Regex matching PMG 7.3

[xazer]

Hello,

since nobody in the German sub seemed to know the answer to this I'll try again here. In my installation I have several regexes for filtering mails from sketchy or untrustworthy toplevel domains like .lol.
Since the update 7.3-7 none of the regexes seems to match any domain. Here is my regex for the mentioned example .lol

.*([0-9a-z|-]+\.)[0-9a-z|-]+\.(lol)+

Mails from the domain lockermaster.lol were delivered to the users despite this rule. (screenshot)

 

[sterzy]

The regex you posted demands at least one subdomain. So “lockermaster.lol” does not match this regex, but “a.lockermaster.lol” does. Also note that .* at the beginning can make this regex very inefficient.

Small break down of the regex:

• .*: match any character as often as possible. This leads to back-tracking making the regex inefficient.
• ([0-9a-z|-]+\.): capturing group one, match any of the characters between “0” and “9”, “a” and “z”, as well as “|” and “-” one or more times and then a period. This requires a subdomain.
• [0-9a-z|-]+\.: match the same stuff again one or more times followed by a period. This would match the main domain.
• (lol)+ capture group two, match the string “lol” one or more times. This would then match the TLD “lol”, but also “lollol” and “lollollol” and so on.

If all you want to do is match every “.lol” TLD, you could try \.lol$. This would demand that at the end of the string “.lol” occurs.

You can use websites such as Regex 101 [1] to gain a better understand of how regexes work.

[1]: https://regex101.com/

 

[xazer]

Hi sterzy,

the

.*

at the beginning was suggested by another user here some time ago.

I personaly prefer regexr.com for Testing but I'm getting the feeling that pmg does not evaluate regexes the same way as other applications.

Your suggestion

\.lol$

does not match "lockermaster.lol" according to pmg.

 

[sterzy]

Ah, I see this particular regex is automatically anchored. Then yeah, you'll need to use this one instead .*\.lol, which will be anchored and become this regex ^.*\.lol$. So it will match the beginning of a line (“^”), then any character zero or more times (“.*”), then the string “.lol” and then the end of line (“$”). This should still match anything ending in “.lol” and be more efficient than your original regex for cases such as “a.lockermaster.lol.lol” (12 vs. 49 steps).