root/lib/libssl/ssl_srvr.c
/* $OpenBSD: ssl_srvr.c,v 1.168 2026/04/03 12:58:19 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 <stdio.h>

#include <openssl/bn.h>
#include <openssl/buffer.h>
#include <openssl/curve25519.h>
#include <openssl/evp.h>
#include <openssl/dh.h>
#include <openssl/hmac.h>
#include <openssl/md5.h>
#include <openssl/objects.h>
#include <openssl/opensslconf.h>
#include <openssl/x509.h>

#include "bytestring.h"
#include "crypto_internal.h"
#include "dtls_local.h"
#include "ssl_local.h"
#include "ssl_sigalgs.h"
#include "ssl_tlsext.h"

static int ssl3_get_client_hello(SSL *s);
static int ssl3_send_dtls_hello_verify_request(SSL *s);
static int ssl3_send_server_hello(SSL *s);
static int ssl3_send_hello_request(SSL *s);
static int ssl3_send_server_certificate(SSL *s);
static int ssl3_send_server_key_exchange(SSL *s);
static int ssl3_send_certificate_request(SSL *s);
static int ssl3_send_server_done(SSL *s);
static int ssl3_get_client_certificate(SSL *s);
static int ssl3_get_client_key_exchange(SSL *s);
static int ssl3_get_cert_verify(SSL *s);
static int ssl3_send_newsession_ticket(SSL *s);
static int ssl3_send_cert_status(SSL *s);
static int ssl3_send_server_change_cipher_spec(SSL *s);
static int ssl3_send_server_finished(SSL *s);
static int ssl3_get_client_finished(SSL *s);

int
ssl3_accept(SSL *s)
{
        unsigned long alg_k;
        int new_state, state, skip = 0;
        int listen = 0;
        int ret = -1;

        ERR_clear_error();
        errno = 0;

        if (SSL_is_dtls(s))
                listen = s->d1->listen;

        /* init things to blank */
        s->in_handshake++;
        if (!SSL_in_init(s) || SSL_in_before(s))
                SSL_clear(s);

        if (SSL_is_dtls(s))
                s->d1->listen = listen;

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

                switch (s->s3->hs.state) {
                case SSL_ST_RENEGOTIATE:
                        s->renegotiate = 1;
                        /* s->s3->hs.state=SSL_ST_ACCEPT; */

                case SSL_ST_BEFORE:
                case SSL_ST_ACCEPT:
                case SSL_ST_BEFORE|SSL_ST_ACCEPT:
                case SSL_ST_OK|SSL_ST_ACCEPT:
                        s->server = 1;

                        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;
                        }

                        /* Ensure that we cannot negotiate TLSv1.1 or lower. */
                        if (s->s3->hs.our_min_tls_version < TLS1_2_VERSION) {
                                SSLerror(s, ERR_R_INTERNAL_ERROR);
                                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;
                        }

                        s->init_num = 0;

                        if (s->s3->hs.state != SSL_ST_RENEGOTIATE) {
                                /*
                                 * Ok, we now need to push on a buffering BIO
                                 * so that the output is sent in a way that
                                 * TCP likes :-)
                                 */
                                if (!ssl_init_wbio_buffer(s, 1)) {
                                        ret = -1;
                                        goto end;
                                }

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

                                s->s3->hs.state = SSL3_ST_SR_CLNT_HELLO_A;
                                s->ctx->stats.sess_accept++;
                        } else if (!SSL_is_dtls(s) && !s->s3->send_connection_binding) {
                                /*
                                 * Server attempting to renegotiate with
                                 * client that doesn't support secure
                                 * renegotiation.
                                 */
                                SSLerror(s, SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
                                ssl3_send_alert(s, SSL3_AL_FATAL,
                                    SSL_AD_HANDSHAKE_FAILURE);
                                ret = -1;
                                goto end;
                        } else {
                                /*
                                 * s->s3->hs.state == SSL_ST_RENEGOTIATE,
                                 * we will just send a HelloRequest.
                                 */
                                s->ctx->stats.sess_accept_renegotiate++;
                                s->s3->hs.state = SSL3_ST_SW_HELLO_REQ_A;
                        }
                        break;

                case SSL3_ST_SW_HELLO_REQ_A:
                case SSL3_ST_SW_HELLO_REQ_B:
                        s->shutdown = 0;
                        if (SSL_is_dtls(s)) {
                                dtls1_clear_record_buffer(s);
                                dtls1_start_timer(s);
                        }
                        ret = ssl3_send_hello_request(s);
                        if (ret <= 0)
                                goto end;
                        if (SSL_is_dtls(s))
                                s->s3->hs.tls12.next_state = SSL3_ST_SR_CLNT_HELLO_A;
                        else
                                s->s3->hs.tls12.next_state = SSL3_ST_SW_HELLO_REQ_C;
                        s->s3->hs.state = SSL3_ST_SW_FLUSH;
                        s->init_num = 0;

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

                case SSL3_ST_SW_HELLO_REQ_C:
                        s->s3->hs.state = SSL_ST_OK;
                        break;

                case SSL3_ST_SR_CLNT_HELLO_A:
                case SSL3_ST_SR_CLNT_HELLO_B:
                case SSL3_ST_SR_CLNT_HELLO_C:
                        s->shutdown = 0;
                        if (SSL_is_dtls(s)) {
                                ret = ssl3_get_client_hello(s);
                                if (ret <= 0)
                                        goto end;
                                dtls1_stop_timer(s);

                                if (ret == 1 &&
                                    (SSL_get_options(s) & SSL_OP_COOKIE_EXCHANGE))
                                        s->s3->hs.state = DTLS1_ST_SW_HELLO_VERIFY_REQUEST_A;
                                else
                                        s->s3->hs.state = SSL3_ST_SW_SRVR_HELLO_A;

                                s->init_num = 0;

                                /*
                                 * Reflect ClientHello sequence to remain
                                 * stateless while listening.
                                 */
                                if (listen) {
                                        tls12_record_layer_reflect_seq_num(
                                            s->rl);
                                }

                                /* If we're just listening, stop here */
                                if (listen && s->s3->hs.state == SSL3_ST_SW_SRVR_HELLO_A) {
                                        ret = 2;
                                        s->d1->listen = 0;
                                        /*
                                         * Set expected sequence numbers to
                                         * continue the handshake.
                                         */
                                        s->d1->handshake_read_seq = 2;
                                        s->d1->handshake_write_seq = 1;
                                        s->d1->next_handshake_write_seq = 1;
                                        goto end;
                                }
                        } else {
                                if (s->rwstate != SSL_X509_LOOKUP) {
                                        ret = ssl3_get_client_hello(s);
                                        if (ret <= 0)
                                                goto end;
                                }

                                s->renegotiate = 2;
                                s->s3->hs.state = SSL3_ST_SW_SRVR_HELLO_A;
                                s->init_num = 0;
                        }
                        break;

                case DTLS1_ST_SW_HELLO_VERIFY_REQUEST_A:
                case DTLS1_ST_SW_HELLO_VERIFY_REQUEST_B:
                        ret = ssl3_send_dtls_hello_verify_request(s);
                        if (ret <= 0)
                                goto end;
                        s->s3->hs.state = SSL3_ST_SW_FLUSH;
                        s->s3->hs.tls12.next_state = SSL3_ST_SR_CLNT_HELLO_A;

                        /* HelloVerifyRequest resets Finished MAC. */
                        tls1_transcript_reset(s);
                        break;

                case SSL3_ST_SW_SRVR_HELLO_A:
                case SSL3_ST_SW_SRVR_HELLO_B:
                        if (SSL_is_dtls(s)) {
                                s->renegotiate = 2;
                                dtls1_start_timer(s);
                        }
                        ret = ssl3_send_server_hello(s);
                        if (ret <= 0)
                                goto end;
                        if (s->hit) {
                                if (s->tlsext_ticket_expected)
                                        s->s3->hs.state = SSL3_ST_SW_SESSION_TICKET_A;
                                else
                                        s->s3->hs.state = SSL3_ST_SW_CHANGE_A;
                        } else {
                                s->s3->hs.state = SSL3_ST_SW_CERT_A;
                        }
                        s->init_num = 0;
                        break;

                case SSL3_ST_SW_CERT_A:
                case SSL3_ST_SW_CERT_B:
                        /* Check if it is anon DH or anon ECDH. */
                        if (!(s->s3->hs.cipher->algorithm_auth &
                            SSL_aNULL)) {
                                if (SSL_is_dtls(s))
                                        dtls1_start_timer(s);
                                ret = ssl3_send_server_certificate(s);
                                if (ret <= 0)
                                        goto end;
                                if (s->tlsext_status_expected)
                                        s->s3->hs.state = SSL3_ST_SW_CERT_STATUS_A;
                                else
                                        s->s3->hs.state = SSL3_ST_SW_KEY_EXCH_A;
                        } else {
                                skip = 1;
                                s->s3->hs.state = SSL3_ST_SW_KEY_EXCH_A;
                        }
                        s->init_num = 0;
                        break;

                case SSL3_ST_SW_KEY_EXCH_A:
                case SSL3_ST_SW_KEY_EXCH_B:
                        alg_k = s->s3->hs.cipher->algorithm_mkey;

