yggdrasil-network/yggdrasil-go
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1. added FlowKeyMessage type

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This commit is contained in:
vadym 2021-07-11 12:40:00 +03:00
parent 4bc342ec13
commit fb7b1f2c20
1 changed files with 43 additions and 0 deletions
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43
src/util/util.go
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@ -8,6 +8,11 @@ import (
"time"
)
type FlowKeyMessage struct {
FlowKey uint64
Message []byte
}
// TimerStop stops a timer and makes sure the channel is drained, returns true if the timer was stopped before firing.
func TimerStop(t *time.Timer) bool {
stopped := t.Stop()
@ -35,3 +40,41 @@ func FuncTimeout(timeout time.Duration, f func()) bool {
return false
}
}
// GetFlowKey takes an IP packet as an argument and returns some information about the traffic flow.
// For IPv4 packets, this is derived from the source and destination protocol and port numbers.
// For IPv6 packets, this is derived from the FlowLabel field of the packet if this was set, otherwise it's handled like IPv4.
// The FlowKey is then used internally by Yggdrasil for congestion control.
func GetFlowKey(bs []byte) uint64 {
// Work out the flowkey - this is used to determine which switch queue
// traffic will be pushed to in the event of congestion
var flowkey uint64
// Get the IP protocol version from the packet
switch bs[0] & 0xf0 {
case 0x40: // IPv4 packet
ihl := (bs[0] & 0x0f) * 4 // whole IPv4 header length (min 20)
// 8 is minimum UDP packet length
if ihl >= 20 && len(bs)-int(ihl) >= 8 {
switch bs[9] /* protocol */ {
case 0x06 /* TCP */, 0x11 /* UDP */, 0x84 /* SCTP */ :
flowkey = uint64(bs[9])<<32 /* proto */ |
uint64(bs[ihl+0])<<24 | uint64(bs[ihl+1])<<16 /* sport */ |
uint64(bs[ihl+2])<<8 | uint64(bs[ihl+3]) /* dport */
}
}
case 0x60: // IPv6 packet
// Check if the flowlabel was specified in the packet header
flowkey = uint64(bs[1]&0x0f)<<16 | uint64(bs[2])<<8 | uint64(bs[3])
// If the flowlabel isn't present, make protokey from proto | sport | dport
// if the packet meets minimum UDP packet length
if flowkey == 0 && len(bs) >= 48 {
switch bs[9] /* protocol */ {
case 0x06 /* TCP */, 0x11 /* UDP */, 0x84 /* SCTP */ :
flowkey = uint64(bs[6])<<32 /* proto */ |
uint64(bs[40])<<24 | uint64(bs[41])<<16 /* sport */ |
uint64(bs[42])<<8 | uint64(bs[43]) /* dport */
}
}
}
return flowkey
}