forked from qdeconinck/mp-quic
/
close_path_frame.go
418 lines (349 loc) · 10.5 KB
/
close_path_frame.go
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package wire
import (
"bytes"
"errors"
"github.com/lucas-clemente/quic-go/internal/protocol"
"github.com/lucas-clemente/quic-go/internal/utils"
)
// A ClosePathFrame in (IETF) QUIC
type ClosePathFrame struct {
PathID protocol.PathID
LargestAcked protocol.PacketNumber
LowestAcked protocol.PacketNumber
AckRanges []AckRange // has to be ordered. The ACK range with the highest First goes first, the ACK range with the lowest First goes last
}
func (f *ClosePathFrame) Write(b *bytes.Buffer, version protocol.VersionNumber) error {
typeByte := uint8(0x11)
b.WriteByte(typeByte)
b.WriteByte(uint8(f.PathID))
largestAckedLen := protocol.GetPacketNumberLength(f.LargestAcked)
var flags uint8 = 0x00
if f.HasMissingRanges() {
flags |= 0x10
}
if largestAckedLen != protocol.PacketNumberLen1 {
flags ^= (uint8(largestAckedLen / 2)) << 2
}
missingSequenceNumberDeltaLen := f.getMissingSequenceNumberDeltaLen()
if missingSequenceNumberDeltaLen != protocol.PacketNumberLen1 {
flags ^= (uint8(missingSequenceNumberDeltaLen / 2))
}
b.WriteByte(flags)
var numRanges uint64
var numRangesWritten uint64
if f.HasMissingRanges() {
numRanges = f.numWritableNackRanges()
if numRanges > 0xFF {
panic("ClosePathFrame: Too many ACK ranges")
}
b.WriteByte(uint8(numRanges - 1))
}
switch largestAckedLen {
case protocol.PacketNumberLen1:
b.WriteByte(uint8(f.LargestAcked))
case protocol.PacketNumberLen2:
utils.GetByteOrder(version).WriteUint16(b, uint16(f.LargestAcked))
case protocol.PacketNumberLen4:
utils.GetByteOrder(version).WriteUint32(b, uint32(f.LargestAcked))
case protocol.PacketNumberLen6:
utils.GetByteOrder(version).WriteUint48(b, uint64(f.LargestAcked))
}
var firstAckBlockLength protocol.PacketNumber
if !f.HasMissingRanges() {
firstAckBlockLength = f.LargestAcked - f.LowestAcked + 1
} else {
if f.LargestAcked != f.AckRanges[0].Last {
return errInconsistentAckLargestAcked
}
if f.LowestAcked != f.AckRanges[len(f.AckRanges)-1].First {
return errInconsistentAckLowestAcked
}
firstAckBlockLength = f.LargestAcked - f.AckRanges[0].First + 1
numRangesWritten++
}
switch missingSequenceNumberDeltaLen {
case protocol.PacketNumberLen1:
b.WriteByte(uint8(firstAckBlockLength))
case protocol.PacketNumberLen2:
utils.GetByteOrder(version).WriteUint16(b, uint16(firstAckBlockLength))
case protocol.PacketNumberLen4:
utils.GetByteOrder(version).WriteUint32(b, uint32(firstAckBlockLength))
case protocol.PacketNumberLen6:
utils.GetByteOrder(version).WriteUint48(b, uint64(firstAckBlockLength))
}
for i, ackRange := range f.AckRanges {
if i == 0 {
continue
}
length := ackRange.Last - ackRange.First + 1
gap := f.AckRanges[i-1].First - ackRange.Last - 1
num := gap/0xFF + 1
if gap%0xFF == 0 {
num--
}
if num == 1 {
b.WriteByte(uint8(gap))
switch missingSequenceNumberDeltaLen {
case protocol.PacketNumberLen1:
b.WriteByte(uint8(length))
case protocol.PacketNumberLen2:
utils.GetByteOrder(version).WriteUint16(b, uint16(length))
case protocol.PacketNumberLen4:
utils.GetByteOrder(version).WriteUint32(b, uint32(length))
case protocol.PacketNumberLen6:
utils.GetByteOrder(version).WriteUint48(b, uint64(length))
}
numRangesWritten++
} else {
for i := 0; i < int(num); i++ {
var lengthWritten uint64
var gapWritten uint8
if i == int(num)-1 { // last block
