1 /* $NetBSD: channels.h,v 1.29 2025/04/09 15:49:32 christos Exp $ */ 2 /* $OpenBSD: channels.h,v 1.158 2024/10/13 22:20:06 djm Exp $ */ 3 4 /* 5 * Author: Tatu Ylonen <ylo@cs.hut.fi> 6 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland 7 * All rights reserved 8 * 9 * As far as I am concerned, the code I have written for this software 10 * can be used freely for any purpose. Any derived versions of this 11 * software must be clearly marked as such, and if the derived work is 12 * incompatible with the protocol description in the RFC file, it must be 13 * called by a name other than "ssh" or "Secure Shell". 14 */ 15 /* 16 * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved. 17 * 18 * Redistribution and use in source and binary forms, with or without 19 * modification, are permitted provided that the following conditions 20 * are met: 21 * 1. Redistributions of source code must retain the above copyright 22 * notice, this list of conditions and the following disclaimer. 23 * 2. Redistributions in binary form must reproduce the above copyright 24 * notice, this list of conditions and the following disclaimer in the 25 * documentation and/or other materials provided with the distribution. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 28 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 29 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 30 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 31 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 32 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 33 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 34 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 35 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 36 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #ifndef CHANNEL_H 40 #define CHANNEL_H 41 42 /* Definitions for channel types. */ 43 #define SSH_CHANNEL_X11_LISTENER 1 /* Listening for inet X11 conn. */ 44 #define SSH_CHANNEL_PORT_LISTENER 2 /* Listening on a port. */ 45 #define SSH_CHANNEL_OPENING 3 /* waiting for confirmation */ 46 #define SSH_CHANNEL_OPEN 4 /* normal open two-way channel */ 47 #define SSH_CHANNEL_CLOSED 5 /* waiting for close confirmation */ 48 #define SSH_CHANNEL_AUTH_SOCKET 6 /* authentication socket */ 49 #define SSH_CHANNEL_X11_OPEN 7 /* reading first X11 packet */ 50 #define SSH_CHANNEL_LARVAL 10 /* larval session */ 51 #define SSH_CHANNEL_RPORT_LISTENER 11 /* Listening to a R-style port */ 52 #define SSH_CHANNEL_CONNECTING 12 53 #define SSH_CHANNEL_DYNAMIC 13 54 #define SSH_CHANNEL_ZOMBIE 14 /* Almost dead. */ 55 #define SSH_CHANNEL_MUX_LISTENER 15 /* Listener for mux conn. */ 56 #define SSH_CHANNEL_MUX_CLIENT 16 /* Conn. to mux client */ 57 #define SSH_CHANNEL_ABANDONED 17 /* Abandoned session, eg mux */ 58 #define SSH_CHANNEL_UNIX_LISTENER 18 /* Listening on a domain socket. */ 59 #define SSH_CHANNEL_RUNIX_LISTENER 19 /* Listening to a R-style domain socket. */ 60 #define SSH_CHANNEL_MUX_PROXY 20 /* proxy channel for mux-client */ 61 #define SSH_CHANNEL_RDYNAMIC_OPEN 21 /* reverse SOCKS, parsing request */ 62 #define SSH_CHANNEL_RDYNAMIC_FINISH 22 /* reverse SOCKS, finishing connect */ 63 #define SSH_CHANNEL_MAX_TYPE 23 64 65 #define CHANNEL_CANCEL_PORT_STATIC -1 66 67 /* nonblocking flags