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mvfst/quic/codec/QuicWriteCodec.cpp
Joseph Beshay 015c62e964 Refactor ACK writing for the different ACK types
Summary:
This replaces three separate functions for writing ACK, ACK_ECN, and ACK_RECEIVE_TIMESTAMPS with one function that can write all three.

Previously, we have two paths:
1. Default path which writes the base ACK frame and optionally adds the ECN counts if the frame type is ACK_ECN.
2. If ACK_RECEIVE_TIMESTAMPS are supported, another path would take the ART config and write that frame with the ART fields.
Path #2 does not support ECN marks.

This change consolidates ACK writing into a single path which takes ART config and frame type. It decides which fields to include based upon the type and config passed. This change does not add any new frame types but it prepares for one that can carry both ECN counts and ART fields.

Differential Revision: D68931147

fbshipit-source-id: 47b425b30f00b6c76574bc768d0ec249c60a0aa7
2025-02-13 17:48:18 -08:00

1054 lines
41 KiB
C++

/*
* Copyright (c) Meta Platforms, Inc. and affiliates.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*/
#include <quic/codec/QuicWriteCodec.h>
#include <algorithm>
#include <quic/QuicConstants.h>
#include <quic/QuicException.h>
#include <quic/codec/QuicInteger.h>
#include <cstdint>
#include <sstream>
namespace {
/**
* A helper function to check if there are enough space to write in the packet.
* Return: true if there is enough space, false otherwise
*/
bool packetSpaceCheck(uint64_t limit, size_t require) {
return (folly::to<uint64_t>(require) <= limit);
}
} // namespace
namespace quic {
Optional<uint64_t> writeStreamFrameHeader(
PacketBuilderInterface& builder,
StreamId id,
uint64_t offset,
uint64_t writeBufferLen,
uint64_t flowControlLen,
bool fin,
Optional<bool> skipLenHint,
OptionalIntegral<StreamGroupId> streamGroupId,
bool appendFrame) {
if (builder.remainingSpaceInPkt() == 0) {
return none;
}
if (writeBufferLen == 0 && !fin) {
throw QuicInternalException(
"No data or fin supplied when writing stream.",
LocalErrorCode::INTERNAL_ERROR);
}
StreamTypeField::Builder streamTypeBuilder;
if (streamGroupId) {
streamTypeBuilder.switchToStreamGroups();
}
QuicInteger idInt(id);
Optional<QuicInteger> groupIdInt;
if (streamGroupId) {
groupIdInt = QuicInteger(*streamGroupId);
}
// First account for the things that are non-optional: frame type, stream id
// and (optional) group id.
uint64_t headerSize = sizeof(uint8_t) + idInt.getSize();
if (groupIdInt) {
headerSize += groupIdInt->getSize();
}
if (builder.remainingSpaceInPkt() < headerSize) {
VLOG(4) << "No space in packet for stream header. stream=" << id
<< " remaining=" << builder.remainingSpaceInPkt();
return none;
}
QuicInteger offsetInt(offset);
if (offset != 0) {
streamTypeBuilder.setOffset();
headerSize += offsetInt.getSize();
}
// Next we have to deal with the data length. This is trickier. The length of
// data we are able to send depends on 3 things: how much we have in the
// buffer, how much flow control we have, and the remaining size in the
// packet. If the amount we want to send is >= the remaining packet size after
// the header so far we can omit the length field and consume the rest of the
// packet. If it is not then we need to use the minimal varint encoding
// possible to avoid sending not-full packets.
// Note: we don't bother with one potential optimization, which is writing
// a zero length fin-only stream frame and omitting the length field.
uint64_t dataLen = std::min(writeBufferLen, flowControlLen);
uint64_t dataLenLen = 0;
bool shouldSkipLengthField;
if (skipLenHint) {
shouldSkipLengthField = *skipLenHint;
} else {
// Check if we can fill the entire packet with the rest of this stream frame
shouldSkipLengthField =
dataLen > 0 && dataLen >= builder.remainingSpaceInPkt() - headerSize;
}
// At most we can write the minimal between data length and what the packet
// builder allows us to write.
dataLen = std::min(dataLen, builder.remainingSpaceInPkt() - headerSize);
if (!shouldSkipLengthField) {
if (dataLen <= kOneByteLimit - 1) {
dataLenLen = 1;
} else if (dataLen <= kTwoByteLimit - 2) {
dataLenLen = 2;
} else if (dataLen <= kFourByteLimit - 4) {
dataLenLen = 4;
} else if (dataLen <= kEightByteLimit - 8) {
dataLenLen = 8;
} else {
// This should never really happen as dataLen is bounded by the remaining
// space in the packet which should be << kEightByteLimit.
throw QuicInternalException(
"Stream frame length too large.", LocalErrorCode::INTERNAL_ERROR);
}
}
if (dataLenLen > 0) {
if (dataLen != 0 &&
headerSize + dataLenLen >= builder.remainingSpaceInPkt()) {
VLOG(4) << "No space in packet for stream header. stream=" << id
<< " remaining=" << builder.remainingSpaceInPkt();
return none;
}
// We have to encode the actual data length in the header.
headerSize += dataLenLen;
if (builder.remainingSpaceInPkt() < dataLen + headerSize) {
dataLen = builder.remainingSpaceInPkt() - headerSize;
}
}
bool shouldSetFin = fin && dataLen == writeBufferLen;
if (dataLen == 0 && !shouldSetFin) {
// This would be an empty non-fin stream frame.
return none;
}
if (builder.remainingSpaceInPkt() < headerSize) {
VLOG(4) << "No space in packet for stream header. stream=" << id
<< " remaining=" << builder.remainingSpaceInPkt();
return none;
}
// Done with the accounting, set the bits and write the actual frame header.
