/* $OpenBSD: ssl_clnt.c,v 1.153 2022/08/17 07:39:19 jsing Exp $ */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 *
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 *
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 *
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */
/* ====================================================================
 * Copyright (c) 1998-2007 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    openssl-core@openssl.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */
/* ====================================================================
 * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
 *
 * Portions of the attached software ("Contribution") are developed by
 * SUN MICROSYSTEMS, INC., and are contributed to the OpenSSL project.
 *
 * The Contribution is licensed pursuant to the OpenSSL open source
 * license provided above.
 *
 * ECC cipher suite support in OpenSSL originally written by
 * Vipul Gupta and Sumit Gupta of Sun Microsystems Laboratories.
 *
 */
/* ====================================================================
 * Copyright 2005 Nokia. All rights reserved.
 *
 * The portions of the attached software ("Contribution") is developed by
 * Nokia Corporation and is licensed pursuant to the OpenSSL open source
 * license.
 *
 * The Contribution, originally written by Mika Kousa and Pasi Eronen of
 * Nokia Corporation, consists of the "PSK" (Pre-Shared Key) ciphersuites
 * support (see RFC 4279) to OpenSSL.
 *
 * No patent licenses or other rights except those expressly stated in
 * the OpenSSL open source license shall be deemed granted or received
 * expressly, by implication, estoppel, or otherwise.
 *
 * No assurances are provided by Nokia that the Contribution does not
 * infringe the patent or other intellectual property rights of any third
 * party or that the license provides you with all the necessary rights
 * to make use of the Contribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. IN
 * ADDITION TO THE DISCLAIMERS INCLUDED IN THE LICENSE, NOKIA
 * SPECIFICALLY DISCLAIMS ANY LIABILITY FOR CLAIMS BROUGHT BY YOU OR ANY
 * OTHER ENTITY BASED ON INFRINGEMENT OF INTELLECTUAL PROPERTY RIGHTS OR
 * OTHERWISE.
 */

#include <limits.h>
#include <stdint.h>
#include <stdio.h>

#include <openssl/bn.h>
#include <openssl/buffer.h>
#include <openssl/curve25519.h>
#include <openssl/dh.h>
#include <openssl/evp.h>
#include <openssl/md5.h>
#include <openssl/objects.h>
#include <openssl/opensslconf.h>

#ifndef OPENSSL_NO_ENGINE
#include <openssl/engine.h>
#endif
#ifndef OPENSSL_NO_GOST
#include <openssl/gost.h>
#endif

#include "bytestring.h"
#include "dtls_locl.h"
#include "ssl_locl.h"
#include "ssl_sigalgs.h"
#include "ssl_tlsext.h"

static int ca_dn_cmp(const X509_NAME * const *a, const X509_NAME * const *b);

int
ssl3_connect(SSL *s)
{
        int new_state, state, skip = 0;
        int ret = -1;

        ERR_clear_error();
        errno = 0;

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

        for (;;) {
                state = s->s3->hs.state;

                switch (s->s3->hs.state) {
                case SSL_ST_RENEGOTIATE:
                        s->internal->renegotiate = 1;
                        s->s3->hs.state = SSL_ST_CONNECT;
                        s->ctx->internal->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;

                        ssl_info_callback(s, SSL_CB_HANDSHAKE_START, 1);

                        if (!ssl_legacy_stack_version(s, s->version)) {
                                SSLerror(s, ERR_R_INTERNAL_ERROR);
                                ret = -1;
                                goto end;
                        }

                        if (!ssl_supported_tls_version_range(s,
                            &s->s3->hs.our_min_tls_version,
                            &s->s3->hs.our_max_tls_version)) {
                                SSLerror(s, SSL_R_NO_PROTOCOLS_AVAILABLE);
                                ret = -1;
                                goto end;
                        }

                        if (!ssl_security_version(s,
                            s->s3->hs.our_min_tls_version)) {
                                SSLerror(s, SSL_R_VERSION_TOO_LOW);
                                ret = -1;
                                goto end;
                        }

                        if (!ssl3_setup_init_buffer(s)) {
                                ret = -1;
                                goto end;
                        }
                        if (!ssl3_setup_buffers(s)) {
                                ret = -1;
                                goto end;
                        }
                        if (!ssl_init_wbio_buffer(s, 0)) {
                                ret = -1;
                                goto end;
                        }

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

                        if (!tls1_transcript_init(s)) {
                                ret = -1;
                                goto end;
                        }

                        s->s3->hs.state = SSL3_ST_CW_CLNT_HELLO_A;
                        s->ctx->internal->stats.sess_connect++;
                        s->internal->init_num = 0;

                        if (SSL_is_dtls(s)) {
                                /* mark client_random uninitialized */
                                memset(s->s3->client_random, 0,
                                    sizeof(s->s3->client_random));
                                s->d1->send_cookie = 0;
                                s->internal->hit = 0;
                        }
                        break;

                case SSL3_ST_CW_CLNT_HELLO_A:
                case SSL3_ST_CW_CLNT_HELLO_B:
                        s->internal->shutdown = 0;

                        if (SSL_is_dtls(s)) {
                                /* every DTLS ClientHello resets Finished MAC */
                                tls1_transcript_reset(s);

                                dtls1_start_timer(s);
                        }

                        ret = ssl3_send_client_hello(s);
                        if (ret <= 0)
                                goto end;

                        if (SSL_is_dtls(s) && s->d1->send_cookie) {
                                s->s3->hs.state = SSL3_ST_CW_FLUSH;
                                s->s3->hs.tls12.next_state = SSL3_ST_CR_SRVR_HELLO_A;
                        } else
                                s->s3->hs.state = SSL3_ST_CR_SRVR_HELLO_A;

                        s->internal->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->internal->hit) {
                                s->s3->hs.state = SSL3_ST_CR_FINISHED_A;
                                if (!SSL_is_dtls(s)) {
                                        if (s->internal->tlsext_ticket_expected) {
                                                /* receive renewed session ticket */
                                                s->s3->hs.state = SSL3_ST_CR_SESSION_TICKET_A;
                                        }

                                        /* No client certificate verification. */
                                        tls1_transcript_free(s);
                                }
                        } else if (SSL_is_dtls(s)) {
                                s->s3->hs.state = DTLS1_ST_CR_HELLO_VERIFY_REQUEST_A;
                        } else {
                                s->s3->hs.state = SSL3_ST_CR_CERT_A;
                        }
                        s->internal->init_num = 0;
                        break;

                case DTLS1_ST_CR_HELLO_VERIFY_REQUEST_A:
                case DTLS1_ST_CR_HELLO_VERIFY_REQUEST_B:
                        ret = ssl3_get_dtls_hello_verify(s);
                        if (ret <= 0)
                                goto end;
                        dtls1_stop_timer(s);
                        if (s->d1->send_cookie) /* start again, with a cookie */
                                s->s3->hs.state = SSL3_ST_CW_CLNT_HELLO_A;
                        else
                                s->s3->hs.state = SSL3_ST_CR_CERT_A;
                        s->internal->init_num = 0;
                        break;

                case SSL3_ST_CR_CERT_A:
                case SSL3_ST_CR_CERT_B:
                        ret = ssl3_check_finished(s);
                        if (ret <= 0)
                                goto end;
                        if (ret == 2) {
                                s->internal->hit = 1;
                                if (s->internal->tlsext_ticket_expected)
                                        s->s3->hs.state = SSL3_ST_CR_SESSION_TICKET_A;
                                else
                                        s->s3->hs.state = SSL3_ST_CR_FINISHED_A;
                                s->internal->init_num = 0;
                                break;
                        }
                        /* Check if it is anon DH/ECDH. */
                        if (!(s->s3->hs.cipher->algorithm_auth &
                            SSL_aNULL)) {
                                ret = ssl3_get_server_certificate(s);
                                if (ret <= 0)
                                        goto end;
                                if (s->internal->tlsext_status_expected)
                                        s->s3->hs.state = SSL3_ST_CR_CERT_STATUS_A;
                                else
                                        s->s3->hs.state = SSL3_ST_CR_KEY_EXCH_A;
                        } else {
                                skip = 1;
                                s->s3->hs.state = SSL3_ST_CR_KEY_EXCH_A;
                        }
                        s->internal->init_num = 0;
                        break;

                case SSL3_ST_CR_KEY_EXCH_A:
                case SSL3_ST_CR_KEY_EXCH_B:
                        ret = ssl3_get_server_key_exchange(s);
                        if (ret <= 0)
                                goto end;
                        s->s3->hs.state = SSL3_ST_CR_CERT_REQ_A;
                        s->internal->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;
                                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->s3->hs.state = SSL3_ST_CR_SRVR_DONE_A;
                        s->internal->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;
                        if (SSL_is_dtls(s))
                                dtls1_stop_timer(s);
                        if (s->s3->hs.tls12.cert_request)
                                s->s3->hs.state = SSL3_ST_CW_CERT_A;
                        else
                                s->s3->hs.state = SSL3_ST_CW_KEY_EXCH_A;
                        s->internal->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:
                        if (SSL_is_dtls(s))
                                dtls1_start_timer(s);
                        ret = ssl3_send_client_certificate(s);
                        if (ret <= 0)
                                goto end;
                        s->s3->hs.state = SSL3_ST_CW_KEY_EXCH_A;
                        s->internal->init_num = 0;
                        break;

                case SSL3_ST_CW_KEY_EXCH_A:
                case SSL3_ST_CW_KEY_EXCH_B:
                        if (SSL_is_dtls(s))
                                dtls1_start_timer(s);
                        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->hs.tls12.cert_request == 1) {
                                s->s3->hs.state = SSL3_ST_CW_CERT_VRFY_A;
                        } else {
                                s->s3->hs.state = SSL3_ST_CW_CHANGE_A;
                                s->s3->change_cipher_spec = 0;
                        }
                        if (!SSL_is_dtls(s)) {
                                if (s->s3->flags & TLS1_FLAGS_SKIP_CERT_VERIFY) {
                                        s->s3->hs.state = SSL3_ST_CW_CHANGE_A;
                                        s->s3->change_cipher_spec = 0;
                                }
                        }

