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resolved: fix use of ERRNO_IS_DISCONNECT()

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Given that ERRNO_IS_DISCONNECT() also matches positive values,
make sure this macro is not called with arguments that do not have
errno semantics.

In this case the argument passed to ERRNO_IS_DISCONNECT() is the value
returned by manager_recv() which can legitimately return 1 without errno
semantics, so fix this by moving ERRNO_IS_DISCONNECT() invocation to the
branch where the return value is known to be negative.
This commit is contained in:
Dmitry V. Levin 2023-07-07 08:00:00 +00:00
parent bb228f0ebc
commit 0bdea17c0a
1 changed files with 15 additions and 18 deletions
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33
src/resolve/resolved-dns-transaction.c
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@ -1367,25 +1367,22 @@ static int on_dns_packet(sd_event_source *s, int fd, uint32_t revents, void *use
assert(t->scope);
r = manager_recv(t->scope->manager, fd, DNS_PROTOCOL_DNS, &p);
if (ERRNO_IS_DISCONNECT(r)) {
usec_t usec;
/* UDP connection failures get reported via ICMP and then are possibly delivered to us on the
* next recvmsg(). Treat this like a lost packet. */
log_debug_errno(r, "Connection failure for DNS UDP packet: %m");
assert_se(sd_event_now(t->scope->manager->event, CLOCK_BOOTTIME, &usec) >= 0);
dns_server_packet_lost(t->server, IPPROTO_UDP, t->current_feature_level);
dns_transaction_close_connection(t, /* use_graveyard = */ false);
if (dns_transaction_limited_retry(t)) /* Try a different server */
return 0;
dns_transaction_complete_errno(t, r);
return 0;
}
if (r < 0) {
if (ERRNO_IS_DISCONNECT(r)) {
usec_t usec;
/* UDP connection failures get reported via ICMP and then are possibly delivered to us on the
* next recvmsg(). Treat this like a lost packet. */
log_debug_errno(r, "Connection failure for DNS UDP packet: %m");
assert_se(sd_event_now(t->scope->manager->event, CLOCK_BOOTTIME, &usec) >= 0);
dns_server_packet_lost(t->server, IPPROTO_UDP, t->current_feature_level);
dns_transaction_close_connection(t, /* use_graveyard = */ false);
if (dns_transaction_limited_retry(t)) /* Try a different server */
return 0;
}
dns_transaction_complete_errno(t, r);
return 0;
}