Fix caching bug with negative records.

To provoke this bug, at least the following must be true.

A reply must be a CNAME.
The target of the CNAME must not exist for the queried RR (a No Data reply).
The No Data reply must include an SOA record in the NS section.
The query must take place over TCP.

The result is the caching of a CNAME whose target is the
name of the SOA record, instead of the No data record.

If there is a RR at this target, then a subsequent query for that
RRtype will get a qrong reply.

Thanks to the testers extraordinaire at Pi-Hole for spotting this
and providing enough information to chase it down.

CHANGELOG

@@ -61,6 +61,15 @@ version 2.92
 
 	Add TFTP options windowsize (RFC 7440) and timeout (RFC 2349).
 	
+	Change the behaviour of the DHVPv6 server when a REBIND message
+	is received but no lease exists. Under these circumstances a new
+	lease is created _only_ when the --dhcp-authoritative option is
+	set. This matches the behavior of the DHCPv4 server.
+
+	Add --dhcp-split-relay option. This makes a DHCPv4 relay which
+	is functional when client and server networks aren't mutually
+	route-able.
+
 	
 version 2.91
 	Fix spurious "resource limit exceeded messages". Thanks to 

doc.html

@@ -95,7 +95,5 @@ a contribution towards my expenses, please use the donation button below.
 <input type="image" src="https://www.paypalobjects.com/en_US/GB/i/btn/btn_donateCC_LG.gif" border="0" name="submit" alt="PayPal – The safer, easier way to pay online.">
 <img alt="" border="0" src="https://www.paypalobjects.com/en_GB/i/scr/pixel.gif" width="1" height="1">
 </form>
-
-
 </BODY>
-
+</HTML>

man/dnsmasq.8

@@ -1487,7 +1487,28 @@ DHCPv4 to a DHCPv6 server or vice-versa.
 The DHCP relay function for IPv6 includes the ability to snoop
 prefix-delegation from relayed DHCP transactions. See
 .B --dhcp-script
-for details. 
+for details.
+.TP
+.B --dhcp-split-relay=<local address>,[<server address>[#<server port>]],<server-facing-interface>
+A usefully enchanced version of DHCPv4 relay. IPv4 DHCP normally uses a single address
+for two functions; it is used by the DHCP server to determine which network to allocate
+an address on, and it is used as the address of the relay to which the server sends packets.
+
+This version of DHCP relay splits these functions. It uses the address of the server-facing relay
+interface as the address that the server talks to. The address of the client-facing interface
+(the first item in the config) is used as to determine the client's subnet. The
+local address is also used as server-ID override so that the client always sends requests
+via the relay. The effect of this is that server doesn't require
+a route to the client network and the clients don't require a route to the server.
+
+The interface parameter is mandatory and a cannot be a wildcard.
+
+If setting up a network where the client networks have limited routing, be careful
+about configuring the DHCP server. Dnsmasq, as DHCP server, will set the default route to the
+client-facing relay interface unless explicitly configured: that is a sensible default.
+The normal default DNS server (the same address as the DHCP server)
+will not be appropriate when there is no route bewteen the
+two, so this will have to be explicitly configured. 
 .TP
 .B \-U, --dhcp-vendorclass=set:<tag>,[enterprise:<IANA-enterprise number>,]<vendor-class>
 Map from a vendor-class string to a tag. Most DHCP clients provide a 
@@ -1739,7 +1760,9 @@ For DHCPv4, it changes the behaviour from strict RFC compliance so that DHCP req
 unknown leases from unknown hosts are not ignored. This allows new hosts
 to get a lease without a tedious timeout under all circumstances. It also 
 allows dnsmasq to rebuild its lease database without each client needing to 
-reacquire a lease, if the database is lost. For DHCPv6 it sets the
+reacquire a lease, if the database is lost. For DHCPv6 it controls the same
+behaviour as DHCPv4 with missing leases (except for the RFC uncompliance - the
+DHCPv6 RFCs allow this behaviour if configured). It also sets the
 priority in replies to 255 (the maximum) instead of 0 (the minimum).
 .TP
 .B --dhcp-rapid-commit

setup.html

@@ -229,3 +229,5 @@ contents of the cache to the syslog.
 
 <P>For a complete listing of options please take a look at the manpage
 dnsmasq(8).
+</BODY>
+</HTML>

src/cache.c

@@ -938,15 +938,14 @@ int cache_recv_insert(time_t now, int fd)
 		if (newc)
 		  {
 		    newc->addr.cname.is_name_ptr = 0;
+		    newc->addr.cname.target.cache = crecp;
 		    
