1 /* $OpenBSD: channels.h,v 1.167 2026/06/24 06:53:11 djm 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 85 /* default pattern-lists used to classify channel types as bulk */ 86 #define CHANNEL_BULK_TTY "" 87 #define CHANNEL_BULK_NOTTY "direct-*,forwarded-*,dynamic-*," \ 88 "tun-*,x11-*,session*,stdio-forward" 89 90 struct ssh; 91 struct Channel; 92 typedef struct Channel Channel; 93 94 typedef void channel_open_fn(struct ssh *, int, int, void *); 95 typedef void channel_callback_fn(struct ssh *, int, int, void *); 96 typedef int channel_infilter_fn(struct ssh *, struct Channel *, char *, int); 97 typedef void channel_filter_cleanup_fn(struct ssh *, int, void *); 98 typedef u_char *channel_outfilter_fn(struct ssh *, struct Channel *, 99 u_char **, size_t *); 100 101 /* Channel success/failure callbacks */ 102 typedef void channel_confirm_cb(struct ssh *, int, struct Channel *, void *); 103 typedef void channel_confirm_abandon_cb(struct ssh *, struct Channel *, void *); 104 struct channel_confirm { 105 TAILQ_ENTRY(channel_confirm) entry; 106 channel_confirm_cb *cb; 107 channel_confirm_abandon_cb *abandon_cb; 108 void *ctx; 109 }; 110 TAILQ_HEAD(channel_confirms, channel_confirm); 111 112 /* Context for non-blocking connects */ 113 struct channel_connect { 114 char *host; 115 int port; 116 struct addrinfo *ai, *aitop; 117 }; 118 119 /* Callbacks for mux channels back into client-specific code */ 120 typedef int mux_callback_fn(struct ssh *, struct Channel *); 121 122 /* 123 * NB. channel IDs on the wire and in c->remote_id are uint32, but local 124 * channel IDs (e.g. c->self) only ever use the int32 subset of this range, 125 * because we use local channel ID -1 for housekeeping. Remote channels have 126 * a dedicated "have_remote_id" flag to indicate their validity. 127 */ 128 129 struct Channel { 130 int type; /* channel type/state */ 131 132 int self; /* my own channel identifier */ 133 uint32_t remote_id; /* channel identifier for remote peer */ 134 int have_remote_id; /* non-zero if remote_id is valid */ 135 136 u_int istate; /* input from channel (state of receive half) */ 137 u_int ostate; /* output to channel (state of transmit half) */ 138 int flags; /* close sent/rcvd */ 139 int rfd; /* read fd */ 140 int wfd; /* write fd */ 141 int efd; /* extended fd */ 142 int sock; /* sock fd */ 143 u_int io_want; /* bitmask of SSH_CHAN_IO_* */ 144 u_int io_ready; /* bitmask of SSH_CHAN_IO_* */ 145 int pfds[4]; /* pollfd entries for rfd/wfd/efd/sock */ 146 int ctl_chan; /* control channel (multiplexed connections) */ 147 uint32_t ctl_child_id; /* child session for mux controllers */ 148 int have_ctl_child_id;/* non-zero if ctl_child_id is valid */ 149 int remote_has_tty; /* remote side has a tty */ 150 int isatty; /* rfd is a tty */ 151 #ifdef _AIX 152 int wfd_isatty; /* wfd is a tty */ 153 #endif 154 int client_tty; /* (client) TTY has been requested */ 155 int force_drain; /* force close on iEOF */ 156 time_t notbefore; /* Pause IO until deadline (time_t) */ 157 int delayed; /* post-IO handlers for newly created 158 * channels are delayed until the first call 159 * to a matching pre-IO handler. 