BoringSSL as optional cryptobackend for ngtcp2

PR добавляет возможность использовать BoringSSL в ngtcp2 в качестве криптобиблиотеки. Для проектов в Аркадии, уже зависящих от ngtcp2, добавлена явная зависимость от слоя абстракции quictls (сейчас в транке ngtcp2 собирается с quictls).
commit_hash:3d6607abecfcff2157859acbdd18f9d0345ac485

1 files changed, 765 insertions, 0 deletions

diff --git a/contrib/restricted/google/boringssl/ssl/s3_both.cc b/contrib/restricted/google/boringssl/ssl/s3_both.cc
new file mode 100644
index 00000000000..c735b2fca5d
--- /dev/null
+++ b/contrib/restricted/google/boringssl/ssl/s3_both.cc
@@ -0,0 +1,765 @@
+/* Copyright (C) 1995-1998 Eric Young ([email protected])
+ * All rights reserved.
+ *
+ * This package is an SSL implementation written
+ * by Eric Young ([email protected]).
+ * 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 ([email protected]).
+ *
+ * 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 ([email protected])"
+ *    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 ([email protected])"
+ *
+ * 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) 1998-2002 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
+ *    [email protected].
+ *
+ * 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
+ * ([email protected]).  This product includes software written by Tim
+ * Hudson ([email protected]). */
+/* ====================================================================
+ * Copyright 2002 Sun Microsystems, Inc. ALL RIGHTS RESERVED.
+ * ECC cipher suite support in OpenSSL originally developed by
+ * SUN MICROSYSTEMS, INC., and contributed to the OpenSSL project. */
+
+#include <contrib/restricted/google/boringssl/include/openssl/ssl.h>
+
+#include <assert.h>
+#include <limits.h>
+#include <string.h>
+
+#include <tuple>
+
+#include <contrib/restricted/google/boringssl/include/openssl/buf.h>
+#include <contrib/restricted/google/boringssl/include/openssl/bytestring.h>
+#include <contrib/restricted/google/boringssl/include/openssl/err.h>
+#include <contrib/restricted/google/boringssl/include/openssl/evp.h>
+#include <contrib/restricted/google/boringssl/include/openssl/mem.h>
+#include <contrib/restricted/google/boringssl/include/openssl/md5.h>
+#include <contrib/restricted/google/boringssl/include/openssl/nid.h>
+#include <contrib/restricted/google/boringssl/include/openssl/rand.h>
+#include <contrib/restricted/google/boringssl/include/openssl/sha.h>
+
+#include "../crypto/internal.h"
+#include "internal.h"
+
+
+BSSL_NAMESPACE_BEGIN
+
+static bool add_record_to_flight(SSL *ssl, uint8_t type,
+                                 Span<const uint8_t> in) {
+  // The caller should have flushed |pending_hs_data| first.
+  assert(!ssl->s3->pending_hs_data);
+  // We'll never add a flight while in the process of writing it out.
+  assert(ssl->s3->pending_flight_offset == 0);
+
+  if (ssl->s3->pending_flight == nullptr) {
+    ssl->s3->pending_flight.reset(BUF_MEM_new());
+    if (ssl->s3->pending_flight == nullptr) {
+      return false;
+    }
+  }
+
+  size_t max_out = in.size() + SSL_max_seal_overhead(ssl);
+  size_t new_cap = ssl->s3->pending_flight->length + max_out;
+  if (max_out < in.size() || new_cap < max_out) {
+    OPENSSL_PUT_ERROR(SSL, ERR_R_OVERFLOW);
+    return false;
+  }
+
+  size_t len;
+  if (!BUF_MEM_reserve(ssl->s3->pending_flight.get(), new_cap) ||
+      !tls_seal_record(ssl,
+                       (uint8_t *)ssl->s3->pending_flight->data +
+                           ssl->s3->pending_flight->length,
+                       &len, max_out, type, in.data(), in.size())) {
+    return false;
+  }
+
+  ssl->s3->pending_flight->length += len;
+  return true;
+}
+
+bool tls_init_message(const SSL *ssl, CBB *cbb, CBB *body, uint8_t type) {
+  // Pick a modest size hint to save most of the |realloc| calls.
