libssh2/src/packet.c

/* Copyright (c) 2004-2007, Sara Golemon <sarag@libssh2.org>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms,
 * with or without modification, are permitted provided
 * that the following conditions are met:
 *
 *   Redistributions of source code must retain the above
 *   copyright notice, this list of conditions and the
 *   following disclaimer.
 *
 *   Redistributions in binary form must reproduce the above
 *   copyright notice, this list of conditions and the following
 *   disclaimer in the documentation and/or other materials
 *   provided with the distribution.
 *
 *   Neither the name of the copyright holder nor the names
 *   of any other contributors may be used to endorse or
 *   promote products derived from this software without
 *   specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
 * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 */

#include "libssh2_priv.h"
#include <errno.h>
#include <fcntl.h>
#ifndef WIN32
#include <unistd.h>
#endif

/* Needed for struct iovec on some platforms */
#ifdef HAVE_SYS_UIO_H
#include <sys/uio.h>
#endif

#include <sys/time.h>
#include <sys/types.h>

#ifdef HAVE_POLL
# include <sys/poll.h>
#else
# ifdef HAVE_SELECT
#  ifdef HAVE_SYS_SELECT_H
#   include <sys/select.h>
#  else
#   include <sys/time.h>
#   include <sys/types.h>
#  endif
# endif
#endif

#include <inttypes.h>

inline int libssh2_packet_queue_listener(LIBSSH2_SESSION *session, unsigned char *data, unsigned long datalen);
inline int libssh2_packet_x11_open(LIBSSH2_SESSION *session, unsigned char *data, unsigned long datalen);

/* {{{ libssh2_packet_queue_listener
 * Queue a connection request for a listener
 */
inline int libssh2_packet_queue_listener(LIBSSH2_SESSION *session,
                                         unsigned char *data,
                                         unsigned long datalen)
{
        /* Look for a matching listener */
        unsigned char *s = data + (sizeof("forwarded-tcpip") - 1) + 5;
        /* 17 = packet_type(1) + channel(4) + reason(4) + descr(4) + lang(4) */
        unsigned long packet_len = 17 + (sizeof("Forward not requested") - 1);
        unsigned char *p, packet[17 + (sizeof("Forward not requested") - 1)];
        LIBSSH2_LISTENER *l = session->listeners;
        char failure_code = 1; /* SSH_OPEN_ADMINISTRATIVELY_PROHIBITED */
        uint32_t sender_channel, initial_window_size, packet_size;
        unsigned char *host, *shost;
        uint32_t port, sport, host_len, shost_len;
        (void)datalen;

        sender_channel = libssh2_ntohu32(s);            s += 4;

        initial_window_size = libssh2_ntohu32(s);       s += 4;
        packet_size = libssh2_ntohu32(s);                       s += 4;

        host_len = libssh2_ntohu32(s);                          s += 4;
        host = s;                                                                       s += host_len;
        port = libssh2_ntohu32(s);                                      s += 4;

        shost_len = libssh2_ntohu32(s);                         s += 4;
        shost = s;                                                                      s += shost_len;
        sport = libssh2_ntohu32(s);                                     s += 4;

        _libssh2_debug(session, LIBSSH2_DBG_CONN, "Remote received connection from %s:%ld to %s:%ld", shost, sport, host, port);

        while (l) {
                if ((l->port == (int)port) &&
                        (strlen(l->host) == host_len) &&
                        (memcmp(l->host, host, host_len) == 0)) {
                        /* This is our listener */
                        LIBSSH2_CHANNEL *channel, *last_queued = l->queue;

                        if (l->queue_maxsize &&
                                (l->queue_maxsize <= l->queue_size)) {
                                /* Queue is full */
                                failure_code = 4; /* SSH_OPEN_RESOURCE_SHORTAGE */
        _libssh2_debug(session, LIBSSH2_DBG_CONN, "Listener queue full, ignoring");
                                break;
                        }

                        channel = LIBSSH2_ALLOC(session, sizeof(LIBSSH2_CHANNEL));
                        if (!channel) {
                                libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate a channel for new connection", 0);
                                failure_code = 4; /* SSH_OPEN_RESOURCE_SHORTAGE */
                                break;
                        }
                        memset(channel, 0, sizeof(LIBSSH2_CHANNEL));

