Fix hang at startup when DHCPv6 enabled on a complex network

configuration - we have to read all the MAC addresses from netlink,
not bail when we find a suitable one.

Fix thinko in dhcp_update_configs - thanks to Hartmut for spotting
that.

Get a sensible address for the default DNS server even when using a
relay.

debian/rules

@@ -33,8 +33,8 @@ ifeq ($(DEB_BUILD_ARCH_OS),linux)
 endif
 endif
 
-ifeq (,$(filter nodhcp6,$(DEB_BUILD_OPTIONS)))
-     COPTS += -DHAVE_DHCP6
+ifneq (,$(filter nodhcp6,$(DEB_BUILD_OPTIONS)))
+     COPTS += -DNO_DHCP6
 endif
 
 ifneq (,$(filter noipv6,$(DEB_BUILD_OPTIONS)))

src/dhcp-common.c

@@ -332,9 +332,9 @@ void dhcp_update_configs(struct dhcp_config *configs)
 	      }
 
 #ifdef HAVE_DHCP6
-	    if (prot == AF_INET6 && !config_find_by_address6(configs, &crec->addr.addr.addr.addr6, 129, 0))
+	    if (prot == AF_INET6 && !config_find_by_address6(configs, &crec->addr.addr.addr.addr6, 128, 0))
 	      {
-		memcpy(config->hwaddr, &crec->addr.addr.addr.addr6, IN6ADDRSZ);
+		memcpy(&config->addr6, &crec->addr.addr.addr.addr6, IN6ADDRSZ);
 		config->flags |= CONFIG_ADDR6 | CONFIG_ADDR_HOSTS;
 		continue;
 	      }

src/dhcp6.c

@@ -20,6 +20,7 @@
 
 struct iface_param {
   struct dhcp_context *current;
+  struct in6_addr fallback;
   int ind;
 };
 
@@ -200,10 +201,14 @@ void dhcp6_packet(time_t now)
 
   /* unlinked contexts are marked by context->current == context */
   for (context = daemon->dhcp6; context; context = context->next)
-    context->current = context;
-  
+    {
+      context->current = context;
+      memset(&context->local6, 0, IN6ADDRSZ);
+    }
+
   parm.current = NULL;
   parm.ind = if_index;
+  memset(&parm.fallback, 0, IN6ADDRSZ);
   
   if (!iface_enumerate(AF_INET6, &parm, complete_context6))
     return;
@@ -211,7 +216,7 @@ void dhcp6_packet(time_t now)
   lease_prune(NULL, now); /* lose any expired leases */
 
   msg.msg_iov =  &daemon->dhcp_packet;
-  sz = dhcp6_reply(parm.current, if_index, ifr.ifr_name, sz, IN6_IS_ADDR_MULTICAST(&from.in6.sin6_addr), now);
+  sz = dhcp6_reply(parm.current, if_index, ifr.ifr_name, &parm.fallback, sz, IN6_IS_ADDR_MULTICAST(&from.in6.sin6_addr), now);
   
   lease_update_file(now);
   lease_update_dns();
@@ -229,23 +234,32 @@ static int complete_context6(struct in6_addr *local,  int prefix,
 
