ssl/statem/statem.c

   1 /*
   2  * Copyright 2015-2016 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the OpenSSL license (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <openssl/rand.h>
  11 #include "../ssl_locl.h"
  12 #include "statem_locl.h"
  13
  14 /*
  15  * This file implements the SSL/TLS/DTLS state machines.
  16  *
  17  * There are two primary state machines:
  18  *
  19  * 1) Message flow state machine
  20  * 2) Handshake state machine
  21  *
  22  * The Message flow state machine controls the reading and sending of messages
  23  * including handling of non-blocking IO events, flushing of the underlying
  24  * write BIO, handling unexpected messages, etc. It is itself broken into two
  25  * separate sub-state machines which control reading and writing respectively.
  26  *
  27  * The Handshake state machine keeps track of the current SSL/TLS handshake
  28  * state. Transitions of the handshake state are the result of events that
  29  * occur within the Message flow state machine.
  30  *
  31  * Overall it looks like this:
  32  *
  33  * ---------------------------------------------            -------------------
  34  * |                                           |            |                 |
  35  * | Message flow state machine                |            |                 |
  36  * |                                           |            |                 |
  37  * | -------------------- -------------------- | Transition | Handshake state |
  38  * | | MSG_FLOW_READING | | MSG_FLOW_WRITING | | Event      | machine         |
  39  * | | sub-state        | | sub-state        | |----------->|                 |
  40  * | | machine for      | | machine for      | |            |                 |
  41  * | | reading messages | | writing messages | |            |                 |
  42  * | -------------------- -------------------- |            |                 |
  43  * |                                           |            |                 |
  44  * ---------------------------------------------            -------------------
  45  *
  46  */
  47
  48 /* Sub state machine return values */
  49 typedef enum {
  50     /* Something bad happened or NBIO */
  51     SUB_STATE_ERROR,
  52     /* Sub state finished go to the next sub state */
  53     SUB_STATE_FINISHED,
  54     /* Sub state finished and handshake was completed */
  55     SUB_STATE_END_HANDSHAKE
  56 } SUB_STATE_RETURN;
  57
  58 static int state_machine(SSL *s, int server);
  59 static void init_read_state_machine(SSL *s);
  60 static SUB_STATE_RETURN read_state_machine(SSL *s);
  61 static void init_write_state_machine(SSL *s);
  62 static SUB_STATE_RETURN write_state_machine(SSL *s);
  63
  64 OSSL_HANDSHAKE_STATE SSL_get_state(const SSL *ssl)
  65 {
  66     return ssl->statem.hand_state;
  67 }
  68
  69 int SSL_in_init(SSL *s)
  70 {
  71     return s->statem.in_init;
  72 }
  73
  74 int SSL_is_init_finished(SSL *s)
  75 {
  76     return !(s->statem.in_init) && (s->statem.hand_state == TLS_ST_OK);
  77 }
  78
  79 int SSL_in_before(SSL *s)
  80 {
  81     /*
  82      * Historically being "in before" meant before anything had happened. In the
  83      * current code though we remain in the "before" state for a while after we
  84      * have started the handshake process (e.g. as a server waiting for the
  85      * first message to arrive). There "in before" is taken to mean "in before"
  86      * and not started any handshake process yet.
  87      */
  88     return (s->statem.hand_state == TLS_ST_BEFORE)
  89         && (s->statem.state == MSG_FLOW_UNINITED);
  90 }
  91
  92 /*
  93  * Clear the state machine state and reset back to MSG_FLOW_UNINITED
  94  */
  95 void ossl_statem_clear(SSL *s)
  96 {
  97     s->statem.state = MSG_FLOW_UNINITED;
  98     s->statem.hand_state = TLS_ST_BEFORE;
  99     s->statem.in_init = 1;
 100     s->statem.no_cert_verify = 0;
 101 }
 102
 103 /*
 104  * Set the state machine up ready for a renegotiation handshake
 105  */
 106 void ossl_statem_set_renegotiate(SSL *s)
 107 {
 108     s->statem.in_init = 1;
 109     s->statem.request_state = TLS_ST_SW_HELLO_REQ;
 110 }
 111
 112 /*
 113  * Put the state machine into an error state. This is a permanent error for
 114  * the current connection.
