ssl/tls13_both.c - boringssl - Git at Google

 /* Copyright (c) 2016, Google Inc.
  *
  * Permission to use, copy, modify, and/or distribute this software for any
  * purpose with or without fee is hereby granted, provided that the above
  * copyright notice and this permission notice appear in all copies.
  *
  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
  * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */

 #include <openssl/ssl.h>

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

 #include <openssl/bytestring.h>
 #include <openssl/err.h>
 #include <openssl/hkdf.h>
 #include <openssl/mem.h>
 #include <openssl/stack.h>
 #include <openssl/x509.h>
 #include <openssl/x509v3.h>

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


 /* kMaxKeyUpdates is the number of consecutive KeyUpdates that will be
  * processed. Without this limit an attacker could force unbounded processing
  * without being able to return application data. */
 static const uint8_t kMaxKeyUpdates = 32;

 int tls13_handshake(SSL_HANDSHAKE *hs) {
   SSL *const ssl = hs->ssl;
   for (;;) {
     /* Resolve the operation the handshake was waiting on. */
     switch (hs->wait) {
       case ssl_hs_error:
         OPENSSL_PUT_ERROR(SSL, SSL_R_SSL_HANDSHAKE_FAILURE);
         return -1;

       case ssl_hs_flush:
       case ssl_hs_flush_and_read_message: {
         int ret = BIO_flush(ssl->wbio);
         if (ret <= 0) {
           ssl->rwstate = SSL_WRITING;
           return ret;
         }
         if (hs->wait != ssl_hs_flush_and_read_message) {
           break;
         }
         ssl->method->expect_flight(ssl);
         hs->wait = ssl_hs_read_message;
         /* Fall-through. */
       }

       case ssl_hs_read_message: {
         int ret = ssl->method->ssl_get_message(ssl, -1, ssl_dont_hash_message);
         if (ret <= 0) {
           return ret;
         }
         break;
       }

       case ssl_hs_write_message: {
         int ret = ssl->method->write_message(ssl);
         if (ret <= 0) {
           return ret;
         }
         break;
       }

       case ssl_hs_x509_lookup:
         ssl->rwstate = SSL_X509_LOOKUP;
         hs->wait = ssl_hs_ok;
         return -1;

       case ssl_hs_channel_id_lookup:
         ssl->rwstate = SSL_CHANNEL_ID_LOOKUP;
         hs->wait = ssl_hs_ok;
         return -1;

       case ssl_hs_private_key_operation:
         ssl->rwstate = SSL_PRIVATE_KEY_OPERATION;
         hs->wait = ssl_hs_ok;
         return -1;

       case ssl_hs_ok:
         break;
     }

     /* Run the state machine again. */
     hs->wait = hs->do_tls13_handshake(hs);
     if (hs->wait == ssl_hs_error) {
       /* Don't loop around to avoid a stray |SSL_R_SSL_HANDSHAKE_FAILURE| the
        * first time around. */
       return -1;
     }
     if (hs->wait == ssl_hs_ok) {
       /* The handshake has completed. */
       return 1;
     }

     /* Otherwise, loop to the beginning and resolve what was blocking the
      * handshake. */
   }
 }

 int tls13_get_cert_verify_signature_input(
     SSL *ssl, uint8_t **out, size_t *out_len,
     enum ssl_cert_verify_context_t cert_verify_context) {
   CBB cbb;
   if (!CBB_init(&cbb, 64 + 33 + 1 + 2 * EVP_MAX_MD_SIZE)) {
     goto err;
   }

   for (size_t i = 0; i < 64; i++) {
     if (!CBB_add_u8(&cbb, 0x20)) {
       goto err;
     }
   }

   const uint8_t *context;
   size_t context_len;
   if (cert_verify_context == ssl_cert_verify_server) {
     /* Include the NUL byte. */
     static const char kContext[] = "TLS 1.3, server CertificateVerify";
     context = (const uint8_t *)kContext;
     context_len = sizeof(kContext);
   } else if (cert_verify_context == ssl_cert_verify_client) {
     static const char kContext[] = "TLS 1.3, client CertificateVerify";
     context = (const uint8_t *)kContext;
     context_len = sizeof(kContext);
   } else if (cert_verify_context == ssl_cert_verify_channel_id) {
     static const char kContext[] = "TLS 1.3, Channel ID";
     context = (const uint8_t *)kContext;
     context_len = sizeof(kContext);
   } else {
     goto err;
   }

   if (!CBB_add_bytes(&cbb, context, context_len)) {
     goto err;
   }

   uint8_t context_hash[EVP_MAX_MD_SIZE];
   size_t context_hash_len;
   if (!tls13_get_context_hash(ssl, context_hash, &context_hash_len) ||
       !CBB_add_bytes(&cbb, context_hash, context_hash_len) ||
       !CBB_finish(&cbb, out, out_len)) {
     goto err;
   }

   return 1;

 err:
   OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
   CBB_cleanup(&cbb);
   return 0;
 }

 int tls13_process_certificate(SSL_HANDSHAKE *hs, int allow_anonymous) {
   SSL *const ssl = hs->ssl;
   CBS cbs, context, certificate_list;
   CBS_init(&cbs, ssl->init_msg, ssl->init_num);
   if (!CBS_get_u8_length_prefixed(&cbs, &context) ||
       CBS_len(&context) != 0) {
     ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
     return 0;
   }

   const int retain_sha256 =
       ssl->server && ssl->retain_only_sha256_of_client_certs;
   int ret = 0;

