nchan.c revision 1.40
1/* 2 * Copyright (c) 1999, 2000, 2001 Markus Friedl. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 1. Redistributions of source code must retain the above copyright 8 * notice, this list of conditions and the following disclaimer. 9 * 2. Redistributions in binary form must reproduce the above copyright 10 * notice, this list of conditions and the following disclaimer in the 11 * documentation and/or other materials provided with the distribution. 12 * 13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 14 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 15 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 17 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 18 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 19 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 20 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 21 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 22 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 23 */ 24 25#include "includes.h" 26RCSID("$OpenBSD: nchan.c,v 1.40 2002/01/14 13:40:10 markus Exp $"); 27 28#include "ssh1.h" 29#include "ssh2.h" 30#include "buffer.h" 31#include "packet.h" 32#include "channels.h" 33#include "compat.h" 34#include "log.h" 35 36/* 37 * SSH Protocol 1.5 aka New Channel Protocol 38 * Thanks to Martina, Axel and everyone who left Erlangen, leaving me bored. 39 * Written by Markus Friedl in October 1999 40 * 41 * Protocol versions 1.3 and 1.5 differ in the handshake protocol used for the 42 * tear down of channels: 43 * 44 * 1.3: strict request-ack-protocol: 45 * CLOSE -> 46 * <- CLOSE_CONFIRM 47 * 48 * 1.5: uses variations of: 49 * IEOF -> 50 * <- OCLOSE 51 * <- IEOF 52 * OCLOSE -> 53 * i.e. both sides have to close the channel 54 * 55 * 2.0: the EOF messages are optional 56 * 57 * See the debugging output from 'ssh -v' and 'sshd -d' of 58 * ssh-1.2.27 as an example. 59 * 60 */ 61 62/* functions manipulating channel states */ 63/* 64 * EVENTS update channel input/output states execute ACTIONS 65 */ 66/* events concerning the INPUT from socket for channel (istate) */ 67chan_event_fn *chan_rcvd_oclose = NULL; 68chan_event_fn *chan_read_failed = NULL; 69chan_event_fn *chan_ibuf_empty = NULL; 70/* events concerning the OUTPUT from channel for socket (ostate) */ 71chan_event_fn *chan_rcvd_ieof = NULL; 72chan_event_fn *chan_write_failed = NULL; 73chan_event_fn *chan_obuf_empty = NULL; 74/* 75 * ACTIONS: should never update the channel states 76 */ 77static void chan_send_ieof1(Channel *); 78static void chan_send_oclose1(Channel *); 79static void chan_send_close2(Channel *); 80static void chan_send_eof2(Channel *); 81 82/* helper */ 83static void chan_shutdown_write(Channel *); 84static void chan_shutdown_read(Channel *); 85 86static char *ostates[] = { "open", "drain", "wait_ieof", "closed" }; 87static char *istates[] = { "open", "drain", "wait_oclose", "closed" }; 88 89static void 90chan_set_istate(Channel *c, u_int next) 91{ 92 if (c->istate > CHAN_INPUT_CLOSED || next > CHAN_INPUT_CLOSED) 93 fatal("chan_set_istate: bad state %d -> %d", c->istate, next); 94 debug("channel %d: input %s -> %s", c->self, istates[c->istate], 95 istates[next]); 96 c->istate = next; 97} 98static void 99chan_set_ostate(Channel *c, u_int next) 100{ 101 if (c->ostate > CHAN_OUTPUT_CLOSED || next > CHAN_OUTPUT_CLOSED) 102 fatal("chan_set_ostate: bad state %d -> %d", c->ostate, next); 