Revert "external/boringssl: Sync to 7a817f48bafee508b2d23ad278f892ee1cb32b91."

This reverts commit d03f4c0ac5663fb300b1f40f1059c4194dd0652a.

Reason for revert: Investigating b/194282044

Change-Id: I168d73caae2cbc83921133cd47aef37d3bce8c37

1 files changed, 0 insertions, 4387 deletions

diff --git a/src/ssl/extensions.cc b/src/ssl/extensions.cc
deleted file mode 100644
index 4950d266..00000000
--- a/src/ssl/extensions.cc
+++ /dev/null
@@ -1,4387 +0,0 @@
-/* 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). */
-
-#include <openssl/ssl.h>
-
-#include <assert.h>
-#include <limits.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include <algorithm>
-#include <utility>
-
-#include <openssl/aead.h>
-#include <openssl/bytestring.h>
-#include <openssl/chacha.h>
-#include <openssl/curve25519.h>
-#include <openssl/digest.h>
-#include <openssl/err.h>
-#include <openssl/evp.h>
-#include <openssl/hmac.h>
-#include <openssl/hpke.h>
-#include <openssl/mem.h>
-#include <openssl/nid.h>
-#include <openssl/rand.h>
-
-#include "../crypto/internal.h"
-#include "internal.h"
-
-
-BSSL_NAMESPACE_BEGIN
-
-static bool ssl_check_clienthello_tlsext(SSL_HANDSHAKE *hs);
-static bool ssl_check_serverhello_tlsext(SSL_HANDSHAKE *hs);
-
-static int compare_uint16_t(const void *p1, const void *p2) {
-  uint16_t u1 = *((const uint16_t *)p1);
-  uint16_t u2 = *((const uint16_t *)p2);
-  if (u1 < u2) {
-    return -1;
-  } else if (u1 > u2) {
-    return 1;
-  } else {
-    return 0;
-  }
-}
-
-// Per http://tools.ietf.org/html/rfc5246#section-7.4.1.4, there may not be
-// more than one extension of the same type in a ClientHello or ServerHello.
-// This function does an initial scan over the extensions block to filter those
-// out.
-static bool tls1_check_duplicate_extensions(const CBS *cbs) {
-  // First pass: count the extensions.
-  size_t num_extensions = 0;
-  CBS extensions = *cbs;
-  while (CBS_len(&extensions) > 0) {
-    uint16_t type;
-    CBS extension;
-
-    if (!CBS_get_u16(&extensions, &type) ||
-        !CBS_get_u16_length_prefixed(&extensions, &extension)) {
-      return false;
-    }
-
-    num_extensions++;
-  }
-
-  if (num_extensions == 0) {
-    return true;
-  }
-
-  Array<uint16_t> extension_types;
-  if (!extension_types.Init(num_extensions)) {
-    return false;
-  }
-
-  // Second pass: gather the extension types.
-  extensions = *cbs;
-  for (size_t i = 0; i < extension_types.size(); i++) {
-    CBS extension;
-
-    if (!CBS_get_u16(&extensions, &extension_types[i]) ||
-        !CBS_get_u16_length_prefixed(&extensions, &extension)) {
-      // This should not happen.
-      return false;
-    }
-  }
-  assert(CBS_len(&extensions) == 0);
-
-  // Sort the extensions and make sure there are no duplicates.
-  qsort(extension_types.data(), extension_types.size(), sizeof(uint16_t),
-        compare_uint16_t);
-  for (size_t i = 1; i < num_extensions; i++) {
-    if (extension_types[i - 1] == extension_types[i]) {
-      return false;
-    }
-  }
-
-  return true;
-}
-
-static bool is_post_quantum_group(uint16_t id) {
-  return id == SSL_CURVE_CECPQ2;
-}
-
-bool ssl_client_hello_init(const SSL *ssl, SSL_CLIENT_HELLO *out,
-                           Span<const uint8_t> body) {
-  OPENSSL_memset(out, 0, sizeof(*out));
-  out->ssl = const_cast<SSL *>(ssl);
-  out->client_hello = body.data();
-  out->client_hello_len = body.size();
-
-  CBS client_hello, random, session_id;
-  CBS_init(&client_hello, out->client_hello, out->client_hello_len);
-  if (!CBS_get_u16(&client_hello, &out->version) ||
-      !CBS_get_bytes(&client_hello, &random, SSL3_RANDOM_SIZE) ||
-      !CBS_get_u8_length_prefixed(&client_hello, &session_id) ||
-      CBS_len(&session_id) > SSL_MAX_SSL_SESSION_ID_LENGTH) {
-    return false;
-  }
-
-  out->random = CBS_data(&random);
-  out->random_len = CBS_len(&random);
-  out->session_id = CBS_data(&session_id);
-  out->session_id_len = CBS_len(&session_id);
-
-  // Skip past DTLS cookie
-  if (SSL_is_dtls(out->ssl)) {
-    CBS cookie;
-    if (!CBS_get_u8_length_prefixed(&client_hello, &cookie) ||
-        CBS_len(&cookie) > DTLS1_COOKIE_LENGTH) {
-      return false;
-    }
-  }
-
-  CBS cipher_suites, compression_methods;
-  if (!CBS_get_u16_length_prefixed(&client_hello, &cipher_suites) ||
-      CBS_len(&cipher_suites) < 2 || (CBS_len(&cipher_suites) & 1) != 0 ||
-      !CBS_get_u8_length_prefixed(&client_hello, &compression_methods) ||
-      CBS_len(&compression_methods) < 1) {
-    return false;
-  }
-
-  out->cipher_suites = CBS_data(&cipher_suites);
-  out->cipher_suites_len = CBS_len(&cipher_suites);
-  out->compression_methods = CBS_data(&compression_methods);
-  out->compression_methods_len = CBS_len(&compression_methods);
-
-  // If the ClientHello ends here then it's valid, but doesn't have any
-  // extensions.
-  if (CBS_len(&client_hello) == 0) {
-    out->extensions = NULL;
-    out->extensions_len = 0;
-    return true;
-  }
-
-  // Extract extensions and check it is valid.
-  CBS extensions;
-  if (!CBS_get_u16_length_prefixed(&client_hello, &extensions) ||
-      !tls1_check_duplicate_extensions(&extensions) ||
-      CBS_len(&client_hello) != 0) {
-    return false;
-  }
-
-  out->extensions = CBS_data(&extensions);
-  out->extensions_len = CBS_len(&extensions);
-
-  return true;
-}
-
-bool ssl_client_hello_get_extension(const SSL_CLIENT_HELLO *client_hello,
-                                    CBS *out, uint16_t extension_type) {
-  CBS extensions;
-  CBS_init(&extensions, client_hello->extensions, client_hello->extensions_len);
-  while (CBS_len(&extensions) != 0) {
-    // Decode the next extension.
-    uint16_t type;
-    CBS extension;
-    if (!CBS_get_u16(&extensions, &type) ||
-        !CBS_get_u16_length_prefixed(&extensions, &extension)) {
-      return false;
-    }
-
-    if (type == extension_type) {
-      *out = extension;
-      return true;
-    }
-  }
-
-  return false;
-}
-
-static const uint16_t kDefaultGroups[] = {
-    SSL_CURVE_X25519,
-    SSL_CURVE_SECP256R1,
-    SSL_CURVE_SECP384R1,
-};
-
-Span<const uint16_t> tls1_get_grouplist(const SSL_HANDSHAKE *hs) {
-  if (!hs->config->supported_group_list.empty()) {
-    return hs->config->supported_group_list;
-  }
-  return Span<const uint16_t>(kDefaultGroups);
-}
-
-bool tls1_get_shared_group(SSL_HANDSHAKE *hs, uint16_t *out_group_id) {
-  SSL *const ssl = hs->ssl;
-  assert(ssl->server);
-
-  // Clients are not required to send a supported_groups extension. In this
-  // case, the server is free to pick any group it likes. See RFC 4492,
-  // section 4, paragraph 3.
-  //
-  // However, in the interests of compatibility, we will skip ECDH if the
-  // client didn't send an extension because we can't be sure that they'll
-  // support our favoured group. Thus we do not special-case an emtpy
-  // |peer_supported_group_list|.
-
-  Span<const uint16_t> groups = tls1_get_grouplist(hs);
-  Span<const uint16_t> pref, supp;
-  if (ssl->options & SSL_OP_CIPHER_SERVER_PREFERENCE) {
-    pref = groups;
-    supp = hs->peer_supported_group_list;
-  } else {
-    pref = hs->peer_supported_group_list;
-    supp = groups;
-  }
-
-  for (uint16_t pref_group : pref) {
-    for (uint16_t supp_group : supp) {
-      if (pref_group == supp_group &&
-          // CECPQ2(b) doesn't fit in the u8-length-prefixed ECPoint field in
-          // TLS 1.2 and below.
-          (ssl_protocol_version(ssl) >= TLS1_3_VERSION ||
-           !is_post_quantum_group(pref_group))) {
-        *out_group_id = pref_group;
-        return true;
-      }
-    }
-  }
-
-  return false;
-}
-
-bool tls1_set_curves(Array<uint16_t> *out_group_ids, Span<const int> curves) {
-  Array<uint16_t> group_ids;
-  if (!group_ids.Init(curves.size())) {
-    return false;
-  }
-
-  for (size_t i = 0; i < curves.size(); i++) {
-    if (!ssl_nid_to_group_id(&group_ids[i], curves[i])) {
-      return false;
-    }
-  }
-
-  *out_group_ids = std::move(group_ids);
-  return true;
-}
-
-bool tls1_set_curves_list(Array<uint16_t> *out_group_ids, const char *curves) {
-  // Count the number of curves in the list.
-  size_t count = 0;
-  const char *ptr = curves, *col;
-  do {
-    col = strchr(ptr, ':');
-    count++;
-    if (col) {
-      ptr = col + 1;
-    }
-  } while (col);
-
-  Array<uint16_t> group_ids;
-  if (!group_ids.Init(count)) {
-    return false;
-  }
-
-  size_t i = 0;
-  ptr = curves;
-  do {
-    col = strchr(ptr, ':');
-    if (!ssl_name_to_group_id(&group_ids[i++], ptr,
-                              col ? (size_t)(col - ptr) : strlen(ptr))) {
-      return false;
-    }
-    if (col) {
-      ptr = col + 1;
-    }
-  } while (col);
-
-  assert(i == count);
-  *out_group_ids = std::move(group_ids);
-  return true;
-}
-
-bool tls1_check_group_id(const SSL_HANDSHAKE *hs, uint16_t group_id) {
-  if (is_post_quantum_group(group_id) &&
-      ssl_protocol_version(hs->ssl) < TLS1_3_VERSION) {
-    // CECPQ2(b) requires TLS 1.3.
-    return false;
-  }
-
-  // We internally assume zero is never allocated as a group ID.
-  if (group_id == 0) {
-    return false;
-  }
-
-  for (uint16_t supported : tls1_get_grouplist(hs)) {
-    if (supported == group_id) {
-      return true;
-    }
-  }
-
-  return false;
-}
-
-// kVerifySignatureAlgorithms is the default list of accepted signature
-// algorithms for verifying.
-static const uint16_t kVerifySignatureAlgorithms[] = {
-    // List our preferred algorithms first.
-    SSL_SIGN_ECDSA_SECP256R1_SHA256,
-    SSL_SIGN_RSA_PSS_RSAE_SHA256,
-    SSL_SIGN_RSA_PKCS1_SHA256,
-
-    // Larger hashes are acceptable.
-    SSL_SIGN_ECDSA_SECP384R1_SHA384,
-    SSL_SIGN_RSA_PSS_RSAE_SHA384,
-    SSL_SIGN_RSA_PKCS1_SHA384,
-
-    SSL_SIGN_RSA_PSS_RSAE_SHA512,
-    SSL_SIGN_RSA_PKCS1_SHA512,
-
-    // For now, SHA-1 is still accepted but least preferable.
-    SSL_SIGN_RSA_PKCS1_SHA1,
-};
-
-// kSignSignatureAlgorithms is the default list of supported signature
-// algorithms for signing.
-static const uint16_t kSignSignatureAlgorithms[] = {
-    // List our preferred algorithms first.
-    SSL_SIGN_ED25519,
-    SSL_SIGN_ECDSA_SECP256R1_SHA256,
-    SSL_SIGN_RSA_PSS_RSAE_SHA256,
-    SSL_SIGN_RSA_PKCS1_SHA256,
-
-    // If needed, sign larger hashes.
-    //
-    // TODO(davidben): Determine which of these may be pruned.
-    SSL_SIGN_ECDSA_SECP384R1_SHA384,
-    SSL_SIGN_RSA_PSS_RSAE_SHA384,
-    SSL_SIGN_RSA_PKCS1_SHA384,
-
-    SSL_SIGN_ECDSA_SECP521R1_SHA512,
-    SSL_SIGN_RSA_PSS_RSAE_SHA512,
-    SSL_SIGN_RSA_PKCS1_SHA512,
-
-    // If the peer supports nothing else, sign with SHA-1.
-    SSL_SIGN_ECDSA_SHA1,
-    SSL_SIGN_RSA_PKCS1_SHA1,
-};
-
-static Span<const uint16_t> tls12_get_verify_sigalgs(const SSL_HANDSHAKE *hs) {
-  if (hs->config->verify_sigalgs.empty()) {
-    return Span<const uint16_t>(kVerifySignatureAlgorithms);
-  }
-  return hs->config->verify_sigalgs;
-}
-
-bool tls12_add_verify_sigalgs(const SSL_HANDSHAKE *hs, CBB *out) {
-  for (uint16_t sigalg : tls12_get_verify_sigalgs(hs)) {
-    if (!CBB_add_u16(out, sigalg)) {
-      return false;
-    }
-  }
-  return true;
-}
-
-bool tls12_check_peer_sigalg(const SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                             uint16_t sigalg) {
-  for (uint16_t verify_sigalg : tls12_get_verify_sigalgs(hs)) {
-    if (verify_sigalg == sigalg) {
-      return true;
-    }
-  }
-
-  OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_SIGNATURE_TYPE);
-  *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-  return false;
-}
-
-// tls_extension represents a TLS extension that is handled internally.
-//
-// The parse callbacks receive a |CBS| that contains the contents of the
-// extension (i.e. not including the type and length bytes). If an extension is
-// not received then the parse callbacks will be called with a NULL CBS so that
-// they can do any processing needed to handle the absence of an extension.
-//
-// The add callbacks receive a |CBB| to which the extension can be appended but
-// the function is responsible for appending the type and length bytes too.
-//
-// |add_clienthello| may be called multiple times and must not mutate |hs|. It
-// is additionally passed two output |CBB|s. If the extension is the same
-// independent of the value of |type|, the callback may write to
-// |out_compressible| instead of |out|. When serializing the ClientHelloInner,
-// all compressible extensions will be made continguous and replaced with
-// ech_outer_extensions when encrypted. When serializing the ClientHelloOuter
-// or not offering ECH, |out| will be equal to |out_compressible|, so writing to
-// |out_compressible| still works.
-//
-// Note the |parse_serverhello| and |add_serverhello| callbacks refer to the
-// TLS 1.2 ServerHello. In TLS 1.3, these callbacks act on EncryptedExtensions,
-// with ServerHello extensions handled elsewhere in the handshake.
-//
-// All callbacks return true for success and false for error. If a parse
-// function returns zero then a fatal alert with value |*out_alert| will be
-// sent. If |*out_alert| isn't set, then a |decode_error| alert will be sent.
-struct tls_extension {
-  uint16_t value;
-
-  bool (*add_clienthello)(const SSL_HANDSHAKE *hs, CBB *out,
-                          CBB *out_compressible, ssl_client_hello_type_t type);
-  bool (*parse_serverhello)(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                            CBS *contents);
-
-  bool (*parse_clienthello)(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                            CBS *contents);
-  bool (*add_serverhello)(SSL_HANDSHAKE *hs, CBB *out);
-};
-
-static bool forbid_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                     CBS *contents) {
-  if (contents != NULL) {
-    // Servers MUST NOT send this extension.
-    *out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
-    OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
-    return false;
-  }
-
-  return true;
-}
-
-static bool ignore_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                     CBS *contents) {
-  // This extension from the client is handled elsewhere.
-  return true;
-}
-
-static bool dont_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  return true;
-}
-
-// Server name indication (SNI).
-//
-// https://tools.ietf.org/html/rfc6066#section-3.
-
-static bool ext_sni_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                    CBB *out_compressible,
-                                    ssl_client_hello_type_t type) {
-  const SSL *const ssl = hs->ssl;
-  // If offering ECH, send the public name instead of the configured name.
-  Span<const uint8_t> hostname;
-  if (type == ssl_client_hello_outer) {
-    hostname = hs->selected_ech_config->public_name;
-  } else {
-    if (ssl->hostname == nullptr) {
-      return true;
-    }
-    hostname =
-        MakeConstSpan(reinterpret_cast<const uint8_t *>(ssl->hostname.get()),
-                      strlen(ssl->hostname.get()));
-  }
-
-  CBB contents, server_name_list, name;
-  if (!CBB_add_u16(out, TLSEXT_TYPE_server_name) ||
-      !CBB_add_u16_length_prefixed(out, &contents) ||
-      !CBB_add_u16_length_prefixed(&contents, &server_name_list) ||
-      !CBB_add_u8(&server_name_list, TLSEXT_NAMETYPE_host_name) ||
-      !CBB_add_u16_length_prefixed(&server_name_list, &name) ||
-      !CBB_add_bytes(&name, hostname.data(), hostname.size()) ||
-      !CBB_flush(out)) {
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_sni_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                      CBS *contents) {
-  // The server may acknowledge SNI with an empty extension. We check the syntax
-  // but otherwise ignore this signal.
-  return contents == NULL || CBS_len(contents) == 0;
-}
-
-static bool ext_sni_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                      CBS *contents) {
-  // SNI has already been parsed earlier in the handshake. See |extract_sni|.
-  return true;
-}
-
-static bool ext_sni_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  if (hs->ssl->s3->session_reused ||
-      !hs->should_ack_sni) {
-    return true;
-  }
-
-  if (!CBB_add_u16(out, TLSEXT_TYPE_server_name) ||
-      !CBB_add_u16(out, 0 /* length */)) {
-    return false;
-  }
-
-  return true;
-}
-
-
-// Encrypted ClientHello (ECH)
-//
-// https://tools.ietf.org/html/draft-ietf-tls-esni-10
-
-static bool ext_ech_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                    CBB *out_compressible,
-                                    ssl_client_hello_type_t type) {
-  if (type == ssl_client_hello_inner || hs->ech_client_bytes.empty()) {
-    return true;
-  }
-
-  CBB ech_body;
-  if (!CBB_add_u16(out, TLSEXT_TYPE_encrypted_client_hello) ||
-      !CBB_add_u16_length_prefixed(out, &ech_body) ||
-      !CBB_add_bytes(&ech_body, hs->ech_client_bytes.data(),
-                     hs->ech_client_bytes.size()) ||
-      !CBB_flush(out)) {
-    return false;
-  }
-  return true;
-}
-
-static bool ext_ech_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                      CBS *contents) {
-  SSL *const ssl = hs->ssl;
-  if (contents == NULL) {
-    return true;
-  }
-
-  // The ECH extension may not be sent in TLS 1.2 ServerHello, only TLS 1.3
-  // EncryptedExtension.
