ssl/statem/statem.c

   1 /* ssl/statem/statem.c */
   2 /*
   3  * Written by Matt Caswell for the OpenSSL project.
   4  */
   5 /* ====================================================================
   6  * Copyright (c) 1998-2015 The OpenSSL Project.  All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  *
  12  * 1. Redistributions of source code must retain the above copyright
  13  *    notice, this list of conditions and the following disclaimer.
  14  *
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in
  17  *    the documentation and/or other materials provided with the
  18  *    distribution.
  19  *
  20  * 3. All advertising materials mentioning features or use of this
  21  *    software must display the following acknowledgment:
  22  *    "This product includes software developed by the OpenSSL Project
  23  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
  24  *
  25  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  26  *    endorse or promote products derived from this software without
  27  *    prior written permission. For written permission, please contact
  28  *    openssl-core@openssl.org.
  29  *
  30  * 5. Products derived from this software may not be called "OpenSSL"
  31  *    nor may "OpenSSL" appear in their names without prior written
  32  *    permission of the OpenSSL Project.
  33  *
  34  * 6. Redistributions of any form whatsoever must retain the following
  35  *    acknowledgment:
  36  *    "This product includes software developed by the OpenSSL Project
  37  *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
  38  *
  39  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  40  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  41  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  42  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  43  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  44  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  45  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  46  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  48  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  49  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  50  * OF THE POSSIBILITY OF SUCH DAMAGE.
  51  * ====================================================================
  52  *
  53  * This product includes cryptographic software written by Eric Young
  54  * (eay@cryptsoft.com).  This product includes software written by Tim
  55  * Hudson (tjh@cryptsoft.com).
  56  *
  57  */
  58
  59 #include <openssl/rand.h>
  60 #include "../ssl_locl.h"
  61 #include "statem_locl.h"
  62
  63 /*
  64  * This file implements the SSL/TLS/DTLS state machines.
  65  *
  66  * There are two primary state machines:
  67  *
  68  * 1) Message flow state machine
  69  * 2) Handshake state machine
  70  *
  71  * The Message flow state machine controls the reading and sending of messages
  72  * including handling of non-blocking IO events, flushing of the underlying
  73  * write BIO, handling unexpected messages, etc. It is itself broken into two
  74  * separate sub-state machines which control reading and writing respectively.
  75  *
  76  * The Handshake state machine keeps track of the current SSL/TLS handshake
  77  * state. Transitions of the handshake state are the result of events that
  78  * occur within the Message flow state machine.
  79  *
  80  * Overall it looks like this:
  81  *
  82  * ---------------------------------------------            -------------------
  83  * |                                           |            |                 |
  84  * | Message flow state machine                |            |                 |
  85  * |                                           |            |                 |
  86  * | -------------------- -------------------- | Transition | Handshake state |
  87  * | | MSG_FLOW_READING | | MSG_FLOW_WRITING | | Event      | machine         |
  88  * | | sub-state        | | sub-state        | |----------->|                 |
  89  * | | machine for      | | machine for      | |            |                 |
  90  * | | reading messages | | writing messages | |            |                 |
  91  * | -------------------- -------------------- |            |                 |
  92  * |                                           |            |                 |
  93  * ---------------------------------------------            -------------------
  94  *
  95  */
  96
  97 /* Sub state machine return values */
  98 enum SUB_STATE_RETURN {
  99     /* Something bad happened or NBIO */
 100     SUB_STATE_ERROR,
 101     /* Sub state finished go to the next sub state */
 102     SUB_STATE_FINISHED,
 103     /* Sub state finished and handshake was completed */
 104     SUB_STATE_END_HANDSHAKE
 105 };
 106
 107 static int state_machine(SSL *s, int server);
 108 static void init_read_state_machine(SSL *s);
 109 static enum SUB_STATE_RETURN read_state_machine(SSL *s);
 110 static void init_write_state_machine(SSL *s);
 111 static enum SUB_STATE_RETURN write_state_machine(SSL *s);
 112
 113 OSSL_HANDSHAKE_STATE SSL_get_state(const SSL *ssl)
 114 {
 115     return ssl->statem.hand_state;
 116 }
 117
 118 int SSL_in_init(SSL *s)
 119 {
 120     return s->statem.in_init;
 121 }
 122
 123 int SSL_is_init_finished(SSL *s)
 124 {
 125     return !(s->statem.in_init) && (s->statem.hand_state == TLS_ST_OK);
 126 }
 127
 128 int SSL_in_before(SSL *s)
 129 {
 130     /*
 131      * Historically being "in before" meant before anything had happened. In the
 132      * current code though we remain in the "before" state for a while after we
 133      * have started the handshake process (e.g. as a server waiting for the
 134      * first message to arrive). There "in before" is taken to mean "in before"
 135      * and not started any handshake process yet.
