The following edits were made: \

1. Updated UDP send data code\
2. Corrected internet checksum\
3. Moved udp_buffer() and udp_buflen() to udp.c from udp.h

src/include/gpxe/tcpip_if.h

@@ -83,7 +83,7 @@ extern void trans_rx ( struct pk_buff *pkb, uint8_t trans_proto,
 extern int trans_tx ( struct pk_buff *pkb, struct tcpip_protocol *tcpip, 
 		      struct sockaddr *dest );
 
-extern uint16_t calc_chksum ( void *data, size_t len );
+extern uint16_t calc_chksum ( void *b, int len );
 
 extern struct tcpip_protocol * find_tcpip_protocol ( uint8_t trans_proto );
 extern struct tcpip_net_protocol * find_tcpip_net_protocol ( sa_family_t sa_family );

src/include/gpxe/udp.h

@@ -41,6 +41,23 @@ struct udp_connection;
  *
  */
 struct udp_operations {
+	
+	/**
+	 * Transmit data
+	 *
+	 * @v conn	UDP connection
+	 * @v buf	Temporary data buffer
+	 * @v len	Length of temporary data buffer
+	 *
+	 * The application may use the temporary data buffer to
+	 * construct the data to be sent.  Note that merely filling
+	 * the buffer will do nothing; the application must call
+	 * udp_send() in order to actually transmit the data.  Use of
+	 * the buffer is not compulsory; the application may call
+	 * udp_send() on any block of data.
+	 */
+	void ( * senddata ) ( struct tcp_connection *conn, void *buf,
+			      size_t len );
 	/**
 	 * New data received
 	 *
@@ -69,11 +86,6 @@ struct udp_connection {
 	struct udp_operations *udp_op;
 };
 
-/**
- * List of registered UDP connections
- */
-static LIST_HEAD ( udp_conns );
-
 /**
  * UDP protocol
  */