Flag-protected. Add stateless reject support to crypto streams.

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 {
 
 void ServerHelloNotifier::OnAckNotification(
     int num_retransmitted_packets,
     int num_retransmitted_bytes,
     QuicTime::Delta delta_largest_observed) {
   server_stream_->OnServerHelloAcked();
 }
 
 QuicCryptoServerStream::QuicCryptoServerStream(
     const QuicCryptoServerConfig* crypto_config,
     QuicSession* session)
     : QuicCryptoStream(session),
       crypto_config_(crypto_config),
       validate_client_hello_cb_(nullptr),
       num_handshake_messages_(0),
-      num_server_config_update_messages_sent_(0) {
+      num_server_config_update_messages_sent_(0),
+      use_stateless_rejects_if_peer_supported_(false),
+      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) {
@@ skipping 31 matching lines @@
       session()->connection()->clock(), 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 (FLAGS_enable_quic_stateless_reject_support) {
+    peer_supports_stateless_rejects_ = DoesPeerSupportStatelessRejects(message);
+  }
+
+  CryptoHandshakeMessage reply;
   string error_details;
-  CryptoHandshakeMessage reply;
-  QuicErrorCode error = ProcessClientHello(
-      message, result, &reply, &error_details);
+  QuicErrorCode error =
+      ProcessClientHello(message, result, &reply, &error_details);
 
   if (error != QUIC_NO_ERROR) {
     CloseConnectionWithDetails(error, error_details);
     return;
   }
 
   if (reply.tag() != kSHLO) {
     SendHandshakeMessage(reply);
     return;
   }
 
-  // If we are returning a SHLO then we accepted the handshake.
+  // 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(
@@ skipping 96 matching lines @@
     const ValidateClientHelloResultCallback::Result& result,
     CryptoHandshakeMessage* reply,
     string* error_details) {
   // 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 =
+      FLAGS_enable_quic_stateless_reject_support &&
+      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= */ false,
-      /* server_designated_connection_id= */ 0, connection->clock(),
-      connection->random_generator(), &crypto_negotiated_params_, reply,
-      error_details);
+      use_stateless_rejects_in_crypto_config, server_designated_connection_id,
+      connection->clock(), connection->random_generator(),
+      &crypto_negotiated_params_, reply, error_details);
 }
 
 void QuicCryptoServerStream::OverrideQuicConfigDefaults(QuicConfig* config) {
 }
 
 const CachedNetworkParameters*
 QuicCryptoServerStream::previous_cached_network_params() const {
   return previous_cached_network_params_.get();
 }
 
 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