[Dnsmasq-discuss] [PATCH] Add support for binding to both interface and IP

[Kristian Evensen]

The current --server syntax allows for binding to interface or address. However,
in some (admittedly special) cases it is useful to be able to specify both. This
commit introduces the following syntax to support binding to both interface and
address:

--server X.X.X.X at IP@interface#port

Based on my tests, the syntax is backwards compatible with the current
@IP/interface#port. The code will fail if two interface names are given.

Signed-off-by: Kristian Evensen <kristian.evensen at gmail.com>
---
 src/option.c | 36 ++++++++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/src/option.c b/src/option.c
index d0d9509..bcb19a9 100644
--- a/src/option.c
+++ b/src/option.c
@@ -757,6 +757,7 @@ char *parse_server(char *arg, union mysockaddr *addr, union mysockaddr *source_a
 {
   int source_port = 0, serv_port = NAMESERVER_PORT;
   char *portno, *source;
+  char *interface_opt = NULL;
 #ifdef HAVE_IPV6
   int scope_index = 0;
   char *scope_id;
@@ -782,6 +783,19 @@ char *parse_server(char *arg, union mysockaddr *addr, union mysockaddr *source_a
   scope_id = split_chr(arg, '%');
 #endif
   
+  if (source) {
+    interface_opt = split_chr(source, '@');
+
+    if (interface_opt)
+      {
+#if defined(SO_BINDTODEVICE)
+	strncpy(interface, interface_opt, IF_NAMESIZE - 1);
+#else
+	return _("interface binding not supported");
+#endif
+      }
+  }
+
   if (inet_pton(AF_INET, arg, &addr->in.sin_addr) > 0)
     {
       addr->in.sin_port = htons(serv_port);	
@@ -800,8 +814,15 @@ char *parse_server(char *arg, union mysockaddr *addr, union mysockaddr *source_a
 	  if (!(inet_pton(AF_INET, source, &source_addr->in.sin_addr) > 0))
 	    {
 #if defined(SO_BINDTODEVICE)
-	      source_addr->in.sin_addr.s_addr = INADDR_ANY;
-	      strncpy(interface, source, IF_NAMESIZE - 1);
+	      if (interface_opt)
+		{
+		  return _("interface can only be specified once");
+		}
+	      else 
+		{
+		  source_addr->in.sin_addr.s_addr = INADDR_ANY;
+		  strncpy(interface, source, IF_NAMESIZE - 1);
+		}
 #else
 	      return _("interface binding not supported");
 #endif
@@ -832,8 +853,15 @@ char *parse_server(char *arg, union mysockaddr *addr, union mysockaddr *source_a
 	  if (inet_pton(AF_INET6, source, &source_addr->in6.sin6_addr) == 0)
 	    {
 #if defined(SO_BINDTODEVICE)
-	      source_addr->in6.sin6_addr = in6addr_any; 
-	      strncpy(interface, source, IF_NAMESIZE - 1);
+	      if (interface_opt)
+		{
+		  return _("interface can only be specified once");
+		}
+	      else
+		{
+		  source_addr->in6.sin6_addr = in6addr_any;
+		  strncpy(interface, source, IF_NAMESIZE - 1);
+		}
 #else
 	      return _("interface binding not supported");
 #endif
-- 
2.5.0