103 debug("channel %d: output %s -> %s", c->self, ostates[c->ostate], 104 ostates[next]); 105 c->ostate = next; 106} 107 108/* 109 * SSH1 specific implementation of event functions 110 */ 111 112static void 113chan_rcvd_oclose1(Channel *c) 114{ 115 debug("channel %d: rcvd oclose", c->self); 116 switch (c->istate) { 117 case CHAN_INPUT_WAIT_OCLOSE: 118 chan_set_istate(c, CHAN_INPUT_CLOSED); 119 break; 120 case CHAN_INPUT_OPEN: 121 chan_shutdown_read(c); 122 chan_send_ieof1(c); 123 chan_set_istate(c, CHAN_INPUT_CLOSED); 124 break; 125 case CHAN_INPUT_WAIT_DRAIN: 126 /* both local read_failed and remote write_failed */ 127 chan_send_ieof1(c); 128 chan_set_istate(c, CHAN_INPUT_CLOSED); 129 break; 130 default: 131 error("channel %d: protocol error: rcvd_oclose for istate %d", 132 c->self, c->istate); 133 return; 134 } 135} 136static void 137chan_read_failed_12(Channel *c) 138{ 139 debug("channel %d: read failed", c->self); 140 switch (c->istate) { 141 case CHAN_INPUT_OPEN: 142 chan_shutdown_read(c); 143 chan_set_istate(c, CHAN_INPUT_WAIT_DRAIN); 144 break; 145 default: 146 error("channel %d: chan_read_failed for istate %d", 147 c->self, c->istate); 148 break; 149 } 150} 151static void 152chan_ibuf_empty1(Channel *c) 153{ 154 debug("channel %d: ibuf empty", c->self); 155 if (buffer_len(&c->input)) { 156 error("channel %d: chan_ibuf_empty for non empty buffer", 157 c->self); 158 return; 159 } 160 switch (c->istate) { 161 case CHAN_INPUT_WAIT_DRAIN: 162 if (compat20) { 163 if (!(c->flags & CHAN_CLOSE_SENT)) 164 chan_send_eof2(c); 165 chan_set_istate(c, CHAN_INPUT_CLOSED); 166 } else { 167 chan_send_ieof1(c); 168 chan_set_istate(c, CHAN_INPUT_WAIT_OCLOSE); 169 } 170 break; 171 default: 172 error("channel %d: chan_ibuf_empty for istate %d", 173 c->self, c->istate); 174 break; 175 } 176} 177static void 178chan_rcvd_ieof1(Channel *c) 179{ 180 debug("channel %d: rcvd ieof", c->self); 181 switch (c->ostate) { 182 case CHAN_OUTPUT_OPEN: 183 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); 184 break; 185 case CHAN_OUTPUT_WAIT_IEOF: 186 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 187 break; 188 default: 189 error("channel %d: protocol error: rcvd_ieof for ostate %d", 190 c->self, c->ostate); 191 break; 192 } 193} 194static void 195chan_write_failed1(Channel *c) 196{ 197 debug("channel %d: write failed", c->self); 198 switch (c->ostate) { 199 case CHAN_OUTPUT_OPEN: 200 chan_shutdown_write(c); 201 chan_send_oclose1(c); 202 chan_set_ostate(c, CHAN_OUTPUT_WAIT_IEOF); 203 break; 204 case CHAN_OUTPUT_WAIT_DRAIN: 205 chan_shutdown_write(c); 206 chan_send_oclose1(c); 207 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 208 break; 209 default: 210 error("channel %d: chan_write_failed for ostate %d", 211 c->self, c->ostate); 212 break; 213 } 214} 215static void 216chan_obuf_empty1(Channel *c) 217{ 218 debug("channel %d: obuf empty", c->self); 219 if (buffer_len(&c->output)) { 220 error("channel %d: chan_obuf_empty for non empty buffer", 221 c->self); 222 return; 223 } 224 switch (c->ostate) { 225 case CHAN_OUTPUT_WAIT_DRAIN: 226 chan_shutdown_write(c); 227 if (!compat20) 228 chan_send_oclose1(c); 229 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 230 break; 231 default: 232 error("channel %d: internal error: obuf_empty for ostate %d", 233 c->self, c->ostate); 234 break; 235 } 236} 237static void 238chan_send_ieof1(Channel *c) 239{ 240 