                        channel->session = session;
                        channel->channel_type_len = sizeof("forwarded-tcpip") - 1;
                        channel->channel_type = LIBSSH2_ALLOC(session, channel->channel_type_len + 1);
                        if (!channel->channel_type) {
                                libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate a channel for new connection", 0);
                                LIBSSH2_FREE(session, channel);
                                failure_code = 4; /* SSH_OPEN_RESOURCE_SHORTAGE */
                                break;
                        }
                        memcpy(channel->channel_type, "forwarded-tcpip", channel->channel_type_len + 1);

                        channel->remote.id = sender_channel;
                        channel->remote.window_size_initial = LIBSSH2_CHANNEL_WINDOW_DEFAULT;
                        channel->remote.window_size = LIBSSH2_CHANNEL_WINDOW_DEFAULT;
                        channel->remote.packet_size = LIBSSH2_CHANNEL_PACKET_DEFAULT;

                        channel->local.id = libssh2_channel_nextid(session);
                        channel->local.window_size_initial = initial_window_size;
                        channel->local.window_size = initial_window_size;
                        channel->local.packet_size = packet_size;

        _libssh2_debug(session, LIBSSH2_DBG_CONN, "Connection queued: channel %lu/%lu win %lu/%lu packet %lu/%lu",
                                                                                                                channel->local.id, channel->remote.id,
                                                                                                                channel->local.window_size, channel->remote.window_size,
                                                                                                                channel->local.packet_size, channel->remote.packet_size);

                        p = packet;
                        *(p++) = SSH_MSG_CHANNEL_OPEN_CONFIRMATION;
                        libssh2_htonu32(p, channel->remote.id);                                         p += 4;
                        libssh2_htonu32(p, channel->local.id);                                          p += 4;
                        libssh2_htonu32(p, channel->remote.window_size_initial);        p += 4;
                        libssh2_htonu32(p, channel->remote.packet_size);                        p += 4;

                        if (libssh2_packet_write(session, packet, 17)) {
                                libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send channel open confirmation", 0);
                                return -1;
                        }

                        /* Link the channel into the end of the queue list */

                        if (!last_queued) {
                                l->queue = channel;
                                return 0;
                        }

                        while (last_queued->next) last_queued = last_queued->next;

                        last_queued->next = channel;
                        channel->prev = last_queued;

                        l->queue_size++;

                        return 0;
                }

                l = l->next;
        }

        /* We're not listening to you */
        {

                p = packet;
                *(p++) = SSH_MSG_CHANNEL_OPEN_FAILURE;
                libssh2_htonu32(p, sender_channel);             p += 4;
                libssh2_htonu32(p, failure_code);               p += 4;
                libssh2_htonu32(p, sizeof("Forward not requested") - 1);        p += 4;
                memcpy(s, "Forward not requested", sizeof("Forward not requested") - 1);        p += sizeof("Forward not requested") - 1;
                libssh2_htonu32(p, 0);

                if (libssh2_packet_write(session, packet, packet_len)) {
                        libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send open failure", 0);
                        return -1;
                }
                return 0;
        }
}
/* }}} */

/* {{{ libssh2_packet_x11_open
 * Accept a forwarded X11 connection
 */
inline int libssh2_packet_x11_open(LIBSSH2_SESSION *session,
                                   unsigned char *data, unsigned long datalen)
{
        int failure_code = 2; /* SSH_OPEN_CONNECT_FAILED */
        unsigned char *s = data + (sizeof("x11") - 1) + 5;
        unsigned long packet_len = 17 + (sizeof("X11 Forward Unavailable") - 1);
        unsigned char *p, packet[17 + (sizeof("X11 Forward Unavailable") - 1)];
                                        /* packet_type(1) + channel(4) + reason(4) + descr(4) + lang(4) */
        LIBSSH2_CHANNEL *channel;
        unsigned long sender_channel, initial_window_size, packet_size;
        unsigned char *shost;
        unsigned long sport, shost_len;
        (void)datalen;

        sender_channel = libssh2_ntohu32(s);                    s += 4;
        initial_window_size = libssh2_ntohu32(s);               s += 4;
        packet_size = libssh2_ntohu32(s);                               s += 4;
        shost_len = libssh2_ntohu32(s);                                 s += 4;
        shost = s;                                                                              s += shost_len;
        sport = libssh2_ntohu32(s);                                             s += 4;

