channel.c

/* channel.c
 *
 * $Id$
 */

/* lsh, an implementation of the ssh protocol
 *
 * Copyright (C) 1998 Niels Mller
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program 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
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "channel.h"

#include "format.h"
#include "io.h"
#include "read_data.h"
#include "ssh.h"
#include "werror.h"
#include "xalloc.h"

#include <assert.h>
#include <string.h>

#define GABA_DEFINE
#include "channel.h.x"
#undef GABA_DEFINE

#include "channel.c.x"

/* GABA:
   (class
     (name connection_service)
     (super command)
     (vars
       ; Supported global requests 
       (global_requests object alist)

       (channel_types object alist) ))

       ; Initialize connection (for instance, request channels to be 
       ; opened or services to be forwarded).

       ; (start object connection_startup)))
*/

/* GABA:
   (class
     (name global_request_handler)
     (super packet_handler)
     (vars
       (global_requests object alist)))
*/

/* GABA:
   (class
     (name channel_open_handler)
     (super packet_handler)
     (vars
       (channel_types object alist)))
*/

/* GABA:
   (class
     (name channel_open_response)
     (super channel_open_callback)
     (vars
       (remote_channel_number simple UINT32)
       (window_size simple UINT32)
       (max_packet simple UINT32)))
*/

struct lsh_string *format_global_failure(void)
{
  return ssh_format("%c", SSH_MSG_REQUEST_FAILURE);
}

struct lsh_string *format_global_success(void)
{
  return ssh_format("%c", SSH_MSG_REQUEST_SUCCESS);
}

struct lsh_string *format_open_confirmation(struct ssh_channel *channel,
					    UINT32 channel_number,
					    const char *format, ...)
{
  va_list args;
  UINT32 l1, l2;
  struct lsh_string *packet;

#define CONFIRM_FORMAT "%c%i%i%i%i"
#define CONFIRM_ARGS \
  SSH_MSG_CHANNEL_OPEN_CONFIRMATION, channel->channel_number, \
  channel_number, channel->rec_window_size, channel->rec_max_packet
    
  l1 = ssh_format_length(CONFIRM_FORMAT, CONFIRM_ARGS);

  va_start(args, format);
  l2 = ssh_vformat_length(format, args);
  va_end(args);

  packet = lsh_string_alloc(l1 + l2);

  ssh_format_write(CONFIRM_FORMAT, l1, packet->data, CONFIRM_ARGS);

  va_start(args, format);
  ssh_vformat_write(format, l2, packet->data+l1, args);
  va_end(args);

  return packet;
#undef CONFIRM_FORMAT
#undef CONFIRM_ARGS
}

struct lsh_string *format_open_failure(UINT32 channel, UINT32 reason,
				       const char *msg, const char *language)
{
  return ssh_format("%c%i%i%z%z", SSH_MSG_CHANNEL_OPEN_FAILURE,
		    channel, reason, msg, language);
}

struct lsh_string *format_channel_success(UINT32 channel)
{
  return ssh_format("%c%i", SSH_MSG_CHANNEL_SUCCESS, channel);
}

struct lsh_string *format_channel_failure(UINT32 channel)
{
  return ssh_format("%c%i", SSH_MSG_CHANNEL_FAILURE, channel);
}

struct lsh_string *prepare_window_adjust(struct ssh_channel *channel,
					 UINT32 add)
{
  channel->rec_window_size += add;
  
  return ssh_format("%c%i%i",
		    SSH_MSG_CHANNEL_WINDOW_ADJUST,
		    channel->channel_number, add);
}

/* Channel objects */

#define INITIAL_CHANNELS 32
/* Arbitrary limit */
#define MAX_CHANNELS (1L<<17)

struct channel_table *make_channel_table(void)
{
  NEW(channel_table, table);

  table->channels = lsh_space_alloc(sizeof(struct ssh_channel *)
				      * INITIAL_CHANNELS);
  table->allocated_channels = INITIAL_CHANNELS;
  table->next_channel = 0;
  table->used_channels = 0;
  table->max_channels = MAX_CHANNELS;

  table->pending_close = 0;

  object_queue_init(&table->active_global_requests);
  object_queue_init(&table->pending_global_requests);
  
  return table;
};

