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.state = MSG_FLOW_RENEGOTIATE;
 109     s->statem.in_init = 1;
 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_RENEGOTIATE state and finish in MSG_FLOW_FINISHED. Valid states and
 193  * transitions are as follows:
 194  *
 195  * MSG_FLOW_UNINITED     MSG_FLOW_RENEGOTIATE
 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 #ifndef OPENSSL_NO_HEARTBEATS
 255     /*
 256      * If we're awaiting a HeartbeatResponse, pretend we already got and
 257      * don't await it anymore, because Heartbeats don't make sense during
 258      * handshakes anyway.
 259      */
 260     if (s->tlsext_hb_pending) {
 261         if (SSL_IS_DTLS(s))
 262             dtls1_stop_timer(s);
 263         s->tlsext_hb_pending = 0;
 264         s->tlsext_hb_seq++;
 265     }
 266 #endif
 267
 268     /* Initialise state machine */
 269
 270     if (st->state == MSG_FLOW_RENEGOTIATE) {
 271         s->renegotiate = 1;
 272         if (!server)
 273             s->ctx->stats.sess_connect_renegotiate++;
 274     }
 275
 276     if (st->state == MSG_FLOW_UNINITED || st->state == MSG_FLOW_RENEGOTIATE) {
 277         if (st->state == MSG_FLOW_UNINITED) {
 278             st->hand_state = TLS_ST_BEFORE;
 279         }
 280
 281         s->server = server;
 282         if (cb != NULL)
 283             cb(s, SSL_CB_HANDSHAKE_START, 1);
 284
 285         if (SSL_IS_DTLS(s)) {
 286             if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00) &&
 287                 (server || (s->version & 0xff00) != (DTLS1_BAD_VER & 0xff00))) {
 288                 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 289                 goto end;
 290             }
 291         } else {
 292             if ((s->version >> 8) != SSL3_VERSION_MAJOR) {
 293                 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 294                 goto end;
 295             }
 296         }
 297
 298         if (!ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL)) {
 299             SSLerr(SSL_F_STATE_MACHINE, SSL_R_VERSION_TOO_LOW);
 300             goto end;
 301         }
 302
 303         if (s->init_buf == NULL) {
 304             if ((buf = BUF_MEM_new()) == NULL) {
 305                 goto end;
 306             }
 307             if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {
 308                 goto end;
 309             }
 310             s->init_buf = buf;
 311             buf = NULL;
 312         }
 313
 314         if (!ssl3_setup_buffers(s)) {
 315             goto end;
 316         }
 317         s->init_num = 0;
 318
 319         /*
 320          * Should have been reset by tls_process_finished, too.
 321          */
 322         s->s3->change_cipher_spec = 0;
 323
 324         /*
 325          * Ok, we now need to push on a buffering BIO ...but not with
 326          * SCTP
 327          */
 328 #ifndef OPENSSL_NO_SCTP
 329         if (!SSL_IS_DTLS(s) || !BIO_dgram_is_sctp(SSL_get_wbio(s)))
 330 #endif
 331             if (!ssl_init_wbio_buffer(s)) {
 332                 goto end;
 333             }
 334
 335         if (!server || st->state != MSG_FLOW_RENEGOTIATE) {
 336             if (!ssl3_init_finished_mac(s)) {
 337                 ossl_statem_set_error(s);
 338                 goto end;
 339             }
 340         }
 341
 342         if (server) {
 343             if (st->state != MSG_FLOW_RENEGOTIATE) {
 344                 s->ctx->stats.sess_accept++;
 345             } else if (!s->s3->send_connection_binding &&
 346                        !(s->options &
 347                          SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION)) {
 348                 /*
 349                  * Server attempting to renegotiate with client that doesn't
 350                  * support secure renegotiation.
