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Log failed TCP DNS connections upstream when --log-debug active.

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This commit is contained in:
Simon Kelley
2025-02-05 17:15:52 +00:00
parent f31667317d
commit 0b6144583b
1 changed files with 11 additions and 5 deletions
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16
src/forward.c
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@@ -1934,7 +1934,7 @@ static ssize_t tcp_talk(int first, int last, int start, unsigned char *packet,
break;
}
serv = daemon->serverarray[start];
*servp = serv = daemon->serverarray[start];
retry:
blockdata_retrieve(saved_question, qsize, header);
@@ -1985,6 +1985,10 @@ static ssize_t tcp_talk(int first, int last, int start, unsigned char *packet,
trying again in non-FASTOPEN mode. */
if (fatal || (!data_sent && connect(serv->tcpfd, &serv->addr.sa, sa_len(&serv->addr)) == -1))
{
failed:
int port = prettyprint_addr(&serv->addr, daemon->addrbuff);
my_syslog(LOG_DEBUG|MS_DEBUG, _("TCP connection failed to %s#%d"), daemon->addrbuff, port);
close(serv->tcpfd);
serv->tcpfd = -1;
continue;
@@ -2000,15 +2004,17 @@ static ssize_t tcp_talk(int first, int last, int start, unsigned char *packet,
!read_write(serv->tcpfd, (unsigned char *)length, sizeof (*length), RW_READ_ONCE) ||
!read_write(serv->tcpfd, payload, (rsize = ntohs(*length)), RW_READ_ONCE))
{
close(serv->tcpfd);
serv->tcpfd = -1;
/* We get data then EOF, reopen connection to same server,
else try next. This avoids DoS from a server which accepts
connections and then closes them. */
if (serv->flags & SERV_GOT_TCP)
goto retry;
{
close(serv->tcpfd);
serv->tcpfd = -1;
goto retry;
}
else
continue;
goto failed;
}
/* If the question section of the reply doesn't match the question we sent, then