summaryrefslogtreecommitdiff
path: root/src/mongo/transport/session_asio.h
blob: 99a0804ecb8174481e53f96fa1f18b4648341dca (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
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
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
/**
 *    Copyright (C) 2018-present MongoDB, Inc.
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the Server Side Public License, version 1,
 *    as published by MongoDB, Inc.
 *
 *    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
 *    Server Side Public License for more details.
 *
 *    You should have received a copy of the Server Side Public License
 *    along with this program. If not, see
 *    <http://www.mongodb.com/licensing/server-side-public-license>.
 *
 *    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 Server Side 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.
 */

#pragma once

#include <utility>

#include "mongo/base/system_error.h"
#include "mongo/config.h"
#include "mongo/db/stats/counters.h"
#include "mongo/transport/asio_utils.h"
#include "mongo/transport/baton.h"
#include "mongo/transport/transport_layer_asio.h"
#include "mongo/util/fail_point.h"
#include "mongo/util/net/socket_utils.h"
#ifdef MONGO_CONFIG_SSL
#include "mongo/util/net/ssl_manager.h"
#include "mongo/util/net/ssl_types.h"
#endif

#include "asio.hpp"
#ifdef MONGO_CONFIG_SSL
#include "mongo/util/net/ssl.hpp"
#endif

namespace mongo {
namespace transport {

MONGO_FAIL_POINT_DEFINE(transportLayerASIOshortOpportunisticReadWrite);

template <typename SuccessValue>
auto futurize(const std::error_code& ec, SuccessValue&& successValue) {
    using Result = Future<std::decay_t<SuccessValue>>;
    if (MONGO_unlikely(ec)) {
        return Result::makeReady(errorCodeToStatus(ec));
    }
    return Result::makeReady(successValue);
}

Future<void> futurize(const std::error_code& ec) {
    using Result = Future<void>;
    if (MONGO_unlikely(ec)) {
        return Result::makeReady(errorCodeToStatus(ec));
    }
    return Result::makeReady();
}

using GenericSocket = asio::generic::stream_protocol::socket;

class TransportLayerASIO::ASIOSession final : public Session {
    ASIOSession(const ASIOSession&) = delete;
    ASIOSession& operator=(const ASIOSession&) = delete;

public:
    // If the socket is disconnected while any of these options are being set, this constructor
    // may throw, but it is guaranteed to throw a mongo DBException.
    ASIOSession(TransportLayerASIO* tl, GenericSocket socket, bool isIngressSession) try
        : _socket(std::move(socket)),
          _tl(tl),
          _isIngressSession(isIngressSession) {
        auto family = endpointToSockAddr(_socket.local_endpoint()).getType();
        if (family == AF_INET || family == AF_INET6) {
            _socket.set_option(asio::ip::tcp::no_delay(true));
            _socket.set_option(asio::socket_base::keep_alive(true));
            setSocketKeepAliveParams(_socket.native_handle());
        }

        _localAddr = endpointToSockAddr(_socket.local_endpoint());
        _remoteAddr = endpointToSockAddr(_socket.remote_endpoint());
        _local = HostAndPort(_localAddr.toString(true));
        _remote = HostAndPort(_remoteAddr.toString(true));
    } catch (const DBException&) {
        throw;
    } catch (const asio::system_error& error) {
        uasserted(ErrorCodes::SocketException, error.what());
    } catch (...) {
        uasserted(50797, str::stream() << "Unknown exception while configuring socket.");
    }

    ~ASIOSession() {
        end();
    }

    TransportLayer* getTransportLayer() const override {
        return _tl;
    }

    const HostAndPort& remote() const override {
        return _remote;
    }

    const HostAndPort& local() const override {
        return _local;
    }

    const SockAddr& remoteAddr() const override {
        return _remoteAddr;
    }

    const SockAddr& localAddr() const override {
        return _localAddr;
    }

    void end() override {
        if (getSocket().is_open()) {
            std::error_code ec;
            getSocket().shutdown(GenericSocket::shutdown_both, ec);
            if ((ec) && (ec != asio::error::not_connected)) {
                error() << "Error shutting down socket: " << ec.message();
            }
        }
    }