 115  */
 116 void ossl_statem_set_error(SSL *s)
 117 {
 118     s->statem.state = MSG_FLOW_ERROR;
 119 }
 120
 121 /*
 122  * Discover whether the current connection is in the error state.
 123  *
 124  * Valid return values are:
 125  *   1: Yes
 126  *   0: No
 127  */
 128 int ossl_statem_in_error(const SSL *s)
 129 {
 130     if (s->statem.state == MSG_FLOW_ERROR)
 131         return 1;
 132
 133     return 0;
 134 }
 135
 136 void ossl_statem_set_in_init(SSL *s, int init)
 137 {
 138     s->statem.in_init = init;
 139 }
 140
 141 int ossl_statem_get_in_handshake(SSL *s)
 142 {
 143     return s->statem.in_handshake;
 144 }
 145
 146 void ossl_statem_set_in_handshake(SSL *s, int inhand)
 147 {
 148     if (inhand)
 149         s->statem.in_handshake++;
 150     else
 151         s->statem.in_handshake--;
 152 }
 153
 154 void ossl_statem_set_hello_verify_done(SSL *s)
 155 {
 156     s->statem.state = MSG_FLOW_UNINITED;
 157     s->statem.in_init = 1;
 158     /*
 159      * This will get reset (briefly) back to TLS_ST_BEFORE when we enter
 160      * state_machine() because |state| is MSG_FLOW_UNINITED, but until then any
 161      * calls to SSL_in_before() will return false. Also calls to
 162      * SSL_state_string() and SSL_state_string_long() will return something
 163      * sensible.
 164      */
 165     s->statem.hand_state = TLS_ST_SR_CLNT_HELLO;
 166 }
 167
 168 int ossl_statem_connect(SSL *s)
 169 {
 170     return state_machine(s, 0);
 171 }
 172
 173 int ossl_statem_accept(SSL *s)
 174 {
 175     return state_machine(s, 1);
 176 }
 177
 178 typedef void (*info_cb) (const SSL *, int, int);
 179
 180 static info_cb get_callback(SSL *s)
 181 {
 182     if (s->info_callback != NULL)
 183         return s->info_callback;
 184     else if (s->ctx->info_callback != NULL)
 185         return s->ctx->info_callback;
 186
 187     return NULL;
 188 }
 189
 190 /*
 191  * The main message flow state machine. We start in the MSG_FLOW_UNINITED or
 192  * MSG_FLOW_FINISHED state and finish in MSG_FLOW_FINISHED. Valid states and
 193  * transitions are as follows:
 194  *
 195  * MSG_FLOW_UNINITED     MSG_FLOW_FINISHED
 196  *        |                       |
 197  *        +-----------------------+
 198  *        v
 199  * MSG_FLOW_WRITING <---> MSG_FLOW_READING
 200  *        |
 201  *        V
 202  * MSG_FLOW_FINISHED
 203  *        |
 204  *        V
 205  *    [SUCCESS]
 206  *
 207  * We may exit at any point due to an error or NBIO event. If an NBIO event
 208  * occurs then we restart at the point we left off when we are recalled.
 209  * MSG_FLOW_WRITING and MSG_FLOW_READING have sub-state machines associated with them.
 210  *
 211  * In addition to the above there is also the MSG_FLOW_ERROR state. We can move
 212  * into that state at any point in the event that an irrecoverable error occurs.
 213  *
 214  * Valid return values are:
 215  *   1: Success
 216  * <=0: NBIO or error
 217  */
 218 static int state_machine(SSL *s, int server)
 219 {
 220     BUF_MEM *buf = NULL;
 221     unsigned long Time = (unsigned long)time(NULL);
 222     void (*cb) (const SSL *ssl, int type, int val) = NULL;
 223     OSSL_STATEM *st = &s->statem;
 224     int ret = -1;
 225     int ssret;
 226
 227     if (st->state == MSG_FLOW_ERROR) {
 228         /* Shouldn't have been called if we're already in the error state */
 229         return -1;
 230     }
 231
 232     RAND_add(&Time, sizeof(Time), 0);
 233     ERR_clear_error();
 234     clear_sys_error();
 235
 236     cb = get_callback(s);
 237
 238     st->in_handshake++;
 239     if (!SSL_in_init(s) || SSL_in_before(s)) {
 240         if (!SSL_clear(s))
 241             return -1;
 242     }
 243 #ifndef OPENSSL_NO_SCTP
 244     if (SSL_IS_DTLS(s)) {
 245         /*
 246          * Notify SCTP BIO socket to enter handshake mode and prevent stream
 247          * identifier other than 0. Will be ignored if no SCTP is used.