                        /*
                         * Only send if using a DH key exchange.
                         *
                         * For ECC ciphersuites, we send a ServerKeyExchange
                         * message only if the cipher suite is ECDHE. In other
                         * cases, the server certificate contains the server's
                         * public key for key exchange.
                         */
                        if (alg_k & (SSL_kDHE|SSL_kECDHE)) {
                                if (SSL_is_dtls(s))
                                        dtls1_start_timer(s);
                                ret = ssl3_send_server_key_exchange(s);
                                if (ret <= 0)
                                        goto end;
                        } else
                                skip = 1;

                        s->s3->hs.state = SSL3_ST_SW_CERT_REQ_A;
                        s->init_num = 0;
                        break;

                case SSL3_ST_SW_CERT_REQ_A:
                case SSL3_ST_SW_CERT_REQ_B:
                        /*
                         * Determine whether or not we need to request a
                         * certificate.
                         *
                         * Do not request a certificate if:
                         *
                         * - We did not ask for it (SSL_VERIFY_PEER is unset).
                         *
                         * - SSL_VERIFY_CLIENT_ONCE is set and we are
                         *   renegotiating.
                         *
                         * - We are using an anonymous ciphersuites
                         *   (see section "Certificate request" in SSL 3 drafts
                         *   and in RFC 2246) ... except when the application
                         *   insists on verification (against the specs, but
                         *   s3_clnt.c accepts this for SSL 3).
                         */
                        if (!(s->verify_mode & SSL_VERIFY_PEER) ||
                            ((s->session->peer_cert != NULL) &&
                             (s->verify_mode & SSL_VERIFY_CLIENT_ONCE)) ||
                            ((s->s3->hs.cipher->algorithm_auth &
                             SSL_aNULL) && !(s->verify_mode &
                             SSL_VERIFY_FAIL_IF_NO_PEER_CERT))) {
                                /* No cert request. */
                                skip = 1;
                                s->s3->hs.tls12.cert_request = 0;
                                s->s3->hs.state = SSL3_ST_SW_SRVR_DONE_A;

                                if (!SSL_is_dtls(s))
                                        tls1_transcript_free(s);
                        } else {
                                s->s3->hs.tls12.cert_request = 1;
                                if (SSL_is_dtls(s))
                                        dtls1_start_timer(s);
                                ret = ssl3_send_certificate_request(s);
                                if (ret <= 0)
                                        goto end;
                                s->s3->hs.state = SSL3_ST_SW_SRVR_DONE_A;
                                s->init_num = 0;
                        }
                        break;

                case SSL3_ST_SW_SRVR_DONE_A:
                case SSL3_ST_SW_SRVR_DONE_B:
                        if (SSL_is_dtls(s))
                                dtls1_start_timer(s);
                        ret = ssl3_send_server_done(s);
                        if (ret <= 0)
                                goto end;
                        s->s3->hs.tls12.next_state = SSL3_ST_SR_CERT_A;
                        s->s3->hs.state = SSL3_ST_SW_FLUSH;
                        s->init_num = 0;
                        break;

                case SSL3_ST_SW_FLUSH:
                        /*
                         * This code originally checked to see if
                         * any data was pending using BIO_CTRL_INFO
                         * and then flushed. This caused problems
                         * as documented in PR#1939. The proposed
                         * fix doesn't completely resolve this issue
                         * as buggy implementations of BIO_CTRL_PENDING
                         * still exist. So instead we just flush
                         * unconditionally.
                         */
                        s->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->rwstate = SSL_NOTHING;
                                                s->s3->hs.state = s->s3->hs.tls12.next_state;
                                        }
                                }
                                ret = -1;
                                goto end;
                        }
                        s->rwstate = SSL_NOTHING;
                        s->s3->hs.state = s->s3->hs.tls12.next_state;
                        break;

                case SSL3_ST_SR_CERT_A:
                case SSL3_ST_SR_CERT_B:
                        if (s->s3->hs.tls12.cert_request != 0) {
                                ret = ssl3_get_client_certificate(s);
                                if (ret <= 0)
                                        goto end;
                        }
                        s->init_num = 0;
                        s->s3->hs.state = SSL3_ST_SR_KEY_EXCH_A;
                        break;

                case SSL3_ST_SR_KEY_EXCH_A:
                case SSL3_ST_SR_KEY_EXCH_B:
                        ret = ssl3_get_client_key_exchange(s);
                        if (ret <= 0)
                                goto end;

                        if (SSL_is_dtls(s)) {
                                s->s3->hs.state = SSL3_ST_SR_CERT_VRFY_A;
                                s->init_num = 0;
                        }

                        alg_k = s->s3->hs.cipher->algorithm_mkey;
                        if (SSL_USE_SIGALGS(s)) {
                                s->s3->hs.state = SSL3_ST_SR_CERT_VRFY_A;
                                s->init_num = 0;
                                if (!s->session->peer_cert)
                                        break;
                                /*
                                 * Freeze the transcript for use during client
                                 * certificate verification.
                                 */
                                tls1_transcript_freeze(s);
                        } else {
                                s->s3->hs.state = SSL3_ST_SR_CERT_VRFY_A;
                                s->init_num = 0;

                                tls1_transcript_free(s);

                                /*
                                 * We need to get hashes here so if there is
                                 * a client cert, it can be verified.
                                 */
                                if (!tls1_transcript_hash_value(s,
                                    s->s3->hs.tls12.cert_verify,
                                    sizeof(s->s3->hs.tls12.cert_verify),
                                    NULL)) {
                                        ret = -1;
                                        goto end;
                                }
                        }
                        break;

                case SSL3_ST_SR_CERT_VRFY_A:
                case SSL3_ST_SR_CERT_VRFY_B:
                        if (SSL_is_dtls(s))
                                s->d1->change_cipher_spec_ok = 1;
                        else
                                s->s3->flags |= SSL3_FLAGS_CCS_OK;

                        /* we should decide if we expected this one */
                        ret = ssl3_get_cert_verify(s);
                        if (ret <= 0)
                                goto end;
                        s->s3->hs.state = SSL3_ST_SR_FINISHED_A;
                        s->init_num = 0;
                        break;

                case SSL3_ST_SR_FINISHED_A:
                case SSL3_ST_SR_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_client_finished(s);
                        if (ret <= 0)
                                goto end;
                        if (SSL_is_dtls(s))
                                dtls1_stop_timer(s);
                        if (s->hit)
                                s->s3->hs.state = SSL_ST_OK;
                        else if (s->tlsext_ticket_expected)
                                s->s3->hs.state = SSL3_ST_SW_SESSION_TICKET_A;
                        else
                                s->s3->hs.state = SSL3_ST_SW_CHANGE_A;
                        s->init_num = 0;
                        break;

                case SSL3_ST_SW_SESSION_TICKET_A:
                case SSL3_ST_SW_SESSION_TICKET_B:
                        ret = ssl3_send_newsession_ticket(s);
                        if (ret <= 0)
                                goto end;
                        s->s3->hs.state = SSL3_ST_SW_CHANGE_A;
                        s->init_num = 0;
                        break;

                case SSL3_ST_SW_CERT_STATUS_A:
                case SSL3_ST_SW_CERT_STATUS_B:
                        ret = ssl3_send_cert_status(s);
                        if (ret <= 0)
                                goto end;
                        s->s3->hs.state = SSL3_ST_SW_KEY_EXCH_A;
                        s->init_num = 0;
                        break;

                case SSL3_ST_SW_CHANGE_A:
                case SSL3_ST_SW_CHANGE_B:
                        ret = ssl3_send_server_change_cipher_spec(s);
                        if (ret <= 0)
                                goto end;
                        s->s3->hs.state = SSL3_ST_SW_FINISHED_A;
                        s->init_num = 0;
                        s->session->cipher_value = s->s3->hs.cipher->value;

                        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_SW_FINISHED_A:
                case SSL3_ST_SW_FINISHED_B:
                        ret = ssl3_send_server_finished(s);
                        if (ret <= 0)
                                goto end;
                        s->s3->hs.state = SSL3_ST_SW_FLUSH;
                        if (s->hit) {
                                s->s3->hs.tls12.next_state = SSL3_ST_SR_FINISHED_A;
                                tls1_transcript_free(s);
                        } else
                                s->s3->hs.tls12.next_state = SSL_ST_OK;
                        s->init_num = 0;
                        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);

                        /* remove buffering on output */
                        ssl_free_wbio_buffer(s);

                        s->init_num = 0;

                        /* Skipped if we just sent a HelloRequest. */
                        if (s->renegotiate == 2) {
                                s->renegotiate = 0;
                                s->new_session = 0;

                                ssl_update_cache(s, SSL_SESS_CACHE_SERVER);

