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     return state_machine(s, 0);
 170 }
 171
 172 int ossl_statem_accept(SSL *s)
 173 {
 174     return state_machine(s, 1);
 175 }
 176
 177 static void (*get_callback(SSL *s))(const SSL *, int, int)
 178 {
 179     if (s->info_callback != NULL)
 180         return s->info_callback;
 181     else if (s->ctx->info_callback != NULL)
 182         return s->ctx->info_callback;
 183
 184     return NULL;
 185 }
 186
 187 /*
 188  * The main message flow state machine. We start in the MSG_FLOW_UNINITED or
 189  * MSG_FLOW_RENEGOTIATE state and finish in MSG_FLOW_FINISHED. Valid states and
 190  * transitions are as follows:
 191  *
 192  * MSG_FLOW_UNINITED     MSG_FLOW_RENEGOTIATE
 193  *        |                       |
 194  *        +-----------------------+
 195  *        v
 196  * MSG_FLOW_WRITING <---> MSG_FLOW_READING
 197  *        |
 198  *        V
 199  * MSG_FLOW_FINISHED
 200  *        |
 201  *        V
 202  *    [SUCCESS]
 203  *
 204  * We may exit at any point due to an error or NBIO event. If an NBIO event
 205  * occurs then we restart at the point we left off when we are recalled.
 206  * MSG_FLOW_WRITING and MSG_FLOW_READING have sub-state machines associated with them.
 207  *
 208  * In addition to the above there is also the MSG_FLOW_ERROR state. We can move
 209  * into that state at any point in the event that an irrecoverable error occurs.
 210  *
 211  * Valid return values are:
 212  *   1: Success
 213  * <=0: NBIO or error
 214  */
 215 static int state_machine(SSL *s, int server)
 216 {
 217     BUF_MEM *buf = NULL;
 218     unsigned long Time = (unsigned long)time(NULL);
 219     void (*cb) (const SSL *ssl, int type, int val) = NULL;
 220     OSSL_STATEM *st = &s->statem;
 221     int ret = -1;
 222     int ssret;
 223
 224     if (st->state == MSG_FLOW_ERROR) {
 225         /* Shouldn't have been called if we're already in the error state */
 226         return -1;
 227     }
 228
 229     RAND_add(&Time, sizeof(Time), 0);
 230     ERR_clear_error();
 231     clear_sys_error();
 232
 233     cb = get_callback(s);
 234
 235     st->in_handshake++;
 236     if (!SSL_in_init(s) || SSL_in_before(s)) {
 237         if (!SSL_clear(s))
 238             return -1;
 239     }
 240
 241 #ifndef OPENSSL_NO_SCTP
 242     if (SSL_IS_DTLS(s)) {
 243         /*
 244          * Notify SCTP BIO socket to enter handshake mode and prevent stream
 245          * identifier other than 0. Will be ignored if no SCTP is used.
 246          */
 247         BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
 248                  st->in_handshake, NULL);
 249     }
 250 #endif
 251
 252 #ifndef OPENSSL_NO_HEARTBEATS
 253     /*
 254      * If we're awaiting a HeartbeatResponse, pretend we already got and
 255      * don't await it anymore, because Heartbeats don't make sense during
 256      * handshakes anyway.
 257      */
 258     if (s->tlsext_hb_pending) {
 259         if (SSL_IS_DTLS(s))
 260             dtls1_stop_timer(s);
 261         s->tlsext_hb_pending = 0;
 262         s->tlsext_hb_seq++;
 263     }
 264 #endif
 265
 266     /* Initialise state machine */
 267
 268     if (st->state == MSG_FLOW_RENEGOTIATE) {
 269         s->renegotiate = 1;
 270         if (!server)
 271             s->ctx->stats.sess_connect_renegotiate++;
 272     }
 273
 274     if (st->state == MSG_FLOW_UNINITED || st->state == MSG_FLOW_RENEGOTIATE) {
 275         if (st->state == MSG_FLOW_UNINITED) {
 276             st->hand_state = TLS_ST_BEFORE;
 277         }
 278
 279         s->server = server;
 280         if (cb != NULL)
 281             cb(s, SSL_CB_HANDSHAKE_START, 1);
 282
 283         if (SSL_IS_DTLS(s)) {
 284             if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00) &&
 285                     (server
 286                     || (s->version & 0xff00) != (DTLS1_BAD_VER & 0xff00))) {
 287                 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 288                 goto end;
 289             }
 290         } else {
 291             if ((s->version >> 8) != SSL3_VERSION_MAJOR) {
 292                 SSLerr(SSL_F_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 293                 goto end;
 294             }
 295         }
 296
 297         if (!ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL)) {
 298             SSLerr(SSL_F_STATE_MACHINE, SSL_R_VERSION_TOO_LOW);
 299             goto end;
 300         }
 301
 302         if (s->init_buf == NULL) {
 303             if ((buf = BUF_MEM_new()) == NULL) {
 304                 goto end;
 305             }
 306             if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {
 307                 goto end;
 308             }
 309             s->init_buf = buf;
 310             buf = NULL;
 311         }
 312
 313         if (!ssl3_setup_buffers(s)) {
 314             goto end;
 315         }
 316         s->init_num = 0;
 317
 318         /*
 319          * Should have been reset by tls_process_finished, too.
