Add QuicFramer and friends.

net/quic/quic_framer.cc

Index: net/quic/quic_framer.cc
diff --git a/net/quic/quic_framer.cc b/net/quic/quic_framer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..fd9ddeb6f195d6d2ea9b1b25fe6b94a7306d4391
--- /dev/null
+++ b/net/quic/quic_framer.cc
@@ -0,0 +1,791 @@
+// 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_framer.h"
+
+#include "base/hash_tables.h"
+#include "net/quic/crypto/quic_decrypter.h"
+#include "net/quic/crypto/quic_encrypter.h"
+#include "net/quic/quic_data_reader.h"
+#include "net/quic/quic_data_writer.h"
+#include "net/quic/quic_utils.h"
+
+using base::hash_set;
+using base::StringPiece;
+
+namespace net {
+
+QuicFramer::QuicFramer(QuicDecrypter* decrypter, QuicEncrypter* encrypter)
+    : visitor_(NULL),
+      fec_builder_(NULL),
+      error_(QUIC_NO_ERROR),
+      decrypter_(decrypter),
+      encrypter_(encrypter) {
+}
+
+QuicFramer::~QuicFramer() {}
+
+bool QuicFramer::ConstructFragementDataPacket(
+    const QuicPacketHeader& header,
+    const QuicFragments& fragments,
+    QuicPacket** packet) {
+  // compute the length of the packet

[jar (doing other things), 2012/10/14 23:04:38]

nit: comments start with Upper-case, and end with periods.

[Ryan Hamilton, 2012/10/15 21:22:08]

Done.

+  size_t len = kPacketHeaderSize;
+  len += 1;  // fragment count

[jar (doing other things), 2012/10/14 23:04:38]

nit: IMO, nicer would be sizeof(some_named_member_)

[Ryan Hamilton, 2012/10/15 21:22:08]

That's a bit tricky because the sizeof(member_) is not guaranteed to be
sizeof(wire_format).  Added a number of comments.

+  for (size_t i = 0; i < fragments.size(); ++i) {
+    len += 1;  // space for the 8 bit type
+    len += ComputeFragmentPayloadLength(fragments[i]);
+  }
+
+  QuicDataWriter writer(len);
+
+  if (!WritePacketHeader(header, &writer)) {
+    return false;
+  }
+
+  // fragment count
+  if (!writer.WriteUInt8(fragments.size())) {

[jar (doing other things), 2012/10/14 23:04:38]

Do we have guarantees that framents.size() is less than 8 bits?  For consistency
in this method, it might be nice to assign the value to a uint8, and use that
local value. Line 52 made me wonder what would happen if the value was larger.

[Ryan Hamilton, 2012/10/15 21:22:08]

