[wxWidgets.git] / src / common / socket.cpp

/////////////////////////////////////////////////////////////////////////////
// Name:       src/common/socket.cpp
// Purpose:    Socket handler classes
// Authors:    Guilhem Lavaux, Guillermo Rodriguez Garcia
// Created:    April 1997
// Copyright:  (C) 1999-1997, Guilhem Lavaux
//             (C) 2000-1999, Guillermo Rodriguez Garcia
// RCS_ID:     $Id$
// License:    wxWindows licence
/////////////////////////////////////////////////////////////////////////////

// ==========================================================================
// Declarations
// ==========================================================================

// For compilers that support precompilation, includes "wx.h".
#include "wx/wxprec.h"

#ifdef __BORLANDC__
    #pragma hdrstop
#endif

#if wxUSE_SOCKETS

#include "wx/socket.h"

#ifndef WX_PRECOMP
    #include "wx/object.h"
    #include "wx/string.h"
    #include "wx/intl.h"
    #include "wx/log.h"
    #include "wx/event.h"
    #include "wx/app.h"
    #include "wx/utils.h"
    #include "wx/timer.h"
    #include "wx/module.h"
#endif

#include "wx/apptrait.h"
#include "wx/sckaddr.h"
#include "wx/stopwatch.h"
#include "wx/thread.h"
#include "wx/evtloop.h"

// DLL options compatibility check:
#include "wx/build.h"
WX_CHECK_BUILD_OPTIONS("wxNet")

// --------------------------------------------------------------------------
// macros and constants
// --------------------------------------------------------------------------

// discard buffer
#define MAX_DISCARD_SIZE (10 * 1024)

#define wxTRACE_Socket _T("wxSocket")

// --------------------------------------------------------------------------
// wxWin macros
// --------------------------------------------------------------------------

IMPLEMENT_CLASS(wxSocketBase, wxObject)
IMPLEMENT_CLASS(wxSocketServer, wxSocketBase)
IMPLEMENT_CLASS(wxSocketClient, wxSocketBase)
IMPLEMENT_CLASS(wxDatagramSocket, wxSocketBase)
IMPLEMENT_DYNAMIC_CLASS(wxSocketEvent, wxEvent)

// --------------------------------------------------------------------------
// private classes
// --------------------------------------------------------------------------

class wxSocketState : public wxObject
{
public:
    wxSocketFlags            m_flags;
    wxSocketEventFlags       m_eventmask;
    bool                     m_notify;
    void                    *m_clientData;

public:
    wxSocketState() : wxObject() {}

    DECLARE_NO_COPY_CLASS(wxSocketState)
};

// ============================================================================
// GSocketManager
// ============================================================================

GSocketManager *GSocketManager::ms_manager = NULL;

/* static */
void GSocketManager::Set(GSocketManager *manager)
{
    wxASSERT_MSG( !ms_manager, "too late to set manager now" );

    ms_manager = manager;
}

/* static */
void GSocketManager::Init()
{
    wxASSERT_MSG( !ms_manager, "shouldn't be initialized twice" );

    /*
        Details: Initialize() creates a hidden window as a sink for socket
        events, such as 'read completed'. wxMSW has only one message loop
        for the main thread. If Initialize is called in a secondary thread,
        the socket window will be created for the secondary thread, but
        since there is no message loop on this thread, it will never
        receive events and all socket operations will time out.
        BTW, the main thread must not be stopped using sleep or block
        on a semaphore (a bad idea in any case) or socket operations
        will time out.

        On the Mac side, Initialize() stores a pointer to the CFRunLoop for
        the main thread. Because secondary threads do not have run loops,
        adding event notifications to the "Current" loop would have no
        effect at all, events would never fire.
    */
    wxASSERT_MSG( wxIsMainThread(),
                    "sockets must be initialized from the main thread" );

    wxAppConsole * const app = wxAppConsole::GetInstance();
    wxCHECK_RET( app, "sockets can't be initialized without wxApp" );

    ms_manager = app->GetTraits()->GetSocketManager();
}

// ==========================================================================
// wxSocketBase
// ==========================================================================

// --------------------------------------------------------------------------
// Initialization and shutdown
// --------------------------------------------------------------------------

// FIXME-MT: all this is MT-unsafe, of course, we should protect all accesses
//           to m_countInit with a crit section
size_t wxSocketBase::m_countInit = 0;

bool wxSocketBase::IsInitialized()
{
    return m_countInit > 0;
}

bool wxSocketBase::Initialize()
{
    if ( !m_countInit++ )
    {
        if ( !GSocket_Init() )
        {
            m_countInit--;

            return false;
        }
    }

    return true;
}

void wxSocketBase::Shutdown()
{
    // we should be initialized
    wxASSERT_MSG( m_countInit > 0, _T("extra call to Shutdown()") );
    if ( --m_countInit == 0 )
    {
        GSocket_Cleanup();
    }
}

// --------------------------------------------------------------------------
// Ctor and dtor
// --------------------------------------------------------------------------

void wxSocketBase::Init()
{
    m_socket       = NULL;
    m_type         = wxSOCKET_UNINIT;

