bootp: Prevent u-boot from using others responses.

In rare circumstances two dhcp clients may generate the same
bootp ID. If this happens it is vital that the client also checks
the hw address in the received response to prevent IP address conflicts.

Signed-off-by: Anton Persson <don.juanton@gmail.com>
diff --git a/net/bootp.c b/net/bootp.c
index aefc808..d7852db 100644
--- a/net/bootp.c
+++ b/net/bootp.c
@@ -132,6 +132,8 @@
 		retval = -5;
 	else if (!bootp_match_id(net_read_u32(&bp->bp_id)))
 		retval = -6;
+	else if (memcmp(bp->bp_chaddr, net_ethaddr, HWL_ETHER) != 0)
+		retval = -7;
 
 	debug("Filtering pkt = %d\n", retval);