/* Returns -1 if allocation fails */
/* NOTE: This function returns locally chosen channel numbers, which
 * are always small integers. So there's no problem fitting them in
 * a signed int. */
int alloc_channel(struct channel_table *table)
{
  UINT32 i;
  
  for(i = table->next_channel; i < table->used_channels; i++)
    {
      if (!table->channels[i])
	{
	  table->next_channel = i+1;
	  return i;
	}
    }
  if (i == table->max_channels)
    return -1;

  if (i == table->allocated_channels) 
    {
      int new_size = table->allocated_channels * 2;
      struct ssh_channel **new
	= lsh_space_alloc(sizeof(struct ssh_channel *) * new_size);

      memcpy(new, table->channels,
	     sizeof(struct ssh_channel *) * table->used_channels);
      
      table->channels = new;
      table->allocated_channels = new_size;
    }

  table->next_channel = table->used_channels = i+1;

  return i;
}

void dealloc_channel(struct channel_table *table, int i)
{
  assert(i >= 0);
  assert( (unsigned) i < table->used_channels);
  
  table->channels[i] = NULL;

  if ( (unsigned) i < table->next_channel)
    table->next_channel = i;
}

/* Returns -1 if no channel number can be allocated. See also the note
 * for alloc_channel(). */
int register_channel(struct channel_table *table, struct ssh_channel *channel)
{
  int n = alloc_channel(table);

  if (n >= 0)
    table->channels[n] = channel;

  return n;
}

struct ssh_channel *lookup_channel(struct channel_table *table, UINT32 i)
{
  return (i < table->used_channels)
    ? table->channels[i] : NULL;
}

static int adjust_rec_window(struct ssh_channel *channel)
{
  if (channel->rec_window_size < channel->max_window / 2)
    return A_WRITE(channel->write,
		   prepare_window_adjust
		   (channel, channel->max_window - channel->rec_window_size));
  else
    return 0;
}

/* Process channel-related status codes. Used by the packet handlers,
 * before returning. */
static int channel_process_status(struct channel_table *table,
				  int channel,
				  int status)
{
  struct ssh_channel *c = table->channels[channel];
  
  while (!LSH_CLOSEDP(status))
    {
      if (status & LSH_CHANNEL_CLOSE)
	{ /* Close the channel now */ 
	  if (!c->flags & CHANNEL_SENT_CLOSE)
	    status |= channel_close(c);
	  break;
	}
      
      if (status & LSH_CHANNEL_READY_SEND)
	{
	  status &= ~ LSH_CHANNEL_READY_SEND;
	  if (c->send_window_size)
	    status |= CHANNEL_SEND(c);
	}
      else if (status & LSH_CHANNEL_READY_REC)
	{
	  status &= ~ LSH_CHANNEL_READY_REC;
	  status |= adjust_rec_window(c);
	}
      else
	break;
    }
	
  if (status & LSH_CHANNEL_FINISHED)
    {
      /* Clear this bit */
      status &= ~LSH_CHANNEL_FINISHED;

      if (c->close)
	status |= CHANNEL_CLOSE(c);
      
      dealloc_channel(table, channel);
    }

  if (status & LSH_CHANNEL_PENDING_CLOSE)
    table->pending_close = 1;
  
  /* If this was the last channel, close connection */
  if (table->pending_close && !table->next_channel)
    status |= LSH_CLOSE;

  return status;
}

/* Ugly macros to make it a little simpler to free the input packet at
 * the right time. */

#define START int foo_res
#define RETURN(x) do { foo_res = (x); goto foo_finish; } while(0)
#define END(s) foo_finish: do { lsh_string_free((s)); return foo_res; } while(0)

