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260 lines
8 KiB
Go
260 lines
8 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/internal/utils"
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"github.com/lucas-clemente/quic-go/protocol"
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"github.com/lucas-clemente/quic-go/qerr"
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)
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var (
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errPacketNumberLenNotSet = errors.New("PublicHeader: PacketNumberLen not set")
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errResetAndVersionFlagSet = errors.New("PublicHeader: Reset Flag and Version Flag should not be set at the same time")
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errReceivedTruncatedConnectionID = qerr.Error(qerr.InvalidPacketHeader, "receiving packets with truncated ConnectionID is not supported")
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errInvalidConnectionID = qerr.Error(qerr.InvalidPacketHeader, "connection ID cannot be 0")
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errGetLengthNotForVersionNegotiation = errors.New("PublicHeader: GetLength cannot be called for VersionNegotiation packets")
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)
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// The PublicHeader of a QUIC packet. Warning: This struct should not be considered stable and will change soon.
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type PublicHeader struct {
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Raw []byte
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ConnectionID protocol.ConnectionID
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VersionFlag bool
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ResetFlag bool
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TruncateConnectionID bool
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PacketNumberLen protocol.PacketNumberLen
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PacketNumber protocol.PacketNumber
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VersionNumber protocol.VersionNumber // VersionNumber sent by the client
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SupportedVersions []protocol.VersionNumber // VersionNumbers sent by the server
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DiversificationNonce []byte
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}
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// Write writes a public header. Warning: This API should not be considered stable and will change soon.
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func (h *PublicHeader) Write(b *bytes.Buffer, version protocol.VersionNumber, pers protocol.Perspective) error {
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publicFlagByte := uint8(0x00)
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if h.VersionFlag && h.ResetFlag {
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return errResetAndVersionFlagSet
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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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if !h.TruncateConnectionID {
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publicFlagByte |= 0x08
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}
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if len(h.DiversificationNonce) > 0 {
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if len(h.DiversificationNonce) != 32 {
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return errors.New("invalid diversification nonce length")
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}
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publicFlagByte |= 0x04
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}
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// only set PacketNumberLen bits if a packet number will be written
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if h.hasPacketNumber(pers) {
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switch h.PacketNumberLen {
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case protocol.PacketNumberLen1:
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publicFlagByte |= 0x00
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case protocol.PacketNumberLen2:
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publicFlagByte |= 0x10
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case protocol.PacketNumberLen4:
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publicFlagByte |= 0x20
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case protocol.PacketNumberLen6:
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publicFlagByte |= 0x30
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}
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}
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b.WriteByte(publicFlagByte)
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if !h.TruncateConnectionID {
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utils.WriteUint64(b, uint64(h.ConnectionID))
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}
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if h.VersionFlag && pers == protocol.PerspectiveClient {
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utils.WriteUint32(b, protocol.VersionNumberToTag(h.VersionNumber))
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}
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if len(h.DiversificationNonce) > 0 {
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b.Write(h.DiversificationNonce)
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}
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// if we're a server, and the VersionFlag is set, we must not include anything else in the packet
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if !h.hasPacketNumber(pers) {
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return nil
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}
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if h.PacketNumberLen != protocol.PacketNumberLen1 && h.PacketNumberLen != protocol.PacketNumberLen2 && h.PacketNumberLen != protocol.PacketNumberLen4 && h.PacketNumberLen != protocol.PacketNumberLen6 {
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return errPacketNumberLenNotSet
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}
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switch h.PacketNumberLen {
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case protocol.PacketNumberLen1:
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b.WriteByte(uint8(h.PacketNumber))
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case protocol.PacketNumberLen2:
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utils.WriteUint16(b, uint16(h.PacketNumber))
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case protocol.PacketNumberLen4:
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utils.WriteUint32(b, uint32(h.PacketNumber))
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case protocol.PacketNumberLen6:
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utils.WriteUint48(b, uint64(h.PacketNumber))
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default:
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return errPacketNumberLenNotSet
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}
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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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// The packetSentBy is the perspective of the peer that sent this PublicHeader, i.e. if we're the server, packetSentBy should be PerspectiveClient.
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// Warning: This API should not be considered stable and will change soon.
