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openssh/channels.h
djm@openbsd.org 35253af01d
upstream: when restoring non-blocking mode to stdio fds, restore 
exactly the flags that ssh started with and don't just clobber them with
zero, as this could also remove the append flag from the set;

bz3523; ok dtucker@

OpenBSD-Commit-ID: 1336b03e881db7564a4b66014eb24c5230e9a0c0
2023-01-18 13:21:00 +11:00

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/* $OpenBSD: channels.h,v 1.148 2023/01/18 02:00:10 djm 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
/* 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_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_MUX_LISTENER 15 /* Listener for mux conn. */
#define SSH_CHANNEL_MUX_CLIENT 16 /* Conn. to mux client */
#define SSH_CHANNEL_ABANDONED 17 /* Abandoned session, eg mux */
#define SSH_CHANNEL_UNIX_LISTENER 18 /* Listening on a domain socket. */
#define SSH_CHANNEL_RUNIX_LISTENER 19 /* Listening to a R-style domain socket. */
#define SSH_CHANNEL_MUX_PROXY 20 /* proxy channel for mux-client */
#define SSH_CHANNEL_RDYNAMIC_OPEN 21 /* reverse SOCKS, parsing request */
#define SSH_CHANNEL_RDYNAMIC_FINISH 22 /* reverse SOCKS, finishing connect */
#define SSH_CHANNEL_MAX_TYPE 23
#define CHANNEL_CANCEL_PORT_STATIC -1
/* nonblocking flags for channel_new */
#define CHANNEL_NONBLOCK_LEAVE 0 /* don't modify non-blocking state */
#define CHANNEL_NONBLOCK_SET 1 /* set non-blocking state */
#define CHANNEL_NONBLOCK_STDIO 2 /* set non-blocking and restore on close */
/* c->restore_block mask flags */
#define CHANNEL_RESTORE_RFD 0x01
#define CHANNEL_RESTORE_WFD 0x02
#define CHANNEL_RESTORE_EFD 0x04
/* TCP forwarding */
#define FORWARD_DENY 0
#define FORWARD_REMOTE (1)
#define FORWARD_LOCAL (1<<1)
#define FORWARD_ALLOW (FORWARD_REMOTE|FORWARD_LOCAL)
#define FORWARD_ADM 0x100
#define FORWARD_USER 0x101
struct ssh;
struct Channel;
typedef struct Channel Channel;
struct fwd_perm_list;
typedef void channel_open_fn(struct ssh *, int, int, void *);
typedef void channel_callback_fn(struct ssh *, int, int, void *);
typedef int channel_infilter_fn(struct ssh *, struct Channel *, char *, int);
typedef void channel_filter_cleanup_fn(struct ssh *, int, void *);
typedef u_char *channel_outfilter_fn(struct ssh *, struct Channel *,
u_char **, size_t *);
/* Channel success/failure callbacks */
typedef void channel_confirm_cb(struct ssh *, int, struct Channel *, void *);
typedef void channel_confirm_abandon_cb(struct ssh *, struct Channel *, void *);
struct channel_confirm {
TAILQ_ENTRY(channel_confirm) entry;
channel_confirm_cb *cb;
channel_confirm_abandon_cb *abandon_cb;
void *ctx;
};
TAILQ_HEAD(channel_confirms, channel_confirm);
/* Context for non-blocking connects */
struct channel_connect {
char *host;
int port;
struct addrinfo *ai, *aitop;
};
/* Callbacks for mux channels back into client-specific code */
typedef int mux_callback_fn(struct ssh *, struct Channel *);
/*
* NB. channel IDs on the wire and in c->remote_id are uint32, but local
* channel IDs (e.g. c->self) only ever use the int32 subset of this range,
* because we use local channel ID -1 for housekeeping. Remote channels have
* a dedicated "have_remote_id" flag to indicate their validity.
*/
struct Channel {
int type; /* channel type/state */
int self; /* my own channel identifier */
uint32_t remote_id; /* channel identifier for remote peer */
int have_remote_id; /* non-zero if remote_id is valid */
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 */
u_int io_want; /* bitmask of SSH_CHAN_IO_* */
u_int io_ready; /* bitmask of SSH_CHAN_IO_* */
int pfds[4]; /* pollfd entries for rfd/wfd/efd/sock */
int ctl_chan; /* control channel (multiplexed connections) */
int isatty; /* rfd is a tty */
#ifdef _AIX
int wfd_isatty; /* wfd is a tty */
#endif
int client_tty; /* (client) TTY has been requested */
int force_drain; /* force close on iEOF */
time_t notbefore; /* Pause IO until deadline (time_t) */
int delayed; /* post-IO handlers for newly created
* channels are delayed until the first call
* to a matching pre-IO handler.