    StatusWith<Message> sourceMessage() override {
        ensureSync();
        return sourceMessageImpl().getNoThrow();
    }

    Future<Message> asyncSourceMessage(const BatonHandle& baton = nullptr) override {
        ensureAsync();
        return sourceMessageImpl(baton);
    }

    Status sinkMessage(Message message) override {
        ensureSync();

        return write(asio::buffer(message.buf(), message.size()))
            .then([this, &message] {
                if (_isIngressSession) {
                    networkCounter.hitPhysicalOut(message.size());
                }
            })
            .getNoThrow();
    }

    Future<void> asyncSinkMessage(Message message, const BatonHandle& baton = nullptr) override {
        ensureAsync();
        return write(asio::buffer(message.buf(), message.size()), baton)
            .then([this, message /*keep the buffer alive*/]() {
                if (_isIngressSession) {
                    networkCounter.hitPhysicalOut(message.size());
                }
            });
    }

    void cancelAsyncOperations(const BatonHandle& baton = nullptr) override {
        LOG(3) << "Cancelling outstanding I/O operations on connection to " << _remote;
        if (baton && baton->networking()) {
            baton->networking()->cancelSession(*this);
        } else {
            getSocket().cancel();
        }
    }

    void setTimeout(boost::optional<Milliseconds> timeout) override {
        invariant(!timeout || timeout->count() > 0);
        _configuredTimeout = timeout;
    }

    bool isConnected() override {
        // socket.is_open() only returns whether the socket is a valid file descriptor and
        // if we haven't marked this socket as closed already.
        if (!getSocket().is_open())
            return false;

        auto swPollEvents = pollASIOSocket(getSocket(), POLLIN, Milliseconds{0});
        if (!swPollEvents.isOK()) {
            if (swPollEvents != ErrorCodes::NetworkTimeout) {
                warning() << "Failed to poll socket for connectivity check: "
                          << swPollEvents.getStatus();
                return false;
            }
            return true;
        }

        auto revents = swPollEvents.getValue();
        if (revents & POLLIN) {
            char testByte;
            int size = ::recv(getSocket().native_handle(), &testByte, sizeof(testByte), MSG_PEEK);
            if (size == sizeof(testByte)) {
                return true;
            } else if (size == -1) {
                auto errDesc = errnoWithDescription(errno);
                warning() << "Failed to check socket connectivity: " << errDesc;
            }
            // If size == 0 then we got disconnected and we should return false.
        }

        return false;
    }

protected:
    friend class TransportLayerASIO;
    friend TransportLayerASIO::BatonASIO;

#ifdef MONGO_CONFIG_SSL
    // The unique_lock here is held by TransportLayerASIO to synchronize with the asyncConnect
    // timeout callback. It will be unlocked before the SSL actually handshake begins.
    Future<void> handshakeSSLForEgressWithLock(stdx::unique_lock<stdx::mutex> lk,
                                               const HostAndPort& target) {
        if (!_tl->_egressSSLContext) {
            return Future<void>::makeReady(Status(ErrorCodes::SSLHandshakeFailed,
                                                  "SSL requested but SSL support is disabled"));
        }

        _sslSocket.emplace(
            std::move(_socket), *_tl->_egressSSLContext, removeFQDNRoot(target.host()));
        lk.unlock();

        auto doHandshake = [&] {
            if (_blockingMode == Sync) {
                std::error_code ec;
                _sslSocket->handshake(asio::ssl::stream_base::client, ec);
                return futurize(ec);
            } else {
                return _sslSocket->async_handshake(asio::ssl::stream_base::client, UseFuture{});
            }
        };
        return doHandshake().then([this, target] {
            _ranHandshake = true;

            SSLPeerInfo::forSession(shared_from_this()) =
                uassertStatusOK(getSSLManager()->parseAndValidatePeerCertificate(
                    _sslSocket->native_handle(), target.host(), target));