    // state
    m_flags        = 0;
    m_connected    =
    m_establishing =
    m_reading      =
    m_writing      =
    m_error        =
    m_closed       = false;
    m_lcount       = 0;
    m_timeout      = 600;
    m_beingDeleted = false;

    // pushback buffer
    m_unread       = NULL;
    m_unrd_size    = 0;
    m_unrd_cur     = 0;

    // events
    m_id           = wxID_ANY;
    m_handler      = NULL;
    m_clientData   = NULL;
    m_notify       = false;
    m_eventmask    = 0;

    if ( !IsInitialized() )
    {
        // this Initialize() will be undone by wxSocketModule::OnExit(), all
        // the other calls to it should be matched by a call to Shutdown()
        Initialize();
    }
}

wxSocketBase::wxSocketBase()
{
    Init();
}

wxSocketBase::wxSocketBase(wxSocketFlags flags, wxSocketType type)
{
    Init();

    m_flags = flags;
    m_type  = type;
}

wxSocketBase::~wxSocketBase()
{
    // Just in case the app called Destroy() *and* then deleted the socket
    // immediately: don't leave dangling pointers.
    wxAppTraits *traits = wxTheApp ? wxTheApp->GetTraits() : NULL;
    if ( traits )
        traits->RemoveFromPendingDelete(this);

    // Shutdown and close the socket
    if (!m_beingDeleted)
        Close();

    // Destroy the GSocket object
    if (m_socket)
        delete m_socket;

    // Free the pushback buffer
    if (m_unread)
        free(m_unread);
}

bool wxSocketBase::Destroy()
{
    // Delayed destruction: the socket will be deleted during the next idle
    // loop iteration. This ensures that all pending events have been
    // processed.
    m_beingDeleted = true;

    // Shutdown and close the socket
    Close();

    // Supress events from now on
    Notify(false);

    // schedule this object for deletion
    wxAppTraits *traits = wxTheApp ? wxTheApp->GetTraits() : NULL;
    if ( traits )
    {
        // let the traits object decide what to do with us
        traits->ScheduleForDestroy(this);
    }
    else // no app or no traits
    {
        // in wxBase we might have no app object at all, don't leak memory
        delete this;
    }

    return true;
}

// --------------------------------------------------------------------------
// Basic IO calls
// --------------------------------------------------------------------------

// The following IO operations update m_error and m_lcount:
// {Read, Write, ReadMsg, WriteMsg, Peek, Unread, Discard}
//
// TODO: Should Connect, Accept and AcceptWith update m_error?

bool wxSocketBase::Close()
{
    // Interrupt pending waits
    InterruptWait();

    if (m_socket)
    {
        // Disable callbacks
        m_socket->UnsetCallback(
            GSOCK_INPUT_FLAG |
            GSOCK_OUTPUT_FLAG |
            GSOCK_LOST_FLAG |
            GSOCK_CONNECTION_FLAG
        );

        // Shutdown the connection
        m_socket->Shutdown();
    }

    m_connected = false;
    m_establishing = false;
    return true;
}

wxSocketBase& wxSocketBase::Read(void* buffer, wxUint32 nbytes)
{
    // Mask read events
    m_reading = true;

    m_lcount = _Read(buffer, nbytes);

    // If in wxSOCKET_WAITALL mode, all bytes should have been read.
    if (m_flags & wxSOCKET_WAITALL)
        m_error = (m_lcount != nbytes);
    else
        m_error = (m_lcount == 0);

    // Allow read events from now on
    m_reading = false;

    return *this;
}

wxUint32 wxSocketBase::_Read(void* buffer_, wxUint32 nbytes)
{
    char *buffer = (char *)buffer_;

    int total;

    // Try the pushback buffer first
    total = GetPushback(buffer, nbytes, false);
    nbytes -= total;
    buffer  = (char *)buffer + total;

    // Return now in one of the following cases:
    // - the socket is invalid,
    // - we got all the data
    if ( !m_socket ||
            !nbytes )
        return total;

    // Possible combinations (they are checked in this order)
    // wxSOCKET_NOWAIT
    // wxSOCKET_WAITALL (with or without wxSOCKET_BLOCK)
    // wxSOCKET_BLOCK
    // wxSOCKET_NONE
    //
    int ret;
    if (m_flags & wxSOCKET_NOWAIT)
    {
        m_socket->SetNonBlocking(1);
        ret = m_socket->Read(buffer, nbytes);
        m_socket->SetNonBlocking(0);

        if ( ret < 0 )
            return 0;

        total += ret;
    }
    else // blocking socket
    {
        for ( ;; )
        {
            // dispatch events unless disabled
            if ( !(m_flags & wxSOCKET_BLOCK) && !WaitForRead() )
                break;

            ret = m_socket->Read(buffer, nbytes);
            if ( ret == 0 )
            {
                // for connection-oriented (e.g. TCP) sockets we can only read
                // 0 bytes if the other end has been closed, and for
                // connectionless ones (UDP) this flag doesn't make sense
                // anyhow so we can set it to true too without doing any harm
                m_closed = true;
                break;
            }

            if ( ret < 0 )
            {
                // this will be always interpreted as error by Read()
                return 0;
            }

            total += ret;