        _libssh2_debug(session, LIBSSH2_DBG_CONN, "X11 Connection Received from %s:%ld on channel %lu", shost, sport, sender_channel);
        if (session->x11) {
                channel = LIBSSH2_ALLOC(session, sizeof(LIBSSH2_CHANNEL));
                if (!channel) {
                        libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate a channel for new connection", 0);
                        failure_code = 4; /* SSH_OPEN_RESOURCE_SHORTAGE */
                        goto x11_exit;
                }
                memset(channel, 0, sizeof(LIBSSH2_CHANNEL));

                channel->session = session;
                channel->channel_type_len = sizeof("x11") - 1;
                channel->channel_type = LIBSSH2_ALLOC(session, channel->channel_type_len + 1);
                if (!channel->channel_type) {
                        libssh2_error(session, LIBSSH2_ERROR_ALLOC, "Unable to allocate a channel for new connection", 0);
                        LIBSSH2_FREE(session, channel);
                        failure_code = 4; /* SSH_OPEN_RESOURCE_SHORTAGE */
                        goto x11_exit;
                }
                memcpy(channel->channel_type, "x11", channel->channel_type_len + 1);

                channel->remote.id = sender_channel;
                channel->remote.window_size_initial = LIBSSH2_CHANNEL_WINDOW_DEFAULT;
                channel->remote.window_size = LIBSSH2_CHANNEL_WINDOW_DEFAULT;
                channel->remote.packet_size = LIBSSH2_CHANNEL_PACKET_DEFAULT;

                channel->local.id = libssh2_channel_nextid(session);
                channel->local.window_size_initial = initial_window_size;
                channel->local.window_size = initial_window_size;
                channel->local.packet_size = packet_size;

        _libssh2_debug(session, LIBSSH2_DBG_CONN, "X11 Connection established: channel %lu/%lu win %lu/%lu packet %lu/%lu",
                                                                                                                channel->local.id, channel->remote.id,
                                                                                                                channel->local.window_size, channel->remote.window_size,
                                                                                                                channel->local.packet_size, channel->remote.packet_size);
                p = packet;
                *(p++) = SSH_MSG_CHANNEL_OPEN_CONFIRMATION;
                libssh2_htonu32(p, channel->remote.id);                                         p += 4;
                libssh2_htonu32(p, channel->local.id);                                          p += 4;
                libssh2_htonu32(p, channel->remote.window_size_initial);        p += 4;
                libssh2_htonu32(p, channel->remote.packet_size);                        p += 4;

                if (libssh2_packet_write(session, packet, 17)) {
                        libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send channel open confirmation", 0);
                        return -1;
                }

                /* Link the channel into the session */
                if (session->channels.tail) {
                        session->channels.tail->next = channel;
                        channel->prev = session->channels.tail;
                } else {
                        session->channels.head = channel;
                        channel->prev = NULL;
                }
                channel->next = NULL;
                session->channels.tail = channel;

                /*
                 * Pass control to the callback, they may turn right around and
                 * free the channel, or actually use it
                 */
                LIBSSH2_X11_OPEN(channel, (char *)shost, sport);

                return 0;
        } else {
                failure_code = 4; /* SSH_OPEN_RESOURCE_SHORTAGE */
        }

 x11_exit:
        p = packet;
        *(p++) = SSH_MSG_CHANNEL_OPEN_FAILURE;
        libssh2_htonu32(p, sender_channel);                             p += 4;
        libssh2_htonu32(p, failure_code);                               p += 4;
        libssh2_htonu32(p, sizeof("X11 Forward Unavailable") - 1);              p += 4;
        memcpy(s, "X11 Forward Unavailable", sizeof("X11 Forward Unavailable") - 1); p += sizeof("X11 Forward Unavailable") - 1;
        libssh2_htonu32(p, 0);

        if (libssh2_packet_write(session, packet, packet_len)) {
                libssh2_error(session, LIBSSH2_ERROR_SOCKET_SEND, "Unable to send open failure", 0);
                return -1;
        }
        return 0;
}
/* }}} */