 248          */
 249         BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
 250                  st->in_handshake, NULL);
 251     }
 252 #endif
 253
 254     /* Initialise state machine */
 255     if (st->state == MSG_FLOW_UNINITED
 256             || st->state == MSG_FLOW_FINISHED) {
 257         if (st->state == MSG_FLOW_UNINITED) {
 258             st->hand_state = TLS_ST_BEFORE;
 259             st->request_state = TLS_ST_BEFORE;
 260         }
 261
 262         s->server = server;
 263         if (cb != NULL)
 264             cb(s, SSL_CB_HANDSHAKE_START, 1);
 265
 266         if (SSL_IS_DTLS(s)) {
 267             if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00) &&
 268                 (server || (s->version & 0xff00) != (DTLS1_BAD_VER & 0xff00))) {
 269                 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 270                 goto end;
 271             }
 272         } else {
 273             if ((s->version >> 8) != SSL3_VERSION_MAJOR) {
 274                 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 275                 goto end;
 276             }
 277         }
 278
 279         if (!ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL)) {
 280             SSLerr(SSL_F_STATE_MACHINE, SSL_R_VERSION_TOO_LOW);
 281             goto end;
 282         }
 283
 284         if (s->init_buf == NULL) {
 285             if ((buf = BUF_MEM_new()) == NULL) {
 286                 goto end;
 287             }
 288             if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {
 289                 goto end;
 290             }
 291             s->init_buf = buf;
 292             buf = NULL;
 293         }
 294
 295         if (!ssl3_setup_buffers(s)) {
 296             goto end;
 297         }
 298         s->init_num = 0;
 299
 300         /*
 301          * Should have been reset by tls_process_finished, too.
 302          */
 303         s->s3->change_cipher_spec = 0;
 304
 305         /*
 306          * Ok, we now need to push on a buffering BIO ...but not with
 307          * SCTP
 308          */
 309 #ifndef OPENSSL_NO_SCTP
 310         if (!SSL_IS_DTLS(s) || !BIO_dgram_is_sctp(SSL_get_wbio(s)))
 311 #endif
 312             if (!ssl_init_wbio_buffer(s)) {
 313                 goto end;
 314             }
 315
 316         if (SSL_IS_FIRST_HANDSHAKE(s) || s->renegotiate) {
 317             if (!tls_setup_handshake(s)) {
 318                 ossl_statem_set_error(s);
 319                 goto end;
 320             }
 321
 322             if (SSL_IS_FIRST_HANDSHAKE(s))
 323                 st->read_state_first_init = 1;
 324         }
 325
 326         st->state = MSG_FLOW_WRITING;
 327         init_write_state_machine(s);
 328     }
 329
 330     while (st->state != MSG_FLOW_FINISHED) {
 331         if (st->state == MSG_FLOW_READING) {
 332             ssret = read_state_machine(s);
 333             if (ssret == SUB_STATE_FINISHED) {
 334                 st->state = MSG_FLOW_WRITING;
 335                 init_write_state_machine(s);
 336             } else {
 337                 /* NBIO or error */
 338                 goto end;
 339             }
 340         } else if (st->state == MSG_FLOW_WRITING) {
 341             ssret = write_state_machine(s);
 342             if (ssret == SUB_STATE_FINISHED) {
 343                 st->state = MSG_FLOW_READING;
 344                 init_read_state_machine(s);
 345             } else if (ssret == SUB_STATE_END_HANDSHAKE) {
 346                 st->state = MSG_FLOW_FINISHED;
 347             } else {
 348                 /* NBIO or error */
 349                 goto end;
 350             }
 351         } else {
 352             /* Error */
 353             ossl_statem_set_error(s);
 354             goto end;
 355         }
 356     }
 357
 358     ret = 1;
 359
 360  end:
 361     st->in_handshake--;
 362
 363 #ifndef OPENSSL_NO_SCTP
 364     if (SSL_IS_DTLS(s)) {
 365         /*
 366          * Notify SCTP BIO socket to leave handshake mode and allow stream
 367          * identifier other than 0. Will be ignored if no SCTP is used.