 136      */
 137     return (s->statem.hand_state == TLS_ST_BEFORE)
 138         && (s->statem.state == MSG_FLOW_UNINITED);
 139 }
 140
 141 /*
 142  * Clear the state machine state and reset back to MSG_FLOW_UNINITED
 143  */
 144 void ossl_statem_clear(SSL *s)
 145 {
 146     s->statem.state = MSG_FLOW_UNINITED;
 147     s->statem.hand_state = TLS_ST_BEFORE;
 148     s->statem.in_init = 1;
 149     s->statem.no_cert_verify = 0;
 150 }
 151
 152 /*
 153  * Set the state machine up ready for a renegotiation handshake
 154  */
 155 void ossl_statem_set_renegotiate(SSL *s)
 156 {
 157     s->statem.state = MSG_FLOW_RENEGOTIATE;
 158     s->statem.in_init = 1;
 159 }
 160
 161 /*
 162  * Put the state machine into an error state. This is a permanent error for
 163  * the current connection.
 164  */
 165 void ossl_statem_set_error(SSL *s)
 166 {
 167     s->statem.state = MSG_FLOW_ERROR;
 168 }
 169
 170 /*
 171  * Discover whether the current connection is in the error state.
 172  *
 173  * Valid return values are:
 174  *   1: Yes
 175  *   0: No
 176  */
 177 int ossl_statem_in_error(const SSL *s)
 178 {
 179     if (s->statem.state == MSG_FLOW_ERROR)
 180         return 1;
 181
 182     return 0;
 183 }
 184
 185 void ossl_statem_set_in_init(SSL *s, int init)
 186 {
 187     s->statem.in_init = init;
 188 }
 189
 190 int ossl_statem_connect(SSL *s) {
 191     return state_machine(s, 0);
 192 }
 193
 194 int ossl_statem_accept(SSL *s)
 195 {
 196     return state_machine(s, 1);
 197 }
 198
 199 /*
 200  * The main message flow state machine. We start in the MSG_FLOW_UNINITED or
 201  * MSG_FLOW_RENEGOTIATE state and finish in MSG_FLOW_FINISHED. Valid states and
 202  * transitions are as follows:
 203  *
 204  * MSG_FLOW_UNINITED     MSG_FLOW_RENEGOTIATE
 205  *        |                       |
 206  *        +-----------------------+
 207  *        v
 208  * MSG_FLOW_WRITING <---> MSG_FLOW_READING
 209  *        |
 210  *        V
 211  * MSG_FLOW_FINISHED
 212  *        |
 213  *        V
 214  *    [SUCCESS]
 215  *
 216  * We may exit at any point due to an error or NBIO event. If an NBIO event
 217  * occurs then we restart at the point we left off when we are recalled.
 218  * MSG_FLOW_WRITING and MSG_FLOW_READING have sub-state machines associated with them.
 219  *
 220  * In addition to the above there is also the MSG_FLOW_ERROR state. We can move
 221  * into that state at any point in the event that an irrecoverable error occurs.
 222  *
 223  * Valid return values are:
 224  *   1: Success
 225  * <=0: NBIO or error
 226  */
 227 static int state_machine(SSL *s, int server) {
 228     BUF_MEM *buf = NULL;
 229     unsigned long Time = (unsigned long)time(NULL);
 230     void (*cb) (const SSL *ssl, int type, int val) = NULL;
 231     OSSL_STATEM *st = &s->statem;
 232     int ret = -1;
 233     int ssret;
 234
 235     if (st->state == MSG_FLOW_ERROR) {
 236         /* Shouldn't have been called if we're already in the error state */
 237         return -1;
 238     }
 239
 240     RAND_add(&Time, sizeof(Time), 0);
 241     ERR_clear_error();
 242     clear_sys_error();
 243
 244     if (s->info_callback != NULL)
 245         cb = s->info_callback;
 246     else if (s->ctx->info_callback != NULL)
 247         cb = s->ctx->info_callback;
 248
 249     s->in_handshake++;
 250     if (!SSL_in_init(s) || SSL_in_before(s)) {
 251         if (!SSL_clear(s))
 252             return -1;
 253     }
 254
 255 #ifndef OPENSSL_NO_SCTP
 256     if (SSL_IS_DTLS(s)) {
 257         /*
 258          * Notify SCTP BIO socket to enter handshake mode and prevent stream
 259          * identifier other than 0. Will be ignored if no SCTP is used.