/* {{{ libssh2_packet_new
 * Create a new packet and attach it to the brigade
 */
int libssh2_packet_add(LIBSSH2_SESSION *session, unsigned char *data, size_t datalen, int macstate)
{
        LIBSSH2_PACKET *packet;
        unsigned long data_head = 0;

        _libssh2_debug(session, LIBSSH2_DBG_TRANS, "Packet type %d received, length=%d", (int)data[0], (int)datalen);
        if (macstate == LIBSSH2_MAC_INVALID) {
                if (session->macerror) {
                        if (LIBSSH2_MACERROR(session, (char *)data, datalen) == 0) {
                                /* Calling app has given the OK, Process it anyway */
                                macstate = LIBSSH2_MAC_CONFIRMED;
                        } else {
                                libssh2_error(session, LIBSSH2_ERROR_INVALID_MAC, "Invalid Message Authentication Code received", 0);
                                if (session->ssh_msg_disconnect) {
                                        LIBSSH2_DISCONNECT(session, SSH_DISCONNECT_MAC_ERROR, "Invalid MAC received", sizeof("Invalid MAC received") - 1, "", 0);
                                }
                                return -1;
                        }
                } else {
                        libssh2_error(session, LIBSSH2_ERROR_INVALID_MAC, "Invalid Message Authentication Code received", 0);
                        if (session->ssh_msg_disconnect) {
                                LIBSSH2_DISCONNECT(session, SSH_DISCONNECT_MAC_ERROR, "Invalid MAC received", sizeof("Invalid MAC received") - 1, "", 0);
                        }
                        return -1;
                }
        }

        /* A couple exceptions to the packet adding rule: */
        switch (data[0]) {
                case SSH_MSG_DISCONNECT:
                {
                        char *message, *language;
                        int reason, message_len, language_len;

                        reason = libssh2_ntohu32(data + 1);
                        message_len = libssh2_ntohu32(data + 5);
                        message = (char *)data + 9; /* packet_type(1) + reason(4) + message_len(4) */
                        language_len = libssh2_ntohu32(data + 9 + message_len);
                        /* This is where we hack on the data a little,
                         * Use the MSB of language_len to to a terminating NULL (In all liklihood it is already)
                         * Shift the language tag back a byte (In all likelihood it's zero length anyway
                         * Store a NULL in the last byte of the packet to terminate the language string
                         * With the lengths passed this isn't *REALLY* necessary, but it's "kind"
                         */
                        message[message_len] = '\0';
                        language = (char *)data + 9 + message_len + 3;
                        if (language_len) {
                                memcpy(language, language + 1, language_len);
                        }
                        language[language_len] = '\0';

                        if (session->ssh_msg_disconnect) {
                                LIBSSH2_DISCONNECT(session, reason, message, message_len, language, language_len);
                        }
			_libssh2_debug(session, LIBSSH2_DBG_TRANS, "Disconnect(%d): %s(%s)", reason, message, language);
                        LIBSSH2_FREE(session, data);
                        session->socket_state = LIBSSH2_SOCKET_DISCONNECTED;
                        return -1;
                }
                        break;
                case SSH_MSG_IGNORE:
                        /* As with disconnect, back it up one and add a trailing NULL */
                        memcpy(data + 4, data + 5, datalen - 5);
                        data[datalen] = '\0';
                        if (session->ssh_msg_ignore) {
                                LIBSSH2_IGNORE(session, (char *)data + 4, datalen - 5);
                        }
                        LIBSSH2_FREE(session, (char *)data);
                        return 0;
                        break;
                case SSH_MSG_DEBUG:
                {
                        int always_display = data[0];
                        char *message, *language;
                        int message_len, language_len;

                        message_len = libssh2_ntohu32(data + 2);
                        message = (char *)data + 6; /* packet_type(1) + display(1) + message_len(4) */
                        language_len = libssh2_ntohu32(data + 6 + message_len);
                        /* This is where we hack on the data a little,
                         * Use the MSB of language_len to to a terminating NULL (In all liklihood it is already)
                         * Shift the language tag back a byte (In all likelihood it's zero length anyway
                         * Store a NULL in the last byte of the packet to terminate the language string
                         * With the lengths passed this isn't *REALLY* necessary, but it's "kind"
                         */
                        message[message_len] = '\0';
                        language = (char *)data + 6 + message_len + 3;
                        if (language_len) {
                                memcpy(language, language + 1, language_len);
                        }
                        language[language_len] = '\0';

