// Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <openssl/ssl.h>

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

#include <openssl/err.h>

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


BSSL_NAMESPACE_BEGIN

static void tls_on_handshake_complete(SSLImpl *ssl) {
  // The handshake should have released its final message.
  assert(!ssl->s3->has_message);

  // During the handshake, `hs_buf` is retained. Release if it there is no
  // excess in it. There should not be any excess because the handshake logic
  // rejects unprocessed data after each Finished message. Note this means we do
  // not allow a TLS 1.2 HelloRequest to be packed into the same record as
  // Finished. (Schannel also rejects this.)
  assert(!ssl->s3->hs_buf || ssl->s3->hs_buf->length == 0);
  if (ssl->s3->hs_buf && ssl->s3->hs_buf->length == 0) {
    ssl->s3->hs_buf.reset();
  }
}

static bool tls_set_read_state(SSLImpl *ssl, ssl_encryption_level_t level,
                               UniquePtr<SSLAEADContext> aead_ctx,
                               Span<const uint8_t> traffic_secret) {
  // Cipher changes are forbidden if the current epoch has leftover data.
  if (tls_has_unprocessed_handshake_data(ssl)) {
    OPENSSL_PUT_ERROR(SSL, SSL_R_EXCESS_HANDSHAKE_DATA);
    ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);
    return false;
  }

  if (SSL_is_quic(ssl)) {
    if ((ssl->s3->hs == nullptr || ssl->s3->hs->pending_hints == nullptr) &&
        !ssl->quic_method->set_read_secret(ssl, level, aead_ctx->cipher(),
                                           traffic_secret.data(),
                                           traffic_secret.size())) {
      return false;
    }

    // QUIC only uses `ssl` for handshake messages, which never use early data
    // keys, so we return without installing anything. This avoids needing to
    // have two secrets active at once in 0-RTT.
    if (level == ssl_encryption_early_data) {
      return true;
    }
    ssl->s3->quic_read_level = level;
  }

  ssl->s3->read_sequence = 0;
  ssl->s3->aead_read_ctx = std::move(aead_ctx);
  return true;
}

static bool tls_set_write_state(SSLImpl *ssl, ssl_encryption_level_t level,
                                UniquePtr<SSLAEADContext> aead_ctx,
                                Span<const uint8_t> traffic_secret) {
  if (!tls_flush_pending_hs_data(ssl)) {
    return false;
  }

  if (SSL_is_quic(ssl)) {
    if ((ssl->s3->hs == nullptr || ssl->s3->hs->pending_hints == nullptr) &&
        !ssl->quic_method->set_write_secret(ssl, level, aead_ctx->cipher(),
                                            traffic_secret.data(),
                                            traffic_secret.size())) {
      return false;
    }

    // QUIC only uses `ssl` for handshake messages, which never use early data
    // keys, so we return without installing anything. This avoids needing to
    // have two secrets active at once in 0-RTT.
    if (level == ssl_encryption_early_data) {
      return true;
    }
    ssl->s3->quic_write_level = level;
  }

  ssl->s3->write_sequence = 0;
  ssl->s3->aead_write_ctx = std::move(aead_ctx);
  return true;
}

static void tls_finish_flight(SSLImpl *ssl) {
  // We don't track whether a flight is complete in TLS and instead always flush
  // every queued message in `tls_flush`, whether the flight is complete or not.
}

static void tls_schedule_ack(SSLImpl *ssl) {
  // TLS does not use ACKs.
}

static const SSL_PROTOCOL_METHOD kTLSProtocolMethod = {
    false /* is_dtls */,
    tls_new,
    tls_free,
    tls_get_message,
    tls_next_message,
    tls_has_unprocessed_handshake_data,
    tls_open_handshake,
    tls_open_change_cipher_spec,
    tls_open_app_data,
    tls_write_app_data,
    tls_dispatch_alert,
    tls_init_message,
    tls_finish_message,
    tls_add_message,
    tls_add_change_cipher_spec,
    tls_finish_flight,
    tls_schedule_ack,
    tls_flush,
    tls_on_handshake_complete,
    tls_set_read_state,
    tls_set_write_state,
};

static bool ssl_noop_x509_check_client_CA_names(
    STACK_OF(CRYPTO_BUFFER) *names) {
  return true;
}