 260          */
 261         BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
 262                  s->in_handshake, NULL);
 263     }
 264 #endif
 265
 266 #ifndef OPENSSL_NO_HEARTBEATS
 267     /*
 268      * If we're awaiting a HeartbeatResponse, pretend we already got and
 269      * don't await it anymore, because Heartbeats don't make sense during
 270      * handshakes anyway.
 271      */
 272     if (s->tlsext_hb_pending) {
 273         if (SSL_IS_DTLS(s))
 274             dtls1_stop_timer(s);
 275         s->tlsext_hb_pending = 0;
 276         s->tlsext_hb_seq++;
 277     }
 278 #endif
 279
 280     /* Initialise state machine */
 281
 282     if (st->state == MSG_FLOW_RENEGOTIATE) {
 283         s->renegotiate = 1;
 284         if (!server)
 285             s->ctx->stats.sess_connect_renegotiate++;
 286     }
 287
 288     if (st->state == MSG_FLOW_UNINITED || st->state == MSG_FLOW_RENEGOTIATE) {
 289         if (st->state == MSG_FLOW_UNINITED) {
 290             st->hand_state = TLS_ST_BEFORE;
 291         }
 292
 293         s->server = server;
 294         if (cb != NULL)
 295             cb(s, SSL_CB_HANDSHAKE_START, 1);
 296
 297         if (SSL_IS_DTLS(s)) {
 298             if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00) &&
 299                     (server
 300                     || (s->version & 0xff00) != (DTLS1_BAD_VER & 0xff00))) {
 301                 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 302                 goto end;
 303             }
 304         } else {
 305             if ((s->version >> 8) != SSL3_VERSION_MAJOR
 306                     && s->version != TLS_ANY_VERSION) {
 307                 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 308                 goto end;
 309             }
 310         }
 311
 312         if (!SSL_IS_DTLS(s)) {
 313             if (s->version != TLS_ANY_VERSION &&
 314                     !ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL)) {
 315                 SSLerr(SSL_F_STATE_MACHINE, SSL_R_VERSION_TOO_LOW);
 316                 goto end;
 317             }
 318         }
 319
 320         if (s->init_buf == NULL) {
 321             if ((buf = BUF_MEM_new()) == NULL) {
 322                 goto end;
 323             }
 324             if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {
 325                 goto end;
 326             }
 327             s->init_buf = buf;
 328             buf = NULL;
 329         }
 330
 331         if (!ssl3_setup_buffers(s)) {
 332             goto end;
 333         }
 334         s->init_num = 0;
 335
 336         /*
 337          * Should have been reset by tls_process_finished, too.
 338          */
 339         s->s3->change_cipher_spec = 0;
 340
 341         if (!server || st->state != MSG_FLOW_RENEGOTIATE) {
 342                 /*
 343                  * Ok, we now need to push on a buffering BIO ...but not with
 344                  * SCTP
 345                  */
 346 #ifndef OPENSSL_NO_SCTP
 347                 if (!SSL_IS_DTLS(s) || !BIO_dgram_is_sctp(SSL_get_wbio(s)))
 348 #endif
 349                     if (!ssl_init_wbio_buffer(s, server ? 1 : 0)) {
 350                         goto end;
 351                     }
 352
 353             ssl3_init_finished_mac(s);
 354         }
 355
 356         if (server) {
 357             if (st->state != MSG_FLOW_RENEGOTIATE) {
 358                 s->ctx->stats.sess_accept++;
 359             } else if (!s->s3->send_connection_binding &&
 360                        !(s->options &
 361                          SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)) {
 362                 /*
 363                  * Server attempting to renegotiate with client that doesn't
 364                  * support secure renegotiation.
