cwinfo/yggdrasil-go
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Clean up / clarify coords sending code.

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cathugger 2018-07-30 00:01:37 +00:00
parent 11b0a82c4a
commit fec7100898
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1 changed files with 6 additions and 5 deletions
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11
src/yggdrasil/session.go
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@ -428,7 +428,7 @@ func (sinfo *sessionInfo) doSend(bs []byte) {
var coords []byte
// Read IPv6 flowlabel field (20 bits).
// XXX(cathugger): is len(bs) validated there?
// Assumes packet at least contains IPv6 header.
flowlabel := uint(bs[1]&0x0f)<<16 | uint(bs[2])<<8 | uint(bs[3])
if flowlabel != 0 {
// Now we append something to the coords
@ -437,14 +437,15 @@ func (sinfo *sessionInfo) doSend(bs []byte) {
// 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
coords = append(coords, sinfo.coords...) // Start with the real coords
coords = append(coords, 0) // Then target the local switchport
coords = wire_put_uint64(uint64(flowlabel), coords) // 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?
// Recent enough Linux kernel supports flowlabels out of the box so this will be rare.
// XXX Attempt to look into TCP/UDP/SCTP/DCCP headers' sport/dport fields there?
coords = sinfo.coords
}
payload, nonce := boxSeal(&sinfo.sharedSesKey, bs, &sinfo.myNonce)