41 lines
699 B
Go
41 lines
699 B
Go
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package main
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import (
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"fmt"
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"log"
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"net"
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"os"
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"strings"
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"github.com/google/gopacket/routing"
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)
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func main() {
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ips := os.Args[1:]
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switch {
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case len(ips) == 0:
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log.Fatal("Expect exactly one argument")
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case len(ips) >= 2:
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log.Fatal("Expect only one argument")
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}
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rawIP := strings.Split(ips[0], "/")[0]
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ip := net.ParseIP(rawIP)
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if ip == nil {
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log.Fatal("failed to parse raw ip")
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}
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router, err := routing.New()
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if err != nil {
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log.Fatalf("failed to get new routing instance: %v", err.Error())
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}
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_, _, prefferedSrc, err := router.Route(ip)
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if err != nil {
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log.Fatalf("failed to find gateway for ip: %v", err.Error())
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}
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fmt.Fprintln(os.Stdout, prefferedSrc.String())
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}
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