for channel_new */ 68 #define CHANNEL_NONBLOCK_LEAVE 0 /* don't modify non-blocking state */ 69 #define CHANNEL_NONBLOCK_SET 1 /* set non-blocking state */ 70 #define CHANNEL_NONBLOCK_STDIO 2 /* set non-blocking and restore on close */ 71 72 /* c->restore_block mask flags */ 73 #define CHANNEL_RESTORE_RFD 0x01 74 #define CHANNEL_RESTORE_WFD 0x02 75 #define CHANNEL_RESTORE_EFD 0x04 76 77 /* TCP forwarding */ 78 #define FORWARD_DENY 0 79 #define FORWARD_REMOTE (1) 80 #define FORWARD_LOCAL (1<<1) 81 #define FORWARD_ALLOW (FORWARD_REMOTE|FORWARD_LOCAL) 82 83 #define FORWARD_ADM 0x100 84 #define FORWARD_USER 0x101 85 86 struct ssh; 87 struct Channel; 88 typedef struct Channel Channel; 89 90 typedef void channel_open_fn(struct ssh *, int, int, void *); 91 typedef void channel_callback_fn(struct ssh *, int, int, void *); 92 typedef int channel_infilter_fn(struct ssh *, struct Channel *, const char *, 93 int); 94 typedef void channel_filter_cleanup_fn(struct ssh *, int, void *); 95 typedef u_char *channel_outfilter_fn(struct ssh *, struct Channel *, 96 u_char **, size_t *); 97 98 /* Channel success/failure callbacks */ 99 typedef void channel_confirm_cb(struct ssh *, int, struct Channel *, void *); 100 typedef void channel_confirm_abandon_cb(struct ssh *, struct Channel *, void *); 101 struct channel_confirm { 102 TAILQ_ENTRY(channel_confirm) entry; 103 channel_confirm_cb *cb; 104 channel_confirm_abandon_cb *abandon_cb; 105 void *ctx; 106 }; 107 TAILQ_HEAD(channel_confirms, channel_confirm); 108 109 /* Context for non-blocking connects */ 110 struct channel_connect { 111 char *host; 112 int port; 113 struct addrinfo *ai, *aitop; 114 }; 115 116 /* Callbacks for mux channels back into client-specific code */ 117 typedef int mux_callback_fn(struct ssh *, struct Channel *); 118 119 /* 120 * NB. channel IDs on the wire and in c->remote_id are uint32, but local 121 * channel IDs (e.g. c->self) only ever use the int32 subset of this range, 122 * because we use local channel ID -1 for housekeeping. Remote channels have 123 * a dedicated "have_remote_id" flag to indicate their validity. 124 */ 125 126 struct Channel { 127 int type; /* channel type/state */ 128 129 int self; /* my own channel identifier */ 130 uint32_t remote_id; /* channel identifier for remote peer */ 131 int have_remote_id; /* non-zero if remote_id is valid */ 132 133 u_int istate; /* input from channel (state of receive half) */ 134 u_int ostate; /* output to channel (state of transmit half) */ 135 int flags; /* close sent/rcvd */ 136 int rfd; /* read fd */ 137 int wfd; /* write fd */ 138 int efd; /* extended fd */ 139 int sock; /* sock fd */ 140 u_int io_want; /* bitmask of SSH_CHAN_IO_* */ 141 u_int io_ready; /* bitmask of SSH_CHAN_IO_* */ 142 int pfds[4]; /* pollfd entries for rfd/wfd/efd/sock */ 143 int ctl_chan; /* control channel (multiplexed connections) */ 144 uint32_t ctl_child_id; /* child session for mux controllers */ 145 int have_ctl_child_id;/* non-zero if ctl_child_id is valid */ 146 int isatty; /* rfd is a tty */ 147 int client_tty; /* (client) TTY has been requested */ 148 int force_drain; /* force close on iEOF */ 149 time_t notbefore; /* Pause IO until deadline (time_t) */ 150 int delayed; /* post-IO handlers for newly created 151 * channels are delayed until the first call 152 * to a matching pre-IO handler. 