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121 lines
3.1 KiB
C
121 lines
3.1 KiB
C
/*
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* Copyright (C) 2017 Kaspar Schleiser <kaspar@schleiser.de>
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup net_sock_dns
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* @{
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* @file
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* @brief sock DNS client implementation
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* @author Kaspar Schleiser <kaspar@schleiser.de>
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* @author Hendrik van Essen <hendrik.ve@fu-berlin.de>
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* @}
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*/
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#include <errno.h>
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#include <string.h>
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#include <arpa/inet.h>
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#include "net/dns.h"
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#include "net/dns/cache.h"
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#include "net/dns/msg.h"
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#include "net/sock/udp.h"
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#include "net/sock/dns.h"
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/* min domain name length is 1, so minimum record length is 7 */
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#define DNS_MIN_REPLY_LEN (unsigned)(sizeof(dns_hdr_t) + 7)
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/* global DNS server UDP endpoint */
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sock_udp_ep_t sock_dns_server;
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#ifdef MODULE_AUTO_INIT_SOCK_DNS
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void auto_init_sock_dns(void)
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{
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assert( CONFIG_AUTO_INIT_SOCK_DNS_IP_VERSION == 4
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|| CONFIG_AUTO_INIT_SOCK_DNS_IP_VERSION == 6);
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assert( CONFIG_AUTO_INIT_SOCK_DNS_SERVER_PORT > 0
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&& CONFIG_AUTO_INIT_SOCK_DNS_SERVER_PORT <= 0xffff);
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switch (CONFIG_AUTO_INIT_SOCK_DNS_IP_VERSION) {
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#ifdef SOCK_HAS_IPV4
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case 4:
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inet_pton(AF_INET, CONFIG_AUTO_INIT_SOCK_DNS_SERVER_ADDR,
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sock_dns_server.addr.ipv4);
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sock_dns_server.family = AF_INET;
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break;
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#endif
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#ifdef SOCK_HAS_IPV6
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case 6:
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inet_pton(AF_INET6, CONFIG_AUTO_INIT_SOCK_DNS_SERVER_ADDR,
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sock_dns_server.addr.ipv6);
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sock_dns_server.family = AF_INET6;
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break;
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#endif
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default:
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assert(0);
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return;
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}
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sock_dns_server.port = CONFIG_AUTO_INIT_SOCK_DNS_SERVER_PORT;
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}
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#endif /* MODULE_AUTO_INIT_SOCK_DNS */
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int sock_dns_query(const char *domain_name, void *addr_out, int family)
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{
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ssize_t res;
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sock_udp_t sock_dns;
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static uint8_t dns_buf[CONFIG_DNS_MSG_LEN];
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if (sock_dns_server.port == 0) {
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return -ECONNREFUSED;
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}
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if (strlen(domain_name) > SOCK_DNS_MAX_NAME_LEN) {
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return -ENOSPC;
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}
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res = dns_cache_query(domain_name, addr_out, family);
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if (res) {
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return res;
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}
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res = sock_udp_create(&sock_dns, NULL, &sock_dns_server, 0);
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if (res) {
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goto out;
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}
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uint16_t id = 0;
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for (int i = 0; i < SOCK_DNS_RETRIES; i++) {
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size_t buflen = dns_msg_compose_query(dns_buf, domain_name, id, family);
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res = sock_udp_send(&sock_dns, dns_buf, buflen, NULL);
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if (res <= 0) {
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continue;
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}
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res = sock_udp_recv(&sock_dns, dns_buf, sizeof(dns_buf), 1000000LU, NULL);
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if (res > 0) {
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if (res > (int)DNS_MIN_REPLY_LEN) {
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uint32_t ttl;
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if ((res = dns_msg_parse_reply(dns_buf, res, family,
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addr_out, &ttl)) > 0) {
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dns_cache_add(domain_name, addr_out, res, ttl);
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goto out;
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}
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}
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else {
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res = -EBADMSG;
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}
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}
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}
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out:
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sock_udp_close(&sock_dns);
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return res;
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}
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