   (void)scope; /* warning */
   (void)dad;
-
-  for (context = daemon->dhcp6; context; context = context->next)
+  
+  if (if_index == param->ind &&
+      !IN6_IS_ADDR_LOOPBACK(local) &&
+      !IN6_IS_ADDR_LINKLOCAL(local) &&
+      !IN6_IS_ADDR_MULTICAST(local))
     {
-      if (prefix == context->prefix &&
-	  !IN6_IS_ADDR_LOOPBACK(local) &&
-	  !IN6_IS_ADDR_LINKLOCAL(local) &&
-	  !IN6_IS_ADDR_MULTICAST(local) &&
-	  is_same_net6(local, &context->start6, prefix) &&
-          is_same_net6(local, &context->end6, prefix))
-        {
-          /* link it onto the current chain if we've not seen it before */
-          if (if_index == param->ind && context->current == context)
-            {
-              context->current = param->current;
-              param->current = context;
-	      context->local6 = *local;
-            }
+      /* Determine a globally address on the arrival interface, even
+	 if we have no matching dhcp-context, because we're only
+	 allocating on remote subnets via relays. This
+	 is used as a default for the DNS server option. */
+      memcpy(&param->fallback, &local, IN6ADDRSZ);
+      
+      for (context = daemon->dhcp6; context; context = context->next)
+	{
+	  if (prefix == context->prefix &&
+	      is_same_net6(local, &context->start6, prefix) &&
+	      is_same_net6(local, &context->end6, prefix))
+	    {
+	      /* link it onto the current chain if we've not seen it before */
+	      if (context->current == context)
+		{
+		  context->current = param->current;
+		  param->current = context;
+		  context->local6 = *local;
+		}
+	    }
 	}
     }          
   return 1;
@@ -305,7 +319,7 @@ int address6_allocate(struct dhcp_context *context,  unsigned char *clid, int cl
 	  do {
 	    /* eliminate addresses in use by the server. */
 	    for (d = context; d; d = d->current)
-	      if (addr == addr6part(&d->router6))
+	      if (addr == addr6part(&d->local6))
 		break;
 
 	    if (!d &&

src/dnsmasq.h

@@ -603,7 +603,7 @@ struct dhcp_context {
   struct in_addr start, end; /* range of available addresses */
 #ifdef HAVE_DHCP6
   struct in6_addr start6, end6; /* range of available addresses */
-  struct in6_addr local6, router6;
+  struct in6_addr local6;
   int prefix;
 #endif
   int flags;
@@ -1036,7 +1036,8 @@ void make_duid(time_t now);
 
 /* rfc3315.c */
 #ifdef HAVE_DHCP6
-size_t dhcp6_reply(struct dhcp_context *context, int interface, char *iface_name, size_t sz, int is_multicast, time_t now);
+size_t dhcp6_reply(struct dhcp_context *context, int interface, char *iface_name,  
+		   struct in6_addr *fallback, size_t sz, int is_multicast, time_t now);
 #endif
 
 /* dhcp-common.c */

src/netlink.c

@@ -136,6 +136,7 @@ int iface_enumerate(int family, void *parm, int (*callback)())
   struct nlmsghdr *h;
   ssize_t len;
   static unsigned int seq = 0;
+  int callback_ok = 1;
 
   struct {
     struct nlmsghdr nlh;
@@ -186,7 +187,7 @@ int iface_enumerate(int family, void *parm, int (*callback)())
 	else if (h->nlmsg_type == NLMSG_ERROR)
 	  nl_err(h);
 	else if (h->nlmsg_type == NLMSG_DONE)
-	  return 1;
+	  return callback_ok;
 	else if (h->nlmsg_type == RTM_NEWADDR && family != AF_UNSPEC && family != AF_LOCAL)
 	  {
 	    struct ifaddrmsg *ifa = NLMSG_DATA(h);  
@@ -213,9 +214,9 @@ int iface_enumerate(int family, void *parm, int (*callback)())
 			rta = RTA_NEXT(rta, len1);
 		      }
 		    
-		    if (addr.s_addr)
+		    if (addr.s_addr && callback_ok)
 		      if (!((*callback)(addr, ifa->ifa_index, netmask, broadcast, parm)))
-			return 0;
+			callback_ok = 0;
 		  }
 #ifdef HAVE_IPV6
 		else if (ifa->ifa_family == AF_INET6)
@@ -229,10 +230,10 @@ int iface_enumerate(int family, void *parm, int (*callback)())
 			rta = RTA_NEXT(rta, len1);
 		      }
 		    
-		    if (addrp)
+		    if (addrp && callback_ok)
 		      if (!((*callback)(addrp, (int)(ifa->ifa_prefixlen), (int)(ifa->ifa_scope), 
 					(int)(ifa->ifa_index), (int)(ifa->ifa_flags & IFA_F_TENTATIVE), parm)))
-			return 0;
+			callback_ok = 0;
 		  }
 #endif
 	      }
@@ -258,9 +259,9 @@ int iface_enumerate(int family, void *parm, int (*callback)())
 		rta = RTA_NEXT(rta, len1);
 	      }
 
