udp_query.cc 6.18 KB
Newer Older
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
// Copyright (C) 2011  Internet Systems Consortium, Inc. ("ISC")
//
// Permission to use, copy, modify, and/or 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 <config.h>

17 18 19
// unistd is needed for asio.hpp with SunStudio
#include <unistd.h>

20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
#include <asio.hpp>

#include <boost/bind.hpp>
#include <boost/shared_array.hpp>

#include <dns/messagerenderer.h>
#include <dns/opcode.h>
#include <dns/rcode.h>

#include <log/dummylog.h>

#include <asio.hpp>

#include <asiolink.h>

35
#include <coroutine.h>
36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189
#include <asiolink/udp_endpoint.h>

#include <asiolink/udp_query.h>

using namespace asio;
using asio::ip::udp;
using asio::ip::tcp;
using isc::log::dlog;

using namespace std;
using namespace isc::dns;

namespace asiolink {


// Private UDPQuery data (see internal/udpdns.h for reasons)
struct UDPQuery::PrivateData {
    // Socket we send query to and expect reply from there
    udp::socket socket;
    // Where was the query sent
    udp::endpoint remote;
    // What we ask the server
    Question question;
    // We will store the answer here
    OutputBufferPtr buffer;
    OutputBufferPtr msgbuf;
    // Temporary buffer for answer
    boost::shared_array<char> data;
    // This will be called when the data arrive or timeouts
    Callback* callback;
    // Did we already stop operating (data arrived, we timed out, someone
    // called stop). This can be so when we are cleaning up/there are
    // still pointers to us.
    bool stopped;
    // Timer to measure timeouts.
    deadline_timer timer;
    // How many milliseconds are we willing to wait for answer?
    int timeout;

    PrivateData(io_service& service,
        const udp::socket::protocol_type& protocol, const Question &q,
        OutputBufferPtr b, Callback *c) :
        socket(service, protocol),
        question(q),
        buffer(b),
        msgbuf(new OutputBuffer(512)),
        callback(c),
        stopped(false),
        timer(service)
    { }
};

/// The following functions implement the \c UDPQuery class.
///
/// The constructor
UDPQuery::UDPQuery(io_service& io_service,
                   const Question& q, const IOAddress& addr, uint16_t port,
                   OutputBufferPtr buffer, Callback *callback, int timeout) :
    data_(new PrivateData(io_service,
        addr.getFamily() == AF_INET ? udp::v4() : udp::v6(), q, buffer,
        callback))
{
    data_->remote = UDPEndpoint(addr, port).getASIOEndpoint();
    data_->timeout = timeout;
}

/// The function operator is implemented with the "stackless coroutine"
/// pattern; see internal/coroutine.h for details.
void
UDPQuery::operator()(error_code ec, size_t length) {
    if (ec || data_->stopped) {
        return;
    }

    CORO_REENTER (this) {
        /// Generate the upstream query and render it to wire format
        /// This is done in a different scope to allow inline variable
        /// declarations.
        {
            Message msg(Message::RENDER);
            
            // XXX: replace with boost::random or some other suitable PRNG
            msg.setQid(0);
            msg.setOpcode(Opcode::QUERY());
            msg.setRcode(Rcode::NOERROR());
            msg.setHeaderFlag(Message::HEADERFLAG_RD);
            msg.addQuestion(data_->question);
            MessageRenderer renderer(*data_->msgbuf);
            msg.toWire(renderer);
            dlog("Sending " + msg.toText() + " to " +
                data_->remote.address().to_string());
        }


        // If we timeout, we stop, which will shutdown everything and
        // cancel all other attempts to run inside the coroutine
        if (data_->timeout != -1) {
            data_->timer.expires_from_now(boost::posix_time::milliseconds(
                data_->timeout));
            data_->timer.async_wait(boost::bind(&UDPQuery::stop, *this,
                TIME_OUT));
        }

        // Begin an asynchronous send, and then yield.  When the
        // send completes, we will resume immediately after this point.
        CORO_YIELD data_->socket.async_send_to(buffer(data_->msgbuf->getData(),
            data_->msgbuf->getLength()), data_->remote, *this);

        /// Allocate space for the response.  (XXX: This should be
        /// optimized by maintaining a free list of pre-allocated blocks)
        data_->data.reset(new char[MAX_LENGTH]);

        /// Begin an asynchronous receive, and yield.  When the receive
        /// completes, we will resume immediately after this point.
        CORO_YIELD data_->socket.async_receive_from(buffer(data_->data.get(),
            MAX_LENGTH), data_->remote, *this);
        // The message is not rendered yet, so we can't print it easilly
        dlog("Received response from " + data_->remote.address().to_string());

        /// Copy the answer into the response buffer.  (XXX: If the
        /// OutputBuffer object were made to meet the requirements of
        /// a MutableBufferSequence, then it could be written to directly
        /// by async_recieve_from() and this additional copy step would
        /// be unnecessary.)
        data_->buffer->writeData(data_->data.get(), length);

        /// We are done
        stop(SUCCESS);
    }
}

void
UDPQuery::stop(Result result) {
    if (!data_->stopped) {
        switch (result) {
            case TIME_OUT:
                dlog("Query timed out");
                break;
            case STOPPED:
                dlog("Query stopped");
                break;
            default:;
        }
        data_->stopped = true;
        data_->socket.cancel();
        data_->socket.close();
        data_->timer.cancel();
        if (data_->callback) {
            (*data_->callback)(result);
        }
    }
}

} // namespace asiolink