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TCP/TLS DNS: unthrottle only when all input data processing

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This commit ensures that we restart reading only when all DNS data in
the input buffer is processed so the we will not get into the
situation when the buffer is overrun.
This commit is contained in:
Artem Boldariev 2024-07-03 13:58:32 +03:00 committed by Ondřej Surý
parent e31190e704
commit c33b3d26f6
No known key found for this signature in database
GPG key ID: 2820F37E873DEA41
3 changed files with 40 additions and 42 deletions
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36
lib/isc/netmgr/netmgr.c
View file

@ -2369,14 +2369,41 @@ isc__nm_process_sock_buffer(isc_nmsocket_t *sock) {
int_fast32_t ah = atomic_load(&sock->ah);
isc_result_t result = processbuffer(sock);
switch (result) {
case ISC_R_NOMORE:
case ISC_R_NOMORE: {
/*
* Don't reset the timer until we have a
* full DNS message.
*/
result = isc__nm_start_reading(sock);
if (result != ISC_R_SUCCESS) {
return (result);
/*
* Restart reading if we have less data in the send
* queue than the send buffer size, this means that the
* TCP client has started reading some data again.
* Starting reading when we go under the limit instead
* of waiting for all data has been flushed allows
* faster recovery (in case there was a congestion and
* now there isn't).
*/
size_t write_queue_size =
uv_stream_get_write_queue_size(
&sock->uv_handle.stream);
if (write_queue_size < ISC_NETMGR_TCP_SENDBUF_SIZE) {
if (sock->reading_throttled) {
isc_log_write(isc_lctx,
ISC_LOGCATEGORY_GENERAL,
ISC_LOGMODULE_NETMGR,
ISC_LOG_DEBUG(3),
"resuming TCP "
"connection, the other "
"side is reading the "
"data again (%zu)",
write_queue_size);
sock->reading_throttled = false;
}
result = isc__nm_start_reading(sock);
if (result != ISC_R_SUCCESS) {
return (result);
}
}
/*
* Start the timer only if there are no externally used
@ -2388,6 +2415,7 @@ isc__nm_process_sock_buffer(isc_nmsocket_t *sock) {
isc__nmsocket_timer_start(sock);
}
goto done;
}
case ISC_R_CANCELED:
isc__nmsocket_timer_stop(sock);
isc__nm_stop_reading(sock);

23
lib/isc/netmgr/tcpdns.c
View file

@ -1162,25 +1162,10 @@ tcpdns_maybe_restart_reading(isc_nmsocket_t *sock) {
if (!sock->client && sock->reading_throttled &&
!uv_is_active(&sock->uv_handle.handle))
{
/*
* Restart reading if we have less data in the send queue than
* the send buffer size, this means that the TCP client has
* started reading some data again. Starting reading when we go
* under the limit instead of waiting for all data has been
* flushed allows faster recovery (in case there was a
* congestion and now there isn't).
*/
size_t write_queue_size =
uv_stream_get_write_queue_size(&sock->uv_handle.stream);
if (write_queue_size < ISC_NETMGR_TCP_SENDBUF_SIZE) {
isc_log_write(
isc_lctx, ISC_LOGCATEGORY_GENERAL,
ISC_LOGMODULE_NETMGR, ISC_LOG_DEBUG(3),
"resuming TCP connection, the other side "
"is reading the data again (%zu)",
write_queue_size);
sock->reading_throttled = false;
isc__nm_start_reading(sock);
isc_result_t result = isc__nm_process_sock_buffer(sock);
if (result != ISC_R_SUCCESS) {
atomic_store(&sock->reading, true);
isc__nm_failed_read_cb(sock, result, false);
}
}
}

23
lib/isc/netmgr/tlsdns.c
View file

@ -1828,25 +1828,10 @@ tlsdns_maybe_restart_reading(isc_nmsocket_t *sock) {
if (!sock->client && sock->reading_throttled &&
!uv_is_active(&sock->uv_handle.handle))
{
/*
* Restart reading if we have less data in the send queue than
* the send buffer size, this means that the TCP client has
* started reading some data again. Starting reading when we go
* under the limit instead of waiting for all data has been
* flushed allows faster recovery (in case there was a
* congestion and now there isn't).
*/
size_t write_queue_size =
uv_stream_get_write_queue_size(&sock->uv_handle.stream);
if (write_queue_size < ISC_NETMGR_TCP_SENDBUF_SIZE) {
isc_log_write(
isc_lctx, ISC_LOGCATEGORY_GENERAL,
ISC_LOGMODULE_NETMGR, ISC_LOG_DEBUG(3),
"resuming TCP connection, the other side "
"is reading the data again (%zu)",
write_queue_size);
sock->reading_throttled = false;
isc__nm_start_reading(sock);
isc_result_t result = isc__nm_process_sock_buffer(sock);
if (result != ISC_R_SUCCESS) {
atomic_store(&sock->reading, true);
isc__nm_failed_read_cb(sock, result, false);
}
}
}