/* Channel related messages */

/* GABA:
   (class
     (name global_request_status)
     (vars
       ; -1 for still active requests,
       ; 0 for failure,
       ; 1 for success
       (status . int)))
*/

static struct global_request_status *make_global_request_status(void)
{
  NEW(global_request_status, self);
  self->status = -1;

  return self;
}

/* GABA:
   (class
     (name global_request_response)
     (super global_request_callback)
     (vars
       (active object global_request_status)))
*/

static int
do_global_request_response(struct global_request_callback *c,
			   int success)
{
  CAST(global_request_response, self, c);
  struct object_queue *q = &self->super.connection->channels->active_global_requests;

  int res = 0;
  
  assert( self->active->status == -1);
  assert( (success == 0) || (success == 1) );
  assert( !object_queue_is_empty(q));
	  
  self->active->status = success;

  for (;;)
    {
      CAST(global_request_status, n, object_queue_peek_head(q));
      if (!n || (n->status < 0))
	return res;

      object_queue_remove_head(q);
      
      res |= A_WRITE(self->super.connection->write,
		     (n->status
		      ? format_global_success()
		      : format_global_failure()));
      
      if (LSH_CLOSEDP(res))
	return res;
    }
}

static struct global_request_callback *
make_global_request_response(struct ssh_connection *connection,
			     struct global_request_status *active)
{
  NEW(global_request_response, self);

  self->super.connection = connection;
  self->super.response = do_global_request_response;

  self->active = active;

  return &self->super;
}
     
static int do_global_request(struct packet_handler *c,
			     struct ssh_connection *connection,
			     struct lsh_string *packet)
{
  CAST(global_request_handler, closure, c);

  struct simple_buffer buffer;
  unsigned msg_number;
  int name;
  int want_reply;
  START;
  
  simple_buffer_init(&buffer, packet->length, packet->data);

  if (parse_uint8(&buffer, &msg_number)
      && (msg_number == SSH_MSG_GLOBAL_REQUEST)
      && parse_atom(&buffer, &name)
      && parse_boolean(&buffer, &want_reply))
    {
      struct global_request *req;
      struct global_request_callback *c = NULL;
      
      if (!name || !(req = ALIST_GET(closure->global_requests, name)))
	RETURN (A_WRITE(connection->write,
		       format_global_failure()));

      if (want_reply)
	{
	  struct global_request_status *a = make_global_request_status();

	  object_queue_add_tail(&connection->channels->active_global_requests,
				&a->super);
	  
	  c = make_global_request_response(connection, a);
	}
      RETURN (GLOBAL_REQUEST(req, connection, &buffer, c));
    }
  RETURN (LSH_FAIL | LSH_DIE);

  END (packet);
}

/* Callback given to the CHANNEL_OPEN method */
static int do_channel_open_response(struct channel_open_callback *c,
                                    struct ssh_channel *channel,
                                    UINT32 error, char *error_msg,
                                    struct lsh_string *args)
{
  CAST(channel_open_response, closure, c);
  
  int local_channel_number;

  if (!channel)
    {
      if (error)
        return A_WRITE(closure->super.connection->write,
                       format_open_failure(closure->remote_channel_number,
                                           error, error_msg, ""));
        /* The request was invalid */
        return LSH_FAIL | LSH_DIE;
    }

  if ( (local_channel_number
            = register_channel(closure->super.connection->channels,
			       channel)) < 0)
    {
      werror("Could not allocate a channel number for opened channel!\n");
      return A_WRITE(closure->super.connection->write,
                     format_open_failure(closure->remote_channel_number,
                                         SSH_OPEN_RESOURCE_SHORTAGE,
                                         "Could not allocate a channel number "
                                         "(shouldn't happen...)", ""));
    }

  /* FIXME: This copying could just as well be done by the
   * CHANNEL_OPEN handler? Then we can remove the corresponding fields
   * from the closure as well. */
  channel->send_window_size = closure->window_size;
  channel->send_max_packet = closure->max_packet;
  channel->channel_number = closure->remote_channel_number;

