/**
 *    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.
 */

#include "mongo/platform/basic.h"

#include "mongo/util/net/sock.h"

#ifndef _WIN32
#include <netdb.h>
#include <sys/socket.h>
#include <sys/types.h>
#endif

#include "mongo/db/server_options.h"
#include "mongo/stdx/thread.h"
#include "mongo/unittest/unittest.h"
#include "mongo/util/concurrency/notification.h"
#include "mongo/util/fail_point.h"
#include "mongo/util/net/socket_exception.h"

namespace {

using namespace mongo;
using std::shared_ptr;

typedef std::shared_ptr<Socket> SocketPtr;
typedef std::pair<SocketPtr, SocketPtr> SocketPair;

// On UNIX, make a connected pair of PF_LOCAL (aka PF_UNIX) sockets via the native 'socketpair'
// call. The 'type' parameter should be one of SOCK_STREAM, SOCK_DGRAM, SOCK_SEQPACKET, etc.
// For Win32, we don't have a native socketpair function, so we hack up a connected PF_INET
// pair on a random port.
SocketPair socketPair(int type, int protocol = 0);

#if defined(_WIN32)
namespace detail {
void awaitAccept(SOCKET* acceptSock, SOCKET listenSock, Notification<void>& notify) {
    *acceptSock = INVALID_SOCKET;
    const SOCKET result = ::accept(listenSock, nullptr, 0);
    if (result != INVALID_SOCKET) {
        *acceptSock = result;
    }
    notify.set();
}

void awaitConnect(SOCKET* connectSock, const struct addrinfo& where, Notification<void>& notify) {
    *connectSock = INVALID_SOCKET;
    SOCKET newSock = ::socket(where.ai_family, where.ai_socktype, where.ai_protocol);
    if (newSock != INVALID_SOCKET) {
        int result = ::connect(newSock, where.ai_addr, where.ai_addrlen);
        if (result == 0) {
            *connectSock = newSock;
        }
    }
    notify.set();
}
}  // namespace detail

SocketPair socketPair(const int type, const int protocol) {
    const int domain = PF_INET;

    // Create a listen socket and a connect socket.
    const SOCKET listenSock = ::socket(domain, type, protocol);
    if (listenSock == INVALID_SOCKET)
        return SocketPair();

    // Bind the listen socket on port zero, it will pick one for us, and start it listening
    // for connections.
    struct addrinfo hints, *res;
    ::memset(&hints, 0, sizeof(hints));
    hints.ai_family = PF_INET;
    hints.ai_socktype = type;
    hints.ai_flags = AI_PASSIVE;

    int result = ::getaddrinfo(nullptr, "0", &hints, &res);
    if (result != 0) {
        closesocket(listenSock);
        return SocketPair();
    }

    result = ::bind(listenSock, res->ai_addr, res->ai_addrlen);
    if (result != 0) {
        closesocket(listenSock);
        ::freeaddrinfo(res);
        return SocketPair();
    }

    // Read out the port to which we bound.
    sockaddr_in bindAddr;
    ::socklen_t len = sizeof(bindAddr);
    ::memset(&bindAddr, 0, sizeof(bindAddr));
    result = ::getsockname(listenSock, reinterpret_cast<struct sockaddr*>(&bindAddr), &len);
    if (result != 0) {
        closesocket(listenSock);
        ::freeaddrinfo(res);
        return SocketPair();
    }

    result = ::listen(listenSock, 1);
    if (result != 0) {
        closesocket(listenSock);
        ::freeaddrinfo(res);
        return SocketPair();
    }

    struct addrinfo connectHints, *connectRes;
    ::memset(&connectHints, 0, sizeof(connectHints));
    connectHints.ai_family = PF_INET;
    connectHints.ai_socktype = type;
    std::stringstream portStream;
    portStream << ntohs(bindAddr.sin_port);
    result = ::getaddrinfo(nullptr, portStream.str().c_str(), &connectHints, &connectRes);
    if (result != 0) {
        closesocket(listenSock);
        ::freeaddrinfo(res);
        return SocketPair();
    }

    // I'd prefer to avoid trying to do this non-blocking on Windows. Just spin up some
    // threads to do the connect and acccept.

    Notification<void> accepted;
    SOCKET acceptSock = INVALID_SOCKET;
    stdx::thread acceptor([&] { detail::awaitAccept(&acceptSock, listenSock, accepted); });

    Notification<void> connected;
    SOCKET connectSock = INVALID_SOCKET;
    stdx::thread connector([&] { detail::awaitConnect(&connectSock, *connectRes, connected); });

    connected.get();
    connector.join();
    if (connectSock == INVALID_SOCKET) {
        closesocket(listenSock);
        ::freeaddrinfo(res);
        ::freeaddrinfo(connectRes);
        closesocket(acceptSock);
        closesocket(connectSock);
        return SocketPair();
    }

    accepted.get();
    acceptor.join();
    if (acceptSock == INVALID_SOCKET) {
        closesocket(listenSock);
        ::freeaddrinfo(res);
        ::freeaddrinfo(connectRes);
        closesocket(acceptSock);
        closesocket(connectSock);
        return SocketPair();
    }

    closesocket(listenSock);
    ::freeaddrinfo(res);
    ::freeaddrinfo(connectRes);

    SocketPtr first(new Socket(static_cast<int>(acceptSock), SockAddr()));
    SocketPtr second(new Socket(static_cast<int>(connectSock), SockAddr()));

    return SocketPair(first, second);
}
#else
// We can just use ::socketpair and wrap up the result in a Socket.
SocketPair socketPair(const int type, const int protocol) {
    // PF_LOCAL is the POSIX name for Unix domain sockets, while PF_UNIX
    // is the name that BSD used.  We use the BSD name because it is more
    // widely supported (e.g. Solaris 10).
    const int domain = PF_UNIX;

    int socks[2];
    const int result = ::socketpair(domain, type, protocol, socks);
    if (result == 0) {
        return SocketPair(SocketPtr(new Socket(socks[0], SockAddr())),
                          SocketPtr(new Socket(socks[1], SockAddr())));
    }
    return SocketPair();
}
#endif

