Advertise lost prefixes with pref_time == 0 for 2 hours.

CHANGELOG

@@ -71,6 +71,14 @@ version 2.67
 	    Make --clear-on-reload apply to setting upstream servers
 	    via DBus too.
 
+	    When the address which triggered the construction of an
+	    advertised IPv6 prefix disappears, continue to advertise 
+	    the prefix for up to 2 hours, with the preferred lifetime
+	    set to zero. This satisfies RFC 6204 4.3 L-13 and makes
+	    things work better if a prefix disappears without being
+	    deprecated first. Thanks to Uwe Schindler for persuasively
+	    arguing for this.
+
 
 version 2.66
             Add the ability to act as an authoritative DNS

src/dhcp-common.c

@@ -720,7 +720,7 @@ void log_context(int family, struct dhcp_context *context)
       p += sprintf(p, ", ");
       
       if (indextoname(daemon->doing_dhcp6 ? daemon->dhcp6fd : daemon->icmp6fd, context->if_index, ifrn_name))
-	sprintf(p, "constructed for %s", ifrn_name);
+	sprintf(p, "%s for %s", (context->flags & CONTEXT_OLD) ? "old prefix" : "constructed", ifrn_name);
     }
   else if (context->flags & CONTEXT_TEMPLATE)
     {
@@ -731,7 +731,8 @@ void log_context(int family, struct dhcp_context *context)
     }
 #endif
      
-  if ((context->flags & CONTEXT_DHCP) || family == AF_INET) 
+  if (!(context->flags & CONTEXT_OLD) &&
+      ((context->flags & CONTEXT_DHCP) || family == AF_INET)) 
     {
       inet_ntop(family, start, daemon->dhcp_buff, 256);
       inet_ntop(family, end, daemon->dhcp_buff3, 256);
@@ -748,7 +749,7 @@ void log_context(int family, struct dhcp_context *context)
     }
   
 #ifdef HAVE_DHCP6
-  if (context->flags & CONTEXT_RA_NAME)
+  if ((context->flags & CONTEXT_RA_NAME) && !(context->flags & CONTEXT_OLD))
     my_syslog(MS_DHCP | LOG_INFO, _("DHCPv4-derived IPv6 names on %s%s"), daemon->addrbuff, template);
   
   if ((context->flags & CONTEXT_RA) || (option_bool(OPT_RA) && (context->flags & CONTEXT_DHCP) && family == AF_INET6)) 

src/dhcp6.c

@@ -220,7 +220,7 @@ static int complete_context6(struct in6_addr *local,  int prefix,
       for (context = daemon->dhcp6; context; context = context->next)
 	{
 	  if ((context->flags & CONTEXT_DHCP) &&
-	      !(context->flags & CONTEXT_TEMPLATE) &&
+	      !(context->flags & (CONTEXT_TEMPLATE | CONTEXT_OLD)) &&
 	      prefix == context->prefix &&
 	      is_same_net6(local, &context->start6, prefix) &&
 	      is_same_net6(local, &context->end6, prefix))
@@ -552,7 +552,10 @@ static int construct_worker(struct in6_addr *local, int prefix,
 	      IN6_ARE_ADDR_EQUAL(&start6, &context->start6) &&
 	      IN6_ARE_ADDR_EQUAL(&end6, &context->end6))
 	    {
-	      context->flags &= ~CONTEXT_GC;
+	      int flags = context->flags;
+	      context->flags &= ~(CONTEXT_GC | CONTEXT_OLD);
+	      if (flags & CONTEXT_OLD)
+		log_context(AF_INET6, context);
 	      break;
 	    }
 	
@@ -565,6 +568,7 @@ static int construct_worker(struct in6_addr *local, int prefix,
 	    context->flags |= CONTEXT_CONSTRUCTED;
 	    context->if_index = if_index;
 	    context->local6 = *local;
+	    context->saved_valid = 0;
 	    
 	    context->next = daemon->dhcp6;
 	    daemon->dhcp6 = context;
@@ -587,35 +591,53 @@ static int construct_worker(struct in6_addr *local, int prefix,
 
 void dhcp_construct_contexts(time_t now)
 { 
-  struct dhcp_context *tmp, *context, **up;
+  struct dhcp_context *context, *tmp, **up;
   struct cparam param;
   param.newone = 0;
   param.newname = 0;
   param.now = now;
 
   for (context = daemon->dhcp6; context; context = context->next)
-    {
+    if (context->flags & CONTEXT_CONSTRUCTED)
-      context->if_index = 0;
+      context->flags |= CONTEXT_GC;
-      if (context->flags & CONTEXT_CONSTRUCTED)
-      	context->flags |= CONTEXT_GC;
-    }
    
   iface_enumerate(AF_INET6, &param, construct_worker);
 
   for (up = &daemon->dhcp6, context = daemon->dhcp6; context; context = tmp)
     {
+      
       tmp = context->next; 
      