-  if (ssl_protocol_version(ssl) < TLS1_3_VERSION) {
-    *out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
-    OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
-    return false;
-  }
-
-  if (!ssl_is_valid_ech_config_list(*contents)) {
-    *out_alert = SSL_AD_DECODE_ERROR;
-    return false;
-  }
-
-  // The server may only send retry configs in response to ClientHelloOuter (or
-  // ECH GREASE), not ClientHelloInner. The unsolicited extension rule checks
-  // this implicitly because the ClientHelloInner has no encrypted_client_hello
-  // extension.
-  //
-  // TODO(https://crbug.com/boringssl/275): If
-  // https://github.com/tlswg/draft-ietf-tls-esni/pull/422 is merged, a later
-  // draft will fold encrypted_client_hello and ech_is_inner together. Then this
-  // assert should become a runtime check.
-  assert(ssl->s3->ech_status != ssl_ech_accepted);
-  if (hs->selected_ech_config &&
-      !hs->ech_retry_configs.CopyFrom(*contents)) {
-    *out_alert = SSL_AD_INTERNAL_ERROR;
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_ech_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                      CBS *contents) {
-  if (contents != nullptr) {
-    hs->ech_present = true;
-    return true;
-  }
-  return true;
-}
-
-static bool ext_ech_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  SSL *const ssl = hs->ssl;
-  if (ssl_protocol_version(ssl) < TLS1_3_VERSION ||
-      ssl->s3->ech_status == ssl_ech_accepted ||  //
-      hs->ech_keys == nullptr) {
-    return true;
-  }
-
-  // Write the list of retry configs to |out|. Note |SSL_CTX_set1_ech_keys|
-  // ensures |ech_keys| contains at least one retry config.
-  CBB body, retry_configs;
-  if (!CBB_add_u16(out, TLSEXT_TYPE_encrypted_client_hello) ||
-      !CBB_add_u16_length_prefixed(out, &body) ||
-      !CBB_add_u16_length_prefixed(&body, &retry_configs)) {
-    return false;
-  }
-  for (const auto &config : hs->ech_keys->configs) {
-    if (!config->is_retry_config()) {
-      continue;
-    }
-    if (!CBB_add_bytes(&retry_configs, config->ech_config().raw.data(),
-                       config->ech_config().raw.size())) {
-      return false;
-    }
-  }
-  return CBB_flush(out);
-}
-
-static bool ext_ech_is_inner_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                             CBB *out_compressible,
-                                             ssl_client_hello_type_t type) {
-  if (type == ssl_client_hello_inner) {
-    if (!CBB_add_u16(out, TLSEXT_TYPE_ech_is_inner) ||
-        !CBB_add_u16(out, 0 /* empty extension */)) {
-      return false;
-    }
-  }
-  return true;
-}
-
-static bool ext_ech_is_inner_parse_clienthello(SSL_HANDSHAKE *hs,
-                                               uint8_t *out_alert,
-                                               CBS *contents) {
-  if (contents == nullptr) {
-    return true;
-  }
-  if (CBS_len(contents) > 0) {
-    *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-    return false;
-  }
-  hs->ech_is_inner_present = true;
-  return true;
-}
-
-
-// Renegotiation indication.
-//
-// https://tools.ietf.org/html/rfc5746
-
-static bool ext_ri_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                   CBB *out_compressible,
-                                   ssl_client_hello_type_t type) {
-  const SSL *const ssl = hs->ssl;
-  // Renegotiation indication is not necessary in TLS 1.3.
-  if (hs->min_version >= TLS1_3_VERSION ||
-     type == ssl_client_hello_inner) {
-    return true;
-  }
-
-  assert(ssl->s3->initial_handshake_complete ==
-         (ssl->s3->previous_client_finished_len != 0));
-
-  CBB contents, prev_finished;
-  if (!CBB_add_u16(out, TLSEXT_TYPE_renegotiate) ||
-      !CBB_add_u16_length_prefixed(out, &contents) ||
-      !CBB_add_u8_length_prefixed(&contents, &prev_finished) ||
-      !CBB_add_bytes(&prev_finished, ssl->s3->previous_client_finished,
-                     ssl->s3->previous_client_finished_len) ||
-      !CBB_flush(out)) {
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_ri_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                     CBS *contents) {
-  SSL *const ssl = hs->ssl;
-  if (contents != NULL && ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
-    *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-    return false;
-  }
-
-  // Servers may not switch between omitting the extension and supporting it.
-  // See RFC 5746, sections 3.5 and 4.2.
-  if (ssl->s3->initial_handshake_complete &&
-      (contents != NULL) != ssl->s3->send_connection_binding) {
-    *out_alert = SSL_AD_HANDSHAKE_FAILURE;
-    OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
-    return false;
-  }
-
-  if (contents == NULL) {
-    // Strictly speaking, if we want to avoid an attack we should *always* see
-    // RI even on initial ServerHello because the client doesn't see any
-    // renegotiation during an attack. However this would mean we could not
-    // connect to any server which doesn't support RI.
-    //
-    // OpenSSL has |SSL_OP_LEGACY_SERVER_CONNECT| to control this, but in
-    // practical terms every client sets it so it's just assumed here.
-    return true;
-  }
-
-  const size_t expected_len = ssl->s3->previous_client_finished_len +
-                              ssl->s3->previous_server_finished_len;
-
-  // Check for logic errors
-  assert(!expected_len || ssl->s3->previous_client_finished_len);
-  assert(!expected_len || ssl->s3->previous_server_finished_len);
-  assert(ssl->s3->initial_handshake_complete ==
-         (ssl->s3->previous_client_finished_len != 0));
-  assert(ssl->s3->initial_handshake_complete ==
-         (ssl->s3->previous_server_finished_len != 0));
-
-  // Parse out the extension contents.
-  CBS renegotiated_connection;
-  if (!CBS_get_u8_length_prefixed(contents, &renegotiated_connection) ||
-      CBS_len(contents) != 0) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_ENCODING_ERR);
-    *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-    return false;
-  }
-
-  // Check that the extension matches.
-  if (CBS_len(&renegotiated_connection) != expected_len) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
-    *out_alert = SSL_AD_HANDSHAKE_FAILURE;
-    return false;
-  }
-
-  const uint8_t *d = CBS_data(&renegotiated_connection);
-  bool ok = CRYPTO_memcmp(d, ssl->s3->previous_client_finished,
-                          ssl->s3->previous_client_finished_len) == 0;
-#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
-  ok = true;
-#endif
-  if (!ok) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
-    *out_alert = SSL_AD_HANDSHAKE_FAILURE;
-    return false;
-  }
-  d += ssl->s3->previous_client_finished_len;
-
-  ok = CRYPTO_memcmp(d, ssl->s3->previous_server_finished,
-                     ssl->s3->previous_server_finished_len) == 0;
-#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
-  ok = true;
-#endif
-  if (!ok) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
-    *out_alert = SSL_AD_HANDSHAKE_FAILURE;
-    return false;
-  }
-  ssl->s3->send_connection_binding = true;
-
-  return true;
-}
-
-static bool ext_ri_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                     CBS *contents) {
-  SSL *const ssl = hs->ssl;
-  // Renegotiation isn't supported as a server so this function should never be
-  // called after the initial handshake.
-  assert(!ssl->s3->initial_handshake_complete);
-
-  if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
-    return true;
-  }
-
-  if (contents == NULL) {
-    return true;
-  }
-
-  CBS renegotiated_connection;
-  if (!CBS_get_u8_length_prefixed(contents, &renegotiated_connection) ||
-      CBS_len(contents) != 0) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_ENCODING_ERR);
-    return false;
-  }
-
-  // Check that the extension matches. We do not support renegotiation as a
-  // server, so this must be empty.
-  if (CBS_len(&renegotiated_connection) != 0) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_MISMATCH);
-    *out_alert = SSL_AD_HANDSHAKE_FAILURE;
-    return false;
-  }
-
-  ssl->s3->send_connection_binding = true;
-
-  return true;
-}
-
-static bool ext_ri_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  SSL *const ssl = hs->ssl;
-  // Renegotiation isn't supported as a server so this function should never be
-  // called after the initial handshake.
-  assert(!ssl->s3->initial_handshake_complete);
-
-  if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
-    return true;
-  }
-
-  if (!CBB_add_u16(out, TLSEXT_TYPE_renegotiate) ||
-      !CBB_add_u16(out, 1 /* length */) ||
-      !CBB_add_u8(out, 0 /* empty renegotiation info */)) {
-    return false;
-  }
-
-  return true;
-}
-
-
-// Extended Master Secret.
-//
-// https://tools.ietf.org/html/rfc7627
-
-static bool ext_ems_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                    CBB *out_compressible,
-                                    ssl_client_hello_type_t type) {
-  // Extended master secret is not necessary in TLS 1.3.
-  if (hs->min_version >= TLS1_3_VERSION || type == ssl_client_hello_inner) {
-    return true;
-  }
-
-  if (!CBB_add_u16(out, TLSEXT_TYPE_extended_master_secret) ||
-      !CBB_add_u16(out, 0 /* length */)) {
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_ems_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                      CBS *contents) {
-  SSL *const ssl = hs->ssl;
-
-  if (contents != NULL) {
-    if (ssl_protocol_version(ssl) >= TLS1_3_VERSION ||
-        CBS_len(contents) != 0) {
-      return false;
-    }
-
-    hs->extended_master_secret = true;
-  }
-
-  // Whether EMS is negotiated may not change on renegotiation.
-  if (ssl->s3->established_session != nullptr &&
-      hs->extended_master_secret !=
-          !!ssl->s3->established_session->extended_master_secret) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_RENEGOTIATION_EMS_MISMATCH);
-    *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_ems_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                      CBS *contents) {
-  if (ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) {
-    return true;
-  }
-
-  if (contents == NULL) {
-    return true;
-  }
-
-  if (CBS_len(contents) != 0) {
-    return false;
-  }
-
-  hs->extended_master_secret = true;
-  return true;
-}
-
-static bool ext_ems_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  if (!hs->extended_master_secret) {
-    return true;
-  }
-
-  if (!CBB_add_u16(out, TLSEXT_TYPE_extended_master_secret) ||
-      !CBB_add_u16(out, 0 /* length */)) {
-    return false;
-  }
-
-  return true;
-}
-
-
-// Session tickets.
-//
-// https://tools.ietf.org/html/rfc5077
-
-static bool ext_ticket_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                       CBB *out_compressible,
-                                       ssl_client_hello_type_t type) {
-  const SSL *const ssl = hs->ssl;
-  // TLS 1.3 uses a different ticket extension.
-  if (hs->min_version >= TLS1_3_VERSION || type == ssl_client_hello_inner ||
-      SSL_get_options(ssl) & SSL_OP_NO_TICKET) {
-    return true;
-  }
-
-  Span<const uint8_t> ticket;
-
-  // Renegotiation does not participate in session resumption. However, still
-  // advertise the extension to avoid potentially breaking servers which carry
-  // over the state from the previous handshake, such as OpenSSL servers
-  // without upstream's 3c3f0259238594d77264a78944d409f2127642c4.
-  if (!ssl->s3->initial_handshake_complete &&
-      ssl->session != nullptr &&
-      !ssl->session->ticket.empty() &&
-      // Don't send TLS 1.3 session tickets in the ticket extension.
-      ssl_session_protocol_version(ssl->session.get()) < TLS1_3_VERSION) {
-    ticket = ssl->session->ticket;
-  }
-
-  CBB ticket_cbb;
-  if (!CBB_add_u16(out, TLSEXT_TYPE_session_ticket) ||
-      !CBB_add_u16_length_prefixed(out, &ticket_cbb) ||
-      !CBB_add_bytes(&ticket_cbb, ticket.data(), ticket.size()) ||
-      !CBB_flush(out)) {
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_ticket_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                         CBS *contents) {
-  SSL *const ssl = hs->ssl;
-  if (contents == NULL) {
-    return true;
-  }
-
-  if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
-    return false;
-  }
-
-  // If |SSL_OP_NO_TICKET| is set then no extension will have been sent and
-  // this function should never be called, even if the server tries to send the
-  // extension.
-  assert((SSL_get_options(ssl) & SSL_OP_NO_TICKET) == 0);
-
-  if (CBS_len(contents) != 0) {
-    return false;
-  }
-
-  hs->ticket_expected = true;
-  return true;
-}
-
-static bool ext_ticket_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  if (!hs->ticket_expected) {
-    return true;
-  }
-
-  // If |SSL_OP_NO_TICKET| is set, |ticket_expected| should never be true.
-  assert((SSL_get_options(hs->ssl) & SSL_OP_NO_TICKET) == 0);
-
-  if (!CBB_add_u16(out, TLSEXT_TYPE_session_ticket) ||
-      !CBB_add_u16(out, 0 /* length */)) {
-    return false;
-  }
-
-  return true;
-}
-
-
-// Signature Algorithms.
-//
-// https://tools.ietf.org/html/rfc5246#section-7.4.1.4.1
-
-static bool ext_sigalgs_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                        CBB *out_compressible,
-                                        ssl_client_hello_type_t type) {
-  if (hs->max_version < TLS1_2_VERSION) {
-    return true;
-  }
-
-  CBB contents, sigalgs_cbb;
-  if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_signature_algorithms) ||
-      !CBB_add_u16_length_prefixed(out_compressible, &contents) ||
-      !CBB_add_u16_length_prefixed(&contents, &sigalgs_cbb) ||
-      !tls12_add_verify_sigalgs(hs, &sigalgs_cbb) ||
-      !CBB_flush(out_compressible)) {
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_sigalgs_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                          CBS *contents) {
-  hs->peer_sigalgs.Reset();
-  if (contents == NULL) {
-    return true;
-  }
-
-  CBS supported_signature_algorithms;
-  if (!CBS_get_u16_length_prefixed(contents, &supported_signature_algorithms) ||
-      CBS_len(contents) != 0 ||
-      !tls1_parse_peer_sigalgs(hs, &supported_signature_algorithms)) {
-    return false;
-  }
-
-  return true;
-}
-
-
-// OCSP Stapling.
-//
-// https://tools.ietf.org/html/rfc6066#section-8
-
-static bool ext_ocsp_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                     CBB *out_compressible,
-                                     ssl_client_hello_type_t type) {
-  if (!hs->config->ocsp_stapling_enabled) {
-    return true;
-  }
-
-  CBB contents;
-  if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_status_request) ||
-      !CBB_add_u16_length_prefixed(out_compressible, &contents) ||
-      !CBB_add_u8(&contents, TLSEXT_STATUSTYPE_ocsp) ||
-      !CBB_add_u16(&contents, 0 /* empty responder ID list */) ||
-      !CBB_add_u16(&contents, 0 /* empty request extensions */) ||
-      !CBB_flush(out_compressible)) {
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_ocsp_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                       CBS *contents) {
-  SSL *const ssl = hs->ssl;
-  if (contents == NULL) {
-    return true;
-  }
-
-  // TLS 1.3 OCSP responses are included in the Certificate extensions.
-  if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
-    return false;
-  }
-
-  // OCSP stapling is forbidden on non-certificate ciphers.
-  if (CBS_len(contents) != 0 ||
-      !ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
-    return false;
-  }
-
-  // Note this does not check for resumption in TLS 1.2. Sending
-  // status_request here does not make sense, but OpenSSL does so and the
-  // specification does not say anything. Tolerate it but ignore it.
-
-  hs->certificate_status_expected = true;
-  return true;
-}
-
-static bool ext_ocsp_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                       CBS *contents) {
-  if (contents == NULL) {
-    return true;
-  }
-
-  uint8_t status_type;
-  if (!CBS_get_u8(contents, &status_type)) {
-    return false;
-  }
-
-  // We cannot decide whether OCSP stapling will occur yet because the correct
-  // SSL_CTX might not have been selected.
-  hs->ocsp_stapling_requested = status_type == TLSEXT_STATUSTYPE_ocsp;
-
-  return true;
-}
-
-static bool ext_ocsp_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  SSL *const ssl = hs->ssl;
-  if (ssl_protocol_version(ssl) >= TLS1_3_VERSION ||
-      !hs->ocsp_stapling_requested || hs->config->cert->ocsp_response == NULL ||
-      ssl->s3->session_reused ||
-      !ssl_cipher_uses_certificate_auth(hs->new_cipher)) {
-    return true;
-  }
-
-  hs->certificate_status_expected = true;
-
-  return CBB_add_u16(out, TLSEXT_TYPE_status_request) &&
-         CBB_add_u16(out, 0 /* length */);
-}
-
-
-// Next protocol negotiation.
-//
-// https://htmlpreview.github.io/?https://github.com/agl/technotes/blob/master/nextprotoneg.html
-
-static bool ext_npn_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                    CBB *out_compressible,
-                                    ssl_client_hello_type_t type) {
-  const SSL *const ssl = hs->ssl;
-  if (ssl->ctx->next_proto_select_cb == NULL ||
-      // Do not allow NPN to change on renegotiation.
-      ssl->s3->initial_handshake_complete ||
-      // NPN is not defined in DTLS or TLS 1.3.
-      SSL_is_dtls(ssl) || hs->min_version >= TLS1_3_VERSION ||
-      type == ssl_client_hello_inner) {
-    return true;
-  }
-
-  if (!CBB_add_u16(out, TLSEXT_TYPE_next_proto_neg) ||
-      !CBB_add_u16(out, 0 /* length */)) {
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_npn_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                      CBS *contents) {
-  SSL *const ssl = hs->ssl;
-  if (contents == NULL) {
-    return true;
-  }
-
-  if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
-    return false;
-  }
-
-  // If any of these are false then we should never have sent the NPN
-  // extension in the ClientHello and thus this function should never have been
-  // called.
-  assert(!ssl->s3->initial_handshake_complete);
-  assert(!SSL_is_dtls(ssl));
-  assert(ssl->ctx->next_proto_select_cb != NULL);
-
-  if (!ssl->s3->alpn_selected.empty()) {
-    // NPN and ALPN may not be negotiated in the same connection.
-    *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-    OPENSSL_PUT_ERROR(SSL, SSL_R_NEGOTIATED_BOTH_NPN_AND_ALPN);
-    return false;
-  }
-
-  const uint8_t *const orig_contents = CBS_data(contents);
-  const size_t orig_len = CBS_len(contents);
-
-  while (CBS_len(contents) != 0) {
-    CBS proto;
-    if (!CBS_get_u8_length_prefixed(contents, &proto) ||
-        CBS_len(&proto) == 0) {
-      return false;
-    }
-  }
-
-  uint8_t *selected;
-  uint8_t selected_len;
-  if (ssl->ctx->next_proto_select_cb(
-          ssl, &selected, &selected_len, orig_contents, orig_len,
-          ssl->ctx->next_proto_select_cb_arg) != SSL_TLSEXT_ERR_OK ||
-      !ssl->s3->next_proto_negotiated.CopyFrom(
-          MakeConstSpan(selected, selected_len))) {
-    *out_alert = SSL_AD_INTERNAL_ERROR;
-    return false;
-  }
-
-  hs->next_proto_neg_seen = true;
-  return true;
-}
-
-static bool ext_npn_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                      CBS *contents) {
-  SSL *const ssl = hs->ssl;
-  if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
-    return true;
-  }
-
-  if (contents != NULL && CBS_len(contents) != 0) {
-    return false;
-  }
-
-  if (contents == NULL ||
-      ssl->s3->initial_handshake_complete ||
-      ssl->ctx->next_protos_advertised_cb == NULL ||
-      SSL_is_dtls(ssl)) {
-    return true;
-  }
-
-  hs->next_proto_neg_seen = true;
-  return true;
-}
-
-static bool ext_npn_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  SSL *const ssl = hs->ssl;
-  // |next_proto_neg_seen| might have been cleared when an ALPN extension was
-  // parsed.
