io_timeout_sec, 120);
+  protocol_session_set_io_timeout(&session, 0);
+  EXPECT_EQ_INT(session.io_timeout_sec, 0);
+  /* A NULL session is a no-op, not a crash. */
+  protocol_session_set_io_timeout(NULL, 5);
+
+  /* A short per-session deadline must actually bound a non-responsive read:
+   * with no writer the poll waits for the configured 1 s and then fails,
+   * rather than the built-in 60 s. */
+  int p[2];
+  EXPECT_EQ_INT(pipe(p), 0);
+  ProtocolSession timed;
+  protocol_session_init(&timed, p[0], p[1]);
+  protocol_session_set_io_timeout(&timed, 1);
+  char buf[4];
+  EXPECT_FALSE(protocol_receive_n_data(&timed, buf, sizeof(buf)));
+  close(p[0]);
+  close(p[1]);
+}
+
 static void test_send_receive_status_timed() {
   int p[2];
   EXPECT_EQ_INT(pipe(p), 0);
@@ -440,6 +469,7 @@ void test_protocol() {
   test_send_receive_data();
   test_send_receive_int();
   test_send_receive_status();
+  test_protocol_session_io_timeout();
   test_send_receive_status_timed();
   test_receive_n_data_truncated();
   test_receive_str_truncated();

tests/test_receiver_timeout.c

@@ -0,0 +1,97 @@
+#include "test_receiver_timeout.h"
+
+#include "protocol.h"
+#include "receiver.h"
+#include "test_utils.h"
+#include <sys/socket.h>
+#include <time.h>
+#include <unistd.h>
+
+static bool sink_discard(File* file, void* context) {
+  (void)context;
+  file_destroy(file);
+  return true;
+}
+
+/* The idle/session bound is a pure function of three monotonic timestamps, so
+ * it can be exercised deterministically without sleeping an hour.  A tiny
+ * overridden limit covers the same arithmetic the loop uses. */
+static void test_receiver_time_limit_predicate() {
+  receiver_set_time_limits(10, 100);
+  struct timespec start = {.tv_sec = 1000, .tv_nsec = 0};
+  struct timespec fresh = {.tv_sec = 1000, .tv_nsec = 0};
+  struct timespec just_idle = {.tv_sec = 1009, .tv_nsec = 0}; /* 9 s no progress */
+  struct timespec idle = {.tv_sec = 1010, .tv_nsec = 0};      /* 10 s no progress */
+  struct timespec just_wall = {.tv_sec = 1099, .tv_nsec = 0};
+  struct timespec wall = {.tv_sec = 1100, .tv_nsec = 0};    /* 100 s session */
+  struct timespec wp_just = {.tv_sec = 1098, .tv_nsec = 0}; /* idle 1 s */
+  struct timespec wp_wall = {.tv_sec = 1099, .tv_nsec = 0}; /* idle 1 s */
+
+  EXPECT_FALSE(receiver_time_limit_exceeded(&start, &fresh, &fresh));
+  EXPECT_FALSE(receiver_time_limit_exceeded(&start, &fresh, &just_idle));
+  EXPECT_TRUE(receiver_time_limit_exceeded(&start, &fresh, &idle));
+  EXPECT_FALSE(receiver_time_limit_exceeded(&start, &wp_just, &just_wall));
+  EXPECT_TRUE(receiver_time_limit_exceeded(&start, &wp_wall, &wall));
+
+  /* Reset restores the generous production defaults (1 h idle / 24 h total). */
+  receiver_reset_time_limits();
+  struct timespec under_hour = {.tv_sec = 1000 + 3599, .tv_nsec = 0};
+  EXPECT_FALSE(receiver_time_limit_exceeded(&start, &start, &under_hour));
+  receiver_reset_time_limits();
+}
+
+/* Drive the actual receive loop with a test-only idle limit of 0 so the very
+ * first keepalive is rejected: this exercises the loop's abort path (log +
+ * STATUS_ERROR + return -1) with no timing dependence. */
+static void test_receiver_aborts_idle_keepalive() {
+  receiver_set_time_limits(0, 3600);
+  int sv[2];
+  EXPECT_EQ_INT(socketpair(AF_UNIX, SOCK_STREAM, 0, sv), 0);
+  Config* config = config_create();
+  EXPECT_NOT_NULL(config);
+  ReceiverSink sink = {.store_file = sink_discard,
+                       .context = NULL,
+                       .send_error = true,
+                       .send_success = false,
+                       .send_success_frame = NULL};
+
+  /* Bind an explicit session so the fd-based receive helpers use the
+   * socketpair rather than any transport left over from an earlier test. */
+  ProtocolSession session;
+  protocol_session_init(&session, sv[1], sv[1]);
+  protocol_session_bind(&session);
+
+  Status keepalive = STATUS_KEEPALIVE;
+  ssize_t wrote = write(sv[0], &keepalive, sizeof(keepalive));
+  int result = -2;
+  if (wrote == (ssize_t)sizeof(keepalive))
+    result = receiver_process_pending(config, sv[1], &sink, NULL);
+  Status reply = STATUS_OK;
+  ssize_t got = -1;
+  if (result == -1)
+    got = read(sv[0], &reply, sizeof(reply));
+
+  /* Tear down the binding/descriptors BEFORE asserting: an EXPECT_* failure
+   * returns immediately, and a dangling bound_session would poison later
+   * fd-level protocol I/O tests. */
+  protocol_session_unbind();
+  config_delete(config);
+  close(sv[0]);
+  close(sv[1]);
+  receiver_reset_time_limits();
+
+  EXPECT_EQ_INT((int)wrote, (int)sizeof(keepalive));
+  EXPECT_EQ_INT(result, -1);
+  EXPECT_EQ_INT((int)got, (int)sizeof(reply));
+  EXPECT_EQ_INT((int)reply, (int)STATUS_ERROR);
+}
+
+void test_receiver_timeout(void) {
+  /* EXPECT_* returns from the current function on failure, so reset the
+   * process-global limits around the subtests (and again after) to guarantee a
+   * failed assertion cannot leave the receiver aborted for later tests. */
+  receiver_reset_time_limits();
+  test_receiver_time_limit_predicate();
+  test_receiver_aborts_idle_keepalive();
+  receiver_reset_time_limits();
+}

