path: root/src/lactcpconnection.c

/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- */

/*  Lac - Library for asynchronous communication
 *  Copyright (C) 2000, 2001, 2002, 2003, 2007  Søren Sandmann
 *
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Library General Public
 *  License as published by the Free Software Foundation; either
 *  version 2 of the License, or (at your option) any later version.
 *
 *  This library 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 GNU
 *  Library General Public License for more details.
 *
 *  You should have received a copy of the GNU Library General Public
 *  License along with this library; if not, write to the 
 *  Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 *  Boston, MA  02111-1307, USA.
 */

#include <string.h>
#include "lac.h"
#include "lacinternals.h"

/*
 * Prototypes for a primitive abstraction covering TCP and SSL
 */
typedef enum {
    UNDEFINED,
    CONNECT_IN_PROGRESS,
    CONNECTED,
    DISCONNECTED,
} ConnectionState;

struct _LacTcpConnection {
    int                         fd;
    LacTcpConnectionFunc        callback;
    gpointer                    data;

    GQueue *                    pending_events;
    
    ConnectionState             state;
    LacByteQueue *              unwritten;
    
    gboolean                    has_fd;
    gboolean                    in_emit_events;
    gboolean                    need_flush;
    gint                        ref_count;
};

static void
event_free (LacConnectionEvent *event)
{
    if (event->type == LAC_CONNECTION_EVENT_READ)
    {
        /* FIXME: at some point we should support pushing
         * data back into the queue, ie., it must be kept alive
         */
        lac_byte_queue_free (event->read.byte_queue, TRUE);
    }
    else if (event->type == LAC_CONNECTION_EVENT_ERROR)
        g_error_free ((GError *)event->error.err);
    
    g_free (event);
}

static void
queue_connect (LacTcpConnection *connection)
{
    LacConnectionEvent *event = g_new (LacConnectionEvent, 1);

    event->type = LAC_CONNECTION_EVENT_CONNECT;

    g_queue_push_tail (connection->pending_events, event);
}

static void
queue_read (LacTcpConnection *connection, LacByteQueue *queue)
{
    LacConnectionEvent *event = g_new (LacConnectionEvent, 1);
    
    event->type = LAC_CONNECTION_EVENT_READ;
    event->read.byte_queue = queue;
    event->read.data = lac_byte_queue_peek (queue, &(event->read.len));

    g_queue_push_tail (connection->pending_events, event);
}

static void
queue_close (LacTcpConnection *connection, gboolean remote)
{
    LacConnectionEvent *event = g_new (LacConnectionEvent, 1);

    event->type = LAC_CONNECTION_EVENT_CLOSE;
    event->close.remote_closed = remote;

    g_queue_push_tail (connection->pending_events, event);
}

static void
queue_error (LacTcpConnection *connection, const GError *err)
{
    LacConnectionEvent *event = g_new (LacConnectionEvent, 1);
    
    event->type = LAC_CONNECTION_EVENT_ERROR;
    event->error.err = g_error_copy (err);

    g_queue_push_tail (connection->pending_events, event);
}

static void
emit_events (LacTcpConnection *connection)
{
    LacConnectionEvent *event;

    if (connection->in_emit_events)
        return;

    connection->in_emit_events = TRUE;
    lac_tcp_connection_ref (connection);

    while ((event = g_queue_pop_head (connection->pending_events)))
    {
        if (connection->state != DISCONNECTED)
        {
            if (event->type == LAC_CONNECTION_EVENT_CLOSE ||
                event->type == LAC_CONNECTION_EVENT_ERROR)
            {
                connection->state = DISCONNECTED;

                if (connection->has_fd)
                {
                    lac_fd_remove_watch (connection->fd);
                    lac_close (connection->fd, NULL);
                    connection->has_fd = FALSE;
                }
            }
            
            connection->callback (connection, event);
        }
        
        event_free (event);
    }

    connection->in_emit_events = FALSE;
    lac_tcp_connection_unref (connection);
}

static gboolean
emit_events_idle_handler (gpointer data)
{
    LacTcpConnection *connection = data;
    emit_events (connection);

    lac_tcp_connection_unref (connection);