// This should match the name of the fail point declared in sock.cpp.
const char kSocketFailPointName[] = "throwSockExcep";

class SocketFailPointTest : public unittest::Test {
public:
    SocketFailPointTest()
        : _failPoint(globalFailPointRegistry().find(kSocketFailPointName)),
          _sockets(socketPair(SOCK_STREAM)) {
        ASSERT_TRUE(_failPoint != nullptr);
        ASSERT_TRUE(_sockets.first);
        ASSERT_TRUE(_sockets.second);
    }

    ~SocketFailPointTest() {}

    bool trySend() {
        char byte = 'x';
        _sockets.first->send(&byte, sizeof(byte), "SocketFailPointTest::trySend");
        return true;
    }

    bool trySendVector() {
        std::vector<std::pair<char*, int>> data;
        char byte = 'x';
        data.push_back(std::make_pair(&byte, sizeof(byte)));
        _sockets.first->send(data, "SocketFailPointTest::trySendVector");
        return true;
    }

    bool tryRecv() {
        char byte;
        _sockets.second->recv(&byte, sizeof(byte));
        return true;
    }

    // You must queue at least one byte on the send socket before calling this function.
    size_t countRecvable(size_t max) {
        std::vector<char> buf(max);
        // This isn't great, because we don't have a guarantee that multiple sends will be
        // captured in one recv. However, sock doesn't let us pass flags into recv, so we
        // can't make this non blocking, and therefore can't risk another call.
        return _sockets.second->unsafe_recv(&buf[0], max);
    }

    FailPoint* const _failPoint;
    const SocketPair _sockets;
};

class ScopedFailPointEnabler {
public:
    ScopedFailPointEnabler(FailPoint& fp) : _fp(fp) {
        _fp.setMode(FailPoint::alwaysOn);
    }

    ~ScopedFailPointEnabler() {
        _fp.setMode(FailPoint::off);
    }

private:
    FailPoint& _fp;
};

TEST_F(SocketFailPointTest, TestSend) {
    ASSERT_TRUE(trySend());
    ASSERT_TRUE(tryRecv());
    {
        const ScopedFailPointEnabler enabled(*_failPoint);
        auto expectedEx =
            makeSocketError(SocketErrorKind::SEND_ERROR, _sockets.first->remoteString());
        ASSERT_THROWS_WHAT(trySend(), NetworkException, expectedEx.reason());
    }
    // Channel should be working again
    ASSERT_TRUE(trySend());
    ASSERT_TRUE(tryRecv());
}

TEST_F(SocketFailPointTest, TestSendVector) {
    ASSERT_TRUE(trySendVector());
    ASSERT_TRUE(tryRecv());
    {
        const ScopedFailPointEnabler enabled(*_failPoint);
        ASSERT_THROWS(trySendVector(), NetworkException);
    }
    ASSERT_TRUE(trySendVector());
    ASSERT_TRUE(tryRecv());
}

TEST_F(SocketFailPointTest, TestRecv) {
    ASSERT_TRUE(trySend());  // data for recv
    ASSERT_TRUE(tryRecv());
    {
        ASSERT_TRUE(trySend());  // data for recv
        const ScopedFailPointEnabler enabled(*_failPoint);
        auto expectedEx =
            makeSocketError(SocketErrorKind::RECV_ERROR, _sockets.first->remoteString());
        ASSERT_THROWS_WHAT(tryRecv(), NetworkException, expectedEx.reason());
    }
    ASSERT_TRUE(trySend());  // data for recv
    ASSERT_TRUE(tryRecv());
}

TEST_F(SocketFailPointTest, TestFailedSendsDontSend) {
    ASSERT_TRUE(trySend());
    ASSERT_TRUE(tryRecv());
    {
        ASSERT_TRUE(trySend());  // queue 1 byte
        const ScopedFailPointEnabler enabled(*_failPoint);
        // Fail to queue another byte
        ASSERT_THROWS(trySend(), NetworkException);
    }
    // Failed byte should not have been transmitted.
    ASSERT_EQUALS(size_t(1), countRecvable(2));
}

// Ensure that calling send doesn't actually enqueue data to the socket
TEST_F(SocketFailPointTest, TestFailedVectorSendsDontSend) {
    ASSERT_TRUE(trySend());
    ASSERT_TRUE(tryRecv());
    {
        ASSERT_TRUE(trySend());  // queue 1 byte
        const ScopedFailPointEnabler enabled(*_failPoint);
        // Fail to queue another byte
        ASSERT_THROWS(trySendVector(), NetworkException);
    }
    // Failed byte should not have been transmitted.
    ASSERT_EQUALS(size_t(1), countRecvable(2));
}

TEST_F(SocketFailPointTest, TestFailedRecvsDontRecv) {
    ASSERT_TRUE(trySend());
    ASSERT_TRUE(tryRecv());
    {
        ASSERT_TRUE(trySend());
        const ScopedFailPointEnabler enabled(*_failPoint);
        // Fail to recv that byte
        ASSERT_THROWS(tryRecv(), NetworkException);
    }
    // Failed byte should still be queued to recv.
    ASSERT_EQUALS(size_t(1), countRecvable(1));
    // Channel should be working again
    ASSERT_TRUE(trySend());
    ASSERT_TRUE(tryRecv());
}


}  // namespace