Added DCHECK

+    return false;
+  }
+
+  for (size_t i = 0; i < fragments.size(); ++i) {
+    const QuicFragment& fragment = fragments[i];
+    if (!writer.WriteUInt8(fragment.type)) {
+          return false;
+    }
+
+    switch (fragment.type) {
+      case STREAM_FRAGMENT:
+        if (!AppendStreamFragmentPayload(*fragment.stream_fragment,
+                                         &writer)) {
+          return false;
+        }
+        break;
+      case PDU_FRAGMENT:
+        return RaiseError(QUIC_INVALID_FRAGMENT_DATA);
+      case ACK_FRAGMENT:
+        if (!AppendAckFragmentPayload(*fragment.ack_fragment, &writer)) {
+          return false;
+        }
+        break;
+      case RST_STREAM_FRAGMENT:
+        if (!AppendRstStreamFragmentPayload(*fragment.rst_stream_fragment,
+                                            &writer)) {
+          return false;
+        }
+        break;
+      case CONNECTION_CLOSE_FRAGMENT:
+        if (!AppendConnectionCloseFragmentPayload(
+            *fragment.connection_close_fragment, &writer)) {
+          return false;
+        }
+        break;
+      default:
+        return RaiseError(QUIC_INVALID_FRAGMENT_DATA);
+    }
+  }
+
+  *packet = new QuicPacket(writer.take(), len, true);
+  if (fec_builder_) {
+    fec_builder_->OnBuiltFecProtectedPayload(header,
+                                             (*packet)->FecProtectedData());
+  }
+
+  return true;
+}
+
+bool QuicFramer::ConstructFecPacket(const QuicPacketHeader& header,
+                                    const QuicFecData& fec,
+                                    QuicPacket** packet) {
+  // compute the length of the packet
+  size_t len = kPacketHeaderSize;
+  len += 6;  // first protected packet sequence number
+  len += fec.redundancy.length();
+
+  QuicDataWriter writer(len);
+
+  if (!WritePacketHeader(header, &writer)) {
+    return false;
+  }
+
+  if (!writer.WriteUInt48(fec.first_protected_packet_sequence_number)) {
+    return false;
+  }
+
+  if (!writer.WriteBytes(fec.redundancy.data(), fec.redundancy.length())) {
+    return false;
+  }
+
+  *packet = new QuicPacket(writer.take(), len, true);
+
+  return true;
+}
+
+void QuicFramer::IncrementRetransmitCount(QuicPacket* packet) {
+  DCHECK_GT(packet->length(), kPacketHeaderSize);

[jar (doing other things), 2012/10/14 23:04:38]

A CHECK is a bit tempting here.  I'm not sure about the context of this call...
but then again, it is called rarely at most, so a CHECK might be NBD.

...also... this stuff *might* go away if we don't retransmit.

[Ryan Hamilton, 2012/10/15 21:22:08]

In general we really don't want the server to crash in release mode.  DCHECK
(i.e. crash in debug mode) is totally fine.  But crashing in release mode is
highly undesirable.

[jar (doing other things), 2012/10/15 23:54:32]

It sure seems evil to increment memory that is not really ours... even in a
server scenario.  That is the big fear here.  If you hate the CHECK, maybe a
test, and then noop if invalid?

On 2012/10/15 21:22:08, Ryan Hamilton wrote:

[Ryan Hamilton, 2012/10/16 00:03:56]

Done.  I'll attempt to land a CHECK on the server side an can hash out a better
alternative there.

+
+  ++packet->mutable_data()[kRetransmissionOffset];
+}
+
+uint8 QuicFramer::GetRetransmitCount(QuicPacket* packet) {
+  DCHECK_GT(packet->length(), kPacketHeaderSize);
+
+  return packet->mutable_data()[kRetransmissionOffset];
+}
+
+bool QuicFramer::ProcessPacket(const IPEndPoint& peer_address,
+                               const QuicEncryptedPacket& packet) {
+  LOG(INFO) << "here!";

[jar (doing other things), 2012/10/14 23:04:38]

nit: DLOG

[Ryan Hamilton, 2012/10/15 21:22:08]

Removed.

+  DCHECK(!reader_.get());
+  reader_.reset(new QuicDataReader(packet.data(), packet.length()));
+  visitor_->OnPacket(peer_address);
+
+  // First parse the packet header.
+  QuicPacketHeader header;
+  if (!ProcessPacketHeader(&header, packet)) {
+    DLOG(WARNING) << "Unable to process header.";
+    return RaiseError(QUIC_INVALID_PACKET_HEADER);
+  }
+
+  if (!visitor_->OnPacketHeader(header)) {
+    reader_.reset(NULL);
+    return true;
+  }
+
+  if (packet.length() > kMaxPacketSize) {
+    DLOG(WARNING) << "Packet too large: " << packet.length();
+    return RaiseError(QUIC_PACKET_TOO_LARGE);
+  }
+
+  // Handle the payload.
+  if ((header.flags & PACKET_FLAGS_FEC) == 0) {
+    if (header.fec_group != 0) {
+      StringPiece payload = reader_->PeekRemainingPayload();
+      visitor_->OnFecProtectedPayload(payload);
+    }
+    if (!ProcessFragmentData()) {
+      DLOG(WARNING) << "Unable to process fragment data.";
+      return false;
+    }
+  } else {
+    QuicFecData fec_data;
+    fec_data.fec_group = header.fec_group;
+    if (!reader_->ReadUInt48(
+            &fec_data.first_protected_packet_sequence_number)) {
+      set_detailed_error("Unable to read first protected packet.");
+      return false;
+    }
+
+    fec_data.redundancy = reader_->ReadRemainingPayload();
+    visitor_->OnFecData(fec_data);
+  }
+
+  visitor_->OnPacketComplete();
+  reader_.reset(NULL);

