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/*
 * Copyright (c) 2010-2019 Isode Limited.
 * All rights reserved.
 * See the COPYING file for more information.
 */

#include <boost/asio.hpp>

#include <Swiften/Network/PlatformDomainNameServiceQuery.h>

#pragma GCC diagnostic ignored "-Wold-style-cast"

#include <Swiften/Base/Platform.h>
#include <stdlib.h>
#include <boost/numeric/conversion/cast.hpp>
#ifdef SWIFTEN_PLATFORM_WINDOWS
#undef UNICODE
#include <windows.h>
#include <windns.h>
#ifndef DNS_TYPE_SRV
#define DNS_TYPE_SRV 33
#endif
#else
#include <arpa/nameser.h>
#include <arpa/nameser_compat.h>
#include <resolv.h>
#endif
#include <boost/bind.hpp>

#include <Swiften/Base/ByteArray.h>
#include <Swiften/EventLoop/EventLoop.h>
#include <Swiften/Base/Log.h>
#include <Swiften/Base/StdRandomGenerator.h>
#include <Swiften/Network/PlatformDomainNameResolver.h>

using namespace Swift;

namespace Swift {

PlatformDomainNameServiceQuery::PlatformDomainNameServiceQuery(const boost::optional<std::string>& serviceName, EventLoop* eventLoop, PlatformDomainNameResolver* resolver) : PlatformDomainNameQuery(resolver), eventLoop(eventLoop), serviceValid(false) {
    if (!!serviceName) {
        service = *serviceName;
        serviceValid = true;
    }
}

PlatformDomainNameServiceQuery::~PlatformDomainNameServiceQuery() {

}

void PlatformDomainNameServiceQuery::run() {
    getResolver()->addQueryToQueue(shared_from_this());
}

void PlatformDomainNameServiceQuery::runBlocking() {
    if (!serviceValid) {
        emitError();
        return;
    }

    SWIFT_LOG(debug) << "Querying " << service;

    std::vector<DomainNameServiceQuery::Result> records;

#if defined(SWIFTEN_PLATFORM_WINDOWS)
    DNS_RECORD* responses;
    // FIXME: This conversion doesn't work if unicode is deffed above
    if (DnsQuery(service.c_str(), DNS_TYPE_SRV, DNS_QUERY_STANDARD, NULL, &responses, NULL) != ERROR_SUCCESS) {
        emitError();
        return;
    }

    DNS_RECORD* currentEntry = responses;
    while (currentEntry) {
        if (currentEntry->wType == DNS_TYPE_SRV) {
            DomainNameServiceQuery::Result record;
            record.priority = currentEntry->Data.SRV.wPriority;
            record.weight = currentEntry->Data.SRV.wWeight;
            record.port = currentEntry->Data.SRV.wPort;

            // The pNameTarget is actually a PCWSTR, so I would have expected this
            // conversion to not work at all, but it does.
            // Actually, it doesn't. Fix this and remove explicit cast
            // Remove unicode undef above as well
            record.hostname = std::string((const char*) currentEntry->Data.SRV.pNameTarget);
            records.push_back(record);
        }
        currentEntry = currentEntry->pNext;
    }
    DnsRecordListFree(responses, DnsFreeRecordList);

#else
    // Make sure we reinitialize the domain list every time
    res_init();

    ByteArray response;
    response.resize(NS_PACKETSZ);
    int responseLength = res_query(const_cast<char*>(service.c_str()), ns_c_in, ns_t_srv, reinterpret_cast<u_char*>(vecptr(response)), response.size());
    if (responseLength == -1) {
        SWIFT_LOG(debug) << "Error";
        emitError();
        return;
    }

    // Parse header
    HEADER* header = reinterpret_cast<HEADER*>(vecptr(response));
    unsigned char* messageStart = vecptr(response);
    unsigned char* messageEnd = messageStart + responseLength;
    unsigned char* currentEntry = messageStart + NS_HFIXEDSZ;

    // Skip over the queries
    int queriesCount = ntohs(header->qdcount);
    while (queriesCount > 0) {
        int entryLength = dn_skipname(currentEntry, messageEnd);
        if (entryLength < 0) {
            emitError();
            return;
        }
        currentEntry += entryLength + NS_QFIXEDSZ;
        queriesCount--;
    }

    // Process the SRV answers
    int answersCount = ntohs(header->ancount);
    while (answersCount > 0) {
        DomainNameServiceQuery::Result record;

        int entryLength = dn_skipname(currentEntry, messageEnd);
        currentEntry += entryLength;
        currentEntry += NS_RRFIXEDSZ;

        try {
            // Priority
            if (currentEntry + 2 >= messageEnd) {
                emitError();
                return;
            }
            record.priority = boost::numeric_cast<int>(ns_get16(currentEntry));
            currentEntry += 2;

            // Weight
            if (currentEntry + 2 >= messageEnd) {
                emitError();
                return;
            }
            record.weight = boost::numeric_cast<int>(ns_get16(currentEntry));
            currentEntry += 2;

            // Port
            if (currentEntry + 2 >= messageEnd) {
                emitError();
                return;
            }
            record.port = boost::numeric_cast<unsigned short>(ns_get16(currentEntry));
            currentEntry += 2;

            // Hostname
            if (currentEntry >= messageEnd) {
                emitError();
                return;
            }
        }
        catch (const boost::numeric::bad_numeric_cast&) {
            emitError();
            return;
        }

        ByteArray entry;
        entry.resize(NS_MAXDNAME);
        entryLength = dn_expand(messageStart, messageEnd, currentEntry, reinterpret_cast<char*>(vecptr(entry)), entry.size());
        if (entryLength < 0) {
            emitError();
            return;
        }
        record.hostname = std::string(reinterpret_cast<const char*>(vecptr(entry)));
        records.push_back(record);
        currentEntry += entryLength;
        answersCount--;
    }
#endif

    StdRandomGenerator generator;
    DomainNameServiceQuery::sortResults(records, generator);
    //std::cout << "Sending out " << records.size() << " SRV results " << std::endl;
    eventLoop->postEvent(boost::bind(boost::ref(onResult), records), shared_from_this());
}

void PlatformDomainNameServiceQuery::emitError() {
    eventLoop->postEvent(boost::bind(boost::ref(onResult), std::vector<DomainNameServiceQuery::Result>()), shared_from_this());
}

}