ssl/dtls_method.cc

/*
 * DTLS implementation written by Nagendra Modadugu
 * (nagendra@cs.stanford.edu) for the OpenSSL project 2005.
 */
/* ====================================================================
 * Copyright (c) 1999-2005 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
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 *    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"
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 * 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
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 *
 * 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 <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 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);
  if (ssl_protocol_version(ssl) > TLS1_2_VERSION) {
    // TODO(crbug.com/42290594): Handle the additional epochs used for key
    // update.
    new_epoch.epoch = level;
    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 {
    new_epoch.epoch = ssl->d1->read_epoch.epoch + 1;
    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) {
  DTLSWriteEpoch new_epoch;
  if (ssl_protocol_version(ssl) > TLS1_2_VERSION) {
    // TODO(crbug.com/42290594): See above.
    new_epoch.next_record = DTLSRecordNumber(level, 0);
    new_epoch.rn_encrypter =
        RecordNumberEncrypter::Create(aead_ctx->cipher(), traffic_secret);
    if (new_epoch.rn_encrypter == nullptr) {
      return false;
    }
  } else {
    new_epoch.next_record =
        DTLSRecordNumber(ssl->d1->write_epoch.epoch() + 1, 0);
  }
  new_epoch.aead = std::move(aead_ctx);

  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_flush_flight,
    dtls1_send_ack,
    dtls1_on_handshake_complete,
    dtls1_set_read_state,
    dtls1_set_write_state,
};

const SSL_METHOD *DTLS_method(void) {
  static const SSL_METHOD kMethod = {
      0,
      &kDTLSProtocolMethod,
      &ssl_crypto_x509_method,
  };
  return &kMethod;
}

const SSL_METHOD *DTLS_with_buffers_method(void) {
  static const SSL_METHOD kMethod = {
      0,
      &kDTLSProtocolMethod,
      &ssl_noop_x509_method,
  };
  return &kMethod;
}

// Legacy version-locked methods.

const SSL_METHOD *DTLSv1_2_method(void) {
  static const SSL_METHOD kMethod = {
      DTLS1_2_VERSION,
      &kDTLSProtocolMethod,
      &ssl_crypto_x509_method,
  };
  return &kMethod;
}

const SSL_METHOD *DTLSv1_method(void) {
  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(void) { return DTLSv1_2_method(); }

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

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

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

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

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