            // if wxSOCKET_WAITALL is not set, we can leave now as we did read
            // something
            if ( !(m_flags & wxSOCKET_WAITALL) )
                break;

            // otherwise check if read the maximal requested amount of data
            nbytes -= ret;
            if ( !nbytes )
                break;

            // we didn't, so continue reading
            buffer  = (char *)buffer + ret;
        }
    }

    return total;
}

wxSocketBase& wxSocketBase::ReadMsg(void* buffer, wxUint32 nbytes)
{
    wxUint32 len, len2, sig, total;
    bool error;
    int old_flags;
    struct
    {
        unsigned char sig[4];
        unsigned char len[4];
    } msg;

    // Mask read events
    m_reading = true;

    total = 0;
    error = true;
    old_flags = m_flags;
    SetFlags((m_flags & wxSOCKET_BLOCK) | wxSOCKET_WAITALL);

    if (_Read(&msg, sizeof(msg)) != sizeof(msg))
        goto exit;

    sig = (wxUint32)msg.sig[0];
    sig |= (wxUint32)(msg.sig[1] << 8);
    sig |= (wxUint32)(msg.sig[2] << 16);
    sig |= (wxUint32)(msg.sig[3] << 24);

    if (sig != 0xfeeddead)
    {
        wxLogWarning(_("wxSocket: invalid signature in ReadMsg."));
        goto exit;
    }

    len = (wxUint32)msg.len[0];
    len |= (wxUint32)(msg.len[1] << 8);
    len |= (wxUint32)(msg.len[2] << 16);
    len |= (wxUint32)(msg.len[3] << 24);

    if (len > nbytes)
    {
        len2 = len - nbytes;
        len = nbytes;
    }
    else
        len2 = 0;

    // Don't attempt to read if the msg was zero bytes long.
    if (len)
    {
        total = _Read(buffer, len);

        if (total != len)
            goto exit;
    }

    if (len2)
    {
        char *discard_buffer = new char[MAX_DISCARD_SIZE];
        long discard_len;

        // NOTE: discarded bytes don't add to m_lcount.
        do
        {
            discard_len = ((len2 > MAX_DISCARD_SIZE)? MAX_DISCARD_SIZE : len2);
            discard_len = _Read(discard_buffer, (wxUint32)discard_len);
            len2 -= (wxUint32)discard_len;
        }
        while ((discard_len > 0) && len2);

        delete [] discard_buffer;

        if (len2 != 0)
            goto exit;
    }
    if (_Read(&msg, sizeof(msg)) != sizeof(msg))
        goto exit;

    sig = (wxUint32)msg.sig[0];
    sig |= (wxUint32)(msg.sig[1] << 8);
    sig |= (wxUint32)(msg.sig[2] << 16);
    sig |= (wxUint32)(msg.sig[3] << 24);

    if (sig != 0xdeadfeed)
    {
        wxLogWarning(_("wxSocket: invalid signature in ReadMsg."));
        goto exit;
    }

    // everything was OK
    error = false;

exit:
    m_error = error;
    m_lcount = total;
    m_reading = false;
    SetFlags(old_flags);

    return *this;
}

wxSocketBase& wxSocketBase::Peek(void* buffer, wxUint32 nbytes)
{
    // Mask read events
    m_reading = true;

    m_lcount = _Read(buffer, nbytes);
    Pushback(buffer, m_lcount);

    // If in wxSOCKET_WAITALL mode, all bytes should have been read.
    if (m_flags & wxSOCKET_WAITALL)
        m_error = (m_lcount != nbytes);
    else
        m_error = (m_lcount == 0);

    // Allow read events again
    m_reading = false;

    return *this;
}

wxSocketBase& wxSocketBase::Write(const void *buffer, wxUint32 nbytes)
{
    // Mask write events
    m_writing = true;

    m_lcount = _Write(buffer, nbytes);

    // If in wxSOCKET_WAITALL mode, all bytes should have been written.
    if (m_flags & wxSOCKET_WAITALL)
        m_error = (m_lcount != nbytes);
    else
        m_error = (m_lcount == 0);

    // Allow write events again
    m_writing = false;

    return *this;
}

wxUint32 wxSocketBase::_Write(const void *buffer_, wxUint32 nbytes)
{
    const char *buffer = (const char *)buffer_;

    wxUint32 total = 0;

    // If the socket is invalid or parameters are ill, return immediately
    if (!m_socket || !buffer || !nbytes)
        return 0;

    // Possible combinations (they are checked in this order)
    // wxSOCKET_NOWAIT
    // wxSOCKET_WAITALL (with or without wxSOCKET_BLOCK)
    // wxSOCKET_BLOCK
    // wxSOCKET_NONE
    //
    int ret;
    if (m_flags & wxSOCKET_NOWAIT)
    {
        m_socket->SetNonBlocking(1);
        ret = m_socket->Write(buffer, nbytes);
        m_socket->SetNonBlocking(0);

        if (ret > 0)
            total = ret;
    }
    else // blocking socket
    {
        for ( ;; )
        {
            if ( !(m_flags & wxSOCKET_BLOCK) && !WaitForWrite() )
                break;

            ret = m_socket->Write(buffer, nbytes);