160 * this way post-IO handlers are not 161 * accidentally called if a FD gets reused */ 162 int restore_block; /* fd mask to restore blocking status */ 163 int restore_flags[3];/* flags to restore */ 164 struct sshbuf *input; /* data read from socket, to be sent over 165 * encrypted connection */ 166 struct sshbuf *output; /* data received over encrypted connection for 167 * send on socket */ 168 struct sshbuf *extended; 169 170 char *path; 171 /* path for unix domain sockets, or host name for forwards */ 172 int listening_port; /* port being listened for forwards */ 173 char *listening_addr; /* addr being listened for forwards */ 174 int host_port; /* remote port to connect for forwards */ 175 char *remote_name; /* remote hostname */ 176 177 u_int remote_window; 178 u_int remote_maxpacket; 179 u_int local_window; 180 u_int local_window_exceeded; 181 u_int local_window_max; 182 u_int local_consumed; 183 u_int local_maxpacket; 184 int extended_usage; 185 int agent_new; /* For agent listeners, use RFC XXX reqests */ 186 int single_connection; 187 188 char *ctype; /* const type - NB. not freed on channel_free */ 189 char *xctype; /* extended type */ 190 int bulk; /* channel is non-interactive */ 191 192 /* callback */ 193 channel_open_fn *open_confirm; 194 void *open_confirm_ctx; 195 channel_callback_fn *detach_user; 196 int detach_close; 197 struct channel_confirms status_confirms; 198 199 /* filter */ 200 channel_infilter_fn *input_filter; 201 channel_outfilter_fn *output_filter; 202 void *filter_ctx; 203 channel_filter_cleanup_fn *filter_cleanup; 204 205 /* keep boundaries */ 206 int datagram; 207 208 /* non-blocking connect */ 209 /* XXX make this a pointer so the structure can be opaque */ 210 struct channel_connect connect_ctx; 211 212 /* multiplexing protocol hook, called for each packet received */ 213 mux_callback_fn *mux_rcb; 214 void *mux_ctx; 215 int mux_pause; 216 int mux_downstream_id; 217 218 /* Inactivity timeouts */ 219 220 /* Last traffic seen for OPEN channels */ 221 time_t lastused; 222 /* Inactivity timeout deadline in seconds (0 = no timeout) */ 223 int inactive_deadline; 224 }; 225 226 #define CHAN_EXTENDED_IGNORE 0 227 #define CHAN_EXTENDED_READ 1 228 #define CHAN_EXTENDED_WRITE 2 229 230 /* default window/packet sizes for tcp/x11-fwd-channel */ 231 #define CHAN_SES_PACKET_DEFAULT (32*1024) 232 #define CHAN_SES_WINDOW_DEFAULT (64*CHAN_SES_PACKET_DEFAULT) 233 #define CHAN_TCP_PACKET_DEFAULT (32*1024) 234 #define CHAN_TCP_WINDOW_DEFAULT (64*CHAN_TCP_PACKET_DEFAULT) 235 #define CHAN_X11_PACKET_DEFAULT (16*1024) 236 #define CHAN_X11_WINDOW_DEFAULT (4*CHAN_X11_PACKET_DEFAULT) 237 238 /* possible input states */ 239 #define CHAN_INPUT_OPEN 0 240 #define CHAN_INPUT_WAIT_DRAIN 1 241 #define CHAN_INPUT_WAIT_OCLOSE 2 242 #define CHAN_INPUT_CLOSED 3 243 244 /* possible output states */ 245 #define CHAN_OUTPUT_OPEN 0 246 #define CHAN_OUTPUT_WAIT_DRAIN 1 247 #define CHAN_OUTPUT_WAIT_IEOF 2 248 #define CHAN_OUTPUT_CLOSED 3 249 250 #define CHAN_CLOSE_SENT 0x01 251 #define CHAN_CLOSE_RCVD 0x02 252 #define CHAN_EOF_SENT 0x04 253 #define CHAN_EOF_RCVD 0x08 254 #define CHAN_LOCAL 0x10 255 256 /* file descriptor events */ 257 #define SSH_CHAN_IO_RFD 0x01 258 #define SSH_CHAN_IO_WFD 0x02 259 #define SSH_CHAN_IO_EFD_R 0x04 260 #define SSH_CHAN_IO_EFD_W 0x08 261 #define SSH_CHAN_IO_EFD (SSH_CHAN_IO_EFD_R|SSH_CHAN_IO_EFD_W) 262 #define SSH_CHAN_IO_SOCK_R 