Add IPv6 support

[mrbesen]

This adds IPv6 support as mentioned in #39 . It works on Linux with ICMP and HTTP-Ping. (Of cause IPv4 still works)

You can enter a host by its ipv4 address (1.1.1.1), its ipv6 address (2a03:4000:2b:41f::4) or by its hostname (ipv4.mrbesen.de or ipv6.mrbesen.de). HTTP ping still works just by prepending http:// and the Device option (-I) also works.

To allow for resolving ipv6 addresses i moved from gethostbyname() to getaddrinfo(). All the code for resolving the address is in resolve.c.

I could not get it to work on Windows. I tried different ways of compiling the code for windows. Crosscompiling it with Mingw created a exe file that kinda worked with wine but straight up crashed on my win10 vm (no matter the arguments). I implemented the old gethostbyname() resolve method for windows but it did not help. I have no experience developing C-Applications on Windows and i have no idea where to start the debugging, or even how or which debugger to use on Windows.

Maybe someone more "Windows-experienced" can take a look on the windows side of this PR.

I have not added any way of forcing ipv6 or ipv4 (for example a -4 or -6 option) the only way would be to just use the plain address instead of the hostname. I think that is fine for now and would be fairly easy to implement, because getaddrinfo() allows for a hint which can force the resolver to focus on ipv4 or ipv6.

P.S: Feel free to use my server as test target (ipv4.mrbesen.de, ipv6.mrbesen.de and mrbesen.de)

[mrbesen]

Do I understand correctly that this branch doesn't work at all on Windows? Could it be the changed include (ws2tcpip.h)?

Yes, it does not work on Windows. I just tried to add the winsock2.h everywhere where i include ws2tcpip.h but it did not change anything. It crashes instantly. No matter if i choose http, icmp, ipv4 or ipv6. Starting the program as admin does not help either.

How it looks to start cnping (the window closes itself shortly after):

Without an argument it creates this screen:

But after pressing "Ping" it goes back to the gray crash and closes 1s later. There is never the error MessageBox you get from the ERRMB macro.

Maybe i just f-ed something up compiling the exe file. (All though the file seems to work with wine - at least with ICMP Ping, HTTP Ping seems to be a bit broken too) Is there a way to download the exe file from the Ci Pipeline?

[dreua]

Is there a way to download the exe file from the Ci Pipeline?

Currently no, I might convert that to GH Actions sooner or later, then yes. What happens iff you compile the current master, does that work?

[mrbesen]

I just compiled the master and it did not work (same crash). So looks like i am just not able to compile at all. (the 1.0.0 release binary works fine) Do you have any tips on how to compile the binary? I have made a simple docker container from the ubuntu:bionic image and then installed the dependencys that the Ci installs too.

sudo apt update
sudo apt-get install -y make libxinerama-dev libxext-dev libx11-dev build-essential binutils-mingw-w64-i686 gcc-mingw-w64-i686 g++-mingw-w64-i686 mesa-common-dev libglvnd-dev

And then i just compiled cnping with make cnping.exe

Nothing fancy, i just dont want all the mingw stuff on my main system.

[dreua]

I have no clue, your process sounds exactly right: As you said, that's what the CI does. I'll try to look into it and get back to you. Does an older version of cnping.exe work? I once had crashes because of missing drivers or such, especially on a VM.

Update: You mentioned that 1.0.0 works, so that sounds like some of the build dependencies had a "breaking change", doesn't it?

[mrbesen]

I have just compiled the 1.0.0 tag and it worked. So it looks like the bug is somewhere between 1.0.0 and master.

Maybe something with rawdraw? It wasnt a submodule back then (I made sure the rawdraw/ content is there when i compiled it).

Edit: at first glance it looks like this is the same bug: #83 I can try the binary on a bare metal device later.

[mrbesen]

Ok, i have now tested the binary on a bare metal windows10 and it seems to work the same as the 1.0.0 binary. Looks like something inseide rawdraw made it incompatible with my VM?

What do i mean with "the same as the 1.0.0 binary"?

• ipv4 ICMP ping: works like a charm
• ipv6 ICMP ping: not implemented -> error is shown & exit
• ipv4 HTTP Ping: kinda buggy it seems to only send a ping once every 3s and every other ping fails.
• ipv6 HTTP Ping: same as ipv4 HTTP Ping

One problem: when i use a DNS-name, that has an A-record and an AAAA-record (ipv4 and ipv6) it uses the AAAA-record and failes, because ipv6 is not implemented. The last commit fixes that.

Edit: The VM i used for testing is kvm (qemu) with windows10. This is the configuration:

sudo kvm -drive file=$device,media=disk,cache=writeback,index=0,aio=threads,format=raw -m 12G -cpu host -smp cores=8,threads=1,sockets=1 -k de -vga std -display gtk -runas $USER

[mrbesen]

I have now removed the commit where i implemented the alternative (old) resolve method for windows and the commit where i reverted that change.

I would be happy if you could merge this.

[dreua]

Hi sorry this has been on my todo list for some time now. I'd like to test it myself on Windows again but haven't found the time. I'm sure I can do that in the first half of December, would that be sufficient for you or do you need it merged faster for some reason?

[mrbesen]

No, take your time.