   EVP_PKEY *pkey = NULL;
   STACK_OF(CRYPTO_BUFFER) *certs = sk_CRYPTO_BUFFER_new_null();
   if (certs == NULL) {
     ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
     OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
     goto err;
   }

   if (!CBS_get_u24_length_prefixed(&cbs, &certificate_list)) {
     ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
     goto err;
   }

   while (CBS_len(&certificate_list) > 0) {
     CBS certificate, extensions;
     if (!CBS_get_u24_length_prefixed(&certificate_list, &certificate) ||
         !CBS_get_u16_length_prefixed(&certificate_list, &extensions) ||
         CBS_len(&certificate) == 0) {
       ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
       OPENSSL_PUT_ERROR(SSL, SSL_R_CERT_LENGTH_MISMATCH);
       goto err;
     }

     if (sk_CRYPTO_BUFFER_num(certs) == 0) {
       pkey = ssl_cert_parse_pubkey(&certificate);
       if (pkey == NULL) {
         ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
         OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
         goto err;
       }
       /* TLS 1.3 always uses certificate keys for signing thus the correct
        * keyUsage is enforced. */
       if (!ssl_cert_check_digital_signature_key_usage(&certificate)) {
         ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
         goto err;
       }

       if (retain_sha256) {
         /* Retain the hash of the leaf certificate if requested. */
         SHA256(CBS_data(&certificate), CBS_len(&certificate),
                ssl->s3->new_session->peer_sha256);
       }
     }

     CRYPTO_BUFFER *buf =
         CRYPTO_BUFFER_new_from_CBS(&certificate, ssl->ctx->pool);
     if (buf == NULL ||
         !sk_CRYPTO_BUFFER_push(certs, buf)) {
       CRYPTO_BUFFER_free(buf);
       ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
       OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
       goto err;
     }

     /* Parse out the extensions. */
     int have_status_request = 0, have_sct = 0;
     CBS status_request, sct;
     const SSL_EXTENSION_TYPE ext_types[] = {
         {TLSEXT_TYPE_status_request, &have_status_request, &status_request},
         {TLSEXT_TYPE_certificate_timestamp, &have_sct, &sct},
     };

     uint8_t alert;
     if (!ssl_parse_extensions(&extensions, &alert, ext_types,
                               OPENSSL_ARRAY_SIZE(ext_types),
                               0 /* reject unknown */)) {
       ssl3_send_alert(ssl, SSL3_AL_FATAL, alert);
       goto err;
     }

     /* All Certificate extensions are parsed, but only the leaf extensions are
      * stored. */
     if (have_status_request) {
       if (ssl->server || !ssl->ocsp_stapling_enabled) {
         OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
         ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNSUPPORTED_EXTENSION);
         goto err;
       }

       uint8_t status_type;
       CBS ocsp_response;
       if (!CBS_get_u8(&status_request, &status_type) ||
           status_type != TLSEXT_STATUSTYPE_ocsp ||
           !CBS_get_u24_length_prefixed(&status_request, &ocsp_response) ||
           CBS_len(&ocsp_response) == 0 ||
           CBS_len(&status_request) != 0) {
         ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
         goto err;
       }

       if (sk_CRYPTO_BUFFER_num(certs) == 1 &&
           !CBS_stow(&ocsp_response, &ssl->s3->new_session->ocsp_response,
                     &ssl->s3->new_session->ocsp_response_length)) {
         ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
         goto err;
       }
     }

     if (have_sct) {
       if (ssl->server || !ssl->signed_cert_timestamps_enabled) {
         OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
         ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNSUPPORTED_EXTENSION);
         goto err;
       }

       if (!ssl_is_sct_list_valid(&sct)) {
         OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION);
         ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
         goto err;
       }

       if (sk_CRYPTO_BUFFER_num(certs) == 1 &&
           !CBS_stow(&sct,
                     &ssl->s3->new_session->tlsext_signed_cert_timestamp_list,
                     &ssl->s3->new_session
                          ->tlsext_signed_cert_timestamp_list_length)) {
         ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
         goto err;
       }
     }
   }

   if (CBS_len(&cbs) != 0) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
     ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
     goto err;
   }

   EVP_PKEY_free(hs->peer_pubkey);
   hs->peer_pubkey = pkey;
   pkey = NULL;

   sk_CRYPTO_BUFFER_pop_free(ssl->s3->new_session->certs, CRYPTO_BUFFER_free);
   ssl->s3->new_session->certs = certs;
   certs = NULL;

   if (!ssl_session_x509_cache_objects(ssl->s3->new_session)) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
     ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
     goto err;
   }

   if (sk_CRYPTO_BUFFER_num(ssl->s3->new_session->certs) == 0) {
     if (!allow_anonymous) {
       OPENSSL_PUT_ERROR(SSL, SSL_R_PEER_DID_NOT_RETURN_A_CERTIFICATE);
       ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_CERTIFICATE_REQUIRED);
       goto err;
     }