 368          */
 369         BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
 370                  st->in_handshake, NULL);
 371     }
 372 #endif
 373
 374     BUF_MEM_free(buf);
 375     if (cb != NULL) {
 376         if (server)
 377             cb(s, SSL_CB_ACCEPT_EXIT, ret);
 378         else
 379             cb(s, SSL_CB_CONNECT_EXIT, ret);
 380     }
 381     return ret;
 382 }
 383
 384 /*
 385  * Initialise the MSG_FLOW_READING sub-state machine
 386  */
 387 static void init_read_state_machine(SSL *s)
 388 {
 389     OSSL_STATEM *st = &s->statem;
 390
 391     st->read_state = READ_STATE_HEADER;
 392 }
 393
 394 static int grow_init_buf(SSL *s, size_t size) {
 395
 396     size_t msg_offset = (char *)s->init_msg - s->init_buf->data;
 397
 398     if (!BUF_MEM_grow_clean(s->init_buf, (int)size))
 399         return 0;
 400
 401     if (size < msg_offset)
 402         return 0;
 403
 404     s->init_msg = s->init_buf->data + msg_offset;
 405
 406     return 1;
 407 }
 408
 409 /*
 410  * This function implements the sub-state machine when the message flow is in
 411  * MSG_FLOW_READING. The valid sub-states and transitions are:
 412  *
 413  * READ_STATE_HEADER <--+<-------------+
 414  *        |             |              |
 415  *        v             |              |
 416  * READ_STATE_BODY -----+-->READ_STATE_POST_PROCESS
 417  *        |                            |
 418  *        +----------------------------+
 419  *        v
 420  * [SUB_STATE_FINISHED]
 421  *
 422  * READ_STATE_HEADER has the responsibility for reading in the message header
 423  * and transitioning the state of the handshake state machine.
 424  *
 425  * READ_STATE_BODY reads in the rest of the message and then subsequently
 426  * processes it.
 427  *
 428  * READ_STATE_POST_PROCESS is an optional step that may occur if some post
 429  * processing activity performed on the message may block.
 430  *
 431  * Any of the above states could result in an NBIO event occurring in which case
 432  * control returns to the calling application. When this function is recalled we
 433  * will resume in the same state where we left off.
 434  */
 435 static SUB_STATE_RETURN read_state_machine(SSL *s)
 436 {
 437     OSSL_STATEM *st = &s->statem;
 438     int ret, mt;
 439     size_t len = 0;
 440     int (*transition) (SSL *s, int mt);
 441     PACKET pkt;
 442     MSG_PROCESS_RETURN(*process_message) (SSL *s, PACKET *pkt);
 443     WORK_STATE(*post_process_message) (SSL *s, WORK_STATE wst);
 444     size_t (*max_message_size) (SSL *s);
 445     void (*cb) (const SSL *ssl, int type, int val) = NULL;
 446
 447     cb = get_callback(s);
 448
 449     if (s->server) {
 450         transition = ossl_statem_server_read_transition;
 451         process_message = ossl_statem_server_process_message;
 452         max_message_size = ossl_statem_server_max_message_size;
 453         post_process_message = ossl_statem_server_post_process_message;
 454     } else {
 455         transition = ossl_statem_client_read_transition;
 456         process_message = ossl_statem_client_process_message;
 457         max_message_size = ossl_statem_client_max_message_size;
 458         post_process_message = ossl_statem_client_post_process_message;
 459     }
 460
 461     if (st->read_state_first_init) {
 462         s->first_packet = 1;
 463         st->read_state_first_init = 0;
 464     }
 465
 466     while (1) {
 467         switch (st->read_state) {
 468         case READ_STATE_HEADER:
 469             /* Get the state the peer wants to move to */
 470             if (SSL_IS_DTLS(s)) {
 471                 /*
 472                  * In DTLS we get the whole message in one go - header and body
 473                  */
 474                 ret = dtls_get_message(s, &mt, &len);
 475             } else {
 476                 ret = tls_get_message_header(s, &mt);
 477             }
 478
 479             if (ret == 0) {
 480                 /* Could be non-blocking IO */
 481                 return SUB_STATE_ERROR;
 482             }
 483
 484             if (cb != NULL) {
 485                 /* Notify callback of an impending state change */