 351                  */
 352                 SSLerr(SSL_F_STATE_MACHINE,
 353                        SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
 354                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
 355                 ossl_statem_set_error(s);
 356                 goto end;
 357             } else {
 358                 /*
 359                  * st->state == MSG_FLOW_RENEGOTIATE, we will just send a
 360                  * HelloRequest
 361                  */
 362                 s->ctx->stats.sess_accept_renegotiate++;
 363             }
 364
 365             s->s3->tmp.cert_request = 0;
 366         } else {
 367             s->ctx->stats.sess_connect++;
 368
 369             /* mark client_random uninitialized */
 370             memset(s->s3->client_random, 0, sizeof(s->s3->client_random));
 371             s->hit = 0;
 372
 373             s->s3->tmp.cert_req = 0;
 374
 375             if (SSL_IS_DTLS(s)) {
 376                 st->use_timer = 1;
 377             }
 378         }
 379
 380         st->state = MSG_FLOW_WRITING;
 381         init_write_state_machine(s);
 382         st->read_state_first_init = 1;
 383     }
 384
 385     while (st->state != MSG_FLOW_FINISHED) {
 386         if (st->state == MSG_FLOW_READING) {
 387             ssret = read_state_machine(s);
 388             if (ssret == SUB_STATE_FINISHED) {
 389                 st->state = MSG_FLOW_WRITING;
 390                 init_write_state_machine(s);
 391             } else {
 392                 /* NBIO or error */
 393                 goto end;
 394             }
 395         } else if (st->state == MSG_FLOW_WRITING) {
 396             ssret = write_state_machine(s);
 397             if (ssret == SUB_STATE_FINISHED) {
 398                 st->state = MSG_FLOW_READING;
 399                 init_read_state_machine(s);
 400             } else if (ssret == SUB_STATE_END_HANDSHAKE) {
 401                 st->state = MSG_FLOW_FINISHED;
 402             } else {
 403                 /* NBIO or error */
 404                 goto end;
 405             }
 406         } else {
 407             /* Error */
 408             ossl_statem_set_error(s);
 409             goto end;
 410         }
 411     }
 412
 413     st->state = MSG_FLOW_UNINITED;
 414     ret = 1;
 415
 416  end:
 417     st->in_handshake--;
 418
 419 #ifndef OPENSSL_NO_SCTP
 420     if (SSL_IS_DTLS(s)) {
 421         /*
 422          * Notify SCTP BIO socket to leave handshake mode and allow stream
 423          * identifier other than 0. Will be ignored if no SCTP is used.
 424          */
 425         BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
 426                  st->in_handshake, NULL);
 427     }
 428 #endif
 429
 430     BUF_MEM_free(buf);
 431     if (cb != NULL) {
 432         if (server)
 433             cb(s, SSL_CB_ACCEPT_EXIT, ret);
 434         else
 435             cb(s, SSL_CB_CONNECT_EXIT, ret);
 436     }
 437     return ret;
 438 }
 439
 440 /*
 441  * Initialise the MSG_FLOW_READING sub-state machine
 442  */
 443 static void init_read_state_machine(SSL *s)
 444 {
 445     OSSL_STATEM *st = &s->statem;
 446
 447     st->read_state = READ_STATE_HEADER;
 448 }
 449
 450 static int grow_init_buf(SSL *s, size_t size) {
 451
 452     size_t msg_offset = (char *)s->init_msg - s->init_buf->data;
 453
 454     if (!BUF_MEM_grow_clean(s->init_buf, (int)size))
 455         return 0;
 456
 457     if (size < msg_offset)
 458         return 0;
 459
 460     s->init_msg = s->init_buf->data + msg_offset;
 461
 462     return 1;
 463 }
 464
 465 /*
 466  * This function implements the sub-state machine when the message flow is in
 467  * MSG_FLOW_READING. The valid sub-states and transitions are:
 468  *
 469  * READ_STATE_HEADER <--+<-------------+
 470  *        |             |              |
 471  *        v             |              |
 472  * READ_STATE_BODY -----+-->READ_STATE_POST_PROCESS
 473  *        |                            |
 474  *        +----------------------------+
 475  *        v
 476  * [SUB_STATE_FINISHED]
 477  *
 478  * READ_STATE_HEADER has the responsibility for reading in the message header
 479  * and transitioning the state of the handshake state machine.
 480  *
 481  * READ_STATE_BODY reads in the rest of the message and then subsequently
 482  * processes it.
 483  *
 484  * READ_STATE_POST_PROCESS is an optional step that may occur if some post
 485  * processing activity performed on the message may block.
 486  *
 487  * Any of the above states could result in an NBIO event occurring in which case
 488  * control returns to the calling application. When this function is recalled we
 489  * will resume in the same state where we left off.
