preg_match() regex to validate URL

[deko]

As I understand it, the characters that make up an Internet domain name can
consist of only alpha-numeric characters and a hyphen
(http://tools.ietf.org/html/rfc3696)

So I'm trying to write regex that will provide a basic url format validation:

starts with http or https (the only 2 prots I'm interested in), is followed by
'://', then ([any alpha-numeric or hyphen] followed by a '.' appearing 1 or more
times), then followed by anything *, and is case-insensitive.

I tried this:

if (preg_match('/^(http|https):\/\/([a-z0-9-]\.+)*/i', $urlString))
{
$valid == true;
}
else
{
$valid == false;
}

but no luck.

Any suggestions welcome...

Thanks in advance.

[Rik]

Re: preg_match() regex to validate URL

deko wrote:

Deko, while you enthusiasm is appreciated, please stay in the same thread
when making a post about the same subject. Starting several threads not
only creates confusion about answers already given and context, it also
gives off the feeling of being very pushy.

As I understand it, the characters that make up an Internet domain name
can consist of only alpha-numeric characters and a hyphen
(http://tools.ietf.org/html/rfc3696)

...."Any characters, or combination of bits (as octets), are permitted in
DNS names. However, there is a preferred form that is required by most
applications.". ....

So I'm trying to write regex that will provide a basic url format
validation:
>
starts with http or https (the only 2 prots I'm interested in), is
followed by '://', then ([any alpha-numeric or hyphen] followed by a '.'
appearing 1 or more times), then followed by anything *, and is
case-insensitive.
>
I tried this:
>
if (preg_match('/^(http|https):\/\/([a-z0-9-]\.+)*/i', $urlString))

This bit "([a-z0-9-]\.+)" does not do what you think it does, it matches
_one_ single character in the [a-z0-9-]-range, followed by at least one,
but an arbitrary amount of literal dots. And that repeated zero or more
times.. So 'http://a.b.c.d......d. .e....a......' would match.

Further more, you seem to have anchorder this with ^, so it will only
match if http(s):// is at the very beginning of the string. Is that whatr
you want?

'/^https?:\/\/[a-z0-9-]+(\.[a-z0-9-]+)+/i'

--
Rik Wasmus

[deko]

Re: preg_match() regex to validate URL

>As I understand it, the characters that make up an Internet domain name can

>consist of only alpha-numeric characters and a hyphen
>(http://tools.ietf.org/html/rfc3696)

..."Any characters, or combination of bits (as octets), are permitted in DNS
names. However, there is a preferred form that is required by most
applications.". ....

I just tried registering various domain names with an underscore. The
registrar's system rejected it. While this may not be the best verification, I
have yet to see a valid Internet domain with an underscore or any other
non-alphanumeric character (other than a hyphen).

'/^https?:\/\/[a-z0-9-]+(\.[a-z0-9-]+)+/i'

Thanks, Rik

[Rik]

Re: preg_match() regex to validate URL

On Mon, 12 Feb 2007 10:29:26 +0100, deko <deko@nospam.co mwrote:

>>As I understand it, the characters that make up an Internet domain
>>name can consist of only alpha-numeric characters and a hyphen
>>(http://tools.ietf.org/html/rfc3696)

>..."Any characters, or combination of bits (as octets), are permitted
>in DNS names. However, there is a preferred form that is required by
>most applications.". ....

>
I just tried registering various domain names with an underscore. The
registrar's system rejected it. While this may not be the best
verification, I have yet to see a valid Internet domain with an
underscore or any other non-alphanumeric character (other than a hyphen).

There are efforts to fully internationalis e DNS entries, so even non-roman
based character sets are allowed. See for instance
<http://www.ietf.org/rfc/rfc4185.txt>. We're not there yet by a long shot,
but there's no doubt it will happen.

--
Rik Wasmus

[deko]

Re: preg_match() regex to validate URL

>>>As I understand it, the characters that make up an Internet domain name

>>>can consist of only alpha-numeric characters and a hyphen
>>>(http://tools.ietf.org/html/rfc3696)
>>..."Any characters, or combination of bits (as octets), are permitted in
>>DNS names. However, there is a preferred form that is required by most
>>applications. ".....

