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path: root/src/mongo/util/dns_query.cpp
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/**
 *    Copyright (C) 2017 MongoDB Inc.
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the GNU Affero General Public License, version 3,
 *    as published by the Free Software Foundation.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    GNU Affero General Public License for more details.
 *
 *    You should have received a copy of the GNU Affero General Public License
 *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the GNU Affero General Public License in all respects for
 *    all of the code used other than as permitted herein. If you modify file(s)
 *    with this exception, you may extend this exception to your version of the
 *    file(s), but you are not obligated to do so. If you do not wish to do so,
 *    delete this exception statement from your version. If you delete this
 *    exception statement from all source files in the program, then also delete
 *    it in the license file.
 */

#include "mongo/platform/basic.h"

#include "mongo/util/dns_query.h"

#include <array>
#include <cassert>
#include <cstdint>
#include <exception>
#include <iostream>
#include <memory>
#include <sstream>
#include <stdexcept>
#include <string>
#include <vector>

#include <boost/noncopyable.hpp>

// It is safe to include the implementation "headers" in an anonymous namespace, as the code is
// meant to live in a single TU -- this one.  Include one of these headers last.
#define MONGO_UTIL_DNS_QUERY_PLATFORM_INCLUDE_WHITELIST
#ifdef WIN32
#include "mongo/util/dns_query_windows-impl.h"
#else
#include "mongo/util/dns_query_posix-impl.h"
#endif
#undef MONGO_UTIL_DNS_QUERY_PLATFORM_INCLUDE_WHITELIST

using std::begin;
using std::end;
using namespace std::literals::string_literals;

namespace mongo {

/**
 * Returns a string with the IP address or domain name listed...
 */
std::vector<std::string> dns::lookupARecords(const std::string& service) {
    DNSQueryState dnsQuery;
    auto response = dnsQuery.lookup(service, DNSQueryClass::kInternet, DNSQueryType::kAddress);

    if (response.size() == 0) {
        throw DBException(ErrorCodes::DNSProtocolError,
                          "Looking up " + service + " A record yielded no results.");
    }

    std::vector<std::string> rv;
    std::transform(begin(response), end(response), back_inserter(rv), [](const auto& entry) {
        return entry.addressEntry();
    });

    return rv;
}

std::vector<dns::SRVHostEntry> dns::lookupSRVRecords(const std::string& service) {
    DNSQueryState dnsQuery;

    auto response = dnsQuery.lookup(service, DNSQueryClass::kInternet, DNSQueryType::kSRV);

    std::vector<SRVHostEntry> rv;

    std::transform(begin(response), end(response), back_inserter(rv), [](const auto& entry) {
        return entry.srvHostEntry();
    });
    return rv;
}

std::vector<std::string> dns::lookupTXTRecords(const std::string& service) {
    DNSQueryState dnsQuery;

    auto response = dnsQuery.lookup(service, DNSQueryClass::kInternet, DNSQueryType::kTXT);

    std::vector<std::string> rv;

    for (auto& entry : response) {
        auto txtEntry = entry.txtEntry();
        rv.insert(end(rv),
                  std::make_move_iterator(begin(txtEntry)),
                  std::make_move_iterator(end(txtEntry)));
    }
    return rv;
}

std::vector<std::string> dns::getTXTRecords(const std::string& service) try {
    return lookupTXTRecords(service);
} catch (const DBException& ex) {
    if (ex.code() == ErrorCodes::DNSHostNotFound) {
        return {};
    }
    throw;
}
}  // namespace mongo