                                s->ctx->stats.sess_accept_good++;
                                /* s->server=1; */
                                s->handshake_func = ssl3_accept;

                                ssl_info_callback(s, SSL_CB_HANDSHAKE_DONE, 1);
                        }

                        ret = 1;

                        if (SSL_is_dtls(s)) {
                                /* Done handshaking, next message is client hello. */
                                s->d1->handshake_read_seq = 0;
                                /* Next message is server hello. */
                                s->d1->handshake_write_seq = 0;
                                s->d1->next_handshake_write_seq = 0;
                        }
                        goto end;
                        /* break; */

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

                if (!s->s3->hs.tls12.reuse_message && !skip) {
                        if (s->s3->hs.state != state) {
                                new_state = s->s3->hs.state;
                                s->s3->hs.state = state;
                                ssl_info_callback(s, SSL_CB_ACCEPT_LOOP, 1);
                                s->s3->hs.state = new_state;
                        }
                }
                skip = 0;
        }
 end:
        /* BIO_flush(s->wbio); */
        s->in_handshake--;
        ssl_info_callback(s, SSL_CB_ACCEPT_EXIT, ret);

        return (ret);
}

static int
ssl3_send_hello_request(SSL *s)
{
        CBB cbb, hello;

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

        if (s->s3->hs.state == SSL3_ST_SW_HELLO_REQ_A) {
                if (!ssl3_handshake_msg_start(s, &cbb, &hello,
                    SSL3_MT_HELLO_REQUEST))
                        goto err;
                if (!ssl3_handshake_msg_finish(s, &cbb))
                        goto err;

                s->s3->hs.state = SSL3_ST_SW_HELLO_REQ_B;
        }

        /* SSL3_ST_SW_HELLO_REQ_B */
        return (ssl3_handshake_write(s));

 err:
        CBB_cleanup(&cbb);

        return (-1);
}

static int
ssl3_get_client_hello(SSL *s)
{
        CBS cbs, client_random, session_id, cookie, cipher_suites;
        CBS compression_methods;
        uint16_t client_version;
        uint8_t comp_method;
        int comp_null;
        int i, j, al, ret, cookie_valid = 0;
        SSL_CIPHER *c;
        STACK_OF(SSL_CIPHER) *ciphers = NULL;
        const SSL_METHOD *method;
        uint16_t shared_version;

        /*
         * We do this so that we will respond with our native type.
         * If we are TLSv1 and we get SSLv3, we will respond with TLSv1,
         * This down switching should be handled by a different method.
         * If we are SSLv3, we will respond with SSLv3, even if prompted with
         * TLSv1.
         */
        if (s->s3->hs.state == SSL3_ST_SR_CLNT_HELLO_A)
                s->s3->hs.state = SSL3_ST_SR_CLNT_HELLO_B;

        s->first_packet = 1;
        if ((ret = ssl3_get_message(s, SSL3_ST_SR_CLNT_HELLO_B,
            SSL3_ST_SR_CLNT_HELLO_C, SSL3_MT_CLIENT_HELLO,
            SSL3_RT_MAX_PLAIN_LENGTH)) <= 0)
                return ret;
        s->first_packet = 0;

        ret = -1;

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

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

        /* Parse client hello up until the extensions (if any). */
        if (!CBS_get_u16(&cbs, &client_version))
                goto decode_err;
        if (!CBS_get_bytes(&cbs, &client_random, SSL3_RANDOM_SIZE))
                goto decode_err;
        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;
        }
        if (SSL_is_dtls(s)) {
                if (!CBS_get_u8_length_prefixed(&cbs, &cookie))
                        goto decode_err;
        }
        if (!CBS_get_u16_length_prefixed(&cbs, &cipher_suites))
                goto decode_err;
        if (!CBS_get_u8_length_prefixed(&cbs, &compression_methods))
                goto decode_err;

        /*
         * Use version from inside client hello, not from record header.
         * (may differ: see RFC 2246, Appendix E, second paragraph)
         */
        if (!ssl_max_shared_version(s, client_version, &shared_version)) {
                if ((client_version >> 8) == SSL3_VERSION_MAJOR &&
                    !tls12_record_layer_write_protected(s->rl)) {
                        /*
                         * Similar to ssl3_get_record, send alert using remote
                         * version number.
                         */
                        s->version = client_version;
                }
                SSLerror(s, SSL_R_WRONG_VERSION_NUMBER);
                al = SSL_AD_PROTOCOL_VERSION;
                goto fatal_err;
        }
        s->s3->hs.peer_legacy_version = client_version;
        s->version = shared_version;

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

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

        /*
         * If we require cookies (DTLS) and this ClientHello does not contain
         * one, just return since we do not want to allocate any memory yet.
         * So check cookie length...
         */
        if (SSL_is_dtls(s)) {
                if (SSL_get_options(s) & SSL_OP_COOKIE_EXCHANGE) {
                        if (CBS_len(&cookie) == 0)
                                return (1);
                }
        }

        if (!CBS_write_bytes(&client_random, s->s3->client_random,
            sizeof(s->s3->client_random), NULL))
                goto err;

        s->hit = 0;

        /*
         * Versions before 0.9.7 always allow clients to resume sessions in
         * renegotiation. 0.9.7 and later allow this by default, but optionally
         * ignore resumption requests with flag
         * SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION (it's a new flag
         * rather than a change to default behavior so that applications
         * relying on this for security won't even compile against older
         * library versions).
         *
         * 1.0.1 and later also have a function SSL_renegotiate_abbreviated()
         * to request renegotiation but not a new session (s->new_session
         * remains unset): for servers, this essentially just means that the
         * SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION setting will be
         * ignored.
         */
        if ((s->new_session && (s->options &
            SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION))) {
                if (!ssl_get_new_session(s, 1))
                        goto err;
        } else {
                CBS ext_block;

                CBS_dup(&cbs, &ext_block);

                i = ssl_get_prev_session(s, &session_id, &ext_block, &al);
                if (i == 1) { /* previous session */
                        s->hit = 1;
                } else if (i == -1)
                        goto fatal_err;
                else {
                        /* i == 0 */
                        if (!ssl_get_new_session(s, 1))
                                goto err;
                }
        }

        if (SSL_is_dtls(s)) {
                /*
                 * The ClientHello may contain a cookie even if the HelloVerify
                 * message has not been sent - make sure that it does not cause
                 * an overflow.
                 */
                if (CBS_len(&cookie) > sizeof(s->d1->rcvd_cookie)) {
                        al = SSL_AD_DECODE_ERROR;
                        SSLerror(s, SSL_R_COOKIE_MISMATCH);
                        goto fatal_err;
                }

                /* Verify the cookie if appropriate option is set. */
                if ((SSL_get_options(s) & SSL_OP_COOKIE_EXCHANGE) &&
                    CBS_len(&cookie) > 0) {
                        size_t cookie_len;

                        /* XXX - rcvd_cookie seems to only be used here... */
                        if (!CBS_write_bytes(&cookie, s->d1->rcvd_cookie,
                            sizeof(s->d1->rcvd_cookie), &cookie_len))
                                goto err;

                        if (s->ctx->app_verify_cookie_cb != NULL) {
                                if (s->ctx->app_verify_cookie_cb(s,
                                    s->d1->rcvd_cookie, cookie_len) == 0) {
                                        al = SSL_AD_HANDSHAKE_FAILURE;
                                        SSLerror(s, SSL_R_COOKIE_MISMATCH);
                                        goto fatal_err;
                                }
                                /* else cookie verification succeeded */
                        /* XXX - can d1->cookie_len > sizeof(rcvd_cookie) ? */
                        } else if (timingsafe_memcmp(s->d1->rcvd_cookie,
                            s->d1->cookie, s->d1->cookie_len) != 0) {
                                /* default verification */
                                al = SSL_AD_HANDSHAKE_FAILURE;
                                SSLerror(s, SSL_R_COOKIE_MISMATCH);
                                goto fatal_err;
                        }
                        cookie_valid = 1;
                }
        }

        /* XXX - This logic seems wrong... */
        if (CBS_len(&cipher_suites) == 0 && CBS_len(&session_id) != 0) {
                /* we need a cipher if we are not resuming a session */
                al = SSL_AD_ILLEGAL_PARAMETER;
                SSLerror(s, SSL_R_NO_CIPHERS_SPECIFIED);
                goto fatal_err;
        }

        if (CBS_len(&cipher_suites) > 0) {
                if ((ciphers = ssl_bytes_to_cipher_list(s,
                    &cipher_suites)) == NULL)
                        goto err;
        }