+  if (!CBB_init(cbb, 64) ||
+      !CBB_add_u8(cbb, type) ||
+      !CBB_add_u24_length_prefixed(cbb, body)) {
+    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
+    CBB_cleanup(cbb);
+    return false;
+  }
+
+  return true;
+}
+
+bool tls_finish_message(const SSL *ssl, CBB *cbb, Array<uint8_t> *out_msg) {
+  return CBBFinishArray(cbb, out_msg);
+}
+
+bool tls_add_message(SSL *ssl, Array<uint8_t> msg) {
+  // Pack handshake data into the minimal number of records. This avoids
+  // unnecessary encryption overhead, notably in TLS 1.3 where we send several
+  // encrypted messages in a row. For now, we do not do this for the null
+  // cipher. The benefit is smaller and there is a risk of breaking buggy
+  // implementations.
+  //
+  // TODO(davidben): See if we can do this uniformly.
+  Span<const uint8_t> rest = msg;
+  if (ssl->quic_method == nullptr &&
+      ssl->s3->aead_write_ctx->is_null_cipher()) {
+    while (!rest.empty()) {
+      Span<const uint8_t> chunk = rest.subspan(0, ssl->max_send_fragment);
+      rest = rest.subspan(chunk.size());
+
+      if (!add_record_to_flight(ssl, SSL3_RT_HANDSHAKE, chunk)) {
+        return false;
+      }
+    }
+  } else {
+    while (!rest.empty()) {
+      // Flush if |pending_hs_data| is full.
+      if (ssl->s3->pending_hs_data &&
+          ssl->s3->pending_hs_data->length >= ssl->max_send_fragment &&
+          !tls_flush_pending_hs_data(ssl)) {
+        return false;
+      }
+
+      size_t pending_len =
+          ssl->s3->pending_hs_data ? ssl->s3->pending_hs_data->length : 0;
+      Span<const uint8_t> chunk =
+          rest.subspan(0, ssl->max_send_fragment - pending_len);
+      assert(!chunk.empty());
+      rest = rest.subspan(chunk.size());
+
+      if (!ssl->s3->pending_hs_data) {
+        ssl->s3->pending_hs_data.reset(BUF_MEM_new());
+      }
+      if (!ssl->s3->pending_hs_data ||
+          !BUF_MEM_append(ssl->s3->pending_hs_data.get(), chunk.data(),
+                          chunk.size())) {
+        return false;
+      }
+    }
+  }
+
+  ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_HANDSHAKE, msg);
+  // TODO(svaldez): Move this up a layer to fix abstraction for SSLTranscript on
+  // hs.
+  if (ssl->s3->hs != NULL &&
+      !ssl->s3->hs->transcript.Update(msg)) {
+    return false;
+  }
+  return true;
+}
+
+bool tls_flush_pending_hs_data(SSL *ssl) {
+  if (!ssl->s3->pending_hs_data || ssl->s3->pending_hs_data->length == 0) {
+    return true;
+  }
+
+  UniquePtr<BUF_MEM> pending_hs_data = std::move(ssl->s3->pending_hs_data);
+  auto data =
+      MakeConstSpan(reinterpret_cast<const uint8_t *>(pending_hs_data->data),
+                    pending_hs_data->length);
+  if (ssl->quic_method) {
+    if ((ssl->s3->hs == nullptr || !ssl->s3->hs->hints_requested) &&
+        !ssl->quic_method->add_handshake_data(ssl, ssl->s3->write_level,
+                                              data.data(), data.size())) {
+      OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_INTERNAL_ERROR);
+      return false;
+    }
+    return true;
+  }
+
+  return add_record_to_flight(ssl, SSL3_RT_HANDSHAKE, data);
+}
+
+bool tls_add_change_cipher_spec(SSL *ssl) {
