Simple Java regex to extract IP address and port from enclosing string

Question

Consider a pair of IPv4 or IPv6 address and port, separated by either / or :, e.g.

10.10.10.10:1234

The port is optional, so strings like

10.10.10.10/
10.10.10.10:
10.10.10.10

are also valid. The address/port pair may be followed by space or comma characters and it is part of a much longer enclosing string.

What would be a very simple regex to extract the 2 values in separate fields from the enclosing string (without using String manipulation functions)?

For example, an expression like

(?<address>[^\s,]+[^\s,:\.])((/|:)(?<port>\d*))?

extracts both address and port in the same string.

The goal here is to achieve extraction with the simplest possible regex, even if it is not 100% accurate (i.e., even if it matches other strings as well).

If it's not a problem if it is simple and long, check this (no port but can be appended) stackoverflow.com/questions/23483855/… — uraimo
– uraimo, Commented Apr 20, 2015 at 20:11
I have seen many such regular expressions, but looking for a simple one. :-) — PNS
– PNS, Commented Apr 20, 2015 at 20:24

Ace McCloud · Accepted Answer · 2015-04-20 20:17:06Z

2

([0-9.]*)(\/|:)([0-9]*)

Here is the regex . First group gives you IP. Third group gives you the Port number. Middle group gives separator i.e / or : used for alternation. It can be ignored.

edited Apr 20, 2015 at 20:17

answered Apr 20, 2015 at 20:10

Ace McCloud

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7 Comments

PNS Over a year ago

It works fine for IPv4 but does not cover IPv6. Thanks and +1.

Ace McCloud Over a year ago

could you give me a sample for IPv6 address ?

PNS Over a year ago

IPV6 addresses contain numbers [0-9], letters [A-F] and : symbols, e.g. 1234:ab8:46a3::2a8e:567:1234 is an IPv6 address.

Ace McCloud Over a year ago

okay. is the number of colons : fixed before the port number colon ?i.e 4 ?

PNS Over a year ago

No, it can be any number, from 0 to quite a few and you can never know how many exactly.

|

hd1 · Accepted Answer · 2015-04-20 20:09:05Z

1

Use commons validator:

InetAddressValidator validator = InetAddressValidator.getInstance();
if (validator.isValid(ipAddress) {
   // cool, isn't valid
}
throw new InvalidAddressException(ipAddress);

answered Apr 20, 2015 at 20:09

hd1

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2 Comments

hd1 Over a year ago

Regular expressions are not the way to go here, PNS.

PNS Over a year ago

They are the only way. The address/port pair is extracted from a long string, as I say in the question, and that long string also has other fields that nee to be extracted. So, the regular expression I asked for will be part of a much longer one.

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