     /* OpenSSL returns X509_V_OK when no certificates are requested. This is
      * classed by them as a bug, but it's assumed by at least NGINX. */
     ssl->s3->new_session->verify_result = X509_V_OK;

     /* No certificate, so nothing more to do. */
     ret = 1;
     goto err;
   }

   ssl->s3->new_session->peer_sha256_valid = retain_sha256;

   if (!ssl_verify_cert_chain(ssl, &ssl->s3->new_session->verify_result,
                              ssl->s3->new_session->x509_chain)) {
     goto err;
   }

   ret = 1;

 err:
   sk_CRYPTO_BUFFER_pop_free(certs, CRYPTO_BUFFER_free);
   EVP_PKEY_free(pkey);
   return ret;
 }

 int tls13_process_certificate_verify(SSL_HANDSHAKE *hs) {
   SSL *const ssl = hs->ssl;
   int ret = 0;
   uint8_t *msg = NULL;
   size_t msg_len;

   if (hs->peer_pubkey == NULL) {
     goto err;
   }

   CBS cbs, signature;
   uint16_t signature_algorithm;
   CBS_init(&cbs, ssl->init_msg, ssl->init_num);
   if (!CBS_get_u16(&cbs, &signature_algorithm) ||
       !CBS_get_u16_length_prefixed(&cbs, &signature) ||
       CBS_len(&cbs) != 0) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
     ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
     goto err;
   }

   int al;
   if (!tls12_check_peer_sigalg(ssl, &al, signature_algorithm)) {
     ssl3_send_alert(ssl, SSL3_AL_FATAL, al);
     goto err;
   }
   ssl->s3->new_session->peer_signature_algorithm = signature_algorithm;

   if (!tls13_get_cert_verify_signature_input(
           ssl, &msg, &msg_len,
           ssl->server ? ssl_cert_verify_client : ssl_cert_verify_server)) {
     ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
     goto err;
   }

   int sig_ok =
       ssl_public_key_verify(ssl, CBS_data(&signature), CBS_len(&signature),
                             signature_algorithm, hs->peer_pubkey, msg, msg_len);
 #if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
   sig_ok = 1;
   ERR_clear_error();
 #endif
   if (!sig_ok) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SIGNATURE);
     ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
     goto err;
   }

   ret = 1;

 err:
   OPENSSL_free(msg);
   return ret;
 }

 int tls13_check_message_type(SSL *ssl, int type) {
   if (ssl->s3->tmp.message_type != type) {
     ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
     OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_MESSAGE);
     ERR_add_error_dataf("got type %d, wanted type %d",
                         ssl->s3->tmp.message_type, type);
     return 0;
   }

   return 1;
 }

 int tls13_process_finished(SSL_HANDSHAKE *hs) {
   SSL *const ssl = hs->ssl;
   uint8_t verify_data[EVP_MAX_MD_SIZE];
   size_t verify_data_len;
   if (!tls13_finished_mac(hs, verify_data, &verify_data_len, !ssl->server)) {
     return 0;
   }

   int finished_ok =
       ssl->init_num == verify_data_len &&
       CRYPTO_memcmp(verify_data, ssl->init_msg, verify_data_len) == 0;
 #if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
   finished_ok = 1;
 #endif
   if (!finished_ok) {
     ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
     OPENSSL_PUT_ERROR(SSL, SSL_R_DIGEST_CHECK_FAILED);
     return 0;
   }

   return 1;
 }

 int tls13_prepare_certificate(SSL_HANDSHAKE *hs) {
   SSL *const ssl = hs->ssl;
   CBB cbb, body, certificate_list;
   if (!ssl->method->init_message(ssl, &cbb, &body, SSL3_MT_CERTIFICATE) ||
       /* The request context is always empty in the handshake. */
       !CBB_add_u8(&body, 0) ||
       !CBB_add_u24_length_prefixed(&body, &certificate_list)) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
     goto err;
   }

   if (!ssl_has_certificate(ssl)) {
     if (!ssl_complete_message(ssl, &cbb)) {
       goto err;
     }

     return 1;
   }

   CERT *cert = ssl->cert;
   CBB leaf, extensions;
   if (!CBB_add_u24_length_prefixed(&certificate_list, &leaf) ||
       !ssl_add_cert_to_cbb(&leaf, cert->x509_leaf) ||
       !CBB_add_u16_length_prefixed(&certificate_list, &extensions)) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
     goto err;
   }

   if (hs->scts_requested &&
       ssl->ctx->signed_cert_timestamp_list_length != 0) {
     CBB contents;
     if (!CBB_add_u16(&extensions, TLSEXT_TYPE_certificate_timestamp) ||
         !CBB_add_u16_length_prefixed(&extensions, &contents) ||
         !CBB_add_bytes(&contents, ssl->ctx->signed_cert_timestamp_list,
                        ssl->ctx->signed_cert_timestamp_list_length) ||
         !CBB_flush(&extensions)) {
       OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
       goto err;
     }
   }