            // see comments for similar logic for ret handling in _Read()
            if ( ret == 0 )
            {
                m_closed = true;
                break;
            }

            if ( ret < 0 )
            {
                return 0;
            }

            total += ret;
            if ( !(m_flags & wxSOCKET_WAITALL) )
                break;

            nbytes -= ret;
            if ( !nbytes )
                break;

            buffer = (const char *)buffer + ret;
        }
    }

    return total;
}

wxSocketBase& wxSocketBase::WriteMsg(const void *buffer, wxUint32 nbytes)
{
    wxUint32 total;
    bool error;
    struct
    {
        unsigned char sig[4];
        unsigned char len[4];
    } msg;

    // Mask write events
    m_writing = true;

    error = true;
    total = 0;
    SetFlags((m_flags & wxSOCKET_BLOCK) | wxSOCKET_WAITALL);

    msg.sig[0] = (unsigned char) 0xad;
    msg.sig[1] = (unsigned char) 0xde;
    msg.sig[2] = (unsigned char) 0xed;
    msg.sig[3] = (unsigned char) 0xfe;

    msg.len[0] = (unsigned char) (nbytes & 0xff);
    msg.len[1] = (unsigned char) ((nbytes >> 8) & 0xff);
    msg.len[2] = (unsigned char) ((nbytes >> 16) & 0xff);
    msg.len[3] = (unsigned char) ((nbytes >> 24) & 0xff);

    if (_Write(&msg, sizeof(msg)) < sizeof(msg))
        goto exit;

    total = _Write(buffer, nbytes);

    if (total < nbytes)
        goto exit;

    msg.sig[0] = (unsigned char) 0xed;
    msg.sig[1] = (unsigned char) 0xfe;
    msg.sig[2] = (unsigned char) 0xad;
    msg.sig[3] = (unsigned char) 0xde;
    msg.len[0] =
    msg.len[1] =
    msg.len[2] =
    msg.len[3] = (char) 0;

    if ((_Write(&msg, sizeof(msg))) < sizeof(msg))
        goto exit;

    // everything was OK
    error = false;

exit:
    m_error = error;
    m_lcount = total;
    m_writing = false;

    return *this;
}

wxSocketBase& wxSocketBase::Unread(const void *buffer, wxUint32 nbytes)
{
    if (nbytes != 0)
        Pushback(buffer, nbytes);

    m_error = false;
    m_lcount = nbytes;

    return *this;
}

wxSocketBase& wxSocketBase::Discard()
{
    char *buffer = new char[MAX_DISCARD_SIZE];
    wxUint32 ret;
    wxUint32 total = 0;

    // Mask read events
    m_reading = true;

    SetFlags(wxSOCKET_NOWAIT);

    do
    {
        ret = _Read(buffer, MAX_DISCARD_SIZE);
        total += ret;
    }
    while (ret == MAX_DISCARD_SIZE);

    delete[] buffer;
    m_lcount = total;
    m_error  = false;

    // Allow read events again
    m_reading = false;

    return *this;
}

// --------------------------------------------------------------------------
// Wait functions
// --------------------------------------------------------------------------

// All Wait functions poll the socket using GSocket_Select() to
// check for the specified combination of conditions, until one
// of these conditions become true, an error occurs, or the
// timeout elapses. The polling loop runs the event loop so that
// this won't block the GUI.

bool wxSocketBase::_Wait(long seconds,
                         long milliseconds,
                         wxSocketEventFlags flags)
{
    GSocketEventFlags result;
    long timeout; // in ms

    // Set this to true to interrupt ongoing waits
    m_interrupt = false;

    // Check for valid socket
    if (!m_socket)
        return false;

    // Check for valid timeout value.
    if (seconds != -1)
        timeout = seconds * 1000 + milliseconds;
    else
        timeout = m_timeout * 1000;

    // Get the active event loop
    wxEventLoopBase * const eventLoop = wxEventLoop::GetActive();

#ifdef __WXMSW__
    wxASSERT_MSG( !wxIsMainThread() || eventLoop,
            "Sockets won't work without a running event loop" );
#endif // __WXMSW__

    // Wait in an active polling loop.
    //
    // NOTE: We duplicate some of the code in OnRequest, but this doesn't
    //   hurt. It has to be here because the (GSocket) event might arrive
    //   a bit delayed, and it has to be in OnRequest as well because we
    //   don't know whether the Wait functions are being used.
    //
    // Do this at least once (important if timeout == 0, when
    // we are just polling). Also, if just polling, do not yield.

    const wxMilliClock_t time_limit = wxGetLocalTimeMillis() + timeout;
    bool done = false;
    bool valid_result = false;

    if (!eventLoop)
    {
        // This is used to avoid a busy loop on wxBase - having a select
        // timeout of 50 ms per iteration should be enough.
        if (timeout > 50)
            m_socket->SetTimeout(50);
        else
            m_socket->SetTimeout(timeout);
    }

    while (!done)
    {
        result = m_socket->Select(flags | GSOCK_LOST_FLAG);