0x10 263 #define SSH_CHAN_IO_SOCK_W 0x20 264 #define SSH_CHAN_IO_SOCK (SSH_CHAN_IO_SOCK_R|SSH_CHAN_IO_SOCK_W) 265 266 /* Read buffer size */ 267 #define CHAN_RBUF (16*1024) 268 269 /* Maximum size for direct reads to buffers */ 270 #define CHANNEL_MAX_READ CHAN_SES_PACKET_DEFAULT 271 272 /* Maximum channel input buffer size */ 273 #define CHAN_INPUT_MAX (16*1024*1024) 274 275 /* Hard limit on number of channels */ 276 #define CHANNELS_MAX_CHANNELS (16*1024) 277 278 /* check whether 'efd' is still in use */ 279 #define CHANNEL_EFD_INPUT_ACTIVE(c) \ 280 (c->extended_usage == CHAN_EXTENDED_READ && \ 281 (c->efd != -1 || \ 282 sshbuf_len(c->extended) > 0)) 283 #define CHANNEL_EFD_OUTPUT_ACTIVE(c) \ 284 (c->extended_usage == CHAN_EXTENDED_WRITE && \ 285 c->efd != -1 && (!(c->flags & (CHAN_EOF_RCVD|CHAN_CLOSE_RCVD)) || \ 286 sshbuf_len(c->extended) > 0)) 287 288 /* Add/remove channel management structures to/from SSH transport instance */ 289 void channel_init_channels(struct ssh *ssh); 290 void channel_free_channels(struct ssh *ssh); 291 292 /* channel management */ 293 294 Channel *channel_by_id(struct ssh *, int); 295 Channel *channel_by_remote_id(struct ssh *, u_int); 296 Channel *channel_lookup(struct ssh *, int); 297 Channel *channel_new(struct ssh *, char *, int, int, int, int, 298 u_int, u_int, int, const char *, int); 299 void channel_set_fds(struct ssh *, int, int, int, int, int, 300 int, int, u_int); 301 void channel_set_tty(struct ssh *, Channel *); 302 void channel_free(struct ssh *, Channel *); 303 void channel_free_all(struct ssh *); 304 void channel_stop_listening(struct ssh *); 305 void channel_force_close(struct ssh *, Channel *, int); 306 void channel_set_xtype(struct ssh *, int, const char *); 307 308 void channel_send_open(struct ssh *, int); 309 void channel_request_start(struct ssh *, int, const char *, int); 310 void channel_register_cleanup(struct ssh *, int, 311 channel_callback_fn *, int); 312 void channel_register_open_confirm(struct ssh *, int, 313 channel_open_fn *, void *); 314 void channel_register_filter(struct ssh *, int, channel_infilter_fn *, 315 channel_outfilter_fn *, channel_filter_cleanup_fn *, void *); 316 void channel_register_status_confirm(struct ssh *, int, 317 channel_confirm_cb *, channel_confirm_abandon_cb *, void *); 318 void channel_cancel_cleanup(struct ssh *, int); 319 int channel_close_fd(struct ssh *, Channel *, int *); 320 void channel_send_window_changes(struct ssh *); 321 int channel_has_bulk(struct ssh *); 322 323 /* channel inactivity timeouts */ 324 void channel_add_timeout(struct ssh *, const char *, int); 325 void channel_clear_timeouts(struct ssh *); 326 327 /* mux proxy support */ 328 329 int channel_proxy_downstream(struct ssh *, Channel *mc); 330 int channel_proxy_upstream(Channel *, int, uint32_t, struct ssh *); 331 332 /* protocol handler */ 333 334 int channel_input_data(int, uint32_t, struct ssh *); 335 int channel_input_extended_data(int, uint32_t, struct ssh *); 336 int channel_input_ieof(int, uint32_t, struct ssh *); 337 int channel_input_oclose(int, uint32_t, struct ssh *); 338 int channel_input_open_confirmation(int, uint32_t, struct ssh *); 339 int channel_input_open_failure(int, uint32_t, struct ssh *); 340 int channel_input_window_adjust(int, uint32_t, struct