tests/test_receiver_timeout.h

@@ -0,0 +1,6 @@
+#ifndef TEST_RECEIVER_TIMEOUT_H
+#define TEST_RECEIVER_TIMEOUT_H
+
+void test_receiver_timeout(void);
+
+#endif

tests/test_scanner.c

@@ -1317,6 +1317,58 @@ static void test_scanner_captures_directory_times() {
   rmdir(root);
 }
 
+/* Ownership guard for chunk_data_to_chunk(): a returned Chunk owns its File
+ * objects, so destroying the chunk must free them exactly once and the scanner
+ * must never free them again.  chunk_size = 1 forces the mid-directory
+ * conversion branch (chunk_data_size > chunk_size) for every file, and the
+ * chunk is destroyed immediately, catching a double free / use-after-free under
+ * ASan if ownership transfer regressed.
+ *
+ * The failure path (array_list_to_array() or chunk_create() returning NULL) is
+ * not reachable from a unit test: both allocate through protocol_alloc(), and
+ * each allocation they perform is no larger than the array_list allocations
+ * that already succeeded while building the list (array_list_to_array() copies
+ * exactly `size` pointers, which never exceeds the capacity just grown, and
+ * sizeof(Chunk) is far below the initial 100-entry item array).  Binding a
+ * small --max-alloc session therefore always fails *before* this function, not
+ * inside it, so fault injection cannot isolate these paths. */
+static void test_scanner_chunk_ownership() {
+  const char* dir = "test_scan_ownership";
+  const char* file1 = "test_scan_ownership/a.txt";
+  const char* file2 = "test_scan_ownership/b.txt";
+  const char* file3 = "test_scan_ownership/c.txt";
+
+  EXPECT_EQ_INT(mkdir(dir, 0755), 0);
+  create_test_file(file1, "aaaa");
+  create_test_file(file2, "bbbb");
+  create_test_file(file3, "cccc");
+
+  ScannerOptions options = {0};
+  options.chunk_size = 1;
+  DirectoryScanner* scanner = directory_scanner_create_with_options(dir, &options);
+  EXPECT_NOT_NULL(scanner);
+
+  int chunks = 0;
+  int files = 0;
+  Chunk* chunk;
+  while ((chunk = directory_scanner_next(scanner)) != NULL) {
+    chunks++;
+    files += chunk->element_count;
+    EXPECT_EQ_INT(chunk->element_count, 1);
+    chunk_destroy(chunk);
+    EXPECT_FALSE(directory_scanner_failed(scanner));
+  }
+  EXPECT_EQ_INT(files, 3);
+  EXPECT_EQ_INT(chunks, 3);
+  EXPECT_FALSE(directory_scanner_failed(scanner));
+
+  directory_scanner_destroy(scanner);
+  unlink(file1);
+  unlink(file2);
+  unlink(file3);
+  rmdir(dir);
+}
+
 void test_scanner() {
   test_scanner_single_file();
   test_scanner_multiple_files();
@@ -1353,4 +1405,5 @@ void test_scanner() {
   test_dirs_files_from();
   test_files_from_relative_send_path();
   test_scanner_captures_directory_times();
+  test_scanner_chunk_ownership();
 }

tests/test_shared_utils.c

@@ -356,6 +356,69 @@ static void test_loopback_helpers() {
   close(listener);
 }
 