* this way post-IO handlers are not
* accidentally called if a FD gets reused */
int restore_block; /* fd mask to restore blocking status */
int restore_flags[3];/* flags to restore */
struct sshbuf *input; /* data read from socket, to be sent over
* encrypted connection */
struct sshbuf *output; /* data received over encrypted connection for
* send on socket */
struct sshbuf *extended;
char *path;
/* path for unix domain sockets, or host name for forwards */
int listening_port; /* port being listened for forwards */
char *listening_addr; /* addr 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; /* const type - NB. not freed on channel_free */
char *xctype; /* extended type */
/* callback */
channel_open_fn *open_confirm;
void *open_confirm_ctx;
channel_callback_fn *detach_user;
int detach_close;
struct channel_confirms status_confirms;
/* filter */
channel_infilter_fn *input_filter;
channel_outfilter_fn *output_filter;
void *filter_ctx;
channel_filter_cleanup_fn *filter_cleanup;
/* keep boundaries */
int datagram;
/* non-blocking connect */
/* XXX make this a pointer so the structure can be opaque */
struct channel_connect connect_ctx;
/* multiplexing protocol hook, called for each packet received */
mux_callback_fn *mux_rcb;
void *mux_ctx;
int mux_pause;
int mux_downstream_id;
/* Inactivity timeouts */
/* Last traffic seen for OPEN channels */
time_t lastused;
/* Inactivity timeout deadline in seconds (0 = no timeout) */
u_int inactive_deadline;
};
#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 (64*CHAN_SES_PACKET_DEFAULT)
#define CHAN_TCP_PACKET_DEFAULT (32*1024)
#define CHAN_TCP_WINDOW_DEFAULT (64*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_LOCAL 0x10
/* file descriptor events */
#define SSH_CHAN_IO_RFD 0x01
#define SSH_CHAN_IO_WFD 0x02
#define SSH_CHAN_IO_EFD_R 0x04
#define SSH_CHAN_IO_EFD_W 0x08
#define SSH_CHAN_IO_EFD (SSH_CHAN_IO_EFD_R|SSH_CHAN_IO_EFD_W)
#define SSH_CHAN_IO_SOCK_R 0x10
#define SSH_CHAN_IO_SOCK_W 0x20
#define SSH_CHAN_IO_SOCK (SSH_CHAN_IO_SOCK_R|SSH_CHAN_IO_SOCK_W)
/* Read buffer size */
#define CHAN_RBUF (16*1024)
/* Maximum size for direct reads to buffers */
#define CHANNEL_MAX_READ CHAN_SES_PACKET_DEFAULT
/* Maximum channel input buffer size */
#define CHAN_INPUT_MAX (16*1024*1024)
/* Hard limit on number of channels */
#define CHANNELS_MAX_CHANNELS (16*1024)
/* check whether 'efd' is still in use */
#define CHANNEL_EFD_INPUT_ACTIVE(c) \
(c->extended_usage == CHAN_EXTENDED_READ && \
(c->efd != -1 || \
sshbuf_len(c->extended) > 0))
#define CHANNEL_EFD_OUTPUT_ACTIVE(c) \
(c->extended_usage == CHAN_EXTENDED_WRITE && \
c->efd != -1 && (!(c->flags & (CHAN_EOF_RCVD|CHAN_CLOSE_RCVD)) || \
sshbuf_len(c->extended) > 0))
/* Add channel management structures to SSH transport instance */
void channel_init_channels(struct ssh *ssh);
/* channel management */
Channel *channel_by_id(struct ssh *, int);
Channel *channel_by_remote_id(struct ssh *, u_int);
Channel *channel_lookup(struct ssh *, int);
Channel *channel_new(struct ssh *, char *, int, int, int, int,
u_int, u_int, int, const char *, int);
void channel_set_fds(struct ssh *, int, int, int, int, int,
int, int, u_int);
void channel_free(struct ssh *, Channel *);
void channel_free_all(struct ssh *);
void channel_stop_listening(struct ssh *);
void channel_force_close(struct ssh *, Channel *, int);
void channel_set_xtype(struct ssh *, int, const char *);
void channel_send_open(struct ssh *, int);
void channel_request_start(struct ssh *, int, char *, int);
void channel_register_cleanup(struct ssh *, int,
channel_callback_fn *, int);
void channel_register_open_confirm(struct ssh *, int,
channel_open_fn *, void *);
void channel_register_filter(struct ssh *, int, channel_infilter_fn *,
channel_outfilter_fn *, channel_filter_cleanup_fn *, void *);
void channel_register_status_confirm(struct ssh *, int,
