1/* $OpenBSD: channels.h,v 1.156 2024/05/23 23:47:16 jsg Exp $ */ 2 3/* 4 * Author: Tatu Ylonen <ylo@cs.hut.fi> 5 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 6 * All rights reserved 7 * 8 * As far as I am concerned, the code I have written for this software 9 * can be used freely for any purpose. Any derived versions of this 10 * software must be clearly marked as such, and if the derived work is 11 * incompatible with the protocol description in the RFC file, it must be 12 * called by a name other than "ssh" or "Secure Shell". 13 */ 14/* 15 * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved. 16 * 17 * Redistribution and use in source and binary forms, with or without 18 * modification, are permitted provided that the following conditions 19 * are met: 20 * 1. Redistributions of source code must retain the above copyright 21 * notice, this list of conditions and the following disclaimer. 22 * 2. Redistributions in binary form must reproduce the above copyright 23 * notice, this list of conditions and the following disclaimer in the 24 * documentation and/or other materials provided with the distribution. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 36 */ 37 38#ifndef CHANNEL_H 39#define CHANNEL_H 40 41/* Definitions for channel types. */ 42#define SSH_CHANNEL_X11_LISTENER 1 /* Listening for inet X11 conn. */ 43#define SSH_CHANNEL_PORT_LISTENER 2 /* Listening on a port. */ 44#define SSH_CHANNEL_OPENING 3 /* waiting for confirmation */ 45#define SSH_CHANNEL_OPEN 4 /* normal open two-way channel */ 46#define SSH_CHANNEL_CLOSED 5 /* waiting for close confirmation */ 47#define SSH_CHANNEL_AUTH_SOCKET 6 /* authentication socket */ 48#define SSH_CHANNEL_X11_OPEN 7 /* reading first X11 packet */ 49#define SSH_CHANNEL_LARVAL 10 /* larval session */ 50#define SSH_CHANNEL_RPORT_LISTENER 11 /* Listening to a R-style port */ 51#define SSH_CHANNEL_CONNECTING 12 52#define SSH_CHANNEL_DYNAMIC 13 53#define SSH_CHANNEL_ZOMBIE 14 /* Almost dead. */ 54#define SSH_CHANNEL_MUX_LISTENER 15 /* Listener for mux conn. */ 55#define SSH_CHANNEL_MUX_CLIENT 16 /* Conn. to mux client */ 56#define SSH_CHANNEL_ABANDONED 17 /* Abandoned session, eg mux */ 57#define SSH_CHANNEL_UNIX_LISTENER 18 /* Listening on a domain socket. */ 58#define SSH_CHANNEL_RUNIX_LISTENER 19 /* Listening to a R-style domain socket. */ 59#define SSH_CHANNEL_MUX_PROXY 20 /* proxy channel for mux-client */ 60#define SSH_CHANNEL_RDYNAMIC_OPEN 21 /* reverse SOCKS, parsing request */ 61#define SSH_CHANNEL_RDYNAMIC_FINISH 22 /* reverse SOCKS, finishing connect */ 62#define SSH_CHANNEL_MAX_TYPE 23 63 64#define CHANNEL_CANCEL_PORT_STATIC -1 65 66/* nonblocking flags for channel_new */ 67#define CHANNEL_NONBLOCK_LEAVE 0 /* don't modify non-blocking state */ 68#define CHANNEL_NONBLOCK_SET 1 /* set non-blocking state */ 69#define CHANNEL_NONBLOCK_STDIO 2 /* set non-blocking and restore on close */ 70 71/* c->restore_block mask flags */ 72#define CHANNEL_RESTORE_RFD 0x01 73#define CHANNEL_RESTORE_WFD 0x02 74#define CHANNEL_RESTORE_EFD 0x04 75 76/* TCP forwarding */ 77#define FORWARD_DENY 0 78#define FORWARD_REMOTE (1) 79#define FORWARD_LOCAL (1<<1) 80#define FORWARD_ALLOW (FORWARD_REMOTE|FORWARD_LOCAL) 81 82#define FORWARD_ADM 0x100 83#define FORWARD_USER 0x101 84 85struct ssh; 86struct Channel; 87typedef struct Channel Channel; 88 89typedef void channel_open_fn(struct ssh *, int, int, void *); 90typedef void channel_callback_fn(struct ssh *, int, int, void *); 91typedef int channel_infilter_fn(struct ssh *, struct Channel *, char *, int); 92typedef void channel_filter_cleanup_fn(struct ssh *, int, void *); 93typedef u_char *channel_outfilter_fn(struct ssh *, struct Channel *, 94 u_char **, size_t *); 95 96/* Channel success/failure callbacks */ 97typedef void channel_confirm_cb(struct