ssl/ssl_lib.c

/* 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.
 * ECC cipher suite support in OpenSSL originally developed by 
 * SUN MICROSYSTEMS, INC., and contributed to the OpenSSL project.
 */
/* ====================================================================
 * 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 <openssl/ssl.h>

#include <assert.h>
#include <stdlib.h>
#include <string.h>

#include <openssl/bytestring.h>
#include <openssl/crypto.h>
#include <openssl/dh.h>
#include <openssl/err.h>
#include <openssl/lhash.h>
#include <openssl/mem.h>
#include <openssl/rand.h>

#include "internal.h"
#include "../crypto/internal.h"

#if defined(OPENSSL_WINDOWS)
#include <sys/timeb.h>
#else
#include <sys/socket.h>
#include <sys/time.h>
#endif


/* |SSL_R_UNKNOWN_PROTOCOL| is no longer emitted, but continue to define it
 * to avoid downstream churn. */
OPENSSL_DECLARE_ERROR_REASON(SSL, UNKNOWN_PROTOCOL)

/* The following errors are no longer emitted, but are used in nginx without
 * #ifdefs. */
OPENSSL_DECLARE_ERROR_REASON(SSL, BLOCK_CIPHER_PAD_IS_WRONG)
OPENSSL_DECLARE_ERROR_REASON(SSL, NO_CIPHERS_SPECIFIED)

/* Some error codes are special. Ensure the make_errors.go script never
 * regresses this. */
OPENSSL_COMPILE_ASSERT(SSL_R_TLSV1_ALERT_NO_RENEGOTIATION ==
                           SSL_AD_NO_RENEGOTIATION + SSL_AD_REASON_OFFSET,
                       ssl_alert_reason_code_mismatch);

/* kMaxHandshakeSize is the maximum size, in bytes, of a handshake message. */
static const size_t kMaxHandshakeSize = (1u << 24) - 1;

static CRYPTO_EX_DATA_CLASS g_ex_data_class_ssl =
    CRYPTO_EX_DATA_CLASS_INIT_WITH_APP_DATA;
static CRYPTO_EX_DATA_CLASS g_ex_data_class_ssl_ctx =
    CRYPTO_EX_DATA_CLASS_INIT_WITH_APP_DATA;

int SSL_library_init(void) {
  CRYPTO_library_init();
  return 1;
}

static uint32_t ssl_session_hash(const SSL_SESSION *sess) {
  const uint8_t *session_id = sess->session_id;

  uint8_t tmp_storage[sizeof(uint32_t)];
  if (sess->session_id_length < sizeof(tmp_storage)) {
    memset(tmp_storage, 0, sizeof(tmp_storage));
    memcpy(tmp_storage, sess->session_id, sess->session_id_length);
    session_id = tmp_storage;
  }

  uint32_t hash =
      ((uint32_t)session_id[0]) |
      ((uint32_t)session_id[1] << 8) |
      ((uint32_t)session_id[2] << 16) |
      ((uint32_t)session_id[3] << 24);

  return hash;
}

/* NB: If this function (or indeed the hash function which uses a sort of
 * coarser function than this one) is changed, ensure
 * SSL_CTX_has_matching_session_id() is checked accordingly. It relies on being
 * able to construct an SSL_SESSION that will collide with any existing session
 * with a matching session ID. */
static int ssl_session_cmp(const SSL_SESSION *a, const SSL_SESSION *b) {
  if (a->ssl_version != b->ssl_version) {
    return 1;
  }

  if (a->session_id_length != b->session_id_length) {
    return 1;
  }

  return memcmp(a->session_id, b->session_id, a->session_id_length);
}

SSL_CTX *SSL_CTX_new(const SSL_METHOD *method) {
  SSL_CTX *ret = NULL;

  if (method == NULL) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_NULL_SSL_METHOD_PASSED);
    return NULL;
  }

  if (SSL_get_ex_data_X509_STORE_CTX_idx() < 0) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_X509_VERIFICATION_SETUP_PROBLEMS);
    goto err;
  }

  ret = OPENSSL_malloc(sizeof(SSL_CTX));
  if (ret == NULL) {
    goto err;
  }

  memset(ret, 0, sizeof(SSL_CTX));

  ret->method = method->method;

  CRYPTO_MUTEX_init(&ret->lock);

  ret->session_cache_mode = SSL_SESS_CACHE_SERVER;
  ret->session_cache_size = SSL_SESSION_CACHE_MAX_SIZE_DEFAULT;

  /* We take the system default */
  ret->session_timeout = SSL_DEFAULT_SESSION_TIMEOUT;

  ret->references = 1;

  ret->max_cert_list = SSL_MAX_CERT_LIST_DEFAULT;
  ret->verify_mode = SSL_VERIFY_NONE;
  ret->cert = ssl_cert_new();
  if (ret->cert == NULL) {
    goto err;
  }

  ret->sessions = lh_SSL_SESSION_new(ssl_session_hash, ssl_session_cmp);
  if (ret->sessions == NULL) {
    goto err;
  }
  ret->cert_store = X509_STORE_new();
  if (ret->cert_store == NULL) {
    goto err;
  }

  ssl_create_cipher_list(ret->method, &ret->cipher_list,
                         SSL_DEFAULT_CIPHER_LIST);
  if (ret->cipher_list == NULL ||
      sk_SSL_CIPHER_num(ret->cipher_list->ciphers) <= 0) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_LIBRARY_HAS_NO_CIPHERS);
    goto err2;
  }

  ret->param = X509_VERIFY_PARAM_new();
  if (!ret->param) {
    goto err;
  }

  ret->client_CA = sk_X509_NAME_new_null();
  if (ret->client_CA == NULL) {
    goto err;
  }

  CRYPTO_new_ex_data(&ret->ex_data);

  ret->max_send_fragment = SSL3_RT_MAX_PLAIN_LENGTH;

  /* Setup RFC4507 ticket keys */
  if (!RAND_bytes(ret->tlsext_tick_key_name, 16) ||
      !RAND_bytes(ret->tlsext_tick_hmac_key, 16) ||
      !RAND_bytes(ret->tlsext_tick_aes_key, 16)) {
    ret->options |= SSL_OP_NO_TICKET;
  }

  /* Disable the auto-chaining feature by default. Once this has stuck without
   * problems, the feature will be removed entirely. */
  ret->mode = SSL_MODE_NO_AUTO_CHAIN;

  /* Lock the SSL_CTX to the specified version, for compatibility with legacy
   * uses of SSL_METHOD. */
  if (!SSL_CTX_set_max_proto_version(ret, method->version) ||
      !SSL_CTX_set_min_proto_version(ret, method->version)) {
    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
    goto err2;
  }

  return ret;

err:
  OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
err2:
  SSL_CTX_free(ret);
  return NULL;
}

int SSL_CTX_up_ref(SSL_CTX *ctx) {
  CRYPTO_refcount_inc(&ctx->references);
  return 1;
}

void SSL_CTX_free(SSL_CTX *ctx) {
  if (ctx == NULL ||
      !CRYPTO_refcount_dec_and_test_zero(&ctx->references)) {
    return;
  }

  X509_VERIFY_PARAM_free(ctx->param);

  /* Free internal session cache. However: the remove_cb() may reference the
   * ex_data of SSL_CTX, thus the ex_data store can only be removed after the
   * sessions were flushed. As the ex_data handling routines might also touch
   * the session cache, the most secure solution seems to be: empty (flush) the
   * cache, then free ex_data, then finally free the cache. (See ticket
   * [openssl.org #212].) */
  SSL_CTX_flush_sessions(ctx, 0);

  CRYPTO_free_ex_data(&g_ex_data_class_ssl_ctx, ctx, &ctx->ex_data);

  CRYPTO_MUTEX_cleanup(&ctx->lock);
  lh_SSL_SESSION_free(ctx->sessions);
  X509_STORE_free(ctx->cert_store);
  ssl_cipher_preference_list_free(ctx->cipher_list);
  ssl_cert_free(ctx->cert);
  sk_SSL_CUSTOM_EXTENSION_pop_free(ctx->client_custom_extensions,
                                   SSL_CUSTOM_EXTENSION_free);
  sk_SSL_CUSTOM_EXTENSION_pop_free(ctx->server_custom_extensions,
                                   SSL_CUSTOM_EXTENSION_free);
  sk_X509_NAME_pop_free(ctx->client_CA, X509_NAME_free);
  sk_SRTP_PROTECTION_PROFILE_free(ctx->srtp_profiles);
  OPENSSL_free(ctx->psk_identity_hint);
  OPENSSL_free(ctx->supported_group_list);
  OPENSSL_free(ctx->alpn_client_proto_list);
  CRYPTO_BUFFER_free(ctx->ocsp_response);
  OPENSSL_free(ctx->signed_cert_timestamp_list);
  EVP_PKEY_free(ctx->tlsext_channel_id_private);

  OPENSSL_free(ctx);
}

SSL *SSL_new(SSL_CTX *ctx) {
  if (ctx == NULL) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_NULL_SSL_CTX);
    return NULL;
  }
  if (ctx->method == NULL) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_SSL_CTX_HAS_NO_DEFAULT_SSL_VERSION);
    return NULL;
  }

  SSL *ssl = OPENSSL_malloc(sizeof(SSL));
  if (ssl == NULL) {
    goto err;
  }
  memset(ssl, 0, sizeof(SSL));

  ssl->min_version = ctx->min_version;
  ssl->max_version = ctx->max_version;

  /* RFC 6347 states that implementations SHOULD use an initial timer value of
   * 1 second. */
  ssl->initial_timeout_duration_ms = 1000;

  ssl->options = ctx->options;
  ssl->mode = ctx->mode;
  ssl->max_cert_list = ctx->max_cert_list;

  ssl->cert = ssl_cert_dup(ctx->cert);
  if (ssl->cert == NULL) {
    goto err;
  }

  ssl->msg_callback = ctx->msg_callback;
  ssl->msg_callback_arg = ctx->msg_callback_arg;
  ssl->verify_mode = ctx->verify_mode;
  ssl->sid_ctx_length = ctx->sid_ctx_length;
  assert(ssl->sid_ctx_length <= sizeof ssl->sid_ctx);
  memcpy(&ssl->sid_ctx, &ctx->sid_ctx, sizeof(ssl->sid_ctx));
  ssl->verify_callback = ctx->default_verify_callback;
  ssl->retain_only_sha256_of_client_certs =
      ctx->retain_only_sha256_of_client_certs;

  ssl->param = X509_VERIFY_PARAM_new();
  if (!ssl->param) {
    goto err;
  }
  X509_VERIFY_PARAM_inherit(ssl->param, ctx->param);
  ssl->quiet_shutdown = ctx->quiet_shutdown;
  ssl->max_send_fragment = ctx->max_send_fragment;

  CRYPTO_refcount_inc(&ctx->references);
  ssl->ctx = ctx;
  CRYPTO_refcount_inc(&ctx->references);
  ssl->initial_ctx = ctx;

  if (ctx->supported_group_list) {
    ssl->supported_group_list =
        BUF_memdup(ctx->supported_group_list,
                   ctx->supported_group_list_len * 2);
    if (!ssl->supported_group_list) {
      goto err;
    }
    ssl->supported_group_list_len = ctx->supported_group_list_len;
  }

  if (ssl->ctx->alpn_client_proto_list) {
    ssl->alpn_client_proto_list = BUF_memdup(
        ssl->ctx->alpn_client_proto_list, ssl->ctx->alpn_client_proto_list_len);
    if (ssl->alpn_client_proto_list == NULL) {
      goto err;
    }
    ssl->alpn_client_proto_list_len = ssl->ctx->alpn_client_proto_list_len;
  }

  ssl->method = ctx->method;

  if (!ssl->method->ssl_new(ssl)) {
    goto err;
  }

  ssl->rwstate = SSL_NOTHING;

  CRYPTO_new_ex_data(&ssl->ex_data);

  ssl->psk_identity_hint = NULL;
  if (ctx->psk_identity_hint) {
    ssl->psk_identity_hint = BUF_strdup(ctx->psk_identity_hint);
    if (ssl->psk_identity_hint == NULL) {
      goto err;
    }
  }
  ssl->psk_client_callback = ctx->psk_client_callback;
  ssl->psk_server_callback = ctx->psk_server_callback;

  ssl->tlsext_channel_id_enabled = ctx->tlsext_channel_id_enabled;
  if (ctx->tlsext_channel_id_private) {
    EVP_PKEY_up_ref(ctx->tlsext_channel_id_private);
    ssl->tlsext_channel_id_private = ctx->tlsext_channel_id_private;
  }

  ssl->signed_cert_timestamps_enabled =
      ssl->ctx->signed_cert_timestamps_enabled;
  ssl->ocsp_stapling_enabled = ssl->ctx->ocsp_stapling_enabled;

  ssl->session_timeout = SSL_DEFAULT_SESSION_TIMEOUT;