+  static const uint8_t kChangeCipherSpec[1] = {SSL3_MT_CCS};
+
+  if (!tls_flush_pending_hs_data(ssl)) {
+    return false;
+  }
+
+  if (!ssl->quic_method &&
+      !add_record_to_flight(ssl, SSL3_RT_CHANGE_CIPHER_SPEC,
+                            kChangeCipherSpec)) {
+    return false;
+  }
+
+  ssl_do_msg_callback(ssl, 1 /* write */, SSL3_RT_CHANGE_CIPHER_SPEC,
+                      kChangeCipherSpec);
+  return true;
+}
+
+int tls_flush_flight(SSL *ssl) {
+  if (!tls_flush_pending_hs_data(ssl)) {
+    return -1;
+  }
+
+  if (ssl->quic_method) {
+    if (ssl->s3->write_shutdown != ssl_shutdown_none) {
+      OPENSSL_PUT_ERROR(SSL, SSL_R_PROTOCOL_IS_SHUTDOWN);
+      return -1;
+    }
+
+    if (!ssl->quic_method->flush_flight(ssl)) {
+      OPENSSL_PUT_ERROR(SSL, SSL_R_QUIC_INTERNAL_ERROR);
+      return -1;
+    }
+  }
+
+  if (ssl->s3->pending_flight == nullptr) {
+    return 1;
+  }
+
+  if (ssl->s3->write_shutdown != ssl_shutdown_none) {
+    OPENSSL_PUT_ERROR(SSL, SSL_R_PROTOCOL_IS_SHUTDOWN);
+    return -1;
+  }
+
+  static_assert(INT_MAX <= 0xffffffff, "int is larger than 32 bits");
+  if (ssl->s3->pending_flight->length > INT_MAX) {
+    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
+    return -1;
+  }
+
+  // If there is pending data in the write buffer, it must be flushed out before
+  // any new data in pending_flight.
+  if (!ssl->s3->write_buffer.empty()) {
+    int ret = ssl_write_buffer_flush(ssl);
+    if (ret <= 0) {
+      ssl->s3->rwstate = SSL_ERROR_WANT_WRITE;
+      return ret;
+    }
+  }
+
+  if (ssl->wbio == nullptr) {
+    OPENSSL_PUT_ERROR(SSL, SSL_R_BIO_NOT_SET);
+    return -1;
+  }
+
+  // Write the pending flight.
+  while (ssl->s3->pending_flight_offset < ssl->s3->pending_flight->length) {
+    int ret = BIO_write(
+        ssl->wbio.get(),
+        ssl->s3->pending_flight->data + ssl->s3->pending_flight_offset,
+        ssl->s3->pending_flight->length - ssl->s3->pending_flight_offset);
+    if (ret <= 0) {
+      ssl->s3->rwstate = SSL_ERROR_WANT_WRITE;
+      return ret;
+    }
+
+    ssl->s3->pending_flight_offset += ret;
+  }
+
+  if (BIO_flush(ssl->wbio.get()) <= 0) {
+    ssl->s3->rwstate = SSL_ERROR_WANT_WRITE;
+    return -1;
+  }
+
+  ssl->s3->pending_flight.reset();
+  ssl->s3->pending_flight_offset = 0;
+  return 1;
+}
+
+static ssl_open_record_t read_v2_client_hello(SSL *ssl, size_t *out_consumed,
+                                              Span<const uint8_t> in) {
+  *out_consumed = 0;
+  assert(in.size() >= SSL3_RT_HEADER_LENGTH);
+  // Determine the length of the V2ClientHello.
+  size_t msg_length = ((in[0] & 0x7f) << 8) | in[1];
+  if (msg_length > (1024 * 4)) {
+    OPENSSL_PUT_ERROR(SSL, SSL_R_RECORD_TOO_LARGE);
+    return ssl_open_record_error;
+  }
+  if (msg_length < SSL3_RT_HEADER_LENGTH - 2) {
+    // Reject lengths that are too short early. We have already read
+    // |SSL3_RT_HEADER_LENGTH| bytes, so we should not attempt to process an
+    // (invalid) V2ClientHello which would be shorter than that.
+    OPENSSL_PUT_ERROR(SSL, SSL_R_RECORD_LENGTH_MISMATCH);
+    return ssl_open_record_error;
+  }
+
+  // Ask for the remainder of the V2ClientHello.
