1/* $NetBSD: channels.h,v 1.26 2023/12/20 17:15:20 christos Exp $ */ 2/* $OpenBSD: channels.h,v 1.154 2023/12/18 14:47:20 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 86struct ssh; 87struct Channel; 88typedef struct Channel Channel; 89struct fwd_perm_list; 90 91typedef void channel_open_fn(struct ssh *, int, int, void *); 92typedef void channel_callback_fn(struct ssh *, int, int, void *); 93typedef int channel_infilter_fn(struct ssh *, struct Channel *, const char *, 94 int); 95typedef void channel_filter_cleanup_fn(struct ssh *, int, void *); 96typedef u_char *channel_outfilter_fn(struct ssh *, struct Channel *, 97 u_char **, size_t *); 98 99/* Channel success/failure callbacks */ 100typedef void channel_confirm_cb(struct ssh *, int, struct Channel *, void *); 101typedef void channel_confirm_abandon_cb(struct ssh *, struct Channel *, void *); 102struct channel_confirm { 103 TAILQ_ENTRY(channel_confirm) entry; 104 channel_confirm_cb *cb; 105 channel_confirm_abandon_cb *abandon_cb; 106 void *ctx; 107}; 108TAILQ_HEAD(channel_confirms, channel_confirm); 109 110/* Context for non-blocking connects */ 111struct channel_connect { 112 char *host; 113 int port; 114 struct addrinfo *ai, *aitop; 115}; 116 117/* Callbacks for mux channels back into client-specific code */ 118typedef int mux_callback_fn(struct ssh *, struct Channel *); 119 120/* 121 * NB. channel IDs on the wire and in c->remote_id are uint32, but local 122 * channel IDs (e.g. c->self) only ever use the int32 subset of this range, 123 * because we use local channel ID -1 for housekeeping. Remote channels have 124 * a dedicated "have_remote_id" flag to indicate their validity. 125 */ 126 127struct Channel { 128 int type; /* channel type/state */ 129 130 int self; /* my own channel identifier */ 131 uint32_t remote_id; /* channel identifier for remote peer */ 132 int have_remote_id; /* non-zero if remote_id is valid */ 133 134 u_int istate; /* input from channel (state of receive half) */ 135 u_int ostate; /* output to channel (state of transmit half) */ 136 int flags; /* close sent/rcvd */ 137 int rfd; /* read fd */ 138 int wfd; /* write fd */ 139 int efd; /* extended fd */ 140 int sock; /* sock fd */ 141 u_int io_want; /* bitmask of SSH_CHAN_IO_* */ 142 u_int io_ready; /* bitmask of SSH_CHAN_IO_* */ 143 int pfds[4]; /* pollfd entries for rfd/wfd/efd/sock */ 144 int ctl_chan; /* control channel (multiplexed connections) */ 145 int isatty; /* rfd is a tty */ 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 dynamic_window; 177 int extended_usage; 178 int single_connection; 179 u_int tcpwinsz; 180 181 char *ctype; /* const type - NB. not freed on channel_free */ 182 char *xctype; /* extended type */ 183 184 /* callback */ 185 channel_open_fn *open_confirm; 186 void *open_confirm_ctx; 187 channel_callback_fn *detach_user; 188 int detach_close; 189 struct channel_confirms status_confirms; 190 191 /* filter */ 192 channel_infilter_fn *input_filter; 193 channel_outfilter_fn *output_filter; 194 void *filter_ctx; 195 channel_filter_cleanup_fn *filter_cleanup; 196 197 /* keep boundaries */ 198 int datagram; 199 200 /* non-blocking connect */ 201 /* XXX make this a pointer so the structure can be opaque */ 202 struct channel_connect connect_ctx; 203 204 /* multiplexing protocol hook, called for each packet received */ 205 mux_callback_fn *mux_rcb; 206 void *mux_ctx; 207 int mux_pause; 208 int mux_downstream_id; 209 210 /* Inactivity timeouts */ 211 212 /* Last traffic seen for OPEN channels */ 213 time_t lastused; 214 /* Inactivity timeout deadline in seconds (0 = no timeout) */ 215 int inactive_deadline; 216}; 217 218#define CHAN_EXTENDED_IGNORE 0 219#define CHAN_EXTENDED_READ 1 220#define CHAN_EXTENDED_WRITE 