From 44c42dd40eb58679419abb8ab5f20fb5bff26eac Mon Sep 17 00:00:00 2001
From: Peng Fan <peng.fan@nxp.com>
Date: Thu, 7 Jan 2016 15:28:23 +0800
Subject: net: bootp: Ignore packets whose yiaddr is 0

When doing `dhcp`, there is a bad dhcp server in my network
which always reply dhcp request with yiaddr 0, which cause
uboot can not successfully get ipaddr from the good dhcp server.
But the Linux PC can get the ip address even if there is a bad
dhcp server. This patch is to fix that even if there is a bad
dhcp server, uboot can still get ipaddr and tftp work ok.

The way is to ignore the packets from the bad dhcp server by filtering
out the yiaddr whose value is 0.

Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: Joe Hershberger <joe.hershberger@ni.com>
Reviewed-by: Wolfgang Denk <wd@denx.de>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

diff --git a/net/bootp.c b/net/bootp.c
index 8aeddb0..8da2e9b 100644
--- a/net/bootp.c
+++ b/net/bootp.c
@@ -995,6 +995,9 @@ static void dhcp_handler(uchar *pkt, unsigned dest, struct in_addr sip,
 	debug("DHCPHandler: got DHCP packet: (src=%d, dst=%d, len=%d) state: "
 	      "%d\n", src, dest, len, dhcp_state);
 
+	if (net_read_ip(&bp->bp_yiaddr).s_addr == 0)
+		return;
+
 	switch (dhcp_state) {
 	case SELECTING:
 		/*
-- 
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