  /* FIXME: Is the channel->write field really needed? */
  channel->write = closure->super.connection->write;

  return A_WRITE(closure->super.connection->write,
                 args
                 ? format_open_confirmation(channel, local_channel_number,
                                            "%lfS", args)
                 : format_open_confirmation(channel, local_channel_number,
                                            ""));
}

static struct channel_open_response *
make_channel_open_response(struct ssh_connection* connection,
			   UINT32 remote_channel_number,
			   UINT32 window_size,
			   UINT32 max_packet)
{
  NEW(channel_open_response, closure);

  closure->super.response = do_channel_open_response;
  closure->super.connection = connection;
  closure->remote_channel_number = remote_channel_number;
  closure->window_size = window_size;
  closure->max_packet = max_packet;

  return closure;
}


#if 0
/* ;;GABA:
   (class
     (name channel_open_continuation)
     (super command_continuation)
     (vars
       (connection object ssh_connection)
       (remote_channel_number simple UINT32)
       (window_size simple UINT32)
       (max_packet simple UINT32)))
*/

static int do_channel_open_continue(struct command_continuation *c,
				    struct lsh_object *result)
{
  CAST(channel_open_continuation, self, c);
  CAST_SUBTYPE(channel);
}
#endif
				    
static int do_channel_open(struct packet_handler *c,
			   struct ssh_connection *connection,
			   struct lsh_string *packet)
{
  CAST(channel_open_handler, closure, c);

  struct simple_buffer buffer;
  unsigned msg_number;
  int type;
  UINT32 remote_channel_number;
  UINT32 window_size;
  UINT32 max_packet;
  START;
  
  simple_buffer_init(&buffer, packet->length, packet->data);

  if (parse_uint8(&buffer, &msg_number)
      && (msg_number == SSH_MSG_CHANNEL_OPEN)
      && parse_atom(&buffer, &type)
      && parse_uint32(&buffer, &remote_channel_number)
      && parse_uint32(&buffer, &window_size)
      && parse_uint32(&buffer, &max_packet))
    {
      struct channel_open *open;
      struct channel_open_response *response;
      int res;
      
      if (connection->channels->pending_close)
	/* We are waiting for channels to close. Don't open any new ones. */
	RETURN
	  (A_WRITE(connection->write,
		   format_open_failure(remote_channel_number,
				       SSH_OPEN_ADMINISTRATIVELY_PROHIBITED,
				       "Waiting for channels to close.", "")));
      
      if (!type || !(open = ALIST_GET(closure->channel_types, type)))
	RETURN (A_WRITE(connection->write,
			format_open_failure(remote_channel_number,
					    SSH_OPEN_UNKNOWN_CHANNEL_TYPE,
					    "Unknown channel type", "")));

      response = make_channel_open_response(connection,
					    remote_channel_number,
					    window_size, max_packet);
      /* NOTE: If the channel could be opened immediately, this method
       * will call response right away. */
      res = CHANNEL_OPEN(open, connection, &buffer, &response->super);

      RETURN (res);
    }
  RETURN (LSH_FAIL | LSH_DIE);

  END(packet);
}     

static int do_channel_request(struct packet_handler *closure UNUSED,
			      struct ssh_connection *connection,
			      struct lsh_string *packet)
{
  struct simple_buffer buffer;
  unsigned msg_number;
  UINT32 channel_number;
  int type;
  int want_reply;
  START;
  
  simple_buffer_init(&buffer, packet->length, packet->data);

  if (parse_uint8(&buffer, &msg_number)
      && (msg_number == SSH_MSG_CHANNEL_REQUEST)
      && parse_uint32(&buffer, &channel_number)
      && parse_atom(&buffer, &type)
      && parse_boolean(&buffer, &want_reply))
    {
      struct ssh_channel *channel = lookup_channel(connection->channels,
						   channel_number);

      /* NOTE: We can't free packet yet, because it is not yet fully
       * parsed. There may be some more arguments, which are parsed by
       * the CHANNEL_REQUEST method below. */

      if (channel)
	{
	  struct channel_request *req;

	  if (type && channel->request_types 
	      && ( (req = ALIST_GET(channel->request_types, type)) ))
	    RETURN
	      (channel_process_status
	       (connection->channels, channel_number,
		CHANNEL_REQUEST(req, channel, connection, want_reply, &buffer)));
	  else
	    RETURN (want_reply
		    ? A_WRITE(connection->write,
			      format_channel_failure(channel->channel_number))
		    : LSH_OK | LSH_GOON);
	  