 365                  */
 366                 SSLerr(SSL_F_STATE_MACHINE,
 367                        SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
 368                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
 369                 ossl_statem_set_error(s);
 370                 goto end;
 371             } else {
 372                 /*
 373                  * st->state == MSG_FLOW_RENEGOTIATE, we will just send a
 374                  * HelloRequest
 375                  */
 376                 s->ctx->stats.sess_accept_renegotiate++;
 377             }
 378         } else {
 379             s->ctx->stats.sess_connect++;
 380
 381             /* mark client_random uninitialized */
 382             memset(s->s3->client_random, 0, sizeof(s->s3->client_random));
 383             s->hit = 0;
 384
 385             s->s3->tmp.cert_request = 0;
 386
 387             if (SSL_IS_DTLS(s)) {
 388                 st->use_timer = 1;
 389             }
 390         }
 391
 392         st->state = MSG_FLOW_WRITING;
 393         init_write_state_machine(s);
 394         st->read_state_first_init = 1;
 395     }
 396
 397     while(st->state != MSG_FLOW_FINISHED) {
 398         if(st->state == MSG_FLOW_READING) {
 399             ssret = read_state_machine(s);
 400             if (ssret == SUB_STATE_FINISHED) {
 401                 st->state = MSG_FLOW_WRITING;
 402                 init_write_state_machine(s);
 403             } else {
 404                 /* NBIO or error */
 405                 goto end;
 406             }
 407         } else if (st->state == MSG_FLOW_WRITING) {
 408             ssret = write_state_machine(s);
 409             if (ssret == SUB_STATE_FINISHED) {
 410                 st->state = MSG_FLOW_READING;
 411                 init_read_state_machine(s);
 412             } else if (ssret == SUB_STATE_END_HANDSHAKE) {
 413                 st->state = MSG_FLOW_FINISHED;
 414             } else {
 415                 /* NBIO or error */
 416                 goto end;
 417             }
 418         } else {
 419             /* Error */
 420             ossl_statem_set_error(s);
 421             goto end;
 422         }
 423     }
 424
 425     st->state = MSG_FLOW_UNINITED;
 426     ret = 1;
 427
 428  end:
 429     s->in_handshake--;
 430
 431 #ifndef OPENSSL_NO_SCTP
 432     if (SSL_IS_DTLS(s)) {
 433         /*
 434          * Notify SCTP BIO socket to leave handshake mode and allow stream
 435          * identifier other than 0. Will be ignored if no SCTP is used.
 436          */
 437         BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
 438                  s->in_handshake, NULL);
 439     }
 440 #endif
 441
 442     BUF_MEM_free(buf);
 443     if (cb != NULL) {
 444         if (server)
 445             cb(s, SSL_CB_ACCEPT_EXIT, ret);
 446         else
 447             cb(s, SSL_CB_CONNECT_EXIT, ret);
 448     }
 449     return ret;
 450 }
 451
 452 /*
 453  * Initialise the MSG_FLOW_READING sub-state machine
 454  */
 455 static void init_read_state_machine(SSL *s)
 456 {
 457     OSSL_STATEM *st = &s->statem;
 458
 459     st->read_state = READ_STATE_HEADER;
 460 }
 461
 462 /*
 463  * This function implements the sub-state machine when the message flow is in
 464  * MSG_FLOW_READING. The valid sub-states and transitions are:
 465  *
 466  * READ_STATE_HEADER <--+<-------------+
 467  *        |             |              |
 468  *        v             |              |
 469  * READ_STATE_BODY -----+-->READ_STATE_POST_PROCESS
 470  *        |                            |
 471  *        +----------------------------+
 472  *        v
 473  * [SUB_STATE_FINISHED]
 474  *
 475  * READ_STATE_HEADER has the responsibility for reading in the message header
 476  * and transitioning the state of the handshake state machine.
 477  *
 478  * READ_STATE_BODY reads in the rest of the message and then subsequently
 479  * processes it.
 480  *
 481  * READ_STATE_POST_PROCESS is an optional step that may occur if some post
 482  * processing activity performed on the message may block.
 483  *
 484  * Any of the above states could result in an NBIO event occuring in which case
 485  * control returns to the calling application. When this function is recalled we
 486  * will resume in the same state where we left off.
