From 58fae14ef2dfab7eb3330475c8f20f79af76c4c4 Mon Sep 17 00:00:00 2001
From: Jeremy Lakeman <Jeremy.Lakeman@gmail.com>
Date: Tue, 11 Sep 2012 15:20:44 +0930
Subject: [PATCH] Bind to interface address so unicast packets can be received
 & always bind to INADDR_ANY

---
 overlay_interface.c | 34 +++++++++++++++-------------------
 overlay_olsr.c      |  9 ++++-----
 2 files changed, 19 insertions(+), 24 deletions(-)

diff --git a/overlay_interface.c b/overlay_interface.c
index a7dbeba0..1f28cd38 100644
--- a/overlay_interface.c
+++ b/overlay_interface.c
@@ -356,24 +356,22 @@ overlay_interface_init_socket(int interface_index)
   overlay_interface *const interface = &overlay_interfaces[interface_index];
   interface->fileP = 0;
 
-#ifdef __APPLE__
   /*
-  On OSX and probably windows you can't bind to a broadcast address.
-   */
-  const struct sockaddr *addr = (const struct sockaddr *)&interface->address;
-
-  /* On osx, UDP sockets bound to a specific interface can send broadcast packets just fine, 
-   but can't receive broadcast packets
-   So we need a socket bound to INADDR_ANY for receiving them.
+   On linux you can bind to the broadcast address to receive broadcast packets per interface [or subnet],
+   but then you can't receive unicast packets on the same socket.
+   
+   On osx, you can only receive broadcast packets if you bind to INADDR_ANY.
+   
+   So the most portable way to do this is to bind to each interface's IP address for sending broadcasts 
+   and receiving unicasts, and bind a separate socket to INADDR_ANY just for receiving broadcast packets.
+   
+   Sending packets from INADDR_ANY would probably work, but gives us less control over which interfaces are sending packets.
+   But there may be some platforms that need some other combination for everything to work.
    */
+  
   overlay_interface_init_any(interface->port);
-#else
-  /*
-   Bind to the broadcast address, so that we can reliably receive broadcast 
-   traffic on linux platforms. 
-   */
-  const struct sockaddr *addr = (const struct sockaddr *)&interface->broadcast_address;
-#endif
+  
+  const struct sockaddr *addr = (const struct sockaddr *)&interface->address;
   
   interface->alarm.poll.fd = overlay_bind_socket(addr, sizeof(interface->broadcast_address), interface->name);
   if (interface->alarm.poll.fd<0){
@@ -718,7 +716,8 @@ overlay_broadcast_ensemble(int interface_number,
     }
   else
     {
-      DEBUGF("Sending overlay frame on %s to %s",interface->name,inet_ntoa(recipientaddr->sin_addr));
+      if (debug&DEBUG_OVERLAYINTERFACES) 
+	DEBUGF("Sending %d byte overlay frame on %s to %s",len,interface->name,inet_ntoa(recipientaddr->sin_addr));
       if(sendto(interface->alarm.poll.fd, 
 		bytes, len, 0, (struct sockaddr *)recipientaddr, sizeof(struct sockaddr_in)) != len){
 	WHY_perror("sendto(c)");
@@ -1147,9 +1146,6 @@ overlay_fill_send_packet(struct outgoing_packet *packet, time_ms_t now) {
       if (debug&DEBUG_PACKETCONSTRUCTION)
 	dump("assembled packet",&packet->buffer->bytes[0],packet->buffer->position);
       
-      if (debug&DEBUG_OVERLAYINTERFACES) 
-	DEBUGF("Sending %d byte packet",packet->buffer->position);
-      
       overlay_broadcast_ensemble(packet->i, &packet->dest, packet->buffer->bytes, packet->buffer->position);
     }
     ob_free(packet->buffer);
diff --git a/overlay_olsr.c b/overlay_olsr.c
index 9424690b..1f4ce8ee 100644
--- a/overlay_olsr.c
+++ b/overlay_olsr.c
@@ -151,8 +151,8 @@ static void parse_frame(struct overlay_buffer *buff){
   
   frame.modifiers=ob_get(buff);
   
-//  dump("received headers", buff->bytes, buff->position);
-//  dump("received payload", buff->bytes+buff->position, buff->sizeLimit - buff->position);
+  if (debug&DEBUG_OVERLAYINTERFACES) 
+    DEBUGF("Received %d byte payload via olsr", buff->sizeLimit - buff->position);
   
   // the remaining bytes are an mdp payload, process it
   frame.payload = buff;
@@ -218,7 +218,6 @@ static int send_packet(unsigned char *header, int header_len, unsigned char *pay
     .msg_iovlen=2,
   };
   
-  DEBUGF("Sending broadcast via olsr");
   if (sendmsg(read_watch.poll.fd, &msg, 0)<0){
     return WHY_perror("Sending packet");
   }
@@ -240,8 +239,8 @@ int olsr_send(struct overlay_frame *frame){
   overlay_broadcast_append(b, &frame->broadcast_id);
   ob_append_byte(b, frame->modifiers);
   
-//  dump("sent headers", b->bytes, b->position);
-//  dump("sent payload", frame->payload->bytes, frame->payload->sizeLimit);
+  if (debug&DEBUG_OVERLAYINTERFACES) 
+    DEBUGF("Sending %d byte payload via olsr", frame->payload->sizeLimit);
   
   // send the packet
   int ret = send_packet(b->bytes, b->position, frame->payload->bytes, frame->payload->sizeLimit);