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 typedef enum  {
  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 } SUB_STATE_RETURN;
 106
 107 static int state_machine(SSL *s, int server);
 108 static void init_read_state_machine(SSL *s);
 109 static SUB_STATE_RETURN read_state_machine(SSL *s);
 110 static void init_write_state_machine(SSL *s);
 111 static 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 static void (*get_callback(SSL *s))(const SSL *, int, int)
 200 {
 201     if (s->info_callback != NULL)
 202         return s->info_callback;
 203     else if (s->ctx->info_callback != NULL)
 204         return s->ctx->info_callback;
 205
 206     return NULL;
 207 }
 208
 209 /*
 210  * The main message flow state machine. We start in the MSG_FLOW_UNINITED or
 211  * MSG_FLOW_RENEGOTIATE state and finish in MSG_FLOW_FINISHED. Valid states and
 212  * transitions are as follows:
 213  *
 214  * MSG_FLOW_UNINITED     MSG_FLOW_RENEGOTIATE
 215  *        |                       |
 216  *        +-----------------------+
 217  *        v
 218  * MSG_FLOW_WRITING <---> MSG_FLOW_READING
 219  *        |
 220  *        V
 221  * MSG_FLOW_FINISHED
 222  *        |
 223  *        V
 224  *    [SUCCESS]
 225  *
 226  * We may exit at any point due to an error or NBIO event. If an NBIO event
 227  * occurs then we restart at the point we left off when we are recalled.
 228  * MSG_FLOW_WRITING and MSG_FLOW_READING have sub-state machines associated with them.
 229  *
 230  * In addition to the above there is also the MSG_FLOW_ERROR state. We can move
 231  * into that state at any point in the event that an irrecoverable error occurs.
 232  *
 233  * Valid return values are:
 234  *   1: Success
 235  * <=0: NBIO or error
 236  */
 237 static int state_machine(SSL *s, int server) {
 238     BUF_MEM *buf = NULL;
 239     unsigned long Time = (unsigned long)time(NULL);
 240     void (*cb) (const SSL *ssl, int type, int val) = NULL;
 241     OSSL_STATEM *st = &s->statem;
 242     int ret = -1;
 243     int ssret;
 244
 245     if (st->state == MSG_FLOW_ERROR) {
 246         /* Shouldn't have been called if we're already in the error state */
 247         return -1;
 248     }
 249
 250     RAND_add(&Time, sizeof(Time), 0);
 251     ERR_clear_error();
 252     clear_sys_error();
 253
 254     cb = get_callback(s);
 255
 256     s->in_handshake++;
 257     if (!SSL_in_init(s) || SSL_in_before(s)) {
 258         if (!SSL_clear(s))
 259             return -1;
 260     }
 261
 262 #ifndef OPENSSL_NO_SCTP
 263     if (SSL_IS_DTLS(s)) {
 264         /*
 265          * Notify SCTP BIO socket to enter handshake mode and prevent stream
 266          * identifier other than 0. Will be ignored if no SCTP is used.
 267          */
 268         BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
 269                  s->in_handshake, NULL);
 270     }
 271 #endif
 272
 273 #ifndef OPENSSL_NO_HEARTBEATS
 274     /*
 275      * If we're awaiting a HeartbeatResponse, pretend we already got and
 276      * don't await it anymore, because Heartbeats don't make sense during
 277      * handshakes anyway.
