tcpserverbalancer.cpp

/*
 * SPDX-FileCopyrightText: (C) 2017-2018 Daniel Nicoletti <dantti12@gmail.com>
 * SPDX-License-Identifier: BSD-3-Clause
 */
#if defined(_WIN32)
#    ifndef _WIN32_WINNT
#        define _WIN32_WINNT 0x0601
#    endif
#    ifndef WIN32_LEAN_AND_MEAN
#        define WIN32_LEAN_AND_MEAN
#    endif
#    include <winsock2.h>
#    include <ws2tcpip.h>
#endif
 
#include "tcpserverbalancer.h"
 
#include "server.h"
#include "serverengine.h"
#include "tcpserver.h"
#include "tcpsslserver.h"
 
#include <iostream>
#include <mutex>
 
#include <QFile>
#include <QLoggingCategory>
#include <QSslKey>
 
#ifdef Q_OS_LINUX
#    include <arpa/inet.h>
#    include <fcntl.h>
#    include <sys/socket.h>
#    include <sys/types.h>
#    include <unistd.h>
#endif
 
Q_LOGGING_CATEGORY(C_SERVER_BALANCER, "cutelyst.server.tcpbalancer", QtWarningMsg)
 
using namespace Cutelyst;
 
#ifdef Q_OS_LINUX
namespace {
int listenReuse(const QHostAddress &address,
                int listenQueue,
                quint16 port,
                bool reusePort,
                bool startListening);
}
#endif
 
#ifdef Q_OS_WIN
namespace {
bool ensureWinsockInitialized(QString *errorOut)
{
    static std::once_flag once;
    static int wsaInitError = 0;
    std::call_once(once, [] {
        WSADATA wsaData;
        if (WSAStartup(MAKEWORD(2, 2), &wsaData) != 0) {
            wsaInitError = WSAGetLastError();
        }
    });
    if (wsaInitError != 0) {
        if (errorOut) {
            *errorOut = QStringLiteral("WSAStartup failed (Windows socket error %1)")
                            .arg(wsaInitError);
        }
        return false;
    }
    return true;
}
 
QString windowsSocketErrorString(int error)
{
    switch (error) {
    case WSAEADDRINUSE:
        return QStringLiteral("The bound address is already in use");
    case WSAEACCES:
        return QStringLiteral("The requested address is a protected address and requires "
                              "appropriate privileges");
    case WSAEADDRNOTAVAIL:
        return QStringLiteral("The requested address is not valid in this context");
    case WSANOTINITIALISED:
        return QStringLiteral("Winsock has not been initialized");
    default:
        return QStringLiteral("Windows socket error %1").arg(error);
    }
}
 
int listenExclusive(const QHostAddress &address, int listenQueue, quint16 port, QString *errorOut)
{
    if (!ensureWinsockInitialized(errorOut)) {
        return -1;
    }
 
    const bool ipv6 = address.protocol() == QHostAddress::IPv6Protocol ||
                      address.protocol() == QHostAddress::AnyIPProtocol;
 
    SOCKET socket =
        WSASocketW(ipv6 ? AF_INET6 : AF_INET,
                   SOCK_STREAM,
                   IPPROTO_TCP,
                   nullptr,
                   0,
                   WSA_FLAG_NO_HANDLE_INHERIT | WSA_FLAG_OVERLAPPED);
    if (socket == INVALID_SOCKET) {
        if (errorOut) {
            *errorOut = windowsSocketErrorString(WSAGetLastError());
        }
        return -1;
    }
 