debug("channel %d: send ieof", c->self); 241 switch (c->istate) { 242 case CHAN_INPUT_OPEN: 243 case CHAN_INPUT_WAIT_DRAIN: 244 packet_start(SSH_MSG_CHANNEL_INPUT_EOF); 245 packet_put_int(c->remote_id); 246 packet_send(); 247 break; 248 default: 249 error("channel %d: cannot send ieof for istate %d", 250 c->self, c->istate); 251 break; 252 } 253} 254static void 255chan_send_oclose1(Channel *c) 256{ 257 debug("channel %d: send oclose", c->self); 258 switch (c->ostate) { 259 case CHAN_OUTPUT_OPEN: 260 case CHAN_OUTPUT_WAIT_DRAIN: 261 buffer_clear(&c->output); 262 packet_start(SSH_MSG_CHANNEL_OUTPUT_CLOSE); 263 packet_put_int(c->remote_id); 264 packet_send(); 265 break; 266 default: 267 error("channel %d: cannot send oclose for ostate %d", 268 c->self, c->ostate); 269 break; 270 } 271} 272 273/* 274 * the same for SSH2 275 */ 276static void 277chan_rcvd_close2(Channel *c) 278{ 279 debug("channel %d: rcvd close", c->self); 280 if (c->flags & CHAN_CLOSE_RCVD) 281 error("channel %d: protocol error: close rcvd twice", c->self); 282 c->flags |= CHAN_CLOSE_RCVD; 283 if (c->type == SSH_CHANNEL_LARVAL) { 284 /* tear down larval channels immediately */ 285 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 286 chan_set_istate(c, CHAN_INPUT_CLOSED); 287 return; 288 } 289 switch (c->ostate) { 290 case CHAN_OUTPUT_OPEN: 291 /* 292 * wait until a data from the channel is consumed if a CLOSE 293 * is received 294 */ 295 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); 296 break; 297 } 298 switch (c->istate) { 299 case CHAN_INPUT_OPEN: 300 chan_shutdown_read(c); 301 chan_set_istate(c, CHAN_INPUT_CLOSED); 302 break; 303 case CHAN_INPUT_WAIT_DRAIN: 304 chan_send_eof2(c); 305 chan_set_istate(c, CHAN_INPUT_CLOSED); 306 break; 307 } 308} 309static void 310chan_ibuf_empty2(Channel *c) 311{ 312 chan_ibuf_empty1(c); 313} 314static void 315chan_rcvd_eof2(Channel *c) 316{ 317 debug("channel %d: rcvd eof", c->self); 318 if (c->ostate == CHAN_OUTPUT_OPEN) 319 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); 320} 321static void 322chan_write_failed2(Channel *c) 323{ 324 debug("channel %d: write failed", c->self); 325 switch (c->ostate) { 326 case CHAN_OUTPUT_OPEN: 327 chan_shutdown_write(c); /* ?? */ 328 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 329 break; 330 case CHAN_OUTPUT_WAIT_DRAIN: 331 chan_shutdown_write(c); 332 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 333 break; 334 default: 335 error("channel %d: chan_write_failed for ostate %d", 336 c->self, c->ostate); 337 break; 338 } 339} 340static void 341chan_obuf_empty2(Channel *c) 342{ 343 chan_obuf_empty1(c); 344} 345static void 346chan_send_eof2(Channel *c) 347{ 348 debug("channel %d: send eof", c->self); 349 switch (c->istate) { 350 case CHAN_INPUT_WAIT_DRAIN: 351 packet_start(SSH2_MSG_CHANNEL_EOF); 352 packet_put_int(c->remote_id); 353 packet_send(); 354 break; 355 default: 356 error("channel %d: cannot send eof for istate %d", 357 c->self, c->istate); 358 break; 359 } 360} 361static void 362chan_send_close2(Channel *c) 363{ 364 debug("channel %d: send close", c->self); 365 if (c->ostate != CHAN_OUTPUT_CLOSED || 366 c->istate != CHAN_INPUT_CLOSED) { 367 error("channel %d: cannot send close for istate/ostate %d/%d", 368 c->self, c->istate, c->ostate); 369 } else if (c->flags & CHAN_CLOSE_SENT) { 370 error("channel %d: already sent close", c->self); 371 } else { 372 packet_start(SSH2_MSG_CHANNEL_CLOSE); 