-		    if (!crecp)
-		      newc->addr.cname.target.cache = NULL;
-		    else
+		    if (crecp)
 		      {
 			next_uid(crecp);
-			newc->addr.cname.target.cache = crecp;
 			newc->addr.cname.uid = crecp->uid;
 		      }
+		    crecp = newc;
 		  }
 	      }
 	    else

src/dhcp-common.c

@@ -1067,10 +1067,12 @@ void log_relay(int family, struct dhcp_relay *relay)
     {
       if (broadcast)
 	my_syslog(MS_DHCP | LOG_INFO, _("DHCP relay from %s via %s"), daemon->addrbuff, relay->interface);
+      else if (relay->split_mode)
+	my_syslog(MS_DHCP | LOG_INFO, _("DHCP split-relay from %s to %s via %s"), daemon->addrbuff, daemon->namebuff, relay->interface);
       else
 	my_syslog(MS_DHCP | LOG_INFO, _("DHCP relay from %s to %s via %s"), daemon->addrbuff, daemon->namebuff, relay->interface);
     }
-  else
+  else 
     my_syslog(MS_DHCP | LOG_INFO, _("DHCP relay from %s to %s"), daemon->addrbuff, daemon->namebuff);
 }
    

src/dhcp-protocol.h

@@ -73,6 +73,7 @@
 #define SUBOPT_REMOTE_ID         2
 #define SUBOPT_SUBNET_SELECT     5     /* RFC 3527 */
 #define SUBOPT_SUBSCR_ID         6     /* RFC 3393 */
+#define SUBOPT_FLAGS             10    /* RFC 5010 */
 #define SUBOPT_SERVER_OR         11    /* RFC 5107 */
 
 #define SUBOPT_PXE_BOOT_ITEM     71    /* PXE standard */

src/dhcp.c

@@ -32,8 +32,6 @@ static int complete_context(struct in_addr local, int if_index, char *label,
 			    struct in_addr netmask, struct in_addr broadcast, void *vparam);
 static int check_listen_addrs(struct in_addr local, int if_index, char *label,
 			      struct in_addr netmask, struct in_addr broadcast, void *vparam);
-static void relay_upstream4(int iface_index, struct dhcp_packet *mess, size_t sz);
-static struct dhcp_relay *relay_reply4(struct dhcp_packet *mess, char *arrival_interface);
 
 static int make_fd(int port)
 {
@@ -151,6 +149,7 @@ void dhcp_packet(time_t now, int pxe_fd)
 #ifdef HAVE_LINUX_NETWORK
   struct arpreq arp_req;
   struct timeval tv;
+  struct in_addr dst_addr;
 #endif
   
   union {
@@ -176,13 +175,11 @@ void dhcp_packet(time_t now, int pxe_fd)
       (sz < (ssize_t)(sizeof(*mess) - sizeof(mess->options)))) 
     return;
   
-#ifdef HAVE_DUMPFILE
-  dump_packet_udp(DUMP_DHCP, (void *)daemon->dhcp_packet.iov_base, sz, (union mysockaddr *)&dest, NULL, fd);
-#endif
-  
 #if defined (HAVE_LINUX_NETWORK)
   if (ioctl(fd, SIOCGSTAMP, &tv) == 0)
     recvtime = tv.tv_sec;
+
+  dst_addr.s_addr = 0;
   
   if (msg.msg_controllen >= sizeof(struct cmsghdr))
     for (cmptr = CMSG_FIRSTHDR(&msg); cmptr; cmptr = CMSG_NXTHDR(&msg, cmptr))
@@ -194,7 +191,8 @@ void dhcp_packet(time_t now, int pxe_fd)
 	  } p;
 	  p.c = CMSG_DATA(cmptr);
 	  iface_index = p.p->ipi_ifindex;
-	  if (p.p->ipi_addr.s_addr != INADDR_BROADCAST)
+	  dst_addr = p.p->ipi_addr; 
+	  if (dst_addr.s_addr != INADDR_BROADCAST)
 	    unicast_dest = 1;
 	}
 
@@ -224,7 +222,25 @@ void dhcp_packet(time_t now, int pxe_fd)
 	  iface_index = *(p.i);
 	}
 #endif
-	
+
+#ifdef HAVE_DUMPFILE
+  union mysockaddr *sockp = NULL;
+  
+#  ifdef HAVE_LINUX_NETWORK
+  union mysockaddr tosock;
+  
+  sockp = &tosock;
+  tosock.in.sin_port = htons(daemon->dhcp_server_port);
+  tosock.in.sin_addr = dst_addr;
+  tosock.sa.sa_family = AF_INET;
+#    ifdef HAVE_SOCKADDR_SA_LEN
+  tosock.in.sin_len = sizeof(struct sockaddr_in);
+#    endif
+#  endif
+  
+  dump_packet_udp(DUMP_DHCP, (void *)daemon->dhcp_packet.iov_base, sz, (union mysockaddr *)&dest, sockp, -1);
+#endif
+  	
   if (!indextoname(daemon->dhcpfd, iface_index, ifr.ifr_name) ||
       ioctl(daemon->dhcpfd, SIOCGIFFLAGS, &ifr) != 0)
     return;
@@ -344,7 +360,7 @@ void dhcp_packet(time_t now, int pxe_fd)
       if (!iface_enumerate(AF_INET, &parm, (callback_t){.af_inet=complete_context}))
 	return;
 
-      relay_upstream4(iface_index, mess, (size_t)sz);
+      relay_upstream4(iface_index, mess, (size_t)sz, unicast_dest);
        
       /* May have configured relay, but not DHCP server */
       if (!daemon->dhcp)
@@ -1091,122 +1107,4 @@ char *host_from_dns(struct in_addr addr)
   return NULL;
 }
 
