text: // Copyright (c) 2017 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 "quic/core/tls_client_handshaker.h"
  
  #include <cstring>
  #include <string>
  
  #include "absl/strings/str_cat.h"
  #include "absl/strings/string_view.h"
  #include "third_party/boringssl/src/include/openssl/ssl.h"
  #include "quic/core/crypto/quic_crypto_client_config.h"
  #include "quic/core/crypto/quic_encrypter.h"
  #include "quic/core/crypto/transport_parameters.h"
  #include "quic/core/quic_session.h"
  #include "quic/core/quic_types.h"
  #include "quic/platform/api/quic_flags.h"
  #include "quic/platform/api/quic_hostname_utils.h"
  #include "common/quiche_text_utils.h"
  
  namespace quic {
  
  TlsClientHandshaker::TlsClientHandshaker(
      const QuicServerId& server_id,
      QuicCryptoStream* stream,
      QuicSession* session,
      std::unique_ptr<ProofVerifyContext> verify_context,
      QuicCryptoClientConfig* crypto_config,
      QuicCryptoClientStream::ProofHandler* proof_handler,
      bool has_application_state)
      : TlsHandshaker(stream, session),
        session_(session),
        server_id_(server_id),
        proof_verifier_(crypto_config->proof_verifier()),
        verify_context_(std::move(verify_context)),
        proof_handler_(proof_handler),
        session_cache_(crypto_config->session_cache()),
        user_agent_id_(crypto_config->user_agent_id()),
        pre_shared_key_(crypto_config->pre_shared_key()),
        crypto_negotiated_params_(new QuicCryptoNegotiatedParameters),
        has_application_state_(has_application_state),
        crypto_config_(crypto_config),
        tls_connection_(crypto_config->ssl_ctx(), this, session->GetSSLConfig()) {
    std::string token =
        crypto_config->LookupOrCreate(server_id)->source_address_token();
    if (!token.empty()) {
      session->SetSourceAddressTokenToSend(token);
    }
  }
  
  TlsClientHandshaker::~TlsClientHandshaker() {}
  
  bool TlsClientHandshaker::CryptoConnect() {
    if (!pre_shared_key_.empty()) {
      // TODO(b/154162689) add PSK support to QUIC+TLS.
      std::string error_details =
          "QUIC client pre-shared keys not yet supported with TLS";
      QUIC_BUG(quic_bug_10576_1) << error_details;
      CloseConnection(QUIC_HANDSHAKE_FAILED, error_details);
      return false;
    }
  
    // Make sure we use the right TLS extension codepoint.
    int use_legacy_extension = 0;
    if (session()->version().UsesLegacyTlsExtension()) {
      use_legacy_extension = 1;
    }
    SSL_set_quic_use_legacy_codepoint(ssl(), use_legacy_extension);
  
    // TODO(b/193650832) Add SetFromConfig to QUIC handshakers and remove reliance
    // on session pointer.
    if (session()->permutes_tls_extensions()) {
      // Ask BoringSSL to randomize the order of TLS extensions.
  #if BORINGSSL_API_VERSION >= 16
      QUIC_DLOG(INFO) << "Enabling TLS extension permutation";
      SSL_set_permute_extensions(ssl(), true);
  #endif  // BORINGSSL_API_VERSION
    }
  
    // Set the SNI to send, if any.
    SSL_set_connect_state(ssl());
    if (QUIC_DLOG_INFO_IS_ON() &&
        !QuicHostnameUtils::IsValidSNI(server_id_.host())) {
      QUIC_DLOG(INFO) << "Client configured with invalid hostname \""
                      << server_id_.host() << "\", not sending as SNI";
    }
    if (!server_id_.host().empty() &&
        (QuicHostnameUtils::IsValidSNI(server_id_.host()) ||
         allow_invalid_sni_for_tests_) &&
        SSL_set_tlsext_host_name(ssl(), server_id_.host().c_str()) != 1) {
      return false;
    }
  
    if (!SetAlpn()) {
      CloseConnection(QUIC_HANDSHAKE_FAILED, "Client failed to set ALPN");
      return false;
    }
  
    // Set the Transport Parameters to send in the ClientHello
    if (!SetTransportParameters()) {
      CloseConnection(QUIC_HANDSHAKE_FAILED,
                      "Client failed to set Transport Parameters");
      return false;
    }
  
    // Set a session to resume, if there is one.
    if (session_cache_) {
      cached_state_ = session_cache_->Lookup(server_id_, SSL_get_SSL_CTX(ssl()));
    }
    if (cached_state_) {
      SSL_set_session(ssl(), cached_state_->tls_session.get());
    }
  
    // Start the handshake.
    AdvanceHandshake();
    return session()->connection()->connected();
  }
  
  bool TlsClientHandshaker::PrepareZeroRttConfig(
      QuicResumptionState* cached_state) {
    std::string error_details;
    if (!cached_state->transport_params ||
        handshaker_delegate()->ProcessTransportParameters(
            *(cached_state->transport_params),
            /*is_resumption = */ true, &error_details) != QUIC_NO_ERROR) {
      QUIC_BUG(quic_bug_10576_2)
          << "Unable to parse cached transport parameters.";
      CloseConnection(QUIC_HANDSHAKE_FAILED,
                      "Client failed to parse cached Transport Parameters.");
      return false;
    }
  
    session()->connection()->OnTransportParametersResumed(
        *(cached_state->transport_params));
    session()->OnConfigNegotiated();
  
    if (has_application_state_) {
      if (!cached_state->application_state ||
          !session()->ResumeApplicationState(
              cached_state->application_state.get())) {
        QUIC_BUG(quic_bug_10576_3) << "Unable to parse cached application state.";
        CloseConnection(QUIC_HANDSHAKE_FAILED,
                        "Client failed to parse cached application state.");
        return false;
      }
    }
    return true;
  }
  
  static bool IsValidAlpn(const std::string& alpn_string) {
    return alpn_string.length() <= std::numeric_limits<uint8_t>::max();
  }
  
  bool TlsClientHandshaker::SetAlpn() {
    std::vector<std::string> alpns = session()->GetAlpnsToOffer();
    if (alpns.empty()) {
      if (allow_empty_alpn_for_tests_) {
        return true;
      }
  
      QUIC_BUG(quic_bug_10576_4) << "ALPN missing";
      return false;
    }
    if (!std::all_of(alpns.begin(), alpns.end(), IsValidAlpn)) {
      QUIC_BUG(quic_bug_10576_5) << "ALPN too long";
      return false;
    }
  
    // SSL_set_alpn_protos expects a sequence of one-byte-length-prefixed
    // strings.
    uint8_t alpn[1024];
    QuicDataWriter alpn_writer(sizeof(alpn), reinterpret_cast<char*>(alpn));
    bool success = true;
    for (const std::string& alpn_string : alpns) {
      success = success && alpn_writer.WriteUInt8(alpn_string.size()) &&
                alpn_writer.WriteStringPiece(alpn_string);
    }
    success =
        success && (SSL_set_alpn_protos(ssl(), alpn, alpn_writer.length()) == 0);
    if (!success) {
      QUIC_BUG(quic_bug_10576_6)
          << "Failed to set ALPN: "
          << quiche::QuicheTextUtils::HexDump(
                 absl::string_view(alpn_writer.data(), alpn_writer.length()));
      return false;
    }
  
    // Enable ALPS only for versions that use HTTP/3 frames.
    for (const std::string& alpn_string : alpns) {
      ParsedQuicVersion version = ParseQuicVersionString(alpn_string);
      if (!version.IsKnown() || !version.UsesHttp3()) {
        continue;
      }
      if (SSL_add_application_settings(
              ssl(), reinterpret_cast<const uint8_t*>(alpn_string.data()),
              alpn_string.size(), nullptr, /* settings_len = */ 0) != 1) {
        QUIC_BUG(quic_bug_10576_7) << "Failed to enable ALPS.";
        return false;
      }
    }
  
    QUIC_DLOG(INFO) << "Client using ALPN: '" << alpns[0] << "'";
    return true;
  }
  
  bool TlsClientHandshaker::SetTransportParameters() {
    TransportParameters params;
    params.perspective = Perspective::IS_CLIENT;
    params.version =
        CreateQuicVersionLabel(session()->supported_versions().front());
  
    if (!handshaker_delegate()->FillTransportParameters(&params)) {
      return false;
    }
    if (!user_agent_id_.empty()) {
      params.user_agent_id = user_agent_id_;
    }
  
    // Notify QuicConnectionDebugVisitor.
    session()->connection()->OnTransportParametersSent(params);
  
    std::vector<uint8_t> param_bytes;
    return SerializeTransportParameters(session()->connection()->version(),
                                        params, &param_bytes) &&
           SSL_set_quic_transport_params(ssl(), param_bytes.data(),
                                         param_bytes.size()) == 1;
  }
  
  bool TlsClientHandshaker::ProcessTransportParameters(
      std::string* error_details) {
    received_transport_params_ = std::make_unique<TransportParameters>();
    const uint8_t* param_bytes;
    size_t param_bytes_len;
    SSL_get_peer_quic_transport_params(ssl(), &param_bytes, &param_bytes_len);
    if (param_bytes_len == 0) {
      *error_details = "Server's transport parameters are missing";
      return false;
    }
    std::string parse_error_details;
    if (!ParseTransportParameters(
            session()->connection()->version(), Perspective::IS_SERVER,
            param_bytes, param_bytes_len, received_transport_params_.get(),
            &parse_error_details)) {
      QUICHE_DCHECK(!parse_error_details.empty());
      *error_details =
          "Unable to parse server's transport parameters: " + parse_error_details;
      return false;
    }
  
    // Notify QuicConnectionDebugVisitor.
    session()->connection()->OnTransportParametersReceived(
        *received_transport_params_);
  
    // When interoperating with non-Google implementations that do not send
    // the version extension, set it to what we expect.
    if (received_transport_params_->version == 0) {
      received_transport_params_->version =
          CreateQuicVersionLabel(session()->connection()->version());
    }
    if (received_transport_params_->supported_versions.empty()) {
      received_transport_params_->supported_versions.push_back(
          received_transport_params_->version);
    }
  
    if (received_transport_params_->version !=
        CreateQuicVersionLabel(session()->connection()->version())) {
      *error_details = "Version mismatch detected";
      return false;
    }
    if (CryptoUtils::ValidateServerHelloVersions(
            received_transport_params_->supported_versions,
            session()->connection()->server_supported_versions(),
            error_details) != QUIC_NO_ERROR ||
        handshaker_delegate()->ProcessTransportParameters(
            *received_transport_params_, /* is_resumption = */ false,
            error_details) != QUIC_NO_ERROR) {
      QUICHE_DCHECK(!error_details->empty());
      return false;
    }
  
    session()->OnConfigNegotiated();
    if (is_connection_closed()) {
      *error_details =
          "Session closed the connection when parsing negotiated config.";
      return false;
    }
    return true;
  }
  
  int TlsClientHandshaker::num_sent_client_hellos() const {
    return 0;
  }
  
  bool TlsClientHandshaker::IsResumption() const {
    QUIC_BUG_IF(quic_bug_12736_1, !one_rtt_keys_available());
    return SSL_session_reused(ssl()) == 1;
  }
  
  bool TlsClientHandshaker::EarlyDataAccepted() const {
    QUIC_BUG_IF(quic_bug_12736_2, !one_rtt_keys_available());
    return SSL_early_data_accepted(ssl()) == 1;
  }
  
  ssl_early_data_reason_t TlsClientHandshaker::EarlyDataReason() const {
    return TlsHandshaker::EarlyDataReason();
  }
  
  bool TlsClientHandshaker::ReceivedInchoateReject() const {
    QUIC_BUG_IF(quic_bug_12736_3, !one_rtt_keys_available());
    // REJ messages are a QUIC crypto feature, so TLS always returns false.
    return false;
  }
  
  int TlsClientHandshaker::num_scup_messages_received() const {
    // SCUP messages aren't sent or received when using the TLS handshake.
    return 0;
  }
  
  std::string TlsClientHandshaker::chlo_hash() const {
    return "";
  }
  
  bool TlsClientHandshaker::encryption_established() const {
    return encryption_established_;
  }
  
  bool TlsClientHandshaker::one_rtt_keys_available() const {
    return state_ >= HANDSHAKE_COMPLETE;
  }
  
  const QuicCryptoNegotiatedParameters&
  TlsClientHandshaker::crypto_negotiated_params() const {
    return *crypto_negotiated_params_;
  }
  
  CryptoMessageParser* TlsClientHandshaker::crypto_message_parser() {
    return TlsHandshaker::crypto_message_parser();
  }
  
  HandshakeState TlsClientHandshaker::GetHandshakeState() const {
    return state_;
  }
  
  size_t TlsClientHandshaker::BufferSizeLimitForLevel(
      EncryptionLevel level) const {
    return TlsHandshaker::BufferSizeLimitForLevel(level);
  }
  
  bool TlsClientHandshaker::KeyUpdateSupportedLocally() const {
    return true;
  }
  
  std::unique_ptr<QuicDecrypter>
  TlsClientHandshaker::AdvanceKeysAndCreateCurrentOneRttDecrypter() {
    return TlsHandshaker::AdvanceKeysAndCreateCurrentOneRttDecrypter();
  }
  
  std::unique_ptr<QuicEncrypter>
  TlsClientHandshaker::CreateCurrentOneRttEncrypter() {
    return TlsHandshaker::CreateCurrentOneRttEncrypter();
  }
  
  void TlsClientHandshaker::OnOneRttPacketAcknowledged() {
    OnHandshakeConfirmed();
  }
  
  void TlsClientHandshaker::OnHandshakePacketSent() {
    if (initial_keys_dropped_) {
      return;
    }
    initial_keys_dropped_ = true;
    handshaker_delegate()->DiscardOldEncryptionKey(ENCRYPTION_INITIAL);
    handshaker_delegate()->DiscardOldDecryptionKey(ENCRYPTION_INITIAL);
  }
  
  void TlsClientHandshaker::OnConnectionClosed(QuicErrorCode error,
                                               ConnectionCloseSource source) {
    TlsHandshaker::OnConnectionClosed(error, source);
  }
  
  void TlsClientHandshaker::OnHandshakeDoneReceived() {
    if (!one_rtt_keys_available()) {
      CloseConnection(QUIC_HANDSHAKE_FAILED,
                      "Unexpected handshake done received");
      return;
    }
    OnHandshakeConfirmed();
  }
  
  void TlsClientHandshaker::OnNewTokenReceived(absl::string_view token) {
    if (token.empty()) {
      return;
    }
    QuicCryptoClientConfig::CachedState* cached =
        crypto_config_->LookupOrCreate(server_id_);
    cached->set_source_address_token(token);
  }
  
  void TlsClientHandshaker::SetWriteSecret(
      EncryptionLevel level,
      const SSL_CIPHER* cipher,
      const std::vector<uint8_t>& write_secret) {
    if (is_connection_closed()) {
      return;
    }
    if (level == ENCRYPTION_FORWARD_SECURE || level == ENCRYPTION_ZERO_RTT) {
      encryption_established_ = true;
    }
    TlsHandshaker::SetWriteSecret(level, cipher, write_secret);
    if (level == ENCRYPTION_FORWARD_SECURE) {
      handshaker_delegate()->DiscardOldEncryptionKey(ENCRYPTION_ZERO_RTT);
    }
  }
  
  void TlsClientHandshaker::OnHandshakeConfirmed() {
    QUICHE_DCHECK(one_rtt_keys_available());
    if (state_ >= HANDSHAKE_CONFIRMED) {
      return;
    }
    state_ = HANDSHAKE_CONFIRMED;
    handshaker_delegate()->DiscardOldEncryptionKey(ENCRYPTION_HANDSHAKE);
    handshaker_delegate()->DiscardOldDecryptionKey(ENCRYPTION_HANDSHAKE);
  }
  
  QuicAsyncStatus TlsClientHandshaker::VerifyCertChain(
      const std::vector<std::string>& certs,
      std::string* error_details,
      std::unique_ptr<ProofVerifyDetails>* details,
      uint8_t* out_alert,
      std::unique_ptr<ProofVerifierCallback> callback) {
    const uint8_t* ocsp_response_raw;
    size_t ocsp_response_len;
    SSL_get0_ocsp_response(ssl(), &ocsp_response_raw, &ocsp_response_len);
    std::string ocsp_response(reinterpret_cast<const char*>(ocsp_response_raw),
                              ocsp_response_len);
    const uint8_t* sct_list_raw;
    size_t sct_list_len;
    SSL_get0_signed_cert_timestamp_list(ssl(), &sct_list_raw, &sct_list_len);
    std::string sct_list(reinterpret_cast<const char*>(sct_list_raw),
                         sct_list_len);
  
    return proof_verifier_->VerifyCertChain(
        server_id_.host(), server_id_.port(), certs, ocsp_response, sct_list,
        verify_context_.get(), error_details, details, out_alert,
        std::move(callback));
  }
  
  void TlsClientHandshaker::OnProofVerifyDetailsAvailable(
      const ProofVerifyDetails& verify_details) {
    proof_handler_->OnProofVerifyDetailsAvailable(verify_details);
  }
  
  void TlsClientHandshaker::FinishHandshake() {
    FillNegotiatedParams();
  
    QUICHE_CHECK(!SSL_in_early_data(ssl()));
  
    QUIC_LOG(INFO) << "Client: handshake finished";
  
    std::string error_details;
    if (!ProcessTransportParameters(&error_details)) {
      QUICHE_DCHECK(!error_details.empty());
      CloseConnection(QUIC_HANDSHAKE_FAILED, error_details);
      return;
    }
  
    const uint8_t* alpn_data = nullptr;
    unsigned alpn_length = 0;
    SSL_get0_alpn_selected(ssl(), &alpn_data, &alpn_length);
  
    if (alpn_length == 0) {
      QUIC_DLOG(ERROR) << "Client: server did not select ALPN";
      // TODO(b/130164908) this should send no_application_protocol
      // instead of QUIC_HANDSHAKE_FAILED.
      CloseConnection(QUIC_HANDSHAKE_FAILED, "Server did not select ALPN");
      return;
    }
  
    std::string received_alpn_string(reinterpret_cast<const char*>(alpn_data),
                                     alpn_length);
    std::vector<std::string> offered_alpns = session()->GetAlpnsToOffer();
    if (std::find(offered_alpns.begin(), offered_alpns.end(),
                  received_alpn_string) == offered_alpns.end()) {
      QUIC_LOG(ERROR) << "Client: received mismatched ALPN '"
                      << received_alpn_string;
      // TODO(b/130164908) this should send no_application_protocol
      // instead of QUIC_HANDSHAKE_FAILED.
      CloseConnection(QUIC_HANDSHAKE_FAILED, "Client received mismatched ALPN");
      return;
    }
    session()->OnAlpnSelected(received_alpn_string);
    QUIC_DLOG(INFO) << "Client: server selected ALPN: '" << received_alpn_string
                    << "'";
  
    // Parse ALPS extension.
    const uint8_t* alps_data;
    size_t alps_length;
    SSL_get0_peer_application_settings(ssl(), &alps_data, &alps_length);
    if (alps_length > 0) {
      auto error = session()->OnAlpsData(alps_data, alps_length);
      if (error) {
        // Calling CloseConnection() is safe even in case OnAlpsData() has
        // already closed the connection.
        CloseConnection(
            QUIC_HANDSHAKE_FAILED,
            absl::StrCat("Error processing ALPS data: ", error.value()));
        return;
      }
    }
  
    state_ = HANDSHAKE_COMPLETE;
    handshaker_delegate()->OnTlsHandshakeComplete();
  }
  
  void TlsClientHandshaker::OnEnterEarlyData() {
    QUICHE_DCHECK(SSL_in_early_data(ssl()));
  
    // TODO(wub): It might be unnecessary to FillNegotiatedParams() at this time,
    // because we fill it again when handshake completes.
    FillNegotiatedParams();
  
    // If we're attempting a 0-RTT handshake, then we need to let the transport
    // and application know what state to apply to early data.
    PrepareZeroRttConfig(cached_state_.get());
  }
  
  void TlsClientHandshaker::FillNegotiatedParams() {
    const SSL_CIPHER* cipher = SSL_get_current_cipher(ssl());
    if (cipher) {
      crypto_negotiated_params_->cipher_suite =
          SSL_CIPHER_get_protocol_id(cipher);
    }
    crypto_negotiated_params_->key_exchange_group = SSL_get_curve_id(ssl());
    crypto_negotiated_params_->peer_signature_algorithm =
        SSL_get_peer_signature_algorithm(ssl());
  }
  
  void TlsClientHandshaker::ProcessPostHandshakeMessage() {
    int rv = SSL_process_quic_post_handshake(ssl());
    if (rv != 1) {
      CloseConnection(QUIC_HANDSHAKE_FAILED, "Unexpected post-handshake data");
    }
  }
  
  bool TlsClientHandshaker::ShouldCloseConnectionOnUnexpectedError(
      int ssl_error) {
    if (ssl_error != SSL_ERROR_EARLY_DATA_REJECTED) {
      return true;
    }
    HandleZeroRttReject();
    return false;
  }
  
  void TlsClientHandshaker::HandleZeroRttReject() {
    QUIC_LOG(INFO) << "0-RTT handshake attempted but was rejected by the server";
    QUICHE_DCHECK(session_cache_);
    // Disable encrytion to block outgoing data until 1-RTT keys are available.
    encryption_established_ = false;
    handshaker_delegate()->OnZeroRttRejected(EarlyDataReason());
    SSL_reset_early_data_reject(ssl());
    session_cache_->ClearEarlyData(server_id_);
    AdvanceHandshake();
  }
  
  void TlsClientHandshaker::InsertSession(bssl::UniquePtr<SSL_SESSION> session) {
    if (!received_transport_params_) {
      QUIC_BUG(quic_bug_10576_8) << "Transport parameters isn't received";
      return;
    }
    if (session_cache_ == nullptr) {
      QUIC_DVLOG(1) << "No session cache, not inserting a session";
      return;
    }
    if (has_application_state_ && !received_application_state_) {
      // Application state is not received yet. cache the sessions.
      if (cached_tls_sessions_[0] != nullptr) {
        cached_tls_sessions_[1] = std::move(cached_tls_sessions_[0]);
      }
      cached_tls_sessions_[0] = std::move(session);
      return;
    }
    session_cache_->Insert(server_id_, std::move(session),
                           *received_transport_params_,
                           received_application_state_.get());
  }
  
  void TlsClientHandshaker::WriteMessage(EncryptionLevel level,
                                         absl::string_view data) {
    if (level == ENCRYPTION_HANDSHAKE && state_ < HANDSHAKE_PROCESSED) {
      state_ = HANDSHAKE_PROCESSED;
    }
    TlsHandshaker::WriteMessage(level, data);
  }
  
  void TlsClientHandshaker::SetServerApplicationStateForResumption(
      std::unique_ptr<ApplicationState> application_state) {
    QUICHE_DCHECK(one_rtt_keys_available());
    received_application_state_ = std::move(application_state);
    // At least one tls session is cached before application state is received. So
    // insert now.
    if (session_cache_ != nullptr && cached_tls_sessions_[0] != nullptr) {
      if (cached_tls_sessions_[1] != nullptr) {
        // Insert the older session first.
        session_cache_->Insert(server_id_, std::move(cached_tls_sessions_[1]),
                               *received_transport_params_,
                               received_application_state_.get());
      }
      session_cache_->Insert(server_id_, std::move(cached_tls_sessions_[0]),
                             *received_transport_params_,
                             received_application_state_.get());
    }
  }
  
  }  // namespace quic
  