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Simpler flowlabel parsing; avoid using 0 flowlabel.

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cathugger 2018-07-29 22:09:16 +00:00
parent ddab8ecf33
commit 11b0a82c4a
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1 changed files with 20 additions and 20 deletions
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40
src/yggdrasil/session.go
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@ -425,28 +425,28 @@ func (sinfo *sessionInfo) doSend(bs []byte) {
if !sinfo.init {
return
} // To prevent using empty session keys
// Now we append something to the coords
// Specifically, we append a 0, and then arbitrary data
// The 0 ensures that the destination node switch forwards to the self peer (router)
// The rest is ignored, but it's still part as the coords, so it affects switch queues
// This helps separate traffic streams (coords, flowlabel) to be queued independently
var coords []byte
addUint64 := func(bs []byte) {
// Converts bytes to a uint64
// Converts that back to variable length bytes
// Appends it to coords
var u uint64
for _, b := range bs {
u <<= 8
u |= uint64(b)
}
coords = append(coords, wire_encode_uint64(u)...)
// Read IPv6 flowlabel field (20 bits).
// XXX(cathugger): is len(bs) validated there?
flowlabel := uint(bs[1]&0x0f)<<16 | uint(bs[2])<<8 | uint(bs[3])
if flowlabel != 0 {
// Now we append something to the coords
// Specifically, we append a 0, and then arbitrary data
// The 0 ensures that the destination node switch forwards to the self peer (router)
// The rest is ignored, but it's still part as the coords, so it affects switch queues
// This helps separate traffic streams (coords, flowlabel) to be queued independently
coords = append(coords, sinfo.coords...) // Start with the real coords
coords = append(coords, 0) // Then target the local switchport
coords = append(coords, wire_encode_uint64(uint64(flowlabel))...) // Then variable-length encoded flowlabel
} else {
// 0 value means that flowlabels aren't being generated by OS.
// To save bytes, we're not including it, therefore we won't need self-port override either.
// So just use sinfo.coords directly to avoid golang GC allocations.
// XXX: investigate where flowlabels aren't included, and attempt to look into TCP/UDP/SCTP/DCCP headers' sport/dport fields?
coords = sinfo.coords
}
coords = append(coords, sinfo.coords...) // Start with the real coords
coords = append(coords, 0) // Then target the local switchport
flowlabel := append([]byte(nil), bs[1:4]...)
flowlabel[0] &= 0x0f
addUint64(flowlabel)
payload, nonce := boxSeal(&sinfo.sharedSesKey, bs, &sinfo.myNonce)
defer util_putBytes(payload)
p := wire_trafficPacket{