int ssl3_connect(SSL *s)
{
    BUF_MEM *buf = NULL;
    unsigned long Time = (unsigned long)time(NULL);
    void (*cb) (const SSL *ssl, int type, int val) = NULL;
    int ret = -1;
    int new_state, state, skip = 0;

    RAND_add(&Time, sizeof(Time), 0);
    ERR_clear_error();
    clear_sys_error();

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

    s->in_handshake++;
    if (!SSL_in_init(s) || SSL_in_before(s))
        SSL_clear(s);

#ifndef OPENSSL_NO_HEARTBEATS
    /*
     * If we're awaiting a HeartbeatResponse, pretend we already got and
     * don't await it anymore, because Heartbeats don't make sense during
     * handshakes anyway.
     */
    if (s->tlsext_hb_pending) {
        s->tlsext_hb_pending = 0;
        s->tlsext_hb_seq++;
    }
#endif

    for (;;) {
        state = s->state;

        switch (s->state) {
        case SSL_ST_RENEGOTIATE:
            s->renegotiate = 1;
            s->state = SSL_ST_CONNECT;
            s->ctx->stats.sess_connect_renegotiate++;
            /* break */
        case SSL_ST_BEFORE:
        case SSL_ST_CONNECT:
        case SSL_ST_BEFORE | SSL_ST_CONNECT:
        case SSL_ST_OK | SSL_ST_CONNECT:

            s->server = 0;
            if (cb != NULL)
                cb(s, SSL_CB_HANDSHAKE_START, 1);

            if ((s->version & 0xff00) != 0x0300) {
                SSLerr(SSL_F_SSL3_CONNECT, ERR_R_INTERNAL_ERROR);
                s->state = SSL_ST_ERR;
                ret = -1;
                goto end;
            }

            /* s->version=SSL3_VERSION; */
            s->type = SSL_ST_CONNECT;

            if (s->init_buf == NULL) {
                if ((buf = BUF_MEM_new()) == NULL) {
                    ret = -1;
                    s->state = SSL_ST_ERR;
                    goto end;
                }
                if (!BUF_MEM_grow(buf, SSL3_RT_MAX_PLAIN_LENGTH)) {
                    ret = -1;
                    s->state = SSL_ST_ERR;
                    goto end;
                }
                s->init_buf = buf;
                buf = NULL;
            }

            if (!ssl3_setup_buffers(s)) {
                ret = -1;
                goto end;
            }

            /* setup buffing BIO */
            if (!ssl_init_wbio_buffer(s, 0)) {
                ret = -1;
                s->state = SSL_ST_ERR;
                goto end;
            }

            /* don't push the buffering BIO quite yet */

            ssl3_init_finished_mac(s);

            s->state = SSL3_ST_CW_CLNT_HELLO_A;
            s->ctx->stats.sess_connect++;
            s->init_num = 0;
            s->s3->flags &= ~SSL3_FLAGS_CCS_OK;
            /*
             * Should have been reset by ssl3_get_finished, too.
             */
            s->s3->change_cipher_spec = 0;
            break;

        case SSL3_ST_CW_CLNT_HELLO_A:
        case SSL3_ST_CW_CLNT_HELLO_B:

            s->shutdown = 0;
            ret = ssl3_client_hello(s);
            if (ret <= 0)
                goto end;
            s->state = SSL3_ST_CR_SRVR_HELLO_A;
            s->init_num = 0;