    BOOL exclusive = TRUE;
    if (setsockopt(socket,
                   SOL_SOCKET,
                   SO_EXCLUSIVEADDRUSE,
                   reinterpret_cast<const char *>(&exclusive),
                   sizeof(exclusive)) != 0) {
        if (errorOut) {
            *errorOut = windowsSocketErrorString(WSAGetLastError());
        }
        closesocket(socket);
        return -1;
    }
 
    if (ipv6) {
        sockaddr_in6 sa{};
        sa.sin6_family = AF_INET6;
        sa.sin6_port   = htons(port);
        if (address.protocol() == QHostAddress::AnyIPProtocol) {
            sa.sin6_addr = in6addr_any;
        } else {
            const Q_IPV6ADDR tmp = address.toIPv6Address();
            memcpy(&sa.sin6_addr, &tmp, sizeof(tmp));
        }
        if (bind(socket, reinterpret_cast<sockaddr *>(&sa), sizeof(sa)) != 0) {
            if (errorOut) {
                *errorOut = windowsSocketErrorString(WSAGetLastError());
            }
            closesocket(socket);
            return -1;
        }
    } else {
        sockaddr_in sa{};
        sa.sin_family = AF_INET;
        sa.sin_port   = htons(port);
        if (address.protocol() == QHostAddress::Any) {
            sa.sin_addr.s_addr = INADDR_ANY;
        } else {
            sa.sin_addr.s_addr = htonl(address.toIPv4Address());
        }
        if (bind(socket, reinterpret_cast<sockaddr *>(&sa), sizeof(sa)) != 0) {
            if (errorOut) {
                *errorOut = windowsSocketErrorString(WSAGetLastError());
            }
            closesocket(socket);
            return -1;
        }
    }
 
    if (::listen(socket, listenQueue) != 0) {
        if (errorOut) {
            *errorOut = windowsSocketErrorString(WSAGetLastError());
        }
        closesocket(socket);
        return -1;
    }
 
    return static_cast<int>(socket);
}
} // namespace
#endif
 
TcpServerBalancer::TcpServerBalancer(Server *server)
    : QTcpServer(server)
    , m_server(server)
{
}
 
TcpServerBalancer::~TcpServerBalancer()
{
#ifndef QT_NO_SSL
    delete m_sslConfiguration;
#endif // QT_NO_SSL
}
 
bool TcpServerBalancer::listen(const QString &line, Protocol *protocol, bool secure)
{
    m_protocol = protocol;
 
    int commaPos                    = line.indexOf(u',');
    const QString addressPortString = line.mid(0, commaPos);
 
    QString addressString;
    int closeBracketPos = addressPortString.indexOf(u']');
    if (closeBracketPos != -1) {
        if (!line.startsWith(u'[')) {
            std::cerr << "Failed to parse address: " << qPrintable(addressPortString) << '\n';
            return false;
        }
        addressString = addressPortString.mid(1, closeBracketPos - 1);
    } else {
        addressString = addressPortString.section(u':', 0, -2);
    }
    const QString portString = addressPortString.section(u':', -1);
 
    QHostAddress address;
    if (addressString.isEmpty()) {
        address = QHostAddress(QHostAddress::Any);
    } else {
        address.setAddress(addressString);
    }
 
    bool ok;
    quint16 port = portString.toUInt(&ok);
    if (!ok || (port < 1 || port > 35554)) {
        port = 80;
    }
 
#ifndef QT_NO_SSL
    if (secure) {
        if (commaPos == -1) {
            std::cerr << "No SSL certificate specified" << '\n';
            return false;
        }
 
        const QString sslString = line.mid(commaPos + 1);
        const QString certPath  = sslString.section(u',', 0, 0);
        QFile certFile(certPath);
        if (!certFile.open(QFile::ReadOnly)) {
            std::cerr << "Failed to open SSL certificate" << qPrintable(certPath)
                      << qPrintable(certFile.errorString()) << '\n';
            return false;
        }
        QSslCertificate cert(&certFile);
        if (cert.isNull()) {
            std::cerr << "Failed to parse SSL certificate" << '\n';
            return false;
        }
 
        const QString keyPath = sslString.section(u',', 1, 1);
        QFile keyFile(keyPath);
        if (!keyFile.open(QFile::ReadOnly)) {
            std::cerr << "Failed to open SSL private key" << qPrintable(keyPath)
                      << qPrintable(keyFile.errorString()) << '\n';
            return false;
        }
 
