Make --listen-address work for all 127.0.0.0/8 addresses.

CHANGELOG

@@ -40,7 +40,16 @@ version 2.61
 
 	    Set the environment variable DNSMASQ_LOG_DHCP when running
 	    the script id --log-dhcp is in effect, so that script can
-	    taylor their logging verbosity. Suggestion from Malte Forkel.
+	    taylor their logging verbosity. Suggestion from Malte
+	    Forkel.
+	    
+	    Arrange that addresses specified with --listen-address
+	    work even if there is no interface carrying the
+	    address. This is chiefly useful for IPv4 loopback
+	    addresses, where any address in 127.0.0.0/8 is a valid
+	    loopback address, but normally only 127.0.0.1 appears on
+	    the lo interface. Thanks to Mathieu Trudel-Lapierre for
+	    the idea and initial patch. 
 
  
 version 2.60

src/dnsmasq.c

@@ -209,13 +209,6 @@ int main (int argc, char **argv)
       for (if_tmp = daemon->if_names; if_tmp; if_tmp = if_tmp->next)
 	if (if_tmp->name && !if_tmp->used)
 	  die(_("unknown interface %s"), if_tmp->name, EC_BADNET);
-  
-      for (if_tmp = daemon->if_addrs; if_tmp; if_tmp = if_tmp->next)
-	if (!if_tmp->used)
-	  {
-	    prettyprint_addr(&if_tmp->addr, daemon->namebuff);
-	    die(_("no interface with address %s"), daemon->namebuff, EC_BADNET);
-	  }
     }
   else 
     create_wildcard_listeners();
@@ -1284,18 +1277,19 @@ static void check_dns_listeners(fd_set *set, time_t now)
 	  int confd;
 	  struct irec *iface = NULL;
 	  pid_t p;
+	  union mysockaddr tcp_addr;
+	  socklen_t tcp_len = sizeof(union mysockaddr);
+
+	  while ((confd = accept(listener->tcpfd, NULL, NULL)) == -1 && errno == EINTR);
 	  
-	  while((confd = accept(listener->tcpfd, NULL, NULL)) == -1 && errno == EINTR);
-	  
-	  if (confd == -1)
+	  if (confd == -1 ||
+	      getsockname(confd, (struct sockaddr *)&tcp_addr, &tcp_len) == -1)
 	    continue;
 	  
 	  if (option_bool(OPT_NOWILD))
-	    iface = listener->iface;
+	    iface = listener->iface; /* May be NULL */
 	  else
 	    {
-	      union mysockaddr tcp_addr;
-	      socklen_t tcp_len = sizeof(union mysockaddr);
 	      /* Check for allowed interfaces when binding the wildcard address:
 		 we do this by looking for an interface with the same address as 
 		 the local address of the TCP connection, then looking to see if that's
@@ -1303,14 +1297,13 @@ static void check_dns_listeners(fd_set *set, time_t now)
 		 interface too, for localisation. */
 	      
 	      /* interface may be new since startup */
-	      if (enumerate_interfaces() &&
-		  getsockname(confd, (struct sockaddr *)&tcp_addr, &tcp_len) != -1)
+	      if (enumerate_interfaces())
 		for (iface = daemon->interfaces; iface; iface = iface->next)
 		  if (sockaddr_isequal(&iface->addr, &tcp_addr))
 		    break;
 	    }
 	  
-	  if (!iface)
+	  if (!iface && !option_bool(OPT_NOWILD))
 	    {
 	      shutdown(confd, SHUT_RDWR);
 	      close(confd);
@@ -1336,7 +1329,13 @@ static void check_dns_listeners(fd_set *set, time_t now)
 	      unsigned char *buff;
 	      struct server *s; 
 	      int flags;
-	      
+	      struct in_addr netmask;
+
+	      if (iface)
+		netmask = iface->netmask;
+	      else
+		netmask.s_addr = 0;
+
 #ifndef NO_FORK
 	      /* Arrange for SIGALARM after CHILD_LIFETIME seconds to
 		 terminate the process. */
@@ -1354,7 +1353,7 @@ static void check_dns_listeners(fd_set *set, time_t now)
 	      if ((flags = fcntl(confd, F_GETFL, 0)) != -1)
 		fcntl(confd, F_SETFL, flags & ~O_NONBLOCK);
 	      
