/*

 * Copyright 2015-2019 The OpenSSL Project Authors. All Rights Reserved.

 *

 * Licensed under the OpenSSL license (the "License").  You may not use

 * this file except in compliance with the License.  You can obtain a copy

 * in the file LICENSE in the source distribution or at

 * https://www.openssl.org/source/license.html

 */

#include "internal/cryptlib.h"

#include <openssl/rand.h>

#include "../ssl_local.h"

#include "statem_local.h"

#include <assert.h>

/*

 * This file implements the SSL/TLS/DTLS state machines.

 *

 * There are two primary state machines:

 *

 * 1) Message flow state machine

 * 2) Handshake state machine

 *

 * The Message flow state machine controls the reading and sending of messages

 * including handling of non-blocking IO events, flushing of the underlying

 * write BIO, handling unexpected messages, etc. It is itself broken into two

 * separate sub-state machines which control reading and writing respectively.

 *

 * The Handshake state machine keeps track of the current SSL/TLS handshake

 * state. Transitions of the handshake state are the result of events that

 * occur within the Message flow state machine.

 *

 * Overall it looks like this:

 *

 * ---------------------------------------------            -------------------

 * |                                           |            |                 |

 * | Message flow state machine                |            |                 |

 * |                                           |            |                 |

 * | -------------------- -------------------- | Transition | Handshake state |

 * | | MSG_FLOW_READING | | MSG_FLOW_WRITING | | Event      | machine         |

 * | | sub-state        | | sub-state        | |----------->|                 |

 * | | machine for      | | machine for      | |            |                 |

 * | | reading messages | | writing messages | |            |                 |

 * | -------------------- -------------------- |            |                 |

 * |                                           |            |                 |

 * ---------------------------------------------            -------------------

 *

 */

/* Sub state machine return values */

typedef enum {

    /* Something bad happened or NBIO */

    SUB_STATE_ERROR,

    /* Sub state finished go to the next sub state */

    SUB_STATE_FINISHED,

    /* Sub state finished and handshake was completed */

    SUB_STATE_END_HANDSHAKE

} SUB_STATE_RETURN;

static int state_machine(SSL *s, int server);

static void init_read_state_machine(SSL *s);

static SUB_STATE_RETURN read_state_machine(SSL *s);

static void init_write_state_machine(SSL *s);

static SUB_STATE_RETURN write_state_machine(SSL *s);

OSSL_HANDSHAKE_STATE SSL_get_state(const SSL *ssl)

{

    return ssl->statem.hand_state;

}

int SSL_in_init(const SSL *s)

{

    return s->statem.in_init;

}

int SSL_is_init_finished(const SSL *s)

{

    return !(s->statem.in_init) && (s->statem.hand_state == TLS_ST_OK);

}

int SSL_in_before(const SSL *s)

{

    /*

     * Historically being "in before" meant before anything had happened. In the

     * current code though we remain in the "before" state for a while after we

     * have started the handshake process (e.g. as a server waiting for the

     * first message to arrive). There "in before" is taken to mean "in before"

     * and not started any handshake process yet.

     */

    return (s->statem.hand_state == TLS_ST_BEFORE)

        && (s->statem.state == MSG_FLOW_UNINITED);

}

/*

 * Clear the state machine state and reset back to MSG_FLOW_UNINITED

 */

void ossl_statem_clear(SSL *s)

{

    s->statem.state = MSG_FLOW_UNINITED;

    s->statem.hand_state = TLS_ST_BEFORE;

    s->statem.in_init = 1;

    s->statem.no_cert_verify = 0;

}

/*

 * Set the state machine up ready for a renegotiation handshake

 */

void ossl_statem_set_renegotiate(SSL *s)

{

    s->statem.in_init = 1;

    s->statem.request_state = TLS_ST_SW_HELLO_REQ;

}

/*

 * Put the state machine into an error state and send an alert if appropriate.

 * This is a permanent error for the current connection.