373 packet_put_int(c->remote_id); 374 packet_send(); 375 c->flags |= CHAN_CLOSE_SENT; 376 } 377} 378 379/* shared */ 380 381void 382chan_mark_dead(Channel *c) 383{ 384 c->type = SSH_CHANNEL_ZOMBIE; 385} 386 387int 388chan_is_dead(Channel *c, int send) 389{ 390 if (c->type == SSH_CHANNEL_ZOMBIE) { 391 debug("channel %d: zombie", c->self); 392 return 1; 393 } 394 if (c->istate != CHAN_INPUT_CLOSED || c->ostate != CHAN_OUTPUT_CLOSED) 395 return 0; 396 if (!compat20) { 397 debug("channel %d: is dead", c->self); 398 return 1; 399 } 400 /* 401 * we have to delay the close message if the efd (for stderr) is 402 * still active 403 */ 404 if (((c->extended_usage != CHAN_EXTENDED_IGNORE) && 405 buffer_len(&c->extended) > 0) 406#if 0 407 || ((c->extended_usage == CHAN_EXTENDED_READ) && 408 c->efd != -1) 409#endif 410 ) { 411 debug2("channel %d: active efd: %d len %d type %s", 412 c->self, c->efd, buffer_len(&c->extended), 413 c->extended_usage==CHAN_EXTENDED_READ ? 414 "read": "write"); 415 } else { 416 if (!(c->flags & CHAN_CLOSE_SENT)) { 417 if (send) { 418 chan_send_close2(c); 419 } else { 420 /* channel would be dead if we sent a close */ 421 if (c->flags & CHAN_CLOSE_RCVD) { 422 debug("channel %d: almost dead", 423 c->self); 424 return 1; 425 } 426 } 427 } 428 if ((c->flags & CHAN_CLOSE_SENT) && 429 (c->flags & CHAN_CLOSE_RCVD)) { 430 debug("channel %d: is dead", c->self); 431 return 1; 432 } 433 } 434 return 0; 435} 436 437void 438chan_init_iostates(Channel *c) 439{ 440 c->ostate = CHAN_OUTPUT_OPEN; 441 c->istate = CHAN_INPUT_OPEN; 442 c->flags = 0; 443} 444 445/* init */ 446void 447chan_init(void) 448{ 449 if (compat20) { 450 chan_rcvd_oclose = chan_rcvd_close2; 451 chan_read_failed = chan_read_failed_12; 452 chan_ibuf_empty = chan_ibuf_empty2; 453 454 chan_rcvd_ieof = chan_rcvd_eof2; 455 chan_write_failed = chan_write_failed2; 456 chan_obuf_empty = chan_obuf_empty2; 457 } else { 458 chan_rcvd_oclose = chan_rcvd_oclose1; 459 chan_read_failed = chan_read_failed_12; 460 chan_ibuf_empty = chan_ibuf_empty1; 461 462 chan_rcvd_ieof = chan_rcvd_ieof1; 463 chan_write_failed = chan_write_failed1; 464 chan_obuf_empty = chan_obuf_empty1; 465 } 466} 467 468/* helper */ 469static void 470chan_shutdown_write(Channel *c) 471{ 472 buffer_clear(&c->output); 473 if (compat20 && c->type == SSH_CHANNEL_LARVAL) 474 return; 475 /* shutdown failure is allowed if write failed already */ 476 debug("channel %d: close_write", c->self); 477 if (c->sock != -1) { 478 if (shutdown(c->sock, SHUT_WR) < 0) 479 debug("channel %d: chan_shutdown_write: " 480 "shutdown() failed for fd%d: %.100s", 481 c->self, c->sock, strerror(errno)); 482 } else { 483 if (channel_close_fd(&c->wfd) < 0) 484 log("channel %d: chan_shutdown_write: " 485 "close() failed for fd%d: %.100s", 486 c->self, c->wfd, strerror(errno)); 487 } 488} 489static void 490chan_shutdown_read(Channel *c) 491{ 492 if (compat20 && c->type == SSH_CHANNEL_LARVAL) 493 return; 494 debug("channel %d: close_read", c->self); 495 if (c->sock != -1) { 496 if (shutdown(c->sock, SHUT_RD) < 0) 497 error("channel %d: chan_shutdown_read: " 498 "shutdown() failed for fd%d [i%d o%d]: %.100s", 499 c->self, c->sock, c->istate, c->ostate, 500 strerror(errno)); 501 } else { 502 if (channel_close_fd(&c->rfd) < 0) 503 log("channel %d: chan_shutdown_read: " 504 "close() failed for fd%d: %.100s", 505 c->self, c->rfd, strerror(errno)); 506 } 507} 508