-  if (!hs->next_proto_neg_seen) {
-    return true;
-  }
-
-  const uint8_t *npa;
-  unsigned npa_len;
-
-  if (ssl->ctx->next_protos_advertised_cb(
-          ssl, &npa, &npa_len, ssl->ctx->next_protos_advertised_cb_arg) !=
-      SSL_TLSEXT_ERR_OK) {
-    hs->next_proto_neg_seen = false;
-    return true;
-  }
-
-  CBB contents;
-  if (!CBB_add_u16(out, TLSEXT_TYPE_next_proto_neg) ||
-      !CBB_add_u16_length_prefixed(out, &contents) ||
-      !CBB_add_bytes(&contents, npa, npa_len) ||
-      !CBB_flush(out)) {
-    return false;
-  }
-
-  return true;
-}
-
-
-// Signed certificate timestamps.
-//
-// https://tools.ietf.org/html/rfc6962#section-3.3.1
-
-static bool ext_sct_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                    CBB *out_compressible,
-                                    ssl_client_hello_type_t type) {
-  if (!hs->config->signed_cert_timestamps_enabled) {
-    return true;
-  }
-
-  if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_certificate_timestamp) ||
-      !CBB_add_u16(out_compressible, 0 /* length */)) {
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_sct_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                      CBS *contents) {
-  SSL *const ssl = hs->ssl;
-  if (contents == NULL) {
-    return true;
-  }
-
-  // TLS 1.3 SCTs are included in the Certificate extensions.
-  if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
-    *out_alert = SSL_AD_DECODE_ERROR;
-    return false;
-  }
-
-  // If this is false then we should never have sent the SCT extension in the
-  // ClientHello and thus this function should never have been called.
-  assert(hs->config->signed_cert_timestamps_enabled);
-
-  if (!ssl_is_sct_list_valid(contents)) {
-    *out_alert = SSL_AD_DECODE_ERROR;
-    return false;
-  }
-
-  // Session resumption uses the original session information. The extension
-  // should not be sent on resumption, but RFC 6962 did not make it a
-  // requirement, so tolerate this.
-  //
-  // TODO(davidben): Enforce this anyway.
-  if (!ssl->s3->session_reused) {
-    hs->new_session->signed_cert_timestamp_list.reset(
-        CRYPTO_BUFFER_new_from_CBS(contents, ssl->ctx->pool));
-    if (hs->new_session->signed_cert_timestamp_list == nullptr) {
-      *out_alert = SSL_AD_INTERNAL_ERROR;
-      return false;
-    }
-  }
-
-  return true;
-}
-
-static bool ext_sct_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                      CBS *contents) {
-  if (contents == NULL) {
-    return true;
-  }
-
-  if (CBS_len(contents) != 0) {
-    return false;
-  }
-
-  hs->scts_requested = true;
-  return true;
-}
-
-static bool ext_sct_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  SSL *const ssl = hs->ssl;
-  // The extension shouldn't be sent when resuming sessions.
-  if (ssl_protocol_version(ssl) >= TLS1_3_VERSION || ssl->s3->session_reused ||
-      hs->config->cert->signed_cert_timestamp_list == NULL) {
-    return true;
-  }
-
-  CBB contents;
-  return CBB_add_u16(out, TLSEXT_TYPE_certificate_timestamp) &&
-         CBB_add_u16_length_prefixed(out, &contents) &&
-         CBB_add_bytes(
-             &contents,
-             CRYPTO_BUFFER_data(
-                 hs->config->cert->signed_cert_timestamp_list.get()),
-             CRYPTO_BUFFER_len(
-                 hs->config->cert->signed_cert_timestamp_list.get())) &&
-         CBB_flush(out);
-}
-
-
-// Application-level Protocol Negotiation.
-//
-// https://tools.ietf.org/html/rfc7301
-
-static bool ext_alpn_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                     CBB *out_compressible,
-                                     ssl_client_hello_type_t type) {
-  const SSL *const ssl = hs->ssl;
-  if (hs->config->alpn_client_proto_list.empty() && ssl->quic_method) {
-    // ALPN MUST be used with QUIC.
-    OPENSSL_PUT_ERROR(SSL, SSL_R_NO_APPLICATION_PROTOCOL);
-    return false;
-  }
-
-  if (hs->config->alpn_client_proto_list.empty() ||
-      ssl->s3->initial_handshake_complete) {
-    return true;
-  }
-
-  CBB contents, proto_list;
-  if (!CBB_add_u16(out_compressible,
-                   TLSEXT_TYPE_application_layer_protocol_negotiation) ||
-      !CBB_add_u16_length_prefixed(out_compressible, &contents) ||
-      !CBB_add_u16_length_prefixed(&contents, &proto_list) ||
-      !CBB_add_bytes(&proto_list, hs->config->alpn_client_proto_list.data(),
-                     hs->config->alpn_client_proto_list.size()) ||
-      !CBB_flush(out_compressible)) {
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_alpn_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                       CBS *contents) {
-  SSL *const ssl = hs->ssl;
-  if (contents == NULL) {
-    if (ssl->quic_method) {
-      // ALPN is required when QUIC is used.
-      OPENSSL_PUT_ERROR(SSL, SSL_R_NO_APPLICATION_PROTOCOL);
-      *out_alert = SSL_AD_NO_APPLICATION_PROTOCOL;
-      return false;
-    }
-    return true;
-  }
-
-  assert(!ssl->s3->initial_handshake_complete);
-  assert(!hs->config->alpn_client_proto_list.empty());
-
-  if (hs->next_proto_neg_seen) {
-    // NPN and ALPN may not be negotiated in the same connection.
-    *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-    OPENSSL_PUT_ERROR(SSL, SSL_R_NEGOTIATED_BOTH_NPN_AND_ALPN);
-    return false;
-  }
-
-  // The extension data consists of a ProtocolNameList which must have
-  // exactly one ProtocolName. Each of these is length-prefixed.
-  CBS protocol_name_list, protocol_name;
-  if (!CBS_get_u16_length_prefixed(contents, &protocol_name_list) ||
-      CBS_len(contents) != 0 ||
-      !CBS_get_u8_length_prefixed(&protocol_name_list, &protocol_name) ||
-      // Empty protocol names are forbidden.
-      CBS_len(&protocol_name) == 0 ||
-      CBS_len(&protocol_name_list) != 0) {
-    return false;
-  }
-
-  if (!ssl_is_alpn_protocol_allowed(hs, protocol_name)) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_ALPN_PROTOCOL);
-    *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-    return false;
-  }
-
-  if (!ssl->s3->alpn_selected.CopyFrom(protocol_name)) {
-    *out_alert = SSL_AD_INTERNAL_ERROR;
-    return false;
-  }
-
-  return true;
-}
-
-bool ssl_is_valid_alpn_list(Span<const uint8_t> in) {
-  CBS protocol_name_list = in;
-  if (CBS_len(&protocol_name_list) == 0) {
-    return false;
-  }
-  while (CBS_len(&protocol_name_list) > 0) {
-    CBS protocol_name;
-    if (!CBS_get_u8_length_prefixed(&protocol_name_list, &protocol_name) ||
-        // Empty protocol names are forbidden.
-        CBS_len(&protocol_name) == 0) {
-      return false;
-    }
-  }
-  return true;
-}
-
-bool ssl_is_alpn_protocol_allowed(const SSL_HANDSHAKE *hs,
-                                  Span<const uint8_t> protocol) {
-  if (hs->config->alpn_client_proto_list.empty()) {
-    return false;
-  }
-
-  if (hs->ssl->ctx->allow_unknown_alpn_protos) {
-    return true;
-  }
-
-  // Check that the protocol name is one of the ones we advertised.
-  CBS client_protocol_name_list =
-          MakeConstSpan(hs->config->alpn_client_proto_list),
-      client_protocol_name;
-  while (CBS_len(&client_protocol_name_list) > 0) {
-    if (!CBS_get_u8_length_prefixed(&client_protocol_name_list,
-                                    &client_protocol_name)) {
-      return false;
-    }
-
-    if (client_protocol_name == protocol) {
-      return true;
-    }
-  }
-
-  return false;
-}
-
-bool ssl_negotiate_alpn(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                        const SSL_CLIENT_HELLO *client_hello) {
-  SSL *const ssl = hs->ssl;
-  CBS contents;
-  if (ssl->ctx->alpn_select_cb == NULL ||
-      !ssl_client_hello_get_extension(
-          client_hello, &contents,
-          TLSEXT_TYPE_application_layer_protocol_negotiation)) {
-    if (ssl->quic_method) {
-      // ALPN is required when QUIC is used.
-      OPENSSL_PUT_ERROR(SSL, SSL_R_NO_APPLICATION_PROTOCOL);
-      *out_alert = SSL_AD_NO_APPLICATION_PROTOCOL;
-      return false;
-    }
-    // Ignore ALPN if not configured or no extension was supplied.
-    return true;
-  }
-
-  // ALPN takes precedence over NPN.
-  hs->next_proto_neg_seen = false;
-
-  CBS protocol_name_list;
-  if (!CBS_get_u16_length_prefixed(&contents, &protocol_name_list) ||
-      CBS_len(&contents) != 0 ||
-      !ssl_is_valid_alpn_list(protocol_name_list)) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_PARSE_TLSEXT);
-    *out_alert = SSL_AD_DECODE_ERROR;
-    return false;
-  }
-
-  const uint8_t *selected;
-  uint8_t selected_len;
-  int ret = ssl->ctx->alpn_select_cb(
-      ssl, &selected, &selected_len, CBS_data(&protocol_name_list),
-      CBS_len(&protocol_name_list), ssl->ctx->alpn_select_cb_arg);
-  // ALPN is required when QUIC is used.
-  if (ssl->quic_method &&
-      (ret == SSL_TLSEXT_ERR_NOACK || ret == SSL_TLSEXT_ERR_ALERT_WARNING)) {
-    ret = SSL_TLSEXT_ERR_ALERT_FATAL;
-  }
-  switch (ret) {
-    case SSL_TLSEXT_ERR_OK:
-      if (selected_len == 0) {
-        OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_ALPN_PROTOCOL);
-        *out_alert = SSL_AD_INTERNAL_ERROR;
-        return false;
-      }
-      if (!ssl->s3->alpn_selected.CopyFrom(
-              MakeConstSpan(selected, selected_len))) {
-        *out_alert = SSL_AD_INTERNAL_ERROR;
-        return false;
-      }
-      break;
-    case SSL_TLSEXT_ERR_NOACK:
-    case SSL_TLSEXT_ERR_ALERT_WARNING:
-      break;
-    case SSL_TLSEXT_ERR_ALERT_FATAL:
-      *out_alert = SSL_AD_NO_APPLICATION_PROTOCOL;
-      OPENSSL_PUT_ERROR(SSL, SSL_R_NO_APPLICATION_PROTOCOL);
-      return false;
-    default:
-      // Invalid return value.
-      *out_alert = SSL_AD_INTERNAL_ERROR;
-      OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
-      return false;
-  }
-
-  return true;
-}
-
-static bool ext_alpn_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  SSL *const ssl = hs->ssl;
-  if (ssl->s3->alpn_selected.empty()) {
-    return true;
-  }
-
-  CBB contents, proto_list, proto;
-  if (!CBB_add_u16(out, TLSEXT_TYPE_application_layer_protocol_negotiation) ||
-      !CBB_add_u16_length_prefixed(out, &contents) ||
-      !CBB_add_u16_length_prefixed(&contents, &proto_list) ||
-      !CBB_add_u8_length_prefixed(&proto_list, &proto) ||
-      !CBB_add_bytes(&proto, ssl->s3->alpn_selected.data(),
-                     ssl->s3->alpn_selected.size()) ||
-      !CBB_flush(out)) {
-    return false;
-  }
-
-  return true;
-}
-
-
-// Channel ID.
-//
-// https://tools.ietf.org/html/draft-balfanz-tls-channelid-01
-
-static bool ext_channel_id_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                           CBB *out_compressible,
-                                           ssl_client_hello_type_t type) {
-  const SSL *const ssl = hs->ssl;
-  if (!hs->config->channel_id_private || SSL_is_dtls(ssl) ||
-      // Don't offer Channel ID in ClientHelloOuter. ClientHelloOuter handshakes
-      // are not authenticated for the name that can learn the Channel ID.
-      //
-      // We could alternatively offer the extension but sign with a random key.
-      // For other extensions, we try to align |ssl_client_hello_outer| and
-      // |ssl_client_hello_unencrypted|, to improve the effectiveness of ECH
-      // GREASE. However, Channel ID is deprecated and unlikely to be used with
-      // ECH, so do the simplest thing.
-      type == ssl_client_hello_outer) {
-    return true;
-  }
-
-  if (!CBB_add_u16(out, TLSEXT_TYPE_channel_id) ||
-      !CBB_add_u16(out, 0 /* length */)) {
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_channel_id_parse_serverhello(SSL_HANDSHAKE *hs,
-                                             uint8_t *out_alert,
-                                             CBS *contents) {
-  if (contents == NULL) {
-    return true;
-  }
-
-  assert(!SSL_is_dtls(hs->ssl));
-  assert(hs->config->channel_id_private);
-
-  if (CBS_len(contents) != 0) {
-    return false;
-  }
-
-  hs->channel_id_negotiated = true;
-  return true;
-}
-
-static bool ext_channel_id_parse_clienthello(SSL_HANDSHAKE *hs,
-                                             uint8_t *out_alert,
-                                             CBS *contents) {
-  SSL *const ssl = hs->ssl;
-  if (contents == NULL || !hs->config->channel_id_enabled || SSL_is_dtls(ssl)) {
-    return true;
-  }
-
-  if (CBS_len(contents) != 0) {
-    return false;
-  }
-
-  hs->channel_id_negotiated = true;
-  return true;
-}
-
-static bool ext_channel_id_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  if (!hs->channel_id_negotiated) {
-    return true;
-  }
-
-  if (!CBB_add_u16(out, TLSEXT_TYPE_channel_id) ||
-      !CBB_add_u16(out, 0 /* length */)) {
-    return false;
-  }
-
-  return true;
-}
-
-
-// Secure Real-time Transport Protocol (SRTP) extension.
-//
-// https://tools.ietf.org/html/rfc5764
-
-static bool ext_srtp_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                     CBB *out_compressible,
-                                     ssl_client_hello_type_t type) {
-  const SSL *const ssl = hs->ssl;
-  const STACK_OF(SRTP_PROTECTION_PROFILE) *profiles =
-      SSL_get_srtp_profiles(ssl);
-  if (profiles == NULL ||
-      sk_SRTP_PROTECTION_PROFILE_num(profiles) == 0 ||
-      !SSL_is_dtls(ssl)) {
-    return true;
-  }
-
-  CBB contents, profile_ids;
-  if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_srtp) ||
-      !CBB_add_u16_length_prefixed(out_compressible, &contents) ||
-      !CBB_add_u16_length_prefixed(&contents, &profile_ids)) {
-    return false;
-  }
-
-  for (const SRTP_PROTECTION_PROFILE *profile : profiles) {
-    if (!CBB_add_u16(&profile_ids, profile->id)) {
-      return false;
-    }
-  }
-
-  if (!CBB_add_u8(&contents, 0 /* empty use_mki value */) ||
-      !CBB_flush(out_compressible)) {
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_srtp_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                       CBS *contents) {
-  SSL *const ssl = hs->ssl;
-  if (contents == NULL) {
-    return true;
-  }
-
-  // The extension consists of a u16-prefixed profile ID list containing a
-  // single uint16_t profile ID, then followed by a u8-prefixed srtp_mki field.
-  //
-  // See https://tools.ietf.org/html/rfc5764#section-4.1.1
-  assert(SSL_is_dtls(ssl));
-  CBS profile_ids, srtp_mki;
-  uint16_t profile_id;
-  if (!CBS_get_u16_length_prefixed(contents, &profile_ids) ||
-      !CBS_get_u16(&profile_ids, &profile_id) ||
-      CBS_len(&profile_ids) != 0 ||
-      !CBS_get_u8_length_prefixed(contents, &srtp_mki) ||
-      CBS_len(contents) != 0) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
-    return false;
-  }
-
-  if (CBS_len(&srtp_mki) != 0) {
-    // Must be no MKI, since we never offer one.
-    OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_MKI_VALUE);
-    *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-    return false;
-  }
-
-  // Check to see if the server gave us something we support and offered.
-  for (const SRTP_PROTECTION_PROFILE *profile : SSL_get_srtp_profiles(ssl)) {
-    if (profile->id == profile_id) {
-      ssl->s3->srtp_profile = profile;
-      return true;
-    }
-  }
-
-  OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
-  *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-  return false;
-}
-
-static bool ext_srtp_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                       CBS *contents) {
-  SSL *const ssl = hs->ssl;
-  // DTLS-SRTP is only defined for DTLS.
-  if (contents == NULL || !SSL_is_dtls(ssl)) {
-    return true;
-  }
-
-  CBS profile_ids, srtp_mki;
-  if (!CBS_get_u16_length_prefixed(contents, &profile_ids) ||
-      CBS_len(&profile_ids) < 2 ||
-      !CBS_get_u8_length_prefixed(contents, &srtp_mki) ||
-      CBS_len(contents) != 0) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_BAD_SRTP_PROTECTION_PROFILE_LIST);
-    return false;
-  }
-  // Discard the MKI value for now.
-
-  const STACK_OF(SRTP_PROTECTION_PROFILE) *server_profiles =
-      SSL_get_srtp_profiles(ssl);
-
-  // Pick the server's most preferred profile.
-  for (const SRTP_PROTECTION_PROFILE *server_profile : server_profiles) {
-    CBS profile_ids_tmp;
-    CBS_init(&profile_ids_tmp, CBS_data(&profile_ids), CBS_len(&profile_ids));
-
-    while (CBS_len(&profile_ids_tmp) > 0) {
-      uint16_t profile_id;
-      if (!CBS_get_u16(&profile_ids_tmp, &profile_id)) {
-        return false;
-      }
-
-      if (server_profile->id == profile_id) {
-        ssl->s3->srtp_profile = server_profile;
-        return true;
-      }
-    }
-  }
-
-  return true;
-}
-
-static bool ext_srtp_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  SSL *const ssl = hs->ssl;
-  if (ssl->s3->srtp_profile == NULL) {
-    return true;
-  }
-
-  assert(SSL_is_dtls(ssl));
-  CBB contents, profile_ids;
-  if (!CBB_add_u16(out, TLSEXT_TYPE_srtp) ||
-      !CBB_add_u16_length_prefixed(out, &contents) ||
-      !CBB_add_u16_length_prefixed(&contents, &profile_ids) ||
-      !CBB_add_u16(&profile_ids, ssl->s3->srtp_profile->id) ||
-      !CBB_add_u8(&contents, 0 /* empty MKI */) ||
-      !CBB_flush(out)) {
-    return false;
-  }
-
-  return true;
-}
-
-
-// EC point formats.
