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, 29 insertions, 0 deletions

diff --git a/net/net.c b/net/net.c
index e215fd8d9a..4bbe5313c3 100644
--- a/net/net.c
+++ b/net/net.c
@@ -92,6 +92,9 @@
 #if defined(CONFIG_CDP_VERSION)
 #include <timestamp.h>
 #endif
+#if defined(CONFIG_CMD_DNS)
+#include "dns.h"
+#endif
 
 #if defined(CONFIG_CMD_NET)
 
@@ -291,6 +294,9 @@ NetInitLoop(proto_t protocol)
 		NetServerIP = getenv_IPaddr ("serverip");
 		NetOurNativeVLAN = getenv_VLAN("nvlan");
 		NetOurVLAN = getenv_VLAN("vlan");
+#if defined(CONFIG_CMD_DNS)
+		NetOurDNSIP = getenv_IPaddr("dnsip");
+#endif
 		env_changed_id = env_id;
 	}
 
@@ -426,6 +432,11 @@ restart:
 			SntpStart();
 			break;
 #endif
+#if defined(CONFIG_CMD_DNS)
+		case DNS:
+			DnsStart();
+			break;
+#endif
 		default:
 			break;
 		}
@@ -1518,6 +1529,14 @@ static int net_check_prereq (proto_t protocol)
 		}
 		goto common;
 #endif
+#if defined(CONFIG_CMD_DNS)
+	case DNS:
+		if (NetOurDNSIP == 0) {
+			puts("*** ERROR: DNS server address not given\n");
+			return 1;
+		}
+		goto common;
+#endif
 #if defined(CONFIG_CMD_NFS)
 	case NFS:
 #endif
@@ -1681,6 +1700,16 @@ void copy_filename (char *dst, char *src, int size)
 
 #endif
 
+#if defined(CONFIG_CMD_NFS) || defined(CONFIG_CMD_SNTP) || defined(CONFIG_CMD_DNS)
+/*
+ * make port a little random, but use something trivial to compute
+ */
+unsigned int random_port(void)
+{
+	return 1024 + (get_timer(0) % 0x8000);;
+}
+#endif
+
 void ip_to_string (IPaddr_t x, char *s)
 {
 	x = ntohl (x);