if (dataLenLen > 0) {
streamTypeBuilder.setLength();
}
if (shouldSetFin) {
streamTypeBuilder.setFin();
}
auto streamType = streamTypeBuilder.build();
builder.writeBE(streamType.fieldValue());
builder.write(idInt);
if (groupIdInt) {
builder.write(*groupIdInt);
}
if (offset != 0) {
builder.write(offsetInt);
}
if (dataLenLen > 0) {
builder.write(QuicInteger(dataLen));
}
if (appendFrame) {
builder.appendFrame(WriteStreamFrame(
id,
offset,
dataLen,
streamType.hasFin(),
false /* fromBufMetaIn */,
streamGroupId));
} else {
builder.markNonEmpty();
}
return folly::make_optional(dataLen);
}
void writeStreamFrameData(
PacketBuilderInterface& builder,
const ChainedByteRangeHead& writeBuffer,
uint64_t dataLen) {
if (dataLen > 0) {
builder.insert(writeBuffer, dataLen);
}
}
Optional<WriteCryptoFrame> writeCryptoFrame(
uint64_t offsetIn,
const ChainedByteRangeHead& data,
PacketBuilderInterface& builder) {
uint64_t spaceLeftInPkt = builder.remainingSpaceInPkt();
QuicInteger intFrameType(static_cast<uint8_t>(FrameType::CRYPTO_FRAME));
QuicInteger offsetInteger(offsetIn);
size_t lengthBytes = 2;
size_t cryptoFrameHeaderSize =
intFrameType.getSize() + offsetInteger.getSize() + lengthBytes;
if (spaceLeftInPkt <= cryptoFrameHeaderSize) {
VLOG(3) << "No space left in packet to write cryptoFrame header of size: "
<< cryptoFrameHeaderSize << ", space left=" << spaceLeftInPkt;
return none;
}
size_t spaceRemaining = spaceLeftInPkt - cryptoFrameHeaderSize;
size_t dataLength = data.chainLength();
size_t writableData = std::min(dataLength, spaceRemaining);
QuicInteger lengthVarInt(writableData);
if (lengthVarInt.getSize() > lengthBytes) {
throw QuicInternalException(
std::string("Length bytes representation"),
LocalErrorCode::CODEC_ERROR);
}
builder.write(intFrameType);
builder.write(offsetInteger);
builder.write(lengthVarInt);
builder.insert(data, writableData);
builder.appendFrame(WriteCryptoFrame(offsetIn, lengthVarInt.getValue()));
return WriteCryptoFrame(offsetIn, lengthVarInt.getValue());
}
/*
* This function will fill the parameter ack frame with ack blocks from the
* parameter ackBlocks until it runs out of space (bytesLimit). The largest
* ack block should have been inserted by the caller.
*/
static size_t fillFrameWithAckBlocks(
const AckBlocks& ackBlocks,
WriteAckFrame& ackFrame,
uint64_t bytesLimit) {
PacketNum currentSeqNum = ackBlocks.crbegin()->start;
// starts off with 0 which is what we assumed the initial ack block to be for
// the largest acked.
size_t numAdditionalAckBlocks = 0;
size_t previousNumAckBlocks = 0;
// Skip the largest, as it has already been emplaced.
for (auto blockItr = ackBlocks.crbegin() + 1; blockItr != ackBlocks.crend();
++blockItr) {
const auto& currBlock = *blockItr;
// These must be true because of the properties of the interval set.
CHECK_GE(currentSeqNum, currBlock.end + 2);
PacketNum gap = currentSeqNum - currBlock.end - 2;
PacketNum currBlockLen = currBlock.end - currBlock.start;
// TODO this is still extra work, as we end up duplicating these
// calculations in the caller, we could store the results so they
// can be reused by the caller when writing the frame.
size_t gapSize = getQuicIntegerSizeThrows(gap);
size_t currBlockLenSize = getQuicIntegerSizeThrows(currBlockLen);
size_t numAdditionalAckBlocksSize =
getQuicIntegerSizeThrows(numAdditionalAckBlocks + 1);
size_t previousNumAckBlocksSize =
getQuicIntegerSizeThrows(previousNumAckBlocks);
size_t additionalSize = gapSize + currBlockLenSize +
(numAdditionalAckBlocksSize - previousNumAckBlocksSize);
if (bytesLimit < additionalSize) {
break;
}
numAdditionalAckBlocks++;
bytesLimit -= additionalSize;
previousNumAckBlocks = numAdditionalAckBlocks;
currentSeqNum = currBlock.start;
ackFrame.ackBlocks.emplace_back(currBlock.start, currBlock.end);
}
return numAdditionalAckBlocks;
}
size_t computeSizeUsedByRecvdTimestamps(WriteAckFrame& ackFrame) {
size_t usedSize = 0;
for (auto& recvdPacketsTimestampRanges :
ackFrame.recvdPacketsTimestampRanges) {
usedSize += getQuicIntegerSizeThrows(recvdPacketsTimestampRanges.gap);
usedSize += getQuicIntegerSizeThrows(
recvdPacketsTimestampRanges.timestamp_delta_count);
for (auto& timestampDelta : recvdPacketsTimestampRanges.deltas) {
usedSize += getQuicIntegerSizeThrows(timestampDelta);
}
}
return usedSize;
}
static size_t fillFrameWithPacketReceiveTimestamps(
const quic::WriteAckFrameMetaData& ackFrameMetaData,
WriteAckFrame& ackFrame,
uint64_t largestAckedPacketNum,
uint64_t spaceLeft,
uint64_t receiveTimestampsExponent,
uint64_t maxRecvTimestampsToSend) {
if (ackFrameMetaData.ackState.recvdPacketInfos.size() == 0) {
return 0;
}
auto recvdPacketInfos = ackFrameMetaData.ackState.recvdPacketInfos;
// Insert all received packet timestamps into an interval set, to identify