 */

void ossl_statem_fatal(SSL *s, int al, int func, int reason, const char *file,

                       int line)

{

    ERR_put_error(ERR_LIB_SSL, func, reason, file, line);

    /* We shouldn't call SSLfatal() twice. Once is enough */

    if (s->statem.in_init && s->statem.state == MSG_FLOW_ERROR)

      return;

    s->statem.in_init = 1;

    s->statem.state = MSG_FLOW_ERROR;

    if (al != SSL_AD_NO_ALERT

            && s->statem.enc_write_state != ENC_WRITE_STATE_INVALID)

        ssl3_send_alert(s, SSL3_AL_FATAL, al);

}

/*

 * This macro should only be called if we are already expecting to be in

 * a fatal error state. We verify that we are, and set it if not (this would

 * indicate a bug).

 */

#define check_fatal(s, f) \

    do { \

        if (!ossl_assert((s)->statem.in_init \

                         && (s)->statem.state == MSG_FLOW_ERROR)) \

            SSLfatal(s, SSL_AD_INTERNAL_ERROR, (f), \

                     SSL_R_MISSING_FATAL); \

    } while (0)

/*

 * Discover whether the current connection is in the error state.

 *

 * Valid return values are:

 *   1: Yes

 *   0: No

 */

int ossl_statem_in_error(const SSL *s)

{

    if (s->statem.state == MSG_FLOW_ERROR)

        return 1;

    return 0;

}

void ossl_statem_set_in_init(SSL *s, int init)

{

    s->statem.in_init = init;

}

int ossl_statem_get_in_handshake(SSL *s)

{

    return s->statem.in_handshake;

}

void ossl_statem_set_in_handshake(SSL *s, int inhand)

{

    if (inhand)

        s->statem.in_handshake++;

    else

        s->statem.in_handshake--;

}

/* Are we in a sensible state to skip over unreadable early data? */

int ossl_statem_skip_early_data(SSL *s)

{

    if (s->ext.early_data != SSL_EARLY_DATA_REJECTED)

        return 0;

    if (!s->server

            || s->statem.hand_state != TLS_ST_EARLY_DATA

            || s->hello_retry_request == SSL_HRR_COMPLETE)

        return 0;

    return 1;

}

/*

 * Called when we are in SSL_read*(), SSL_write*(), or SSL_accept()

 * /SSL_connect()/SSL_do_handshake(). Used to test whether we are in an early

 * data state and whether we should attempt to move the handshake on if so.

 * |sending| is 1 if we are attempting to send data (SSL_write*()), 0 if we are

 * attempting to read data (SSL_read*()), or -1 if we are in SSL_do_handshake()

 * or similar.

 */

void ossl_statem_check_finish_init(SSL *s, int sending)

{

    if (sending == -1) {

        if (s->statem.hand_state == TLS_ST_PENDING_EARLY_DATA_END

                || s->statem.hand_state == TLS_ST_EARLY_DATA) {

            ossl_statem_set_in_init(s, 1);

            if (s->early_data_state == SSL_EARLY_DATA_WRITE_RETRY) {

                /*

                 * SSL_connect() or SSL_do_handshake() has been called directly.

                 * We don't allow any more writing of early data.

                 */

                s->early_data_state = SSL_EARLY_DATA_FINISHED_WRITING;

            }

        }

    } else if (!s->server) {

        if ((sending && (s->statem.hand_state == TLS_ST_PENDING_EARLY_DATA_END

                      || s->statem.hand_state == TLS_ST_EARLY_DATA)

                  && s->early_data_state != SSL_EARLY_DATA_WRITING)

                || (!sending && s->statem.hand_state == TLS_ST_EARLY_DATA)) {

            ossl_statem_set_in_init(s, 1);

            /*

             * SSL_write() has been called directly. We don't allow any more

             * writing of early data.

             */

            if (sending && s->early_data_state == SSL_EARLY_DATA_WRITE_RETRY)

                s->early_data_state = SSL_EARLY_DATA_FINISHED_WRITING;

        }

    } else {

        if (s->early_data_state == SSL_EARLY_DATA_FINISHED_READING

                && s->statem.hand_state == TLS_ST_EARLY_DATA)

            ossl_statem_set_in_init(s, 1);

    }

}

void ossl_statem_set_hello_verify_done(SSL *s)

{

    s->statem.state = MSG_FLOW_UNINITED;

    s->statem.in_init = 1;

    /*

     * This will get reset (briefly) back to TLS_ST_BEFORE when we enter

     * state_machine() because |state| is MSG_FLOW_UNINITED, but until then any

     * calls to SSL_in_before() will return false. Also calls to

     * SSL_state_string() and SSL_state_string_long() will return something

     * sensible.

