Add snooping of DHCPv6 prefix delegation to the DHCP-relay function.dhcpv6-snoop

8 files changed, 175 insertions, 13 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 4a012de..aabeb5a 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -19,6 +19,8 @@ version 2.87
 	now supported for both IPv4 and IPv6 and the configuration
 	syntax made easier (but backwards compatible).
 	
+	Add snooping of IPv6 prefix-delegations to the DHCP-relay system.
+
 	
 version 2.86
 	Handle DHCPREBIND requests in the DHCPv6 server code.
diff --git a/man/dnsmasq.8 b/man/dnsmasq.8
index 8bdcaa3..4de8969 100644
--- a/man/dnsmasq.8
+++ b/man/dnsmasq.8
@@ -1356,6 +1356,11 @@ supported: the relay function will take precedence.
 
 Both DHCPv4 and DHCPv6 relay is supported. It's not possible to relay
 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. 
 .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 
@@ -1766,15 +1771,25 @@ receives a HUP signal, the script will be invoked for existing leases
 with an "old" event.
 
 
-There are four further actions which may appear as the first argument
-to the script, "init", "arp-add", "arp-del" and "tftp". More may be added in the future, so
+There are five further actions which may appear as the first argument
+to the script, "init", "arp-add", "arp-del", "relay-snoop" and "tftp".
+More may be added in the future, so
 scripts should be written to ignore unknown actions. "init" is
 described below in 
 .B --leasefile-ro
+
 The "tftp" action is invoked when a TFTP file transfer completes: the
 arguments are the file size in bytes, the address to which the file
 was sent, and the complete pathname of the file.
- 
+
+The "relay-snoop" action is invoked when dnsmasq is configured as a DHCP
+relay for DHCPv6 and it relays a prefx delegation to a client. The arguments
+are the name of the interface where the client is conected, its (link-local)
+address on that interface and the delegated prefix. This information is
+sufficient to install routes to the delegated prefix of a router. See
+.B --dhcp-relay
+for more details on configuring DHCP relay.
+
 The "arp-add" and "arp-del" actions are only called if enabled with
 .B --script-arp
 They are are supplied with a MAC address and IP address as arguments. "arp-add" indicates
diff --git a/src/dhcp6-protocol.h b/src/dhcp6-protocol.h
index ebe8dfd..f1d0991 100644
--- a/src/dhcp6-protocol.h
+++ b/src/dhcp6-protocol.h
@@ -55,6 +55,8 @@
 #define OPTION6_RECONF_ACCEPT   20
 #define OPTION6_DNS_SERVER      23
 #define OPTION6_DOMAIN_SEARCH   24
+#define OPTION6_IA_PD           25
+#define OPTION6_IAPREFIX        26
 #define OPTION6_REFRESH_TIME    32
 #define OPTION6_REMOTE_ID       37
 #define OPTION6_SUBSCRIBER_ID   38
diff --git a/src/dhcp6.c b/src/dhcp6.c
index ae1f5c1..c061879 100644
--- a/src/dhcp6.c
+++ b/src/dhcp6.c
@@ -135,9 +135,8 @@ void dhcp6_packet(time_t now)
   if (!indextoname(daemon->dhcp6fd, if_index, ifr.ifr_name))
     return;
 
-  if ((port = relay_reply6(&from, sz, ifr.ifr_name)) != 0)
+  if (relay_reply6(&from, sz, ifr.ifr_name))
     {
-      from.sin6_port = htons(port);
       while (retry_send(sendto(daemon->dhcp6fd, daemon->outpacket.iov_base, 
 			       save_counter(-1), 0, (struct sockaddr *)&from, 
 			       sizeof(from))));
diff --git a/src/dnsmasq.c b/src/dnsmasq.c
index 2fe9808..422e40f 100644
--- a/src/dnsmasq.c
+++ b/src/dnsmasq.c
@@ -734,7 +734,11 @@ int main (int argc, char **argv)
    /* if we are to run scripts, we need to fork a helper before dropping root. */
   daemon->helperfd = -1;
 #ifdef HAVE_SCRIPT 
-  if ((daemon->dhcp || daemon->dhcp6 || option_bool(OPT_TFTP) || option_bool(OPT_SCRIPT_ARP)) && 
+  if ((daemon->dhcp ||
+       daemon->dhcp6 ||
+       daemon->relay6 ||
+       option_bool(OPT_TFTP) ||
+       option_bool(OPT_SCRIPT_ARP)) && 
       (daemon->lease_change_command || daemon->luascript))
       daemon->helperfd = create_helper(pipewrite, err_pipe[1], script_uid, script_gid, max_fd);
 #endif
@@ -1139,6 +1143,10 @@ int main (int argc, char **argv)
       while (helper_buf_empty() && do_tftp_script_run());
 #    endif
 