-static void relay_upstream4(int iface_index, struct dhcp_packet *mess, size_t sz)
-{
-  struct in_addr giaddr = mess->giaddr;
-  u8 hops = mess->hops;
-  struct dhcp_relay *relay;
-
-  if (mess->op != BOOTREQUEST)
-    return;
-
-  for (relay = daemon->relay4; relay; relay = relay->next)
-    if (relay->iface_index != 0 && relay->iface_index == iface_index)
-      break;
-
-  /* No relay config. */
-  if (!relay)
-    return;
-  
-  for (; relay; relay = relay->next)
-    if (relay->iface_index != 0 && relay->iface_index == iface_index)
-      {
-	union mysockaddr to;
-	union all_addr from;
-
-	mess->hops = hops;
-	mess->giaddr = giaddr;
-	
-	if ((mess->hops++) > 20)
-	  continue;
-	
-	/* source address == relay address */
-	from.addr4 = relay->local.addr4;
-
-	/* already gatewayed ? */
-	if (giaddr.s_addr)
-	  {
-	    /* if so check if by us, to stomp on loops. */
-	    if (giaddr.s_addr == relay->local.addr4.s_addr)
-	      continue;
-	  }
-	else
-	  {
-	    /* plug in our address */
-	    mess->giaddr.s_addr = relay->local.addr4.s_addr;
-	  }
-	
-	to.sa.sa_family = AF_INET;
-	to.in.sin_addr = relay->server.addr4;
-	to.in.sin_port = htons(relay->port);
-#ifdef HAVE_SOCKADDR_SA_LEN
-	to.in.sin_len = sizeof(struct sockaddr_in);
-#endif
-	
-	/* Broadcasting to server. */
-	if (relay->server.addr4.s_addr == 0)
-	  {
-	    struct ifreq ifr;
-	    
-	    if (relay->interface)
-	      safe_strncpy(ifr.ifr_name, relay->interface, IF_NAMESIZE);
-	    
-	    if (!relay->interface || strchr(relay->interface, '*') ||
-		ioctl(daemon->dhcpfd, SIOCGIFBRDADDR, &ifr) == -1)
-	      {
-		my_syslog(MS_DHCP | LOG_ERR, _("Cannot broadcast DHCP relay via interface %s"), relay->interface);
-		continue;
-	      }
-	    
-	    to.in.sin_addr = ((struct sockaddr_in *) &ifr.ifr_addr)->sin_addr;
-	  }
-	
-#ifdef HAVE_DUMPFILE
-	{
-	  union mysockaddr fromsock;
-	  fromsock.in.sin_port = htons(daemon->dhcp_server_port);
-	  fromsock.in.sin_addr = from.addr4;
-	  fromsock.sa.sa_family = AF_INET;
-
-	  dump_packet_udp(DUMP_DHCP, (void *)mess, sz, &fromsock, &to, -1);
-	}
-#endif
-	
-	 send_from(daemon->dhcpfd, 0, (char *)mess, sz, &to, &from, 0);
-	 
-	 if (option_bool(OPT_LOG_OPTS))
-	   {
-	     inet_ntop(AF_INET, &relay->local, daemon->addrbuff, ADDRSTRLEN);
-	     if (relay->server.addr4.s_addr == 0)
-	       snprintf(daemon->dhcp_buff2, DHCP_BUFF_SZ, _("broadcast via %s"), relay->interface);
-	     else
-	       inet_ntop(AF_INET, &relay->server.addr4, daemon->dhcp_buff2, DHCP_BUFF_SZ);
-	     my_syslog(MS_DHCP | LOG_INFO, _("DHCP relay at %s -> %s"), daemon->addrbuff, daemon->dhcp_buff2);
-	   }
-      }
-  
-  /* restore in case of a local reply. */
-  mess->giaddr = giaddr;
-}
-
-
-static struct dhcp_relay *relay_reply4(struct dhcp_packet *mess, char *arrival_interface)
-{
-  struct dhcp_relay *relay;
-
-  if (mess->giaddr.s_addr == 0 || mess->op != BOOTREPLY)
-    return NULL;
-
-  for (relay = daemon->relay4; relay; relay = relay->next)
-    {
-      if (mess->giaddr.s_addr == relay->local.addr4.s_addr)
-	{
-	  if (!relay->interface || wildcard_match(relay->interface, arrival_interface))
-	    return relay->iface_index != 0 ? relay : NULL;
-	}
-    }
-  
-  return NULL;	 
-}     
-
 #endif

src/dhcp6.c

@@ -176,6 +176,7 @@ void dhcp6_packet(time_t now)
   else
     {
       struct dhcp_bridge *bridge, *alias;
+      int multicast_dest = 0;
       
       for (tmp = daemon->if_except; tmp; tmp = tmp->next)
 	if (tmp->name && wildcard_match(tmp->name, ifr.ifr_name))
@@ -231,13 +232,20 @@ void dhcp6_packet(time_t now)
 	    memset(&context->local6, 0, IN6ADDRSZ);
 	  }
       
-      /* Ignore requests sent to the ALL_SERVERS multicast address for relay when
-	 we're listening there for DHCPv6 server reasons. */
-      inet_pton(AF_INET6, ALL_SERVERS, &all_servers);
+      inet_pton(AF_INET6, ALL_RELAY_AGENTS_AND_SERVERS, &all_servers);
+      if (IN6_ARE_ADDR_EQUAL(&dst_addr, &all_servers))
+	multicast_dest = 1;
       