 320          */
 321         s->s3->change_cipher_spec = 0;
 322
 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         } else {
 365             s->ctx->stats.sess_connect++;
 366
 367             /* mark client_random uninitialized */
 368             memset(s->s3->client_random, 0, sizeof(s->s3->client_random));
 369             s->hit = 0;
 370
 371             s->s3->tmp.cert_request = 0;
 372
 373             if (SSL_IS_DTLS(s)) {
 374                 st->use_timer = 1;
 375             }
 376         }
 377
 378         st->state = MSG_FLOW_WRITING;
 379         init_write_state_machine(s);
 380         st->read_state_first_init = 1;
 381     }
 382
 383     while(st->state != MSG_FLOW_FINISHED) {
 384         if(st->state == MSG_FLOW_READING) {
 385             ssret = read_state_machine(s);
 386             if (ssret == SUB_STATE_FINISHED) {
 387                 st->state = MSG_FLOW_WRITING;
 388                 init_write_state_machine(s);
 389             } else {
 390                 /* NBIO or error */
 391                 goto end;
 392             }
 393         } else if (st->state == MSG_FLOW_WRITING) {
 394             ssret = write_state_machine(s);
 395             if (ssret == SUB_STATE_FINISHED) {
 396                 st->state = MSG_FLOW_READING;
 397                 init_read_state_machine(s);
 398             } else if (ssret == SUB_STATE_END_HANDSHAKE) {
 399                 st->state = MSG_FLOW_FINISHED;
 400             } else {
 401                 /* NBIO or error */
 402                 goto end;
 403             }
 404         } else {
 405             /* Error */
 406             ossl_statem_set_error(s);
 407             goto end;
 408         }
 409     }
 410
 411     st->state = MSG_FLOW_UNINITED;
 412     ret = 1;
 413
 414  end:
 415     st->in_handshake--;
 416
 417 #ifndef OPENSSL_NO_SCTP
 418     if (SSL_IS_DTLS(s)) {
 419         /*
 420          * Notify SCTP BIO socket to leave handshake mode and allow stream
 421          * identifier other than 0. Will be ignored if no SCTP is used.
 422          */
 423         BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,
 424                  st->in_handshake, NULL);
 425     }
 426 #endif
 427
 428     BUF_MEM_free(buf);
 429     if (cb != NULL) {
 430         if (server)
 431             cb(s, SSL_CB_ACCEPT_EXIT, ret);
 432         else
 433             cb(s, SSL_CB_CONNECT_EXIT, ret);
 434     }
 435     return ret;
 436 }
 437
 438 /*
 439  * Initialise the MSG_FLOW_READING sub-state machine
 440  */
 441 static void init_read_state_machine(SSL *s)
 442 {
 443     OSSL_STATEM *st = &s->statem;
 444
 445     st->read_state = READ_STATE_HEADER;
 446 }
 447
 448 /*
 449  * This function implements the sub-state machine when the message flow is in
 450  * MSG_FLOW_READING. The valid sub-states and transitions are:
 451  *
 452  * READ_STATE_HEADER <--+<-------------+
 453  *        |             |              |
 454  *        v             |              |
 455  * READ_STATE_BODY -----+-->READ_STATE_POST_PROCESS
 456  *        |                            |
 457  *        +----------------------------+
 458  *        v
 459  * [SUB_STATE_FINISHED]
 460  *
 461  * READ_STATE_HEADER has the responsibility for reading in the message header
 462  * and transitioning the state of the handshake state machine.
 463  *
 464  * READ_STATE_BODY reads in the rest of the message and then subsequently
 465  * processes it.
 466  *
 467  * READ_STATE_POST_PROCESS is an optional step that may occur if some post
 468  * processing activity performed on the message may block.
