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protocol: add transport I/O vtable over TCP/TLS primitives

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Introduce ProtocolIoOps (send/recv/has_pending), selected once by
protocol_session_init() and protocol_session_set_ssl(), and dispatch the
send, receive and status-read loops through session->ops instead of
branching on session->ssl at runtime.

Each op performs one transfer attempt and classifies the result
(PROTOCOL_IO_RETRY/CLOSED/ERROR), preserving the WANT_READ/WANT_WRITE
wait_events switching, the SSL_ERROR_SYSCALL/EINTR retry, the
SSL_pending poll gating and the deadline handling. The raw read()/write()
fallback lives in the plaintext ops.

Add unit tests: a socketpair session with a counting ops wrapper proving
the loops dispatch through the vtable, and a worker-thread test that
protocol_current_ssl() resolves the bound session's SSL when io_ssl is NULL.
This commit is contained in:
TapTap
2026-09-23 00:18:36 +02:00
parent 1f8d60e30d
commit ec6692ac41
3 changed files with 314 additions and 79 deletions
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src/shared/protocol.h
+34 -2
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@@ -50,16 +50,48 @@
typedef struct ssl_st SSL;
typedef struct ProtocolSession ProtocolSession;
/*
* Transport vtable: the per-session set of I/O primitives the three protocol
* loops (send, receive, status-read) dispatch through. The ops are selected
* once, when the session is initialized or its SSL is installed, so the loops
* never branch on the transport at runtime. A plaintext session uses the
* read()/write() ops; a TLS session uses the SSL_read()/SSL_write() ops.
*
* `send`/`recv` attempt exactly one transfer and return:
* > 0 bytes transferred,
* PROTOCOL_IO_RETRY no progress; poll on *wait_events and retry,
* PROTOCOL_IO_CLOSED peer closed the stream,
* PROTOCOL_IO_ERROR fatal transport error.
* `has_pending` reports bytes already buffered by the transport (a TLS record
* residue); the receive loops skip the poll() gate when it is true.
*/
typedef struct ProtocolIoOps {
ssize_t (*send)(ProtocolSession* session, const void* data, size_t size, short* wait_events);
ssize_t (*recv)(ProtocolSession* session, void* data, size_t size, short* wait_events);
bool (*has_pending)(const ProtocolSession* session);
} ProtocolIoOps;
/* Negative sentinels returned by ProtocolIoOps.send/recv (see above). */
enum {
PROTOCOL_IO_RETRY = -1,
PROTOCOL_IO_CLOSED = -2,
PROTOCOL_IO_ERROR = -3,
};
/*
* Explicit owner of protocol I/O. A session does not own the descriptors or
* SSL object; it only describes the transport used by a transfer. This makes
* it safe to pass the transport to a worker without relying on inherited
* thread-local state.
*/
typedef struct ProtocolSession {
struct ProtocolSession {
int read_fd;
int write_fd;
SSL* ssl;
/* Transport dispatch selected by protocol_session_init()/set_ssl(). */
const ProtocolIoOps* ops;
unsigned long long bwlimit;
long long bw_tokens;
long long bw_last_refill_sec;
@@ -75,7 +107,7 @@ typedef struct ProtocolSession {
* SO_RCVTIMEO/SO_SNDTIMEO. The server does not propagate a client 0 here: it
* installs protocol_server_io_timeout_sec() so its sessions keep a floor. */
int io_timeout_sec;
} ProtocolSession;
};
typedef int Status;
enum NET_STATUS {