-      if (!IN6_ARE_ADDR_EQUAL(&dst_addr, &all_servers) &&
-	  relay_upstream6(if_index, (size_t)sz, &from.sin6_addr, from.sin6_scope_id, now))
-	return;
+      inet_pton(AF_INET6, ALL_SERVERS, &all_servers);
+      if (IN6_ARE_ADDR_EQUAL(&dst_addr, &all_servers))
+	multicast_dest = 1;
+      else
+	{
+	  /* Ignore requests sent to the ALL_SERVERS multicast address for relay when
+	     we're listening there for DHCPv6 server reasons. */
+	  if (relay_upstream6(if_index, (size_t)sz, &from.sin6_addr, from.sin6_scope_id, now))
+	    return;
+	}
       
       if (!iface_enumerate(AF_INET6, &parm, (callback_t){.af_inet6=complete_context6}))
 	return;
@@ -266,7 +274,7 @@ void dhcp6_packet(time_t now)
       
       lease_prune(NULL, now); /* lose any expired leases */
       
-      port = dhcp6_reply(parm.current, if_index, ifr.ifr_name, &parm.fallback, 
+      port = dhcp6_reply(parm.current, multicast_dest, if_index, ifr.ifr_name, &parm.fallback, 
 			 &parm.ll_addr, &parm.ula_addr, sz, &from.sin6_addr, now);
       
       /* The port in the source address of the original request should

src/dnsmasq.h

@@ -1148,6 +1148,7 @@ struct dhcp_relay {
   char *interface; /* Allowable interface for replies from server, and dest for IPv6 multicast */
   int iface_index; /* working - interface in which requests arrived, for return */
   int port;        /* Port of relay we forward to. */
+  int split_mode;  /* Split address allocation and relay address. */
 #ifdef HAVE_SCRIPT
   struct snoop_record {
     struct in6_addr client, prefix;
@@ -1666,6 +1667,8 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
 		  time_t recvtime, struct in_addr leasequery_source);
 unsigned char *extended_hwaddr(int hwtype, int hwlen, unsigned char *hwaddr, 
 			       int clid_len, unsigned char *clid, int *len_out);
+void relay_upstream4(int iface_index, struct dhcp_packet *mess, size_t sz, int unicast);
+struct dhcp_relay *relay_reply4(struct dhcp_packet *mess, char *arrival_interface);
 #endif
 
 /* dnsmasq.c */
@@ -1801,7 +1804,7 @@ void get_client_mac(struct in6_addr *client, int iface, unsigned char *mac,
   
 /* rfc3315.c */
 #ifdef HAVE_DHCP6
-unsigned short dhcp6_reply(struct dhcp_context *context, int interface, char *iface_name,  
+unsigned short dhcp6_reply(struct dhcp_context *context, int multicast_dest, int interface, char *iface_name,  
 			   struct in6_addr *fallback, struct in6_addr *ll_addr, struct in6_addr *ula_addr,
 			   size_t sz, struct in6_addr *client_addr, time_t now);
 int relay_upstream6(int iface_index, ssize_t sz, struct in6_addr *peer_address, 

src/option.c

@@ -196,6 +196,7 @@ struct myoption {
 #define LOPT_NO_ENCODE     387
 #define LOPT_DO_ENCODE     388
 #define LOPT_LEASEQUERY    389
+#define LOPT_SPLIT_RELAY   390
 
 #ifdef HAVE_GETOPT_LONG
 static const struct option opts[] =  
@@ -374,6 +375,7 @@ static const struct myoption opts[] =
     { "dnssec-timestamp", 1, 0, LOPT_DNSSEC_STAMP },
     { "dnssec-limits", 1, 0, LOPT_DNSSEC_LIMITS },
     { "dhcp-relay", 1, 0, LOPT_RELAY },
+    { "dhcp-split-relay", 1, 0, LOPT_SPLIT_RELAY },
     { "ra-param", 1, 0, LOPT_RA_PARAM },
     { "quiet-dhcp", 0, 0, LOPT_QUIET_DHCP },
     { "quiet-dhcp6", 0, 0, LOPT_QUIET_DHCP6 },
@@ -542,6 +544,7 @@ static struct {
   { LOPT_GEN_NAMES, ARG_DUP, "[=tag:<tag>]", gettext_noop("Generate hostnames based on MAC address for nameless clients."), NULL},
   { LOPT_PROXY, ARG_DUP, "[=<ipaddr>]...", gettext_noop("Use these DHCP relays as full proxies."), NULL },
   { LOPT_RELAY, ARG_DUP, "<local-addr>,<server>[,<iface>]", gettext_noop("Relay DHCP requests to a remote server"), NULL},
+  { LOPT_SPLIT_RELAY, ARG_DUP, "<local-addr>,<server>,<iface>", gettext_noop("Relay DHCP requests to a remote server"), NULL},
   { LOPT_CNAME, ARG_DUP, "<alias>,<target>[,<ttl>]", gettext_noop("Specify alias name for LOCAL DNS name."), NULL },
   { LOPT_PXE_PROMT, ARG_DUP, "<prompt>,[<timeout>]", gettext_noop("Prompt to send to PXE clients."), NULL },
   { LOPT_PXE_SERV, ARG_DUP, "<service>", gettext_noop("Boot service for PXE menu."), NULL },
@@ -4716,11 +4719,21 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
       break;
       