ssh *, int, struct Channel *, void *); 98typedef void channel_confirm_abandon_cb(struct ssh *, struct Channel *, void *); 99struct channel_confirm { 100 TAILQ_ENTRY(channel_confirm) entry; 101 channel_confirm_cb *cb; 102 channel_confirm_abandon_cb *abandon_cb; 103 void *ctx; 104}; 105TAILQ_HEAD(channel_confirms, channel_confirm); 106 107/* Context for non-blocking connects */ 108struct channel_connect { 109 char *host; 110 int port; 111 struct addrinfo *ai, *aitop; 112}; 113 114/* Callbacks for mux channels back into client-specific code */ 115typedef int mux_callback_fn(struct ssh *, struct Channel *); 116 117/* 118 * NB. channel IDs on the wire and in c->remote_id are uint32, but local 119 * channel IDs (e.g. c->self) only ever use the int32 subset of this range, 120 * because we use local channel ID -1 for housekeeping. Remote channels have 121 * a dedicated "have_remote_id" flag to indicate their validity. 122 */ 123 124struct Channel { 125 int type; /* channel type/state */ 126 127 int self; /* my own channel identifier */ 128 uint32_t remote_id; /* channel identifier for remote peer */ 129 int have_remote_id; /* non-zero if remote_id is valid */ 130 131 u_int istate; /* input from channel (state of receive half) */ 132 u_int ostate; /* output to channel (state of transmit half) */ 133 int flags; /* close sent/rcvd */ 134 int rfd; /* read fd */ 135 int wfd; /* write fd */ 136 int efd; /* extended fd */ 137 int sock; /* sock fd */ 138 u_int io_want; /* bitmask of SSH_CHAN_IO_* */ 139 u_int io_ready; /* bitmask of SSH_CHAN_IO_* */ 140 int pfds[4]; /* pollfd entries for rfd/wfd/efd/sock */ 141 int ctl_chan; /* control channel (multiplexed connections) */ 142 int isatty; /* rfd is a tty */ 143 int client_tty; /* (client) TTY has been requested */ 144 int force_drain; /* force close on iEOF */ 145 time_t notbefore; /* Pause IO until deadline (time_t) */ 146 int delayed; /* post-IO handlers for newly created 147 * channels are delayed until the first call 148 * to a matching pre-IO handler. 149 * this way post-IO handlers are not 150 * accidentally called if a FD gets reused */ 151 int restore_block; /* fd mask to restore blocking status */ 152 int restore_flags[3];/* flags to restore */ 153 struct sshbuf *input; /* data read from socket, to be sent over 154 * encrypted connection */ 155 struct sshbuf *output; /* data received over encrypted connection for 156 * send on socket */ 157 struct sshbuf *extended; 158 159 char *path; 160 /* path for unix domain sockets, or host name for forwards */ 161 int listening_port; /* port being listened for forwards */ 162 char *listening_addr; /* addr being listened for forwards */ 163 int host_port; /* remote port to connect for forwards */ 164 char *remote_name; /* remote hostname */ 165 166 u_int remote_window; 167 u_int remote_maxpacket; 168 u_int local_window; 169 u_int local_window_exceeded; 170 u_int local_window_max; 171 u_int local_consumed; 172 u_int local_maxpacket; 173 int extended_usage; 174 int single_connection; 175 176 char *ctype; /* const type - NB. not freed on channel_free */ 177 char *xctype; /* extended type */ 178 179 /* callback */ 180 channel_open_fn *open_confirm; 181 void *open_confirm_ctx; 182 channel_callback_fn *detach_user; 183 int detach_close; 184 struct channel_confirms status_confirms; 185 186 /* filter */ 187 channel_infilter_fn *input_filter; 188 channel_outfilter_fn *output_filter; 189 void *filter_ctx; 190 channel_filter_cleanup_fn *filter_cleanup; 191 192 /* keep boundaries */ 193 int datagram; 194 195 /* non-blocking connect */ 196 /* XXX make this a pointer so the structure can be opaque */ 197 struct channel_connect connect_ctx; 198 199 /* multiplexing protocol hook, called for each packet received */ 200 mux_callback_fn *mux_rcb; 201 void *mux_ctx; 202 