     */

    s->statem.hand_state = TLS_ST_SR_CLNT_HELLO;

}

int ossl_statem_connect(SSL *s)

{

    return state_machine(s, 0);

}

int ossl_statem_accept(SSL *s)

{

    return state_machine(s, 1);

}

typedef void (*info_cb) (const SSL *, int, int);

static info_cb get_callback(SSL *s)

{

    if (s->info_callback != NULL)

        return s->info_callback;

    else if (s->ctx->info_callback != NULL)

        return s->ctx->info_callback;

    return NULL;

}

/*

 * The main message flow state machine. We start in the MSG_FLOW_UNINITED or

 * MSG_FLOW_FINISHED state and finish in MSG_FLOW_FINISHED. Valid states and

 * transitions are as follows:

 *

 * MSG_FLOW_UNINITED     MSG_FLOW_FINISHED

 *        |                       |

 *        +-----------------------+

 *        v

 * MSG_FLOW_WRITING <---> MSG_FLOW_READING

 *        |

 *        V

 * MSG_FLOW_FINISHED

 *        |

 *        V

 *    [SUCCESS]

 *

 * We may exit at any point due to an error or NBIO event. If an NBIO event

 * occurs then we restart at the point we left off when we are recalled.

 * MSG_FLOW_WRITING and MSG_FLOW_READING have sub-state machines associated with them.

 *

 * In addition to the above there is also the MSG_FLOW_ERROR state. We can move

 * into that state at any point in the event that an irrecoverable error occurs.

 *

 * Valid return values are:

 *   1: Success

 * <=0: NBIO or error

 */

static int state_machine(SSL *s, int server)

{

    BUF_MEM *buf = NULL;

    void (*cb) (const SSL *ssl, int type, int val) = NULL;

    OSSL_STATEM *st = &s->statem;

    int ret = -1;

    int ssret;

    if (st->state == MSG_FLOW_ERROR) {

        /* Shouldn't have been called if we're already in the error state */

        return -1;

    }

    ERR_clear_error();

    clear_sys_error();

    cb = get_callback(s);

    st->in_handshake++;

    if (!SSL_in_init(s) || SSL_in_before(s)) {

        /*

         * If we are stateless then we already called SSL_clear() - don't do

         * it again and clear the STATELESS flag itself.

         */

        if ((s->s3->flags & TLS1_FLAGS_STATELESS) == 0 && !SSL_clear(s))

            return -1;

    }

#ifndef OPENSSL_NO_SCTP

    if (SSL_IS_DTLS(s) && BIO_dgram_is_sctp(SSL_get_wbio(s))) {

        /*

         * Notify SCTP BIO socket to enter handshake mode and prevent stream

         * identifier other than 0.

         */

        BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,

                 st->in_handshake, NULL);

    }

#endif

    /* Initialise state machine */

    if (st->state == MSG_FLOW_UNINITED

            || st->state == MSG_FLOW_FINISHED) {

        if (st->state == MSG_FLOW_UNINITED) {

            st->hand_state = TLS_ST_BEFORE;

            st->request_state = TLS_ST_BEFORE;

        }

        s->server = server;

        if (cb != NULL) {

            if (SSL_IS_FIRST_HANDSHAKE(s) || !SSL_IS_TLS13(s))

                cb(s, SSL_CB_HANDSHAKE_START, 1);

        }

        /*

         * Fatal errors in this block don't send an alert because we have

         * failed to even initialise properly. Sending an alert is probably

         * doomed to failure.

