resolv/res_data.cpp

/*	$NetBSD: res_data.c,v 1.8 2004/06/09 18:07:03 christos Exp $	*/

/*
 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 1995-1999 by Internet Software Consortium.
 *
 * 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 ISC DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC 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/param.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/types.h>

#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <netinet/in.h>

#include <ctype.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "resolv_private.h"

extern const char* const _res_opcodes[] = {
        "QUERY",  "IQUERY", "CQUERYM", "CQUERYU", /* experimental */
        "NOTIFY",                                 /* experimental */
        "UPDATE", "6",      "7",       "8",        "9",       "10",
        "11",     "12",     "13",      "ZONEINIT", "ZONEREF",
};

extern struct __res_state _nres;

#define res_need_init() ((_nres.options & RES_INIT) == 0U)

int res_init(void) {
    int rv;

    /*
     * These three fields used to be statically initialized.  This made
     * it hard to use this code in a shared library.  It is necessary,
     * now that we're doing dynamic initialization here, that we preserve
     * the old semantics: if an application modifies one of these three
     * fields of _res before res_init() is called, res_init() will not
     * alter them.  Of course, if an application is setting them to
     * _zero_ before calling res_init(), hoping to override what used
     * to be the static default, we can't detect it and unexpected results
     * will follow.  Zero for any of these fields would make no sense,
     * so one can safely assume that the applications were already getting
     * unexpected results.
     *
     * _nres.options is tricky since some apps were known to diddle the bits
     * before res_init() was first called. We can't replicate that semantic
     * with dynamic initialization (they may have turned bits off that are
     * set in RES_DEFAULT).  Our solution is to declare such applications
     * "broken".  They could fool us by setting RES_INIT but none do (yet).
     */
    if (!_nres.retrans) _nres.retrans = RES_TIMEOUT;
    if (!_nres.retry) _nres.retry = 4;
    if (!(_nres.options & RES_INIT)) _nres.options = RES_DEFAULT;

    /*
     * This one used to initialize implicitly to zero, so unless the app
     * has set it to something in particular, we can randomize it now.
     */
    if (!_nres.id) _nres.id = res_randomid();

    rv = res_vinit(&_nres, 1);
    return rv;
}

int res_mkquery(int op,                 // opcode of query
                const char* dname,      // domain name
                int cl, int type,       // class and type of query
                const u_char* data,     // resource record data
                int datalen,            // length of data
                const u_char* newrr_in, // new rr for modify or append
                u_char* buf,            // buffer to put query
                int buflen)             // size of buffer
{
    if (res_need_init() && res_init() == -1) {
        RES_SET_H_ERRNO(&_nres, NETDB_INTERNAL);
        return -1;
    }
    return res_nmkquery(&_nres, op, dname, cl, type, data, datalen, newrr_in, buf, buflen);
}

int res_query(const char* name,    // domain name
              int cl, int type,    // class and type of query
              u_char* answer,      // buffer to put answer
              int anslen)          // size of answer buffer
{
    if (res_need_init() && res_init() == -1) {
        RES_SET_H_ERRNO(&_nres, NETDB_INTERNAL);
        return -1;
    }
    return res_nquery(&_nres, name, cl, type, answer, anslen);
}

int res_send(const u_char* buf, int buflen, u_char* ans, int anssiz) {
    if (res_need_init() && res_init() == -1) {
        /* errno should have been set by res_init() in this case. */
        return -1;
    }

    return res_nsend(&_nres, buf, buflen, ans, anssiz);
}

int res_search(const char* name,    // domain name
               int cl, int type,    // class and type of query
               u_char* answer,      // buffer to put answer
               int anslen)          // size of answer
{
    if (res_need_init() && res_init() == -1) {
        RES_SET_H_ERRNO(&_nres, NETDB_INTERNAL);
        return -1;
    }

    return res_nsearch(&_nres, name, cl, type, answer, anslen);
}