     case LOPT_RELAY: /* --dhcp-relay */
+    case LOPT_SPLIT_RELAY: /* --dhcp-splt-relay */
       {
 	struct dhcp_relay *new = opt_malloc(sizeof(struct dhcp_relay));
 	char *two = split(arg);
 	char *three = split(two);
-	
+
+	if (option == LOPT_SPLIT_RELAY)
+	  {
+	    new->split_mode = 1;
+	    
+	    /* split mode must have two addresses and a non-wildcard interface name. */
+	    if (!three || strchr(three, '*'))
+	      two = NULL;
+	  }
+		    
 	new->iface_index = 0;
 
 	if (two)
@@ -4748,7 +4761,7 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 		daemon->relay4 = new;
 	      }
 #ifdef HAVE_DHCP6
-	    else if (inet_pton(AF_INET6, arg, &new->local))
+	    else if (inet_pton(AF_INET6, arg, &new->local) && !new->split_mode)
 	      {
 		char *hash = split_chr(two, '#');
 
@@ -4769,7 +4782,9 @@ static int one_opt(int option, char *arg, char *errstr, char *gen_err, int comma
 		daemon->relay6 = new;
 	      }
 #endif
-
+	    else
+	      two = NULL;
+	    
 	    new->interface = opt_string_alloc(three);
 	  }
 	

src/rfc1035.c

@@ -516,7 +516,7 @@ int do_doctor(struct dns_header *header, size_t qlen, char *namebuff)
    Cache said SOA and return the difference in length between name and the name of the 
    SOA RR so we can look it up again.
 */
-static int find_soa(struct dns_header *header, size_t qlen, char *name, int *substring, unsigned long *ttlp, int no_cache, time_t now)
+static int find_soa(struct dns_header *header, size_t qlen, char *name, int *substring, unsigned long *ttlp, int cache, time_t now)
 {
   unsigned char *p, *psave;
   int qtype, qclass, rdlen;
@@ -556,7 +556,7 @@ static int find_soa(struct dns_header *header, size_t qlen, char *name, int *sub
 	    {
 	      int prefix = name_len - soa_len;
 	      
-	      if (!no_cache)
+	      if (cache)
 		{
 		  if (!(addr.rrblock.rrdata = blockdata_alloc(NULL, 0)))
 		    return 0;
@@ -568,12 +568,12 @@ static int find_soa(struct dns_header *header, size_t qlen, char *name, int *sub
 		{
 		  if (!extract_name(header, qlen, &p, daemon->workspacename, EXTR_NAME_EXTRACT, 0))
 		    {
-		      if (!no_cache)
+		      if (cache)
 			blockdata_free(addr.rrblock.rrdata);
 		      return 0;
 		    }
 		  
-		  if (!no_cache)
+		  if (cache)
 		    {
 		      len = to_wire(daemon->workspacename);
 		      if (!blockdata_expand(addr.rrblock.rrdata, addr.rrblock.datalen, daemon->workspacename, len))
@@ -588,13 +588,13 @@ static int find_soa(struct dns_header *header, size_t qlen, char *name, int *sub
 
 	      if (!CHECK_LEN(header, p, qlen, 20))
 		{
-		  if (!no_cache)
+		  if (cache)
 		    blockdata_free(addr.rrblock.rrdata);
 		  return 0;
 		}
 	      
 	      /* rest of RR */
-	      if (!no_cache)
+	      if (cache)
 		{
 		  int secflag = 0;
 
@@ -1079,7 +1079,17 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
 	  
 	  if (insert && !option_bool(OPT_NO_NEG))
 	    {
-	      int substring, have_soa = find_soa(header, qlen, name, &substring, &ttl, no_cache_dnssec, now);
+	      /* The order of records going into the cache matters (see  cache_recv_insert()).
+		 The target of a CNAME must immediately follow the CNAME.
+		 (CNAME has already gone into the cache at this point)
+		 Here we call find_soa to get the ttl and substring, but
+		 we DON'T LET IT INSERT the SOA into the cache if our negative record is a CNAME target
+		 so that the SOA doesn't come before the CNAME target.
+
+		 We call find_soa() again after inserting the CNAME target to insert the SOA
+		 if necessary. */
+
+	      int substring, have_soa = find_soa(header, qlen, name, &substring, &ttl, cpp == NULL, now);
 	      
 	      if (have_soa || daemon->neg_ttl)
 		{		  
@@ -1101,6 +1111,10 @@ int extract_addresses(struct dns_header *header, size_t qlen, char *name, time_t
 		      next_uid(newc);
 		      cpp->addr.cname.target.cache = newc;
 		      cpp->addr.cname.uid = newc->uid;
+		    
+		      /* we didn't insert the SOA before a CNAME target above, do it now. */
+		      if (have_soa)
+			find_soa(header, qlen, name, NULL, NULL, 1, now);
 		    }
 		}
 	    }

src/rfc2131.c

@@ -204,6 +204,10 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
 	      memcpy(agent_id, opt, total);
 	    }
 
