nchan.c revision 1.2
1 /* $NetBSD: nchan.c,v 1.2 2009/06/07 22:38:47 christos Exp $ */ 2 /* $OpenBSD: nchan.c,v 1.62 2008/11/07 18:50:18 stevesk Exp $ */ 3 /* 4 * Copyright (c) 1999, 2000, 2001, 2002 Markus Friedl. All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25 */ 26 27 #include "includes.h" 28 __RCSID("$NetBSD: nchan.c,v 1.2 2009/06/07 22:38:47 christos Exp $"); 29 #include <sys/types.h> 30 #include <sys/socket.h> 31 #include <sys/queue.h> 32 33 #include <errno.h> 34 #include <string.h> 35 #include <stdarg.h> 36 37 #include "ssh1.h" 38 #include "ssh2.h" 39 #include "buffer.h" 40 #include "packet.h" 41 #include "channels.h" 42 #include "compat.h" 43 #include "log.h" 44 45 /* 46 * SSH Protocol 1.5 aka New Channel Protocol 47 * Thanks to Martina, Axel and everyone who left Erlangen, leaving me bored. 48 * Written by Markus Friedl in October 1999 49 * 50 * Protocol versions 1.3 and 1.5 differ in the handshake protocol used for the 51 * tear down of channels: 52 * 53 * 1.3: strict request-ack-protocol: 54 * CLOSE -> 55 * <- CLOSE_CONFIRM 56 * 57 * 1.5: uses variations of: 58 * IEOF -> 59 * <- OCLOSE 60 * <- IEOF 61 * OCLOSE -> 62 * i.e. both sides have to close the channel 63 * 64 * 2.0: the EOF messages are optional 65 * 66 * See the debugging output from 'ssh -v' and 'sshd -d' of 67 * ssh-1.2.27 as an example. 68 * 69 */ 70 71 /* functions manipulating channel states */ 72 /* 73 * EVENTS update channel input/output states execute ACTIONS 74 */ 75 /* 76 * ACTIONS: should never update the channel states 77 */ 78 static void chan_send_ieof1(Channel *); 79 static void chan_send_oclose1(Channel *); 80 static void chan_send_close2(Channel *); 81 static void chan_send_eof2(Channel *); 82 static void chan_send_eow2(Channel *); 83 84 /* helper */ 85 static void chan_shutdown_write(Channel *); 86 static void chan_shutdown_read(Channel *); 87 88 static char *ostates[] = { "open", "drain", "wait_ieof", "closed" }; 89 static char *istates[] = { "open", "drain", "wait_oclose", "closed" }; 90 91 static void 92 chan_set_istate(Channel *c, u_int next) 93 { 94 if (c->istate > CHAN_INPUT_CLOSED || next > CHAN_INPUT_CLOSED) 95 fatal("chan_set_istate: bad state %d -> %d", c->istate, next); 96 debug2("channel %d: input %s -> %s", c->self, istates[c->istate], 97 istates[next]); 98 c->istate = next; 99 } 100 static void 101 chan_set_ostate(Channel *c, u_int next) 102 { 103 if (c->ostate > CHAN_OUTPUT_CLOSED || next > CHAN_OUTPUT_CLOSED) 104 fatal("chan_set_ostate: bad state %d -> %d", c->ostate, next); 105 debug2("channel %d: output %s -> %s", c->self, ostates[c->ostate], 106 ostates[next]); 107 c->ostate = next; 108 } 109 110 /* 111 * SSH1 specific implementation of event functions 112 */ 113 114 static void 115 chan_rcvd_oclose1(Channel *c) 116 { 117 debug2("channel %d: rcvd oclose", c->self); 118 switch (c->istate) { 119 case CHAN_INPUT_WAIT_OCLOSE: 120 chan_set_istate(c, CHAN_INPUT_CLOSED); 121 break; 122 case CHAN_INPUT_OPEN: 123 chan_shutdown_read(c); 124 chan_send_ieof1(c); 125 chan_set_istate(c, CHAN_INPUT_CLOSED); 126 break; 127 case CHAN_INPUT_WAIT_DRAIN: 128 /* both local read_failed and remote write_failed */ 129 chan_send_ieof1(c); 130 chan_set_istate(c, CHAN_INPUT_CLOSED); 131 break; 132 default: 