forked from quic-go/quic-go
106 lines
2.6 KiB
Go
106 lines
2.6 KiB
Go
package quic
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import (
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"bytes"
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"fmt"
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"github.com/lucas-clemente/quic-go/utils"
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)
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// An AckFrame in QUIC
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type AckFrame struct {
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Entropy byte
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LargestObserved uint64
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DelayTime uint16 // Todo: properly interpret this value as described in the specification
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}
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// Write writes an ACK frame.
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func (f *AckFrame) Write(b *bytes.Buffer) error {
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typeByte := uint8(0x48)
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b.WriteByte(typeByte)
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b.WriteByte(f.Entropy)
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utils.WriteUint32(b, uint32(f.LargestObserved)) // TODO: send the correct length
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utils.WriteUint16(b, 1) // TODO: Ack delay time
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b.WriteByte(0x01) // Just one timestamp
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b.WriteByte(0x00) // Largest observed
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utils.WriteUint32(b, 0) // First timestamp
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return nil
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}
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// ParseAckFrame reads an ACK frame
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func ParseAckFrame(r *bytes.Reader, typeByte byte) (*AckFrame, error) {
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frame := &AckFrame{}
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fmt.Printf("Bytes remaining in this packet: %d\n", r.Len())
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if typeByte&0x20 == 0x20 {
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panic("NACK ranges not yet implemented.")
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}
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if typeByte&0x20 == 0x20 {
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panic("truncated ACKs not yet implemented.")
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}
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largestObservedLen := 2 * ((typeByte & 0x0C) >> 2)
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if largestObservedLen == 0 {
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largestObservedLen = 1
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}
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missingSequenceNumberDeltaLen := 2 * (typeByte & 0x11)
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if missingSequenceNumberDeltaLen == 0 {
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missingSequenceNumberDeltaLen = 1
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}
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var err error
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frame.Entropy, err = r.ReadByte() // read 1
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if err != nil {
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return nil, err
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}
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frame.LargestObserved, err = utils.ReadUintN(r, largestObservedLen) // read 1
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if err != nil {
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return nil, err
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}
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frame.DelayTime, err = utils.ReadUint16(r) // read 2
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if err != nil {
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return nil, err
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}
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numTimestampByte, err := r.ReadByte() // read 1
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if err != nil {
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return nil, err
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}
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numTimestamp := uint8(numTimestampByte)
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fmt.Printf("\tnumTimestamp: %d\n", numTimestamp)
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// 1 byte Delta Largest observed
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_, err = r.ReadByte() // read 1
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if err != nil {
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return nil, err
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}
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// 4 byte First timestamp
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firstTimestamp, err := utils.ReadUint32(r) // read 4
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if err != nil {
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return nil, err
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}
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fmt.Printf("\tfirstTimestamp: %d\n", firstTimestamp)
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for i := 0; i < int(numTimestamp)-1; i++ { // ToDo: check number of repititions
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fmt.Printf("\tTimestamp #%d\n", i+2)
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// 1 byte Delta Largest observed
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_, err = r.ReadByte()
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if err != nil {
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return nil, err
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}
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// 2 byte Time Since Previous Timestamp
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timeSincePreviousTimestamp, err := utils.ReadUint16(r)
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if err != nil {
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return nil, err
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}
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fmt.Printf("\t\ttimeSincePreviousTimestamp: %d\n", timeSincePreviousTimestamp)
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}
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fmt.Printf("Bytes remaining in this packet: %d\n", r.Len())
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return frame, nil
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}
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