lengthWritten = uint64(length)
gapWritten = uint8(1 + ((gap - 1) % 255))
} else {
lengthWritten = 0
gapWritten = 0xFF
}
b.WriteByte(gapWritten)
switch missingSequenceNumberDeltaLen {
case protocol.PacketNumberLen1:
b.WriteByte(uint8(lengthWritten))
case protocol.PacketNumberLen2:
utils.GetByteOrder(version).WriteUint16(b, uint16(lengthWritten))
case protocol.PacketNumberLen4:
utils.GetByteOrder(version).WriteUint32(b, uint32(lengthWritten))
case protocol.PacketNumberLen6:
utils.GetByteOrder(version).WriteUint48(b, lengthWritten)
}
numRangesWritten++
}
}
// this is needed if not all AckRanges can be written to the ACK frame (if there are more than 0xFF)
if numRangesWritten >= numRanges {
break
}
}
if numRanges != numRangesWritten {
return errors.New("BUG: Inconsistent number of ACK ranges written in ClosePath")
}
return nil
}
func ParseClosePathFrame(r *bytes.Reader, version protocol.VersionNumber) (*ClosePathFrame, error) {
frame := &ClosePathFrame{}
// read the TypeByte
_, err := r.ReadByte()
if err != nil {
return nil, err
}
pathID, err := r.ReadByte()
if err != nil {
return nil, err
}
frame.PathID = protocol.PathID(pathID)
flags, err := r.ReadByte()
if err != nil {
return nil, err
}
hasMissingRanges := false
if flags&0x10 == 0x10 {
hasMissingRanges = true
}
largestAckedLen := 2 * ((flags & 0x0C) >> 2)
if largestAckedLen == 0 {
largestAckedLen = 1
}
missingSequenceNumberDeltaLen := 2 * (flags & 0x03)
if missingSequenceNumberDeltaLen == 0 {
missingSequenceNumberDeltaLen = 1
}
var numAckBlocks uint8
if hasMissingRanges {
numAckBlocks, err = r.ReadByte()
if err != nil {
return nil, err
}
}
if hasMissingRanges && numAckBlocks == 0 {
return nil, ErrInvalidAckRanges
}
largestAcked, err := utils.GetByteOrder(version).ReadUintN(r, largestAckedLen)
if err != nil {
return nil, err
}
frame.LargestAcked = protocol.PacketNumber(largestAcked)
ackBlockLength, err := utils.GetByteOrder(version).ReadUintN(r, missingSequenceNumberDeltaLen)
if err != nil {
return nil, err
}
if frame.LargestAcked > 0 && ackBlockLength < 1 {
return nil, ErrInvalidFirstAckRange
}
if ackBlockLength > largestAcked {
return nil, ErrInvalidAckRanges
}
if hasMissingRanges {
ackRange := AckRange{
First: protocol.PacketNumber(largestAcked-ackBlockLength) + 1,
Last: frame.LargestAcked,
}
frame.AckRanges = append(frame.AckRanges, ackRange)
var inLongBlock bool
var lastRangeComplete bool
for i := uint8(0); i < numAckBlocks; i++ {
var gap uint8
gap, err = r.ReadByte()
if err != nil {
return nil, err
}
ackBlockLength, err = utils.GetByteOrder(version).ReadUintN(r, missingSequenceNumberDeltaLen)
if err != nil {
return nil, err
}
length := protocol.PacketNumber(ackBlockLength)
if inLongBlock {
frame.AckRanges[len(frame.AckRanges)-1].First -= protocol.PacketNumber(gap) + length
frame.AckRanges[len(frame.AckRanges)-1].Last -= protocol.PacketNumber(gap)
} else {
lastRangeComplete = false
ackRange := AckRange{
Last: frame.AckRanges[len(frame.AckRanges)-1].First - protocol.PacketNumber(gap) - 1,
}
ackRange.First = ackRange.Last - length + 1
frame.AckRanges = append(frame.AckRanges, ackRange)
}
if length > 0 {
lastRangeComplete = true
}
inLongBlock = (ackBlockLength == 0)
}
// if the last range was not complete, First and Last make no sense
// remote the range from frame.AckRanges
if !lastRangeComplete {
frame.AckRanges = frame.AckRanges[:len(frame.AckRanges)-1]
}
frame.LowestAcked = frame.AckRanges[len(frame.AckRanges)-1].First