         */

        if (SSL_IS_DTLS(s)) {

            if ((s->version & 0xff00) != (DTLS1_VERSION & 0xff00) &&

                (server || (s->version & 0xff00) != (DTLS1_BAD_VER & 0xff00))) {

                SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE,

                         ERR_R_INTERNAL_ERROR);

                goto end;

            }

        } else {

            if ((s->version >> 8) != SSL3_VERSION_MAJOR) {

                SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE,

                         ERR_R_INTERNAL_ERROR);

                goto end;

            }

        }

        if (!ssl_security(s, SSL_SECOP_VERSION, 0, s->version, NULL)) {

            SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE,

                     ERR_R_INTERNAL_ERROR);

            goto end;

        }

        if (s->init_buf == NULL) {

            if ((buf = BUF_MEM_new()) == NULL) {

                SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE,

                         ERR_R_INTERNAL_ERROR);

                goto end;

            }

            if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {

                SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE,

                         ERR_R_INTERNAL_ERROR);

                goto end;

            }

            s->init_buf = buf;

            buf = NULL;

        }

        if (!ssl3_setup_buffers(s)) {

            SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE,

                     ERR_R_INTERNAL_ERROR);

            goto end;

        }

        s->init_num = 0;

        /*

         * Should have been reset by tls_process_finished, too.

         */

        s->s3->change_cipher_spec = 0;

        /*

         * Ok, we now need to push on a buffering BIO ...but not with

         * SCTP

         */

#ifndef OPENSSL_NO_SCTP

        if (!SSL_IS_DTLS(s) || !BIO_dgram_is_sctp(SSL_get_wbio(s)))

#endif

            if (!ssl_init_wbio_buffer(s)) {

                SSLfatal(s, SSL_AD_NO_ALERT, SSL_F_STATE_MACHINE,

                         ERR_R_INTERNAL_ERROR);

                goto end;

            }

        if ((SSL_in_before(s))

                || s->renegotiate) {

            if (!tls_setup_handshake(s)) {

                /* SSLfatal() already called */

                goto end;

            }

            if (SSL_IS_FIRST_HANDSHAKE(s))

                st->read_state_first_init = 1;

        }

        st->state = MSG_FLOW_WRITING;

        init_write_state_machine(s);

    }

    while (st->state != MSG_FLOW_FINISHED) {

        if (st->state == MSG_FLOW_READING) {

            ssret = read_state_machine(s);

            if (ssret == SUB_STATE_FINISHED) {

                st->state = MSG_FLOW_WRITING;

                init_write_state_machine(s);

            } else {

                /* NBIO or error */

                goto end;

            }

        } else if (st->state == MSG_FLOW_WRITING) {

            ssret = write_state_machine(s);

            if (ssret == SUB_STATE_FINISHED) {

                st->state = MSG_FLOW_READING;

                init_read_state_machine(s);

            } else if (ssret == SUB_STATE_END_HANDSHAKE) {

                st->state = MSG_FLOW_FINISHED;

            } else {

                /* NBIO or error */

                goto end;

            }

        } else {

            /* Error */

            check_fatal(s, SSL_F_STATE_MACHINE);

            SSLerr(SSL_F_STATE_MACHINE, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);

            goto end;

        }

    }

    ret = 1;

 end:

    st->in_handshake--;

#ifndef OPENSSL_NO_SCTP

    if (SSL_IS_DTLS(s) && BIO_dgram_is_sctp(SSL_get_wbio(s))) {

        /*

         * Notify SCTP BIO socket to leave handshake mode and allow stream

         * identifier other than 0.

         */

        BIO_ctrl(SSL_get_wbio(s), BIO_CTRL_DGRAM_SCTP_SET_IN_HANDSHAKE,

                 st->in_handshake, NULL);

    }

#endif

    BUF_MEM_free(buf);

    if (cb != NULL) {

        if (server)

            cb(s, SSL_CB_ACCEPT_EXIT, ret);

        else

            cb(s, SSL_CB_CONNECT_EXIT, ret);

    }

    return ret;

}

/*

 * Initialise the MSG_FLOW_READING sub-state machine

 */

static void init_read_state_machine(SSL *s)

{

    OSSL_STATEM *st = &s->statem;

    st->read_state = READ_STATE_HEADER;

}

static int grow_init_buf(SSL *s, size_t size) {

    size_t msg_offset = (char *)s->init_msg - s->init_buf->data;

    if (!BUF_MEM_grow_clean(s->init_buf, (int)size))

        return 0;

    if (size < msg_offset)

        return 0;

    s->init_msg = s->init_buf->data + msg_offset;

    return 1;

}

/*

 * This function implements the sub-state machine when the message flow is in

 * MSG_FLOW_READING. The valid sub-states and transitions are:

 *

 * READ_STATE_HEADER <--+<-------------+

 *        |             |              |

 *        v             |              |

 * READ_STATE_BODY -----+-->READ_STATE_POST_PROCESS

 *        |                            |

 *        +----------------------------+

 *        v

 * [SUB_STATE_FINISHED]

 *

 * READ_STATE_HEADER has the responsibility for reading in the message header

 * and transitioning the state of the handshake state machine.

