Revert "Merge pull request 'Merge all 5 batch PRs: security, CLI features, protocol, performance, tests/docs' (#143) from merge-all-v2 into main"

This reverts commit 29f4f8cde6, reversing changes made to c6bf7bb84e.
2026-07-29 18:10:01 +02:00
parent 29f4f8cde6
commit d3dca6c2a5
33 changed files with 1144 additions and 1113 deletions
@@ -5,6 +5,3 @@ __pycache__/
 build-asan
 coverage.info
 build-*/
-build2/
-build3/
-build_docker2/
@@ -5,26 +5,17 @@ A high-performance file synchronization system with SSH and TCP transport, TLS e
 ## Technical Overview

 1. **Dual transport**: custom TCP client-server or SSH subprocess (rsync-style `user@host:/path`)
-2. **TLS encryption**: OpenSSL-based TLS 1.2+ for encrypted TCP connections with optional CA verification
+2. **TLS encryption**: OpenSSL-based TLS 1.2+ for encrypted TCP connections
 3. **Chunked file transfer**: files grouped into configurable-size chunks (default ~10 MB)
 4. **Streaming zstd compression** (levels 1–22) using `ZSTD_compressStream2`
 5. **Multithreading**: producer-consumer pipeline with thread-safe queues (scanner → loader → sender)
 6. **Incremental sync**: skip files unchanged since last transfer (compares size + mtime)
-7. **Batch incremental**: send incremental checks in batched groups for reduced round-trips
-8. **Metadata preservation**: `mode`, `uid`, `gid`, `mtime` restored on disk when enabled
-9. **`sendfile()` zero-copy** on TCP (~2× faster on loopback)
-10. **SSH ControlMaster** for connection reuse across repeated invocations
-11. **Bandwidth limiting**: token-bucket throttling (`--bwlimit`)
-12. **`--delete`**: receiver removes files not present in sender manifest
-13. **`--exclude` / `--include`**: glob-pattern filename filtering
-14. **Path traversal protection**: `..` sequences in file paths are rejected automatically
-15. **Connection limits**: server enforces maximum concurrent connections (default 100)
-16. **Keep-alive**: periodic `STATUS_KEEPALIVE` messages detect stalled connections
-17. **Abort handling**: `SIGINT` sends `STATUS_ABORT` for clean server-side teardown
-18. **Atomic writes**: received files are written to a temporary name then atomically renamed
-19. **Backup mode**: `--backup` preserves overwritten files with optional `--backup-dir`
-20. **Log file**: `--log-file` redirects log output to a file instead of stderr
-21. **Transfer statistics**: `--stats` prints summary of transferred bytes, files, and timing
+7. **Metadata preservation**: `mode`, `uid`, `gid`, `mtime` restored on disk when enabled
+8. **`sendfile()` zero-copy** on TCP (~2× faster on loopback)
+9. **SSH ControlMaster** for connection reuse across repeated invocations
+10. **Bandwidth limiting**: token-bucket throttling (`--bwlimit`)
+11. **`--delete`**: receiver removes files not present in sender manifest
+12. **`--exclude` / `--include`**: glob-pattern filename filtering

 ## System Architecture

@@ -34,33 +25,20 @@ A high-performance file synchronization system with SSH and TCP transport, TLS e
 - Streaming zstd compression with configurable level
 - Chunk serialization (compact binary format) or per-file transfer
 - Incremental transfer: sends file metadata to server, skips unchanged files
- Batch incremental: groups incremental checks to minimize round-trips
 - Manifests all sent paths when `--delete` is active
 - Sends via TCP `sendfile()` or SSH pipe
 - Optional progress display with throughput
 - Bandwidth limiting via token-bucket algorithm
- Configurable I/O and connection timeouts (`--timeout`, `--contimeout`)
- Quiet mode (`-q`/`--quiet`) suppresses all non-error output
- Backup overwritten files (`--backup`) with optional directory (`--backup-dir`)
- Transfer statistics summary (`--stats`)
- Maximum directory depth control (`--max-depth`)
- Log file output (`--log-file`)
- Configurable multithreaded queue size (`--queue-size`)
- Exclude patterns from file (`--exclude-from`)

 ### Server
 - TCP mode: listens on configurable port (default 8080); SSH mode: runs via `--stdio`
- TLS mode: wraps TCP connections with OpenSSL with optional CA verification
+- TLS mode: wraps TCP connections with OpenSSL
 - Receives and reassembles files
 - Decompresses (streaming zstd), deserializes, restores metadata
 - Handles incremental checks: compares size + mtime against destination files
- Handles batch incremental checks for reduced round-trips
 - Processes `STATUS_MANIFEST` for `--delete`: walks destination tree, removes extras
- Per-connection concurrency via `fork()` with configurable connection limit (default 100)
+- Per-connection concurrency via `fork()`
 - Thread pool for parallel processing
- Atomic writes: files written to `.tmp` path then atomically renamed on success
- Abort handling: cleanly shuts down on `STATUS_ABORT` from client
- Path traversal protection: rejects file paths containing `..`

 ## Protocol Details

@@ -74,11 +52,6 @@ A high-performance file synchronization system with SSH and TCP transport, TLS e
 | `STATUS_CHUNK` | Following data is a serialized chunk |
 | `STATUS_MANIFEST` | Following data is a file manifest (for `--delete`) |
 | `STATUS_CHECK` | Incremental check: client sends file path + size + mtime, server responds with OK (skip) or NEXT (send) |
-| `STATUS_CHECK_BATCH` | Batch incremental check: multiple file checks sent in one message |
-| `STATUS_KEEPALIVE` | Keep-alive heartbeat to detect stalled connections |
-| `STATUS_ABORT` | Abort signal: client interrupts, server cleans up and exits |
-| `STATUS_DELTA_SIGNATURE` | Delta sync: following data is a file signature (rsync-style rolling hash) |
-| `STATUS_DELTA_DATA` | Delta sync: following data is a delta patch for a file |

 ### Wire Format — Metadata

@@ -86,16 +59,12 @@ When `use_metadata` is enabled (`-M`), each file entry carries a 4-byte `present

 ### Transfer Flow
 ```
-Config → (STATUS_NEXT | STATUS_CHUNK | STATUS_CHECK | STATUS_CHECK_BATCH)* → [STATUS_MANIFEST] → STATUS_FINISHED → STATUS_OK
+Config → (STATUS_NEXT | STATUS_CHUNK | STATUS_CHECK)* → [STATUS_MANIFEST] → STATUS_FINISHED → STATUS_OK
 ```

-Keep-alive (`STATUS_KEEPALIVE`) may be sent at any point during the transfer. The receiver resets its inactivity timer on receipt. If no data arrives within the receive timeout, the connection is aborted.
-
-Abort (`STATUS_ABORT`) may be sent at any point. On receipt the server cleans up temporary files and exits the child process.
-
 ### Protocol Version

-`1.3.0` — server and client must match. Mismatch results in `STATUS_ERROR`.
+`1.1.0` — server and client must match. Mismatch results in `STATUS_ERROR`.

 ## Command-Line Arguments

@@ -114,26 +83,15 @@ Abort (`STATUS_ABORT`) may be sent at any point. On receipt the server cleans up
 | `-n, --dry-run` | Scan and print what would be transferred |
 | `-p <port>` | SSH port (default: 22) |
 | `-v, --verbose` | Enable debug logging |
-| `-q, --quiet` | Suppress all non-error output |
-| `--silent` | Alias for `--quiet` |
 | `--progress` | Show real-time transfer speed |
 | `--delete` | Delete files on receiver not present in source |
 | `--exclude <pattern>` | Exclude files matching glob pattern (repeatable) |
-| `--exclude-from <file>` | Read exclude patterns from a file (one per line) |
 | `--include <pattern>` | Only transfer files matching glob pattern (repeatable, whitelist) |
 | `--max-size <n>` | Skip files larger than n bytes |
 | `--min-size <n>` | Skip files smaller than n bytes |
 | `--incremental` | Skip files unchanged since last transfer (size + mtime). Auto-enables `--preserve`. Incompatible with `-s`. |
 | `--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) |
-| `--contimeout <sec>` | Connection timeout in seconds (default: 10) |
-| `--backup` | Backup existing destination files before overwriting |
-| `--backup-dir <dir>` | Target directory for backups (requires `--backup`) |
-| `--stats` | Print transfer statistics at end (bytes, files, timing) |
-| `--max-depth <n>` | Maximum directory depth to recurse (0 = unlimited, default: 0) |
-| `--log-file <path>` | Write log messages to file instead of stderr |
-| `--queue-size <n>` | Queue capacity for multithreaded mode (default: 100) |
 | `--source-dir <path>` | Source directory (overrides `FASTSYNC_SOURCE_DIR`) |
 | `--dest-dir <path>` | Server destination directory (overrides `FASTSYNC_DEST_DIR`) |
 | `--save-to-disk` | Write received files to disk |
@@ -164,12 +122,6 @@ Abort (`STATUS_ABORT`) may be sent at any point. On receipt the server cleans up
 | `FASTSYNC_SOURCE_DIR` | — | Source directory fallback |
 | `FASTSYNC_DEST_DIR` | — | Destination directory fallback |
 | `FASTSYNC_SAVE_TO_DISK` | `false` | Disk persistence fallback |
-| `FASTSYNC_SSH_PORT` | `22` | Default SSH port |
-| `FASTSYNC_SERVER_HOST` | `127.0.0.1` | Default server host |
-| `FASTSYNC_SERVER_PORT` | `8080` | Default server port |
-| `FASTSYNC_TLS_CERT` | — | Default TLS certificate path |
-| `FASTSYNC_TLS_KEY` | — | Default TLS private key path |
-| `FASTSYNC_TLS_CA` | — | Default TLS CA certificate path |

 ## Implementation Details

@@ -177,44 +129,21 @@ Abort (`STATUS_ABORT`) may be sent at any point. On receipt the server cleans up
 1. **Chunk** — collection of files (~10 MB total by default)
 2. **File** — path, content (`Data`), optional `FileMetadata` pointer
 3. **FileMetadata** — `mode`, `uid`, `gid`, `mtime_sec`, `mtime_nsec`
-4. **Config** — runtime parameters (transported over wire, TLS settings excluded). Includes `timeout`, `contimeout`, `quiet`, `backup`, `backup_dir`, `stats`, `max_depth`, `log_file`, `queue_size`.
+4. **Config** — runtime parameters (transported over wire, TLS settings excluded)
 5. **Queue** — thread-safe bounded queue with condition variables
-6. **DirectoryScanner** — recursive BFS traversal with exclude and include pattern support, max-depth enforcement
+6. **DirectoryScanner** — recursive BFS traversal with exclude and include pattern support

 ### Key Algorithms
-1. **File scanning** — BFS directory traversal; entries matched against exclude and include patterns, max-depth enforced
+1. **File scanning** — BFS directory traversal; entries matched against exclude and include patterns
 2. **Chunking** — files accumulated until `chunk_size` threshold, then flushed
 3. **Compression** — streaming zstd via `ZSTD_compressStream2` / `ZSTD_decompressStream`
-4. **Network protocol** — status-code-driven exchange with metadata packing, keep-alive, and abort support
-5. **Incremental check** — client sends `STATUS_CHECK` + path + size + mtime; server compares against destination. Can be batched via `STATUS_CHECK_BATCH` for reduced round-trips.
+4. **Network protocol** — status-code-driven exchange with metadata packing
+5. **Incremental check** — client sends `STATUS_CHECK` + path + size + mtime; server compares against destination
 6. **Bandwidth limiting** — token-bucket algorithm with `nanosleep` throttling on 64 KB write chunks
 7. **Metadata restoration** — `chmod()`, `chown()`, `utimensat()` on the receiving side
 8. **`--delete`** — sender tracks all sent paths; receiver walks destination tree and removes unlisted files/directories
 9. **SSH transport** — `socketpair()` + `fork()` + `execvp("ssh", ...)` with `ControlMaster` and port support
 10. **TLS transport** — OpenSSL `SSL_CTX` with TLS 1.2 minimum, optional CA verification, transparent `SSL_read`/`SSL_write` via `io_set_ssl()`
-11. **Path traversal protection** — `has_path_traversal()` rejects any file path containing `..` components, preventing directory escape attacks
-12. **Connection limiting** — server tracks active connections and rejects new ones beyond `max_connections` (default 100)
-13. **Keep-alive** — idle connections receive periodic `STATUS_KEEPALIVE` to detect half-open TCP connections
-14. **Abort handling** — `SIGINT` sets an abort flag; the next protocol operation sends `STATUS_ABORT` for clean server cleanup
-15. **Atomic writes** — files are written to a `.tmp` suffix then atomically renamed via `rename()`, preventing partial files
-16. **Backup** — before overwriting, existing files are moved to `--backup-dir` (or same directory with `~` suffix) preserving the original
-
-## Security Features
-
-### Path Traversal Protection
-All received file paths are validated by `has_path_traversal()` before any disk operation. Any path containing `..` components is rejected with `STATUS_ERROR`, preventing directory escape attacks.
-
-### TLS Certificate Verification
-When `--ca` is provided, the server performs mutual TLS verification (`SSL_VERIFY_PEER` with depth 4). Without `--ca`, TLS is still encrypted but peer certificates are not verified.
-
-### Connection Limits
-The server enforces a maximum of 100 concurrent connections (configurable via `max_connections` in `Server`). When the limit is reached, new connections are immediately rejected and closed.
-
-### Abort Handling
-If the client receives `SIGINT` (Ctrl+C) during a transfer, it sends `STATUS_ABORT` to the server. The server then cleans up temporary files and exits the child process, preventing incomplete files from remaining on disk.
-
-### Atomic Writes
-Received files are written to a temporary path (suffixed with `.tmp`) and then atomically renamed to the final filename via `rename()`. This prevents partial or corrupted files from appearing at the destination if the transfer is interrupted.

 ## Build Requirements

@@ -294,21 +223,6 @@ Place the `fastsync-server` binary in the remote `$PATH`. The client runs `ssh u
 # Bandwidth limit to 1 MB/s
 ./build/client --bwlimit 1024 /src user@host:/dst

-# With timeouts, quiet mode, and stats
-./build/client --timeout 60 --contimeout 15 --quiet --stats /src user@host:/dst
-
-# Backup overwritten files to a directory
-./build/client --backup --backup-dir /backups /src user@host:/dst
-
-# Exclude patterns from file, limit depth
-./build/client --exclude-from ignore.txt --max-depth 3 /src user@host:/dst
-
-# Custom queue size for multithreading
-./build/client -m --queue-size 200 /src user@host:/dst
-
-# Log to file
-./build/client --log-file /tmp/fastsync.log /src user@host:/dst
-
 # All features
 ./build/client -a --progress --chunk-size 5242880 --exclude "*.log" --delete /src /dst
 ```
@@ -316,9 +230,7 @@ Place the `fastsync-server` binary in the remote `$PATH`. The client runs `ssh u
 ## Testing

 ```bash
-# Unit tests (18 suites — array_list, chunk, compression, config, data, delta, file, glob,
-#                      metadata, property, protocol, queue, robustness, scanner,
-#                      shared_utils, stress, transport_tcp, transport_ssh, transport_tls)
+# Unit tests (7 suites)
 ./build/tests

 # Integration + benchmark suite
@@ -332,15 +244,12 @@ The benchmark prints throughput metrics, best configuration, and speedup vs rsyn
 1. Chunk size (~10 MB default) balances memory and transfer efficiency
 2. Compression level trades CPU for bandwidth
 3. `sendfile()` bypasses userspace — ~2× faster on localhost for large files
-4. Multithreading scales with core count; `--queue-size` controls pipeline buffering
+4. Multithreading scales with core count
 5. Metadata transfer adds negligible overhead (~24 bytes per file when enabled)
 6. SSH socketpair buffer set to 1 MB for improved pipe throughput
 7. SSH ControlMaster reuses connections across repeated invocations
 8. Incremental sync eliminates redundant transfers entirely
-9. Batch incremental reduces round-trips by grouping multiple checks into one message
-10. Bandwidth limiting uses token-bucket with nanosleep for accurate throttling
-11. Atomic writes add a single `rename()` per file — negligible overhead
-12. Path traversal check is O(n) in path length with negligible cost
+9. Bandwidth limiting uses token-bucket with nanosleep for accurate throttling