        // Incoming connection (server) or connection established (client)
        if (result & GSOCK_CONNECTION_FLAG)
        {
            m_connected = true;
            m_establishing = false;
            valid_result = true;
            break;
        }

        // Data available or output buffer ready
        if ((result & GSOCK_INPUT_FLAG) || (result & GSOCK_OUTPUT_FLAG))
        {
            valid_result = true;
            break;
        }

        // Connection lost
        if (result & GSOCK_LOST_FLAG)
        {
            m_connected = false;
            m_establishing = false;
            valid_result = ((flags & GSOCK_LOST_FLAG) != 0);
            break;
        }

        // Wait more?
        long time_left = wxMilliClockToLong(time_limit - wxGetLocalTimeMillis());
        if ((!timeout) || (time_left <= 0) || (m_interrupt))
            done = true;
        else
        {
            if (eventLoop)
            {
                // from the main thread itself we have to run the event loop to
                // let the events (including the GUI events and the low-level
                // (not wxWidgets) events from GSocket) be processed but from
                // another thread it is enough to just call wxThread::Yield()
                // which will give away the rest of our time slice: the
                // explanation is that the events will be processed by the main
                // thread anyhow, but we don't want to eat the CPU time
                // uselessly while sitting in the loop waiting for the data
                if ( wxIsMainThread() )
                {
                    if ( eventLoop->Pending() )
                        eventLoop->Dispatch();
                }
#if wxUSE_THREADS
                else
                    wxThread::Yield();
#endif // wxUSE_THREADS
            }
            else
            {
                // If there's less than 50 ms left, just call select with that timeout.
                if (time_left < 50)
                    m_socket->SetTimeout(time_left);
            }
        }
    }

    // Set timeout back to original value (we overwrote it for polling)
    if (!eventLoop)
        m_socket->SetTimeout(m_timeout*1000);

    return valid_result;
}

bool wxSocketBase::Wait(long seconds, long milliseconds)
{
    return _Wait(seconds, milliseconds, GSOCK_INPUT_FLAG |
                                        GSOCK_OUTPUT_FLAG |
                                        GSOCK_CONNECTION_FLAG |
                                        GSOCK_LOST_FLAG);
}

bool wxSocketBase::WaitForRead(long seconds, long milliseconds)
{
    // Check pushback buffer before entering _Wait
    if (m_unread)
        return true;

    // Note that GSOCK_INPUT_LOST has to be explicitly passed to
    // _Wait because of the semantics of WaitForRead: a return
    // value of true means that a GSocket_Read call will return
    // immediately, not that there is actually data to read.

    return _Wait(seconds, milliseconds, GSOCK_INPUT_FLAG | GSOCK_LOST_FLAG);
}


bool wxSocketBase::WaitForWrite(long seconds, long milliseconds)
{
    return _Wait(seconds, milliseconds, GSOCK_OUTPUT_FLAG);
}

bool wxSocketBase::WaitForLost(long seconds, long milliseconds)
{
    return _Wait(seconds, milliseconds, GSOCK_LOST_FLAG);
}

// --------------------------------------------------------------------------
// Miscellaneous
// --------------------------------------------------------------------------

//
// Get local or peer address
//

bool wxSocketBase::GetPeer(wxSockAddress& addr_man) const
{
    GAddress *peer;

    if (!m_socket)
        return false;

    peer = m_socket->GetPeer();

    // copying a null address would just trigger an assert anyway

    if (!peer)
        return false;

    addr_man.SetAddress(peer);
    GAddress_destroy(peer);

    return true;
}

bool wxSocketBase::GetLocal(wxSockAddress& addr_man) const
{
    GAddress *local;

    if (!m_socket)
        return false;

    local = m_socket->GetLocal();
    addr_man.SetAddress(local);
    GAddress_destroy(local);

    return true;
}

//
// Save and restore socket state
//

void wxSocketBase::SaveState()
{
    wxSocketState *state;

    state = new wxSocketState();

    state->m_flags      = m_flags;
    state->m_notify     = m_notify;
    state->m_eventmask  = m_eventmask;
    state->m_clientData = m_clientData;

    m_states.Append(state);
}

void wxSocketBase::RestoreState()
{
    wxList::compatibility_iterator node;
    wxSocketState *state;

    node = m_states.GetLast();
    if (!node)
        return;

    state = (wxSocketState *)node->GetData();

    m_flags      = state->m_flags;
    m_notify     = state->m_notify;
    m_eventmask  = state->m_eventmask;
    m_clientData = state->m_clientData;

    m_states.Erase(node);
    delete state;
}

//
// Timeout and flags
//

void wxSocketBase::SetTimeout(long seconds)
{
    m_timeout = seconds;

    if (m_socket)
        m_socket->SetTimeout(m_timeout * 1000);
}

void wxSocketBase::SetFlags(wxSocketFlags flags)
{
    m_flags = flags;
}


// --------------------------------------------------------------------------
// Event handling
// --------------------------------------------------------------------------

