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Drop expired but not accepted TCP connections

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This commit ensures that we are not attempting to accept an expired
TCP connection as we are not interested in any data that could have
been accumulated in its internal buffers. Now we just drop them for
good.
This commit is contained in:
Artem Boldariev 2024-07-02 16:16:59 +03:00
parent bf9fd2a6ff
commit 5781ff3a93
2 changed files with 30 additions and 0 deletions
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7
lib/isc/netmgr/netmgr-int.h
View File

@ -36,6 +36,7 @@
#include <isc/stats.h>
#include <isc/thread.h>
#include <isc/tid.h>
#include <isc/time.h>
#include <isc/tls.h>
#include <isc/util.h>
#include <isc/uv.h>
@ -641,6 +642,12 @@ struct isc_nmsocket {
bool reading;
bool timedout;
/*%
* A timestamp of when the connection acceptance was delayed due
* to quota.
*/
isc_nanosecs_t quota_accept_ts;
/*%
* Established an outgoing connection, as client not server.
*/

23
lib/isc/netmgr/tcp.c
View File

@ -549,6 +549,7 @@ tcp_connection_cb(uv_stream_t *server, int status) {
&csock->quotacb, quota_accept_cb,
csock);
if (result == ISC_R_QUOTA) {
csock->quota_accept_ts = isc_time_monotonic();
isc__nm_incstats(ssock, STATID_ACCEPTFAIL);
goto done;
}
@ -901,6 +902,28 @@ accept_connection(isc_nmsocket_t *csock) {
goto failure;
}
/* Check if the connection is not expired */
if (csock->quota_accept_ts != 0) {
/* The timestamp is given in nanoseconds */
const uint64_t time_elapsed_ms =
(isc_time_monotonic() - csock->quota_accept_ts) /
NS_PER_MS;
if (time_elapsed_ms >= csock->read_timeout) {
/*
* At this point we have received a connection from a
* queue of accepted connections (via uv_accept()), but
* it has expired. We cannot do anything better than
* drop it on the floor at this point.
*/
result = ISC_R_TIMEDOUT;
goto failure;
} else {
/* Adjust the initial read timeout accordingly */
csock->read_timeout -= time_elapsed_ms;
}
}
r = uv_tcp_getpeername(&csock->uv_handle.tcp, (struct sockaddr *)&ss,
&(int){ sizeof(ss) });
if (r != 0) {