  /* If the context has a default timeout, use it over the default. */
  if (ctx->session_timeout != 0) {
    ssl->session_timeout = ctx->session_timeout;
  }

  /* If the context has an OCSP response, use it. */
  if (ctx->ocsp_response != NULL) {
    CRYPTO_BUFFER_up_ref(ctx->ocsp_response);
    ssl->ocsp_response = ctx->ocsp_response;
  }

  return ssl;

err:
  SSL_free(ssl);
  OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);

  return NULL;
}

void SSL_free(SSL *ssl) {
  if (ssl == NULL) {
    return;
  }

  X509_VERIFY_PARAM_free(ssl->param);

  CRYPTO_free_ex_data(&g_ex_data_class_ssl, ssl, &ssl->ex_data);

  ssl_free_wbio_buffer(ssl);
  assert(ssl->bbio == NULL);

  BIO_free_all(ssl->rbio);
  BIO_free_all(ssl->wbio);

  BUF_MEM_free(ssl->init_buf);

  /* add extra stuff */
  ssl_cipher_preference_list_free(ssl->cipher_list);

  SSL_SESSION_free(ssl->session);

  ssl_cert_free(ssl->cert);

  OPENSSL_free(ssl->tlsext_hostname);
  SSL_CTX_free(ssl->initial_ctx);
  OPENSSL_free(ssl->supported_group_list);
  OPENSSL_free(ssl->alpn_client_proto_list);
  EVP_PKEY_free(ssl->tlsext_channel_id_private);
  OPENSSL_free(ssl->psk_identity_hint);
  sk_X509_NAME_pop_free(ssl->client_CA, X509_NAME_free);
  sk_SRTP_PROTECTION_PROFILE_free(ssl->srtp_profiles);
  CRYPTO_BUFFER_free(ssl->ocsp_response);

  if (ssl->method != NULL) {
    ssl->method->ssl_free(ssl);
  }
  SSL_CTX_free(ssl->ctx);

  OPENSSL_free(ssl);
}

void SSL_set_connect_state(SSL *ssl) {
  ssl->server = 0;
  ssl->handshake_func = ssl3_connect;
}

void SSL_set_accept_state(SSL *ssl) {
  ssl->server = 1;
  ssl->handshake_func = ssl3_accept;
}

void SSL_set0_rbio(SSL *ssl, BIO *rbio) {
  BIO_free_all(ssl->rbio);
  ssl->rbio = rbio;
}

void SSL_set0_wbio(SSL *ssl, BIO *wbio) {
  /* If the output buffering BIO is still in place, remove it. */
  if (ssl->bbio != NULL) {
    ssl->wbio = BIO_pop(ssl->wbio);
  }

  BIO_free_all(ssl->wbio);
  ssl->wbio = wbio;

  /* Re-attach |bbio| to the new |wbio|. */
  if (ssl->bbio != NULL) {
    ssl->wbio = BIO_push(ssl->bbio, ssl->wbio);
  }
}

void SSL_set_bio(SSL *ssl, BIO *rbio, BIO *wbio) {
  /* For historical reasons, this function has many different cases in ownership
   * handling. */

  /* If nothing has changed, do nothing */
  if (rbio == SSL_get_rbio(ssl) && wbio == SSL_get_wbio(ssl)) {
    return;
  }

  /* If the two arguments are equal, one fewer reference is granted than
   * taken. */
  if (rbio != NULL && rbio == wbio) {
    BIO_up_ref(rbio);
  }

  /* If only the wbio is changed, adopt only one reference. */
  if (rbio == SSL_get_rbio(ssl)) {
    SSL_set0_wbio(ssl, wbio);
    return;
  }

  /* There is an asymmetry here for historical reasons. If only the rbio is
   * changed AND the rbio and wbio were originally different, then we only adopt
   * one reference. */
  if (wbio == SSL_get_wbio(ssl) && SSL_get_rbio(ssl) != SSL_get_wbio(ssl)) {
    SSL_set0_rbio(ssl, rbio);
    return;
  }

  /* Otherwise, adopt both references. */
  SSL_set0_rbio(ssl, rbio);
  SSL_set0_wbio(ssl, wbio);
}

BIO *SSL_get_rbio(const SSL *ssl) { return ssl->rbio; }

BIO *SSL_get_wbio(const SSL *ssl) {
  if (ssl->bbio != NULL) {
    /* If |bbio| is active, the true caller-configured BIO is its |next_bio|. */
    assert(ssl->bbio == ssl->wbio);
    return ssl->bbio->next_bio;
  }
  return ssl->wbio;
}

int SSL_do_handshake(SSL *ssl) {
  ssl->rwstate = SSL_NOTHING;
  /* Functions which use SSL_get_error must clear the error queue on entry. */
  ERR_clear_error();
  ERR_clear_system_error();

  if (ssl->handshake_func == NULL) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_CONNECTION_TYPE_NOT_SET);
    return -1;
  }

  if (!SSL_in_init(ssl)) {
    return 1;
  }

  if (ssl->s3->hs == NULL) {
    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
    return -1;
  }

  /* Run the handshake. */
  assert(ssl->s3->hs != NULL);
  int ret = ssl->handshake_func(ssl->s3->hs);
  if (ret <= 0) {
    return ret;
  }

  /* Destroy the handshake object if the handshake has completely finished. */
  if (!SSL_in_init(ssl)) {
    ssl_handshake_free(ssl->s3->hs);
    ssl->s3->hs = NULL;
  }

  return 1;
}

int SSL_connect(SSL *ssl) {
  if (ssl->handshake_func == NULL) {
    /* Not properly initialized yet */
    SSL_set_connect_state(ssl);
  }

  return SSL_do_handshake(ssl);
}

int SSL_accept(SSL *ssl) {
  if (ssl->handshake_func == NULL) {
    /* Not properly initialized yet */
    SSL_set_accept_state(ssl);
  }

  return SSL_do_handshake(ssl);
}

static int ssl_do_renegotiate(SSL *ssl) {
  /* We do not accept renegotiations as a server or SSL 3.0. SSL 3.0 will be
   * removed entirely in the future and requires retaining more data for
   * renegotiation_info. */
  if (ssl->server || ssl->version == SSL3_VERSION) {
    goto no_renegotiation;
  }

  if (ssl->s3->tmp.message_type != SSL3_MT_HELLO_REQUEST ||
      ssl->init_num != 0) {
    ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
    OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_HELLO_REQUEST);
    return 0;
  }

  switch (ssl->renegotiate_mode) {
    case ssl_renegotiate_ignore:
      /* Ignore the HelloRequest. */
      return 1;

    case ssl_renegotiate_once:
      if (ssl->s3->total_renegotiations != 0) {
        goto no_renegotiation;
      }
      break;

    case ssl_renegotiate_never:
      goto no_renegotiation;

    case ssl_renegotiate_freely:
      break;
  }

  /* Renegotiation is only supported at quiescent points in the application
   * protocol, namely in HTTPS, just before reading the HTTP response. Require
   * the record-layer be idle and avoid complexities of sending a handshake
   * record while an application_data record is being written. */
  if (ssl_write_buffer_is_pending(ssl)) {
    goto no_renegotiation;
  }

  /* Begin a new handshake. */
  if (ssl->s3->hs != NULL) {
    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
    return 0;
  }
  ssl->s3->hs = ssl_handshake_new(ssl);
  if (ssl->s3->hs == NULL) {
    return 0;
  }

  ssl->s3->total_renegotiations++;
  return 1;

no_renegotiation:
  ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_NO_RENEGOTIATION);
  OPENSSL_PUT_ERROR(SSL, SSL_R_NO_RENEGOTIATION);
  return 0;
}

static int ssl_do_post_handshake(SSL *ssl) {
  if (ssl3_protocol_version(ssl) < TLS1_3_VERSION) {
    return ssl_do_renegotiate(ssl);
  }

  return tls13_post_handshake(ssl);
}

static int ssl_read_impl(SSL *ssl, void *buf, int num, int peek) {
  ssl->rwstate = SSL_NOTHING;
  /* Functions which use SSL_get_error must clear the error queue on entry. */
  ERR_clear_error();
  ERR_clear_system_error();

  if (ssl->handshake_func == NULL) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_UNINITIALIZED);
    return -1;
  }

  for (;;) {
    /* Complete the current handshake, if any. False Start will cause
     * |SSL_do_handshake| to return mid-handshake, so this may require multiple
     * iterations. */
    while (SSL_in_init(ssl)) {
      int ret = SSL_do_handshake(ssl);
      if (ret < 0) {
        return ret;
      }
      if (ret == 0) {
        OPENSSL_PUT_ERROR(SSL, SSL_R_SSL_HANDSHAKE_FAILURE);
        return -1;
      }
    }

    int got_handshake;
    int ret = ssl->method->read_app_data(ssl, &got_handshake, buf, num, peek);
    if (ret > 0 || !got_handshake) {
      ssl->s3->key_update_count = 0;
      return ret;
    }

    /* Handle the post-handshake message and try again. */
    if (!ssl_do_post_handshake(ssl)) {
      return -1;
    }
    ssl->method->release_current_message(ssl, 1 /* free buffer */);
  }
}

int SSL_read(SSL *ssl, void *buf, int num) {
  return ssl_read_impl(ssl, buf, num, 0 /* consume bytes */);
}

int SSL_peek(SSL *ssl, void *buf, int num) {
  return ssl_read_impl(ssl, buf, num, 1 /* peek */);
}

int SSL_write(SSL *ssl, const void *buf, int num) {
  ssl->rwstate = SSL_NOTHING;
  /* Functions which use SSL_get_error must clear the error queue on entry. */
  ERR_clear_error();
  ERR_clear_system_error();

  if (ssl->handshake_func == NULL) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_UNINITIALIZED);
    return -1;
  }

  if (ssl->s3->send_shutdown != ssl_shutdown_none) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_PROTOCOL_IS_SHUTDOWN);
    return -1;
  }

  /* If necessary, complete the handshake implicitly. */
  if (SSL_in_init(ssl) && !SSL_in_false_start(ssl)) {
    int ret = SSL_do_handshake(ssl);
    if (ret < 0) {
      return ret;
    }
    if (ret == 0) {
      OPENSSL_PUT_ERROR(SSL, SSL_R_SSL_HANDSHAKE_FAILURE);
      return -1;
    }
  }

  return ssl->method->write_app_data(ssl, buf, num);
}

int SSL_shutdown(SSL *ssl) {
  ssl->rwstate = SSL_NOTHING;
  /* Functions which use SSL_get_error must clear the error queue on entry. */
  ERR_clear_error();
  ERR_clear_system_error();

  if (ssl->handshake_func == NULL) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_UNINITIALIZED);
    return -1;
  }

  /* We can't shutdown properly if we are in the middle of a handshake. */
  if (SSL_in_init(ssl)) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_SHUTDOWN_WHILE_IN_INIT);
    return -1;
  }

  if (ssl->quiet_shutdown) {
    /* Do nothing if configured not to send a close_notify. */
    ssl->s3->send_shutdown = ssl_shutdown_close_notify;
    ssl->s3->recv_shutdown = ssl_shutdown_close_notify;
    return 1;
  }

  /* This function completes in two stages. It sends a close_notify and then it
   * waits for a close_notify to come in. Perform exactly one action and return
   * whether or not it succeeds. */

  if (ssl->s3->send_shutdown != ssl_shutdown_close_notify) {
    /* Send a close_notify. */
    if (ssl3_send_alert(ssl, SSL3_AL_WARNING, SSL_AD_CLOSE_NOTIFY) <= 0) {
      return -1;
    }
  } else if (ssl->s3->alert_dispatch) {
    /* Finish sending the close_notify. */
    if (ssl->method->dispatch_alert(ssl) <= 0) {
      return -1;
    }
  } else if (ssl->s3->recv_shutdown != ssl_shutdown_close_notify) {
    /* Wait for the peer's close_notify. */
    ssl->method->read_close_notify(ssl);
    if (ssl->s3->recv_shutdown != ssl_shutdown_close_notify) {
      return -1;
    }
  }