 ## Benchmark Results

@@ -3,7 +3,6 @@
 #include "delta.h"
 #include "log.h"
 #include "protocol.h"
-#include "transport_tcp.h"
 #include "transport_tls.h"
 #include "utils.h"
 #include <errno.h>
@@ -32,8 +31,6 @@ static void print_usage(void) {
  printf("  --delete            Delete files on receiver not in source\n");
  printf("  --exclude <pattern> Exclude files matching pattern\n");
  printf("  --include <pattern> Only include files matching pattern\n");
-  printf("  --exclude-from <file> Read exclude patterns from file\n");
-  printf("  --include-from <file> Read include patterns from file\n");
  printf("  --max-size <n>      Skip files larger than n bytes\n");
  printf("  --min-size <n>      Skip files smaller than n bytes\n");
  printf("  --incremental       Skip files unchanged since last transfer\n");
@@ -58,51 +55,11 @@ static void print_usage(void) {
  printf("  --cert <path>       TLS certificate file (PEM)\n");
  printf("  --key <path>        TLS private key file (PEM)\n");
  printf("  --ca <path>         TLS CA certificate file (PEM)\n");
-  printf("  --timeout <sec>     I/O timeout in seconds (default: 30)\n");
-  printf("  --contimeout <sec>  Connection timeout in seconds (default: 10)\n");
-  printf("  -q, --quiet         Suppress non-error output\n");
-  printf("  --silent            Alias for --quiet\n");
-  printf("  --backup            Backup existing files before overwriting\n");
-  printf("  --backup-dir <dir>  Directory for backups (requires --backup)\n");
-  printf("  --stats             Print transfer statistics at end\n");
-  printf("  --max-depth <n>     Maximum directory depth (0=unlimited)\n");
-  printf("  --log-file <path>   Write log messages to file\n");
-  printf("  --queue-size <n>    Queue capacity for multithreaded mode (default: 100)\n");
  printf("  --partial           Keep partial files on interrupted transfer\n");
  printf("  --fastsync-server-path <path>\n");
  printf("                      Path to fastsync-server on remote (default: fastsync-server)\n");
  printf("  --help              Show this help\n");
-}
-
-static int read_patterns_from_file(const char* filepath, char*** patterns, int* count) {
-  FILE* fp = fopen(filepath, "r");
-  if (!fp) {
-    fprintf(stderr, "Error: could not open pattern file '%s': %s\n", filepath, strerror(errno));
-    return -1;
-  }
-  char line[4096];
-  while (fgets(line, sizeof(line), fp)) {
-    char* p = line;
-    while (*p == ' ' || *p == '\t')
-      p++;
-    if (*p == '#' || *p == '\n' || *p == '\0')
-      continue;
-    size_t len = strlen(p);
-    while (len > 0 && (p[len - 1] == '\n' || p[len - 1] == '\r'))
-      p[--len] = '\0';
-    if (len == 0)
-      continue;
-    char** tmp = realloc(*patterns, (*count + 1) * sizeof(char*));
-    if (!tmp) {
-      fprintf(stderr, "Error: memory allocation failed for pattern file\n");
-      fclose(fp);
-      return -1;
-    }
-    *patterns = tmp;
-    (*patterns)[(*count)++] = str_dup(p);
-  }
-  fclose(fp);
-  return 0;
+  printf("  -V, --version       Show version and exit\n");
 }

 int main(int argc, char* argv[]) {
@@ -116,16 +73,13 @@ int main(int argc, char* argv[]) {
  }

  int exit_code = 0;
-  Config* config = NULL;
  bool config_owned_by_pipeline = false;
-
-  char* config_version = str_dup(PROTOCOL_VERSION);
-  if (!config_version) {
+  Config* config = config_create(str_dup(PROTOCOL_VERSION), NULL, NULL, save_to_disk, false, false,
+                                 false, false, 5, false, 0);
+  if (config == NULL) {
    exit_code = 1;
    goto cleanup;
  }
-  config = config_create(config_version, NULL, NULL, save_to_disk, false, false, false, false, 5,
-                         false, 0);

  int positional_args[2];
  int positional_count = 0;
@@ -134,6 +88,9 @@ int main(int argc, char* argv[]) {
    if (strcmp(argv[i], "--help") == 0) {
      print_usage();
      goto cleanup;
+    } else if (strcmp(argv[i], "-V") == 0 || strcmp(argv[i], "--version") == 0) {
+      printf("fastsync version %s\n", PROTOCOL_VERSION);
+      goto cleanup;
    } else if (strcmp(argv[i], "-a") == 0 || strcmp(argv[i], "--archive") == 0) {
      config->use_compression = true;
      config->use_multithreading = true;
@@ -142,7 +99,14 @@ int main(int argc, char* argv[]) {
    } else if (strcmp(argv[i], "-n") == 0 || strcmp(argv[i], "--dry-run") == 0) {
      config->dry_run = true;
    } else if (strcmp(argv[i], "-p") == 0 && i + 1 < argc) {
-      config->ssh_port = atoi(argv[++i]);
+      char* end;
+      long p = strtol(argv[++i], &end, 10);
+      if (*end != '\0' || p <= 0 || p > 65535) {
+        fprintf(stderr, "Error: invalid SSH port '%s' (must be 1-65535)\n", argv[i]);
+        exit_code = 1;
+        goto cleanup;
+      }
+      config->ssh_port = (int)p;
    } else if (strcmp(argv[i], "--delete") == 0) {
      config->use_delete = true;
    } else if (strcmp(argv[i], "--exclude") == 0 && i + 1 < argc) {
@@ -219,7 +183,14 @@ int main(int argc, char* argv[]) {
      free(config->server_host);
      config->server_host = str_dup(argv[++i]);
    } else if (strcmp(argv[i], "--server-port") == 0 && i + 1 < argc) {
-      config->server_port = atoi(argv[++i]);
+      char* end;
+      long p = strtol(argv[++i], &end, 10);
+      if (*end != '\0' || p <= 0 || p > 65535) {
+        fprintf(stderr, "Error: invalid server port '%s' (must be 1-65535)\n", argv[i]);
+        exit_code = 1;
+        goto cleanup;
+      }
+      config->server_port = (int)p;
    } else if (strcmp(argv[i], "--bwlimit") == 0 && i + 1 < argc) {
      char* end;
      errno = 0;
@@ -253,64 +224,6 @@ int main(int argc, char* argv[]) {
    } else if (strcmp(argv[i], "--ca") == 0 && i + 1 < argc) {
      free(config->tls_ca);
      config->tls_ca = str_dup(argv[++i]);
-    } else if (strcmp(argv[i], "--timeout") == 0 && i + 1 < argc) {
-      config->timeout = atoi(argv[++i]);
-      if (config->timeout <= 0) {
-        fprintf(stderr, "Error: --timeout must be a positive integer\n");
-        exit_code = 1;
-        goto cleanup;
-      }
-    } else if (strcmp(argv[i], "--contimeout") == 0 && i + 1 < argc) {
-      config->contimeout = atoi(argv[++i]);
-      if (config->contimeout <= 0) {
-        fprintf(stderr, "Error: --contimeout must be a positive integer\n");
-        exit_code = 1;
-        goto cleanup;
-      }
-    } else if (strcmp(argv[i], "-q") == 0 || strcmp(argv[i], "--quiet") == 0 ||
-               strcmp(argv[i], "--silent") == 0) {
-      config->quiet = true;
-    } else if (strcmp(argv[i], "--backup") == 0) {
-      config->backup = true;
-    } else if (strcmp(argv[i], "--backup-dir") == 0 && i + 1 < argc) {
-      config->backup_dir = str_dup(argv[++i]);
-    } else if (strcmp(argv[i], "--stats") == 0) {
-      config->stats = true;
-    } else if (strcmp(argv[i], "--max-depth") == 0 && i + 1 < argc) {
-      config->max_depth = atoi(argv[++i]);
-      if (config->max_depth < 0) {
-        fprintf(stderr, "Error: --max-depth must be a non-negative integer\n");
-        exit_code = 1;
-        goto cleanup;
-      }
-    } else if (strcmp(argv[i], "--log-file") == 0 && i + 1 < argc) {
-      FILE* lf = fopen(argv[++i], "a");
-      if (!lf) {
-        fprintf(stderr, "Error: could not open log file '%s': %s\n", argv[i], strerror(errno));
-        exit_code = 1;
-        goto cleanup;
-      }
-      config->log_file = lf;
-      log_set_file(lf);
-    } else if (strcmp(argv[i], "--queue-size") == 0 && i + 1 < argc) {
-      config->queue_size = atoi(argv[++i]);
-      if (config->queue_size <= 0) {
-        fprintf(stderr, "Error: --queue-size must be a positive integer\n");
-        exit_code = 1;
-        goto cleanup;
-      }
-    } else if (strcmp(argv[i], "--exclude-from") == 0 && i + 1 < argc) {
-      if (read_patterns_from_file(argv[++i], &config->exclude_patterns, &config->exclude_count) !=
-          0) {
-        exit_code = 1;
-        goto cleanup;
-      }
-    } else if (strcmp(argv[i], "--include-from") == 0 && i + 1 < argc) {
-      if (read_patterns_from_file(argv[++i], &config->include_patterns, &config->include_count) !=
-          0) {
-        exit_code = 1;
-        goto cleanup;
-      }
    } else if (strcmp(argv[i], "--partial") == 0) {
      config->partial = true;
    } else if (strcmp(argv[i], "--fastsync-server-path") == 0 && i + 1 < argc) {
@@ -414,8 +327,6 @@ int main(int argc, char* argv[]) {
    tls_global_init();
  }

-  tcp_set_timeouts(config->timeout, config->contimeout);
-
  if (config->use_multithreading) {
    config_owned_by_pipeline = true;
    exit_code = send_files_multithreaded(config);
@@ -424,11 +335,7 @@ int main(int argc, char* argv[]) {
  }

 cleanup:
-  if (config) {
-    if (config->log_file)
-      fclose(config->log_file);
-    if (!config_owned_by_pipeline)
-      config_delete(config);
-  }
+  if (!config_owned_by_pipeline)
+    config_delete(config);
  return exit_code;
 }
@@ -21,9 +21,6 @@
 #include <string.h>
 #include <threads.h>
 #include <time.h>
-#include <unistd.h>
-
-#define STREAM_THRESHOLD (64ULL * 1024 * 1024)

 static int incremental_check(Client* client, File* file, DeltaSignature** out_sig) {
  *out_sig = NULL;
@@ -211,13 +208,10 @@ int send_chunk(Client* client, Chunk* chunk, Config* config) {
    return 0;
  }

+  bool use_sendfile = config->use_sendfile && !config->use_compression;
  for (int i = 0; i < chunk->element_count; i++) {
-    File* f = chunk->items[i];
-    if (f == NULL)
-      continue;
-    bool stream = f->data->data == NULL && f->data->size > 0;
-    bool use_sendfile = (config->use_sendfile && !config->use_compression) || stream;
-    int rc = send_single_file(client, f, config, config->use_incremental, use_sendfile);
+    int rc =
+        send_single_file(client, chunk->items[i], config, config->use_incremental, use_sendfile);
    if (rc == 1)
      continue;
    if (rc < 0)
@@ -302,14 +296,16 @@ static int send_chunks_multithreaded(void* pipeline_context) {

 static int scan_directory_multithreaded(void* pipeline_context) {
  PipelineContextSender* context = (PipelineContextSender*)pipeline_context;
-  ParallelScanner* scanner = parallel_scanner_create(
+  mtx_lock(&context->mutex_scanner);
+  DirectoryScanner* scanner = directory_scanner_create(
      context->config->send_directory, context->config->use_metadata, context->config->chunk_size,
      context->config->exclude_patterns, context->config->exclude_count,
      context->config->include_patterns, context->config->include_count, context->config->max_size,
-      context->config->min_size, context->config->max_depth, 4);
+      context->config->min_size);
+  mtx_unlock(&context->mutex_scanner);

  Chunk* current_chunk;
-  while ((current_chunk = parallel_scanner_next(scanner)) != NULL) {
+  while ((current_chunk = directory_scanner_next(scanner)) != NULL) {
    if (context->config->use_delete) {
      mtx_lock(&context->mutex_scanner);
      for (int i = 0; i < current_chunk->element_count; i++) {
@@ -329,7 +325,7 @@ static int scan_directory_multithreaded(void* pipeline_context) {
  cnd_signal(&context->condition_not_empty_scanner);
  mtx_unlock(&context->mutex_scanner);

-  parallel_scanner_destroy(scanner);
+  directory_scanner_destroy(scanner);
  return thrd_success;
 }

@@ -348,12 +344,9 @@ static int load_files_multithreaded(void* pipeline_context) {
    }
    if (!context->config->use_sendfile) {
      for (int i = 0; i < chunk->element_count; i++) {
-        File* f = chunk->items[i];
-        if (f->data->size > STREAM_THRESHOLD)
-          continue;
-        if (!file_load_data(f)) {
+        if (!file_load_data(chunk->items[i])) {
          log_message(LOG_LEVEL_ERROR, "Failed to load file data, skipping");
-          file_destroy(f);
+          file_destroy(chunk->items[i]);
          chunk->items[i] = NULL;
        }
      }
@@ -369,7 +362,7 @@ int send_files(Config* config) {
    DirectoryScanner* scanner = directory_scanner_create(
        config->send_directory, config->use_metadata, config->chunk_size, config->exclude_patterns,
        config->exclude_count, config->include_patterns, config->include_count, config->max_size,
-        config->min_size, config->max_depth);
+        config->min_size);
    Chunk* chunk;
    int file_count = 0;
    unsigned long long total_bytes = 0;
@@ -423,7 +416,7 @@ int send_files(Config* config) {
  DirectoryScanner* scanner = directory_scanner_create(
      config->send_directory, config->use_metadata, config->chunk_size, config->exclude_patterns,
      config->exclude_count, config->include_patterns, config->include_count, config->max_size,
-      config->min_size, config->max_depth);
+      config->min_size);
  Chunk* current_chunk;
  unsigned long long total_bytes = 0;
  time_t last_progress = 0;
@@ -442,10 +435,7 @@ int send_files(Config* config) {
    }
    if (!config->use_sendfile) {
      for (int i = 0; i < current_chunk->element_count; i++) {
-        File* f = current_chunk->items[i];
-        if (f->data->size > STREAM_THRESHOLD)
-          continue;
-        if (!file_load_data(f)) {
+        if (!file_load_data(current_chunk->items[i])) {
          log_message(LOG_LEVEL_ERROR, "Failed to load file data");
          continue;
        }
@@ -512,7 +502,7 @@ int send_files_multithreaded(Config* config) {
    DirectoryScanner* scanner = directory_scanner_create(
        config->send_directory, config->use_metadata, config->chunk_size, config->exclude_patterns,
        config->exclude_count, config->include_patterns, config->include_count, config->max_size,
-        config->min_size, config->max_depth);
+        config->min_size);
    Chunk* chunk;
    int file_count = 0;
    unsigned long long total_bytes = 0;
@@ -530,20 +520,8 @@ int send_files_multithreaded(Config* config) {
    return 0;
  }

-  long pages = sysconf(_SC_AVPHYS_PAGES);
-  long page_size = sysconf(_SC_PAGE_SIZE);
-  unsigned long long available_memory =
-      pages > 0 && page_size > 0 ? (unsigned long long)pages * (unsigned long long)page_size
-                                 : 512ULL * 1024 * 1024;
-  unsigned long long avg_file_size = 1024 * 1024;
-  int qsize = (int)(available_memory / avg_file_size);
-  if (qsize < 10)
-    qsize = 10;
-  if (qsize > 1000)
-    qsize = 1000;
-
-  Queue* q1 = queue_create(qsize, chunk_destroy);
-  Queue* q2 = queue_create(qsize, chunk_destroy);
+  Queue* q1 = queue_create(100, chunk_destroy);
+  Queue* q2 = queue_create(100, chunk_destroy);
  if (!q1 || !q2) {
    if (q1)
      queue_destroy(q1);
@@ -9,53 +9,101 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>
-#include <threads.h>
 #include <unistd.h>

-typedef struct {
-  char* path;
-  int depth;
-} DirEntry;
-
-static void dir_entry_destroy(void* item) {
-  if (item) {
-    DirEntry* de = (DirEntry*)item;
-    free(de->path);
-    free(de);
-  }
-}
-
-static DirEntry* dir_entry_create(const char* path, int depth) {
-  DirEntry* de = malloc(sizeof(DirEntry));
-  if (de) {
-    de->path = str_dup(path);
-    de->depth = depth;
-  }
-  return de;
-}
-
-DirectoryScanner* directory_scanner_create(const char* root_directory, bool use_metadata,
+DirectoryScanner* directory_scanner_create(char* root_directory, bool use_metadata,
                                           unsigned long long chunk_size, char** exclude_patterns,
                                           int exclude_count, char** include_patterns,
                                           int include_count, unsigned long long max_size,
-                                           unsigned long long min_size, int max_depth) {
+                                           unsigned long long min_size) {
+  return directory_scanner_create_full(root_directory, use_metadata, chunk_size, exclude_patterns,
+                                       exclude_count, include_patterns, include_count, max_size,
+                                       min_size, true);
+}
+
+DirectoryScanner* directory_scanner_create_full(char* root_directory, bool use_metadata,
+                                                unsigned long long chunk_size,
+                                                char** exclude_patterns, int exclude_count,
+                                                char** include_patterns, int include_count,
+                                                unsigned long long max_size,
+                                                unsigned long long min_size, bool follow_symlinks) {
  DirectoryScanner* scanner = malloc(sizeof(DirectoryScanner));
  if (scanner == NULL)
    return NULL;
-  scanner->directories = queue_create(100, dir_entry_destroy);
+  scanner->directories = queue_create(100, free);
  scanner->current_dir = NULL;
  scanner->current_path = NULL;
  scanner->use_metadata = use_metadata;
  scanner->chunk_size = chunk_size > 0 ? chunk_size : DESIRED_CHUNK_SIZE;
-  scanner->exclude_patterns = exclude_patterns;
+  /* Deep-copy exclude patterns */
+  if (exclude_count > 0 && exclude_patterns != NULL) {
+    scanner->exclude_patterns = malloc((size_t)exclude_count * sizeof(char*));
+    if (scanner->exclude_patterns == NULL) {
+      queue_destroy(scanner->directories);
+      free(scanner);
+      return NULL;
+    }
+    for (int i = 0; i < exclude_count; i++) {
+      scanner->exclude_patterns[i] = str_dup(exclude_patterns[i]);
+      if (scanner->exclude_patterns[i] == NULL) {
+        for (int j = 0; j < i; j++)
+          free(scanner->exclude_patterns[j]);
+        free(scanner->exclude_patterns);
+        queue_destroy(scanner->directories);
+        free(scanner);
+        return NULL;
+      }
+    }
+  } else {
+    scanner->exclude_patterns = NULL;
+  }
  scanner->exclude_count = exclude_count;
-  scanner->include_patterns = include_patterns;
+
+  /* Deep-copy include patterns */
+  if (include_count > 0 && include_patterns != NULL) {
+    scanner->include_patterns = malloc((size_t)include_count * sizeof(char*));
+    if (scanner->include_patterns == NULL) {
+      for (int i = 0; i < exclude_count; i++)
+        free(scanner->exclude_patterns[i]);
+      free(scanner->exclude_patterns);
+      queue_destroy(scanner->directories);
+      free(scanner);
+      return NULL;
+    }
+    for (int i = 0; i < include_count; i++) {
+      scanner->include_patterns[i] = str_dup(include_patterns[i]);
+      if (scanner->include_patterns[i] == NULL) {
+        for (int j = 0; j < i; j++)
+          free(scanner->include_patterns[j]);
+        free(scanner->include_patterns);
+        for (int j = 0; j < exclude_count; j++)
+          free(scanner->exclude_patterns[j]);
+        free(scanner->exclude_patterns);
+        queue_destroy(scanner->directories);
+        free(scanner);
+        return NULL;
+      }
+    }
+  } else {
+    scanner->include_patterns = NULL;
+  }
  scanner->include_count = include_count;
  scanner->max_size = max_size;
  scanner->min_size = min_size;
-  scanner->max_depth = max_depth;
-  scanner->current_depth = 0;
-  queue_enqueue(scanner->directories, dir_entry_create(root_directory, 0));
+  scanner->follow_symlinks = follow_symlinks;
+  char* root_copy = str_dup(root_directory);
+  if (root_copy == NULL) {
+    for (int i = 0; i < scanner->include_count; i++)
+      free(scanner->include_patterns[i]);
+    free(scanner->include_patterns);
+    for (int i = 0; i < scanner->exclude_count; i++)
+      free(scanner->exclude_patterns[i]);
+    free(scanner->exclude_patterns);
+    queue_destroy(scanner->directories);
+    free(scanner);
+    return NULL;
+  }
+  queue_enqueue(scanner->directories, root_copy);
  return scanner;
 }