+#    ifdef HAVE_DHCP6
+      while (helper_buf_empty() && do_snoop_script_run());
+#    endif
+      
       if (!helper_buf_empty())
 	poll_listen(daemon->helperfd, POLLOUT);
 #else
@@ -1153,6 +1161,11 @@ int main (int argc, char **argv)
       while (do_tftp_script_run());
 #    endif
 
+#    ifdef HAVE_DHCP6
+      while (helper_buf_empty() && do_snoop_script_run());
+#    endif
+      
+
 #endif
 
    
diff --git a/src/dnsmasq.h b/src/dnsmasq.h
index 05c1743..ba09bd0 100644
--- a/src/dnsmasq.h
+++ b/src/dnsmasq.h
@@ -778,6 +778,7 @@ struct frec {
 #define ACTION_TFTP          5
 #define ACTION_ARP           6
 #define ACTION_ARP_DEL       7
+#define ACTION_RELAY_SNOOP   8
 
 #define LEASE_NEW            1  /* newly created */
 #define LEASE_CHANGED        2  /* modified */
@@ -1076,6 +1077,13 @@ struct dhcp_relay {
   union all_addr local, server;
   char *interface; /* Allowable interface for replies from server, and dest for IPv6 multicast */
   int iface_index; /* working - interface in which requests arrived, for return */
+#ifdef HAVE_SCRIPT
+  struct snoop_record {
+    struct in6_addr client, prefix;
+    int prefix_len;
+    struct snoop_record *next;
+  } *snoop_records;
+#endif
   struct dhcp_relay *current, *next;
 };
 
@@ -1227,13 +1235,18 @@ extern struct daemon {
   unsigned char *duid;
   struct iovec outpacket;
   int dhcp6fd, icmp6fd;
+#  ifdef HAVE_SCRIPT
+  struct snoop_record *free_snoops;
+#  endif
 #endif
+  
   /* DBus stuff */
   /* void * here to avoid depending on dbus headers outside dbus.c */
   void *dbus;
 #ifdef HAVE_DBUS
   struct watch *watches;
 #endif
+
   /* UBus stuff */
 #ifdef HAVE_UBUS
   /* void * here to avoid depending on ubus headers outside ubus.c */
@@ -1619,6 +1632,9 @@ void queue_tftp(off_t file_len, char *filename, union mysockaddr *peer);
 void queue_arp(int action, unsigned char *mac, int maclen,
 	       int family, union all_addr *addr);
 int helper_buf_empty(void);
+#ifdef HAVE_DHCP6
+void queue_relay_snoop(struct in6_addr *client, int if_index, struct in6_addr *prefix, int prefix_len);
+#endif
 #endif
 
 /* tftp.c */
@@ -1664,7 +1680,8 @@ unsigned short dhcp6_reply(struct dhcp_context *context, int interface, char *if
 void relay_upstream6(struct dhcp_relay *relay, ssize_t sz, struct in6_addr *peer_address, 
 		     u32 scope_id, time_t now);
 
-unsigned short relay_reply6( struct sockaddr_in6 *peer, ssize_t sz, char *arrival_interface);
+int relay_reply6( struct sockaddr_in6 *peer, ssize_t sz, char *arrival_interface);
+int do_snoop_script_run(void);
 #endif
 