-      if (context->flags & CONTEXT_GC)
+      if (context->flags & CONTEXT_GC && !(context->flags & CONTEXT_OLD))
 	{
-	  *up = context->next;
+	  
-	  param.newone = 1; /* include deletion */ 
+	  if ((context->flags & (CONTEXT_RA_ONLY | CONTEXT_RA_NAME | CONTEXT_RA_STATELESS)) ||
-	  if (context->flags & CONTEXT_RA_NAME)
+	      option_bool(OPT_RA))
-	    param.newname = 1; 
+	    {
-	  free(context);
+	      /* previously constructed context has gone. advertise it's demise */
+	      context->flags |= CONTEXT_OLD;
+	      context->address_lost_time = now;
+	      if (context->saved_valid > 7200) /* 2 hours */
+		context->saved_valid = 7200;
+	      ra_start_unsolicted(now, context);
+	      param.newone = 1; /* include deletion */ 
+	      
+	      if (context->flags & CONTEXT_RA_NAME)
+		param.newname = 1; 
+			      
+	      log_context(AF_INET6, context);
+	      
+	      up = &context->next;
+	    }
+	  else
+	    {
+	      /* we were never doing RA for this, so free now */
+	      *up = context->next;
+	      free(context);
+	    }
 	}
       else
-	up = &context->next;
+	 up = &context->next;
     }
   
   if (param.newone)

src/dnsmasq.h

@@ -706,8 +706,8 @@ struct dhcp_context {
   struct in6_addr start6, end6; /* range of available addresses */
   struct in6_addr local6;
   int prefix, if_index;
-  unsigned int valid, preferred;
+  unsigned int valid, preferred, saved_valid;
-  time_t ra_time, ra_short_period_start;
+  time_t ra_time, ra_short_period_start, address_lost_time;
   char *template_interface;
 #endif
   int flags;
@@ -732,6 +732,8 @@ struct dhcp_context {
 #define CONTEXT_CONF_USED  16384
 #define CONTEXT_USED       32768
 #define CONTEXT_NOAUTH     65536
+#define CONTEXT_OLD       131072
+
 
 struct ping_result {
   struct in_addr addr;

src/radv.c

@@ -47,6 +47,7 @@ static int iface_search(struct in6_addr *local,  int prefix,
 			int scope, int if_index, int flags, 
 			int prefered, int valid, void *vparam);
 static int add_lla(int index, unsigned int type, char *mac, size_t maclen, void *parm);
+static void new_timeout(struct dhcp_context *context, time_t now);
 
 static int hop_limit;
 
@@ -187,9 +188,8 @@ static void send_ra(time_t now, int iface, char *iface_name, struct in6_addr *de
 {
   struct ra_packet *ra;
   struct ra_param parm;
-  struct ifreq ifr;
   struct sockaddr_in6 addr;
-  struct dhcp_context *context;
+  struct dhcp_context *context, *tmp,  **up;
   struct dhcp_netid iface_id;
   struct dhcp_opt *opt_cfg;
   int done_dns = 0;
@@ -228,11 +228,65 @@ static void send_ra(time_t now, int iface, char *iface_name, struct in6_addr *de
       context->netid.next = &context->netid;
     }
 
-  if (!iface_enumerate(AF_INET6, &parm, add_prefixes) ||
+  if (!iface_enumerate(AF_INET6, &parm, add_prefixes))
-      !parm.found_context)
     return;
 