	}
      werror("SSH_MSG_CHANNEL_REQUEST on nonexistant channel %i\n",
	     channel_number);

    }
  RETURN (LSH_FAIL | LSH_DIE);
  
  END(packet);
}
      
static int do_window_adjust(struct packet_handler *closure UNUSED,
			    struct ssh_connection *connection,
			    struct lsh_string *packet)
{
  struct simple_buffer buffer;
  unsigned msg_number;
  UINT32 channel_number;
  UINT32 size;

  simple_buffer_init(&buffer, packet->length, packet->data);

  if (parse_uint8(&buffer, &msg_number)
      && (msg_number == SSH_MSG_CHANNEL_WINDOW_ADJUST)
      && parse_uint32(&buffer, &channel_number)
      && parse_uint32(&buffer, &size)
      && parse_eod(&buffer))
    {
      struct ssh_channel *channel = lookup_channel(connection->channels,
						   channel_number);

      lsh_string_free(packet);
      
      if (channel
	  && !(channel->flags & (CHANNEL_RECEIVED_EOF
				 | CHANNEL_RECEIVED_CLOSE)))
	{
	  if (! (channel->flags & CHANNEL_SENT_CLOSE))
	    {
	      channel->send_window_size += size;
	      if (channel->send_window_size && channel->send)
		return channel_process_status(connection->channels,
					      channel_number,
					      CHANNEL_SEND(channel));
	    }
	  return LSH_OK | LSH_GOON;
	}
      /* FIXME: What to do now? Should unknown channel numbers be
       * ignored silently? */
      werror("SSH_MSG_CHANNEL_WINDOW_ADJUST on nonexistant or closed "
	     "channel %i\n", channel_number);
      return LSH_FAIL | LSH_DIE;
    }
  lsh_string_free(packet);

  return LSH_FAIL | LSH_DIE;
}

static int do_channel_data(struct packet_handler *closure UNUSED,
			   struct ssh_connection *connection,
			   struct lsh_string *packet)
{
  struct simple_buffer buffer;
  unsigned msg_number;
  UINT32 channel_number;
  struct lsh_string *data;
  
  simple_buffer_init(&buffer, packet->length, packet->data);

  if (parse_uint8(&buffer, &msg_number)
      && (msg_number == SSH_MSG_CHANNEL_DATA)
      && parse_uint32(&buffer, &channel_number)
      && ( (data = parse_string_copy(&buffer)) )
      && parse_eod(&buffer))
    {
      struct ssh_channel *channel = lookup_channel(connection->channels,
						   channel_number);

      lsh_string_free(packet);
      
      if (channel && channel->receive
	  && !(channel->flags & (CHANNEL_RECEIVED_EOF
				 | CHANNEL_RECEIVED_CLOSE)))
	{
	  if (channel->flags & CHANNEL_SENT_CLOSE)
	    {
	      werror("Ignoring data on channel which is closing\n");
	      return LSH_OK | LSH_GOON;
	    }
	  else
	    {
	      int res = 0;
	      
	      if (data->length > channel->rec_window_size)
		{
		  /* Truncate data to fit window */
		  werror("Channel data overflow. Extra data ignored.\n"); 
		  data->length = channel->rec_window_size;
		}

	      if (!data->length)
		/* Ignore data packet */
		return 0;
	      channel->rec_window_size -= data->length;

	      /* FIXME: Unconditionally adjusting the receive window
	       * breaks flow control. We better let the channel's
	       * receive method decide whether or not to receive more
	       * data. */
	      res = adjust_rec_window(channel);
	      
	      if (LSH_CLOSEDP(res))
		return res;

	      return channel_process_status(
		connection->channels, channel_number,
		res | CHANNEL_RECEIVE(channel, 
				      CHANNEL_DATA, data));
	    }
	  return LSH_OK | LSH_GOON;
	}
	  
      werror("Data on closed or non-existant channel %i\n",
	     channel_number);
      lsh_string_free(data);
      return LSH_FAIL | LSH_DIE;
    }
  lsh_string_free(packet);
  