 490  */
 491 static SUB_STATE_RETURN read_state_machine(SSL *s)
 492 {
 493     OSSL_STATEM *st = &s->statem;
 494     int ret, mt;
 495     unsigned long len = 0;
 496     int (*transition) (SSL *s, int mt);
 497     PACKET pkt;
 498     MSG_PROCESS_RETURN(*process_message) (SSL *s, PACKET *pkt);
 499     WORK_STATE(*post_process_message) (SSL *s, WORK_STATE wst);
 500     unsigned long (*max_message_size) (SSL *s);
 501     void (*cb) (const SSL *ssl, int type, int val) = NULL;
 502
 503     cb = get_callback(s);
 504
 505     if (s->server) {
 506         transition = ossl_statem_server_read_transition;
 507         process_message = ossl_statem_server_process_message;
 508         max_message_size = ossl_statem_server_max_message_size;
 509         post_process_message = ossl_statem_server_post_process_message;
 510     } else {
 511         transition = ossl_statem_client_read_transition;
 512         process_message = ossl_statem_client_process_message;
 513         max_message_size = ossl_statem_client_max_message_size;
 514         post_process_message = ossl_statem_client_post_process_message;
 515     }
 516
 517     if (st->read_state_first_init) {
 518         s->first_packet = 1;
 519         st->read_state_first_init = 0;
 520     }
 521
 522     while (1) {
 523         switch (st->read_state) {
 524         case READ_STATE_HEADER:
 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                 ossl_statem_set_error(s);
 553                 return SUB_STATE_ERROR;
 554             }
 555
 556             if (s->s3->tmp.message_size > max_message_size(s)) {
 557                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
 558                 SSLerr(SSL_F_READ_STATE_MACHINE, SSL_R_EXCESSIVE_MESSAGE_SIZE);
 559                 return SUB_STATE_ERROR;
 560             }
 561
 562             /* dtls_get_message already did this */
 563             if (!SSL_IS_DTLS(s)
 564                     && s->s3->tmp.message_size > 0
 565                     && !grow_init_buf(s, s->s3->tmp.message_size
 566                                          + SSL3_HM_HEADER_LENGTH)) {
 567                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
 568                 SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_BUF_LIB);
 569                 return SUB_STATE_ERROR;
 570             }
 571
 572             st->read_state = READ_STATE_BODY;
 573             /* Fall through */
 574
 575         case READ_STATE_BODY:
 576             if (!SSL_IS_DTLS(s)) {
 577                 /* We already got this above for DTLS */
 578                 ret = tls_get_message_body(s, &len);
 579                 if (ret == 0) {
 580                     /* Could be non-blocking IO */
 581                     return SUB_STATE_ERROR;
 582                 }
 583             }
 584
 585             s->first_packet = 0;
 586             if (!PACKET_buf_init(&pkt, s->init_msg, len)) {
 587                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
 588                 SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 589                 return SUB_STATE_ERROR;
 590             }
 591             ret = process_message(s, &pkt);
 592
 593             /* Discard the packet data */
 594             s->init_num = 0;
 595
 596             switch (ret) {
 597             case MSG_PROCESS_ERROR:
 598                 return SUB_STATE_ERROR;
 599
 600             case MSG_PROCESS_FINISHED_READING:
 601                 if (SSL_IS_DTLS(s)) {
 602                     dtls1_stop_timer(s);
 603                 }
 604                 return SUB_STATE_FINISHED;
 605
 606             case MSG_PROCESS_CONTINUE_PROCESSING:
 607                 st->read_state = READ_STATE_POST_PROCESS;
 608                 st->read_state_work = WORK_MORE_A;
 609                 break;
 610
 611             default:
 612                 st->read_state = READ_STATE_HEADER;
 613                 break;
 614             }
 615             break;
 616
 617         case READ_STATE_POST_PROCESS:
 618             st->read_state_work = post_process_message(s, st->read_state_work);
 619             switch (st->read_state_work) {
 620             default:
 621                 return SUB_STATE_ERROR;
 622
 623             case WORK_FINISHED_CONTINUE:
 624                 st->read_state = READ_STATE_HEADER;
 625                 break;
 626
 627             case WORK_FINISHED_STOP:
 628                 if (SSL_IS_DTLS(s)) {
 629                     dtls1_stop_timer(s);
 630                 }
 631                 return SUB_STATE_FINISHED;
 632             }
 633             break;
 634
 635         default:
 636             /* Shouldn't happen */
 637             ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
 638             SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 639             ossl_statem_set_error(s);
 640             return SUB_STATE_ERROR;
 641         }
 642     }
 643 }
 644
 645 /*
 646  * Send a previously constructed message to the peer.