                        if (session->ssh_msg_debug) {
                                LIBSSH2_DEBUG(session, always_display, message, message_len, language, language_len);
                        }
        /* _libssh2_debug will actually truncate this for us so that it's not an inordinate about of data */
        _libssh2_debug(session, LIBSSH2_DBG_TRANS, "Debug Packet: %s", message);
                        LIBSSH2_FREE(session, data);
                        return 0;
                }
                        break;
                case SSH_MSG_CHANNEL_EXTENDED_DATA:
                        data_head += 4; /* streamid(4) */
                case SSH_MSG_CHANNEL_DATA:
                        data_head += 9; /* packet_type(1) + channelno(4) + datalen(4) */
                        {
                                LIBSSH2_CHANNEL *channel = libssh2_channel_locate(session, libssh2_ntohu32(data + 1));

                                if (!channel) {
                                        libssh2_error(session, LIBSSH2_ERROR_CHANNEL_UNKNOWN, "Packet received for unknown channel, ignoring", 0);
                                        LIBSSH2_FREE(session, data);
                                        return 0;
                                }
#ifdef LIBSSH2DEBUG
{
        unsigned long stream_id = 0;

        if (data[0] == SSH_MSG_CHANNEL_EXTENDED_DATA) {
                stream_id = libssh2_ntohu32(data + 5);
        }

        _libssh2_debug(session, LIBSSH2_DBG_CONN, "%d bytes received for channel %lu/%lu stream #%lu", (int)(datalen - data_head), channel->local.id, channel->remote.id, stream_id);
}
#endif
                                if ((channel->remote.extended_data_ignore_mode == LIBSSH2_CHANNEL_EXTENDED_DATA_IGNORE) && (data[0] == SSH_MSG_CHANNEL_EXTENDED_DATA)) {
                                        /* Pretend we didn't receive this */
                                        LIBSSH2_FREE(session, data);

        _libssh2_debug(session, LIBSSH2_DBG_CONN, "Ignoring extended data and refunding %d bytes", (int)(datalen - 13));
                                        /* Adjust the window based on the block we just freed */
                                        libssh2_channel_receive_window_adjust(channel, datalen - 13, 0);

                                        return 0;
                                }

                                /* REMEMBER! remote means remote as source of data, NOT remote window! */
                                if (channel->remote.packet_size < (datalen - data_head)) {
                                        /* Spec says we MAY ignore bytes sent beyond packet_size */
                                        libssh2_error(session, LIBSSH2_ERROR_CHANNEL_PACKET_EXCEEDED, "Packet contains more data than we offered to receive, truncating", 0);
                                        datalen = channel->remote.packet_size + data_head;
                                }
                                if (channel->remote.window_size <= 0) {
                                        /* Spec says we MAY ignore bytes sent beyond window_size */
                                        libssh2_error(session, LIBSSH2_ERROR_CHANNEL_WINDOW_EXCEEDED, "The current receive window is full, data ignored", 0);
                                        LIBSSH2_FREE(session, data);
                                        return 0;
                                }
                                /* Reset EOF status */
                                channel->remote.eof = 0;

                                if ((datalen - data_head) > channel->remote.window_size) {
                                        libssh2_error(session, LIBSSH2_ERROR_CHANNEL_WINDOW_EXCEEDED, "Remote sent more data than current window allows, truncating", 0);
                                        datalen = channel->remote.window_size + data_head;
                                } else {
                                        /* Now that we've received it, shrink our window */
                                        channel->remote.window_size -= datalen - data_head;
                                }
                        }
                        break;
                case SSH_MSG_CHANNEL_EOF:
                        {
                                LIBSSH2_CHANNEL *channel = libssh2_channel_locate(session, libssh2_ntohu32(data + 1));

                                if (!channel) {
                                        /* We may have freed already, just quietly ignore this... */
                                        LIBSSH2_FREE(session, data);
                                        return 0;
                                }

				_libssh2_debug(session, LIBSSH2_DBG_CONN, "EOF received for channel %lu/%lu", channel->local.id, channel->remote.id);
                                channel->remote.eof = 1;

