Fix for 12af2b171d

If identical queries from IPv4 and IPv6 sources are combined by the
new code added in 15b60ddf93 then replies
can end up being sent via the wrong family of socket. The ->fd
should be per query, not per-question.

In bind-interfaces mode, this could also result in replies being sent
via the wrong socket even when IPv4/IPV6 issues are not in play.

src/dnsmasq.h

@@ -664,6 +664,7 @@ struct frec {
     union mysockaddr source;
     union all_addr dest;
     unsigned int iface, log_id;
+    int fd;
     unsigned short orig_id;
     struct frec_src *next;
   } frec_src;
@@ -671,7 +672,7 @@ struct frec {
   struct randfd *rfd4;
   struct randfd *rfd6;
   unsigned short new_id;
-  int fd, forwardall, flags;
+  int forwardall, flags;
   time_t time;
   unsigned char *hash[HASH_SIZE];
 #ifdef HAVE_DNSSEC 

src/dnssec.c

@@ -335,6 +335,33 @@ static int sort_rrset(struct dns_header *header, size_t plen, u16 *rr_desc, int
 	    return rrsetidx; /* short packet */
 	  state2.end = state2.ip + rdlen2; 
 
+	  /* If the RR has no names in it then canonicalisation
+	     is the identity function and we can compare
+	     the RRs directly. If not we compare the 
+	     canonicalised RRs one byte at a time. */
+	  if (*rr_desc == (u16)-1)	  
+	    {
+	      int rdmin = rdlen1 > rdlen2 ? rdlen2 : rdlen1;
+	      int cmp = memcmp(state1.ip, state2.ip, rdmin);
+	      
+	      if (cmp > 0 || (cmp == 0 && rdlen1 > rdmin))
+		{
+		  unsigned char *tmp = rrset[i+1];
+		  rrset[i+1] = rrset[i];
+		  rrset[i] = tmp;
+		  swap = 1;
+		}
+	      else if (cmp == 0 && (rdlen1 == rdlen2))
+		{
+		  /* Two RRs are equal, remove one copy. RFC 4034, para 6.3 */
+		  for (j = i+1; j < rrsetidx-1; j++)
+		    rrset[j] = rrset[j+1];
+		  rrsetidx--;
+		  i--;
+		}
+	    }
+	  else
+	    /* Comparing canonicalised RRs, byte-at-a-time. */
 	    while (1)
 	      {
 		int ok1, ok2;

src/forward.c

@@ -378,6 +378,7 @@ static int forward_query(int udpfd, union mysockaddr *udpaddr,
 	      new->dest = *dst_addr;
 	      new->log_id = daemon->log_id;
 	      new->iface = dst_iface;
+	      new->fd = udpfd;
 	    }
 	  
 	  return 1;
@@ -402,8 +403,8 @@ static int forward_query(int udpfd, union mysockaddr *udpaddr,
 	  forward->frec_src.dest = *dst_addr;
 	  forward->frec_src.iface = dst_iface;
 	  forward->frec_src.next = NULL;
+	  forward->frec_src.fd = udpfd;
 	  forward->new_id = get_id();
-	  forward->fd = udpfd;
 	  memcpy(forward->hash, hash, HASH_SIZE);
 	  forward->forwardall = 0;
 	  forward->flags = fwd_flags;
@@ -1300,7 +1301,7 @@ void reply_query(int fd, int family, time_t now)
 	      dump_packet(DUMP_REPLY, daemon->packet, (size_t)nn, NULL, &src->source);
 #endif
 	      
-	      send_from(forward->fd, option_bool(OPT_NOWILD) || option_bool (OPT_CLEVERBIND), daemon->packet, nn, 
+	      send_from(src->fd, option_bool(OPT_NOWILD) || option_bool (OPT_CLEVERBIND), daemon->packet, nn, 
 			&src->source, &src->dest, src->iface);
 
 	      if (option_bool(OPT_EXTRALOG) && src != &forward->frec_src)