// A note on how events are processed, which is probably the most
// difficult thing to get working right while keeping the same API
// and functionality for all platforms.
//
// When GSocket detects an event, it calls wx_socket_callback, which in
// turn just calls wxSocketBase::OnRequest in the corresponding wxSocket
// object. OnRequest does some housekeeping, and if the event is to be
// propagated to the user, it creates a new wxSocketEvent object and
// posts it. The event is not processed immediately, but delayed with
// AddPendingEvent instead. This is necessary in order to decouple the
// event processing from wx_socket_callback; otherwise, subsequent IO
// calls made from the user event handler would fail, as gtk callbacks
// are not reentrant.
//
// Note that, unlike events, user callbacks (now deprecated) are _not_
// decoupled from wx_socket_callback and thus they suffer from a variety
// of problems. Avoid them where possible and use events instead.

extern "C"
void LINKAGEMODE wx_socket_callback(GSocket * WXUNUSED(socket),
                                    GSocketEvent notification,
                                    char *cdata)
{
    wxSocketBase *sckobj = (wxSocketBase *)cdata;

    sckobj->OnRequest((wxSocketNotify) notification);
}

void wxSocketBase::OnRequest(wxSocketNotify notification)
{
    // NOTE: We duplicate some of the code in _Wait, but this doesn't
    //   hurt. It has to be here because the (GSocket) event might arrive
    //   a bit delayed, and it has to be in _Wait as well because we don't
    //   know whether the Wait functions are being used.

    switch(notification)
    {
        case wxSOCKET_CONNECTION:
            m_establishing = false;
            m_connected = true;
            break;

            // If we are in the middle of a R/W operation, do not
            // propagate events to users. Also, filter 'late' events
            // which are no longer valid.

        case wxSOCKET_INPUT:
            if (m_reading || !m_socket->Select(GSOCK_INPUT_FLAG))
                return;
            break;

        case wxSOCKET_OUTPUT:
            if (m_writing || !m_socket->Select(GSOCK_OUTPUT_FLAG))
                return;
            break;

        case wxSOCKET_LOST:
            m_connected = false;
            m_establishing = false;
            break;
    }

    // Schedule the event

    wxSocketEventFlags flag = 0;
    wxUnusedVar(flag);
    switch (notification)
    {
        case GSOCK_INPUT:      flag = GSOCK_INPUT_FLAG; break;
        case GSOCK_OUTPUT:     flag = GSOCK_OUTPUT_FLAG; break;
        case GSOCK_CONNECTION: flag = GSOCK_CONNECTION_FLAG; break;
        case GSOCK_LOST:       flag = GSOCK_LOST_FLAG; break;
        default:
                               wxLogWarning(_("wxSocket: unknown event!."));
                               return;
    }

    if (((m_eventmask & flag) == flag) && m_notify)
    {
        if (m_handler)
        {
            wxSocketEvent event(m_id);
            event.m_event      = notification;
            event.m_clientData = m_clientData;
            event.SetEventObject(this);

            m_handler->AddPendingEvent(event);
        }
    }
}

void wxSocketBase::Notify(bool notify)
{
    m_notify = notify;
    if (m_socket)
        m_socket->Notify(notify);
}

void wxSocketBase::SetNotify(wxSocketEventFlags flags)
{
    m_eventmask = flags;
}

void wxSocketBase::SetEventHandler(wxEvtHandler& handler, int id)
{
    m_handler = &handler;
    m_id      = id;
}

// --------------------------------------------------------------------------
// Pushback buffer
// --------------------------------------------------------------------------

void wxSocketBase::Pushback(const void *buffer, wxUint32 size)
{
    if (!size) return;

    if (m_unread == NULL)
        m_unread = malloc(size);
    else
    {
        void *tmp;

        tmp = malloc(m_unrd_size + size);
        memcpy((char *)tmp + size, m_unread, m_unrd_size);
        free(m_unread);

        m_unread = tmp;
    }

    m_unrd_size += size;

    memcpy(m_unread, buffer, size);
}

wxUint32 wxSocketBase::GetPushback(void *buffer, wxUint32 size, bool peek)
{
    if (!m_unrd_size)
        return 0;

    if (size > (m_unrd_size-m_unrd_cur))
        size = m_unrd_size-m_unrd_cur;

    memcpy(buffer, (char *)m_unread + m_unrd_cur, size);

    if (!peek)
    {
        m_unrd_cur += size;
        if (m_unrd_size == m_unrd_cur)
        {
            free(m_unread);
            m_unread = NULL;
            m_unrd_size = 0;
            m_unrd_cur  = 0;
        }
    }

    return size;
}


// ==========================================================================
// wxSocketServer
// ==========================================================================

