/*      $OpenBSD: res_init.c,v 1.11 2019/06/17 05:54:45 otto Exp $      */
/*
 * Copyright (c) 2012 Eric Faurot <eric@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/nameser.h>
#include <netinet/in.h>
#include <netdb.h>

#include <asr.h>
#include <resolv.h>
#include <string.h>

#include "asr_private.h"
#include "thread_private.h"


struct __res_state _res;
struct __res_state_ext _res_ext;

int h_errno;

int
res_init(void)
{
        static void *resinit_mutex;
        struct asr_ctx  *ac;
        int i;

        ac = _asr_use_resolver(NULL);

        /*
         * The first thread to call res_init() will setup the global _res
         * structure from the async context, not overriding fields set early
         * by the user.
         */
        _MUTEX_LOCK(&resinit_mutex);
        if (!(_res.options & RES_INIT)) {
                if (_res.retry == 0)
                        _res.retry = ac->ac_nsretries;
                if (_res.retrans == 0)
                        _res.retrans = ac->ac_nstimeout;
                if (_res.options == 0)
                        _res.options = ac->ac_options;
                if (_res.lookups[0] == '\0')
                        strlcpy(_res.lookups, ac->ac_db, sizeof(_res.lookups));

                for (i = 0; i < ac->ac_nscount && i < MAXNS; i++) {
                        /*
                         * No need to check for length since we copy to a
                         * struct sockaddr_storage with a size of 256 bytes
                         * and sa_len has only 8 bits.
                         */
                        memcpy(&_res_ext.nsaddr_list[i], ac->ac_ns[i],
                            ac->ac_ns[i]->sa_len);
                        if (ac->ac_ns[i]->sa_len <= sizeof(_res.nsaddr_list[i]))
                                memcpy(&_res.nsaddr_list[i], ac->ac_ns[i],
                                    ac->ac_ns[i]->sa_len);
                        else
                                memset(&_res.nsaddr_list[i], 0,
                                    sizeof(_res.nsaddr_list[i]));
                }
                _res.nscount = i;
                _res.options |= RES_INIT;
        }
        _MUTEX_UNLOCK(&resinit_mutex);

        /*
         * If the program is not threaded, we want to reflect (some) changes
         * made by the user to the global _res structure.
         * This is a bit of a hack: if there is already an async query on
         * this context, it might change things in its back.  It is ok
         * as long as the user only uses the blocking resolver API.
         * If needed we could consider cloning the context if there is
         * a running query.
         */
        if (!__isthreaded) {
                ac->ac_nsretries = _res.retry;
                ac->ac_nstimeout = _res.retrans;
                ac->ac_options = _res.options;
                strlcpy(ac->ac_db, _res.lookups, sizeof(ac->ac_db));
                ac->ac_dbcount = strlen(ac->ac_db);
        }

        _asr_ctx_unref(ac);

        return (0);
}
DEF_WEAK(res_init);