133 error("channel %d: protocol error: rcvd_oclose for istate %d", 134 c->self, c->istate); 135 return; 136 } 137 } 138 void 139 chan_read_failed(Channel *c) 140 { 141 debug2("channel %d: read failed", c->self); 142 switch (c->istate) { 143 case CHAN_INPUT_OPEN: 144 chan_shutdown_read(c); 145 chan_set_istate(c, CHAN_INPUT_WAIT_DRAIN); 146 break; 147 default: 148 error("channel %d: chan_read_failed for istate %d", 149 c->self, c->istate); 150 break; 151 } 152 } 153 void 154 chan_ibuf_empty(Channel *c) 155 { 156 debug2("channel %d: ibuf empty", c->self); 157 if (buffer_len(&c->input)) { 158 error("channel %d: chan_ibuf_empty for non empty buffer", 159 c->self); 160 return; 161 } 162 switch (c->istate) { 163 case CHAN_INPUT_WAIT_DRAIN: 164 if (compat20) { 165 if (!(c->flags & CHAN_CLOSE_SENT)) 166 chan_send_eof2(c); 167 chan_set_istate(c, CHAN_INPUT_CLOSED); 168 } else { 169 chan_send_ieof1(c); 170 chan_set_istate(c, CHAN_INPUT_WAIT_OCLOSE); 171 } 172 break; 173 default: 174 error("channel %d: chan_ibuf_empty for istate %d", 175 c->self, c->istate); 176 break; 177 } 178 } 179 static void 180 chan_rcvd_ieof1(Channel *c) 181 { 182 debug2("channel %d: rcvd ieof", c->self); 183 switch (c->ostate) { 184 case CHAN_OUTPUT_OPEN: 185 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); 186 break; 187 case CHAN_OUTPUT_WAIT_IEOF: 188 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 189 break; 190 default: 191 error("channel %d: protocol error: rcvd_ieof for ostate %d", 192 c->self, c->ostate); 193 break; 194 } 195 } 196 static void 197 chan_write_failed1(Channel *c) 198 { 199 debug2("channel %d: write failed", c->self); 200 switch (c->ostate) { 201 case CHAN_OUTPUT_OPEN: 202 chan_shutdown_write(c); 203 chan_send_oclose1(c); 204 chan_set_ostate(c, CHAN_OUTPUT_WAIT_IEOF); 205 break; 206 case CHAN_OUTPUT_WAIT_DRAIN: 207 chan_shutdown_write(c); 208 chan_send_oclose1(c); 209 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 210 break; 211 default: 212 error("channel %d: chan_write_failed for ostate %d", 213 c->self, c->ostate); 214 break; 215 } 216 } 217 void 218 chan_obuf_empty(Channel *c) 219 { 220 debug2("channel %d: obuf empty", c->self); 221 if (buffer_len(&c->output)) { 222 error("channel %d: chan_obuf_empty for non empty buffer", 223 c->self); 224 return; 225 } 226 switch (c->ostate) { 227 case CHAN_OUTPUT_WAIT_DRAIN: 228 chan_shutdown_write(c); 229 if (!compat20) 230 chan_send_oclose1(c); 231 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 232 break; 233 default: 234 error("channel %d: internal error: obuf_empty for ostate %d", 235 c->self, c->ostate); 236 break; 237 } 238 } 239 static void 240 chan_send_ieof1(Channel *c) 241 { 242 debug2("channel %d: send ieof", c->self); 243 switch (c->istate) { 244 case CHAN_INPUT_OPEN: 245 case CHAN_INPUT_WAIT_DRAIN: 246 packet_start(SSH_MSG_CHANNEL_INPUT_EOF); 247 packet_put_int(c->remote_id); 248 packet_send(); 249 break; 250 default: 251 error("channel %d: cannot send ieof for istate %d", 252 c->self, c->istate); 253 break; 254 } 255 } 256 static void 257 chan_send_oclose1(Channel *c) 258 { 259 debug2("channel %d: send oclose", c->self); 260 switch (c->ostate) { 261 case CHAN_OUTPUT_OPEN: 262 case CHAN_OUTPUT_WAIT_DRAIN: 263 buffer_clear(&c->output); 