        QSsl::KeyAlgorithm algorithm = QSsl::Rsa;
        const QString keyAlgorithm   = sslString.section(u',', 2, 2);
        if (!keyAlgorithm.isEmpty()) {
            if (keyAlgorithm.compare(u"rsa", Qt::CaseInsensitive) == 0) {
                algorithm = QSsl::Rsa;
            } else if (keyAlgorithm.compare(u"ec", Qt::CaseInsensitive) == 0) {
                algorithm = QSsl::Ec;
            } else {
                std::cerr << "Failed to select SSL Key Algorithm" << qPrintable(keyAlgorithm)
                          << '\n';
                return false;
            }
        }
 
        QSslKey key(&keyFile, algorithm);
        if (key.isNull()) {
            std::cerr << "Failed to parse SSL private key" << '\n';
            return false;
        }
 
        m_sslConfiguration = new QSslConfiguration;
        m_sslConfiguration->setLocalCertificate(cert);
        m_sslConfiguration->setPrivateKey(key);
        m_sslConfiguration->setPeerVerifyMode(
            QSslSocket::VerifyNone); // prevent asking for client certificate
        if (m_server->httpsH2()) {
            m_sslConfiguration->setAllowedNextProtocols(
                {QByteArrayLiteral("h2"), QSslConfiguration::NextProtocolHttp1_1});
        }
    }
#endif // QT_NO_SSL
 
    m_address = address;
    m_port    = port;
    m_bindError.clear();
 
#ifdef Q_OS_LINUX
    int socket = listenReuse(
        address, m_server->listenQueue(), port, m_server->reusePort(), !m_server->reusePort());
    if (socket > 0) {
        if (setSocketDescriptor(socket)) {
            pauseAccepting();
        } else {
            m_bindError = errorString();
            ::close(socket);
            qCWarning(C_SERVER_BALANCER) << "Failed to listen on TCP:" << line << m_bindError;
            return false;
        }
    } else {
        std::cerr << "Failed to listen on TCP: " << qPrintable(line) << " : "
                  << qPrintable(errorString()) << '\n';
        return false;
    }
#elif defined(Q_OS_WIN)
    int socket = listenExclusive(address, m_server->listenQueue(), port, &m_bindError);
    if (socket > 0) {
        if (setSocketDescriptor(socket)) {
            pauseAccepting();
        } else {
            if (m_bindError.isEmpty()) {
                m_bindError = errorString();
            }
            closesocket(socket);
            qCWarning(C_SERVER_BALANCER) << "Failed to listen on TCP:" << line << m_bindError;
            return false;
        }
    } else {
        qCWarning(C_SERVER_BALANCER) << "Failed to listen on TCP:" << line << m_bindError;
        return false;
    }
#else
    setListenBacklogSize(m_server->listenQueue());
    bool ret = QTcpServer::listen(address, port);
    if (ret) {
        pauseAccepting();
    } else {
        m_bindError = errorString();
        std::cerr << "Failed to listen on TCP: " << qPrintable(line) << " : "
                  << qPrintable(m_bindError) << '\n';
        return false;
    }
#endif
 
    m_serverName = serverAddress().toString().toLatin1() + ':' + QByteArray::number(port);
    return true;
}
 
namespace {
#ifdef Q_OS_LINUX
// UnixWare 7 redefines socket -> _socket
inline int qt_safe_socket(int domain, int type, int protocol, int flags = 0)
{
    Q_ASSERT((flags & ~O_NONBLOCK) == 0);
 
    int fd;
#    ifdef QT_THREADSAFE_CLOEXEC
    int newtype = type | SOCK_CLOEXEC;
    if (flags & O_NONBLOCK) {
        newtype |= SOCK_NONBLOCK;
    }
    fd = ::socket(domain, newtype, protocol);
    return fd;
#    else
    fd = ::socket(domain, type, protocol);
    if (fd == -1) {
        return -1;
    }
 
