SFML/src/SFML/Network/SocketTCP.cpp

////////////////////////////////////////////////////////////
//
// SFML - Simple and Fast Multimedia Library
// Copyright (C) 2007-2009 Laurent Gomila (laurent.gom@gmail.com)
//
// This software is provided 'as-is', without any express or implied warranty.
// In no event will the authors be held liable for any damages arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it freely,
// subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented;
//    you must not claim that you wrote the original software.
//    If you use this software in a product, an acknowledgment
//    in the product documentation would be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such,
//    and must not be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source distribution.
//
////////////////////////////////////////////////////////////

////////////////////////////////////////////////////////////
// Headers
////////////////////////////////////////////////////////////
#include <SFML/Network/SocketTCP.hpp>
#include <SFML/Network/IpAddress.hpp>
#include <SFML/Network/Packet.hpp>
#include <SFML/Network/SocketHelper.hpp>
#include <SFML/System/Err.hpp>
#include <algorithm>
#include <string.h>


#ifdef _MSC_VER
    #pragma warning(disable : 4127) // "conditional expression is constant" generated by the FD_SET macro
#endif


namespace sf
{
////////////////////////////////////////////////////////////
/// Default constructor
////////////////////////////////////////////////////////////
SocketTCP::SocketTCP()
{
    Create(SocketHelper::InvalidSocket());
}


////////////////////////////////////////////////////////////
/// Change the blocking state of the socket
////////////////////////////////////////////////////////////
void SocketTCP::SetBlocking(bool blocking)
{
    // Make sure our socket is valid
    if (!IsValid())
        Create();

    SocketHelper::SetBlocking(mySocket, blocking);
    myIsBlocking = blocking;
}


////////////////////////////////////////////////////////////
/// Connect to another computer on a specified port
////////////////////////////////////////////////////////////
Socket::Status SocketTCP::Connect(unsigned short port, const IpAddress& host, float timeout)
{
    // Make sure our socket is valid
    if (!IsValid())
        Create();

    // Build the host address
    sockaddr_in sockAddr;
    memset(sockAddr.sin_zero, 0, sizeof(sockAddr.sin_zero));
    sockAddr.sin_addr.s_addr = inet_addr(host.ToString().c_str());
    sockAddr.sin_family      = AF_INET;
    sockAddr.sin_port        = htons(port);

    if (timeout <= 0)
    {
        // ----- We're not using a timeout : just try to connect -----

        if (connect(mySocket, reinterpret_cast<sockaddr*>(&sockAddr), sizeof(sockAddr)) == -1)
        {
            // Failed to connect
            return SocketHelper::GetErrorStatus();
        }

        // Connection succeeded
        return Socket::Done;
    }
    else
    {
        // ----- We're using a timeout : we'll need a few tricks to make it work -----

        // Save the previous blocking state
        bool blocking = myIsBlocking;

        // Switch to non-blocking to enable our connection timeout
        if (blocking)
            SetBlocking(false);

        // Try to connect to host
        if (connect(mySocket, reinterpret_cast<sockaddr*>(&sockAddr), sizeof(sockAddr)) >= 0)
        {
            // We got instantly connected! (it may no happen a lot...)
            return Socket::Done;
        }

        // Get the error status
        Socket::Status status = SocketHelper::GetErrorStatus();

        // If we were in non-blocking mode, return immediatly
        if (!blocking)
            return status;

        // Otherwise, wait until something happens to our socket (success, timeout or error)
        if (status == Socket::NotReady)
        {
            // Setup the selector
            fd_set selector;
            FD_ZERO(&selector);
            FD_SET(mySocket, &selector);

            // Setup the timeout
            timeval time;
            time.tv_sec  = static_cast<long>(timeout);
            time.tv_usec = (static_cast<long>(timeout * 1000) % 1000) * 1000;

            // Wait for something to write on our socket (which means that the connection request has returned)
            if (select(static_cast<int>(mySocket + 1), NULL, &selector, NULL, &time) > 0)
            {
                // At this point the connection may have been either accepted or refused.
                // To know whether it's a success or a failure, we try to retrieve the name of the connected peer
                SocketHelper::LengthType size = sizeof(sockAddr);
                if (getpeername(mySocket, reinterpret_cast<sockaddr*>(&sockAddr), &size) != -1)
                {
                    // Connection accepted
                    status = Socket::Done;
                }
                else
                {
                    // Connection failed
                    status = SocketHelper::GetErrorStatus();
                }
            }
            else
            {
                // Failed to connect before timeout is over
                status = SocketHelper::GetErrorStatus();
            }
        }

        // Switch back to blocking mode
        SetBlocking(true);

        return status;
    }
}


////////////////////////////////////////////////////////////
/// Listen to a specified port for incoming data or connections
////////////////////////////////////////////////////////////
bool SocketTCP::Listen(unsigned short port)
{
    // Make sure our socket is valid
    if (!IsValid())
        Create();