        /* If it is a hit, check that the cipher is in the list */
        /* XXX - CBS_len(&cipher_suites) will always be zero here... */
        if (s->hit && CBS_len(&cipher_suites) > 0) {
                j = 0;

                for (i = 0; i < sk_SSL_CIPHER_num(ciphers); i++) {
                        c = sk_SSL_CIPHER_value(ciphers, i);
                        if (c->value == s->session->cipher_value) {
                                j = 1;
                                break;
                        }
                }
                if (j == 0) {
                        /*
                         * We need to have the cipher in the cipher
                         * list if we are asked to reuse it
                         */
                        al = SSL_AD_ILLEGAL_PARAMETER;
                        SSLerror(s, SSL_R_REQUIRED_CIPHER_MISSING);
                        goto fatal_err;
                }
        }

        comp_null = 0;
        while (CBS_len(&compression_methods) > 0) {
                if (!CBS_get_u8(&compression_methods, &comp_method))
                        goto decode_err;
                if (comp_method == 0)
                        comp_null = 1;
        }
        if (comp_null == 0) {
                al = SSL_AD_DECODE_ERROR;
                SSLerror(s, SSL_R_NO_COMPRESSION_SPECIFIED);
                goto fatal_err;
        }

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

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

        if (!s->s3->renegotiate_seen && s->renegotiate) {
                al = SSL_AD_HANDSHAKE_FAILURE;
                SSLerror(s, SSL_R_UNSAFE_LEGACY_RENEGOTIATION_DISABLED);
                goto fatal_err;
        }

        if (ssl_check_clienthello_tlsext_early(s) <= 0) {
                SSLerror(s, SSL_R_CLIENTHELLO_TLSEXT);
                goto err;
        }

        /*
         * Check if we want to use external pre-shared secret for this
         * handshake for not reused session only. We need to generate
         * server_random before calling tls_session_secret_cb in order to allow
         * SessionTicket processing to use it in key derivation.
         */
        arc4random_buf(s->s3->server_random, SSL3_RANDOM_SIZE);

        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. If we are downgrading from TLS 1.3
                 * we must set the last 8 bytes of the server random to magical
                 * values to indicate we meant to downgrade.  For TLS 1.2 it is
                 * recommended that we do the same.
                 */
                size_t index = SSL3_RANDOM_SIZE - sizeof(tls13_downgrade_12);
                uint8_t *magic = &s->s3->server_random[index];
                if (s->s3->hs.negotiated_tls_version == TLS1_2_VERSION) {
                        /* Indicate we chose to downgrade to 1.2. */
                        memcpy(magic, tls13_downgrade_12,
                            sizeof(tls13_downgrade_12));
                } else {
                        /* Indicate we chose to downgrade to 1.1 or lower */
                        memcpy(magic, tls13_downgrade_11,
                            sizeof(tls13_downgrade_11));
                }
        }

        if (!s->hit && s->tls_session_secret_cb != NULL) {
                const SSL_CIPHER *pref_cipher = NULL;
                int master_key_length = sizeof(s->session->master_key);

                if (!s->tls_session_secret_cb(s,
                    s->session->master_key, &master_key_length, ciphers,
                    &pref_cipher, s->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;

                s->hit = 1;
                s->session->verify_result = X509_V_OK;

                sk_SSL_CIPHER_free(s->s3->hs.client_ciphers);
                s->s3->hs.client_ciphers = ciphers;
                ciphers = NULL;

                /*
                 * XXX - this allows the callback to use any client cipher and
                 * completely ignore the server cipher list. We should ensure
                 * that the pref_cipher is in both the client list and the
                 * server list.
                 */

                /* Check if some cipher was preferred by the callback. */
                if (pref_cipher == NULL)
                        pref_cipher = ssl3_choose_cipher(s, s->s3->hs.client_ciphers,
                            SSL_get_ciphers(s));
                if (pref_cipher == NULL) {
                        al = SSL_AD_HANDSHAKE_FAILURE;
                        SSLerror(s, SSL_R_NO_SHARED_CIPHER);
                        goto fatal_err;
                }
                s->s3->hs.cipher = pref_cipher;

                /* XXX - why? */
                sk_SSL_CIPHER_free(s->cipher_list);
                s->cipher_list = sk_SSL_CIPHER_dup(s->s3->hs.client_ciphers);
        }

        /*
         * Given s->session->ciphers and SSL_get_ciphers, we must
         * pick a cipher
         */

        if (!s->hit) {
                if (ciphers == NULL) {
                        al = SSL_AD_ILLEGAL_PARAMETER;
                        SSLerror(s, SSL_R_NO_CIPHERS_PASSED);
                        goto fatal_err;
                }
                sk_SSL_CIPHER_free(s->s3->hs.client_ciphers);
                s->s3->hs.client_ciphers = ciphers;
                ciphers = NULL;

                if ((c = ssl3_choose_cipher(s, s->s3->hs.client_ciphers,
                    SSL_get_ciphers(s))) == NULL) {
                        al = SSL_AD_HANDSHAKE_FAILURE;
                        SSLerror(s, SSL_R_NO_SHARED_CIPHER);
                        goto fatal_err;
                }
                s->s3->hs.cipher = c;
                s->session->cipher_value = s->s3->hs.cipher->value;
        } else {
                s->s3->hs.cipher = ssl3_get_cipher_by_value(s->session->cipher_value);
                if (s->s3->hs.cipher == NULL)
                        goto fatal_err;
        }

        if (!tls1_transcript_hash_init(s))
                goto err;

        if (!SSL_USE_SIGALGS(s) || !(s->verify_mode & SSL_VERIFY_PEER))
                tls1_transcript_free(s);

        /*
         * We now have the following setup.
         * client_random
         * cipher_list          - our preferred list of ciphers
         * ciphers              - the clients preferred list of ciphers
         * compression          - basically ignored right now
         * ssl version is set   - sslv3
         * s->session           - The ssl session has been setup.
         * s->hit               - session reuse flag
         * s->hs.cipher - the new cipher to use.
         */

        /* Handles TLS extensions that we couldn't check earlier */
        if (ssl_check_clienthello_tlsext_late(s) <= 0) {
                SSLerror(s, SSL_R_CLIENTHELLO_TLSEXT);
                goto err;
        }

        ret = cookie_valid ? 2 : 1;

        if (0) {
 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:
        sk_SSL_CIPHER_free(ciphers);

        return (ret);
}

static int
ssl3_send_dtls_hello_verify_request(SSL *s)
{
        CBB cbb, verify, cookie;

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

        if (s->s3->hs.state == DTLS1_ST_SW_HELLO_VERIFY_REQUEST_A) {
                if (s->ctx->app_gen_cookie_cb == NULL ||
                    s->ctx->app_gen_cookie_cb(s, s->d1->cookie,
                        &(s->d1->cookie_len)) == 0) {
                        SSLerror(s, ERR_R_INTERNAL_ERROR);
                        return 0;
                }

                /*
                 * Per RFC 6347 section 4.2.1, the HelloVerifyRequest should
                 * always contain DTLSv1.0 regardless of the version that is
                 * going to be negotiated.
                 */
                if (!ssl3_handshake_msg_start(s, &cbb, &verify,
                    DTLS1_MT_HELLO_VERIFY_REQUEST))
                        goto err;
                if (!CBB_add_u16(&verify, DTLS1_VERSION))
                        goto err;
                if (!CBB_add_u8_length_prefixed(&verify, &cookie))
                        goto err;
                if (!CBB_add_bytes(&cookie, s->d1->cookie, s->d1->cookie_len))
                        goto err;
                if (!ssl3_handshake_msg_finish(s, &cbb))
                        goto err;

                s->s3->hs.state = DTLS1_ST_SW_HELLO_VERIFY_REQUEST_B;
        }

        /* s->s3->hs.state = DTLS1_ST_SW_HELLO_VERIFY_REQUEST_B */
        return (ssl3_handshake_write(s));

 err:
        CBB_cleanup(&cbb);

        return (-1);
}

static int
ssl3_send_server_hello(SSL *s)
{
        CBB cbb, server_hello, session_id;
        size_t sl;

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

        if (s->s3->hs.state == SSL3_ST_SW_SRVR_HELLO_A) {
                if (!ssl3_handshake_msg_start(s, &cbb, &server_hello,
                    SSL3_MT_SERVER_HELLO))
                        goto err;

                if (!CBB_add_u16(&server_hello, s->version))
                        goto err;
                if (!CBB_add_bytes(&server_hello, s->s3->server_random,
                    sizeof(s->s3->server_random)))
                        goto err;

                /*
                 * There are several cases for the session ID to send
                 * back in the server hello:
                 *
                 * - For session reuse from the session cache,
                 *   we send back the old session ID.
                 * - If stateless session reuse (using a session ticket)
                 *   is successful, we send back the client's "session ID"
                 *   (which doesn't actually identify the session).
                 * - If it is a new session, we send back the new
                 *   session ID.
                 * - However, if we want the new session to be single-use,
                 *   we send back a 0-length session ID.
                 *
                 * s->hit is non-zero in either case of session reuse,
                 * so the following won't overwrite an ID that we're supposed
                 * to send back.
                 */
                if (!(s->ctx->session_cache_mode & SSL_SESS_CACHE_SERVER)
                    && !s->hit)
                        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_u8_length_prefixed(&server_hello, &session_id))
                        goto err;
                if (!CBB_add_bytes(&session_id, s->session->session_id, sl))
                        goto err;

