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https://github.com/cwinfo/yggdrasil-go.git
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Clean up the flow a bit (partly because I am allergic to huge compounded if statements)
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@ -423,40 +423,37 @@ func (sinfo *sessionInfo) doWorker() {
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func (sinfo *sessionInfo) doSend(bs []byte) {
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defer util_putBytes(bs)
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if !sinfo.init {
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// To prevent using empty session keys
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return
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} // To prevent using empty session keys
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}
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coords := sinfo.coords
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// Read IPv6 flowlabel field (20 bits).
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// Assumes packet at least contains IPv6 header.
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flowkey := uint64(bs[1]&0x0f)<<16 | uint64(bs[2])<<8 | uint64(bs[3])
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if flowkey == 0 /* not specified */ &&
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len(bs) >= 48 /* min UDP len, others are bigger */ &&
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(bs[6] == 0x06 || bs[6] == 0x11 || bs[6] == 0x84) /* TCP UDP SCTP */ {
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// if flowlabel was unspecified (0), try to use known protocols' ports
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// protokey: proto | sport | dport
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flowkey = uint64(bs[6])<<32 /* proto */ |
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uint64(bs[40])<<24 | uint64(bs[41])<<16 /* sport */ |
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uint64(bs[42])<<8 | uint64(bs[43]) /* dport */
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// Check if the flowlabel was specified
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if flowkey == 0 {
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// Does the packet meet the minimum UDP packet size? (others are bigger)
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if len(bs) >= 48 {
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// Is the protocol TCP, UDP, SCTP?
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if bs[6] == 0x06 || bs[6] == 0x11 || bs[6] == 0x84 {
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// if flowlabel was unspecified (0), try to use known protocols' ports
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// protokey: proto | sport | dport
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flowkey = uint64(bs[6])<<32 /* proto */ |
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uint64(bs[40])<<24 | uint64(bs[41])<<16 /* sport */ |
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uint64(bs[42])<<8 | uint64(bs[43]) /* dport */
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}
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}
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}
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var coords []byte
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// If we have a flowkey, either through the IPv6 flowlabel field or through
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// known TCP/UDP/SCTP proto-sport-dport triplet, then append it to the coords.
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// Appending extra coords after a 0 ensures that we still target the local router
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// but lets us send extra data (which is otherwise ignored) to help separate
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// traffic streams into independent queues
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if flowkey != 0 {
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// Now we append something to the coords
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// Specifically, we append a 0, and then arbitrary data
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// The 0 ensures that the destination node switch forwards to the self peer (router)
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// The rest is ignored, but it's still part as the coords, so it affects switch queues
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// This helps separate traffic streams (coords, flowlabel) to be queued independently
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// TODO could we avoid allocations there and put this work into wire_trafficPacket.encode()?
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coords = append(coords, sinfo.coords...) // Start with the real coords
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coords = append(coords, 0) // Then target the local switchport
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coords = append(coords, 0) // First target the local switchport
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coords = wire_put_uint64(flowkey, coords) // Then variable-length encoded flowkey
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} else {
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// flowlabel was unspecified (0) and protocol unrecognised.
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// To save bytes, we're not including it, therefore we won't need self-port override either.
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// So just use sinfo.coords directly to avoid golang GC allocations.
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// Recent enough Linux and BSDs support flowlabels (auto_flowlabel) out of the box so this will be rare.
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coords = sinfo.coords
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}
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// Prepare the payload
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payload, nonce := boxSeal(&sinfo.sharedSesKey, bs, &sinfo.myNonce)
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defer util_putBytes(payload)
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p := wire_trafficPacket{
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