        });
    }

    // For synchronous connections where we don't have an async timer, just take a dummy lock and
    // pass it to the WithLock version of handshakeSSLForEgress
    Future<void> handshakeSSLForEgress(const HostAndPort& target) {
        stdx::mutex mutex;
        return handshakeSSLForEgressWithLock(stdx::unique_lock<stdx::mutex>(mutex), target);
    }
#endif

    void ensureSync() {
        asio::error_code ec;
        if (_blockingMode != Sync) {
            getSocket().non_blocking(false, ec);
            fassert(40490, errorCodeToStatus(ec));
            _blockingMode = Sync;
        }

        if (_socketTimeout != _configuredTimeout) {
            // Change boost::none (which means no timeout) into a zero value for the socket option,
            // which also means no timeout.
            auto timeout = _configuredTimeout.value_or(Milliseconds{0});
            getSocket().set_option(ASIOSocketTimeoutOption<SO_SNDTIMEO>(timeout), ec);
            uassertStatusOK(errorCodeToStatus(ec));

            getSocket().set_option(ASIOSocketTimeoutOption<SO_RCVTIMEO>(timeout), ec);
            uassertStatusOK(errorCodeToStatus(ec));

            _socketTimeout = _configuredTimeout;
        }
    }

    void ensureAsync() {
        if (_blockingMode == Async)
            return;

        // Socket timeouts currently only effect synchronous calls, so make sure the caller isn't
        // expecting a socket timeout when they do an async operation.
        invariant(!_configuredTimeout);

        asio::error_code ec;
        getSocket().non_blocking(true, ec);
        fassert(50706, errorCodeToStatus(ec));
        _blockingMode = Async;
    }

private:
    template <int Name>
    class ASIOSocketTimeoutOption {
    public:
#ifdef _WIN32
        using TimeoutType = DWORD;

        ASIOSocketTimeoutOption(Milliseconds timeoutVal) : _timeout(timeoutVal.count()) {}

#else
        using TimeoutType = timeval;

        ASIOSocketTimeoutOption(Milliseconds timeoutVal) {
            _timeout.tv_sec = duration_cast<Seconds>(timeoutVal).count();
            const auto minusSeconds = timeoutVal - Seconds{_timeout.tv_sec};
            _timeout.tv_usec = duration_cast<Microseconds>(minusSeconds).count();
        }
#endif

        template <typename Protocol>
        int name(const Protocol&) const {
            return Name;
        }

        template <typename Protocol>
        const TimeoutType* data(const Protocol&) const {
            return &_timeout;
        }

        template <typename Protocol>
        std::size_t size(const Protocol&) const {
            return sizeof(_timeout);
        }

        template <typename Protocol>
        int level(const Protocol&) const {
            return SOL_SOCKET;
        }

    private:
        TimeoutType _timeout;
    };

    GenericSocket& getSocket() {
#ifdef MONGO_CONFIG_SSL
        if (_sslSocket) {
            return static_cast<GenericSocket&>(_sslSocket->lowest_layer());
        }
#endif
        return _socket;
    }

    Future<Message> sourceMessageImpl(const BatonHandle& baton = nullptr) {
        static constexpr auto kHeaderSize = sizeof(MSGHEADER::Value);

        auto headerBuffer = SharedBuffer::allocate(kHeaderSize);
        auto ptr = headerBuffer.get();
        return read(asio::buffer(ptr, kHeaderSize), baton)
            .then([ headerBuffer = std::move(headerBuffer), this, baton ]() mutable {
                if (checkForHTTPRequest(asio::buffer(headerBuffer.get(), kHeaderSize))) {
                    return sendHTTPResponse(baton);
                }

                const auto msgLen = size_t(MSGHEADER::View(headerBuffer.get()).getMessageLength());
                if (msgLen < kHeaderSize || msgLen > MaxMessageSizeBytes) {
                    StringBuilder sb;
                    sb << "recv(): message msgLen " << msgLen << " is invalid. "
                       << "Min " << kHeaderSize << " Max: " << MaxMessageSizeBytes;
                    const auto str = sb.str();
                    LOG(0) << str;

                    return Future<Message>::makeReady(Status(ErrorCodes::ProtocolError, str));
                }

                if (msgLen == kHeaderSize) {
                    // This probably isn't a real case since all (current) messages have bodies.
                    if (_isIngressSession) {
                        networkCounter.hitPhysicalIn(msgLen);
                    }
                    return Future<Message>::makeReady(Message(std::move(headerBuffer)));
                }

                auto buffer = SharedBuffer::allocate(msgLen);
                memcpy(buffer.get(), headerBuffer.get(), kHeaderSize);