                /* Cipher suite. */
                if (!CBB_add_u16(&server_hello, s->s3->hs.cipher->value))
                        goto err;

                /* Compression method (null). */
                if (!CBB_add_u8(&server_hello, 0))
                        goto err;

                /* TLS extensions */
                if (!tlsext_server_build(s, SSL_TLSEXT_MSG_SH, &server_hello)) {
                        SSLerror(s, ERR_R_INTERNAL_ERROR);
                        goto err;
                }

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

        /* SSL3_ST_SW_SRVR_HELLO_B */
        return (ssl3_handshake_write(s));

 err:
        CBB_cleanup(&cbb);

        return (-1);
}

static int
ssl3_send_server_done(SSL *s)
{
        CBB cbb, done;

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

        if (s->s3->hs.state == SSL3_ST_SW_SRVR_DONE_A) {
                if (!ssl3_handshake_msg_start(s, &cbb, &done,
                    SSL3_MT_SERVER_DONE))
                        goto err;
                if (!ssl3_handshake_msg_finish(s, &cbb))
                        goto err;

                s->s3->hs.state = SSL3_ST_SW_SRVR_DONE_B;
        }

        /* SSL3_ST_SW_SRVR_DONE_B */
        return (ssl3_handshake_write(s));

 err:
        CBB_cleanup(&cbb);

        return (-1);
}

static int
ssl3_send_server_kex_dhe(SSL *s, CBB *cbb)
{
        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 (s->cert->dhe_params_auto != 0) {
                size_t key_bits;

                if ((key_bits = ssl_dhe_params_auto_key_bits(s)) == 0) {
                        SSLerror(s, ERR_R_INTERNAL_ERROR);
                        ssl3_send_alert(s, SSL3_AL_FATAL,
                            SSL_AD_INTERNAL_ERROR);
                        goto err;
                }
                tls_key_share_set_key_bits(s->s3->hs.key_share,
                    key_bits);
        } else {
                DH *dh_params = s->cert->dhe_params;

                if (dh_params == NULL && s->cert->dhe_params_cb != NULL)
                        dh_params = s->cert->dhe_params_cb(s, 0,
                            SSL_C_PKEYLENGTH(s->s3->hs.cipher));

                if (dh_params == NULL) {
                        SSLerror(s, SSL_R_MISSING_TMP_DH_KEY);
                        ssl3_send_alert(s, SSL3_AL_FATAL,
                            SSL_AD_HANDSHAKE_FAILURE);
                        goto err;
                }

                if (!tls_key_share_set_dh_params(s->s3->hs.key_share, dh_params))
                        goto err;
        }

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

        if (!tls_key_share_params(s->s3->hs.key_share, cbb))
                goto err;
        if (!tls_key_share_public(s->s3->hs.key_share, cbb))
                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_send_server_kex_ecdhe(SSL *s, CBB *cbb)
{
        CBB public;
        int nid;

        if (!tls1_get_supported_group(s, &nid)) {
                SSLerror(s, SSL_R_UNSUPPORTED_ELLIPTIC_CURVE);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
                goto err;
        }

        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_server_generate(s->s3->hs.key_share))
                goto err;

        /*
         * ECC key exchange - see RFC 8422, section 5.4.
         */
        if (!CBB_add_u8(cbb, NAMED_CURVE_TYPE))
                goto err;
        if (!CBB_add_u16(cbb, tls_key_share_group(s->s3->hs.key_share)))
                goto err;
        if (!CBB_add_u8_length_prefixed(cbb, &public))
                goto err;
        if (!tls_key_share_public(s->s3->hs.key_share, &public))
                goto err;
        if (!CBB_flush(cbb))
                goto err;

        return 1;

 err:
        return 0;
}

static int
ssl3_send_server_key_exchange(SSL *s)
{
        CBB cbb, cbb_signature, cbb_signed_params, server_kex;
        CBS params;
        const struct ssl_sigalg *sigalg = NULL;
        unsigned char *signed_params = NULL;
        size_t signed_params_len;
        unsigned char *signature = NULL;
        size_t signature_len = 0;
        const EVP_MD *md = NULL;
        unsigned long type;
        EVP_MD_CTX *md_ctx = NULL;
        EVP_PKEY_CTX *pctx;
        EVP_PKEY *pkey;
        int al;

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

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

        if (s->s3->hs.state == SSL3_ST_SW_KEY_EXCH_A) {

                if (!ssl3_handshake_msg_start(s, &cbb, &server_kex,
                    SSL3_MT_SERVER_KEY_EXCHANGE))
                        goto err;

                if (!CBB_init(&cbb_signed_params, 0))
                        goto err;

                if (!CBB_add_bytes(&cbb_signed_params, s->s3->client_random,
                    SSL3_RANDOM_SIZE)) {
                        SSLerror(s, ERR_R_INTERNAL_ERROR);
                        goto err;
                }
                if (!CBB_add_bytes(&cbb_signed_params, s->s3->server_random,
                    SSL3_RANDOM_SIZE)) {
                        SSLerror(s, ERR_R_INTERNAL_ERROR);
                        goto err;
                }

                type = s->s3->hs.cipher->algorithm_mkey;
                if (type & SSL_kDHE) {
                        if (!ssl3_send_server_kex_dhe(s, &cbb_signed_params))
                                goto err;
                } else if (type & SSL_kECDHE) {
                        if (!ssl3_send_server_kex_ecdhe(s, &cbb_signed_params))
                                goto err;
                } else {
                        al = SSL_AD_HANDSHAKE_FAILURE;
                        SSLerror(s, SSL_R_UNKNOWN_KEY_EXCHANGE_TYPE);
                        goto fatal_err;
                }

                if (!CBB_finish(&cbb_signed_params, &signed_params,
                    &signed_params_len))
                        goto err;

                CBS_init(&params, signed_params, signed_params_len);
                if (!CBS_skip(&params, 2 * SSL3_RANDOM_SIZE))
                        goto err;

                if (!CBB_add_bytes(&server_kex, CBS_data(&params),
                    CBS_len(&params)))
                        goto err;

                /* Add signature unless anonymous. */
                if (!(s->s3->hs.cipher->algorithm_auth & SSL_aNULL)) {
                        if ((pkey = ssl_get_sign_pkey(s, s->s3->hs.cipher,
                            &md, &sigalg)) == NULL) {
                                al = SSL_AD_DECODE_ERROR;
                                goto fatal_err;
                        }
                        s->s3->hs.our_sigalg = sigalg;

                        /* Send signature algorithm. */
                        if (SSL_USE_SIGALGS(s)) {
                                if (!CBB_add_u16(&server_kex, sigalg->value)) {
                                        al = SSL_AD_INTERNAL_ERROR;
                                        SSLerror(s, ERR_R_INTERNAL_ERROR);
                                        goto fatal_err;
                                }
                        }

                        if (!EVP_DigestSignInit(md_ctx, &pctx, md, NULL, pkey)) {
                                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_DigestSign(md_ctx, NULL, &signature_len,
                            signed_params, signed_params_len)) {
                                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_DigestSign(md_ctx, signature, &signature_len,
                            signed_params, signed_params_len)) {
                                SSLerror(s, ERR_R_EVP_LIB);
                                goto err;
                        }

                        if (!CBB_add_u16_length_prefixed(&server_kex,
                            &cbb_signature))
                                goto err;
                        if (!CBB_add_bytes(&cbb_signature, signature,
                            signature_len))
                                goto err;
                }

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

                s->s3->hs.state = SSL3_ST_SW_KEY_EXCH_B;
        }

        EVP_MD_CTX_free(md_ctx);
        free(signature);
        free(signed_params);

        return (ssl3_handshake_write(s));

 fatal_err:
        ssl3_send_alert(s, SSL3_AL_FATAL, al);
 err:
        CBB_cleanup(&cbb_signed_params);
        CBB_cleanup(&cbb);
        EVP_MD_CTX_free(md_ctx);
        free(signature);
        free(signed_params);

        return (-1);
}

static int
ssl3_send_certificate_request(SSL *s)
{
        CBB cbb, cert_request, cert_types, sigalgs, cert_auth, dn;
        STACK_OF(X509_NAME) *sk = NULL;
        X509_NAME *name;
        int i;

        /*
         * Certificate Request - RFC 5246 section 7.4.4.
         */

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

        if (s->s3->hs.state == SSL3_ST_SW_CERT_REQ_A) {
                if (!ssl3_handshake_msg_start(s, &cbb, &cert_request,
                    SSL3_MT_CERTIFICATE_REQUEST))
                        goto err;

                if (!CBB_add_u8_length_prefixed(&cert_request, &cert_types))
                        goto err;
                if (!ssl3_get_req_cert_types(s, &cert_types))
                        goto err;

                if (SSL_USE_SIGALGS(s)) {
                        if (!CBB_add_u16_length_prefixed(&cert_request,
                            &sigalgs))
                                goto err;
                        if (!ssl_sigalgs_build(s->s3->hs.negotiated_tls_version,
                            &sigalgs, SSL_get_security_level(s)))
                                goto err;
                }

                if (!CBB_add_u16_length_prefixed(&cert_request, &cert_auth))
                        goto err;

                sk = SSL_get_client_CA_list(s);
                for (i = 0; i < sk_X509_NAME_num(sk); i++) {
                        unsigned char *name_data;
                        size_t name_len;

