1/* $OpenBSD: channels.h,v 1.154 2023/12/18 14:47:20 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 85struct ssh; 86struct Channel; 87typedef struct Channel Channel; 88struct fwd_perm_list; 89 90typedef void channel_open_fn(struct ssh *, int, int, void *); 91typedef void channel_callback_fn(struct ssh *, int, int, void *); 92typedef int channel_infilter_fn(struct ssh *, struct Channel *, char *, int); 93typedef void channel_filter_cleanup_fn(struct ssh *, int, void *); 94typedef u_char *channel_outfilter_fn(struct ssh *, struct Channel *, 95 u_char **, size_t *); 96 97/* Channel success/failure callbacks */ 98typedef void channel_confirm_cb(struct ssh *, int, struct Channel *, void *); 99typedef void channel_confirm_abandon_cb(struct ssh *, struct Channel *, void *); 100struct channel_confirm { 101 TAILQ_ENTRY(channel_confirm) entry; 102 channel_confirm_cb *cb; 103 channel_confirm_abandon_cb *abandon_cb; 104 void *ctx; 105}; 106TAILQ_HEAD(channel_confirms, channel_confirm); 107 108/* Context for non-blocking connects */ 109struct channel_connect { 110 char *host; 111 int port; 112 struct addrinfo *ai, *aitop; 113}; 114 115/* Callbacks for mux channels back into client-specific code */ 116typedef int mux_callback_fn(struct ssh *, struct Channel *); 117 118/* 119 * NB. channel IDs on the wire and in c->remote_id are uint32, but local 120 * channel IDs (e.g. c->self) only ever use the int32 subset of this range, 121 * because we use local channel ID -1 for housekeeping. Remote channels have 122 * a dedicated "have_remote_id" flag to indicate their validity. 123 */ 124 125struct Channel { 126 int type; /* channel type/state */ 127 128 int self; /* my own channel identifier */ 129 uint32_t remote_id; /* channel identifier for remote peer */ 130 int have_remote_id; /* non-zero if remote_id is valid */ 131 132 u_int istate; /* input from channel (state of receive half) */ 133 u_int ostate; /* output to channel (state of transmit half) */ 134 int flags; /* close sent/rcvd */ 135 int rfd; /* read fd */ 136 int wfd; /* write fd */ 137 int efd; /* extended fd */ 138 int sock; /* sock fd */ 139 u_int io_want; /* bitmask of SSH_CHAN_IO_* */ 140 u_int io_ready; /* bitmask of SSH_CHAN_IO_* */ 141 int pfds[4]; /* pollfd entries for rfd/wfd/efd/sock */ 142 int ctl_chan; /* control channel (multiplexed connections) */ 143 int isatty; /* rfd is a tty */ 144#ifdef _AIX 145 int wfd_isatty; /* wfd is a tty */ 146#endif 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 extended_usage; 178 int single_connection; 179 180 char *ctype; /* const type - NB. not freed on channel_free */ 181 char *xctype; /* extended type */ 182 183 /* callback */ 184 channel_open_fn *open_confirm; 185 void *open_confirm_ctx; 186 channel_callback_fn *detach_user; 187 int detach_close; 188 struct channel_confirms status_confirms; 189 190 /* filter */ 191 channel_infilter_fn *input_filter; 192 channel_outfilter_fn *output_filter; 193 void *filter_ctx; 194 channel_filter_cleanup_fn *filter_cleanup; 195 196 /* keep boundaries */ 197 int datagram; 198 199 /* non-blocking connect */ 200 /* XXX make this a pointer so the structure can be opaque */ 201 struct channel_connect connect_ctx; 202 203 /* multiplexing protocol hook, called for each packet received */ 204 mux_callback_fn *mux_rcb; 205 void *mux_ctx; 206 int mux_pause; 207 int mux_downstream_id; 208 209 /* Inactivity timeouts */ 210 211 /* Last traffic seen for OPEN channels */ 212 time_t lastused; 213 /* Inactivity timeout deadline in seconds (0 = no timeout) */ 214 int inactive_deadline; 215}; 216 217#define CHAN_EXTENDED_IGNORE 0 218#define CHAN_EXTENDED_READ 1 219#define CHAN_EXTENDED_WRITE 