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extmod/modlwip: Keep TCP data on remote RST.

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This commit fixes a long standing bug/deficiency in the lwIP socket code,
whereby it would abandon all incoming TCP data if the remote sent a TCP
RST.

This behaviour it tested by the existing
`tests/multi_net/tcp_client_rst.py` and
`tests/multi_net/asyncio_tcp_client_rst.py` tests, and they both fail on
boards like PYBD_SFx and RPI_PICO_W due to the deficiency.

With the fix here, both of those tests now pass on lwIP targets, along with
all existing socket tests.

Signed-off-by: Damien George <damien@micropython.org>
This commit is contained in:
Damien George
2025-08-20 00:45:10 +10:00
parent c696ca91e0
commit a7cd41847d
1 changed files with 36 additions and 20 deletions
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56
extmod/modlwip.c
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@@ -348,8 +348,9 @@ typedef struct _lwip_socket_obj_t {
#define STATE_LISTENING 1
#define STATE_CONNECTING 2
#define STATE_CONNECTED 3
#define STATE_PEER_CLOSED 4
#define STATE_ACTIVE_UDP 5
#define STATE_ACTIVE_UDP 4
#define STATE_PEER_CLOSED 5 // Values higher than this must also be closed by peer
#define STATE_PEER_RST_HANDLED 6
// Negative value is lwIP error
int8_t state;
} lwip_socket_obj_t;
@@ -370,10 +371,10 @@ static struct tcp_pcb *volatile *lwip_socket_incoming_array(lwip_socket_obj_t *s
}
}
static void lwip_socket_free_incoming(lwip_socket_obj_t *socket) {
static void lwip_socket_free_incoming(lwip_socket_obj_t *socket, bool free_queued_stream_data) {
if (socket->state != STATE_LISTENING) {
if (socket->type == MOD_NETWORK_SOCK_STREAM) {
if (socket->incoming.tcp.pbuf != NULL) {
if (free_queued_stream_data && socket->incoming.tcp.pbuf != NULL) {
pbuf_free(socket->incoming.tcp.pbuf);
socket->incoming.tcp.pbuf = NULL;
}
@@ -399,6 +400,8 @@ static void lwip_socket_free_incoming(lwip_socket_obj_t *socket) {
tcp_array[i] = NULL;
}
}
// This socket is now a non-listening stream, so clear the relevant state.
socket->incoming.tcp.pbuf = NULL;
}
}
@@ -487,8 +490,9 @@ static void _lwip_udp_incoming(void *arg, struct udp_pcb *upcb, struct pbuf *p,
static void _lwip_tcp_error(void *arg, err_t err) {
lwip_socket_obj_t *socket = (lwip_socket_obj_t *)arg;
// Free any incoming buffers or connections that are stored
lwip_socket_free_incoming(socket);
// Free any incoming buffers or connections that are stored, but keep potential
// queued TCP data in case it's read later. Will be freed by MP_STREAM_CLOSE.
lwip_socket_free_incoming(socket, false);
// Pass the error code back via the connection variable.
socket->state = err;
// If we got here, the lwIP stack either has deallocated or will deallocate the pcb.
@@ -818,9 +822,6 @@ static mp_uint_t lwip_tcp_send(lwip_socket_obj_t *socket, const byte *buf, mp_ui
// Helper function for recv/recvfrom to handle TCP packets
static mp_uint_t lwip_tcp_receive(lwip_socket_obj_t *socket, byte *buf, mp_uint_t len, mp_int_t flags, int *_errno) {
// Check for any pending errors
STREAM_ERROR_CHECK(socket);
if (socket->state == STATE_LISTENING) {
// original socket in listening state, not the accepted connection.
*_errno = MP_ENOTCONN;
@@ -828,10 +829,20 @@ static mp_uint_t lwip_tcp_receive(lwip_socket_obj_t *socket, byte *buf, mp_uint_