// contiguous ranges
uint64_t pktsAdded = 0;
IntervalSet<PacketNum> receivedPktNumsIntervalSet;
for (auto& recvdPkt : recvdPacketInfos) {
// Add up to the peer requested max ack receive timestamps;
if (pktsAdded == maxRecvTimestampsToSend) {
break;
}
receivedPktNumsIntervalSet.insert(recvdPkt.pktNum);
pktsAdded++;
}
auto prevPktNum = largestAckedPacketNum;
auto timestampIt = recvdPacketInfos.crbegin();
size_t cumUsedSpace = 0;
// We start from the latest timestamp intervals
bool outOfSpace = false;
for (auto timestampIntervalsIt = receivedPktNumsIntervalSet.crbegin();
timestampIntervalsIt != receivedPktNumsIntervalSet.crend();
timestampIntervalsIt++) {
RecvdPacketsTimestampsRange nextTimestampRange;
size_t nextTimestampRangeUsedSpace = 0;
// Compute pktNum gap for each time-stamp range
if (ackFrame.recvdPacketsTimestampRanges.empty()) {
nextTimestampRange.gap = prevPktNum - timestampIntervalsIt->end;
} else {
nextTimestampRange.gap = prevPktNum - 2 - timestampIntervalsIt->end;
}
// Initialize spaced used by the next candidate time-stamp range
nextTimestampRangeUsedSpace +=
getQuicIntegerSizeThrows(nextTimestampRange.gap);
while (timestampIt != recvdPacketInfos.crend() &&
timestampIt->pktNum >= timestampIntervalsIt->start &&
timestampIt->pktNum <= timestampIntervalsIt->end) {
std::chrono::microseconds deltaDuration;
if (timestampIt == recvdPacketInfos.crbegin()) {
deltaDuration =
(timestampIt->timings.receiveTimePoint > ackFrameMetaData.connTime)
? std::chrono::duration_cast<std::chrono::microseconds>(
timestampIt->timings.receiveTimePoint -
ackFrameMetaData.connTime)
: 0us;
} else {
deltaDuration = std::chrono::duration_cast<std::chrono::microseconds>(
(timestampIt - 1)->timings.receiveTimePoint -
timestampIt->timings.receiveTimePoint);
}
auto delta = deltaDuration.count() >> receiveTimestampsExponent;
// Check if adding a new time-stamp delta from the current time-stamp
// interval Will allow us to run out of space. Since adding a new delta
// impacts cumulative counts of deltas these are not already incorporated
// into nextTimestampRangeUsedSpace.
if (spaceLeft <
(cumUsedSpace + nextTimestampRangeUsedSpace +
getQuicIntegerSizeThrows(delta) +
getQuicIntegerSizeThrows(nextTimestampRange.deltas.size() + 1) +
getQuicIntegerSizeThrows(
ackFrame.recvdPacketsTimestampRanges.size() + 1))) {
outOfSpace = true;
break;
}
nextTimestampRange.deltas.push_back(delta);
nextTimestampRangeUsedSpace += getQuicIntegerSizeThrows(delta);
timestampIt++;
}
if (nextTimestampRange.deltas.size() > 0) {
nextTimestampRange.timestamp_delta_count =
nextTimestampRange.deltas.size();
cumUsedSpace += nextTimestampRangeUsedSpace +
getQuicIntegerSizeThrows(nextTimestampRange.deltas.size());
ackFrame.recvdPacketsTimestampRanges.push_back(nextTimestampRange);
prevPktNum = timestampIntervalsIt->start;
DCHECK(cumUsedSpace <= spaceLeft);
}
if (outOfSpace) {
break;
}
}
DCHECK(cumUsedSpace == computeSizeUsedByRecvdTimestamps(ackFrame));
return ackFrame.recvdPacketsTimestampRanges.size();
}
static Optional<WriteAckFrame> maybeWriteAckBaseFields(
const quic::WriteAckFrameMetaData& ackFrameMetaData,
PacketBuilderInterface& builder,
FrameType frameType,
uint64_t maxSpaceToUse) {
auto spaceLeft = maxSpaceToUse;
const WriteAckFrameState& ackState = ackFrameMetaData.ackState;
// The last block must be the largest block.
auto largestAckedPacket = ackState.acks.back().end;
// ackBlocks are already an interval set so each value is naturally
// non-overlapping.
auto firstAckBlockLength = largestAckedPacket - ackState.acks.back().start;
// We could technically split the range if the size of the representation of
// the integer is too large, but that gets super tricky and is of dubious
// value.
QuicInteger largestAckedPacketInt(largestAckedPacket);
QuicInteger firstAckBlockLengthInt(firstAckBlockLength);
// Convert ackDelay to unsigned value explicitly before right shifting to
// avoid issues with right shifting signed values.
uint64_t encodedAckDelay = ackFrameMetaData.ackDelay.count();
encodedAckDelay = encodedAckDelay >> ackFrameMetaData.ackDelayExponent;
QuicInteger ackDelayInt(encodedAckDelay);
QuicInteger minAdditionalAckBlockCount(0);
// Required fields are Type, LargestAcked, AckDelay, AckBlockCount,
// firstAckBlockLength
QuicInteger encodedintFrameType(static_cast<uint8_t>(frameType));
uint64_t headerSize = encodedintFrameType.getSize() +
largestAckedPacketInt.getSize() + ackDelayInt.getSize() +
minAdditionalAckBlockCount.getSize() + firstAckBlockLengthInt.getSize();
if (spaceLeft < headerSize) {
return none;
}
WriteAckFrame ackFrame;
ackFrame.frameType = frameType;
// Reserve the number of ack blocks we could fit in the remaining space.
