// Copyright 2005-2016 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"

using namespace bssl;

static void dtls1_on_handshake_complete(SSL *ssl) {

  if (ssl_protocol_version(ssl) <= TLS1_2_VERSION) {

    // Stop the reply timer left by the last flight we sent. In DTLS 1.2, the

    // retransmission timer ends when the handshake completes. If we sent the

    // final flight, we may still need to retransmit it, but that is driven by

    // messages from the peer.

    dtls1_stop_timer(ssl);

    // If the final flight had a reply, we know the peer has received it. If

    // not, we must leave the flight around for post-handshake retransmission.

    if (ssl->d1->flight_has_reply) {

      dtls_clear_outgoing_messages(ssl);

    }

  }

}

static bool next_epoch(const SSL *ssl, uint16_t *out,

                       ssl_encryption_level_t level, uint16_t prev) {

  switch (level) {

    case ssl_encryption_initial:

    case ssl_encryption_early_data:

    case ssl_encryption_handshake:

      *out = static_cast<uint16_t>(level);

      return true;

    case ssl_encryption_application:

      if (prev < ssl_encryption_application &&

          ssl_protocol_version(ssl) >= TLS1_3_VERSION) {

        *out = static_cast<uint16_t>(level);

        return true;

      }

      if (prev == 0xffff) {

        OPENSSL_PUT_ERROR(SSL, SSL_R_TOO_MANY_KEY_UPDATES);

        return false;

      }

      *out = prev + 1;

      return true;

  }

  assert(0);

  return false;

}

static bool dtls1_set_read_state(SSL *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 (dtls_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;

  }

  DTLSReadEpoch new_epoch;

  new_epoch.aead = std::move(aead_ctx);

  new_epoch.traffic_secret.CopyFrom(traffic_secret);

  if (!next_epoch(ssl, &new_epoch.epoch, level, ssl->d1->read_epoch.epoch)) {

    ssl_send_alert(ssl, SSL3_AL_FATAL, SSL_AD_UNEXPECTED_MESSAGE);

    return false;

  }

  if (ssl_protocol_version(ssl) > TLS1_2_VERSION) {

    new_epoch.rn_encrypter =

        RecordNumberEncrypter::Create(new_epoch.aead->cipher(), traffic_secret);

    if (new_epoch.rn_encrypter == nullptr) {

      return false;

    }

    // In DTLS 1.3, new read epochs are not applied immediately. In principle,

    // we could do the same in DTLS 1.2, but we would ignore every record from

    // the previous epoch anyway.

    assert(ssl->d1->next_read_epoch == nullptr);

    ssl->d1->next_read_epoch = MakeUnique<DTLSReadEpoch>(std::move(new_epoch));

    if (ssl->d1->next_read_epoch == nullptr) {

      return false;

    }

  } else {

    ssl->d1->read_epoch = std::move(new_epoch);

    ssl->d1->has_change_cipher_spec = false;

  }

  return true;

}

static bool dtls1_set_write_state(SSL *ssl, ssl_encryption_level_t level,

                                  UniquePtr<SSLAEADContext> aead_ctx,

                                  Span<const uint8_t> traffic_secret) {

  uint16_t epoch;

  if (!next_epoch(ssl, &epoch, level, ssl->d1->write_epoch.epoch())) {

    return false;

  }

  DTLSWriteEpoch new_epoch;

  new_epoch.aead = std::move(aead_ctx);

  new_epoch.next_record = DTLSRecordNumber(epoch, 0);

  new_epoch.traffic_secret.CopyFrom(traffic_secret);

  if (ssl_protocol_version(ssl) > TLS1_2_VERSION) {

    new_epoch.rn_encrypter =

        RecordNumberEncrypter::Create(new_epoch.aead->cipher(), traffic_secret);

    if (new_epoch.rn_encrypter == nullptr) {

      return false;

    }

  }

  auto current = MakeUnique<DTLSWriteEpoch>(std::move(ssl->d1->write_epoch));

  if (current == nullptr) {

    return false;

  }

  ssl->d1->write_epoch = std::move(new_epoch);

  ssl->d1->extra_write_epochs.PushBack(std::move(current));

  dtls_clear_unused_write_epochs(ssl);

  return true;

}

static const SSL_PROTOCOL_METHOD kDTLSProtocolMethod = {

    true /* is_dtls */,

    dtls1_new,

    dtls1_free,

    dtls1_get_message,

    dtls1_next_message,

    dtls_has_unprocessed_handshake_data,

    dtls1_open_handshake,

    dtls1_open_change_cipher_spec,

    dtls1_open_app_data,

    dtls1_write_app_data,

    dtls1_dispatch_alert,

    dtls1_init_message,

    dtls1_finish_message,

    dtls1_add_message,

    dtls1_add_change_cipher_spec,

    dtls1_finish_flight,

    dtls1_schedule_ack,

    dtls1_flush,

    dtls1_on_handshake_complete,

    dtls1_set_read_state,

    dtls1_set_write_state,

};

const SSL_METHOD *DTLS_method() {

  static const SSL_METHOD kMethod = {

      0,

      &kDTLSProtocolMethod,

      &ssl_crypto_x509_method,

  };

  return &kMethod;

}

const SSL_METHOD *DTLS_with_buffers_method() {

  static const SSL_METHOD kMethod = {

      0,

      &kDTLSProtocolMethod,

      &ssl_noop_x509_method,

  };

  return &kMethod;

}

// Legacy version-locked methods.

const SSL_METHOD *DTLSv1_2_method() {

  static const SSL_METHOD kMethod = {

      DTLS1_2_VERSION,

      &kDTLSProtocolMethod,

      &ssl_crypto_x509_method,

  };

  return &kMethod;

}

const SSL_METHOD *DTLSv1_method() {

  static const SSL_METHOD kMethod = {

      DTLS1_VERSION,

      &kDTLSProtocolMethod,

      &ssl_crypto_x509_method,

  };

  return &kMethod;

}

// Legacy side-specific methods.

const SSL_METHOD *DTLSv1_2_server_method() { return DTLSv1_2_method(); }

const SSL_METHOD *DTLSv1_server_method() { return DTLSv1_method(); }

const SSL_METHOD *DTLSv1_2_client_method() { return DTLSv1_2_method(); }

const SSL_METHOD *DTLSv1_client_method() { return DTLSv1_method(); }

const SSL_METHOD *DTLS_server_method() { return DTLS_method(); }

const SSL_METHOD *DTLS_client_method() { return DTLS_method(); }