                                LIBSSH2_FREE(session, data);
                                return 0;
                        }
                        break;
            case SSH_MSG_CHANNEL_REQUEST:
                    {
                                if (libssh2_ntohu32(data+5) == sizeof("exit-status") - 1
                                        && !memcmp("exit-status", data + 9, sizeof("exit-status") - 1)) {

                                        /* we've got "exit-status" packet. Set the session value */
                                        LIBSSH2_CHANNEL *channel = libssh2_channel_locate(session, libssh2_ntohu32(data+1));

                                        if (channel) {
                                                channel->exit_status = libssh2_ntohu32(data + 9 + sizeof("exit-status"));
                                                _libssh2_debug(session, LIBSSH2_DBG_CONN, "Exit status %lu received for channel %lu/%lu", channel->exit_status, channel->local.id, channel->remote.id);
                                        }

                                        LIBSSH2_FREE(session, data);
                                        return 0;
                                }
                        }
                        break;
                case SSH_MSG_CHANNEL_CLOSE:
                        {
                                LIBSSH2_CHANNEL *channel = libssh2_channel_locate(session, libssh2_ntohu32(data + 1));

                                if (!channel) {
                                        /* We may have freed already, just quietly ignore this... */
                                        LIBSSH2_FREE(session, data);
                                        return 0;
                                }
        _libssh2_debug(session, LIBSSH2_DBG_CONN, "Close received for channel %lu/%lu", channel->local.id, channel->remote.id);

                                channel->remote.close = 1;
                                channel->remote.eof = 1;
                                /* TODO: Add a callback for this */

                                LIBSSH2_FREE(session, data);
                                return 0;
                        }
                        break;
                case SSH_MSG_CHANNEL_OPEN:
                        if ((datalen >= (sizeof("forwarded-tcpip") + 4)) &&
                                ((sizeof("forwarded-tcpip")-1) == libssh2_ntohu32(data + 1)) &&
                                (memcmp(data + 5, "forwarded-tcpip", sizeof("forwarded-tcpip") - 1) == 0)) {
                                int retval = libssh2_packet_queue_listener(session, data, datalen);

                                LIBSSH2_FREE(session, data);
                                return retval;
                        }
                        if ((datalen >= (sizeof("x11") + 4)) &&
                                ((sizeof("x11")-1) == libssh2_ntohu32(data + 1)) &&
                                (memcmp(data + 5, "x11", sizeof("x11") - 1) == 0)) {
                                int retval = libssh2_packet_x11_open(session, data, datalen);

                                LIBSSH2_FREE(session, data);
                                return retval;
                        }
                        break;
                case SSH_MSG_CHANNEL_WINDOW_ADJUST:
                        {
                                LIBSSH2_CHANNEL *channel = libssh2_channel_locate(session, libssh2_ntohu32(data + 1));
                                unsigned long bytestoadd = libssh2_ntohu32(data + 5);

                                if (channel && bytestoadd) {
                                        channel->local.window_size += bytestoadd;
                                }
        _libssh2_debug(session, LIBSSH2_DBG_CONN, "Window adjust received for channel %lu/%lu, adding %lu bytes, new window_size=%lu", channel->local.id, channel->remote.id, bytestoadd, channel->local.window_size);

                                LIBSSH2_FREE(session, data);
                                return 0;
                        }
                        break;
        }

        packet = LIBSSH2_ALLOC(session, sizeof(LIBSSH2_PACKET));
        memset(packet, 0, sizeof(LIBSSH2_PACKET));

        packet->data = data;
        packet->data_len = datalen;
        packet->data_head = data_head;
        packet->mac = macstate;
        packet->brigade = &session->packets;
        packet->next = NULL;

        if (session->packets.tail) {
                packet->prev = session->packets.tail;
                packet->prev->next = packet;
                session->packets.tail = packet;
        } else {
                session->packets.head = packet;
                session->packets.tail = packet;
                packet->prev = NULL;
        }

        if (data[0] == SSH_MSG_KEXINIT && !(session->state & LIBSSH2_STATE_EXCHANGING_KEYS)) {
                /* Remote wants new keys
                 * Well, it's already in the brigade,
                 * let's just call back into ourselves
                 */
		_libssh2_debug(session, LIBSSH2_DBG_TRANS,
			       "Renegotiating Keys");
                libssh2_kex_exchange(session, 1);
                /* If there was a key reexchange failure, let's just hope we didn't send NEWKEYS yet, otherwise remote will drop us like a rock */
        }