-	    if (inaddr && mac)
+	    if (inaddr && mac && callback_ok)
 	      if (!((*callback)(neigh->ndm_family, inaddr, mac, maclen, parm)))
-		return 0;
+		callback_ok = 0;
 	  }
 #ifdef HAVE_DHCP6
 	else if (h->nlmsg_type == RTM_NEWLINK && family == AF_LOCAL)
@@ -282,9 +283,9 @@ int iface_enumerate(int family, void *parm, int (*callback)())
 		rta = RTA_NEXT(rta, len1);
 	      }
 
-	    if (mac && !((link->ifi_flags & (IFF_LOOPBACK | IFF_POINTOPOINT))) && 
+	    if (mac && callback_ok && !((link->ifi_flags & (IFF_LOOPBACK | IFF_POINTOPOINT))) && 
 		!((*callback)((unsigned int)link->ifi_type, mac, maclen, parm)))
-	      return 0;
+	      callback_ok = 0;
 	  }
 #endif
     }

src/rfc3315.c

@@ -31,9 +31,9 @@ static void put_opt6_long(unsigned int val);
 static void put_opt6_string(char *s);
 
 static int dhcp6_maybe_relay(struct in6_addr *link_address, struct dhcp_netid **relay_tagsp, struct dhcp_context *context, 
-			     int interface, char *iface_name, void *inbuff, size_t sz, int is_unicast, time_t now);
+			     int interface, char *iface_name, struct in6_addr *fallback, void *inbuff, size_t sz, int is_unicast, time_t now);
 static int dhcp6_no_relay(int msg_type,  struct in6_addr *link_address, struct dhcp_netid *tags, struct dhcp_context *context, 
-			  int interface, char *iface_name, void *inbuff, size_t sz, int is_unicast, time_t now);
+			  int interface, char *iface_name, struct in6_addr *fallback, void *inbuff, size_t sz, int is_unicast, time_t now);
 static void log6_packet(char *type, unsigned char *clid, int clid_len, struct in6_addr *addr, int xid, char *iface, char *string);
 
 static void *opt6_find (void *opts, void *end, unsigned int search, unsigned int minsize);
@@ -45,7 +45,8 @@ static unsigned int opt6_uint(unsigned char *opt, int offset, int size);
 #define opt6_ptr(opt, i) ((void *)&(((unsigned char *)(opt))[4+(i)]))
 
 
-size_t dhcp6_reply(struct dhcp_context *context, int interface, char *iface_name, size_t sz, int is_unicast, time_t now)
+size_t dhcp6_reply(struct dhcp_context *context, int interface, char *iface_name,
+		   struct in6_addr *fallback, size_t sz, int is_unicast, time_t now)
 {
   struct dhcp_netid *relay_tags = NULL;
   struct dhcp_vendor *vendor;
@@ -56,7 +57,7 @@ size_t dhcp6_reply(struct dhcp_context *context, int interface, char *iface_name
   
   outpacket_counter = 0;
   
-  if (dhcp6_maybe_relay(NULL, &relay_tags, context, interface, iface_name, daemon->dhcp_packet.iov_base, sz, is_unicast, now))
+  if (dhcp6_maybe_relay(NULL, &relay_tags, context, interface, iface_name, fallback, daemon->dhcp_packet.iov_base, sz, is_unicast, now))
     return outpacket_counter;
 
   return 0;
@@ -64,7 +65,7 @@ size_t dhcp6_reply(struct dhcp_context *context, int interface, char *iface_name
 
 /* This cost me blood to write, it will probably cost you blood to understand - srk. */
 static int dhcp6_maybe_relay(struct in6_addr *link_address, struct dhcp_netid **relay_tagsp, struct dhcp_context *context,
-			     int interface, char *iface_name, void *inbuff, size_t sz, int is_unicast, time_t now)
+			     int interface, char *iface_name, struct in6_addr *fallback, void *inbuff, size_t sz, int is_unicast, time_t now)
 {
   void *end = inbuff + sz;
   void *opts = inbuff + 34;
@@ -114,7 +115,7 @@ static int dhcp6_maybe_relay(struct in6_addr *link_address, struct dhcp_netid **
 	  return 0;
 	}
 