   if (hs->ocsp_stapling_requested &&
       ssl->ocsp_response != NULL) {
     CBB contents, ocsp_response;
     if (!CBB_add_u16(&extensions, TLSEXT_TYPE_status_request) ||
         !CBB_add_u16_length_prefixed(&extensions, &contents) ||
         !CBB_add_u8(&contents, TLSEXT_STATUSTYPE_ocsp) ||
         !CBB_add_u24_length_prefixed(&contents, &ocsp_response) ||
         !CBB_add_bytes(&ocsp_response, CRYPTO_BUFFER_data(ssl->ocsp_response),
                        CRYPTO_BUFFER_len(ssl->ocsp_response)) ||
         !CBB_flush(&extensions)) {
       OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
       goto err;
     }
   }

   for (size_t i = 0; i < sk_X509_num(cert->x509_chain); i++) {
     CBB child;
     if (!CBB_add_u24_length_prefixed(&certificate_list, &child) ||
         !ssl_add_cert_to_cbb(&child, sk_X509_value(cert->x509_chain, i)) ||
         !CBB_add_u16(&certificate_list, 0 /* no extensions */)) {
       OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
       goto err;
     }
   }

   if (!ssl_complete_message(ssl, &cbb)) {
     goto err;
   }

   return 1;

 err:
   CBB_cleanup(&cbb);
   return 0;
 }

 enum ssl_private_key_result_t tls13_prepare_certificate_verify(
     SSL_HANDSHAKE *hs, int is_first_run) {
   SSL *const ssl = hs->ssl;
   enum ssl_private_key_result_t ret = ssl_private_key_failure;
   uint8_t *msg = NULL;
   size_t msg_len;
   CBB cbb, body;
   CBB_zero(&cbb);

   uint16_t signature_algorithm;
   if (!tls1_choose_signature_algorithm(hs, &signature_algorithm)) {
     goto err;
   }
   if (!ssl->method->init_message(ssl, &cbb, &body,
                                  SSL3_MT_CERTIFICATE_VERIFY) ||
       !CBB_add_u16(&body, signature_algorithm)) {
     OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
     goto err;
   }

   /* Sign the digest. */
   CBB child;
   const size_t max_sig_len = ssl_private_key_max_signature_len(ssl);
   uint8_t *sig;
   size_t sig_len;
   if (!CBB_add_u16_length_prefixed(&body, &child) ||
       !CBB_reserve(&child, &sig, max_sig_len)) {
     ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
     goto err;
   }

   enum ssl_private_key_result_t sign_result;
   if (is_first_run) {
     if (!tls13_get_cert_verify_signature_input(
             ssl, &msg, &msg_len,
             ssl->server ? ssl_cert_verify_server : ssl_cert_verify_client)) {
       ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
       goto err;
     }
     sign_result = ssl_private_key_sign(ssl, sig, &sig_len, max_sig_len,
                                        signature_algorithm, msg, msg_len);
   } else {
     sign_result = ssl_private_key_complete(ssl, sig, &sig_len, max_sig_len);
   }

   if (sign_result != ssl_private_key_success) {
     ret = sign_result;
     goto err;
   }

   if (!CBB_did_write(&child, sig_len) ||
       !ssl_complete_message(ssl, &cbb)) {
     goto err;
   }

   ret = ssl_private_key_success;

 err:
   CBB_cleanup(&cbb);
   OPENSSL_free(msg);
   return ret;
 }

 int tls13_prepare_finished(SSL_HANDSHAKE *hs) {
   SSL *const ssl = hs->ssl;
   size_t verify_data_len;
   uint8_t verify_data[EVP_MAX_MD_SIZE];

   if (!tls13_finished_mac(hs, verify_data, &verify_data_len, ssl->server)) {
     ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
     OPENSSL_PUT_ERROR(SSL, SSL_R_DIGEST_CHECK_FAILED);
     return 0;
   }

   CBB cbb, body;
   if (!ssl->method->init_message(ssl, &cbb, &body, SSL3_MT_FINISHED) ||
       !CBB_add_bytes(&body, verify_data, verify_data_len) ||
       !ssl_complete_message(ssl, &cbb)) {
     CBB_cleanup(&cbb);
     return 0;
   }

   return 1;
 }

 static int tls13_receive_key_update(SSL *ssl) {
   CBS cbs;
   uint8_t key_update_request;
   CBS_init(&cbs, ssl->init_msg, ssl->init_num);
   if (!CBS_get_u8(&cbs, &key_update_request) ||
       CBS_len(&cbs) != 0 ||
       (key_update_request != SSL_KEY_UPDATE_NOT_REQUESTED &&
        key_update_request != SSL_KEY_UPDATE_REQUESTED)) {
     OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
     ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
     return 0;
   }

   /* TODO(svaldez): Send KeyUpdate if |key_update_request| is
    * |SSL_KEY_UPDATE_REQUESTED|. */
   return tls13_rotate_traffic_key(ssl, evp_aead_open);
 }

 int tls13_post_handshake(SSL *ssl) {
   if (ssl->s3->tmp.message_type == SSL3_MT_KEY_UPDATE) {
     ssl->s3->key_update_count++;
     if (ssl->s3->key_update_count > kMaxKeyUpdates) {
       OPENSSL_PUT_ERROR(SSL, SSL_R_TOO_MANY_KEY_UPDATES);
       ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
       return 0;
     }

     return tls13_receive_key_update(ssl);
   }

   ssl->s3->key_update_count = 0;

   if (ssl->s3->tmp.message_type == SSL3_MT_NEW_SESSION_TICKET &&
       !ssl->server) {
     return tls13_process_new_session_ticket(ssl);
   }

   // TODO(svaldez): Handle post-handshake authentication.

   ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
   OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_MESSAGE);
   return 0;
 }
	/* Copyright (c) 2016, Google Inc.
	*
	* Permission to use, copy, modify, and/or distribute this software for any
	* purpose with or without fee is hereby granted, provided that the above
	* copyright notice and this permission notice appear in all copies.
	*
	* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
	* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
	* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
	* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */

	#include <openssl/ssl.h>

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

	#include <openssl/bytestring.h>
	#include <openssl/err.h>
	#include <openssl/hkdf.h>
	#include <openssl/mem.h>
	#include <openssl/stack.h>
	#include <openssl/x509.h>
	#include <openssl/x509v3.h>

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


	/* kMaxKeyUpdates is the number of consecutive KeyUpdates that will be
	* processed. Without this limit an attacker could force unbounded processing
	* without being able to return application data. */
	static const uint8_t kMaxKeyUpdates = 32;

	int tls13_handshake(SSL_HANDSHAKE *hs) {
	SSL *const ssl = hs->ssl;
	for (;;) {
	/* Resolve the operation the handshake was waiting on. */
	switch (hs->wait) {
	case ssl_hs_error:
	OPENSSL_PUT_ERROR(SSL, SSL_R_SSL_HANDSHAKE_FAILURE);
	return -1;

	case ssl_hs_flush:
	case ssl_hs_flush_and_read_message: {
	int ret = BIO_flush(ssl->wbio);
	if (ret <= 0) {
	ssl->rwstate = SSL_WRITING;
	return ret;
	}
	if (hs->wait != ssl_hs_flush_and_read_message) {
	break;
	}
	ssl->method->expect_flight(ssl);
	hs->wait = ssl_hs_read_message;
	/* Fall-through. */
	}

	case ssl_hs_read_message: {
	int ret = ssl->method->ssl_get_message(ssl, -1, ssl_dont_hash_message);
	if (ret <= 0) {
	return ret;
	}
	break;
	}

	case ssl_hs_write_message: {
	int ret = ssl->method->write_message(ssl);
	if (ret <= 0) {
	return ret;
	}
	break;
	}

	case ssl_hs_x509_lookup:
	ssl->rwstate = SSL_X509_LOOKUP;
	hs->wait = ssl_hs_ok;
	return -1;

	case ssl_hs_channel_id_lookup:
	ssl->rwstate = SSL_CHANNEL_ID_LOOKUP;
	hs->wait = ssl_hs_ok;
	return -1;

	case ssl_hs_private_key_operation:
	ssl->rwstate = SSL_PRIVATE_KEY_OPERATION;
	hs->wait = ssl_hs_ok;
	return -1;

	case ssl_hs_ok:
	break;
	}

	/* Run the state machine again. */
	hs->wait = hs->do_tls13_handshake(hs);
	if (hs->wait == ssl_hs_error) {
	/* Don't loop around to avoid a stray \|SSL_R_SSL_HANDSHAKE_FAILURE\| the
	* first time around. */
	return -1;
	}
	if (hs->wait == ssl_hs_ok) {
	/* The handshake has completed. */
	return 1;
	}

	/* Otherwise, loop to the beginning and resolve what was blocking the
	* handshake. */
	}
	}

	int tls13_get_cert_verify_signature_input(
	SSL ssl, uint8_t out, size_t out_len,
	enum ssl_cert_verify_context_t cert_verify_context) {
	CBB cbb;
	if (!CBB_init(&cbb, 64 + 33 + 1 + 2 * EVP_MAX_MD_SIZE)) {
	goto err;
	}

	for (size_t i = 0; i < 64; i++) {
	if (!CBB_add_u8(&cbb, 0x20)) {
	goto err;
	}
	}

	const uint8_t *context;
	size_t context_len;
	if (cert_verify_context == ssl_cert_verify_server) {
	/* Include the NUL byte. */
	static const char kContext[] = "TLS 1.3, server CertificateVerify";
	context = (const uint8_t *)kContext;
	context_len = sizeof(kContext);
	} else if (cert_verify_context == ssl_cert_verify_client) {
	static const char kContext[] = "TLS 1.3, client CertificateVerify";
	context = (const uint8_t *)kContext;
	context_len = sizeof(kContext);
	} else if (cert_verify_context == ssl_cert_verify_channel_id) {
	static const char kContext[] = "TLS 1.3, Channel ID";
	context = (const uint8_t *)kContext;
	context_len = sizeof(kContext);
	} else {
	goto err;
	}

	if (!CBB_add_bytes(&cbb, context, context_len)) {
	goto err;
	}

	uint8_t context_hash[EVP_MAX_MD_SIZE];
	size_t context_hash_len;
	if (!tls13_get_context_hash(ssl, context_hash, &context_hash_len) \|\|
	!CBB_add_bytes(&cbb, context_hash, context_hash_len) \|\|
	!CBB_finish(&cbb, out, out_len)) {
	goto err;
	}

	return 1;

	err:
	OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
	CBB_cleanup(&cbb);
	return 0;
	}

	int tls13_process_certificate(SSL_HANDSHAKE *hs, int allow_anonymous) {
	SSL *const ssl = hs->ssl;
	CBS cbs, context, certificate_list;
	CBS_init(&cbs, ssl->init_msg, ssl->init_num);
	if (!CBS_get_u8_length_prefixed(&cbs, &context) \|\|
	CBS_len(&context) != 0) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
	return 0;
	}

	const int retain_sha256 =
	ssl->server && ssl->retain_only_sha256_of_client_certs;
	int ret = 0;