[jar (doing other things), 2012/10/14 23:04:38]

I wasn't clear about when you wanted to delete reader_, and when you returned
false, but didn't delete it. Why is it valuable to save it sometimes (in some
error conditions)?

[Ryan Hamilton, 2012/10/15 21:22:08]

I believe it is dropped everywhere.  Note the DCHECK at the start of
ProcessPacket:

  DCHECK(!reader_.get());

[jar (doing other things), 2012/10/15 23:54:32]

There are a bunch of early returns that don't *seem* to reset reader_.  Line
158, 169 and 177 are examples. 

[Ryan Hamilton, 2012/10/16 00:03:56]

You're talking about this, right:

	 158     return RaiseError(QUIC_PACKET_TOO_LARGE);

I think that's ok.  Look at the definition of RaiseError, which includes:

 787   reader_.reset(NULL);

[Ryan Hamilton, 2012/10/16 16:46:47]

Looks like 166 and 177 do not RaiseError.  I'll fix and then upstream.  Thanks
for the catch.

+  return true;
+}
+
+bool QuicFramer::ProcessRevivedPacket(const IPEndPoint& peer_address,
+                                      const QuicPacketHeader& header,
+                                      StringPiece payload) {
+  DCHECK(!reader_.get());
+
+  visitor_->OnPacket(peer_address);
+
+  visitor_->OnPacketHeader(header);
+
+  if (payload.length() > kMaxPacketSize) {
+    set_detailed_error("Revived packet too large.");
+    return RaiseError(QUIC_PACKET_TOO_LARGE);
+  }
+
+  reader_.reset(new QuicDataReader(payload.data(), payload.length()));
+  if (!ProcessFragmentData()) {
+    DLOG(WARNING) << "Unable to process fragment data.";

[jar (doing other things), 2012/10/14 23:04:38]

This appears to be the only path where reader_ is not dropped.  How is it
further used in this case?

[Ryan Hamilton, 2012/10/15 21:22:08]

I believe it is dropped here because RaiseError is called from
ProcessFragmentData().

