nchan.c

   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"
  26 RCSID("$OpenBSD: nchan.c,v 1.39 2002/01/14 13:34:07 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) */
  67 chan_event_fn *chan_rcvd_oclose                 = NULL;
  68 chan_event_fn *chan_read_failed                 = NULL;
  69 chan_event_fn *chan_ibuf_empty                  = NULL;
  70 /* events concerning the OUTPUT from channel for socket (ostate) */
  71 chan_event_fn *chan_rcvd_ieof                   = NULL;
  72 chan_event_fn *chan_write_failed                = NULL;
  73 chan_event_fn *chan_obuf_empty                  = NULL;
  74 /*
  75  * ACTIONS: should never update the channel states
  76  */
  77 static void     chan_send_ieof1(Channel *);
  78 static void     chan_send_oclose1(Channel *);
  79 static void     chan_send_close2(Channel *);
  80 static void     chan_send_eof2(Channel *);
  81
  82 /* helper */
  83 static void     chan_shutdown_write(Channel *);
  84 static void     chan_shutdown_read(Channel *);
  85
  86 static char *ostates[] = { "open", "drain", "wait_ieof", "closed" };
  87 static char *istates[] = { "open", "drain", "wait_oclose", "closed" };
  88
  89 static void
  90 chan_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 }
  98 static void
  99 chan_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
 112 static void
 113 chan_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 }
 136 static void
 137 chan_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 }
 151 static void
 152 chan_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 }
 177 static void
 178 chan_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 }
 194 static void
 195 chan_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 }
 215 static void
 216 chan_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 }
 237 static void
 238 chan_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 }
 254 static void
 255 chan_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  */
 276 static void
 277 chan_rcvd_oclose2(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                 break;
 302         case CHAN_INPUT_WAIT_DRAIN:
 303                 chan_send_eof2(c);
 304                 break;
 305         }
 306         chan_set_istate(c, CHAN_INPUT_CLOSED);
 307 }
 308 static void
 309 chan_ibuf_empty2(Channel *c)
 310 {
 311         chan_ibuf_empty1(c);
 312 }
 313 static void
 314 chan_rcvd_ieof2(Channel *c)
 315 {
 316         debug("channel %d: rcvd eof", c->self);
 317         if (c->ostate == CHAN_OUTPUT_OPEN)
 318                 chan_set_ostate(c, CHAN_OUTPUT_WAIT_DRAIN);
 319 }
 320 static void
 321 chan_write_failed2(Channel *c)
 322 {
 323         debug("channel %d: write failed", c->self);
 324         switch (c->ostate) {
 325         case CHAN_OUTPUT_OPEN:
 326                 chan_shutdown_write(c); /* ?? */
 327                 chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
 328                 break;
 329         case CHAN_OUTPUT_WAIT_DRAIN:
 330                 chan_shutdown_write(c);
 331                 chan_set_ostate(c, CHAN_OUTPUT_CLOSED);
 332                 break;
 333         default:
 334                 error("channel %d: chan_write_failed for ostate %d",
 335                     c->self, c->ostate);
 336                 break;
 337         }
 338 }
 339 static void
 340 chan_obuf_empty2(Channel *c)
 341 {
 342         chan_obuf_empty1(c);
 343 }
 344 static void
 345 chan_send_eof2(Channel *c)
 346 {
 347         debug("channel %d: send eof", c->self);
 348         switch (c->istate) {
 349         case CHAN_INPUT_WAIT_DRAIN:
 350                 packet_start(SSH2_MSG_CHANNEL_EOF);
 351                 packet_put_int(c->remote_id);
 352                 packet_send();
 353                 break;
 354         default:
 355                 error("channel %d: cannot send eof for istate %d",
 356                     c->self, c->istate);
 357                 break;
 358         }
 359 }
 360 static void
 361 chan_send_close2(Channel *c)
 362 {
 363         debug("channel %d: send close", c->self);
 364         if (c->ostate != CHAN_OUTPUT_CLOSED ||
 365             c->istate != CHAN_INPUT_CLOSED) {
 366                 error("channel %d: cannot send close for istate/ostate %d/%d",
 367                     c->self, c->istate, c->ostate);
 368         } else if (c->flags & CHAN_CLOSE_SENT) {
 369                 error("channel %d: already sent close", c->self);
 370         } else {
 371                 packet_start(SSH2_MSG_CHANNEL_CLOSE);
 372                 packet_put_int(c->remote_id);
 373                 packet_send();
 374                 c->flags |= CHAN_CLOSE_SENT;
 375         }
 376 }
 377
 378 /* shared */
 379
 380 void
 381 chan_mark_dead(Channel *c)
 382 {
 383         c->type = SSH_CHANNEL_ZOMBIE;
 384 }
 385
 386 int
 387 chan_is_dead(Channel *c, int send)
 388 {
 389         if (c->type == SSH_CHANNEL_ZOMBIE) {
 390                 debug("channel %d: zombie", c->self);
 391                 return 1;
 392         }
 393         if (c->istate != CHAN_INPUT_CLOSED || c->ostate != CHAN_OUTPUT_CLOSED)
 394                 return 0;
 395         if (!compat20) {
 396                 debug("channel %d: is dead", c->self);
 397                 return 1;
 398         }
 399         /*
 400          * we have to delay the close message if the efd (for stderr) is
 401          * still active
 402          */
 403         if (((c->extended_usage != CHAN_EXTENDED_IGNORE) &&
 404             buffer_len(&c->extended) > 0)
 405 #if 0
 406             || ((c->extended_usage == CHAN_EXTENDED_READ) &&
 407             c->efd != -1)
 408 #endif
 409             ) {
 410                 debug2("channel %d: active efd: %d len %d type %s",
 411                     c->self, c->efd, buffer_len(&c->extended),
 412                     c->extended_usage==CHAN_EXTENDED_READ ?