    ::fcntl(fd, F_SETFD, FD_CLOEXEC);
 
    // set non-block too?
    if (flags & O_NONBLOCK) {
        ::fcntl(fd, F_SETFL, ::fcntl(fd, F_GETFL) | O_NONBLOCK);
    }
 
    return fd;
#    endif
}
 
int createNewSocket(QAbstractSocket::NetworkLayerProtocol &socketProtocol)
{
    int protocol = 0;
 
    int domain = (socketProtocol == QAbstractSocket::IPv6Protocol ||
                  socketProtocol == QAbstractSocket::AnyIPProtocol)
                     ? AF_INET6
                     : AF_INET;
    int type   = SOCK_STREAM;
 
    int socket = qt_safe_socket(domain, type, protocol, O_NONBLOCK);
    if (socket < 0 && socketProtocol == QAbstractSocket::AnyIPProtocol && errno == EAFNOSUPPORT) {
        domain         = AF_INET;
        socket         = qt_safe_socket(domain, type, protocol, O_NONBLOCK);
        socketProtocol = QAbstractSocket::IPv4Protocol;
    }
 
    if (socket < 0) {
        int ecopy = errno;
        switch (ecopy) {
        case EPROTONOSUPPORT:
        case EAFNOSUPPORT:
        case EINVAL:
            qCDebug(C_SERVER_BALANCER)
                << "setError(QAbstractSocket::UnsupportedSocketOperationError, "
                   "ProtocolUnsupportedErrorString)";
            break;
        case ENFILE:
        case EMFILE:
        case ENOBUFS:
        case ENOMEM:
            qCDebug(C_SERVER_BALANCER)
                << "setError(QAbstractSocket::SocketResourceError, ResourceErrorString)";
            break;
        case EACCES:
            qCDebug(C_SERVER_BALANCER)
                << "setError(QAbstractSocket::SocketAccessError, AccessErrorString)";
            break;
        default:
            break;
        }
 
#    if defined(QNATIVESOCKETENGINE_DEBUG)
        qCDebug(C_SERVER_BALANCER,
                "QNativeSocketEnginePrivate::createNewSocket(%d, %d) == false (%s)",
                socketType,
                socketProtocol,
                strerror(ecopy));
#    endif
 
        return false;
    }
 
#    if defined(QNATIVESOCKETENGINE_DEBUG)
    qCDebug(C_SERVER_BALANCER,
            "QNativeSocketEnginePrivate::createNewSocket(%d, %d) == true",
            socketType,
            socketProtocol);
#    endif
 
    return socket;
}
 
union qt_sockaddr {
    sockaddr a;
    sockaddr_in a4;
    sockaddr_in6 a6;
};
 
#    define QT_SOCKLEN_T int
#    define QT_SOCKET_BIND ::bind
 
namespace SetSALen {
template <typename T>
void set(T *sa, typename std::enable_if<(&T::sa_len, true), QT_SOCKLEN_T>::type len)
{
    sa->sa_len = len;
}
template <typename T>
void set(T *sin6, typename std::enable_if<(&T::sin6_len, true), QT_SOCKLEN_T>::type len)
{
    sin6->sin6_len = len;
}
template <typename T>
void set(T *, ...)
{
}
} // namespace SetSALen
 