 486                 if (s->server)
 487                     cb(s, SSL_CB_ACCEPT_LOOP, 1);
 488                 else
 489                     cb(s, SSL_CB_CONNECT_LOOP, 1);
 490             }
 491             /*
 492              * Validate that we are allowed to move to the new state and move
 493              * to that state if so
 494              */
 495             if (!transition(s, mt)) {
 496                 ossl_statem_set_error(s);
 497                 return SUB_STATE_ERROR;
 498             }
 499
 500             if (s->s3->tmp.message_size > max_message_size(s)) {
 501                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
 502                 SSLerr(SSL_F_READ_STATE_MACHINE, SSL_R_EXCESSIVE_MESSAGE_SIZE);
 503                 return SUB_STATE_ERROR;
 504             }
 505
 506             /* dtls_get_message already did this */
 507             if (!SSL_IS_DTLS(s)
 508                     && s->s3->tmp.message_size > 0
 509                     && !grow_init_buf(s, s->s3->tmp.message_size
 510                                          + SSL3_HM_HEADER_LENGTH)) {
 511                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
 512                 SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_BUF_LIB);
 513                 return SUB_STATE_ERROR;
 514             }
 515
 516             st->read_state = READ_STATE_BODY;
 517             /* Fall through */
 518
 519         case READ_STATE_BODY:
 520             if (!SSL_IS_DTLS(s)) {
 521                 /* We already got this above for DTLS */
 522                 ret = tls_get_message_body(s, &len);
 523                 if (ret == 0) {
 524                     /* Could be non-blocking IO */
 525                     return SUB_STATE_ERROR;
 526                 }
 527             }
 528
 529             s->first_packet = 0;
 530             if (!PACKET_buf_init(&pkt, s->init_msg, len)) {
 531                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
 532                 SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 533                 return SUB_STATE_ERROR;
 534             }
 535             ret = process_message(s, &pkt);
 536
 537             /* Discard the packet data */
 538             s->init_num = 0;
 539
 540             switch (ret) {
 541             case MSG_PROCESS_ERROR:
 542                 return SUB_STATE_ERROR;
 543
 544             case MSG_PROCESS_FINISHED_READING:
 545                 if (SSL_IS_DTLS(s)) {
 546                     dtls1_stop_timer(s);
 547                 }
 548                 return SUB_STATE_FINISHED;
 549
 550             case MSG_PROCESS_CONTINUE_PROCESSING:
 551                 st->read_state = READ_STATE_POST_PROCESS;
 552                 st->read_state_work = WORK_MORE_A;
 553                 break;
 554
 555             default:
 556                 st->read_state = READ_STATE_HEADER;
 557                 break;
 558             }
 559             break;
 560
 561         case READ_STATE_POST_PROCESS:
 562             st->read_state_work = post_process_message(s, st->read_state_work);
 563             switch (st->read_state_work) {
 564             case WORK_ERROR:
 565             case WORK_MORE_A:
 566             case WORK_MORE_B:
 567             case WORK_MORE_C:
 568                 return SUB_STATE_ERROR;
 569
 570             case WORK_FINISHED_CONTINUE:
 571                 st->read_state = READ_STATE_HEADER;
 572                 break;
 573
 574             case WORK_FINISHED_STOP:
 575                 if (SSL_IS_DTLS(s)) {
 576                     dtls1_stop_timer(s);
 577                 }
 578                 return SUB_STATE_FINISHED;
 579             }
 580             break;
 581
 582         default:
 583             /* Shouldn't happen */
 584             ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
 585             SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 586             ossl_statem_set_error(s);
 587             return SUB_STATE_ERROR;
 588         }
 589     }
 590 }
 591
 592 /*
 593  * Send a previously constructed message to the peer.