+	  /* look for RFC5010 flags sub-option */
+	  if ((sopt = option_find1(option_ptr(opt, 0), option_ptr(opt, option_len(opt)), SUBOPT_FLAGS, INADDRSZ)))
+	    unicast_dest = !!(option_uint(opt, 0, 1) & 0x80);
+	      
 	  /* look for RFC3527 Link selection sub-option */
 	  if ((sopt = option_find1(option_ptr(opt, 0), option_ptr(opt, option_len(opt)), SUBOPT_SUBNET_SELECT, INADDRSZ)))
 	    subnet_addr = option_addr(sopt);
@@ -289,6 +293,8 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
 	{
 	  addr = subnet_addr;
 	  force = 1;
+	  if (mess->giaddr.s_addr)
+	    via_relay = 1;
 	}
       else if (mess->giaddr.s_addr)
 	{
@@ -357,7 +363,12 @@ size_t dhcp_reply(struct dhcp_context *context, char *iface_name, int int_index,
 		  if (context_tmp->local.s_addr == 0)
 		    context_tmp->local = fallback;
 		  if (context_tmp->router.s_addr == 0 && !share)
-		    context_tmp->router = mess->giaddr;
+		    {
+		      if (override.s_addr)
+			context_tmp->router = override;
+		      else
+			context_tmp->router = mess->giaddr;
+		    }
 		  
 		  /* fill in missing broadcast addresses for relayed ranges */
 		  if (!(context_tmp->flags & CONTEXT_BRDCAST) && context_tmp->broadcast.s_addr == 0 )
@@ -3044,4 +3055,187 @@ static void apply_delay(u32 xid, time_t recvtime, struct dhcp_netid *netid)
     }
 }
 
