Support for IPv6 (1/x)

[khorben]

This group of commits of a series attempting to bring IPv6 support to fwknop (see #1). It notably allows IPv6 communication over TCP or UDP, with or without PCAP, for both the server and the client. At this stage, only IPv4 firewalling rules can be applied.
This currently requires SOURCE ANY to be set in the configuration.

[khorben]

You can find additional patches in the khorben/ipv6 branch here. It is my staging branch so the changes may be more intrusive while I rework them, but feel free to review and consider them for inclusion if you find them good enough.

[mrash]

Many thanks. I’ll provide feedback by tomorrow night.

[mrash]

Thanks for starting the IPv6 integration. Looks like you have focused on the changes necessary on the ipv6-server branch to start accepting incoming SPA packets via IPv6. As you noted somewhere, this does not change the SPA packet format, but more about the mechanics of acquiring the packet data. Have you also started looking at what would be required to encode IPv6 addresses within the SPA packets themselves? I.e. changing the access request field for example?

I think it would be a good idea to also start bootstrapping the test suite to handle IPv6. At least, I have found this to be a good way to work on major features. Maybe what I should do is start helping with the test suite in this regard.

[khorben]

That's right, with this branch SPA packets can be received via IPv6. I saw that IPv4 addresses are base64-encoded in there, so I think it will be possible to use the regular IPv6 notation there (abc::123.port etc) and simply check for valid IPv4 or IPv6 information there - therefore not affecting compatibility with older IPv4-only services.
Indeed I had a look at the test suite, but it did not work for me on NetBSD. I have setup a Linux VM to test there instead though.

[khorben]

On master:

    Tests excluded (see output/tests.excluded): 243

[+] 9/0/9 Fuzzing tests passed/failed/executed
[+] 719/12/731 test buckets passed/failed/executed

On khorben/ipv6-server:

    Tests excluded (see output/tests.excluded): 243

[+] 9/0/9 Fuzzing tests passed/failed/executed
[+] 689/42/731 test buckets passed/failed/executed

Also, the IPv6 tests took much more time, but I ran them first and had activity in other VMs, so it is not necessarily reflecting performance degradation.

[khorben]

I just (rebased on master and) added commit 8d0fb60 to fix an issue when parsing the response of the external IP resolver. This should also support IPv6 already, would it be added to the server in the future.

[khorben]

See #285 for feature-complete IPv6 support on the client and server sides.