	EVP_PKEY *pkey = NULL;
	STACK_OF(CRYPTO_BUFFER) *certs = sk_CRYPTO_BUFFER_new_null();
	if (certs == NULL) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
	goto err;
	}

	if (!CBS_get_u24_length_prefixed(&cbs, &certificate_list)) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
	goto err;
	}

	while (CBS_len(&certificate_list) > 0) {
	CBS certificate, extensions;
	if (!CBS_get_u24_length_prefixed(&certificate_list, &certificate) \|\|
	!CBS_get_u16_length_prefixed(&certificate_list, &extensions) \|\|
	CBS_len(&certificate) == 0) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	OPENSSL_PUT_ERROR(SSL, SSL_R_CERT_LENGTH_MISMATCH);
	goto err;
	}

	if (sk_CRYPTO_BUFFER_num(certs) == 0) {
	pkey = ssl_cert_parse_pubkey(&certificate);
	if (pkey == NULL) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
	goto err;
	}
	/* TLS 1.3 always uses certificate keys for signing thus the correct
	* keyUsage is enforced. */
	if (!ssl_cert_check_digital_signature_key_usage(&certificate)) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
	goto err;
	}

	if (retain_sha256) {
	/* Retain the hash of the leaf certificate if requested. */
	SHA256(CBS_data(&certificate), CBS_len(&certificate),
	ssl->s3->new_session->peer_sha256);
	}
	}

	CRYPTO_BUFFER *buf =
	CRYPTO_BUFFER_new_from_CBS(&certificate, ssl->ctx->pool);
	if (buf == NULL \|\|
	!sk_CRYPTO_BUFFER_push(certs, buf)) {
	CRYPTO_BUFFER_free(buf);
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
	goto err;
	}

	/* Parse out the extensions. */
	int have_status_request = 0, have_sct = 0;
	CBS status_request, sct;
	const SSL_EXTENSION_TYPE ext_types[] = {
	{TLSEXT_TYPE_status_request, &have_status_request, &status_request},
	{TLSEXT_TYPE_certificate_timestamp, &have_sct, &sct},
	};

	uint8_t alert;
	if (!ssl_parse_extensions(&extensions, &alert, ext_types,
	OPENSSL_ARRAY_SIZE(ext_types),
	0 /* reject unknown */)) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, alert);
	goto err;
	}

	/* All Certificate extensions are parsed, but only the leaf extensions are
	* stored. */
	if (have_status_request) {
	if (ssl->server \|\| !ssl->ocsp_stapling_enabled) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNSUPPORTED_EXTENSION);
	goto err;
	}

	uint8_t status_type;
	CBS ocsp_response;
	if (!CBS_get_u8(&status_request, &status_type) \|\|
	status_type != TLSEXT_STATUSTYPE_ocsp \|\|
	!CBS_get_u24_length_prefixed(&status_request, &ocsp_response) \|\|
	CBS_len(&ocsp_response) == 0 \|\|
	CBS_len(&status_request) != 0) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	goto err;
	}

	if (sk_CRYPTO_BUFFER_num(certs) == 1 &&
	!CBS_stow(&ocsp_response, &ssl->s3->new_session->ocsp_response,
	&ssl->s3->new_session->ocsp_response_length)) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	goto err;
	}
	}

	if (have_sct) {
	if (ssl->server \|\| !ssl->signed_cert_timestamps_enabled) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNSUPPORTED_EXTENSION);
	goto err;
	}

	if (!ssl_is_sct_list_valid(&sct)) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION);
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	goto err;
	}

	if (sk_CRYPTO_BUFFER_num(certs) == 1 &&
	!CBS_stow(&sct,
	&ssl->s3->new_session->tlsext_signed_cert_timestamp_list,
	&ssl->s3->new_session
	->tlsext_signed_cert_timestamp_list_length)) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	goto err;
	}
	}
	}

	if (CBS_len(&cbs) != 0) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	goto err;
	}

	EVP_PKEY_free(hs->peer_pubkey);
	hs->peer_pubkey = pkey;
	pkey = NULL;

	sk_CRYPTO_BUFFER_pop_free(ssl->s3->new_session->certs, CRYPTO_BUFFER_free);
	ssl->s3->new_session->certs = certs;
	certs = NULL;

	if (!ssl_session_x509_cache_objects(ssl->s3->new_session)) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	goto err;
	}

	if (sk_CRYPTO_BUFFER_num(ssl->s3->new_session->certs) == 0) {
	if (!allow_anonymous) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_PEER_DID_NOT_RETURN_A_CERTIFICATE);
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_CERTIFICATE_REQUIRED);
	goto err;
	}

	/* OpenSSL returns X509_V_OK when no certificates are requested. This is
	* classed by them as a bug, but it's assumed by at least NGINX. */
	ssl->s3->new_session->verify_result = X509_V_OK;