 *

 * READ_STATE_BODY reads in the rest of the message and then subsequently

 * processes it.

 *

 * READ_STATE_POST_PROCESS is an optional step that may occur if some post

 * processing activity performed on the message may block.

 *

 * Any of the above states could result in an NBIO event occurring in which case

 * control returns to the calling application. When this function is recalled we

 * will resume in the same state where we left off.

 */

static SUB_STATE_RETURN read_state_machine(SSL *s)

{

    OSSL_STATEM *st = &s->statem;

    int ret, mt;

    size_t len = 0;

    int (*transition) (SSL *s, int mt);

    PACKET pkt;

    MSG_PROCESS_RETURN(*process_message) (SSL *s, PACKET *pkt);

    WORK_STATE(*post_process_message) (SSL *s, WORK_STATE wst);

    size_t (*max_message_size) (SSL *s);

    void (*cb) (const SSL *ssl, int type, int val) = NULL;

    cb = get_callback(s);

    if (s->server) {

        transition = ossl_statem_server_read_transition;

        process_message = ossl_statem_server_process_message;

        max_message_size = ossl_statem_server_max_message_size;

        post_process_message = ossl_statem_server_post_process_message;

    } else {

        transition = ossl_statem_client_read_transition;

        process_message = ossl_statem_client_process_message;

        max_message_size = ossl_statem_client_max_message_size;

        post_process_message = ossl_statem_client_post_process_message;

    }

    if (st->read_state_first_init) {

        s->first_packet = 1;

        st->read_state_first_init = 0;

    }

    while (1) {

        switch (st->read_state) {

        case READ_STATE_HEADER:

            /* Get the state the peer wants to move to */

            if (SSL_IS_DTLS(s)) {

                /*

                 * In DTLS we get the whole message in one go - header and body

                 */

                ret = dtls_get_message(s, &mt, &len;;

            } else {

                ret = tls_get_message_header(s, &mt;;

            }

            if (ret == 0) {

                /* Could be non-blocking IO */

                return SUB_STATE_ERROR;

            }

            if (cb != NULL) {

                /* Notify callback of an impending state change */

                if (s->server)

                    cb(s, SSL_CB_ACCEPT_LOOP, 1);

                else

                    cb(s, SSL_CB_CONNECT_LOOP, 1);

            }

            /*

             * Validate that we are allowed to move to the new state and move

             * to that state if so

             */

            if (!transition(s, mt))

                return SUB_STATE_ERROR;

            if (s->s3->tmp.message_size > max_message_size(s)) {

                SSLfatal(s, SSL_AD_ILLEGAL_PARAMETER, SSL_F_READ_STATE_MACHINE,

                         SSL_R_EXCESSIVE_MESSAGE_SIZE);

                return SUB_STATE_ERROR;

            }

            /* dtls_get_message already did this */

            if (!SSL_IS_DTLS(s)

                    && s->s3->tmp.message_size > 0

                    && !grow_init_buf(s, s->s3->tmp.message_size

                                         + SSL3_HM_HEADER_LENGTH)) {

                SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_READ_STATE_MACHINE,

                         ERR_R_BUF_LIB);

                return SUB_STATE_ERROR;

            }

            st->read_state = READ_STATE_BODY;

            /* Fall through */

        case READ_STATE_BODY:

            if (!SSL_IS_DTLS(s)) {

                /* We already got this above for DTLS */

                ret = tls_get_message_body(s, &len;;

                if (ret == 0) {

                    /* Could be non-blocking IO */

                    return SUB_STATE_ERROR;

                }

            }

            s->first_packet = 0;

            if (!PACKET_buf_init(&pkt, s->init_msg, len)) {

                SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_READ_STATE_MACHINE,

                         ERR_R_INTERNAL_ERROR);

                return SUB_STATE_ERROR;