+/* The daemon host ACL reads the numeric peer address through
+ * utils_fd_peer_ip.  A real loopback TCP peer reports "127.0.0.1"; a pipe or an
+ * AF_UNIX socketpair has no INET peer and must return false with an empty
+ * buffer (the fail-closed "cannot tell" result). */
+static void test_fd_peer_ip() {
+  char ip[INET6_ADDRSTRLEN];
+  EXPECT_FALSE(utils_fd_peer_ip(-1, ip, sizeof(ip)));
+  EXPECT_EQ_STR(ip, "");
+  EXPECT_FALSE(utils_fd_peer_ip(-1, NULL, 0));
+
+  int pipe_fds[2];
+  EXPECT_EQ_INT(pipe(pipe_fds), 0);
+  EXPECT_FALSE(utils_fd_peer_ip(pipe_fds[0], ip, sizeof(ip)));
+  EXPECT_EQ_STR(ip, "");
+  close(pipe_fds[0]);
+  close(pipe_fds[1]);
+
+  int pair_fds[2];
+  EXPECT_EQ_INT(socketpair(AF_UNIX, SOCK_STREAM, 0, pair_fds), 0);
+  EXPECT_FALSE(utils_fd_peer_ip(pair_fds[0], ip, sizeof(ip)));
+  EXPECT_EQ_STR(ip, "");
+  close(pair_fds[0]);
+  close(pair_fds[1]);
+
+  int listener = socket(AF_INET, SOCK_STREAM, 0);
+  EXPECT_TRUE(listener >= 0);
+  struct sockaddr_in bind_addr;
+  memset(&bind_addr, 0, sizeof(bind_addr));
+  bind_addr.sin_family = AF_INET;
+  bind_addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
+  bind_addr.sin_port = 0;
+  EXPECT_EQ_INT(bind(listener, (const struct sockaddr*)&bind_addr, sizeof(bind_addr)), 0);
+  EXPECT_EQ_INT(listen(listener, 1), 0);
+  socklen_t addr_len = sizeof(bind_addr);
+  EXPECT_EQ_INT(getsockname(listener, (struct sockaddr*)&bind_addr, &addr_len), 0);
+  int dialer = socket(AF_INET, SOCK_STREAM, 0);
+  EXPECT_TRUE(dialer >= 0);
+  EXPECT_EQ_INT(connect(dialer, (const struct sockaddr*)&bind_addr, sizeof(bind_addr)), 0);
+  int accepted = accept(listener, NULL, NULL);
+  EXPECT_TRUE(accepted >= 0);
+  EXPECT_TRUE(utils_fd_peer_ip(accepted, ip, sizeof(ip)));
+  EXPECT_EQ_STR(ip, "127.0.0.1");
+
+  /* utils_sockaddr_to_string includes the port for a real peer. */
+  struct sockaddr_storage peer;
+  socklen_t peer_len = sizeof(peer);
+  EXPECT_EQ_INT(getpeername(accepted, (struct sockaddr*)&peer, &peer_len), 0);
+  char peer_string[128];
+  EXPECT_TRUE(
+      utils_sockaddr_to_string((const struct sockaddr*)&peer, peer_string, sizeof(peer_string)));
+  EXPECT_TRUE(strncmp(peer_string, "127.0.0.1:", strlen("127.0.0.1:")) == 0);
+  close(accepted);
+  close(dialer);
+  close(listener);
+
+  /* A non-INET family formats to "unknown" at the call site, not a bogus IP. */
+  struct sockaddr sa_unix;
+  memset(&sa_unix, 0, sizeof(sa_unix));
+  sa_unix.sa_family = AF_UNIX;
+  EXPECT_FALSE(utils_sockaddr_to_string(&sa_unix, peer_string, sizeof(peer_string)));
+  EXPECT_EQ_STR(peer_string, "");
+}
+
 void test_shared_utils() {
   test_walker_removes_extras_keeps_manifest_and_protected();
   test_walker_max_delete_exceeded_deletes_nothing();
@@ -363,6 +426,7 @@ void test_shared_utils() {
   test_walker_unlimited_deletes_all();
   test_walker_hard_bound_all_or_nothing();
   test_loopback_helpers();
+  test_fd_peer_ip();
 
   /* --append / --append-verify tail-resume math: a resume is eligible only for
      a shorter existing destination, and the tail length is then the difference. */