 487  */
 488 static enum SUB_STATE_RETURN read_state_machine(SSL *s) {
 489     OSSL_STATEM *st = &s->statem;
 490     int ret, mt;
 491     unsigned long len;
 492     int (*transition)(SSL *s, int mt);
 493     PACKET pkt;
 494     enum MSG_PROCESS_RETURN (*process_message)(SSL *s, PACKET *pkt);
 495     enum WORK_STATE (*post_process_message)(SSL *s, enum WORK_STATE wst);
 496     unsigned long (*max_message_size)(SSL *s);
 497     void (*cb) (const SSL *ssl, int type, int val) = NULL;
 498
 499     if (s->info_callback != NULL)
 500         cb = s->info_callback;
 501     else if (s->ctx->info_callback != NULL)
 502         cb = s->ctx->info_callback;
 503
 504     if(s->server) {
 505         transition = server_read_transition;
 506         process_message = server_process_message;
 507         max_message_size = server_max_message_size;
 508         post_process_message = server_post_process_message;
 509     } else {
 510         transition = client_read_transition;
 511         process_message = client_process_message;
 512         max_message_size = client_max_message_size;
 513         post_process_message = client_post_process_message;
 514     }
 515
 516     if (st->read_state_first_init) {
 517         s->first_packet = 1;
 518         st->read_state_first_init = 0;
 519     }
 520
 521     while(1) {
 522         switch(st->read_state) {
 523         case READ_STATE_HEADER:
 524             s->init_num = 0;
 525             /* Get the state the peer wants to move to */
 526             if (SSL_IS_DTLS(s)) {
 527                 /*
 528                  * In DTLS we get the whole message in one go - header and body
 529                  */
 530                 ret = dtls_get_message(s, &mt, &len);
 531             } else {
 532                 ret = tls_get_message_header(s, &mt);
 533             }
 534
 535             if (ret == 0) {
 536                 /* Could be non-blocking IO */
 537                 return SUB_STATE_ERROR;
 538             }
 539
 540             if (cb != NULL) {
 541                 /* Notify callback of an impending state change */
 542                 if (s->server)
 543                     cb(s, SSL_CB_ACCEPT_LOOP, 1);
 544                 else
 545                     cb(s, SSL_CB_CONNECT_LOOP, 1);
 546             }
 547             /*
 548              * Validate that we are allowed to move to the new state and move
 549              * to that state if so
 550              */
 551             if(!transition(s, mt)) {
 552                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL3_AD_UNEXPECTED_MESSAGE);
 553                 SSLerr(SSL_F_READ_STATE_MACHINE, SSL_R_UNEXPECTED_MESSAGE);
 554                 return SUB_STATE_ERROR;
 555             }
 556
 557             if (s->s3->tmp.message_size > max_message_size(s)) {
 558                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
 559                 SSLerr(SSL_F_READ_STATE_MACHINE, SSL_R_EXCESSIVE_MESSAGE_SIZE);
 560                 return SUB_STATE_ERROR;
 561             }
 562
 563             st->read_state = READ_STATE_BODY;
 564             /* Fall through */
 565
 566         case READ_STATE_BODY:
 567             if (!SSL_IS_DTLS(s)) {
 568                 /* We already got this above for DTLS */
 569                 ret = tls_get_message_body(s, &len);
 570                 if (ret == 0) {
 571                     /* Could be non-blocking IO */
 572                     return SUB_STATE_ERROR;
 573                 }
 574             }
 575
 576             s->first_packet = 0;
 577             if (!PACKET_buf_init(&pkt, s->init_msg, len)) {
 578                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
 579                 SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 580                 return SUB_STATE_ERROR;
 581             }
 582             ret = process_message(s, &pkt);
 583             if (ret == MSG_PROCESS_ERROR) {
 584                 return SUB_STATE_ERROR;
 585             }
 586
 587             if (ret == MSG_PROCESS_FINISHED_READING) {
 588                 if (SSL_IS_DTLS(s)) {
 589                     dtls1_stop_timer(s);
 590                 }
 591                 return SUB_STATE_FINISHED;
 592             }
 593
 594             if (ret == MSG_PROCESS_CONTINUE_PROCESSING) {
 595                 st->read_state = READ_STATE_POST_PROCESS;
 596                 st->read_state_work = WORK_MORE_A;
 597             } else {
 598                 st->read_state = READ_STATE_HEADER;
 599             }
 600             break;
 601
 602         case READ_STATE_POST_PROCESS:
 603             st->read_state_work = post_process_message(s, st->read_state_work);
 604             switch(st->read_state_work) {
 605             default:
 606                 return SUB_STATE_ERROR;
 607
 608             case WORK_FINISHED_CONTINUE:
 609                 st->read_state = READ_STATE_HEADER;
 610                 break;
 611
 612             case WORK_FINISHED_STOP:
 613                 if (SSL_IS_DTLS(s)) {
 614                     dtls1_stop_timer(s);
 615                 }
 616                 return SUB_STATE_FINISHED;
 617             }
 618             break;
 619
 620         default:
 621             /* Shouldn't happen */
 622             ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
 623             SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 624             ossl_statem_set_error(s);
 625             return SUB_STATE_ERROR;
 626         }
 627     }
 628 }
 629
 630 /*
 631  * Send a previously constructed message to the peer.