}
if (socket->incoming.tcp.pbuf == NULL) {
// Check for any pending errors that should propagate out on socket read.
if (socket->state < 0) {
*_errno = error_lookup_table[-socket->state];
if (*_errno == MP_ECONNRESET) {
socket->state = STATE_PEER_RST_HANDLED;
} else {
socket->state = _ERR_BADF;
}
return MP_STREAM_ERROR;
}
// Non-blocking socket or flag
if (socket->timeout == 0 || (flags & MSG_DONTWAIT)) {
if (socket->state == STATE_PEER_CLOSED) {
if (socket->state >= STATE_PEER_CLOSED) {
return 0;
}
*_errno = MP_EAGAIN;
@@ -847,7 +858,7 @@ static mp_uint_t lwip_tcp_receive(lwip_socket_obj_t *socket, byte *buf, mp_uint_
poll_sockets();
}
if (socket->state == STATE_PEER_CLOSED) {
if (socket->state >= STATE_PEER_CLOSED) {
if (socket->incoming.tcp.pbuf == NULL) {
// socket closed and no data left in buffer
return 0;
@@ -864,8 +875,6 @@ static mp_uint_t lwip_tcp_receive(lwip_socket_obj_t *socket, byte *buf, mp_uint_
MICROPY_PY_LWIP_ENTER
assert(socket->pcb.tcp != NULL);
struct pbuf *p = socket->incoming.tcp.pbuf;
mp_uint_t remaining = p->len - socket->recv_offset;
@@ -888,7 +897,9 @@ static mp_uint_t lwip_tcp_receive(lwip_socket_obj_t *socket, byte *buf, mp_uint_
} else {
socket->recv_offset += len;
}
tcp_recved(socket->pcb.tcp, len);
if (socket->pcb.tcp != NULL) {
tcp_recved(socket->pcb.tcp, len);
}
}
MICROPY_PY_LWIP_EXIT
@@ -1292,8 +1303,6 @@ static mp_obj_t lwip_socket_recv_common(size_t n_args, const mp_obj_t *args, ip_
vstr_t vstr;
mp_uint_t ret = 0;
lwip_socket_check_connected(socket);
vstr_init_len(&vstr, len);
switch (socket->type) {
@@ -1308,6 +1317,7 @@ static mp_obj_t lwip_socket_recv_common(size_t n_args, const mp_obj_t *args, ip_
#if MICROPY_PY_LWIP_SOCK_RAW
case MOD_NETWORK_SOCK_RAW:
#endif
lwip_socket_check_connected(socket);
ret = lwip_raw_udp_receive(socket, (byte *)vstr.buf, len, flags, ip, port, &_errno);
break;
}
@@ -1580,7 +1590,10 @@ static mp_uint_t lwip_socket_ioctl(mp_obj_t self_in, mp_uint_t request, uintptr_
}
} else if (socket->type == MOD_NETWORK_SOCK_STREAM) {
// For TCP sockets there is just one slot for incoming data
if (socket->incoming.tcp.pbuf != NULL) {
// The socket is also readable when in RST state
if (socket->incoming.tcp.pbuf != NULL
|| socket->state == ERR_RST
|| socket->state == STATE_PEER_RST_HANDLED) {
ret |= MP_STREAM_POLL_RD;
}
} else {
@@ -1619,6 +1632,8 @@ static mp_uint_t lwip_socket_ioctl(mp_obj_t self_in, mp_uint_t request, uintptr_
} else if (socket->state == ERR_RST) {
// Socket was reset by peer, a write will return an error
ret |= flags & MP_STREAM_POLL_WR;
ret |= MP_STREAM_POLL_ERR | MP_STREAM_POLL_HUP;
} else if (socket->state == STATE_PEER_RST_HANDLED) {
ret |= MP_STREAM_POLL_HUP;
} else if (socket->state == _ERR_BADF) {
ret |= MP_STREAM_POLL_NVAL;
@@ -1629,14 +1644,15 @@ static mp_uint_t lwip_socket_ioctl(mp_obj_t self_in, mp_uint_t request, uintptr_
}
} else if (request == MP_STREAM_CLOSE) {
// Free any incoming buffers or connections that are stored
lwip_socket_free_incoming(socket, true);
if (socket->pcb.tcp == NULL) {
socket->state = _ERR_BADF;
MICROPY_PY_LWIP_EXIT
return 0;
}
// Free any incoming buffers or connections that are stored
lwip_socket_free_incoming(socket);
switch (socket->type) {
case MOD_NETWORK_SOCK_STREAM: {
// Deregister callback (pcb.tcp is set to NULL below so must deregister now)