@@ -67,6 +115,12 @@ void directory_scanner_destroy(DirectoryScanner* scanner) {
    scanner->current_dir = NULL;
  }
  free(scanner->current_path);
+  for (int i = 0; i < scanner->exclude_count; i++)
+    free(scanner->exclude_patterns[i]);
+  free(scanner->exclude_patterns);
+  for (int i = 0; i < scanner->include_count; i++)
+    free(scanner->include_patterns[i]);
+  free(scanner->include_patterns);
  queue_destroy(scanner->directories);
  free(scanner);
 }
@@ -80,6 +134,7 @@ static Chunk* chunk_data_to_chunk(ArrayList* chunk_data) {
  return chunk;
 }

+// Returns: 1 on success, 0 if no more directories in queue, -1 on opendir failure
 static int open_next_directory(DirectoryScanner* scanner) {
  if (scanner->current_dir) {
    closedir(scanner->current_dir);
@@ -90,10 +145,7 @@ static int open_next_directory(DirectoryScanner* scanner) {
  if (queue_is_empty(scanner->directories))
    return 0;

-  DirEntry* de = (DirEntry*)queue_dequeue(scanner->directories);
-  scanner->current_path = de->path;
-  scanner->current_depth = de->depth;
-  free(de);
+  scanner->current_path = (char*)queue_dequeue(scanner->directories);
  scanner->current_dir = opendir(scanner->current_path);
  if (scanner->current_dir == NULL) {
    perror("Could not open directory");
@@ -131,24 +183,82 @@ Chunk* directory_scanner_next(DirectoryScanner* scanner) {

    char* cur_path = path_cat(scanner->current_path, entry->d_name);
    struct stat stats;
-    if (stat(cur_path, &stats) != 0) {
+    // Use lstat to detect symlinks
+    if (lstat(cur_path, &stats) != 0) {
      free(cur_path);
      continue;
    }

-    if (S_ISDIR(stats.st_mode)) {
-      int next_depth = scanner->current_depth + 1;
-      if (scanner->max_depth <= 0 || next_depth < scanner->max_depth) {
-        DirEntry* de = dir_entry_create(cur_path, next_depth);
-        if (!queue_enqueue(scanner->directories, de))
-          dir_entry_destroy(de);
-      }
-      free(cur_path);
-    } else {
-      if (scanner->max_depth > 0 && scanner->current_depth + 1 > scanner->max_depth) {
+    // If follow_symlinks is enabled and this is a symlink, resolve it
+    if (scanner->follow_symlinks && S_ISLNK(stats.st_mode)) {
+      struct stat target_stats;
+      if (stat(cur_path, &target_stats) != 0) {
+        // Broken symlink, skip
        free(cur_path);
        continue;
      }
+      stats = target_stats;
+    }
+
+    if (S_ISDIR(stats.st_mode)) {
+      queue_enqueue(scanner->directories, (void*)cur_path);
+    } else if (S_ISLNK(stats.st_mode)) {
+      // Handle symlink (not following)
+      bool excluded = false;
+      for (int i = 0; i < scanner->exclude_count; i++) {
+        if (glob_match(scanner->exclude_patterns[i], entry->d_name)) {
+          excluded = true;
+          break;
+        }
+      }
+      if (excluded) {
+        free(cur_path);
+        continue;
+      }
+
+      if (scanner->include_count > 0) {
+        bool included = false;
+        for (int i = 0; i < scanner->include_count; i++) {
+          if (glob_match(scanner->include_patterns[i], entry->d_name)) {
+            included = true;
+            break;
+          }
+        }
+        if (!included) {
+          free(cur_path);
+          continue;
+        }
+      }
+
+      File* file = file_create(cur_path);
+      if (file == NULL) {
+        free(cur_path);
+        continue;
+      }
+      file->type = FILE_TYPE_SYMLINK;
+      // Read link target
+      char link_buf[4096];
+      ssize_t link_len = readlink(cur_path, link_buf, sizeof(link_buf) - 1);
+      if (link_len >= 0) {
+        link_buf[link_len] = '\0';
+        file->link_target = str_dup(link_buf);
+        if (file->link_target == NULL) {
+          file_destroy(file);
+          free(cur_path);
+          continue;
+        }
+      }
+      file->data->size = 0;
+      if (scanner->use_metadata)
+        file->metadata = file_metadata_create(&stats);
+      array_list_add(chunk_data, file);
+      chunk_data_size += 1; // small size for symlinks
+      if (chunk_data_size > scanner->chunk_size) {
+        free(cur_path);
+        return chunk_data_to_chunk(chunk_data);
+      }
+      free(cur_path);
+    } else {
      bool excluded = false;
      for (int i = 0; i < scanner->exclude_count; i++) {
        if (glob_match(scanner->exclude_patterns[i], entry->d_name)) {
@@ -204,256 +314,3 @@ Chunk* directory_scanner_next(DirectoryScanner* scanner) {
  array_list_delete(chunk_data);
  return NULL;
 }
-
-typedef struct {
-  ParallelScanner* ps;
-  char** dirs;
-  int dir_count;
-  bool use_metadata;
-  unsigned long long chunk_size;
-  char** exclude_patterns;
-  int exclude_count;
-  char** include_patterns;
-  int include_count;
-  unsigned long long max_size;
-  unsigned long long min_size;
-  int max_depth;
-} ParallelWorkerArg;
-
-static int parallel_worker_thread(void* arg) {
-  ParallelWorkerArg* wa = (ParallelWorkerArg*)arg;
-  for (int i = 0; i < wa->dir_count; i++) {
-    DirectoryScanner* ds = directory_scanner_create(
-        wa->dirs[i], wa->use_metadata, wa->chunk_size, wa->exclude_patterns, wa->exclude_count,
-        wa->include_patterns, wa->include_count, wa->max_size, wa->min_size, wa->max_depth);
-    Chunk* chunk;
-    while ((chunk = directory_scanner_next(ds)) != NULL) {
-      queue_enqueue_multithreaded(wa->ps->result_queue, chunk, &wa->ps->result_mutex,
-                                  &wa->ps->result_not_empty, &wa->ps->result_not_full);
-    }
-    directory_scanner_destroy(ds);
-    free(wa->dirs[i]);
-  }
-  ParallelScanner* ps = wa->ps;
-  free(wa->dirs);
-  free(wa);
-  mtx_lock(&ps->result_mutex);
-  ps->completed++;
-  if (ps->completed >= ps->num_threads) {
-    ps->done = true;
-    cnd_signal(&ps->result_not_empty);
-  }
-  mtx_unlock(&ps->result_mutex);
-  return thrd_success;
-}
-
-ParallelScanner* parallel_scanner_create(char* root_directory, bool use_metadata,
-                                         unsigned long long chunk_size, char** exclude_patterns,
-                                         int exclude_count, char** include_patterns,
-                                         int include_count, unsigned long long max_size,
-                                         unsigned long long min_size, int max_depth,
-                                         int num_threads) {
-  ParallelScanner* ps = calloc(1, sizeof(ParallelScanner));
-  if (!ps)
-    return NULL;
-  ps->result_queue = queue_create(100, chunk_destroy);
-  if (!ps->result_queue) {
-    free(ps);
-    return NULL;
-  }
-  if (mtx_init(&ps->result_mutex, mtx_plain) != thrd_success ||
-      cnd_init(&ps->result_not_empty) != thrd_success ||
-      cnd_init(&ps->result_not_full) != thrd_success) {
-    queue_destroy(ps->result_queue);
-    free(ps);
-    return NULL;
-  }
-
-  DIR* dir = opendir(root_directory);
-  if (!dir) {
-    perror("Could not open root directory for parallel scan");
-    parallel_scanner_destroy(ps);
-    return NULL;
-  }
-
-  ArrayList* root_files = array_list_create(file_destroy);
-  ArrayList* subdirs = array_list_create(free);
-  struct dirent* entry;
-  while ((entry = readdir(dir)) != NULL) {
-    if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0)
-      continue;
-    char* cur_path = path_cat(root_directory, entry->d_name);
-    if (!cur_path)
-      continue;
-    struct stat st;
-    if (stat(cur_path, &st) != 0) {
-      free(cur_path);
-      continue;
-    }
-    if (S_ISDIR(st.st_mode)) {
-      array_list_add(subdirs, cur_path);
-    } else {
-      bool excluded = false;
-      for (int i = 0; i < exclude_count; i++) {
-        if (glob_match(exclude_patterns[i], entry->d_name)) {
-          excluded = true;
-          break;
-        }
-      }
-      if (excluded) {
-        free(cur_path);
-        continue;
-      }
-      if (include_count > 0) {
-        bool included = false;
-        for (int i = 0; i < include_count; i++) {
-          if (glob_match(include_patterns[i], entry->d_name)) {
-            included = true;
-            break;
-          }
-        }
-        if (!included) {
-          free(cur_path);
-          continue;
-        }
-      }
-      if ((max_size > 0 && (unsigned long long)st.st_size > max_size) ||
-          (min_size > 0 && (unsigned long long)st.st_size < min_size)) {
-        free(cur_path);
-        continue;
-      }
-      File* file = file_create(cur_path);
-      free(cur_path);
-      if (!file)
-        continue;
-      file->data->size = st.st_size;
-      if (use_metadata)
-        file->metadata = file_metadata_create(&st);
-      array_list_add(root_files, file);
-    }
-  }
-  closedir(dir);
-
-  unsigned long long cs = chunk_size > 0 ? chunk_size : DESIRED_CHUNK_SIZE;
-  if (root_files->size > 0) {
-    ArrayList* batch = array_list_create(NULL);
-    unsigned long long batch_size = 0;
-    Chunk* first = NULL;
-    for (int i = 0; i < root_files->size; i++) {
-      File* f = (File*)root_files->items[i];
-      array_list_add(batch, f);
-      batch_size += f->data->size;
-      if (batch_size >= cs || i == root_files->size - 1) {
-        void** items = array_list_to_array(batch);
-        Chunk* c = chunk_create((File**)items, batch->size);
-        free(items);
-        batch->item_destroyer = NULL;
-        array_list_delete(batch);
-        batch = NULL;
-        if (!first) {
-          first = c;
-        } else {
-          queue_enqueue_multithreaded(ps->result_queue, c, &ps->result_mutex, &ps->result_not_empty,
-                                      &ps->result_not_full);
-        }
-        if (i < root_files->size - 1) {
-          batch = array_list_create(NULL);
-          batch_size = 0;
-        }
-      }
-    }
-    if (batch) {
-      batch->item_destroyer = NULL;
-      array_list_delete(batch);
-    }
-    ps->initial_chunk = first;
-    root_files->item_destroyer = NULL;
-  }
-  array_list_delete(root_files);
-
-  int n = num_threads > 0 ? num_threads : 4;
-  if (n > subdirs->size)
-    n = subdirs->size > 0 ? subdirs->size : 1;
-
-  if (subdirs->size > 0) {
-    ps->num_threads = n;
-    ps->threads = calloc(n, sizeof(thrd_t));
-    if (!ps->threads) {
-      array_list_delete(subdirs);
-      parallel_scanner_destroy(ps);
-      return NULL;
-    }
-    int dirs_per_thread = subdirs->size / n;
-    int remainder = subdirs->size % n;
-    int start = 0;
-    for (int t = 0; t < n; t++) {
-      int count = dirs_per_thread + (t < remainder ? 1 : 0);
-      if (count == 0)
-        break;
-      ParallelWorkerArg* wa = calloc(1, sizeof(ParallelWorkerArg));
-      if (!wa)
-        break;
-      wa->ps = ps;
-      wa->dirs = calloc(count, sizeof(char*));
-      if (!wa->dirs) {
-        free(wa);
-        break;
-      }
-      for (int j = 0; j < count; j++)
-        wa->dirs[j] = str_dup((char*)subdirs->items[start + j]);
-      wa->dir_count = count;
-      wa->use_metadata = use_metadata;
-      wa->chunk_size = cs;
-      wa->exclude_patterns = exclude_patterns;
-      wa->exclude_count = exclude_count;
-      wa->include_patterns = include_patterns;
-      wa->include_count = include_count;
-      wa->max_size = max_size;
-      wa->min_size = min_size;
-      wa->max_depth = max_depth;
-      start += count;
-      if (thrd_create(&ps->threads[t], parallel_worker_thread, wa) != thrd_success) {
-        for (int j = 0; j < count; j++)
-          free(wa->dirs[j]);
-        free(wa->dirs);
-        free(wa);
-        ps->num_threads = t;
-        break;
-      }
-    }
-  }
-  array_list_delete(subdirs);
-  return ps;
-}
-
-Chunk* parallel_scanner_next(ParallelScanner* ps) {
-  if (ps->initial_chunk) {
-    Chunk* c = ps->initial_chunk;
-    ps->initial_chunk = NULL;
-    return c;
-  }
-  if (ps->num_threads == 0) {
-    ps->done = true;
-    return NULL;
-  }
-  Chunk* chunk = queue_dequeue_multithreaded(
-      ps->result_queue, &ps->result_mutex, &ps->result_not_empty, &ps->result_not_full, &ps->done);
-  return chunk;
-}
-
-void parallel_scanner_destroy(ParallelScanner* ps) {
-  if (!ps)
-    return;
-  ps->done = true;
-  cnd_signal(&ps->result_not_empty);
-  for (int i = 0; i < ps->num_threads; i++)
-    thrd_join(ps->threads[i], NULL);
-  free(ps->threads);
-  if (ps->initial_chunk)
-    chunk_destroy(ps->initial_chunk);
-  queue_destroy(ps->result_queue);
-  mtx_destroy(&ps->result_mutex);
-  cnd_destroy(&ps->result_not_empty);
-  cnd_destroy(&ps->result_not_full);
-  free(ps);
-}
@@ -5,7 +5,6 @@
 #include "queue.h"
 #include <dirent.h>
 #include <stdbool.h>
-#include <threads.h>

 typedef struct {
  Queue* directories;
@@ -19,37 +18,21 @@ typedef struct {
  int include_count;
  unsigned long long max_size;
  unsigned long long min_size;
-  int max_depth;
-  int current_depth;
+  bool follow_symlinks;
 } DirectoryScanner;

-typedef struct {
-  Queue* result_queue;
-  mtx_t result_mutex;
-  cnd_t result_not_empty;
-  cnd_t result_not_full;
-  int num_threads;
-  thrd_t* threads;
-  bool done;
-  int completed;
-  Chunk* initial_chunk;
-} ParallelScanner;
-
-DirectoryScanner* directory_scanner_create(const char* root_directory, bool use_metadata,
+DirectoryScanner* directory_scanner_create(char* root_directory, bool use_metadata,
                                           unsigned long long chunk_size, char** exclude_patterns,
                                           int exclude_count, char** include_patterns,
                                           int include_count, unsigned long long max_size,
-                                           unsigned long long min_size, int max_depth);
+                                           unsigned long long min_size);
+DirectoryScanner* directory_scanner_create_full(char* root_directory, bool use_metadata,
+                                                unsigned long long chunk_size,
+                                                char** exclude_patterns, int exclude_count,
+                                                char** include_patterns, int include_count,
+                                                unsigned long long max_size,
+                                                unsigned long long min_size, bool follow_symlinks);
 Chunk* directory_scanner_next(DirectoryScanner* scanner);
 void directory_scanner_destroy(DirectoryScanner* scanner);

-ParallelScanner* parallel_scanner_create(char* root_directory, bool use_metadata,
-                                         unsigned long long chunk_size, char** exclude_patterns,
-                                         int exclude_count, char** include_patterns,
-                                         int include_count, unsigned long long max_size,
-                                         unsigned long long min_size, int max_depth,
-                                         int num_threads);
-Chunk* parallel_scanner_next(ParallelScanner* scanner);
-void parallel_scanner_destroy(ParallelScanner* scanner);
-
 #endif
@@ -11,26 +11,55 @@
 #include "transport_tls.h"
 #include "unistd.h"
 #include "utils.h"
+#include <libgen.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>

+// Check if a file path should be excluded based on config patterns
+static bool is_excluded(const char* path, const Config* config) {
+  // Extract filename from path
+  char* path_dup = str_dup(path);
+  if (!path_dup)
+    return false;
+  /* basename(3) may return a pointer into path_dup or a static buffer;
+   * either way we free path_dup, not fname. */
+  char* fname = basename(path_dup);
+
+  // Check exclude patterns
+  for (int i = 0; i < config->exclude_count; i++) {
+    if (glob_match(config->exclude_patterns[i], fname)) {
+      free(path_dup);
+      return true;
+    }
+  }
+
+  // Check include patterns (if any, file must match at least one)
+  if (config->include_count > 0) {
+    bool included = false;
+    for (int i = 0; i < config->include_count; i++) {
+      if (glob_match(config->include_patterns[i], fname)) {
+        included = true;
+        break;
+      }
+    }
+    if (!included) {
+      free(path_dup);
+      return true;
+    }
+  }
+
+  free(path_dup);
+  return false;
+}
+
 int receive_files(Config* config, int fd) {
  Status status;
  if (!receive_status(fd, &status))
    return -1;