 632  */
 633 static int statem_do_write(SSL *s)
 634 {
 635     OSSL_STATEM *st = &s->statem;
 636
 637     if (st->hand_state == TLS_ST_CW_CHANGE
 638             || st->hand_state == TLS_ST_SW_CHANGE) {
 639         if (SSL_IS_DTLS(s))
 640             return dtls1_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
 641         else
 642             return ssl3_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
 643     } else {
 644         return ssl_do_write(s);
 645     }
 646 }
 647
 648 /*
 649  * Initialise the MSG_FLOW_WRITING sub-state machine
 650  */
 651 static void init_write_state_machine(SSL *s)
 652 {
 653     OSSL_STATEM *st = &s->statem;
 654
 655     st->write_state = WRITE_STATE_TRANSITION;
 656 }
 657
 658 /*
 659  * This function implements the sub-state machine when the message flow is in
 660  * MSG_FLOW_WRITING. The valid sub-states and transitions are:
 661  *
 662  * +-> WRITE_STATE_TRANSITION ------> [SUB_STATE_FINISHED]
 663  * |             |
 664  * |             v
 665  * |      WRITE_STATE_PRE_WORK -----> [SUB_STATE_END_HANDSHAKE]
 666  * |             |
 667  * |             v
 668  * |       WRITE_STATE_SEND
 669  * |             |
 670  * |             v
 671  * |     WRITE_STATE_POST_WORK
 672  * |             |
 673  * +-------------+
 674  *
 675  * WRITE_STATE_TRANSITION transitions the state of the handshake state machine
 676
 677  * WRITE_STATE_PRE_WORK performs any work necessary to prepare the later
 678  * sending of the message. This could result in an NBIO event occuring in
 679  * which case control returns to the calling application. When this function
 680  * is recalled we will resume in the same state where we left off.
 681  *
 682  * WRITE_STATE_SEND sends the message and performs any work to be done after
 683  * sending.
 684  *
 685  * WRITE_STATE_POST_WORK performs any work necessary after the sending of the
 686  * message has been completed. As for WRITE_STATE_PRE_WORK this could also
 687  * result in an NBIO event.
 688  */
 689 static enum SUB_STATE_RETURN write_state_machine(SSL *s)
 690 {
 691     OSSL_STATEM *st = &s->statem;
 692     int ret;
 693     enum WRITE_TRAN (*transition)(SSL *s);
 694     enum WORK_STATE (*pre_work)(SSL *s, enum WORK_STATE wst);
 695     enum WORK_STATE (*post_work)(SSL *s, enum WORK_STATE wst);
 696     int (*construct_message)(SSL *s);
 697     void (*cb) (const SSL *ssl, int type, int val) = NULL;
 698
 699     if (s->info_callback != NULL)
 700         cb = s->info_callback;
 701     else if (s->ctx->info_callback != NULL)
 702         cb = s->ctx->info_callback;
 703
 704     if(s->server) {
 705         transition = server_write_transition;
 706         pre_work = server_pre_work;
 707         post_work = server_post_work;
 708         construct_message = server_construct_message;
 709     } else {
 710         transition = client_write_transition;
 711         pre_work = client_pre_work;
 712         post_work = client_post_work;
 713         construct_message = client_construct_message;
 714     }
 715
 716     while(1) {
 717         switch(st->write_state) {
 718         case WRITE_STATE_TRANSITION:
 719             if (cb != NULL) {
 720                 /* Notify callback of an impending state change */
 721                 if (s->server)
 722                     cb(s, SSL_CB_ACCEPT_LOOP, 1);
 723                 else
 724                     cb(s, SSL_CB_CONNECT_LOOP, 1);
 725             }
 726             switch(transition(s)) {
 727             case WRITE_TRAN_CONTINUE:
 728                 st->write_state = WRITE_STATE_PRE_WORK;
 729                 st->write_state_work = WORK_MORE_A;
 730                 break;
 731
 732             case WRITE_TRAN_FINISHED:
 733                 return SUB_STATE_FINISHED;
 734                 break;
 735