+void relay_upstream4(int iface_index, struct dhcp_packet *mess, size_t sz, int unicast)
+{
+  struct in_addr giaddr = mess->giaddr;
+  u8 hops = mess->hops;
+  struct dhcp_relay *relay;
+  size_t orig_sz = sz;
+  unsigned char *endopt = NULL;
+    
+  if (mess->op != BOOTREQUEST)
+    return;
+
+  for (relay = daemon->relay4; relay; relay = relay->next)
+    if (relay->iface_index != 0 && relay->iface_index == iface_index)
+      {
+	union mysockaddr to;
+	union all_addr from;
+	struct ifreq ifr;
+	
+	/* restore orig packet */
+	mess->hops = hops;
+	mess->giaddr = giaddr;
+	if (endopt)
+	  *endopt = OPTION_END;
+	sz = orig_sz;
+	
+	if ((mess->hops++) > 20)
+	  continue;
+
+	if (relay->interface)
+	  {
+	    safe_strncpy(ifr.ifr_name, relay->interface, IF_NAMESIZE);
+	    ifr.ifr_addr.sa_family = AF_INET;
+	  }
+	
+	if (!relay->split_mode)
+	  {
+	    /* already gatewayed ? */
+	    if (giaddr.s_addr)
+	      {
+		/* if so check if by us, to stomp on loops. */
+		if (giaddr.s_addr == relay->local.addr4.s_addr)
+		  continue;
+	      }
+
+	    /* plug in our address */
+	    from.addr4 = mess->giaddr = relay->local.addr4;
+	  }
+	else
+	  {
+	    /* Split mode. We put our address on the server-facing interface
+	       into giaddr for the server to talk back to us on.
+
+	       Our address on client-facing interface goes into agent-id
+	       subnet-selector subopt, so that the server allocates the correct address. */
+	    
+	    /* get our address on the server-facing interface. */
+	    if (ioctl(daemon->dhcpfd, SIOCGIFADDR, &ifr) == -1)
+	      continue;
+	    
+	    /* already gatewayed ? */
+	    if (giaddr.s_addr)
+	      {
+		/* if so check if by us, to stomp on loops. */
+		if (giaddr.s_addr == ((struct sockaddr_in *) &ifr.ifr_addr)->sin_addr.s_addr)
+		  continue;
+	      }
+	    
+	    /* giaddr is our address on the outgoing interface in split mode. */
+	    from.addr4 = mess->giaddr = ((struct sockaddr_in *) &ifr.ifr_addr)->sin_addr;
+	    
+	    if (!endopt)
+	      {
+		/* Add an RFC3026 relay agent information option (2 bytes) at the very end of the options.
+		   Said option to contain a RFC 3527 link selection sub option (6 bytes) and
+		   RFC 5017 serverid-override option (6 bytes) and RFC5010 (3 bytes).
+		   New END option is a 18th byte, so we need 18 bytes free.
+		   We only need to do this once, and poke the address into the same place each time. */
+		
+		if (!(endopt = option_find1((&mess->options[0] + sizeof(u32)), ((unsigned char *)mess) + sz, OPTION_END, 0)) ||
+		    (endopt + 18 > (unsigned char *)(mess + 1)))
+		  continue;
+		
+		endopt[1] = 15; /* length */
+		endopt[2] = SUBOPT_SUBNET_SELECT;
+		endopt[3] = 4; /* length */
+		endopt[8] = SUBOPT_SERVER_OR;
+		endopt[9] = 4;
+		endopt[14] = SUBOPT_FLAGS;
+		endopt[15] = 1; /* length */
+		endopt[17] = OPTION_END;
+		sz = (endopt - (unsigned char *)mess) + 18;
+	      }
+	    
+	    /* IP address is already in network byte order */
+	    memcpy(&endopt[4], &relay->local.addr4.s_addr, INADDRSZ);
+	    memcpy(&endopt[10], &relay->local.addr4.s_addr, INADDRSZ);
+	    endopt[16] = unicast ? 0x80 : 0x00;
+	    endopt[0] = OPTION_AGENT_ID;
+	  }
+	
+	to.sa.sa_family = AF_INET;
+	to.in.sin_addr = relay->server.addr4;
+	to.in.sin_port = htons(relay->port);
+#ifdef HAVE_SOCKADDR_SA_LEN
+	to.in.sin_len = sizeof(struct sockaddr_in);
+#endif
+	
+	/* Broadcasting to server. */
+	if (relay->server.addr4.s_addr == 0)
+	  {
+	    if (!relay->interface || strchr(relay->interface, '*') ||
+		ioctl(daemon->dhcpfd, SIOCGIFBRDADDR, &ifr) == -1)
+	      {
+		my_syslog(MS_DHCP | LOG_ERR, _("Cannot broadcast DHCP relay via interface %s"), relay->interface);
+		continue;
+	      }
+	    
+	    to.in.sin_addr = ((struct sockaddr_in *) &ifr.ifr_addr)->sin_addr;
+	  }
+	
+#ifdef HAVE_DUMPFILE
+	{
+	  union mysockaddr fromsock;
+	  fromsock.in.sin_port = htons(daemon->dhcp_server_port);
+	  fromsock.in.sin_addr = from.addr4;
+	  fromsock.sa.sa_family = AF_INET;
+
+	  dump_packet_udp(DUMP_DHCP, (void *)mess, sz, &fromsock, &to, -1);
+	}
+#endif
+	
+	 send_from(daemon->dhcpfd, 0, (char *)mess, sz, &to, &from, 0);
+	 
+	 if (option_bool(OPT_LOG_OPTS))
+	   {
+	     inet_ntop(AF_INET, &relay->local, daemon->addrbuff, ADDRSTRLEN);
+	     if (relay->server.addr4.s_addr == 0)
+	       snprintf(daemon->dhcp_buff2, DHCP_BUFF_SZ, _("broadcast via %s"), relay->interface);
+	     else
+	       inet_ntop(AF_INET, &relay->server.addr4, daemon->dhcp_buff2, DHCP_BUFF_SZ);
+	     my_syslog(MS_DHCP | LOG_INFO, _("DHCP relay at %s -> %s"), daemon->addrbuff, daemon->dhcp_buff2);
+	   }
+      }
+  
+  /* restore in case of a local reply. */
+  mess->hops = hops;
+  mess->giaddr = giaddr;
+  if (endopt)
+    *endopt = OPTION_END;
+}
+
+struct dhcp_relay *relay_reply4(struct dhcp_packet *mess, char *arrival_interface)
+{
+  struct dhcp_relay *relay;
+
+  if (mess->giaddr.s_addr == 0 || mess->op != BOOTREPLY)
+    return NULL;
+
+  for (relay = daemon->relay4; relay; relay = relay->next)
+    {
+      if (relay->split_mode)
+	{
+	  struct ifreq ifr;
+
+	  safe_strncpy(ifr.ifr_name, arrival_interface, IF_NAMESIZE);
+	  ifr.ifr_addr.sa_family = AF_INET;
+
+	  /* giaddr is our address on the returning interface in split mode. */
+	  if (ioctl(daemon->dhcpfd, SIOCGIFADDR, &ifr) == -1 ||
+	      mess->giaddr.s_addr != ((struct sockaddr_in *) &ifr.ifr_addr)->sin_addr.s_addr)
+	    continue;
+	}
+      else if (mess->giaddr.s_addr != relay->local.addr4.s_addr)
+	continue;
+      
+      if (!relay->interface || wildcard_match(relay->interface, arrival_interface))
+	return relay->iface_index != 0 ? relay : NULL;
+    }
+  
+  return NULL;	 
+}     
+
+
 #endif /* HAVE_DHCP */

src/rfc3315.c

@@ -21,7 +21,7 @@
 
 struct state {
   unsigned char *clid;
-  int clid_len, ia_type, interface, hostname_auth, lease_allocate;
+  int multicast_dest, clid_len, ia_type, interface, hostname_auth, lease_allocate;
   char *client_hostname, *hostname, *domain, *send_domain;
   struct dhcp_context *context;
   struct in6_addr *link_address, *fallback, *ll_addr, *ula_addr;
@@ -68,7 +68,7 @@ static void calculate_times(struct dhcp_context *context, unsigned int *min_time
 #define opt6_user_vendor_next(opt, end) (opt6_next(((uint8_t *) opt) - 2, end))
  