153 * this way post-IO handlers are not 154 * accidentally called if a FD gets reused */ 155 int restore_block; /* fd mask to restore blocking status */ 156 int restore_flags[3];/* flags to restore */ 157 struct sshbuf *input; /* data read from socket, to be sent over 158 * encrypted connection */ 159 struct sshbuf *output; /* data received over encrypted connection for 160 * send on socket */ 161 struct sshbuf *extended; 162 163 char *path; 164 /* path for unix domain sockets, or host name for forwards */ 165 int listening_port; /* port being listened for forwards */ 166 char *listening_addr; /* addr being listened for forwards */ 167 int host_port; /* remote port to connect for forwards */ 168 char *remote_name; /* remote hostname */ 169 170 u_int remote_window; 171 u_int remote_maxpacket; 172 u_int local_window; 173 u_int local_window_exceeded; 174 u_int local_window_max; 175 u_int local_consumed; 176 u_int local_maxpacket; 177 int dynamic_window; 178 int extended_usage; 179 int single_connection; 180 u_int tcpwinsz; 181 182 char *ctype; /* const type - NB. not freed on channel_free */ 183 char *xctype; /* extended type */ 184 185 /* callback */ 186 channel_open_fn *open_confirm; 187 void *open_confirm_ctx; 188 channel_callback_fn *detach_user; 189 int detach_close; 190 struct channel_confirms status_confirms; 191 192 /* filter */ 193 channel_infilter_fn *input_filter; 194 channel_outfilter_fn *output_filter; 195 void *filter_ctx; 196 channel_filter_cleanup_fn *filter_cleanup; 197 198 /* keep boundaries */ 199 int datagram; 200 201 /* non-blocking connect */ 202 /* XXX make this a pointer so the structure can be opaque */ 203 struct channel_connect connect_ctx; 204 205 /* multiplexing protocol hook, called for each packet received */ 206 mux_callback_fn *mux_rcb; 207 void *mux_ctx; 208 int mux_pause; 209 int mux_downstream_id; 210 211 /* Inactivity timeouts */ 212 213 /* Last traffic seen for OPEN channels */ 214 time_t lastused; 215 /* Inactivity timeout deadline in seconds (0 = no timeout) */ 216 int inactive_deadline; 217 }; 218 219 #define CHAN_EXTENDED_IGNORE 0 220 #define CHAN_EXTENDED_READ 1 221 #define CHAN_EXTENDED_WRITE 2 222 223 /* default window/packet sizes for tcp/x11-fwd-channel */ 224 #define CHAN_SES_PACKET_DEFAULT (32*1024) 225 #define CHAN_SES_WINDOW_DEFAULT (4*CHAN_SES_PACKET_DEFAULT) 226 227 #define CHAN_TCP_PACKET_DEFAULT (32*1024) 228 #define CHAN_TCP_WINDOW_DEFAULT (4*CHAN_TCP_PACKET_DEFAULT) 229 230 #define CHAN_X11_PACKET_DEFAULT (16*1024) 231 #define CHAN_X11_WINDOW_DEFAULT (4*CHAN_X11_PACKET_DEFAULT) 232 233 /* possible input states */ 234 #define CHAN_INPUT_OPEN 0 235 #define CHAN_INPUT_WAIT_DRAIN 1 236 #define CHAN_INPUT_WAIT_OCLOSE 2 237 #define CHAN_INPUT_CLOSED 3 238 239 /* possible output states */ 240 #define CHAN_OUTPUT_OPEN 0 241 #define CHAN_OUTPUT_WAIT_DRAIN 1 242 #define CHAN_OUTPUT_WAIT_IEOF 2 243 #define CHAN_OUTPUT_CLOSED 3 244 245 #define CHAN_CLOSE_SENT 0x01 246 #define CHAN_CLOSE_RCVD 0x02 247 #define CHAN_EOF_SENT 0x04 248 #define CHAN_EOF_RCVD 0x08 249 #define CHAN_LOCAL 0x10 250 251 /* file descriptor events */ 252 #define SSH_CHAN_IO_RFD 0x01 253 #define SSH_CHAN_IO_WFD 0x02 254 #define