+  if (in.size() < 2 + msg_length) {
+    *out_consumed = 2 + msg_length;
+    return ssl_open_record_partial;
+  }
+
+  CBS v2_client_hello = CBS(ssl->s3->read_buffer.span().subspan(2, msg_length));
+  // The V2ClientHello without the length is incorporated into the handshake
+  // hash. This is only ever called at the start of the handshake, so hs is
+  // guaranteed to be non-NULL.
+  if (!ssl->s3->hs->transcript.Update(v2_client_hello)) {
+    return ssl_open_record_error;
+  }
+
+  ssl_do_msg_callback(ssl, 0 /* read */, 0 /* V2ClientHello */,
+                      v2_client_hello);
+
+  uint8_t msg_type;
+  uint16_t version, cipher_spec_length, session_id_length, challenge_length;
+  CBS cipher_specs, session_id, challenge;
+  if (!CBS_get_u8(&v2_client_hello, &msg_type) ||
+      !CBS_get_u16(&v2_client_hello, &version) ||
+      !CBS_get_u16(&v2_client_hello, &cipher_spec_length) ||
+      !CBS_get_u16(&v2_client_hello, &session_id_length) ||
+      !CBS_get_u16(&v2_client_hello, &challenge_length) ||
+      !CBS_get_bytes(&v2_client_hello, &cipher_specs, cipher_spec_length) ||
+      !CBS_get_bytes(&v2_client_hello, &session_id, session_id_length) ||
+      !CBS_get_bytes(&v2_client_hello, &challenge, challenge_length) ||
+      CBS_len(&v2_client_hello) != 0) {
+    OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
+    return ssl_open_record_error;
+  }
+
+  // msg_type has already been checked.
+  assert(msg_type == SSL2_MT_CLIENT_HELLO);
+
+  // The client_random is the V2ClientHello challenge. Truncate or left-pad with
+  // zeros as needed.
+  size_t rand_len = CBS_len(&challenge);
+  if (rand_len > SSL3_RANDOM_SIZE) {
+    rand_len = SSL3_RANDOM_SIZE;
+  }
+  uint8_t random[SSL3_RANDOM_SIZE];
+  OPENSSL_memset(random, 0, SSL3_RANDOM_SIZE);
+  OPENSSL_memcpy(random + (SSL3_RANDOM_SIZE - rand_len), CBS_data(&challenge),
+                 rand_len);
+
+  // Write out an equivalent TLS ClientHello directly to the handshake buffer.
+  size_t max_v3_client_hello = SSL3_HM_HEADER_LENGTH + 2 /* version */ +
+                               SSL3_RANDOM_SIZE + 1 /* session ID length */ +
+                               2 /* cipher list length */ +
+                               CBS_len(&cipher_specs) / 3 * 2 +
+                               1 /* compression length */ + 1 /* compression */;
+  ScopedCBB client_hello;
+  CBB hello_body, cipher_suites;
+  if (!ssl->s3->hs_buf) {
+    ssl->s3->hs_buf.reset(BUF_MEM_new());
+  }
+  if (!ssl->s3->hs_buf ||
+      !BUF_MEM_reserve(ssl->s3->hs_buf.get(), max_v3_client_hello) ||
+      !CBB_init_fixed(client_hello.get(), (uint8_t *)ssl->s3->hs_buf->data,
+                      ssl->s3->hs_buf->max) ||
+      !CBB_add_u8(client_hello.get(), SSL3_MT_CLIENT_HELLO) ||
+      !CBB_add_u24_length_prefixed(client_hello.get(), &hello_body) ||
+      !CBB_add_u16(&hello_body, version) ||
+      !CBB_add_bytes(&hello_body, random, SSL3_RANDOM_SIZE) ||
+      // No session id.
+      !CBB_add_u8(&hello_body, 0) ||
+      !CBB_add_u16_length_prefixed(&hello_body, &cipher_suites)) {
+    return ssl_open_record_error;
+  }
+
+  // Copy the cipher suites.
+  while (CBS_len(&cipher_specs) > 0) {
+    uint32_t cipher_spec;
+    if (!CBS_get_u24(&cipher_specs, &cipher_spec)) {
+      OPENSSL_PUT_ERROR(SSL, SSL_R_DECODE_ERROR);
+      return ssl_open_record_error;
+    }
+
+    // Skip SSLv2 ciphers.