 469  *
 470  * Any of the above states could result in an NBIO event occurring in which case
 471  * control returns to the calling application. When this function is recalled we
 472  * will resume in the same state where we left off.
 473  */
 474 static SUB_STATE_RETURN read_state_machine(SSL *s) {
 475     OSSL_STATEM *st = &s->statem;
 476     int ret, mt;
 477     unsigned long len = 0;
 478     int (*transition)(SSL *s, int mt);
 479     PACKET pkt;
 480     MSG_PROCESS_RETURN (*process_message)(SSL *s, PACKET *pkt);
 481     WORK_STATE (*post_process_message)(SSL *s, WORK_STATE wst);
 482     unsigned long (*max_message_size)(SSL *s);
 483     void (*cb) (const SSL *ssl, int type, int val) = NULL;
 484
 485     cb = get_callback(s);
 486
 487     if(s->server) {
 488         transition = ossl_statem_server_read_transition;
 489         process_message = ossl_statem_server_process_message;
 490         max_message_size = ossl_statem_server_max_message_size;
 491         post_process_message = ossl_statem_server_post_process_message;
 492     } else {
 493         transition = ossl_statem_client_read_transition;
 494         process_message = ossl_statem_client_process_message;
 495         max_message_size = ossl_statem_client_max_message_size;
 496         post_process_message = ossl_statem_client_post_process_message;
 497     }
 498
 499     if (st->read_state_first_init) {
 500         s->first_packet = 1;
 501         st->read_state_first_init = 0;
 502     }
 503
 504     while(1) {
 505         switch(st->read_state) {
 506         case READ_STATE_HEADER:
 507             /* Get the state the peer wants to move to */
 508             if (SSL_IS_DTLS(s)) {
 509                 /*
 510                  * In DTLS we get the whole message in one go - header and body
 511                  */
 512                 ret = dtls_get_message(s, &mt, &len);
 513             } else {
 514                 ret = tls_get_message_header(s, &mt);
 515             }
 516
 517             if (ret == 0) {
 518                 /* Could be non-blocking IO */
 519                 return SUB_STATE_ERROR;
 520             }
 521
 522             if (cb != NULL) {
 523                 /* Notify callback of an impending state change */
 524                 if (s->server)
 525                     cb(s, SSL_CB_ACCEPT_LOOP, 1);
 526                 else
 527                     cb(s, SSL_CB_CONNECT_LOOP, 1);
 528             }
 529             /*
 530              * Validate that we are allowed to move to the new state and move
 531              * to that state if so
 532              */
 533             if(!transition(s, mt)) {
 534                 ossl_statem_set_error(s);
 535                 return SUB_STATE_ERROR;
 536             }
 537
 538             if (s->s3->tmp.message_size > max_message_size(s)) {
 539                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
 540                 SSLerr(SSL_F_READ_STATE_MACHINE, SSL_R_EXCESSIVE_MESSAGE_SIZE);
 541                 return SUB_STATE_ERROR;
 542             }
 543
 544             st->read_state = READ_STATE_BODY;
 545             /* Fall through */
 546
 547         case READ_STATE_BODY:
 548             if (!SSL_IS_DTLS(s)) {
 549                 /* We already got this above for DTLS */
 550                 ret = tls_get_message_body(s, &len);
 551                 if (ret == 0) {
 552                     /* Could be non-blocking IO */
 553                     return SUB_STATE_ERROR;
 554                 }
 555             }
 556
 557             s->first_packet = 0;
 558             if (!PACKET_buf_init(&pkt, s->init_msg, len)) {
 559                 ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
 560                 SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 561                 return SUB_STATE_ERROR;
 562             }
 563             ret = process_message(s, &pkt);
 564
 565             /* Discard the packet data */
 566             s->init_num = 0;
 567
 568             if (ret == MSG_PROCESS_ERROR) {
 569                 return SUB_STATE_ERROR;
 570             }
 571
 572             if (ret == MSG_PROCESS_FINISHED_READING) {
 573                 if (SSL_IS_DTLS(s)) {
 574                     dtls1_stop_timer(s);
 575                 }
 576                 return SUB_STATE_FINISHED;
 577             }
 578
 579             if (ret == MSG_PROCESS_CONTINUE_PROCESSING) {
 580                 st->read_state = READ_STATE_POST_PROCESS;
 581                 st->read_state_work = WORK_MORE_A;
 582             } else {
 583                 st->read_state = READ_STATE_HEADER;
 584             }
 585             break;
 586
 587         case READ_STATE_POST_PROCESS:
 588             st->read_state_work = post_process_message(s, st->read_state_work);
 589             switch(st->read_state_work) {
 590             default:
 591                 return SUB_STATE_ERROR;
 592
 593             case WORK_FINISHED_CONTINUE:
 594                 st->read_state = READ_STATE_HEADER;
 595                 break;
 596
 597             case WORK_FINISHED_STOP:
 598                 if (SSL_IS_DTLS(s)) {
 599                     dtls1_stop_timer(s);
 600                 }
 601                 return SUB_STATE_FINISHED;
 602             }
 603             break;
 604
 605         default:
 606             /* Shouldn't happen */
 607             ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
 608             SSLerr(SSL_F_READ_STATE_MACHINE, ERR_R_INTERNAL_ERROR);
 609             ossl_statem_set_error(s);
 610             return SUB_STATE_ERROR;
 611         }
 612     }
 613 }
 614
 615 /*
 616  * Send a previously constructed message to the peer.
