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 85 struct ssh; 86 struct Channel; 87 typedef struct Channel Channel; 88 89 typedef void channel_open_fn(struct ssh *, int, int, void *); 90 typedef void channel_callback_fn(struct ssh *, int, int, void *); 91 typedef int channel_infilter_fn(struct ssh *, struct Channel *, char *, int); 92 typedef void channel_filter_cleanup_fn(struct ssh *, int, void *); 93 typedef u_char *channel_outfilter_fn(struct ssh *, struct Channel *, 94 u_char **, size_t *); 95 96 /* Channel success/failure callbacks */ 97 typedef void channel_confirm_cb(struct ssh *, int, struct Channel *, void *); 98 typedef void channel_confirm_abandon_cb(struct ssh *, struct Channel *, void *); 99 struct channel_confirm { 100 TAILQ_ENTRY(channel_confirm) entry; 101 channel_confirm_cb *cb; 102 channel_confirm_abandon_cb *abandon_cb; 103 void *ctx; 104 }; 105 TAILQ_HEAD(channel_confirms, channel_confirm); 106 107 /* Context for non-blocking connects */ 108 struct 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 */ 115 typedef 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 */ 123 124 struct 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 #ifdef _AIX 144 int wfd_isatty; /* wfd is a tty */ 145 #endif 146 int client_tty; /* (client) TTY has been requested */ 147 int force_drain; /* force close on iEOF */ 148 time_t notbefore; /* Pause IO until deadline (time_t) */ 149 int delayed; /* post-IO handlers for newly created 150 * channels are delayed until the first call 151 * to a matching pre-IO handler. 152 * this way post-IO handlers are not 153 * accidentally called if a FD gets reused */ 154 int restore_block; /* fd mask to restore blocking status */ 155 int restore_flags[3];/* flags to restore */ 156 struct sshbuf *input; /* data read from socket, to be sent over 157 * encrypted connection */ 158 struct sshbuf *output; /* data received over encrypted connection for 159 * send on socket */ 160 struct sshbuf *extended; 161 162 char *path; 163 /* path for unix domain sockets, or host name for forwards */ 164 int listening_port; /* port being listened for forwards */ 165 char *listening_addr; /* addr being listened for forwards */ 166 int host_port; /* remote port to connect for forwards */ 167 char *remote_name; /* remote hostname */ 168 169 u_int remote_window; 170 u_int remote_maxpacket; 171 u_int local_window; 172 u_int local_window_exceeded; 173 u_int local_window_max; 174 u_int local_consumed; 175 u_int local_maxpacket; 176 int extended_usage; 177 int single_connection; 178 179 char *ctype; /* const type - NB. not freed on channel_free */ 180 char *xctype; /* extended type */ 181 182 /* callback */ 183 channel_open_fn *open_confirm; 184 void *open_confirm_ctx; 185 channel_callback_fn *detach_user; 186 int detach_close; 187 struct channel_confirms status_confirms; 188 189 /* filter */ 190 channel_infilter_fn *input_filter; 191 channel_outfilter_fn *output_filter; 192 void *filter_ctx; 193 channel_filter_cleanup_fn *filter_cleanup; 194 195 /* keep boundaries */ 196 int datagram; 197 198 /* non-blocking connect */ 199 /* XXX make this a pointer so the structure can be opaque */ 200 struct channel_connect connect_ctx; 201 202 /* multiplexing protocol hook, called for each packet received */ 203 mux_callback_fn *mux_rcb; 204 void *mux_ctx; 205 int mux_pause; 206 int mux_downstream_id; 207 208 /* Inactivity timeouts */ 209 210 /* Last traffic seen for OPEN channels */ 211 time_t lastused; 212 /* Inactivity timeout deadline in seconds (0 = no timeout) */ 213 int inactive_deadline; 214 }; 215 216 #define CHAN_EXTENDED_IGNORE 0 217 #define CHAN_EXTENDED_READ 1 218 #define CHAN_EXTENDED_WRITE 2 219 220 /* default window/packet sizes for tcp/x11-fwd-channel */ 221 #define CHAN_SES_PACKET_DEFAULT (32*1024) 222 #define CHAN_SES_WINDOW_DEFAULT (64*CHAN_SES_PACKET_DEFAULT) 223 #define CHAN_TCP_PACKET_DEFAULT (32*1024) 224 #define CHAN_TCP_WINDOW_DEFAULT (64*CHAN_TCP_PACKET_DEFAULT) 225 #define CHAN_X11_PACKET_DEFAULT (16*1024) 226 #define CHAN_X11_WINDOW_DEFAULT (4*CHAN_X11_PACKET_DEFAULT) 227 228 /* possible input states */ 229 #define CHAN_INPUT_OPEN 0 230 #define CHAN_INPUT_WAIT_DRAIN 1 231 #define CHAN_INPUT_WAIT_OCLOSE 2 232 #define CHAN_INPUT_CLOSED 3 233 234 /* possible output states */ 235 #define CHAN_OUTPUT_OPEN 0 236 #define CHAN_OUTPUT_WAIT_DRAIN 1 237 #define CHAN_OUTPUT_WAIT_IEOF 2 238 #define CHAN_OUTPUT_CLOSED 3 239 240 #define CHAN_CLOSE_SENT 0x01 241 #define CHAN_CLOSE_RCVD 0x02 242 #define CHAN_EOF_SENT 0x04 243 #define CHAN_EOF_RCVD 0x08 244 #define CHAN_LOCAL 0x10 245 246 /* file descriptor events */ 247 #define SSH_CHAN_IO_RFD 0x01 248 #define SSH_CHAN_IO_WFD 0x02 249 #define SSH_CHAN_IO_EFD_R 0x04 250 #define SSH_CHAN_IO_EFD_W 0x08 251 #define SSH_CHAN_IO_EFD (SSH_CHAN_IO_EFD_R|SSH_CHAN_IO_EFD_W) 252 #define SSH_CHAN_IO_SOCK_R 0x10 253 #define SSH_CHAN_IO_SOCK_W 0x20 254 #define SSH_CHAN_IO_SOCK (SSH_CHAN_IO_SOCK_R|SSH_CHAN_IO_SOCK_W) 255 256 /* Read buffer size */ 257 #define CHAN_RBUF (16*1024) 258 259 /* Maximum size for direct reads to buffers */ 260 #define CHANNEL_MAX_READ CHAN_SES_PACKET_DEFAULT 261 262 /* Maximum channel input buffer size */ 263 #define CHAN_INPUT_MAX (16*1024*1024) 264 265 /* Hard limit on number of channels */ 266 #define CHANNELS_MAX_CHANNELS (16*1024) 267 268 /* check whether 'efd' is still in use */ 269 #define CHANNEL_EFD_INPUT_ACTIVE(c) \ 270 (c->extended_usage == CHAN_EXTENDED_READ && \ 271 (c->efd != -1 || \ 272 sshbuf_len(c->extended) > 0)) 273 #define CHANNEL_EFD_OUTPUT_ACTIVE(c) \ 274 (c->extended_usage == CHAN_EXTENDED_WRITE && \ 275 c->efd != -1 && (!(c->flags & (CHAN_EOF_RCVD|CHAN_CLOSE_RCVD)) || \ 276 sshbuf_len(c->extended) > 0)) 277 278 /* Add channel management structures to SSH transport instance */ 279 void channel_init_channels(struct ssh *ssh); 280 281 /* channel management */ 282 283 Channel *channel_by_id(struct ssh *, int); 284 Channel *channel_by_remote_id(struct ssh *, u_int); 285 Channel *channel_lookup(struct ssh *, int); 286 Channel *channel_new(struct ssh *, char *, int, int, int, int, 287 u_int, u_int, int, const char *, int); 288 void channel_set_fds(struct ssh *, int, int, int, int, int, 289 int, int, u_int); 290 void channel_free(struct ssh *, Channel *); 291 void channel_free_all(struct ssh *); 292 void channel_stop_listening(struct ssh *); 293 void channel_force_close(struct ssh *, Channel *, int); 294 void channel_set_xtype(struct ssh *, int, const char *); 295 296 void channel_send_open(struct ssh *, int); 297 void channel_request_start(struct ssh *, int, char *, int); 298 void channel_register_cleanup(struct ssh *, int, 299 channel_callback_fn *, int); 300 void channel_register_open_confirm(struct ssh *, int, 301 channel_open_fn *, void *); 302 void channel_register_filter(struct ssh *, int, channel_infilter_fn *, 303 channel_outfilter_fn *, channel_filter_cleanup_fn *, void *); 304 void channel_register_status_confirm(struct ssh *, int, 305 channel_confirm_cb *, channel_confirm_abandon_cb *, void *); 306 void channel_cancel_cleanup(struct ssh *, int); 307 int channel_close_fd(struct ssh *, Channel *, int *); 308 void channel_send_window_changes(struct ssh *); 309 310 /* channel inactivity timeouts */ 311 void channel_add_timeout(struct ssh *, const char *, int); 312 void channel_clear_timeouts(struct ssh *); 313 314 /* mux proxy support */ 