File SolidSyslogLwipRawTcpStream.h¶

FileList > Interface > SolidSyslogLwipRawTcpStream.h

A TCP stream over the lwIP Raw API, for a StreamSender or as the byte transport under a TlsStream / MbedTlsStream. More...

#include "ExternC.h"
#include "SolidSyslogSleep.h"
#include "SolidSyslogTcpConnectTimeoutFunction.h"

Classes¶

Type	Name
struct	SolidSyslogLwipRawTcpStreamConfig Tunes SolidSyslogLwipRawTcpStream's bounded connect.

Public Functions¶

Type	Name
struct SolidSyslogStream *	SolidSyslogLwipRawTcpStream_Create (const struct SolidSyslogLwipRawTcpStreamConfig * config) Draw a TCP stream from the pool; the config's Sleep drives the bounded connect and its GetConnectTimeoutMs bounds it (see the file overview for the stream's behaviour).
void	SolidSyslogLwipRawTcpStream_Destroy (struct SolidSyslogStream * base) Release the pool slot and close the connection.

Detailed Description¶

Every lwIP call runs under the SolidSyslogLwipRaw_Marshal hop; the callbacks lwIP fires back (connected / recv / err) only flip flags, so they stay unmarshalled. What the stream does through its vtable is the substance:

Open runs tcp_new + pcb setup + tcp_connect in one marshalled batch, then spins on the caller's thread — sleeping via the config's Sleep so lwIP's timer / RX paths advance the SYN exchange — until the connected callback reports success, an error, or the connect deadline (config's GetConnectTimeoutMs, re-read each attempt so a runtime-tunable value applies on the next reconnect) elapses. On failure the half-open pcb is tcp_abort'd. Every pcb carries SOF_KEEPALIVE, and Nagle is off (TCP_NODELAY) so a small latency-sensitive record — or a stacked TLS handshake flight — is not held for an ACK.
Send is all-or-nothing: tcp_write uses TCP_WRITE_FLAG_COPY, so the caller's buffer lifetime ends at return; any write/output failure closes the stream for the sender to reconnect. A peer FIN marks the stream unwritable while still readable, so buffered bytes drain before the close.
Read drains the bounded RX pbuf queue (size SOLIDSYSLOG_LWIP_RAW_TCP_RX_QUEUE_SIZE; a full queue backpressures lwIP, which replays the pbuf later), returning bytes copied, 0 for would-block, or < 0 once a drained peer FIN closes the stream internally.

It encapsulates lwIP's tcp_close-after-tcp_err use-after-free rule: the err callback nulls the pcb pointer, and Close only calls tcp_close when the pointer is still live, so a released pcb is never closed twice. Accepted pbufs are always freed on close regardless of pcb state. See docs/integrating-lwip.md for the full integrator guide.

Public Functions Documentation¶

function SolidSyslogLwipRawTcpStream_Create¶

Draw a TCP stream from the pool; the config's Sleep drives the bounded connect and its GetConnectTimeoutMs bounds it (see the file overview for the stream's behaviour).

struct SolidSyslogStream * SolidSyslogLwipRawTcpStream_Create (
    const struct SolidSyslogLwipRawTcpStreamConfig * config
)

A NULL config, a NULL Sleep, or an exhausted pool (default size 2, for the TLS-over-plain-TCP pair) falls back to the shared NullStream.

function SolidSyslogLwipRawTcpStream_Destroy¶

Release the pool slot and close the connection.

void SolidSyslogLwipRawTcpStream_Destroy (
    struct SolidSyslogStream * base
)

The documentation for this class was generated from the following file Platform/LwipRaw/Interface/SolidSyslogLwipRawTcpStream.h