  return LSH_FAIL | LSH_DIE;
}

static int do_channel_extended_data(struct packet_handler *closure UNUSED,
				    struct ssh_connection *connection,
				    struct lsh_string *packet)
{
  struct simple_buffer buffer;
  unsigned msg_number;
  UINT32 channel_number;
  UINT32 type;
  struct lsh_string *data;
  
  simple_buffer_init(&buffer, packet->length, packet->data);

  if (parse_uint8(&buffer, &msg_number)
      && (msg_number == SSH_MSG_CHANNEL_EXTENDED_DATA)
      && parse_uint32(&buffer, &channel_number)
      && parse_uint32(&buffer, &type)
      && ( (data = parse_string_copy(&buffer)) )
      && parse_eod(&buffer))
    {
      struct ssh_channel *channel = lookup_channel(connection->channels,
						   channel_number);

      lsh_string_free(packet);
      
      if (channel && channel->receive
	  && !(channel->flags & (CHANNEL_RECEIVED_EOF
				 | CHANNEL_RECEIVED_CLOSE)))
	{
	  if (channel->flags & CHANNEL_SENT_CLOSE)
	    {
	      werror("Ignoring extended data on channel which is closing\n");
	      return LSH_OK | LSH_GOON;
	    }
	  else
	    {
	      int res = 0;
	      
	      if (data->length > channel->rec_window_size)
		{
		  /* Truncate data to fit window */
		  werror("Channel extended data overflow. "
			 "Extra data ignored.\n");
		  data->length = channel->rec_window_size;
		}
	      
	      channel->rec_window_size -= data->length;

	      /* FIXME: Like for do_channel_data(), unconditionally
	       * adjusting the window breaks flow control. */
	      res = adjust_rec_window(channel);

	      if (LSH_CLOSEDP(res))
		return res;

	      switch(type)
		{
		case SSH_EXTENDED_DATA_STDERR:
		  return channel_process_status(
		    connection->channels, channel_number,
		    res | CHANNEL_RECEIVE(channel, 
					  CHANNEL_STDERR_DATA, data));
		default:
		  werror("Unknown type %i of extended data.\n",
			 type);
		  lsh_string_free(data);
		  return LSH_FAIL | LSH_DIE;
		}
	    }
	}
      werror("Extended data on closed or non-existant channel %i\n",
	     channel_number);
      lsh_string_free(data);
      return LSH_FAIL | LSH_DIE;
    }
  lsh_string_free(packet);
  
  return LSH_FAIL | LSH_DIE;
}

static int do_channel_eof(struct packet_handler *closure UNUSED,
			  struct ssh_connection *connection,
			  struct lsh_string *packet)
{
  struct simple_buffer buffer;
  unsigned msg_number;
  UINT32 channel_number;
  
  simple_buffer_init(&buffer, packet->length, packet->data);

  if (parse_uint8(&buffer, &msg_number)
      && (msg_number == SSH_MSG_CHANNEL_EOF)
      && parse_uint32(&buffer, &channel_number)
      && parse_eod(&buffer))
    {
      struct ssh_channel *channel = lookup_channel(connection->channels,
						   channel_number);

      lsh_string_free(packet);

      if (channel)
	{
	  int res = 0;
	  
	  if (channel->flags & (CHANNEL_RECEIVED_EOF | CHANNEL_RECEIVED_CLOSE))
	    {
	      werror("Receiving EOF on channel on closed channel.\n");
	      return LSH_FAIL | LSH_DIE;
	    }

	  channel->flags |= CHANNEL_RECEIVED_EOF;

	  if (channel->eof)
	    res = CHANNEL_EOF(channel);
	  else
	    /* FIXME: What is a reasonable default behaviour?
	     * Closing the channel may be the right thing to do. */
	    if (! (channel->flags & CHANNEL_SENT_CLOSE))
	      res |= channel_close(channel);
#if 0
	  if (!LSH_CLOSEDP(res)
	      && ! (channel->flags & CHANNEL_SENT_CLOSE)
	      && (channel->flags & CHANNEL_SENT_EOF))
	    {
	      /* Both parties have sent EOF. Initiate close, if we
	       * havn't done that already. */
	      
	      res |= channel_close(channel);
	    }
#endif      
	  return channel_process_status(connection->channels, channel_number,
					res);

