[tcpip] Allow for transmission to multicast IPv4 addresses

When sending to a multicast address, it may be necessary to specify
the source address explicitly, since the multicast destination address
does not provide enough information to deduce the source address via
the miniroute table.

Allow the source address specified via the data-xfer metadata to be
passed down through the TCP/IP stack to the IPv4 layer, which can use
it as a default source address.

1 files changed, 8 insertions, 11 deletions

diff --git a/src/net/udp.c b/src/net/udp.c
index fddf81df..63c2d9ee 100644
--- a/src/net/udp.c
+++ b/src/net/udp.c
@@ -182,13 +182,13 @@ static void udp_close ( struct udp_connection *udp, int rc ) {
  *
  * @v udp		UDP connection
  * @v iobuf		I/O buffer
- * @v src_port		Source port, or 0 to use default
+ * @v src		Source address, or NULL to use default
  * @v dest		Destination address, or NULL to use default
  * @v netdev		Network device, or NULL to use default
  * @ret rc		Return status code
  */
 static int udp_tx ( struct udp_connection *udp, struct io_buffer *iobuf,
-		    unsigned int src_port, struct sockaddr_tcpip *dest,
+		    struct sockaddr_tcpip *src, struct sockaddr_tcpip *dest,
 		    struct net_device *netdev ) {
        	struct udp_header *udphdr;
 	size_t len;
@@ -201,8 +201,8 @@ static int udp_tx ( struct udp_connection *udp, struct io_buffer *iobuf,
 	}
 
 	/* Fill in default values if not explicitly provided */
-	if ( ! src_port )
-		src_port = udp->local.st_port;
+	if ( ! src )
+		src = &udp->local;
 	if ( ! dest )
 		dest = &udp->peer;
 
@@ -210,7 +210,7 @@ static int udp_tx ( struct udp_connection *udp, struct io_buffer *iobuf,
 	udphdr = iob_push ( iobuf, sizeof ( *udphdr ) );
 	len = iob_len ( iobuf );
 	udphdr->dest = dest->st_port;
-	udphdr->src = src_port;
+	udphdr->src = src->st_port;
 	udphdr->len = htons ( len );
 	udphdr->chksum = 0;
 	udphdr->chksum = tcpip_chksum ( udphdr, len );
@@ -221,7 +221,7 @@ static int udp_tx ( struct udp_connection *udp, struct io_buffer *iobuf,
 	       ntohs ( udphdr->len ) );
 
 	/* Send it to the next layer for processing */
-	if ( ( rc = tcpip_tx ( iobuf, &udp_protocol, dest, netdev,
+	if ( ( rc = tcpip_tx ( iobuf, &udp_protocol, src, dest, netdev,
 			       &udphdr->chksum ) ) != 0 ) {
 		DBGC ( udp, "UDP %p could not transmit packet: %s\n",
 		       udp, strerror ( rc ) );
@@ -399,22 +399,19 @@ static int udp_xfer_deliver_iob ( struct xfer_interface *xfer,
 				  struct xfer_metadata *meta ) {
 	struct udp_connection *udp =
 		container_of ( xfer, struct udp_connection, xfer );
-	struct sockaddr_tcpip *src;
+	struct sockaddr_tcpip *src = NULL;
 	struct sockaddr_tcpip *dest = NULL;
 	struct net_device *netdev = NULL;
-	unsigned int src_port = 0;
 
 	/* Apply xfer metadata */
 	if ( meta ) {
 		src = ( struct sockaddr_tcpip * ) meta->src;
-		if ( src )
-			src_port = src->st_port;
 		dest = ( struct sockaddr_tcpip * ) meta->dest;
 		netdev = meta->netdev;
 	}
 
 	/* Transmit data, if possible */
-	udp_tx ( udp, iobuf, src_port, dest, netdev );
+	udp_tx ( udp, iobuf, src, dest, netdev );
 
 	return 0;
 }