-      return dhcp6_no_relay(msg_type, link_address, *relay_tagsp, context, interface, iface_name, inbuff, sz, is_unicast, now);
+      return dhcp6_no_relay(msg_type, link_address, *relay_tagsp, context, interface, iface_name, fallback, inbuff, sz, is_unicast, now);
     }
 
   /* must have at least msg_type+hopcount+link_address+peer_address+minimal size option
@@ -159,7 +160,7 @@ static int dhcp6_maybe_relay(struct in6_addr *link_address, struct dhcp_netid **
 	  memcpy(&link_address, inbuff + 2, IN6ADDRSZ); 
 	  /* Not, zero is_unicast since that is now known to refer to the 
 	     relayed packet, not the original sent by the client */
-	  if (!dhcp6_maybe_relay(&link_address, relay_tagsp, context, interface, iface_name, opt6_ptr(opt, 0), opt6_len(opt), 0, now))
+	  if (!dhcp6_maybe_relay(&link_address, relay_tagsp, context, interface, iface_name, fallback, opt6_ptr(opt, 0), opt6_len(opt), 0, now))
 	    return 0;
 	}
       else
@@ -171,7 +172,7 @@ static int dhcp6_maybe_relay(struct in6_addr *link_address, struct dhcp_netid **
 }
 
 static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dhcp_netid *tags, struct dhcp_context *context, 
-			  int interface, char *iface_name, void *inbuff, size_t sz, int is_unicast, time_t now)
+			  int interface, char *iface_name, struct in6_addr *fallback, void *inbuff, size_t sz, int is_unicast, time_t now)
 {
   void *packet_options = inbuff + 4;
   void *end = inbuff + sz;
@@ -394,7 +395,7 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
 	      if (!config)
 		{
 		  /* Search again now we have a hostname. 
-		     Only accept configs without CLID and HWADDR here, (they won't match)
+		     Only accept configs without CLID here, (it won't match)
 		     to avoid impersonation by name. */
 		  struct dhcp_config *new = find_config6(daemon->dhcp_conf, context, NULL, 0, hostname);
 		  if (new && !have_config(new, CONFIG_CLID) && !new->hwaddr)
@@ -422,18 +423,31 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
       if (have_config(config, CONFIG_DISABLE))
 	ignore = 1;
     }
+   
+  tagif = run_tag_if(tags);
   
   /* if all the netids in the ignore list are present, ignore this client */
   if (daemon->dhcp_ignore)
     {
       struct dhcp_netid_list *id_list;
      
-      tagif = run_tag_if(tags);
-      
       for (id_list = daemon->dhcp_ignore; id_list; id_list = id_list->next)
 	if (match_netid(id_list->list, tagif, 0))
 	  ignore = 1;
     }
+  
+  /* if all the netids in the ignore_name list are present, ignore client-supplied name */
+  if (!hostname_auth)
+    {
+       struct dhcp_netid_list *id_list;
+       
+       for (id_list = daemon->dhcp_ignore_names; id_list; id_list = id_list->next)
+	 if ((!id_list->list) || match_netid(id_list->list, tagif, 0))
+	   break;
+       if (id_list)
+	 hostname = NULL;
+    }
+  
 
   switch (msg_type)
     {
@@ -508,7 +522,8 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
 		    struct in6_addr *req_addr = opt6_ptr(ia_option, 0);
 		    preferred_time = opt6_uint(ia_option, 16, 4);
 		    
-		    if (!address6_available(context, req_addr, tags))
+		    if (!address6_available(context, req_addr, tags) &&
+			(!have_config(config, CONFIG_ADDR6) || memcmp(&config->addr6, req_addr, IN6ADDRSZ) != 0))
 		      {
 			if (msg_type == DHCP6REQUEST)
 			  {
@@ -584,13 +599,23 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
 		    address_assigned = 1;
 		    