        return 0;
}
/* }}} */

/* {{{ libssh2_packet_ask
 * Scan the brigade for a matching packet type, optionally poll the socket for
 * a packet first
 */
int libssh2_packet_ask_ex(LIBSSH2_SESSION *session, unsigned char packet_type,
                          unsigned char **data, unsigned long *data_len,
                          unsigned long match_ofs,
                          const unsigned char *match_buf,
                          unsigned long match_len, int poll_socket)
{
        LIBSSH2_PACKET *packet = session->packets.head;

        if (poll_socket) {
                libssh2pack_t rc = libssh2_packet_read(session);
                if ((rc < 0) && !packet) {
                        return rc;
                }
        }
        _libssh2_debug(session, LIBSSH2_DBG_TRANS,
		       "Looking for packet of type: %d", (int)packet_type);

        while (packet) {
                if (packet->data[0] == packet_type &&
                    (packet->data_len >= (match_ofs + match_len)) &&
                    (!match_buf ||
                     (memcmp(packet->data + match_ofs, match_buf, match_len) == 0))) {
                        *data = packet->data;
                        *data_len = packet->data_len;

                        if (packet->prev) {
                                packet->prev->next = packet->next;
                        } else {
                                session->packets.head = packet->next;
                        }

                        if (packet->next) {
                                packet->next->prev = packet->prev;
                        } else {
                                session->packets.tail = packet->prev;
                        }

                        LIBSSH2_FREE(session, packet);

                        return 0;
                }
                packet = packet->next;
        }
        return -1;
}
/* }}} */

/* {{{ libssh2_packet_askv
 * Scan for any of a list of packet types in the brigade, optionally poll the
 * socket for a packet first
 */
int libssh2_packet_askv_ex(LIBSSH2_SESSION *session,
                           unsigned char *packet_types,
                           unsigned char **data,
                           unsigned long *data_len,
                           unsigned long match_ofs,
                           const unsigned char *match_buf,
                           unsigned long match_len, int poll_socket)
{
        int i, packet_types_len = strlen((char *)packet_types);

        for(i = 0; i < packet_types_len; i++) {
                if (0 == libssh2_packet_ask_ex(session, packet_types[i],
                                               data, data_len, match_ofs,
                                               match_buf, match_len,
                                               i ? 0 : poll_socket)) {
                        return 0;
                }
        }

        return -1;
}
/* }}} */

/* {{{ waitsocket
 * Returns
 * negative on error
 * >0 on incoming data
 * 0 on timeout
 *
 * FIXME: convert to use poll on systems that have it.
 */
int libssh2_waitsocket(LIBSSH2_SESSION *session,
		       long seconds)
{
	struct timeval timeout;
	int rc;
	fd_set fd;

	timeout.tv_sec = seconds;
	timeout.tv_usec = 0;

	FD_ZERO(&fd);

	FD_SET(session->socket_fd, &fd);

	rc = select(session->socket_fd+1, &fd, NULL, NULL, &timeout);

	return rc;
}

/* {{{ libssh2_packet_require
 * [BLOCKING] for LIBSSH2_READ_TIMEOUT seconds
 * Loops libssh2_packet_read() until the packet requested is available
 * SSH_DISCONNECT or a SOCKET_DISCONNECTED will cause a bailout
 *
 * Returns negative on error
 * Returns 0 when it has taken care of the requested packet.
 */

int libssh2_packet_require_ex(LIBSSH2_SESSION *session,
                              unsigned char packet_type,
                              unsigned char **data, unsigned long *data_len,
                              unsigned long match_ofs,
                              const unsigned char *match_buf,
                              unsigned long match_len)
{
        time_t start = time(NULL);

        if (libssh2_packet_ask_ex(session, packet_type, data, data_len,
                                  match_ofs, match_buf, match_len, 0) == 0) {
                /* A packet was available in the packet brigade */
                return 0;
        }