 594  */
 595 static int statem_do_write(SSL *s)
 596 {
 597     OSSL_STATEM *st = &s->statem;
 598
 599     if (st->hand_state == TLS_ST_CW_CHANGE
 600         || st->hand_state == TLS_ST_SW_CHANGE) {
 601         if (SSL_IS_DTLS(s))
 602             return dtls1_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
 603         else
 604             return ssl3_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
 605     } else {
 606         return ssl_do_write(s);
 607     }
 608 }
 609
 610 /*
 611  * Initialise the MSG_FLOW_WRITING sub-state machine
 612  */
 613 static void init_write_state_machine(SSL *s)
 614 {
 615     OSSL_STATEM *st = &s->statem;
 616
 617     st->write_state = WRITE_STATE_TRANSITION;
 618 }
 619
 620 /*
 621  * This function implements the sub-state machine when the message flow is in
 622  * MSG_FLOW_WRITING. The valid sub-states and transitions are:
 623  *
 624  * +-> WRITE_STATE_TRANSITION ------> [SUB_STATE_FINISHED]
 625  * |             |
 626  * |             v
 627  * |      WRITE_STATE_PRE_WORK -----> [SUB_STATE_END_HANDSHAKE]
 628  * |             |
 629  * |             v
 630  * |       WRITE_STATE_SEND
 631  * |             |
 632  * |             v
 633  * |     WRITE_STATE_POST_WORK
 634  * |             |
 635  * +-------------+
 636  *
 637  * WRITE_STATE_TRANSITION transitions the state of the handshake state machine
 638
 639  * WRITE_STATE_PRE_WORK performs any work necessary to prepare the later
 640  * sending of the message. This could result in an NBIO event occurring in
 641  * which case control returns to the calling application. When this function
 642  * is recalled we will resume in the same state where we left off.
 643  *
 644  * WRITE_STATE_SEND sends the message and performs any work to be done after
 645  * sending.
 646  *
 647  * WRITE_STATE_POST_WORK performs any work necessary after the sending of the
 648  * message has been completed. As for WRITE_STATE_PRE_WORK this could also
 649  * result in an NBIO event.
 650  */
 651 static SUB_STATE_RETURN write_state_machine(SSL *s)
 652 {
 653     OSSL_STATEM *st = &s->statem;
 654     int ret;
 655     WRITE_TRAN(*transition) (SSL *s);
 656     WORK_STATE(*pre_work) (SSL *s, WORK_STATE wst);
 657     WORK_STATE(*post_work) (SSL *s, WORK_STATE wst);
 658     int (*get_construct_message_f) (SSL *s, WPACKET *pkt,
 659                                     int (**confunc) (SSL *s, WPACKET *pkt),
 660                                     int *mt);
 661     void (*cb) (const SSL *ssl, int type, int val) = NULL;
 662     int (*confunc) (SSL *s, WPACKET *pkt);
 663     int mt;
 664     WPACKET pkt;
 665
 666     cb = get_callback(s);
 667
 668     if (s->server) {
 669         transition = ossl_statem_server_write_transition;
 670         pre_work = ossl_statem_server_pre_work;
 671         post_work = ossl_statem_server_post_work;
 672         get_construct_message_f = ossl_statem_server_construct_message;
 673     } else {
 674         transition = ossl_statem_client_write_transition;
 675         pre_work = ossl_statem_client_pre_work;
 676         post_work = ossl_statem_client_post_work;
 677         get_construct_message_f = ossl_statem_client_construct_message;
 678     }
 679
 680     while (1) {
 681         switch (st->write_state) {
 682         case WRITE_STATE_TRANSITION:
 683             if (cb != NULL) {
 684                 /* Notify callback of an impending state change */
 685                 if (s->server)
 686                     cb(s, SSL_CB_ACCEPT_LOOP, 1);
 687                 else
 688                     cb(s, SSL_CB_CONNECT_LOOP, 1);
 689             }
 690             switch (transition(s)) {
 691             case WRITE_TRAN_CONTINUE:
 692                 st->write_state = WRITE_STATE_PRE_WORK;
 693                 st->write_state_work = WORK_MORE_A;
 694                 break;
 695
 696             case WRITE_TRAN_FINISHED:
 697                 return SUB_STATE_FINISHED;
 698                 break;
 699
 700             case WRITE_TRAN_ERROR:
 701                 return SUB_STATE_ERROR;
 702             }
 703             break;
 704
 705         case WRITE_STATE_PRE_WORK:
 706             switch (st->write_state_work = pre_work(s, st->write_state_work)) {
