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Robin Getz1a32bf42009-07-20 14:53:54 -04001/*
2 * DNS support driver
3 *
4 * Copyright (c) 2008 Pieter Voorthuijsen <pieter.voorthuijsen@prodrive.nl>
5 * Copyright (c) 2009 Robin Getz <rgetz@blackfin.uclinux.org>
6 *
7 * This is a simple DNS implementation for U-Boot. It will use the first IP
8 * in the DNS response as NetServerIP. This can then be used for any other
9 * network related activities.
10 *
11 * The packet handling is partly based on TADNS, original copyrights
12 * follow below.
13 *
14 */
15
16/*
17 * Copyright (c) 2004-2005 Sergey Lyubka <valenok@gmail.com>
18 *
19 * "THE BEER-WARE LICENSE" (Revision 42):
20 * Sergey Lyubka wrote this file. As long as you retain this notice you
21 * can do whatever you want with this stuff. If we meet some day, and you think
22 * this stuff is worth it, you can buy me a beer in return.
23 */
24
25#include <common.h>
26#include <command.h>
27#include <net.h>
Bernhard Kaindl6dc809f2011-10-15 23:59:22 +000028#include <asm/unaligned.h>
Robin Getz1a32bf42009-07-20 14:53:54 -040029
30#include "dns.h"
31
32char *NetDNSResolve; /* The host to resolve */
33char *NetDNSenvvar; /* The envvar to store the answer in */
34
35static int DnsOurPort;
36
37static void
38DnsSend(void)
39{
40 struct header *header;
41 int n, name_len;
42 uchar *p, *pkt;
43 const char *s;
44 const char *name;
45 enum dns_query_type qtype = DNS_A_RECORD;
46
47 name = NetDNSResolve;
Joe Hershberger594c26f2012-05-23 07:58:04 +000048 pkt = p = (uchar *)(NetTxPacket + NetEthHdrSize() + IP_UDP_HDR_SIZE);
Robin Getz1a32bf42009-07-20 14:53:54 -040049
50 /* Prepare DNS packet header */
51 header = (struct header *) pkt;
52 header->tid = 1;
53 header->flags = htons(0x100); /* standard query */
54 header->nqueries = htons(1); /* Just one query */
55 header->nanswers = 0;
56 header->nauth = 0;
57 header->nother = 0;
58
59 /* Encode DNS name */
60 name_len = strlen(name);
61 p = (uchar *) &header->data; /* For encoding host name into packet */
62
63 do {
64 s = strchr(name, '.');
65 if (!s)
66 s = name + name_len;
67
68 n = s - name; /* Chunk length */
69 *p++ = n; /* Copy length */
70 memcpy(p, name, n); /* Copy chunk */
71 p += n;
72
73 if (*s == '.')
74 n++;
75
76 name += n;
77 name_len -= n;
78 } while (*s != '\0');
79
80 *p++ = 0; /* Mark end of host name */
81 *p++ = 0; /* Some servers require double null */
82 *p++ = (unsigned char) qtype; /* Query Type */
83
84 *p++ = 0;
85 *p++ = 1; /* Class: inet, 0x0001 */
86
87 n = p - pkt; /* Total packet length */
88 debug("Packet size %d\n", n);
89
90 DnsOurPort = random_port();
91
92 NetSendUDPPacket(NetServerEther, NetOurDNSIP, DNS_SERVICE_PORT,
93 DnsOurPort, n);
94 debug("DNS packet sent\n");
95}
96
97static void
98DnsTimeout(void)
99{
100 puts("Timeout\n");
Joe Hershberger22f6e992012-05-23 07:59:14 +0000101 net_set_state(NETLOOP_FAIL);
Robin Getz1a32bf42009-07-20 14:53:54 -0400102}
103
104static void
Luca Ceresoli03eb1292011-04-18 06:19:50 +0000105DnsHandler(uchar *pkt, unsigned dest, IPaddr_t sip, unsigned src, unsigned len)
Robin Getz1a32bf42009-07-20 14:53:54 -0400106{
107 struct header *header;
108 const unsigned char *p, *e, *s;
109 u16 type, i;
110 int found, stop, dlen;
111 char IPStr[22];
112 IPaddr_t IPAddress;