	/* No certificate, so nothing more to do. */
	ret = 1;
	goto err;
	}

	ssl->s3->new_session->peer_sha256_valid = retain_sha256;

	if (!ssl_verify_cert_chain(ssl, &ssl->s3->new_session->verify_result,
	ssl->s3->new_session->x509_chain)) {
	goto err;
	}

	ret = 1;

	err:
	sk_CRYPTO_BUFFER_pop_free(certs, CRYPTO_BUFFER_free);
	EVP_PKEY_free(pkey);
	return ret;
	}

	int tls13_process_certificate_verify(SSL_HANDSHAKE *hs) {
	SSL *const ssl = hs->ssl;
	int ret = 0;
	uint8_t *msg = NULL;
	size_t msg_len;

	if (hs->peer_pubkey == NULL) {
	goto err;
	}

	CBS cbs, signature;
	uint16_t signature_algorithm;
	CBS_init(&cbs, ssl->init_msg, ssl->init_num);
	if (!CBS_get_u16(&cbs, &signature_algorithm) \|\|
	!CBS_get_u16_length_prefixed(&cbs, &signature) \|\|
	CBS_len(&cbs) != 0) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	goto err;
	}

	int al;
	if (!tls12_check_peer_sigalg(ssl, &al, signature_algorithm)) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, al);
	goto err;
	}
	ssl->s3->new_session->peer_signature_algorithm = signature_algorithm;

	if (!tls13_get_cert_verify_signature_input(
	ssl, &msg, &msg_len,
	ssl->server ? ssl_cert_verify_client : ssl_cert_verify_server)) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	goto err;
	}

	int sig_ok =
	ssl_public_key_verify(ssl, CBS_data(&signature), CBS_len(&signature),
	signature_algorithm, hs->peer_pubkey, msg, msg_len);
	#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
	sig_ok = 1;
	ERR_clear_error();
	#endif
	if (!sig_ok) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SIGNATURE);
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
	goto err;
	}

	ret = 1;

	err:
	OPENSSL_free(msg);
	return ret;
	}

	int tls13_check_message_type(SSL *ssl, int type) {
	if (ssl->s3->tmp.message_type != type) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
	OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_MESSAGE);
	ERR_add_error_dataf("got type %d, wanted type %d",
	ssl->s3->tmp.message_type, type);
	return 0;
	}

	return 1;
	}

	int tls13_process_finished(SSL_HANDSHAKE *hs) {
	SSL *const ssl = hs->ssl;
	uint8_t verify_data[EVP_MAX_MD_SIZE];
	size_t verify_data_len;
	if (!tls13_finished_mac(hs, verify_data, &verify_data_len, !ssl->server)) {
	return 0;
	}

	int finished_ok =
	ssl->init_num == verify_data_len &&
	CRYPTO_memcmp(verify_data, ssl->init_msg, verify_data_len) == 0;
	#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
	finished_ok = 1;
	#endif
	if (!finished_ok) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
	OPENSSL_PUT_ERROR(SSL, SSL_R_DIGEST_CHECK_FAILED);
	return 0;
	}

	return 1;
	}

	int tls13_prepare_certificate(SSL_HANDSHAKE *hs) {
	SSL *const ssl = hs->ssl;
	CBB cbb, body, certificate_list;
	if (!ssl->method->init_message(ssl, &cbb, &body, SSL3_MT_CERTIFICATE) \|\|
	/* The request context is always empty in the handshake. */
	!CBB_add_u8(&body, 0) \|\|
	!CBB_add_u24_length_prefixed(&body, &certificate_list)) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	goto err;
	}

	if (!ssl_has_certificate(ssl)) {
	if (!ssl_complete_message(ssl, &cbb)) {
	goto err;
	}

	return 1;
	}

	CERT *cert = ssl->cert;
	CBB leaf, extensions;
	if (!CBB_add_u24_length_prefixed(&certificate_list, &leaf) \|\|
	!ssl_add_cert_to_cbb(&leaf, cert->x509_leaf) \|\|
	!CBB_add_u16_length_prefixed(&certificate_list, &extensions)) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	goto err;
	}

	if (hs->scts_requested &&
	ssl->ctx->signed_cert_timestamp_list_length != 0) {
	CBB contents;
	if (!CBB_add_u16(&extensions, TLSEXT_TYPE_certificate_timestamp) \|\|
	!CBB_add_u16_length_prefixed(&extensions, &contents) \|\|
	!CBB_add_bytes(&contents, ssl->ctx->signed_cert_timestamp_list,
	ssl->ctx->signed_cert_timestamp_list_length) \|\|
	!CBB_flush(&extensions)) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	goto err;
	}
	}

	if (hs->ocsp_stapling_requested &&
	ssl->ocsp_response != NULL) {
	CBB contents, ocsp_response;
	if (!CBB_add_u16(&extensions, TLSEXT_TYPE_status_request) \|\|
	!CBB_add_u16_length_prefixed(&extensions, &contents) \|\|
	!CBB_add_u8(&contents, TLSEXT_STATUSTYPE_ocsp) \|\|
	!CBB_add_u24_length_prefixed(&contents, &ocsp_response) \|\|
	!CBB_add_bytes(&ocsp_response, CRYPTO_BUFFER_data(ssl->ocsp_response),
	CRYPTO_BUFFER_len(ssl->ocsp_response)) \|\|
	!CBB_flush(&extensions)) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	goto err;
	}
	}