-//
-// https://tools.ietf.org/html/rfc4492#section-5.1.2
-
-static bool ext_ec_point_add_extension(const SSL_HANDSHAKE *hs, CBB *out) {
-  CBB contents, formats;
-  if (!CBB_add_u16(out, TLSEXT_TYPE_ec_point_formats) ||
-      !CBB_add_u16_length_prefixed(out, &contents) ||
-      !CBB_add_u8_length_prefixed(&contents, &formats) ||
-      !CBB_add_u8(&formats, TLSEXT_ECPOINTFORMAT_uncompressed) ||
-      !CBB_flush(out)) {
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_ec_point_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                         CBB *out_compressible,
-                                         ssl_client_hello_type_t type) {
-  // The point format extension is unnecessary in TLS 1.3.
-  if (hs->min_version >= TLS1_3_VERSION || type == ssl_client_hello_inner) {
-    return true;
-  }
-
-  return ext_ec_point_add_extension(hs, out);
-}
-
-static bool ext_ec_point_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                           CBS *contents) {
-  if (contents == NULL) {
-    return true;
-  }
-
-  if (ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) {
-    return false;
-  }
-
-  CBS ec_point_format_list;
-  if (!CBS_get_u8_length_prefixed(contents, &ec_point_format_list) ||
-      CBS_len(contents) != 0) {
-    return false;
-  }
-
-  // Per RFC 4492, section 5.1.2, implementations MUST support the uncompressed
-  // point format.
-  if (OPENSSL_memchr(CBS_data(&ec_point_format_list),
-                     TLSEXT_ECPOINTFORMAT_uncompressed,
-                     CBS_len(&ec_point_format_list)) == NULL) {
-    *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_ec_point_parse_clienthello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                          CBS *contents) {
-  if (ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) {
-    return true;
-  }
-
-  return ext_ec_point_parse_serverhello(hs, out_alert, contents);
-}
-
-static bool ext_ec_point_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  SSL *const ssl = hs->ssl;
-  if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
-    return true;
-  }
-
-  const uint32_t alg_k = hs->new_cipher->algorithm_mkey;
-  const uint32_t alg_a = hs->new_cipher->algorithm_auth;
-  const bool using_ecc = (alg_k & SSL_kECDHE) || (alg_a & SSL_aECDSA);
-
-  if (!using_ecc) {
-    return true;
-  }
-
-  return ext_ec_point_add_extension(hs, out);
-}
-
-
-// Pre Shared Key
-//
-// https://tools.ietf.org/html/rfc8446#section-4.2.11
-
-static bool should_offer_psk(const SSL_HANDSHAKE *hs,
-                             ssl_client_hello_type_t type) {
-  const SSL *const ssl = hs->ssl;
-  if (hs->max_version < TLS1_3_VERSION || ssl->session == nullptr ||
-      ssl_session_protocol_version(ssl->session.get()) < TLS1_3_VERSION ||
-      // The ClientHelloOuter cannot include the PSK extension.
-      //
-      // TODO(https://crbug.com/boringssl/275): draft-ietf-tls-esni-10 mandates
-      // this, but it risks breaking the ClientHelloOuter flow on 0-RTT reject.
-      // Later drafts will recommend including a placeholder one, at which point
-      // we will need to synthesize a ticket. See
-      // https://github.com/tlswg/draft-ietf-tls-esni/issues/408
-      type == ssl_client_hello_outer) {
-    return false;
-  }
-
-  // Per RFC 8446 section 4.1.4, skip offering the session if the selected
-  // cipher in HelloRetryRequest does not match. This avoids performing the
-  // transcript hash transformation for multiple hashes.
-  if (ssl->s3->used_hello_retry_request &&
-      ssl->session->cipher->algorithm_prf != hs->new_cipher->algorithm_prf) {
-    return false;
-  }
-
-  return true;
-}
-
-static size_t ext_pre_shared_key_clienthello_length(
-    const SSL_HANDSHAKE *hs, ssl_client_hello_type_t type) {
-  const SSL *const ssl = hs->ssl;
-  if (!should_offer_psk(hs, type)) {
-    return 0;
-  }
-
-  size_t binder_len = EVP_MD_size(ssl_session_get_digest(ssl->session.get()));
-  return 15 + ssl->session->ticket.size() + binder_len;
-}
-
-static bool ext_pre_shared_key_add_clienthello(const SSL_HANDSHAKE *hs,
-                                               CBB *out, bool *out_needs_binder,
-                                               ssl_client_hello_type_t type) {
-  const SSL *const ssl = hs->ssl;
-  *out_needs_binder = false;
-  if (!should_offer_psk(hs, type)) {
-    return true;
-  }
-
-  struct OPENSSL_timeval now;
-  ssl_get_current_time(ssl, &now);
-  uint32_t ticket_age = 1000 * (now.tv_sec - ssl->session->time);
-  uint32_t obfuscated_ticket_age = ticket_age + ssl->session->ticket_age_add;
-
-  // Fill in a placeholder zero binder of the appropriate length. It will be
-  // computed and filled in later after length prefixes are computed.
-  uint8_t zero_binder[EVP_MAX_MD_SIZE] = {0};
-  size_t binder_len = EVP_MD_size(ssl_session_get_digest(ssl->session.get()));
-
-  CBB contents, identity, ticket, binders, binder;
-  if (!CBB_add_u16(out, TLSEXT_TYPE_pre_shared_key) ||
-      !CBB_add_u16_length_prefixed(out, &contents) ||
-      !CBB_add_u16_length_prefixed(&contents, &identity) ||
-      !CBB_add_u16_length_prefixed(&identity, &ticket) ||
-      !CBB_add_bytes(&ticket, ssl->session->ticket.data(),
-                     ssl->session->ticket.size()) ||
-      !CBB_add_u32(&identity, obfuscated_ticket_age) ||
-      !CBB_add_u16_length_prefixed(&contents, &binders) ||
-      !CBB_add_u8_length_prefixed(&binders, &binder) ||
-      !CBB_add_bytes(&binder, zero_binder, binder_len)) {
-    return false;
-  }
-
-  *out_needs_binder = true;
-  return CBB_flush(out);
-}
-
-bool ssl_ext_pre_shared_key_parse_serverhello(SSL_HANDSHAKE *hs,
-                                              uint8_t *out_alert,
-                                              CBS *contents) {
-  uint16_t psk_id;
-  if (!CBS_get_u16(contents, &psk_id) ||
-      CBS_len(contents) != 0) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-    *out_alert = SSL_AD_DECODE_ERROR;
-    return false;
-  }
-
-  // We only advertise one PSK identity, so the only legal index is zero.
-  if (psk_id != 0) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_IDENTITY_NOT_FOUND);
-    *out_alert = SSL_AD_UNKNOWN_PSK_IDENTITY;
-    return false;
-  }
-
-  return true;
-}
-
-bool ssl_ext_pre_shared_key_parse_clienthello(
-    SSL_HANDSHAKE *hs, CBS *out_ticket, CBS *out_binders,
-    uint32_t *out_obfuscated_ticket_age, uint8_t *out_alert,
-    const SSL_CLIENT_HELLO *client_hello, CBS *contents) {
-  // Verify that the pre_shared_key extension is the last extension in
-  // ClientHello.
-  if (CBS_data(contents) + CBS_len(contents) !=
-      client_hello->extensions + client_hello->extensions_len) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_PRE_SHARED_KEY_MUST_BE_LAST);
-    *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-    return false;
-  }
-
-  // We only process the first PSK identity since we don't support pure PSK.
-  CBS identities, binders;
-  if (!CBS_get_u16_length_prefixed(contents, &identities) ||
-      !CBS_get_u16_length_prefixed(&identities, out_ticket) ||
-      !CBS_get_u32(&identities, out_obfuscated_ticket_age) ||
-      !CBS_get_u16_length_prefixed(contents, &binders) ||
-      CBS_len(&binders) == 0 ||
-      CBS_len(contents) != 0) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-    *out_alert = SSL_AD_DECODE_ERROR;
-    return false;
-  }
-
-  *out_binders = binders;
-
-  // Check the syntax of the remaining identities, but do not process them.
-  size_t num_identities = 1;
-  while (CBS_len(&identities) != 0) {
-    CBS unused_ticket;
-    uint32_t unused_obfuscated_ticket_age;
-    if (!CBS_get_u16_length_prefixed(&identities, &unused_ticket) ||
-        !CBS_get_u32(&identities, &unused_obfuscated_ticket_age)) {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-      *out_alert = SSL_AD_DECODE_ERROR;
-      return false;
-    }
-
-    num_identities++;
-  }
-
-  // Check the syntax of the binders. The value will be checked later if
-  // resuming.
-  size_t num_binders = 0;
-  while (CBS_len(&binders) != 0) {
-    CBS binder;
-    if (!CBS_get_u8_length_prefixed(&binders, &binder)) {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-      *out_alert = SSL_AD_DECODE_ERROR;
-      return false;
-    }
-
-    num_binders++;
-  }
-
-  if (num_identities != num_binders) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_PSK_IDENTITY_BINDER_COUNT_MISMATCH);
-    *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-    return false;
-  }
-
-  return true;
-}
-
-bool ssl_ext_pre_shared_key_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  if (!hs->ssl->s3->session_reused) {
-    return true;
-  }
-
-  CBB contents;
-  if (!CBB_add_u16(out, TLSEXT_TYPE_pre_shared_key) ||
-      !CBB_add_u16_length_prefixed(out, &contents) ||
-      // We only consider the first identity for resumption
-      !CBB_add_u16(&contents, 0) ||
-      !CBB_flush(out)) {
-    return false;
-  }
-
-  return true;
-}
-
-
-// Pre-Shared Key Exchange Modes
-//
-// https://tools.ietf.org/html/rfc8446#section-4.2.9
-
-static bool ext_psk_key_exchange_modes_add_clienthello(
-    const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible,
-    ssl_client_hello_type_t type) {
-  if (hs->max_version < TLS1_3_VERSION) {
-    return true;
-  }
-
-  CBB contents, ke_modes;
-  if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_psk_key_exchange_modes) ||
-      !CBB_add_u16_length_prefixed(out_compressible, &contents) ||
-      !CBB_add_u8_length_prefixed(&contents, &ke_modes) ||
-      !CBB_add_u8(&ke_modes, SSL_PSK_DHE_KE)) {
-    return false;
-  }
-
-  return CBB_flush(out_compressible);
-}
-
-static bool ext_psk_key_exchange_modes_parse_clienthello(SSL_HANDSHAKE *hs,
-                                                         uint8_t *out_alert,
-                                                         CBS *contents) {
-  if (contents == NULL) {
-    return true;
-  }
-
-  CBS ke_modes;
-  if (!CBS_get_u8_length_prefixed(contents, &ke_modes) ||
-      CBS_len(&ke_modes) == 0 ||
-      CBS_len(contents) != 0) {
-    *out_alert = SSL_AD_DECODE_ERROR;
-    return false;
-  }
-
-  // We only support tickets with PSK_DHE_KE.
-  hs->accept_psk_mode = OPENSSL_memchr(CBS_data(&ke_modes), SSL_PSK_DHE_KE,
-                                       CBS_len(&ke_modes)) != NULL;
-
-  return true;
-}
-
-
-// Early Data Indication
-//
-// https://tools.ietf.org/html/rfc8446#section-4.2.10
-
-static bool ext_early_data_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                           CBB *out_compressible,
-                                           ssl_client_hello_type_t type) {
-  const SSL *const ssl = hs->ssl;
-  // The second ClientHello never offers early data, and we must have already
-  // filled in |early_data_reason| by this point.
-  if (ssl->s3->used_hello_retry_request) {
-    assert(ssl->s3->early_data_reason != ssl_early_data_unknown);
-    return true;
-  }
-
-  if (!hs->early_data_offered) {
-    return true;
-  }
-
-  // If offering ECH, the extension only applies to ClientHelloInner, but we
-  // send the extension in both ClientHellos. This ensures that, if the server
-  // handshakes with ClientHelloOuter, it can skip past early data. See
-  // https://github.com/tlswg/draft-ietf-tls-esni/pull/415
-  //
-  // TODO(https://crbug.com/boringssl/275): Replace this with a reference to the
-  // right section in the next draft.
-  if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_early_data) ||
-      !CBB_add_u16(out_compressible, 0) ||
-      !CBB_flush(out_compressible)) {
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_early_data_parse_serverhello(SSL_HANDSHAKE *hs,
-                                             uint8_t *out_alert,
-                                             CBS *contents) {
-  SSL *const ssl = hs->ssl;
-  if (contents == NULL) {
-    if (hs->early_data_offered && !ssl->s3->used_hello_retry_request) {
-      ssl->s3->early_data_reason = ssl->s3->session_reused
-                                       ? ssl_early_data_peer_declined
-                                       : ssl_early_data_session_not_resumed;
-    } else {
-      // We already filled in |early_data_reason| when declining to offer 0-RTT
-      // or handling the implicit HelloRetryRequest reject.
-      assert(ssl->s3->early_data_reason != ssl_early_data_unknown);
-    }
-    return true;
-  }
-
-  // If we received an HRR, the second ClientHello never offers early data, so
-  // the extensions logic will automatically reject early data extensions as
-  // unsolicited. This covered by the ServerAcceptsEarlyDataOnHRR test.
-  assert(!ssl->s3->used_hello_retry_request);
-
-  if (CBS_len(contents) != 0) {
-    *out_alert = SSL_AD_DECODE_ERROR;
-    return false;
-  }
-
-  if (!ssl->s3->session_reused) {
-    *out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
-    OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
-    return false;
-  }
-
-  ssl->s3->early_data_reason = ssl_early_data_accepted;
-  ssl->s3->early_data_accepted = true;
-  return true;
-}
-
-static bool ext_early_data_parse_clienthello(SSL_HANDSHAKE *hs,
-                                             uint8_t *out_alert, CBS *contents) {
-  SSL *const ssl = hs->ssl;
-  if (contents == NULL ||
-      ssl_protocol_version(ssl) < TLS1_3_VERSION) {
-    return true;
-  }
-
-  if (CBS_len(contents) != 0) {
-    *out_alert = SSL_AD_DECODE_ERROR;
-    return false;
-  }
-
-  hs->early_data_offered = true;
-  return true;
-}
-
-static bool ext_early_data_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  if (!hs->ssl->s3->early_data_accepted) {
-    return true;
-  }
-
-  if (!CBB_add_u16(out, TLSEXT_TYPE_early_data) ||
-      !CBB_add_u16(out, 0) ||
-      !CBB_flush(out)) {
-    return false;
-  }
-
-  return true;
-}
-
-
-// Key Share
-//
-// https://tools.ietf.org/html/rfc8446#section-4.2.8
-
-bool ssl_setup_key_shares(SSL_HANDSHAKE *hs, uint16_t override_group_id) {
-  SSL *const ssl = hs->ssl;
-  hs->key_shares[0].reset();
-  hs->key_shares[1].reset();
-  hs->key_share_bytes.Reset();
-
-  if (hs->max_version < TLS1_3_VERSION) {
-    return true;
-  }
-
-  bssl::ScopedCBB cbb;
-  if (!CBB_init(cbb.get(), 64)) {
-    return false;
-  }
-
-  if (override_group_id == 0 && ssl->ctx->grease_enabled) {
-    // Add a fake group. See RFC 8701.
-    if (!CBB_add_u16(cbb.get(), ssl_get_grease_value(hs, ssl_grease_group)) ||
-        !CBB_add_u16(cbb.get(), 1 /* length */) ||
-        !CBB_add_u8(cbb.get(), 0 /* one byte key share */)) {
-      return false;
-    }
-  }
-
-  uint16_t group_id = override_group_id;
-  uint16_t second_group_id = 0;
-  if (override_group_id == 0) {
-    // Predict the most preferred group.
-    Span<const uint16_t> groups = tls1_get_grouplist(hs);
-    if (groups.empty()) {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_NO_GROUPS_SPECIFIED);
-      return false;
-    }
-
-    group_id = groups[0];
-
-    if (is_post_quantum_group(group_id) && groups.size() >= 2) {
-      // CECPQ2(b) is not sent as the only initial key share. We'll include the
-      // 2nd preference group too to avoid round-trips.
-      second_group_id = groups[1];
-      assert(second_group_id != group_id);
-    }
-  }
-
-  CBB key_exchange;
-  hs->key_shares[0] = SSLKeyShare::Create(group_id);
-  if (!hs->key_shares[0] ||  //
-      !CBB_add_u16(cbb.get(), group_id) ||
-      !CBB_add_u16_length_prefixed(cbb.get(), &key_exchange) ||
-      !hs->key_shares[0]->Offer(&key_exchange)) {
-    return false;
-  }
-
-  if (second_group_id != 0) {
-    hs->key_shares[1] = SSLKeyShare::Create(second_group_id);
-    if (!hs->key_shares[1] ||  //
-        !CBB_add_u16(cbb.get(), second_group_id) ||
-        !CBB_add_u16_length_prefixed(cbb.get(), &key_exchange) ||
-        !hs->key_shares[1]->Offer(&key_exchange)) {
-      return false;
-    }
-  }
-
-  return CBBFinishArray(cbb.get(), &hs->key_share_bytes);
-}
-
-static bool ext_key_share_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                          CBB *out_compressible,
-                                          ssl_client_hello_type_t type) {
-  if (hs->max_version < TLS1_3_VERSION) {
-    return true;
-  }
-
-  assert(!hs->key_share_bytes.empty());
-  CBB contents, kse_bytes;
-  if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_key_share) ||
-      !CBB_add_u16_length_prefixed(out_compressible, &contents) ||
-      !CBB_add_u16_length_prefixed(&contents, &kse_bytes) ||
-      !CBB_add_bytes(&kse_bytes, hs->key_share_bytes.data(),
-                     hs->key_share_bytes.size()) ||
-      !CBB_flush(out_compressible)) {
-    return false;
-  }
-
-  return true;
-}
-
-bool ssl_ext_key_share_parse_serverhello(SSL_HANDSHAKE *hs,
-                                         Array<uint8_t> *out_secret,
-                                         uint8_t *out_alert, CBS *contents) {
-  CBS peer_key;
-  uint16_t group_id;
-  if (!CBS_get_u16(contents, &group_id) ||
-      !CBS_get_u16_length_prefixed(contents, &peer_key) ||
-      CBS_len(contents) != 0) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-    *out_alert = SSL_AD_DECODE_ERROR;
-    return false;
-  }
-
-  SSLKeyShare *key_share = hs->key_shares[0].get();
-  if (key_share->GroupID() != group_id) {
-    if (!hs->key_shares[1] || hs->key_shares[1]->GroupID() != group_id) {
-      *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-      OPENSSL_PUT_ERROR(SSL, SSL_R_WRONG_CURVE);
-      return false;
-    }
-    key_share = hs->key_shares[1].get();
-  }
-
-  if (!key_share->Finish(out_secret, out_alert, peer_key)) {
-    *out_alert = SSL_AD_INTERNAL_ERROR;
-    return false;
-  }
-
-  hs->new_session->group_id = group_id;
-  hs->key_shares[0].reset();
-  hs->key_shares[1].reset();
-  return true;
-}
-
-bool ssl_ext_key_share_parse_clienthello(SSL_HANDSHAKE *hs, bool *out_found,
-                                         Span<const uint8_t> *out_peer_key,
-                                         uint8_t *out_alert,
-                                         const SSL_CLIENT_HELLO *client_hello) {
-  // We only support connections that include an ECDHE key exchange.
