Fix WSL2 static IP always (test full IP string, not only begin)

[ocroz]

The script does not update the IP if starting with correct string.

Expected IP: 192.168.50.2
Current IP: 192.168.50.205

In this case, the script does not update the IP as expected.

[wikiped]

Thanks for trying to solve this.

I am not sure I understand under what conditions capturing trailing slash would help better in checking for expected IP address:

> ip_addr=172.16.0.2
> echo 172.16.0.2/24 | grep -F "$ip_addr"
172.16.0.2
> 
> echo 192.168.0.2/24 | grep -F "$ip_addr"
> 

vs:

> echo 172.16.0.2/24 | grep -qF "$ip_addr/"
172.16.0.2/
> 
> echo 192.168.0.2/24 | grep -F "$ip_addr/"
> 

[ocroz]

After shutdown, wsl assigns a new IP within the selected Subnet.

Say the subnet is 192.168.50.1/24 on Windows side, wsl assigns any IP from 192.168.50.2 to 192.168.50.255.

The problem is when the assigned IP starts with the expected IP stored in /etc/wsl.conf

# Get current assigned IP
$ dev=eth0
$ ip addr show dev $dev | grep -Po "inet \K[\d\./]+" 2>/dev/null
192.168.50.205/24

# Get expected IP
$ grep static_ip /etc/wsl.conf
static_ip = 192.168.50.2

# Success
$ ip_addr=192.168.50.2
$ echo 192.168.50.105/24 | grep -F "$ip_addr" # Remove -q

# Failure
$ ip_addr=192.168.50.2
$ echo 192.168.50.205/24 | grep -F "$ip_addr" # Remove -q
192.168.50.205/24

The current algorithm bugs when assigned IP starts with expected IP.

[ocroz]

PS: This module is unusable until you fix this issue.

If to have proper DNS nameserver, we need to wsl --shutdown (see #4 which you closed without fixing it).

Then we are facing this annoying problem where wsl2 machine is not configured with its expected IP half of the times (see #7).

[wikiped]

Thanks for spotting this partial match bug, it has been fixed in Version 0.7.0 using slightly different approach.