 617  */
 618 static int statem_do_write(SSL *s)
 619 {
 620     OSSL_STATEM *st = &s->statem;
 621
 622     if (st->hand_state == TLS_ST_CW_CHANGE
 623             || st->hand_state == TLS_ST_SW_CHANGE) {
 624         if (SSL_IS_DTLS(s))
 625             return dtls1_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
 626         else
 627             return ssl3_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);
 628     } else {
 629         return ssl_do_write(s);
 630     }
 631 }
 632
 633 /*
 634  * Initialise the MSG_FLOW_WRITING sub-state machine
 635  */
 636 static void init_write_state_machine(SSL *s)
 637 {
 638     OSSL_STATEM *st = &s->statem;
 639
 640     st->write_state = WRITE_STATE_TRANSITION;
 641 }
 642
 643 /*
 644  * This function implements the sub-state machine when the message flow is in
 645  * MSG_FLOW_WRITING. The valid sub-states and transitions are:
 646  *
 647  * +-> WRITE_STATE_TRANSITION ------> [SUB_STATE_FINISHED]
 648  * |             |
 649  * |             v
 650  * |      WRITE_STATE_PRE_WORK -----> [SUB_STATE_END_HANDSHAKE]
 651  * |             |
 652  * |             v
 653  * |       WRITE_STATE_SEND
 654  * |             |
 655  * |             v
 656  * |     WRITE_STATE_POST_WORK
 657  * |             |
 658  * +-------------+
 659  *
 660  * WRITE_STATE_TRANSITION transitions the state of the handshake state machine
 661
 662  * WRITE_STATE_PRE_WORK performs any work necessary to prepare the later
 663  * sending of the message. This could result in an NBIO event occurring in
 664  * which case control returns to the calling application. When this function
 665  * is recalled we will resume in the same state where we left off.
 666  *
 667  * WRITE_STATE_SEND sends the message and performs any work to be done after
 668  * sending.
 669  *
 670  * WRITE_STATE_POST_WORK performs any work necessary after the sending of the
 671  * message has been completed. As for WRITE_STATE_PRE_WORK this could also
 672  * result in an NBIO event.
 673  */
 674 static SUB_STATE_RETURN write_state_machine(SSL *s)
 675 {
 676     OSSL_STATEM *st = &s->statem;
 677     int ret;
 678     WRITE_TRAN (*transition)(SSL *s);
 679     WORK_STATE (*pre_work)(SSL *s, WORK_STATE wst);
 680     WORK_STATE (*post_work)(SSL *s, WORK_STATE wst);
 681     int (*construct_message)(SSL *s);
 682     void (*cb) (const SSL *ssl, int type, int val) = NULL;
 683
 684     cb = get_callback(s);
 685
 686     if(s->server) {
 687         transition = ossl_statem_server_write_transition;
 688         pre_work = ossl_statem_server_pre_work;
 689         post_work = ossl_statem_server_post_work;
 690         construct_message = ossl_statem_server_construct_message;
 691     } else {
 692         transition = ossl_statem_client_write_transition;
 693         pre_work = ossl_statem_client_pre_work;
 694         post_work = ossl_statem_client_post_work;
 695         construct_message = ossl_statem_client_construct_message;
 696     }
 697
 698     while(1) {
 699         switch(st->write_state) {
 700         case WRITE_STATE_TRANSITION:
 701             if (cb != NULL) {
 702                 /* Notify callback of an impending state change */
 703                 if (s->server)
 704                     cb(s, SSL_CB_ACCEPT_LOOP, 1);
 705                 else
 706                     cb(s, SSL_CB_CONNECT_LOOP, 1);
 707             }
 708             switch(transition(s)) {
 709             case WRITE_TRAN_CONTINUE:
 710                 st->write_state = WRITE_STATE_PRE_WORK;
 711                 st->write_state_work = WORK_MORE_A;
 712                 break;
 713
 714             case WRITE_TRAN_FINISHED:
 715                 return SUB_STATE_FINISHED;
 716                 break;
 717
 718             default:
 719                 return SUB_STATE_ERROR;
 720             }
 721             break;
 722
 723         case WRITE_STATE_PRE_WORK:
 724             switch(st->write_state_work = pre_work(s, st->write_state_work)) {
 725             default:
 726                 return SUB_STATE_ERROR;
 727
 728             case WORK_FINISHED_CONTINUE:
 729                 st->write_state = WRITE_STATE_SEND;
 730                 break;
 731
 732             case WORK_FINISHED_STOP:
 733                 return SUB_STATE_END_HANDSHAKE;
 734             }
 735             if(construct_message(s) == 0)
 736                 return SUB_STATE_ERROR;
 737
 738             /* Fall through */
 739
 740         case WRITE_STATE_SEND:
 741             if (SSL_IS_DTLS(s) && st->use_timer) {
 742                 dtls1_start_timer(s);
 743             }
 744             ret = statem_do_write(s);
 745             if (ret <= 0) {
 746                 return SUB_STATE_ERROR;
 747             }
 748             st->write_state = WRITE_STATE_POST_WORK;
 749             st->write_state_work = WORK_MORE_A;
 750             /* Fall through */
 751
 752         case WRITE_STATE_POST_WORK:
 753             switch(st->write_state_work = post_work(s, st->write_state_work)) {
 754             default:
 755                 return SUB_STATE_ERROR;
 756
 757             case WORK_FINISHED_CONTINUE:
 758                 st->write_state = WRITE_STATE_TRANSITION;
 759                 break;
 760
 761             case WORK_FINISHED_STOP:
 762                 return SUB_STATE_END_HANDSHAKE;
 763             }
 764             break;
 765
 766         default:
 767             return SUB_STATE_ERROR;
 768         }
 769     }
 770 }
 771
 772 /*
 773  * Flush the write BIO
 774  */
 775 int statem_flush(SSL *s)
 776 {
 777     s->rwstate = SSL_WRITING;
 778     if (BIO_flush(s->wbio) <= 0) {
 779         return 0;
 780     }
 781     s->rwstate = SSL_NOTHING;
 782
 783     return 1;
 784 }
 785
 786 /*
 787  * Called by the record layer to determine whether application data is
 788  * allowed to be sent in the current handshake state or not.
 789  *
 790  * Return values are:
 791  *   1: Yes (application data allowed)
 792  *   0: No (application data not allowed)
 793  */
 794 int ossl_statem_app_data_allowed(SSL *s)
 795 {
 796     OSSL_STATEM *st = &s->statem;
 797
 798     if (st->state == MSG_FLOW_UNINITED || st->state == MSG_FLOW_RENEGOTIATE)
 799         return 0;
 800
 801     if (!s->s3->in_read_app_data || (s->s3->total_renegotiations == 0))
 802         return 0;
 803
 804     if (s->server) {
 805         /*
 806          * If we're a server and we haven't got as far as writing our
 807          * ServerHello yet then we allow app data
 808          */
 809         if (st->hand_state == TLS_ST_BEFORE
 810                 || st->hand_state == TLS_ST_SR_CLNT_HELLO)
 811             return 1;
 812     } else {
 813         /*
 814          * If we're a client and we haven't read the ServerHello yet then we
 815          * allow app data
 816          */
 817         if (st->hand_state == TLS_ST_CW_CLNT_HELLO)
 818             return 1;
 819     }
 820
 821     return 0;
 822 }
 823
 824 #ifndef OPENSSL_NO_SCTP
 825 /*
 826  * Set flag used by SCTP to determine whether we are in the read sock state
 827  */
 828 void ossl_statem_set_sctp_read_sock(SSL *s, int read_sock)
 829 {
 830     s->statem.in_sctp_read_sock = read_sock;
 831 }
 832
 833 /*
 834  * Called by the record layer to determine whether we are in the read sock
 835  * state or not.
 836  *
 837  * Return values are:
 838  *   1: Yes (we are in the read sock state)
 839  *   0: No (we are not in the read sock state)
 840  */
 841 int ossl_statem_in_sctp_read_sock(SSL *s)
 842 {
 843     return s->statem.in_sctp_read_sock;
 844 }
 845 #endif