+    return false;
+  }
+
+  visitor_->OnPacketComplete();
+  reader_.reset(NULL);
+  return true;
+}
+
+bool QuicFramer::WritePacketHeader(const QuicPacketHeader& header,
+                                   QuicDataWriter* writer) {
+  // ConnectionHeader
+  if (!writer->WriteUInt64(header.guid)) {
+    return false;
+  }
+
+  if (!writer->WriteUInt48(header.packet_sequence_number)) {
+    return false;
+  }
+
+  if (!writer->WriteBytes(&header.retransmission_count, 1)) {
+    return false;
+  }
+
+  // CongestionMonitoredHeader
+  if (!writer->WriteUInt64(header.transmission_time)) {
+    return false;
+  }
+
+  uint8 flags = static_cast<uint8>(header.flags);
+  if (!writer->WriteBytes(&flags, 1)) {
+     return false;
+  }
+
+  if (!writer->WriteBytes(&header.fec_group, 1)) {
+    return false;
+  }
+
+  return true;
+}
+
+bool QuicFramer::ProcessPacketHeader(QuicPacketHeader* header,
+                                     const QuicEncryptedPacket& packet) {
+  LOG(INFO) << "here!";
+  // ConnectionHeader
+  if (!reader_->ReadUInt64(&header->guid)) {
+    set_detailed_error("Unable to read GUID.");
+    return false;
+  }
+
+  LOG(INFO) << "here!";
+  if (!reader_->ReadUInt48(&header->packet_sequence_number)) {
+    set_detailed_error("Unable to read sequence number.");
+    return false;
+  }
+
+  LOG(INFO) << "here!";
+  if (!reader_->ReadBytes(&header->retransmission_count, 1)) {
+    set_detailed_error("Unable to read retransmission count.");
+    return false;
+  }
+
+  // CongestionMonitoredHeader
+  LOG(INFO) << "here!";
+  if (!reader_->ReadUInt64(&header->transmission_time)) {
+    set_detailed_error("Unable to read transmission time.");
+    return false;
+  }
+
+  unsigned char flags;
+  LOG(INFO) << "here!";
+  if (!reader_->ReadBytes(&flags, 1)) {
+    set_detailed_error("Unable to read flags.");
+    return false;
+  }
+
+  LOG(INFO) << "here!";
+  if (flags > PACKET_FLAGS_MAX) {
+    set_detailed_error("Illegal flags value.");
+    return false;
+  }
+
+  LOG(INFO) << "here!";
+  header->flags = static_cast<QuicPacketFlags>(flags);
+
+  LOG(INFO) << "here!";
+  if (!DecryptPayload(packet)) {
+    DLOG(WARNING) << "Unable to decrypt payload.";
+    return RaiseError(QUIC_DECRYPTION_FAILURE);
+  }
+
+  LOG(INFO) << "here!";
+  if (!reader_->ReadBytes(&header->fec_group, 1)) {
+    set_detailed_error("Unable to read fec group.");
+    return false;
+  }
+
+  LOG(INFO) << "done!";
+  return true;
+}
+
+bool QuicFramer::ProcessFragmentData() {
+  uint8 fragment_count;
+  if (!reader_->ReadBytes(&fragment_count, 1)) {
+    set_detailed_error("Unable to read fragment count.");
+    return RaiseError(QUIC_INVALID_FRAGMENT_DATA);
+  }
+
+  for (uint8 i = 0; i < fragment_count; ++i) {
+    uint8 fragment_type;
+    if (!reader_->ReadBytes(&fragment_type, 1)) {
+      set_detailed_error("Unable to read fragment type.");
+      return RaiseError(QUIC_INVALID_FRAGMENT_DATA);
+    }
+    switch (fragment_type) {
+      case STREAM_FRAGMENT:
+        if (!ProcessStreamFragment()) {
+          return RaiseError(QUIC_INVALID_FRAGMENT_DATA);
+        }
+        break;
+      case PDU_FRAGMENT:
+        if (!ProcessPDUFragment()) {
+          return RaiseError(QUIC_INVALID_FRAGMENT_DATA);
+        }
+        break;
+      case ACK_FRAGMENT: {
+        QuicAckFragment fragment;
+        if (!ProcessAckFragment(&fragment)) {
+          return RaiseError(QUIC_INVALID_FRAGMENT_DATA);
+        }
+        break;
+      }
+      case RST_STREAM_FRAGMENT:
+        if (!ProcessRstStreamFragment()) {
+          return RaiseError(QUIC_INVALID_RST_STREAM_DATA);
+        }
+        break;
+      case CONNECTION_CLOSE_FRAGMENT:
+        if (!ProcessConnectionCloseFragment()) {
+          return RaiseError(QUIC_INVALID_CONNECTION_CLOSE_DATA);
+        }
+        break;
+      default:
+        set_detailed_error("Illegal fragment type.");
+        DLOG(WARNING) << "Illegal fragment type: " << (int)fragment_type;
+        return RaiseError(QUIC_INVALID_FRAGMENT_DATA);
+    }
+  }
+
+  return true;
+}
+
+bool QuicFramer::ProcessStreamFragment() {
+  QuicStreamFragment fragment;
+  if (!reader_->ReadUInt32(&fragment.stream_id)) {
+    set_detailed_error("Unable to read stream_id.");
+    return false;
+  }
+
+  uint8 fin;
+  if (!reader_->ReadBytes(&fin, 1)) {
+    set_detailed_error("Unable to read fin.");
+    return false;
+  }
+  if (fin > 1) {
+    return false;

[jar (doing other things), 2012/10/14 23:04:38]

nit: perhaps set detailed error?