    // Build the address
    sockaddr_in sockAddr;
    memset(sockAddr.sin_zero, 0, sizeof(sockAddr.sin_zero));
    sockAddr.sin_addr.s_addr = htonl(INADDR_ANY);
    sockAddr.sin_family      = AF_INET;
    sockAddr.sin_port        = htons(port);

    // Bind the socket to the specified port
    if (bind(mySocket, reinterpret_cast<sockaddr*>(&sockAddr), sizeof(sockAddr)) == -1)
    {
        // Not likely to happen, but...
        Err() << "Failed to bind socket to port " << port << std::endl;
        return false;
    }

    // Listen to the bound port
    if (listen(mySocket, 0) == -1)
    {
        // Oops, socket is deaf
        Err() << "Failed to listen to port " << port << std::endl;
        return false;
    }

    return true;
}


////////////////////////////////////////////////////////////
/// Wait for a connection (must be listening to a port).
/// This function will block if the socket is blocking
////////////////////////////////////////////////////////////
Socket::Status SocketTCP::Accept(SocketTCP& connected, IpAddress* address)
{
    // Address that will be filled with client informations
    sockaddr_in clientAddress;
    SocketHelper::LengthType length = sizeof(clientAddress);

    // Accept a new connection
    connected = accept(mySocket, reinterpret_cast<sockaddr*>(&clientAddress), &length);

    // Check errors
    if (!connected.IsValid())
    {
        if (address)
            *address = IpAddress();

        return SocketHelper::GetErrorStatus();
    }

    // Fill address if requested
    if (address)
        *address = IpAddress(inet_ntoa(clientAddress.sin_addr));

    return Socket::Done;
}


////////////////////////////////////////////////////////////
/// Send an array of bytes to the host (must be connected first)
////////////////////////////////////////////////////////////
Socket::Status SocketTCP::Send(const char* data, std::size_t sizeInBytes)
{
    // First check that socket is valid
    if (!IsValid())
        return Socket::Error;

    // Check parameters
    if (data && sizeInBytes)
    {
        // Loop until every byte has been sent
        int sent = 0;
        int sizeToSend = static_cast<int>(sizeInBytes);
        for (int length = 0; length < sizeToSend; length += sent)
        {
            // Send a chunk of data
            sent = send(mySocket, data + length, sizeToSend - length, 0);

            // Check if an error occured
            if (sent <= 0)
                return SocketHelper::GetErrorStatus();
        }

        return Socket::Done;
    }
    else
    {
        // Error...
        Err() << "Cannot send data over the network (invalid parameters)" << std::endl;
        return Socket::Error;
    }
}


////////////////////////////////////////////////////////////
/// Receive an array of bytes from the host (must be connected first).
/// This function will block if the socket is blocking
////////////////////////////////////////////////////////////
Socket::Status SocketTCP::Receive(char* data, std::size_t maxSize, std::size_t& sizeReceived)
{
    // First clear the size received
    sizeReceived = 0;

    // Check that socket is valid
    if (!IsValid())
        return Socket::Error;

    // Check parameters
    if (data && maxSize)
    {
        // Receive a chunk of bytes
        int received = recv(mySocket, data, static_cast<int>(maxSize), 0);

        // Check the number of bytes received
        if (received > 0)
        {
            sizeReceived = static_cast<std::size_t>(received);
            return Socket::Done;
        }
        else if (received == 0)
        {
            return Socket::Disconnected;
        }
        else
        {
            return SocketHelper::GetErrorStatus();
        }
    }
    else
    {
        // Error...
        Err() << "Cannot receive data from the network (invalid parameters)" << std::endl;
        return Socket::Error;
    }
}


////////////////////////////////////////////////////////////
/// Send a packet of data to the host (must be connected first)
////////////////////////////////////////////////////////////
Socket::Status SocketTCP::Send(Packet& packet)
{
    // Get the data to send from the packet
    std::size_t dataSize = 0;
    const char* data = packet.OnSend(dataSize);

    // Send the packet size
    Uint32 packetSize = htonl(static_cast<unsigned long>(dataSize));
    Send(reinterpret_cast<const char*>(&packetSize), sizeof(packetSize));

    // Send the packet data
    if (packetSize > 0)
    {
        return Send(data, dataSize);
    }
    else
    {
        return Socket::Done;
    }
}


