[U-Boot] [PATCH] net: bootp: Ignore packets whose yiaddr is 0

[Wolfgang Denk <wd@denx.de>]

Dear Peng Fan,

In message <1451875796-15860-1-git-send-email-peng.fan@nxp.com> you wrote:
> 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>
> ---
>  net/bootp.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/net/bootp.c b/net/bootp.c
> index 8aeddb0..ff2ebbe 100644
> --- a/net/bootp.c
> +++ b/net/bootp.c
> @@ -992,6 +992,9 @@ static void dhcp_handler(uchar *pkt, unsigned dest, struct in_addr sip,
>  	if (check_reply_packet(pkt, dest, src, len))
>  		return;
>  
> +	if (net_read_ip(&bp->bp_yiaddr).s_addr == 0)
> +		return;
> +
>  	debug("DHCPHandler: got DHCP packet: (src=%d, dst=%d, len=%d) state: "
>  	      "%d\n", src, dest, len, dhcp_state);

I suggest the return should be done _after_ the debug message.

Best regards,

Wolfgang Denk

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