315 316 int channel_proxy_downstream(struct ssh *, Channel *mc); 317 int channel_proxy_upstream(Channel *, int, u_int32_t, struct ssh *); 318 319 /* protocol handler */ 320 321 int channel_input_data(int, u_int32_t, struct ssh *); 322 int channel_input_extended_data(int, u_int32_t, struct ssh *); 323 int channel_input_ieof(int, u_int32_t, struct ssh *); 324 int channel_input_oclose(int, u_int32_t, struct ssh *); 325 int channel_input_open_confirmation(int, u_int32_t, struct ssh *); 326 int channel_input_open_failure(int, u_int32_t, struct ssh *); 327 int channel_input_window_adjust(int, u_int32_t, struct ssh *); 328 int channel_input_status_confirm(int, u_int32_t, struct ssh *); 329 330 /* file descriptor handling (read/write) */ 331 struct pollfd; 332 struct timespec; 333 334 void channel_prepare_poll(struct ssh *, struct pollfd **, 335 u_int *, u_int *, u_int, struct timespec *); 336 void channel_after_poll(struct ssh *, struct pollfd *, u_int); 337 int channel_output_poll(struct ssh *); 338 339 int channel_not_very_much_buffered_data(struct ssh *); 340 void channel_close_all(struct ssh *); 341 int channel_still_open(struct ssh *); 342 int channel_tty_open(struct ssh *); 343 const char *channel_format_extended_usage(const Channel *); 344 char *channel_open_message(struct ssh *); 345 int channel_find_open(struct ssh *); 346 347 /* tcp forwarding */ 348 struct Forward; 349 struct ForwardOptions; 350 void channel_set_af(struct ssh *, int af); 351 void channel_permit_all(struct ssh *, int); 352 void channel_add_permission(struct ssh *, int, int, char *, int); 353 void channel_clear_permission(struct ssh *, int, int); 354 void channel_disable_admin(struct ssh *, int); 355 void channel_update_permission(struct ssh *, int, int); 356 Channel *channel_connect_to_port(struct ssh *, const char *, u_short, 357 char *, char *, int *, const char **); 358 Channel *channel_connect_to_path(struct ssh *, const char *, char *, char *); 359 Channel *channel_connect_stdio_fwd(struct ssh *, const char*, 360 int, int, int, int); 361 Channel *channel_connect_by_listen_address(struct ssh *, const char *, 362 u_short, char *, char *); 363 Channel *channel_connect_by_listen_path(struct ssh *, const char *, 364 char *, char *); 365 int channel_request_remote_forwarding(struct ssh *, struct Forward *); 366 int channel_setup_local_fwd_listener(struct ssh *, struct Forward *, 367 struct ForwardOptions *); 368 int channel_request_rforward_cancel(struct ssh *, struct Forward *); 369 int channel_setup_remote_fwd_listener(struct ssh *, struct Forward *, 370 int *, struct ForwardOptions *); 371 int channel_cancel_rport_listener(struct ssh *, struct Forward *); 372 int channel_cancel_lport_listener(struct ssh *, struct Forward *, 373 int, struct ForwardOptions *); 374 int permitopen_port(const char *); 375 376 /* x11 forwarding */ 377 378 void channel_set_x11_refuse_time(struct ssh *, time_t); 379 int x11_connect_display(struct ssh *); 380 int x11_create_display_inet(struct ssh *, int, int, int, u_int *, int **); 381 void x11_request_forwarding_with_spoofing(struct ssh *, int, 382 const char *, const char *, const char *, int); 383 384 /* channel close */ 385 386 int chan_is_dead(struct ssh *, Channel *, int); 387 void chan_mark_dead(struct ssh *, Channel *); 388 389 /* channel events */ 390 391 void chan_rcvd_oclose(struct ssh *, Channel *); 392 void chan_rcvd_eow(struct ssh *, Channel *); 393 void chan_read_failed(struct ssh *, Channel *); 394 void chan_ibuf_empty(struct ssh *, Channel *); 395 void chan_rcvd_ieof(struct ssh *, Channel *); 396 void chan_write_failed(struct ssh *, Channel *); 397 void chan_obuf_empty(struct ssh *, Channel *); 398 399 #endif 400