[U-Boot] Possible fix for dns command

[Mathias Adam]

Hello,

I'm currently using u-boot on a TI DM816x evaluation board (u-boot as
included in TI's EZSDK 5.02). I manually enabled CONFIG_CMD_DNS. However,
running dhcp followed by dns <some_host_name> only gave timeouts.

I found (using #define DEBUG) that DNS UDP queries are being sent to the
MAC of the DHCP server -- which is not equal to the DNS server, hence the
timeouts. Forcing ARP queries before DNS fixed this (see patch below). I
copyied that line from net/tftp.c (which works out of the box).

However, as I'm quite new to u-boot I'm not sure whether that behaviour is
intended or if my patch breaks other things?

Patch (against plain u-boot-2011.09):

--- net/dns.c	2011-09-29 21:11:15.000000000 +0200
+++
../ti-ezsdk_dm816x-evm_5_02_02_60/board-support/u-boot-2010.06-psp04.00.00.12/net/dns.c	2011-11-16
10:35:38.335903630 +0100
@@ -206,5 +206,8 @@
 	NetSetTimeout(DNS_TIMEOUT, DnsTimeout);
 	NetSetHandler(DnsHandler);
+	/* zero out server ether in case the server ip has changed */
+	memset(NetServerEther, 0, 6);
+
 	DnsSend();
 }



Regards,
Mathias Adam