/* $OpenBSD: channels.h,v 1.154 2023/12/18 14:47:20 djm Exp $ */ /* * Author: Tatu Ylonen * Copyright (c) 1995 Tatu Ylonen , 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 */ 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_exceeded; 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) */ 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 *, 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); int 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 *); int channel_tty_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*, int, 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 *, time_t); 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