ssh *); 341 int channel_input_status_confirm(int, uint32_t, struct ssh *); 342 343 /* file descriptor handling (read/write) */ 344 struct pollfd; 345 struct timespec; 346 347 void channel_prepare_poll(struct ssh *, struct pollfd **, 348 u_int *, u_int *, u_int, struct timespec *); 349 void channel_after_poll(struct ssh *, struct pollfd *, u_int); 350 int channel_output_poll(struct ssh *); 351 352 int channel_not_very_much_buffered_data(struct ssh *); 353 void channel_close_all(struct ssh *); 354 int channel_still_open(struct ssh *); 355 int channel_tty_open(struct ssh *); 356 const char *channel_format_extended_usage(const Channel *); 357 char *channel_open_message(struct ssh *); 358 void channel_report_open(struct ssh *, int); 359 int channel_find_open(struct ssh *); 360 361 /* tcp forwarding */ 362 struct Forward; 363 struct ForwardOptions; 364 void channel_set_af(struct ssh *, int af); 365 void channel_permit_all(struct ssh *, int); 366 void channel_add_permission(struct ssh *, int, int, char *, int); 367 void channel_clear_permission(struct ssh *, int, int); 368 void channel_disable_admin(struct ssh *, int); 369 void channel_update_permission(struct ssh *, int, int); 370 Channel *channel_connect_to_port(struct ssh *, const char *, u_short, 371 char *, char *, int *, const char **); 372 Channel *channel_connect_to_path(struct ssh *, const char *, char *, char *); 373 Channel *channel_connect_stdio_fwd(struct ssh *, const char*, 374 int, int, int, int); 375 Channel *channel_connect_by_listen_address(struct ssh *, const char *, 376 u_short, char *, char *); 377 Channel *channel_connect_by_listen_path(struct ssh *, const char *, 378 char *, char *); 379 int channel_request_remote_forwarding(struct ssh *, struct Forward *); 380 int channel_setup_local_fwd_listener(struct ssh *, struct Forward *, 381 struct ForwardOptions *); 382 int channel_request_rforward_cancel(struct ssh *, struct Forward *); 383 int channel_setup_remote_fwd_listener(struct ssh *, struct Forward *, 384 int *, struct ForwardOptions *); 385 int channel_cancel_rport_listener(struct ssh *, struct Forward *); 386 int channel_cancel_lport_listener(struct ssh *, struct Forward *, 387 int, struct ForwardOptions *); 388 int permitopen_port(const char *); 389 390 /* x11 forwarding */ 391 392 void channel_set_x11_refuse_time(struct ssh *, time_t); 393 int x11_connect_display(struct ssh *); 394 int x11_create_display_inet(struct ssh *, int, int, int, u_int *, int **); 395 void x11_request_forwarding_with_spoofing(struct ssh *, int, 396 const char *, const char *, const char *, int); 397 int x11_channel_used_recently(struct ssh *ssh); 398 399 /* channel close */ 400 401 int chan_is_dead(struct ssh *, Channel *, int); 402 void chan_mark_dead(struct ssh *, Channel *); 403 404 /* agent forwarding */ 405 void client_channel_reqest_agent_forwarding(struct ssh *, int); 406 407 /* channel events */ 408 409 void chan_rcvd_oclose(struct ssh *, Channel *); 410 void chan_rcvd_eow(struct ssh *, Channel *); 411 void chan_read_failed(struct ssh *, Channel *); 412 void chan_ibuf_empty(struct ssh *, Channel *); 413 void chan_rcvd_ieof(struct ssh *, Channel *); 414 void chan_write_failed(struct ssh *, Channel *); 415 void chan_obuf_empty(struct ssh *, Channel *); 416 417 #endif 418