 
-unsigned short dhcp6_reply(struct dhcp_context *context, int interface, char *iface_name,
+unsigned short dhcp6_reply(struct dhcp_context *context, int multicast_dest, int interface, char *iface_name,
 			   struct in6_addr *fallback,  struct in6_addr *ll_addr, struct in6_addr *ula_addr,
 			   size_t sz, struct in6_addr *client_addr, time_t now)
 {
@@ -87,6 +87,7 @@ unsigned short dhcp6_reply(struct dhcp_context *context, int interface, char *if
   
   reset_counter();
   state.context = context;
+  state.multicast_dest = multicast_dest;
   state.interface = interface;
   state.iface_name = iface_name;
   state.fallback = fallback;
@@ -244,7 +245,11 @@ static int dhcp6_maybe_relay(struct state *state, unsigned char *inbuff, size_t
 	      struct in6_addr align;
 	      /* the packet data is unaligned, copy to aligned storage */
 	      memcpy(&align, inbuff + 2, IN6ADDRSZ); 
-	      state->link_address = &align;
+
+
+	      /* RFC6221 para 4 */
+	      if (!IN6_IS_ADDR_UNSPECIFIED(&align))
+		state->link_address = &align;
 	      /* 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(state, opt6_ptr(opt, 0), opt6_len(opt), client_addr, 0, now))
@@ -333,20 +338,24 @@ static int dhcp6_no_relay(struct state *state, int msg_type, unsigned char *inbu
   else if (msg_type != DHCP6IREQ)
     return 0;
 
-  /* server-id must match except for SOLICIT, CONFIRM and REBIND messages, which MUST NOT
-     have a server-id.  3315 para 15.x */
   opt = opt6_find(state->packet_options, state->end, OPTION6_SERVER_ID, 1);
-
-  if (msg_type == DHCP6SOLICIT || msg_type == DHCP6CONFIRM || msg_type == DHCP6REBIND)
+  
+  if (msg_type == DHCP6SOLICIT || msg_type == DHCP6CONFIRM || msg_type == DHCP6REBIND || msg_type == DHCP6IREQ)
     {
-      if (opt)
+      /* Above message types must be multicast 3315 Section 15. */
+      if (!state->multicast_dest)
 	return 0;
-    }
-  else if (msg_type == DHCP6IREQ)
-    {
-      /* If server-id provided, it must match. */
-      if (opt && (opt6_len(opt) != daemon->duid_len ||
-		  memcmp(opt6_ptr(opt, 0), daemon->duid, daemon->duid_len) != 0))
+
+      /* server-id must match except for SOLICIT, CONFIRM and REBIND messages, which MUST NOT
+	 have a server-id.  3315 para 15.x */
+      if (msg_type == DHCP6IREQ)
+	{
+	  /* If server-id provided in IREQ, it must match. */
+	  if (opt && (opt6_len(opt) != daemon->duid_len ||
+		      memcmp(opt6_ptr(opt, 0), daemon->duid, daemon->duid_len) != 0))
+	    return 0;
+	}
+      else if (opt) 
 	return 0;
     }
   else
@@ -634,7 +643,7 @@ static int dhcp6_no_relay(struct state *state, int msg_type, unsigned char *inbu
       
     case DHCP6SOLICIT:
       {
-      	int address_assigned = 0;
+      	int address_assigned;
 	/* tags without all prefix-class tags */
 	struct dhcp_netid *solicit_tags;
 	struct dhcp_context *c;
@@ -653,6 +662,7 @@ static int dhcp6_no_relay(struct state *state, int msg_type, unsigned char *inbu
 
       request_no_address:
 	solicit_tags = tagif;
+	address_assigned = 0;
 	
 	if (ignore)
 	  return 0;
@@ -764,15 +774,6 @@ static int dhcp6_no_relay(struct state *state, int msg_type, unsigned char *inbu
 	    
 	    if (address_assigned != 1)
 	      {
-		/* If the server will not assign any addresses to any IAs in a
-		   subsequent Request from the client, the server MUST send an Advertise
-		   message to the client that doesn't include any IA options. */
-		if (!state->lease_allocate)
-		  {
-		    save_counter(o);
-		    continue;
-		  }
-		
 		/* If the server cannot assign any addresses to an IA in the message
 		   from the client, the server MUST include the IA in the Reply message
 		   with no addresses in the IA and a Status Code option in the IA
@@ -799,7 +800,6 @@ static int dhcp6_no_relay(struct state *state, int msg_type, unsigned char *inbu
 	    o = new_opt6(OPTION6_PREFERENCE);
 	    put_opt6_char(option_bool(OPT_AUTHORITATIVE) ? 255 : 0);
 	    end_opt6(o);
-	    tagif = add_options(state, 0);
 	  }
 	else
 	  { 
@@ -819,7 +819,8 @@ static int dhcp6_no_relay(struct state *state, int msg_type, unsigned char *inbu
 		  break;
 		}
 	  }
-
+	
+	tagif = add_options(state, 0);
 	break;
       }
       
@@ -977,8 +978,10 @@ static int dhcp6_no_relay(struct state *state, int msg_type, unsigned char *inbu
 		  {
 		    if (msg_type == DHCP6REBIND)
 		      {
-			/* When rebinding, we can create a lease if it doesn't exist. */
-			lease = lease6_allocate(&req_addr, state->ia_type == OPTION6_IA_NA ? LEASE_NA : LEASE_TA);
+			/* When rebinding, we can create a lease if it doesn't exist, as long
+			   as --dhcp-authoritative is set. */
+			if (option_bool(OPT_AUTHORITATIVE))
+			  lease = lease6_allocate(&req_addr, state->ia_type == OPTION6_IA_NA ? LEASE_NA : LEASE_TA);
 			if (lease)
 			  lease_set_iaid(lease, state->iaid);
 			else