  /* Return 0 for unidirectional shutdown and 1 for bidirectional shutdown. */
  return ssl->s3->recv_shutdown == ssl_shutdown_close_notify;
}

int SSL_send_fatal_alert(SSL *ssl, uint8_t alert) {
  if (ssl->s3->alert_dispatch) {
    if (ssl->s3->send_alert[0] != SSL3_AL_FATAL ||
        ssl->s3->send_alert[1] != alert) {
      /* We are already attempting to write a different alert. */
      OPENSSL_PUT_ERROR(SSL, SSL_R_PROTOCOL_IS_SHUTDOWN);
      return -1;
    }
    return ssl->method->dispatch_alert(ssl);
  }

  return ssl3_send_alert(ssl, SSL3_AL_FATAL, alert);
}

static int bio_retry_reason_to_error(int reason) {
  switch (reason) {
    case BIO_RR_CONNECT:
      return SSL_ERROR_WANT_CONNECT;
    case BIO_RR_ACCEPT:
      return SSL_ERROR_WANT_ACCEPT;
    default:
      return SSL_ERROR_SYSCALL;
  }
}

int SSL_get_error(const SSL *ssl, int ret_code) {
  if (ret_code > 0) {
    return SSL_ERROR_NONE;
  }

  /* Make things return SSL_ERROR_SYSCALL when doing SSL_do_handshake etc,
   * where we do encode the error */
  uint32_t err = ERR_peek_error();
  if (err != 0) {
    if (ERR_GET_LIB(err) == ERR_LIB_SYS) {
      return SSL_ERROR_SYSCALL;
    }
    return SSL_ERROR_SSL;
  }

  if (ret_code == 0) {
    if (ssl->s3->recv_shutdown == ssl_shutdown_close_notify) {
      return SSL_ERROR_ZERO_RETURN;
    }
    /* An EOF was observed which violates the protocol, and the underlying
     * transport does not participate in the error queue. Bubble up to the
     * caller. */
    return SSL_ERROR_SYSCALL;
  }

  switch (ssl->rwstate) {
    case SSL_PENDING_SESSION:
      return SSL_ERROR_PENDING_SESSION;

    case SSL_CERTIFICATE_SELECTION_PENDING:
      return SSL_ERROR_PENDING_CERTIFICATE;

    case SSL_READING: {
      BIO *bio = SSL_get_rbio(ssl);
      if (BIO_should_read(bio)) {
        return SSL_ERROR_WANT_READ;
      }

      if (BIO_should_write(bio)) {
        /* TODO(davidben): OpenSSL historically checked for writes on the read
         * BIO. Can this be removed? */
        return SSL_ERROR_WANT_WRITE;
      }

      if (BIO_should_io_special(bio)) {
        return bio_retry_reason_to_error(BIO_get_retry_reason(bio));
      }

      break;
    }

    case SSL_WRITING: {
      BIO *bio = SSL_get_wbio(ssl);
      if (BIO_should_write(bio)) {
        return SSL_ERROR_WANT_WRITE;
      }

      if (BIO_should_read(bio)) {
        /* TODO(davidben): OpenSSL historically checked for reads on the write
         * BIO. Can this be removed? */
        return SSL_ERROR_WANT_READ;
      }

      if (BIO_should_io_special(bio)) {
        return bio_retry_reason_to_error(BIO_get_retry_reason(bio));
      }

      break;
    }

    case SSL_X509_LOOKUP:
      return SSL_ERROR_WANT_X509_LOOKUP;

    case SSL_CHANNEL_ID_LOOKUP:
      return SSL_ERROR_WANT_CHANNEL_ID_LOOKUP;

    case SSL_PRIVATE_KEY_OPERATION:
      return SSL_ERROR_WANT_PRIVATE_KEY_OPERATION;
  }

  return SSL_ERROR_SYSCALL;
}

static int set_min_version(const SSL_PROTOCOL_METHOD *method, uint16_t *out,
                           uint16_t version) {
  if (version == 0) {
    *out = method->min_version;
    return 1;
  }

  if (version == TLS1_3_VERSION) {
    version = TLS1_3_DRAFT_VERSION;
  }

  return method->version_from_wire(out, version);
}

static int set_max_version(const SSL_PROTOCOL_METHOD *method, uint16_t *out,
                           uint16_t version) {
  if (version == 0) {
    *out = method->max_version;
    /* TODO(svaldez): Enable TLS 1.3 by default once fully implemented. */
    if (*out > TLS1_2_VERSION) {
      *out = TLS1_2_VERSION;
    }
    return 1;
  }

  if (version == TLS1_3_VERSION) {
    version = TLS1_3_DRAFT_VERSION;
  }

  return method->version_from_wire(out, version);
}

int SSL_CTX_set_min_proto_version(SSL_CTX *ctx, uint16_t version) {
  return set_min_version(ctx->method, &ctx->min_version, version);
}

int SSL_CTX_set_max_proto_version(SSL_CTX *ctx, uint16_t version) {
  return set_max_version(ctx->method, &ctx->max_version, version);
}

int SSL_set_min_proto_version(SSL *ssl, uint16_t version) {
  return set_min_version(ssl->method, &ssl->min_version, version);
}

int SSL_set_max_proto_version(SSL *ssl, uint16_t version) {
  return set_max_version(ssl->method, &ssl->max_version, version);
}

uint32_t SSL_CTX_set_options(SSL_CTX *ctx, uint32_t options) {
  ctx->options |= options;
  return ctx->options;
}

uint32_t SSL_CTX_clear_options(SSL_CTX *ctx, uint32_t options) {
  ctx->options &= ~options;
  return ctx->options;
}

uint32_t SSL_CTX_get_options(const SSL_CTX *ctx) { return ctx->options; }

uint32_t SSL_set_options(SSL *ssl, uint32_t options) {
  ssl->options |= options;
  return ssl->options;
}

uint32_t SSL_clear_options(SSL *ssl, uint32_t options) {
  ssl->options &= ~options;
  return ssl->options;
}

uint32_t SSL_get_options(const SSL *ssl) { return ssl->options; }

uint32_t SSL_CTX_set_mode(SSL_CTX *ctx, uint32_t mode) {
  ctx->mode |= mode;
  return ctx->mode;
}

uint32_t SSL_CTX_clear_mode(SSL_CTX *ctx, uint32_t mode) {
  ctx->mode &= ~mode;
  return ctx->mode;
}

uint32_t SSL_CTX_get_mode(const SSL_CTX *ctx) { return ctx->mode; }

uint32_t SSL_set_mode(SSL *ssl, uint32_t mode) {
  ssl->mode |= mode;
  return ssl->mode;
}

uint32_t SSL_clear_mode(SSL *ssl, uint32_t mode) {
  ssl->mode &= ~mode;
  return ssl->mode;
}

uint32_t SSL_get_mode(const SSL *ssl) { return ssl->mode; }

void SSL_CTX_set0_buffer_pool(SSL_CTX *ctx, CRYPTO_BUFFER_POOL *pool) {
  ctx->pool = pool;
}

X509 *SSL_get_peer_certificate(const SSL *ssl) {
  if (ssl == NULL) {
    return NULL;
  }
  SSL_SESSION *session = SSL_get_session(ssl);
  if (session == NULL || session->x509_peer == NULL) {
    return NULL;
  }
  X509_up_ref(session->x509_peer);
  return session->x509_peer;
}

STACK_OF(X509) *SSL_get_peer_cert_chain(const SSL *ssl) {
  if (ssl == NULL) {
    return NULL;
  }
  SSL_SESSION *session = SSL_get_session(ssl);
  if (session == NULL ||
      session->x509_chain == NULL) {
    return NULL;
  }

  if (!ssl->server) {
    return session->x509_chain;
  }

  /* OpenSSL historically didn't include the leaf certificate in the returned
   * certificate chain, but only for servers. */
  if (session->x509_chain_without_leaf == NULL) {
    session->x509_chain_without_leaf = sk_X509_new_null();
    if (session->x509_chain_without_leaf == NULL) {
      return NULL;
    }

    for (size_t i = 1; i < sk_X509_num(session->x509_chain); i++) {
      X509 *cert = sk_X509_value(session->x509_chain, i);
      if (!sk_X509_push(session->x509_chain_without_leaf, cert)) {
        sk_X509_pop_free(session->x509_chain_without_leaf, X509_free);
        session->x509_chain_without_leaf = NULL;
        return NULL;
      }
      X509_up_ref(cert);
    }
  }

  return session->x509_chain_without_leaf;
}

STACK_OF(X509) *SSL_get_peer_full_cert_chain(const SSL *ssl) {
  SSL_SESSION *session = SSL_get_session(ssl);
  if (session == NULL) {
    return NULL;
  }

  return session->x509_chain;
}

int SSL_get_tls_unique(const SSL *ssl, uint8_t *out, size_t *out_len,
                       size_t max_out) {
  /* tls-unique is not defined for SSL 3.0 or TLS 1.3. */
  if (!ssl->s3->initial_handshake_complete ||
      ssl3_protocol_version(ssl) < TLS1_VERSION ||
      ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
    goto err;
  }

  /* The tls-unique value is the first Finished message in the handshake, which
   * is the client's in a full handshake and the server's for a resumption. See
   * https://tools.ietf.org/html/rfc5929#section-3.1. */
  const uint8_t *finished = ssl->s3->previous_client_finished;
  size_t finished_len = ssl->s3->previous_client_finished_len;
  if (ssl->session != NULL) {
    /* tls-unique is broken for resumed sessions unless EMS is used. */
    if (!ssl->session->extended_master_secret) {
      goto err;
    }
    finished = ssl->s3->previous_server_finished;
    finished_len = ssl->s3->previous_server_finished_len;
  }

  *out_len = finished_len;
  if (finished_len > max_out) {
    *out_len = max_out;
  }

  memcpy(out, finished, *out_len);
  return 1;

err:
  *out_len = 0;
  memset(out, 0, max_out);
  return 0;
}

int SSL_CTX_set_session_id_context(SSL_CTX *ctx, const uint8_t *sid_ctx,
                                   size_t sid_ctx_len) {
  if (sid_ctx_len > sizeof(ctx->sid_ctx)) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_SSL_SESSION_ID_CONTEXT_TOO_LONG);
    return 0;
  }

  assert(sizeof(ctx->sid_ctx) < 256);
  ctx->sid_ctx_length = (uint8_t)sid_ctx_len;
  memcpy(ctx->sid_ctx, sid_ctx, sid_ctx_len);

  return 1;
}

int SSL_set_session_id_context(SSL *ssl, const uint8_t *sid_ctx,
                               size_t sid_ctx_len) {
  if (sid_ctx_len > sizeof(ssl->sid_ctx)) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_SSL_SESSION_ID_CONTEXT_TOO_LONG);
    return 0;
  }

  assert(sizeof(ssl->sid_ctx) < 256);
  ssl->sid_ctx_length = (uint8_t)sid_ctx_len;
  memcpy(ssl->sid_ctx, sid_ctx, sid_ctx_len);

  return 1;
}

int SSL_CTX_set_purpose(SSL_CTX *ctx, int purpose) {
  return X509_VERIFY_PARAM_set_purpose(ctx->param, purpose);
}

int SSL_set_purpose(SSL *ssl, int purpose) {
  return X509_VERIFY_PARAM_set_purpose(ssl->param, purpose);
}

int SSL_CTX_set_trust(SSL_CTX *ctx, int trust) {
  return X509_VERIFY_PARAM_set_trust(ctx->param, trust);
}

int SSL_set_trust(SSL *ssl, int trust) {
  return X509_VERIFY_PARAM_set_trust(ssl->param, trust);
}

int SSL_CTX_set1_param(SSL_CTX *ctx, const X509_VERIFY_PARAM *param) {
  return X509_VERIFY_PARAM_set1(ctx->param, param);
}

int SSL_set1_param(SSL *ssl, const X509_VERIFY_PARAM *param) {
  return X509_VERIFY_PARAM_set1(ssl->param, param);
}

void ssl_cipher_preference_list_free(
    struct ssl_cipher_preference_list_st *cipher_list) {
  if (cipher_list == NULL) {
    return;
  }
  sk_SSL_CIPHER_free(cipher_list->ciphers);
  OPENSSL_free(cipher_list->in_group_flags);
  OPENSSL_free(cipher_list);
}

