Fixes binhex/arch-qbittorrentvpn#120

[davidgibbons]

Arch ipcalc doesn't include network anymore:
$ ipcalc 10.0.0.1 255.255.255.255
Address: 10.0.0.1 00001010.00000000.00000000.00000001
Netmask: 255.255.255.255 = 32 11111111.11111111.11111111.11111111
Wildcard: 0.0.0.0 00000000.00000000.00000000.00000000
=>
Hostroute: 10.0.0.1 00001010.00000000.00000000.00000001
Hosts/Net: 1 Class A, Private Internet

The redhat package from Aur does.

[binhex]

Rather than switching tool i think a tweak to the regex should suffice:-

ipcalc -b 10.0.0.1 255.255.255.0 | grep -P -o -m 1 "(?<=Netmask:).*" | grep -P -o -m 1 "\d{1,2}(\s+)?$"

works for me:-

[root@106f54fbed10 /]#  ipcalc -b 10.0.0.1 255.255.255.0 | grep -P -o -m 1 "(?<=Netmask:).*" | grep -P -o -m 1 "\d{1,2}(\s+)?$"
24   
[root@106f54fbed10 /]#  ipcalc -b 10.0.0.1 255.0.0.0 | grep -P -o -m 1 "(?<=Netmask:).*" | grep -P -o -m 1 "\d{1,2}(\s+)?$"
8        
[root@106f54fbed10 /]#  ipcalc -b 10.0.0.1 255.255.0.0 | grep -P -o -m 1 "(?<=Netmask:).*" | grep -P -o -m 1 "\d{1,2}(\s+)?$"
16     
[root@106f54fbed10 /]#  ipcalc -b 10.0.0.1 255.255.255.0 | grep -P -o -m 1 "(?<=Netmask:).*" | grep -P -o -m 1 "\d{1,2}(\s+)?$"
24   
[root@106f54fbed10 /]#  ipcalc -b 10.0.0.1 255.255.255.255 | grep -P -o -m 1 "(?<=Netmask:).*" | grep -P -o -m 1 "\d{1,2}(\s+)?$"
32 

[davidgibbons]

From the linked issue, it sounded like the expected output would be the Netmask and Network together, not just a bit count mask. Testing more and I'm seeing it's a more complex issue. The network line is in there -- sometimes, but not if the mask is 255.255.255.255 I wonder if that should just be checked and trigger different logic?

Could do some version of `if $dockermask == "255.255.255.255"; "${docker_ip}/32" ? As far as I can tell it's just that specific case of ipcalc not behaving the same.

[binhex]

From the linked issue, it sounded like the expected output would be the Netmask and Network together, not just a bit count mask. Testing more and I'm seeing it's a more complex issue. The network line is in there -- sometimes, but not if the mask is 255.255.255.255 I wonder if that should just be checked and trigger different logic?

Could do some version of `if d o c k e r m a s k == " 255.255 .255 .255 " ; " {docker_ip}/32" ? As far as I can tell it's just that specific case of ipcalc not behaving the same.

Yep i think you are correct, it does look like the issue is only for networks with a single host, as in /32, if that is the case (and it does look that way) then a single if statement should suffice as you suggested.

[binhex]

Something like this:-

		# convert netmask into cidr format, strip leading spaces
		if [[ "${docker_mask}" == "255.255.255.255" ]]; then
			# edge case where ipcalc does not work for networks with a single host, so we specify the cidr mask manually
			docker_network_cidr="${docker_ip}/32"
		else
			docker_network_cidr=$(ipcalc "${docker_ip}" "${docker_mask}" | grep -P -o -m 1 "(?<=Network:)\s+[^\s]+" | sed -e 's/^[[:space:]]*//')
		fi

[binhex]

Thanks for your input