 707             case WORK_ERROR:
 708             case WORK_MORE_A:
 709             case WORK_MORE_B:
 710             case WORK_MORE_C:
 711                 return SUB_STATE_ERROR;
 712
 713             case WORK_FINISHED_CONTINUE:
 714                 st->write_state = WRITE_STATE_SEND;
 715                 break;
 716
 717             case WORK_FINISHED_STOP:
 718                 return SUB_STATE_END_HANDSHAKE;
 719             }
 720             if (!WPACKET_init(&pkt, s->init_buf)
 721                     || !get_construct_message_f(s, &pkt, &confunc, &mt)
 722                     || !ssl_set_handshake_header(s, &pkt, mt)
 723                     || (confunc != NULL && !confunc(s, &pkt))
 724                     || !ssl_close_construct_packet(s, &pkt, mt)
 725                     || !WPACKET_finish(&pkt)) {
 726                 WPACKET_cleanup(&pkt);
 727                 ossl_statem_set_error(s);
 728                 return SUB_STATE_ERROR;
 729             }
 730
 731             /* Fall through */
 732
 733         case WRITE_STATE_SEND:
 734             if (SSL_IS_DTLS(s) && st->use_timer) {
 735                 dtls1_start_timer(s);
 736             }
 737             ret = statem_do_write(s);
 738             if (ret <= 0) {
 739                 return SUB_STATE_ERROR;
 740             }
 741             st->write_state = WRITE_STATE_POST_WORK;
 742             st->write_state_work = WORK_MORE_A;
 743             /* Fall through */
 744
 745         case WRITE_STATE_POST_WORK:
 746             switch (st->write_state_work = post_work(s, st->write_state_work)) {
 747             case WORK_ERROR:
 748             case WORK_MORE_A:
 749             case WORK_MORE_B:
 750             case WORK_MORE_C:
 751                 return SUB_STATE_ERROR;
 752
 753             case WORK_FINISHED_CONTINUE:
 754                 st->write_state = WRITE_STATE_TRANSITION;
 755                 break;
 756
 757             case WORK_FINISHED_STOP:
 758                 return SUB_STATE_END_HANDSHAKE;
 759             }
 760             break;
 761
 762         default:
 763             return SUB_STATE_ERROR;
 764         }
 765     }
 766 }
 767
 768 /*
 769  * Flush the write BIO
 770  */
 771 int statem_flush(SSL *s)
 772 {
 773     s->rwstate = SSL_WRITING;
 774     if (BIO_flush(s->wbio) <= 0) {
 775         return 0;
 776     }
 777     s->rwstate = SSL_NOTHING;
 778
 779     return 1;
 780 }
 781
 782 /*
 783  * Called by the record layer to determine whether application data is
 784  * allowed to be received in the current handshake state or not.
 785  *
 786  * Return values are:
 787  *   1: Yes (application data allowed)
 788  *   0: No (application data not allowed)
 789  */
 790 int ossl_statem_app_data_allowed(SSL *s)
 791 {
 792     OSSL_STATEM *st = &s->statem;
 793
 794     if (st->state == MSG_FLOW_UNINITED)
 795         return 0;
 796
 797     if (!s->s3->in_read_app_data || (s->s3->total_renegotiations == 0))
 798         return 0;
 799
 800     if (s->server) {
 801         /*
 802          * If we're a server and we haven't got as far as writing our
 803          * ServerHello yet then we allow app data
 804          */
 805         if (st->hand_state == TLS_ST_BEFORE
 806             || st->hand_state == TLS_ST_SR_CLNT_HELLO)
 807             return 1;
 808     } else {
 809         /*
 810          * If we're a client and we haven't read the ServerHello yet then we
 811          * allow app data
 812          */
 813         if (st->hand_state == TLS_ST_CW_CLNT_HELLO)
 814             return 1;
 815     }
 816
 817     return 0;
 818 }
 819
 820 #ifndef OPENSSL_NO_SCTP
 821 /*
 822  * Set flag used by SCTP to determine whether we are in the read sock state
 823  */
 824 void ossl_statem_set_sctp_read_sock(SSL *s, int read_sock)
 825 {
 826     s->statem.in_sctp_read_sock = read_sock;
 827 }
 828
 829 /*
 830  * Called by the record layer to determine whether we are in the read sock
 831  * state or not.
 832  *
 833  * Return values are:
 834  *   1: Yes (we are in the read sock state)
 835  *   0: No (we are not in the read sock state)
 836  */
 837 int ossl_statem_in_sctp_read_sock(SSL *s)
 838 {
 839     return s->statem.in_sctp_read_sock;
 840 }
 841 #endif