+    if ((cipher_spec & 0xff0000) != 0) {
+      continue;
+    }
+    if (!CBB_add_u16(&cipher_suites, cipher_spec)) {
+      OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
+      return ssl_open_record_error;
+    }
+  }
+
+  // Add the null compression scheme and finish.
+  if (!CBB_add_u8(&hello_body, 1) ||
+      !CBB_add_u8(&hello_body, 0) ||
+      !CBB_finish(client_hello.get(), NULL, &ssl->s3->hs_buf->length)) {
+    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
+    return ssl_open_record_error;
+  }
+
+  *out_consumed = 2 + msg_length;
+  ssl->s3->is_v2_hello = true;
+  return ssl_open_record_success;
+}
+
+static bool parse_message(const SSL *ssl, SSLMessage *out,
+                          size_t *out_bytes_needed) {
+  if (!ssl->s3->hs_buf) {
+    *out_bytes_needed = 4;
+    return false;
+  }
+
+  CBS cbs;
+  uint32_t len;
+  CBS_init(&cbs, reinterpret_cast<const uint8_t *>(ssl->s3->hs_buf->data),
+           ssl->s3->hs_buf->length);
+  if (!CBS_get_u8(&cbs, &out->type) ||
+      !CBS_get_u24(&cbs, &len)) {
+    *out_bytes_needed = 4;
+    return false;
+  }
+
+  if (!CBS_get_bytes(&cbs, &out->body, len)) {
+    *out_bytes_needed = 4 + len;
+    return false;
+  }
+
+  CBS_init(&out->raw, reinterpret_cast<const uint8_t *>(ssl->s3->hs_buf->data),
+           4 + len);
+  out->is_v2_hello = ssl->s3->is_v2_hello;
+  return true;
+}
+
+bool tls_get_message(const SSL *ssl, SSLMessage *out) {
+  size_t unused;
+  if (!parse_message(ssl, out, &unused)) {
+    return false;
+  }
+  if (!ssl->s3->has_message) {
+    if (!out->is_v2_hello) {
+      ssl_do_msg_callback(ssl, 0 /* read */, SSL3_RT_HANDSHAKE, out->raw);
+    }
+    ssl->s3->has_message = true;
+  }
+  return true;
+}
+
+bool tls_can_accept_handshake_data(const SSL *ssl, uint8_t *out_alert) {
+  // If there is a complete message, the caller must have consumed it first.
+  SSLMessage msg;
+  size_t bytes_needed;
+  if (parse_message(ssl, &msg, &bytes_needed)) {
+    OPENSSL_PUT_ERROR(SSL, ERR_R_INTERNAL_ERROR);
+    *out_alert = SSL_AD_INTERNAL_ERROR;
+    return false;
+  }
+
+  // Enforce the limit so the peer cannot force us to buffer 16MB.
+  if (bytes_needed > 4 + ssl_max_handshake_message_len(ssl)) {
+    OPENSSL_PUT_ERROR(SSL, SSL_R_EXCESSIVE_MESSAGE_SIZE);
+    *out_alert = SSL_AD_ILLEGAL_PARAMETER;
+    return false;
+  }
+
+  return true;
+}
+
+bool tls_has_unprocessed_handshake_data(const SSL *ssl) {
+  size_t msg_len = 0;
+  if (ssl->s3->has_message) {
+    SSLMessage msg;
+    size_t unused;
+    if (parse_message(ssl, &msg, &unused)) {
+      msg_len = CBS_len(&msg.raw);
+    }
+  }
+
+  return ssl->s3->hs_buf && ssl->s3->hs_buf->length > msg_len;
+}
+
+bool tls_append_handshake_data(SSL *ssl, Span<const uint8_t> data) {
+  // Re-create the handshake buffer if needed.
+  if (!ssl->s3->hs_buf) {
+    ssl->s3->hs_buf.reset(BUF_MEM_new());
+  }
+  return ssl->s3->hs_buf &&
+         BUF_MEM_append(ssl->s3->hs_buf.get(), data.data(), data.size());
+}
+
+ssl_open_record_t tls_open_handshake(SSL *ssl, size_t *out_consumed,
+                                     uint8_t *out_alert, Span<uint8_t> in) {
+  *out_consumed = 0;
+  // Bypass the record layer for the first message to handle V2ClientHello.
+  if (ssl->server && !ssl->s3->v2_hello_done) {
+    // Ask for the first 5 bytes, the size of the TLS record header. This is
+    // sufficient to detect a V2ClientHello and ensures that we never read
+    // beyond the first record.
+    if (in.size() < SSL3_RT_HEADER_LENGTH) {
+      *out_consumed = SSL3_RT_HEADER_LENGTH;
+      return ssl_open_record_partial;
+    }
+
+    // Some dedicated error codes for protocol mixups should the application
+    // wish to interpret them differently. (These do not overlap with
+    // ClientHello or V2ClientHello.)
+    const char *str = reinterpret_cast<const char*>(in.data());
+    if (strncmp("GET ", str, 4) == 0 ||
+        strncmp("POST ", str, 5) == 0 ||
+        strncmp("HEAD ", str, 5) == 0 ||
+        strncmp("PUT ", str, 4) == 0) {
+      OPENSSL_PUT_ERROR(SSL, SSL_R_HTTP_REQUEST);
+      *out_alert = 0;
+      return ssl_open_record_error;
+    }
+    if (strncmp("CONNE", str, 5) == 0) {
+      OPENSSL_PUT_ERROR(SSL, SSL_R_HTTPS_PROXY_REQUEST);
+      *out_alert = 0;
+      return ssl_open_record_error;
+    }
+
+    // Check for a V2ClientHello.
+    if ((in[0] & 0x80) != 0 && in[2] == SSL2_MT_CLIENT_HELLO &&
+        in[3] == SSL3_VERSION_MAJOR) {
+      auto ret = read_v2_client_hello(ssl, out_consumed, in);
+      if (ret == ssl_open_record_error) {
+        *out_alert = 0;
+      } else if (ret == ssl_open_record_success) {
+        ssl->s3->v2_hello_done = true;
+      }
+      return ret;
+    }
+
+    ssl->s3->v2_hello_done = true;
+  }
+
+  uint8_t type;
+  Span<uint8_t> body;
+  auto ret = tls_open_record(ssl, &type, &body, out_consumed, out_alert, in);
+  if (ret != ssl_open_record_success) {
+    return ret;
+  }
+
+  // WatchGuard's TLS 1.3 interference bug is very distinctive: they drop the
+  // ServerHello and send the remaining encrypted application data records
+  // as-is. This manifests as an application data record when we expect
+  // handshake. Report a dedicated error code for this case.
+  if (!ssl->server && type == SSL3_RT_APPLICATION_DATA &&
+      ssl->s3->aead_read_ctx->is_null_cipher()) {
+    OPENSSL_PUT_ERROR(SSL, SSL_R_APPLICATION_DATA_INSTEAD_OF_HANDSHAKE);
+    *out_alert = SSL_AD_UNEXPECTED_MESSAGE;
+    return ssl_open_record_error;
+  }
+
+  if (type != SSL3_RT_HANDSHAKE) {
+    OPENSSL_PUT_ERROR(SSL, SSL_R_UNEXPECTED_RECORD);
+    *out_alert = SSL_AD_UNEXPECTED_MESSAGE;
+    return ssl_open_record_error;
+  }
+
+  // Append the entire handshake record to the buffer.
+  if (!tls_append_handshake_data(ssl, body)) {
+    *out_alert = SSL_AD_INTERNAL_ERROR;
+    return ssl_open_record_error;
+  }
+
+  return ssl_open_record_success;
+}
+
+void tls_next_message(SSL *ssl) {
+  SSLMessage msg;
+  if (!tls_get_message(ssl, &msg) ||
+      !ssl->s3->hs_buf ||
+      ssl->s3->hs_buf->length < CBS_len(&msg.raw)) {
+    assert(0);
+    return;
+  }
+
+  OPENSSL_memmove(ssl->s3->hs_buf->data,
+                  ssl->s3->hs_buf->data + CBS_len(&msg.raw),
+                  ssl->s3->hs_buf->length - CBS_len(&msg.raw));
+  ssl->s3->hs_buf->length -= CBS_len(&msg.raw);
+  ssl->s3->is_v2_hello = false;
+  ssl->s3->has_message = false;
+
+  // Post-handshake messages are rare, so release the buffer after every
+  // message. During the handshake, |on_handshake_complete| will release it.