            /* turn on buffering for the next lot of output */
            if (s->bbio != s->wbio)
                s->wbio = BIO_push(s->bbio, s->wbio);

            break;

        case SSL3_ST_CR_SRVR_HELLO_A:
        case SSL3_ST_CR_SRVR_HELLO_B:
            ret = ssl3_get_server_hello(s);
            if (ret <= 0)
                goto end;

            if (s->hit) {
                s->state = SSL3_ST_CR_FINISHED_A;
#ifndef OPENSSL_NO_TLSEXT
                if (s->tlsext_ticket_expected) {
                    /* receive renewed session ticket */
                    s->state = SSL3_ST_CR_SESSION_TICKET_A;
                }
#endif
            } else {
                s->state = SSL3_ST_CR_CERT_A;
            }
            s->init_num = 0;
            break;
        case SSL3_ST_CR_CERT_A:
        case SSL3_ST_CR_CERT_B:
#ifndef OPENSSL_NO_TLSEXT
            /* Noop (ret = 0) for everything but EAP-FAST. */
            ret = ssl3_check_finished(s);
            if (ret < 0)
                goto end;
            if (ret == 1) {
                s->hit = 1;
                s->state = SSL3_ST_CR_FINISHED_A;
                s->init_num = 0;
                break;
            }
#endif
            /* Check if it is anon DH/ECDH, SRP auth */
            /* or PSK */
            if (!
                (s->s3->tmp.
                 new_cipher->algorithm_auth & (SSL_aNULL | SSL_aSRP))
                    && !(s->s3->tmp.new_cipher->algorithm_mkey & SSL_kPSK)) {
                ret = ssl3_get_server_certificate(s);
                if (ret <= 0)
                    goto end;
#ifndef OPENSSL_NO_TLSEXT
                if (s->tlsext_status_expected)
                    s->state = SSL3_ST_CR_CERT_STATUS_A;
                else
                    s->state = SSL3_ST_CR_KEY_EXCH_A;
            } else {
                skip = 1;
                s->state = SSL3_ST_CR_KEY_EXCH_A;
            }
#else
            } else
                skip = 1;

            s->state = SSL3_ST_CR_KEY_EXCH_A;
#endif
            s->init_num = 0;
            break;

        case SSL3_ST_CR_KEY_EXCH_A:
        case SSL3_ST_CR_KEY_EXCH_B:
            ret = ssl3_get_key_exchange(s);
            if (ret <= 0)
                goto end;
            s->state = SSL3_ST_CR_CERT_REQ_A;
            s->init_num = 0;

            /*
             * at this point we check that we have the required stuff from
             * the server
             */
            if (!ssl3_check_cert_and_algorithm(s)) {
                ret = -1;
                s->state = SSL_ST_ERR;
                goto end;
            }
            break;

        case SSL3_ST_CR_CERT_REQ_A:
        case SSL3_ST_CR_CERT_REQ_B:
            ret = ssl3_get_certificate_request(s);
            if (ret <= 0)
                goto end;
            s->state = SSL3_ST_CR_SRVR_DONE_A;
            s->init_num = 0;
            break;

        case SSL3_ST_CR_SRVR_DONE_A:
        case SSL3_ST_CR_SRVR_DONE_B:
            ret = ssl3_get_server_done(s);
            if (ret <= 0)
                goto end;
#ifndef OPENSSL_NO_SRP
            if (s->s3->tmp.new_cipher->algorithm_mkey & SSL_kSRP) {
                if ((ret = SRP_Calc_A_param(s)) <= 0) {
                    SSLerr(SSL_F_SSL3_CONNECT, SSL_R_SRP_A_CALC);
                    ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
                    s->state = SSL_ST_ERR;
                    goto end;
                }
            }
#endif
            if (s->s3->tmp.cert_req)
                s->state = SSL3_ST_CW_CERT_A;
            else
                s->state = SSL3_ST_CW_KEY_EXCH_A;
            s->init_num = 0;

            break;

        case SSL3_ST_CW_CERT_A:
        case SSL3_ST_CW_CERT_B:
        case SSL3_ST_CW_CERT_C:
        case SSL3_ST_CW_CERT_D:
            ret = ssl3_send_client_certificate(s);
            if (ret <= 0)
                goto end;
            s->state = SSL3_ST_CW_KEY_EXCH_A;
            s->init_num = 0;
            break;