Robin Getz1a32bf42009-07-20 14:53:54 -0400113
114
115 debug("%s\n", __func__);
116 if (dest != DnsOurPort)
117 return;
118
119 for (i = 0; i < len; i += 4)
120 debug("0x%p - 0x%.2x 0x%.2x 0x%.2x 0x%.2x\n",
121 pkt+i, pkt[i], pkt[i+1], pkt[i+2], pkt[i+3]);
122
Bernhard Kaindl6dc809f2011-10-15 23:59:22 +0000123 /* We sent one query. We want to have a single answer: */
Robin Getz1a32bf42009-07-20 14:53:54 -0400124 header = (struct header *) pkt;
125 if (ntohs(header->nqueries) != 1)
126 return;
127
128 /* Received 0 answers */
129 if (header->nanswers == 0) {
Bernhard Kaindl6dc809f2011-10-15 23:59:22 +0000130 puts("DNS: host not found\n");
Joe Hershberger22f6e992012-05-23 07:59:14 +0000131 net_set_state(NETLOOP_SUCCESS);
Robin Getz1a32bf42009-07-20 14:53:54 -0400132 return;
133 }
134
135 /* Skip host name */
136 s = &header->data[0];
137 e = pkt + len;
138 for (p = s; p < e && *p != '\0'; p++)
139 continue;
140
141 /* We sent query class 1, query type 1 */
Bernhard Kaindl6dc809f2011-10-15 23:59:22 +0000142 if (&p[5] > e || get_unaligned_be16(p+1) != DNS_A_RECORD) {
143 puts("DNS: response was not an A record\n");
Joe Hershberger22f6e992012-05-23 07:59:14 +0000144 net_set_state(NETLOOP_SUCCESS);
Robin Getz1a32bf42009-07-20 14:53:54 -0400145 return;
146 }
147
148 /* Go to the first answer section */
149 p += 5;
150
151 /* Loop through the answers, we want A type answer */
152 for (found = stop = 0; !stop && &p[12] < e; ) {
153
154 /* Skip possible name in CNAME answer */
155 if (*p != 0xc0) {
156 while (*p && &p[12] < e)
157 p++;
158 p--;
159 }
160 debug("Name (Offset in header): %d\n", p[1]);
161
Bernhard Kaindl6dc809f2011-10-15 23:59:22 +0000162 type = get_unaligned_be16(p+2);
Robin Getz1a32bf42009-07-20 14:53:54 -0400163 debug("type = %d\n", type);
164 if (type == DNS_CNAME_RECORD) {
165 /* CNAME answer. shift to the next section */
166 debug("Found canonical name\n");
Bernhard Kaindl6dc809f2011-10-15 23:59:22 +0000167 dlen = get_unaligned_be16(p+10);
Robin Getz1a32bf42009-07-20 14:53:54 -0400168 debug("dlen = %d\n", dlen);
169 p += 12 + dlen;
170 } else if (type == DNS_A_RECORD) {
171 debug("Found A-record\n");
172 found = stop = 1;
173 } else {
174 debug("Unknown type\n");
175 stop = 1;
176 }
177 }
178
179 if (found && &p[12] < e) {
180
Bernhard Kaindl6dc809f2011-10-15 23:59:22 +0000181 dlen = get_unaligned_be16(p+10);
Robin Getz1a32bf42009-07-20 14:53:54 -0400182 p += 12;
183 memcpy(&IPAddress, p, 4);
184
185 if (p + dlen <= e) {
186 ip_to_string(IPAddress, IPStr);
187 printf("%s\n", IPStr);
188 if (NetDNSenvvar)
189 setenv(NetDNSenvvar, IPStr);
190 } else
191 puts("server responded with invalid IP number\n");
192 }
193
Joe Hershberger22f6e992012-05-23 07:59:14 +0000194 net_set_state(NETLOOP_SUCCESS);
Robin Getz1a32bf42009-07-20 14:53:54 -0400195}
196
197void
198DnsStart(void)
199{
200 debug("%s\n", __func__);
201
202 NetSetTimeout(DNS_TIMEOUT, DnsTimeout);
Joe Hershbergerece223b2012-05-23 07:59:15 +0000203 net_set_udp_handler(DnsHandler);
Robin Getz1a32bf42009-07-20 14:53:54 -0400204
Gerhard Sittigf395e752014-09-12 08:48:15 +0200205 /* Clear a previous MAC address, the server IP might have changed. */
206 memset(NetServerEther, 0, sizeof(NetServerEther));
207
Robin Getz1a32bf42009-07-20 14:53:54 -0400208 DnsSend();
209}