	for (size_t i = 0; i < sk_X509_num(cert->x509_chain); i++) {
	CBB child;
	if (!CBB_add_u24_length_prefixed(&certificate_list, &child) \|\|
	!ssl_add_cert_to_cbb(&child, sk_X509_value(cert->x509_chain, i)) \|\|
	!CBB_add_u16(&certificate_list, 0 /* no extensions */)) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	goto err;
	}
	}

	if (!ssl_complete_message(ssl, &cbb)) {
	goto err;
	}

	return 1;

	err:
	CBB_cleanup(&cbb);
	return 0;
	}

	enum ssl_private_key_result_t tls13_prepare_certificate_verify(
	SSL_HANDSHAKE *hs, int is_first_run) {
	SSL *const ssl = hs->ssl;
	enum ssl_private_key_result_t ret = ssl_private_key_failure;
	uint8_t *msg = NULL;
	size_t msg_len;
	CBB cbb, body;
	CBB_zero(&cbb);

	uint16_t signature_algorithm;
	if (!tls1_choose_signature_algorithm(hs, &signature_algorithm)) {
	goto err;
	}
	if (!ssl->method->init_message(ssl, &cbb, &body,
	SSL3_MT_CERTIFICATE_VERIFY) \|\|
	!CBB_add_u16(&body, signature_algorithm)) {
	OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
	goto err;
	}

	/* Sign the digest. */
	CBB child;
	const size_t max_sig_len = ssl_private_key_max_signature_len(ssl);
	uint8_t *sig;
	size_t sig_len;
	if (!CBB_add_u16_length_prefixed(&body, &child) \|\|
	!CBB_reserve(&child, &sig, max_sig_len)) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	goto err;
	}

	enum ssl_private_key_result_t sign_result;
	if (is_first_run) {
	if (!tls13_get_cert_verify_signature_input(
	ssl, &msg, &msg_len,
	ssl->server ? ssl_cert_verify_server : ssl_cert_verify_client)) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	goto err;
	}
	sign_result = ssl_private_key_sign(ssl, sig, &sig_len, max_sig_len,
	signature_algorithm, msg, msg_len);
	} else {
	sign_result = ssl_private_key_complete(ssl, sig, &sig_len, max_sig_len);
	}

	if (sign_result != ssl_private_key_success) {
	ret = sign_result;
	goto err;
	}

	if (!CBB_did_write(&child, sig_len) \|\|
	!ssl_complete_message(ssl, &cbb)) {
	goto err;
	}

	ret = ssl_private_key_success;

	err:
	CBB_cleanup(&cbb);
	OPENSSL_free(msg);
	return ret;
	}

	int tls13_prepare_finished(SSL_HANDSHAKE *hs) {
	SSL *const ssl = hs->ssl;
	size_t verify_data_len;
	uint8_t verify_data[EVP_MAX_MD_SIZE];

	if (!tls13_finished_mac(hs, verify_data, &verify_data_len, ssl->server)) {
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
	OPENSSL_PUT_ERROR(SSL, SSL_R_DIGEST_CHECK_FAILED);
	return 0;
	}

	CBB cbb, body;
	if (!ssl->method->init_message(ssl, &cbb, &body, SSL3_MT_FINISHED) \|\|
	!CBB_add_bytes(&body, verify_data, verify_data_len) \|\|
	!ssl_complete_message(ssl, &cbb)) {
	CBB_cleanup(&cbb);
	return 0;
	}

	return 1;
	}

	static int tls13_receive_key_update(SSL *ssl) {
	CBS cbs;
	uint8_t key_update_request;
	CBS_init(&cbs, ssl->init_msg, ssl->init_num);
	if (!CBS_get_u8(&cbs, &key_update_request) \|\|
	CBS_len(&cbs) != 0 \|\|
	(key_update_request != SSL_KEY_UPDATE_NOT_REQUESTED &&
	key_update_request != SSL_KEY_UPDATE_REQUESTED)) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
	return 0;
	}

	/* TODO(svaldez): Send KeyUpdate if \|key_update_request\| is
	* \|SSL_KEY_UPDATE_REQUESTED\|. */
	return tls13_rotate_traffic_key(ssl, evp_aead_open);
	}

	int tls13_post_handshake(SSL *ssl) {
	if (ssl->s3->tmp.message_type == SSL3_MT_KEY_UPDATE) {
	ssl->s3->key_update_count++;
	if (ssl->s3->key_update_count > kMaxKeyUpdates) {
	OPENSSL_PUT_ERROR(SSL, SSL_R_TOO_MANY_KEY_UPDATES);
	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
	return 0;
	}

	return tls13_receive_key_update(ssl);
	}

	ssl->s3->key_update_count = 0;

	if (ssl->s3->tmp.message_type == SSL3_MT_NEW_SESSION_TICKET &&
	!ssl->server) {
	return tls13_process_new_session_ticket(ssl);
	}

	// TODO(svaldez): Handle post-handshake authentication.

	ssl3_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
	OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_MESSAGE);
	return 0;
	}