forked from quic-go/quic-go
95 lines
1.9 KiB
Go
95 lines
1.9 KiB
Go
package quic
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import (
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"bytes"
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"errors"
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"io"
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"github.com/lucas-clemente/quic-go/utils"
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)
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// The PublicHeader of a QUIC packet
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type PublicHeader struct {
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VersionFlag bool
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ResetFlag bool
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ConnectionID uint64
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QuicVersion uint32
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PacketNumber uint64
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// packetNumberLen uint8
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}
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// WritePublicHeader writes a public header
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func (h *PublicHeader) WritePublicHeader(b *bytes.Buffer) error {
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publicFlagByte := uint8(0x0C | 0x20)
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if h.VersionFlag && h.ResetFlag {
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return errors.New("Reset Flag and Version Flag should not be set at the same time")
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}
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if h.VersionFlag {
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publicFlagByte |= 0x01
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}
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if h.ResetFlag {
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publicFlagByte |= 0x02
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}
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b.WriteByte(publicFlagByte)
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utils.WriteUint64(b, h.ConnectionID) // TODO: Send shorter connection id if possible
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utils.WriteUint32(b, uint32(h.PacketNumber)) // TODO: Send shorter packet number if possible
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return nil
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}
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// ParsePublicHeader parses a QUIC packet's public header
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func ParsePublicHeader(b io.ByteReader) (*PublicHeader, error) {
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header := &PublicHeader{}
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// First byte
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publicFlagByte, err := b.ReadByte()
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if err != nil {
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return nil, err
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}
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header.VersionFlag = publicFlagByte&0x01 > 0
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header.ResetFlag = publicFlagByte&0x02 > 0
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var connectionIDLen, packetNumberLen uint8
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switch publicFlagByte & 0x0C {
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case 0x0C:
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connectionIDLen = 8
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case 0x08:
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connectionIDLen = 4
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case 0x04:
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connectionIDLen = 1
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}
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switch publicFlagByte & 0x30 {
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case 0x30:
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packetNumberLen = 6
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case 0x20:
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packetNumberLen = 4
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case 0x10:
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packetNumberLen = 2
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case 0x00:
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packetNumberLen = 1
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}
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// Connection ID
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header.ConnectionID, err = utils.ReadUintN(b, connectionIDLen)
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if err != nil {
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return nil, err
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}
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// Version (optional)
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if header.VersionFlag {
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header.QuicVersion, err = utils.ReadUint32BigEndian(b)
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if err != nil {
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return nil, err
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}
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}
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// Packet number
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header.PacketNumber, err = utils.ReadUintN(b, packetNumberLen)
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if err != nil {
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return nil, err
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}
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return header, nil
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}
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