[Ryan Hamilton, 2012/10/15 21:22:08]

Done.  I assume this code path will change at some point once we start bit
packing.

+  }
+  fragment.fin = (fin == 1);
+
+  if (!reader_->ReadUInt64(&fragment.offset)) {
+    set_detailed_error("Unable to read offset.");
+    return false;
+  }
+
+  if (!reader_->ReadStringPiece16(&fragment.data)) {
+    set_detailed_error("Unable to read fragment data.");
+    return false;
+  }
+
+  visitor_->OnStreamFragment(fragment);
+  return true;
+}
+
+bool QuicFramer::ProcessPDUFragment() {
+  return false;
+}
+
+bool QuicFramer::ProcessAckFragment(QuicAckFragment* fragment) {
+  if (!reader_->ReadUInt48(&fragment->received_info.largest_received)) {
+    set_detailed_error("Unable to read largest received.");
+    return false;
+  }
+
+  if (!reader_->ReadUInt64(&fragment->received_info.time_received)) {
+    set_detailed_error("Unable to read time received.");
+    return false;
+  }
+
+  uint8 num_unacked_packets;
+  if (!reader_->ReadBytes(&num_unacked_packets, 1)) {
+    set_detailed_error("Unable to read num unacked packets.");
+    return false;
+  }
+
+  for (int i = 0; i < num_unacked_packets; ++i) {
+    QuicPacketSequenceNumber sequence_number;
+    if (!reader_->ReadUInt48(&sequence_number)) {
+      set_detailed_error("Unable to read sequence number in unacked packets.");
+      return false;
+    }
+    fragment->received_info.missing_packets.insert(sequence_number);
+  }
+
+  if (!reader_->ReadUInt48(&fragment->sent_info.least_unacked)) {
+    set_detailed_error("Unable to read least unacked.");
+    return false;
+  }
+
+  uint8 num_non_retransmiting_packets;
+  if (!reader_->ReadBytes(&num_non_retransmiting_packets, 1)) {
+    set_detailed_error("Unable to read num non-retransmitting.");
+    return false;
+  }
+  for (uint8 i = 0; i < num_non_retransmiting_packets; ++i) {
+    QuicPacketSequenceNumber sequence_number;
+    if (!reader_->ReadUInt48(&sequence_number)) {
+      set_detailed_error(
+          "Unable to read sequence number in non-retransmitting.");
+      return false;
+    }
+    fragment->sent_info.non_retransmiting.insert(sequence_number);
+  }
+
+  uint8 congestion_info_type;
+  if (!reader_->ReadBytes(&congestion_info_type, 1)) {
+    set_detailed_error("Unable to read congestion info type.");
+    return false;
+  }
+  fragment->congestion_info.type =
+      static_cast<CongestionFeedbackType>(congestion_info_type);
+
+  switch (fragment->congestion_info.type) {
+    case kNone:
+      break;
+    case kInterArrival: {
+      CongestionFeedbackMessageInterArrival* inter_arrival =
+          &fragment->congestion_info.inter_arrival;
+      if (!reader_->ReadUInt16(
+              &inter_arrival->accumulated_number_of_lost_packets)) {
+        set_detailed_error(
+            "Unable to read accumulated number of lost packets.");
+        return false;
+      }
+      if (!reader_->ReadBytes(&inter_arrival->offset_time, 2)) {
+        set_detailed_error("Unable to read offset time.");
+        return false;
+      }
+      if (!reader_->ReadUInt16(&inter_arrival->delta_time)) {
+        set_detailed_error("Unable to read delta time.");
+        return false;
+      }
+      break;
+    }
+    case kFixRate: {
+      CongestionFeedbackMessageFixRate* fix_rate =
+          &fragment->congestion_info.fix_rate;
+      if (!reader_->ReadUInt32(&fix_rate->bitrate_in_bytes_per_second)) {
+        set_detailed_error("Unable to read bitrate.");
+        return false;
+      }
+      break;
+    }
+    case kTCP: {
+      CongestionFeedbackMessageTCP* tcp = &fragment->congestion_info.tcp;