2 220 221/* default window/packet sizes for tcp/x11-fwd-channel */ 222#define CHAN_SES_PACKET_DEFAULT (32*1024) 223#define CHAN_SES_WINDOW_DEFAULT (64*CHAN_SES_PACKET_DEFAULT) 224#define CHAN_TCP_PACKET_DEFAULT (32*1024) 225#define CHAN_TCP_WINDOW_DEFAULT (64*CHAN_TCP_PACKET_DEFAULT) 226#define CHAN_X11_PACKET_DEFAULT (16*1024) 227#define CHAN_X11_WINDOW_DEFAULT (4*CHAN_X11_PACKET_DEFAULT) 228 229/* possible input states */ 230#define CHAN_INPUT_OPEN 0 231#define CHAN_INPUT_WAIT_DRAIN 1 232#define CHAN_INPUT_WAIT_OCLOSE 2 233#define CHAN_INPUT_CLOSED 3 234 235/* possible output states */ 236#define CHAN_OUTPUT_OPEN 0 237#define CHAN_OUTPUT_WAIT_DRAIN 1 238#define CHAN_OUTPUT_WAIT_IEOF 2 239#define CHAN_OUTPUT_CLOSED 3 240 241#define CHAN_CLOSE_SENT 0x01 242#define CHAN_CLOSE_RCVD 0x02 243#define CHAN_EOF_SENT 0x04 244#define CHAN_EOF_RCVD 0x08 245#define CHAN_LOCAL 0x10 246 247/* file descriptor events */ 248#define SSH_CHAN_IO_RFD 0x01 249#define SSH_CHAN_IO_WFD 0x02 250#define SSH_CHAN_IO_EFD_R 0x04 251#define SSH_CHAN_IO_EFD_W 0x08 252#define SSH_CHAN_IO_EFD (SSH_CHAN_IO_EFD_R|SSH_CHAN_IO_EFD_W) 253#define SSH_CHAN_IO_SOCK_R 0x10 254#define SSH_CHAN_IO_SOCK_W 0x20 255#define SSH_CHAN_IO_SOCK (SSH_CHAN_IO_SOCK_R|SSH_CHAN_IO_SOCK_W) 256 257/* Read buffer size */ 258#define CHAN_RBUF (16*1024) 259 260/* Maximum size for direct reads to buffers */ 261#define CHANNEL_MAX_READ CHAN_SES_PACKET_DEFAULT 262 263/* Maximum channel input buffer size */ 264#define CHAN_INPUT_MAX (16*1024*1024) 265 266/* Hard limit on number of channels */ 267#define CHANNELS_MAX_CHANNELS (16*1024) 268 269/* check whether 'efd' is still in use */ 270#define CHANNEL_EFD_INPUT_ACTIVE(c) \ 271 (c->extended_usage == CHAN_EXTENDED_READ && \ 272 (c->efd != -1 || \ 273 sshbuf_len(c->extended) > 0)) 274#define CHANNEL_EFD_OUTPUT_ACTIVE(c) \ 275 (c->extended_usage == CHAN_EXTENDED_WRITE && \ 276 c->efd != -1 && (!(c->flags & (CHAN_EOF_RCVD|CHAN_CLOSE_RCVD)) || \ 277 sshbuf_len(c->extended) > 0)) 278 279/* Add channel management structures to SSH transport instance */ 280void channel_init_channels(struct ssh *ssh); 281 282/* channel management */ 283 284Channel *channel_by_id(struct ssh *, int); 285Channel *channel_by_remote_id(struct ssh *, u_int); 286Channel *channel_lookup(struct ssh *, int); 287Channel *channel_new(struct ssh *, char *, int, int, int, int, 288 u_int, u_int, int, const char *, int); 289void channel_set_fds(struct ssh *, int, int, int, int, int, 290 int, int, u_int); 291void channel_free(struct ssh *, Channel *); 292void channel_free_all(struct ssh *); 293void channel_stop_listening(struct ssh *); 294void channel_force_close(struct ssh *, Channel *, int); 295void channel_set_xtype(struct ssh *, int, const char *); 296 297void channel_send_open(struct ssh *, int); 298void channel_request_start(struct ssh *, int, char *, int); 299void channel_register_cleanup(struct ssh *, int, 300 channel_callback_fn *, int); 301void channel_register_open_confirm(struct ssh *, int, 302 channel_open_fn *, void *); 303void channel_register_filter(struct ssh *, int, channel_infilter_fn *, 304 channel_outfilter_fn *, channel_filter_cleanup_fn *, void *); 305void channel_register_status_confirm(struct ssh *, int, 306 channel_confirm_cb *, channel_confirm_abandon_cb *, void *); 307void channel_cancel_cleanup(struct ssh *, int); 308int channel_close_fd(struct ssh *, Channel *, int *); 309void channel_send_window_changes(struct ssh *); 310 311/* channel inactivity timeouts */ 312void channel_add_timeout(struct ssh *, const char *, int); 313void channel_clear_timeouts(struct ssh *); 314 315/* mux proxy support */ 316 317int