	}
      werror("EOF on non-existant channel %i\n",
	     channel_number);
      return LSH_FAIL | LSH_DIE;
    }
      
  lsh_string_free(packet);
  return LSH_FAIL | LSH_DIE;
}

static int do_channel_close(struct packet_handler *closure UNUSED,
			    struct ssh_connection *connection,
			    struct lsh_string *packet)
{
  struct simple_buffer buffer;
  unsigned msg_number;
  UINT32 channel_number;
  
  simple_buffer_init(&buffer, packet->length, packet->data);

  if (parse_uint8(&buffer, &msg_number)
      && (msg_number == SSH_MSG_CHANNEL_CLOSE)
      && parse_uint32(&buffer, &channel_number)
      && parse_eod(&buffer))
    {
      struct ssh_channel *channel = lookup_channel(connection->channels,
						   channel_number);

      lsh_string_free(packet);
      
      if (channel)
	{
	  int res = 0;
	  
	  if (channel->flags & CHANNEL_RECEIVED_CLOSE)
	    {
	      werror("Receiving multiple CLOSE on channel.\n");
	      return LSH_FAIL | LSH_DIE;
	    }

	  channel->flags |= CHANNEL_RECEIVED_CLOSE;
	  
	  if (! (channel->flags & (CHANNEL_RECEIVED_EOF | CHANNEL_SENT_EOF)))
	    {
	      werror("Unexpected channel CLOSE.\n");
	    }

	  if (! (channel->flags & (CHANNEL_RECEIVED_EOF))
	      && channel->eof)
	    res = CHANNEL_EOF(channel);
	  
	  return channel_process_status(
	    connection->channels, channel_number,
	    ( ( (channel->flags & (CHANNEL_SENT_CLOSE))
		? LSH_OK | LSH_CHANNEL_FINISHED
		: channel_close(channel))
	      | res));
	}
      werror("CLOSE on non-existant channel %i\n",
	     channel_number);
      return LSH_FAIL | LSH_DIE;
      
    }
  lsh_string_free(packet);
  return LSH_FAIL | LSH_DIE;
}

static int do_channel_open_confirm(struct packet_handler *closure UNUSED,
				   struct ssh_connection *connection,
				   struct lsh_string *packet)
{
  struct simple_buffer buffer;
  unsigned msg_number;
  UINT32 local_channel_number;
  UINT32 remote_channel_number;  
  UINT32 window_size;
  UINT32 max_packet;
  
  simple_buffer_init(&buffer, packet->length, packet->data);

  if (parse_uint8(&buffer, &msg_number)
      && (msg_number == SSH_MSG_CHANNEL_OPEN_CONFIRMATION)
      && parse_uint32(&buffer, &local_channel_number)
      && parse_uint32(&buffer, &remote_channel_number)
      && parse_uint32(&buffer, &window_size)
      && parse_uint32(&buffer, &max_packet)
      && parse_eod(&buffer))
    {
      struct ssh_channel *channel = lookup_channel(connection->channels,
						   local_channel_number);

      lsh_string_free(packet);

      if (channel && channel->open_continuation)
	{
	  channel->channel_number = remote_channel_number;
	  channel->send_window_size = window_size;
	  channel->send_max_packet = max_packet;

	  return channel_process_status
	    (connection->channels,
	     local_channel_number,
	     COMMAND_RETURN(channel->open_continuation, channel));
	}
      werror("Unexpected SSH_MSG_CHANNEL_OPEN_CONFIRMATION on channel %i\n",
	     local_channel_number);
      return LSH_FAIL | LSH_DIE;
    }
  lsh_string_free(packet);
  return LSH_FAIL | LSH_DIE;
}

static int do_channel_open_failure(struct packet_handler *closure UNUSED,
			      struct ssh_connection *connection,
			      struct lsh_string *packet)
{
  struct simple_buffer buffer;
  unsigned msg_number;
  UINT32 channel_number;
  UINT32 reason;