X509_VERIFY_PARAM *SSL_CTX_get0_param(SSL_CTX *ctx) { return ctx->param; }

X509_VERIFY_PARAM *SSL_get0_param(SSL *ssl) { return ssl->param; }

void SSL_certs_clear(SSL *ssl) { ssl_cert_clear_certs(ssl->cert); }

int SSL_get_fd(const SSL *ssl) { return SSL_get_rfd(ssl); }

int SSL_get_rfd(const SSL *ssl) {
  int ret = -1;
  BIO *b = BIO_find_type(SSL_get_rbio(ssl), BIO_TYPE_DESCRIPTOR);
  if (b != NULL) {
    BIO_get_fd(b, &ret);
  }
  return ret;
}

int SSL_get_wfd(const SSL *ssl) {
  int ret = -1;
  BIO *b = BIO_find_type(SSL_get_wbio(ssl), BIO_TYPE_DESCRIPTOR);
  if (b != NULL) {
    BIO_get_fd(b, &ret);
  }
  return ret;
}

int SSL_set_fd(SSL *ssl, int fd) {
  BIO *bio = BIO_new(BIO_s_socket());
  if (bio == NULL) {
    OPENSSL_PUT_ERROR(SSL, ERR_R_BUF_LIB);
    return 0;
  }
  BIO_set_fd(bio, fd, BIO_NOCLOSE);
  SSL_set_bio(ssl, bio, bio);
  return 1;
}

int SSL_set_wfd(SSL *ssl, int fd) {
  BIO *rbio = SSL_get_rbio(ssl);
  if (rbio == NULL || BIO_method_type(rbio) != BIO_TYPE_SOCKET ||
      BIO_get_fd(rbio, NULL) != fd) {
    BIO *bio = BIO_new(BIO_s_socket());
    if (bio == NULL) {
      OPENSSL_PUT_ERROR(SSL, ERR_R_BUF_LIB);
      return 0;
    }
    BIO_set_fd(bio, fd, BIO_NOCLOSE);
    SSL_set0_wbio(ssl, bio);
  } else {
    /* Copy the rbio over to the wbio. */
    BIO_up_ref(rbio);
    SSL_set0_wbio(ssl, rbio);
  }

  return 1;
}

int SSL_set_rfd(SSL *ssl, int fd) {
  BIO *wbio = SSL_get_wbio(ssl);
  if (wbio == NULL || BIO_method_type(wbio) != BIO_TYPE_SOCKET ||
      BIO_get_fd(wbio, NULL) != fd) {
    BIO *bio = BIO_new(BIO_s_socket());
    if (bio == NULL) {
      OPENSSL_PUT_ERROR(SSL, ERR_R_BUF_LIB);
      return 0;
    }
    BIO_set_fd(bio, fd, BIO_NOCLOSE);
    SSL_set0_rbio(ssl, bio);
  } else {
    /* Copy the wbio over to the rbio. */
    BIO_up_ref(wbio);
    SSL_set0_rbio(ssl, wbio);
  }
  return 1;
}

static size_t copy_finished(void *out, size_t out_len, const uint8_t *in,
                            size_t in_len) {
  if (out_len > in_len) {
    out_len = in_len;
  }
  memcpy(out, in, out_len);
  return in_len;
}

size_t SSL_get_finished(const SSL *ssl, void *buf, size_t count) {
  if (!ssl->s3->initial_handshake_complete ||
      ssl3_protocol_version(ssl) < TLS1_VERSION ||
      ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
    return 0;
  }

  if (ssl->server) {
    return copy_finished(buf, count, ssl->s3->previous_server_finished,
                         ssl->s3->previous_server_finished_len);
  }

  return copy_finished(buf, count, ssl->s3->previous_client_finished,
                       ssl->s3->previous_client_finished_len);
}

size_t SSL_get_peer_finished(const SSL *ssl, void *buf, size_t count) {
  if (!ssl->s3->initial_handshake_complete ||
      ssl3_protocol_version(ssl) < TLS1_VERSION ||
      ssl3_protocol_version(ssl) >= TLS1_3_VERSION) {
    return 0;
  }

  if (ssl->server) {
    return copy_finished(buf, count, ssl->s3->previous_client_finished,
                         ssl->s3->previous_client_finished_len);
  }

  return copy_finished(buf, count, ssl->s3->previous_server_finished,
                       ssl->s3->previous_server_finished_len);
}

int SSL_get_verify_mode(const SSL *ssl) { return ssl->verify_mode; }

int SSL_get_verify_depth(const SSL *ssl) {
  return X509_VERIFY_PARAM_get_depth(ssl->param);
}

int SSL_get_extms_support(const SSL *ssl) {
  if (!ssl->s3->have_version) {
    return 0;
  }
  return ssl3_protocol_version(ssl) >= TLS1_3_VERSION ||
         ssl->s3->tmp.extended_master_secret == 1;
}

int (*SSL_get_verify_callback(const SSL *ssl))(int, X509_STORE_CTX *) {
  return ssl->verify_callback;
}

int SSL_CTX_get_verify_mode(const SSL_CTX *ctx) { return ctx->verify_mode; }

int SSL_CTX_get_verify_depth(const SSL_CTX *ctx) {
  return X509_VERIFY_PARAM_get_depth(ctx->param);
}

int (*SSL_CTX_get_verify_callback(const SSL_CTX *ctx))(
    int ok, X509_STORE_CTX *store_ctx) {
  return ctx->default_verify_callback;
}

void SSL_set_verify(SSL *ssl, int mode,
                    int (*callback)(int ok, X509_STORE_CTX *store_ctx)) {
  ssl->verify_mode = mode;
  if (callback != NULL) {
    ssl->verify_callback = callback;
  }
}

void SSL_set_verify_depth(SSL *ssl, int depth) {
  X509_VERIFY_PARAM_set_depth(ssl->param, depth);
}

int SSL_CTX_get_read_ahead(const SSL_CTX *ctx) { return 0; }

int SSL_get_read_ahead(const SSL *ssl) { return 0; }

void SSL_CTX_set_read_ahead(SSL_CTX *ctx, int yes) { }

void SSL_set_read_ahead(SSL *ssl, int yes) { }

int SSL_pending(const SSL *ssl) {
  if (ssl->s3->rrec.type != SSL3_RT_APPLICATION_DATA) {
    return 0;
  }
  return ssl->s3->rrec.length;
}

/* Fix this so it checks all the valid key/cert options */
int SSL_CTX_check_private_key(const SSL_CTX *ctx) {
  if (ctx->cert->privatekey == NULL) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_NO_PRIVATE_KEY_ASSIGNED);
    return 0;
  }

  X509 *x509 = ctx->cert->x509_leaf;
  if (x509 == NULL) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_NO_CERTIFICATE_ASSIGNED);
    return 0;
  }

  return X509_check_private_key(x509, ctx->cert->privatekey);
}

/* Fix this function so that it takes an optional type parameter */
int SSL_check_private_key(const SSL *ssl) {
  if (ssl->cert->privatekey == NULL) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_NO_PRIVATE_KEY_ASSIGNED);
    return 0;
  }

  X509 *x509 = ssl->cert->x509_leaf;
  if (x509 == NULL) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_NO_CERTIFICATE_ASSIGNED);
    return 0;
  }

  return X509_check_private_key(x509, ssl->cert->privatekey);
}

long SSL_get_default_timeout(const SSL *ssl) {
  return SSL_DEFAULT_SESSION_TIMEOUT;
}

int SSL_renegotiate(SSL *ssl) {
  /* Caller-initiated renegotiation is not supported. */
  OPENSSL_PUT_ERROR(SSL, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
  return 0;
}

int SSL_renegotiate_pending(SSL *ssl) {
  return SSL_in_init(ssl) && ssl->s3->initial_handshake_complete;
}

int SSL_total_renegotiations(const SSL *ssl) {
  return ssl->s3->total_renegotiations;
}

size_t SSL_CTX_get_max_cert_list(const SSL_CTX *ctx) {
  return ctx->max_cert_list;
}

void SSL_CTX_set_max_cert_list(SSL_CTX *ctx, size_t max_cert_list) {
  if (max_cert_list > kMaxHandshakeSize) {
    max_cert_list = kMaxHandshakeSize;
  }
  ctx->max_cert_list = (uint32_t)max_cert_list;
}

size_t SSL_get_max_cert_list(const SSL *ssl) {
  return ssl->max_cert_list;
}

void SSL_set_max_cert_list(SSL *ssl, size_t max_cert_list) {
  if (max_cert_list > kMaxHandshakeSize) {
    max_cert_list = kMaxHandshakeSize;
  }
  ssl->max_cert_list = (uint32_t)max_cert_list;
}

int SSL_CTX_set_max_send_fragment(SSL_CTX *ctx, size_t max_send_fragment) {
  if (max_send_fragment < 512) {
    max_send_fragment = 512;
  }
  if (max_send_fragment > SSL3_RT_MAX_PLAIN_LENGTH) {
    max_send_fragment = SSL3_RT_MAX_PLAIN_LENGTH;
  }
  ctx->max_send_fragment = (uint16_t)max_send_fragment;

  return 1;
}

int SSL_set_max_send_fragment(SSL *ssl, size_t max_send_fragment) {
  if (max_send_fragment < 512) {
    max_send_fragment = 512;
  }
  if (max_send_fragment > SSL3_RT_MAX_PLAIN_LENGTH) {
    max_send_fragment = SSL3_RT_MAX_PLAIN_LENGTH;
  }
  ssl->max_send_fragment = (uint16_t)max_send_fragment;

  return 1;
}

int SSL_set_mtu(SSL *ssl, unsigned mtu) {
  if (!SSL_is_dtls(ssl) || mtu < dtls1_min_mtu()) {
    return 0;
  }
  ssl->d1->mtu = mtu;
  return 1;
}

int SSL_get_secure_renegotiation_support(const SSL *ssl) {
  return ssl->s3->send_connection_binding;
}

LHASH_OF(SSL_SESSION) *SSL_CTX_sessions(SSL_CTX *ctx) { return ctx->sessions; }

size_t SSL_CTX_sess_number(const SSL_CTX *ctx) {
  return lh_SSL_SESSION_num_items(ctx->sessions);
}

unsigned long SSL_CTX_sess_set_cache_size(SSL_CTX *ctx, unsigned long size) {
  unsigned long ret = ctx->session_cache_size;
  ctx->session_cache_size = size;
  return ret;
}

unsigned long SSL_CTX_sess_get_cache_size(const SSL_CTX *ctx) {
  return ctx->session_cache_size;
}

int SSL_CTX_set_session_cache_mode(SSL_CTX *ctx, int mode) {
  int ret = ctx->session_cache_mode;
  ctx->session_cache_mode = mode;
  return ret;
}

int SSL_CTX_get_session_cache_mode(const SSL_CTX *ctx) {
  return ctx->session_cache_mode;
}


int SSL_CTX_get_tlsext_ticket_keys(SSL_CTX *ctx, void *out, size_t len) {
  if (out == NULL) {
    return 48;
  }
  if (len != 48) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_TICKET_KEYS_LENGTH);
    return 0;
  }
  uint8_t *out_bytes = out;
  memcpy(out_bytes, ctx->tlsext_tick_key_name, 16);
  memcpy(out_bytes + 16, ctx->tlsext_tick_hmac_key, 16);
  memcpy(out_bytes + 32, ctx->tlsext_tick_aes_key, 16);
  return 1;
}

int SSL_CTX_set_tlsext_ticket_keys(SSL_CTX *ctx, const void *in, size_t len) {
  if (in == NULL) {
    return 48;
  }
  if (len != 48) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_TICKET_KEYS_LENGTH);
    return 0;
  }
  const uint8_t *in_bytes = in;
  memcpy(ctx->tlsext_tick_key_name, in_bytes, 16);
  memcpy(ctx->tlsext_tick_hmac_key, in_bytes + 16, 16);
  memcpy(ctx->tlsext_tick_aes_key, in_bytes + 32, 16);
  return 1;
}

int SSL_CTX_set_tlsext_ticket_key_cb(
    SSL_CTX *ctx, int (*callback)(SSL *ssl, uint8_t *key_name, uint8_t *iv,
                                  EVP_CIPHER_CTX *ctx, HMAC_CTX *hmac_ctx,
                                  int encrypt)) {
  ctx->tlsext_ticket_key_cb = callback;
  return 1;
}

int SSL_CTX_set1_curves(SSL_CTX *ctx, const int *curves, size_t curves_len) {
  return tls1_set_curves(&ctx->supported_group_list,
                         &ctx->supported_group_list_len, curves,
                         curves_len);
}

int SSL_set1_curves(SSL *ssl, const int *curves, size_t curves_len) {
  return tls1_set_curves(&ssl->supported_group_list,
                         &ssl->supported_group_list_len, curves,
                         curves_len);
}

int SSL_CTX_set1_curves_list(SSL_CTX *ctx, const char *curves) {
  return tls1_set_curves_list(&ctx->supported_group_list,
                              &ctx->supported_group_list_len, curves);
}

int SSL_set1_curves_list(SSL *ssl, const char *curves) {
  return tls1_set_curves_list(&ssl->supported_group_list,
                              &ssl->supported_group_list_len, curves);
}

uint16_t SSL_get_curve_id(const SSL *ssl) {
  /* TODO(davidben): This checks the wrong session if there is a renegotiation in
   * progress. */
  SSL_SESSION *session = SSL_get_session(ssl);
  if (session == NULL) {
    return 0;
  }

  return session->group_id;
}

int SSL_CTX_set_tmp_dh(SSL_CTX *ctx, const DH *dh) {
  DH_free(ctx->cert->dh_tmp);
  ctx->cert->dh_tmp = DHparams_dup(dh);
  if (ctx->cert->dh_tmp == NULL) {
    OPENSSL_PUT_ERROR(SSL, ERR_R_DH_LIB);
    return 0;
  }
  return 1;
}

int SSL_set_tmp_dh(SSL *ssl, const DH *dh) {
  DH_free(ssl->cert->dh_tmp);
  ssl->cert->dh_tmp = DHparams_dup(dh);
  if (ssl->cert->dh_tmp == NULL) {
    OPENSSL_PUT_ERROR(SSL, ERR_R_DH_LIB);
    return 0;
  }
  return 1;
}