264 packet_start(SSH_MSG_CHANNEL_OUTPUT_CLOSE); 265 packet_put_int(c->remote_id); 266 packet_send(); 267 break; 268 default: 269 error("channel %d: cannot send oclose for ostate %d", 270 c->self, c->ostate); 271 break; 272 } 273 } 274 275 /* 276 * the same for SSH2 277 */ 278 static void 279 chan_rcvd_close2(Channel *c) 280 { 281 debug2("channel %d: rcvd close", c->self); 282 if (c->flags & CHAN_CLOSE_RCVD) 283 error("channel %d: protocol error: close rcvd twice", c->self); 284 c->flags |= CHAN_CLOSE_RCVD; 285 if (c->type == SSH_CHANNEL_LARVAL) { 286 /* tear down larval channels immediately */ 287 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 288 chan_set_istate(c, CHAN_INPUT_CLOSED); 289 return; 290 } 291 switch (c->ostate) { 292 case CHAN_OUTPUT_OPEN: 293 /* 294 * wait until a data from the channel is consumed if a CLOSE 295 * is received 296 */ 297 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); 298 break; 299 } 300 switch (c->istate) { 301 case CHAN_INPUT_OPEN: 302 chan_shutdown_read(c); 303 chan_set_istate(c, CHAN_INPUT_CLOSED); 304 break; 305 case CHAN_INPUT_WAIT_DRAIN: 306 chan_send_eof2(c); 307 chan_set_istate(c, CHAN_INPUT_CLOSED); 308 break; 309 } 310 } 311 void 312 chan_rcvd_eow(Channel *c) 313 { 314 debug2("channel %d: rcvd eow", c->self); 315 switch (c->istate) { 316 case CHAN_INPUT_OPEN: 317 chan_shutdown_read(c); 318 chan_set_istate(c, CHAN_INPUT_CLOSED); 319 break; 320 } 321 } 322 static void 323 chan_rcvd_eof2(Channel *c) 324 { 325 debug2("channel %d: rcvd eof", c->self); 326 c->flags |= CHAN_EOF_RCVD; 327 if (c->ostate == CHAN_OUTPUT_OPEN) 328 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN); 329 } 330 static void 331 chan_write_failed2(Channel *c) 332 { 333 debug2("channel %d: write failed", c->self); 334 switch (c->ostate) { 335 case CHAN_OUTPUT_OPEN: 336 case CHAN_OUTPUT_WAIT_DRAIN: 337 chan_shutdown_write(c); 338 if (strcmp(c->ctype, "session") == 0) 339 chan_send_eow2(c); 340 chan_set_ostate(c, CHAN_OUTPUT_CLOSED); 341 break; 342 default: 343 error("channel %d: chan_write_failed for ostate %d", 344 c->self, c->ostate); 345 break; 346 } 347 } 348 static void 349 chan_send_eof2(Channel *c) 350 { 351 debug2("channel %d: send eof", c->self); 352 switch (c->istate) { 353 case CHAN_INPUT_WAIT_DRAIN: 354 packet_start(SSH2_MSG_CHANNEL_EOF); 355 packet_put_int(c->remote_id); 356 packet_send(); 357 c->flags |= CHAN_EOF_SENT; 358 break; 359 default: 360 error("channel %d: cannot send eof for istate %d", 361 c->self, c->istate); 362 break; 363 } 364 } 365 static void 366 chan_send_close2(Channel *c) 367 { 368 debug2("channel %d: send close", c->self); 369 if (c->ostate != CHAN_OUTPUT_CLOSED || 370 c->istate != CHAN_INPUT_CLOSED) { 371 error("channel %d: cannot send close for istate/ostate %d/%d", 372 c->self, c->istate, c->ostate); 373 } else if (c->flags & CHAN_CLOSE_SENT) { 374 error("channel %d: already sent close", c->self); 375 } else { 376 packet_start(SSH2_MSG_CHANNEL_CLOSE); 377 packet_put_int(c->remote_id); 378 packet_send(); 379 c->flags |= CHAN_CLOSE_SENT; 380 } 381 } 382 static void 383 chan_send_eow2(Channel *c) 384 { 385 debug2("channel %d: send eow", c->self); 386 if (c->ostate == CHAN_OUTPUT_CLOSED) { 387 error("channel %d: must not sent eow on closed output", 388 c->self); 389 return; 390 } 391 if (!