-  while (status == STATUS_NEXT || status == STATUS_CHUNK || status == STATUS_CHECK ||
-         status == STATUS_KEEPALIVE || status == STATUS_ABORT || status == STATUS_CHECK_BATCH) {
-    if (status == STATUS_KEEPALIVE) {
-      send_status(fd, STATUS_KEEPALIVE);
-      goto next;
-    }
-    if (status == STATUS_ABORT) {
-      log_message(LOG_LEVEL_INFO, "Received abort from client, cleaning up");
-      return -1;
-    }
+  while (status == STATUS_NEXT || status == STATUS_CHUNK || status == STATUS_CHECK) {
    if (status == STATUS_CHECK) {
      bool skipped;
      File* file = receive_incremental_check(fd, config, &skipped);
@@ -38,8 +67,8 @@ int receive_files(Config* config, int fd) {
        goto next;
      if (file == NULL && !skipped)
        return -1;
-      if (config->save_to_disk)
-        file_save_to_disk(config->receive_root_directory, file, NULL);
+      if (config->save_to_disk && !is_excluded(file->path, config))
+        file_save_to_disk(config->receive_root_directory, file);
      file_destroy(file);
    } else if (status == STATUS_CHUNK) {
      Chunk* chunk = receive_chunk_data(fd, config);
@@ -48,38 +77,10 @@ int receive_files(Config* config, int fd) {
        return -1;
      }
      for (int i = 0; i < chunk->element_count; i++) {
-        if (config->save_to_disk)
-          file_save_to_disk(config->receive_root_directory, chunk->items[i], NULL);
+        if (config->save_to_disk && !is_excluded(chunk->items[i]->path, config))
+          file_save_to_disk(config->receive_root_directory, chunk->items[i]);
      }
      chunk_destroy(chunk);
-    } else if (status == STATUS_CHECK_BATCH) {
-      int count;
-      if (!receive_int(fd, &count))
-        return -1;
-      for (int i = 0; i < count; i++) {
-        char* check_path = receive_str(fd);
-        if (!check_path)
-          return -1;
-        unsigned long long check_size;
-        long long check_mtime;
-        if (!receive_n_data(fd, &check_size, sizeof(check_size)) ||
-            !receive_n_data(fd, &check_mtime, sizeof(check_mtime))) {
-          free(check_path);
-          return -1;
-        }
-        char* full_path = path_cat(config->receive_root_directory, check_path);
-        struct stat st;
-        bool has_old = full_path && stat(full_path, &st) == 0;
-        bool match = has_old && (unsigned long long)st.st_size == check_size &&
-                     (long long)st.st_mtime == check_mtime;
-        if (match)
-          send_status(fd, STATUS_OK);
-        else
-          send_status(fd, STATUS_NEXT);
-        free(full_path);
-        free(check_path);
-      }
-      goto next;
    } else {
      File* file = file_receive(config, fd);
      if (file == NULL) {
@@ -87,8 +88,8 @@ int receive_files(Config* config, int fd) {
        send_status(fd, STATUS_ERROR);
        return -1;
      }
-      if (config->save_to_disk)
-        file_save_to_disk(config->receive_root_directory, file, NULL);
+      if (config->save_to_disk && !is_excluded(file->path, config))
+        file_save_to_disk(config->receive_root_directory, file);
      file_destroy(file);
    }
  next:
@@ -150,13 +151,12 @@ void handler(int file_descriptor) {
 }

 static Server* g_server = NULL;
+static volatile sig_atomic_t g_server_cleanup_requested = 0;

 static void cleanup(int sig) {
  (void)sig;
-  if (g_server) {
-    server_delete(&g_server);
-  }
-  _exit(0);
+  server_request_shutdown();
+  g_server_cleanup_requested = 1;
 }

 static void print_server_usage(void) {
@@ -172,6 +172,7 @@ static void print_server_usage(void) {
  printf("  --ca <path>         TLS CA certificate file (PEM)\n");
  printf("  -v, --verbose       Enable debug logging\n");
  printf("  --help              Show this help\n");
+  printf("  -V, --version       Show version and exit\n");
 }

 int main(int argc, char* argv[]) {
@@ -186,6 +187,9 @@ int main(int argc, char* argv[]) {
    if (strcmp(argv[i], "--help") == 0) {
      print_server_usage();
      return 0;
+    } else if (strcmp(argv[i], "-V") == 0 || strcmp(argv[i], "--version") == 0) {
+      printf("fastsync-server version %s\n", PROTOCOL_VERSION);
+      return 0;
    } else if (strcmp(argv[i], "--stdio") == 0) {
      io_set_fds(STDIN_FILENO, STDOUT_FILENO);
      handler(STDIN_FILENO);
@@ -242,5 +246,10 @@ int main(int argc, char* argv[]) {
  } else {
    server_listen(g_server, handler);
  }
+
+  /* Graceful shutdown: delete the server */
+  if (g_server_cleanup_requested)
+    log_message(LOG_LEVEL_INFO, "Shutdown requested, cleaning up");
+  server_delete(&g_server);
  return 0;
 }
@@ -1,31 +1,26 @@
 #include "compression.h"
 #include "data.h"
 #include "log.h"
-#include "stdlib.h"
-#include "string.h"
-#include <strings.h>
+#include <stdint.h>
+#include <stdlib.h>
 #include "zstd.h"

 #define INITIAL_DECOMPRESS_BUF_SIZE (1024 * 1024)

-static const char* SKIP_COMPRESSION_EXTENSIONS[] = {".jpg", ".jpeg", ".png", ".gif", ".mp4", ".mkv",
-                                                    ".zip", ".gz",   ".xz",  ".zst", NULL};
-
-bool compression_should_skip(const char* path) {
-  if (!path)
-    return false;
-  const char* dot = strrchr(path, '.');
-  if (!dot)
-    return false;
-  for (int i = 0; SKIP_COMPRESSION_EXTENSIONS[i]; i++) {
-    if (strcasecmp(dot, SKIP_COMPRESSION_EXTENSIONS[i]) == 0)
-      return true;
-  }
-  return false;
-}
-
 Data* data_compress(Data* data_to_compress, int compression_level) {
  log_message(LOG_LEVEL_DEBUG, "Starting to compress data");
+
+  /* Clamp compression level to valid zstd range [1, 22] */
+  if (compression_level < 1) {
+    log_message(LOG_LEVEL_WARNING, "compression_level %d out of range [1,22], using 1",
+                compression_level);
+    compression_level = 1;
+  } else if (compression_level > 22) {
+    log_message(LOG_LEVEL_WARNING, "compression_level %d out of range [1,22], using 22",
+                compression_level);
+    compression_level = 22;
+  }
+
  size_t dst_size = ZSTD_compressBound(data_to_compress->size);
  Data* compressed_data = data_create_empty(dst_size);
  if (compressed_data == NULL)
@@ -84,8 +79,16 @@ Data* data_decompress(Data* compressed_data) {
    return NULL;
  }

-  size_t buf_size =
-      (!ZSTD_isError(dst_size) && dst_size > 0) ? (size_t)dst_size : INITIAL_DECOMPRESS_BUF_SIZE;
+  size_t buf_size = INITIAL_DECOMPRESS_BUF_SIZE;
+  if (!ZSTD_isError(dst_size) && dst_size > 0) {
+    if (dst_size > SIZE_MAX) {
+      log_message(LOG_LEVEL_ERROR,
+                  "Decompressed size %llu exceeds addressable memory, using fallback buffer",
+                  dst_size);
+    } else {
+      buf_size = (size_t)dst_size;
+    }
+  }
  Data* uncompressed_data = data_create_empty(buf_size);
  if (!uncompressed_data) {
    log_message(LOG_LEVEL_ERROR, "Failed to allocate decompression buffer");
@@ -2,10 +2,8 @@
 #define COMPRESSION_H

 #include "data.h"
-#include <stdbool.h>

 Data* data_compress(Data* data_to_compress, int compression_level);
 Data* data_decompress(Data* compressed_data);
-bool compression_should_skip(const char* path);

 #endif
@@ -4,6 +4,7 @@
 #include "protocol.h"
 #include "utils.h"
 #include <stdbool.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -14,7 +15,7 @@ Config* config_create(char* version, char* send_directory, char* receive_directo
                      bool use_sendfile, unsigned long long chunk_size) {

  Config* config = malloc(sizeof(Config));
-  if (!config)
+  if (config == NULL)
    return NULL;
  config->version = version;
  config->send_directory = send_directory;
@@ -48,17 +49,10 @@ Config* config_create(char* version, char* send_directory, char* receive_directo
  config->tls_cert = NULL;
  config->tls_key = NULL;
  config->tls_ca = NULL;
+  config->follow_symlinks = false;
+  config->partial = false;
  config->server_host = str_dup("127.0.0.1");
  config->server_port = 8080;
-  config->timeout = 30;
-  config->contimeout = 10;
-  config->quiet = false;
-  config->backup = false;
-  config->backup_dir = NULL;
-  config->stats = false;
-  config->max_depth = 0;
-  config->log_file = NULL;
-  config->queue_size = 100;
  return config;
 }

@@ -89,6 +83,8 @@ void config_parse_ssh_dest(Config* config) {
 }

 void config_delete(Config* config) {
+  if (config == NULL)
+    return;
  free(config->version);
  free(config->send_directory);
  free(config->receive_root_directory);
@@ -103,7 +99,6 @@ void config_delete(Config* config) {
  free(config->tls_cert);
  free(config->tls_key);
  free(config->tls_ca);
-  free(config->backup_dir);
  free(config->server_host);
  free(config);
 }
@@ -141,9 +136,25 @@ bool config_send(int file_descriptor, const Config* config) {
    return false;
  if (!send_n_data(file_descriptor, &config->delta_max_file_size, sizeof(unsigned long long)))
    return false;
-  if (!send_int(file_descriptor, config->backup))
+  if (!send_int(file_descriptor, config->exclude_count))
    return false;
-  if (!send_str(file_descriptor, config->backup_dir ? config->backup_dir : ""))
+  for (int i = 0; i < config->exclude_count; i++) {
+    if (!send_str(file_descriptor, config->exclude_patterns[i]))
+      return false;
+  }
+  if (!send_int(file_descriptor, config->include_count))
+    return false;
+  for (int i = 0; i < config->include_count; i++) {
+    if (!send_str(file_descriptor, config->include_patterns[i]))
+      return false;
+  }
+  if (!send_n_data(file_descriptor, &config->max_size, sizeof(config->max_size)))
+    return false;
+  if (!send_n_data(file_descriptor, &config->min_size, sizeof(config->min_size)))
+    return false;
+  if (!send_int(file_descriptor, config->follow_symlinks))
+    return false;
+  if (!send_int(file_descriptor, config->partial))
    return false;
  Status status;
  if (!receive_status(file_descriptor, &status))
@@ -240,19 +251,82 @@ Config* config_receive(int file_descriptor) {
  config->tls_cert = NULL;
  config->tls_key = NULL;
  config->tls_ca = NULL;
-  config->timeout = 30;
-  config->contimeout = 10;
-  config->quiet = false;
-  config->stats = false;
-  config->max_depth = 0;
-  config->log_file = NULL;
-  config->queue_size = 100;
-  if (!receive_int(file_descriptor, &tmp))
+  config->follow_symlinks = false;
+  config->partial = false;
+
+#define MAX_PATTERN_COUNT 10000
+
+  // Receive exclude patterns
+  int ec;
+  if (!receive_int(file_descriptor, &ec))
    goto error;
-  config->backup = tmp;
-  config->backup_dir = receive_str(file_descriptor);
-  if (config->backup_dir == NULL)
+  if (ec > MAX_PATTERN_COUNT) {
+    log_message(LOG_LEVEL_ERROR, "Exclude pattern count %d exceeds maximum %d", ec,
+                MAX_PATTERN_COUNT);
    goto error;
+  }
+  config->exclude_count = ec;
+  if (ec > 0) {
+    config->exclude_patterns = malloc((size_t)ec * sizeof(char*));
+    if (!config->exclude_patterns) {
+      config->exclude_count = 0;
+      goto error;
+    }
+    for (int i = 0; i < ec; i++) {
+      config->exclude_patterns[i] = receive_str(file_descriptor);
+      if (!config->exclude_patterns[i]) {
+        for (int j = 0; j < i; j++)
+          free(config->exclude_patterns[j]);
+        free(config->exclude_patterns);
+        config->exclude_patterns = NULL;
+        config->exclude_count = 0;
+        goto error;
+      }
+    }
+  }
+
+  // Receive include patterns
+  int ic;
+  if (!receive_int(file_descriptor, &ic))
+    goto error;
+  if (ic > MAX_PATTERN_COUNT) {
+    log_message(LOG_LEVEL_ERROR, "Include pattern count %d exceeds maximum %d", ic,
+                MAX_PATTERN_COUNT);
+    goto error;
+  }
+  config->include_count = ic;
+  if (ic > 0) {
+    config->include_patterns = malloc((size_t)ic * sizeof(char*));
+    if (!config->include_patterns) {
+      config->include_count = 0;
+      goto error;
+    }
+    for (int i = 0; i < ic; i++) {
+      config->include_patterns[i] = receive_str(file_descriptor);
+      if (!config->include_patterns[i]) {
+        for (int j = 0; j < i; j++)
+          free(config->include_patterns[j]);
+        free(config->include_patterns);
+        config->include_patterns = NULL;
+        config->include_count = 0;
+        goto error;
+      }
+    }
+  }
+
+  if (!receive_n_data(file_descriptor, &config->max_size, sizeof(config->max_size)))
+    goto error;
+  if (!receive_n_data(file_descriptor, &config->min_size, sizeof(config->min_size)))
+    goto error;
+  int tmp_follow;
+  if (!receive_int(file_descriptor, &tmp_follow))
+    goto error;
+  config->follow_symlinks = tmp_follow;
+  int tmp_partial;
+  if (!receive_int(file_descriptor, &tmp_partial))
+    goto error;
+  config->partial = tmp_partial;
+
  config->server_host = str_dup("127.0.0.1");
  config->server_port = 8080;
  if (!send_status(file_descriptor, STATUS_OK))
@@ -263,8 +337,17 @@ error:
  free(config->version);
  free(config->send_directory);
  free(config->receive_root_directory);
+  for (int i = 0; i < config->exclude_count; i++)
+    free(config->exclude_patterns[i]);
+  free(config->exclude_patterns);
+  for (int i = 0; i < config->include_count; i++)
+    free(config->include_patterns[i]);
+  free(config->include_patterns);
+  free(config->tls_cert);
+  free(config->tls_key);
+  free(config->tls_ca);
+  free(config->ssh_destination);
  free(config->server_host);
-  free(config->backup_dir);
  free(config);
  return NULL;
 }
@@ -3,7 +3,6 @@

 #include <stdbool.h>
 #include <stdint.h>
-#include <stdio.h>

 typedef enum { TRANSPORT_TCP, TRANSPORT_SSH } TransportType;

@@ -42,18 +41,11 @@ typedef struct Config {
  char* tls_cert;
  char* tls_key;
  char* tls_ca;
-  int timeout;
-  int contimeout;
-  bool quiet;
-  bool backup;
-  char* backup_dir;
-  bool stats;
-  int max_depth;
-  FILE* log_file;
-  int queue_size;
+  bool follow_symlinks;
+  bool partial;
 } Config;

-#define PROTOCOL_VERSION "1.3.0"
+#define PROTOCOL_VERSION "2.0.0"
 #define DEFAULT_CHUNK_SIZE (10 * 1024 * 1024)

 Config* config_create(char* version, char* send_directory, char* receive_directory,
@@ -108,12 +108,7 @@ DeltaSignature* delta_signature_deserialize(const Data* data) {
    return NULL;
  }

-  uint64_t blocks_size = (uint64_t)sig->block_count * sizeof(DeltaBlockSig);
-  if (blocks_size > SIZE_MAX) {
-    free(sig);
-    return NULL;
-  }
-  sig->blocks = malloc((size_t)blocks_size);
+  sig->blocks = malloc(sig->block_count * sizeof(DeltaBlockSig));
  if (!sig->blocks) {
    free(sig);
    return NULL;
@@ -3,6 +3,7 @@
 #include <fcntl.h>
 #include <libgen.h>
 #include <stddef.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -21,6 +22,9 @@
 #include "protocol.h"
 #include "utils.h"

+#define STREAM_THRESHOLD (64ULL * 1024 * 1024) /* 64 MB */
+#define STREAM_CHUNK_SIZE (1ULL * 1024 * 1024) /* 1 MB */
+
 File* file_create(const char* path) {
  File* file = (File*)malloc(sizeof(File));
  if (file == NULL) {
@@ -35,7 +39,7 @@ File* file_create(const char* path) {
    return NULL;
  }

-  strcpy(file->path, path);
+  memcpy(file->path, path, path_len + 1);
  file->data = data_create_reserve(0);
  if (file->data == NULL) {
    free(file->path);
@@ -43,7 +47,8 @@ File* file_create(const char* path) {
    return NULL;
  }
  file->metadata = NULL;
-  file->skip = false;
+  file->type = FILE_TYPE_REGULAR;
+  file->link_target = NULL;
  return file;
 }

@@ -57,6 +62,8 @@ void file_destroy(void* item) {
  file->metadata = NULL;
  free(file->path);
  file->path = NULL;
+  free(file->link_target);
+  file->link_target = NULL;
  free(file);
 }

@@ -85,6 +92,14 @@ void file_metadata_destroy(void* metadata) {
 bool file_load_data(File* file) {
  if (file == NULL)
    return false;
+  // Symlinks have no data to load
+  if (file->type == FILE_TYPE_SYMLINK)
+    return true;
+  // For streaming files, just record the size, don't load into memory
+  if (file->data->size > STREAM_THRESHOLD) {
+    // Don't allocate; streaming will read directly from disk
+    return true;
+  }
  if (file->data->data == NULL) {
    file->data->data = malloc(file->data->size);
    if (file->data->data == NULL) {
@@ -95,16 +110,87 @@ bool file_load_data(File* file) {
  size_t bytes_read = file_content_to_buffer(file);
  if (bytes_read != file->data->size) {
    log_message(LOG_LEVEL_ERROR, "Did not read expected amount of bytes from file");
+    free(file->data->data);
+    file->data->data = NULL;
+    file->data->size = 0;
    return false;
  }
  return true;
 }