 278      */
 279     if (s->tlsext_hb_pending) {
 280         if (SSL_IS_DTLS(s))
 281             dtls1_stop_timer(s);
 282         s->tlsext_hb_pending = 0;
 283         s->tlsext_hb_seq++;
 284     }
 285 #endif
 286
 287     /* Initialise state machine */
 288
 289     if (st->state == MSG_FLOW_RENEGOTIATE) {
 290         s->renegotiate = 1;
 291         if (!server)
 292             s->ctx->stats.sess_connect_renegotiate++;
 293     }
 294
 295     if (st->state == MSG_FLOW_UNINITED || st->state == MSG_FLOW_RENEGOTIATE) {
 296         if (st->state == MSG_FLOW_UNINITED) {
 297             st->hand_state = TLS_ST_BEFORE;
 298         }
 299
 300         s->server = server;
 301         if (cb != NULL)
 302             cb(s, SSL_CB_HANDSHAKE_START, 1);
 303
 304         if (SSL_IS_DTLS(s)) {
 305             if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00) &&
 306                     (server
 307                     || (s->version & 0xff00) != (DTLS1_BAD_VER & 0xff00))) {
 308                 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 309                 goto end;
 310             }
 311         } else {
 312             if ((s->version >> 8) != SSL3_VERSION_MAJOR
 313                     && s->version != TLS_ANY_VERSION) {
 314                 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 315                 goto end;
 316             }
 317         }
 318
 319         if (!SSL_IS_DTLS(s)) {
 320             if (s->version != TLS_ANY_VERSION &&
 321                     !ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL)) {
 322                 SSLerr(SSL_F_STATE_MACHINE, SSL_R_VERSION_TOO_LOW);
 323                 goto end;
 324             }
 325         }
 326
 327         if (s->init_buf == NULL) {
 328             if ((buf = BUF_MEM_new()) == NULL) {
 329                 goto end;
 330             }
 331             if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {
 332                 goto end;
 333             }
 334             s->init_buf = buf;
 335             buf = NULL;
 336         }
 337
 338         if (!ssl3_setup_buffers(s)) {
 339             goto end;
 340         }
 341         s->init_num = 0;
 342
 343         /*
 344          * Should have been reset by tls_process_finished, too.
 345          */
 346         s->s3->change_cipher_spec = 0;
 347
 348         if (!server || st->state != MSG_FLOW_RENEGOTIATE) {
 349                 /*
 350                  * Ok, we now need to push on a buffering BIO ...but not with
 351                  * SCTP
 352                  */
 353 #ifndef OPENSSL_NO_SCTP
 354                 if (!SSL_IS_DTLS(s) || !BIO_dgram_is_sctp(SSL_get_wbio(s)))
 355 #endif
 356                     if (!ssl_init_wbio_buffer(s, server ? 1 : 0)) {
 357                         goto end;
 358                     }
 359
 360             ssl3_init_finished_mac(s);
 361         }
 362
 363         if (server) {
 364             if (st->state != MSG_FLOW_RENEGOTIATE) {
 365                 s->ctx->stats.sess_accept++;
 366             } else if (!s->s3->send_connection_binding &&
 367                        !(s->options &
 368                          SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)) {
 369                 /*
 370                  * Server attempting to renegotiate with client that doesn't
 371                  * support secure renegotiation.
 372                  */
 373                 SSLerr(SSL_F_STATE_MACHINE,
 374                        SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
 375                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
 376                 ossl_statem_set_error(s);
 377                 goto end;
 378             } else {
 379                 /*
 380                  * st->state == MSG_FLOW_RENEGOTIATE, we will just send a
 381                  * HelloRequest
 382                  */
 383                 s->ctx->stats.sess_accept_renegotiate++;
 384             }
 385         } else {
 386             s->ctx->stats.sess_connect++;
 387
 388             /* mark client_random uninitialized */
 389             memset(s->s3->client_random, 0, sizeof(s->s3->client_random));
 390             s->hit = 0;
 391
 392             s->s3->tmp.cert_request = 0;
 393
 394             if (SSL_IS_DTLS(s)) {
 395                 st->use_timer = 1;
 396             }
 397         }
 398
 399         st->state = MSG_FLOW_WRITING;
 400         init_write_state_machine(s);
 401         st->read_state_first_init = 1;
 402     }
 403
 404     while(st->state != MSG_FLOW_FINISHED) {
 405         if(st->state == MSG_FLOW_READING) {
 406             ssret = read_state_machine(s);
 407             if (ssret == SUB_STATE_FINISHED) {
 408                 st->state = MSG_FLOW_WRITING;
 409                 init_write_state_machine(s);
 410             } else {
 411                 /* NBIO or error */
 412                 goto end;
 413             }
 414         } else if (st->state == MSG_FLOW_WRITING) {
 415             ssret = write_state_machine(s);
 416             if (ssret == SUB_STATE_FINISHED) {
 417                 st->state = MSG_FLOW_READING;
 418                 init_read_state_machine(s);
 419             } else if (ssret == SUB_STATE_END_HANDSHAKE) {
 420                 st->state = MSG_FLOW_FINISHED;
 421             } else {
 422                 /* NBIO or error */
 423                 goto end;
 424             }
 425         } else {
 426             /* Error */
 427             ossl_statem_set_error(s);
 428             goto end;
 429         }
 430     }
 431
 432     st->state = MSG_FLOW_UNINITED;
 433     ret = 1;
 434
 435  end:
 436     s->in_handshake--;
 437
 438 #ifndef OPENSSL_NO_SCTP
 439     if (SSL_IS_DTLS(s)) {
 440         /*
 441          * Notify SCTP BIO socket to leave handshake mode and allow stream
 442          * identifier other than 0. Will be ignored if no SCTP is used.
