Add DNS support

On 04 Oct 2008 Pieter posted a dns implementation for U-Boot.

http://www.mail-archive.com/u-boot-users@lists.sourceforge.net/msg10216.html
>
> DNS can be enabled by setting CFG_CMD_DNS. After performing a query,
> the serverip environment var is updated.
>
> Probably there are some cosmetic issues with the patch. Unfortunatly I
> do not have the time to correct these. So if anybody else likes DNS
> support in U-Boot and has the time, feel free to patch it in the main tree.

Here it is again - slightly modified & smaller:
  - update to 2009-06 (Pieter's patch was for U-Boot 1.2.0)
  - README.dns is added
  - syntax is changed (now takes a third option, the env var to store
    the result in)
  - add a random port() function in net.c
  - sort Makefile in ./net/Makefile
  - dns just returns unless a env var is given
  - run through checkpatch, and clean up style issues
  - remove packet from stack
  - cleaned up some comments
  - failure returns much faster (if server responds, don't wait for
    timeout)
  - use built in functions (memcpy) rather than byte copy.

Signed-off-by: Robin Getz <rgetz@blackfin.uclinux.org>
Signed-off-by: Pieter Voorthuijsen <pieter.voorthuijsen@prodrive.nl>
Signed-off-by: Ben Warren <biggerbadderben@gmail.com>

1 files changed, 39 insertions, 0 deletions

diff --git a/net/dns.h b/net/dns.h
new file mode 100644
index 0000000..277c093
--- /dev/null
+++ b/net/dns.h
@@ -0,0 +1,39 @@
+/*
+ * (C) Masami Komiya <mkomiya@sonare.it> 2005
+ *  Copyright 2009, Robin Getz <rgetz@blackfin.uclinux.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2, or (at
+ * your option) any later version.
+ */
+
+#ifndef __DNS_H__
+#define __DNS_H__
+
+#define DNS_SERVICE_PORT 53
+#define DNS_TIMEOUT      10000UL
+
+/* http://en.wikipedia.org/wiki/List_of_DNS_record_types */
+enum dns_query_type {
+	DNS_A_RECORD = 0x01,
+	DNS_CNAME_RECORD = 0x05,
+	DNS_MX_RECORD = 0x0f,
+};
+
+/*
+ * DNS network packet
+ */
+struct header {
+	uint16_t	tid;		/* Transaction ID */
+	uint16_t	flags;		/* Flags */
+	uint16_t	nqueries;	/* Questions */
+	uint16_t	nanswers;	/* Answers */
+	uint16_t	nauth;		/* Authority PRs */
+	uint16_t	nother;		/* Other PRs */
+	unsigned char	data[1];	/* Data, variable length */
+};
+
+extern void DnsStart(void);		/* Begin DNS */
+
+#endif