ackFrame.ackBlocks.reserve(spaceLeft / 4);
// Account for the header size
spaceLeft -= headerSize;
ackFrame.ackBlocks.push_back(ackState.acks.back());
auto numAdditionalAckBlocks =
fillFrameWithAckBlocks(ackState.acks, ackFrame, spaceLeft);
QuicInteger numAdditionalAckBlocksInt(numAdditionalAckBlocks);
builder.write(encodedintFrameType);
builder.write(largestAckedPacketInt);
builder.write(ackDelayInt);
builder.write(numAdditionalAckBlocksInt);
builder.write(firstAckBlockLengthInt);
PacketNum currentSeqNum = ackState.acks.back().start;
for (auto it = ackFrame.ackBlocks.cbegin() + 1;
it != ackFrame.ackBlocks.cend();
++it) {
CHECK_GE(currentSeqNum, it->end + 2);
PacketNum gap = currentSeqNum - it->end - 2;
PacketNum currBlockLen = it->end - it->start;
QuicInteger gapInt(gap);
QuicInteger currentBlockLenInt(currBlockLen);
builder.write(gapInt);
builder.write(currentBlockLenInt);
currentSeqNum = it->start;
}
ackFrame.ackDelay = ackFrameMetaData.ackDelay;
return ackFrame;
}
static uint64_t computeEcnRequiredSpace(
const quic::WriteAckFrameMetaData& ackFrameMetaData) {
QuicInteger ecnECT0Count(ackFrameMetaData.ackState.ecnECT0CountReceived);
QuicInteger ecnECT1Count(ackFrameMetaData.ackState.ecnECT1CountReceived);
QuicInteger ecnCECount(ackFrameMetaData.ackState.ecnCECountReceived);
return ecnECT0Count.getSize() + ecnECT1Count.getSize() + ecnCECount.getSize();
}
static uint64_t computeReceiveTimestampsMinimumSpace(
const quic::WriteAckFrameMetaData& ackFrameMetaData) {
// Compute minimum size requirements for 3 fields that must be sent
// in every ACK_RECEIVE_TIMESTAMPS frame
const WriteAckFrameState& ackState = ackFrameMetaData.ackState;
uint64_t countTimestampRanges = 0;
uint64_t maybeLastPktNum = 0;
std::chrono::microseconds maybeLastPktTsDelta = 0us;
if (ackState.lastRecvdPacketInfo) {
maybeLastPktNum = ackState.lastRecvdPacketInfo.value().pktNum;
maybeLastPktTsDelta =
(ackState.lastRecvdPacketInfo.value().timings.receiveTimePoint >
ackFrameMetaData.connTime
? std::chrono::duration_cast<std::chrono::microseconds>(
ackState.lastRecvdPacketInfo.value()
.timings.receiveTimePoint -
ackFrameMetaData.connTime)
: 0us);
}
return getQuicIntegerSize(countTimestampRanges).value_or(0) +
getQuicIntegerSize(maybeLastPktNum).value_or(0) +
getQuicIntegerSize(maybeLastPktTsDelta.count()).value_or(0);
}
static void writeECNFieldsToAck(
const quic::WriteAckFrameMetaData& ackFrameMetaData,
WriteAckFrame& ackFrame,
PacketBuilderInterface& builder) {
ackFrame.ecnECT0Count = ackFrameMetaData.ackState.ecnECT0CountReceived;
ackFrame.ecnECT1Count = ackFrameMetaData.ackState.ecnECT1CountReceived;
ackFrame.ecnCECount = ackFrameMetaData.ackState.ecnCECountReceived;
QuicInteger ecnECT0Count(ackFrameMetaData.ackState.ecnECT0CountReceived);
QuicInteger ecnECT1Count(ackFrameMetaData.ackState.ecnECT1CountReceived);
QuicInteger ecnCECount(ackFrameMetaData.ackState.ecnCECountReceived);
builder.write(ecnECT0Count);
builder.write(ecnECT1Count);
builder.write(ecnCECount);
}
namespace {
struct AckReceiveTimesStampsWritten {
size_t TimestampRangesWritten{0};
size_t TimestampWritten{0};
};
} // namespace
AckReceiveTimesStampsWritten writeReceiveTimestampFieldsToAck(
const quic::WriteAckFrameMetaData& ackFrameMetaData,
WriteAckFrame& ackFrame,
PacketBuilderInterface& builder,
const AckReceiveTimestampsConfig& recvTimestampsConfig,
uint64_t maxRecvTimestampsToSend) {
const WriteAckFrameState& ackState = ackFrameMetaData.ackState;
uint64_t spaceLeft = builder.remainingSpaceInPkt();
uint64_t lastPktNum = 0;
std::chrono::microseconds lastPktTsDelta = 0us;
if (ackState.lastRecvdPacketInfo) {
lastPktNum = ackState.lastRecvdPacketInfo.value().pktNum;
lastPktTsDelta =
(ackState.lastRecvdPacketInfo.value().timings.receiveTimePoint >
ackFrameMetaData.connTime
? std::chrono::duration_cast<std::chrono::microseconds>(
ackState.lastRecvdPacketInfo.value()
.timings.receiveTimePoint -
ackFrameMetaData.connTime)
: 0us);
}
QuicInteger lastRecvdPacketNumInt(lastPktNum);
builder.write(lastRecvdPacketNumInt);
ackFrame.maybeLatestRecvdPacketNum = lastRecvdPacketNumInt.getValue();
QuicInteger lastRecvdPacketTimeInt(lastPktTsDelta.count());
builder.write(lastRecvdPacketTimeInt);
ackFrame.maybeLatestRecvdPacketTime =
std::chrono::microseconds(lastRecvdPacketTimeInt.getValue());
size_t countTimestampRanges = 0;
size_t countTimestamps = 0;
spaceLeft = builder.remainingSpaceInPkt();
if (spaceLeft > 0) {
auto largestAckedPacket = ackState.acks.back().end;
uint64_t receiveTimestampsExponentToUse =
recvTimestampsConfig.receiveTimestampsExponent;
countTimestampRanges = fillFrameWithPacketReceiveTimestamps(