(datafellows & SSH_NEW_OPENSSH)) 392 return; 393 packet_start(SSH2_MSG_CHANNEL_REQUEST); 394 packet_put_int(c->remote_id); 395 packet_put_cstring("eow (at) openssh.com"); 396 packet_put_char(0); 397 packet_send(); 398 } 399 400 /* shared */ 401 402 void 403 chan_rcvd_ieof(Channel *c) 404 { 405 if (compat20) 406 chan_rcvd_eof2(c); 407 else 408 chan_rcvd_ieof1(c); 409 if (c->ostate == CHAN_OUTPUT_WAIT_DRAIN && 410 buffer_len(&c->output) == 0 && 411 !CHANNEL_EFD_OUTPUT_ACTIVE(c)) 412 chan_obuf_empty(c); 413 } 414 void 415 chan_rcvd_oclose(Channel *c) 416 { 417 if (compat20) 418 chan_rcvd_close2(c); 419 else 420 chan_rcvd_oclose1(c); 421 } 422 void 423 chan_write_failed(Channel *c) 424 { 425 if (compat20) 426 chan_write_failed2(c); 427 else 428 chan_write_failed1(c); 429 } 430 431 void 432 chan_mark_dead(Channel *c) 433 { 434 c->type = SSH_CHANNEL_ZOMBIE; 435 } 436 437 int 438 chan_is_dead(Channel *c, int do_send) 439 { 440 if (c->type == SSH_CHANNEL_ZOMBIE) { 441 debug2("channel %d: zombie", c->self); 442 return 1; 443 } 444 if (c->istate != CHAN_INPUT_CLOSED || c->ostate != CHAN_OUTPUT_CLOSED) 445 return 0; 446 if (!compat20) { 447 debug2("channel %d: is dead", c->self); 448 return 1; 449 } 450 if ((datafellows & SSH_BUG_EXTEOF) && 451 c->extended_usage == CHAN_EXTENDED_WRITE && 452 c->efd != -1 && 453 buffer_len(&c->extended) > 0) { 454 debug2("channel %d: active efd: %d len %d", 455 c->self, c->efd, buffer_len(&c->extended)); 456 return 0; 457 } 458 if (!(c->flags & CHAN_CLOSE_SENT)) { 459 if (do_send) { 460 chan_send_close2(c); 461 } else { 462 /* channel would be dead if we sent a close */ 463 if (c->flags & CHAN_CLOSE_RCVD) { 464 debug2("channel %d: almost dead", 465 c->self); 466 return 1; 467 } 468 } 469 } 470 if ((c->flags & CHAN_CLOSE_SENT) && 471 (c->flags & CHAN_CLOSE_RCVD)) { 472 debug2("channel %d: is dead", c->self); 473 return 1; 474 } 475 return 0; 476 } 477 478 /* helper */ 479 static void 480 chan_shutdown_write(Channel *c) 481 { 482 buffer_clear(&c->output); 483 if (compat20 && c->type == SSH_CHANNEL_LARVAL) 484 return; 485 /* shutdown failure is allowed if write failed already */ 486 debug2("channel %d: close_write", c->self); 487 if (c->sock != -1) { 488 if (shutdown(c->sock, SHUT_WR) < 0) 489 debug2("channel %d: chan_shutdown_write: " 490 "shutdown() failed for fd %d: %.100s", 491 c->self, c->sock, strerror(errno)); 492 } else { 493 if (channel_close_fd(&c->wfd) < 0) 494 logit("channel %d: chan_shutdown_write: " 495 "close() failed for fd %d: %.100s", 496 c->self, c->wfd, strerror(errno)); 497 } 498 } 499 static void 500 chan_shutdown_read(Channel *c) 501 { 502 if (compat20 && c->type == SSH_CHANNEL_LARVAL) 503 return; 504 debug2("channel %d: close_read", c->self); 505 if (c->sock != -1) { 506 if (shutdown(c->sock, SHUT_RD) < 0) 507 error("channel %d: chan_shutdown_read: " 508 "shutdown() failed for fd %d [i%d o%d]: %.100s", 509 c->self, c->sock, c->istate, c->ostate, 510 strerror(errno)); 511 } else { 512 if (channel_close_fd(&c->rfd) < 0) 513 logit("channel %d: chan_shutdown_read: " 514 "close() failed for fd %d: %.100s", 515 c->self, c->rfd, strerror(errno)); 516 } 517 } 518
Indexes created Thu Apr 23 00:23:13 UTC 2026