 736             default:
 737                 return SUB_STATE_ERROR;
 738             }
 739             break;
 740
 741         case WRITE_STATE_PRE_WORK:
 742             switch(st->write_state_work = pre_work(s, st->write_state_work)) {
 743             default:
 744                 return SUB_STATE_ERROR;
 745
 746             case WORK_FINISHED_CONTINUE:
 747                 st->write_state = WRITE_STATE_SEND;
 748                 break;
 749
 750             case WORK_FINISHED_STOP:
 751                 return SUB_STATE_END_HANDSHAKE;
 752             }
 753             if(construct_message(s) == 0)
 754                 return SUB_STATE_ERROR;
 755
 756             /* Fall through */
 757
 758         case WRITE_STATE_SEND:
 759             if (SSL_IS_DTLS(s) && st->use_timer) {
 760                 dtls1_start_timer(s);
 761             }
 762             ret = statem_do_write(s);
 763             if (ret <= 0) {
 764                 return SUB_STATE_ERROR;
 765             }
 766             st->write_state = WRITE_STATE_POST_WORK;
 767             st->write_state_work = WORK_MORE_A;
 768             /* Fall through */
 769
 770         case WRITE_STATE_POST_WORK:
 771             switch(st->write_state_work = post_work(s, st->write_state_work)) {
 772             default:
 773                 return SUB_STATE_ERROR;
 774
 775             case WORK_FINISHED_CONTINUE:
 776                 st->write_state = WRITE_STATE_TRANSITION;
 777                 break;
 778
 779             case WORK_FINISHED_STOP:
 780                 return SUB_STATE_END_HANDSHAKE;
 781             }
 782             break;
 783
 784         default:
 785             return SUB_STATE_ERROR;
 786         }
 787     }
 788 }
 789
 790 /*
 791  * Flush the write BIO
 792  */
 793 int statem_flush(SSL *s)
 794 {
 795     s->rwstate = SSL_WRITING;
 796     if (BIO_flush(s->wbio) <= 0) {
 797         return 0;
 798     }
 799     s->rwstate = SSL_NOTHING;
 800
 801     return 1;
 802 }
 803
 804 /*
 805  * Called by the record layer to determine whether application data is
 806  * allowed to be sent in the current handshake state or not.
 807  *
 808  * Return values are:
 809  *   1: Yes (application data allowed)
 810  *   0: No (application data not allowed)
 811  */
 812 int ossl_statem_app_data_allowed(SSL *s)
 813 {
 814     OSSL_STATEM *st = &s->statem;
 815
 816     if (st->state == MSG_FLOW_UNINITED || st->state == MSG_FLOW_RENEGOTIATE)
 817         return 0;
 818
 819     if (!s->s3->in_read_app_data || (s->s3->total_renegotiations == 0))
 820         return 0;
 821
 822     if (s->server) {
 823         /*
 824          * If we're a server and we haven't got as far as writing our
 825          * ServerHello yet then we allow app data
 826          */
 827         if (st->hand_state == TLS_ST_BEFORE
 828                 || st->hand_state == TLS_ST_SR_CLNT_HELLO)
 829             return 1;
 830     } else {
 831         /*
 832          * If we're a client and we haven't read the ServerHello yet then we
 833          * allow app data
 834          */
 835         if (st->hand_state == TLS_ST_CW_CLNT_HELLO)
 836             return 1;
 837     }
 838
 839     return 0;
 840 }
 841
 842 #ifndef OPENSSL_NO_SCTP
 843 /*
 844  * Set flag used by SCTP to determine whether we are in the read sock state
 845  */
 846 void ossl_statem_set_sctp_read_sock(SSL *s, int read_sock)
 847 {
 848     s->statem.in_sctp_read_sock = read_sock;
 849 }
 850
 851 /*
 852  * Called by the record layer to determine whether we are in the read sock
 853  * state or not.
 854  *
 855  * Return values are:
 856  *   1: Yes (we are in the read sock state)
 857  *   0: No (we are not in the read sock state)
 858  */
 859 int statem_in_sctp_read_sock(SSL *s)
 860 {
 861     return s->statem.in_sctp_read_sock;
 862 }
 863 #endif