SSH_CHAN_IO_EFD_R 0x04 255 #define SSH_CHAN_IO_EFD_W 0x08 256 #define SSH_CHAN_IO_EFD (SSH_CHAN_IO_EFD_R|SSH_CHAN_IO_EFD_W) 257 #define SSH_CHAN_IO_SOCK_R 0x10 258 #define SSH_CHAN_IO_SOCK_W 0x20 259 #define SSH_CHAN_IO_SOCK (SSH_CHAN_IO_SOCK_R|SSH_CHAN_IO_SOCK_W) 260 261 /* Read buffer size */ 262 #define CHAN_RBUF (16*1024) 263 264 /* Maximum size for direct reads to buffers */ 265 #define CHANNEL_MAX_READ CHAN_SES_PACKET_DEFAULT 266 267 /* Maximum channel input buffer size */ 268 #define CHAN_INPUT_MAX (16*1024*1024) 269 270 /* Hard limit on number of channels */ 271 #define CHANNELS_MAX_CHANNELS (16*1024) 272 273 /* check whether 'efd' is still in use */ 274 #define CHANNEL_EFD_INPUT_ACTIVE(c) \ 275 (c->extended_usage == CHAN_EXTENDED_READ && \ 276 (c->efd != -1 || \ 277 sshbuf_len(c->extended) > 0)) 278 #define CHANNEL_EFD_OUTPUT_ACTIVE(c) \ 279 (c->extended_usage == CHAN_EXTENDED_WRITE && \ 280 c->efd != -1 && (!(c->flags & (CHAN_EOF_RCVD|CHAN_CLOSE_RCVD)) || \ 281 sshbuf_len(c->extended) > 0)) 282 283 /* Add channel management structures to SSH transport instance */ 284 void channel_init_channels(struct ssh *ssh); 285 286 /* channel management */ 287 288 Channel *channel_by_id(struct ssh *, int); 289 Channel *channel_by_remote_id(struct ssh *, u_int); 290 Channel *channel_lookup(struct ssh *, int); 291 Channel *channel_new(struct ssh *, const char *, int, int, int, int, 292 u_int, u_int, int, const char *, int); 293 void channel_set_fds(struct ssh *, int, int, int, int, int, 294 int, int, u_int); 295 void channel_free(struct ssh *, Channel *); 296 void channel_free_all(struct ssh *); 297 void channel_stop_listening(struct ssh *); 298 void channel_force_close(struct ssh *, Channel *, int); 299 void channel_set_xtype(struct ssh *, int, const char *); 300 301 void channel_send_open(struct ssh *, int); 302 void channel_request_start(struct ssh *, int, const char *, int); 303 void channel_register_cleanup(struct ssh *, int, 304 channel_callback_fn *, int); 305 void channel_register_open_confirm(struct ssh *, int, 306 channel_open_fn *, void *); 307 void channel_register_filter(struct ssh *, int, channel_infilter_fn *, 308 channel_outfilter_fn *, channel_filter_cleanup_fn *, void *); 309 void channel_register_status_confirm(struct ssh *, int, 310 channel_confirm_cb *, channel_confirm_abandon_cb *, void *); 311 void channel_cancel_cleanup(struct ssh *, int); 312 int channel_close_fd(struct ssh *, Channel *, int *); 313 void channel_send_window_changes(struct ssh *); 314 315 /* channel inactivity timeouts */ 316 void channel_add_timeout(struct ssh *, const char *, int); 317 void channel_clear_timeouts(struct ssh *); 318 319 /* mux proxy support */ 320 321 int channel_proxy_downstream(struct ssh *, Channel *mc); 322 int channel_proxy_upstream(Channel *, int, u_int32_t, struct ssh *); 323 324 /* protocol handler */ 325 326 int channel_input_data(int, u_int32_t, struct ssh *); 327 int channel_input_extended_data(int, u_int32_t, struct ssh *); 328 int channel_input_ieof(int, u_int32_t, struct ssh *); 329 int channel_input_oclose(int, u_int32_t, struct ssh *); 330 int channel_input_open_confirmation(int, u_int32_t, struct ssh *); 331 int channel_input_open_failure(int, u_int32_t, struct ssh *); 332 int channel_input_window_adjust(int, u_int32_t, struct