1/*	$OpenBSD: res_init.c,v 1.11 2019/06/17 05:54:45 otto Exp $	*/
2/*
3 * Copyright (c) 2012 Eric Faurot <eric@openbsd.org>
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18#include <sys/types.h>
19#include <sys/socket.h>
20#include <arpa/nameser.h>
21#include <netinet/in.h>
22#include <netdb.h>
23
24#include <asr.h>
25#include <resolv.h>
26#include <string.h>
27
28#include "asr_private.h"
29#include "thread_private.h"
30
31
32struct __res_state _res;
33struct __res_state_ext _res_ext;
34
35int h_errno;
36
37int
38res_init(void)
39{
40	static void *resinit_mutex;
41	struct asr_ctx	*ac;
42	int i;
43
44	ac = _asr_use_resolver(NULL);
45
46	/*
47	 * The first thread to call res_init() will setup the global _res
48	 * structure from the async context, not overriding fields set early
49	 * by the user.
50	 */
51	_MUTEX_LOCK(&resinit_mutex);
52	if (!(_res.options & RES_INIT)) {
53		if (_res.retry == 0)
54			_res.retry = ac->ac_nsretries;
55		if (_res.retrans == 0)
56			_res.retrans = ac->ac_nstimeout;
57		if (_res.options == 0)
58			_res.options = ac->ac_options;
59		if (_res.lookups[0] == '\0')
60			strlcpy(_res.lookups, ac->ac_db, sizeof(_res.lookups));
61
62		for (i = 0; i < ac->ac_nscount && i < MAXNS; i++) {
63			/*
64			 * No need to check for length since we copy to a
65			 * struct sockaddr_storage with a size of 256 bytes
66			 * and sa_len has only 8 bits.
67			 */
68			memcpy(&_res_ext.nsaddr_list[i], ac->ac_ns[i],
69			    ac->ac_ns[i]->sa_len);
70			if (ac->ac_ns[i]->sa_len <= sizeof(_res.nsaddr_list[i]))
71				memcpy(&_res.nsaddr_list[i], ac->ac_ns[i],
72				    ac->ac_ns[i]->sa_len);
73			else
74				memset(&_res.nsaddr_list[i], 0,
75				    sizeof(_res.nsaddr_list[i]));
76		}
77		_res.nscount = i;
78		_res.options |= RES_INIT;
79	}
80	_MUTEX_UNLOCK(&resinit_mutex);
81
82	/*
83	 * If the program is not threaded, we want to reflect (some) changes
84	 * made by the user to the global _res structure.
85	 * This is a bit of a hack: if there is already an async query on
86	 * this context, it might change things in its back.  It is ok
87	 * as long as the user only uses the blocking resolver API.
88	 * If needed we could consider cloning the context if there is
89	 * a running query.
90	 */
91	if (!__isthreaded) {
92		ac->ac_nsretries = _res.retry;
93		ac->ac_nstimeout = _res.retrans;
94		ac->ac_options = _res.options;
95		strlcpy(ac->ac_db, _res.lookups, sizeof(ac->ac_db));
96		ac->ac_dbcount = strlen(ac->ac_db);
97	}
98
99	_asr_ctx_unref(ac);
100
101	return (0);
102}
103DEF_WEAK(res_init);
104