+// Stream file content in chunks without loading entire file into RAM
+static bool file_send_streaming(File* file, int file_descriptor) {
+  unsigned long long total_size = file->data->size;
+  // Send total size prefix (same wire format as send_data)
+  if (!send_n_data(file_descriptor, &total_size, sizeof(total_size)))
+    return false;
+
+  FILE* fp = fopen(file->path, "rb");
+  if (!fp) {
+    perror("Could not open file for streaming");
+    return false;
+  }
+
+  char* buf = malloc(STREAM_CHUNK_SIZE);
+  if (!buf) {
+    fclose(fp);
+    return false;
+  }
+  unsigned long long remaining = total_size;
+  while (remaining > 0) {
+    size_t to_read = (size_t)((remaining < STREAM_CHUNK_SIZE) ? remaining : STREAM_CHUNK_SIZE);
+    size_t nread = fread(buf, 1, to_read, fp);
+    if (nread != to_read) {
+      if (ferror(fp)) {
+        perror("Read error during streaming");
+      }
+      send_status(file_descriptor, STATUS_ERROR);
+      free(buf);
+      fclose(fp);
+      return false;
+    }
+    if (!send_n_data(file_descriptor, buf, nread)) {
+      send_status(file_descriptor, STATUS_ERROR);
+      free(buf);
+      fclose(fp);
+      return false;
+    }
+    remaining -= (unsigned long long)nread;
+  }
+  free(buf);
+  fclose(fp);
+  return true;
+}
+
 bool file_send_single_calls(File* file, int file_descriptor, bool use_metadata,
                            int compression_level, bool send_path) {
+  if (send_path && !send_str(file_descriptor, file->path))
+    return false;
+  if (use_metadata && !metadata_send(file_descriptor, file->metadata))
+    return false;
+
+  // Send file type indicator so receiver can distinguish regular from symlink
+  int ft = (int)file->type;
+  if (!send_int(file_descriptor, ft))
+    return false;
+
+  if (file->type == FILE_TYPE_SYMLINK) {
+    // Send link target, then zero-length data
+    if (!send_str(file_descriptor, file->link_target ? file->link_target : ""))
+      return false;
+    Data empty = {NULL, 0};
+    return send_data(file_descriptor, &empty);
+  }
+
  const Data* data_to_send = file->data;
  Data* compressed_data = NULL;
-  if (compression_level > 0 && !compression_should_skip(file->path)) {
+
+  // Streaming mode: for large files without compression, stream from disk
+  if (file->data->size > STREAM_THRESHOLD && compression_level == 0) {
+    return file_send_streaming(file, file_descriptor);
+  }
+
+  if (compression_level > 0) {
    compressed_data = data_compress(file->data, compression_level);
    if (compressed_data == NULL) {
      log_message(LOG_LEVEL_ERROR, "Failed to compress file data");
@@ -112,14 +198,6 @@ bool file_send_single_calls(File* file, int file_descriptor, bool use_metadata,
    }
    data_to_send = compressed_data;
  }
-  if (send_path && !send_str(file_descriptor, file->path)) {
-    data_destroy(compressed_data);
-    return false;
-  }
-  if (use_metadata && !metadata_send(file_descriptor, file->metadata)) {
-    data_destroy(compressed_data);
-    return false;
-  }
  if (!send_data(file_descriptor, data_to_send)) {
    data_destroy(compressed_data);
    return false;
@@ -128,15 +206,38 @@ bool file_send_single_calls(File* file, int file_descriptor, bool use_metadata,
  return true;
 }

-bool file_save_to_disk(const char* root_directory, File* file, const Config* config) {
-  (void)config;
-  if (has_path_traversal(file->path)) {
-    log_message(LOG_LEVEL_ERROR, "Path traversal detected in file path: %s", file->path);
-    return false;
+bool file_save_to_disk(const char* root_directory, File* file) {
+  if (file->type == FILE_TYPE_SYMLINK && file->link_target) {
+    // Validate link_target — reject absolute paths or traversal
+    if (file->link_target[0] == '/' || strstr(file->link_target, "..") != NULL) {
+      log_message(LOG_LEVEL_ERROR, "Path traversal blocked in symlink target: %s",
+                  file->link_target);
+      return false;
+    }
+    char* disk_path = path_cat((char*)root_directory, file->path);
+    if (disk_path == NULL)
+      return false;
+    if (strstr(disk_path, "..") != NULL) {
+      log_message(LOG_LEVEL_ERROR, "Path traversal blocked: %s", disk_path);
+      free(disk_path);
+      return false;
+    }
+    unlink(disk_path);
+    bool ok = (symlink(file->link_target, disk_path) == 0);
+    if (ok && file->metadata)
+      file_restore_metadata(disk_path, file->metadata);
+    free(disk_path);
+    return ok;
  }
+
  char* disk_path = path_cat((char*)root_directory, file->path);
  if (disk_path == NULL)
    return false;
+  if (strstr(disk_path, "..") != NULL) {
+    log_message(LOG_LEVEL_ERROR, "Path traversal blocked: %s", disk_path);
+    free(disk_path);
+    return false;
+  }
  bool ok = to_disk(disk_path, file->data->data, file->data->size);
  if (ok)
    file_restore_metadata(disk_path, file->metadata);
@@ -162,19 +263,60 @@ static void* old_data_from_path(const char* full_path, unsigned long long old_si
  return data;
 }

+/**
+ * Helper: receive data from wire, optionally decompress, and store in file.
+ * On success, returns the received Data* (caller owns it). On failure, returns NULL.
+ * If `file_data` is received via receive_data(fd), this function handles decompression
+ * when config->use_compression is set.
+ */
+static Data* receive_and_decompress(int fd, const Config* config) {
+  Data* file_data = receive_data(fd);
+  if (file_data == NULL)
+    return NULL;
+  if (config->use_compression) {
+    Data* uncompressed = data_decompress(file_data);
+    data_destroy(file_data);
+    if (uncompressed == NULL)
+      return NULL;
+    file_data = uncompressed;
+  }
+  return file_data;
+}
+
+/**
+ * Helper: receive metadata from wire and assign to file.
+ * Returns true on success (metadata may be NULL if absent), false on I/O error.
+ */
+static bool receive_and_assign_metadata(int fd, const Config* config, File* file) {
+  if (!config->use_metadata)
+    return true;
+  int meta_ok = 1;
+  file->metadata = metadata_receive(fd, &meta_ok);
+  if (!meta_ok) {
+    file_destroy(file);
+    send_status(fd, STATUS_ERROR);
+    return false;
+  }
+  return true;
+}
+
 static File* receive_delta_file(int fd, const Config* config, const char* check_path,
                                void* old_data, unsigned long long old_size) {
-  if (!old_data)
+  if (!old_data) {
+    send_status(fd, STATUS_ERROR);
    return NULL;
+  }

  DeltaSignature* sig = delta_signature_create(old_data, old_size, config->delta_block_size);
  if (!sig) {
+    send_status(fd, STATUS_ERROR);
    free(old_data);
    return NULL;
  }

  Data* sig_data = delta_signature_serialize(sig);
  if (!sig_data) {
+    send_status(fd, STATUS_ERROR);
    delta_signature_destroy(sig);
    free(old_data);
    return NULL;
@@ -277,34 +419,16 @@ static File* receive_delta_file(int fd, const Config* config, const char* check_
      return NULL;
    }

-    if (config->use_metadata) {
-      int meta_ok = 1;
-      file->metadata = metadata_receive(fd, &meta_ok);
-      if (!meta_ok) {
-        file_destroy(file);
-        send_status(fd, STATUS_ERROR);
-        return NULL;
-      }
-    }
+    if (!receive_and_assign_metadata(fd, config, file))
+      return NULL;

-    Data* file_data = receive_data(fd);
+    Data* file_data = receive_and_decompress(fd, config);
    if (file_data == NULL) {
      file_destroy(file);
      send_status(fd, STATUS_ERROR);
      return NULL;
    }

-    if (config->use_compression) {
-      Data* uncompressed = data_decompress(file_data);
-      data_destroy(file_data);
-      if (uncompressed == NULL) {
-        file_destroy(file);
-        send_status(fd, STATUS_ERROR);
-        return NULL;
-      }
-      file_data = uncompressed;
-    }
-
    data_destroy(file->data);
    file->data = file_data;
    return file;
@@ -332,18 +456,30 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
    return NULL;
  }

-  if (has_path_traversal(check_path)) {
-    log_message(LOG_LEVEL_ERROR, "Path traversal detected: %s", check_path);
+  char* full_path = path_cat(config->receive_root_directory, check_path);
+  if (full_path && strstr(full_path, "..") != NULL) {
+    log_message(LOG_LEVEL_ERROR, "Path traversal blocked: %s", full_path);
+    free(full_path);
    free(check_path);
    send_status(fd, STATUS_ERROR);
    return NULL;
  }
-
-  char* full_path = path_cat(config->receive_root_directory, check_path);
  struct stat st;
  bool has_old_file = (full_path && stat(full_path, &st) == 0);
  unsigned long long old_size = has_old_file ? (unsigned long long)st.st_size : 0;

+  // Check for partial file if enabled
+  if (config->partial && !has_old_file && full_path) {
+    char* partial_path = malloc(strlen(full_path) + 20);
+    if (partial_path) {
+      snprintf(partial_path, strlen(full_path) + 20, "%s.fastsync-partial", full_path);
+      has_old_file = (stat(partial_path, &st) == 0);
+      if (has_old_file)
+        old_size = (unsigned long long)st.st_size;
+      free(partial_path);
+    }
+  }
+
  bool match = has_old_file && (unsigned long long)st.st_size == check_size &&
               (long long)st.st_mtime == check_mtime;

@@ -389,32 +525,33 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
    return NULL;
  }

-  if (config->use_metadata) {
-    int meta_ok = 1;
-    file->metadata = metadata_receive(fd, &meta_ok);
-    if (!meta_ok) {
-      file_destroy(file);
-      send_status(fd, STATUS_ERROR);
-      return NULL;
-    }
-  }
+  if (!receive_and_assign_metadata(fd, config, file))
+    return NULL;

-  Data* file_data = receive_data(fd);
-  if (file_data == NULL) {
+  int file_type;
+  if (!receive_int(fd, &file_type)) {
    file_destroy(file);
    send_status(fd, STATUS_ERROR);
    return NULL;
  }
+  file->type = (FileType)file_type;

-  if (config->use_compression) {
-    Data* uncompressed = data_decompress(file_data);
-    data_destroy(file_data);
-    if (uncompressed == NULL) {
-      file_destroy(file);
-      send_status(fd, STATUS_ERROR);
-      return NULL;
+  if (file->type == FILE_TYPE_SYMLINK) {
+    char* link_target = receive_str(fd);
+    if (link_target) {
+      file->link_target = link_target;
    }
-    file_data = uncompressed;
+    Data* empty_data = receive_data(fd);
+    if (empty_data)
+      data_destroy(empty_data);
+    return file;
+  }
+
+  Data* file_data = receive_and_decompress(fd, config);
+  if (file_data == NULL) {
+    file_destroy(file);
+    send_status(fd, STATUS_ERROR);
+    return NULL;
  }

  data_destroy(file->data);
@@ -423,68 +560,51 @@ File* receive_incremental_check(int fd, const Config* config, bool* skipped) {
 }

 bool to_disk(const char* path, const void* data, unsigned long long data_size) {
-  char* tmp_path = NULL;
-  char* directory = NULL;
-
+  // dirname() may modify its argument and may return a pointer to static storage.
+  // We must use a copy of the result to be safe.
  char* path_dup = str_dup(path);
  if (!path_dup)
    return false;
  const char* dir_result = dirname(path_dup);
-  directory = str_dup(dir_result);
+  char* directory = str_dup(dir_result);
  free(path_dup);
  if (!directory)
    return false;

  bool ok = true;
-  if (!mkdir_r(directory))
-    goto done;
-
-  size_t path_len = strlen(path);
-  tmp_path = malloc(path_len + 5);
-  if (!tmp_path) {
+  if (!mkdir_r(directory)) {
    ok = false;
    goto done;
  }
-  memcpy(tmp_path, path, path_len);
-  memcpy(tmp_path + path_len, ".tmp", 5);
-
-  FILE* file_pointer = fopen(tmp_path, "wb");
+  FILE* file_pointer = fopen(path, "wb");
  if (file_pointer == NULL) {
-    perror("Could not open temporary file");
+    perror("Could not open File");
    ok = false;
    goto done;
  }
  if (fwrite(data, 1, data_size, file_pointer) != data_size) {
-    perror("Failed to write all data to temporary file");
+    perror("Failed to write all data to disk");
    fclose(file_pointer);
-    unlink(tmp_path);
    ok = false;
    goto done;
  }
  fclose(file_pointer);

-  if (rename(tmp_path, path) != 0) {
-    perror("Failed to atomically rename temporary file");
-    unlink(tmp_path);
-    ok = false;
-    goto done;
-  }
-
 done:
-  free(tmp_path);
  free(directory);
  return ok;
 }

 bool file_send_sendfile(File* file, int file_descriptor, bool use_metadata, int compression_level,
                        bool send_path) {
+  // Handle symlinks
+  if (file->type == FILE_TYPE_SYMLINK) {
+    return file_send_single_calls(file, file_descriptor, use_metadata, compression_level,
+                                  send_path);
+  }
+
  // sendfile is incompatible with compression (kernel zero-copy).
  // If compression is requested, fall back to the regular send path.
-  // NOTE: This is a safety net only — callers must ensure compression_level == 0
-  // before calling file_send_sendfile. The fallback to file_send_single_calls
-  // preserves the send_path contract, but callers should not rely on it for
-  // correctness (the --sendfile flag is validated to be mutually exclusive with
-  // -c/--compress at the CLI layer).
  if (compression_level > 0)
    return file_send_single_calls(file, file_descriptor, use_metadata, compression_level,
                                  send_path);
@@ -494,6 +614,10 @@ bool file_send_sendfile(File* file, int file_descriptor, bool use_metadata, int
  if (use_metadata && !metadata_send(file_descriptor, file->metadata))
    return false;

+  int ft = (int)file->type;
+  if (!send_int(file_descriptor, ft))
+    return false;
+
  int fd = open(file->path, O_RDONLY);
  if (fd == -1) {
    perror("Could not open file for sendfile");
@@ -508,8 +632,13 @@ bool file_send_sendfile(File* file, int file_descriptor, bool use_metadata, int

  off_t offset = 0;
  while ((unsigned long long)offset < file_size) {
-    ssize_t sent = sendfile(file_descriptor, fd, &offset, file_size - offset);
+    size_t send_count = (size_t)(file_size - (unsigned long long)offset);
+    if ((unsigned long long)send_count != file_size - (unsigned long long)offset)
+      send_count = SIZE_MAX;
+    ssize_t sent = sendfile(file_descriptor, fd, &offset, send_count);
    if (sent == -1) {
+      if (errno == EINTR)
+        continue;
      perror("sendfile failed");
      close(fd);
      return false;
@@ -536,6 +665,30 @@ File* file_receive(const Config* config, int file_descriptor) {
      return NULL;
    }
  }
+
+  // Receive file type indicator
+  int file_type;
+  if (!receive_int(file_descriptor, &file_type)) {
+    file_destroy(file);
+    return NULL;
+  }
+  file->type = (FileType)file_type;
+
+  if (file->type == FILE_TYPE_SYMLINK) {
+    char* link_target = receive_str(file_descriptor);
+    if (link_target == NULL) {
+      file_destroy(file);
+      return NULL;
+    }
+    file->link_target = link_target;
+    // Receive and discard zero-length data
+    Data* empty_data = receive_data(file_descriptor);
+    if (empty_data)
+      data_destroy(empty_data);
+    return file;
+  }
+
+  // Regular file - receive data
  Data* file_data = receive_data(file_descriptor);
  if (file_data == NULL) {
    file_destroy(file);
@@ -550,6 +703,7 @@ File* file_receive(const Config* config, int file_descriptor) {
    }
    file_data = file_data_uncompressed;
  }
+
  data_destroy(file->data);
  file->data = file_data;
  return file;
@@ -20,7 +20,8 @@ typedef struct {
  char* path;
  Data* data;
  FileMetadata* metadata;
-  bool skip;
+  FileType type;
+  char* link_target;
 } File;

 File* file_create(const char* path);
@@ -35,7 +36,7 @@ size_t file_content_to_buffer(File* file);
 FileMetadata* file_metadata_create(const struct stat* stats);
 void file_metadata_destroy(void* metadata);
 bool to_disk(const char* path, const void* data, unsigned long long data_size);
-bool file_save_to_disk(const char* root_directory, File* file, const Config* config);
+bool file_save_to_disk(const char* root_directory, File* file);
 File* receive_incremental_check(int fd, const Config* config, bool* skipped);
 int receive_manifest(int fd, const Config* config, int* next_status);

@@ -5,21 +5,19 @@

 static const char* log_level_strings[] = {"DEBUG", "INFO", "WARN", "ERROR"};
 static LogLevel current_log_level = LOG_LEVEL_WARNING;
-static FILE* log_fp = NULL;

 void set_log_level(LogLevel level) {
  current_log_level = level;
 }

-void log_set_file(FILE* fp) {
-  log_fp = fp;
-}
-
 void log_message(LogLevel log_level, const char* format, ...) {
  if (log_level < current_log_level)
    return;
  time_t now = time(NULL);
-  const struct tm* t = localtime(&now);
+  struct tm result_buf;
+  const struct tm* t = localtime_r(&now, &result_buf);
+  if (t == NULL)
+    return;

  fprintf(stderr, "%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]);
@@ -29,14 +27,4 @@ void log_message(LogLevel log_level, const char* format, ...) {
  vfprintf(stderr, format, args);
  va_end(args);
  fprintf(stderr, "\n");
-
-  if (log_fp) {
-    fprintf(log_fp, "%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]);
-    va_start(args, format);
-    vfprintf(log_fp, format, args);
-    va_end(args);
-    fprintf(log_fp, "\n");
-    fflush(log_fp);
-  }
 }
@@ -1,12 +1,9 @@
 #ifndef LOG_H
 #define LOG_H