void setPortAndAddress(quint16 port,
                       const QHostAddress &address,
                       QAbstractSocket::NetworkLayerProtocol socketProtocol,
                       qt_sockaddr *aa,
                       int *sockAddrSize)
{
    if (address.protocol() == QAbstractSocket::IPv6Protocol ||
        address.protocol() == QAbstractSocket::AnyIPProtocol ||
        socketProtocol == QAbstractSocket::IPv6Protocol ||
        socketProtocol == QAbstractSocket::AnyIPProtocol) {
        memset(&aa->a6, 0, sizeof(sockaddr_in6));
        aa->a6.sin6_family = AF_INET6;
        // #if QT_CONFIG(networkinterface)
        //             aa->a6.sin6_scope_id = scopeIdFromString(address.scopeId());
        // #endif
        aa->a6.sin6_port = htons(port);
        Q_IPV6ADDR tmp   = address.toIPv6Address();
        memcpy(&aa->a6.sin6_addr, &tmp, sizeof(tmp));
        *sockAddrSize = sizeof(sockaddr_in6);
        SetSALen::set(&aa->a, sizeof(sockaddr_in6));
    } else {
        memset(&aa->a, 0, sizeof(sockaddr_in));
        aa->a4.sin_family      = AF_INET;
        aa->a4.sin_port        = htons(port);
        aa->a4.sin_addr.s_addr = htonl(address.toIPv4Address());
        *sockAddrSize          = sizeof(sockaddr_in);
        SetSALen::set(&aa->a, sizeof(sockaddr_in));
    }
}
 
bool nativeBind(int socketDescriptor, const QHostAddress &address, quint16 port)
{
    qt_sockaddr aa;
    int sockAddrSize;
    setPortAndAddress(port, address, address.protocol(), &aa, &sockAddrSize);
 
#    ifdef IPV6_V6ONLY
    if (aa.a.sa_family == AF_INET6) {
        int ipv6only = 0;
        if (address.protocol() == QAbstractSocket::IPv6Protocol) {
            ipv6only = 1;
        }
        // default value of this socket option varies depending on unix variant (or system
        // configuration on BSD), so always set it explicitly
        ::setsockopt(
            socketDescriptor, IPPROTO_IPV6, IPV6_V6ONLY, (char *) &ipv6only, sizeof(ipv6only));
    }
#    endif
 
    int bindResult = ::bind(socketDescriptor, &aa.a, sockAddrSize);
    if (bindResult < 0 && errno == EAFNOSUPPORT &&
        address.protocol() == QAbstractSocket::AnyIPProtocol) {
        // retry with v4
        aa.a4.sin_family      = AF_INET;
        aa.a4.sin_port        = htons(port);
        aa.a4.sin_addr.s_addr = htonl(address.toIPv4Address());
        sockAddrSize          = sizeof(aa.a4);
        bindResult            = QT_SOCKET_BIND(socketDescriptor, &aa.a, sockAddrSize);
    }
 
    if (bindResult < 0) {
#    if defined(QNATIVESOCKETENGINE_DEBUG)
        int ecopy = errno;
#    endif
        //        switch(errno) {
        //        case EADDRINUSE:
        //            setError(QAbstractSocket::AddressInUseError, AddressInuseErrorString);
        //            break;
        //        case EACCES:
        //            setError(QAbstractSocket::SocketAccessError, AddressProtectedErrorString);
        //            break;
        //        case EINVAL:
        //            setError(QAbstractSocket::UnsupportedSocketOperationError,
        //            OperationUnsupportedErrorString); break;
        //        case EADDRNOTAVAIL:
        //            setError(QAbstractSocket::SocketAddressNotAvailableError,
        //            AddressNotAvailableErrorString); break;
        //        default:
        //            break;
        //        }
 