 443          */
 444         BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
 445                  s->in_handshake, NULL);
 446     }
 447 #endif
 448
 449     BUF_MEM_free(buf);
 450     if (cb != NULL) {
 451         if (server)
 452             cb(s, SSL_CB_ACCEPT_EXIT, ret);
 453         else
 454             cb(s, SSL_CB_CONNECT_EXIT, ret);
 455     }
 456     return ret;
 457 }
 458
 459 /*
 460  * Initialise the MSG_FLOW_READING sub-state machine
 461  */
 462 static void init_read_state_machine(SSL *s)
 463 {
 464     OSSL_STATEM *st = &s->statem;
 465
 466     st->read_state = READ_STATE_HEADER;
 467 }
 468
 469 /*
 470  * This function implements the sub-state machine when the message flow is in
 471  * MSG_FLOW_READING. The valid sub-states and transitions are:
 472  *
 473  * READ_STATE_HEADER <--+<-------------+
 474  *        |             |              |
 475  *        v             |              |
 476  * READ_STATE_BODY -----+-->READ_STATE_POST_PROCESS
 477  *        |                            |
 478  *        +----------------------------+
 479  *        v
 480  * [SUB_STATE_FINISHED]
 481  *
 482  * READ_STATE_HEADER has the responsibility for reading in the message header
 483  * and transitioning the state of the handshake state machine.
 484  *
 485  * READ_STATE_BODY reads in the rest of the message and then subsequently
 486  * processes it.
 487  *
 488  * READ_STATE_POST_PROCESS is an optional step that may occur if some post
 489  * processing activity performed on the message may block.
 490  *
 491  * Any of the above states could result in an NBIO event occuring in which case
 492  * control returns to the calling application. When this function is recalled we
 493  * will resume in the same state where we left off.