            }

            ret = process_message(s, &pkt);

            /* Discard the packet data */

            s->init_num = 0;

            switch (ret) {

            case MSG_PROCESS_ERROR:

                check_fatal(s, SSL_F_READ_STATE_MACHINE);

                return SUB_STATE_ERROR;

            case MSG_PROCESS_FINISHED_READING:

                if (SSL_IS_DTLS(s)) {

                    dtls1_stop_timer(s);

                }

                return SUB_STATE_FINISHED;

            case MSG_PROCESS_CONTINUE_PROCESSING:

                st->read_state = READ_STATE_POST_PROCESS;

                st->read_state_work = WORK_MORE_A;

                break;

            default:

                st->read_state = READ_STATE_HEADER;

                break;

            }

            break;

        case READ_STATE_POST_PROCESS:

            st->read_state_work = post_process_message(s, st->read_state_work);

            switch (st->read_state_work) {

            case WORK_ERROR:

                check_fatal(s, SSL_F_READ_STATE_MACHINE);

                /* Fall through */

            case WORK_MORE_A:

            case WORK_MORE_B:

            case WORK_MORE_C:

                return SUB_STATE_ERROR;

            case WORK_FINISHED_CONTINUE:

                st->read_state = READ_STATE_HEADER;

                break;

            case WORK_FINISHED_STOP:

                if (SSL_IS_DTLS(s)) {

                    dtls1_stop_timer(s);

                }

                return SUB_STATE_FINISHED;

            }

            break;

        default:

            /* Shouldn't happen */

            SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_READ_STATE_MACHINE,

                     ERR_R_INTERNAL_ERROR);

            return SUB_STATE_ERROR;

        }

    }

}

/*

 * Send a previously constructed message to the peer.

 */

static int statem_do_write(SSL *s)

{

    OSSL_STATEM *st = &s->statem;

    if (st->hand_state == TLS_ST_CW_CHANGE

        || st->hand_state == TLS_ST_SW_CHANGE) {

        if (SSL_IS_DTLS(s))

            return dtls1_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);

        else

            return ssl3_do_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);

    } else {

        return ssl_do_write(s);

    }

}

/*

 * Initialise the MSG_FLOW_WRITING sub-state machine

 */

static void init_write_state_machine(SSL *s)

{

    OSSL_STATEM *st = &s->statem;

    st->write_state = WRITE_STATE_TRANSITION;

}

/*

 * This function implements the sub-state machine when the message flow is in

 * MSG_FLOW_WRITING. The valid sub-states and transitions are:

 *

 * +-> WRITE_STATE_TRANSITION ------> [SUB_STATE_FINISHED]

 * |             |

 * |             v

 * |      WRITE_STATE_PRE_WORK -----> [SUB_STATE_END_HANDSHAKE]

 * |             |

 * |             v

 * |       WRITE_STATE_SEND

 * |             |

 * |             v

 * |     WRITE_STATE_POST_WORK

 * |             |

 * +-------------+

 *

 * WRITE_STATE_TRANSITION transitions the state of the handshake state machine

 * WRITE_STATE_PRE_WORK performs any work necessary to prepare the later

 * sending of the message. This could result in an NBIO event occurring in

 * which case control returns to the calling application. When this function

 * is recalled we will resume in the same state where we left off.

 *

 * WRITE_STATE_SEND sends the message and performs any work to be done after

 * sending.

 *

 * WRITE_STATE_POST_WORK performs any work necessary after the sending of the

 * message has been completed. As for WRITE_STATE_PRE_WORK this could also

 * result in an NBIO event.