                        s->internal->init_num = 0;
                        break;

                case SSL3_ST_CW_CERT_VRFY_A:
                case SSL3_ST_CW_CERT_VRFY_B:
                        if (SSL_is_dtls(s))
                                dtls1_start_timer(s);
                        ret = ssl3_send_client_verify(s);
                        if (ret <= 0)
                                goto end;
                        s->s3->hs.state = SSL3_ST_CW_CHANGE_A;
                        s->internal->init_num = 0;
                        s->s3->change_cipher_spec = 0;
                        break;

                case SSL3_ST_CW_CHANGE_A:
                case SSL3_ST_CW_CHANGE_B:
                        if (SSL_is_dtls(s) && !s->internal->hit)
                                dtls1_start_timer(s);
                        ret = ssl3_send_change_cipher_spec(s,
                            SSL3_ST_CW_CHANGE_A, SSL3_ST_CW_CHANGE_B);
                        if (ret <= 0)
                                goto end;

                        s->s3->hs.state = SSL3_ST_CW_FINISHED_A;
                        s->internal->init_num = 0;
                        s->session->cipher = s->s3->hs.cipher;

                        if (!tls1_setup_key_block(s)) {
                                ret = -1;
                                goto end;
                        }
                        if (!tls1_change_write_cipher_state(s)) {
                                ret = -1;
                                goto end;
                        }
                        break;

                case SSL3_ST_CW_FINISHED_A:
                case SSL3_ST_CW_FINISHED_B:
                        if (SSL_is_dtls(s) && !s->internal->hit)
                                dtls1_start_timer(s);
                        ret = ssl3_send_finished(s, SSL3_ST_CW_FINISHED_A,
                            SSL3_ST_CW_FINISHED_B);
                        if (ret <= 0)
                                goto end;
                        if (!SSL_is_dtls(s))
                                s->s3->flags |= SSL3_FLAGS_CCS_OK;
                        s->s3->hs.state = SSL3_ST_CW_FLUSH;

                        /* clear flags */
                        if (s->internal->hit) {
                                s->s3->hs.tls12.next_state = SSL_ST_OK;
                        } else {
                                /* Allow NewSessionTicket if ticket expected */
                                if (s->internal->tlsext_ticket_expected)
                                        s->s3->hs.tls12.next_state =
                                            SSL3_ST_CR_SESSION_TICKET_A;
                                else
                                        s->s3->hs.tls12.next_state =
                                            SSL3_ST_CR_FINISHED_A;
                        }
                        s->internal->init_num = 0;
                        break;

                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->s3->hs.state = SSL3_ST_CR_FINISHED_A;
                        s->internal->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->s3->hs.state = SSL3_ST_CR_KEY_EXCH_A;
                        s->internal->init_num = 0;
                        break;

                case SSL3_ST_CR_FINISHED_A:
                case SSL3_ST_CR_FINISHED_B:
                        if (SSL_is_dtls(s))
                                s->d1->change_cipher_spec_ok = 1;
                        else
                                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 (SSL_is_dtls(s))
                                dtls1_stop_timer(s);

                        if (s->internal->hit)
                                s->s3->hs.state = SSL3_ST_CW_CHANGE_A;
                        else
                                s->s3->hs.state = SSL_ST_OK;
                        s->internal->init_num = 0;
                        break;

                case SSL3_ST_CW_FLUSH:
                        s->internal->rwstate = SSL_WRITING;
                        if (BIO_flush(s->wbio) <= 0) {
                                if (SSL_is_dtls(s)) {
                                        /* If the write error was fatal, stop trying */
                                        if (!BIO_should_retry(s->wbio)) {
                                                s->internal->rwstate = SSL_NOTHING;
                                                s->s3->hs.state = s->s3->hs.tls12.next_state;
                                        }
                                }
                                ret = -1;
                                goto end;
                        }
                        s->internal->rwstate = SSL_NOTHING;
                        s->s3->hs.state = s->s3->hs.tls12.next_state;
                        break;

                case SSL_ST_OK:
                        /* clean a few things up */
                        tls1_cleanup_key_block(s);

                        if (s->s3->handshake_transcript != NULL) {
                                SSLerror(s, ERR_R_INTERNAL_ERROR);
                                ret = -1;
                                goto end;
                        }

                        if (!SSL_is_dtls(s))
                                ssl3_release_init_buffer(s);

                        ssl_free_wbio_buffer(s);

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

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

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

                        ssl_info_callback(s, SSL_CB_HANDSHAKE_DONE, 1);

                        if (SSL_is_dtls(s)) {
                                /* done with handshaking */
                                s->d1->handshake_read_seq = 0;
                                s->d1->next_handshake_write_seq = 0;
                        }

                        goto end;
                        /* break; */

                default:
                        SSLerror(s, SSL_R_UNKNOWN_STATE);
                        ret = -1;
                        goto end;
                        /* break; */
                }

                /* did we do anything */
                if (!s->s3->hs.tls12.reuse_message && !skip) {
                        if (s->internal->debug) {
                                if ((ret = BIO_flush(s->wbio)) <= 0)
                                        goto end;
                        }

                        if (s->s3->hs.state != state) {
                                new_state = s->s3->hs.state;
                                s->s3->hs.state = state;
                                ssl_info_callback(s, SSL_CB_CONNECT_LOOP, 1);
                                s->s3->hs.state = new_state;
                        }
                }
                skip = 0;
        }

 end:
        s->internal->in_handshake--;
        ssl_info_callback(s, SSL_CB_CONNECT_EXIT, ret);

        return (ret);
}

int
ssl3_send_client_hello(SSL *s)
{
        CBB cbb, client_hello, session_id, cookie, cipher_suites;
        CBB compression_methods;
        uint16_t max_version;
        size_t sl;

        memset(&cbb, 0, sizeof(cbb));

        if (s->s3->hs.state == SSL3_ST_CW_CLNT_HELLO_A) {
                SSL_SESSION *sess = s->session;

                if (!ssl_max_supported_version(s, &max_version)) {
                        SSLerror(s, SSL_R_NO_PROTOCOLS_AVAILABLE);
                        return (-1);
                }
                s->version = max_version;

                if (sess == NULL || sess->ssl_version != s->version ||
                    (sess->session_id_length == 0 && sess->tlsext_tick == NULL) ||
                    sess->not_resumable) {
                        if (!ssl_get_new_session(s, 0))
                                goto err;
                }
                /* else use the pre-loaded session */

                /*
                 * If a DTLS ClientHello message is being resent after a
                 * HelloVerifyRequest, we must retain the original client
                 * random value.
                 */
                if (!SSL_is_dtls(s) || s->d1->send_cookie == 0)
                        arc4random_buf(s->s3->client_random, SSL3_RANDOM_SIZE);

                if (!ssl3_handshake_msg_start(s, &cbb, &client_hello,
                    SSL3_MT_CLIENT_HELLO))
                        goto err;

                if (!CBB_add_u16(&client_hello, s->version))
                        goto err;

                /* Random stuff */
                if (!CBB_add_bytes(&client_hello, s->s3->client_random,
                    sizeof(s->s3->client_random)))
                        goto err;

                /* Session ID */
                if (!CBB_add_u8_length_prefixed(&client_hello, &session_id))
                        goto err;
                if (!s->internal->new_session &&
                    s->session->session_id_length > 0) {
                        sl = s->session->session_id_length;
                        if (sl > sizeof(s->session->session_id)) {
                                SSLerror(s, ERR_R_INTERNAL_ERROR);
                                goto err;
                        }
                        if (!CBB_add_bytes(&session_id,
                            s->session->session_id, sl))
                                goto err;
                }

                /* DTLS Cookie. */
                if (SSL_is_dtls(s)) {
                        if (s->d1->cookie_len > sizeof(s->d1->cookie)) {
                                SSLerror(s, ERR_R_INTERNAL_ERROR);
                                goto err;
                        }
                        if (!CBB_add_u8_length_prefixed(&client_hello, &cookie))
                                goto err;
                        if (!CBB_add_bytes(&cookie, s->d1->cookie,
                            s->d1->cookie_len))
                                goto err;
                }

                /* Ciphers supported */
                if (!CBB_add_u16_length_prefixed(&client_hello, &cipher_suites))
                        return 0;
                if (!ssl_cipher_list_to_bytes(s, SSL_get_ciphers(s),
                    &cipher_suites)) {
                        SSLerror(s, SSL_R_NO_CIPHERS_AVAILABLE);
                        goto err;
                }

                /* Add in compression methods (null) */
                if (!CBB_add_u8_length_prefixed(&client_hello,
                    &compression_methods))
                        goto err;
                if (!CBB_add_u8(&compression_methods, 0))
                        goto err;

                /* TLS extensions */
                if (!tlsext_client_build(s, SSL_TLSEXT_MSG_CH, &client_hello)) {
                        SSLerror(s, ERR_R_INTERNAL_ERROR);
                        goto err;
                }

                if (!ssl3_handshake_msg_finish(s, &cbb))
                        goto err;

                s->s3->hs.state = SSL3_ST_CW_CLNT_HELLO_B;
        }

        /* SSL3_ST_CW_CLNT_HELLO_B */
        return (ssl3_handshake_write(s));

 err:
        CBB_cleanup(&cbb);

        return (-1);
}

int
ssl3_get_dtls_hello_verify(SSL *s)
{
        CBS hello_verify_request, cookie;
        size_t cookie_len;
        uint16_t ssl_version;
        int al, ret;

        if ((ret = ssl3_get_message(s, DTLS1_ST_CR_HELLO_VERIFY_REQUEST_A,
            DTLS1_ST_CR_HELLO_VERIFY_REQUEST_B, -1, s->internal->max_cert_list)) <= 0)
                return ret;

        if (s->s3->hs.tls12.message_type != DTLS1_MT_HELLO_VERIFY_REQUEST) {
                s->d1->send_cookie = 0;
                s->s3->hs.tls12.reuse_message = 1;
                return (1);
        }

        if (s->internal->init_num < 0)
                goto decode_err;

        CBS_init(&hello_verify_request, s->internal->init_msg,
            s->internal->init_num);

        if (!CBS_get_u16(&hello_verify_request, &ssl_version))
                goto decode_err;
        if (!CBS_get_u8_length_prefixed(&hello_verify_request, &cookie))
                goto decode_err;
        if (CBS_len(&hello_verify_request) != 0)
                goto decode_err;

        /*
         * Per RFC 6347 section 4.2.1, the HelloVerifyRequest should always
         * contain DTLSv1.0 the version that is going to be negotiated.
         * Tolerate DTLSv1.2 just in case.
         */
        if (ssl_version != DTLS1_VERSION && ssl_version != DTLS1_2_VERSION) {
                SSLerror(s, SSL_R_WRONG_SSL_VERSION);
                s->version = (s->version & 0xff00) | (ssl_version & 0xff);
                al = SSL_AD_PROTOCOL_VERSION;
                goto fatal_err;
        }

        if (!CBS_write_bytes(&cookie, s->d1->cookie,
            sizeof(s->d1->cookie), &cookie_len)) {
                s->d1->cookie_len = 0;
                al = SSL_AD_ILLEGAL_PARAMETER;
                goto fatal_err;
        }
        s->d1->cookie_len = cookie_len;
        s->d1->send_cookie = 1;

        return 1;

 decode_err:
        al = SSL_AD_DECODE_ERROR;
 fatal_err:
        ssl3_send_alert(s, SSL3_AL_FATAL, al);
        return -1;
}

int
ssl3_get_server_hello(SSL *s)
{
        CBS cbs, server_random, session_id;
        uint16_t server_version, cipher_suite;
        uint8_t compression_method;
        const SSL_CIPHER *cipher;
        const SSL_METHOD *method;
        unsigned long alg_k;
        int al, ret;

        s->internal->first_packet = 1;
        if ((ret = ssl3_get_message(s, SSL3_ST_CR_SRVR_HELLO_A,
            SSL3_ST_CR_SRVR_HELLO_B, -1, 20000 /* ?? */)) <= 0)
                return ret;
        s->internal->first_packet = 0;

        if (s->internal->init_num < 0)
                goto decode_err;

        CBS_init(&cbs, s->internal->init_msg, s->internal->init_num);

        if (SSL_is_dtls(s)) {
                if (s->s3->hs.tls12.message_type == DTLS1_MT_HELLO_VERIFY_REQUEST) {
                        if (s->d1->send_cookie == 0) {
                                s->s3->hs.tls12.reuse_message = 1;
                                return (1);
                        } else {
                                /* Already sent a cookie. */
                                al = SSL_AD_UNEXPECTED_MESSAGE;
                                SSLerror(s, SSL_R_BAD_MESSAGE_TYPE);
                                goto fatal_err;
                        }
                }
        }

        if (s->s3->hs.tls12.message_type != SSL3_MT_SERVER_HELLO) {
                al = SSL_AD_UNEXPECTED_MESSAGE;
                SSLerror(s, SSL_R_BAD_MESSAGE_TYPE);
                goto fatal_err;
        }

        if (!CBS_get_u16(&cbs, &server_version))
                goto decode_err;

        if (!ssl_check_version_from_server(s, server_version)) {
                SSLerror(s, SSL_R_WRONG_SSL_VERSION);
                s->version = (s->version & 0xff00) | (server_version & 0xff);
                al = SSL_AD_PROTOCOL_VERSION;
                goto fatal_err;
        }
        s->s3->hs.peer_legacy_version = server_version;
        s->version = server_version;

        s->s3->hs.negotiated_tls_version = ssl_tls_version(server_version);
        if (s->s3->hs.negotiated_tls_version == 0) {
                SSLerror(s, ERR_R_INTERNAL_ERROR);
                goto err;
        }

        if ((method = ssl_get_method(server_version)) == NULL) {
                SSLerror(s, ERR_R_INTERNAL_ERROR);
                goto err;
        }
        s->method = method;

        /* Server random. */
        if (!CBS_get_bytes(&cbs, &server_random, SSL3_RANDOM_SIZE))
                goto decode_err;
        if (!CBS_write_bytes(&server_random, s->s3->server_random,
            sizeof(s->s3->server_random), NULL))
                goto err;

        if (s->s3->hs.our_max_tls_version >= TLS1_2_VERSION &&
            s->s3->hs.negotiated_tls_version < s->s3->hs.our_max_tls_version) {
                /*
                 * RFC 8446 section 4.1.3. We must not downgrade if the server
                 * random value contains the TLS 1.2 or TLS 1.1 magical value.
                 */
                if (!CBS_skip(&server_random,
                    CBS_len(&server_random) - sizeof(tls13_downgrade_12)))
                        goto err;
                if (s->s3->hs.negotiated_tls_version == TLS1_2_VERSION &&
                    CBS_mem_equal(&server_random, tls13_downgrade_12,
                    sizeof(tls13_downgrade_12))) {
                        al = SSL_AD_ILLEGAL_PARAMETER;
                        SSLerror(s, SSL_R_INAPPROPRIATE_FALLBACK);
                        goto fatal_err;
                }
                if (CBS_mem_equal(&server_random, tls13_downgrade_11,
                    sizeof(tls13_downgrade_11))) {
                        al = SSL_AD_ILLEGAL_PARAMETER;
                        SSLerror(s, SSL_R_INAPPROPRIATE_FALLBACK);
                        goto fatal_err;
                }
        }

        /* Session ID. */
        if (!CBS_get_u8_length_prefixed(&cbs, &session_id))
                goto decode_err;

        if (CBS_len(&session_id) > SSL3_SESSION_ID_SIZE) {
                al = SSL_AD_ILLEGAL_PARAMETER;
                SSLerror(s, SSL_R_SSL3_SESSION_ID_TOO_LONG);
                goto fatal_err;
        }

        /* Cipher suite. */
        if (!CBS_get_u16(&cbs, &cipher_suite))
                goto decode_err;

        /*
         * Check if we want to resume the session based on external
         * pre-shared secret.
         */
        if (s->internal->tls_session_secret_cb != NULL) {
                SSL_CIPHER *pref_cipher = NULL;
                int master_key_length = sizeof(s->session->master_key);

                if (!s->internal->tls_session_secret_cb(s,
                    s->session->master_key, &master_key_length, NULL,
                    &pref_cipher, s->internal->tls_session_secret_cb_arg)) {
                        SSLerror(s, ERR_R_INTERNAL_ERROR);
                        goto err;
                }
                if (master_key_length <= 0) {
                        SSLerror(s, ERR_R_INTERNAL_ERROR);
                        goto err;
                }
                s->session->master_key_length = master_key_length;

                if ((s->session->cipher = pref_cipher) == NULL)
                        s->session->cipher =
                            ssl3_get_cipher_by_value(cipher_suite);
                s->s3->flags |= SSL3_FLAGS_CCS_OK;
        }

        if (s->session->session_id_length != 0 &&
            CBS_mem_equal(&session_id, s->session->session_id,
                s->session->session_id_length)) {
                if (s->sid_ctx_length != s->session->sid_ctx_length ||
                    timingsafe_memcmp(s->session->sid_ctx,
                    s->sid_ctx, s->sid_ctx_length) != 0) {
                        /* actually a client application bug */
                        al = SSL_AD_ILLEGAL_PARAMETER;
                        SSLerror(s, SSL_R_ATTEMPT_TO_REUSE_SESSION_IN_DIFFERENT_CONTEXT);
                        goto fatal_err;
                }
                s->s3->flags |= SSL3_FLAGS_CCS_OK;
                s->internal->hit = 1;
        } else {
                /* a miss or crap from the other end */

                /* If we were trying for session-id reuse, make a new
                 * SSL_SESSION so we don't stuff up other people */
                s->internal->hit = 0;
                if (s->session->session_id_length > 0) {
                        if (!ssl_get_new_session(s, 0)) {
                                al = SSL_AD_INTERNAL_ERROR;
                                goto fatal_err;
                        }
                }

                /*
                 * XXX - improve the handling for the case where there is a
                 * zero length session identifier.
                 */
                if (!CBS_write_bytes(&session_id, s->session->session_id,
                    sizeof(s->session->session_id),
                    &s->session->session_id_length))
                        goto err;

                s->session->ssl_version = s->version;
        }

        if ((cipher = ssl3_get_cipher_by_value(cipher_suite)) == NULL) {
                al = SSL_AD_ILLEGAL_PARAMETER;
                SSLerror(s, SSL_R_UNKNOWN_CIPHER_RETURNED);
                goto fatal_err;
        }

        /* TLS v1.2 only ciphersuites require v1.2 or later. */
        if ((cipher->algorithm_ssl & SSL_TLSV1_2) &&
            s->s3->hs.negotiated_tls_version < TLS1_2_VERSION) {
                al = SSL_AD_ILLEGAL_PARAMETER;
                SSLerror(s, SSL_R_WRONG_CIPHER_RETURNED);
                goto fatal_err;
        }

        if (!ssl_cipher_in_list(SSL_get_ciphers(s), cipher)) {
                /* we did not say we would use this cipher */
                al = SSL_AD_ILLEGAL_PARAMETER;
                SSLerror(s, SSL_R_WRONG_CIPHER_RETURNED);
                goto fatal_err;
        }

        /*
         * Depending on the session caching (internal/external), the cipher
         * and/or cipher_id values may not be set. Make sure that
         * cipher_id is set and use it for comparison.
         */
        if (s->session->cipher)
                s->session->cipher_id = s->session->cipher->id;
        if (s->internal->hit && (s->session->cipher_id != cipher->id)) {
                al = SSL_AD_ILLEGAL_PARAMETER;
                SSLerror(s, SSL_R_OLD_SESSION_CIPHER_NOT_RETURNED);
                goto fatal_err;
        }
        s->s3->hs.cipher = cipher;

        if (!tls1_transcript_hash_init(s))
                goto err;

        /*
         * Don't digest cached records if no sigalgs: we may need them for
         * client authentication.
         */
        alg_k = s->s3->hs.cipher->algorithm_mkey;
        if (!(SSL_USE_SIGALGS(s) || (alg_k & SSL_kGOST)))
                tls1_transcript_free(s);

        if (!CBS_get_u8(&cbs, &compression_method))
                goto decode_err;

        if (compression_method != 0) {
                al = SSL_AD_ILLEGAL_PARAMETER;
                SSLerror(s, SSL_R_UNSUPPORTED_COMPRESSION_ALGORITHM);
                goto fatal_err;
        }

        if (!tlsext_client_parse(s, SSL_TLSEXT_MSG_SH, &cbs, &al)) {
                SSLerror(s, SSL_R_PARSE_TLSEXT);
                goto fatal_err;
        }

        if (CBS_len(&cbs) != 0)
                goto decode_err;

        /*
         * Determine if we need to see RI. Strictly speaking if we want to
         * avoid an attack we should *always* see RI even on initial server
         * hello because the client doesn't see any renegotiation during an
         * attack. However this would mean we could not connect to any server
         * which doesn't support RI so for the immediate future tolerate RI
         * absence on initial connect only.
         */
        if (!s->s3->renegotiate_seen &&
            !(s->internal->options & SSL_OP_LEGACY_SERVER_CONNECT)) {
                al = SSL_AD_HANDSHAKE_FAILURE;
                SSLerror(s, SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
                goto fatal_err;
        }

        if (ssl_check_serverhello_tlsext(s) <= 0) {
                SSLerror(s, SSL_R_SERVERHELLO_TLSEXT);
                goto err;
        }

        return (1);

 decode_err:
        /* wrong packet length */
        al = SSL_AD_DECODE_ERROR;
        SSLerror(s, SSL_R_BAD_PACKET_LENGTH);
 fatal_err:
        ssl3_send_alert(s, SSL3_AL_FATAL, al);
 err:
        return (-1);
}

int
ssl3_get_server_certificate(SSL *s)
{
        CBS cbs, cert_list, cert_data;
        STACK_OF(X509) *certs = NULL;
        X509 *cert = NULL;
        const uint8_t *p;
        int al, ret;

        if ((ret = ssl3_get_message(s, SSL3_ST_CR_CERT_A,
            SSL3_ST_CR_CERT_B, -1, s->internal->max_cert_list)) <= 0)
                return ret;

        ret = -1;

        if (s->s3->hs.tls12.message_type == SSL3_MT_SERVER_KEY_EXCHANGE) {
                s->s3->hs.tls12.reuse_message = 1;
                return (1);
        }

        if (s->s3->hs.tls12.message_type != SSL3_MT_CERTIFICATE) {
                al = SSL_AD_UNEXPECTED_MESSAGE;
                SSLerror(s, SSL_R_BAD_MESSAGE_TYPE);
                goto fatal_err;
        }

        if ((certs = sk_X509_new_null()) == NULL) {
                SSLerror(s, ERR_R_MALLOC_FAILURE);
                goto err;
        }

        if (s->internal->init_num < 0)
                goto decode_err;

        CBS_init(&cbs, s->internal->init_msg, s->internal->init_num);

        if (!CBS_get_u24_length_prefixed(&cbs, &cert_list))
                goto decode_err;
        if (CBS_len(&cbs) != 0)
                goto decode_err;

        while (CBS_len(&cert_list) > 0) {
                if (!CBS_get_u24_length_prefixed(&cert_list, &cert_data))
                        goto decode_err;
                p = CBS_data(&cert_data);
                if ((cert = d2i_X509(NULL, &p, CBS_len(&cert_data))) == NULL) {
                        al = SSL_AD_BAD_CERTIFICATE;
                        SSLerror(s, ERR_R_ASN1_LIB);
                        goto fatal_err;
                }
                if (p != CBS_data(&cert_data) + CBS_len(&cert_data))
                        goto decode_err;
                if (!sk_X509_push(certs, cert)) {
                        SSLerror(s, ERR_R_MALLOC_FAILURE);
                        goto err;
                }
                cert = NULL;
        }

        /* A server must always provide a non-empty certificate list. */
        if (sk_X509_num(certs) < 1) {
                SSLerror(s, SSL_R_PEER_DID_NOT_RETURN_A_CERTIFICATE);
                goto decode_err;
        }

        if (ssl_verify_cert_chain(s, certs) <= 0 &&
            s->verify_mode != SSL_VERIFY_NONE) {
                al = ssl_verify_alarm_type(s->verify_result);
                SSLerror(s, SSL_R_CERTIFICATE_VERIFY_FAILED);
                goto fatal_err;
        }
        s->session->verify_result = s->verify_result;
        ERR_clear_error();

        if (!tls_process_peer_certs(s, certs))
                goto err;

        ret = 1;

        if (0) {
 decode_err:
                /* wrong packet length */
                al = SSL_AD_DECODE_ERROR;
                SSLerror(s, SSL_R_BAD_PACKET_LENGTH);
 fatal_err:
                ssl3_send_alert(s, SSL3_AL_FATAL, al);
        }
 err:
        sk_X509_pop_free(certs, X509_free);
        X509_free(cert);

        return (ret);
}

static int
ssl3_get_server_kex_dhe(SSL *s, CBS *cbs)
{
        int decode_error, invalid_params, invalid_key;
        int nid = NID_dhKeyAgreement;

        tls_key_share_free(s->s3->hs.key_share);
        if ((s->s3->hs.key_share = tls_key_share_new_nid(nid)) == NULL)
                goto err;

        if (!tls_key_share_peer_params(s->s3->hs.key_share, cbs,
            &decode_error, &invalid_params)) {
                if (decode_error) {
                        SSLerror(s, SSL_R_BAD_PACKET_LENGTH);
                        ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
                }
                goto err;
        }
        if (!tls_key_share_peer_public(s->s3->hs.key_share, cbs,
            &decode_error, &invalid_key)) {
                if (decode_error) {
                        SSLerror(s, SSL_R_BAD_PACKET_LENGTH);
                        ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
                }
                goto err;
        }

        if (invalid_params) {
                SSLerror(s, SSL_R_BAD_DH_P_LENGTH);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
                goto err;
        }
        if (invalid_key) {
                SSLerror(s, SSL_R_BAD_DH_PUB_KEY_LENGTH);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
                goto err;
        }

        if (!tls_key_share_peer_security(s, s->s3->hs.key_share)) {
                SSLerror(s, SSL_R_DH_KEY_TOO_SMALL);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
                return 0;
        }

        return 1;

 err:
        return 0;
}

static int
ssl3_get_server_kex_ecdhe(SSL *s, CBS *cbs)
{
        uint8_t curve_type;
        uint16_t group_id;
        int decode_error;
        CBS public;

        if (!CBS_get_u8(cbs, &curve_type))
                goto decode_err;
        if (!CBS_get_u16(cbs, &group_id))
                goto decode_err;

        /* Only named curves are supported. */
        if (curve_type != NAMED_CURVE_TYPE) {
                SSLerror(s, SSL_R_UNSUPPORTED_ELLIPTIC_CURVE);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
                goto err;
        }

        if (!CBS_get_u8_length_prefixed(cbs, &public))
                goto decode_err;

        /*
         * Check that the group is one of our preferences - if it is not,
         * the server has sent us an invalid group.
         */
        if (!tls1_check_group(s, group_id)) {
                SSLerror(s, SSL_R_WRONG_CURVE);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
                goto err;
        }

        tls_key_share_free(s->s3->hs.key_share);
        if ((s->s3->hs.key_share = tls_key_share_new(group_id)) == NULL)
                goto err;

        if (!tls_key_share_peer_public(s->s3->hs.key_share, &public,
            &decode_error, NULL)) {
                if (decode_error)
                        goto decode_err;
                goto err;
        }

        return 1;

 decode_err:
        SSLerror(s, SSL_R_BAD_PACKET_LENGTH);
        ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
 err:
        return 0;
}

int
ssl3_get_server_key_exchange(SSL *s)
{
        CBS cbs, signature;
        EVP_MD_CTX *md_ctx;
        const unsigned char *param;
        size_t param_len;
        long alg_k, alg_a;
        int al, ret;

        alg_k = s->s3->hs.cipher->algorithm_mkey;
        alg_a = s->s3->hs.cipher->algorithm_auth;

        /*
         * Use same message size as in ssl3_get_certificate_request()
         * as ServerKeyExchange message may be skipped.
         */
        if ((ret = ssl3_get_message(s, SSL3_ST_CR_KEY_EXCH_A,
            SSL3_ST_CR_KEY_EXCH_B, -1, s->internal->max_cert_list)) <= 0)
                return ret;

        if ((md_ctx = EVP_MD_CTX_new()) == NULL)
                goto err;

        if (s->internal->init_num < 0)
                goto err;

        CBS_init(&cbs, s->internal->init_msg, s->internal->init_num);

        if (s->s3->hs.tls12.message_type != SSL3_MT_SERVER_KEY_EXCHANGE) {
                /*
                 * Do not skip server key exchange if this cipher suite uses
                 * ephemeral keys.
                 */
                if (alg_k & (SSL_kDHE|SSL_kECDHE)) {
                        SSLerror(s, SSL_R_UNEXPECTED_MESSAGE);
                        al = SSL_AD_UNEXPECTED_MESSAGE;
                        goto fatal_err;
                }

                s->s3->hs.tls12.reuse_message = 1;
                EVP_MD_CTX_free(md_ctx);
                return (1);
        }

        param = CBS_data(&cbs);
        param_len = CBS_len(&cbs);

        if (alg_k & SSL_kDHE) {
                if (!ssl3_get_server_kex_dhe(s, &cbs))
                        goto err;
        } else if (alg_k & SSL_kECDHE) {
                if (!ssl3_get_server_kex_ecdhe(s, &cbs))
                        goto err;
        } else if (alg_k != 0) {
                al = SSL_AD_UNEXPECTED_MESSAGE;
                SSLerror(s, SSL_R_UNEXPECTED_MESSAGE);
                goto fatal_err;
        }

        param_len -= CBS_len(&cbs);

        /* if it was signed, check the signature */
        if ((alg_a & SSL_aNULL) == 0) {
                uint16_t sigalg_value = SIGALG_NONE;
                const struct ssl_sigalg *sigalg;
                EVP_PKEY_CTX *pctx;
                EVP_PKEY *pkey = NULL;

                if ((alg_a & SSL_aRSA) != 0 &&
                    s->session->peer_cert_type == SSL_PKEY_RSA) {
                        pkey = X509_get0_pubkey(s->session->peer_cert);
                } else if ((alg_a & SSL_aECDSA) != 0 &&
                    s->session->peer_cert_type == SSL_PKEY_ECC) {
                        pkey = X509_get0_pubkey(s->session->peer_cert);
                }
                if (pkey == NULL) {
                        al = SSL_AD_ILLEGAL_PARAMETER;
                        SSLerror(s, SSL_R_UNKNOWN_CERTIFICATE_TYPE);
                        goto fatal_err;
                }

                if (SSL_USE_SIGALGS(s)) {
                        if (!CBS_get_u16(&cbs, &sigalg_value))
                                goto decode_err;
                }
                if (!CBS_get_u16_length_prefixed(&cbs, &signature))
                        goto decode_err;
                if (CBS_len(&signature) > EVP_PKEY_size(pkey)) {
                        al = SSL_AD_DECODE_ERROR;
                        SSLerror(s, SSL_R_WRONG_SIGNATURE_LENGTH);
                        goto fatal_err;
                }

                if ((sigalg = ssl_sigalg_for_peer(s, pkey,
                    sigalg_value)) == NULL) {
                        al = SSL_AD_DECODE_ERROR;
                        goto fatal_err;
                }
                s->s3->hs.peer_sigalg = sigalg;

                if (!EVP_DigestVerifyInit(md_ctx, &pctx, sigalg->md(),
                    NULL, pkey))
                        goto err;
                if (!EVP_DigestVerifyUpdate(md_ctx, s->s3->client_random,
                    SSL3_RANDOM_SIZE))
                        goto err;
                if ((sigalg->flags & SIGALG_FLAG_RSA_PSS) &&
                    (!EVP_PKEY_CTX_set_rsa_padding(pctx,
                    RSA_PKCS1_PSS_PADDING) ||
                    !EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1)))
                        goto err;
                if (!EVP_DigestVerifyUpdate(md_ctx, s->s3->server_random,
                    SSL3_RANDOM_SIZE))
                        goto err;
                if (!EVP_DigestVerifyUpdate(md_ctx, param, param_len))
                        goto err;
                if (EVP_DigestVerifyFinal(md_ctx, CBS_data(&signature),
                    CBS_len(&signature)) <= 0) {
                        al = SSL_AD_DECRYPT_ERROR;
                        SSLerror(s, SSL_R_BAD_SIGNATURE);
                        goto fatal_err;
                }
        }

        if (CBS_len(&cbs) != 0) {
                al = SSL_AD_DECODE_ERROR;
                SSLerror(s, SSL_R_EXTRA_DATA_IN_MESSAGE);
                goto fatal_err;
        }

        EVP_MD_CTX_free(md_ctx);

        return (1);

 decode_err:
        al = SSL_AD_DECODE_ERROR;
        SSLerror(s, SSL_R_BAD_PACKET_LENGTH);

 fatal_err:
        ssl3_send_alert(s, SSL3_AL_FATAL, al);

 err:
        EVP_MD_CTX_free(md_ctx);

        return (-1);
}

int
ssl3_get_certificate_request(SSL *s)
{
        CBS cert_request, cert_types, rdn_list;
        X509_NAME *xn = NULL;
        const unsigned char *q;
        STACK_OF(X509_NAME) *ca_sk = NULL;
        int ret;

        if ((ret = ssl3_get_message(s, SSL3_ST_CR_CERT_REQ_A,
            SSL3_ST_CR_CERT_REQ_B, -1, s->internal->max_cert_list)) <= 0)
                return ret;

        ret = 0;

        s->s3->hs.tls12.cert_request = 0;

        if (s->s3->hs.tls12.message_type == SSL3_MT_SERVER_DONE) {
                s->s3->hs.tls12.reuse_message = 1;
                /*
                 * If we get here we don't need any cached handshake records
                 * as we wont be doing client auth.
                 */
                tls1_transcript_free(s);
                return (1);
        }

        if (s->s3->hs.tls12.message_type != SSL3_MT_CERTIFICATE_REQUEST) {
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
                SSLerror(s, SSL_R_WRONG_MESSAGE_TYPE);
                goto err;
        }

        /* TLS does not like anon-DH with client cert */
        if (s->s3->hs.cipher->algorithm_auth & SSL_aNULL) {
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
                SSLerror(s, SSL_R_TLS_CLIENT_CERT_REQ_WITH_ANON_CIPHER);
                goto err;
        }

        if (s->internal->init_num < 0)
                goto decode_err;
        CBS_init(&cert_request, s->internal->init_msg, s->internal->init_num);

        if ((ca_sk = sk_X509_NAME_new(ca_dn_cmp)) == NULL) {
                SSLerror(s, ERR_R_MALLOC_FAILURE);
                goto err;
        }

        if (!CBS_get_u8_length_prefixed(&cert_request, &cert_types))
                goto decode_err;

        if (SSL_USE_SIGALGS(s)) {
                CBS sigalgs;

                if (CBS_len(&cert_request) < 2) {
                        SSLerror(s, SSL_R_DATA_LENGTH_TOO_LONG);
                        goto err;
                }
                if (!CBS_get_u16_length_prefixed(&cert_request, &sigalgs)) {
                        ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
                        SSLerror(s, SSL_R_DATA_LENGTH_TOO_LONG);
                        goto err;
                }
                if (CBS_len(&sigalgs) % 2 != 0 || CBS_len(&sigalgs) > 64) {
                        ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
                        SSLerror(s, SSL_R_SIGNATURE_ALGORITHMS_ERROR);
                        goto err;
                }
                if (!CBS_stow(&sigalgs, &s->s3->hs.sigalgs,
                    &s->s3->hs.sigalgs_len))
                        goto err;
        }

        /* get the CA RDNs */
        if (CBS_len(&cert_request) < 2) {
                SSLerror(s, SSL_R_DATA_LENGTH_TOO_LONG);
                goto err;
        }

        if (!CBS_get_u16_length_prefixed(&cert_request, &rdn_list) ||
            CBS_len(&cert_request) != 0) {
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
                SSLerror(s, SSL_R_LENGTH_MISMATCH);
                goto err;
        }

        while (CBS_len(&rdn_list) > 0) {
                CBS rdn;

                if (CBS_len(&rdn_list) < 2) {
                        SSLerror(s, SSL_R_DATA_LENGTH_TOO_LONG);
                        goto err;
                }

                if (!CBS_get_u16_length_prefixed(&rdn_list, &rdn)) {
                        ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
                        SSLerror(s, SSL_R_CA_DN_TOO_LONG);
                        goto err;
                }

                q = CBS_data(&rdn);
                if ((xn = d2i_X509_NAME(NULL, &q, CBS_len(&rdn))) == NULL) {
                        ssl3_send_alert(s, SSL3_AL_FATAL,
                            SSL_AD_DECODE_ERROR);
                        SSLerror(s, ERR_R_ASN1_LIB);
                        goto err;
                }

                if (q != CBS_data(&rdn) + CBS_len(&rdn)) {
                        ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
                        SSLerror(s, SSL_R_CA_DN_LENGTH_MISMATCH);
                        goto err;
                }
                if (!sk_X509_NAME_push(ca_sk, xn)) {
                        SSLerror(s, ERR_R_MALLOC_FAILURE);
                        goto err;
                }
                xn = NULL;      /* avoid free in err block */
        }

        /* we should setup a certificate to return.... */
        s->s3->hs.tls12.cert_request = 1;
        sk_X509_NAME_pop_free(s->s3->hs.tls12.ca_names, X509_NAME_free);
        s->s3->hs.tls12.ca_names = ca_sk;
        ca_sk = NULL;

        ret = 1;
        if (0) {
 decode_err:
                SSLerror(s, SSL_R_BAD_PACKET_LENGTH);
        }
 err:
        X509_NAME_free(xn);
        sk_X509_NAME_pop_free(ca_sk, X509_NAME_free);
        return (ret);
}

static int
ca_dn_cmp(const X509_NAME * const *a, const X509_NAME * const *b)
{
        return (X509_NAME_cmp(*a, *b));
}

int
ssl3_get_new_session_ticket(SSL *s)
{
        uint32_t lifetime_hint;
        CBS cbs, session_ticket;
        unsigned int session_id_length = 0;
        int al, ret;

        if ((ret = ssl3_get_message(s, SSL3_ST_CR_SESSION_TICKET_A,
            SSL3_ST_CR_SESSION_TICKET_B, -1, 16384)) <= 0)
                return ret;

        if (s->s3->hs.tls12.message_type == SSL3_MT_FINISHED) {
                s->s3->hs.tls12.reuse_message = 1;
                return (1);
        }
        if (s->s3->hs.tls12.message_type != SSL3_MT_NEWSESSION_TICKET) {
                al = SSL_AD_UNEXPECTED_MESSAGE;
                SSLerror(s, SSL_R_BAD_MESSAGE_TYPE);
                goto fatal_err;
        }

        if (s->internal->init_num < 0) {
                al = SSL_AD_DECODE_ERROR;
                SSLerror(s, SSL_R_LENGTH_MISMATCH);
                goto fatal_err;
        }

        CBS_init(&cbs, s->internal->init_msg, s->internal->init_num);
        if (!CBS_get_u32(&cbs, &lifetime_hint) ||
            !CBS_get_u16_length_prefixed(&cbs, &session_ticket) ||
            CBS_len(&cbs) != 0) {
                al = SSL_AD_DECODE_ERROR;
                SSLerror(s, SSL_R_LENGTH_MISMATCH);
                goto fatal_err;
        }
        s->session->tlsext_tick_lifetime_hint = lifetime_hint;

        if (!CBS_stow(&session_ticket, &s->session->tlsext_tick,
            &s->session->tlsext_ticklen)) {
                SSLerror(s, ERR_R_MALLOC_FAILURE);
                goto err;
        }

        /*
         * There are two ways to detect a resumed ticket sesion.
         * One is to set an appropriate session ID and then the server
         * must return a match in ServerHello. This allows the normal
         * client session ID matching to work and we know much
         * earlier that the ticket has been accepted.
         *
         * The other way is to set zero length session ID when the
         * ticket is presented and rely on the handshake to determine
         * session resumption.
         *
         * We choose the former approach because this fits in with
         * assumptions elsewhere in OpenSSL. The session ID is set
         * to the SHA256 hash of the ticket.
         */
        if (!EVP_Digest(CBS_data(&session_ticket), CBS_len(&session_ticket),
            s->session->session_id, &session_id_length, EVP_sha256(), NULL)) {
                al = SSL_AD_INTERNAL_ERROR;
                SSLerror(s, ERR_R_EVP_LIB);
                goto fatal_err;
        }
        s->session->session_id_length = session_id_length;

        return (1);

 fatal_err:
        ssl3_send_alert(s, SSL3_AL_FATAL, al);
 err:
        return (-1);
}

int
ssl3_get_cert_status(SSL *s)
{
        CBS cert_status, response;
        uint8_t status_type;
        int al, ret;

        if ((ret = ssl3_get_message(s, SSL3_ST_CR_CERT_STATUS_A,
            SSL3_ST_CR_CERT_STATUS_B, -1, 16384)) <= 0)
                return ret;

        if (s->s3->hs.tls12.message_type == SSL3_MT_SERVER_KEY_EXCHANGE) {
                /*
                 * Tell the callback the server did not send us an OSCP
                 * response, and has decided to head directly to key exchange.
                 */
                if (s->ctx->internal->tlsext_status_cb) {
                        free(s->internal->tlsext_ocsp_resp);
                        s->internal->tlsext_ocsp_resp = NULL;
                        s->internal->tlsext_ocsp_resp_len = 0;