 494  */
 495 static SUB_STATE_RETURN read_state_machine(SSL *s) {
 496     OSSL_STATEM *st = &s->statem;
 497     int ret, mt;
 498     unsigned long len;
 499     int (*transition)(SSL *s, int mt);
 500     PACKET pkt;
 501     enum MSG_PROCESS_RETURN (*process_message)(SSL *s, PACKET *pkt);
 502     enum WORK_STATE (*post_process_message)(SSL *s, enum WORK_STATE wst);
 503     unsigned long (*max_message_size)(SSL *s);
 504     void (*cb) (const SSL *ssl, int type, int val) = NULL;
 505
 506     cb = get_callback(s);
 507
 508     if(s->server) {
 509         transition = server_read_transition;
 510         process_message = server_process_message;
 511         max_message_size = server_max_message_size;
 512         post_process_message = server_post_process_message;
 513     } else {
 514         transition = client_read_transition;
 515         process_message = client_process_message;
 516         max_message_size = client_max_message_size;
 517         post_process_message = client_post_process_message;
 518     }
 519
 520     if (st->read_state_first_init) {
 521         s->first_packet = 1;
 522         st->read_state_first_init = 0;
 523     }
 524
 525     while(1) {
 526         switch(st->read_state) {
 527         case READ_STATE_HEADER:
 528             s->init_num = 0;
 529             /* Get the state the peer wants to move to */
 530             if (SSL_IS_DTLS(s)) {
 531                 /*
 532                  * In DTLS we get the whole message in one go - header and body
 533                  */
 534                 ret = dtls_get_message(s, &mt, &len);
 535             } else {
 536                 ret = tls_get_message_header(s, &mt);
 537             }
 538
 539             if (ret == 0) {
 540                 /* Could be non-blocking IO */
 541                 return SUB_STATE_ERROR;
 542             }
 543
 544             if (cb != NULL) {
 545                 /* Notify callback of an impending state change */
 546                 if (s->server)
 547                     cb(s, SSL_CB_ACCEPT_LOOP, 1);
 548                 else
 549                     cb(s, SSL_CB_CONNECT_LOOP, 1);
 550             }
 551             /*
 552              * Validate that we are allowed to move to the new state and move
 553              * to that state if so
 554              */
 555             if(!transition(s, mt)) {
 556                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL3_AD_UNEXPECTED_MESSAGE);
 557                 SSLerr(SSL_F_READ_STATE_MACHINE, SSL_R_UNEXPECTED_MESSAGE);
 558                 return SUB_STATE_ERROR;
 559             }
 560
 561             if (s->s3->tmp.message_size > max_message_size(s)) {
 562                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
 563                 SSLerr(SSL_F_READ_STATE_MACHINE, SSL_R_EXCESSIVE_MESSAGE_SIZE);
 564                 return SUB_STATE_ERROR;
 565             }
 566
 567             st->read_state = READ_STATE_BODY;
 568             /* Fall through */
 569
 570         case READ_STATE_BODY:
 571             if (!SSL_IS_DTLS(s)) {
 572                 /* We already got this above for DTLS */
 573                 ret = tls_get_message_body(s, &len);
 574                 if (ret == 0) {
 575                     /* Could be non-blocking IO */
 576                     return SUB_STATE_ERROR;
 577                 }
 578             }
 579
 580             s->first_packet = 0;
 581             if (!PACKET_buf_init(&pkt, s->init_msg, len)) {
 582                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
 583                 SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 584                 return SUB_STATE_ERROR;
 585             }
 586             ret = process_message(s, &pkt);
 587             if (ret == MSG_PROCESS_ERROR) {
 588                 return SUB_STATE_ERROR;
 589             }
 590
 591             if (ret == MSG_PROCESS_FINISHED_READING) {
 592                 if (SSL_IS_DTLS(s)) {
 593                     dtls1_stop_timer(s);
 594                 }
 595                 return SUB_STATE_FINISHED;
 596             }
 597
 598             if (ret == MSG_PROCESS_CONTINUE_PROCESSING) {
 599                 st->read_state = READ_STATE_POST_PROCESS;
 600                 st->read_state_work = WORK_MORE_A;
 601             } else {
 602                 st->read_state = READ_STATE_HEADER;
 603             }
 604             break;
 605
 606         case READ_STATE_POST_PROCESS:
 607             st->read_state_work = post_process_message(s, st->read_state_work);
 608             switch(st->read_state_work) {
 609             default:
 610                 return SUB_STATE_ERROR;
 611
 612             case WORK_FINISHED_CONTINUE:
 613                 st->read_state = READ_STATE_HEADER;
 614                 break;
 615
 616             case WORK_FINISHED_STOP:
 617                 if (SSL_IS_DTLS(s)) {
 618                     dtls1_stop_timer(s);
 619                 }
 620                 return SUB_STATE_FINISHED;
 621             }
 622             break;
 623
 624         default:
 625             /* Shouldn't happen */
 626             ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
 627             SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 628             ossl_statem_set_error(s);
 629             return SUB_STATE_ERROR;
 630         }
 631     }
 632 }
 633
 634 /*
 635  * Send a previously constructed message to the peer.