-  strncpy(ifr.ifr_name, iface_name, IF_NAMESIZE);
+  /* Look for constructed contexts associated with addresses which have gone, 
+     and advertise them with preferred_time == 0  RFC 6204 4.3 L-13 */
+  for (up = &daemon->dhcp6, context = daemon->dhcp6; context; context = tmp)
+    {
+      tmp = context->next;
+
+      if (context->if_index == iface && (context->flags & CONTEXT_OLD))
+	{
+	  unsigned int old = difftime(now, context->address_lost_time);
+	  
+	  if (old > context->saved_valid)
+	    {
+	      /* We've advertised this enough, time to go */
+	      *up = context->next;
+	      free(context);
+	    }
+	  else
+	    {
+	      struct prefix_opt *opt;
+	      struct in6_addr local = context->start6;
+	      int do_slaac = 0;
+
+	      parm.found_context = 1;
+
+	      /* zero net part of address */
+	      setaddr6part(&local, addr6part(&local) & ~((context->prefix == 64) ? (u64)-1LL : (1LLU << (128 - context->prefix)) - 1LLU));
+	     
+	      if ((context->flags & 
+		   (CONTEXT_RA_ONLY | CONTEXT_RA_NAME | CONTEXT_RA_STATELESS)))
+		do_slaac = 1;
+	      
+	      if ((opt = expand(sizeof(struct prefix_opt))))
+		{
+		  opt->type = ICMP6_OPT_PREFIX;
+		  opt->len = 4;
+		  opt->prefix_len = context->prefix;
+		  /* autonomous only if we're not doing dhcp, always set "on-link" */
+		  opt->flags = do_slaac ? 0xC0 : 0x80;
+		  opt->valid_lifetime = htonl(context->saved_valid - old);
+		  opt->preferred_lifetime = htonl(0);
+		  opt->reserved = 0; 
+		  opt->prefix = local;
+		  
+		  inet_ntop(AF_INET6, &local, daemon->addrbuff, ADDRSTRLEN);
+		  my_syslog(MS_DHCP | LOG_INFO, "RTR-ADVERT(%s) %s old prefix", iface_name, daemon->addrbuff); 		    
+		}
+	   
+	      up = &context->next;
+	    }
+	}
+      else
+	up = &context->next;
+    }
+    
+  if (!parm.found_context)
+    return;
     
 #ifdef HAVE_LINUX_NETWORK
   /* Note that IPv6 MTU is not necessarilly the same as the IPv4 MTU
@@ -361,11 +415,13 @@ static int add_prefixes(struct in6_addr *local,  int prefix,
 	  struct dhcp_context *context;
 	  
 	  for (context = daemon->dhcp6; context; context = context->next)
-	    if (!(context->flags & CONTEXT_TEMPLATE) &&
+	    if (!(context->flags & (CONTEXT_TEMPLATE | CONTEXT_OLD)) &&
 		prefix == context->prefix &&
 		is_same_net6(local, &context->start6, prefix) &&
 		is_same_net6(local, &context->end6, prefix))
 	      {
+		context->saved_valid = valid;
+
 		if ((context->flags & 
 		     (CONTEXT_RA_ONLY | CONTEXT_RA_NAME | CONTEXT_RA_STATELESS)))
 		  {
@@ -466,6 +522,7 @@ static int add_prefixes(struct in6_addr *local,  int prefix,
 		  inet_ntop(AF_INET6, local, daemon->addrbuff, ADDRSTRLEN);
 		  my_syslog(MS_DHCP | LOG_INFO, "RTR-ADVERT(%s) %s", param->if_name, daemon->addrbuff); 		    
 		}
+
 	    }
 	}
     }          
@@ -520,16 +577,25 @@ time_t periodic_ra(time_t now)
       if (!context)
 	break;
       
-      /* There's a context overdue, but we can't find an interface
+      if ((context->flags & CONTEXT_OLD) && context->if_index != 0)
-	 associated with it, because it's for a subnet we dont 
+	{
-	 have an interface on. Probably we're doing DHCP on
+	  /* A context for an old address. We'll not find the interface by 
-	 a remote subnet via a relay. Zero the timer, since we won't
+	     looking for addresses, but we know it anyway, as long as we
-	 ever be able to send ra's and satistfy it. */
+	     sent at least one RA whilst the address was current. */
-      if (iface_enumerate(AF_INET6, &param, iface_search))
+	  param.iface = context->if_index;
+	  new_timeout(context, now);
+	}
+      else if (iface_enumerate(AF_INET6, &param, iface_search))
+	/* There's a context overdue, but we can't find an interface
+	   associated with it, because it's for a subnet we dont 
+	   have an interface on. Probably we're doing DHCP on
+	   a remote subnet via a relay. Zero the timer, since we won't
+	   ever be able to send ra's and satistfy it. */
 	context->ra_time = 0;
-      else if (param.iface != 0 &&
+      
-	       indextoname(daemon->icmp6fd, param.iface, interface) &&
+      if (param.iface != 0 &&
-	       iface_check(AF_LOCAL, NULL, interface, NULL))
+	  indextoname(daemon->icmp6fd, param.iface, interface) &&
+	  iface_check(AF_LOCAL, NULL, interface, NULL))
 	{
 	  struct iname *tmp;
 	  for (tmp = daemon->dhcp_except; tmp; tmp = tmp->next)
@@ -554,7 +620,7 @@ static int iface_search(struct in6_addr *local,  int prefix,
   (void)valid;
  
