multicast tftp: RFC2090

Implemented IETF RFC2090, Multicast TFTP.  Initial implementation
on Realtek RTL8139 and Freescale TSEC.

Signed-off-by: David Updegraff <dave@cray.com>
Signed-off-by: Ben Warren <bwarren@qstreams.com>
diff --git a/net/net.c b/net/net.c
index e9d7757..2b11a13 100644
--- a/net/net.c
+++ b/net/net.c
@@ -118,6 +118,10 @@
 char		NetOurRootPath[64]={0,};	/* Our bootpath			*/
 ushort		NetBootFileSize=0;		/* Our bootfile size in blocks	*/
 
+#ifdef CONFIG_MCAST_TFTP	/* Multicast TFTP */
+IPaddr_t Mcast_addr;
+#endif
+
 /** END OF BOOTP EXTENTIONS **/
 
 ulong		NetBootFileXferSize;	/* The actual transferred size of the bootfile (in bytes) */
@@ -1386,6 +1390,9 @@
 		}
 		tmp = NetReadIP(&ip->ip_dst);
 		if (NetOurIP && tmp != NetOurIP && tmp != 0xFFFFFFFF) {
+#ifdef CONFIG_MCAST_TFTP
+			if (Mcast_addr != tmp) 
+#endif
 			return;
 		}
 		/*
@@ -1492,6 +1499,7 @@
 		}
 #endif
 
+
 #ifdef CONFIG_NETCONSOLE
 		nc_input_packet((uchar *)ip +IP_HDR_SIZE,
 						ntohs(ip->udp_dst),