[U-Boot] [PATCH] - add dns

Robin Getz rgetz at blackfin.uclinux.org
Fri Jul 17 21:53:07 CEST 2009


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)
  - 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.

bfin> dhcp
BOOTP broadcast 1
DHCP client bound to address 192.168.0.4
bfin> dns pool.ntp.org
69.36.241.112
bfin> sntp $(serverip)
Date: 2009-07-17 Time: 19:16:51
bfin> dns www.google.com
64.233.161.147
bfin> ping $(serverip)
Using Blackfin EMAC device
host 64.233.161.147 is alive

Signed-off-by: Robin Getz <rgetz at blackfin.uclinux.org>
Signed-off-by: Pieter Voorthuijsen <pieter.voorthuijsen at prodrive.nl>


 common/cmd_net.c                  |   32 ++++
 include/configs/bfin_adi_common.h |    7
 include/net.h                     |    4
 net/Makefile                      |    1
 net/dns.c                         |  213 ++++++++++++++++++++++++++++
 net/dns.h                         |   38 ++++
 net/net.c                         |   20 ++
 7 files changed, 314 insertions(+), 1 deletion(-)

---

Index: include/net.h
===================================================================
--- include/net.h	(revision 1968)
+++ include/net.h	(working copy)
@@ -361,6 +361,10 @@
 /* from net/net.c */
 extern char	BootFile[128];			/* Boot File name		*/
 