                        ret = s->ctx->internal->tlsext_status_cb(s,
                            s->ctx->internal->tlsext_status_arg);
                        if (ret == 0) {
                                al = SSL_AD_BAD_CERTIFICATE_STATUS_RESPONSE;
                                SSLerror(s, SSL_R_INVALID_STATUS_RESPONSE);
                                goto fatal_err;
                        }
                        if (ret < 0) {
                                al = SSL_AD_INTERNAL_ERROR;
                                SSLerror(s, ERR_R_MALLOC_FAILURE);
                                goto fatal_err;
                        }
                }
                s->s3->hs.tls12.reuse_message = 1;
                return (1);
        }

        if (s->s3->hs.tls12.message_type != SSL3_MT_CERTIFICATE &&
            s->s3->hs.tls12.message_type != SSL3_MT_CERTIFICATE_STATUS) {
                al = SSL_AD_UNEXPECTED_MESSAGE;
                SSLerror(s, SSL_R_BAD_MESSAGE_TYPE);
                goto fatal_err;
        }

        if (s->internal->init_num < 0) {
                /* need at least status type + length */
                al = SSL_AD_DECODE_ERROR;
                SSLerror(s, SSL_R_LENGTH_MISMATCH);
                goto fatal_err;
        }

        CBS_init(&cert_status, s->internal->init_msg, s->internal->init_num);
        if (!CBS_get_u8(&cert_status, &status_type) ||
            CBS_len(&cert_status) < 3) {
                /* need at least status type + length */
                al = SSL_AD_DECODE_ERROR;
                SSLerror(s, SSL_R_LENGTH_MISMATCH);
                goto fatal_err;
        }

        if (status_type != TLSEXT_STATUSTYPE_ocsp) {
                al = SSL_AD_DECODE_ERROR;
                SSLerror(s, SSL_R_UNSUPPORTED_STATUS_TYPE);
                goto fatal_err;
        }

        if (!CBS_get_u24_length_prefixed(&cert_status, &response) ||
            CBS_len(&cert_status) != 0) {
                al = SSL_AD_DECODE_ERROR;
                SSLerror(s, SSL_R_LENGTH_MISMATCH);
                goto fatal_err;
        }

        if (!CBS_stow(&response, &s->internal->tlsext_ocsp_resp,
            &s->internal->tlsext_ocsp_resp_len)) {
                al = SSL_AD_INTERNAL_ERROR;
                SSLerror(s, ERR_R_MALLOC_FAILURE);
                goto fatal_err;
        }

        if (s->ctx->internal->tlsext_status_cb) {
                ret = s->ctx->internal->tlsext_status_cb(s,
                    s->ctx->internal->tlsext_status_arg);
                if (ret == 0) {
                        al = SSL_AD_BAD_CERTIFICATE_STATUS_RESPONSE;
                        SSLerror(s, SSL_R_INVALID_STATUS_RESPONSE);
                        goto fatal_err;
                }
                if (ret < 0) {
                        al = SSL_AD_INTERNAL_ERROR;
                        SSLerror(s, ERR_R_MALLOC_FAILURE);
                        goto fatal_err;
                }
        }
        return (1);
 fatal_err:
        ssl3_send_alert(s, SSL3_AL_FATAL, al);
        return (-1);
}

int
ssl3_get_server_done(SSL *s)
{
        int ret;

        if ((ret = ssl3_get_message(s, SSL3_ST_CR_SRVR_DONE_A,
            SSL3_ST_CR_SRVR_DONE_B, SSL3_MT_SERVER_DONE, 
            30 /* should be very small, like 0 :-) */)) <= 0)
                return ret;

        if (s->internal->init_num != 0) {
                /* should contain no data */
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
                SSLerror(s, SSL_R_LENGTH_MISMATCH);
                return -1;
        }

        return 1;
}

static int
ssl3_send_client_kex_rsa(SSL *s, CBB *cbb)
{
        unsigned char pms[SSL_MAX_MASTER_KEY_LENGTH];
        unsigned char *enc_pms = NULL;
        uint16_t max_legacy_version;
        EVP_PKEY *pkey;
        RSA *rsa;
        int ret = 0;
        int enc_len;
        CBB epms;

        /*
         * RSA-Encrypted Premaster Secret Message - RFC 5246 section 7.4.7.1.
         */

        pkey = X509_get0_pubkey(s->session->peer_cert);
        if (pkey == NULL || (rsa = EVP_PKEY_get0_RSA(pkey)) == NULL) {
                SSLerror(s, ERR_R_INTERNAL_ERROR);
                goto err;
        }

        /*
         * Our maximum legacy protocol version - while RFC 5246 section 7.4.7.1
         * says "The latest (newest) version supported by the client", if we're
         * doing RSA key exchange then we have to presume that we're talking to
         * a server that does not understand the supported versions extension
         * and therefore our maximum version is that sent in the ClientHello.
         */
        if (!ssl_max_legacy_version(s, &max_legacy_version))
                goto err;
        pms[0] = max_legacy_version >> 8;
        pms[1] = max_legacy_version & 0xff;
        arc4random_buf(&pms[2], sizeof(pms) - 2);

        if ((enc_pms = malloc(RSA_size(rsa))) == NULL) {
                SSLerror(s, ERR_R_MALLOC_FAILURE);
                goto err;
        }

        enc_len = RSA_public_encrypt(sizeof(pms), pms, enc_pms, rsa,
            RSA_PKCS1_PADDING);
        if (enc_len <= 0) {
                SSLerror(s, SSL_R_BAD_RSA_ENCRYPT);
                goto err;
        }

        if (!CBB_add_u16_length_prefixed(cbb, &epms))
                goto err;
        if (!CBB_add_bytes(&epms, enc_pms, enc_len))
                goto err;
        if (!CBB_flush(cbb))
                goto err;

        if (!tls12_derive_master_secret(s, pms, sizeof(pms)))
                goto err;

        ret = 1;

 err:
        explicit_bzero(pms, sizeof(pms));
        free(enc_pms);

        return ret;
}

static int
ssl3_send_client_kex_dhe(SSL *s, CBB *cbb)
{
        uint8_t *key = NULL;
        size_t key_len = 0;
        int ret = 0;

        /* Ensure that we have an ephemeral key from the server for DHE. */
        if (s->s3->hs.key_share == NULL) {
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
                SSLerror(s, SSL_R_UNABLE_TO_FIND_DH_PARAMETERS);
                goto err;
        }

        if (!tls_key_share_generate(s->s3->hs.key_share))
                goto err;
        if (!tls_key_share_public(s->s3->hs.key_share, cbb))
                goto err;
        if (!tls_key_share_derive(s->s3->hs.key_share, &key, &key_len))
                goto err;

        if (!tls_key_share_peer_security(s, s->s3->hs.key_share)) {
                SSLerror(s, SSL_R_DH_KEY_TOO_SMALL);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
                return 0;
        }

        if (!tls12_derive_master_secret(s, key, key_len))
                goto err;

        ret = 1;

 err:
        freezero(key, key_len);

        return ret;
}

static int
ssl3_send_client_kex_ecdhe(SSL *s, CBB *cbb)
{
        uint8_t *key = NULL;
        size_t key_len = 0;
        CBB public;
        int ret = 0;

        /* Ensure that we have an ephemeral key for ECDHE. */
        if (s->s3->hs.key_share == NULL) {
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
                SSLerror(s, ERR_R_INTERNAL_ERROR);
                goto err;
        }

        if (!tls_key_share_generate(s->s3->hs.key_share))
                goto err;

        if (!CBB_add_u8_length_prefixed(cbb, &public))
                return 0;
        if (!tls_key_share_public(s->s3->hs.key_share, &public))
                goto err;
        if (!CBB_flush(cbb))
                goto err;

        if (!tls_key_share_derive(s->s3->hs.key_share, &key, &key_len))
                goto err;

        if (!tls12_derive_master_secret(s, key, key_len))
                goto err;

        ret = 1;

 err:
        freezero(key, key_len);

        return ret;
}

static int
ssl3_send_client_kex_gost(SSL *s, CBB *cbb)
{
        unsigned char premaster_secret[32], shared_ukm[32], tmp[256];
        EVP_PKEY_CTX *pkey_ctx = NULL;
        EVP_MD_CTX *ukm_hash = NULL;
        EVP_PKEY *pkey;
        size_t msglen;
        unsigned int md_len;
        CBB gostblob;
        int nid;
        int ret = 0;

        /* Get server sertificate PKEY and create ctx from it */
        pkey = X509_get0_pubkey(s->session->peer_cert);
        if (pkey == NULL || s->session->peer_cert_type != SSL_PKEY_GOST01) {
                SSLerror(s, SSL_R_NO_GOST_CERTIFICATE_SENT_BY_PEER);
                goto err;
        }
        if ((pkey_ctx = EVP_PKEY_CTX_new(pkey, NULL)) == NULL) {
                SSLerror(s, ERR_R_MALLOC_FAILURE);
                goto err;
        }

        /*
         * If we have send a certificate, and certificate key parameters match
         * those of server certificate, use certificate key for key exchange.
         * Otherwise, generate ephemeral key pair.
         */
        if (EVP_PKEY_encrypt_init(pkey_ctx) <= 0)
                goto err;

        /* Generate session key. */
        arc4random_buf(premaster_secret, sizeof(premaster_secret));