-  CBS contents;
-  if (!ssl_client_hello_get_extension(client_hello, &contents,
-                                      TLSEXT_TYPE_key_share)) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_KEY_SHARE);
-    *out_alert = SSL_AD_MISSING_EXTENSION;
-    return false;
-  }
-
-  CBS key_shares;
-  if (!CBS_get_u16_length_prefixed(&contents, &key_shares) ||
-      CBS_len(&contents) != 0) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-    return false;
-  }
-
-  // Find the corresponding key share.
-  const uint16_t group_id = hs->new_session->group_id;
-  CBS peer_key;
-  CBS_init(&peer_key, nullptr, 0);
-  while (CBS_len(&key_shares) > 0) {
-    uint16_t id;
-    CBS peer_key_tmp;
-    if (!CBS_get_u16(&key_shares, &id) ||
-        !CBS_get_u16_length_prefixed(&key_shares, &peer_key_tmp) ||
-        CBS_len(&peer_key_tmp) == 0) {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-      return false;
-    }
-
-    if (id == group_id) {
-      if (CBS_len(&peer_key) != 0) {
-        OPENSSL_PUT_ERROR(SSL, SSL_R_DUPLICATE_KEY_SHARE);
-        *out_alert = SSL_AD_ILLEGAL_PARAMETER;
-        return false;
-      }
-
-      peer_key = peer_key_tmp;
-      // Continue parsing the structure to keep peers honest.
-    }
-  }
-
-  if (out_peer_key != nullptr) {
-    *out_peer_key = peer_key;
-  }
-  *out_found = CBS_len(&peer_key) != 0;
-  return true;
-}
-
-bool ssl_ext_key_share_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  CBB kse_bytes, public_key;
-  if (!CBB_add_u16(out, TLSEXT_TYPE_key_share) ||
-      !CBB_add_u16_length_prefixed(out, &kse_bytes) ||
-      !CBB_add_u16(&kse_bytes, hs->new_session->group_id) ||
-      !CBB_add_u16_length_prefixed(&kse_bytes, &public_key) ||
-      !CBB_add_bytes(&public_key, hs->ecdh_public_key.data(),
-                     hs->ecdh_public_key.size()) ||
-      !CBB_flush(out)) {
-    return false;
-  }
-  return true;
-}
-
-
-// Supported Versions
-//
-// https://tools.ietf.org/html/rfc8446#section-4.2.1
-
-static bool ext_supported_versions_add_clienthello(
-    const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible,
-    ssl_client_hello_type_t type) {
-  const SSL *const ssl = hs->ssl;
-  if (hs->max_version <= TLS1_2_VERSION) {
-    return true;
-  }
-
-  // supported_versions is compressible in ECH if ClientHelloOuter already
-  // requires TLS 1.3. Otherwise the extensions differ in the older versions.
-  if (hs->min_version >= TLS1_3_VERSION) {
-    out = out_compressible;
-  }
-
-  CBB contents, versions;
-  if (!CBB_add_u16(out, TLSEXT_TYPE_supported_versions) ||
-      !CBB_add_u16_length_prefixed(out, &contents) ||
-      !CBB_add_u8_length_prefixed(&contents, &versions)) {
-    return false;
-  }
-
-  // Add a fake version. See RFC 8701.
-  if (ssl->ctx->grease_enabled &&
-      !CBB_add_u16(&versions, ssl_get_grease_value(hs, ssl_grease_version))) {
-    return false;
-  }
-
-  // Encrypted ClientHellos requires TLS 1.3 or later.
-  uint16_t extra_min_version =
-      type == ssl_client_hello_inner ? TLS1_3_VERSION : 0;
-  if (!ssl_add_supported_versions(hs, &versions, extra_min_version) ||
-      !CBB_flush(out)) {
-    return false;
-  }
-
-  return true;
-}
-
-
-// Cookie
-//
-// https://tools.ietf.org/html/rfc8446#section-4.2.2
-
-static bool ext_cookie_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                       CBB *out_compressible,
-                                       ssl_client_hello_type_t type) {
-  if (hs->cookie.empty()) {
-    return true;
-  }
-
-  CBB contents, cookie;
-  if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_cookie) ||
-      !CBB_add_u16_length_prefixed(out_compressible, &contents) ||
-      !CBB_add_u16_length_prefixed(&contents, &cookie) ||
-      !CBB_add_bytes(&cookie, hs->cookie.data(), hs->cookie.size()) ||
-      !CBB_flush(out_compressible)) {
-    return false;
-  }
-
-  return true;
-}
-
-
-// Supported Groups
-//
-// https://tools.ietf.org/html/rfc4492#section-5.1.1
-// https://tools.ietf.org/html/rfc8446#section-4.2.7
-
-static bool ext_supported_groups_add_clienthello(const SSL_HANDSHAKE *hs,
-                                                 CBB *out,
-                                                 CBB *out_compressible,
-                                                 ssl_client_hello_type_t type) {
-  const SSL *const ssl = hs->ssl;
-  CBB contents, groups_bytes;
-  if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_supported_groups) ||
-      !CBB_add_u16_length_prefixed(out_compressible, &contents) ||
-      !CBB_add_u16_length_prefixed(&contents, &groups_bytes)) {
-    return false;
-  }
-
-  // Add a fake group. See RFC 8701.
-  if (ssl->ctx->grease_enabled &&
-      !CBB_add_u16(&groups_bytes,
-                   ssl_get_grease_value(hs, ssl_grease_group))) {
-    return false;
-  }
-
-  for (uint16_t group : tls1_get_grouplist(hs)) {
-    if (is_post_quantum_group(group) &&
-        hs->max_version < TLS1_3_VERSION) {
-      continue;
-    }
-    if (!CBB_add_u16(&groups_bytes, group)) {
-      return false;
-    }
-  }
-
-  return CBB_flush(out_compressible);
-}
-
-static bool ext_supported_groups_parse_serverhello(SSL_HANDSHAKE *hs,
-                                                   uint8_t *out_alert,
-                                                   CBS *contents) {
-  // This extension is not expected to be echoed by servers in TLS 1.2, but some
-  // BigIP servers send it nonetheless, so do not enforce this.
-  return true;
-}
-
-static bool parse_u16_array(const CBS *cbs, Array<uint16_t> *out) {
-  CBS copy = *cbs;
-  if ((CBS_len(&copy) & 1) != 0) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-    return false;
-  }
-
-  Array<uint16_t> ret;
-  if (!ret.Init(CBS_len(&copy) / 2)) {
-    return false;
-  }
-  for (size_t i = 0; i < ret.size(); i++) {
-    if (!CBS_get_u16(&copy, &ret[i])) {
-      OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
-      return false;
-    }
-  }
-
-  assert(CBS_len(&copy) == 0);
-  *out = std::move(ret);
-  return 1;
-}
-
-static bool ext_supported_groups_parse_clienthello(SSL_HANDSHAKE *hs,
-                                                  uint8_t *out_alert,
-                                                   CBS *contents) {
-  if (contents == NULL) {
-    return true;
-  }
-
-  CBS supported_group_list;
-  if (!CBS_get_u16_length_prefixed(contents, &supported_group_list) ||
-      CBS_len(&supported_group_list) == 0 ||
-      CBS_len(contents) != 0 ||
-      !parse_u16_array(&supported_group_list, &hs->peer_supported_group_list)) {
-    return false;
-  }
-
-  return true;
-}
-
-
-// QUIC Transport Parameters
-
-static bool ext_quic_transport_params_add_clienthello_impl(
-    const SSL_HANDSHAKE *hs, CBB *out, bool use_legacy_codepoint) {
-  if (hs->config->quic_transport_params.empty() && !hs->ssl->quic_method) {
-    return true;
-  }
-  if (hs->config->quic_transport_params.empty() || !hs->ssl->quic_method) {
-    // QUIC Transport Parameters must be sent over QUIC, and they must not be
-    // sent over non-QUIC transports. If transport params are set, then
-    // SSL(_CTX)_set_quic_method must also be called.
-    OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_TRANSPORT_PARAMETERS_MISCONFIGURED);
-    return false;
-  }
-  assert(hs->min_version > TLS1_2_VERSION);
-  if (use_legacy_codepoint != hs->config->quic_use_legacy_codepoint) {
-    // Do nothing, we'll send the other codepoint.
-    return true;
-  }
-
-  uint16_t extension_type = TLSEXT_TYPE_quic_transport_parameters;
-  if (hs->config->quic_use_legacy_codepoint) {
-    extension_type = TLSEXT_TYPE_quic_transport_parameters_legacy;
-  }
-
-  CBB contents;
-  if (!CBB_add_u16(out, extension_type) ||
-      !CBB_add_u16_length_prefixed(out, &contents) ||
-      !CBB_add_bytes(&contents, hs->config->quic_transport_params.data(),
-                     hs->config->quic_transport_params.size()) ||
-      !CBB_flush(out)) {
-    return false;
-  }
-  return true;
-}
-
-static bool ext_quic_transport_params_add_clienthello(
-    const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible,
-    ssl_client_hello_type_t type) {
-  return ext_quic_transport_params_add_clienthello_impl(
-      hs, out_compressible, /*use_legacy_codepoint=*/false);
-}
-
-static bool ext_quic_transport_params_add_clienthello_legacy(
-    const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible,
-    ssl_client_hello_type_t type) {
-  return ext_quic_transport_params_add_clienthello_impl(
-      hs, out_compressible, /*use_legacy_codepoint=*/true);
-}
-
-static bool ext_quic_transport_params_parse_serverhello_impl(
-    SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents,
-    bool used_legacy_codepoint) {
-  SSL *const ssl = hs->ssl;
-  if (contents == nullptr) {
-    if (used_legacy_codepoint != hs->config->quic_use_legacy_codepoint) {
-      // Silently ignore because we expect the other QUIC codepoint.
-      return true;
-    }
-    if (!ssl->quic_method) {
-      return true;
-    }
-    *out_alert = SSL_AD_MISSING_EXTENSION;
-    return false;
-  }
-  // The extensions parser will check for unsolicited extensions before
-  // calling the callback.
-  assert(ssl->quic_method != nullptr);
-  assert(ssl_protocol_version(ssl) == TLS1_3_VERSION);
-  assert(used_legacy_codepoint == hs->config->quic_use_legacy_codepoint);
-  return ssl->s3->peer_quic_transport_params.CopyFrom(*contents);
-}
-
-static bool ext_quic_transport_params_parse_serverhello(SSL_HANDSHAKE *hs,
-                                                        uint8_t *out_alert,
-                                                        CBS *contents) {
-  return ext_quic_transport_params_parse_serverhello_impl(
-      hs, out_alert, contents, /*used_legacy_codepoint=*/false);
-}
-
-static bool ext_quic_transport_params_parse_serverhello_legacy(
-    SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) {
-  return ext_quic_transport_params_parse_serverhello_impl(
-      hs, out_alert, contents, /*used_legacy_codepoint=*/true);
-}
-
-static bool ext_quic_transport_params_parse_clienthello_impl(
-    SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents,
-    bool used_legacy_codepoint) {
-  SSL *const ssl = hs->ssl;
-  if (!contents) {
-    if (!ssl->quic_method) {
-      if (hs->config->quic_transport_params.empty()) {
-        return true;
-      }
-      // QUIC transport parameters must not be set if |ssl| is not configured
-      // for QUIC.
-      OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_TRANSPORT_PARAMETERS_MISCONFIGURED);
-      *out_alert = SSL_AD_INTERNAL_ERROR;
-      return false;
-    }
-    if (used_legacy_codepoint != hs->config->quic_use_legacy_codepoint) {
-      // Silently ignore because we expect the other QUIC codepoint.
-      return true;
-    }
-    *out_alert = SSL_AD_MISSING_EXTENSION;
-    return false;
-  }
-  if (!ssl->quic_method) {
-    if (used_legacy_codepoint) {
-      // Ignore the legacy private-use codepoint because that could be sent
-      // to mean something else than QUIC transport parameters.
-      return true;
-    }
-    // Fail if we received the codepoint registered with IANA for QUIC
-    // because that is not allowed outside of QUIC.
-    *out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
-    return false;
-  }
-  assert(ssl_protocol_version(ssl) == TLS1_3_VERSION);
-  if (used_legacy_codepoint != hs->config->quic_use_legacy_codepoint) {
-    // Silently ignore because we expect the other QUIC codepoint.
-    return true;
-  }
-  return ssl->s3->peer_quic_transport_params.CopyFrom(*contents);
-}
-
-static bool ext_quic_transport_params_parse_clienthello(SSL_HANDSHAKE *hs,
-                                                        uint8_t *out_alert,
-                                                        CBS *contents) {
-  return ext_quic_transport_params_parse_clienthello_impl(
-      hs, out_alert, contents, /*used_legacy_codepoint=*/false);
-}
-
-static bool ext_quic_transport_params_parse_clienthello_legacy(
-    SSL_HANDSHAKE *hs, uint8_t *out_alert, CBS *contents) {
-  return ext_quic_transport_params_parse_clienthello_impl(
-      hs, out_alert, contents, /*used_legacy_codepoint=*/true);
-}
-
-static bool ext_quic_transport_params_add_serverhello_impl(
-    SSL_HANDSHAKE *hs, CBB *out, bool use_legacy_codepoint) {
-  if (hs->ssl->quic_method == nullptr && use_legacy_codepoint) {
-    // Ignore the legacy private-use codepoint because that could be sent
-    // to mean something else than QUIC transport parameters.
-    return true;
-  }
-  assert(hs->ssl->quic_method != nullptr);
-  if (hs->config->quic_transport_params.empty()) {
-    // Transport parameters must be set when using QUIC.
-    OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_TRANSPORT_PARAMETERS_MISCONFIGURED);
-    return false;
-  }
-  if (use_legacy_codepoint != hs->config->quic_use_legacy_codepoint) {
-    // Do nothing, we'll send the other codepoint.
-    return true;
-  }
-
-  uint16_t extension_type = TLSEXT_TYPE_quic_transport_parameters;
-  if (hs->config->quic_use_legacy_codepoint) {
-    extension_type = TLSEXT_TYPE_quic_transport_parameters_legacy;
-  }
-
-  CBB contents;
-  if (!CBB_add_u16(out, extension_type) ||
-      !CBB_add_u16_length_prefixed(out, &contents) ||
-      !CBB_add_bytes(&contents, hs->config->quic_transport_params.data(),
-                     hs->config->quic_transport_params.size()) ||
-      !CBB_flush(out)) {
-    return false;
-  }
-
-  return true;
-}
-
-static bool ext_quic_transport_params_add_serverhello(SSL_HANDSHAKE *hs,
-                                                      CBB *out) {
-  return ext_quic_transport_params_add_serverhello_impl(
-      hs, out, /*use_legacy_codepoint=*/false);
-}
-
-static bool ext_quic_transport_params_add_serverhello_legacy(SSL_HANDSHAKE *hs,
-                                                             CBB *out) {
-  return ext_quic_transport_params_add_serverhello_impl(
-      hs, out, /*use_legacy_codepoint=*/true);
-}
-
-// Delegated credentials.
-//
-// https://tools.ietf.org/html/draft-ietf-tls-subcerts
-
-static bool ext_delegated_credential_add_clienthello(
-    const SSL_HANDSHAKE *hs, CBB *out, CBB *out_compressible,
-    ssl_client_hello_type_t type) {
-  return true;
-}
-
-static bool ext_delegated_credential_parse_clienthello(SSL_HANDSHAKE *hs,
-                                                       uint8_t *out_alert,
-                                                       CBS *contents) {
-  if (contents == nullptr || ssl_protocol_version(hs->ssl) < TLS1_3_VERSION) {
-    // Don't use delegated credentials unless we're negotiating TLS 1.3 or
-    // higher.
-    return true;
-  }
-
-  // The contents of the extension are the signature algorithms the client will
-  // accept for a delegated credential.
-  CBS sigalg_list;
-  if (!CBS_get_u16_length_prefixed(contents, &sigalg_list) ||
-      CBS_len(&sigalg_list) == 0 ||
-      CBS_len(contents) != 0 ||
-      !parse_u16_array(&sigalg_list, &hs->peer_delegated_credential_sigalgs)) {
-    return false;
-  }
-
-  hs->delegated_credential_requested = true;
-  return true;
-}
-
-// Certificate compression
-
-static bool cert_compression_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                             CBB *out_compressible,
-                                             ssl_client_hello_type_t type) {
-  bool first = true;
-  CBB contents, algs;
-
-  for (const auto &alg : hs->ssl->ctx->cert_compression_algs) {
-    if (alg.decompress == nullptr) {
-      continue;
-    }
-
-    if (first &&
-        (!CBB_add_u16(out_compressible, TLSEXT_TYPE_cert_compression) ||
-         !CBB_add_u16_length_prefixed(out_compressible, &contents) ||
-         !CBB_add_u8_length_prefixed(&contents, &algs))) {
-      return false;
-    }
-    first = false;
-    if (!CBB_add_u16(&algs, alg.alg_id)) {
-      return false;
-    }
-  }
-
-  return first || CBB_flush(out_compressible);
-}
-
-static bool cert_compression_parse_serverhello(SSL_HANDSHAKE *hs,
-                                               uint8_t *out_alert,
-                                               CBS *contents) {
-  if (contents == nullptr) {
-    return true;
-  }
-
-  // The server may not echo this extension. Any server to client negotiation is
-  // advertised in the CertificateRequest message.