#    if defined(QNATIVESOCKETENGINE_DEBUG)
        qCDebug(C_SERVER_BALANCER,
                "QNativeSocketEnginePrivate::nativeBind(%s, %i) == false (%s)",
                address.toString().toLatin1().constData(),
                port,
                strerror(ecopy));
#    endif
 
        return false;
    }
 
#    if defined(QNATIVESOCKETENGINE_DEBUG)
    qCDebug(C_SERVER_BALANCER,
            "QNativeSocketEnginePrivate::nativeBind(%s, %i) == true",
            address.toString().toLatin1().constData(),
            port);
#    endif
    //    socketState = QAbstractSocket::BoundState;
    return true;
}
 
int listenReuse(const QHostAddress &address,
                int listenQueue,
                quint16 port,
                bool reusePort,
                bool startListening)
{
    QAbstractSocket::NetworkLayerProtocol proto = address.protocol();
 
    int socket = createNewSocket(proto);
    if (socket < 0) {
        qCCritical(C_SERVER_BALANCER) << "Failed to create new socket";
        return -1;
    }
 
    int optval = 1;
    // SO_REUSEADDR is set by default on QTcpServer and allows to bind again
    // without having to wait all previous connections to close
    if (::setsockopt(socket, SOL_SOCKET, SO_REUSEADDR, &optval, sizeof(optval))) {
        qCCritical(C_SERVER_BALANCER) << "Failed to set SO_REUSEADDR on socket" << socket;
        return -1;
    }
 
    if (reusePort) {
        if (::setsockopt(socket, SOL_SOCKET, SO_REUSEPORT, &optval, sizeof(optval))) {
            qCCritical(C_SERVER_BALANCER) << "Failed to set SO_REUSEPORT on socket" << socket;
            return -1;
        }
    }
 
    if (!nativeBind(socket, address, port)) {
        qCCritical(C_SERVER_BALANCER) << "Failed to bind to socket" << socket;
        return -1;
    }
 
    if (startListening && ::listen(socket, listenQueue) < 0) {
        qCCritical(C_SERVER_BALANCER) << "Failed to listen to socket" << socket;
        return -1;
    }
 
    return socket;
}
#endif // Q_OS_LINUX
} // namespace
 
void TcpServerBalancer::setBalancer(bool enable)
{
    m_balancer = enable;
}
 
void TcpServerBalancer::incomingConnection(qintptr handle)
{
    TcpServer *serverIdle = m_servers.at(m_currentServer++ % m_servers.size());
 
    Q_EMIT serverIdle->createConnection(handle);
}
 
TcpServer *TcpServerBalancer::createServer(ServerEngine *engine)
{
    TcpServer *server;
    if (m_sslConfiguration) {
#ifndef QT_NO_SSL
        auto sslServer = new TcpSslServer(m_serverName, m_protocol, m_server, engine);
        sslServer->setSslConfiguration(*m_sslConfiguration);
        server = sslServer;
#endif // QT_NO_SSL
    } else {
        server = new TcpServer(m_serverName, m_protocol, m_server, engine);
    }
    connect(engine, &ServerEngine::shutdown, server, &TcpServer::shutdown);
 
    if (m_balancer) {
        connect(engine, &ServerEngine::started, this, [this, server]() {
            m_servers.push_back(server);
            resumeAccepting();
        }, Qt::QueuedConnection);
        connect(server,
                &TcpServer::createConnection,
                server,
                &TcpServer::incomingConnection,
                Qt::QueuedConnection);
    } else {
 
#ifdef Q_OS_LINUX
        if (m_server->reusePort()) {
            connect(engine, &ServerEngine::started, this, [this, server]() {
                int socket = listenReuse(
                    m_address, m_server->listenQueue(), m_port, m_server->reusePort(), true);
                if (!server->setSocketDescriptor(socket)) {
                    qFatal("Failed to set server socket descriptor, reuse-port");
                }
            }, Qt::DirectConnection);
            return server;
        }
#endif
 
        if (server->setSocketDescriptor(socketDescriptor())) {
            server->pauseAccepting();
            connect(engine,
                    &ServerEngine::started,
                    server,
                    &TcpServer::resumeAccepting,
                    Qt::DirectConnection);
        } else {
            qFatal("Failed to set server socket descriptor");
        }
    }
 
    return server;
}
 
#include "moc_tcpserverbalancer.cpp"