   for (context = daemon->dhcp6; context; context = context->next)
-    if (!(context->flags & CONTEXT_TEMPLATE) &&
+    if (!(context->flags & (CONTEXT_TEMPLATE | CONTEXT_OLD)) &&
 	prefix == context->prefix &&
 	is_same_net6(local, &context->start6, prefix) &&
 	is_same_net6(local, &context->end6, prefix) &&
@@ -568,12 +634,7 @@ static int iface_search(struct in6_addr *local,  int prefix,
 	if (!(flags & IFACE_TENTATIVE))
 	  param->iface = if_index;
 	
-	if (difftime(param->now, context->ra_short_period_start) < 60.0)
+	new_timeout(context, param->now);
-	  /* range 5 - 20 */
-	  context->ra_time = param->now + 5 + (rand16()/4400);
-	else
-	  /* range 3/4 - 1 times RA_INTERVAL */
-	  context->ra_time = param->now + (3 * RA_INTERVAL)/4 + ((RA_INTERVAL * (unsigned int)rand16()) >> 18);
 	
 	/* zero timers for other contexts on the same subnet, so they don't timeout 
 	   independently */
@@ -589,5 +650,14 @@ static int iface_search(struct in6_addr *local,  int prefix,
   return 1; /* keep searching */
 }
  
+static void new_timeout(struct dhcp_context *context, time_t now)
+{
+  if (difftime(now, context->ra_short_period_start) < 60.0)
+    /* range 5 - 20 */
+    context->ra_time = now + 5 + (rand16()/4400);
+  else
+    /* range 3/4 - 1 times RA_INTERVAL */
+    context->ra_time = now + (3 * RA_INTERVAL)/4 + ((RA_INTERVAL * (unsigned int)rand16()) >> 18);
+}
 
 #endif

src/rfc3315.c

@@ -120,7 +120,7 @@ static int dhcp6_maybe_relay(struct in6_addr *link_address, struct dhcp_netid **
 	      !IN6_IS_ADDR_MULTICAST(link_address))
 	    for (c = daemon->dhcp6; c; c = c->next)
 	      if ((c->flags & CONTEXT_DHCP) &&
-		  !(c->flags & CONTEXT_TEMPLATE) &&
+		  !(c->flags & (CONTEXT_TEMPLATE | CONTEXT_OLD)) &&
 		  is_same_net6(link_address, &c->start6, c->prefix) &&
 		  is_same_net6(link_address, &c->end6, c->prefix))
 		{

src/slaac.c

@@ -38,7 +38,9 @@ void slaac_add_addrs(struct dhcp_lease *lease, time_t now, int force)
   lease->slaac_address = NULL;
 
   for (context = daemon->dhcp6; context; context = context->next) 
-    if ((context->flags & CONTEXT_RA_NAME) && lease->last_interface == context->if_index)
+    if ((context->flags & CONTEXT_RA_NAME) && 
+	!(context->flags & CONTEXT_OLD) &&
+	lease->last_interface == context->if_index)
       {
 	struct in6_addr addr = context->start6;
 	if (lease->hwaddr_len == 6 &&
@@ -123,7 +125,7 @@ time_t periodic_slaac(time_t now, struct dhcp_lease *leases)
   time_t next_event = 0;
   
   for (context = daemon->dhcp6; context; context = context->next)
-    if ((context->flags & CONTEXT_RA_NAME))
+    if ((context->flags & CONTEXT_RA_NAME) && !(context->flags & CONTEXT_OLD))
       break;
 
   /* nothing configured */