 		    /* shouldn't ever fail */
-		    if ((this_context = narrow_context6(context, addrp, tags)))
+		    if ((this_context = narrow_context6(context, addrp, tagif)))
 		      {
 			/* get tags from context if we've not used it before */
-			if (this_context->netid.next != &this_context->netid && this_context->netid.net)
+			if (this_context->netid.next == &this_context->netid && this_context->netid.net)
 			  {
 			    this_context->netid.next = context_tags;
 			    context_tags = &this_context->netid;
+			    if (!hostname_auth)
+			      {
+				struct dhcp_netid_list *id_list;
+				
+				for (id_list = daemon->dhcp_ignore_names; id_list; id_list = id_list->next)
+				  if ((!id_list->list) || match_netid(id_list->list, &this_context->netid, 0))
+				    break;
+				if (id_list)
+				  hostname = NULL;
+			      }
 			  }
 			
 			lease_time = have_config(valid_config, CONFIG_TIME) ? valid_config->lease_time : this_context->lease_time;
@@ -653,13 +678,18 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
 						    client_hostname ? strlen(client_hostname) : 0, 0);				
 				
 				/* space-concat tag set */
-				if (!tags)
+				if (!tagif && !context_tags)
 				  lease_add_extradata(lease, NULL, 0, 0);
 				else
 				  {
-				    struct dhcp_netid *n;
+				    struct dhcp_netid *n, *l;
 				    
-				    for (n = run_tag_if(tags); n; n = n->next)
+				    /* link temporarily */
+				    for (n = context_tags; n && n->next; n = n->next);
+				    if ((l = n))
+				      l->next = tags;
+				    
+				    for (n = run_tag_if(context_tags); n; n = n->next)
 				      {
 					struct dhcp_netid *n1;
 					/* kill dupes */
@@ -669,6 +699,10 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
 					if (!n1)
 					  lease_add_extradata(lease, (unsigned char *)n->net, strlen(n->net), n->next ? ' ' : 0); 
 				      }
+
+				    /* unlink again */
+				    if (l)
+				      l->next = NULL;
 				  }
 
 				if (link_address)
@@ -820,17 +854,27 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
 		    break;
 		  }
 		
-		tagif = run_tag_if(tags);
+		
 		if (!address6_available(context, req_addr, tagif) || 
 		    !(this_context = narrow_context6(context, req_addr, tagif)))
 		  lease_time = 0;
 		else
 		  {
 		    /* get tags from context if we've not used it before */
-		    if (this_context->netid.next != &this_context->netid && this_context->netid.net)
+		    if (this_context->netid.next == &this_context->netid && this_context->netid.net)
 		      {
 			this_context->netid.next = context_tags;
 			context_tags = &this_context->netid;
+			if (!hostname_auth)
+			  {
+			    struct dhcp_netid_list *id_list;
+			    
+			    for (id_list = daemon->dhcp_ignore_names; id_list; id_list = id_list->next)
+			      if ((!id_list->list) || match_netid(id_list->list, &this_context->netid, 0))
+				break;
+			    if (id_list)
+			      hostname = NULL;
+			  }
 		      }
 		    
 		    lease_time = have_config(valid_config, CONFIG_TIME) ? valid_config->lease_time : this_context->lease_time;
@@ -1148,10 +1192,15 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
       
     }
   
-  if (!done_dns)
+  if (!done_dns && 
+      (!IN6_IS_ADDR_UNSPECIFIED(&context->local6) ||
+       !IN6_IS_ADDR_UNSPECIFIED(fallback)))
     {
       o = new_opt6(OPTION6_DNS_SERVER);
-      put_opt6(&context->local6, IN6ADDRSZ);
+      if (IN6_IS_ADDR_UNSPECIFIED(&context->local6))
+	put_opt6(fallback, IN6ADDRSZ);
+      else
+	put_opt6(&context->local6, IN6ADDRSZ);
       end_opt6(o); 
     }
    
@@ -1213,18 +1262,6 @@ static int dhcp6_no_relay(int msg_type, struct in6_addr *link_address, struct dh
     }      
 
 
-  /* if all the netids in the ignore_name list are present, ignore client-supplied name */
-  if (!hostname_auth)
-    {
-       struct dhcp_netid_list *id_list;
-       
-       for (id_list = daemon->dhcp_ignore_names; id_list; id_list = id_list->next)
-	 if ((!id_list->list) || match_netid(id_list->list, tagif, 0))
-	   break;
-       if (id_list)
-	 hostname = NULL;
-    }
-  
   if (hostname)
     {
       unsigned char *p;