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always use 4 byte packet numbers for long header packets

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When retransmitting a long header packet, we never have to split CRYPTO
frames, since the header is guaranteed to have the same size.
This commit is contained in:
Marten Seemann
2018-11-28 11:47:38 +07:00
parent 723e18c78c
commit 05434fecbc
2 changed files with 9 additions and 2 deletions
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8
packet_packer.go
View File

@@ -169,8 +169,10 @@ func (p *packetPacker) MaybePackAckPacket() (*packedPacket, error) {
func (p *packetPacker) PackRetransmission(packet *ackhandler.Packet) ([]*packedPacket, error) {
var controlFrames []wire.Frame
var streamFrames []*wire.StreamFrame
// TODO: treat CRYPTO frames separately
for _, f := range packet.Frames {
// CRYPTO frames are treated as control frames here.
// Since we're making sure that the header can never be larger for a retransmission,
// we never have to split CRYPTO frames.
if sf, ok := f.(*wire.StreamFrame); ok {
sf.DataLenPresent = true
streamFrames = append(streamFrames, sf)
@@ -370,6 +372,10 @@ func (p *packetPacker) getHeader(encLevel protocol.EncryptionLevel) *wire.Extend
if encLevel != protocol.Encryption1RTT {
header.IsLongHeader = true
// Always send Initial and Handshake packets with the maximum packet number length.
// This simplifies retransmissions: Since the header can't get any larger,
// we don't need to split CRYPTO frames.
header.PacketNumberLen = protocol.PacketNumberLen4
header.SrcConnectionID = p.srcConnID
// Set the length to the maximum packet size.
// Since it is encoded as a varint, this guarantees us that the header will end up at most as big as GetLength() returns.

3
packet_packer_test.go
View File

@@ -115,7 +115,8 @@ var _ = Describe("Packet packer", func() {
h := packer.getHeader(protocol.EncryptionHandshake)
Expect(h.IsLongHeader).To(BeTrue())
Expect(h.PacketNumber).To(Equal(protocol.PacketNumber(0x42)))
Expect(h.PacketNumberLen).To(Equal(protocol.PacketNumberLen2))
// long headers always use 4 byte packet numbers, no matter what the packet number generator says
Expect(h.PacketNumberLen).To(Equal(protocol.PacketNumberLen4))
Expect(h.Version).To(Equal(packer.version))
})