channel_proxy_downstream(struct ssh *, Channel *mc); 318int channel_proxy_upstream(Channel *, int, u_int32_t, struct ssh *); 319 320/* protocol handler */ 321 322int channel_input_data(int, u_int32_t, struct ssh *); 323int channel_input_extended_data(int, u_int32_t, struct ssh *); 324int channel_input_ieof(int, u_int32_t, struct ssh *); 325int channel_input_oclose(int, u_int32_t, struct ssh *); 326int channel_input_open_confirmation(int, u_int32_t, struct ssh *); 327int channel_input_open_failure(int, u_int32_t, struct ssh *); 328int channel_input_port_open(int, u_int32_t, struct ssh *); 329int channel_input_window_adjust(int, u_int32_t, struct ssh *); 330int channel_input_status_confirm(int, u_int32_t, struct ssh *); 331 332/* file descriptor handling (read/write) */ 333struct pollfd; 334struct timespec; 335 336void channel_prepare_poll(struct ssh *, struct pollfd **, 337 u_int *, u_int *, u_int, struct timespec *); 338void channel_after_poll(struct ssh *, struct pollfd *, u_int); 339int channel_output_poll(struct ssh *); 340 341int channel_not_very_much_buffered_data(struct ssh *); 342void channel_close_all(struct ssh *); 343int channel_still_open(struct ssh *); 344int channel_tty_open(struct ssh *); 345const char *channel_format_extended_usage(const Channel *); 346char *channel_open_message(struct ssh *); 347int channel_find_open(struct ssh *); 348 349/* tcp forwarding */ 350struct Forward; 351struct ForwardOptions; 352void channel_set_af(struct ssh *, int af); 353void channel_permit_all(struct ssh *, int); 354void channel_add_permission(struct ssh *, int, int, char *, int); 355void channel_clear_permission(struct ssh *, int, int); 356void channel_disable_admin(struct ssh *, int); 357void channel_update_permission(struct ssh *, int, int); 358Channel *channel_connect_to_port(struct ssh *, const char *, u_short, 359 char *, char *, int *, const char **); 360Channel *channel_connect_to_path(struct ssh *, const char *, char *, char *); 361Channel *channel_connect_stdio_fwd(struct ssh *, const char*, 362 int, int, int, int); 363Channel *channel_connect_by_listen_address(struct ssh *, const char *, 364 u_short, char *, char *); 365Channel *channel_connect_by_listen_path(struct ssh *, const char *, 366 char *, char *); 367int channel_request_remote_forwarding(struct ssh *, struct Forward *); 368int channel_setup_local_fwd_listener(struct ssh *, struct Forward *, 369 struct ForwardOptions *); 370int channel_request_rforward_cancel(struct ssh *, struct Forward *); 371int channel_setup_remote_fwd_listener(struct ssh *, struct Forward *, 372 int *, struct ForwardOptions *); 373int channel_cancel_rport_listener(struct ssh *, struct Forward *); 374int channel_cancel_lport_listener(struct ssh *, struct Forward *, 375 int, struct ForwardOptions *); 376int permitopen_port(const char *); 377 378/* x11 forwarding */ 379 380void channel_set_x11_refuse_time(struct ssh *, time_t); 381int x11_connect_display(struct ssh *); 382int x11_create_display_inet(struct ssh *, int, int, int, u_int *, int **); 383void x11_request_forwarding_with_spoofing(struct ssh *, int, 384 const char *, const char *, const char *, int); 385 386/* channel close */ 387 388int chan_is_dead(struct ssh *, Channel *, int); 389void chan_mark_dead(struct ssh *, Channel *); 390 391/* channel events */ 392 393void chan_rcvd_oclose(struct ssh *, Channel *); 394void chan_rcvd_eow(struct ssh *, Channel *); 395void chan_read_failed(struct ssh *, Channel *); 396void chan_ibuf_empty(struct ssh *, Channel *); 397void chan_rcvd_ieof(struct ssh *, Channel *); 398void chan_write_failed(struct ssh *, Channel *); 399void chan_obuf_empty(struct ssh *, Channel *); 400 401#endif 402