2 221 222/* default window/packet sizes for tcp/x11-fwd-channel */ 223#define CHAN_SES_PACKET_DEFAULT (32*1024) 224#define CHAN_SES_WINDOW_DEFAULT (4*CHAN_SES_PACKET_DEFAULT) 225 226#define CHAN_TCP_PACKET_DEFAULT (32*1024) 227#define CHAN_TCP_WINDOW_DEFAULT (4*CHAN_TCP_PACKET_DEFAULT) 228 229#define CHAN_X11_PACKET_DEFAULT (16*1024) 230#define CHAN_X11_WINDOW_DEFAULT (4*CHAN_X11_PACKET_DEFAULT) 231 232/* possible input states */ 233#define CHAN_INPUT_OPEN 0 234#define CHAN_INPUT_WAIT_DRAIN 1 235#define CHAN_INPUT_WAIT_OCLOSE 2 236#define CHAN_INPUT_CLOSED 3 237 238/* possible output states */ 239#define CHAN_OUTPUT_OPEN 0 240#define CHAN_OUTPUT_WAIT_DRAIN 1 241#define CHAN_OUTPUT_WAIT_IEOF 2 242#define CHAN_OUTPUT_CLOSED 3 243 244#define CHAN_CLOSE_SENT 0x01 245#define CHAN_CLOSE_RCVD 0x02 246#define CHAN_EOF_SENT 0x04 247#define CHAN_EOF_RCVD 0x08 248#define CHAN_LOCAL 0x10 249 250/* file descriptor events */ 251#define SSH_CHAN_IO_RFD 0x01 252#define SSH_CHAN_IO_WFD 0x02 253#define SSH_CHAN_IO_EFD_R 0x04 254#define SSH_CHAN_IO_EFD_W 0x08 255#define SSH_CHAN_IO_EFD (SSH_CHAN_IO_EFD_R|SSH_CHAN_IO_EFD_W) 256#define SSH_CHAN_IO_SOCK_R 0x10 257#define SSH_CHAN_IO_SOCK_W 0x20 258#define SSH_CHAN_IO_SOCK (SSH_CHAN_IO_SOCK_R|SSH_CHAN_IO_SOCK_W) 259 260/* Read buffer size */ 261#define CHAN_RBUF (16*1024) 262 263/* Maximum size for direct reads to buffers */ 264#define CHANNEL_MAX_READ CHAN_SES_PACKET_DEFAULT 265 266/* Maximum channel input buffer size */ 267#define CHAN_INPUT_MAX (16*1024*1024) 268 269/* Hard limit on number of channels */ 270#define CHANNELS_MAX_CHANNELS (16*1024) 271 272/* check whether 'efd' is still in use */ 273#define CHANNEL_EFD_INPUT_ACTIVE(c) \ 274 (c->extended_usage == CHAN_EXTENDED_READ && \ 275 (c->efd != -1 || \ 276 sshbuf_len(c->extended) > 0)) 277#define CHANNEL_EFD_OUTPUT_ACTIVE(c) \ 278 (c->extended_usage == CHAN_EXTENDED_WRITE && \ 279 c->efd != -1 && (!(c->flags & (CHAN_EOF_RCVD|CHAN_CLOSE_RCVD)) || \ 280 sshbuf_len(c->extended) > 0)) 281 282/* Add channel management structures to SSH transport instance */ 283void channel_init_channels(struct ssh *ssh); 284 285/* channel management */ 286 287Channel *channel_by_id(struct ssh *, int); 288Channel *channel_by_remote_id(struct ssh *, u_int); 289Channel *channel_lookup(struct ssh *, int); 290Channel *channel_new(struct ssh *, const char *, int, int, int, int, 291 u_int, u_int, int, const char *, int); 292void channel_set_fds(struct ssh *, int, int, int, int, int, 293 int, int, u_int); 294void channel_free(struct ssh *, Channel *); 295void channel_free_all(struct ssh *); 296void channel_stop_listening(struct ssh *); 297void channel_force_close(struct ssh *, Channel *, int); 298void channel_set_xtype(struct ssh *, int, const char *); 299 300void channel_send_open(struct ssh *, int); 301void channel_request_start(struct ssh *, int, const char *, int); 302void channel_register_cleanup(struct ssh *, int, 303 channel_callback_fn *, int); 304void channel_register_open_confirm(struct ssh *, int, 305 channel_open_fn *, void *); 306void channel_register_filter(struct ssh *, int, channel_infilter_fn *, 307 channel_outfilter_fn *, channel_filter_cleanup_fn *, void *); 308void channel_register_status_confirm(struct ssh *, int, 309 channel_confirm_cb *, channel_confirm_abandon_cb *, void *); 310void channel_cancel_cleanup(struct ssh *, int); 311int channel_close_fd(struct ssh *, Channel *, int *); 312void channel_send_window_changes(struct ssh *); 313 314/* channel inactivity timeouts */ 315void channel_add_timeout(struct ssh *, const char *, int); 316void channel_clear_timeouts(struct ssh *); 317 318/* mux proxy support */ 319 320int channel_proxy_downstream(struct ssh *, Channel *mc); 321int