                        name = sk_X509_NAME_value(sk, i);
                        name_len = i2d_X509_NAME(name, NULL);

                        if (!CBB_add_u16_length_prefixed(&cert_auth, &dn))
                                goto err;
                        if (!CBB_add_space(&dn, &name_data, name_len))
                                goto err;
                        if (i2d_X509_NAME(name, &name_data) != name_len)
                                goto err;
                }

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

                s->s3->hs.state = SSL3_ST_SW_CERT_REQ_B;
        }

        /* SSL3_ST_SW_CERT_REQ_B */
        return (ssl3_handshake_write(s));

 err:
        CBB_cleanup(&cbb);

        return (-1);
}

static int
ssl3_get_client_kex_rsa(SSL *s, CBS *cbs)
{
        uint8_t fakepms[SSL_MAX_MASTER_KEY_LENGTH];
        uint8_t *pms = NULL;
        size_t pms_len = 0;
        size_t pad_len;
        EVP_PKEY *pkey = NULL;
        RSA *rsa = NULL;
        CBS enc_pms;
        int decrypt_len;
        uint8_t mask;
        size_t i;
        int valid = 1;
        int ret = 0;

        /*
         * Handle key exchange in the form of an RSA-Encrypted Premaster Secret
         * Message. See RFC 5246, section 7.4.7.1.
         */

        arc4random_buf(fakepms, sizeof(fakepms));

        fakepms[0] = s->s3->hs.peer_legacy_version >> 8;
        fakepms[1] = s->s3->hs.peer_legacy_version & 0xff;

        pkey = s->cert->pkeys[SSL_PKEY_RSA].privatekey;
        if (pkey == NULL || (rsa = EVP_PKEY_get0_RSA(pkey)) == NULL) {
                SSLerror(s, SSL_R_MISSING_RSA_CERTIFICATE);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
                goto err;
        }

        /*
         * The minimum size of an encrypted premaster secret is 11 bytes of
         * padding (00 02 <8 or more non-zero bytes> 00) (RFC 8017, section
         * 9.2) and 48 bytes of premaster secret (RFC 5246, section 7.4.7.1).
         * This means an RSA key size of at least 472 bits.
         */
        pms_len = RSA_size(rsa);
        if (pms_len < 11 + SSL_MAX_MASTER_KEY_LENGTH) {
                SSLerror(s, SSL_R_DECRYPTION_FAILED);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
                goto err;
        }
        pad_len = pms_len - SSL_MAX_MASTER_KEY_LENGTH;

        if (!CBS_get_u16_length_prefixed(cbs, &enc_pms)) {
                SSLerror(s, SSL_R_BAD_PACKET_LENGTH);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
                goto err;
        }
        if (CBS_len(&enc_pms) != pms_len || CBS_len(cbs) != 0) {
                SSLerror(s, SSL_R_TLS_RSA_ENCRYPTED_VALUE_LENGTH_IS_WRONG);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
                goto err;
        }

        if ((pms = calloc(1, pms_len)) == NULL)
                goto err;

        decrypt_len = RSA_private_decrypt(CBS_len(&enc_pms), CBS_data(&enc_pms),
            pms, rsa, RSA_NO_PADDING);

        if (decrypt_len != pms_len) {
                SSLerror(s, SSL_R_DECRYPTION_FAILED);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
                goto err;
        }

        /*
         * All processing from here on needs to avoid leaking any information
         * about the decrypted content, in order to prevent oracle attacks and
         * minimise timing attacks.
         */

        /* Check padding - 00 02 <8 or more non-zero bytes> 00 */
        valid &= crypto_ct_eq_u8(pms[0], 0x00);
        valid &= crypto_ct_eq_u8(pms[1], 0x02);
        for (i = 2; i < pad_len - 1; i++)
                valid &= crypto_ct_ne_u8(pms[i], 0x00);
        valid &= crypto_ct_eq_u8(pms[pad_len - 1], 0x00);

        /* Ensure client version in premaster secret matches ClientHello version. */
        valid &= crypto_ct_eq_u8(pms[pad_len + 0], s->s3->hs.peer_legacy_version >> 8);
        valid &= crypto_ct_eq_u8(pms[pad_len + 1], s->s3->hs.peer_legacy_version & 0xff);

        /* Use the premaster secret if padding is correct, if not use the fake. */
        mask = crypto_ct_eq_mask_u8(valid, 1);
        for (i = 0; i < SSL_MAX_MASTER_KEY_LENGTH; i++)
                pms[i] = (pms[pad_len + i] & mask) | (fakepms[i] & ~mask);

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

        ret = 1;

 err:
        freezero(pms, pms_len);

        return ret;
}

static int
ssl3_get_client_kex_dhe(SSL *s, CBS *cbs)
{
        uint8_t *key = NULL;
        size_t key_len = 0;
        int decode_error, invalid_key;
        int ret = 0;

        if (s->s3->hs.key_share == NULL) {
                SSLerror(s, SSL_R_MISSING_TMP_DH_KEY);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
                goto err;
        }

        if (!tls_key_share_server_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_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_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_get_client_kex_ecdhe(SSL *s, CBS *cbs)
{
        uint8_t *key = NULL;
        size_t key_len = 0;
        int decode_error;
        CBS public;
        int ret = 0;

        if (s->s3->hs.key_share == NULL) {
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_HANDSHAKE_FAILURE);
                SSLerror(s, SSL_R_MISSING_TMP_DH_KEY);
                goto err;
        }

        if (!CBS_get_u8_length_prefixed(cbs, &public)) {
                SSLerror(s, SSL_R_BAD_PACKET_LENGTH);
                ssl3_send_alert(s, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
                goto err;
        }
        if (!tls_key_share_server_peer_public(s->s3->hs.key_share, &public,
            &decode_error, NULL)) {
                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_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_get_client_key_exchange(SSL *s)
{
        unsigned long alg_k;
        int al, ret;
        CBS cbs;

        /* 2048 maxlen is a guess.  How long a key does that permit? */
        if ((ret = ssl3_get_message(s, SSL3_ST_SR_KEY_EXCH_A,
            SSL3_ST_SR_KEY_EXCH_B, SSL3_MT_CLIENT_KEY_EXCHANGE, 2048)) <= 0)
                return ret;

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

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

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

        if (alg_k & SSL_kRSA) {
                if (!ssl3_get_client_kex_rsa(s, &cbs))
                        goto err;
        } else if (alg_k & SSL_kDHE) {
                if (!ssl3_get_client_kex_dhe(s, &cbs))
                        goto err;
        } else if (alg_k & SSL_kECDHE) {
                if (!ssl3_get_client_kex_ecdhe(s, &cbs))
                        goto err;
        } else {
                al = SSL_AD_HANDSHAKE_FAILURE;
                SSLerror(s, SSL_R_UNKNOWN_CIPHER_TYPE);
                goto fatal_err;
        }

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

        return (1);

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

static int
ssl3_get_cert_verify(SSL *s)
{
        CBS cbs, signature;
        const struct ssl_sigalg *sigalg = NULL;
        uint16_t sigalg_value = SIGALG_NONE;
        EVP_PKEY *pkey;
        X509 *peer_cert = NULL;
        EVP_MD_CTX *mctx = NULL;
        int al, verify;
        const unsigned char *hdata;
        size_t hdatalen;
        int type = 0;
        int ret;

        if ((ret = ssl3_get_message(s, SSL3_ST_SR_CERT_VRFY_A,
            SSL3_ST_SR_CERT_VRFY_B, -1, SSL3_RT_MAX_PLAIN_LENGTH)) <= 0)
                return ret;

        ret = 0;