ackFrameMetaData,
ackFrame,
largestAckedPacket,
spaceLeft,
receiveTimestampsExponentToUse,
maxRecvTimestampsToSend);
if (countTimestampRanges > 0) {
QuicInteger timeStampRangeCountInt(
ackFrame.recvdPacketsTimestampRanges.size());
builder.write(timeStampRangeCountInt);
for (auto& recvdPacketsTimestampRanges :
ackFrame.recvdPacketsTimestampRanges) {
QuicInteger gapInt(recvdPacketsTimestampRanges.gap);
QuicInteger timestampDeltaCountInt(
recvdPacketsTimestampRanges.timestamp_delta_count);
builder.write(gapInt);
builder.write(timestampDeltaCountInt);
for (auto& timestamp : recvdPacketsTimestampRanges.deltas) {
QuicInteger deltaInt(timestamp);
builder.write(deltaInt);
countTimestamps++;
}
}
} else {
QuicInteger timeStampRangeCountInt(0);
builder.write(timeStampRangeCountInt);
}
}
return AckReceiveTimesStampsWritten{countTimestampRanges, countTimestamps};
}
Optional<WriteAckFrameResult> writeAckFrame(
const quic::WriteAckFrameMetaData& ackFrameMetaData,
PacketBuilderInterface& builder,
FrameType frameType,
const AckReceiveTimestampsConfig& recvTimestampsConfig,
uint64_t maxRecvTimestampsToSend) {
if (ackFrameMetaData.ackState.acks.empty()) {
return none;
}
uint64_t beginningSpace = builder.remainingSpaceInPkt();
uint64_t spaceLeft = beginningSpace;
// Reserve space for ECN counts if enabled
if (frameType == FrameType::ACK_ECN) {
auto ecnRequiredSpace = computeEcnRequiredSpace(ackFrameMetaData);
if (spaceLeft < ecnRequiredSpace) {
return none;
}
spaceLeft -= ecnRequiredSpace;
}
// Reserve space for receive timestamps if enabled
if (frameType == FrameType::ACK_RECEIVE_TIMESTAMPS) {
auto receiveTimestampsMinimumSpace =
computeReceiveTimestampsMinimumSpace(ackFrameMetaData);
if (spaceLeft < receiveTimestampsMinimumSpace) {
return none;
}
spaceLeft -= receiveTimestampsMinimumSpace;
}
// Start writing fields to the builder
// 1. Write the base ack fields (ACK packet type)
auto maybeAckFrame =
maybeWriteAckBaseFields(ackFrameMetaData, builder, frameType, spaceLeft);
if (!maybeAckFrame.has_value()) {
return none;
}
auto& ackFrame = maybeAckFrame.value();
// 2. Write ECN fields if enabled
if (frameType == FrameType::ACK_ECN) {
writeECNFieldsToAck(ackFrameMetaData, ackFrame, builder);
}
// 3. Write receive timestamp fields if enabled
AckReceiveTimesStampsWritten receiveTimestampsWritten;
if (frameType == FrameType::ACK_RECEIVE_TIMESTAMPS) {
receiveTimestampsWritten = writeReceiveTimestampFieldsToAck(
ackFrameMetaData,
ackFrame,
builder,
recvTimestampsConfig,
maxRecvTimestampsToSend);
}
// Everything written
auto ackFrameWriteResult = WriteAckFrameResult(
beginningSpace - builder.remainingSpaceInPkt(),
ackFrame,
ackFrame.ackBlocks.size(),
receiveTimestampsWritten.TimestampRangesWritten,
receiveTimestampsWritten.TimestampWritten);
builder.appendFrame(std::move(ackFrame));
return ackFrameWriteResult;
}
size_t writeSimpleFrame(
QuicSimpleFrame&& frame,
PacketBuilderInterface& builder) {
using FrameTypeType = std::underlying_type<FrameType>::type;
uint64_t spaceLeft = builder.remainingSpaceInPkt();
switch (frame.type()) {
case QuicSimpleFrame::Type::StopSendingFrame: {
const StopSendingFrame& stopSendingFrame = *frame.asStopSendingFrame();
QuicInteger intFrameType(static_cast<uint8_t>(FrameType::STOP_SENDING));
QuicInteger streamId(stopSendingFrame.streamId);
QuicInteger errorCode(static_cast<uint64_t>(stopSendingFrame.errorCode));
size_t errorSize = errorCode.getSize();
auto stopSendingFrameSize =
intFrameType.getSize() + streamId.getSize() + errorSize;
if (packetSpaceCheck(spaceLeft, stopSendingFrameSize)) {
builder.write(intFrameType);
builder.write(streamId);
builder.write(errorCode);
builder.appendFrame(QuicSimpleFrame(std::move(stopSendingFrame)));
return stopSendingFrameSize;
}
// no space left in packet
return size_t(0);
}
case QuicSimpleFrame::Type::PathChallengeFrame: {
const PathChallengeFrame& pathChallengeFrame =
*frame.asPathChallengeFrame();
QuicInteger frameType(static_cast<uint8_t>(FrameType::PATH_CHALLENGE));
auto pathChallengeFrameSize =
frameType.getSize() + sizeof(pathChallengeFrame.pathData);
if (packetSpaceCheck(spaceLeft, pathChallengeFrameSize)) {
builder.write(frameType);
builder.writeBE(pathChallengeFrame.pathData);
builder.appendFrame(QuicSimpleFrame(std::move(pathChallengeFrame)));
return pathChallengeFrameSize;
}
// no space left in packet
return size_t(0);
}
case QuicSimpleFrame::Type::PathResponseFrame: {
const PathResponseFrame& pathResponseFrame = *frame.asPathResponseFrame();
QuicInteger frameType(static_cast<uint8_t>(FrameType::PATH_RESPONSE));
auto pathResponseFrameSize =