 636  */
 637 static int statem_do_write(SSL *s)
 638 {
 639     OSSL_STATEM *st = &s->statem;
 640
 641     if (st->hand_state == TLS_ST_CW_CHANGE
 642             || st->hand_state == TLS_ST_SW_CHANGE) {
 643         if (SSL_IS_DTLS(s))
 644             return dtls1_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
 645         else
 646             return ssl3_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
 647     } else {
 648         return ssl_do_write(s);
 649     }
 650 }
 651
 652 /*
 653  * Initialise the MSG_FLOW_WRITING sub-state machine
 654  */
 655 static void init_write_state_machine(SSL *s)
 656 {
 657     OSSL_STATEM *st = &s->statem;
 658
 659     st->write_state = WRITE_STATE_TRANSITION;
 660 }
 661
 662 /*
 663  * This function implements the sub-state machine when the message flow is in
 664  * MSG_FLOW_WRITING. The valid sub-states and transitions are:
 665  *
 666  * +-> WRITE_STATE_TRANSITION ------> [SUB_STATE_FINISHED]
 667  * |             |
 668  * |             v
 669  * |      WRITE_STATE_PRE_WORK -----> [SUB_STATE_END_HANDSHAKE]
 670  * |             |
 671  * |             v
 672  * |       WRITE_STATE_SEND
 673  * |             |
 674  * |             v
 675  * |     WRITE_STATE_POST_WORK
 676  * |             |
 677  * +-------------+
 678  *
 679  * WRITE_STATE_TRANSITION transitions the state of the handshake state machine
 680
 681  * WRITE_STATE_PRE_WORK performs any work necessary to prepare the later
 682  * sending of the message. This could result in an NBIO event occuring in
 683  * which case control returns to the calling application. When this function
 684  * is recalled we will resume in the same state where we left off.
 685  *
 686  * WRITE_STATE_SEND sends the message and performs any work to be done after
 687  * sending.
 688  *
 689  * WRITE_STATE_POST_WORK performs any work necessary after the sending of the
 690  * message has been completed. As for WRITE_STATE_PRE_WORK this could also
 691  * result in an NBIO event.
 692  */
 693 static SUB_STATE_RETURN write_state_machine(SSL *s)
 694 {
 695     OSSL_STATEM *st = &s->statem;
 696     int ret;
 697     enum WRITE_TRAN (*transition)(SSL *s);
 698     enum WORK_STATE (*pre_work)(SSL *s, enum WORK_STATE wst);
 699     enum WORK_STATE (*post_work)(SSL *s, enum WORK_STATE wst);
 700     int (*construct_message)(SSL *s);
 701     void (*cb) (const SSL *ssl, int type, int val) = NULL;
 702
 703     cb = get_callback(s);
 704
 705     if(s->server) {
 706         transition = server_write_transition;
 707         pre_work = server_pre_work;
 708         post_work = server_post_work;
 709         construct_message = server_construct_message;
 710     } else {
 711         transition = client_write_transition;
 712         pre_work = client_pre_work;
 713         post_work = client_post_work;
 714         construct_message = client_construct_message;
 715     }
 716
 717     while(1) {
 718         switch(st->write_state) {
 719         case WRITE_STATE_TRANSITION:
 720             if (cb != NULL) {
 721                 /* Notify callback of an impending state change */
 722                 if (s->server)
 723                     cb(s, SSL_CB_ACCEPT_LOOP, 1);
 724                 else
 725                     cb(s, SSL_CB_CONNECT_LOOP, 1);
 726             }
 727             switch(transition(s)) {
 728             case WRITE_TRAN_CONTINUE:
 729                 st->write_state = WRITE_STATE_PRE_WORK;
 730                 st->write_state_work = WORK_MORE_A;
 731                 break;
 732
 733             case WRITE_TRAN_FINISHED:
 734                 return SUB_STATE_FINISHED;
 735                 break;
 736
 737             default:
 738                 return SUB_STATE_ERROR;
 739             }