                MsgData::View msgView(buffer.get());
                return read(asio::buffer(msgView.data(), msgView.dataLen()), baton)
                    .then([ this, buffer = std::move(buffer), msgLen ]() mutable {
                        if (_isIngressSession) {
                            networkCounter.hitPhysicalIn(msgLen);
                        }
                        return Message(std::move(buffer));
                    });
            });
    }

    template <typename MutableBufferSequence>
    Future<void> read(const MutableBufferSequence& buffers, const BatonHandle& baton = nullptr) {
#ifdef MONGO_CONFIG_SSL
        if (_sslSocket) {
            return opportunisticRead(*_sslSocket, buffers, baton);
        } else if (!_ranHandshake) {
            invariant(asio::buffer_size(buffers) >= sizeof(MSGHEADER::Value));

            return opportunisticRead(_socket, buffers, baton)
                .then([this, buffers]() mutable {
                    _ranHandshake = true;
                    return maybeHandshakeSSLForIngress(buffers);
                })
                .then([this, buffers, baton](bool needsRead) mutable {
                    if (needsRead) {
                        return read(buffers, baton);
                    } else {
                        return Future<void>::makeReady();
                    }
                });
        }
#endif
        return opportunisticRead(_socket, buffers, baton);
    }

    template <typename ConstBufferSequence>
    Future<void> write(const ConstBufferSequence& buffers, const BatonHandle& baton = nullptr) {
#ifdef MONGO_CONFIG_SSL
        _ranHandshake = true;
        if (_sslSocket) {
#ifdef __linux__
            // We do some trickery in asio (see moreToSend), which appears to work well on linux,
            // but fails on other platforms.
            return opportunisticWrite(*_sslSocket, buffers, baton);
#else
            if (_blockingMode == Async) {
                // Opportunistic writes are broken for async egress SSL (switching between blocking
                // and non-blocking mode corrupts the TLS exchange).
                return asio::async_write(*_sslSocket, buffers, UseFuture{}).ignoreValue();
            } else {
                return opportunisticWrite(*_sslSocket, buffers, baton);
            }
#endif
        }
#endif
        return opportunisticWrite(_socket, buffers, baton);
    }

    template <typename Stream, typename MutableBufferSequence>
    Future<void> opportunisticRead(Stream& stream,
                                   const MutableBufferSequence& buffers,
                                   const BatonHandle& baton = nullptr) {
        std::error_code ec;
        size_t size;

        if (MONGO_FAIL_POINT(transportLayerASIOshortOpportunisticReadWrite) &&
            _blockingMode == Async) {
            asio::mutable_buffer localBuffer = buffers;

            if (buffers.size()) {
                localBuffer = asio::mutable_buffer(buffers.data(), 1);
            }

            size = asio::read(stream, localBuffer, ec);
            if (!ec && buffers.size() > 1) {
                ec = asio::error::would_block;
            }
        } else {
            size = asio::read(stream, buffers, ec);
        }

        if (((ec == asio::error::would_block) || (ec == asio::error::try_again)) &&
            (_blockingMode == Async)) {
            // asio::read is a loop internally, so some of buffers may have been read into already.
            // So we need to adjust the buffers passed into async_read to be offset by size, if
            // size is > 0.
            MutableBufferSequence asyncBuffers(buffers);
            if (size > 0) {
                asyncBuffers += size;
            }

            if (baton && baton->networking()) {
                return baton->networking()
                    ->addSession(*this, NetworkingBaton::Type::In)
                    .then([&stream, asyncBuffers, baton, this] {
                        return opportunisticRead(stream, asyncBuffers, baton);
                    });
            }

            return asio::async_read(stream, asyncBuffers, UseFuture{}).ignoreValue();
        } else {
            return futurize(ec);
        }
    }