frameType.getSize() + sizeof(pathResponseFrame.pathData);
if (packetSpaceCheck(spaceLeft, pathResponseFrameSize)) {
builder.write(frameType);
builder.writeBE(pathResponseFrame.pathData);
builder.appendFrame(QuicSimpleFrame(std::move(pathResponseFrame)));
return pathResponseFrameSize;
}
// no space left in packet
return size_t(0);
}
case QuicSimpleFrame::Type::NewConnectionIdFrame: {
const NewConnectionIdFrame& newConnectionIdFrame =
*frame.asNewConnectionIdFrame();
QuicInteger frameType(static_cast<uint8_t>(FrameType::NEW_CONNECTION_ID));
QuicInteger sequenceNumber(newConnectionIdFrame.sequenceNumber);
QuicInteger retirePriorTo(newConnectionIdFrame.retirePriorTo);
// Include an 8-bit unsigned integer containing the length of the connId
auto newConnectionIdFrameSize = frameType.getSize() +
sequenceNumber.getSize() + retirePriorTo.getSize() + sizeof(uint8_t) +
newConnectionIdFrame.connectionId.size() +
newConnectionIdFrame.token.size();
if (packetSpaceCheck(spaceLeft, newConnectionIdFrameSize)) {
builder.write(frameType);
builder.write(sequenceNumber);
builder.write(retirePriorTo);
builder.writeBE(newConnectionIdFrame.connectionId.size());
builder.push(
newConnectionIdFrame.connectionId.data(),
newConnectionIdFrame.connectionId.size());
builder.push(
newConnectionIdFrame.token.data(),
newConnectionIdFrame.token.size());
builder.appendFrame(QuicSimpleFrame(std::move(newConnectionIdFrame)));
return newConnectionIdFrameSize;
}
// no space left in packet
return size_t(0);
}
case QuicSimpleFrame::Type::MaxStreamsFrame: {
const MaxStreamsFrame& maxStreamsFrame = *frame.asMaxStreamsFrame();
auto frameType = maxStreamsFrame.isForBidirectionalStream()
? FrameType::MAX_STREAMS_BIDI
: FrameType::MAX_STREAMS_UNI;
QuicInteger intFrameType(static_cast<FrameTypeType>(frameType));
QuicInteger streamCount(maxStreamsFrame.maxStreams);
auto maxStreamsFrameSize = intFrameType.getSize() + streamCount.getSize();
if (packetSpaceCheck(spaceLeft, maxStreamsFrameSize)) {
builder.write(intFrameType);
builder.write(streamCount);
builder.appendFrame(QuicSimpleFrame(maxStreamsFrame));
return maxStreamsFrameSize;
}
return size_t(0);
}
case QuicSimpleFrame::Type::RetireConnectionIdFrame: {
const RetireConnectionIdFrame& retireConnectionIdFrame =
*frame.asRetireConnectionIdFrame();
QuicInteger frameType(
static_cast<uint8_t>(FrameType::RETIRE_CONNECTION_ID));
QuicInteger sequence(retireConnectionIdFrame.sequenceNumber);
auto retireConnectionIdFrameSize =
frameType.getSize() + sequence.getSize();
if (packetSpaceCheck(spaceLeft, retireConnectionIdFrameSize)) {
builder.write(frameType);
builder.write(sequence);
builder.appendFrame(QuicSimpleFrame(retireConnectionIdFrame));
return retireConnectionIdFrameSize;
}
// no space left in packet
return size_t(0);
}
case QuicSimpleFrame::Type::HandshakeDoneFrame: {
const HandshakeDoneFrame& handshakeDoneFrame =
*frame.asHandshakeDoneFrame();
CHECK(builder.getPacketHeader().asShort());
QuicInteger intFrameType(static_cast<uint8_t>(FrameType::HANDSHAKE_DONE));
if (packetSpaceCheck(spaceLeft, intFrameType.getSize())) {
builder.write(intFrameType);
builder.appendFrame(QuicSimpleFrame(handshakeDoneFrame));
return intFrameType.getSize();
}
// no space left in packet
return size_t(0);
}
case QuicSimpleFrame::Type::KnobFrame: {
const KnobFrame& knobFrame = *frame.asKnobFrame();
QuicInteger intFrameType(static_cast<uint64_t>(FrameType::KNOB));
QuicInteger intKnobSpace(knobFrame.knobSpace);
QuicInteger intKnobId(knobFrame.id);
QuicInteger intKnobLen(knobFrame.len);
size_t knobFrameLen = intFrameType.getSize() + intKnobSpace.getSize() +
intKnobId.getSize() + intKnobLen.getSize() + intKnobLen.getValue();
if (packetSpaceCheck(spaceLeft, knobFrameLen)) {
builder.write(intFrameType);
builder.write(intKnobSpace);
builder.write(intKnobId);
builder.write(intKnobLen);
builder.insert(knobFrame.blob->clone());
builder.appendFrame(QuicSimpleFrame(knobFrame));
return knobFrameLen;
}
// no space left in packet
return size_t(0);
}
case QuicSimpleFrame::Type::AckFrequencyFrame: {
const auto ackFrequencyFrame = frame.asAckFrequencyFrame();
QuicInteger intFrameType(static_cast<uint64_t>(FrameType::ACK_FREQUENCY));
QuicInteger intSequenceNumber(ackFrequencyFrame->sequenceNumber);
QuicInteger intPacketTolerance(ackFrequencyFrame->packetTolerance);
QuicInteger intUpdateMaxAckDelay(ackFrequencyFrame->updateMaxAckDelay);
QuicInteger intReorderThreshold(ackFrequencyFrame->reorderThreshold);
size_t ackFrequencyFrameLen = intFrameType.getSize() +
intSequenceNumber.getSize() + intPacketTolerance.getSize() +
intUpdateMaxAckDelay.getSize() + intReorderThreshold.getSize();
