coverage for injector_helper

[shalunov]

To better understand what we'll need to do to get good test coverage, let's start with injector helper.

[shalunov]

Is 58% the best we can have with integration tests? Does CI support IPv6? Why isn't the DHT joining code running? I think we could do a lot more.

[inetic]

Currently the tests don't use DHT. Instead injector_helper knows about injector through a command line argument.

I did it this way because:

1. The injector to which the injector_helper connects must be deterministic in tests.
2. Given that the injector is only supposed to connect to the test injector_helper it very likely has not punched a hole through the NAT before the injector_helper attempts to connect.

(1) could potentially be solved by solving issue #13.

(2) is a bit trickier. I think Travis CI workers are not behind a NAT, not 100% sure though. In such case it would work there. For people behind a NAT though, the test would work only if they:

1. Have a NAT with support for hairpinning. Or
2. Explicitly open a UDP in their NAT. Or
3. We use something like uPnP. Or
4. We try to punch a hole ourselves.

I think I'd first try the fourth option...

Does CI support IPv6?

I'll check, but does libbtdht even supports IPv6? I was under the impression it doesn't (the string nodes6 is nowhere to be found in libbtdht as described by BEP0032, also the callback for finding nodes does not mentions type of the endpoints because only IPv4 is assumed).

[shalunov]

There's some untested IPv6 code. Do we need it? If yes, let's cover; if not, let's remove?

[inetic]

There's some untested IPv6 code. Do we need it? If yes, let's cover; if not, let's remove?

AFAIK, that is really only three lines here and here (both are a copy/paste from here). We don't necessarily NEED it as it seems libbtdht doesn't support IPv6. On the other hand it's something we WANT, so the other course of action would be to add support for it in libbtdht.

But even if we did add it, I haven't yet checked whether Travis supports IPv6, so we still may not be able to cover it with tests.

[inetic]

Just to have a complete picture: It seems the OSX Travis workers do have a support for IPv6, while Linux workers don't.

OSX:

# ifconfig
lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 16384
	options=1203<RXCSUM,TXCSUM,TXSTATUS,SW_TIMESTAMP>
	inet 127.0.0.1 netmask 0xff000000 
	inet6 ::1 prefixlen 128 
	inet6 fe80::1%lo0 prefixlen 64 scopeid 0x1 
	nd6 options=201<PERFORMNUD,DAD>
gif0: flags=8010<POINTOPOINT,MULTICAST> mtu 1280
stf0: flags=0<> mtu 1280
en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500
	options=b<RXCSUM,TXCSUM,VLAN_HWTAGGING>
	ether 00:50:56:9a:09:1b 
	inet6 fe80::401:bc6b:ccc3:99e0%en0 prefixlen 64 secured scopeid 0x4 
	inet 10.182.152.84 netmask 0xffffc000 broadcast 10.182.191.255
	nd6 options=201<PERFORMNUD,DAD>
	media: autoselect (1000baseT <full-duplex>)
	status: active
utun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> mtu 2000
	inet6 fe80::5c1f:7261:1086:5686%utun0 prefixlen 64 scopeid 0x5 
	nd6 options=201<PERFORMNUD,DAD>

Linux:

#ifconfig
eth0      Link encap:Ethernet  HWaddr 42:01:0a:0a:17:ca  
          inet addr:10.10.23.202  Bcast:10.10.23.202  Mask:255.255.255.255
          UP BROADCAST RUNNING MULTICAST  MTU:1460  Metric:1
          RX packets:11979 errors:0 dropped:0 overruns:0 frame:0
          TX packets:8618 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:190239647 (190.2 MB)  TX bytes:830041 (830.0 KB)
lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:32 errors:0 dropped:0 overruns:0 frame:0
          TX packets:32 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:18041 (18.0 KB)  TX bytes:18041 (18.0 KB)

Adding a support for IPv6 however would seem like a task in itself. Here are the courses of action I can see, @shalunov please let me know which one you prefer:

1. Leave the status quo (my preference for the MVP).
2. Remove the 6 lines mentioning IPv6.
3. Modify injector.c, injector_helper.c and test_server.c to use IPv6 when possible + leave libbtdht unchanged.
4. As above, but also modify libbtdht to support IPv6.