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

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

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

        peer_cert = s->session->peer_cert;
        pkey = X509_get0_pubkey(peer_cert);
        type = X509_certificate_type(peer_cert, pkey);

        if (s->s3->hs.tls12.message_type != SSL3_MT_CERTIFICATE_VERIFY) {
                s->s3->hs.tls12.reuse_message = 1;
                if (peer_cert != NULL) {
                        al = SSL_AD_UNEXPECTED_MESSAGE;
                        SSLerror(s, SSL_R_MISSING_VERIFY_MESSAGE);
                        goto fatal_err;
                }
                ret = 1;
                goto end;
        }

        if (peer_cert == NULL) {
                SSLerror(s, SSL_R_NO_CLIENT_CERT_RECEIVED);
                al = SSL_AD_UNEXPECTED_MESSAGE;
                goto fatal_err;
        }

        if (!(type & EVP_PKT_SIGN)) {
                SSLerror(s, SSL_R_SIGNATURE_FOR_NON_SIGNING_CERTIFICATE);
                al = SSL_AD_ILLEGAL_PARAMETER;
                goto fatal_err;
        }

        if (s->s3->change_cipher_spec) {
                SSLerror(s, SSL_R_CCS_RECEIVED_EARLY);
                al = SSL_AD_UNEXPECTED_MESSAGE;
                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 err;
        if (CBS_len(&cbs) != 0) {
                al = SSL_AD_DECODE_ERROR;
                SSLerror(s, SSL_R_EXTRA_DATA_IN_MESSAGE);
                goto fatal_err;
        }

        if (CBS_len(&signature) > EVP_PKEY_size(pkey)) {
                SSLerror(s, SSL_R_WRONG_SIGNATURE_SIZE);
                al = SSL_AD_DECODE_ERROR;
                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 (SSL_USE_SIGALGS(s)) {
                EVP_PKEY_CTX *pctx;

                if (!tls1_transcript_data(s, &hdata, &hdatalen)) {
                        SSLerror(s, ERR_R_INTERNAL_ERROR);
                        al = SSL_AD_INTERNAL_ERROR;
                        goto fatal_err;
                }
                if (!EVP_DigestVerifyInit(mctx, &pctx, sigalg->md(),
                    NULL, pkey)) {
                        SSLerror(s, ERR_R_EVP_LIB);
                        al = SSL_AD_INTERNAL_ERROR;
                        goto fatal_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))) {
                        al = SSL_AD_INTERNAL_ERROR;
                        goto fatal_err;
                }
                if (EVP_DigestVerify(mctx, CBS_data(&signature),
                    CBS_len(&signature), hdata, hdatalen) <= 0) {
                        SSLerror(s, ERR_R_EVP_LIB);
                        al = SSL_AD_INTERNAL_ERROR;
                        goto fatal_err;
                }
        } else if (EVP_PKEY_id(pkey) == EVP_PKEY_RSA) {
                RSA *rsa;

                if ((rsa = EVP_PKEY_get0_RSA(pkey)) == NULL) {
                        al = SSL_AD_INTERNAL_ERROR;
                        SSLerror(s, ERR_R_EVP_LIB);
                        goto fatal_err;
                }
                verify = RSA_verify(NID_md5_sha1, s->s3->hs.tls12.cert_verify,
                    MD5_DIGEST_LENGTH + SHA_DIGEST_LENGTH, CBS_data(&signature),
                    CBS_len(&signature), rsa);
                if (verify < 0) {
                        al = SSL_AD_DECRYPT_ERROR;
                        SSLerror(s, SSL_R_BAD_RSA_DECRYPT);
                        goto fatal_err;
                }
                if (verify == 0) {
                        al = SSL_AD_DECRYPT_ERROR;
                        SSLerror(s, SSL_R_BAD_RSA_SIGNATURE);
                        goto fatal_err;
                }
        } else if (EVP_PKEY_id(pkey) == EVP_PKEY_EC) {
                EC_KEY *eckey;

                if ((eckey = EVP_PKEY_get0_EC_KEY(pkey)) == NULL) {
                        al = SSL_AD_INTERNAL_ERROR;
                        SSLerror(s, ERR_R_EVP_LIB);
                        goto fatal_err;
                }
                verify = ECDSA_verify(0,
                    &(s->s3->hs.tls12.cert_verify[MD5_DIGEST_LENGTH]),
                    SHA_DIGEST_LENGTH, CBS_data(&signature),
                    CBS_len(&signature), eckey);
                if (verify <= 0) {
                        al = SSL_AD_DECRYPT_ERROR;
                        SSLerror(s, SSL_R_BAD_ECDSA_SIGNATURE);
                        goto fatal_err;
                }
        } else {
                SSLerror(s, ERR_R_INTERNAL_ERROR);
                al = SSL_AD_UNSUPPORTED_CERTIFICATE;
                goto fatal_err;
        }

        ret = 1;
        if (0) {
 decode_err:
                al = SSL_AD_DECODE_ERROR;
                SSLerror(s, SSL_R_BAD_PACKET_LENGTH);
 fatal_err:
                ssl3_send_alert(s, SSL3_AL_FATAL, al);
        }
 end:
        tls1_transcript_free(s);
 err:
        EVP_MD_CTX_free(mctx);

        return (ret);
}

static int
ssl3_get_client_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_SR_CERT_A, SSL3_ST_SR_CERT_B,
            -1, s->max_cert_list)) <= 0)
                return ret;

        ret = -1;

        if (s->s3->hs.tls12.message_type == SSL3_MT_CLIENT_KEY_EXCHANGE) {
                if ((s->verify_mode & SSL_VERIFY_PEER) &&
                    (s->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT)) {
                        SSLerror(s, SSL_R_PEER_DID_NOT_RETURN_A_CERTIFICATE);
                        al = SSL_AD_HANDSHAKE_FAILURE;
                        goto fatal_err;
                }

                /*
                 * If we asked for a client certificate and the client has none,
                 * it must respond with a certificate list of length zero.
                 */
                if (s->s3->hs.tls12.cert_request != 0) {
                        SSLerror(s, SSL_R_TLS_PEER_DID_NOT_RESPOND_WITH_CERTIFICATE_LIST);
                        al = SSL_AD_UNEXPECTED_MESSAGE;
                        goto fatal_err;
                }
                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_WRONG_MESSAGE_TYPE);
                goto fatal_err;
        }

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

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

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

        /*
         * A TLS client must send an empty certificate list, if no suitable
         * certificate is available (rather than omitting the Certificate
         * handshake message) - see RFC 5246 section 7.4.6.
         */
        if (CBS_len(&cert_list) == 0) {
                if ((s->verify_mode & SSL_VERIFY_PEER) &&
                    (s->verify_mode & SSL_VERIFY_FAIL_IF_NO_PEER_CERT)) {
                        SSLerror(s, SSL_R_PEER_DID_NOT_RETURN_A_CERTIFICATE);
                        al = SSL_AD_HANDSHAKE_FAILURE;
                        goto fatal_err;
                }
                /* No client certificate so free transcript. */
                tls1_transcript_free(s);
                goto done;
        }

        if ((certs = sk_X509_new_null()) == NULL) {
                SSLerror(s, ERR_R_MALLOC_FAILURE);
                goto 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) {
                        SSLerror(s, ERR_R_ASN1_LIB);
                        goto 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;
        }

        if (ssl_verify_cert_chain(s, certs) <= 0) {
                al = ssl_verify_alarm_type(s->verify_result);
                SSLerror(s, SSL_R_NO_CERTIFICATE_RETURNED);
                goto fatal_err;
        }
        s->session->verify_result = s->verify_result;
        ERR_clear_error();

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

 done:
        ret = 1;
        if (0) {
 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:
        sk_X509_pop_free(certs, X509_free);
        X509_free(cert);

        return (ret);
}

static int
ssl3_send_server_certificate(SSL *s)
{
        CBB cbb, server_cert;
        SSL_CERT_PKEY *cpk;

        /*
         * Server Certificate - RFC 5246, section 7.4.2.
         */

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

        if (s->s3->hs.state == SSL3_ST_SW_CERT_A) {
                if ((cpk = ssl_get_server_send_pkey(s)) == NULL) {
                        SSLerror(s, ERR_R_INTERNAL_ERROR);
                        return (0);
                }

                if (!ssl3_handshake_msg_start(s, &cbb, &server_cert,
                    SSL3_MT_CERTIFICATE))
                        goto err;
                if (!ssl3_output_cert_chain(s, &server_cert, cpk))
                        goto err;
                if (!ssl3_handshake_msg_finish(s, &cbb))
                        goto err;

                s->s3->hs.state = SSL3_ST_SW_CERT_B;
        }

        /* SSL3_ST_SW_CERT_B */
        return (ssl3_handshake_write(s));

 err:
        CBB_cleanup(&cbb);

        return (0);
}

/* send a new session ticket (not necessarily for a new session) */
static int
ssl3_send_newsession_ticket(SSL *s)
{
        CBB cbb, session_ticket, ticket;
        SSL_CTX *tctx = s->initial_ctx;
        size_t enc_session_len, enc_session_max_len, hmac_len;
        size_t session_len = 0;
        unsigned char *enc_session = NULL, *session = NULL;
        unsigned char iv[EVP_MAX_IV_LENGTH];
        unsigned char key_name[16];
        unsigned char *hmac;
        unsigned int hlen;
        EVP_CIPHER_CTX *ctx = NULL;
        HMAC_CTX *hctx = NULL;
        int iv_len, len;