+  if (!SSL_in_init(ssl) && ssl->s3->hs_buf->length == 0) {
+    ssl->s3->hs_buf.reset();
+  }
+}
+
+// CipherScorer produces a "score" for each possible cipher suite offered by
+// the client.
+class CipherScorer {
+ public:
+  CipherScorer(bool has_aes_hw) : aes_is_fine_(has_aes_hw) {}
+
+  typedef std::tuple<bool, bool> Score;
+
+  // MinScore returns a |Score| that will compare less than the score of all
+  // cipher suites.
+  Score MinScore() const {
+    return Score(false, false);
+  }
+
+  Score Evaluate(const SSL_CIPHER *a) const {
+    return Score(
+        // Something is always preferable to nothing.
+        true,
+        // Either AES is fine, or else ChaCha20 is preferred.
+        aes_is_fine_ || a->algorithm_enc == SSL_CHACHA20POLY1305);
+  }
+
+ private:
+  const bool aes_is_fine_;
+};
+
+bool ssl_tls13_cipher_meets_policy(uint16_t cipher_id,
+                                   enum ssl_compliance_policy_t policy) {
+  switch (policy) {
+    case ssl_compliance_policy_none:
+      return true;
+
+    case ssl_compliance_policy_fips_202205:
+      switch (cipher_id) {
+        case TLS1_3_CK_AES_128_GCM_SHA256 & 0xffff:
+        case TLS1_3_CK_AES_256_GCM_SHA384 & 0xffff:
+          return true;
+        case TLS1_3_CK_CHACHA20_POLY1305_SHA256 & 0xffff:
+          return false;
+        default:
+          assert(false);
+          return false;
+      }
+
+    case ssl_compliance_policy_wpa3_192_202304:
+      switch (cipher_id) {
+        case TLS1_3_CK_AES_256_GCM_SHA384 & 0xffff:
+          return true;
+        case TLS1_3_CK_AES_128_GCM_SHA256 & 0xffff:
+        case TLS1_3_CK_CHACHA20_POLY1305_SHA256 & 0xffff:
+          return false;
+        default:
+          assert(false);
+          return false;
+      }
+  }
+
+  assert(false);
+  return false;
+}
+
+const SSL_CIPHER *ssl_choose_tls13_cipher(CBS cipher_suites, bool has_aes_hw,
+                                          uint16_t version,
+                                          enum ssl_compliance_policy_t policy) {
+  if (CBS_len(&cipher_suites) % 2 != 0) {
+    return nullptr;
+  }
+
+  const SSL_CIPHER *best = nullptr;
+  CipherScorer scorer(has_aes_hw);
+  CipherScorer::Score best_score = scorer.MinScore();
+
+  while (CBS_len(&cipher_suites) > 0) {
+    uint16_t cipher_suite;
+    if (!CBS_get_u16(&cipher_suites, &cipher_suite)) {
+      return nullptr;
+    }
+
+    // Limit to TLS 1.3 ciphers we know about.
+    const SSL_CIPHER *candidate = SSL_get_cipher_by_value(cipher_suite);
+    if (candidate == nullptr ||
+        SSL_CIPHER_get_min_version(candidate) > version ||
+        SSL_CIPHER_get_max_version(candidate) < version) {
+      continue;
+    }
+
+    if (!ssl_tls13_cipher_meets_policy(SSL_CIPHER_get_protocol_id(candidate),
+                                       policy)) {
+      continue;
+    }
+
+    const CipherScorer::Score candidate_score = scorer.Evaluate(candidate);
+    // |candidate_score| must be larger to displace the current choice. That way
+    // the client's order controls between ciphers with an equal score.
+    if (candidate_score > best_score) {
+      best = candidate;
+      best_score = candidate_score;
+    }
+  }
+
+  return best;
+}
+
+BSSL_NAMESPACE_END