if (packetSpaceCheck(spaceLeft, ackFrequencyFrameLen)) {
builder.write(intFrameType);
builder.write(intSequenceNumber);
builder.write(intPacketTolerance);
builder.write(intUpdateMaxAckDelay);
builder.write(intReorderThreshold);
builder.appendFrame(QuicSimpleFrame(*ackFrequencyFrame));
return ackFrequencyFrameLen;
}
// no space left in packet
return size_t(0);
}
case QuicSimpleFrame::Type::NewTokenFrame: {
const auto newTokenFrame = frame.asNewTokenFrame();
QuicInteger intFrameType(static_cast<uint8_t>(FrameType::NEW_TOKEN));
auto& token = newTokenFrame->token;
QuicInteger tokenLength(token->computeChainDataLength());
auto newTokenFrameLength = intFrameType.getSize() +
/*encoding token length*/ tokenLength.getSize() +
tokenLength.getValue();
if (packetSpaceCheck(spaceLeft, newTokenFrameLength)) {
builder.write(intFrameType);
builder.write(tokenLength);
builder.insert(token->clone());
builder.appendFrame(QuicSimpleFrame(*newTokenFrame));
return newTokenFrameLength;
}
// no space left in packet
return size_t(0);
}
}
folly::assume_unreachable();
}
size_t writeFrame(QuicWriteFrame&& frame, PacketBuilderInterface& builder) {
using FrameTypeType = std::underlying_type<FrameType>::type;
uint64_t spaceLeft = builder.remainingSpaceInPkt();
switch (frame.type()) {
case QuicWriteFrame::Type::PaddingFrame: {
QuicInteger intFrameType(static_cast<uint8_t>(FrameType::PADDING));
if (packetSpaceCheck(spaceLeft, intFrameType.getSize())) {
builder.write(intFrameType);
builder.appendPaddingFrame();
return intFrameType.getSize();
}
return size_t(0);
}
case QuicWriteFrame::Type::RstStreamFrame: {
RstStreamFrame& rstStreamFrame = *frame.asRstStreamFrame();
QuicInteger intFrameType(static_cast<uint8_t>(
rstStreamFrame.reliableSize ? FrameType::RST_STREAM_AT
: FrameType::RST_STREAM));
QuicInteger streamId(rstStreamFrame.streamId);
QuicInteger finalSize(rstStreamFrame.finalSize);
QuicInteger errorCode(static_cast<uint64_t>(rstStreamFrame.errorCode));
folly::Optional<QuicInteger> maybeReliableSize = folly::none;
size_t errorSize = errorCode.getSize();
auto rstStreamFrameSize = intFrameType.getSize() + errorSize +
streamId.getSize() + finalSize.getSize();
if (rstStreamFrame.reliableSize) {
maybeReliableSize = QuicInteger(*rstStreamFrame.reliableSize);
rstStreamFrameSize += maybeReliableSize->getSize();
}
if (packetSpaceCheck(spaceLeft, rstStreamFrameSize)) {
builder.write(intFrameType);
builder.write(streamId);
builder.write(errorCode);
builder.write(finalSize);
if (maybeReliableSize) {
builder.write(*maybeReliableSize);
}
builder.appendFrame(std::move(rstStreamFrame));
return rstStreamFrameSize;
}
// no space left in packet
return size_t(0);
}
case QuicWriteFrame::Type::MaxDataFrame: {
MaxDataFrame& maxDataFrame = *frame.asMaxDataFrame();
QuicInteger intFrameType(static_cast<uint8_t>(FrameType::MAX_DATA));
QuicInteger maximumData(maxDataFrame.maximumData);
auto frameSize = intFrameType.getSize() + maximumData.getSize();
if (packetSpaceCheck(spaceLeft, frameSize)) {
builder.write(intFrameType);
builder.write(maximumData);
builder.appendFrame(std::move(maxDataFrame));
return frameSize;
}
// no space left in packet
return size_t(0);
}
case QuicWriteFrame::Type::MaxStreamDataFrame: {
MaxStreamDataFrame& maxStreamDataFrame = *frame.asMaxStreamDataFrame();
QuicInteger intFrameType(
static_cast<uint8_t>(FrameType::MAX_STREAM_DATA));
QuicInteger streamId(maxStreamDataFrame.streamId);
QuicInteger maximumData(maxStreamDataFrame.maximumData);
auto maxStreamDataFrameSize =
intFrameType.getSize() + streamId.getSize() + maximumData.getSize();
if (packetSpaceCheck(spaceLeft, maxStreamDataFrameSize)) {
builder.write(intFrameType);
builder.write(streamId);
builder.write(maximumData);
builder.appendFrame(std::move(maxStreamDataFrame));
return maxStreamDataFrameSize;
}
// no space left in packet
return size_t(0);
}
case QuicWriteFrame::Type::DataBlockedFrame: {
DataBlockedFrame& blockedFrame = *frame.asDataBlockedFrame();
QuicInteger intFrameType(static_cast<uint8_t>(FrameType::DATA_BLOCKED));
QuicInteger dataLimit(blockedFrame.dataLimit);
auto blockedFrameSize = intFrameType.getSize() + dataLimit.getSize();
if (packetSpaceCheck(spaceLeft, blockedFrameSize)) {
builder.write(intFrameType);
builder.write(dataLimit);
builder.appendFrame(std::move(blockedFrame));
return blockedFrameSize;
}
// no space left in packet
return size_t(0);
}
case QuicWriteFrame::Type::StreamDataBlockedFrame: {
StreamDataBlockedFrame& streamBlockedFrame =
*frame.asStreamDataBlockedFrame();
QuicInteger intFrameType(
static_cast<uint8_t>(FrameType::STREAM_DATA_BLOCKED));