+      if (!reader_->ReadUInt16(&tcp->accumulated_number_of_lost_packets)) {
+        set_detailed_error(
+            "Unable to read accumulated number of lost packets.");
+        return false;
+      }
+      if (!reader_->ReadUInt16(&tcp->receive_window)) {
+        set_detailed_error("Unable to read receive window.");
+        return false;
+      }
+      break;
+    }
+    default:
+      set_detailed_error("Illegal congestion info type.");
+      DLOG(WARNING) << "Illegal congestion info type: "
+                    << fragment->congestion_info.type;
+      return RaiseError(QUIC_INVALID_FRAGMENT_DATA);
+  }
+
+  visitor_->OnAckFragment(*fragment);
+  return true;
+}
+
+bool QuicFramer::ProcessRstStreamFragment() {
+  QuicRstStreamFragment fragment;
+  if (!reader_->ReadUInt32(&fragment.stream_id)) {
+    set_detailed_error("Unable to read stream_id.");
+    return false;
+  }
+
+  if (!reader_->ReadUInt64(&fragment.offset)) {
+    set_detailed_error("Unable to read offset in rst fragment.");
+    return false;
+  }
+
+  uint32 details;
+  if (!reader_->ReadUInt32(&details)) {
+    set_detailed_error("Unable to read rst stream details.");
+    return false;
+  }
+  fragment.details = static_cast<QuicErrorCode>(details);
+
+  visitor_->OnRstStreamFragment(fragment);
+  return true;
+}
+
+bool QuicFramer::ProcessConnectionCloseFragment() {
+  QuicConnectionCloseFragment fragment;
+
+  uint32 details;
+  if (!reader_->ReadUInt32(&details)) {
+    set_detailed_error("Unable to read connection close details.");
+    return false;
+  }
+  fragment.details = static_cast<QuicErrorCode>(details);
+
+  if (!ProcessAckFragment(&fragment.ack_fragment)) {
+    DLOG(WARNING) << "Unable to process ack fragment.";
+    return false;
+  }
+
+  visitor_->OnConnectionCloseFragment(fragment);
+  return true;
+}
+
+void QuicFramer::WriteTransmissionTime(QuicTransmissionTime time,
+                                       QuicPacket* packet) {
+  QuicDataWriter::WriteUint64ToBuffer(
+      time, packet->mutable_data() + kTransmissionTimeOffset);
+}
+
+QuicEncryptedPacket* QuicFramer::EncryptPacket(const QuicPacket& packet) {
+  scoped_ptr<QuicData> out(encrypter_->Encrypt(packet.AssociatedData(),
+                                               packet.Plaintext()));
+  if (out.get() == NULL) {
+    RaiseError(QUIC_ENCRYPTION_FAILURE);
+    return NULL;
+  }
+  size_t len = kStartOfEncryptedData + out->length();
+  char* buffer = new char[len];
+  // TODO(rch): eliminate this buffer copy by passing in a buffer to Encrypt().
+  memcpy(buffer, packet.data(), kStartOfEncryptedData);
+  memcpy(buffer + kStartOfEncryptedData, out->data(), out->length());
+  return new QuicEncryptedPacket(buffer, len, true);
+}
+
+size_t QuicFramer::GetMaxPlaintextSize(size_t ciphertext_size) {
+  return encrypter_->GetMaxPlaintextSize(ciphertext_size);
+}
+
+bool QuicFramer::DecryptPayload(const QuicEncryptedPacket& packet) {
+  LOG(INFO) << "here!";
+  StringPiece encrypted;
+  if (!reader_->ReadStringPiece(&encrypted, reader_->BytesRemaining())) {
+    return false;
+  }
+  DCHECK(decrypter_.get() != NULL);
+  LOG(INFO) << "here!";
+  decrypted_.reset(decrypter_->Decrypt(packet.AssociatedData(), encrypted));
+  if  (decrypted_.get() == NULL) {
+    return false;
+  }
+
+  reader_.reset(new QuicDataReader(decrypted_->data(), decrypted_->length()));
+  return true;
+}
+
+size_t QuicFramer::ComputeFragmentPayloadLength(const QuicFragment& fragment) {
+  size_t len = 0;
+  switch (fragment.type) {
+    case STREAM_FRAGMENT:
+      len += 4;  // stream id