channel_confirm_cb *, channel_confirm_abandon_cb *, void *);
void channel_cancel_cleanup(struct ssh *, int);
int channel_close_fd(struct ssh *, Channel *, int *);
void channel_send_window_changes(struct ssh *);
/* channel inactivity timeouts */
void channel_add_timeout(struct ssh *, const char *, u_int);
void channel_clear_timeouts(struct ssh *);
/* mux proxy support */
int channel_proxy_downstream(struct ssh *, Channel *mc);
int channel_proxy_upstream(Channel *, int, u_int32_t, struct ssh *);
/* protocol handler */
int channel_input_data(int, u_int32_t, struct ssh *);
int channel_input_extended_data(int, u_int32_t, struct ssh *);
int channel_input_ieof(int, u_int32_t, struct ssh *);
int channel_input_oclose(int, u_int32_t, struct ssh *);
int channel_input_open_confirmation(int, u_int32_t, struct ssh *);
int channel_input_open_failure(int, u_int32_t, struct ssh *);
int channel_input_port_open(int, u_int32_t, struct ssh *);
int channel_input_window_adjust(int, u_int32_t, struct ssh *);
int channel_input_status_confirm(int, u_int32_t, struct ssh *);
/* file descriptor handling (read/write) */
struct pollfd;
struct timespec;
void channel_prepare_poll(struct ssh *, struct pollfd **,
u_int *, u_int *, u_int, struct timespec *);
void channel_after_poll(struct ssh *, struct pollfd *, u_int);
void channel_output_poll(struct ssh *);
int channel_not_very_much_buffered_data(struct ssh *);
void channel_close_all(struct ssh *);
int channel_still_open(struct ssh *);
const char *channel_format_extended_usage(const Channel *);
char *channel_open_message(struct ssh *);
int channel_find_open(struct ssh *);
/* tcp forwarding */
struct Forward;
struct ForwardOptions;
void channel_set_af(struct ssh *, int af);
void channel_permit_all(struct ssh *, int);
void channel_add_permission(struct ssh *, int, int, char *, int);
void channel_clear_permission(struct ssh *, int, int);
void channel_disable_admin(struct ssh *, int);
void channel_update_permission(struct ssh *, int, int);
Channel *channel_connect_to_port(struct ssh *, const char *, u_short,
char *, char *, int *, const char **);
Channel *channel_connect_to_path(struct ssh *, const char *, char *, char *);
Channel *channel_connect_stdio_fwd(struct ssh *, const char*,
u_short, int, int, int);
Channel *channel_connect_by_listen_address(struct ssh *, const char *,
u_short, char *, char *);
Channel *channel_connect_by_listen_path(struct ssh *, const char *,
char *, char *);
int channel_request_remote_forwarding(struct ssh *, struct Forward *);
int channel_setup_local_fwd_listener(struct ssh *, struct Forward *,
struct ForwardOptions *);
int channel_request_rforward_cancel(struct ssh *, struct Forward *);
int channel_setup_remote_fwd_listener(struct ssh *, struct Forward *,
int *, struct ForwardOptions *);
int channel_cancel_rport_listener(struct ssh *, struct Forward *);
int channel_cancel_lport_listener(struct ssh *, struct Forward *,
int, struct ForwardOptions *);
int permitopen_port(const char *);
/* x11 forwarding */
void channel_set_x11_refuse_time(struct ssh *, u_int);
int x11_connect_display(struct ssh *);
int x11_create_display_inet(struct ssh *, int, int, int, u_int *, int **);
void x11_request_forwarding_with_spoofing(struct ssh *, int,
const char *, const char *, const char *, int);
/* channel close */
int chan_is_dead(struct ssh *, Channel *, int);
void chan_mark_dead(struct ssh *, Channel *);
/* channel events */
void chan_rcvd_oclose(struct ssh *, Channel *);
void chan_rcvd_eow(struct ssh *, Channel *);
void chan_read_failed(struct ssh *, Channel *);
void chan_ibuf_empty(struct ssh *, Channel *);
void chan_rcvd_ieof(struct ssh *, Channel *);
void chan_write_failed(struct ssh *, Channel *);
void chan_obuf_empty(struct ssh *, Channel *);
#endif
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