        /*
         * New Session Ticket - RFC 5077, section 3.3.
         */

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

        if ((ctx = EVP_CIPHER_CTX_new()) == NULL)
                goto err;
        if ((hctx = HMAC_CTX_new()) == NULL)
                goto err;

        if (s->s3->hs.state == SSL3_ST_SW_SESSION_TICKET_A) {
                if (!ssl3_handshake_msg_start(s, &cbb, &session_ticket,
                    SSL3_MT_NEWSESSION_TICKET))
                        goto err;

                if (!SSL_SESSION_ticket(s->session, &session, &session_len))
                        goto err;
                if (session_len > 0xffff)
                        goto err;

                /*
                 * Initialize HMAC and cipher contexts. If callback is present
                 * it does all the work, otherwise use generated values from
                 * parent context.
                 */
                if (tctx->tlsext_ticket_key_cb != NULL) {
                        if (tctx->tlsext_ticket_key_cb(s,
                            key_name, iv, ctx, hctx, 1) < 0)
                                goto err;
                } else {
                        arc4random_buf(iv, 16);
                        EVP_EncryptInit_ex(ctx, EVP_aes_128_cbc(), NULL,
                            tctx->tlsext_tick_aes_key, iv);
                        HMAC_Init_ex(hctx, tctx->tlsext_tick_hmac_key,
                            16, EVP_sha256(), NULL);
                        memcpy(key_name, tctx->tlsext_tick_key_name, 16);
                }

                /* Encrypt the session state. */
                enc_session_max_len = session_len + EVP_MAX_BLOCK_LENGTH;
                if ((enc_session = calloc(1, enc_session_max_len)) == NULL)
                        goto err;
                enc_session_len = 0;
                if (!EVP_EncryptUpdate(ctx, enc_session, &len, session,
                    session_len))
                        goto err;
                enc_session_len += len;
                if (!EVP_EncryptFinal_ex(ctx, enc_session + enc_session_len,
                    &len))
                        goto err;
                enc_session_len += len;

                if (enc_session_len > enc_session_max_len)
                        goto err;

                /* Generate the HMAC. */
                if (!HMAC_Update(hctx, key_name, sizeof(key_name)))
                        goto err;
                if (!HMAC_Update(hctx, iv, EVP_CIPHER_CTX_iv_length(ctx)))
                        goto err;
                if (!HMAC_Update(hctx, enc_session, enc_session_len))
                        goto err;

                if ((hmac_len = HMAC_size(hctx)) <= 0)
                        goto err;

                /*
                 * Ticket lifetime hint (advisory only):
                 * We leave this unspecified for resumed session
                 * (for simplicity), and guess that tickets for new
                 * sessions will live as long as their sessions.
                 */
                if (!CBB_add_u32(&session_ticket,
                    s->hit ? 0 : s->session->timeout))
                        goto err;

                if (!CBB_add_u16_length_prefixed(&session_ticket, &ticket))
                        goto err;
                if (!CBB_add_bytes(&ticket, key_name, sizeof(key_name)))
                        goto err;
                if ((iv_len = EVP_CIPHER_CTX_iv_length(ctx)) < 0)
                        goto err;
                if (!CBB_add_bytes(&ticket, iv, iv_len))
                        goto err;
                if (!CBB_add_bytes(&ticket, enc_session, enc_session_len))
                        goto err;
                if (!CBB_add_space(&ticket, &hmac, hmac_len))
                        goto err;

                if (!HMAC_Final(hctx, hmac, &hlen))
                        goto err;
                if (hlen != hmac_len)
                        goto err;

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

                s->s3->hs.state = SSL3_ST_SW_SESSION_TICKET_B;
        }

        EVP_CIPHER_CTX_free(ctx);
        HMAC_CTX_free(hctx);
        freezero(session, session_len);
        free(enc_session);

        /* SSL3_ST_SW_SESSION_TICKET_B */
        return (ssl3_handshake_write(s));

 err:
        CBB_cleanup(&cbb);
        EVP_CIPHER_CTX_free(ctx);
        HMAC_CTX_free(hctx);
        freezero(session, session_len);
        free(enc_session);

        return (-1);
}

static int
ssl3_send_cert_status(SSL *s)
{
        CBB cbb, certstatus, ocspresp;

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

        if (s->s3->hs.state == SSL3_ST_SW_CERT_STATUS_A) {
                if (!ssl3_handshake_msg_start(s, &cbb, &certstatus,
                    SSL3_MT_CERTIFICATE_STATUS))
                        goto err;
                if (!CBB_add_u8(&certstatus, s->tlsext_status_type))
                        goto err;
                if (!CBB_add_u24_length_prefixed(&certstatus, &ocspresp))
                        goto err;
                if (!CBB_add_bytes(&ocspresp, s->tlsext_ocsp_resp,
                    s->tlsext_ocsp_resp_len))
                        goto err;
                if (!ssl3_handshake_msg_finish(s, &cbb))
                        goto err;

                s->s3->hs.state = SSL3_ST_SW_CERT_STATUS_B;
        }

        /* SSL3_ST_SW_CERT_STATUS_B */
        return (ssl3_handshake_write(s));

 err:
        CBB_cleanup(&cbb);

        return (-1);
}

static int
ssl3_send_server_change_cipher_spec(SSL *s)
{
        size_t outlen;
        CBB cbb;

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

        if (s->s3->hs.state == SSL3_ST_SW_CHANGE_A) {
                if (!CBB_init_fixed(&cbb, s->init_buf->data,
                    s->init_buf->length))
                        goto err;
                if (!CBB_add_u8(&cbb, SSL3_MT_CCS))
                        goto err;
                if (!CBB_finish(&cbb, NULL, &outlen))
                        goto err;

                if (outlen > INT_MAX)
                        goto err;

                s->init_num = (int)outlen;
                s->init_off = 0;

                if (SSL_is_dtls(s)) {
                        s->d1->handshake_write_seq =
                            s->d1->next_handshake_write_seq;
                        dtls1_set_message_header_int(s, SSL3_MT_CCS, 0,
                            s->d1->handshake_write_seq, 0, 0);
                        dtls1_buffer_message(s, 1);
                }

                s->s3->hs.state = SSL3_ST_SW_CHANGE_B;
        }

        /* SSL3_ST_SW_CHANGE_B */
        return ssl3_record_write(s, SSL3_RT_CHANGE_CIPHER_SPEC);

 err:
        CBB_cleanup(&cbb);

        return -1;
}

static int
ssl3_get_client_finished(SSL *s)
{
        int al, md_len, ret;
        CBS cbs;

        /* should actually be 36+4 :-) */
        if ((ret = ssl3_get_message(s, SSL3_ST_SR_FINISHED_A,
            SSL3_ST_SR_FINISHED_B, SSL3_MT_FINISHED, 64)) <= 0)
                return ret;

        /* If this occurs, we have missed a message */
        if (!s->s3->change_cipher_spec) {
                al = SSL_AD_UNEXPECTED_MESSAGE;
                SSLerror(s, SSL_R_GOT_A_FIN_BEFORE_A_CCS);
                goto fatal_err;
        }
        s->s3->change_cipher_spec = 0;

        md_len = TLS1_FINISH_MAC_LENGTH;

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

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

        if (s->s3->hs.peer_finished_len != md_len ||
            CBS_len(&cbs) != md_len) {
                al = SSL_AD_DECODE_ERROR;
                SSLerror(s, SSL_R_BAD_DIGEST_LENGTH);
                goto fatal_err;
        }

        if (!CBS_mem_equal(&cbs, s->s3->hs.peer_finished, CBS_len(&cbs))) {
                al = SSL_AD_DECRYPT_ERROR;
                SSLerror(s, SSL_R_DIGEST_CHECK_FAILED);
                goto fatal_err;
        }

        /* Copy finished so we can use it for renegotiation checks. */
        OPENSSL_assert(md_len <= EVP_MAX_MD_SIZE);
        memcpy(s->s3->previous_client_finished,
            s->s3->hs.peer_finished, md_len);
        s->s3->previous_client_finished_len = md_len;

        return (1);
 fatal_err:
        ssl3_send_alert(s, SSL3_AL_FATAL, al);
        return (0);
}

static int
ssl3_send_server_finished(SSL *s)
{
        CBB cbb, finished;

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

        if (s->s3->hs.state == SSL3_ST_SW_FINISHED_A) {
                if (!tls12_derive_finished(s))
                        goto err;

                /* Copy finished so we can use it for renegotiation checks. */
                memcpy(s->s3->previous_server_finished,
                    s->s3->hs.finished, s->s3->hs.finished_len);
                s->s3->previous_server_finished_len = s->s3->hs.finished_len;

                if (!ssl3_handshake_msg_start(s, &cbb, &finished,
                    SSL3_MT_FINISHED))
                        goto err;
                if (!CBB_add_bytes(&finished, s->s3->hs.finished,
                    s->s3->hs.finished_len))
                        goto err;
                if (!ssl3_handshake_msg_finish(s, &cbb))
                        goto err;

                s->s3->hs.state = SSL3_ST_SW_FINISHED_B;
        }

        return (ssl3_handshake_write(s));

 err:
        CBB_cleanup(&cbb);

        return (-1);
}