QuicInteger streamId(streamBlockedFrame.streamId);
QuicInteger dataLimit(streamBlockedFrame.dataLimit);
auto blockedFrameSize =
intFrameType.getSize() + streamId.getSize() + dataLimit.getSize();
if (packetSpaceCheck(spaceLeft, blockedFrameSize)) {
builder.write(intFrameType);
builder.write(streamId);
builder.write(dataLimit);
builder.appendFrame(std::move(streamBlockedFrame));
return blockedFrameSize;
}
// no space left in packet
return size_t(0);
}
case QuicWriteFrame::Type::StreamsBlockedFrame: {
StreamsBlockedFrame& streamsBlockedFrame = *frame.asStreamsBlockedFrame();
auto frameType = streamsBlockedFrame.isForBidirectionalStream()
? FrameType::STREAMS_BLOCKED_BIDI
: FrameType::STREAMS_BLOCKED_UNI;
QuicInteger intFrameType(static_cast<FrameTypeType>(frameType));
QuicInteger streamId(streamsBlockedFrame.streamLimit);
auto streamBlockedFrameSize = intFrameType.getSize() + streamId.getSize();
if (packetSpaceCheck(spaceLeft, streamBlockedFrameSize)) {
builder.write(intFrameType);
builder.write(streamId);
builder.appendFrame(std::move(streamsBlockedFrame));
return streamBlockedFrameSize;
}
// no space left in packet
return size_t(0);
}
case QuicWriteFrame::Type::ConnectionCloseFrame: {
ConnectionCloseFrame& connectionCloseFrame =
*frame.asConnectionCloseFrame();
// Need to distinguish between CONNECTION_CLOSE & CONNECTINO_CLOSE_APP_ERR
const TransportErrorCode* isTransportErrorCode =
connectionCloseFrame.errorCode.asTransportErrorCode();
const ApplicationErrorCode* isApplicationErrorCode =
connectionCloseFrame.errorCode.asApplicationErrorCode();
QuicInteger intFrameType(static_cast<uint8_t>(
isTransportErrorCode ? FrameType::CONNECTION_CLOSE
: FrameType::CONNECTION_CLOSE_APP_ERR));
QuicInteger reasonLength(connectionCloseFrame.reasonPhrase.size());
Optional<QuicInteger> closingFrameType;
if (isTransportErrorCode) {
closingFrameType = QuicInteger(
static_cast<FrameTypeType>(connectionCloseFrame.closingFrameType));
}
QuicInteger errorCode(
isTransportErrorCode
? static_cast<uint64_t>(TransportErrorCode(*isTransportErrorCode))
: static_cast<uint64_t>(
ApplicationErrorCode(*isApplicationErrorCode)));
size_t errorSize = errorCode.getSize();
auto connCloseFrameSize = intFrameType.getSize() + errorSize +
(closingFrameType ? closingFrameType.value().getSize() : 0) +
reasonLength.getSize() + connectionCloseFrame.reasonPhrase.size();
if (packetSpaceCheck(spaceLeft, connCloseFrameSize)) {
builder.write(intFrameType);
builder.write(errorCode);
if (closingFrameType) {
builder.write(closingFrameType.value());
}
builder.write(reasonLength);
builder.push(
(const uint8_t*)connectionCloseFrame.reasonPhrase.data(),
connectionCloseFrame.reasonPhrase.size());
builder.appendFrame(std::move(connectionCloseFrame));
return connCloseFrameSize;
}
// no space left in packet
return size_t(0);
}
case QuicWriteFrame::Type::PingFrame: {
const PingFrame& pingFrame = *frame.asPingFrame();
QuicInteger intFrameType(static_cast<uint8_t>(FrameType::PING));
if (packetSpaceCheck(spaceLeft, intFrameType.getSize())) {
builder.write(intFrameType);
builder.appendFrame(pingFrame);
return intFrameType.getSize();
}
// no space left in packet
return size_t(0);
}
case QuicWriteFrame::Type::QuicSimpleFrame: {
return writeSimpleFrame(std::move(*frame.asQuicSimpleFrame()), builder);
}
case QuicWriteFrame::Type::DatagramFrame: {
const DatagramFrame& datagramFrame = *frame.asDatagramFrame();
QuicInteger frameTypeQuicInt(
static_cast<uint8_t>(FrameType::DATAGRAM_LEN));
QuicInteger datagramLenInt(datagramFrame.length);
auto datagramFrameLength = frameTypeQuicInt.getSize() +
datagramFrame.length + datagramLenInt.getSize();
if (packetSpaceCheck(spaceLeft, datagramFrameLength)) {
builder.write(frameTypeQuicInt);
builder.write(datagramLenInt);
builder.insert(std::move(datagramFrame.data), datagramFrame.length);
builder.appendFrame(datagramFrame);
return datagramFrameLength;
}
// no space left in packet
return size_t(0);
}
case QuicWriteFrame::Type::ImmediateAckFrame: {
const ImmediateAckFrame& immediateAckFrame = *frame.asImmediateAckFrame();
QuicInteger intFrameType(static_cast<uint8_t>(FrameType::IMMEDIATE_ACK));
if (packetSpaceCheck(spaceLeft, intFrameType.getSize())) {
builder.write(intFrameType);
builder.appendFrame(immediateAckFrame);
return intFrameType.getSize();
}
// no space left in packet
return size_t(0);
}
default: {
auto errorStr = folly::to<std::string>(
"Unknown / unsupported frame type received at ", __func__);
VLOG(2) << errorStr;
throw QuicTransportException(
errorStr, TransportErrorCode::FRAME_ENCODING_ERROR);
}
}
}
} // namespace quic