Handle errors when sending ICMP6 pings better.

src/dnsmasq.h

@@ -911,9 +911,9 @@ unsigned char *tcp_request(int confd, time_t now,
 			   union mysockaddr *local_addr, struct in_addr netmask);
 void server_gone(struct server *server);
 struct frec *get_new_frec(time_t now, int *wait);
-void send_from(int fd, int nowild, char *packet, size_t len, 
+int send_from(int fd, int nowild, char *packet, size_t len, 
 	       union mysockaddr *to, struct all_addr *source,
-	       unsigned int iface);
+	       unsigned int iface, int *errp);
 
 /* network.c */
 int indextoname(int fd, int index, char *name);

src/forward.c

@@ -26,9 +26,9 @@ static struct randfd *allocate_rfd(int family);
 
 /* Send a UDP packet with its source address set as "source" 
    unless nowild is true, when we just send it with the kernel default */
-void send_from(int fd, int nowild, char *packet, size_t len, 
+int send_from(int fd, int nowild, char *packet, size_t len, 
-	       union mysockaddr *to, struct all_addr *source,
+	      union mysockaddr *to, struct all_addr *source,
-	       unsigned int iface)
+	      unsigned int iface, int *errp)
 {
   struct msghdr msg;
   struct iovec iov[1]; 
@@ -110,8 +110,15 @@ void send_from(int fd, int nowild, char *packet, size_t len,
       if (retry_send())
 	goto retry;
       
-      my_syslog(LOG_ERR, _("failed to send packet: %s"), strerror(errno));
+      if (errp)
+	*errp = errno;
+      else
+	my_syslog(LOG_ERR, _("failed to send packet: %s"), strerror(errno));
+      
+      return 0;
     }
+
+  return 1;
 }
           
 static unsigned int search_servers(time_t now, struct all_addr **addrpp, 
@@ -432,7 +439,7 @@ static int forward_query(int udpfd, union mysockaddr *udpaddr,
   if (udpfd != -1)
     {
       plen = setup_reply(header, plen, addrp, flags, daemon->local_ttl);
-      send_from(udpfd, option_bool(OPT_NOWILD), (char *)header, plen, udpaddr, dst_addr, dst_iface);
+      send_from(udpfd, option_bool(OPT_NOWILD), (char *)header, plen, udpaddr, dst_addr, dst_iface, NULL);
     }
 
   return 0;
@@ -621,7 +628,7 @@ void reply_query(int fd, int family, time_t now)
 	  header->id = htons(forward->orig_id);
 	  header->hb4 |= HB4_RA; /* recursion if available */
 	  send_from(forward->fd, option_bool(OPT_NOWILD), daemon->packet, nn, 
-		    &forward->source, &forward->dest, forward->iface);
+		    &forward->source, &forward->dest, forward->iface, NULL);
 	}
       free_frec(forward); /* cancel */
     }
@@ -816,7 +823,7 @@ void receive_query(struct listener *listen, time_t now)
   if (m >= 1)
     {
       send_from(listen->fd, option_bool(OPT_NOWILD), (char *)header, 
-		m, &source_addr, &dst_addr, if_index);
+		m, &source_addr, &dst_addr, if_index, NULL);
       daemon->local_answer++;
     }
   else if (forward_query(listen->fd, &source_addr, &dst_addr, if_index,

src/radv.c

@@ -266,7 +266,7 @@ static void send_ra(int iface, char *iface_name, struct in6_addr *dest)
     inet_pton(AF_INET6, ALL_HOSTS, &addr.sin6_addr); 
   
   send_from(daemon->icmp6fd, 0, daemon->outpacket.iov_base, save_counter(0),
-	    (union mysockaddr *)&addr, (struct all_addr *)&parm.link_local, iface); 
+	    (union mysockaddr *)&addr, (struct all_addr *)&parm.link_local, iface, NULL); 
   
 }
 

src/slaac.c

@@ -131,14 +131,15 @@ time_t periodic_slaac(time_t now, struct dhcp_lease *leases)
   for (lease = leases; lease; lease = lease->next)
     for (slaac = lease->slaac_address; slaac; slaac = slaac->next)
       {
-	/* confirmed? */
+	/* confirmed or given up? */
-	if (slaac->backoff == 0)
+	if (slaac->backoff == 0 || slaac->ping_time == 0)
 	  continue;
 	
 	if (difftime(slaac->ping_time, now) <= 0.0)
 	  {
 	    struct ping_packet *ping;
 	    struct sockaddr_in6 addr;
+	    int err;
 	    
 	    save_counter(0);
 	    ping = expand(sizeof(struct ping_packet));
@@ -155,16 +156,22 @@ time_t periodic_slaac(time_t now, struct dhcp_lease *leases)
 	    addr.sin6_port = htons(IPPROTO_ICMPV6);
 	    addr.sin6_addr = slaac->addr;
 	    
-	    send_from(daemon->icmp6fd, 0, daemon->outpacket.iov_base, save_counter(0),
+	    if (send_from(daemon->icmp6fd, 0, daemon->outpacket.iov_base, save_counter(0),
-		      (union mysockaddr *)&addr, (struct all_addr *)&slaac->local, lease->last_interface); 
+			  (union mysockaddr *)&addr, (struct all_addr *)&slaac->local, 
-	    
+			  lease->last_interface, &err)) 
-	    slaac->ping_time += (1 << (slaac->backoff - 1)) + (rand16()/21785); /* 0 - 3 */
+	      {
-	    if (slaac->backoff > 4)
+		slaac->ping_time += (1 << (slaac->backoff - 1)) + (rand16()/21785); /* 0 - 3 */
-	      slaac->ping_time += rand16()/4000; /* 0 - 15 */
+		if (slaac->backoff > 4)
-	    slaac->backoff++;
+		  slaac->ping_time += rand16()/4000; /* 0 - 15 */
+		if (slaac->backoff < 12)
+		  slaac->backoff++;
+	      }
+	    else if (err == EHOSTUNREACH)
+	      slaac->ping_time = 0; /* Give up */
 	  }
 	
-	if (next_event == 0 || difftime(next_event, slaac->ping_time) >= 0.0)
+	if (slaac->ping_time != 0 &&
+	    (next_event == 0 || difftime(next_event, slaac->ping_time) >= 0.0))
 	  next_event = slaac->ping_time;
       }