-#include <stdio.h>
-
 typedef enum { LOG_LEVEL_DEBUG, LOG_LEVEL_INFO, LOG_LEVEL_WARNING, LOG_LEVEL_ERROR } LogLevel;

 void log_message(LogLevel log_level, const char* message, ...);
 void set_log_level(LogLevel level);
-void log_set_file(FILE* fp);

 #endif
@@ -105,16 +105,7 @@ int receive_thread(void* pipeline_context) {
  Status status;
  if (!receive_status(file_descriptor, &status))
    return thrd_error;
-  while (status == STATUS_NEXT || status == STATUS_CHUNK || status == STATUS_CHECK ||
-         status == STATUS_KEEPALIVE || status == STATUS_ABORT || status == STATUS_CHECK_BATCH) {
-    if (status == STATUS_KEEPALIVE) {
-      send_status(file_descriptor, STATUS_KEEPALIVE);
-      goto next;
-    }
-    if (status == STATUS_ABORT) {
-      log_message(LOG_LEVEL_INFO, "Received abort from client, cleaning up");
-      return thrd_error;
-    }
+  while (status == STATUS_NEXT || status == STATUS_CHUNK || status == STATUS_CHECK) {
    if (status == STATUS_CHECK) {
      bool skipped;
      File* file = receive_incremental_check(file_descriptor, config, &skipped);
@@ -126,34 +117,6 @@ int receive_thread(void* pipeline_context) {
      }
    } else if (status == STATUS_CHUNK) {
      receive_chunk_enqueue(file_descriptor, context);
-    } else if (status == STATUS_CHECK_BATCH) {
-      int count;
-      if (!receive_int(file_descriptor, &count))
-        return thrd_error;
-      for (int i = 0; i < count; i++) {
-        char* check_path = receive_str(file_descriptor);
-        if (!check_path)
-          return thrd_error;
-        unsigned long long check_size;
-        long long check_mtime;
-        if (!receive_n_data(file_descriptor, &check_size, sizeof(check_size)) ||
-            !receive_n_data(file_descriptor, &check_mtime, sizeof(check_mtime))) {
-          free(check_path);
-          return thrd_error;
-        }
-        char* full_path = path_cat(config->receive_root_directory, check_path);
-        struct stat st;
-        bool has_old = full_path && stat(full_path, &st) == 0;
-        bool match = has_old && (unsigned long long)st.st_size == check_size &&
-                     (long long)st.st_mtime == check_mtime;
-        if (match)
-          send_status(file_descriptor, STATUS_OK);
-        else
-          send_status(file_descriptor, STATUS_NEXT);
-        free(full_path);
-        free(check_path);
-      }
-      goto next;
    } else {
      File* file = file_receive(config, file_descriptor);
      if (file) {
@@ -163,7 +126,6 @@ int receive_thread(void* pipeline_context) {
        log_message(LOG_LEVEL_ERROR, "Failed to receive file");
      }
    }
-  next:
    if (!receive_status(file_descriptor, &status))
      return thrd_error;
  }
@@ -194,7 +156,7 @@ int write_thread(void* pipeline_context) {
      return thrd_success;
    }
    if (save_to_disk)
-      file_save_to_disk(root_directory, file, context->config);
+      file_save_to_disk(root_directory, file);
    file_destroy(file);
  }
 }
@@ -2,27 +2,20 @@
 #include "log.h"
 #include <errno.h>
 #include <openssl/ssl.h>
-#include <poll.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <time.h>
 #include <unistd.h>

-#define MAX_DATA_SIZE (256ULL * 1024 * 1024)          /* 256 MB max per message */
-#define RECEIVE_TIMEOUT_SEC 60                        /* 60 second per-message timeout */
-#define MAX_CONNECTION_MEMORY (1024ULL * 1024 * 1024) /* 1 GB total per connection */
-
 static __thread int io_read_fd = -1;
 static __thread int io_write_fd = -1;
-static SSL* io_ssl;
+static SSL* io_ssl = NULL;

 static unsigned long long io_bwlimit = 0;
 static long long bw_tokens = 0;
 static struct timespec bw_last_refill = {0, 0};

-static __thread unsigned long long total_allocated_bytes = 0;
-
 void io_set_fds(int read_fd, int write_fd) {
  io_read_fd = read_fd;
  io_write_fd = write_fd;
@@ -53,11 +46,12 @@ static void bw_throttle(size_t bytes_written) {
  bw_tokens -= (long long)bytes_written;

  if (bw_tokens < 0) {
-    long long deficit_us = (long long)((double)(-bw_tokens) / io_bwlimit * 1000000.0);
-    if (deficit_us >= 1000)
-      poll(NULL, 0, (int)(deficit_us / 1000));
-    else
-      usleep((useconds_t)deficit_us);
+    long long deficit_ns = (long long)((double)(-bw_tokens) / io_bwlimit * 1000000000.0);
+    struct timespec sleep_time, remaining;
+    sleep_time.tv_sec = deficit_ns / 1000000000LL;
+    sleep_time.tv_nsec = deficit_ns % 1000000000LL;
+    while (nanosleep(&sleep_time, &remaining) < 0 && errno == EINTR)
+      sleep_time = remaining;
    bw_tokens = 0;
    clock_gettime(CLOCK_MONOTONIC, &bw_last_refill);
  }
@@ -103,21 +97,8 @@ bool send_n_data(int file_descriptor, const void* data, size_t data_size) {
 bool receive_n_data(int file_descriptor, void* data, size_t data_size) {
  log_message(LOG_LEVEL_DEBUG, "    Receiving n Data: %zu", data_size);
  int fd = io_fd(io_read_fd, file_descriptor);
-
-  struct timespec deadline;
-  clock_gettime(CLOCK_MONOTONIC, &deadline);
-  deadline.tv_sec += RECEIVE_TIMEOUT_SEC;
-
  size_t total_bytes_received = 0;
  while (total_bytes_received < data_size) {
-    struct timespec now;
-    clock_gettime(CLOCK_MONOTONIC, &now);
-    if (now.tv_sec > deadline.tv_sec ||
-        (now.tv_sec == deadline.tv_sec && now.tv_nsec > deadline.tv_nsec)) {
-      log_message(LOG_LEVEL_ERROR, "Receive timeout after %ds", RECEIVE_TIMEOUT_SEC);
-      return false;
-    }
-
    ssize_t bytes_received;
    if (io_ssl)
      bytes_received =
@@ -126,9 +107,9 @@ bool receive_n_data(int file_descriptor, void* data, size_t data_size) {
      bytes_received =
          read(fd, (char*)data + total_bytes_received, data_size - total_bytes_received);
    if (bytes_received <= 0) {
-      if (io_ssl) {
+      if (io_ssl && bytes_received < 0) {
        int ssl_err = SSL_get_error(io_ssl, (int)bytes_received);
-        if (ssl_err == SSL_ERROR_WANT_WRITE || ssl_err == SSL_ERROR_WANT_READ)
+        if (ssl_err == SSL_ERROR_WANT_READ || ssl_err == SSL_ERROR_WANT_WRITE)
          continue;
      }
      if (bytes_received == 0)
@@ -161,18 +142,16 @@ static const char* status_to_string(Status status) {
    return "DELTA_SIGNATURE";
  case STATUS_DELTA_DATA:
    return "DELTA_DATA";
-  case STATUS_KEEPALIVE:
-    return "KEEPALIVE";
-  case STATUS_ABORT:
-    return "ABORT";
-  case STATUS_CHECK_BATCH:
-    return "CHECK_BATCH";
  default:
    return "UNKNOWN";
  }
 }

 bool send_str(int file_descriptor, const char* data) {
+  if (data == NULL) {
+    log_message(LOG_LEVEL_ERROR, "send_str called with NULL data");
+    return false;
+  }
  size_t size = strlen(data);
  if (!send_n_data(file_descriptor, &size, sizeof(size_t)))
    return false;
@@ -186,9 +165,9 @@ char* receive_str(int file_descriptor) {
  size_t size;
  if (!receive_n_data(file_descriptor, &size, sizeof(size_t)))
    return NULL;
-  if (size > MAX_DATA_SIZE) {
-    log_message(LOG_LEVEL_ERROR, "String size %zu exceeds maximum %llu", size,
-                (unsigned long long)MAX_DATA_SIZE);
+  if (size > MAX_STRING_SIZE) {
+    log_message(LOG_LEVEL_ERROR, "receive_str: size %zu exceeds maximum %zu", size,
+                (size_t)MAX_STRING_SIZE);
    return NULL;
  }
  char* data = (char*)malloc(size + 1);
@@ -209,23 +188,18 @@ bool send_data(int file_descriptor, const Data* data) {
    return false;
  if (!send_n_data(file_descriptor, data->data, data_size))
    return false;
-  log_message(LOG_LEVEL_DEBUG, "Send %lld data", data_size);
+  log_message(LOG_LEVEL_DEBUG, "Send %llu data", data_size);
  return true;
 }

+#define MAX_DATA_SIZE (1024ULL * 1024 * 1024)
+
 Data* receive_data(int file_descriptor) {
  unsigned long long size = 0;
  if (!receive_n_data(file_descriptor, &size, sizeof(unsigned long long)))
    return NULL;
-  if (size > MAX_DATA_SIZE) {
-    log_message(LOG_LEVEL_ERROR, "Data size %llu exceeds maximum %llu", size,
-                (unsigned long long)MAX_DATA_SIZE);
-    return NULL;
-  }
-  if (total_allocated_bytes + size > MAX_CONNECTION_MEMORY) {
-    log_message(LOG_LEVEL_ERROR, "Per-connection memory limit exceeded (%llu + %llu > %llu)",
-                (unsigned long long)total_allocated_bytes, size,
-                (unsigned long long)MAX_CONNECTION_MEMORY);
+  if ((size_t)size != size || size > MAX_DATA_SIZE) {
+    log_message(LOG_LEVEL_ERROR, "receive_data size %llu exceeds limits", size);
    return NULL;
  }
  void* data = malloc((size_t)size);
@@ -235,8 +209,7 @@ Data* receive_data(int file_descriptor) {
    free(data);
    return NULL;
  }
-  total_allocated_bytes += size;
-  log_message(LOG_LEVEL_DEBUG, "Received %lld data", size);
+  log_message(LOG_LEVEL_DEBUG, "Received %llu data", size);
  return data_create(data, (size_t)size);
 }

@@ -20,10 +20,7 @@ enum NET_STATUS {
  STATUS_MANIFEST,
  STATUS_CHECK,
  STATUS_DELTA_SIGNATURE,
-  STATUS_DELTA_DATA,
-  STATUS_KEEPALIVE,
-  STATUS_ABORT,
-  STATUS_CHECK_BATCH
+  STATUS_DELTA_DATA
 };

 void io_set_fds(int read_fd, int write_fd);
@@ -118,20 +118,19 @@ Client* client_connect_ssh(const char* destination, int port, const char* server
    if (sv[1] > 1)
      close(sv[1]);

-    size_t ssh_user_len;
+    char ssh_user[512];
+    int needed;
    if (r.user && r.user[0] != '\0')
-      ssh_user_len = strlen(r.user) + 1 + strlen(r.host) + 1;
+      needed = snprintf(ssh_user, sizeof(ssh_user), "%s@%s", r.user, r.host);
    else
-      ssh_user_len = strlen(r.host) + 1;
-    char* ssh_user = malloc(ssh_user_len);
-    if (!ssh_user)
-      _exit(1);
-    if (r.user && r.user[0] != '\0')
-      snprintf(ssh_user, ssh_user_len, "%s@%s", r.user, r.host);
-    else
-      snprintf(ssh_user, ssh_user_len, "%s", r.host);
+      needed = snprintf(ssh_user, sizeof(ssh_user), "%s", r.host);
+    if ((size_t)needed >= sizeof(ssh_user))
+      fprintf(stderr, "Warning: ssh_user string truncated\n");

-    char* ssh_argv[16];
+    size_t ssh_argv_max = 32;
+    char** ssh_argv = calloc(ssh_argv_max, sizeof(char*));
+    if (ssh_argv == NULL)
+      _exit(1);
    int ac = 0;
    char port_str[16];
    ssh_argv[ac++] = "ssh";
@@ -142,15 +141,22 @@ Client* client_connect_ssh(const char* destination, int port, const char* server
    ssh_argv[ac++] = "-o";
    ssh_argv[ac++] = "ControlPath=~/.cache/fastsync-%r@%h:%p";
    if (port > 0 && port != 22) {
+      if ((size_t)ac + 2 >= ssh_argv_max) {
+        _exit(1);
+      }
      ssh_argv[ac++] = "-p";
      snprintf(port_str, sizeof(port_str), "%d", port);
      ssh_argv[ac++] = port_str;
    }
+    if ((size_t)ac + 3 >= ssh_argv_max) {
+      _exit(1);
+    }
    ssh_argv[ac++] = ssh_user;
    ssh_argv[ac++] = (char*)(server_path ? server_path : "fastsync-server");
    ssh_argv[ac++] = "--stdio";
    ssh_argv[ac] = NULL;
    execvp("ssh", ssh_argv);
+    free(ssh_argv);
    perror("exec of ssh failed");
    ssize_t wret = write(exec_pipe[1], "x", 1);
    (void)wret;
@@ -182,7 +188,7 @@ Client* client_connect_ssh(const char* destination, int port, const char* server
    return NULL;
  }
  client->file_descriptor = sv[0];
-  client->address.sin_family = AF_UNIX;
+  client->address.ss_family = AF_UNIX;
  client->address_length = 0;
  client->ssh_child_pid = pid;
  client->ssl = NULL;
@@ -3,25 +3,36 @@
 #include "protocol.h"
 #include <arpa/inet.h>
 #include <errno.h>
+#include <netdb.h>
 #include <openssl/ssl.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/socket.h>
+#include <sys/types.h>
 #include <sys/wait.h>
 #include <unistd.h>

-static volatile sig_atomic_t g_active_connections = 0;
+bool set_socket_timeouts(int fd) {
+  struct timeval tv;
+  tv.tv_sec = 30;
+  tv.tv_usec = 0;

-static void sigchld_handler(int sig) {
-  (void)sig;
-  int saved_errno = errno;
-  while (waitpid(-1, NULL, WNOHANG) > 0) {
-    if (g_active_connections > 0)
-      g_active_connections--;
+  int keepalive = 1;
+  if (setsockopt(fd, SOL_SOCKET, SO_KEEPALIVE, &keepalive, sizeof(keepalive)) < 0) {
+    perror("Could not set SO_KEEPALIVE");
+    return false;
  }
-  errno = saved_errno;
+  if (setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv)) < 0) {
+    perror("Could not set SO_RCVTIMEO");
+    return false;
+  }
+  if (setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv)) < 0) {
+    perror("Could not set SO_SNDTIMEO");
+    return false;
+  }
+  return true;
 }

 Server* server_create(int port) {
@@ -30,14 +41,29 @@ Server* server_create(int port) {
    perror("Could not allocate space for Server");
    return NULL;
  }
+  memset(&server->address, 0, sizeof(server->address));

-  int file_descriptor = socket(AF_INET, SOCK_STREAM, 0);
-  if (file_descriptor < 0) {
+  // Try IPv6 first, fall back to IPv4
+  int fd = socket(AF_INET6, SOCK_STREAM, 0);
+  sa_family_t domain = AF_INET6;
+  if (fd < 0) {
+    fd = socket(AF_INET, SOCK_STREAM, 0);
+    domain = AF_INET;
+  }
+  if (fd < 0) {
    perror("Could not create Socket!");
    free(server);
    return NULL;
  }
-  server->file_descriptor = file_descriptor;
+
+  if (!set_socket_timeouts(fd)) {
+    close(fd);
+    free(server);
+    return NULL;
+  }
+
+  server->file_descriptor = fd;
+  server->ssl_ctx = NULL;
  int opt = 1;
  if (setsockopt(server->file_descriptor, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt))) {
    perror("Error setting a socket option!");
@@ -46,20 +72,60 @@ Server* server_create(int port) {
    return NULL;
  }

-  server->address.sin_family = AF_INET;
-  server->address.sin_addr.s_addr = INADDR_ANY;
-  server->address.sin_port = htons(port);
-  server->address_length = sizeof(server->address);
-  server->ssl_ctx = NULL;
-  server->max_connections = 100;
-  server->active_connections = 0;
+  // Use the domain from the socket we actually created
+  struct sockaddr_storage* addr = &server->address;
+  struct sockaddr_in* addr4 = (struct sockaddr_in*)addr;
+  struct sockaddr_in6* addr6 = (struct sockaddr_in6*)addr;
+
+  if (domain == AF_INET6) {
+    addr6->sin6_family = AF_INET6;
+    addr6->sin6_addr = in6addr_any;
+    addr6->sin6_port = htons(port);
+    addr->ss_family = AF_INET6;
+    server->address_length = sizeof(struct sockaddr_in6);
+  } else {
+    addr4->sin_family = AF_INET;
+    addr4->sin_addr.s_addr = INADDR_ANY;
+    addr4->sin_port = htons(port);
+    addr->ss_family = AF_INET;
+    server->address_length = sizeof(struct sockaddr_in);
+  }

  if (bind(server->file_descriptor, (struct sockaddr*)&server->address, server->address_length) <
      0) {
-    perror("Could not bind server");
-    close(server->file_descriptor);
-    free(server);
-    return NULL;
+    // If IPv6 bind failed (maybe no IPv6), try IPv4
+    if (domain == AF_INET6) {
+      close(fd);
+      fd = socket(AF_INET, SOCK_STREAM, 0);
+      if (fd < 0) {
+        perror("Could not create IPv4 Socket!");
+        free(server);
+        return NULL;
+      }
+      if (!set_socket_timeouts(fd)) {
+        close(fd);
+        free(server);
+        return NULL;
+      }
+      server->file_descriptor = fd;
+      setsockopt(server->file_descriptor, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
+      memset(addr, 0, sizeof(*addr));
+      addr4->sin_family = AF_INET;
+      addr4->sin_addr.s_addr = INADDR_ANY;
+      addr4->sin_port = htons(port);
+      server->address_length = sizeof(struct sockaddr_in);
+      if (bind(server->file_descriptor, (struct sockaddr*)addr, server->address_length) < 0) {
+        perror("Could not bind server");
+        close(server->file_descriptor);
+        free(server);
+        return NULL;
+      }
+    } else {
+      perror("Could not bind server");
+      close(server->file_descriptor);
+      free(server);
+      return NULL;
+    }
  }

  return server;
@@ -77,27 +143,36 @@ void server_delete(Server** server) {
  *server = NULL;
 }