 740             break;
 741
 742         case WRITE_STATE_PRE_WORK:
 743             switch(st->write_state_work = pre_work(s, st->write_state_work)) {
 744             default:
 745                 return SUB_STATE_ERROR;
 746
 747             case WORK_FINISHED_CONTINUE:
 748                 st->write_state = WRITE_STATE_SEND;
 749                 break;
 750
 751             case WORK_FINISHED_STOP:
 752                 return SUB_STATE_END_HANDSHAKE;
 753             }
 754             if(construct_message(s) == 0)
 755                 return SUB_STATE_ERROR;
 756
 757             /* Fall through */
 758
 759         case WRITE_STATE_SEND:
 760             if (SSL_IS_DTLS(s) && st->use_timer) {
 761                 dtls1_start_timer(s);
 762             }
 763             ret = statem_do_write(s);
 764             if (ret <= 0) {
 765                 return SUB_STATE_ERROR;
 766             }
 767             st->write_state = WRITE_STATE_POST_WORK;
 768             st->write_state_work = WORK_MORE_A;
 769             /* Fall through */
 770
 771         case WRITE_STATE_POST_WORK:
 772             switch(st->write_state_work = post_work(s, st->write_state_work)) {
 773             default:
 774                 return SUB_STATE_ERROR;
 775
 776             case WORK_FINISHED_CONTINUE:
 777                 st->write_state = WRITE_STATE_TRANSITION;
 778                 break;
 779
 780             case WORK_FINISHED_STOP:
 781                 return SUB_STATE_END_HANDSHAKE;
 782             }
 783             break;
 784
 785         default:
 786             return SUB_STATE_ERROR;
 787         }
 788     }
 789 }
 790
 791 /*
 792  * Flush the write BIO
 793  */
 794 int statem_flush(SSL *s)
 795 {
 796     s->rwstate = SSL_WRITING;
 797     if (BIO_flush(s->wbio) <= 0) {
 798         return 0;
 799     }
 800     s->rwstate = SSL_NOTHING;
 801
 802     return 1;
 803 }
 804
 805 /*
 806  * Called by the record layer to determine whether application data is
 807  * allowed to be sent in the current handshake state or not.
 808  *
 809  * Return values are:
 810  *   1: Yes (application data allowed)
 811  *   0: No (application data not allowed)
 812  */
 813 int ossl_statem_app_data_allowed(SSL *s)
 814 {
 815     OSSL_STATEM *st = &s->statem;
 816
 817     if (st->state == MSG_FLOW_UNINITED || st->state == MSG_FLOW_RENEGOTIATE)
 818         return 0;
 819
 820     if (!s->s3->in_read_app_data || (s->s3->total_renegotiations == 0))
 821         return 0;
 822
 823     if (s->server) {
 824         /*
 825          * If we're a server and we haven't got as far as writing our
 826          * ServerHello yet then we allow app data
 827          */
 828         if (st->hand_state == TLS_ST_BEFORE
 829                 || st->hand_state == TLS_ST_SR_CLNT_HELLO)
 830             return 1;
 831     } else {
 832         /*
 833          * If we're a client and we haven't read the ServerHello yet then we
 834          * allow app data
 835          */
 836         if (st->hand_state == TLS_ST_CW_CLNT_HELLO)
 837             return 1;
 838     }
 839
 840     return 0;
 841 }
 842
 843 #ifndef OPENSSL_NO_SCTP
 844 /*
 845  * Set flag used by SCTP to determine whether we are in the read sock state
 846  */
 847 void ossl_statem_set_sctp_read_sock(SSL *s, int read_sock)
 848 {
 849     s->statem.in_sctp_read_sock = read_sock;
 850 }
 851
 852 /*
 853  * Called by the record layer to determine whether we are in the read sock
 854  * state or not.
 855  *
 856  * Return values are:
 857  *   1: Yes (we are in the read sock state)
 858  *   0: No (we are not in the read sock state)
 859  */
 860 int statem_in_sctp_read_sock(SSL *s)
 861 {
 862     return s->statem.in_sctp_read_sock;
 863 }
 864 #endif