 /* dhcp-common.c */
diff --git a/src/helper.c b/src/helper.c
index 455a68c..d7c7dbd 100644
--- a/src/helper.c
+++ b/src/helper.c
@@ -233,8 +233,13 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
 	  is6 = (data.flags != AF_INET);
 	  data.action = ACTION_ARP;
 	}
-       else 
-	continue;
+       else if (data.action == ACTION_RELAY_SNOOP)
+	 {
+	   is6 = 1;
+	   action_str = "relay-snoop";
+	 }
+       else
+	 continue;
       	
       /* stringify MAC into dhcp_buff */
       p = daemon->dhcp_buff;
@@ -286,7 +291,7 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
 	  char *dot;
 	  hostname = (char *)buf;
 	  hostname[data.hostname_len - 1] = 0;
-	  if (data.action != ACTION_TFTP)
+	  if (data.action != ACTION_TFTP && data.action != ACTION_RELAY_SNOOP)
 	    {
 	      if (!legal_hostname(hostname))
 		hostname = NULL;
@@ -332,6 +337,24 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
 		  lua_call(lua, 2, 0);	/* pass 2 values, expect 0 */
 		}
 	    }
+	  else if (data.action == ACTION_RELAY_SNOOP)
+	    {
+	      lua_getglobal(lua, "snoop"); 
+	      if (lua_type(lua, -1) != LUA_TFUNCTION)
+		lua_pop(lua, 1); /* tftp function optional */
+	      else
+		{
+		  lua_pushstring(lua, action_str); /* arg1 - action */
+		  lua_newtable(lua);               /* arg2 - data table */
+		  lua_pushstring(lua, daemon->addrbuff);
+		  lua_setfield(lua, -2, "client_address");
+		  lua_pushstring(lua, hostname);
+		  lua_setfield(lua, -2, "prefix"); 
+		  lua_pushstring(lua, data.interface);
+		  lua_setfield(lua, -2, "client_interface");
+		  lua_call(lua, 2, 0);	/* pass 2 values, expect 0 */
+		}
+	    }
 	  else if (data.action == ACTION_ARP)
 	    {
 	      lua_getglobal(lua, "arp"); 
@@ -553,7 +576,7 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
 	  close(pipeout[1]);
 	}
       
-      if (data.action != ACTION_TFTP && data.action != ACTION_ARP)
+      if (data.action != ACTION_TFTP && data.action != ACTION_ARP && data.action != ACTION_RELAY_SNOOP)
 	{
 #ifdef HAVE_DHCP6
 	  my_setenv("DNSMASQ_IAID", is6 ? daemon->dhcp_buff3 : NULL, &err);
@@ -640,6 +663,9 @@ int create_helper(int event_fd, int err_fd, uid_t uid, gid_t gid, long max_fd)
 	fcntl(event_fd, F_SETFD, i | FD_CLOEXEC);
       close(pipefd[0]);
 
+      if (data.action == ACTION_RELAY_SNOOP)
+	strcpy(daemon->packet, data.interface);
+      
       p =  strrchr(daemon->lease_change_command, '/');
       if (err == 0)
 	{
@@ -810,6 +836,29 @@ void queue_script(int action, struct dhcp_lease *lease, char *hostname, time_t n
   bytes_in_buf = p - (unsigned char *)buf;
 }
 
+#ifdef HAVE_DHCP6
+void queue_relay_snoop(struct in6_addr *client, int if_index, struct in6_addr *prefix, int prefix_len)
+{
+  /* no script */
+  if (daemon->helperfd == -1)
+    return;
+  
+  inet_ntop(AF_INET6, prefix, daemon->addrbuff, ADDRSTRLEN);
+
+  /* 5 for /nnn and zero on the end of the prefix. */
+  buff_alloc(sizeof(struct script_data) + ADDRSTRLEN + 5);
+  memset(buf, 0, sizeof(struct script_data));
+
+  buf->action = ACTION_RELAY_SNOOP;
+  buf->addr6 = *client;
+  buf->hostname_len = sprintf((char *)(buf+1), "%s/%u", daemon->addrbuff, prefix_len) + 1;
+  
+  indextoname(daemon->dhcp6fd, if_index, buf->interface);
+
+  bytes_in_buf = sizeof(struct script_data) + buf->hostname_len;
+}
+#endif
+
 #ifdef HAVE_TFTP
 /* This nastily re-uses DHCP-fields for TFTP stuff */
 void queue_tftp(off_t file_len, char *filename, union mysockaddr *peer)
diff --git a/src/rfc3315.c b/src/rfc3315.c
index f54fb78..fb387a4 100644
--- a/src/rfc3315.c
+++ b/src/rfc3315.c
@@ -2194,7 +2194,7 @@ void relay_upstream6(struct dhcp_relay *relay, ssize_t sz,
     }
 }
 