// --------------------------------------------------------------------------
// Ctor
// --------------------------------------------------------------------------

wxSocketServer::wxSocketServer(const wxSockAddress& addr_man,
                               wxSocketFlags flags)
              : wxSocketBase(flags, wxSOCKET_SERVER)
{
    wxLogTrace( wxTRACE_Socket, _T("Opening wxSocketServer") );

    m_socket = GSocket_new();

    if (!m_socket)
    {
        wxLogTrace( wxTRACE_Socket, _T("*** GSocket_new failed") );
        return;
    }

    // Setup the socket as server
    m_socket->Notify(m_notify);
    m_socket->SetLocal(addr_man.GetAddress());

    if (GetFlags() & wxSOCKET_REUSEADDR) {
        m_socket->SetReusable();
    }
    if (GetFlags() & wxSOCKET_BROADCAST) {
        m_socket->SetBroadcast();
    }
    if (GetFlags() & wxSOCKET_NOBIND) {
        m_socket->DontDoBind();
    }

    if (m_socket->SetServer() != GSOCK_NOERROR)
    {
        delete m_socket;
        m_socket = NULL;

        wxLogTrace( wxTRACE_Socket, _T("*** GSocket_SetServer failed") );
        return;
    }

    m_socket->SetTimeout(m_timeout * 1000);
    m_socket->SetCallback(GSOCK_INPUT_FLAG | GSOCK_OUTPUT_FLAG |
                                  GSOCK_LOST_FLAG | GSOCK_CONNECTION_FLAG,
                                  wx_socket_callback, (char *)this);

    wxLogTrace( wxTRACE_Socket, _T("wxSocketServer on fd %d"), m_socket->m_fd );
}

// --------------------------------------------------------------------------
// Accept
// --------------------------------------------------------------------------

bool wxSocketServer::AcceptWith(wxSocketBase& sock, bool wait)
{
    GSocket *child_socket;

    if (!m_socket)
        return false;

    // If wait == false, then the call should be nonblocking.
    // When we are finished, we put the socket to blocking mode
    // again.

    if (!wait)
        m_socket->SetNonBlocking(1);

    child_socket = m_socket->WaitConnection();

    if (!wait)
        m_socket->SetNonBlocking(0);

    if (!child_socket)
        return false;

    sock.m_type = wxSOCKET_BASE;
    sock.m_socket = child_socket;
    sock.m_connected = true;

    sock.m_socket->SetTimeout(sock.m_timeout * 1000);
    sock.m_socket->SetCallback(GSOCK_INPUT_FLAG | GSOCK_OUTPUT_FLAG |
            GSOCK_LOST_FLAG | GSOCK_CONNECTION_FLAG,
            wx_socket_callback, (char *)&sock);

    return true;
}

wxSocketBase *wxSocketServer::Accept(bool wait)
{
    wxSocketBase* sock = new wxSocketBase();

    sock->SetFlags(m_flags);

    if (!AcceptWith(*sock, wait))
    {
        sock->Destroy();
        sock = NULL;
    }

    return sock;
}

bool wxSocketServer::WaitForAccept(long seconds, long milliseconds)
{
    return _Wait(seconds, milliseconds, GSOCK_CONNECTION_FLAG);
}

bool wxSocketBase::GetOption(int level, int optname, void *optval, int *optlen)
{
    wxASSERT_MSG( m_socket, _T("Socket not initialised") );

    if (m_socket->GetSockOpt(level, optname, optval, optlen)
        != GSOCK_NOERROR)
    {
        return false;
    }
    return true;
}

bool wxSocketBase::SetOption(int level, int optname, const void *optval,
                              int optlen)
{
    wxASSERT_MSG( m_socket, _T("Socket not initialised") );

    if (m_socket->SetSockOpt(level, optname, optval, optlen)
        != GSOCK_NOERROR)
    {
        return false;
    }
    return true;
}

bool wxSocketBase::SetLocal(const wxIPV4address& local)
{
    GAddress* la = local.GetAddress();

    // If the address is valid, save it for use when we call Connect
    if (la && la->m_addr)
    {
        m_localAddress = local;

        return true;
    }

    return false;
}

// ==========================================================================
// wxSocketClient
// ==========================================================================

// --------------------------------------------------------------------------
// Ctor and dtor
// --------------------------------------------------------------------------

wxSocketClient::wxSocketClient(wxSocketFlags flags)
              : wxSocketBase(flags, wxSOCKET_CLIENT)
{
    m_initialRecvBufferSize =
    m_initialSendBufferSize = -1;
}

wxSocketClient::~wxSocketClient()
{
}

// --------------------------------------------------------------------------
// Connect
// --------------------------------------------------------------------------

bool wxSocketClient::DoConnect(const wxSockAddress& addr_man,
                               const wxSockAddress* local,
                               bool wait)
{
    GSocketError err;

    if (m_socket)
    {
        // Shutdown and destroy the socket
        Close();
        delete m_socket;
    }

    m_socket = GSocket_new();
    m_connected = false;
    m_establishing = false;

    if (!m_socket)
        return false;

    m_socket->SetTimeout(m_timeout * 1000);
    m_socket->SetCallback(
        GSOCK_INPUT_FLAG |
        GSOCK_OUTPUT_FLAG |
        GSOCK_LOST_FLAG |
        GSOCK_CONNECTION_FLAG,
        wx_socket_callback,
        (char *)this
    );