[jar (doing other things), 2012/10/14 23:04:38]

nit: IMO, much better would be mostly sizeof(named_member_) all through here.

[Ryan Hamilton, 2012/10/15 21:22:08]

This is not guaranteed to work because the in-memory format is not equivalent to
the wire format.  Added a todo.

+      len += 1;  // fin
+      len += 8;  // offset
+      len += 2;  // space for the 16 bit length
+      len += fragment.stream_fragment->data.size();
+      break;
+    case PDU_FRAGMENT:
+      DLOG(INFO) << "PDU_FRAGMENT not yet supported";
+      break;  // Need to support this eventually :>
+    case ACK_FRAGMENT: {
+      const QuicAckFragment& ack = *fragment.ack_fragment;
+      len += 6;  // largest received packet sequence number
+      len += 8;  // time delta
+      len += 1;  // num missing packets
+      len += 6 * ack.received_info.missing_packets.size();
+      len += 6;  // least packet sequence number awaiting an ack
+      len += 1;  // num non retransmitting packets
+      len += 6 * ack.sent_info.non_retransmiting.size();
+      len += 1;  // congestion control type
+      switch (ack.congestion_info.type) {
+        case kNone:
+          break;
+        case kInterArrival:
+          len += 6;
+          break;
+        case kFixRate:
+          len += 4;
+          break;
+        case kTCP:
+          len += 4;
+          break;
+        default:
+          set_detailed_error("Illegal feedback type.");
+          DLOG(INFO) << "Illegal feedback type: " << ack.congestion_info.type;
+          break;
+      }
+      break;
+    }
+    case RST_STREAM_FRAGMENT:
+      len += 4;  // stream id
+      len += 8;  // offset
+      len += 4;  // details
+      break;
+    case CONNECTION_CLOSE_FRAGMENT:
+      len += 4;  // details
+      len += ComputeFragmentPayloadLength(
+          QuicFragment(&fragment.connection_close_fragment->ack_fragment));
+      break;
+    default:
+      set_detailed_error("Illegal fragment type.");
+      DLOG(INFO) << "Illegal fragment type: " << fragment.type;
+      break;
+  }
+  return len;
+}
+
+bool QuicFramer::AppendStreamFragmentPayload(
+    const QuicStreamFragment& fragment,
+    QuicDataWriter* writer) {
+  if (!writer->WriteUInt32(fragment.stream_id)) {
+    return false;
+  }
+  if (!writer->WriteUInt8(fragment.fin)) {
+    return false;
+  }
+  if (!writer->WriteUInt64(fragment.offset)) {
+    return false;
+  }
+  if (!writer->WriteUInt16(fragment.data.size())) {
+    return false;
+  }
+  if (!writer->WriteBytes(fragment.data.data(),
+                           fragment.data.size())) {
+    return false;
+  }
+  return true;
+}
+
+bool QuicFramer::AppendAckFragmentPayload(
+    const QuicAckFragment& fragment,
+    QuicDataWriter* writer) {
+  if (!writer->WriteUInt48(fragment.received_info.largest_received)) {
+    return false;
+  }
+  if (!writer->WriteUInt64(fragment.received_info.time_received)) {
+    return false;
+  }
+
+  size_t num_unacked_packets = fragment.received_info.missing_packets.size();
+  if (!writer->WriteBytes(&num_unacked_packets, 1)) {