+/* Flag set by server_request_shutdown() to request graceful shutdown
+   of the accept loop. Accessed only from transport_tcp.c so it won't
+   cause linker errors when this file is compiled into client/test targets. */
+static volatile sig_atomic_t g_tcp_cleanup_requested = 0;
+
+void server_request_shutdown(void) {
+  g_tcp_cleanup_requested = 1;
+}
+
 static void accept_loop(Server* server, void (*child_fn)(int, void*), void* child_ctx,
                        const char* log_fmt) {
  if (listen(server->file_descriptor, SOMAXCONN) < 0) {
    perror("Could not listen on port!");
    return;
  }
-  signal(SIGCHLD, sigchld_handler);
-  while (1) {
-    struct sockaddr_in client_addr;
+  signal(SIGCHLD, SIG_IGN);
+  while (!g_tcp_cleanup_requested) {
+    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) {
+      if (errno == EINTR) {
+        if (g_tcp_cleanup_requested)
+          break;
+        continue;
+      }
      perror("Could not accept the connection");
      continue;
    }
-    if ((unsigned int)g_active_connections >= server->max_connections) {
-      log_message(LOG_LEVEL_WARNING, "Max connections (%u) reached, rejecting",
-                  server->max_connections);
-      close(fd);
-      continue;
-    }
+    set_socket_timeouts(fd);
    log_message(LOG_LEVEL_INFO, "%s", log_fmt);
    pid_t pid = fork();
    if (pid == 0) {
@@ -105,8 +180,6 @@ static void accept_loop(Server* server, void (*child_fn)(int, void*), void* chil
      child_fn(fd, child_ctx);
      close(fd);
      _exit(0);
-    } else if (pid > 0) {
-      g_active_connections++;
    }
    close(fd);
  }
@@ -121,7 +194,11 @@ static void plain_child_fn(int fd, void* ctx) {
 }

 bool server_listen(Server* server, void (*handler)(int file_descriptor)) {
-  log_message(LOG_LEVEL_INFO, "Start Listening on Port: %d", ntohs(server->address.sin_port));
+  struct sockaddr_in* addr4 = (struct sockaddr_in*)&server->address;
+  int port = (server->address.ss_family == AF_INET6)
+                 ? ntohs(((struct sockaddr_in6*)&server->address)->sin6_port)
+                 : ntohs(addr4->sin_port);
+  log_message(LOG_LEVEL_INFO, "Start Listening on Port: %d", port);
  struct plain_ctx ctx = {handler};
  accept_loop(server, plain_child_fn, &ctx, "Received Connection");
  return true;
@@ -129,43 +206,23 @@ 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) {
-  log_message(LOG_LEVEL_INFO, "Start TLS Listening on Port: %d", ntohs(server->address.sin_port));
+  struct sockaddr_in* addr4 = (struct sockaddr_in*)&server->address;
+  int port = (server->address.ss_family == AF_INET6)
+                 ? ntohs(((struct sockaddr_in6*)&server->address)->sin6_port)
+                 : ntohs(addr4->sin_port);
+  log_message(LOG_LEVEL_INFO, "Start TLS Listening on Port: %d", port);
  accept_loop(server, child_fn, child_ctx, log_fmt);
 }

-static int g_timeout_sec = 30;
-static int g_contimeout_sec = 10;
-
-void tcp_set_timeouts(int timeout_sec, int contimeout_sec) {
-  if (timeout_sec > 0)
-    g_timeout_sec = timeout_sec;
-  if (contimeout_sec > 0)
-    g_contimeout_sec = contimeout_sec;
-}
-
-static void tcp_apply_socket_timeout(int fd) {
-  struct timeval tv;
-  tv.tv_sec = g_timeout_sec;
-  tv.tv_usec = 0;
-  setsockopt(fd, SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
-  setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
-}
-
 Client* client_create() {
-  int file_descriptor = socket(AF_INET, SOCK_STREAM, 0);
-  if (file_descriptor < 0) {
-    perror("Could not create Socket!");
-    return NULL;
-  }
-
  Client* client = (Client*)malloc(sizeof(Client));
  if (client == NULL) {
-    close(file_descriptor);
    return NULL;
  }
-  client->file_descriptor = file_descriptor;
-  client->address.sin_family = AF_INET;
+  memset(&client->address, 0, sizeof(client->address));
+  client->address.ss_family = AF_UNSPEC;
  client->address_length = sizeof(client->address);
+  client->file_descriptor = -1;
  client->ssh_child_pid = -1;
  client->ssl = NULL;
  client->ssl_ctx = NULL;
@@ -173,28 +230,55 @@ Client* client_create() {
 }

 bool client_connect(Client* client, char* host, int port) {
-  client->address.sin_port = htons(port);
-  client->address.sin_family = AF_INET;
-  client->address_length = sizeof(client->address);
+  struct addrinfo hints, *res, *rp;
+  memset(&hints, 0, sizeof(hints));
+  hints.ai_family = AF_UNSPEC;
+  hints.ai_socktype = SOCK_STREAM;

-  if (inet_pton(AF_INET, host, &client->address.sin_addr) <= 0) {
-    perror("Could not convert host address!");
+  char port_str[16];
+  snprintf(port_str, sizeof(port_str), "%d", port);
+
+  int gai_err = getaddrinfo(host, port_str, &hints, &res);
+  if (gai_err != 0) {
+    fprintf(stderr, "getaddrinfo: %s\n", gai_strerror(gai_err));
    return false;
  }

-  struct timeval ct;
-  ct.tv_sec = g_contimeout_sec;
-  ct.tv_usec = 0;
-  setsockopt(client->file_descriptor, SOL_SOCKET, SO_RCVTIMEO, &ct, sizeof(ct));
-  setsockopt(client->file_descriptor, SOL_SOCKET, SO_SNDTIMEO, &ct, sizeof(ct));
+  // Try IPv6 first, then IPv4
+  int fd = -1;
+  for (rp = res; rp != NULL; rp = rp->ai_next) {
+    fd = socket(rp->ai_family, rp->ai_socktype, rp->ai_protocol);
+    if (fd < 0)
+      continue;
+    if (!set_socket_timeouts(fd)) {
+      close(fd);
+      fd = -1;
+      continue;
+    }
+    if (connect(fd, rp->ai_addr, rp->ai_addrlen) == 0)
+      break;
+    close(fd);
+    fd = -1;
+  }

-  if (connect(client->file_descriptor, (struct sockaddr*)&client->address, client->address_length) <
-      0) {
+  if (fd < 0) {
    perror("Could not connect to Server!");
+    freeaddrinfo(res);
    return false;
  }

-  tcp_apply_socket_timeout(client->file_descriptor);
+  // Save the connected address
+  socklen_t addr_len = rp->ai_addrlen;
+  if (addr_len > sizeof(client->address))
+    addr_len = sizeof(client->address);
+  memcpy(&client->address, rp->ai_addr, addr_len);
+  client->address_length = addr_len;
+  freeaddrinfo(res);
+
+  // Close old fd if any and set new one
+  if (client->file_descriptor >= 0)
+    close(client->file_descriptor);
+  client->file_descriptor = fd;
  return true;
 }

@@ -205,7 +289,10 @@ void client_disconnect(Client* client) {
    client->ssl = NULL;
    io_set_ssl(NULL);
  }
-  close(client->file_descriptor);
+  if (client->file_descriptor >= 0) {
+    close(client->file_descriptor);
+    client->file_descriptor = -1;
+  }
  if (client->ssh_child_pid > 0) {
    int status;
    waitpid(client->ssh_child_pid, &status, 0);
@@ -216,6 +303,7 @@ void client_disconnect(Client* client) {
 void client_delete(Client* client) {
  if (client == NULL)
    return;
+  client_disconnect(client);
  if (client->ssl_ctx) {
    SSL_CTX_free(client->ssl_ctx);
    client->ssl_ctx = NULL;
@@ -1,21 +1,21 @@
 #ifndef TRANSPORT_TCP_H
 #define TRANSPORT_TCP_H

+#include <netdb.h>
 #include <netinet/in.h>
 #include <stdbool.h>
+#include <sys/socket.h>
 #include <sys/types.h>

 typedef struct Server {
-  struct sockaddr_in address;
+  struct sockaddr_storage address;
  unsigned int address_length;
  int file_descriptor;
  void* ssl_ctx;
-  unsigned int max_connections;
-  volatile unsigned int active_connections;
 } Server;

 typedef struct Client {
-  struct sockaddr_in address;
+  struct sockaddr_storage address;
  unsigned int address_length;
  int file_descriptor;
  pid_t ssh_child_pid;
@@ -28,10 +28,11 @@ 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);
 void server_delete(Server** server);
+void server_request_shutdown(void);
 Client* client_create();
 bool client_connect(Client* client, char* host, int port);
 void client_disconnect(Client* client);
 void client_delete(Client* client);
-void tcp_set_timeouts(int timeout_sec, int contimeout_sec);
+bool set_socket_timeouts(int fd);

 #endif
@@ -5,6 +5,8 @@
 #include <arpa/inet.h>
 #include <openssl/err.h>
 #include <openssl/ssl.h>
+#include <openssl/x509.h>
+#include <openssl/x509v3.h>
 #include <signal.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -73,6 +75,10 @@ static SSL_CTX* create_ssl_ctx(bool is_server, const char* cert, const char* key
    SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER, NULL);
    SSL_CTX_set_verify_depth(ctx, 4);
  } else {
+    if (!is_server) {
+      log_message(LOG_LEVEL_WARNING,
+                  "No CA path provided — TLS server certificate will not be verified");
+    }
    SSL_CTX_set_verify(ctx, SSL_VERIFY_NONE, NULL);
  }

@@ -86,6 +92,7 @@ static SSL* wrap_fd_with_ssl(int fd, SSL_CTX* ctx, bool is_server) {
    return NULL;
  }
  SSL_set_fd(ssl, fd);
+
  int ret;
  if (is_server)
    ret = SSL_accept(ssl);
@@ -98,6 +105,17 @@ static SSL* wrap_fd_with_ssl(int fd, SSL_CTX* ctx, bool is_server) {
    SSL_free(ssl);
    return NULL;
  }
+
+  // In client mode, check verification result if peer verification was requested
+  if (!is_server) {
+    long verify_result = SSL_get_verify_result(ssl);
+    if (verify_result != X509_V_OK) {
+      log_message(LOG_LEVEL_ERROR, "TLS certificate verification failed: %ld", verify_result);
+      SSL_free(ssl);
+      return NULL;
+    }
+  }
+
  return ssl;
 }

@@ -135,16 +153,9 @@ bool server_listen_tls(Server* server, void (*handler)(int file_descriptor)) {

 bool client_connect_tls(Client* client, char* host, int port, const char* cert_path,
                        const char* key_path, const char* ca_path) {
-  client->address.sin_port = htons(port);
-  if (inet_pton(AF_INET, host, &client->address.sin_addr) <= 0) {
-    perror("Could not convert host address!");
+  // Use the common TCP connection logic (with IPv6 support)
+  if (!client_connect(client, host, port))
    return false;
-  }
-  if (connect(client->file_descriptor, (struct sockaddr*)&client->address, client->address_length) <
-      0) {
-    perror("Could not connect to Server!");
-    return false;
-  }

  SSL_CTX* ctx = create_ssl_ctx(false, cert_path, key_path, ca_path);
  if (!ctx)
@@ -157,6 +168,14 @@ bool client_connect_tls(Client* client, char* host, int port, const char* cert_p
    client->ssl_ctx = NULL;
    return false;
  }
+
+  // Set SNI and enable hostname verification
+  SSL_set_tlsext_host_name(ssl, host);
+  X509_VERIFY_PARAM* param = SSL_get0_param(ssl);
+  if (param) {
+    X509_VERIFY_PARAM_set1_host(param, host, 0);
+  }
+
  client->ssl = ssl;
  io_set_ssl(ssl);
  return true;
@@ -10,19 +10,23 @@
 #include <unistd.h>

 bool mkdir_r(const char* path) {
-  char* path_duplicate = malloc(strlen(path) + 1);
+  size_t path_len = strlen(path);
+  char* path_duplicate = malloc(path_len + 1);
  if (!path_duplicate)
    return false;
-  strcpy(path_duplicate, path);
-  char* path_current = (char*)malloc((strlen(path) + 2) * sizeof(char));
+  memcpy(path_duplicate, path, path_len + 1);
+  /* Buffer for building subpaths: path_len + 1 for leading '/' + 1 for null */
+  size_t buf_size = path_len + 2;
+  char* path_current = (char*)malloc(buf_size);
  if (!path_current) {
    free(path_duplicate);
    return false;
  }
-  char* path_current_position = path_current;
+  size_t pos = 0;
  if (path[0] == '/') {
-    strcpy(path_current, "/");
-    path_current_position += 1;
+    path_current[0] = '/';
+    path_current[1] = '\0';
+    pos = 1;
  } else {
    path_current[0] = '\0';
  }
@@ -31,10 +35,16 @@ bool mkdir_r(const char* path) {
  const char* part = strtok_r(path_duplicate, delimiter, &saveptr);
  bool ok = true;
  while (part != NULL) {
-    strcpy(path_current_position, part);
-    path_current_position += strlen(part) * sizeof(char);
-    strcpy(path_current_position, "/");
-    path_current_position += sizeof(char);
+    size_t part_len = strlen(part);
+    if (pos + part_len + 1 >= buf_size) {
+      ok = false;
+      break;
+    }
+    memcpy(path_current + pos, part, part_len);
+    pos += part_len;
+    path_current[pos] = '/';
+    pos++;
+    path_current[pos] = '\0';
    struct stat st;
    if (stat(path_current, &st) != 0) {
      if (mkdir(path_current, 0755) != 0) {
@@ -49,22 +59,24 @@ bool mkdir_r(const char* path) {
  free(path_current);
  return ok;
 }
-
 char* str_dup(const char* string) {
  if (string == NULL)
    return NULL;
  char* new_string = (char*)malloc(strlen(string) + 1);
-  strcpy(new_string, string);
+  memcpy(new_string, string, strlen(string) + 1);
  return new_string;
 }

 bool glob_match(const char* pattern, const char* str) {
  while (*pattern) {
    if (*pattern == '*') {
+      /* Check for double-star (globstar) pattern */
      if (*(pattern + 1) == '*') {
        pattern += 2;
+        /* Trailing double-star matches everything */
        if (*pattern == '\0')
          return true;
+        /* double-star slash: match at any depth */
        if (*pattern == '/')
          pattern++;
        while (*str) {
@@ -74,6 +86,7 @@ bool glob_match(const char* pattern, const char* str) {
        }
        return glob_match(pattern, str);
      }
+      /* Single * — does not cross / boundaries */
      pattern++;
      while (*str && *str != '/') {
        if (glob_match(pattern, str))
@@ -88,7 +101,9 @@ bool glob_match(const char* pattern, const char* str) {
      str++;
    } else {
      if (*pattern != *str) {
+        /* If pattern has a '/' followed by '**', allow zero path components */
        if (*pattern == '/' && *(pattern + 1) == '*' && *(pattern + 2) == '*') {
+          /* Skip over slash-double-star and try to match rest against current str */
          const char* rest = pattern + 3;
          if (*rest == '/')
            rest++;
@@ -169,37 +184,17 @@ void delete_extras(const char* dest_root, ArrayList* manifest) {
  delete_extras_walk(dest_root, "", manifest);
 }

-bool has_path_traversal(const char* path) {
-  if (!path)
-    return false;
-  char* dup = str_dup(path);
-  if (!dup)
-    return false;
-  char* saveptr;
-  const char* part = strtok_r(dup, "/", &saveptr);
-  while (part) {
-    if (strcmp(part, "..") == 0) {
-      free(dup);
-      return true;
-    }
-    part = strtok_r(NULL, "/", &saveptr);
-  }
-  free(dup);
-  return false;
-}
-
 char* path_cat(const char* path1, const char* path2) {
  if (path1 == NULL || *path1 == '\0')
    return str_dup(path2);
  if (path2 == NULL || *path2 == '\0')
    return str_dup(path1);
-  size_t path1_len = strlen(path1);
-  size_t path2_len = strlen(path2);
-  size_t offset = 0;
+  int path1_len = strlen(path1);
+  int path2_len = strlen(path2);
  if (path1[path1_len - 1] == '/')
    path1_len -= 1;
  if (path2[0] == '/') {
-    offset = 1;
+    path2++;
    path2_len -= 1;
  }
  char* new_path = malloc(path1_len + path2_len + 2);
@@ -207,7 +202,7 @@ char* path_cat(const char* path1, const char* path2) {
    return NULL;
  memcpy(new_path, path1, path1_len);
  new_path[path1_len] = '/';
-  memcpy(new_path + path1_len + 1, path2 + offset, path2_len);
+  memcpy(new_path + path1_len + 1, path2, path2_len);
  new_path[path1_len + path2_len + 1] = '\0';
  return new_path;
 }
@@ -9,6 +9,5 @@ char* str_dup(const char* string);
 char* path_cat(const char* path1, const char* path2);
 bool glob_match(const char* pattern, const char* str);
 void delete_extras(const char* dest_root, ArrayList* manifest);
-bool has_path_traversal(const char* path);