STACK_OF(SSL_CIPHER) *SSL_get_ciphers(const SSL *ssl) {
  if (ssl == NULL) {
    return NULL;
  }

  const struct ssl_cipher_preference_list_st *prefs =
      ssl_get_cipher_preferences(ssl);
  if (prefs == NULL) {
    return NULL;
  }

  return prefs->ciphers;
}

const char *SSL_get_cipher_list(const SSL *ssl, int n) {
  const SSL_CIPHER *c;
  STACK_OF(SSL_CIPHER) *sk;

  if (ssl == NULL) {
    return NULL;
  }

  sk = SSL_get_ciphers(ssl);
  if (sk == NULL || n < 0 || (size_t)n >= sk_SSL_CIPHER_num(sk)) {
    return NULL;
  }

  c = sk_SSL_CIPHER_value(sk, n);
  if (c == NULL) {
    return NULL;
  }

  return c->name;
}

int SSL_CTX_set_cipher_list(SSL_CTX *ctx, const char *str) {
  STACK_OF(SSL_CIPHER) *cipher_list =
      ssl_create_cipher_list(ctx->method, &ctx->cipher_list, str);
  if (cipher_list == NULL) {
    return 0;
  }

  /* |ssl_create_cipher_list| may succeed but return an empty cipher list. */
  if (sk_SSL_CIPHER_num(cipher_list) == 0) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_NO_CIPHER_MATCH);
    return 0;
  }

  return 1;
}

int SSL_set_cipher_list(SSL *ssl, const char *str) {
  STACK_OF(SSL_CIPHER) *cipher_list =
      ssl_create_cipher_list(ssl->ctx->method, &ssl->cipher_list, str);
  if (cipher_list == NULL) {
    return 0;
  }

  /* |ssl_create_cipher_list| may succeed but return an empty cipher list. */
  if (sk_SSL_CIPHER_num(cipher_list) == 0) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_NO_CIPHER_MATCH);
    return 0;
  }

  return 1;
}

const char *SSL_get_servername(const SSL *ssl, const int type) {
  if (type != TLSEXT_NAMETYPE_host_name) {
    return NULL;
  }

  /* Historically, |SSL_get_servername| was also the configuration getter
   * corresponding to |SSL_set_tlsext_host_name|. */
  if (ssl->tlsext_hostname != NULL) {
    return ssl->tlsext_hostname;
  }

  /* During the handshake, report the handshake value. */
  if (ssl->s3->hs != NULL) {
    return ssl->s3->hs->hostname;
  }

  /* SSL_get_servername may also be called after the handshake to look up the
   * SNI value.
   *
   * TODO(davidben): This is almost unused. Can we remove it? */
  SSL_SESSION *session = SSL_get_session(ssl);
  if (session == NULL) {
    return NULL;
  }
  return session->tlsext_hostname;
}

int SSL_get_servername_type(const SSL *ssl) {
  SSL_SESSION *session = SSL_get_session(ssl);
  if (session == NULL || session->tlsext_hostname == NULL) {
    return -1;
  }
  return TLSEXT_NAMETYPE_host_name;
}

void SSL_CTX_enable_signed_cert_timestamps(SSL_CTX *ctx) {
  ctx->signed_cert_timestamps_enabled = 1;
}

int SSL_enable_signed_cert_timestamps(SSL *ssl) {
  ssl->signed_cert_timestamps_enabled = 1;
  return 1;
}

void SSL_CTX_enable_ocsp_stapling(SSL_CTX *ctx) {
  ctx->ocsp_stapling_enabled = 1;
}

int SSL_enable_ocsp_stapling(SSL *ssl) {
  ssl->ocsp_stapling_enabled = 1;
  return 1;
}

void SSL_get0_signed_cert_timestamp_list(const SSL *ssl, const uint8_t **out,
                                         size_t *out_len) {
  SSL_SESSION *session = SSL_get_session(ssl);

  *out_len = 0;
  *out = NULL;
  if (ssl->server || !session || !session->tlsext_signed_cert_timestamp_list) {
    return;
  }

  *out = session->tlsext_signed_cert_timestamp_list;
  *out_len = session->tlsext_signed_cert_timestamp_list_length;
}

void SSL_get0_ocsp_response(const SSL *ssl, const uint8_t **out,
                            size_t *out_len) {
  SSL_SESSION *session = SSL_get_session(ssl);

  *out_len = 0;
  *out = NULL;
  if (ssl->server || !session || !session->ocsp_response) {
    return;
  }
  *out = session->ocsp_response;
  *out_len = session->ocsp_response_length;
}

int SSL_CTX_set_signed_cert_timestamp_list(SSL_CTX *ctx, const uint8_t *list,
                                           size_t list_len) {
  CBS sct_list;
  CBS_init(&sct_list, list, list_len);
  if (!ssl_is_sct_list_valid(&sct_list)) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_SCT_LIST);
    return 0;
  }

  return CBS_stow(&sct_list, &ctx->signed_cert_timestamp_list,
                  &ctx->signed_cert_timestamp_list_length);
}

int SSL_CTX_set_ocsp_response(SSL_CTX *ctx, const uint8_t *response,
                              size_t response_len) {
  CRYPTO_BUFFER_free(ctx->ocsp_response);
  ctx->ocsp_response = CRYPTO_BUFFER_new(response, response_len, NULL);
  return ctx->ocsp_response != NULL;
}

int SSL_set_ocsp_response(SSL *ssl, const uint8_t *response,
                          size_t response_len) {
  CRYPTO_BUFFER_free(ssl->ocsp_response);
  ssl->ocsp_response = CRYPTO_BUFFER_new(response, response_len, NULL);
  return ssl->ocsp_response != NULL;
}

int SSL_set_tlsext_host_name(SSL *ssl, const char *name) {
  OPENSSL_free(ssl->tlsext_hostname);
  ssl->tlsext_hostname = NULL;

  if (name == NULL) {
    return 1;
  }

  size_t len = strlen(name);
  if (len == 0 || len > TLSEXT_MAXLEN_host_name) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_SSL3_EXT_INVALID_SERVERNAME);
    return 0;
  }
  ssl->tlsext_hostname = BUF_strdup(name);
  if (ssl->tlsext_hostname == NULL) {
    OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
    return 0;
  }
  return 1;
}

int SSL_CTX_set_tlsext_servername_callback(
    SSL_CTX *ctx, int (*callback)(SSL *ssl, int *out_alert, void *arg)) {
  ctx->tlsext_servername_callback = callback;
  return 1;
}

int SSL_CTX_set_tlsext_servername_arg(SSL_CTX *ctx, void *arg) {
  ctx->tlsext_servername_arg = arg;
  return 1;
}

int SSL_select_next_proto(uint8_t **out, uint8_t *out_len,
                          const uint8_t *server, unsigned server_len,
                          const uint8_t *client, unsigned client_len) {
  unsigned int i, j;
  const uint8_t *result;
  int status = OPENSSL_NPN_UNSUPPORTED;

  /* For each protocol in server preference order, see if we support it. */
  for (i = 0; i < server_len;) {
    for (j = 0; j < client_len;) {
      if (server[i] == client[j] &&
          memcmp(&server[i + 1], &client[j + 1], server[i]) == 0) {
        /* We found a match */
        result = &server[i];
        status = OPENSSL_NPN_NEGOTIATED;
        goto found;
      }
      j += client[j];
      j++;
    }
    i += server[i];
    i++;
  }

  /* There's no overlap between our protocols and the server's list. */
  result = client;
  status = OPENSSL_NPN_NO_OVERLAP;

found:
  *out = (uint8_t *)result + 1;
  *out_len = result[0];
  return status;
}

void SSL_get0_next_proto_negotiated(const SSL *ssl, const uint8_t **out_data,
                                    unsigned *out_len) {
  *out_data = ssl->s3->next_proto_negotiated;
  if (*out_data == NULL) {
    *out_len = 0;
  } else {
    *out_len = ssl->s3->next_proto_negotiated_len;
  }
}

void SSL_CTX_set_next_protos_advertised_cb(
    SSL_CTX *ctx,
    int (*cb)(SSL *ssl, const uint8_t **out, unsigned *out_len, void *arg),
    void *arg) {
  ctx->next_protos_advertised_cb = cb;
  ctx->next_protos_advertised_cb_arg = arg;
}

void SSL_CTX_set_next_proto_select_cb(
    SSL_CTX *ctx, int (*cb)(SSL *ssl, uint8_t **out, uint8_t *out_len,
                            const uint8_t *in, unsigned in_len, void *arg),
    void *arg) {
  ctx->next_proto_select_cb = cb;
  ctx->next_proto_select_cb_arg = arg;
}

int SSL_CTX_set_alpn_protos(SSL_CTX *ctx, const uint8_t *protos,
                            unsigned protos_len) {
  OPENSSL_free(ctx->alpn_client_proto_list);
  ctx->alpn_client_proto_list = BUF_memdup(protos, protos_len);
  if (!ctx->alpn_client_proto_list) {
    return 1;
  }
  ctx->alpn_client_proto_list_len = protos_len;

  return 0;
}

int SSL_set_alpn_protos(SSL *ssl, const uint8_t *protos, unsigned protos_len) {
  OPENSSL_free(ssl->alpn_client_proto_list);
  ssl->alpn_client_proto_list = BUF_memdup(protos, protos_len);
  if (!ssl->alpn_client_proto_list) {
    return 1;
  }
  ssl->alpn_client_proto_list_len = protos_len;

  return 0;
}

void SSL_CTX_set_alpn_select_cb(SSL_CTX *ctx,
                                int (*cb)(SSL *ssl, const uint8_t **out,
                                          uint8_t *out_len, const uint8_t *in,
                                          unsigned in_len, void *arg),
                                void *arg) {
  ctx->alpn_select_cb = cb;
  ctx->alpn_select_cb_arg = arg;
}

void SSL_get0_alpn_selected(const SSL *ssl, const uint8_t **out_data,
                            unsigned *out_len) {
  *out_data = NULL;
  if (ssl->s3) {
    *out_data = ssl->s3->alpn_selected;
  }
  if (*out_data == NULL) {
    *out_len = 0;
  } else {
    *out_len = ssl->s3->alpn_selected_len;
  }
}


void SSL_CTX_set_tls_channel_id_enabled(SSL_CTX *ctx, int enabled) {
  ctx->tlsext_channel_id_enabled = !!enabled;
}

int SSL_CTX_enable_tls_channel_id(SSL_CTX *ctx) {
  SSL_CTX_set_tls_channel_id_enabled(ctx, 1);
  return 1;
}

void SSL_set_tls_channel_id_enabled(SSL *ssl, int enabled) {
  ssl->tlsext_channel_id_enabled = !!enabled;
}

int SSL_enable_tls_channel_id(SSL *ssl) {
  SSL_set_tls_channel_id_enabled(ssl, 1);
  return 1;
}

static int is_p256_key(EVP_PKEY *private_key) {
  const EC_KEY *ec_key = EVP_PKEY_get0_EC_KEY(private_key);
  return ec_key != NULL &&
         EC_GROUP_get_curve_name(EC_KEY_get0_group(ec_key)) ==
             NID_X9_62_prime256v1;
}

int SSL_CTX_set1_tls_channel_id(SSL_CTX *ctx, EVP_PKEY *private_key) {
  if (!is_p256_key(private_key)) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_CHANNEL_ID_NOT_P256);
    return 0;
  }

  EVP_PKEY_free(ctx->tlsext_channel_id_private);
  EVP_PKEY_up_ref(private_key);
  ctx->tlsext_channel_id_private = private_key;
  ctx->tlsext_channel_id_enabled = 1;

  return 1;
}

int SSL_set1_tls_channel_id(SSL *ssl, EVP_PKEY *private_key) {
  if (!is_p256_key(private_key)) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_CHANNEL_ID_NOT_P256);
    return 0;
  }