    // If wait == false, then the call should be nonblocking. When we are
    // finished, we put the socket to blocking mode again.

    if (!wait)
        m_socket->SetNonBlocking(1);

    // Reuse makes sense for clients too, if we are trying to rebind to the same port
    if (GetFlags() & wxSOCKET_REUSEADDR)
    {
        m_socket->SetReusable();
    }
    if (GetFlags() & wxSOCKET_BROADCAST)
    {
        m_socket->SetBroadcast();
    }
    if (GetFlags() & wxSOCKET_NOBIND)
    {
        m_socket->DontDoBind();
    }

    // If no local address was passed and one has been set, use the one that was Set
    if (!local && m_localAddress.GetAddress())
    {
        local = &m_localAddress;
    }

    // Bind to the local IP address and port, when provided
    if (local)
    {
        GAddress* la = local->GetAddress();

        if (la && la->m_addr)
            m_socket->SetLocal(la);
    }

#if defined(__WXMSW__) || defined(__WXGTK__)
    m_socket->SetInitialSocketBuffers(m_initialRecvBufferSize, m_initialSendBufferSize);
#endif

    m_socket->SetPeer(addr_man.GetAddress());
    err = m_socket->Connect(GSOCK_STREAMED);

    //this will register for callbacks - must be called after m_socket->m_fd was initialized
    m_socket->Notify(m_notify);

    if (!wait)
        m_socket->SetNonBlocking(0);

    if (err != GSOCK_NOERROR)
    {
        if (err == GSOCK_WOULDBLOCK)
            m_establishing = true;

        return false;
    }

    m_connected = true;
    return true;
}

bool wxSocketClient::Connect(const wxSockAddress& addr_man, bool wait)
{
    return DoConnect(addr_man, NULL, wait);
}

bool wxSocketClient::Connect(const wxSockAddress& addr_man,
                             const wxSockAddress& local,
                             bool wait)
{
    return DoConnect(addr_man, &local, wait);
}

bool wxSocketClient::WaitOnConnect(long seconds, long milliseconds)
{
    if (m_connected)                      // Already connected
        return true;

    if (!m_establishing || !m_socket)     // No connection in progress
        return false;

    return _Wait(seconds, milliseconds, GSOCK_CONNECTION_FLAG |
                                        GSOCK_LOST_FLAG);
}

// ==========================================================================
// wxDatagramSocket
// ==========================================================================

/* NOTE: experimental stuff - might change */

wxDatagramSocket::wxDatagramSocket( const wxSockAddress& addr,
                                    wxSocketFlags flags )
                : wxSocketBase( flags, wxSOCKET_DATAGRAM )
{
    // Create the socket
    m_socket = GSocket_new();

    if (!m_socket)
    {
        wxFAIL_MSG( _T("datagram socket not new'd") );
        return;
    }
    m_socket->Notify(m_notify);
    // Setup the socket as non connection oriented
    m_socket->SetLocal(addr.GetAddress());
    if (flags & wxSOCKET_REUSEADDR)
    {
        m_socket->SetReusable();
    }
    if (GetFlags() & wxSOCKET_BROADCAST)
    {
        m_socket->SetBroadcast();
    }
    if (GetFlags() & wxSOCKET_NOBIND)
    {
        m_socket->DontDoBind();
    }
    if ( m_socket->SetNonOriented() != GSOCK_NOERROR )
    {
        delete m_socket;
        m_socket = NULL;
        return;
    }

    // Initialize all stuff
    m_connected = false;
    m_establishing = false;
    m_socket->SetTimeout( m_timeout );
    m_socket->SetCallback( GSOCK_INPUT_FLAG | GSOCK_OUTPUT_FLAG |
                           GSOCK_LOST_FLAG | GSOCK_CONNECTION_FLAG,
                           wx_socket_callback, (char*)this );
}

wxDatagramSocket& wxDatagramSocket::RecvFrom( wxSockAddress& addr,
                                              void* buf,
                                              wxUint32 nBytes )
{
    Read(buf, nBytes);
    GetPeer(addr);
    return (*this);
}

wxDatagramSocket& wxDatagramSocket::SendTo( const wxSockAddress& addr,
                                            const void* buf,
                                            wxUint32 nBytes )
{
    wxASSERT_MSG( m_socket, _T("Socket not initialised") );

    m_socket->SetPeer(addr.GetAddress());
    Write(buf, nBytes);
    return (*this);
}

// ==========================================================================
// wxSocketModule
// ==========================================================================

class wxSocketModule : public wxModule
{
public:
    virtual bool OnInit()
    {
        // wxSocketBase will call GSocket_Init() itself when/if needed
        return true;
    }

    virtual void OnExit()
    {
        if ( wxSocketBase::IsInitialized() )
            wxSocketBase::Shutdown();
    }

private:
    DECLARE_DYNAMIC_CLASS(wxSocketModule)
};

IMPLEMENT_DYNAMIC_CLASS(wxSocketModule, wxModule)

#endif // wxUSE_SOCKETS