////////////////////////////////////////////////////////////
/// Receive a packet from the host (must be connected first).
/// This function will block if the socket is blocking
////////////////////////////////////////////////////////////
Socket::Status SocketTCP::Receive(Packet& packet)
{
    // We start by getting the size of the incoming packet
    Uint32      packetSize = 0;
    std::size_t received   = 0;
    if (myPendingPacketSize < 0)
    {
        // Loop until we've received the entire size of the packet
        // (even a 4 bytes variable may be received in more than one call)
        while (myPendingHeaderSize < sizeof(myPendingHeader))
        {
            char* data = reinterpret_cast<char*>(&myPendingHeader) + myPendingHeaderSize;
            Socket::Status status = Receive(data, sizeof(myPendingHeader) - myPendingHeaderSize, received);
            myPendingHeaderSize += received;

            if (status != Socket::Done)
                return status;
        }

        packetSize = ntohl(myPendingHeader);
        myPendingHeaderSize = 0;
    }
    else
    {
        // There is a pending packet : we already know its size
        packetSize = myPendingPacketSize;
    }

    // Then loop until we receive all the packet data
    char buffer[1024];
    while (myPendingPacket.size() < packetSize)
    {
        // Receive a chunk of data
        std::size_t sizeToGet = std::min(static_cast<std::size_t>(packetSize - myPendingPacket.size()), sizeof(buffer));
        Socket::Status status = Receive(buffer, sizeToGet, received);
        if (status != Socket::Done)
        {
            // We must save the size of the pending packet until we can receive its content
            if (status == Socket::NotReady)
                myPendingPacketSize = packetSize;
            return status;
        }

        // Append it into the packet
        if (received > 0)
        {
            myPendingPacket.resize(myPendingPacket.size() + received);
            char* begin = &myPendingPacket[0] + myPendingPacket.size() - received;
            memcpy(begin, buffer, received);
        }
    }

    // We have received all the datas : we can copy it to the user packet, and clear our internal packet
    packet.Clear();
    if (!myPendingPacket.empty())
        packet.OnReceive(&myPendingPacket[0], myPendingPacket.size());
    myPendingPacket.clear();
    myPendingPacketSize = -1;

    return Socket::Done;
}


////////////////////////////////////////////////////////////
/// Close the socket
////////////////////////////////////////////////////////////
bool SocketTCP::Close()
{
    if (IsValid())
    {
        if (!SocketHelper::Close(mySocket))
        {
            Err() << "Failed to close socket" << std::endl;
            return false;
        }

        mySocket = SocketHelper::InvalidSocket();
    }

    myIsBlocking = true;

    return true;
}


////////////////////////////////////////////////////////////
/// Check if the socket is in a valid state ; this function
/// can be called any time to check if the socket is OK
////////////////////////////////////////////////////////////
bool SocketTCP::IsValid() const
{
    return mySocket != SocketHelper::InvalidSocket();
}


////////////////////////////////////////////////////////////
/// Comparison operator ==
////////////////////////////////////////////////////////////
bool SocketTCP::operator ==(const SocketTCP& other) const
{
    return mySocket == other.mySocket;
}


////////////////////////////////////////////////////////////
/// Comparison operator !=
////////////////////////////////////////////////////////////
bool SocketTCP::operator !=(const SocketTCP& other) const
{
    return mySocket != other.mySocket;
}


////////////////////////////////////////////////////////////
/// Comparison operator <.
/// Provided for compatibility with standard containers, as
/// comparing two sockets doesn't make much sense...
////////////////////////////////////////////////////////////
bool SocketTCP::operator <(const SocketTCP& other) const
{
    return mySocket < other.mySocket;
}


////////////////////////////////////////////////////////////
/// Construct the socket from a socket descriptor
/// (for internal use only)
////////////////////////////////////////////////////////////
SocketTCP::SocketTCP(SocketHelper::SocketType descriptor)
{
    Create(descriptor);
}


////////////////////////////////////////////////////////////
/// Create the socket
////////////////////////////////////////////////////////////
void SocketTCP::Create(SocketHelper::SocketType descriptor)
{
    // Use the given socket descriptor, or get a new one
    mySocket = descriptor ? descriptor : socket(PF_INET, SOCK_STREAM, 0);
    myIsBlocking = true;

    // Reset the pending packet
    myPendingHeaderSize = 0;
    myPendingPacket.clear();
    myPendingPacketSize = -1;

    // Setup default options
    if (IsValid())
    {
        // To avoid the "Address already in use" error message when trying to bind to the same port
        int yes = 1;
        if (setsockopt(mySocket, SOL_SOCKET, SO_REUSEADDR, reinterpret_cast<char*>(&yes), sizeof(yes)) == -1)
        {
            Err() << "Failed to set socket option \"SO_REUSEADDR\" ; "
                  << "binding to a same port may fail if too fast" << std::endl;
        }

        // Disable the Nagle algorithm (ie. removes buffering of TCP packets)
        if (setsockopt(mySocket, IPPROTO_TCP, TCP_NODELAY, reinterpret_cast<char*>(&yes), sizeof(yes)) == -1)
        {
            Err() << "Failed to set socket option \"TCP_NODELAY\" ; "
                  << "all your TCP packets will be buffered" << std::endl;
        }

        // Set blocking by default (should always be the case anyway)
        SetBlocking(true);
    }
}

} // namespace sf