net/quic/quic_crypto_server_stream.cc

// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "net/quic/quic_crypto_server_stream.h"

#include "base/base64.h"
#include "crypto/secure_hash.h"
#include "net/quic/crypto/crypto_protocol.h"
#include "net/quic/crypto/crypto_utils.h"
#include "net/quic/crypto/quic_crypto_server_config.h"
#include "net/quic/crypto/quic_random.h"
#include "net/quic/proto/cached_network_parameters.pb.h"
#include "net/quic/quic_config.h"
#include "net/quic/quic_flags.h"
#include "net/quic/quic_protocol.h"
#include "net/quic/quic_session.h"

using std::string;

namespace net {

namespace {
bool HasFixedTag(const CryptoHandshakeMessage& message) {
  const QuicTag* received_tags;
  size_t received_tags_length;
  QuicErrorCode error =
      message.GetTaglist(kCOPT, &received_tags, &received_tags_length);
  if (error == QUIC_NO_ERROR) {
    DCHECK(received_tags);
    for (size_t i = 0; i < received_tags_length; ++i) {
      if (received_tags[i] == kFIXD) {
        return true;
      }
    }
  }
  return false;
}
}  // namespace

void ServerHelloNotifier::OnPacketAcked(
    int acked_bytes,
    QuicTime::Delta delta_largest_observed) {
  // The SHLO is sent in one packet.
  server_stream_->OnServerHelloAcked();
}

void ServerHelloNotifier::OnPacketRetransmitted(int /*retransmitted_bytes*/) {}

QuicCryptoServerStream::QuicCryptoServerStream(
    const QuicCryptoServerConfig* crypto_config,
    QuicSession* session)
    : QuicCryptoServerStreamBase(session),
      crypto_config_(crypto_config),
      validate_client_hello_cb_(nullptr),
      num_handshake_messages_(0),
      num_handshake_messages_with_server_nonces_(0),
      num_server_config_update_messages_sent_(0),
      use_stateless_rejects_if_peer_supported_(
          FLAGS_enable_quic_stateless_reject_support),
      peer_supports_stateless_rejects_(false) {
  DCHECK_EQ(Perspective::IS_SERVER, session->connection()->perspective());
}

QuicCryptoServerStream::~QuicCryptoServerStream() {
  CancelOutstandingCallbacks();
}

void QuicCryptoServerStream::CancelOutstandingCallbacks() {
  // Detach from the validation callback.  Calling this multiple times is safe.
  if (validate_client_hello_cb_ != nullptr) {
    validate_client_hello_cb_->Cancel();
    if (FLAGS_quic_set_client_hello_cb_nullptr) {
      validate_client_hello_cb_ = nullptr;
    }
  }
}

void QuicCryptoServerStream::OnHandshakeMessage(
    const CryptoHandshakeMessage& message) {
  QuicCryptoServerStreamBase::OnHandshakeMessage(message);
  ++num_handshake_messages_;

  // This block should be removed with support for QUIC_VERSION_25.
  if (FLAGS_quic_require_fix && !HasFixedTag(message)) {
    CloseConnection(QUIC_CRYPTO_MESSAGE_PARAMETER_NOT_FOUND);
    return;
  }

  // Do not process handshake messages after the handshake is confirmed.
  if (handshake_confirmed_) {
    CloseConnection(QUIC_CRYPTO_MESSAGE_AFTER_HANDSHAKE_COMPLETE);
    return;
  }

  if (message.tag() != kCHLO) {
    CloseConnection(QUIC_INVALID_CRYPTO_MESSAGE_TYPE);
    return;
  }

  if (validate_client_hello_cb_ != nullptr) {
    // Already processing some other handshake message.  The protocol
    // does not allow for clients to send multiple handshake messages
    // before the server has a chance to respond.
    CloseConnection(QUIC_CRYPTO_MESSAGE_WHILE_VALIDATING_CLIENT_HELLO);
    return;
  }

  validate_client_hello_cb_ = new ValidateCallback(this);
  return crypto_config_->ValidateClientHello(
      message, session()->connection()->peer_address().address(),
      session()->connection()->self_address().address(), version(),
      session()->connection()->clock(), &crypto_proof_,
      validate_client_hello_cb_);
}

void QuicCryptoServerStream::FinishProcessingHandshakeMessage(
    const CryptoHandshakeMessage& message,
    const ValidateClientHelloResultCallback::Result& result) {
  // Clear the callback that got us here.
  DCHECK(validate_client_hello_cb_ != nullptr);
  validate_client_hello_cb_ = nullptr;

  if (use_stateless_rejects_if_peer_supported_) {
    peer_supports_stateless_rejects_ = DoesPeerSupportStatelessRejects(message);
  }

  CryptoHandshakeMessage reply;
  string error_details;
  QuicErrorCode error =
      ProcessClientHello(message, result, &reply, &error_details);

  if (error != QUIC_NO_ERROR) {
    CloseConnectionWithDetails(error, error_details);
    return;
  }

  if (reply.tag() != kSHLO) {
    if (reply.tag() == kSREJ) {
      DCHECK(use_stateless_rejects_if_peer_supported_);
      DCHECK(peer_supports_stateless_rejects_);
      // Before sending the SREJ, cause the connection to save crypto packets
      // so that they can be added to the time wait list manager and
      // retransmitted.
      session()->connection()->EnableSavingCryptoPackets();
    }
    SendHandshakeMessage(reply);

    if (reply.tag() == kSREJ) {
      DCHECK(use_stateless_rejects_if_peer_supported_);
      DCHECK(peer_supports_stateless_rejects_);
      DCHECK(!handshake_confirmed());
      DVLOG(1) << "Closing connection "
               << session()->connection()->connection_id()
               << " because of a stateless reject.";
      session()->connection()->CloseConnection(
          QUIC_CRYPTO_HANDSHAKE_STATELESS_REJECT, /* from_peer */ false);
    }
    return;
  }

  // If we are returning a SHLO then we accepted the handshake.  Now
  // process the negotiated configuration options as part of the
  // session config.
  QuicConfig* config = session()->config();
  OverrideQuicConfigDefaults(config);
  error = config->ProcessPeerHello(message, CLIENT, &error_details);
  if (error != QUIC_NO_ERROR) {
    CloseConnectionWithDetails(error, error_details);
    return;
  }

  session()->OnConfigNegotiated();

  config->ToHandshakeMessage(&reply);

  // Receiving a full CHLO implies the client is prepared to decrypt with
  // the new server write key.  We can start to encrypt with the new server
  // write key.
  //
  // NOTE: the SHLO will be encrypted with the new server write key.
  session()->connection()->SetEncrypter(
      ENCRYPTION_INITIAL,
      crypto_negotiated_params_.initial_crypters.encrypter.release());
  session()->connection()->SetDefaultEncryptionLevel(ENCRYPTION_INITIAL);
  // Set the decrypter immediately so that we no longer accept unencrypted
  // packets.
  session()->connection()->SetDecrypter(
      ENCRYPTION_INITIAL,
      crypto_negotiated_params_.initial_crypters.decrypter.release());

  // We want to be notified when the SHLO is ACKed so that we can disable
  // HANDSHAKE_MODE in the sent packet manager.
  scoped_refptr<ServerHelloNotifier> server_hello_notifier(
      new ServerHelloNotifier(this));
  SendHandshakeMessage(reply, server_hello_notifier.get());

  session()->connection()->SetEncrypter(
      ENCRYPTION_FORWARD_SECURE,
      crypto_negotiated_params_.forward_secure_crypters.encrypter.release());
  session()->connection()->SetAlternativeDecrypter(
      ENCRYPTION_FORWARD_SECURE,
      crypto_negotiated_params_.forward_secure_crypters.decrypter.release(),
      false /* don't latch */);

  encryption_established_ = true;
  handshake_confirmed_ = true;
  session()->OnCryptoHandshakeEvent(QuicSession::HANDSHAKE_CONFIRMED);
}

void QuicCryptoServerStream::SendServerConfigUpdate(
    const CachedNetworkParameters* cached_network_params) {
  if (!handshake_confirmed_) {
    return;
  }

  CryptoHandshakeMessage server_config_update_message;
  if (!crypto_config_->BuildServerConfigUpdateMessage(
          session()->connection()->version(), previous_source_address_tokens_,
          session()->connection()->self_address().address(),
          session()->connection()->peer_address().address(),
          session()->connection()->clock(),
          session()->connection()->random_generator(),
          crypto_negotiated_params_, cached_network_params,
          &server_config_update_message)) {
    DVLOG(1) << "Server: Failed to build server config update (SCUP)!";
    return;
  }

  DVLOG(1) << "Server: Sending server config update: "
           << server_config_update_message.DebugString();
  const QuicData& data = server_config_update_message.GetSerialized();
  WriteOrBufferData(string(data.data(), data.length()), false, nullptr);

  ++num_server_config_update_messages_sent_;
}

void QuicCryptoServerStream::OnServerHelloAcked() {
  session()->connection()->OnHandshakeComplete();
}

uint8 QuicCryptoServerStream::NumHandshakeMessages() const {
  return num_handshake_messages_;
}

uint8 QuicCryptoServerStream::NumHandshakeMessagesWithServerNonces() const {
  return num_handshake_messages_with_server_nonces_;
}

int QuicCryptoServerStream::NumServerConfigUpdateMessagesSent() const {
  return num_server_config_update_messages_sent_;
}

const CachedNetworkParameters*
QuicCryptoServerStream::PreviousCachedNetworkParams() const {
  return previous_cached_network_params_.get();
}

bool QuicCryptoServerStream::UseStatelessRejectsIfPeerSupported() const {
  return use_stateless_rejects_if_peer_supported_;
}

bool QuicCryptoServerStream::PeerSupportsStatelessRejects() const {
  return peer_supports_stateless_rejects_;
}

void QuicCryptoServerStream::SetPeerSupportsStatelessRejects(
    bool peer_supports_stateless_rejects) {
  peer_supports_stateless_rejects_ = peer_supports_stateless_rejects;
}

void QuicCryptoServerStream::SetPreviousCachedNetworkParams(
    CachedNetworkParameters cached_network_params) {
  previous_cached_network_params_.reset(
      new CachedNetworkParameters(cached_network_params));
}

bool QuicCryptoServerStream::GetBase64SHA256ClientChannelID(
    string* output) const {
  if (!encryption_established_ ||
      crypto_negotiated_params_.channel_id.empty()) {
    return false;
  }

  const string& channel_id(crypto_negotiated_params_.channel_id);
  scoped_ptr<crypto::SecureHash> hash(
      crypto::SecureHash::Create(crypto::SecureHash::SHA256));
  hash->Update(channel_id.data(), channel_id.size());
  uint8 digest[32];
  hash->Finish(digest, sizeof(digest));

  base::Base64Encode(string(
      reinterpret_cast<const char*>(digest), sizeof(digest)), output);
  // Remove padding.
  size_t len = output->size();
  if (len >= 2) {
    if ((*output)[len - 1] == '=') {
      len--;
      if ((*output)[len - 1] == '=') {
        len--;
      }
      output->resize(len);
    }
  }
  return true;
}

QuicErrorCode QuicCryptoServerStream::ProcessClientHello(
    const CryptoHandshakeMessage& message,
    const ValidateClientHelloResultCallback::Result& result,
    CryptoHandshakeMessage* reply,
    string* error_details) {
  if (!result.info.server_nonce.empty()) {
    ++num_handshake_messages_with_server_nonces_;
  }
  // Store the bandwidth estimate from the client.
  if (result.cached_network_params.bandwidth_estimate_bytes_per_second() > 0) {
    previous_cached_network_params_.reset(
        new CachedNetworkParameters(result.cached_network_params));
  }
  previous_source_address_tokens_ = result.info.source_address_tokens;

  const bool use_stateless_rejects_in_crypto_config =
      use_stateless_rejects_if_peer_supported_ &&
      peer_supports_stateless_rejects_;
  QuicConnection* connection = session()->connection();
  const QuicConnectionId server_designated_connection_id =
      use_stateless_rejects_in_crypto_config
          ? GenerateConnectionIdForReject(connection->connection_id())
          : 0;
  return crypto_config_->ProcessClientHello(
      result, connection->connection_id(), connection->self_address().address(),
      connection->peer_address(), version(), connection->supported_versions(),
      use_stateless_rejects_in_crypto_config, server_designated_connection_id,
      connection->clock(), connection->random_generator(),
      &crypto_negotiated_params_, &crypto_proof_, reply, error_details);
}

void QuicCryptoServerStream::OverrideQuicConfigDefaults(QuicConfig* config) {
}

QuicCryptoServerStream::ValidateCallback::ValidateCallback(
    QuicCryptoServerStream* parent) : parent_(parent) {
}

void QuicCryptoServerStream::ValidateCallback::Cancel() { parent_ = nullptr; }

void QuicCryptoServerStream::ValidateCallback::RunImpl(
    const CryptoHandshakeMessage& client_hello,
    const Result& result) {
  if (parent_ != nullptr) {
    parent_->FinishProcessingHandshakeMessage(client_hello, result);
  }
}

QuicConnectionId QuicCryptoServerStream::GenerateConnectionIdForReject(
    QuicConnectionId connection_id) {
  return session()->connection()->random_generator()->RandUint64();
}

// TODO(jokulik): Once stateless rejects support is inherent in the version
// number, this function will likely go away entirely.
// static
bool QuicCryptoServerStream::DoesPeerSupportStatelessRejects(
    const CryptoHandshakeMessage& message) {
  const QuicTag* received_tags;
  size_t received_tags_length;
  QuicErrorCode error =
      message.GetTaglist(kCOPT, &received_tags, &received_tags_length);
  if (error != QUIC_NO_ERROR) {
    return false;
  }
  for (size_t i = 0; i < received_tags_length; ++i) {
    if (received_tags[i] == kSREJ) {
      return true;
    }
  }
  return false;
}

}  // namespace net