4 * Copyright (c) 2008 Pieter Voorthuijsen <pieter.voorthuijsen@prodrive.nl>
5 * Copyright (c) 2009 Robin Getz <rgetz@blackfin.uclinux.org>
7 * This is a simple DNS implementation for U-Boot. It will use the first IP
8 * in the DNS response as net_server_ip. This can then be used for any other
9 * network related activities.
11 * The packet handling is partly based on TADNS, original copyrights
17 * Copyright (c) 2004-2005 Sergey Lyubka <valenok@gmail.com>
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.
28 #include <asm/unaligned.h>
32 char *NetDNSResolve; /* The host to resolve */
33 char *NetDNSenvvar; /* The envvar to store the answer in */
35 static int DnsOurPort;
40 struct header *header;
45 enum dns_query_type qtype = DNS_A_RECORD;
48 pkt = (uchar *)(net_tx_packet + net_eth_hdr_size() + IP_UDP_HDR_SIZE);
51 /* Prepare DNS packet header */
52 header = (struct header *) pkt;
54 header->flags = htons(0x100); /* standard query */
55 header->nqueries = htons(1); /* Just one query */
61 name_len = strlen(name);
62 p = (uchar *) &header->data; /* For encoding host name into packet */
65 s = strchr(name, '.');
69 n = s - name; /* Chunk length */
70 *p++ = n; /* Copy length */
71 memcpy(p, name, n); /* Copy chunk */
81 *p++ = 0; /* Mark end of host name */
82 *p++ = 0; /* Some servers require double null */
83 *p++ = (unsigned char) qtype; /* Query Type */
86 *p++ = 1; /* Class: inet, 0x0001 */
88 n = p - pkt; /* Total packet length */
89 debug("Packet size %d\n", n);
91 DnsOurPort = random_port();
93 net_send_udp_packet(net_server_ethaddr, net_dns_server,
94 DNS_SERVICE_PORT, DnsOurPort, n);
95 debug("DNS packet sent\n");
102 net_set_state(NETLOOP_FAIL);
105 static void dns_handler(uchar *pkt, unsigned dest, struct in_addr sip,
106 unsigned src, unsigned len)
108 struct header *header;
109 const unsigned char *p, *e, *s;
111 int found, stop, dlen;
113 struct in_addr ip_addr;
116 debug("%s\n", __func__);
117 if (dest != DnsOurPort)
120 for (i = 0; i < len; i += 4)
121 debug("0x%p - 0x%.2x 0x%.2x 0x%.2x 0x%.2x\n",
122 pkt+i, pkt[i], pkt[i+1], pkt[i+2], pkt[i+3]);
124 /* We sent one query. We want to have a single answer: */
125 header = (struct header *) pkt;
126 if (ntohs(header->nqueries) != 1)
129 /* Received 0 answers */
130 if (header->nanswers == 0) {
131 puts("DNS: host not found\n");
132 net_set_state(NETLOOP_SUCCESS);
137 s = &header->data[0];
139 for (p = s; p < e && *p != '\0'; p++)
142 /* We sent query class 1, query type 1 */
143 if (&p[5] > e || get_unaligned_be16(p+1) != DNS_A_RECORD) {
144 puts("DNS: response was not an A record\n");
145 net_set_state(NETLOOP_SUCCESS);
149 /* Go to the first answer section */
152 /* Loop through the answers, we want A type answer */
153 for (found = stop = 0; !stop && &p[12] < e; ) {
155 /* Skip possible name in CNAME answer */
157 while (*p && &p[12] < e)
161 debug("Name (Offset in header): %d\n", p[1]);
163 type = get_unaligned_be16(p+2);
164 debug("type = %d\n", type);
165 if (type == DNS_CNAME_RECORD) {
166 /* CNAME answer. shift to the next section */
167 debug("Found canonical name\n");
168 dlen = get_unaligned_be16(p+10);
169 debug("dlen = %d\n", dlen);
171 } else if (type == DNS_A_RECORD) {
172 debug("Found A-record\n");
175 debug("Unknown type\n");
180 if (found && &p[12] < e) {
182 dlen = get_unaligned_be16(p+10);
184 memcpy(&ip_addr, p, 4);
187 ip_to_string(ip_addr, IPStr);
188 printf("%s\n", IPStr);
190 setenv(NetDNSenvvar, IPStr);
192 puts("server responded with invalid IP number\n");
195 net_set_state(NETLOOP_SUCCESS);
201 debug("%s\n", __func__);
203 NetSetTimeout(DNS_TIMEOUT, DnsTimeout);
204 net_set_udp_handler(dns_handler);
206 /* Clear a previous MAC address, the server IP might have changed. */
207 memset(net_server_ethaddr, 0, sizeof(net_server_ethaddr));