Minor edits

src/include/gpxe/udp.h

  */
 struct udp_connection {
        /** Address of the remote end of the connection */
-	struct sockaddr sin;
+	struct sockaddr sa;
 	/** Local port on which the connection receives packets */
 	port_t local_port;
 	/** Transmit buffer */

src/net/udp.c

  * This function stores the socket address within the connection
  */
 void udp_connect ( struct udp_connection *conn, struct sockaddr *peer ) {
-	copy_sockaddr ( peer, &conn->sin );
+	copy_sockaddr ( peer, &conn->sa );
 
 	/* Not sure if this should add the connection to udp_conns; If it does,
 	 * uncomment the following code
 	udphdr->dest_port = *dest;
 	udphdr->source_port = conn->local_port;
 	udphdr->len = htons ( pkb_len ( conn->tx_pkb ) );
-	udphdr->chksum = htons ( calc_chksum ( udphdr, sizeof ( *udphdr ) ) );
+	/**
+	 * Calculate the partial checksum. Note this is stored in host byte
+	 * order.
+	 */
+	udphdr->chksum = calc_chksum ( udphdr, sizeof ( *udphdr ) + len );
 
+	/**
+	 * Dump the contents of the UDP header
+	 */
 	udp_dump ( udphdr );
 
 	/* Send it to the next layer for processing */
  * @v len       Length of data
  */
 int udp_send ( struct udp_connection *conn, const void *data, size_t len ) {
-	return udp_sendto ( conn, &conn->sin, data, len );
+	return udp_sendto ( conn, &conn->sa, data, len );
 }
 
 /**