        _libssh2_debug(session, LIBSSH2_DBG_TRANS,
                       "Blocking until packet of type %d becomes available",
                       (int)packet_type);

        while (session->socket_state == LIBSSH2_SOCKET_CONNECTED) {
                libssh2pack_t ret = libssh2_packet_read(session);
                if ((ret < 0)  && (ret != PACKET_EAGAIN)) {
			/* an error which is not just because of blocking */
                        return ret;
                }
                if (packet_type == ret) {
                        /* Be lazy, let packet_ask pull it out of the
                           brigade */
                        ret = libssh2_packet_ask_ex(session, packet_type,
                                                    data, data_len, match_ofs,
                                                    match_buf, match_len, 0);
                        return ret;
                }
                else if (ret <= 0) {
                        /* nothing available, wait until data arrives or
                           we time out */
                        long left = LIBSSH2_READ_TIMEOUT -
                                (time(NULL) - start);

                        if((left <= 0) ||
			   (libssh2_waitsocket(session, left) <= 0)) {
                                return PACKET_TIMEOUT;
                        }
                }
        }

        /* Only reached if the socket died */
        return -1;
}
/* }}} */

/* {{{ libssh2_packet_burn
 * Loops libssh2_packet_read() until any packet is available and promptly discards it
 * Used during KEX exchange to discard badly guessed KEX_INIT packets
 */
int libssh2_packet_burn(LIBSSH2_SESSION *session)
{
        unsigned char *data;
        unsigned long data_len;
        unsigned char all_packets[255];
        int i;
        for(i = 1; i < 256; i++) all_packets[i - 1] = i;

        if (libssh2_packet_askv_ex(session, all_packets, &data, &data_len, 0,
                                   NULL, 0, 0) == 0) {
                i = data[0];
                /* A packet was available in the packet brigade, burn it */
                LIBSSH2_FREE(session, data);
                return i;
        }

        _libssh2_debug(session, LIBSSH2_DBG_TRANS,
		       "Blocking until packet becomes available to burn");

        while (session->socket_state == LIBSSH2_SOCKET_CONNECTED) {
                int ret = libssh2_packet_read(session);
                if (ret < 0) {
                        return ret;
                }
                if (ret == 0) {
                        /* FIXME: this might busyloop */
                        continue;
                }

                /* Be lazy, let packet_ask pull it out of the brigade */
                if (0 == libssh2_packet_ask_ex(session, ret, &data, &data_len,
                                               0, NULL, 0, 0)) {
                        /* Smoke 'em if you got 'em */
                        LIBSSH2_FREE(session, data);
                        return ret;
                }
        }

        /* Only reached if the socket died */
        return -1;
}
/* }}} */

/* {{{ libssh2_packet_requirev
 * [BLOCKING]
 * Loops libssh2_packet_read() until one of a list of packet types requested is
 * available
 * SSH_DISCONNECT or a SOCKET_DISCONNECTED will cause a bailout
 * packet_types is a null terminated list of packet_type numbers
 */

int libssh2_packet_requirev_ex(LIBSSH2_SESSION *session,
                               unsigned char *packet_types,
                               unsigned char **data, unsigned long *data_len,
                               unsigned long match_ofs,
                               const unsigned char *match_buf,
                               unsigned long match_len)
{
        time_t start = time(NULL);

        if (libssh2_packet_askv_ex(session, packet_types, data, data_len,
                                   match_ofs, match_buf, match_len, 0) == 0) {
                /* One of the packets listed was available in the packet
                   brigade */
                return 0;
        }

        while (session->socket_state != LIBSSH2_SOCKET_DISCONNECTED) {
                int ret = libssh2_packet_read(session);
                if ((ret < 0) && (ret != PACKET_EAGAIN)) {
                        return ret;
                }
                if (ret <= 0) {
                        long left = LIBSSH2_READ_TIMEOUT -
                                (time(NULL) - start);

                        if((left <= 0) ||
			   (libssh2_waitsocket(session, left) <= 0 )) {
                                return PACKET_TIMEOUT;
                        }
                }

                if (strchr((char *)packet_types, ret)) {
                        /* Be lazy, let packet_ask pull it out of the
                           brigade */
                        return libssh2_packet_askv_ex(session, packet_types,
                                                      data, data_len,
                                                      match_ofs, match_buf,
                                                      match_len, 0);
                }
        }

        /* Only reached if the socket died */
        return -1;
}
/* }}} */