    return FALSE; /* don't call me again */
}

static void
emit_events_idle (LacTcpConnection *connection)
{
    if (!g_queue_is_empty (connection->pending_events))
    {
        lac_tcp_connection_ref (connection);
        
        g_idle_add (
            emit_events_idle_handler, connection);
    }
}

static void
lac_tcp_connection_do_reads (gpointer data)
{
    LacTcpConnection *connection = data;
    gint len;
    
    enum { BUF_SIZE = 8280 };

    do
    {
        GError *err = NULL;
        LacByteQueue *queue = lac_byte_queue_new ();
        gchar *buf = lac_byte_queue_alloc_tail (queue, BUF_SIZE);
        
        len = lac_recv (connection->fd, buf, BUF_SIZE, &err);

        if (len > 0)
        {
            lac_byte_queue_delete_tail (queue, BUF_SIZE - len);
        
            queue_read (connection, queue);
        }
        else
        {
            lac_byte_queue_free (queue, TRUE);
            
            if (len == 0)
            {
                queue_close (connection, TRUE);
            }
            else
            {
                g_assert (err);
                
                if (!g_error_matches (
                        err, LAC_SOCKET_ERROR, LAC_SOCKET_ERROR_AGAIN))
                {
                    queue_error (connection, err);
                }
                
                g_error_free (err);
            }
        }

        /* FIXME: check that we haven't used too much time? */
    }
    while (len == BUF_SIZE);
}

static void lac_tcp_connection_writable (gpointer data);

static void
lac_tcp_connection_do_writes (LacTcpConnection *connection)
{
    if (connection->state != CONNECTED)
    {
        lac_fd_set_write_callback (connection->fd, lac_tcp_connection_writable);
        return;
    }
    
    while (lac_byte_queue_get_length (connection->unwritten) > 0)
    {
        GError       *err = NULL;
        const gchar  *unwritten;
        gsize         len, sent;
        
        unwritten = lac_byte_queue_peek (connection->unwritten, &len);

        sent = lac_send (connection->fd, unwritten, len, &err);

        if (err)
        {
            if (g_error_matches (
                err, LAC_SOCKET_ERROR, LAC_SOCKET_ERROR_AGAIN))
            {
                lac_fd_set_write_callback (
                    connection->fd, lac_tcp_connection_writable);
            }
            else
            {
                queue_error (connection, err);
            }

            g_error_free (err);
            return;
        }

        lac_byte_queue_delete_head (connection->unwritten, sent);
        
        /* FIXME check that we haven't used too much time? */
    }

    lac_fd_set_write_callback (connection->fd, NULL);
    
    if (connection->need_flush)
    {
        lac_set_nagle (connection->fd, FALSE, NULL);
        lac_set_nagle (connection->fd, TRUE, NULL);

        connection->need_flush = FALSE;
    }
}

static void
lac_tcp_connection_readable (gpointer data)
{
    LacTcpConnection *connection = data;
    
    lac_tcp_connection_do_reads (connection);
    emit_events (connection);
}

static void
lac_tcp_connection_writable (gpointer data)
{
    LacTcpConnection *connection = data;
    
    if (connection->state == CONNECT_IN_PROGRESS)
    {
        connection->state = CONNECTED;
        queue_connect (connection);
    }

    lac_tcp_connection_do_writes (connection);
    emit_events (connection);
}

static void
lac_tcp_connection_connect (LacTcpConnection *connection,
                            const LacAddress *address,
                            int               port)
{
    GError *err = NULL;
    
    lac_connect (connection->fd, address, port, &err);

    if (err)
    {
        if (g_error_matches (
            err, LAC_SOCKET_ERROR, LAC_SOCKET_ERROR_IN_PROGRESS))
        {
            connection->state = CONNECT_IN_PROGRESS;
        }
        else
        {
            queue_error (connection, err);
        }

        g_error_free (err);
    }
    else
    {
        connection->state = CONNECTED;
        queue_connect (connection);
        lac_tcp_connection_do_writes (connection);
    }
}

static void
lac_tcp_connection_discard_pending_events (LacTcpConnection *connection)
{
    LacConnectionEvent *event;

    while ((event = g_queue_pop_head (connection->pending_events)))
        event_free (event);
}

static void
lac_tcp_connection_add_watch (LacTcpConnection *connection)
{
    lac_fd_add_watch (connection->fd, connection);

    lac_fd_set_read_callback (connection->fd, lac_tcp_connection_readable);
    lac_fd_set_write_callback (connection->fd, lac_tcp_connection_writable);
}