    /**
     * moreToSend checks the ssl socket after an opportunisticWrite.  If there are still bytes to
     * send, we manually send them off the underlying socket.  Then we hook that up with a future
     * that gets us back to sending from the ssl side.
     *
     * There are two variants because we call opportunisticWrite on generic sockets and ssl sockets.
     * The generic socket impl never has more to send (because it doesn't have an inner socket it
     * needs to keep sending).
     */
    template <typename ConstBufferSequence>
    boost::optional<Future<void>> moreToSend(GenericSocket& socket,
                                             const ConstBufferSequence& buffers,
                                             const BatonHandle& baton) {
        return boost::none;
    }

#ifdef MONGO_CONFIG_SSL
    template <typename ConstBufferSequence>
    boost::optional<Future<void>> moreToSend(asio::ssl::stream<GenericSocket>& socket,
                                             const ConstBufferSequence& buffers,
                                             const BatonHandle& baton) {
        if (_sslSocket->getCoreOutputBuffer().size()) {
            return opportunisticWrite(getSocket(), _sslSocket->getCoreOutputBuffer(), baton)
                .then([this, &socket, buffers, baton] {
                    return opportunisticWrite(socket, buffers, baton);
                });
        }

        return boost::none;
    }

    boost::optional<std::string> getSniName() const override {
        return SSLPeerInfo::forSession(shared_from_this()).sniName;
    }
#endif

    template <typename Stream, typename ConstBufferSequence>
    Future<void> opportunisticWrite(Stream& stream,
                                    const ConstBufferSequence& buffers,
                                    const BatonHandle& baton = nullptr) {
        std::error_code ec;
        std::size_t size;

        if (MONGO_FAIL_POINT(transportLayerASIOshortOpportunisticReadWrite) &&
            _blockingMode == Async) {
            asio::const_buffer localBuffer = buffers;

            if (buffers.size()) {
                localBuffer = asio::const_buffer(buffers.data(), 1);
            }

            size = asio::write(stream, localBuffer, ec);
            if (!ec && buffers.size() > 1) {
                ec = asio::error::would_block;
            }
        } else {
            size = asio::write(stream, buffers, ec);
        }

        if (((ec == asio::error::would_block) || (ec == asio::error::try_again)) &&
            (_blockingMode == Async)) {

            // asio::write is a loop internally, so some of buffers may have been read into already.
            // So we need to adjust the buffers passed into async_write to be offset by size, if
            // size is > 0.
            ConstBufferSequence asyncBuffers(buffers);
            if (size > 0) {
                asyncBuffers += size;
            }

            if (auto more = moreToSend(stream, asyncBuffers, baton)) {
                return std::move(*more);
            }

            if (baton && baton->networking()) {
                return baton->networking()
                    ->addSession(*this, NetworkingBaton::Type::Out)
                    .then([&stream, asyncBuffers, baton, this] {
                        return opportunisticWrite(stream, asyncBuffers, baton);
                    });
            }

            return asio::async_write(stream, asyncBuffers, UseFuture{}).ignoreValue();
        } else {
            return futurize(ec);
        }
    }

#ifdef MONGO_CONFIG_SSL
    template <typename MutableBufferSequence>
    Future<bool> maybeHandshakeSSLForIngress(const MutableBufferSequence& buffer) {
        invariant(asio::buffer_size(buffer) >= sizeof(MSGHEADER::Value));
        MSGHEADER::ConstView headerView(asio::buffer_cast<char*>(buffer));
        auto responseTo = headerView.getResponseToMsgId();

        if (checkForHTTPRequest(buffer)) {
            return Future<bool>::makeReady(false);
        }
        // This logic was taken from the old mongo/util/net/sock.cpp.
        //
        // It lets us run both TLS and unencrypted mongo over the same port.
        //
        // The first message received from the client should have the responseTo field of the wire
        // protocol message needs to be 0 or -1. Otherwise the connection is either sending
        // garbage or a TLS Hello packet which will be caught by the TLS handshake.
        if (responseTo != 0 && responseTo != -1) {
            if (!_tl->_ingressSSLContext) {
                return Future<bool>::makeReady(
                    Status(ErrorCodes::SSLHandshakeFailed,
                           "SSL handshake received but server is started without SSL support"));
            }

            auto tlsAlert = checkTLSRequest(buffer);
            if (tlsAlert) {
                return opportunisticWrite(getSocket(),
                                          asio::buffer(tlsAlert->data(), tlsAlert->size()))
                    .then([] {
                        return Future<bool>::makeReady(
                            Status(ErrorCodes::SSLHandshakeFailed,
                                   "SSL handshake failed, as client requested disabled protocol"));
                    });
            }