-	      buff = tcp_request(confd, now, &iface->addr, iface->netmask);
+	      buff = tcp_request(confd, now, &tcp_addr, netmask);
 	       
 	      shutdown(confd, SHUT_RDWR);
 	      close(confd);

src/dnsmasq.h

@@ -395,7 +395,7 @@ struct irec {
 
 struct listener {
   int fd, tcpfd, tftpfd, family;
-  struct irec *iface; /* only valid for non-wildcard */
+  struct irec *iface; /* only sometimes valid for non-wildcard */
   struct listener *next;
 };
 

src/forward.c

@@ -660,7 +660,7 @@ void receive_query(struct listener *listen, time_t now)
   /* packet buffer overwritten */
   daemon->srv_save = NULL;
   
-  if (listen->family == AF_INET && option_bool(OPT_NOWILD))
+  if (listen->iface && listen->family == AF_INET && option_bool(OPT_NOWILD))
     {
       dst_addr_4 = listen->iface->addr.in.sin_addr;
       netmask = listen->iface->netmask;

src/network.c

@@ -511,6 +511,7 @@ void create_bound_listeners(int dienow)
 {
   struct listener *new;
   struct irec *iface;
+  struct iname *if_tmp;
 
   for (iface = daemon->interfaces; iface; iface = iface->next)
     if (!iface->done && !iface->dad && 
@@ -521,6 +522,25 @@ void create_bound_listeners(int dienow)
 	daemon->listeners = new;
 	iface->done = 1;
       }
+
+  /* Check for --listen-address options that haven't been used because there's
+     no interface with a matching address. These may be valid: eg it's possible
+     to listen on 127.0.1.1 even if the loopback interface is 127.0.0.1
+
+     If the address isn't valid the bind() will fail and we'll die().
+
+     The resulting listeners have the ->iface field NULL, and this has to be
+     handled by the DNS and TFTP code. It disables --localise-queries processing
+     (no netmask) and some MTU login the tftp code. */
+
+  for (if_tmp = daemon->if_addrs; if_tmp; if_tmp = if_tmp->next)
+    if (!if_tmp->used && 
+	(new = create_listeners(&if_tmp->addr, 1, dienow)))
+      {
+	new->iface = NULL;
+	new->next = daemon->listeners;
+	daemon->listeners = new;
+      }
 }
 
 int is_dad_listeners(void)

src/tftp.c

@@ -57,7 +57,7 @@ void tftp_request(struct listener *listen, time_t now)
   int mtuflag = IP_PMTUDISC_DONT;
 #endif
   char namebuff[IF_NAMESIZE];
-  char *name;
+  char *name = NULL;
   char *prefix = daemon->tftp_prefix;
   struct tftp_prefix *pref;
   struct interface_list *ir;
@@ -95,9 +95,20 @@ void tftp_request(struct listener *listen, time_t now)
   
   if (option_bool(OPT_NOWILD))
     {
-      addr = listen->iface->addr;
-      mtu = listen->iface->mtu;
-      name = listen->iface->name;
+      if (listen->iface)
+	{
+	  addr = listen->iface->addr;
+	  mtu = listen->iface->mtu;
+	  name = listen->iface->name;
+	}
+      else
+	{
+	  /* we're listening on an address that doesn't appear on an interface,
+	     ask the kernel what the socket is bound to */
+	  socklen_t tcp_len = sizeof(union mysockaddr);
+	  if (getsockname(listen->tftpfd, (struct sockaddr *)&addr, &tcp_len) == -1)
+	    return;
+	}
     }
   else
     {
@@ -211,15 +222,18 @@ void tftp_request(struct listener *listen, time_t now)
 	mtu = ifr.ifr_mtu;      
     }
   
-  /* check for per-interface prefix */ 
-  for (pref = daemon->if_prefix; pref; pref = pref->next)
-    if (strcmp(pref->interface, name) == 0)
-      prefix = pref->prefix;
-
-  /* wierd TFTP interfaces disable special options. */
-  for (ir = daemon->tftp_interfaces; ir; ir = ir->next)
-    if (strcmp(ir->interface, name) == 0)
-      special = 1;
+  if (name)
+    {
+      /* check for per-interface prefix */ 
+      for (pref = daemon->if_prefix; pref; pref = pref->next)
+	if (strcmp(pref->interface, name) == 0)
+	  prefix = pref->prefix;
+      
+      /* wierd TFTP interfaces disable special options. */
+      for (ir = daemon->tftp_interfaces; ir; ir = ir->next)
+	if (strcmp(ir->interface, name) == 0)
+	  special = 1;
+    }
 
   if (listen->family == AF_INET)
     {