        /*
         * If we have client certificate, use its secret as peer key.
         * XXX - this presumably lacks PFS.
         */
        if (s->s3->hs.tls12.cert_request != 0 &&
            s->cert->key->privatekey != NULL) {
                if (EVP_PKEY_derive_set_peer(pkey_ctx,
                    s->cert->key->privatekey) <=0) {
                        /*
                         * If there was an error - just ignore it.
                         * Ephemeral key would be used.
                         */
                        ERR_clear_error();
                }
        }

        /*
         * Compute shared IV and store it in algorithm-specific context data.
         */
        if ((ukm_hash = EVP_MD_CTX_new()) == NULL) {
                SSLerror(s, ERR_R_MALLOC_FAILURE);
                goto err;
        }

        /* XXX check handshake hash instead. */
        if (s->s3->hs.cipher->algorithm2 & SSL_HANDSHAKE_MAC_GOST94)
                nid = NID_id_GostR3411_94;
        else
                nid = NID_id_tc26_gost3411_2012_256;
        if (!EVP_DigestInit(ukm_hash, EVP_get_digestbynid(nid)))
                goto err;
        if (!EVP_DigestUpdate(ukm_hash, s->s3->client_random, SSL3_RANDOM_SIZE))
                goto err;
        if (!EVP_DigestUpdate(ukm_hash, s->s3->server_random, SSL3_RANDOM_SIZE))
                goto err;
        if (!EVP_DigestFinal_ex(ukm_hash, shared_ukm, &md_len))
                goto err;
        if (EVP_PKEY_CTX_ctrl(pkey_ctx, -1, EVP_PKEY_OP_ENCRYPT,
            EVP_PKEY_CTRL_SET_IV, 8, shared_ukm) < 0) {
                SSLerror(s, SSL_R_LIBRARY_BUG);
                goto err;
        }

        /*
         * Make GOST keytransport blob message, encapsulate it into sequence.
         */
        msglen = 255;
        if (EVP_PKEY_encrypt(pkey_ctx, tmp, &msglen, premaster_secret,
            sizeof(premaster_secret)) < 0) {
                SSLerror(s, SSL_R_LIBRARY_BUG);
                goto err;
        }

        if (!CBB_add_asn1(cbb, &gostblob, CBS_ASN1_SEQUENCE))
                goto err;
        if (!CBB_add_bytes(&gostblob, tmp, msglen))
                goto err;
        if (!CBB_flush(cbb))
                goto err;

        /* Check if pubkey from client certificate was used. */
        if (EVP_PKEY_CTX_ctrl(pkey_ctx, -1, -1, EVP_PKEY_CTRL_PEER_KEY, 2,
            NULL) > 0)
                s->s3->flags |= TLS1_FLAGS_SKIP_CERT_VERIFY;

        if (!tls12_derive_master_secret(s, premaster_secret, 32))
                goto err;

        ret = 1;

 err:
        explicit_bzero(premaster_secret, sizeof(premaster_secret));
        EVP_PKEY_CTX_free(pkey_ctx);
        EVP_MD_CTX_free(ukm_hash);

        return ret;
}

int
ssl3_send_client_key_exchange(SSL *s)
{
        unsigned long alg_k;
        CBB cbb, kex;

        memset(&cbb, 0, sizeof(cbb));

        if (s->s3->hs.state == SSL3_ST_CW_KEY_EXCH_A) {
                alg_k = s->s3->hs.cipher->algorithm_mkey;

                if (!ssl3_handshake_msg_start(s, &cbb, &kex,
                    SSL3_MT_CLIENT_KEY_EXCHANGE))
                        goto err;

                if (alg_k & SSL_kRSA) {
                        if (!ssl3_send_client_kex_rsa(s, &kex))
                                goto err;
                } else if (alg_k & SSL_kDHE) {
                        if (!ssl3_send_client_kex_dhe(s, &kex))
                                goto err;
                } else if (alg_k & SSL_kECDHE) {
                        if (!ssl3_send_client_kex_ecdhe(s, &kex))
                                goto err;
                } else if (alg_k & SSL_kGOST) {
                        if (!ssl3_send_client_kex_gost(s, &kex))
                                goto err;
                } else {
                        ssl3_send_alert(s, SSL3_AL_FATAL,
                            SSL_AD_HANDSHAKE_FAILURE);
                        SSLerror(s, ERR_R_INTERNAL_ERROR);
                        goto err;
                }

                if (!ssl3_handshake_msg_finish(s, &cbb))
                        goto err;

                s->s3->hs.state = SSL3_ST_CW_KEY_EXCH_B;
        }

        /* SSL3_ST_CW_KEY_EXCH_B */
        return (ssl3_handshake_write(s));

 err:
        CBB_cleanup(&cbb);

        return (-1);
}

static int
ssl3_send_client_verify_sigalgs(SSL *s, EVP_PKEY *pkey,
    const struct ssl_sigalg *sigalg, CBB *cert_verify)
{
        CBB cbb_signature;
        EVP_PKEY_CTX *pctx = NULL;
        EVP_MD_CTX *mctx = NULL;
        const unsigned char *hdata;
        unsigned char *signature = NULL;
        size_t signature_len, hdata_len;
        int ret = 0;

        if ((mctx = EVP_MD_CTX_new()) == NULL)
                goto err;

        if (!tls1_transcript_data(s, &hdata, &hdata_len)) {
                SSLerror(s, ERR_R_INTERNAL_ERROR);
                goto err;
        }
        if (!EVP_DigestSignInit(mctx, &pctx, sigalg->md(), NULL, pkey)) {
                SSLerror(s, ERR_R_EVP_LIB);
                goto err;
        }
        if (sigalg->key_type == EVP_PKEY_GOSTR01 &&
            EVP_PKEY_CTX_ctrl(pctx, -1, EVP_PKEY_OP_SIGN,
            EVP_PKEY_CTRL_GOST_SIG_FORMAT, GOST_SIG_FORMAT_RS_LE, NULL) <= 0) {
                SSLerror(s, ERR_R_EVP_LIB);
                goto err;
        }
        if ((sigalg->flags & SIGALG_FLAG_RSA_PSS) &&
            (!EVP_PKEY_CTX_set_rsa_padding(pctx, RSA_PKCS1_PSS_PADDING) ||
            !EVP_PKEY_CTX_set_rsa_pss_saltlen(pctx, -1))) {
                SSLerror(s, ERR_R_EVP_LIB);
                goto err;
        }
        if (!EVP_DigestSignUpdate(mctx, hdata, hdata_len)) {
                SSLerror(s, ERR_R_EVP_LIB);
                goto err;
        }
        if (!EVP_DigestSignFinal(mctx, NULL, &signature_len) ||
            signature_len == 0) {
                SSLerror(s, ERR_R_EVP_LIB);
                goto err;
        }
        if ((signature = calloc(1, signature_len)) == NULL) {
                SSLerror(s, ERR_R_MALLOC_FAILURE);
                goto err;
        }
        if (!EVP_DigestSignFinal(mctx, signature, &signature_len)) {
                SSLerror(s, ERR_R_EVP_LIB);
                goto err;
        }

        if (!CBB_add_u16(cert_verify, sigalg->value))
                goto err;
        if (!CBB_add_u16_length_prefixed(cert_verify, &cbb_signature))
                goto err;
        if (!CBB_add_bytes(&cbb_signature, signature, signature_len))
                goto err;
        if (!CBB_flush(cert_verify))
                goto err;

        ret = 1;

 err:
        EVP_MD_CTX_free(mctx);
        free(signature);
        return ret;
}

static int
ssl3_send_client_verify_rsa(SSL *s, EVP_PKEY *pkey, CBB *cert_verify)
{
        CBB cbb_signature;
        RSA *rsa;
        unsigned char data[EVP_MAX_MD_SIZE];
        unsigned char *signature = NULL;
        unsigned int signature_len;
        size_t data_len;
        int ret = 0;

        if (!tls1_transcript_hash_value(s, data, sizeof(data), &data_len))
                goto err;
        if ((signature = calloc(1, EVP_PKEY_size(pkey))) == NULL)
                goto err;
        if ((rsa = EVP_PKEY_get0_RSA(pkey)) == NULL)
                goto err;
        if (RSA_sign(NID_md5_sha1, data, data_len, signature, &signature_len,
            rsa) <= 0 ) {
                SSLerror(s, ERR_R_RSA_LIB);
                goto err;
        }

        if (!CBB_add_u16_length_prefixed(cert_verify, &cbb_signature))
                goto err;
        if (!CBB_add_bytes(&cbb_signature, signature, signature_len))
                goto err;
        if (!CBB_flush(cert_verify))
                goto err;

        ret = 1;
 err:
        free(signature);
        return ret;
}

static int
ssl3_send_client_verify_ec(SSL *s, EVP_PKEY *pkey, CBB *cert_verify)
{
        CBB cbb_signature;
        EC_KEY *eckey;
        unsigned char data[EVP_MAX_MD_SIZE];
        unsigned char *signature = NULL;
        unsigned int signature_len;
        int ret = 0;

        if (!tls1_transcript_hash_value(s, data, sizeof(data), NULL))
                goto err;
        if ((signature = calloc(1, EVP_PKEY_size(pkey))) == NULL)
                goto err;
        if ((eckey = EVP_PKEY_get0_EC_KEY(pkey)) == NULL)
                goto err;
        if (!ECDSA_sign(0, &data[MD5_DIGEST_LENGTH], SHA_DIGEST_LENGTH,
            signature, &signature_len, eckey)) {
                SSLerror(s, ERR_R_ECDSA_LIB);
                goto err;
        }

        if (!CBB_add_u16_length_prefixed(cert_verify, &cbb_signature))
                goto err;
        if (!CBB_add_bytes(&cbb_signature, signature, signature_len))
                goto err;
        if (!CBB_flush(cert_verify))
                goto err;

        ret = 1;
 err:
        free(signature);
        return ret;
}

#ifndef OPENSSL_NO_GOST
static int
ssl3_send_client_verify_gost(SSL *s, EVP_PKEY *pkey, CBB *cert_verify)
{
        CBB cbb_signature;
        EVP_MD_CTX *mctx;
        EVP_PKEY_CTX *pctx;
        const EVP_MD *md;
        const unsigned char *hdata;
        unsigned char *signature = NULL;
        size_t signature_len;
        size_t hdata_len;
        int nid;
        int ret = 0;

        if ((mctx = EVP_MD_CTX_new()) == NULL)
                goto err;

