channels.h

/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 */
/*
 * Copyright (c) 2000 Markus Friedl.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */
/* RCSID("$OpenBSD: channels.h,v 1.35 2001/05/31 10:30:15 markus Exp $"); */

#ifndef CHANNEL_H
#define CHANNEL_H

#include "buffer.h"

/* Definitions for channel types. */
#define SSH_CHANNEL_X11_LISTENER	1	/* Listening for inet X11 conn. */
#define SSH_CHANNEL_PORT_LISTENER	2	/* Listening on a port. */
#define SSH_CHANNEL_OPENING		3	/* waiting for confirmation */
#define SSH_CHANNEL_OPEN		4	/* normal open two-way channel */
#define SSH_CHANNEL_CLOSED		5	/* waiting for close confirmation */
#define SSH_CHANNEL_AUTH_SOCKET		6	/* authentication socket */
#define SSH_CHANNEL_X11_OPEN		7	/* reading first X11 packet */
#define SSH_CHANNEL_INPUT_DRAINING	8	/* sending remaining data to conn */
#define SSH_CHANNEL_OUTPUT_DRAINING	9	/* sending remaining data to app */
#define SSH_CHANNEL_LARVAL		10	/* larval session */
#define SSH_CHANNEL_RPORT_LISTENER	11	/* Listening to a R-style port  */
#define SSH_CHANNEL_CONNECTING		12
#define SSH_CHANNEL_DYNAMIC		13
#define SSH_CHANNEL_ZOMBIE		14	/* Almost dead. */
#define SSH_CHANNEL_MAX_TYPE		15

#define SSH_CHANNEL_PATH_LEN		30

/*
 * Data structure for channel data.  This is initialized in channel_new
 * and cleared in channel_free.
 */
struct Channel;
typedef struct Channel Channel;

typedef void channel_callback_fn(int id, void *arg);
typedef int channel_filter_fn(struct Channel *c, char *buf, int len);

struct Channel {
	int     type;		/* channel type/state */
	int     self;		/* my own channel identifier */
	int     remote_id;	/* channel identifier for remote peer */
	/* peer can be reached over encrypted connection, via packet-sent */
	int     istate;		/* input from channel (state of receive half) */
	int     ostate;		/* output to channel  (state of transmit half) */
	int     flags;		/* close sent/rcvd */
	int     rfd;		/* read fd */
	int     wfd;		/* write fd */
	int     efd;		/* extended fd */
	int     sock;		/* sock fd */
	int     isatty;		/* rfd is a tty */
	Buffer  input;		/* data read from socket, to be sent over
				 * encrypted connection */
	Buffer  output;		/* data received over encrypted connection for
				 * send on socket */
	Buffer  extended;
	char    path[SSH_CHANNEL_PATH_LEN];
		/* path for unix domain sockets, or host name for forwards */
	int     listening_port;	/* port being listened for forwards */
	int     host_port;	/* remote port to connect for forwards */
	char   *remote_name;	/* remote hostname */

	int	remote_window;
	int	remote_maxpacket;
	int	local_window;
	int	local_window_max;
	int	local_consumed;
	int	local_maxpacket;
	int     extended_usage;

	char   *ctype;		/* type */

	/* callback */
	channel_callback_fn	*cb_fn;
	void	*cb_arg;
	int	cb_event;
	channel_callback_fn	*dettach_user;

	/* filter */
	channel_filter_fn	*input_filter;
};

#define CHAN_EXTENDED_IGNORE		0
#define CHAN_EXTENDED_READ		1
#define CHAN_EXTENDED_WRITE		2

/* default window/packet sizes for tcp/x11-fwd-channel */
#define CHAN_SES_WINDOW_DEFAULT	(32*1024)
#define CHAN_SES_PACKET_DEFAULT	(CHAN_SES_WINDOW_DEFAULT/2)
#define CHAN_TCP_WINDOW_DEFAULT	(32*1024)
#define CHAN_TCP_PACKET_DEFAULT	(CHAN_TCP_WINDOW_DEFAULT/2)
#define CHAN_X11_WINDOW_DEFAULT	(4*1024)
#define CHAN_X11_PACKET_DEFAULT	(CHAN_X11_WINDOW_DEFAULT/2)

/* possible input states */
#define CHAN_INPUT_OPEN			0x01
#define CHAN_INPUT_WAIT_DRAIN		0x02
#define CHAN_INPUT_WAIT_OCLOSE		0x04
#define CHAN_INPUT_CLOSED		0x08

/* possible output states */
#define CHAN_OUTPUT_OPEN		0x10
#define CHAN_OUTPUT_WAIT_DRAIN		0x20
#define CHAN_OUTPUT_WAIT_IEOF		0x40
#define CHAN_OUTPUT_CLOSED		0x80

#define CHAN_CLOSE_SENT			0x01
#define CHAN_CLOSE_RCVD			0x02


/* channel management */

Channel	*channel_lookup(int id);
Channel *
channel_new(char *ctype, int type, int rfd, int wfd, int efd,
    int window, int maxpack, int extusage, char *remote_name, int nonblock);
void
channel_set_fds(int id, int rfd, int wfd, int efd,
    int extusage, int nonblock);
void    channel_free(Channel *c);

void	channel_send_open(int id);
void	channel_request(int id, char *service, int wantconfirm);
void	channel_request_start(int id, char *service, int wantconfirm);
void	channel_register_callback(int id, int mtype, channel_callback_fn *fn, void *arg);
void	channel_register_cleanup(int id, channel_callback_fn *fn);
void	channel_register_filter(int id, channel_filter_fn *fn);
void	channel_cancel_cleanup(int id);

/* protocol handler */

void	channel_input_channel_request(int type, int plen, void *ctxt);
void	channel_input_close(int type, int plen, void *ctxt);
void	channel_input_close_confirmation(int type, int plen, void *ctxt);
void	channel_input_data(int type, int plen, void *ctxt);
void	channel_input_extended_data(int type, int plen, void *ctxt);
void	channel_input_ieof(int type, int plen, void *ctxt);
void	channel_input_oclose(int type, int plen, void *ctxt);
void	channel_input_open_confirmation(int type, int plen, void *ctxt);
void	channel_input_open_failure(int type, int plen, void *ctxt);
void	channel_input_port_open(int type, int plen, void *ctxt);
void	channel_input_window_adjust(int type, int plen, void *ctxt);

/* file descriptor handling (read/write) */

void
channel_prepare_select(fd_set **readsetp, fd_set **writesetp, int *maxfdp,
    int rekeying);
void    channel_after_select(fd_set * readset, fd_set * writeset);
void    channel_output_poll(void);

int     channel_not_very_much_buffered_data(void);
void    channel_stop_listening(void);
void    channel_close_all(void);
int     channel_still_open(void);
char   *channel_open_message(void);
int	channel_find_open(void);

/* channel_tcpfwd.c */
int
channel_request_local_forwarding(u_short listen_port,
    const char *host_to_connect, u_short port_to_connect, int gateway_ports);
int
channel_request_forwarding(const char *listen_address, u_short listen_port,
    const char *host_to_connect, u_short port_to_connect, int gateway_ports,
    int remote_fwd);
void
channel_request_remote_forwarding(u_short port, const char *host,
    u_short remote_port);
void    channel_permit_all_opens(void);
void	channel_add_permitted_opens(char *host, int port);
void	channel_clear_permitted_opens(void);
void    channel_input_port_forward_request(int is_root, int gateway_ports);
int	channel_connect_to(const char *host, u_short host_port);
int	channel_connect_by_listen_adress(u_short listen_port);

/* x11 forwarding */

int	x11_connect_display(void);
//int	x11_check_cookie(Buffer *b);
char   *x11_create_display(int screen);
char   *x11_create_display_inet(int screen, int x11_display_offset);
void    x11_input_open(int type, int plen, void *ctxt);
void    x11_request_forwarding(void);
void
x11_request_forwarding_with_spoofing(int client_session_id,
    const char *proto, const char *data);
void	deny_input_open(int type, int plen, void *ctxt);

/* agent forwarding */

void    auth_request_forwarding(void);
char   *auth_get_socket_name(void);
int     auth_input_request_forwarding(struct passwd * pw);
void    auth_input_open_request(int type, int plen, void *ctxt);

/* channel close */

typedef void    chan_event_fn(Channel * c);

/* for the input state */
extern chan_event_fn	*chan_rcvd_oclose;
extern chan_event_fn	*chan_read_failed;
extern chan_event_fn	*chan_ibuf_empty;

/* for the output state */
extern chan_event_fn	*chan_rcvd_ieof;
extern chan_event_fn	*chan_write_failed;
extern chan_event_fn	*chan_obuf_empty;

int	chan_is_dead(Channel * c);
void	chan_mark_dead(Channel * c);
void    chan_init_iostates(Channel * c);
void	chan_init(void);

#endif