Timeout probes can have name/ip or not depending of the position in traceroute output

[rarylson]

Consider the following example:

traceroute to vialink.com.br (52.33.65.153), 64 hops max, 52 byte packets
 7  * * *

Here, we'll have three probes. Each one will have rtt = None and ip = None.

Now, in this example:

traceroute to vialink.com.br (52.33.65.153), 64 hops max, 52 byte packets
25  * * 52.93.14.61 (52.93.14.61)  218.370 ms

We will have three probes here. The first two will have rtt = None and ip = None. The last one will have rtt = 218.370 and ip = 52.93.14.61.

Lastly:

traceroute to vialink.com.br (52.33.65.153), 64 hops max, 52 byte packets
10  xe-0-0-0.96.jr03-napbr-db.durand.com.br (200.170.83.97)  20.741 ms  *  16.571 ms

We will also have three probes. The second one will have rtt = None (since it is a timeout) but it will have ip = '200.170.83.97'. This happens because the add_probe method always use the last probe info (name/ip) if the new one has no IP:

    def add_probe(self, probe):
        """Adds a Probe instance to this hop's results."""
        if self.probes:
            probe_last = self.probes[-1]
            if not probe.ip:
                probe.ip = probe_last.ip
                probe.name = probe_last.name
        self.probes.append(probe)

I think this behavior is inconsistent because the same probe can have or not IP depending on the position it is found. So I think a proper behavior is to always use ip = None and name = None in timeout probes. If we consider we never know the host (name/ip) which produced the timeout (can be another host different than the previous one), it makes sense to leave ip = None and name = None in timeout probes.

[rarylson]

Did some tests and the bug still exists in v0.3.0.