        if (!tls1_transcript_data(s, &hdata, &hdata_len)) {
                SSLerror(s, ERR_R_INTERNAL_ERROR);
                goto err;
        }
        if (!EVP_PKEY_get_default_digest_nid(pkey, &nid) ||
            (md = EVP_get_digestbynid(nid)) == NULL) {
                SSLerror(s, ERR_R_EVP_LIB);
                goto err;
        }
        if (!EVP_DigestSignInit(mctx, &pctx, md, NULL, pkey)) {
                SSLerror(s, ERR_R_EVP_LIB);
                goto err;
        }
        if (EVP_PKEY_CTX_ctrl(pctx, -1, EVP_PKEY_OP_SIGN,
            EVP_PKEY_CTRL_GOST_SIG_FORMAT, GOST_SIG_FORMAT_RS_LE, NULL) <= 0) {
                SSLerror(s, ERR_R_EVP_LIB);
                goto err;
        }
        if (!EVP_DigestSignUpdate(mctx, hdata, hdata_len)) {
                SSLerror(s, ERR_R_EVP_LIB);
                goto err;
        }
        if (!EVP_DigestSignFinal(mctx, NULL, &signature_len) ||
            signature_len == 0) {
                SSLerror(s, ERR_R_EVP_LIB);
                goto err;
        }
        if ((signature = calloc(1, signature_len)) == NULL) {
                SSLerror(s, ERR_R_MALLOC_FAILURE);
                goto err;
        }
        if (!EVP_DigestSignFinal(mctx, signature, &signature_len)) {
                SSLerror(s, ERR_R_EVP_LIB);
                goto err;
        }

        if (!CBB_add_u16_length_prefixed(cert_verify, &cbb_signature))
                goto err;
        if (!CBB_add_bytes(&cbb_signature, signature, signature_len))
                goto err;
        if (!CBB_flush(cert_verify))
                goto err;

        ret = 1;
 err:
        EVP_MD_CTX_free(mctx);
        free(signature);
        return ret;
}
#endif

int
ssl3_send_client_verify(SSL *s)
{
        const struct ssl_sigalg *sigalg;
        CBB cbb, cert_verify;
        EVP_PKEY *pkey;

        memset(&cbb, 0, sizeof(cbb));

        if (s->s3->hs.state == SSL3_ST_CW_CERT_VRFY_A) {
                if (!ssl3_handshake_msg_start(s, &cbb, &cert_verify,
                    SSL3_MT_CERTIFICATE_VERIFY))
                        goto err;

                pkey = s->cert->key->privatekey;
                if ((sigalg = ssl_sigalg_select(s, pkey)) == NULL) {
                        SSLerror(s, SSL_R_SIGNATURE_ALGORITHMS_ERROR);
                        goto err;
                }
                s->s3->hs.our_sigalg = sigalg;

                /*
                 * For TLS v1.2 send signature algorithm and signature using
                 * agreed digest and cached handshake records.
                 */
                if (SSL_USE_SIGALGS(s)) {
                        if (!ssl3_send_client_verify_sigalgs(s, pkey, sigalg,
                            &cert_verify))
                                goto err;
                } else if (EVP_PKEY_id(pkey) == EVP_PKEY_RSA) {
                        if (!ssl3_send_client_verify_rsa(s, pkey, &cert_verify))
                                goto err;
                } else if (EVP_PKEY_id(pkey) == EVP_PKEY_EC) {
                        if (!ssl3_send_client_verify_ec(s, pkey, &cert_verify))
                                goto err;
#ifndef OPENSSL_NO_GOST
                } else if (EVP_PKEY_id(pkey) == NID_id_GostR3410_94 ||
                    EVP_PKEY_id(pkey) == NID_id_GostR3410_2001) {
                        if (!ssl3_send_client_verify_gost(s, pkey, &cert_verify))
                                goto err;
#endif
                } else {
                        SSLerror(s, ERR_R_INTERNAL_ERROR);
                        goto err;
                }

                tls1_transcript_free(s);

                if (!ssl3_handshake_msg_finish(s, &cbb))
                        goto err;

                s->s3->hs.state = SSL3_ST_CW_CERT_VRFY_B;
        }

        return (ssl3_handshake_write(s));

 err:
        CBB_cleanup(&cbb);

        return (-1);
}

int
ssl3_send_client_certificate(SSL *s)
{
        EVP_PKEY *pkey = NULL;
        X509 *x509 = NULL;
        CBB cbb, client_cert;
        int i;

        memset(&cbb, 0, sizeof(cbb));

        if (s->s3->hs.state == SSL3_ST_CW_CERT_A) {
                if (s->cert->key->x509 == NULL ||
                    s->cert->key->privatekey == NULL)
                        s->s3->hs.state = SSL3_ST_CW_CERT_B;
                else
                        s->s3->hs.state = SSL3_ST_CW_CERT_C;
        }

        /* We need to get a client cert */
        if (s->s3->hs.state == SSL3_ST_CW_CERT_B) {
                /*
                 * If we get an error, we need to
                 * ssl->internal->rwstate = SSL_X509_LOOKUP; return(-1);
                 * We then get retried later.
                 */
                i = ssl_do_client_cert_cb(s, &x509, &pkey);
                if (i < 0) {
                        s->internal->rwstate = SSL_X509_LOOKUP;
                        return (-1);
                }
                s->internal->rwstate = SSL_NOTHING;
                if ((i == 1) && (pkey != NULL) && (x509 != NULL)) {
                        s->s3->hs.state = SSL3_ST_CW_CERT_B;
                        if (!SSL_use_certificate(s, x509) ||
                            !SSL_use_PrivateKey(s, pkey))
                                i = 0;
                } else if (i == 1) {
                        i = 0;
                        SSLerror(s, SSL_R_BAD_DATA_RETURNED_BY_CALLBACK);
                }

                X509_free(x509);
                EVP_PKEY_free(pkey);
                if (i == 0) {
                        s->s3->hs.tls12.cert_request = 2;

                        /* There is no client certificate to verify. */
                        tls1_transcript_free(s);
                }

                /* Ok, we have a cert */
                s->s3->hs.state = SSL3_ST_CW_CERT_C;
        }

        if (s->s3->hs.state == SSL3_ST_CW_CERT_C) {
                if (!ssl3_handshake_msg_start(s, &cbb, &client_cert,
                    SSL3_MT_CERTIFICATE))
                        goto err;
                if (!ssl3_output_cert_chain(s, &client_cert,
                    (s->s3->hs.tls12.cert_request == 2) ? NULL : s->cert->key))
                        goto err;
                if (!ssl3_handshake_msg_finish(s, &cbb))
                        goto err;

                s->s3->hs.state = SSL3_ST_CW_CERT_D;
        }

        /* SSL3_ST_CW_CERT_D */
        return (ssl3_handshake_write(s));

 err:
        CBB_cleanup(&cbb);

        return (0);
}

#define has_bits(i,m)   (((i)&(m)) == (m))

int
ssl3_check_cert_and_algorithm(SSL *s)
{
        long alg_k, alg_a;
        int nid = NID_undef;
        int i;

        alg_k = s->s3->hs.cipher->algorithm_mkey;
        alg_a = s->s3->hs.cipher->algorithm_auth;

        /* We don't have a certificate. */
        if (alg_a & SSL_aNULL)
                return (1);

        if (s->s3->hs.key_share != NULL)
                nid = tls_key_share_nid(s->s3->hs.key_share);

        /* This is the passed certificate. */

        if (s->session->peer_cert_type == SSL_PKEY_ECC) {
                if (!ssl_check_srvr_ecc_cert_and_alg(s, s->session->peer_cert)) {
                        SSLerror(s, SSL_R_BAD_ECC_CERT);
                        goto fatal_err;
                }
                return (1);
        }

        i = X509_certificate_type(s->session->peer_cert, NULL);

        /* Check that we have a certificate if we require one. */
        if ((alg_a & SSL_aRSA) && !has_bits(i, EVP_PK_RSA|EVP_PKT_SIGN)) {
                SSLerror(s, SSL_R_MISSING_RSA_SIGNING_CERT);
                goto fatal_err;
        }
        if ((alg_k & SSL_kRSA) && !has_bits(i, EVP_PK_RSA|EVP_PKT_ENC)) {
                SSLerror(s, SSL_R_MISSING_RSA_ENCRYPTING_CERT);
                goto fatal_err;
        }
        if ((alg_k & SSL_kDHE) &&
            !(has_bits(i, EVP_PK_DH|EVP_PKT_EXCH) || (nid == NID_dhKeyAgreement))) {
                SSLerror(s, SSL_R_MISSING_DH_KEY);
                goto fatal_err;
        }

        return (1);

 fatal_err:
        ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);

        return (0);
}

/*
 * Check to see if handshake is full or resumed. Usually this is just a
 * case of checking to see if a cache hit has occurred. In the case of
 * session tickets we have to check the next message to be sure.
 */

int
ssl3_check_finished(SSL *s)
{
        int ret;

        /* If we have no ticket it cannot be a resumed session. */
        if (!s->session->tlsext_tick)
                return (1);
        /* this function is called when we really expect a Certificate
         * message, so permit appropriate message length */
        if ((ret = ssl3_get_message(s, SSL3_ST_CR_CERT_A,
            SSL3_ST_CR_CERT_B, -1, s->internal->max_cert_list)) <= 0)
                return ret;

        s->s3->hs.tls12.reuse_message = 1;
        if ((s->s3->hs.tls12.message_type == SSL3_MT_FINISHED) ||
            (s->s3->hs.tls12.message_type == SSL3_MT_NEWSESSION_TICKET))
                return (2);

        return (1);
}

int
ssl_do_client_cert_cb(SSL *s, X509 **px509, EVP_PKEY **ppkey)
{
        int     i = 0;

#ifndef OPENSSL_NO_ENGINE
        if (s->ctx->internal->client_cert_engine) {
                i = ENGINE_load_ssl_client_cert(
                    s->ctx->internal->client_cert_engine, s,
                    SSL_get_client_CA_list(s), px509, ppkey, NULL, NULL, NULL);
                if (i != 0)
                        return (i);
        }
#endif
        if (s->ctx->internal->client_cert_cb)
                i = s->ctx->internal->client_cert_cb(s, px509, ppkey);
        return (i);
}