 647  */
 648 static int statem_do_write(SSL *s)
 649 {
 650     OSSL_STATEM *st = &s->statem;
 651
 652     if (st->hand_state == TLS_ST_CW_CHANGE
 653         || st->hand_state == TLS_ST_SW_CHANGE) {
 654         if (SSL_IS_DTLS(s))
 655             return dtls1_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
 656         else
 657             return ssl3_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
 658     } else {
 659         return ssl_do_write(s);
 660     }
 661 }
 662
 663 /*
 664  * Initialise the MSG_FLOW_WRITING sub-state machine
 665  */
 666 static void init_write_state_machine(SSL *s)
 667 {
 668     OSSL_STATEM *st = &s->statem;
 669
 670     st->write_state = WRITE_STATE_TRANSITION;
 671 }
 672
 673 /*
 674  * This function implements the sub-state machine when the message flow is in
 675  * MSG_FLOW_WRITING. The valid sub-states and transitions are:
 676  *
 677  * +-> WRITE_STATE_TRANSITION ------> [SUB_STATE_FINISHED]
 678  * |             |
 679  * |             v
 680  * |      WRITE_STATE_PRE_WORK -----> [SUB_STATE_END_HANDSHAKE]
 681  * |             |
 682  * |             v
 683  * |       WRITE_STATE_SEND
 684  * |             |
 685  * |             v
 686  * |     WRITE_STATE_POST_WORK
 687  * |             |
 688  * +-------------+
 689  *
 690  * WRITE_STATE_TRANSITION transitions the state of the handshake state machine
 691
 692  * WRITE_STATE_PRE_WORK performs any work necessary to prepare the later
 693  * sending of the message. This could result in an NBIO event occurring in
 694  * which case control returns to the calling application. When this function
 695  * is recalled we will resume in the same state where we left off.
 696  *
 697  * WRITE_STATE_SEND sends the message and performs any work to be done after
 698  * sending.
 699  *
 700  * WRITE_STATE_POST_WORK performs any work necessary after the sending of the
 701  * message has been completed. As for WRITE_STATE_PRE_WORK this could also
 702  * result in an NBIO event.
 703  */
 704 static SUB_STATE_RETURN write_state_machine(SSL *s)
 705 {
 706     OSSL_STATEM *st = &s->statem;
 707     int ret;
 708     WRITE_TRAN(*transition) (SSL *s);
 709     WORK_STATE(*pre_work) (SSL *s, WORK_STATE wst);
 710     WORK_STATE(*post_work) (SSL *s, WORK_STATE wst);
 711     int (*construct_message) (SSL *s);
 712     void (*cb) (const SSL *ssl, int type, int val) = NULL;
 713
 714     cb = get_callback(s);
 715
 716     if (s->server) {
 717         transition = ossl_statem_server_write_transition;
 718         pre_work = ossl_statem_server_pre_work;
 719         post_work = ossl_statem_server_post_work;
 720         construct_message = ossl_statem_server_construct_message;
 721     } else {
 722         transition = ossl_statem_client_write_transition;
 723         pre_work = ossl_statem_client_pre_work;
 724         post_work = ossl_statem_client_post_work;
 725         construct_message = ossl_statem_client_construct_message;
 726     }
 727
 728     while (1) {
 729         switch (st->write_state) {
 730         case WRITE_STATE_TRANSITION:
 731             if (cb != NULL) {
 732                 /* Notify callback of an impending state change */
 733                 if (s->server)
 734                     cb(s, SSL_CB_ACCEPT_LOOP, 1);
 735                 else
 736                     cb(s, SSL_CB_CONNECT_LOOP, 1);
 737             }
 738             switch (transition(s)) {
 739             case WRITE_TRAN_CONTINUE:
 740                 st->write_state = WRITE_STATE_PRE_WORK;
 741                 st->write_state_work = WORK_MORE_A;
 742                 break;
 743
 744             case WRITE_TRAN_FINISHED:
 745                 return SUB_STATE_FINISHED;
 746                 break;
 747
 748             default:
 749                 return SUB_STATE_ERROR;
 750             }
 751             break;
 752
 753         case WRITE_STATE_PRE_WORK:
 754             switch (st->write_state_work = pre_work(s, st->write_state_work)) {
 755             default:
 756                 return SUB_STATE_ERROR;
 757
 758             case WORK_FINISHED_CONTINUE:
 759                 st->write_state = WRITE_STATE_SEND;
 760                 break;
 761
 762             case WORK_FINISHED_STOP:
 763                 return SUB_STATE_END_HANDSHAKE;
 764             }
 765             if (construct_message(s) == 0)
 766                 return SUB_STATE_ERROR;
 767
 768             /* Fall through */
 769
 770         case WRITE_STATE_SEND:
 771             if (SSL_IS_DTLS(s) && st->use_timer) {
 772                 dtls1_start_timer(s);
 773             }
 774             ret = statem_do_write(s);
 775             if (ret <= 0) {
 776                 return SUB_STATE_ERROR;
 777             }
 778             st->write_state = WRITE_STATE_POST_WORK;
 779             st->write_state_work = WORK_MORE_A;
 780             /* Fall through */
 781
 782         case WRITE_STATE_POST_WORK:
 783             switch (st->write_state_work = post_work(s, st->write_state_work)) {
 784             default:
 785                 return SUB_STATE_ERROR;
 786
 787             case WORK_FINISHED_CONTINUE:
 788                 st->write_state = WRITE_STATE_TRANSITION;
 789                 break;
 790
 791             case WORK_FINISHED_STOP:
 792                 return SUB_STATE_END_HANDSHAKE;
 793             }
 794             break;
 795
 796         default:
 797             return SUB_STATE_ERROR;
 798         }
 799     }
 800 }
 801
 802 /*
 803  * Flush the write BIO
 804  */
 805 int statem_flush(SSL *s)
 806 {
 807     s->rwstate = SSL_WRITING;
 808     if (BIO_flush(s->wbio) <= 0) {
 809         return 0;
 810     }
 811     s->rwstate = SSL_NOTHING;
 812
 813     return 1;
 814 }
 815
 816 /*
 817  * Called by the record layer to determine whether application data is
 818  * allowed to be sent in the current handshake state or not.
 819  *
 820  * Return values are:
 821  *   1: Yes (application data allowed)
 822  *   0: No (application data not allowed)
 823  */
 824 int ossl_statem_app_data_allowed(SSL *s)
 825 {
 826     OSSL_STATEM *st = &s->statem;
 827
 828     if (st->state == MSG_FLOW_UNINITED || st->state == MSG_FLOW_RENEGOTIATE)
 829         return 0;
 830
 831     if (!s->s3->in_read_app_data || (s->s3->total_renegotiations == 0))
 832         return 0;
 833
 834     if (s->server) {
 835         /*
 836          * If we're a server and we haven't got as far as writing our
 837          * ServerHello yet then we allow app data
 838          */
 839         if (st->hand_state == TLS_ST_BEFORE
 840             || st->hand_state == TLS_ST_SR_CLNT_HELLO)
 841             return 1;
 842     } else {
 843         /*
 844          * If we're a client and we haven't read the ServerHello yet then we
 845          * allow app data
 846          */
 847         if (st->hand_state == TLS_ST_CW_CLNT_HELLO)
 848             return 1;
 849     }
 850
 851     return 0;
 852 }
 853
 854 #ifndef OPENSSL_NO_SCTP
 855 /*
 856  * Set flag used by SCTP to determine whether we are in the read sock state
 857  */
 858 void ossl_statem_set_sctp_read_sock(SSL *s, int read_sock)
 859 {
 860     s->statem.in_sctp_read_sock = read_sock;
 861 }
 862
 863 /*
 864  * Called by the record layer to determine whether we are in the read sock
 865  * state or not.
 866  *
 867  * Return values are:
 868  *   1: Yes (we are in the read sock state)
 869  *   0: No (we are not in the read sock state)
 870  */
 871 int ossl_statem_in_sctp_read_sock(SSL *s)
 872 {
 873     return s->statem.in_sctp_read_sock;
 874 }
 875 #endif