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Do not un-throttle TCP connections on isc_nm_read()

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Due to omission it was possible to un-throttle a TCP connection
previously throttled due to the peer not reading back data we are
sending.

In particular, that affected DoH code, but it could also affect other
transports (the current or future ones) that pause/resume reading
according to its internal state.
This commit is contained in:
Artem Boldariev 2024-06-11 17:20:22 +03:00
parent f149ecc81a
commit 55b1a093ea
No known key found for this signature in database
GPG Key ID: 40B68E70AFB04AC4
2 changed files with 18 additions and 3 deletions
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6
lib/isc/netmgr/netmgr-int.h
View File

@ -585,6 +585,12 @@ struct isc_nmsocket {
*/ */
uint64_t write_timeout; uint64_t write_timeout;
/*
* Reading was throttled over TCP as the peer does not read the
* data we are sending back.
*/
bool reading_throttled;
/*% outer socket is for 'wrapped' sockets - e.g. tcpdns in tcp */ /*% outer socket is for 'wrapped' sockets - e.g. tcpdns in tcp */
isc_nmsocket_t *outer; isc_nmsocket_t *outer;

15
lib/isc/netmgr/tcp.c
View File

@ -697,9 +697,11 @@ isc__nm_tcp_read(isc_nmhandle_t *handle, isc_nm_recv_cb_t cb, void *cbarg) {
goto failure; goto failure;
} }
result = isc__nm_start_reading(sock); if (!sock->reading_throttled) {
if (result != ISC_R_SUCCESS) { result = isc__nm_start_reading(sock);
goto failure; if (result != ISC_R_SUCCESS) {
goto failure;
}
} }
sock->reading = true; sock->reading = true;
@ -791,6 +793,7 @@ isc__nm_tcp_read_cb(uv_stream_t *stream, ssize_t nread, const uv_buf_t *buf) {
"throttling TCP connection, the other side is " "throttling TCP connection, the other side is "
"not reading the data (%zu)", "not reading the data (%zu)",
write_queue_size); write_queue_size);
sock->reading_throttled = true;
isc__nm_stop_reading(sock); isc__nm_stop_reading(sock);
} }
} else if (uv_is_active(&sock->uv_handle.handle) && } else if (uv_is_active(&sock->uv_handle.handle) &&
@ -1042,6 +1045,7 @@ tcp_maybe_restart_reading(isc_nmsocket_t *sock) {
"is reading the data again (%zu)", "is reading the data again (%zu)",
write_queue_size); write_queue_size);
isc__nm_start_reading(sock); isc__nm_start_reading(sock);
sock->reading_throttled = false;
} }
} }
} }
@ -1064,6 +1068,11 @@ tcp_send_cb(uv_write_t *req, int status) {
isc__nm_failed_send_cb(sock, uvreq, isc_uverr2result(status), isc__nm_failed_send_cb(sock, uvreq, isc_uverr2result(status),
false); false);
if (!sock->client && sock->reading) { if (!sock->client && sock->reading) {
/*
* As we are resuming reading, it is not throttled
* anymore (technically).
*/
sock->reading_throttled = false;
isc__nm_start_reading(sock); isc__nm_start_reading(sock);
isc__nmsocket_reset(sock); isc__nmsocket_reset(sock);
} }