 */

static SUB_STATE_RETURN write_state_machine(SSL *s)

{

    OSSL_STATEM *st = &s->statem;

    int ret;

    WRITE_TRAN(*transition) (SSL *s);

    WORK_STATE(*pre_work) (SSL *s, WORK_STATE wst);

    WORK_STATE(*post_work) (SSL *s, WORK_STATE wst);

    int (*get_construct_message_f) (SSL *s, WPACKET *pkt,

                                    int (**confunc) (SSL *s, WPACKET *pkt),

                                    int *mt);

    void (*cb) (const SSL *ssl, int type, int val) = NULL;

    int (*confunc) (SSL *s, WPACKET *pkt);

    int mt;

    WPACKET pkt;

    cb = get_callback(s);

    if (s->server) {

        transition = ossl_statem_server_write_transition;

        pre_work = ossl_statem_server_pre_work;

        post_work = ossl_statem_server_post_work;

        get_construct_message_f = ossl_statem_server_construct_message;

    } else {

        transition = ossl_statem_client_write_transition;

        pre_work = ossl_statem_client_pre_work;

        post_work = ossl_statem_client_post_work;

        get_construct_message_f = ossl_statem_client_construct_message;

    }

    while (1) {

        switch (st->write_state) {

        case WRITE_STATE_TRANSITION:

            if (cb != NULL) {

                /* Notify callback of an impending state change */

                if (s->server)

                    cb(s, SSL_CB_ACCEPT_LOOP, 1);

                else

                    cb(s, SSL_CB_CONNECT_LOOP, 1);

            }

            switch (transition(s)) {

            case WRITE_TRAN_CONTINUE:

                st->write_state = WRITE_STATE_PRE_WORK;

                st->write_state_work = WORK_MORE_A;

                break;

            case WRITE_TRAN_FINISHED:

                return SUB_STATE_FINISHED;

                break;

            case WRITE_TRAN_ERROR:

                check_fatal(s, SSL_F_WRITE_STATE_MACHINE);

                return SUB_STATE_ERROR;

            }

            break;

        case WRITE_STATE_PRE_WORK:

            switch (st->write_state_work = pre_work(s, st->write_state_work)) {

            case WORK_ERROR:

                check_fatal(s, SSL_F_WRITE_STATE_MACHINE);

                /* Fall through */

            case WORK_MORE_A:

            case WORK_MORE_B:

            case WORK_MORE_C:

                return SUB_STATE_ERROR;

            case WORK_FINISHED_CONTINUE:

                st->write_state = WRITE_STATE_SEND;

                break;

            case WORK_FINISHED_STOP:

                return SUB_STATE_END_HANDSHAKE;

            }

            if (!get_construct_message_f(s, &pkt, &confunc, &mt)) {

                /* SSLfatal() already called */

                return SUB_STATE_ERROR;

            }

            if (mt == SSL3_MT_DUMMY) {

                /* Skip construction and sending. This isn't a "real" state */

                st->write_state = WRITE_STATE_POST_WORK;

                st->write_state_work = WORK_MORE_A;

                break;

            }

            if (!WPACKET_init(&pkt, s->init_buf)

                    || !ssl_set_handshake_header(s, &pkt, mt)) {

                WPACKET_cleanup(&pkt);

                SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_WRITE_STATE_MACHINE,

                         ERR_R_INTERNAL_ERROR);

                return SUB_STATE_ERROR;

            }

            if (confunc != NULL && !confunc(s, &pkt)) {

                WPACKET_cleanup(&pkt);

                check_fatal(s, SSL_F_WRITE_STATE_MACHINE);

                return SUB_STATE_ERROR;

            }

            if (!ssl_close_construct_packet(s, &pkt, mt)

                    || !WPACKET_finish(&pkt)) {

                WPACKET_cleanup(&pkt);

                SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_WRITE_STATE_MACHINE,

                         ERR_R_INTERNAL_ERROR);

                return SUB_STATE_ERROR;

            }

            /* Fall through */

        case WRITE_STATE_SEND:

            if (SSL_IS_DTLS(s) && st->use_timer) {

                dtls1_start_timer(s);

            }

            ret = statem_do_write(s);

            if (ret <= 0) {

                return SUB_STATE_ERROR;

            }

            st->write_state = WRITE_STATE_POST_WORK;

            st->write_state_work = WORK_MORE_A;

            /* Fall through */

        case WRITE_STATE_POST_WORK:

            switch (st->write_state_work = post_work(s, st->write_state_work)) {

            case WORK_ERROR:

                check_fatal(s, SSL_F_WRITE_STATE_MACHINE);

                /* Fall through */

            case WORK_MORE_A:

            case WORK_MORE_B:

            case WORK_MORE_C:

                return SUB_STATE_ERROR;

            case WORK_FINISHED_CONTINUE: