channels.h

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/*      $OpenBSD: channels.h,v 1.83 2005/12/30 15:56:37 reyk Exp $      */

/*
 * 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) 1999, 2000, 2001, 2002 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.
 */

#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            256

struct Channel;
typedef struct Channel Channel;

typedef void channel_callback_fn(int, void *);
typedef int channel_infilter_fn(struct Channel *, char *, int);
typedef u_char *channel_outfilter_fn(struct Channel *, u_char **, u_int *);

struct Channel {
        int     type;           /* channel type/state */
        int     self;           /* my own channel identifier */
        int     remote_id;      /* channel identifier for remote peer */
        u_int   istate;         /* input from channel (state of receive half) */
        u_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     ctl_fd;         /* control fd (client sharing) */
        int     isatty;         /* rfd is a tty */
        int     wfd_isatty;     /* wfd is a tty */
        int     client_tty;     /* (client) TTY has been requested */
        int     force_drain;    /* force close on iEOF */
        int     delayed;                /* fdset hack */
        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 */

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

        char   *ctype;          /* type */

        /* callback */
        channel_callback_fn     *confirm;
        void                    *confirm_ctx;
        channel_callback_fn     *detach_user;
        int                     detach_close;

        /* filter */
        channel_infilter_fn     *input_filter;
        channel_outfilter_fn    *output_filter;

        int     datagram;       /* keep boundaries */
};

#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_PACKET_DEFAULT (32*1024)
#define CHAN_SES_WINDOW_DEFAULT (4*CHAN_SES_PACKET_DEFAULT)
#define CHAN_TCP_PACKET_DEFAULT (32*1024)
#define CHAN_TCP_WINDOW_DEFAULT (4*CHAN_TCP_PACKET_DEFAULT)
#define CHAN_X11_PACKET_DEFAULT (16*1024)
#define CHAN_X11_WINDOW_DEFAULT (4*CHAN_X11_PACKET_DEFAULT)

/* possible input states */
#define CHAN_INPUT_OPEN                 0
#define CHAN_INPUT_WAIT_DRAIN           1
#define CHAN_INPUT_WAIT_OCLOSE          2
#define CHAN_INPUT_CLOSED               3

/* possible output states */
#define CHAN_OUTPUT_OPEN                0
#define CHAN_OUTPUT_WAIT_DRAIN          1
#define CHAN_OUTPUT_WAIT_IEOF           2
#define CHAN_OUTPUT_CLOSED              3

#define CHAN_CLOSE_SENT                 0x01
#define CHAN_CLOSE_RCVD                 0x02
#define CHAN_EOF_SENT                   0x04
#define CHAN_EOF_RCVD                   0x08

#define CHAN_RBUF       16*1024

/* check whether 'efd' is still in use */
#define CHANNEL_EFD_INPUT_ACTIVE(c) \
        (compat20 && c->extended_usage == CHAN_EXTENDED_READ && \
        (c->efd != -1 || \
        buffer_len(&c->extended) > 0))
#define CHANNEL_EFD_OUTPUT_ACTIVE(c) \
        (compat20 && c->extended_usage == CHAN_EXTENDED_WRITE && \
        c->efd != -1 && (!(c->flags & (CHAN_EOF_RCVD|CHAN_CLOSE_RCVD)) || \
        buffer_len(&c->extended) > 0))

/* channel management */

Channel *channel_by_id(int);
Channel *channel_lookup(int);
Channel *channel_new(char *, int, int, int, int, u_int, u_int, int, char *, int);
void     channel_set_fds(int, int, int, int, int, int, u_int);
void     channel_free(Channel *);
void     channel_free_all(void);
void     channel_stop_listening(void);

void     channel_send_open(int);
void     channel_request_start(int, char *, int);
void     channel_register_cleanup(int, channel_callback_fn *, int);
void     channel_register_confirm(int, channel_callback_fn *, void *);
void     channel_register_filter(int, channel_infilter_fn *, channel_outfilter_fn *);
void     channel_cancel_cleanup(int);
int      channel_close_fd(int *);
void     channel_send_window_changes(void);

/* protocol handler */

void     channel_input_close(int, u_int32_t, void *);
void     channel_input_close_confirmation(int, u_int32_t, void *);
void     channel_input_data(int, u_int32_t, void *);
void     channel_input_extended_data(int, u_int32_t, void *);
void     channel_input_ieof(int, u_int32_t, void *);
void     channel_input_oclose(int, u_int32_t, void *);
void     channel_input_open_confirmation(int, u_int32_t, void *);
void     channel_input_open_failure(int, u_int32_t, void *);
void     channel_input_port_open(int, u_int32_t, void *);
void     channel_input_window_adjust(int, u_int32_t, void *);

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

void     channel_prepare_select(fd_set **, fd_set **, int *, u_int*, int);
void     channel_after_select(fd_set *, fd_set *);
void     channel_output_poll(void);

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

/* tcp forwarding */
void     channel_set_af(int af);
void     channel_permit_all_opens(void);
void     channel_add_permitted_opens(char *, int);
void     channel_clear_permitted_opens(void);
void     channel_input_port_forward_request(int, int);
int      channel_connect_to(const char *, u_short);
int      channel_connect_by_listen_address(u_short);
void     channel_request_remote_forwarding(const char *, u_short,
             const char *, u_short);
int      channel_setup_local_fwd_listener(const char *, u_short,
             const char *, u_short, int);
void     channel_request_rforward_cancel(const char *host, u_short port);
int      channel_setup_remote_fwd_listener(const char *, u_short, int);
int      channel_cancel_rport_listener(const char *, u_short);

/* x11 forwarding */

int      x11_connect_display(void);
int      x11_create_display_inet(int, int, int, u_int *, int **);
void     x11_input_open(int, u_int32_t, void *);
void     x11_request_forwarding_with_spoofing(int, const char *, const char *,
            const char *);
void     deny_input_open(int, u_int32_t, void *);

/* agent forwarding */

void     auth_request_forwarding(void);

/* channel close */

int      chan_is_dead(Channel *, int);
void     chan_mark_dead(Channel *);

/* channel events */

void     chan_rcvd_oclose(Channel *);
void     chan_read_failed(Channel *);
void     chan_ibuf_empty(Channel *);

void     chan_rcvd_ieof(Channel *);
void     chan_write_failed(Channel *);
void     chan_obuf_empty(Channel *);

#endif

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