+#if defined(CONFIG_CMD_DNS)
+extern char NetDNSResolve[255];			/* The host to resolve  */
+#endif
+
 #if defined(CONFIG_CMD_PING)
 extern IPaddr_t	NetPingIP;			/* the ip address to ping		*/
 #endif
Index: include/configs/bfin_adi_common.h
===================================================================
--- include/configs/bfin_adi_common.h	(revision 1968)
+++ include/configs/bfin_adi_common.h	(working copy)
@@ -13,6 +13,13 @@
 # if ADI_CMDS_NETWORK
 #  define CONFIG_CMD_DHCP
 #  define CONFIG_CMD_PING
+#  define CONFIG_BOOTP_DNS
+#  define CONFIG_BOOTP_DNS2
+#  define CONFIG_CMD_DNS
+#  ifdef CONFIG_RTC_BFIN
+#   define CONFIG_CMD_SNTP
+#   define CONFIG_BOOTP_NTPSERVER
+#  endif
 #  ifdef CONFIG_BFIN_MAC
 #   define CONFIG_CMD_MII
 #  endif
Index: net/dns.c
===================================================================
--- net/dns.c	(revision 0)
+++ net/dns.c	(revision 0)
@@ -0,0 +1,213 @@
+/*
+ * DNS support driver
+ *
+ * Copyright (c) 2008 Pieter Voorthuijsen <pieter.voorthuijsen at prodrive.nl>
+ * Copyright (c) 2009 Robin Getz <rgetz at blackfin.uclinux.org>
+ *
+ * This is a simple DNS implementation for U-Boot. It will use the first IP
+ * in the DNS response as NetServerIP. This can then be used for any other
+ * network related activities.
+ *
+ * The packet handling is partly based on TADNS, original copyrights
+ * follow below.
+ *
+ */
+
+/*
+ * Copyright (c) 2004-2005 Sergey Lyubka <valenok at gmail.com>
+ *
+ * "THE BEER-WARE LICENSE" (Revision 42):
+ * Sergey Lyubka wrote this file.  As long as you retain this notice you
+ * can do whatever you want with this stuff. If we meet some day, and you think
+ * this stuff is worth it, you can buy me a beer in return.
+ */
+
+#include <common.h>
+#include <command.h>
+#include <net.h>
+
+#include "dns.h"
+
+char NetDNSResolve[255];     /* The host to resolve  */
+
+static int DnsOurPort;
+
+static void
+DnsSend(void)
+{
+	struct header *header;
+	int n, name_len;
+	uchar *p, *pkt;
+	const char *s;
+	const char *name;
+	enum dns_query_type qtype = DNS_A_RECORD;
+
+	name = NetDNSResolve;
+	pkt = p = (uchar *)(NetTxPacket + NetEthHdrSize() + IP_HDR_SIZE);
+
+	/* Prepare DNS packet header */
+	header           = (struct header *) pkt;
+	header->tid      = 1;
+	header->flags    = htons(0x100);	/* standard query */
+	header->nqueries = htons(1);		/* Just one query */
+	header->nanswers = 0;
+	header->nauth    = 0;
+	header->nother   = 0;
+
+	/* Encode DNS name */
+	name_len = strlen(name);
+	p = (uchar *) &header->data;	/* For encoding host name into packet */
+
+	do {
+		s = strchr(name, '.');
+		if (!s)
+			s = name + name_len;
+
+		n = s - name;			/* Chunk length */
+		*p++ = n;			/* Copy length  */
+		memcpy(p, name, n);		/* Copy chunk   */
+		p += n;
+
+		if (*s == '.')
+			n++;
+
+		name += n;
+		name_len -= n;
+	} while (*s != '\0');
+
+	*p++ = 0;			/* Mark end of host name */
+	*p++ = 0;			/* Well, lets put this byte as well */
+	*p++ = (unsigned char) qtype;	/* Query Type */
+
+	*p++ = 0;
+	*p++ = 1;				/* Class: inet, 0x0001 */
+
+	n = p - pkt;				/* Total packet length */
+	debug("Packet size %d\n", n);
+
+	DnsOurPort = 10000 + (get_timer(0) % 4096);
+
+	NetSendUDPPacket(NetServerEther, NetOurDNSIP, DNS_SERVICE_PORT,
+		DnsOurPort, n);
+	debug("DNS packet sent\n");
+}
+
+static void
+DnsTimeout(void)
+{
+	puts("Timeout\n");
+	NetState = NETLOOP_FAIL;
+}
+
+static void
+DnsHandler(uchar *pkt, unsigned dest, unsigned src, unsigned len)
+{
+	struct header *header;
+	const unsigned char *p, *e, *s;
+	u16 type, i;
+	int found, stop, dlen;
+	char IPStr[255];
+	IPaddr_t IPAddress;
+	short tmp;
+
+
+	debug("%s\n", __func__);
+	if (dest != DnsOurPort)
+		return;
+
+	for (i = 0; i < len; i += 4)
+		debug("0x%p - 0x%.2x  0x%.2x  0x%.2x  0x%.2x\n",
+			pkt+i, pkt[i], pkt[i+1], pkt[i+2], pkt[i+3]);
+
+	/* We sent 1 query. We want to see more that 1 answer. */
+	header = (struct header *) pkt;
+	if (ntohs(header->nqueries) != 1)
+		return;
+
+	/* Received 0 answers */
+	if (header->nanswers == 0) {
+		debug("DNS server returned no answers\n");
+		puts("server can't find hostname\n");
+		NetState = NETLOOP_SUCCESS;
+		return;
+	}
+
+	/* Skip host name */
+	s = &header->data[0];
+	e = pkt + len;
+	for (p = s; p < e && *p != '\0'; p++)
+		continue;
+
+	/* We sent query class 1, query type 1 */
+	tmp = p[1] | (p[2] << 8);
+	if (&p[5] > e || ntohs(tmp) != DNS_A_RECORD) {
+		debug("Query was not A record\n");
+		puts("server can't find IP number of hostname\n");
+		NetState = NETLOOP_SUCCESS;
+		return;
+	}
+
+	/* Go to the first answer section */
+	p += 5;
+
+	/* Loop through the answers, we want A type answer */
+	for (found = stop = 0; !stop && &p[12] < e; ) {
+
+		/* Skip possible name in CNAME answer */
+		if (*p != 0xc0) {
+			while (*p && &p[12] < e)
+				p++;
+			p--;
+		}
+		debug("Name (Offset in header): %d\n", p[1]);
+
+		tmp = p[2] | (p[3] << 8);
+		type = ntohs(tmp);
+		debug("type = %d\n", type);
+		if (type == DNS_CNAME_RECORD) {
+			/* CNAME answer. shift to the next section */
+			debug("Found canonical name\n");
+			tmp = p[10] | (p[11] << 8);
+			dlen = ntohs(tmp);
+			debug("dlen = %d\n", dlen);
+			p += 12 + dlen;
+		} else if (type == DNS_A_RECORD) {
+			debug("Found A-record\n");
+			found = stop = 1;
+		} else {
+			debug("Unknown type\n");
+			stop = 1;
+		}
+	}
+
+	if (found && &p[12] < e) {
+
+		tmp = p[10] | (p[11] << 8);
+		dlen = ntohs(tmp);
+		p += 12;
+		memcpy(&IPAddress, p, 4);
+
+		if (p + dlen <= e) {
+			ip_to_string(IPAddress, IPStr);
+			NetServerIP = IPAddress;
+			setenv("serverip", IPStr);
+			printf("%s\n", IPStr);
+		} else
+			puts("server responded with invalid IP number\n");
+	}
+
+	NetState = NETLOOP_SUCCESS;
+}
+
+void
+DnsStart(void)
+{
+	debug("%s\n", __func__);
+
+	NetSetTimeout(DNS_TIMEOUT, DnsTimeout);
+	NetSetHandler(DnsHandler);
+	memset(NetServerEther, 0, 6);
+
+	DnsSend();
+}
+
Index: net/net.c
===================================================================
--- net/net.c	(revision 1968)
+++ net/net.c	(working copy)
@@ -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)
 