channel_proxy_upstream(Channel *, int, u_int32_t, struct ssh *); 322 323/* protocol handler */ 324 325int channel_input_data(int, u_int32_t, struct ssh *); 326int channel_input_extended_data(int, u_int32_t, struct ssh *); 327int channel_input_ieof(int, u_int32_t, struct ssh *); 328int channel_input_oclose(int, u_int32_t, struct ssh *); 329int channel_input_open_confirmation(int, u_int32_t, struct ssh *); 330int channel_input_open_failure(int, u_int32_t, struct ssh *); 331int channel_input_port_open(int, u_int32_t, struct ssh *); 332int channel_input_window_adjust(int, u_int32_t, struct ssh *); 333int channel_input_status_confirm(int, u_int32_t, struct ssh *); 334 335/* file descriptor handling (read/write) */ 336struct pollfd; 337struct timespec; 338 339void channel_prepare_poll(struct ssh *, struct pollfd **, 340 u_int *, u_int *, u_int, struct timespec *); 341void channel_after_poll(struct ssh *, struct pollfd *, u_int); 342int channel_output_poll(struct ssh *); 343 344int channel_not_very_much_buffered_data(struct ssh *); 345void channel_close_all(struct ssh *); 346int channel_still_open(struct ssh *); 347int channel_tty_open(struct ssh *); 348const char *channel_format_extended_usage(const Channel *); 349char *channel_open_message(struct ssh *); 350int channel_find_open(struct ssh *); 351 352/* tcp forwarding */ 353struct Forward; 354struct ForwardOptions; 355void channel_set_af(struct ssh *, int af); 356void channel_permit_all(struct ssh *, int); 357void channel_add_permission(struct ssh *, int, int, char *, int); 358void channel_clear_permission(struct ssh *, int, int); 359void channel_disable_admin(struct ssh *, int); 360void channel_update_permission(struct ssh *, int, int); 361Channel *channel_connect_to_port(struct ssh *, const char *, u_short, 362 const char *, const char *, int *, const char **); 363Channel *channel_connect_to_path(struct ssh *, const char *, const char *, 364 const char *); 365Channel *channel_connect_stdio_fwd(struct ssh *, const char *, 366 int, int, int, int); 367Channel *channel_connect_by_listen_address(struct ssh *, const char *, 368 u_short, const char *, const char *); 369Channel *channel_connect_by_listen_path(struct ssh *, const char *, 370 const char *, const char *); 371int channel_request_remote_forwarding(struct ssh *, struct Forward *); 372int channel_setup_local_fwd_listener(struct ssh *, struct Forward *, 373 struct ForwardOptions *); 374int channel_request_rforward_cancel(struct ssh *, struct Forward *); 375int channel_setup_remote_fwd_listener(struct ssh *, struct Forward *, 376 int *, struct ForwardOptions *); 377int channel_cancel_rport_listener(struct ssh *, struct Forward *); 378int channel_cancel_lport_listener(struct ssh *, struct Forward *, 379 int, struct ForwardOptions *); 380int permitopen_port(const char *); 381 382/* x11 forwarding */ 383 384void channel_set_x11_refuse_time(struct ssh *, time_t); 385int x11_connect_display(struct ssh *); 386int x11_create_display_inet(struct ssh *, int, int, int, u_int *, int **); 387void x11_request_forwarding_with_spoofing(struct ssh *, int, 388 const char *, const char *, const char *, int); 389 390/* channel close */ 391 392int chan_is_dead(struct ssh *, Channel *, int); 393void chan_mark_dead(struct ssh *, Channel *); 394 395/* channel events */ 396 397void chan_rcvd_oclose(struct ssh *, Channel *); 398void chan_rcvd_eow(struct ssh *, Channel *); 399void chan_read_failed(struct ssh *, Channel *); 400void chan_ibuf_empty(struct ssh *, Channel *); 401void chan_rcvd_ieof(struct ssh *, Channel *); 402void chan_write_failed(struct ssh *, Channel *); 403void chan_obuf_empty(struct ssh *, Channel *); 404 405/* hpn handler */ 406void channel_set_hpn(int, int); 407 408#endif 409