 #endif
@@ -47,12 +47,12 @@ int main() {
  RUN_TEST(test_file_sendfile);
  RUN_TEST(test_multiprocessing);
  RUN_TEST(test_log);
-  RUN_TEST(test_robustness);
-  RUN_TEST(test_stress);
-  RUN_TEST(test_property);
  RUN_TEST(test_transport_tcp);
  RUN_TEST(test_transport_ssh);
  RUN_TEST(test_transport_tls);
+  RUN_TEST(test_robustness);
+  RUN_TEST(test_stress);
+  RUN_TEST(test_property);

  printf("\n\033[1;36m=== TEST SUMMARY ===\033[0m\n");
  printf("Total Tests Run: %d\n", tests_run);
@@ -69,7 +69,7 @@ static void test_file_save_to_disk() {
  memcpy(f->data->data, content, strlen(content));
  f->data->size = strlen(content);

-  EXPECT_TRUE(file_save_to_disk("test_save_tmp", f, NULL));
+  EXPECT_TRUE(file_save_to_disk("test_save_tmp", f));

  struct stat st;
  EXPECT_EQ_INT(stat("test_save_tmp/saved_file.txt", &st), 0);
@@ -217,6 +217,10 @@ static void test_file_send_no_path() {
  pid_t pid = fork();
  if (pid == 0) {
    close(p[1]);
+    // Read file type indicator
+    int file_type;
+    EXPECT_TRUE(receive_int(p[0], &file_type));
+    EXPECT_EQ_INT(file_type, (int)FILE_TYPE_REGULAR);
    Data* received = receive_data(p[0]);
    close(p[0]);

@@ -224,6 +224,10 @@ static void test_sendfile_no_path() {
  pid_t pid = fork();
  if (pid == 0) {
    close(p[1]);
+    /* When send_path is false, the sender still sends file_type + data */
+    int file_type;
+    EXPECT_TRUE(receive_int(p[0], &file_type));
+    EXPECT_EQ_INT(file_type, (int)FILE_TYPE_REGULAR);
    Data* received = receive_data(p[0]);
    close(p[0]);

@@ -46,6 +46,7 @@ static void test_send_receive_str() {

  EXPECT_TRUE(send_str(0, ""));

+  /* cppcheck-suppress constVariablePointer */
  char* received = receive_str(0);
  EXPECT_NOT_NULL(received);
  EXPECT_EQ_STR(received, "");
@@ -63,6 +64,7 @@ static void test_send_receive_str_normal() {

  EXPECT_TRUE(send_str(0, "Hello, Protocol!"));

+  /* cppcheck-suppress constVariablePointer */
  char* received = receive_str(0);
  EXPECT_NOT_NULL(received);
  EXPECT_EQ_STR(received, "Hello, Protocol!");
@@ -78,6 +80,7 @@ static void test_send_receive_data() {
  io_set_fds(p[0], p[1]);
  io_set_bwlimit(0);

+  /* cppcheck-suppress constVariablePointer */
  unsigned char bin[] = {0xDE, 0xAD, 0xBE, 0xEF, 0x00, 0xFF};
  void* buf = malloc(sizeof(bin));
  EXPECT_NOT_NULL(buf);
@@ -128,9 +131,9 @@ static void test_send_receive_status() {
  io_set_fds(p[0], p[1]);
  io_set_bwlimit(0);

-  Status statuses[] = {STATUS_OK,        STATUS_ERROR, STATUS_FINISHED,        STATUS_NEXT,
-                       STATUS_CHUNK,     STATUS_CHECK, STATUS_DELTA_SIGNATURE, STATUS_DELTA_DATA,
-                       STATUS_KEEPALIVE, STATUS_ABORT, STATUS_CHECK_BATCH};
+  /* cppcheck-suppress constVariablePointer */
+  Status statuses[] = {STATUS_OK,    STATUS_ERROR, STATUS_FINISHED,        STATUS_NEXT,
+                       STATUS_CHUNK, STATUS_CHECK, STATUS_DELTA_SIGNATURE, STATUS_DELTA_DATA};
  int count = sizeof(statuses) / sizeof(statuses[0]);

  for (int i = 0; i < count; i++) {
@@ -170,6 +173,23 @@ static void test_receive_str_truncated() {
  close(p[0]);
 }

+static void test_receive_str_oversized() {
+  int p[2];
+  EXPECT_EQ_INT(pipe(p), 0);
+  io_set_fds(p[0], p[1]);
+  io_set_bwlimit(0);
+
+  /* Send a size exceeding MAX_STRING_SIZE */
+  size_t huge = MAX_STRING_SIZE + 1;
+  EXPECT_TRUE(send_n_data(0, &huge, sizeof(size_t)));
+
+  const char* received = receive_str(0);
+  EXPECT_NULL(received);
+
+  close(p[0]);
+  close(p[1]);
+}
+
 void test_protocol() {
  test_send_receive_n_data();
  test_send_receive_n_data_zero();
@@ -180,4 +200,5 @@ void test_protocol() {
  test_send_receive_status();
  test_receive_n_data_truncated();
  test_receive_str_truncated();
+  test_receive_str_oversized();
 }
@@ -19,7 +19,7 @@ static void test_scanner_single_file() {
  create_test_file(file1, content1);

  DirectoryScanner* scanner =
-      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 0, 0);
+      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 0);
  EXPECT_NOT_NULL(scanner);

  Chunk* chunk = directory_scanner_next(scanner);
@@ -48,7 +48,7 @@ static void test_scanner_multiple_files() {
  create_test_file(file2, content2);

  DirectoryScanner* scanner =
-      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 0, 0);
+      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 0);
  EXPECT_NOT_NULL(scanner);

  const Chunk* chunk = directory_scanner_next(scanner);
@@ -88,7 +88,7 @@ static void test_scanner_subdirectory() {
  create_test_file(sub_file, content);

  DirectoryScanner* scanner =
-      directory_scanner_create((char*)root, false, 0, NULL, 0, NULL, 0, 0, 0, 0);
+      directory_scanner_create((char*)root, false, 0, NULL, 0, NULL, 0, 0, 0);
  EXPECT_NOT_NULL(scanner);

  int total_files = 0;
@@ -112,7 +112,7 @@ static void test_scanner_empty_directory() {
  EXPECT_EQ_INT(mkdir(dir, 0755), 0);

  DirectoryScanner* scanner =
-      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 0, 0);
+      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 0);
  EXPECT_NOT_NULL(scanner);

  const Chunk* chunk = directory_scanner_next(scanner);
@@ -136,7 +136,7 @@ static void test_scanner_exclude_pattern() {

  char* exclude[] = {"*.tmp"};
  DirectoryScanner* scanner =
-      directory_scanner_create((char*)dir, false, 0, exclude, 1, NULL, 0, 0, 0, 0);
+      directory_scanner_create((char*)dir, false, 0, exclude, 1, NULL, 0, 0, 0);
  EXPECT_NOT_NULL(scanner);

  Chunk* chunk = directory_scanner_next(scanner);
@@ -169,7 +169,7 @@ static void test_scanner_exclude_subdirectory() {

  char* exclude[] = {"*.tmp"};
  DirectoryScanner* scanner =
-      directory_scanner_create((char*)root, false, 0, exclude, 1, NULL, 0, 0, 0, 0);
+      directory_scanner_create((char*)root, false, 0, exclude, 1, NULL, 0, 0, 0);
  EXPECT_NOT_NULL(scanner);

  int total = 0;
@@ -207,7 +207,7 @@ static void test_scanner_include_and_exclude() {
  char* exclude[] = {"*.bak"};
  char* include[] = {"*.txt", "*.log"};
  DirectoryScanner* scanner =
-      directory_scanner_create((char*)dir, false, 0, exclude, 1, include, 2, 0, 0, 0);
+      directory_scanner_create((char*)dir, false, 0, exclude, 1, include, 2, 0, 0);
  EXPECT_NOT_NULL(scanner);

  Chunk* chunk = directory_scanner_next(scanner);
@@ -244,7 +244,7 @@ static void test_scanner_max_size() {

  /* max_size = 10 — only files <= 10 bytes */
  DirectoryScanner* scanner =
-      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 10, 0, 0);
+      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 10, 0);
  EXPECT_NOT_NULL(scanner);

  Chunk* chunk = directory_scanner_next(scanner);
@@ -272,7 +272,7 @@ static void test_scanner_min_size() {

  /* min_size = 1 — only files >= 1 byte */
  DirectoryScanner* scanner =
-      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 1, 0);
+      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 1);
  EXPECT_NOT_NULL(scanner);

  Chunk* chunk = directory_scanner_next(scanner);
@@ -302,7 +302,7 @@ static void test_scanner_size_range() {

  /* Only files between 3 and 20 bytes */
  DirectoryScanner* scanner =
-      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 20, 3, 0);
+      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 20, 3);
  EXPECT_NOT_NULL(scanner);

  Chunk* chunk = directory_scanner_next(scanner);
@@ -338,7 +338,7 @@ static void test_scanner_mixed_patterns() {
  char* exclude[] = {"*.bak"};
  char* include[] = {"*.txt"};
  DirectoryScanner* scanner =
-      directory_scanner_create((char*)dir, false, 0, exclude, 1, include, 1, 10, 3, 0);
+      directory_scanner_create((char*)dir, false, 0, exclude, 1, include, 1, 10, 3);
  EXPECT_NOT_NULL(scanner);

  Chunk* chunk = directory_scanner_next(scanner);
@@ -369,7 +369,7 @@ static void test_scanner_no_patterns() {
  create_test_file(f2, "second");

  DirectoryScanner* scanner =
-      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 0, 0);
+      directory_scanner_create((char*)dir, false, 0, NULL, 0, NULL, 0, 0, 0);
  EXPECT_NOT_NULL(scanner);

  Chunk* chunk = directory_scanner_next(scanner);
@@ -1,14 +1,20 @@
 #include "test_transport_ssh.h"
-#include "test_utils.h"
 #include "transport_ssh.h"
+#include "test_utils.h"
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/wait.h>

-static void test_ssh_connect_invalid_dest_no_colon() {
+/* Test client_connect_ssh with invalid destination (missing colon) */
+static void test_ssh_connect_invalid_dest() {
+  /* Missing colon — parse_remote_dest should fail and return NULL */
  /* cppcheck-suppress constVariablePointer */
  Client* client = client_connect_ssh("invalid-destination-no-colon", 22, NULL);
  EXPECT_NULL(client);
 }

-static void test_ssh_connect_invalid_dest_empty() {
+/* Test client_connect_ssh with empty destination */
+static void test_ssh_connect_empty_dest() {
  /* cppcheck-suppress constVariablePointer */
  Client* client = client_connect_ssh("", 22, NULL);
  EXPECT_NULL(client);
@@ -40,6 +46,8 @@ static void test_ssh_connect_unreachable() {
 }

 void test_transport_ssh() {
-  test_ssh_connect_invalid_dest_no_colon();
-  test_ssh_connect_invalid_dest_empty();
+  test_ssh_connect_invalid_dest();
+  test_ssh_connect_empty_dest();
+  test_ssh_connect_malformed();
+  test_ssh_connect_unreachable();
 }
@@ -1,43 +1,89 @@
 #include "test_transport_tcp.h"
-#include "test_utils.h"
 #include "transport_tcp.h"
+#include "test_utils.h"
+#include <stdlib.h>
 #include <unistd.h>

-static void test_server_create_ephemeral() {
-  Server* s = server_create(0);
-  EXPECT_NOT_NULL(s);
-  EXPECT_TRUE(s->file_descriptor >= 0);
-  EXPECT_EQ_INT(s->address.sin_family, AF_INET);
-  server_delete(&s);
-  EXPECT_NULL(s);
+/* Test client_create and client_delete lifecycle */
+static void test_client_create_delete() {
+  Client* client = client_create();
+  EXPECT_NOT_NULL(client);
+  EXPECT_EQ_INT(client->file_descriptor, -1);
+  EXPECT_EQ_INT(client->address.ss_family, AF_UNSPEC);
+  EXPECT_EQ_INT(client->ssh_child_pid, -1);
+  EXPECT_NULL(client->ssl);
+  EXPECT_NULL(client->ssl_ctx);
+
+  /* Delete should clean up without error */
+  client_delete(client);
 }

-static void test_server_delete_null() {
+/* Test client_delete with NULL (safety) */
+static void test_client_delete_null() {
+  client_delete(NULL);
+  EXPECT_TRUE(true);
+}
+
+/* Test server_create and server_delete lifecycle */
+static void test_server_create_delete() {
+  /* Use port 0 to let the OS assign a port */
+  Server* server = server_create(0);
+  EXPECT_NOT_NULL(server);
+  EXPECT_TRUE(server->file_descriptor >= 0);
+  EXPECT_TRUE(server->address.ss_family == AF_INET || server->address.ss_family == AF_INET6);
+  EXPECT_NULL(server->ssl_ctx);
+
+  /* Clean up */
+  server_delete(&server);
+  EXPECT_NULL(server);
+}
+
+/* Test server_delete with NULL pointer */
+static void test_server_delete_null_ptr() {
+  server_delete(NULL);
+  EXPECT_TRUE(true);
+}
+
+/* Test server_delete with NULL server */
+static void test_server_delete_null_server() {
  Server* s = NULL;
  server_delete(&s);
  EXPECT_NULL(s);
 }

-static void test_client_create() {
-  Client* c = client_create();
-  EXPECT_NOT_NULL(c);
-  EXPECT_TRUE(c->file_descriptor >= 0);
-  EXPECT_EQ_INT(c->address.sin_family, AF_INET);
-  EXPECT_EQ_INT(c->ssh_child_pid, -1);
-  EXPECT_NULL(c->ssl);
-  EXPECT_NULL(c->ssl_ctx);
-  client_disconnect(c);
-  client_delete(c);
+/* Test client_create can be called multiple times */
+static void test_client_create_multiple() {
+  Client* c1 = client_create();
+  Client* c2 = client_create();
+  EXPECT_NOT_NULL(c1);
+  EXPECT_NOT_NULL(c2);
+  EXPECT_EQ_INT(c1->file_descriptor, -1);
+  EXPECT_EQ_INT(c2->file_descriptor, -1);
+
+  client_delete(c1);
+  client_delete(c2);
 }

-static void test_client_delete_null() {
-  Client* c = NULL;
-  client_delete(c);
+/* Test client_disconnect on a fresh client (should close socket) */
+static void test_client_disconnect_fresh() {
+  Client* client = client_create();
+  EXPECT_NOT_NULL(client);
+
+  /* Disconnect should close the file descriptor */
+  client_disconnect(client);
+  /* The fd should now be invalid */
+  /* Verify by trying to use close() on it - should fail */
+  EXPECT_EQ_INT(close(client->file_descriptor), -1);
+
+  client_delete(client);
 }

 void test_transport_tcp() {
-  test_server_create_ephemeral();
-  test_server_delete_null();
-  test_client_create();
+  test_client_create_delete();
  test_client_delete_null();
+  test_server_create_delete();
+  test_server_delete_null_ptr();
+  test_server_delete_null_server();
+  test_client_create_multiple();
+  test_client_disconnect_fresh();
 }
@@ -1,24 +1,81 @@
 #include "test_transport_tls.h"
-#include "test_utils.h"
-#include "transport_tcp.h"
 #include "transport_tls.h"
+#include "transport_tcp.h"
+#include "test_utils.h"
+#include <stdlib.h>
+#include <unistd.h>

+/* Test tls_global_init succeeds */
 static void test_tls_global_init() {
  bool ok = tls_global_init();
  EXPECT_TRUE(ok);
 }

-static void test_server_create_tls_without_certs() {
-  Server* s = server_create(0);
-  EXPECT_NOT_NULL(s);
-  bool ok = server_create_tls(s, NULL, NULL, NULL);
-  EXPECT_TRUE(ok);
-  EXPECT_NOT_NULL(s->ssl_ctx);
-  server_delete(&s);
-  EXPECT_NULL(s);
+/* Test tls_global_init can be called multiple times */
+static void test_tls_global_init_twice() {
+  bool ok1 = tls_global_init();
+  bool ok2 = tls_global_init();
+  EXPECT_TRUE(ok1);
+  EXPECT_TRUE(ok2);
+}
+
+/* Test client_connect_tls with bad certificate path.
+ * The function will create a socket, try to connect to localhost,
+ * fail to connect (since nothing is listening), and return false.
+ * We don't need a server to verify the error path. */
+static void test_tls_connect_bad_cert() {
+  /* First, init TLS globally */
+  tls_global_init();
+
+  Client* client = client_create();
+  EXPECT_NOT_NULL(client);
+
+  /* Attempt to connect to a non-existent server with bad cert paths.
+   * client_connect_tls will try to connect first, fail, and return false.
+   * Note: we use an invalid host to ensure connection failure,
+   * which exercises the error path before cert loading. */
+  bool ok = client_connect_tls(client, "127.0.0.1", 1, "/nonexistent/cert.pem",
+                               "/nonexistent/key.pem", "/nonexistent/ca.pem");
+  EXPECT_FALSE(ok);
+
+  client_delete(client);
+}
+
+/* Test client_connect_tls with NULL cert paths (should still attempt connection).
+ * Cert/key/ca being NULL is valid — the function will attempt to create an
+ * SSL context without client certificates. */
+static void test_tls_connect_null_paths() {
+  tls_global_init();
+
+  Client* client = client_create();
+  EXPECT_NOT_NULL(client);
+
+  /* Connect to invalid address — will fail at connect() step */
+  bool ok = client_connect_tls(client, "127.0.0.1", 1, NULL, NULL, NULL);
+  EXPECT_FALSE(ok);
+
+  client_delete(client);
+}
+
+/* Test server_create_tls with bad cert paths.
+ * The function should fail gracefully. */
+static void test_tls_server_bad_cert() {
+  tls_global_init();
+
+  Server* server = server_create(0);
+  EXPECT_NOT_NULL(server);
+
+  /* Load bad cert paths — should fail and return false */
+  bool ok = server_create_tls(server, "/nonexistent/cert.pem", "/nonexistent/key.pem", NULL);
+  EXPECT_FALSE(ok);
+
+  server_delete(&server);
 }

 void test_transport_tls() {
  test_tls_global_init();
-  test_server_create_tls_without_certs();
+  test_tls_global_init_twice();
+  test_tls_connect_bad_cert();
+  test_tls_connect_null_paths();
+  test_tls_server_bad_cert();
 }