  EVP_PKEY_free(ssl->tlsext_channel_id_private);
  EVP_PKEY_up_ref(private_key);
  ssl->tlsext_channel_id_private = private_key;
  ssl->tlsext_channel_id_enabled = 1;

  return 1;
}

size_t SSL_get_tls_channel_id(SSL *ssl, uint8_t *out, size_t max_out) {
  if (!ssl->s3->tlsext_channel_id_valid) {
    return 0;
  }
  memcpy(out, ssl->s3->tlsext_channel_id, (max_out < 64) ? max_out : 64);
  return 64;
}

void SSL_CTX_set_cert_verify_callback(SSL_CTX *ctx,
                                      int (*cb)(X509_STORE_CTX *store_ctx,
                                                void *arg),
                                      void *arg) {
  ctx->app_verify_callback = cb;
  ctx->app_verify_arg = arg;
}

void SSL_CTX_set_verify(SSL_CTX *ctx, int mode,
                        int (*cb)(int, X509_STORE_CTX *)) {
  ctx->verify_mode = mode;
  ctx->default_verify_callback = cb;
}

void SSL_CTX_set_verify_depth(SSL_CTX *ctx, int depth) {
  X509_VERIFY_PARAM_set_depth(ctx->param, depth);
}

size_t SSL_get0_certificate_types(SSL *ssl, const uint8_t **out_types) {
  if (ssl->server || ssl->s3->hs == NULL) {
    *out_types = NULL;
    return 0;
  }
  *out_types = ssl->s3->hs->certificate_types;
  return ssl->s3->hs->num_certificate_types;
}

void ssl_update_cache(SSL_HANDSHAKE *hs, int mode) {
  SSL *const ssl = hs->ssl;
  SSL_CTX *ctx = ssl->initial_ctx;
  /* Never cache sessions with empty session IDs. */
  if (ssl->s3->established_session->session_id_length == 0 ||
      (ctx->session_cache_mode & mode) != mode) {
    return;
  }

  /* Clients never use the internal session cache. */
  int use_internal_cache = ssl->server && !(ctx->session_cache_mode &
                                            SSL_SESS_CACHE_NO_INTERNAL_STORE);

  /* A client may see new sessions on abbreviated handshakes if the server
   * decides to renew the ticket. Once the handshake is completed, it should be
   * inserted into the cache. */
  if (ssl->s3->established_session != ssl->session ||
      (!ssl->server && hs->ticket_expected)) {
    if (use_internal_cache) {
      SSL_CTX_add_session(ctx, ssl->s3->established_session);
    }
    if (ctx->new_session_cb != NULL) {
      SSL_SESSION_up_ref(ssl->s3->established_session);
      if (!ctx->new_session_cb(ssl, ssl->s3->established_session)) {
        /* |new_session_cb|'s return value signals whether it took ownership. */
        SSL_SESSION_free(ssl->s3->established_session);
      }
    }
  }

  if (use_internal_cache &&
      !(ctx->session_cache_mode & SSL_SESS_CACHE_NO_AUTO_CLEAR)) {
    /* Automatically flush the internal session cache every 255 connections. */
    int flush_cache = 0;
    CRYPTO_MUTEX_lock_write(&ctx->lock);
    ctx->handshakes_since_cache_flush++;
    if (ctx->handshakes_since_cache_flush >= 255) {
      flush_cache = 1;
      ctx->handshakes_since_cache_flush = 0;
    }
    CRYPTO_MUTEX_unlock_write(&ctx->lock);

    if (flush_cache) {
      struct timeval now;
      ssl_get_current_time(ssl, &now);
      SSL_CTX_flush_sessions(ctx, (long)now.tv_sec);
    }
  }
}

static const char *ssl_get_version(int version) {
  switch (version) {
    /* Report TLS 1.3 draft version as TLS 1.3 in the public API. */
    case TLS1_3_DRAFT_VERSION:
      return "TLSv1.3";

    case TLS1_2_VERSION:
      return "TLSv1.2";

    case TLS1_1_VERSION:
      return "TLSv1.1";

    case TLS1_VERSION:
      return "TLSv1";

    case SSL3_VERSION:
      return "SSLv3";

    case DTLS1_VERSION:
      return "DTLSv1";

    case DTLS1_2_VERSION:
      return "DTLSv1.2";

    default:
      return "unknown";
  }
}

const char *SSL_get_version(const SSL *ssl) {
  return ssl_get_version(ssl->version);
}

const char *SSL_SESSION_get_version(const SSL_SESSION *session) {
  return ssl_get_version(session->ssl_version);
}

X509 *SSL_get_certificate(const SSL *ssl) {
  if (ssl->cert != NULL) {
    return ssl->cert->x509_leaf;
  }

  return NULL;
}

EVP_PKEY *SSL_get_privatekey(const SSL *ssl) {
  if (ssl->cert != NULL) {
    return ssl->cert->privatekey;
  }

  return NULL;
}

X509 *SSL_CTX_get0_certificate(const SSL_CTX *ctx) {
  if (ctx->cert != NULL) {
    return ctx->cert->x509_leaf;
  }

  return NULL;
}

EVP_PKEY *SSL_CTX_get0_privatekey(const SSL_CTX *ctx) {
  if (ctx->cert != NULL) {
    return ctx->cert->privatekey;
  }

  return NULL;
}

const SSL_CIPHER *SSL_get_current_cipher(const SSL *ssl) {
  if (ssl->s3->aead_write_ctx == NULL) {
    return NULL;
  }
  return ssl->s3->aead_write_ctx->cipher;
}

int SSL_session_reused(const SSL *ssl) {
  return ssl->s3->session_reused;
}

const COMP_METHOD *SSL_get_current_compression(SSL *ssl) { return NULL; }

const COMP_METHOD *SSL_get_current_expansion(SSL *ssl) { return NULL; }

int *SSL_get_server_tmp_key(SSL *ssl, EVP_PKEY **out_key) { return 0; }

int ssl_is_wbio_buffered(const SSL *ssl) {
  return ssl->bbio != NULL;
}

int ssl_init_wbio_buffer(SSL *ssl) {
  if (ssl->bbio != NULL) {
    /* Already buffered. */
    assert(ssl->bbio == ssl->wbio);
    return 1;
  }

  BIO *bbio = BIO_new(BIO_f_buffer());
  if (bbio == NULL ||
      !BIO_set_read_buffer_size(bbio, 1)) {
    BIO_free(bbio);
    return 0;
  }

  ssl->bbio = bbio;
  ssl->wbio = BIO_push(bbio, ssl->wbio);
  return 1;
}

void ssl_free_wbio_buffer(SSL *ssl) {
  if (ssl->bbio == NULL) {
    return;
  }

  assert(ssl->bbio == ssl->wbio);

  ssl->wbio = BIO_pop(ssl->wbio);
  BIO_free(ssl->bbio);
  ssl->bbio = NULL;
}

void SSL_CTX_set_quiet_shutdown(SSL_CTX *ctx, int mode) {
  ctx->quiet_shutdown = (mode != 0);
}

int SSL_CTX_get_quiet_shutdown(const SSL_CTX *ctx) {
  return ctx->quiet_shutdown;
}

void SSL_set_quiet_shutdown(SSL *ssl, int mode) {
  ssl->quiet_shutdown = (mode != 0);
}

int SSL_get_quiet_shutdown(const SSL *ssl) { return ssl->quiet_shutdown; }

void SSL_set_shutdown(SSL *ssl, int mode) {
  /* It is an error to clear any bits that have already been set. (We can't try
   * to get a second close_notify or send two.) */
  assert((SSL_get_shutdown(ssl) & mode) == SSL_get_shutdown(ssl));

  if (mode & SSL_RECEIVED_SHUTDOWN &&
      ssl->s3->recv_shutdown == ssl_shutdown_none) {
    ssl->s3->recv_shutdown = ssl_shutdown_close_notify;
  }

  if (mode & SSL_SENT_SHUTDOWN &&
      ssl->s3->send_shutdown == ssl_shutdown_none) {
    ssl->s3->send_shutdown = ssl_shutdown_close_notify;
  }
}

int SSL_get_shutdown(const SSL *ssl) {
  int ret = 0;
  if (ssl->s3->recv_shutdown != ssl_shutdown_none) {
    /* Historically, OpenSSL set |SSL_RECEIVED_SHUTDOWN| on both close_notify
     * and fatal alert. */
    ret |= SSL_RECEIVED_SHUTDOWN;
  }
  if (ssl->s3->send_shutdown == ssl_shutdown_close_notify) {
    /* Historically, OpenSSL set |SSL_SENT_SHUTDOWN| on only close_notify. */
    ret |= SSL_SENT_SHUTDOWN;
  }
  return ret;
}

int SSL_version(const SSL *ssl) {
  /* Report TLS 1.3 draft version as TLS 1.3 in the public API. */
  if (ssl->version == TLS1_3_DRAFT_VERSION) {
    return TLS1_3_VERSION;
  }

  return ssl->version;
}

SSL_CTX *SSL_get_SSL_CTX(const SSL *ssl) { return ssl->ctx; }

SSL_CTX *SSL_set_SSL_CTX(SSL *ssl, SSL_CTX *ctx) {
  if (ssl->ctx == ctx) {
    return ssl->ctx;
  }

  if (ctx == NULL) {
    ctx = ssl->initial_ctx;
  }

  ssl_cert_free(ssl->cert);
  ssl->cert = ssl_cert_dup(ctx->cert);

  CRYPTO_refcount_inc(&ctx->references);
  SSL_CTX_free(ssl->ctx); /* decrement reference count */
  ssl->ctx = ctx;

  ssl->sid_ctx_length = ctx->sid_ctx_length;
  assert(ssl->sid_ctx_length <= sizeof(ssl->sid_ctx));
  memcpy(ssl->sid_ctx, ctx->sid_ctx, sizeof(ssl->sid_ctx));

  return ssl->ctx;
}

int SSL_CTX_set_default_verify_paths(SSL_CTX *ctx) {
  return X509_STORE_set_default_paths(ctx->cert_store);
}

int SSL_CTX_load_verify_locations(SSL_CTX *ctx, const char *ca_file,
                                  const char *ca_dir) {
  return X509_STORE_load_locations(ctx->cert_store, ca_file, ca_dir);
}

void SSL_set_info_callback(SSL *ssl,
                           void (*cb)(const SSL *ssl, int type, int value)) {
  ssl->info_callback = cb;
}

void (*SSL_get_info_callback(const SSL *ssl))(const SSL *ssl, int type,
                                              int value) {
  return ssl->info_callback;
}

int SSL_state(const SSL *ssl) {
  if (ssl->s3->hs == NULL) {
    assert(ssl->s3->initial_handshake_complete);
    return SSL_ST_OK;
  }

  return ssl->s3->hs->state;
}

void SSL_set_state(SSL *ssl, int state) { }

char *SSL_get_shared_ciphers(const SSL *ssl, char *buf, int len) {
  if (len <= 0) {
    return NULL;
  }
  buf[0] = '\0';
  return buf;
}

void SSL_set_verify_result(SSL *ssl, long result) {
  if (result != X509_V_OK) {
    abort();
  }
}

long SSL_get_verify_result(const SSL *ssl) {
  SSL_SESSION *session = SSL_get_session(ssl);
  if (session == NULL) {
    return X509_V_ERR_INVALID_CALL;
  }
  return session->verify_result;
}

int SSL_get_ex_new_index(long argl, void *argp, CRYPTO_EX_unused *unused,
                         CRYPTO_EX_dup *dup_func, CRYPTO_EX_free *free_func) {
  int index;
  if (!CRYPTO_get_ex_new_index(&g_ex_data_class_ssl, &index, argl, argp,
                               dup_func, free_func)) {
    return -1;
  }
  return index;
}

int SSL_set_ex_data(SSL *ssl, int idx, void *arg) {
  return CRYPTO_set_ex_data(&ssl->ex_data, idx, arg);
}

void *SSL_get_ex_data(const SSL *ssl, int idx) {
  return CRYPTO_get_ex_data(&ssl->ex_data, idx);
}

int SSL_CTX_get_ex_new_index(long argl, void *argp, CRYPTO_EX_unused *unused,
                             CRYPTO_EX_dup *dup_func,
                             CRYPTO_EX_free *free_func) {
  int index;
  if (!CRYPTO_get_ex_new_index(&g_ex_data_class_ssl_ctx, &index, argl, argp,
                               dup_func, free_func)) {
    return -1;
  }
  return index;
}

int SSL_CTX_set_ex_data(SSL_CTX *ctx, int idx, void *arg) {
  return CRYPTO_set_ex_data(&ctx->ex_data, idx, arg);
}

void *SSL_CTX_get_ex_data(const SSL_CTX *ctx, int idx) {
  return CRYPTO_get_ex_data(&ctx->ex_data, idx);
}

