Reorder sanity checks on UDP packet reception, to cope with failed recvfrom()
diff --git a/src/forward.c b/src/forward.c
index 3f4ec62..a607959 100644
--- a/src/forward.c
+++ b/src/forward.c
@@ -698,14 +698,20 @@
serveraddr.in6.sin6_flowinfo = 0;
#endif
+ header = (struct dns_header *)daemon->packet;
+
+ if (n < (int)sizeof(struct dns_header) || !(header->hb3 & HB3_QR))
+ return;
+
/* spoof check: answer must come from known server, */
for (server = daemon->servers; server; server = server->next)
if (!(server->flags & (SERV_LITERAL_ADDRESS | SERV_NO_ADDR)) &&
sockaddr_isequal(&server->addr, &serveraddr))
break;
-
- header = (struct dns_header *)daemon->packet;
-
+
+ if (!server)
+ return;
+
#ifdef HAVE_DNSSEC
hash = hash_questions(header, n, daemon->namebuff);
#else
@@ -713,11 +719,9 @@
crc = questions_crc(header, n, daemon->namebuff);
#endif
- if (!server ||
- n < (int)sizeof(struct dns_header) || !(header->hb3 & HB3_QR) ||
- !(forward = lookup_frec(ntohs(header->id), hash)))
+ if (!(forward = lookup_frec(ntohs(header->id), hash)))
return;
-
+
if ((RCODE(header) == SERVFAIL || RCODE(header) == REFUSED) &&
!option_bool(OPT_ORDER) &&
forward->forwardall == 0)