int mux_pause; 203 int mux_downstream_id; 204 205 /* Inactivity timeouts */ 206 207 /* Last traffic seen for OPEN channels */ 208 time_t lastused; 209 /* Inactivity timeout deadline in seconds (0 = no timeout) */ 210 int inactive_deadline; 211}; 212 213#define CHAN_EXTENDED_IGNORE 0 214#define CHAN_EXTENDED_READ 1 215#define CHAN_EXTENDED_WRITE 2 216 217/* default window/packet sizes for tcp/x11-fwd-channel */ 218#define CHAN_SES_PACKET_DEFAULT (32*1024) 219#define CHAN_SES_WINDOW_DEFAULT (64*CHAN_SES_PACKET_DEFAULT) 220#define CHAN_TCP_PACKET_DEFAULT (32*1024) 221#define CHAN_TCP_WINDOW_DEFAULT (64*CHAN_TCP_PACKET_DEFAULT) 222#define CHAN_X11_PACKET_DEFAULT (16*1024) 223#define CHAN_X11_WINDOW_DEFAULT (4*CHAN_X11_PACKET_DEFAULT) 224 225/* possible input states */ 226#define CHAN_INPUT_OPEN 0 227#define CHAN_INPUT_WAIT_DRAIN 1 228#define CHAN_INPUT_WAIT_OCLOSE 2 229#define CHAN_INPUT_CLOSED 3 230 231/* possible output states */ 232#define CHAN_OUTPUT_OPEN 0 233#define CHAN_OUTPUT_WAIT_DRAIN 1 234#define CHAN_OUTPUT_WAIT_IEOF 2 235#define CHAN_OUTPUT_CLOSED 3 236 237#define CHAN_CLOSE_SENT 0x01 238#define CHAN_CLOSE_RCVD 0x02 239#define CHAN_EOF_SENT 0x04 240#define CHAN_EOF_RCVD 0x08 241#define CHAN_LOCAL 0x10 242 243/* file descriptor events */ 244#define SSH_CHAN_IO_RFD 0x01 245#define SSH_CHAN_IO_WFD 0x02 246#define SSH_CHAN_IO_EFD_R 0x04 247#define SSH_CHAN_IO_EFD_W 0x08 248#define SSH_CHAN_IO_EFD (SSH_CHAN_IO_EFD_R|SSH_CHAN_IO_EFD_W) 249#define SSH_CHAN_IO_SOCK_R 0x10 250#define SSH_CHAN_IO_SOCK_W 0x20 251#define SSH_CHAN_IO_SOCK (SSH_CHAN_IO_SOCK_R|SSH_CHAN_IO_SOCK_W) 252 253/* Read buffer size */ 254#define CHAN_RBUF (16*1024) 255 256/* Maximum size for direct reads to buffers */ 257#define CHANNEL_MAX_READ CHAN_SES_PACKET_DEFAULT 258 259/* Maximum channel input buffer size */ 260#define CHAN_INPUT_MAX (16*1024*1024) 261 262/* Hard limit on number of channels */ 263#define CHANNELS_MAX_CHANNELS (16*1024) 264 265/* check whether 'efd' is still in use */ 266#define CHANNEL_EFD_INPUT_ACTIVE(c) \ 267 (c->extended_usage == CHAN_EXTENDED_READ && \ 268 (c->efd != -1 || \ 269 sshbuf_len(c->extended) > 0)) 270#define CHANNEL_EFD_OUTPUT_ACTIVE(c) \ 271 (c->extended_usage == CHAN_EXTENDED_WRITE && \ 272 c->efd != -1 && (!(c->flags & (CHAN_EOF_RCVD|CHAN_CLOSE_RCVD)) || \ 273 sshbuf_len(c->extended) > 0)) 274 275/* Add channel management structures to SSH transport instance */ 276void channel_init_channels(struct ssh *ssh); 277 278/* channel management */ 279 280Channel *channel_by_id(struct ssh *, int); 281Channel *channel_by_remote_id(struct ssh *, u_int); 282Channel *channel_lookup(struct ssh *, int); 283Channel *channel_new(struct ssh *, char *, int, int, int, int, 284 u_int, u_int, int, const char *, int); 285void channel_set_fds(struct ssh *, int, int, int, int, int, 286 int, int, u_int); 287void channel_free(struct ssh *, Channel *); 288void channel_free_all(struct ssh *); 289void channel_stop_listening(struct ssh *); 290void channel_force_close(struct ssh *, Channel *, int); 291void channel_set_xtype(struct ssh *, int, const char *); 292 293void channel_send_open(struct ssh *, int); 294void channel_request_start(struct ssh *, int, char *, int); 295void channel_register_cleanup(struct ssh *, int, 296 channel_callback_fn *, int); 297void channel_register_open_confirm(struct ssh *, int, 298 channel_open_fn *, void *); 299void channel_register_filter(struct ssh *, int, channel_infilter_fn *, 300 channel_outfilter_fn *, channel_filter_cleanup_fn *, void *); 301void channel_register_status_confirm(struct ssh *, int, 302 channel_confirm_cb *, channel_confirm_abandon_cb *, void *); 303void channel_cancel_cleanup(struct ssh *, int); 304int channel_close_fd(struct ssh *, Channel *, int *); 305void channel_send_window_changes(struct ssh *); 306 