source: mainline/uspace/srv/net/dnsrsrv/query.c@ 02a09ed

/*
 * Copyright (c) 2013 Jiri Svoboda
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup dnsres
 * @{
 */
/**
 * @file
 */

#include <errno.h>
#include <io/log.h>
#include <mem.h>
#include <stdlib.h>
#include <str.h>

#include "dns_msg.h"
#include "dns_std.h"
#include "dns_type.h"
#include "query.h"
#include "transport.h"

static uint16_t msg_id;

int dns_name2host(const char *name, dns_host_info_t **rinfo)
{
        dns_message_t *msg;
        dns_message_t *amsg;
        dns_question_t *question;
        dns_host_info_t *info;
        char *sname, *cname;
        size_t eoff;
        int rc;

        question = calloc(1, sizeof(dns_question_t));
        if (question == NULL)
                return ENOMEM;

        question->qname = (char *)name;
        question->qtype = DTYPE_A;
        question->qclass = DC_IN;

        msg = dns_message_new();
        if (msg == NULL)
                return ENOMEM;

        list_append(&question->msg, &msg->question);

        msg->id = msg_id++;
        msg->qr = QR_QUERY;
        msg->opcode = OPC_QUERY;
        msg->aa = false;
        msg->tc = false;
        msg->rd = true;
        msg->ra = false;

        rc = dns_request(msg, &amsg);
        if (rc != EOK) {
                return rc;
        }

        /* Start with the caller-provided name */
        sname = str_dup(name);

        list_foreach(amsg->answer, link) {
                dns_rr_t *rr = list_get_instance(link, dns_rr_t, msg);

                log_msg(LOG_DEFAULT, LVL_DEBUG, " - '%s' %u/%u, dsize %zu",
                        rr->name, rr->rtype, rr->rclass, rr->rdata_size);

                if (rr->rtype == DTYPE_CNAME && rr->rclass == DC_IN &&
                    str_cmp(rr->name, sname) == 0) {
                        log_msg(LOG_DEFAULT, LVL_DEBUG, "decode cname (%p, %zu, %zu)",
                            amsg->pdu.data, amsg->pdu.size, rr->roff);
                        rc = dns_name_decode(&amsg->pdu, rr->roff, &cname, &eoff);
                        if (rc != EOK) {
                                log_msg(LOG_DEFAULT, LVL_DEBUG,
                                    "error decoding cname");
                                assert(rc == EINVAL || rc == ENOMEM);
                                dns_message_destroy(msg);
                                dns_message_destroy(amsg);
                                return rc;
                        }

                        log_msg(LOG_DEFAULT, LVL_DEBUG, "name = '%s' "
                            "cname = '%s'", sname, cname);

                        free(sname);
                        /* Continue looking for the more canonical name */
                        sname = cname;
                }

                if (rr->rtype == DTYPE_A && rr->rclass == DC_IN &&
                        rr->rdata_size == sizeof(uint32_t) &&
                            str_cmp(rr->name, sname) == 0) {

                        info = calloc(1, sizeof(dns_host_info_t));
                        if (info == NULL) {
                                dns_message_destroy(msg);
                                dns_message_destroy(amsg);
                                return ENOMEM;
                        }

                        info->cname = str_dup(rr->name);
                        inet_addr_set(dns_uint32_t_decode(rr->rdata, rr->rdata_size),
                            &info->addr);
                        
                        dns_message_destroy(msg);
                        dns_message_destroy(amsg);
                        *rinfo = info;
                        return EOK;
                }
        }

        dns_message_destroy(msg);
        dns_message_destroy(amsg);
        log_msg(LOG_DEFAULT, LVL_DEBUG, "'%s' not resolved, fail", sname);

        return EIO;
}

void dns_hostinfo_destroy(dns_host_info_t *info)
{
        free(info->cname);
        free(info);
}

/** @}
 */