>>
>I just tried registering various domain names with an underscore. The
>registrar's system rejected it. While this may not be the best
>verification , I have yet to see a valid Internet domain with an underscore
>or any other non-alphanumeric character (other than a hyphen).

>
There are efforts to fully internationalis e DNS entries, so even non-roman
based character sets are allowed. See for instance
<http://www.ietf.org/rfc/rfc4185.txt>. We're not there yet by a long shot,
but there's no doubt it will happen.

Eventually, I'm sure.

Getting back to my regex question, I wonder if it would be better to check for
illegal characters:

if
(preg_match('/(`|~|!|@|#|$|%| ^|&|*|(|\)|_|\+ |=|\[|\{|\]|\}|\||;|\:|\'| \"|\<|\>|\?| )/',
$url_a['host'])) ???

I'm not having much luck catching invalid hostnames otherwise...

[Toby A Inkster]

Re: preg_match() regex to validate URL

Rik wrote:

There are efforts to fully internationalis e DNS entries, so even non-roman
based character sets are allowed. See for instance
<http://www.ietf.org/rfc/rfc4185.txt>. We're not there yet by a long shot,
but there's no doubt it will happen.

Not there yet?!

Try telling that to "www.한글.kr" !

--
Toby A Inkster BSc (Hons) ARCS
Contact Me ~ http://tobyinkster.co.uk/contact
Geek of ~ HTML/SQL/Perl/PHP/Python*/Apache/Linux

* = I'm getting there!

[Michael Fesser]

Re: preg_match() regex to validate URL

..oO(Rik)

>'/^https?:\/\/[a-z0-9-]+(\.[a-z0-9-]+)+/i'

With another delimiter you could avoid the escaping of slashes and make
the regexp a bit more readable (IMHO):

'#^https?://[a-z0-9-]+(\.[a-z0-9-]+)+#i'

Just my 2 cents.

Micha

[Rik]

Re: preg_match() regex to validate URL

On Mon, 12 Feb 2007 16:39:24 +0100, Toby A Inkster
<usenet200702@t obyinkster.co.u kwrote:

Rik wrote:
>

>There are efforts to fully internationalis e DNS entries, so even
>non-roman
>based character sets are allowed. See for instance
><http://www.ietf.org/rfc/rfc4185.txt>. We're not there yet by a long
>shot,
>but there's no doubt it will happen.

>
Not there yet?!
>
Try telling that to "www.한글.kr" !

Yup, works. Isn't understood by a lot of programs though, most browsers
will handle it just fine, but browsing is not the only thing we want to
use it for.

Simple example: I cannot ping this with ease in my Windows version...
--
Rik Wasmus

[deko]

Re: preg_match() regex to validate URL

>>'/^https?:\/\/[a-z0-9-]+(\.[a-z0-9-]+)+/i'

>
With another delimiter you could avoid the escaping of slashes and make
the regexp a bit more readable (IMHO):
>
'#^https?://[a-z0-9-]+(\.[a-z0-9-]+)+#i'

Thanks for the tip.

I recently found this: http://baseclass.modulweb.dk/urlvali...viewsource.php

which looks interesting, if not overkill.

[Toby A Inkster]

Re: preg_match() regex to validate URL

Rik wrote:

Yup, works. Isn't understood by a lot of programs though, most browsers
will handle it just fine, but browsing is not the only thing we want to
use it for.
>
Simple example: I cannot ping this with ease in my Windows version...

There are IDN-enabled versions of ping available, but few if any operating
systems ship with them as standard yet.

Though the hope is that operating systems will integrate IDN support
directly into their own gethostbyname() type functions, so there is no
need to explicitly compile IDN support into all software that uses domain
names.

(On the other hand, many software has to parse URLs too, in which case
they'd probably need to update their URL-parsing code to cope with IDN.)

libidn exists, which makes it really easy to drop in support for
internationalis ed domain names into existing network apps. It's LGPL too,
which even makes it available for use by closed-source software.

--
Toby A Inkster BSc (Hons) ARCS
Contact Me ~ http://tobyinkster.co.uk/contact
Geek of ~ HTML/SQL/Perl/PHP/Python*/Apache/Linux

* = I'm getting there!