LacTcpConnection *
lac_tcp_connection_new (const LacAddress  *address,
                    gint               port,
                    LacTcpConnectionFunc  callback,
                    gpointer           data)
{
    LacTcpConnection *connection;
    GError *err = NULL;
    
    g_return_val_if_fail (address != NULL, NULL);
    g_return_val_if_fail (port > 0, NULL);
    g_return_val_if_fail (callback != NULL, NULL);
    
    connection = g_new (LacTcpConnection, 1);
    
    connection->ref_count = 1;
    
    connection->callback = callback;
    connection->data = data;

    connection->pending_events = g_queue_new ();
    
    connection->state = UNDEFINED;
    connection->has_fd = FALSE;
    connection->unwritten = lac_byte_queue_new ();
    
    connection->in_emit_events = FALSE;
    connection->need_flush = FALSE;
        
    connection->fd = lac_socket_tcp (&err);
    if (err)
    {
        queue_error (connection, err);
        emit_events_idle (connection);
        g_error_free (err);
        return connection;
    }

    connection->has_fd = TRUE;
    
    lac_set_blocking (connection->fd, FALSE, &err);
    if (err)
    {
        queue_error (connection, err);
        emit_events_idle (connection);
        g_error_free (err);
        return connection;
    }

    lac_tcp_connection_add_watch (connection);
    lac_tcp_connection_connect (connection, address, port);

    emit_events_idle (connection);
    
    return connection;
}

gpointer
lac_tcp_connection_get_data (LacTcpConnection     *connection)
{
    g_return_val_if_fail (connection != NULL, NULL);
    
    return connection->data;
}

void
lac_tcp_connection_write (LacTcpConnection     *connection,
                      const gchar       *data,
                      guint              len)
{
    gboolean do_writes;

    g_return_if_fail (connection != NULL);
    g_return_if_fail (data != NULL);
    g_return_if_fail (connection->state != DISCONNECTED);

    if (len == 0)
        return;
    
    do_writes = (lac_byte_queue_get_length (connection->unwritten) == 0);

    lac_byte_queue_append (connection->unwritten, data, len);

    if (do_writes)
    {
        lac_tcp_connection_do_writes (connection);
        emit_events (connection);
    }
}

void
lac_tcp_connection_write_cstr (LacTcpConnection     *connection,
                               const gchar       *data)
{
    guint len;
    
    g_return_if_fail (connection != NULL);
    g_return_if_fail (data != NULL);

    len = strlen (data);
    
    if (len > 0)
        lac_tcp_connection_write (connection, data, len);
}

void
lac_tcp_connection_close (LacTcpConnection    *connection)
{
    g_return_if_fail (connection != NULL);

    lac_tcp_connection_discard_pending_events (connection);

    queue_close (connection, FALSE);
    emit_events (connection);
}

LacTcpConnection *
lac_tcp_connection_ref (LacTcpConnection     *connection)
{
    ++connection->ref_count;
    
    return connection;
}

void
lac_tcp_connection_unref (LacTcpConnection     *connection)
{
    if (--connection->ref_count == 0)
    {
        lac_tcp_connection_discard_pending_events (connection);
        g_queue_free (connection->pending_events);

        lac_byte_queue_free (connection->unwritten, TRUE);
        
        if (connection->has_fd)
        {
            lac_fd_remove_watch (connection->fd);
            lac_close (connection->fd, NULL);
        }

        g_free (connection);
    }
}

gboolean
lac_tcp_connection_is_connected (LacTcpConnection *connection)
{
    return connection->state == CONNECTED;
}

void
lac_tcp_connection_flush (LacTcpConnection     *connection)
{
    connection->need_flush = TRUE;

    if (lac_byte_queue_get_length (connection->unwritten) == 0)
        lac_tcp_connection_do_writes (connection);
}