 413                     "read": "write");
 414         } else {
 415                 if (!(c->flags & CHAN_CLOSE_SENT)) {
 416                         if (send) {
 417                                 chan_send_close2(c);
 418                         } else {
 419                                 /* channel would be dead if we sent a close */
 420                                 if (c->flags & CHAN_CLOSE_RCVD) {
 421                                         debug("channel %d: almost dead",
 422                                             c->self);
 423                                         return 1;
 424                                 }
 425                         }
 426                 }
 427                 if ((c->flags & CHAN_CLOSE_SENT) &&
 428                     (c->flags & CHAN_CLOSE_RCVD)) {
 429                         debug("channel %d: is dead", c->self);
 430                         return 1;
 431                 }
 432         }
 433         return 0;
 434 }
 435
 436 void
 437 chan_init_iostates(Channel *c)
 438 {
 439         c->ostate = CHAN_OUTPUT_OPEN;
 440         c->istate = CHAN_INPUT_OPEN;
 441         c->flags = 0;
 442 }
 443
 444 /* init */
 445 void
 446 chan_init(void)
 447 {
 448         if (compat20) {
 449                 chan_rcvd_oclose                = chan_rcvd_oclose2;
 450                 chan_read_failed                = chan_read_failed_12;
 451                 chan_ibuf_empty                 = chan_ibuf_empty2;
 452
 453                 chan_rcvd_ieof                  = chan_rcvd_ieof2;
 454                 chan_write_failed               = chan_write_failed2;
 455                 chan_obuf_empty                 = chan_obuf_empty2;
 456         } else {
 457                 chan_rcvd_oclose                = chan_rcvd_oclose1;
 458                 chan_read_failed                = chan_read_failed_12;
 459                 chan_ibuf_empty                 = chan_ibuf_empty1;
 460
 461                 chan_rcvd_ieof                  = chan_rcvd_ieof1;
 462                 chan_write_failed               = chan_write_failed1;
 463                 chan_obuf_empty                 = chan_obuf_empty1;
 464         }
 465 }
 466
 467 /* helper */
 468 static void
 469 chan_shutdown_write(Channel *c)
 470 {
 471         buffer_clear(&c->output);
 472         if (compat20 && c->type == SSH_CHANNEL_LARVAL)
 473                 return;
 474         /* shutdown failure is allowed if write failed already */
 475         debug("channel %d: close_write", c->self);
 476         if (c->sock != -1) {
 477                 if (shutdown(c->sock, SHUT_WR) < 0)
 478                         debug("channel %d: chan_shutdown_write: "
 479                             "shutdown() failed for fd%d: %.100s",
 480                             c->self, c->sock, strerror(errno));
 481         } else {
 482                 if (channel_close_fd(&c->wfd) < 0)
 483                         log("channel %d: chan_shutdown_write: "
 484                             "close() failed for fd%d: %.100s",
 485                             c->self, c->wfd, strerror(errno));
 486         }
 487 }
 488 static void
 489 chan_shutdown_read(Channel *c)
 490 {
 491         if (compat20 && c->type == SSH_CHANNEL_LARVAL)
 492                 return;
 493         debug("channel %d: close_read", c->self);
 494         if (c->sock != -1) {
 495                 /*
 496                  * shutdown(sock, SHUT_READ) may return ENOTCONN if the
 497                  * write side has been closed already. (bug on Linux)
 498                  * HP-UX may return ENOTCONN also.
 499                  */
 500                 if (shutdown(c->sock, SHUT_RD) < 0
 501                     && errno != ENOTCONN)
 502                         error("channel %d: chan_shutdown_read: "
 503                             "shutdown() failed for fd%d [i%d o%d]: %.100s",
 504                             c->self, c->sock, c->istate, c->ostate,
 505                             strerror(errno));
 506         } else {
 507                 if (channel_close_fd(&c->rfd) < 0)
 508                         log("channel %d: chan_shutdown_read: "
 509                             "close() failed for fd%d: %.100s",
 510                             c->self, c->rfd, strerror(errno));
 511         }
 512 }