-unsigned short relay_reply6(struct sockaddr_in6 *peer, ssize_t sz, char *arrival_interface)
+int relay_reply6(struct sockaddr_in6 *peer, ssize_t sz, char *arrival_interface)
 {
   struct dhcp_relay *relay;
   struct in6_addr link;
@@ -2226,10 +2226,75 @@ unsigned short relay_reply6(struct sockaddr_in6 *peer, ssize_t sz, char *arrival
 	    put_opt6(opt6_ptr(opt, 0), opt6_len(opt));
 	    memcpy(&peer->sin6_addr, &inbuff[18], IN6ADDRSZ); 
 	    peer->sin6_scope_id = relay->iface_index;
-	    return encap_type == DHCP6RELAYREPL ? DHCPV6_SERVER_PORT : DHCPV6_CLIENT_PORT;
+
+	    if (encap_type == DHCP6RELAYREPL)
+	      {
+		peer->sin6_port = ntohs(DHCPV6_SERVER_PORT);
+		return 1;
+	      }
+
+	    peer->sin6_port = ntohs(DHCPV6_CLIENT_PORT);
+	    
+#ifdef HAVE_SCRIPT
+	    if (daemon->lease_change_command && encap_type == DHCP6REPLY)
+	      {
+		/* decapsulate relayed message */
+		opts = opt6_ptr(opt, 4);
+		end = opt6_ptr(opt, opt6_len(opt));
+
+		for (opt = opts; opt; opt = opt6_next(opt, end))
+		  if (opt6_type(opt) == OPTION6_IA_PD && opt6_len(opt) > 12) 
+		    {
+		      void *ia_opts = opt6_ptr(opt, 12);
+		      void *ia_end = opt6_ptr(opt, opt6_len(opt));
+		      void *ia_opt;
+		      
+		      for (ia_opt = ia_opts; ia_opt; ia_opt = opt6_next(ia_opt, ia_end))
+			/* valid lifetime must not be zero. */
+			if (opt6_type(ia_opt) == OPTION6_IAPREFIX && opt6_len(ia_opt) >= 25 && opt6_uint(ia_opt, 4, 4) != 0)
+			  {
+			    if (daemon->free_snoops ||
+				(daemon->free_snoops = whine_malloc(sizeof(struct snoop_record))))
+			      {
+				struct snoop_record *snoop = daemon->free_snoops;
+				
+				daemon->free_snoops = snoop->next;
+				snoop->client = peer->sin6_addr;
+				snoop->prefix_len = opt6_uint(ia_opt, 8, 1); 
+				memcpy(&snoop->prefix, opt6_ptr(ia_opt, 9), IN6ADDRSZ); 
+				snoop->next = relay->snoop_records;
+				relay->snoop_records = snoop;
+			      }
+			  }
+		    }
+	      }
+#endif		
+	    return 1;
 	  }
+      
     }
+  
+  return 0;
+}
 
+int do_snoop_script_run(void)
+{
+#ifdef HAVE_SCRIPT
+  struct dhcp_relay *relay;
+  struct snoop_record *snoop;
+  
+  for (relay = daemon->relay6; relay; relay = relay->next)
+    if ((snoop = relay->snoop_records))
+      {
+	relay->snoop_records = snoop->next;
+	snoop->next = daemon->free_snoops;
+	daemon->free_snoops = snoop;
+	
+	queue_relay_snoop(&snoop->client, relay->iface_index, &snoop->prefix, snoop->prefix_len);
+	return 1;
+      }
+#endif
+  
   return 0;
 }