} else {
if frame.LargestAcked == 0 {
frame.LowestAcked = 0
} else {
frame.LowestAcked = protocol.PacketNumber(largestAcked + 1 - ackBlockLength)
}
}
if !frame.validateAckRanges() {
return nil, ErrInvalidAckRanges
}
return frame, nil
}
func (f *ClosePathFrame) MinLength(version protocol.VersionNumber) (protocol.ByteCount, error) {
length := protocol.ByteCount(1 + 1 + 1) // 1 TypeByte, 1 PathID, 1 Flags
length += protocol.ByteCount(protocol.GetPacketNumberLength(f.LargestAcked))
missingSequenceNumberDeltaLen := protocol.ByteCount(f.getMissingSequenceNumberDeltaLen())
if f.HasMissingRanges() {
// The First ACK block and the NumBlocks field are taken into account
length += (1 + missingSequenceNumberDeltaLen) * protocol.ByteCount(f.numWritableNackRanges())
} else {
length += missingSequenceNumberDeltaLen
}
return length, nil
}
func (f *ClosePathFrame) HasMissingRanges() bool {
return len(f.AckRanges) > 0
}
func (f *ClosePathFrame) validateAckRanges() bool {
if len(f.AckRanges) == 0 {
return true
}
// if there are missing packets, there will always be at least 2 ACK ranges
if len(f.AckRanges) == 1 {
return false
}
if f.AckRanges[0].Last != f.LargestAcked {
return false
}
// check the validity of every single ACK range
for _, ackRange := range f.AckRanges {
if ackRange.First > ackRange.Last {
return false
}
}
// check the consistency for ACK with multiple NACK ranges
for i, ackRange := range f.AckRanges {
if i == 0 {
continue
}
lastAckRange := f.AckRanges[i-1]
if lastAckRange.First <= ackRange.First {
return false
}
if lastAckRange.First <= ackRange.Last+1 {
return false
}
}
return true
}
func (f *ClosePathFrame) getMissingSequenceNumberDeltaLen() protocol.PacketNumberLen {
var maxRangeLength protocol.PacketNumber
if f.HasMissingRanges() {
for _, ackRange := range f.AckRanges {
rangeLength := ackRange.Last - ackRange.First + 1
if rangeLength > maxRangeLength {
maxRangeLength = rangeLength
}
}
} else {
maxRangeLength = f.LargestAcked - f.LowestAcked + 1
}
if maxRangeLength <= 0xFF {
return protocol.PacketNumberLen1
}
if maxRangeLength <= 0xFFFF {
return protocol.PacketNumberLen2
}
if maxRangeLength <= 0xFFFFFFFF {
return protocol.PacketNumberLen4
}
return protocol.PacketNumberLen6
}
// numWritableNackRanges calculates the number of ACK blocks tht are about to be written
// this number is different from len(f.AckRanges) for the case of long gaps (> 255 packets)
func (f *ClosePathFrame) numWritableNackRanges() uint64 {
if len(f.AckRanges) == 0 {
return 0
}
var numRanges uint64
for i, ackRange := range f.AckRanges {
if i == 0 {
continue
}
lastAckRange := f.AckRanges[i-1]
gap := lastAckRange.First - ackRange.Last - 1
rangeLength := 1 + uint64(gap)/0xFF
if uint64(gap)%0xFF == 0 {
rangeLength--
}
if numRanges+rangeLength < 0xFF {
numRanges += rangeLength
} else {
break
}
}
return numRanges + 1
}
// AcksPacket determines if this ClosePath frame acks a certain packet number
func (f *ClosePathFrame) AcksPacket(p protocol.PacketNumber) bool {
if p < f.LowestAcked || p > f.LargestAcked { // this is just a performance optimization
return false
}
if f.HasMissingRanges() {
// TODO: this could be implemented as a binary search
for _, ackRange := range f.AckRanges {
if p >= ackRange.First && p <= ackRange.Last {
return true
}
}
return false
}
// if packet doesn't have missing ranges
return (p >= f.LowestAcked && p <= f.LargestAcked)
}