X509_STORE *SSL_CTX_get_cert_store(const SSL_CTX *ctx) {
  return ctx->cert_store;
}

void SSL_CTX_set_cert_store(SSL_CTX *ctx, X509_STORE *store) {
  X509_STORE_free(ctx->cert_store);
  ctx->cert_store = store;
}

int SSL_want(const SSL *ssl) { return ssl->rwstate; }

void SSL_CTX_set_tmp_rsa_callback(SSL_CTX *ctx,
                                  RSA *(*cb)(SSL *ssl, int is_export,
                                             int keylength)) {
}

void SSL_set_tmp_rsa_callback(SSL *ssl, RSA *(*cb)(SSL *ssl, int is_export,
                                                   int keylength)) {
}

void SSL_CTX_set_tmp_dh_callback(SSL_CTX *ctx,
                                 DH *(*callback)(SSL *ssl, int is_export,
                                                 int keylength)) {
  ctx->cert->dh_tmp_cb = callback;
}

void SSL_set_tmp_dh_callback(SSL *ssl, DH *(*callback)(SSL *ssl, int is_export,
                                                       int keylength)) {
  ssl->cert->dh_tmp_cb = callback;
}

int SSL_CTX_use_psk_identity_hint(SSL_CTX *ctx, const char *identity_hint) {
  if (identity_hint != NULL && strlen(identity_hint) > PSK_MAX_IDENTITY_LEN) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_DATA_LENGTH_TOO_LONG);
    return 0;
  }

  OPENSSL_free(ctx->psk_identity_hint);

  if (identity_hint != NULL) {
    ctx->psk_identity_hint = BUF_strdup(identity_hint);
    if (ctx->psk_identity_hint == NULL) {
      return 0;
    }
  } else {
    ctx->psk_identity_hint = NULL;
  }

  return 1;
}

int SSL_use_psk_identity_hint(SSL *ssl, const char *identity_hint) {
  if (ssl == NULL) {
    return 0;
  }

  if (identity_hint != NULL && strlen(identity_hint) > PSK_MAX_IDENTITY_LEN) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_DATA_LENGTH_TOO_LONG);
    return 0;
  }

  /* Clear currently configured hint, if any. */
  OPENSSL_free(ssl->psk_identity_hint);
  ssl->psk_identity_hint = NULL;

  /* Treat the empty hint as not supplying one. Plain PSK makes it possible to
   * send either no hint (omit ServerKeyExchange) or an empty hint, while
   * ECDHE_PSK can only spell empty hint. Having different capabilities is odd,
   * so we interpret empty and missing as identical. */
  if (identity_hint != NULL && identity_hint[0] != '\0') {
    ssl->psk_identity_hint = BUF_strdup(identity_hint);
    if (ssl->psk_identity_hint == NULL) {
      return 0;
    }
  }

  return 1;
}

const char *SSL_get_psk_identity_hint(const SSL *ssl) {
  if (ssl == NULL) {
    return NULL;
  }
  return ssl->psk_identity_hint;
}

const char *SSL_get_psk_identity(const SSL *ssl) {
  if (ssl == NULL) {
    return NULL;
  }
  SSL_SESSION *session = SSL_get_session(ssl);
  if (session == NULL) {
    return NULL;
  }
  return session->psk_identity;
}

void SSL_set_psk_client_callback(
    SSL *ssl, unsigned (*cb)(SSL *ssl, const char *hint, char *identity,
                             unsigned max_identity_len, uint8_t *psk,
                             unsigned max_psk_len)) {
  ssl->psk_client_callback = cb;
}

void SSL_CTX_set_psk_client_callback(
    SSL_CTX *ctx, unsigned (*cb)(SSL *ssl, const char *hint, char *identity,
                                 unsigned max_identity_len, uint8_t *psk,
                                 unsigned max_psk_len)) {
  ctx->psk_client_callback = cb;
}

void SSL_set_psk_server_callback(
    SSL *ssl, unsigned (*cb)(SSL *ssl, const char *identity, uint8_t *psk,
                             unsigned max_psk_len)) {
  ssl->psk_server_callback = cb;
}

void SSL_CTX_set_psk_server_callback(
    SSL_CTX *ctx, unsigned (*cb)(SSL *ssl, const char *identity,
                                 uint8_t *psk, unsigned max_psk_len)) {
  ctx->psk_server_callback = cb;
}

void SSL_CTX_set_msg_callback(SSL_CTX *ctx,
                              void (*cb)(int write_p, int version,
                                         int content_type, const void *buf,
                                         size_t len, SSL *ssl, void *arg)) {
  ctx->msg_callback = cb;
}

void SSL_CTX_set_msg_callback_arg(SSL_CTX *ctx, void *arg) {
  ctx->msg_callback_arg = arg;
}

void SSL_set_msg_callback(SSL *ssl,
                          void (*cb)(int write_p, int version, int content_type,
                                     const void *buf, size_t len, SSL *ssl,
                                     void *arg)) {
  ssl->msg_callback = cb;
}

void SSL_set_msg_callback_arg(SSL *ssl, void *arg) {
  ssl->msg_callback_arg = arg;
}

void SSL_CTX_set_keylog_callback(SSL_CTX *ctx,
                                 void (*cb)(const SSL *ssl, const char *line)) {
  ctx->keylog_callback = cb;
}

void (*SSL_CTX_get_keylog_callback(const SSL_CTX *ctx))(const SSL *ssl,
                                                        const char *line) {
  return ctx->keylog_callback;
}

void SSL_CTX_set_current_time_cb(SSL_CTX *ctx,
                                 void (*cb)(const SSL *ssl,
                                            struct timeval *out_clock)) {
  ctx->current_time_cb = cb;
}

static int cbb_add_hex(CBB *cbb, const uint8_t *in, size_t in_len) {
  static const char hextable[] = "0123456789abcdef";
  uint8_t *out;

  if (!CBB_add_space(cbb, &out, in_len * 2)) {
    return 0;
  }

  for (size_t i = 0; i < in_len; i++) {
    *(out++) = (uint8_t)hextable[in[i] >> 4];
    *(out++) = (uint8_t)hextable[in[i] & 0xf];
  }

  return 1;
}

int ssl_log_rsa_client_key_exchange(const SSL *ssl,
                                    const uint8_t *encrypted_premaster,
                                    size_t encrypted_premaster_len,
                                    const uint8_t *premaster,
                                    size_t premaster_len) {
  if (ssl->ctx->keylog_callback == NULL) {
    return 1;
  }

  if (encrypted_premaster_len < 8) {
    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
    return 0;
  }

  CBB cbb;
  uint8_t *out;
  size_t out_len;
  if (!CBB_init(&cbb, 4 + 16 + 1 + premaster_len * 2 + 1) ||
      !CBB_add_bytes(&cbb, (const uint8_t *)"RSA ", 4) ||
      /* Only the first 8 bytes of the encrypted premaster secret are
       * logged. */
      !cbb_add_hex(&cbb, encrypted_premaster, 8) ||
      !CBB_add_bytes(&cbb, (const uint8_t *)" ", 1) ||
      !cbb_add_hex(&cbb, premaster, premaster_len) ||
      !CBB_add_u8(&cbb, 0 /* NUL */) ||
      !CBB_finish(&cbb, &out, &out_len)) {
    CBB_cleanup(&cbb);
    return 0;
  }

  ssl->ctx->keylog_callback(ssl, (const char *)out);
  OPENSSL_free(out);
  return 1;
}

int ssl_log_secret(const SSL *ssl, const char *label, const uint8_t *secret,
                   size_t secret_len) {
  if (ssl->ctx->keylog_callback == NULL) {
    return 1;
  }

  CBB cbb;
  uint8_t *out;
  size_t out_len;
  if (!CBB_init(&cbb, strlen(label) + 1 + SSL3_RANDOM_SIZE * 2 + 1 +
                          secret_len * 2 + 1) ||
      !CBB_add_bytes(&cbb, (const uint8_t *)label, strlen(label)) ||
      !CBB_add_bytes(&cbb, (const uint8_t *)" ", 1) ||
      !cbb_add_hex(&cbb, ssl->s3->client_random, SSL3_RANDOM_SIZE) ||
      !CBB_add_bytes(&cbb, (const uint8_t *)" ", 1) ||
      !cbb_add_hex(&cbb, secret, secret_len) ||
      !CBB_add_u8(&cbb, 0 /* NUL */) ||
      !CBB_finish(&cbb, &out, &out_len)) {
    CBB_cleanup(&cbb);
    return 0;
  }

  ssl->ctx->keylog_callback(ssl, (const char *)out);
  OPENSSL_free(out);
  return 1;
}

int SSL_is_init_finished(const SSL *ssl) {
  return SSL_state(ssl) == SSL_ST_OK;
}

int SSL_in_init(const SSL *ssl) {
  return (SSL_state(ssl) & SSL_ST_INIT) != 0;
}

int SSL_in_false_start(const SSL *ssl) {
  if (ssl->s3->hs == NULL) {
    return 0;
  }
  return ssl->s3->hs->in_false_start;
}

int SSL_cutthrough_complete(const SSL *ssl) {
  return SSL_in_false_start(ssl);
}

void SSL_get_structure_sizes(size_t *ssl_size, size_t *ssl_ctx_size,
                             size_t *ssl_session_size) {
  *ssl_size = sizeof(SSL);
  *ssl_ctx_size = sizeof(SSL_CTX);
  *ssl_session_size = sizeof(SSL_SESSION);
}

int ssl3_can_false_start(const SSL *ssl) {
  const SSL_CIPHER *const cipher = SSL_get_current_cipher(ssl);

  /* False Start only for TLS 1.2 with an ECDHE+AEAD cipher and ALPN or NPN. */
  return !SSL_is_dtls(ssl) &&
      SSL_version(ssl) == TLS1_2_VERSION &&
      (ssl->s3->alpn_selected != NULL ||
       ssl->s3->next_proto_negotiated != NULL) &&
      cipher != NULL &&
      cipher->algorithm_mkey == SSL_kECDHE &&
      cipher->algorithm_mac == SSL_AEAD;
}

const SSL3_ENC_METHOD *ssl3_get_enc_method(uint16_t version) {
  switch (version) {
    case SSL3_VERSION:
      return &SSLv3_enc_data;

    case TLS1_VERSION:
    case TLS1_1_VERSION:
    case TLS1_2_VERSION:
    case TLS1_3_VERSION:
      return &TLSv1_enc_data;

    default:
      return NULL;
  }
}

const struct {
  uint16_t version;
  uint32_t flag;
} kVersions[] = {
    {SSL3_VERSION, SSL_OP_NO_SSLv3},
    {TLS1_VERSION, SSL_OP_NO_TLSv1},
    {TLS1_1_VERSION, SSL_OP_NO_TLSv1_1},
    {TLS1_2_VERSION, SSL_OP_NO_TLSv1_2},
    {TLS1_3_VERSION, SSL_OP_NO_TLSv1_3},
};

static const size_t kVersionsLen = OPENSSL_ARRAY_SIZE(kVersions);

int ssl_get_version_range(const SSL *ssl, uint16_t *out_min_version,
                          uint16_t *out_max_version) {
  /* For historical reasons, |SSL_OP_NO_DTLSv1| aliases |SSL_OP_NO_TLSv1|, but
   * DTLS 1.0 should be mapped to TLS 1.1. */
  uint32_t options = ssl->options;
  if (SSL_is_dtls(ssl)) {
    options &= ~SSL_OP_NO_TLSv1_1;
    if (options & SSL_OP_NO_DTLSv1) {
      options |= SSL_OP_NO_TLSv1_1;
    }
  }

  uint16_t min_version = ssl->min_version;
  uint16_t max_version = ssl->max_version;

  /* Bound the range to only those implemented in this protocol. */
  if (min_version < ssl->method->min_version) {
    min_version = ssl->method->min_version;
  }
  if (max_version > ssl->method->max_version) {
    max_version = ssl->method->max_version;
  }