-  return false;
-}
-
-static bool cert_compression_parse_clienthello(SSL_HANDSHAKE *hs,
-                                               uint8_t *out_alert,
-                                               CBS *contents) {
-  if (contents == nullptr) {
-    return true;
-  }
-
-  const SSL_CTX *ctx = hs->ssl->ctx.get();
-  const size_t num_algs = ctx->cert_compression_algs.size();
-
-  CBS alg_ids;
-  if (!CBS_get_u8_length_prefixed(contents, &alg_ids) ||
-      CBS_len(contents) != 0 ||
-      CBS_len(&alg_ids) == 0 ||
-      CBS_len(&alg_ids) % 2 == 1) {
-    return false;
-  }
-
-  const size_t num_given_alg_ids = CBS_len(&alg_ids) / 2;
-  Array<uint16_t> given_alg_ids;
-  if (!given_alg_ids.Init(num_given_alg_ids)) {
-    return false;
-  }
-
-  size_t best_index = num_algs;
-  size_t given_alg_idx = 0;
-
-  while (CBS_len(&alg_ids) > 0) {
-    uint16_t alg_id;
-    if (!CBS_get_u16(&alg_ids, &alg_id)) {
-      return false;
-    }
-
-    given_alg_ids[given_alg_idx++] = alg_id;
-
-    for (size_t i = 0; i < num_algs; i++) {
-      const auto &alg = ctx->cert_compression_algs[i];
-      if (alg.alg_id == alg_id && alg.compress != nullptr) {
-        if (i < best_index) {
-          best_index = i;
-        }
-        break;
-      }
-    }
-  }
-
-  qsort(given_alg_ids.data(), given_alg_ids.size(), sizeof(uint16_t),
-        compare_uint16_t);
-  for (size_t i = 1; i < num_given_alg_ids; i++) {
-    if (given_alg_ids[i - 1] == given_alg_ids[i]) {
-      return false;
-    }
-  }
-
-  if (best_index < num_algs &&
-      ssl_protocol_version(hs->ssl) >= TLS1_3_VERSION) {
-    hs->cert_compression_negotiated = true;
-    hs->cert_compression_alg_id = ctx->cert_compression_algs[best_index].alg_id;
-  }
-
-  return true;
-}
-
-static bool cert_compression_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  return true;
-}
-
-// Application-level Protocol Settings
-//
-// https://tools.ietf.org/html/draft-vvv-tls-alps-01
-
-bool ssl_get_local_application_settings(const SSL_HANDSHAKE *hs,
-                                        Span<const uint8_t> *out_settings,
-                                        Span<const uint8_t> protocol) {
-  for (const ALPSConfig &config : hs->config->alps_configs) {
-    if (protocol == config.protocol) {
-      *out_settings = config.settings;
-      return true;
-    }
-  }
-  return false;
-}
-
-static bool ext_alps_add_clienthello(const SSL_HANDSHAKE *hs, CBB *out,
-                                     CBB *out_compressible,
-                                     ssl_client_hello_type_t type) {
-  const SSL *const ssl = hs->ssl;
-  if (// ALPS requires TLS 1.3.
-      hs->max_version < TLS1_3_VERSION ||
-      // Do not offer ALPS without ALPN.
-      hs->config->alpn_client_proto_list.empty() ||
-      // Do not offer ALPS if not configured.
-      hs->config->alps_configs.empty() ||
-      // Do not offer ALPS on renegotiation handshakes.
-      ssl->s3->initial_handshake_complete) {
-    return true;
-  }
-
-  CBB contents, proto_list, proto;
-  if (!CBB_add_u16(out_compressible, TLSEXT_TYPE_application_settings) ||
-      !CBB_add_u16_length_prefixed(out_compressible, &contents) ||
-      !CBB_add_u16_length_prefixed(&contents, &proto_list)) {
-    return false;
-  }
-
-  for (const ALPSConfig &config : hs->config->alps_configs) {
-    if (!CBB_add_u8_length_prefixed(&proto_list, &proto) ||
-        !CBB_add_bytes(&proto, config.protocol.data(),
-                       config.protocol.size())) {
-      return false;
-    }
-  }
-
-  return CBB_flush(out_compressible);
-}
-
-static bool ext_alps_parse_serverhello(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                                       CBS *contents) {
-  SSL *const ssl = hs->ssl;
-  if (contents == nullptr) {
-    return true;
-  }
-
-  assert(!ssl->s3->initial_handshake_complete);
-  assert(!hs->config->alpn_client_proto_list.empty());
-  assert(!hs->config->alps_configs.empty());
-
-  // ALPS requires TLS 1.3.
-  if (ssl_protocol_version(ssl) < TLS1_3_VERSION) {
-    *out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
-    OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
-    return false;
-  }
-
-  // Note extension callbacks may run in any order, so we defer checking
-  // consistency with ALPN to |ssl_check_serverhello_tlsext|.
-  if (!hs->new_session->peer_application_settings.CopyFrom(*contents)) {
-    *out_alert = SSL_AD_INTERNAL_ERROR;
-    return false;
-  }
-
-  hs->new_session->has_application_settings = true;
-  return true;
-}
-
-static bool ext_alps_add_serverhello(SSL_HANDSHAKE *hs, CBB *out) {
-  SSL *const ssl = hs->ssl;
-  // If early data is accepted, we omit the ALPS extension. It is implicitly
-  // carried over from the previous connection.
-  if (hs->new_session == nullptr ||
-      !hs->new_session->has_application_settings ||
-      ssl->s3->early_data_accepted) {
-    return true;
-  }
-
-  CBB contents;
-  if (!CBB_add_u16(out, TLSEXT_TYPE_application_settings) ||
-      !CBB_add_u16_length_prefixed(out, &contents) ||
-      !CBB_add_bytes(&contents,
-                     hs->new_session->local_application_settings.data(),
-                     hs->new_session->local_application_settings.size()) ||
-      !CBB_flush(out)) {
-    return false;
-  }
-
-  return true;
-}
-
-bool ssl_negotiate_alps(SSL_HANDSHAKE *hs, uint8_t *out_alert,
-                        const SSL_CLIENT_HELLO *client_hello) {
-  SSL *const ssl = hs->ssl;
-  if (ssl->s3->alpn_selected.empty()) {
-    return true;
-  }
-
-  // If we negotiate ALPN over TLS 1.3, try to negotiate ALPS.
-  CBS alps_contents;
-  Span<const uint8_t> settings;
-  if (ssl_protocol_version(ssl) >= TLS1_3_VERSION &&
-      ssl_get_local_application_settings(hs, &settings,
-                                         ssl->s3->alpn_selected) &&
-      ssl_client_hello_get_extension(client_hello, &alps_contents,
-                                     TLSEXT_TYPE_application_settings)) {
-    // Check if the client supports ALPS with the selected ALPN.
-    bool found = false;
-    CBS alps_list;
-    if (!CBS_get_u16_length_prefixed(&alps_contents, &alps_list) ||
-        CBS_len(&alps_contents) != 0 ||
-        CBS_len(&alps_list) == 0) {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-      *out_alert = SSL_AD_DECODE_ERROR;
-      return false;
-    }
-    while (CBS_len(&alps_list) > 0) {
-      CBS protocol_name;
-      if (!CBS_get_u8_length_prefixed(&alps_list, &protocol_name) ||
-          // Empty protocol names are forbidden.
-          CBS_len(&protocol_name) == 0) {
-        OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-        *out_alert = SSL_AD_DECODE_ERROR;
-        return false;
-      }
-      if (protocol_name == MakeConstSpan(ssl->s3->alpn_selected)) {
-        found = true;
-      }
-    }
-
-    // Negotiate ALPS if both client also supports ALPS for this protocol.
-    if (found) {
-      hs->new_session->has_application_settings = true;
-      if (!hs->new_session->local_application_settings.CopyFrom(settings)) {
-        *out_alert = SSL_AD_INTERNAL_ERROR;
-        return false;
-      }
-    }
-  }
-
-  return true;
-}
-
-// kExtensions contains all the supported extensions.
-static const struct tls_extension kExtensions[] = {
-  {
-    TLSEXT_TYPE_server_name,
-    ext_sni_add_clienthello,
-    ext_sni_parse_serverhello,
-    ext_sni_parse_clienthello,
-    ext_sni_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_encrypted_client_hello,
-    ext_ech_add_clienthello,
-    ext_ech_parse_serverhello,
-    ext_ech_parse_clienthello,
-    ext_ech_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_ech_is_inner,
-    ext_ech_is_inner_add_clienthello,
-    forbid_parse_serverhello,
-    ext_ech_is_inner_parse_clienthello,
-    dont_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_extended_master_secret,
-    ext_ems_add_clienthello,
-    ext_ems_parse_serverhello,
-    ext_ems_parse_clienthello,
-    ext_ems_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_renegotiate,
-    ext_ri_add_clienthello,
-    ext_ri_parse_serverhello,
-    ext_ri_parse_clienthello,
-    ext_ri_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_supported_groups,
-    ext_supported_groups_add_clienthello,
-    ext_supported_groups_parse_serverhello,
-    ext_supported_groups_parse_clienthello,
-    dont_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_ec_point_formats,
-    ext_ec_point_add_clienthello,
-    ext_ec_point_parse_serverhello,
-    ext_ec_point_parse_clienthello,
-    ext_ec_point_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_session_ticket,
-    ext_ticket_add_clienthello,
-    ext_ticket_parse_serverhello,
-    // Ticket extension client parsing is handled in ssl_session.c
-    ignore_parse_clienthello,
-    ext_ticket_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_application_layer_protocol_negotiation,
-    ext_alpn_add_clienthello,
-    ext_alpn_parse_serverhello,
-    // ALPN is negotiated late in |ssl_negotiate_alpn|.
-    ignore_parse_clienthello,
-    ext_alpn_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_status_request,
-    ext_ocsp_add_clienthello,
-    ext_ocsp_parse_serverhello,
-    ext_ocsp_parse_clienthello,
-    ext_ocsp_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_signature_algorithms,
-    ext_sigalgs_add_clienthello,
-    forbid_parse_serverhello,
-    ext_sigalgs_parse_clienthello,
-    dont_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_next_proto_neg,
-    ext_npn_add_clienthello,
-    ext_npn_parse_serverhello,
-    ext_npn_parse_clienthello,
-    ext_npn_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_certificate_timestamp,
-    ext_sct_add_clienthello,
-    ext_sct_parse_serverhello,
-    ext_sct_parse_clienthello,
-    ext_sct_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_channel_id,
-    ext_channel_id_add_clienthello,
-    ext_channel_id_parse_serverhello,
-    ext_channel_id_parse_clienthello,
-    ext_channel_id_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_srtp,
-    ext_srtp_add_clienthello,
-    ext_srtp_parse_serverhello,
-    ext_srtp_parse_clienthello,
-    ext_srtp_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_key_share,
-    ext_key_share_add_clienthello,
-    forbid_parse_serverhello,
-    ignore_parse_clienthello,
-    dont_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_psk_key_exchange_modes,
-    ext_psk_key_exchange_modes_add_clienthello,
-    forbid_parse_serverhello,
-    ext_psk_key_exchange_modes_parse_clienthello,
-    dont_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_early_data,
-    ext_early_data_add_clienthello,
-    ext_early_data_parse_serverhello,
-    ext_early_data_parse_clienthello,
-    ext_early_data_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_supported_versions,
-    ext_supported_versions_add_clienthello,
-    forbid_parse_serverhello,
-    ignore_parse_clienthello,
-    dont_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_cookie,
-    ext_cookie_add_clienthello,
-    forbid_parse_serverhello,
-    ignore_parse_clienthello,
-    dont_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_quic_transport_parameters,
-    ext_quic_transport_params_add_clienthello,
-    ext_quic_transport_params_parse_serverhello,
-    ext_quic_transport_params_parse_clienthello,
-    ext_quic_transport_params_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_quic_transport_parameters_legacy,
-    ext_quic_transport_params_add_clienthello_legacy,
-    ext_quic_transport_params_parse_serverhello_legacy,
-    ext_quic_transport_params_parse_clienthello_legacy,
-    ext_quic_transport_params_add_serverhello_legacy,
-  },
-  {
-    TLSEXT_TYPE_cert_compression,
-    cert_compression_add_clienthello,
-    cert_compression_parse_serverhello,
-    cert_compression_parse_clienthello,
-    cert_compression_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_delegated_credential,
-    ext_delegated_credential_add_clienthello,
-    forbid_parse_serverhello,
-    ext_delegated_credential_parse_clienthello,
-    dont_add_serverhello,
-  },
-  {
-    TLSEXT_TYPE_application_settings,
-    ext_alps_add_clienthello,
-    ext_alps_parse_serverhello,
-    // ALPS is negotiated late in |ssl_negotiate_alpn|.
-    ignore_parse_clienthello,
-    ext_alps_add_serverhello,
-  },
-};
-
-#define kNumExtensions (sizeof(kExtensions) / sizeof(struct tls_extension))
-
-static_assert(kNumExtensions <=
-                  sizeof(((SSL_HANDSHAKE *)NULL)->extensions.sent) * 8,
-              "too many extensions for sent bitset");
-static_assert(kNumExtensions <=
-                  sizeof(((SSL_HANDSHAKE *)NULL)->extensions.received) * 8,
-              "too many extensions for received bitset");
-
-bool ssl_setup_extension_permutation(SSL_HANDSHAKE *hs) {
-  if (!hs->config->permute_extensions) {
-    return true;
-  }
-
-  static_assert(kNumExtensions <= UINT8_MAX,
-                "extensions_permutation type is too small");
-  uint32_t seeds[kNumExtensions - 1];
-  Array<uint8_t> permutation;
-  if (!RAND_bytes(reinterpret_cast<uint8_t *>(seeds), sizeof(seeds)) ||
-      !permutation.Init(kNumExtensions)) {
-    return false;
-  }
-  for (size_t i = 0; i < kNumExtensions; i++) {
-    permutation[i] = i;
-  }
-  for (size_t i = kNumExtensions - 1; i > 0; i--) {
-    // Set element |i| to a randomly-selected element 0 <= j <= i.
-    std::swap(permutation[i], permutation[seeds[i - 1] % (i + 1)]);
-  }
-  hs->extension_permutation = std::move(permutation);
-  return true;
-}
-
-static const struct tls_extension *tls_extension_find(uint32_t *out_index,
-                                                      uint16_t value) {
-  unsigned i;
-  for (i = 0; i < kNumExtensions; i++) {
-    if (kExtensions[i].value == value) {
-      *out_index = i;
-      return &kExtensions[i];
-    }
-  }
-
-  return NULL;
-}
-
-static bool add_padding_extension(CBB *cbb, uint16_t ext, size_t len) {
-  CBB child;
-  uint8_t *ptr;
-  if (!CBB_add_u16(cbb, ext) ||  //
-      !CBB_add_u16_length_prefixed(cbb, &child) ||
-      !CBB_add_space(&child, &ptr, len)) {
-    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
-    return false;
-  }
-  OPENSSL_memset(ptr, 0, len);
-  return CBB_flush(cbb);
-}
-
-static bool ssl_add_clienthello_tlsext_inner(SSL_HANDSHAKE *hs, CBB *out,
-                                             CBB *out_encoded,
-                                             bool *out_needs_psk_binder) {
-  // When writing ClientHelloInner, we construct the real and encoded
-  // ClientHellos concurrently, to handle compression. Uncompressed extensions
-  // are written to |extensions| and copied to |extensions_encoded|. Compressed
-  // extensions are buffered in |compressed| and written to the end. (ECH can
-  // only compress continguous extensions.)
-  SSL *const ssl = hs->ssl;
-  bssl::ScopedCBB compressed, outer_extensions;
-  CBB extensions, extensions_encoded;
-  if (!CBB_add_u16_length_prefixed(out, &extensions) ||
-      !CBB_add_u16_length_prefixed(out_encoded, &extensions_encoded) ||
-      !CBB_init(compressed.get(), 64) ||
-      !CBB_init(outer_extensions.get(), 64)) {
-    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
-    return false;
-  }
-
-  hs->inner_extensions_sent = 0;
-
-  if (ssl->ctx->grease_enabled) {
-    // Add a fake empty extension. See RFC 8701. This always matches
-    // |ssl_add_clienthello_tlsext|, so compress it.
-    uint16_t grease_ext = ssl_get_grease_value(hs, ssl_grease_extension1);
-    if (!add_padding_extension(compressed.get(), grease_ext, 0) ||
-        !CBB_add_u16(outer_extensions.get(), grease_ext)) {
-      return false;
-    }
-  }
-
-  for (size_t unpermuted = 0; unpermuted < kNumExtensions; unpermuted++) {
-    size_t i = hs->extension_permutation.empty()
-                   ? unpermuted
-                   : hs->extension_permutation[unpermuted];
-    const size_t len_before = CBB_len(&extensions);
-    const size_t len_compressed_before = CBB_len(compressed.get());
-    if (!kExtensions[i].add_clienthello(hs, &extensions, compressed.get(),
-                                        ssl_client_hello_inner)) {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_ADDING_EXTENSION);
-      ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value);
-      return false;
-    }
-
-    const size_t bytes_written = CBB_len(&extensions) - len_before;
-    const size_t bytes_written_compressed =
-        CBB_len(compressed.get()) - len_compressed_before;
-    // The callback may write to at most one output.
-    assert(bytes_written == 0 || bytes_written_compressed == 0);
-    if (bytes_written != 0 || bytes_written_compressed != 0) {
-      hs->inner_extensions_sent |= (1u << i);
-    }
-    // If compressed, update the running ech_outer_extensions extension.
-    if (bytes_written_compressed != 0 &&
-        !CBB_add_u16(outer_extensions.get(), kExtensions[i].value)) {
-      return false;
-    }
-  }
-
-  if (ssl->ctx->grease_enabled) {
-    // Add a fake non-empty extension. See RFC 8701. This always matches
-    // |ssl_add_clienthello_tlsext|, so compress it.
-    uint16_t grease_ext = ssl_get_grease_value(hs, ssl_grease_extension2);
-    if (!add_padding_extension(compressed.get(), grease_ext, 1) ||
-        !CBB_add_u16(outer_extensions.get(), grease_ext)) {
-      return false;
-    }
-  }
-
-  // Pad the server name. See draft-ietf-tls-esni-10, section 6.1.2.
-  // TODO(https://crbug.com/boringssl/275): Ideally we'd pad the whole thing to
-  // reduce the output range. See
-  // https://github.com/tlswg/draft-ietf-tls-esni/issues/433
-  size_t padding_len = 0;
-  size_t maximum_name_length = hs->selected_ech_config->maximum_name_length;
-  if (ssl->hostname) {
-    size_t hostname_len = strlen(ssl->hostname.get());
-    if (hostname_len <= maximum_name_length) {
-      padding_len = maximum_name_length - hostname_len;
-    } else {
-      // If the server underestimated the maximum size, pad to a multiple of 32.
-      padding_len = 31 - (hostname_len - 1) % 32;
-      // If the input is close to |maximum_name_length|, pad to the next
-      // multiple for at least 32 bytes of length ambiguity.
-      if (hostname_len + padding_len < maximum_name_length + 32) {
-        padding_len += 32;
-      }
-    }
-  } else {
-    // No SNI. Pad up to |maximum_name_length|, including server_name extension
-    // overhead.
-    padding_len = 9 + maximum_name_length;
-  }
-  if (!add_padding_extension(&extensions, TLSEXT_TYPE_padding, padding_len)) {
-    return false;
-  }
-
-  // Uncompressed extensions are encoded as-is.
-  if (!CBB_add_bytes(&extensions_encoded, CBB_data(&extensions),
-                     CBB_len(&extensions))) {
-    return false;
-  }
-
-  // Flush all the compressed extensions.
-  if (CBB_len(compressed.get()) != 0) {
-    CBB extension, child;
-    // Copy them as-is in the real ClientHelloInner.
-    if (!CBB_add_bytes(&extensions, CBB_data(compressed.get()),
-                       CBB_len(compressed.get())) ||
-        // Replace with ech_outer_extensions in the encoded form.