@@ -165,7 +168,6 @@
 ushort		NetOurNativeVLAN = 0xFFFF;	/* ditto			*/
 
 char		BootFile[128];		/* Boot File name			*/
-
 #if defined(CONFIG_CMD_PING)
 IPaddr_t	NetPingIP;		/* the ip address to ping		*/
 
@@ -291,6 +293,9 @@
 		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 @@
 			SntpStart();
 			break;
 #endif
+#if defined(CONFIG_CMD_DNS)
+		case DNS:
+			DnsStart();
+			break;
+#endif
 		default:
 			break;
 		}
@@ -1518,6 +1529,14 @@
 		}
 		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
Index: net/dns.h
===================================================================
--- net/dns.h	(revision 0)
+++ net/dns.h	(revision 0)
@@ -0,0 +1,39 @@
+/*
+ * (C) Masami Komiya <mkomiya at sonare.it> 2005
+ *
+ * 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_MAX          1025	/* Maximum host name */
+#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
Index: net/Makefile
===================================================================
--- net/Makefile	(revision 1968)
+++ net/Makefile	(working copy)
@@ -34,6 +34,7 @@
 COBJS-y += eth.o
 COBJS-y += nfs.o
 COBJS-$(CONFIG_CMD_SNTP) += sntp.o
+COBJS-$(CONFIG_CMD_DNS)  += dns.o
 
 COBJS	:= $(COBJS-y)
 SRCS	:= $(COBJS:.o=.c)
Index: common/cmd_net.c
===================================================================
--- common/cmd_net.c	(revision 1968)
+++ common/cmd_net.c	(working copy)
@@ -353,3 +353,35 @@
 	"[NTP server IP]\n"
 );
 #endif
+
+#if defined(CONFIG_CMD_DNS)
+int do_dns(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+{
+	if (argc < 2) {
+		cmd_usage(cmdtp);
+		return -1;
+	}
+
+	if (strlen(argv[1]) > sizeof(NetDNSResolve) - 1) {
+		puts("Name too long.\n");
+		return -1;
+	}
+
+	strcpy(NetDNSResolve, argv[1]);
+
+	if (NetLoop(DNS) < 0) {
+		printf("dns lookup of %s failed, check setup\n", argv[1]);
+		return 1;
+	}
+
+	return 0;
+}
+
+U_BOOT_CMD(
+	dns,	2,	1,	do_dns,
+	"lookup the IP of a hostname",
+	"[machine to lookup]\n"
+);
+
+#endif	/* CONFIG_CMD_DNS */
+


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