Regexp Warlocks

[JohnOne]

I'm shamelessly just asking this without even trying, because I'm just pathetic at doing regex. Plus I know some of the magicians here enjoy the challenge. Plus I could not find what I need after a web search.

What I'm after is a regexp pattern to validate a LAN IP address, which I believe can be...

10.0.0.0        -   10.255.255.255
172.16.0.0      -   172.31.255.255
192.168.0.0     -   192.168.255.255

My thoughts are that there would probably have to be three at least, or possibly more pattern passes to validate that an IP is within one of the above bounds.

So if it interests you, great, and if it annoys you then feel free to give me a piece of your mind, and thanks for looking in all the same.

 

[JohnOne]

"Regexp Warlocks" I find that a bit of a tongue twister. I keep saying "Regex pworlocks".

[BrewManNH]

RegEx is terrible for valid IP addresses. Try this one, totally non-regex, modify as you need to. It just looks at the IP address you send to it and check to make sure it's valid. You can do further checks on the returned information to verify that it's within the ranges you need it to be.

[JohnOne]

That's what I always do, just do a little dance around regex.

Cheers.

[jchd]

So let's try dancing:

Local $aIPs = [ _
    "10.0.0.0", "10.1.2.3", "10.255.255.255", _
    "172.16.0.0", "172.25.1.2.3", "172.31.255.255", _
    "192.168.0.0", "192.168.1.2", "192.168.255.255", _
    "12.34.56.78", "123.456.789.0", "192.168.0.555" _
]

For $MyIP In $aIPs
    ConsoleWrite($MyIP & " is a" & (_Valid_LAN_IP($MyIP) ? " " : "n in") & "valid LAN IP address" & @LF)
Next

Func _Valid_LAN_IP($ip)
    Return StringRegExp($ip, _
                                "(?x) (?(DEFINE) (?<byte> 2[0-4]\d | 25[0-5] | 1\d\d | [1-9]?\d) )" & _
                                " ^ (" & _
                                "      10 (\.(?&byte)){3} | " & _
                                "      172 \. ( 1 [6-9] | 2\d | 3[01] ) (\.(?&byte)){2} | " & _
                                "      192 \. 168 (\.(?&byte)){2} | " & _
                                ") $")
EndFunc

 

[JohnOne]

It works!

[JohnOne]

Brilliant that jchd.

Thanks.

If aliens visited our planet and thought our language was RegEx, I think they'd just go home without even trying to say hello.

[jchd]

I'm not so sure: RegExps have a very precise semantics (despite a rather cryptic syntax), contrary to human spoken/writen languages which all have a fuzzy multi-level semantics and a fairly complex and often distorded syntax. Basic example: "The horse is out of the barn". This can refer to a bacteria, virus, bug or invasive plant, some news (true fact or made up rumor), a computer worm, a groundshaking secret that should never have been revealed, the launch of some marketting campaign, mission Apollo 38, an actual horse, ...

It would be pretty simple to convert PCRE syntax into a series of function calls and simple structures, both comparable to, say, AutoIt.

BTW, the (?x) option at the start of the regexp allows subsequent unsignificant whitespaces, only to ease reading the thing.

Also the use of an internal subroutine (named byte) is handy in this use case to avoid duplication of long patterns.

[JohnOne]

I just go blank when I look at patterns, with a real dumbstruck and stupefied look on my face, much like when someone hands me one those fancy smart phones.

It's not through laziness, or being stupid, It's real and I cannot control it. Proper weird like a shrink would have a field day with me about it.

And they make me sleepy.

[jchd]

I've recorded a slightly different version as https://regex101.com/r/rU1iI6/1 This one scans a series of lines with IPs and select the valid LAN ones (use option 3 then to obtain the resulting array).

Paste the regexp in the "tester" page and read the "explanation" text. You'll certainly agree that this text reads like pseudo-code (it is, in fact) which one can obviously translate into an ad hoc set of function calls and simple block constructs.

Granted creating correct complex regexps requires a little bit of "regexp thinking" due to the particular way matching attempts work. It always helps translate the regexp goal into plain english in the "explanation" box style, then convert that into PCRE syntax. Some advanced features require good experience but this isn't breaking news. Very few AutoIt noobs don't start coding for a complex 5-GUI app using custom skin and requiring hooking dozens of cryptic Windows messages.