-        !CBB_add_u16(&extensions_encoded, TLSEXT_TYPE_ech_outer_extensions) ||
-        !CBB_add_u16_length_prefixed(&extensions_encoded, &extension) ||
-        !CBB_add_u8_length_prefixed(&extension, &child) ||
-        !CBB_add_bytes(&child, CBB_data(outer_extensions.get()),
-                       CBB_len(outer_extensions.get())) ||
-        !CBB_flush(&extensions_encoded)) {
-      return false;
-    }
-  }
-
-  // The PSK extension must be last. It is never compressed. Note, if there is a
-  // binder, the caller will need to update both ClientHelloInner and
-  // EncodedClientHelloInner after computing it.
-  const size_t len_before = CBB_len(&extensions);
-  if (!ext_pre_shared_key_add_clienthello(hs, &extensions, out_needs_psk_binder,
-                                          ssl_client_hello_inner) ||
-      !CBB_add_bytes(&extensions_encoded, CBB_data(&extensions) + len_before,
-                     CBB_len(&extensions) - len_before) ||
-      !CBB_flush(out) ||  //
-      !CBB_flush(out_encoded)) {
-    return false;
-  }
-
-  return true;
-}
-
-bool ssl_add_clienthello_tlsext(SSL_HANDSHAKE *hs, CBB *out, CBB *out_encoded,
-                                bool *out_needs_psk_binder,
-                                ssl_client_hello_type_t type, size_t header_len,
-                                size_t omit_ech_len) {
-  *out_needs_psk_binder = false;
-
-  if (type == ssl_client_hello_inner) {
-    return ssl_add_clienthello_tlsext_inner(hs, out, out_encoded,
-                                            out_needs_psk_binder);
-  }
-
-  assert(out_encoded == nullptr);  // Only ClientHelloInner needs two outputs.
-  SSL *const ssl = hs->ssl;
-  CBB extensions;
-  if (!CBB_add_u16_length_prefixed(out, &extensions)) {
-    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
-    return false;
-  }
-
-  // Note we may send multiple ClientHellos for DTLS HelloVerifyRequest and TLS
-  // 1.3 HelloRetryRequest. For the latter, the extensions may change, so it is
-  // important to reset this value.
-  hs->extensions.sent = 0;
-
-  // Add a fake empty extension. See RFC 8701.
-  if (ssl->ctx->grease_enabled &&
-      !add_padding_extension(
-          &extensions, ssl_get_grease_value(hs, ssl_grease_extension1), 0)) {
-    return false;
-  }
-
-  bool last_was_empty = false;
-  for (size_t unpermuted = 0; unpermuted < kNumExtensions; unpermuted++) {
-    size_t i = hs->extension_permutation.empty()
-                   ? unpermuted
-                   : hs->extension_permutation[unpermuted];
-    size_t bytes_written;
-    if (omit_ech_len != 0 &&
-        kExtensions[i].value == TLSEXT_TYPE_encrypted_client_hello) {
-      bytes_written = omit_ech_len;
-    } else {
-      const size_t len_before = CBB_len(&extensions);
-      if (!kExtensions[i].add_clienthello(hs, &extensions, &extensions, type)) {
-        OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_ADDING_EXTENSION);
-        ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value);
-        return false;
-      }
-
-      bytes_written = CBB_len(&extensions) - len_before;
-    }
-    if (bytes_written != 0) {
-      hs->extensions.sent |= (1u << i);
-    }
-    // If the difference in lengths is only four bytes then the extension had
-    // an empty body.
-    last_was_empty = (bytes_written == 4);
-  }
-
-  if (ssl->ctx->grease_enabled) {
-    // Add a fake non-empty extension. See RFC 8701.
-    if (!add_padding_extension(
-            &extensions, ssl_get_grease_value(hs, ssl_grease_extension2), 1)) {
-      return false;
-    }
-    last_was_empty = false;
-  }
-
-  // In cleartext ClientHellos, we add the padding extension to work around
-  // bugs. We also apply this padding to ClientHelloOuter, to keep the wire
-  // images aligned.
-  size_t psk_extension_len = ext_pre_shared_key_clienthello_length(hs, type);
-  if (!SSL_is_dtls(ssl) && !ssl->quic_method &&
-      !ssl->s3->used_hello_retry_request) {
-    header_len += SSL3_HM_HEADER_LENGTH + 2 + CBB_len(&extensions) +
-                  omit_ech_len + psk_extension_len;
-    size_t padding_len = 0;
-
-    // The final extension must be non-empty. WebSphere Application
-    // Server 7.0 is intolerant to the last extension being zero-length. See
-    // https://crbug.com/363583.
-    if (last_was_empty && psk_extension_len == 0) {
-      padding_len = 1;
-      // The addition of the padding extension may push us into the F5 bug.
-      header_len += 4 + padding_len;
-    }
-
-    // Add padding to workaround bugs in F5 terminators. See RFC 7685.
-    //
-    // NB: because this code works out the length of all existing extensions
-    // it MUST always appear last (save for any PSK extension).
-    if (header_len > 0xff && header_len < 0x200) {
-      // If our calculations already included a padding extension, remove that
-      // factor because we're about to change its length.
-      if (padding_len != 0) {
-        header_len -= 4 + padding_len;
-      }
-      padding_len = 0x200 - header_len;
-      // Extensions take at least four bytes to encode. Always include at least
-      // one byte of data if including the extension. WebSphere Application
-      // Server 7.0 is intolerant to the last extension being zero-length. See
-      // https://crbug.com/363583.
-      if (padding_len >= 4 + 1) {
-        padding_len -= 4;
-      } else {
-        padding_len = 1;
-      }
-    }
-
-    if (padding_len != 0 &&
-        !add_padding_extension(&extensions, TLSEXT_TYPE_padding, padding_len)) {
-      return false;
-    }
-  }
-
-  // The PSK extension must be last, including after the padding.
-  const size_t len_before = CBB_len(&extensions);
-  if (!ext_pre_shared_key_add_clienthello(hs, &extensions, out_needs_psk_binder,
-                                          type)) {
-    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
-    return false;
-  }
-  assert(psk_extension_len == CBB_len(&extensions) - len_before);
-  (void)len_before;  // |assert| is omitted in release builds.
-
-  // Discard empty extensions blocks.
-  if (CBB_len(&extensions) == 0) {
-    CBB_discard_child(out);
-  }
-
-  return CBB_flush(out);
-}
-
-bool ssl_add_serverhello_tlsext(SSL_HANDSHAKE *hs, CBB *out) {
-  SSL *const ssl = hs->ssl;
-  CBB extensions;
-  if (!CBB_add_u16_length_prefixed(out, &extensions)) {
-    goto err;
-  }
-
-  for (unsigned i = 0; i < kNumExtensions; i++) {
-    if (!(hs->extensions.received & (1u << i))) {
-      // Don't send extensions that were not received.
-      continue;
-    }
-
-    if (!kExtensions[i].add_serverhello(hs, &extensions)) {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_ADDING_EXTENSION);
-      ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value);
-      goto err;
-    }
-  }
-
-  // Discard empty extensions blocks before TLS 1.3.
-  if (ssl_protocol_version(ssl) < TLS1_3_VERSION &&
-      CBB_len(&extensions) == 0) {
-    CBB_discard_child(out);
-  }
-
-  return CBB_flush(out);
-
-err:
-  OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
-  return false;
-}
-
-static bool ssl_scan_clienthello_tlsext(SSL_HANDSHAKE *hs,
-                                        const SSL_CLIENT_HELLO *client_hello,
-                                        int *out_alert) {
-  hs->extensions.received = 0;
-  CBS extensions;
-  CBS_init(&extensions, client_hello->extensions, client_hello->extensions_len);
-  while (CBS_len(&extensions) != 0) {
-    uint16_t type;
-    CBS extension;
-
-    // Decode the next extension.
-    if (!CBS_get_u16(&extensions, &type) ||
-        !CBS_get_u16_length_prefixed(&extensions, &extension)) {
-      *out_alert = SSL_AD_DECODE_ERROR;
-      return false;
-    }
-
-    unsigned ext_index;
-    const struct tls_extension *const ext =
-        tls_extension_find(&ext_index, type);
-    if (ext == NULL) {
-      continue;
-    }
-
-    hs->extensions.received |= (1u << ext_index);
-    uint8_t alert = SSL_AD_DECODE_ERROR;
-    if (!ext->parse_clienthello(hs, &alert, &extension)) {
-      *out_alert = alert;
-      OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION);
-      ERR_add_error_dataf("extension %u", (unsigned)type);
-      return false;
-    }
-  }
-
-  for (size_t i = 0; i < kNumExtensions; i++) {
-    if (hs->extensions.received & (1u << i)) {
-      continue;
-    }
-
-    CBS *contents = NULL, fake_contents;
-    static const uint8_t kFakeRenegotiateExtension[] = {0};
-    if (kExtensions[i].value == TLSEXT_TYPE_renegotiate &&
-        ssl_client_cipher_list_contains_cipher(client_hello,
-                                               SSL3_CK_SCSV & 0xffff)) {
-      // The renegotiation SCSV was received so pretend that we received a
-      // renegotiation extension.
-      CBS_init(&fake_contents, kFakeRenegotiateExtension,
-               sizeof(kFakeRenegotiateExtension));
-      contents = &fake_contents;
-      hs->extensions.received |= (1u << i);
-    }
-
-    // Extension wasn't observed so call the callback with a NULL
-    // parameter.
-    uint8_t alert = SSL_AD_DECODE_ERROR;
-    if (!kExtensions[i].parse_clienthello(hs, &alert, contents)) {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_EXTENSION);
-      ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value);
-      *out_alert = alert;
-      return false;
-    }
-  }
-
-  return true;
-}
-
-bool ssl_parse_clienthello_tlsext(SSL_HANDSHAKE *hs,
-                                  const SSL_CLIENT_HELLO *client_hello) {
-  SSL *const ssl = hs->ssl;
-  int alert = SSL_AD_DECODE_ERROR;
-  if (!ssl_scan_clienthello_tlsext(hs, client_hello, &alert)) {
-    ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
-    return false;
-  }
-
-  if (!ssl_check_clienthello_tlsext(hs)) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_CLIENTHELLO_TLSEXT);
-    return false;
-  }
-
-  return true;
-}
-
-static bool ssl_scan_serverhello_tlsext(SSL_HANDSHAKE *hs, CBS *cbs,
-                                        int *out_alert) {
-  SSL *const ssl = hs->ssl;
-  // Before TLS 1.3, ServerHello extensions blocks may be omitted if empty.
-  if (CBS_len(cbs) == 0 && ssl_protocol_version(ssl) < TLS1_3_VERSION) {
-    return true;
-  }
-
-  // Decode the extensions block and check it is valid.
-  CBS extensions;
-  if (!CBS_get_u16_length_prefixed(cbs, &extensions) ||
-      !tls1_check_duplicate_extensions(&extensions)) {
-    *out_alert = SSL_AD_DECODE_ERROR;
-    return false;
-  }
-
-  uint32_t received = 0;
-  while (CBS_len(&extensions) != 0) {
-    uint16_t type;
-    CBS extension;
-
-    // Decode the next extension.
-    if (!CBS_get_u16(&extensions, &type) ||
-        !CBS_get_u16_length_prefixed(&extensions, &extension)) {
-      *out_alert = SSL_AD_DECODE_ERROR;
-      return false;
-    }
-
-    unsigned ext_index;
-    const struct tls_extension *const ext =
-        tls_extension_find(&ext_index, type);
-
-    if (ext == NULL) {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
-      ERR_add_error_dataf("extension %u", (unsigned)type);
-      *out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
-      return false;
-    }
-
-    static_assert(kNumExtensions <= sizeof(hs->extensions.sent) * 8,
-                  "too many bits");
-
-    if (!(hs->extensions.sent & (1u << ext_index))) {
-      // If the extension was never sent then it is illegal.
-      OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_EXTENSION);
-      ERR_add_error_dataf("extension :%u", (unsigned)type);
-      *out_alert = SSL_AD_UNSUPPORTED_EXTENSION;
-      return false;
-    }
-
-    received |= (1u << ext_index);
-
-    uint8_t alert = SSL_AD_DECODE_ERROR;
-    if (!ext->parse_serverhello(hs, &alert, &extension)) {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_ERROR_PARSING_EXTENSION);
-      ERR_add_error_dataf("extension %u", (unsigned)type);
-      *out_alert = alert;
-      return false;
-    }
-  }
-
-  for (size_t i = 0; i < kNumExtensions; i++) {
-    if (!(received & (1u << i))) {
-      // Extension wasn't observed so call the callback with a NULL
-      // parameter.
-      uint8_t alert = SSL_AD_DECODE_ERROR;
-      if (!kExtensions[i].parse_serverhello(hs, &alert, NULL)) {
-        OPENSSL_PUT_ERROR(SSL, SSL_R_MISSING_EXTENSION);
-        ERR_add_error_dataf("extension %u", (unsigned)kExtensions[i].value);
-        *out_alert = alert;
-        return false;
-      }
-    }
-  }
-
-  return true;
-}
-
-static bool ssl_check_clienthello_tlsext(SSL_HANDSHAKE *hs) {
-  SSL *const ssl = hs->ssl;
-  int ret = SSL_TLSEXT_ERR_NOACK;
-  int al = SSL_AD_UNRECOGNIZED_NAME;
-  if (ssl->ctx->servername_callback != 0) {
-    ret = ssl->ctx->servername_callback(ssl, &al, ssl->ctx->servername_arg);
-  } else if (ssl->session_ctx->servername_callback != 0) {
-    ret = ssl->session_ctx->servername_callback(
-        ssl, &al, ssl->session_ctx->servername_arg);
-  }
-
-  switch (ret) {
-    case SSL_TLSEXT_ERR_ALERT_FATAL:
-      ssl_send_alert(ssl, SSL3_AL_FATAL, al);
-      return false;
-
-    case SSL_TLSEXT_ERR_NOACK:
-      hs->should_ack_sni = false;
-      return true;
-
-    default:
-      return true;
-  }
-}
-
-static bool ssl_check_serverhello_tlsext(SSL_HANDSHAKE *hs) {
-  SSL *const ssl = hs->ssl;
-  // ALPS and ALPN have a dependency between each other, so we defer checking
-  // consistency to after the callbacks run.
-  if (hs->new_session != nullptr && hs->new_session->has_application_settings) {
-    // ALPN must be negotiated.
-    if (ssl->s3->alpn_selected.empty()) {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_NEGOTIATED_ALPS_WITHOUT_ALPN);
-      ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
-      return false;
-    }
-
-    // The negotiated protocol must be one of the ones we advertised for ALPS.
-    Span<const uint8_t> settings;
-    if (!ssl_get_local_application_settings(hs, &settings,
-                                            ssl->s3->alpn_selected)) {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_INVALID_ALPN_PROTOCOL);
-      ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_ILLEGAL_PARAMETER);
-      return false;
-    }
-
-    if (!hs->new_session->local_application_settings.CopyFrom(settings)) {
-      ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_INTERNAL_ERROR);
-      return false;
-    }
-  }
-
-  return true;
-}
-
-bool ssl_parse_serverhello_tlsext(SSL_HANDSHAKE *hs, CBS *cbs) {
-  SSL *const ssl = hs->ssl;
-  int alert = SSL_AD_DECODE_ERROR;
-  if (!ssl_scan_serverhello_tlsext(hs, cbs, &alert)) {
-    ssl_send_alert(ssl, SSL3_AL_FATAL, alert);
-    return false;
-  }
-
-  if (!ssl_check_serverhello_tlsext(hs)) {
-    return false;
-  }
-
-  return true;
-}
-
-static enum ssl_ticket_aead_result_t decrypt_ticket_with_cipher_ctx(
-    Array<uint8_t> *out, EVP_CIPHER_CTX *cipher_ctx, HMAC_CTX *hmac_ctx,
-    Span<const uint8_t> ticket) {
-  size_t iv_len = EVP_CIPHER_CTX_iv_length(cipher_ctx);
-
-  // Check the MAC at the end of the ticket.
-  uint8_t mac[EVP_MAX_MD_SIZE];
-  size_t mac_len = HMAC_size(hmac_ctx);
-  if (ticket.size() < SSL_TICKET_KEY_NAME_LEN + iv_len + 1 + mac_len) {
-    // The ticket must be large enough for key name, IV, data, and MAC.
-    return ssl_ticket_aead_ignore_ticket;
-  }
-  // Split the ticket into the ticket and the MAC.
-  auto ticket_mac = ticket.subspan(ticket.size() - mac_len);
-  ticket = ticket.subspan(0, ticket.size() - mac_len);
-  HMAC_Update(hmac_ctx, ticket.data(), ticket.size());
-  HMAC_Final(hmac_ctx, mac, NULL);
-  assert(mac_len == ticket_mac.size());
-  bool mac_ok = CRYPTO_memcmp(mac, ticket_mac.data(), mac_len) == 0;
-#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
-  mac_ok = true;
-#endif
-  if (!mac_ok) {
-    return ssl_ticket_aead_ignore_ticket;
-  }
-
-  // Decrypt the session data.
-  auto ciphertext = ticket.subspan(SSL_TICKET_KEY_NAME_LEN + iv_len);
-  Array<uint8_t> plaintext;
-#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
-  if (!plaintext.CopyFrom(ciphertext)) {
-    return ssl_ticket_aead_error;
-  }
-#else
-  if (ciphertext.size() >= INT_MAX) {
-    return ssl_ticket_aead_ignore_ticket;
-  }
-  if (!plaintext.Init(ciphertext.size())) {
-    return ssl_ticket_aead_error;
-  }
-  int len1, len2;
-  if (!EVP_DecryptUpdate(cipher_ctx, plaintext.data(), &len1, ciphertext.data(),
-                         (int)ciphertext.size()) ||
-      !EVP_DecryptFinal_ex(cipher_ctx, plaintext.data() + len1, &len2)) {
-    ERR_clear_error();
-    return ssl_ticket_aead_ignore_ticket;
-  }
-  plaintext.Shrink(static_cast<size_t>(len1) + len2);
-#endif
-
-  *out = std::move(plaintext);
-  return ssl_ticket_aead_success;
-}
-
-static enum ssl_ticket_aead_result_t ssl_decrypt_ticket_with_cb(
-    SSL_HANDSHAKE *hs, Array<uint8_t> *out, bool *out_renew_ticket,
-    Span<const uint8_t> ticket) {
-  assert(ticket.size() >= SSL_TICKET_KEY_NAME_LEN + EVP_MAX_IV_LENGTH);
-  ScopedEVP_CIPHER_CTX cipher_ctx;
-  ScopedHMAC_CTX hmac_ctx;
-  auto name = ticket.subspan(0, SSL_TICKET_KEY_NAME_LEN);
-  // The actual IV is shorter, but the length is determined by the callback's
-  // chosen cipher. Instead we pass in |EVP_MAX_IV_LENGTH| worth of IV to ensure
-  // the callback has enough.
