google/gopacket: routing/routing.go; 23 LoC

Found a possible issue in [google/gopacket](https://www.github.com/google/gopacket) at [routing/routing.go](https://github.com/google/gopacket/blob/0d0933d15ffc4c07d065f45a580d4ae1007c1de4/routing/routing.go#L217-L239)

Below is the message reported by the analyzer for this snippet of code. Beware that the analyzer only reports the first issue it finds, so please do not limit your consideration to the contents of the below message.

> reference to iface is reassigned at line 218

[Click here to see the code in its original context.](https://github.com/google/gopacket/blob/0d0933d15ffc4c07d065f45a580d4ae1007c1de4/routing/routing.go#L217-L239)

Click here to show the 23 line(s) of Go which triggered the analyzer.

```go
for _, iface := range ifaces {
rtr.ifaces[iface.Index] = &iface
var addrs ipAddrs
ifaceAddrs, err := iface.Addrs()
if err != nil {
return nil, err
}
for _, addr := range ifaceAddrs {
if inet, ok := addr.(*net.IPNet); ok {
// Go has a nasty habit of giving you IPv4s as ::ffff:1.2.3.4 instead of 1.2.3.4.
// We want to use mapped v4 addresses as v4 preferred addresses, never as v6
// preferred addresses.
if v4 := inet.IP.To4(); v4 != nil {
if addrs.v4 == nil {
addrs.v4 = v4
}
} else if addrs.v6 == nil {
addrs.v6 = inet.IP
}
}
}
rtr.addrs[iface.Index] = addrs
}

```

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commit ID: 0d0933d15ffc4c07d065f45a580d4ae1007c1de4