Explicitly disallow multi-packet CHLOs. Protected by FLAGS_quic_disallow_multi_packet_chlo, default…

net/quic/quic_packet_creator.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_packet_creator.h"
 
 #include <algorithm>
 
 #include "base/logging.h"
 #include "base/macros.h"
+#include "net/quic/crypto/crypto_protocol.h"
 #include "net/quic/crypto/quic_random.h"
 #include "net/quic/quic_bug_tracker.h"
 #include "net/quic/quic_data_writer.h"
 #include "net/quic/quic_flags.h"
 #include "net/quic/quic_utils.h"
 
 using base::StringPiece;
 using std::make_pair;
 using std::max;
 using std::min;
@@ skipping 137 matching lines @@
                                     QuicIOVector iov,
                                     size_t iov_offset,
                                     QuicStreamOffset offset,
                                     bool fin,
                                     bool needs_full_padding,
                                     QuicFrame* frame) {
   if (!HasRoomForStreamFrame(id, offset)) {
     return false;
   }
   CreateStreamFrame(id, iov, iov_offset, offset, fin, frame);
+  // Explicitly disallow multi-packet CHLOs.
+  if (FLAGS_quic_disallow_multi_packet_chlo && id == kCryptoStreamId &&
+      frame->stream_frame->data_length >= sizeof(kCHLO) &&
+      strncmp(frame->stream_frame->data_buffer,
+              reinterpret_cast<const char*>(&kCHLO), sizeof(kCHLO)) == 0) {
+    DCHECK_EQ(static_cast<size_t>(0), iov_offset);

[Ryan Hamilton, 2016/05/25 02:29:20]

nit: instead of static cast, can you just do 0u?

+    if (frame->stream_frame->data_length < iov.iov->iov_len) {
+      const string error_details = "Client hello won't fit in a single packet.";
+      QUIC_BUG << error_details;
+      delegate_->OnUnrecoverableError(QUIC_CRYPTO_CHLO_TOO_LARGE, error_details,
+                                      ConnectionCloseSource::FROM_SELF);
+      delete frame->stream_frame;
+      return false;
+    }
+  }
   if (!AddFrame(*frame, /*save_retransmittable_frames=*/true)) {
     // Fails if we try to write unencrypted stream data.
     delete frame->stream_frame;
     return false;
   }
   if (needs_full_padding) {
     packet_.num_padding_bytes = -1;
   }
   return true;
 }
@@ skipping 437 matching lines @@
   // Switching path needs to update packet number length.
   UpdatePacketNumberLength(least_packet_awaited_by_peer, max_packets_in_flight);
 }
 
 bool QuicPacketCreator::IncludeNonceInPublicHeader() {
   return have_diversification_nonce_ &&
          packet_.encryption_level == ENCRYPTION_INITIAL;
 }
 
 }  // namespace net