-  auto iv = ticket.subspan(SSL_TICKET_KEY_NAME_LEN, EVP_MAX_IV_LENGTH);
-  int cb_ret = hs->ssl->session_ctx->ticket_key_cb(
-      hs->ssl, const_cast<uint8_t *>(name.data()),
-      const_cast<uint8_t *>(iv.data()), cipher_ctx.get(), hmac_ctx.get(),
-      0 /* decrypt */);
-  if (cb_ret < 0) {
-    return ssl_ticket_aead_error;
-  } else if (cb_ret == 0) {
-    return ssl_ticket_aead_ignore_ticket;
-  } else if (cb_ret == 2) {
-    *out_renew_ticket = true;
-  } else {
-    assert(cb_ret == 1);
-  }
-  return decrypt_ticket_with_cipher_ctx(out, cipher_ctx.get(), hmac_ctx.get(),
-                                        ticket);
-}
-
-static enum ssl_ticket_aead_result_t ssl_decrypt_ticket_with_ticket_keys(
-    SSL_HANDSHAKE *hs, Array<uint8_t> *out, Span<const uint8_t> ticket) {
-  assert(ticket.size() >= SSL_TICKET_KEY_NAME_LEN + EVP_MAX_IV_LENGTH);
-  SSL_CTX *ctx = hs->ssl->session_ctx.get();
-
-  // Rotate the ticket key if necessary.
-  if (!ssl_ctx_rotate_ticket_encryption_key(ctx)) {
-    return ssl_ticket_aead_error;
-  }
-
-  const EVP_CIPHER *cipher = EVP_aes_128_cbc();
-  auto name = ticket.subspan(0, SSL_TICKET_KEY_NAME_LEN);
-  auto iv =
-      ticket.subspan(SSL_TICKET_KEY_NAME_LEN, EVP_CIPHER_iv_length(cipher));
-
-  // Pick the matching ticket key and decrypt.
-  ScopedEVP_CIPHER_CTX cipher_ctx;
-  ScopedHMAC_CTX hmac_ctx;
-  {
-    MutexReadLock lock(&ctx->lock);
-    const TicketKey *key;
-    if (ctx->ticket_key_current && name == ctx->ticket_key_current->name) {
-      key = ctx->ticket_key_current.get();
-    } else if (ctx->ticket_key_prev && name == ctx->ticket_key_prev->name) {
-      key = ctx->ticket_key_prev.get();
-    } else {
-      return ssl_ticket_aead_ignore_ticket;
-    }
-    if (!HMAC_Init_ex(hmac_ctx.get(), key->hmac_key, sizeof(key->hmac_key),
-                      tlsext_tick_md(), NULL) ||
-        !EVP_DecryptInit_ex(cipher_ctx.get(), cipher, NULL,
-                            key->aes_key, iv.data())) {
-      return ssl_ticket_aead_error;
-    }
-  }
-  return decrypt_ticket_with_cipher_ctx(out, cipher_ctx.get(), hmac_ctx.get(),
-                                        ticket);
-}
-
-static enum ssl_ticket_aead_result_t ssl_decrypt_ticket_with_method(
-    SSL_HANDSHAKE *hs, Array<uint8_t> *out, bool *out_renew_ticket,
-    Span<const uint8_t> ticket) {
-  Array<uint8_t> plaintext;
-  if (!plaintext.Init(ticket.size())) {
-    OPENSSL_PUT_ERROR(SSL, ERR_R_MALLOC_FAILURE);
-    return ssl_ticket_aead_error;
-  }
-
-  size_t plaintext_len;
-  const enum ssl_ticket_aead_result_t result =
-      hs->ssl->session_ctx->ticket_aead_method->open(
-          hs->ssl, plaintext.data(), &plaintext_len, ticket.size(),
-          ticket.data(), ticket.size());
-  if (result != ssl_ticket_aead_success) {
-    return result;
-  }
-
-  plaintext.Shrink(plaintext_len);
-  *out = std::move(plaintext);
-  return ssl_ticket_aead_success;
-}
-
-enum ssl_ticket_aead_result_t ssl_process_ticket(
-    SSL_HANDSHAKE *hs, UniquePtr<SSL_SESSION> *out_session,
-    bool *out_renew_ticket, Span<const uint8_t> ticket,
-    Span<const uint8_t> session_id) {
-  SSL *const ssl = hs->ssl;
-  *out_renew_ticket = false;
-  out_session->reset();
-
-  if ((SSL_get_options(hs->ssl) & SSL_OP_NO_TICKET) ||
-      session_id.size() > SSL_MAX_SSL_SESSION_ID_LENGTH) {
-    return ssl_ticket_aead_ignore_ticket;
-  }
-
-  // Tickets in TLS 1.3 are tied into pre-shared keys (PSKs), unlike in TLS 1.2
-  // where that concept doesn't exist. The |decrypted_psk| and |ignore_psk|
-  // hints only apply to PSKs. We check the version to determine which this is.
-  const bool is_psk = ssl_protocol_version(ssl) >= TLS1_3_VERSION;
-
-  Array<uint8_t> plaintext;
-  enum ssl_ticket_aead_result_t result;
-  SSL_HANDSHAKE_HINTS *const hints = hs->hints.get();
-  if (is_psk && hints && !hs->hints_requested &&
-      !hints->decrypted_psk.empty()) {
-    result = plaintext.CopyFrom(hints->decrypted_psk) ? ssl_ticket_aead_success
-                                                      : ssl_ticket_aead_error;
-  } else if (is_psk && hints && !hs->hints_requested && hints->ignore_psk) {
-    result = ssl_ticket_aead_ignore_ticket;
-  } else if (ssl->session_ctx->ticket_aead_method != NULL) {
-    result = ssl_decrypt_ticket_with_method(hs, &plaintext, out_renew_ticket,
-                                            ticket);
-  } else {
-    // Ensure there is room for the key name and the largest IV |ticket_key_cb|
-    // may try to consume. The real limit may be lower, but the maximum IV
-    // length should be well under the minimum size for the session material and
-    // HMAC.
-    if (ticket.size() < SSL_TICKET_KEY_NAME_LEN + EVP_MAX_IV_LENGTH) {
-      result = ssl_ticket_aead_ignore_ticket;
-    } else if (ssl->session_ctx->ticket_key_cb != NULL) {
-      result =
-          ssl_decrypt_ticket_with_cb(hs, &plaintext, out_renew_ticket, ticket);
-    } else {
-      result = ssl_decrypt_ticket_with_ticket_keys(hs, &plaintext, ticket);
-    }
-  }
-
-  if (is_psk && hints && hs->hints_requested) {
-    if (result == ssl_ticket_aead_ignore_ticket) {
-      hints->ignore_psk = true;
-    } else if (result == ssl_ticket_aead_success &&
-               !hints->decrypted_psk.CopyFrom(plaintext)) {
-      return ssl_ticket_aead_error;
-    }
-  }
-
-  if (result != ssl_ticket_aead_success) {
-    return result;
-  }
-
-  // Decode the session.
-  UniquePtr<SSL_SESSION> session(SSL_SESSION_from_bytes(
-      plaintext.data(), plaintext.size(), ssl->ctx.get()));
-  if (!session) {
-    ERR_clear_error();  // Don't leave an error on the queue.
-    return ssl_ticket_aead_ignore_ticket;
-  }
-
-  // Envoy's tests expect the session to have a session ID that matches the
-  // placeholder used by the client. It's unclear whether this is a good idea,
-  // but we maintain it for now.
-  SHA256(ticket.data(), ticket.size(), session->session_id);
-  // Other consumers may expect a non-empty session ID to indicate resumption.
-  session->session_id_length = SHA256_DIGEST_LENGTH;
-
-  *out_session = std::move(session);
-  return ssl_ticket_aead_success;
-}
-
-bool tls1_parse_peer_sigalgs(SSL_HANDSHAKE *hs, const CBS *in_sigalgs) {
-  // Extension ignored for inappropriate versions
-  if (ssl_protocol_version(hs->ssl) < TLS1_2_VERSION) {
-    return true;
-  }
-
-  // In all contexts, the signature algorithms list may not be empty. (It may be
-  // omitted by clients in TLS 1.2, but then the entire extension is omitted.)
-  return CBS_len(in_sigalgs) != 0 &&
-         parse_u16_array(in_sigalgs, &hs->peer_sigalgs);
-}
-
-bool tls1_get_legacy_signature_algorithm(uint16_t *out, const EVP_PKEY *pkey) {
-  switch (EVP_PKEY_id(pkey)) {
-    case EVP_PKEY_RSA:
-      *out = SSL_SIGN_RSA_PKCS1_MD5_SHA1;
-      return true;
-    case EVP_PKEY_EC:
-      *out = SSL_SIGN_ECDSA_SHA1;
-      return true;
-    default:
-      return false;
-  }
-}
-
-bool tls1_choose_signature_algorithm(SSL_HANDSHAKE *hs, uint16_t *out) {
-  SSL *const ssl = hs->ssl;
-  CERT *cert = hs->config->cert.get();
-  DC *dc = cert->dc.get();
-
-  // Before TLS 1.2, the signature algorithm isn't negotiated as part of the
-  // handshake.
-  if (ssl_protocol_version(ssl) < TLS1_2_VERSION) {
-    if (!tls1_get_legacy_signature_algorithm(out, hs->local_pubkey.get())) {
-      OPENSSL_PUT_ERROR(SSL, SSL_R_NO_COMMON_SIGNATURE_ALGORITHMS);
-      return false;
-    }
-    return true;
-  }
-
-  Span<const uint16_t> sigalgs = kSignSignatureAlgorithms;
-  if (ssl_signing_with_dc(hs)) {
-    sigalgs = MakeConstSpan(&dc->expected_cert_verify_algorithm, 1);
-  } else if (!cert->sigalgs.empty()) {
-    sigalgs = cert->sigalgs;
-  }
-
-  Span<const uint16_t> peer_sigalgs = tls1_get_peer_verify_algorithms(hs);
-
-  for (uint16_t sigalg : sigalgs) {
-    // SSL_SIGN_RSA_PKCS1_MD5_SHA1 is an internal value and should never be
-    // negotiated.
-    if (sigalg == SSL_SIGN_RSA_PKCS1_MD5_SHA1 ||
-        !ssl_private_key_supports_signature_algorithm(hs, sigalg)) {
-      continue;
-    }
-
-    for (uint16_t peer_sigalg : peer_sigalgs) {
-      if (sigalg == peer_sigalg) {
-        *out = sigalg;
-        return true;
-      }
-    }
-  }
-
-  OPENSSL_PUT_ERROR(SSL, SSL_R_NO_COMMON_SIGNATURE_ALGORITHMS);
-  return false;
-}
-
-Span<const uint16_t> tls1_get_peer_verify_algorithms(const SSL_HANDSHAKE *hs) {
-  Span<const uint16_t> peer_sigalgs = hs->peer_sigalgs;
-  if (peer_sigalgs.empty() && ssl_protocol_version(hs->ssl) < TLS1_3_VERSION) {
-    // If the client didn't specify any signature_algorithms extension then
-    // we can assume that it supports SHA1. See
-    // http://tools.ietf.org/html/rfc5246#section-7.4.1.4.1
-    static const uint16_t kDefaultPeerAlgorithms[] = {SSL_SIGN_RSA_PKCS1_SHA1,
-                                                      SSL_SIGN_ECDSA_SHA1};
-    peer_sigalgs = kDefaultPeerAlgorithms;
-  }
-  return peer_sigalgs;
-}
-
-bool tls1_verify_channel_id(SSL_HANDSHAKE *hs, const SSLMessage &msg) {
-  SSL *const ssl = hs->ssl;
-  // A Channel ID handshake message is structured to contain multiple
-  // extensions, but the only one that can be present is Channel ID.
-  uint16_t extension_type;
-  CBS channel_id = msg.body, extension;
-  if (!CBS_get_u16(&channel_id, &extension_type) ||
-      !CBS_get_u16_length_prefixed(&channel_id, &extension) ||
-      CBS_len(&channel_id) != 0 ||
-      extension_type != TLSEXT_TYPE_channel_id ||
-      CBS_len(&extension) != TLSEXT_CHANNEL_ID_SIZE) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
-    ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECODE_ERROR);
-    return false;
-  }
-
-  UniquePtr<EC_GROUP> p256(EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1));
-  if (!p256) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_NO_P256_SUPPORT);
-    return false;
-  }
-
-  UniquePtr<ECDSA_SIG> sig(ECDSA_SIG_new());
-  UniquePtr<BIGNUM> x(BN_new()), y(BN_new());
-  if (!sig || !x || !y) {
-    return false;
-  }
-
-  const uint8_t *p = CBS_data(&extension);
-  if (BN_bin2bn(p + 0, 32, x.get()) == NULL ||
-      BN_bin2bn(p + 32, 32, y.get()) == NULL ||
-      BN_bin2bn(p + 64, 32, sig->r) == NULL ||
-      BN_bin2bn(p + 96, 32, sig->s) == NULL) {
-    return false;
-  }
-
-  UniquePtr<EC_KEY> key(EC_KEY_new());
-  UniquePtr<EC_POINT> point(EC_POINT_new(p256.get()));
-  if (!key || !point ||
-      !EC_POINT_set_affine_coordinates_GFp(p256.get(), point.get(), x.get(),
-                                           y.get(), nullptr) ||
-      !EC_KEY_set_group(key.get(), p256.get()) ||
-      !EC_KEY_set_public_key(key.get(), point.get())) {
-    return false;
-  }
-
-  uint8_t digest[EVP_MAX_MD_SIZE];
-  size_t digest_len;
-  if (!tls1_channel_id_hash(hs, digest, &digest_len)) {
-    return false;
-  }
-
-  bool sig_ok = ECDSA_do_verify(digest, digest_len, sig.get(), key.get());
-#if defined(BORINGSSL_UNSAFE_FUZZER_MODE)
-  sig_ok = true;
-  ERR_clear_error();
-#endif
-  if (!sig_ok) {
-    OPENSSL_PUT_ERROR(SSL, SSL_R_CHANNEL_ID_SIGNATURE_INVALID);
-    ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_DECRYPT_ERROR);
-    return false;
-  }
-
-  OPENSSL_memcpy(ssl->s3->channel_id, p, 64);
-  ssl->s3->channel_id_valid = true;
-  return true;
-}
-
-bool tls1_write_channel_id(SSL_HANDSHAKE *hs, CBB *cbb) {
-  uint8_t digest[EVP_MAX_MD_SIZE];
-  size_t digest_len;
-  if (!tls1_channel_id_hash(hs, digest, &digest_len)) {
-    return false;
-  }
-
-  EC_KEY *ec_key = EVP_PKEY_get0_EC_KEY(hs->config->channel_id_private.get());
-  if (ec_key == nullptr) {
-    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
-    return false;
-  }
-
-  UniquePtr<BIGNUM> x(BN_new()), y(BN_new());
-  if (!x || !y ||
-      !EC_POINT_get_affine_coordinates_GFp(EC_KEY_get0_group(ec_key),
-                                           EC_KEY_get0_public_key(ec_key),
-                                           x.get(), y.get(), nullptr)) {
-    return false;
-  }
-
-  UniquePtr<ECDSA_SIG> sig(ECDSA_do_sign(digest, digest_len, ec_key));
-  if (!sig) {
-    return false;
-  }
-
-  CBB child;
-  if (!CBB_add_u16(cbb, TLSEXT_TYPE_channel_id) ||
-      !CBB_add_u16_length_prefixed(cbb, &child) ||
-      !BN_bn2cbb_padded(&child, 32, x.get()) ||
-      !BN_bn2cbb_padded(&child, 32, y.get()) ||
-      !BN_bn2cbb_padded(&child, 32, sig->r) ||
-      !BN_bn2cbb_padded(&child, 32, sig->s) ||
-      !CBB_flush(cbb)) {
-    return false;
-  }
-
-  return true;
-}
-
-bool tls1_channel_id_hash(SSL_HANDSHAKE *hs, uint8_t *out, size_t *out_len) {
-  SSL *const ssl = hs->ssl;
-  if (ssl_protocol_version(ssl) >= TLS1_3_VERSION) {
-    Array<uint8_t> msg;
-    if (!tls13_get_cert_verify_signature_input(hs, &msg,
-                                               ssl_cert_verify_channel_id)) {
-      return false;
-    }
-    SHA256(msg.data(), msg.size(), out);
-    *out_len = SHA256_DIGEST_LENGTH;
-    return true;
-  }
-
-  SHA256_CTX ctx;
-
-  SHA256_Init(&ctx);
-  static const char kClientIDMagic[] = "TLS Channel ID signature";
-  SHA256_Update(&ctx, kClientIDMagic, sizeof(kClientIDMagic));
-
-  if (ssl->session != NULL) {
-    static const char kResumptionMagic[] = "Resumption";
-    SHA256_Update(&ctx, kResumptionMagic, sizeof(kResumptionMagic));
-    if (ssl->session->original_handshake_hash_len == 0) {
-      OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
-      return false;
-    }
-    SHA256_Update(&ctx, ssl->session->original_handshake_hash,
-                  ssl->session->original_handshake_hash_len);
-  }
-
-  uint8_t hs_hash[EVP_MAX_MD_SIZE];
-  size_t hs_hash_len;
-  if (!hs->transcript.GetHash(hs_hash, &hs_hash_len)) {
-    return false;
-  }
-  SHA256_Update(&ctx, hs_hash, (size_t)hs_hash_len);
-  SHA256_Final(out, &ctx);
-  *out_len = SHA256_DIGEST_LENGTH;
-  return true;
-}
-
-bool tls1_record_handshake_hashes_for_channel_id(SSL_HANDSHAKE *hs) {
-  SSL *const ssl = hs->ssl;
-  // This function should never be called for a resumed session because the
-  // handshake hashes that we wish to record are for the original, full
-  // handshake.
-  if (ssl->session != NULL) {
-    return false;
-  }
-
-  static_assert(
-      sizeof(hs->new_session->original_handshake_hash) == EVP_MAX_MD_SIZE,
-      "original_handshake_hash is too small");
-
-  size_t digest_len;
-  if (!hs->transcript.GetHash(hs->new_session->original_handshake_hash,
-                              &digest_len)) {
-    return false;
-  }
-
-  static_assert(EVP_MAX_MD_SIZE <= 0xff,
-                "EVP_MAX_MD_SIZE does not fit in uint8_t");
-  hs->new_session->original_handshake_hash_len = (uint8_t)digest_len;
-
-  return true;
-}
-
-bool ssl_is_sct_list_valid(const CBS *contents) {
-  // Shallow parse the SCT list for sanity. By the RFC
-  // (https://tools.ietf.org/html/rfc6962#section-3.3) neither the list nor any
-  // of the SCTs may be empty.
-  CBS copy = *contents;
-  CBS sct_list;
-  if (!CBS_get_u16_length_prefixed(&copy, &sct_list) ||
-      CBS_len(&copy) != 0 ||
-      CBS_len(&sct_list) == 0) {
-    return false;
-  }
-
-  while (CBS_len(&sct_list) > 0) {
-    CBS sct;
-    if (!CBS_get_u16_length_prefixed(&sct_list, &sct) ||
-        CBS_len(&sct) == 0) {
-      return false;
-    }
-  }
-
-  return true;
-}
-
-BSSL_NAMESPACE_END
-
-using namespace bssl;
-
-int SSL_early_callback_ctx_extension_get(const SSL_CLIENT_HELLO *client_hello,
-                                         uint16_t extension_type,
-                                         const uint8_t **out_data,
-                                         size_t *out_len) {
-  CBS cbs;
-  if (!ssl_client_hello_get_extension(client_hello, &cbs, extension_type)) {
-    return 0;
-  }
-
-  *out_data = CBS_data(&cbs);
-  *out_len = CBS_len(&cbs);
-  return 1;
-}