What to add to a regex IPv4 Validation to also validate CIDR IPv4?

Asked Sep 10 '19 at 12:15

Active Sep 10 '19 at 12:38

Viewed 1,247 times

I have two function in JS that check if a typed input is a valid IPv4. This is the regex that I got from @Abana Clara from this question: How to validate IP Address on multiple inputs?

var ipformat = /^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/;

I would like to add to this regex the possibility to also validate CIDR IPv4 addresses.

Please note that both of the following addresses should be valid:

192.168.1.20
192.168.1.20/24

asked Sep 10 '19 at 12:15

bleah1

1

In the linked solution, replace the colon with an escaped slash. – Wiktor Stribiżew Sep 10 '19 at 12:18
But that doesn't look like my regex. It's far from it. I only want to add to that regex, not replace my whole script. – bleah1 Sep 10 '19 at 12:28
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So add `\/[0-9]{1,3}` before `$`... – Wiktor Stribiżew Sep 10 '19 at 12:30
@WiktorStribiżew that validates `192.168.1.20/24` but invalidates `192.168.1.20` – bleah1 Sep 10 '19 at 12:36
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Then make it optional - `(?:\/[0-9]{1,3})?`. – Wiktor Stribiżew Sep 10 '19 at 12:38
@WiktorStribiżew And do you know where to place 32 inside that thing so that 32 be the max value ? – bleah1 Sep 10 '19 at 12:41
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Use http://gamon.webfactional.com/regexnumericrangegenerator/ to get such patterns. If you want 0 to 32, `(?:\/(?:[0-9]|[12][0-9]|3[0-2]))?`. – Wiktor Stribiżew Sep 10 '19 at 12:43
@WiktorStribiżew Thank you very much. I have done it like this: `(?:\/([0-9]|[1-2][0-9]|3[0-2]))?` – bleah1 Sep 10 '19 at 12:46
Yeah, a tiny overhead won't hurt here. – Wiktor Stribiżew Sep 10 '19 at 12:47
@WiktorStribiżew I hoped that you understood how bad I am at this. I don't know what is the overhead, how does it look, where to put or why. – bleah1 Sep 10 '19 at 12:55
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Please check https://stackoverflow.com/questions/31500422/are-non-capturing-groups-redundant – Wiktor Stribiżew Sep 10 '19 at 12:56

What to add to a regex IPv4 Validation to also validate CIDR IPv4?

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