        case SSL3_ST_CW_KEY_EXCH_A:
        case SSL3_ST_CW_KEY_EXCH_B:
            ret = ssl3_send_client_key_exchange(s);
            if (ret <= 0)
                goto end;
            /*
             * EAY EAY EAY need to check for DH fix cert sent back
             */
            /*
             * For TLS, cert_req is set to 2, so a cert chain of nothing is
             * sent, but no verify packet is sent
             */
            /*
             * XXX: For now, we do not support client authentication in ECDH
             * cipher suites with ECDH (rather than ECDSA) certificates. We
             * need to skip the certificate verify message when client's
             * ECDH public key is sent inside the client certificate.
             */
            if (s->s3->tmp.cert_req == 1) {
                s->state = SSL3_ST_CW_CERT_VRFY_A;
            } else {
                s->state = SSL3_ST_CW_CHANGE_A;
            }
            if (s->s3->flags & TLS1_FLAGS_SKIP_CERT_VERIFY) {
                s->state = SSL3_ST_CW_CHANGE_A;
            }

            s->init_num = 0;
            break;

        case SSL3_ST_CW_CERT_VRFY_A:
        case SSL3_ST_CW_CERT_VRFY_B:
            ret = ssl3_send_client_verify(s);
            if (ret <= 0)
                goto end;
            s->state = SSL3_ST_CW_CHANGE_A;
            s->init_num = 0;
            break;

        case SSL3_ST_CW_CHANGE_A:
        case SSL3_ST_CW_CHANGE_B:
            ret = ssl3_send_change_cipher_spec(s,
                                               SSL3_ST_CW_CHANGE_A,
                                               SSL3_ST_CW_CHANGE_B);
            if (ret <= 0)
                goto end;

#if defined(OPENSSL_NO_TLSEXT) || defined(OPENSSL_NO_NEXTPROTONEG)
            s->state = SSL3_ST_CW_FINISHED_A;
#else
            if (s->s3->next_proto_neg_seen)
                s->state = SSL3_ST_CW_NEXT_PROTO_A;
            else
                s->state = SSL3_ST_CW_FINISHED_A;
#endif
            s->init_num = 0;

            s->session->cipher = s->s3->tmp.new_cipher;
#ifdef OPENSSL_NO_COMP
            s->session->compress_meth = 0;
#else
            if (s->s3->tmp.new_compression == NULL)
                s->session->compress_meth = 0;
            else
                s->session->compress_meth = s->s3->tmp.new_compression->id;
#endif
            if (!s->method->ssl3_enc->setup_key_block(s)) {
                ret = -1;
                s->state = SSL_ST_ERR;
                goto end;
            }

            if (!s->method->ssl3_enc->change_cipher_state(s,
                                                          SSL3_CHANGE_CIPHER_CLIENT_WRITE))
            {
                ret = -1;
                s->state = SSL_ST_ERR;
                goto end;
            }

            break;

#if !defined(OPENSSL_NO_TLSEXT) && !defined(OPENSSL_NO_NEXTPROTONEG)
        case SSL3_ST_CW_NEXT_PROTO_A:
        case SSL3_ST_CW_NEXT_PROTO_B:
            ret = ssl3_send_next_proto(s);
            if (ret <= 0)
                goto end;
            s->state = SSL3_ST_CW_FINISHED_A;
            break;
#endif

        case SSL3_ST_CW_FINISHED_A:
        case SSL3_ST_CW_FINISHED_B:
            ret = ssl3_send_finished(s,
                                     SSL3_ST_CW_FINISHED_A,
                                     SSL3_ST_CW_FINISHED_B,
                                     s->method->
                                     ssl3_enc->client_finished_label,
                                     s->method->
                                     ssl3_enc->client_finished_label_len);
            if (ret <= 0)
                goto end;
            s->state = SSL3_ST_CW_FLUSH;