            _sslSocket.emplace(std::move(_socket), *_tl->_ingressSSLContext, "");
            auto doHandshake = [&] {
                if (_blockingMode == Sync) {
                    std::error_code ec;
                    _sslSocket->handshake(asio::ssl::stream_base::server, buffer, ec);
                    return futurize(ec, asio::buffer_size(buffer));
                } else {
                    return _sslSocket->async_handshake(
                        asio::ssl::stream_base::server, buffer, UseFuture{});
                }
            };
            return doHandshake().then([this](size_t size) {
                auto& sslPeerInfo = SSLPeerInfo::forSession(shared_from_this());

                if (sslPeerInfo.subjectName.empty()) {
                    sslPeerInfo = uassertStatusOK(getSSLManager()->parseAndValidatePeerCertificate(
                        _sslSocket->native_handle(), "", _remote));
                }
                return true;
            });
        } else if (_tl->_sslMode() == SSLParams::SSLMode_requireSSL) {
            uasserted(ErrorCodes::SSLHandshakeFailed,
                      "The server is configured to only allow SSL connections");
        } else {
            if (!sslGlobalParams.disableNonSSLConnectionLogging &&
                _tl->_sslMode() == SSLParams::SSLMode_preferSSL) {
                LOG(0) << "SSL mode is set to 'preferred' and connection " << id() << " to "
                       << remote() << " is not using SSL.";
            }
            return Future<bool>::makeReady(false);
        }
    }
#endif

    template <typename Buffer>
    bool checkForHTTPRequest(const Buffer& buffers) {
        invariant(asio::buffer_size(buffers) >= 4);
        const StringData bufferAsStr(asio::buffer_cast<const char*>(buffers), 4);
        return (bufferAsStr == "GET "_sd);
    }

    // Called from read() to send an HTTP response back to a client that's trying to use HTTP
    // over a native MongoDB port. This returns a Future<Message> to match its only caller, but it
    // always contains an error, so it could really return Future<Anything>
    Future<Message> sendHTTPResponse(const BatonHandle& baton = nullptr) {
        constexpr auto userMsg =
            "It looks like you are trying to access MongoDB over HTTP"
            " on the native driver port.\r\n"_sd;

        static const std::string httpResp = str::stream() << "HTTP/1.0 200 OK\r\n"
                                                             "Connection: close\r\n"
                                                             "Content-Type: text/plain\r\n"
                                                             "Content-Length: "
                                                          << userMsg.size() << "\r\n\r\n"
                                                          << userMsg;

        return write(asio::buffer(httpResp.data(), httpResp.size()), baton)
            .onError(
                [](const Status& status) {
                    return Status(
                        ErrorCodes::ProtocolError,
                        str::stream()
                            << "Client sent an HTTP request over a native MongoDB connection, "
                               "but there was an error sending a response: "
                            << status.toString());
                })
            .then([] {
                return StatusWith<Message>(
                    ErrorCodes::ProtocolError,
                    "Client sent an HTTP request over a native MongoDB connection");
            });
    }

    enum BlockingMode {
        Unknown,
        Sync,
        Async,
    };

    BlockingMode _blockingMode = Unknown;

    HostAndPort _remote;
    HostAndPort _local;

    SockAddr _remoteAddr;
    SockAddr _localAddr;

    boost::optional<Milliseconds> _configuredTimeout;
    boost::optional<Milliseconds> _socketTimeout;

    GenericSocket _socket;
#ifdef MONGO_CONFIG_SSL
    boost::optional<asio::ssl::stream<decltype(_socket)>> _sslSocket;
    bool _ranHandshake = false;
#endif

    TransportLayerASIO* const _tl;
    bool _isIngressSession;
};

}  // namespace transport
}  // namespace mongo