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func ParsePublicHeader(b *bytes.Reader, packetSentBy protocol.Perspective) (*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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// TODO: activate this check once Chrome sends the correct value
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// see https://github.com/lucas-clemente/quic-go/issues/232
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// if publicFlagByte&0x04 > 0 {
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// return nil, errors.New("diversification nonces should only be sent by servers")
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// }
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header.TruncateConnectionID = publicFlagByte&0x08 == 0
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if header.TruncateConnectionID && packetSentBy == protocol.PerspectiveClient {
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return nil, errReceivedTruncatedConnectionID
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}
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if header.hasPacketNumber(packetSentBy) {
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switch publicFlagByte & 0x30 {
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case 0x30:
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header.PacketNumberLen = protocol.PacketNumberLen6
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case 0x20:
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header.PacketNumberLen = protocol.PacketNumberLen4
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case 0x10:
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header.PacketNumberLen = protocol.PacketNumberLen2
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case 0x00:
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header.PacketNumberLen = protocol.PacketNumberLen1
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}
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}
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// Connection ID
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if !header.TruncateConnectionID {
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var connID uint64
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connID, err = utils.ReadUint64(b)
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if err != nil {
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return nil, err
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}
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header.ConnectionID = protocol.ConnectionID(connID)
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if header.ConnectionID == 0 {
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return nil, errInvalidConnectionID
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}
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}
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if packetSentBy == protocol.PerspectiveServer && publicFlagByte&0x04 > 0 {
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// TODO: remove the if once the Google servers send the correct value
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// assume that a packet doesn't contain a diversification nonce if the version flag or the reset flag is set, no matter what the public flag says
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// see https://github.com/lucas-clemente/quic-go/issues/232
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if !header.VersionFlag && !header.ResetFlag {
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header.DiversificationNonce = make([]byte, 32)
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if _, err := io.ReadFull(b, header.DiversificationNonce); err != nil {
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return nil, err
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}
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}
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}
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// Version (optional)
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if !header.ResetFlag {
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if header.VersionFlag {
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if packetSentBy == protocol.PerspectiveClient {
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var versionTag uint32
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versionTag, err = utils.ReadUint32(b)
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if err != nil {
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return nil, err
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}
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header.VersionNumber = protocol.VersionTagToNumber(versionTag)
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} else { // parse the version negotiaton packet
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if b.Len()%4 != 0 {
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return nil, qerr.InvalidVersionNegotiationPacket
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}
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header.SupportedVersions = make([]protocol.VersionNumber, 0)
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for {
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var versionTag uint32
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versionTag, err = utils.ReadUint32(b)
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if err != nil {
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break
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}
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v := protocol.VersionTagToNumber(versionTag)
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header.SupportedVersions = append(header.SupportedVersions, v)
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}
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}
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}
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}
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// Packet number
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if header.hasPacketNumber(packetSentBy) {
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packetNumber, err := utils.ReadUintN(b, uint8(header.PacketNumberLen))
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if err != nil {
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return nil, err
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}
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header.PacketNumber = protocol.PacketNumber(packetNumber)
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}
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return header, nil
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}
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// GetLength gets the length of the publicHeader in bytes.
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// It can only be called for regular packets.
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func (h *PublicHeader) GetLength(pers protocol.Perspective) (protocol.ByteCount, error) {
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if h.VersionFlag && h.ResetFlag {
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return 0, errResetAndVersionFlagSet
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}
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if h.VersionFlag && pers == protocol.PerspectiveServer {
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return 0, errGetLengthNotForVersionNegotiation
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}
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length := protocol.ByteCount(1) // 1 byte for public flags
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if h.hasPacketNumber(pers) {
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if h.PacketNumberLen != protocol.PacketNumberLen1 && h.PacketNumberLen != protocol.PacketNumberLen2 && h.PacketNumberLen != protocol.PacketNumberLen4 && h.PacketNumberLen != protocol.PacketNumberLen6 {
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return 0, errPacketNumberLenNotSet
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}
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length += protocol.ByteCount(h.PacketNumberLen)
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}
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if !h.TruncateConnectionID {
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length += 8 // 8 bytes for the connection ID
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}
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// Version Number in packets sent by the client
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if h.VersionFlag {
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length += 4
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}
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length += protocol.ByteCount(len(h.DiversificationNonce))
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return length, nil
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}
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// hasPacketNumber determines if this PublicHeader will contain a packet number
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// this depends on the ResetFlag, the VersionFlag and who sent the packet
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func (h *PublicHeader) hasPacketNumber(packetSentBy protocol.Perspective) bool {
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if h.ResetFlag {
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return false
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}
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if h.VersionFlag && packetSentBy == protocol.PerspectiveServer {
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return false
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}
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return true
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}
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