307/* channel inactivity timeouts */ 308void channel_add_timeout(struct ssh *, const char *, int); 309void channel_clear_timeouts(struct ssh *); 310 311/* mux proxy support */ 312 313int channel_proxy_downstream(struct ssh *, Channel *mc); 314int channel_proxy_upstream(Channel *, int, u_int32_t, struct ssh *); 315 316/* protocol handler */ 317 318int channel_input_data(int, u_int32_t, struct ssh *); 319int channel_input_extended_data(int, u_int32_t, struct ssh *); 320int channel_input_ieof(int, u_int32_t, struct ssh *); 321int channel_input_oclose(int, u_int32_t, struct ssh *); 322int channel_input_open_confirmation(int, u_int32_t, struct ssh *); 323int channel_input_open_failure(int, u_int32_t, struct ssh *); 324int channel_input_window_adjust(int, u_int32_t, struct ssh *); 325int channel_input_status_confirm(int, u_int32_t, struct ssh *); 326 327/* file descriptor handling (read/write) */ 328struct pollfd; 329struct timespec; 330 331void channel_prepare_poll(struct ssh *, struct pollfd **, 332 u_int *, u_int *, u_int, struct timespec *); 333void channel_after_poll(struct ssh *, struct pollfd *, u_int); 334int channel_output_poll(struct ssh *); 335 336int channel_not_very_much_buffered_data(struct ssh *); 337void channel_close_all(struct ssh *); 338int channel_still_open(struct ssh *); 339int channel_tty_open(struct ssh *); 340const char *channel_format_extended_usage(const Channel *); 341char *channel_open_message(struct ssh *); 342int channel_find_open(struct ssh *); 343 344/* tcp forwarding */ 345struct Forward; 346struct ForwardOptions; 347void channel_set_af(struct ssh *, int af); 348void channel_permit_all(struct ssh *, int); 349void channel_add_permission(struct ssh *, int, int, char *, int); 350void channel_clear_permission(struct ssh *, int, int); 351void channel_disable_admin(struct ssh *, int); 352void channel_update_permission(struct ssh *, int, int); 353Channel *channel_connect_to_port(struct ssh *, const char *, u_short, 354 char *, char *, int *, const char **); 355Channel *channel_connect_to_path(struct ssh *, const char *, char *, char *); 356Channel *channel_connect_stdio_fwd(struct ssh *, const char*, 357 int, int, int, int); 358Channel *channel_connect_by_listen_address(struct ssh *, const char *, 359 u_short, char *, char *); 360Channel *channel_connect_by_listen_path(struct ssh *, const char *, 361 char *, char *); 362int channel_request_remote_forwarding(struct ssh *, struct Forward *); 363int channel_setup_local_fwd_listener(struct ssh *, struct Forward *, 364 struct ForwardOptions *); 365int channel_request_rforward_cancel(struct ssh *, struct Forward *); 366int channel_setup_remote_fwd_listener(struct ssh *, struct Forward *, 367 int *, struct ForwardOptions *); 368int channel_cancel_rport_listener(struct ssh *, struct Forward *); 369int channel_cancel_lport_listener(struct ssh *, struct Forward *, 370 int, struct ForwardOptions *); 371int permitopen_port(const char *); 372 373/* x11 forwarding */ 374 375void channel_set_x11_refuse_time(struct ssh *, time_t); 376int x11_connect_display(struct ssh *); 377int x11_create_display_inet(struct ssh *, int, int, int, u_int *, int **); 378void x11_request_forwarding_with_spoofing(struct ssh *, int, 379 const char *, const char *, const char *, int); 380 381/* channel close */ 382 383int chan_is_dead(struct ssh *, Channel *, int); 384void chan_mark_dead(struct ssh *, Channel *); 385 386/* channel events */ 387 388void chan_rcvd_oclose(struct ssh *, Channel *); 389void chan_rcvd_eow(struct ssh *, Channel *); 390void chan_read_failed(struct ssh *, Channel *); 391void chan_ibuf_empty(struct ssh *, Channel *); 392void chan_rcvd_ieof(struct ssh *, Channel *); 393void chan_write_failed(struct ssh *, Channel *); 394void chan_obuf_empty(struct ssh *, Channel *); 395 396#endif 397