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f1d925d9c3
The random_port() routine is not used anywhere else. Make it local to dns.c to reduce code clutter, and shrink generated code a little. Signed-off-by: Baruch Siach <baruch@tkos.co.il>
219 lines
5.1 KiB
C
219 lines
5.1 KiB
C
/*
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* DNS support driver
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*
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* Copyright (c) 2008 Pieter Voorthuijsen <pieter.voorthuijsen@prodrive.nl>
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* Copyright (c) 2009 Robin Getz <rgetz@blackfin.uclinux.org>
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*
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* This is a simple DNS implementation for U-Boot. It will use the first IP
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* in the DNS response as net_server_ip. This can then be used for any other
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* network related activities.
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*
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* The packet handling is partly based on TADNS, original copyrights
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* follow below.
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*
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*/
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/*
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* Copyright (c) 2004-2005 Sergey Lyubka <valenok@gmail.com>
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*
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* "THE BEER-WARE LICENSE" (Revision 42):
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* Sergey Lyubka wrote this file. As long as you retain this notice you
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* can do whatever you want with this stuff. If we meet some day, and you think
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* this stuff is worth it, you can buy me a beer in return.
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*/
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#include <common.h>
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#include <command.h>
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#include <env.h>
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#include <log.h>
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#include <net.h>
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#include <asm/unaligned.h>
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#include "dns.h"
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char *net_dns_resolve; /* The host to resolve */
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char *net_dns_env_var; /* The envvar to store the answer in */
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static int dns_our_port;
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/*
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* make port a little random (1024-17407)
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* This keeps the math somewhat trivial to compute, and seems to work with
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* all supported protocols/clients/servers
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*/
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static unsigned int random_port(void)
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{
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return 1024 + (get_timer(0) % 0x4000);
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}
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static void dns_send(void)
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{
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struct header *header;
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int n, name_len;
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uchar *p, *pkt;
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const char *s;
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const char *name;
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enum dns_query_type qtype = DNS_A_RECORD;
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name = net_dns_resolve;
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pkt = (uchar *)(net_tx_packet + net_eth_hdr_size() + IP_UDP_HDR_SIZE);
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p = pkt;
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/* Prepare DNS packet header */
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header = (struct header *)pkt;
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header->tid = 1;
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header->flags = htons(0x100); /* standard query */
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header->nqueries = htons(1); /* Just one query */
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header->nanswers = 0;
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header->nauth = 0;
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header->nother = 0;
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/* Encode DNS name */
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name_len = strlen(name);
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p = (uchar *)&header->data; /* For encoding host name into packet */
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do {
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s = strchr(name, '.');
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if (!s)
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s = name + name_len;
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n = s - name; /* Chunk length */
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*p++ = n; /* Copy length */
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memcpy(p, name, n); /* Copy chunk */
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p += n;
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if (*s == '.')
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n++;
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name += n;
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name_len -= n;
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} while (*s != '\0');
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*p++ = 0; /* Mark end of host name */
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*p++ = 0; /* Some servers require double null */
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*p++ = (unsigned char) qtype; /* Query Type */
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*p++ = 0;
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*p++ = 1; /* Class: inet, 0x0001 */
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n = p - pkt; /* Total packet length */
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debug("Packet size %d\n", n);
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dns_our_port = random_port();
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net_send_udp_packet(net_server_ethaddr, net_dns_server,
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DNS_SERVICE_PORT, dns_our_port, n);
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debug("DNS packet sent\n");
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}
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static void dns_timeout_handler(void)
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{
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puts("Timeout\n");
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net_set_state(NETLOOP_FAIL);
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}
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static void dns_handler(uchar *pkt, unsigned dest, struct in_addr sip,
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unsigned src, unsigned len)
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{
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struct header *header;
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const unsigned char *p, *e, *s;
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u16 type, i;
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int found, stop, dlen;
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char ip_str[22];
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struct in_addr ip_addr;
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debug("%s\n", __func__);
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if (dest != dns_our_port)
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return;
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for (i = 0; i < len; i += 4)
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debug("0x%p - 0x%.2x 0x%.2x 0x%.2x 0x%.2x\n",
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pkt+i, pkt[i], pkt[i+1], pkt[i+2], pkt[i+3]);
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/* We sent one query. We want to have a single answer: */
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header = (struct header *)pkt;
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if (ntohs(header->nqueries) != 1)
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return;
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/* Received 0 answers */
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if (header->nanswers == 0) {
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puts("DNS: host not found\n");
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net_set_state(NETLOOP_SUCCESS);
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return;
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}
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/* Skip host name */
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s = &header->data[0];
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e = pkt + len;
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for (p = s; p < e && *p != '\0'; p++)
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continue;
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/* We sent query class 1, query type 1 */
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if (&p[5] > e || get_unaligned_be16(p+1) != DNS_A_RECORD) {
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puts("DNS: response was not an A record\n");
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net_set_state(NETLOOP_SUCCESS);
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return;
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}
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/* Go to the first answer section */
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p += 5;
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/* Loop through the answers, we want A type answer */
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for (found = stop = 0; !stop && &p[12] < e; ) {
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/* Skip possible name in CNAME answer */
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if (*p != 0xc0) {
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while (*p && &p[12] < e)
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p++;
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p--;
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}
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debug("Name (Offset in header): %d\n", p[1]);
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type = get_unaligned_be16(p+2);
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debug("type = %d\n", type);
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if (type == DNS_CNAME_RECORD) {
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/* CNAME answer. shift to the next section */
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debug("Found canonical name\n");
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dlen = get_unaligned_be16(p+10);
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debug("dlen = %d\n", dlen);
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p += 12 + dlen;
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} else if (type == DNS_A_RECORD) {
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debug("Found A-record\n");
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found = 1;
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stop = 1;
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} else {
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debug("Unknown type\n");
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stop = 1;
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}
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}
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if (found && &p[12] < e) {
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dlen = get_unaligned_be16(p+10);
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p += 12;
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memcpy(&ip_addr, p, 4);
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if (p + dlen <= e) {
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ip_to_string(ip_addr, ip_str);
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printf("%s\n", ip_str);
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if (net_dns_env_var)
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env_set(net_dns_env_var, ip_str);
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} else {
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puts("server responded with invalid IP number\n");
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}
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}
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net_set_state(NETLOOP_SUCCESS);
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}
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void dns_start(void)
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{
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debug("%s\n", __func__);
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net_set_timeout_handler(DNS_TIMEOUT, dns_timeout_handler);
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net_set_udp_handler(dns_handler);
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/* Clear a previous MAC address, the server IP might have changed. */
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memset(net_server_ethaddr, 0, sizeof(net_server_ethaddr));
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dns_send();
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}
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