static void ssl_noop_x509_clear(CERT *cert) {}
static void ssl_noop_x509_free(CERT *cert) {}
static void ssl_noop_x509_dup(CERT *new_cert, const CERT *cert) {}
static void ssl_noop_x509_flush_cached_leaf(CERT *cert) {}
static void ssl_noop_x509_flush_cached_chain(CERT *cert) {}
static bool ssl_noop_x509_session_cache_objects(SSLSession *sess) {
  return true;
}
static bool ssl_noop_x509_session_dup(SSLSession *new_session,
                                      const SSLSession *session) {
  return true;
}
static void ssl_noop_x509_session_clear(SSLSession *session) {}
static bool ssl_noop_x509_session_verify_cert_chain(SSLSession *session,
                                                    SSL_HANDSHAKE *hs,
                                                    uint8_t *out_alert) {
  return false;
}

static void ssl_noop_x509_hs_flush_cached_ca_names(SSL_HANDSHAKE *hs) {}
static bool ssl_noop_x509_ssl_new(SSL_HANDSHAKE *hs) { return true; }
static void ssl_noop_x509_ssl_config_free(SSL_CONFIG *cfg) {}
static void ssl_noop_x509_ssl_flush_cached_client_CA(SSL_CONFIG *cfg) {}
static bool ssl_noop_x509_ssl_auto_chain_if_needed(SSL_HANDSHAKE *hs) {
  return true;
}
static bool ssl_noop_x509_ssl_ctx_new(SSLContext *ctx) { return true; }
static void ssl_noop_x509_ssl_ctx_free(SSLContext *ctx) {}
static void ssl_noop_x509_ssl_ctx_flush_cached_client_CA(SSLContext *ctx) {}

const SSL_X509_METHOD ssl_noop_x509_method = {
    ssl_noop_x509_check_client_CA_names,
    ssl_noop_x509_clear,
    ssl_noop_x509_free,
    ssl_noop_x509_dup,
    ssl_noop_x509_flush_cached_chain,
    ssl_noop_x509_flush_cached_leaf,
    ssl_noop_x509_session_cache_objects,
    ssl_noop_x509_session_dup,
    ssl_noop_x509_session_clear,
    ssl_noop_x509_session_verify_cert_chain,
    ssl_noop_x509_hs_flush_cached_ca_names,
    ssl_noop_x509_ssl_new,
    ssl_noop_x509_ssl_config_free,
    ssl_noop_x509_ssl_flush_cached_client_CA,
    ssl_noop_x509_ssl_auto_chain_if_needed,
    ssl_noop_x509_ssl_ctx_new,
    ssl_noop_x509_ssl_ctx_free,
    ssl_noop_x509_ssl_ctx_flush_cached_client_CA,
};

BSSL_NAMESPACE_END

using namespace bssl;

const SSL_METHOD *TLS_method() {
  static const SSL_METHOD kMethod = {
      0,
      &kTLSProtocolMethod,
      &ssl_crypto_x509_method,
  };
  return &kMethod;
}

const SSL_METHOD *SSLv23_method() { return TLS_method(); }

const SSL_METHOD *TLS_with_buffers_method() {
  static const SSL_METHOD kMethod = {
      0,
      &kTLSProtocolMethod,
      &ssl_noop_x509_method,
  };
  return &kMethod;
}

// Legacy version-locked methods.

const SSL_METHOD *TLSv1_2_method() {
  static const SSL_METHOD kMethod = {
      TLS1_2_VERSION,
      &kTLSProtocolMethod,
      &ssl_crypto_x509_method,
  };
  return &kMethod;
}

const SSL_METHOD *TLSv1_1_method() {
  static const SSL_METHOD kMethod = {
      TLS1_1_VERSION,
      &kTLSProtocolMethod,
      &ssl_crypto_x509_method,
  };
  return &kMethod;
}

const SSL_METHOD *TLSv1_method() {
  static const SSL_METHOD kMethod = {
      TLS1_VERSION,
      &kTLSProtocolMethod,
      &ssl_crypto_x509_method,
  };
  return &kMethod;
}

// Legacy side-specific methods.

const SSL_METHOD *TLSv1_2_server_method() { return TLSv1_2_method(); }

const SSL_METHOD *TLSv1_1_server_method() { return TLSv1_1_method(); }

const SSL_METHOD *TLSv1_server_method() { return TLSv1_method(); }

const SSL_METHOD *TLSv1_2_client_method() { return TLSv1_2_method(); }

const SSL_METHOD *TLSv1_1_client_method() { return TLSv1_1_method(); }

const SSL_METHOD *TLSv1_client_method() { return TLSv1_method(); }

const SSL_METHOD *SSLv23_server_method() { return SSLv23_method(); }

const SSL_METHOD *SSLv23_client_method() { return SSLv23_method(); }

const SSL_METHOD *TLS_server_method() { return TLS_method(); }

const SSL_METHOD *TLS_client_method() { return TLS_method(); }