            /* clear flags */
            s->s3->flags &= ~SSL3_FLAGS_POP_BUFFER;
            if (s->hit) {
                s->s3->tmp.next_state = SSL_ST_OK;
                if (s->s3->flags & SSL3_FLAGS_DELAY_CLIENT_FINISHED) {
                    s->state = SSL_ST_OK;
                    s->s3->flags |= SSL3_FLAGS_POP_BUFFER;
                    s->s3->delay_buf_pop_ret = 0;
                }
            } else {
#ifndef OPENSSL_NO_TLSEXT
                /*
                 * Allow NewSessionTicket if ticket expected
                 */
                if (s->tlsext_ticket_expected)
                    s->s3->tmp.next_state = SSL3_ST_CR_SESSION_TICKET_A;
                else
#endif

                    s->s3->tmp.next_state = SSL3_ST_CR_FINISHED_A;
            }
            s->init_num = 0;
            break;

#ifndef OPENSSL_NO_TLSEXT
        case SSL3_ST_CR_SESSION_TICKET_A:
        case SSL3_ST_CR_SESSION_TICKET_B:
            ret = ssl3_get_new_session_ticket(s);
            if (ret <= 0)
                goto end;
            s->state = SSL3_ST_CR_FINISHED_A;
            s->init_num = 0;
            break;

        case SSL3_ST_CR_CERT_STATUS_A:
        case SSL3_ST_CR_CERT_STATUS_B:
            ret = ssl3_get_cert_status(s);
            if (ret <= 0)
                goto end;
            s->state = SSL3_ST_CR_KEY_EXCH_A;
            s->init_num = 0;
            break;
#endif

        case SSL3_ST_CR_FINISHED_A:
        case SSL3_ST_CR_FINISHED_B:
            if (!s->s3->change_cipher_spec)
                s->s3->flags |= SSL3_FLAGS_CCS_OK;
            ret = ssl3_get_finished(s, SSL3_ST_CR_FINISHED_A,
                                    SSL3_ST_CR_FINISHED_B);
            if (ret <= 0)
                goto end;

            if (s->hit)
                s->state = SSL3_ST_CW_CHANGE_A;
            else
                s->state = SSL_ST_OK;
            s->init_num = 0;
            break;

        case SSL3_ST_CW_FLUSH:
            s->rwstate = SSL_WRITING;
            if (BIO_flush(s->wbio) <= 0) {
                ret = -1;
                goto end;
            }
            s->rwstate = SSL_NOTHING;
            s->state = s->s3->tmp.next_state;
            break;

        case SSL_ST_OK:
            /* clean a few things up */
            ssl3_cleanup_key_block(s);

            if (s->init_buf != NULL) {
                BUF_MEM_free(s->init_buf);
                s->init_buf = NULL;
            }

            /*
             * If we are not 'joining' the last two packets, remove the
             * buffering now
             */
            if (!(s->s3->flags & SSL3_FLAGS_POP_BUFFER))
                ssl_free_wbio_buffer(s);
            /* else do it later in ssl3_write */

            s->init_num = 0;
            s->renegotiate = 0;
            s->new_session = 0;

            ssl_update_cache(s, SSL_SESS_CACHE_CLIENT);
            if (s->hit)
                s->ctx->stats.sess_hit++;

            ret = 1;
            /* s->server=0; */
            s->handshake_func = ssl3_connect;
            s->ctx->stats.sess_connect_good++;

            if (cb != NULL)
                cb(s, SSL_CB_HANDSHAKE_DONE, 1);

            goto end;
            /* break; */

        case SSL_ST_ERR:
        default:
            SSLerr(SSL_F_SSL3_CONNECT, SSL_R_UNKNOWN_STATE);
            ret = -1;
            goto end;
            /* break; */
        }

        /* did we do anything */
        if (!s->s3->tmp.reuse_message && !skip) {
            if (s->debug) {
                if ((ret = BIO_flush(s->wbio)) <= 0)
                    goto end;
            }

            if ((cb != NULL) && (s->state != state)) {
                new_state = s->state;
                s->state = state;
                cb(s, SSL_CB_CONNECT_LOOP, 1);
                s->state = new_state;
            }
        }
        skip = 0;
    }

The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.