+    return false;
+  }
+
+  hash_set<QuicPacketSequenceNumber>::const_iterator it =
+      fragment.received_info.missing_packets.begin();
+  for (; it != fragment.received_info.missing_packets.end(); ++it) {
+    if (!writer->WriteUInt48(*it)) {
+      return false;
+    }
+  }
+
+  if (!writer->WriteUInt48(fragment.sent_info.least_unacked)) {
+    return false;
+  }
+
+  size_t num_non_retransmiting_packets =
+      fragment.sent_info.non_retransmiting.size();
+  if (!writer->WriteBytes(&num_non_retransmiting_packets, 1)) {
+    return false;
+  }
+
+  it = fragment.sent_info.non_retransmiting.begin();
+  while (it != fragment.sent_info.non_retransmiting.end()) {
+    if (!writer->WriteUInt48(*it)) {
+      return false;
+    }
+    ++it;
+  }
+
+  if (!writer->WriteBytes(&fragment.congestion_info.type, 1)) {
+    return false;
+  }
+
+  switch (fragment.congestion_info.type) {
+    case kNone:
+      break;
+    case kInterArrival: {
+      const CongestionFeedbackMessageInterArrival& inter_arrival =
+          fragment.congestion_info.inter_arrival;
+      if (!writer->WriteUInt16(
+              inter_arrival.accumulated_number_of_lost_packets)) {
+        return false;
+      }
+      if (!writer->WriteBytes(&inter_arrival.offset_time, 2)) {
+        return false;
+      }
+      if (!writer->WriteUInt16(inter_arrival.delta_time)) {
+        return false;
+      }
+      break;
+    }
+    case kFixRate: {
+      const CongestionFeedbackMessageFixRate& fix_rate =
+          fragment.congestion_info.fix_rate;
+      if (!writer->WriteUInt32(fix_rate.bitrate_in_bytes_per_second)) {
+        return false;
+      }
+      break;
+    }
+    case kTCP: {
+      const CongestionFeedbackMessageTCP& tcp = fragment.congestion_info.tcp;
+      if (!writer->WriteUInt16(tcp.accumulated_number_of_lost_packets)) {
+        return false;
+      }
+      if (!writer->WriteUInt16(tcp.receive_window)) {
+        return false;
+      }
+      break;
+    }
+    default:
+      return false;
+  }
+
+  return true;
+}
+
+bool QuicFramer::AppendRstStreamFragmentPayload(
+        const QuicRstStreamFragment& fragment,
+        QuicDataWriter* writer) {
+  if (!writer->WriteUInt32(fragment.stream_id)) {
+    return false;
+  }
+  if (!writer->WriteUInt64(fragment.offset)) {
+    return false;
+  }
+
+  uint32 details = static_cast<uint32>(fragment.details);
+  if (!writer->WriteUInt32(details)) {
+    return false;
+  }
+  return true;
+}
+
+bool QuicFramer::AppendConnectionCloseFragmentPayload(
+    const QuicConnectionCloseFragment& fragment,
+    QuicDataWriter* writer) {
+  uint32 details = static_cast<uint32>(fragment.details);
+  if (!writer->WriteUInt32(details)) {
+    return false;
+  }
+  AppendAckFragmentPayload(fragment.ack_fragment, writer);
+  return true;
+}
+
+bool QuicFramer::RaiseError(QuicErrorCode error) {
+  DLOG(INFO) << detailed_error_;
+  set_error(error);
+  visitor_->OnError(this);
+  reader_.reset(NULL);
+  return false;
+}
+
+}  // namespace net