ssh *); 333 int channel_input_status_confirm(int, u_int32_t, struct ssh *); 334 335 /* file descriptor handling (read/write) */ 336 struct pollfd; 337 struct timespec; 338 339 void channel_prepare_poll(struct ssh *, struct pollfd **, 340 u_int *, u_int *, u_int, struct timespec *); 341 void channel_after_poll(struct ssh *, struct pollfd *, u_int); 342 int channel_output_poll(struct ssh *); 343 344 int channel_not_very_much_buffered_data(struct ssh *); 345 void channel_close_all(struct ssh *); 346 int channel_still_open(struct ssh *); 347 int channel_tty_open(struct ssh *); 348 const char *channel_format_extended_usage(const Channel *); 349 char *channel_open_message(struct ssh *); 350 int channel_find_open(struct ssh *); 351 352 /* tcp forwarding */ 353 struct Forward; 354 struct ForwardOptions; 355 void channel_set_af(struct ssh *, int af); 356 void channel_permit_all(struct ssh *, int); 357 void channel_add_permission(struct ssh *, int, int, char *, int); 358 void channel_clear_permission(struct ssh *, int, int); 359 void channel_disable_admin(struct ssh *, int); 360 void channel_update_permission(struct ssh *, int, int); 361 Channel *channel_connect_to_port(struct ssh *, const char *, u_short, 362 const char *, const char *, int *, const char **); 363 Channel *channel_connect_to_path(struct ssh *, const char *, const char *, 364 const char *); 365 Channel *channel_connect_stdio_fwd(struct ssh *, const char *, 366 int, int, int, int); 367 Channel *channel_connect_by_listen_address(struct ssh *, const char *, 368 u_short, const char *, const char *); 369 Channel *channel_connect_by_listen_path(struct ssh *, const char *, 370 const char *, const char *); 371 int channel_request_remote_forwarding(struct ssh *, struct Forward *); 372 int channel_setup_local_fwd_listener(struct ssh *, struct Forward *, 373 struct ForwardOptions *); 374 int channel_request_rforward_cancel(struct ssh *, struct Forward *); 375 int channel_setup_remote_fwd_listener(struct ssh *, struct Forward *, 376 int *, struct ForwardOptions *); 377 int channel_cancel_rport_listener(struct ssh *, struct Forward *); 378 int channel_cancel_lport_listener(struct ssh *, struct Forward *, 379 int, struct ForwardOptions *); 380 int permitopen_port(const char *); 381 382 /* x11 forwarding */ 383 384 void channel_set_x11_refuse_time(struct ssh *, time_t); 385 int x11_connect_display(struct ssh *); 386 int x11_create_display_inet(struct ssh *, int, int, int, u_int *, int **); 387 void x11_request_forwarding_with_spoofing(struct ssh *, int, 388 const char *, const char *, const char *, int); 389 int x11_channel_used_recently(struct ssh *ssh); 390 391 /* channel close */ 392 393 int chan_is_dead(struct ssh *, Channel *, int); 394 void chan_mark_dead(struct ssh *, Channel *); 395 396 /* channel events */ 397 398 void chan_rcvd_oclose(struct ssh *, Channel *); 399 void chan_rcvd_eow(struct ssh *, Channel *); 400 void chan_read_failed(struct ssh *, Channel *); 401 void chan_ibuf_empty(struct ssh *, Channel *); 402 void chan_rcvd_ieof(struct ssh *, Channel *); 403 void chan_write_failed(struct ssh *, Channel *); 404 void chan_obuf_empty(struct ssh *, Channel *); 405 406 /* hpn handler */ 407 void channel_set_hpn(int, int); 408 409 #endif 410