Match IPv4 and IPv6 addresses but NOT hostname?

Question

I want to check if a string is an IPv4 or IPv6 address, but NOTHING else. Is there any way to accomplish this using standard java libs?

I know of:

InetAddress.getByName(str) - but it accepts hostnames
IPAddressUtil.isIPv4LiteralAddress(str) - but it is an internal class and will give compiler warnings

I know I could use regular expressions, but I prefer to use existing methods.

I think we can agree that there is no standard (as in, included by default) way of accomplishing this. What I ended up doing was to run the supposed IP address through a sloppy IPv4|6 regexp (to sort out anything that does not _look_ like a valid IP address) and then call InetAddress.getByName(str) on the address. — honeyp0t, Feb 28 '12 at 07:40

score 3 · Answer 1 · answered Feb 23 '12 at 17:23

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You can use InetAddresses.forString(), from this library:

http://code.google.com/p/guava-libraries/source/browse/guava/src/com/google/common/net/InetAddresses.java

answered Feb 23 '12 at 17:23

Paul

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That looks like a really nice class. – mpontillo Feb 27 '12 at 17:30

score 1 · Answer 2 · edited May 23 '17 at 12:16

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The way to do this in C is to use inet_pton(). You could port the code to Java. (Or use some really complicated regular expressions, because matching IPv6 addresses isn't simple.)

You could take a look at the regular expression in this question and change it so it doesn't match hostnames, if you're feeling brave. ;-)

edited May 23 '17 at 12:16

Community

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answered Feb 27 '12 at 17:24

mpontillo

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score 0 · Answer 3 · answered Sep 06 '16 at 18:16

The IPAddress Java library supports both IPv4 and IPv6 in a polymorphic manner. It has methods to do what you are describing.

Here is sample code that solves your problem.

Here is more sample code:

IPAddressString ipString = new IPAddressString("ipv4 or ipv6 address string goes here");
System.out.println("IPv4: " + ipString.isIpV4() + " IPv6: " + ipString.isIpV6());

score -2 · Answer 4 · answered Feb 23 '12 at 09:04

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Simple rule of thumbs is if the address is x.x.x.x.x.x.x.x then its an IPV6 address...Try looking into the classes Inet4Address and Inet6Address as well.

answered Feb 23 '12 at 09:04

Mikematic

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Sure, but then there's short forms (skipping zeroes), loopback address, etc. – honeyp0t Feb 23 '12 at 09:23

Match IPv4 and IPv6 addresses but NOT hostname?

4 Answers4