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apply header encryption when packing and unpacking packets

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This commit is contained in:
Marten Seemann 2018-12-14 21:34:00 +06:30
parent 5a68ba0a02
commit a638185f97
4 changed files with 748 additions and 626 deletions
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51
packet_unpacker.go
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@ -47,23 +47,6 @@ func (u *packetUnpacker) Unpack(hdr *wire.Header, data []byte) (*unpackedPacket,
// TODO(#1312): implement parsing of compound packets
}
extHdr, err := hdr.ParseExtended(r, u.version)
if err != nil {
return nil, fmt.Errorf("error parsing extended header: %s", err)
}
extHdr.Raw = data[:len(data)-r.Len()]
data = data[len(data)-r.Len():]
pn := protocol.DecodePacketNumber(
extHdr.PacketNumberLen,
u.largestRcvdPacketNumber,
extHdr.PacketNumber,
)
buf := *getPacketBuffer()
buf = buf[:0]
defer putPacketBuffer(&buf)
var encLevel protocol.EncryptionLevel
switch hdr.Type {
case protocol.PacketTypeInitial:
@ -80,6 +63,40 @@ func (u *packetUnpacker) Unpack(hdr *wire.Header, data []byte) (*unpackedPacket,
if err != nil {
return nil, qerr.Error(qerr.DecryptionFailure, err.Error())
}
hdrLen := int(hdr.ParsedLen())
// The packet number can be up to 4 bytes long, but we won't know the length until we decrypt it.
// 1. save a copy of the 4 bytes
origPNBytes := make([]byte, 4)
copy(origPNBytes, data[hdrLen:hdrLen+4])
// 2. decrypt the header, assuming a 4 byte packet number
opener.DecryptHeader(
data[hdrLen+4:hdrLen+4+16],
&data[0],
data[hdrLen:hdrLen+4],
)
// 3. parse the header (and learn the actual length of the packet number)
extHdr, err := hdr.ParseExtended(r, u.version)
if err != nil {
return nil, fmt.Errorf("error parsing extended header: %s", err)
}
extHdr.Raw = data[:hdrLen+int(extHdr.PacketNumberLen)]
// 4. if the packet number is shorter than 4 bytes, replace the remaining bytes with the copy we saved earlier
if extHdr.PacketNumberLen != protocol.PacketNumberLen4 {
copy(data[hdrLen+int(extHdr.PacketNumberLen):hdrLen+4], origPNBytes[int(extHdr.PacketNumberLen):])
}
data = data[hdrLen+int(extHdr.PacketNumberLen):]
pn := protocol.DecodePacketNumber(
extHdr.PacketNumberLen,
u.largestRcvdPacketNumber,
extHdr.PacketNumber,
)
buf := *getPacketBuffer()
buf = buf[:0]
defer putPacketBuffer(&buf)
decrypted, err := opener.Open(buf, data, pn, extHdr.Raw)
if err != nil {
return nil, qerr.Error(qerr.DecryptionFailure, err.Error())