  /* OpenSSL's API for controlling versions entails blacklisting individual
   * protocols. This has two problems. First, on the client, the protocol can
   * only express a contiguous range of versions. Second, a library consumer
   * trying to set a maximum version cannot disable protocol versions that get
   * added in a future version of the library.
   *
   * To account for both of these, OpenSSL interprets the client-side bitmask
   * as a min/max range by picking the lowest contiguous non-empty range of
   * enabled protocols. Note that this means it is impossible to set a maximum
   * version of the higest supported TLS version in a future-proof way. */
  int any_enabled = 0;
  for (size_t i = 0; i < kVersionsLen; i++) {
    /* Only look at the versions already enabled. */
    if (min_version > kVersions[i].version) {
      continue;
    }
    if (max_version < kVersions[i].version) {
      break;
    }

    if (!(options & kVersions[i].flag)) {
      /* The minimum version is the first enabled version. */
      if (!any_enabled) {
        any_enabled = 1;
        min_version = kVersions[i].version;
      }
      continue;
    }

    /* If there is a disabled version after the first enabled one, all versions
     * after it are implicitly disabled. */
    if (any_enabled) {
      max_version = kVersions[i-1].version;
      break;
    }
  }

  if (!any_enabled) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SSL_VERSION);
    return 0;
  }

  *out_min_version = min_version;
  *out_max_version = max_version;
  return 1;
}

uint16_t ssl3_protocol_version(const SSL *ssl) {
  assert(ssl->s3->have_version);
  uint16_t version;
  if (!ssl->method->version_from_wire(&version, ssl->version)) {
    /* TODO(davidben): Use the internal version representation for ssl->version
     * and map to the public API representation at API boundaries. */
    assert(0);
    return 0;
  }

  return version;
}

int SSL_is_server(const SSL *ssl) { return ssl->server; }

int SSL_is_dtls(const SSL *ssl) { return ssl->method->is_dtls; }

void SSL_CTX_set_select_certificate_cb(SSL_CTX *ctx,
                                       int (*cb)(const SSL_CLIENT_HELLO *)) {
  ctx->select_certificate_cb = cb;
}

void SSL_CTX_set_dos_protection_cb(SSL_CTX *ctx,
                                   int (*cb)(const SSL_CLIENT_HELLO *)) {
  ctx->dos_protection_cb = cb;
}

void SSL_set_renegotiate_mode(SSL *ssl, enum ssl_renegotiate_mode_t mode) {
  ssl->renegotiate_mode = mode;
}

int SSL_get_ivs(const SSL *ssl, const uint8_t **out_read_iv,
                const uint8_t **out_write_iv, size_t *out_iv_len) {
  if (ssl->s3->aead_read_ctx == NULL || ssl->s3->aead_write_ctx == NULL) {
    return 0;
  }

  size_t write_iv_len;
  if (!EVP_AEAD_CTX_get_iv(&ssl->s3->aead_read_ctx->ctx, out_read_iv,
                           out_iv_len) ||
      !EVP_AEAD_CTX_get_iv(&ssl->s3->aead_write_ctx->ctx, out_write_iv,
                           &write_iv_len) ||
      *out_iv_len != write_iv_len) {
    return 0;
  }

  return 1;
}

static uint64_t be_to_u64(const uint8_t in[8]) {
  return (((uint64_t)in[0]) << 56) | (((uint64_t)in[1]) << 48) |
         (((uint64_t)in[2]) << 40) | (((uint64_t)in[3]) << 32) |
         (((uint64_t)in[4]) << 24) | (((uint64_t)in[5]) << 16) |
         (((uint64_t)in[6]) << 8) | ((uint64_t)in[7]);
}

uint64_t SSL_get_read_sequence(const SSL *ssl) {
  /* TODO(davidben): Internally represent sequence numbers as uint64_t. */
  if (SSL_is_dtls(ssl)) {
    /* max_seq_num already includes the epoch. */
    assert(ssl->d1->r_epoch == (ssl->d1->bitmap.max_seq_num >> 48));
    return ssl->d1->bitmap.max_seq_num;
  }
  return be_to_u64(ssl->s3->read_sequence);
}

uint64_t SSL_get_write_sequence(const SSL *ssl) {
  uint64_t ret = be_to_u64(ssl->s3->write_sequence);
  if (SSL_is_dtls(ssl)) {
    assert((ret >> 48) == 0);
    ret |= ((uint64_t)ssl->d1->w_epoch) << 48;
  }
  return ret;
}

uint16_t SSL_get_peer_signature_algorithm(const SSL *ssl) {
  /* TODO(davidben): This checks the wrong session if there is a renegotiation
   * in progress. */
  SSL_SESSION *session = SSL_get_session(ssl);
  if (session == NULL) {
    return 0;
  }

  return session->peer_signature_algorithm;
}

size_t SSL_get_client_random(const SSL *ssl, uint8_t *out, size_t max_out) {
  if (max_out == 0) {
    return sizeof(ssl->s3->client_random);
  }
  if (max_out > sizeof(ssl->s3->client_random)) {
    max_out = sizeof(ssl->s3->client_random);
  }
  memcpy(out, ssl->s3->client_random, max_out);
  return max_out;
}

size_t SSL_get_server_random(const SSL *ssl, uint8_t *out, size_t max_out) {
  if (max_out == 0) {
    return sizeof(ssl->s3->server_random);
  }
  if (max_out > sizeof(ssl->s3->server_random)) {
    max_out = sizeof(ssl->s3->server_random);
  }
  memcpy(out, ssl->s3->server_random, max_out);
  return max_out;
}

const SSL_CIPHER *SSL_get_pending_cipher(const SSL *ssl) {
  if (!SSL_in_init(ssl)) {
    return NULL;
  }
  return ssl->s3->tmp.new_cipher;
}

void SSL_set_retain_only_sha256_of_client_certs(SSL *ssl, int enabled) {
  ssl->retain_only_sha256_of_client_certs = !!enabled;
}

void SSL_CTX_set_retain_only_sha256_of_client_certs(SSL_CTX *ctx, int enabled) {
  ctx->retain_only_sha256_of_client_certs = !!enabled;
}

void SSL_CTX_set_grease_enabled(SSL_CTX *ctx, int enabled) {
  ctx->grease_enabled = !!enabled;
}

int SSL_clear(SSL *ssl) {
  /* In OpenSSL, reusing a client |SSL| with |SSL_clear| causes the previously
   * established session to be offered the next time around. wpa_supplicant
   * depends on this behavior, so emulate it. */
  SSL_SESSION *session = NULL;
  if (!ssl->server && ssl->s3->established_session != NULL) {
    session = ssl->s3->established_session;
    SSL_SESSION_up_ref(session);
  }

  /* TODO(davidben): Some state on |ssl| is reset both in |SSL_new| and
   * |SSL_clear| because it is per-connection state rather than configuration
   * state. Per-connection state should be on |ssl->s3| and |ssl->d1| so it is
   * naturally reset at the right points between |SSL_new|, |SSL_clear|, and
   * |ssl3_new|. */

  ssl->rwstate = SSL_NOTHING;

  BUF_MEM_free(ssl->init_buf);
  ssl->init_buf = NULL;
  ssl->init_msg = NULL;
  ssl->init_num = 0;

  /* The ssl->d1->mtu is simultaneously configuration (preserved across
   * clear) and connection-specific state (gets reset).
   *
   * TODO(davidben): Avoid this. */
  unsigned mtu = 0;
  if (ssl->d1 != NULL) {
    mtu = ssl->d1->mtu;
  }

  ssl->method->ssl_free(ssl);
  if (!ssl->method->ssl_new(ssl)) {
    SSL_SESSION_free(session);
    return 0;
  }

  if (SSL_is_dtls(ssl) && (SSL_get_options(ssl) & SSL_OP_NO_QUERY_MTU)) {
    ssl->d1->mtu = mtu;
  }

  if (session != NULL) {
    SSL_set_session(ssl, session);
    SSL_SESSION_free(session);
  }

  return 1;
}

void ssl_do_info_callback(const SSL *ssl, int type, int value) {
  void (*cb)(const SSL *ssl, int type, int value) = NULL;
  if (ssl->info_callback != NULL) {
    cb = ssl->info_callback;
  } else if (ssl->ctx->info_callback != NULL) {
    cb = ssl->ctx->info_callback;
  }

  if (cb != NULL) {
    cb(ssl, type, value);
  }
}

void ssl_do_msg_callback(SSL *ssl, int is_write, int content_type,
                         const void *buf, size_t len) {
  if (ssl->msg_callback == NULL) {
    return;
  }

  /* |version| is zero when calling for |SSL3_RT_HEADER| and |SSL2_VERSION| for
   * a V2ClientHello. */
  int version;
  switch (content_type) {
    case 0:
      /* V2ClientHello */
      version = SSL2_VERSION;
      break;
    case SSL3_RT_HEADER:
      version = 0;
      break;
    default:
      version = SSL_version(ssl);
  }

  ssl->msg_callback(is_write, version, content_type, buf, len, ssl,
                    ssl->msg_callback_arg);
}

int SSL_CTX_sess_connect(const SSL_CTX *ctx) { return 0; }
int SSL_CTX_sess_connect_good(const SSL_CTX *ctx) { return 0; }
int SSL_CTX_sess_connect_renegotiate(const SSL_CTX *ctx) { return 0; }
int SSL_CTX_sess_accept(const SSL_CTX *ctx) { return 0; }
int SSL_CTX_sess_accept_renegotiate(const SSL_CTX *ctx) { return 0; }
int SSL_CTX_sess_accept_good(const SSL_CTX *ctx) { return 0; }
int SSL_CTX_sess_hits(const SSL_CTX *ctx) { return 0; }
int SSL_CTX_sess_cb_hits(const SSL_CTX *ctx) { return 0; }
int SSL_CTX_sess_misses(const SSL_CTX *ctx) { return 0; }
int SSL_CTX_sess_timeouts(const SSL_CTX *ctx) { return 0; }
int SSL_CTX_sess_cache_full(const SSL_CTX *ctx) { return 0; }

int SSL_num_renegotiations(const SSL *ssl) {
  return SSL_total_renegotiations(ssl);
}

int SSL_CTX_need_tmp_RSA(const SSL_CTX *ctx) { return 0; }
int SSL_need_tmp_RSA(const SSL *ssl) { return 0; }
int SSL_CTX_set_tmp_rsa(SSL_CTX *ctx, const RSA *rsa) { return 1; }
int SSL_set_tmp_rsa(SSL *ssl, const RSA *rsa) { return 1; }
void ERR_load_SSL_strings(void) {}
void SSL_load_error_strings(void) {}
int SSL_cache_hit(SSL *ssl) { return SSL_session_reused(ssl); }

int SSL_CTX_set_tmp_ecdh(SSL_CTX *ctx, const EC_KEY *ec_key) {
  if (ec_key == NULL || EC_KEY_get0_group(ec_key) == NULL) {
    OPENSSL_PUT_ERROR(SSL, ERR_R_PASSED_NULL_PARAMETER);
    return 0;
  }
  int nid = EC_GROUP_get_curve_name(EC_KEY_get0_group(ec_key));
  return SSL_CTX_set1_curves(ctx, &nid, 1);
}

int SSL_set_tmp_ecdh(SSL *ssl, const EC_KEY *ec_key) {
  if (ec_key == NULL || EC_KEY_get0_group(ec_key) == NULL) {
    OPENSSL_PUT_ERROR(SSL, ERR_R_PASSED_NULL_PARAMETER);
    return 0;
  }
  int nid = EC_GROUP_get_curve_name(EC_KEY_get0_group(ec_key));
  return SSL_set1_curves(ssl, &nid, 1);
}

void ssl_get_current_time(const SSL *ssl, struct timeval *out_clock) {
  if (ssl->ctx->current_time_cb != NULL) {
    ssl->ctx->current_time_cb(ssl, out_clock);
    return;
  }

#if defined(BORINGSSL_UNSAFE_DETERMINISTIC_MODE)
  out_clock->tv_sec = 1234;
  out_clock->tv_usec = 1234;
#elif defined(OPENSSL_WINDOWS)
  struct _timeb time;
  _ftime(&time);
  out_clock->tv_sec = time.time;
  out_clock->tv_usec = time.millitm * 1000;
#else
  gettimeofday(out_clock, NULL);
#endif
}

int SSL_CTX_set_min_version(SSL_CTX *ctx, uint16_t version) {
  return SSL_CTX_set_min_proto_version(ctx, version);
}

int SSL_CTX_set_max_version(SSL_CTX *ctx, uint16_t version) {
  return SSL_CTX_set_max_proto_version(ctx, version);
}

int SSL_set_min_version(SSL *ssl, uint16_t version) {
  return SSL_set_min_proto_version(ssl, version);
}

int SSL_set_max_version(SSL *ssl, uint16_t version) {
  return SSL_set_max_proto_version(ssl, version);
}