On Jan 8, 2011, at 12:09 PM, Ashley Sheridan wrote:
> On Sat, 2011-01-08 at 16:55 +0800, WalkinRaven wrote:
>
>> PHP 5.3 PCRE
>>
>> Regular Express to match domain names format according to RFC 1034 -
>> DOMAIN NAMES - CONCEPTS AND FACILITIES
>>
>> /^
>> (
>> [a-z] |
>> [a-z] (?:[a-z]|[0-9]) |
>> [a-z] (?:[a-z]|[0-9]|\-){1,61} (?:[a-z]|[0-9]) ) # One label
>>
>> (?:\.(?1))*+ # More labels
>> \.? # Root domain name
>> $/iDx
>>
>> This rule matches only <label> and <label>. but not <label>.<label>...
>>
>> I don't know what wrong with it.
>>
>> Thank you.
>>
>
>
>
> I think trying to do all of this in one regex will prove more trouble
> than it's worth. Maybe breaking it down into something like this:
>
> <?php
> $domain = "www.ashleysheridan.co.uk";
> $valid = false;
>
> $tlds = array('aero', 'asia', 'biz', 'cat', 'com', 'coop', 'edu', 'gov',
> 'info', 'int', 'jobs', 'mil', 'mobi', 'museum', 'name', 'net', 'org',
> 'pro', 'tel', 'travel', 'xxx', 'ac', 'ad', 'ae', 'af', 'ag', 'ai', 'al',
> 'am', 'an', 'ao', 'aq', 'ar', 'as', 'at', 'au', 'aw', 'ax', 'az', 'ba',
> 'bb', 'bd', 'be', 'bf', 'bg', 'bh', 'bi', 'bj', 'bm', 'bn', 'bo', 'br',
> 'bs', 'bt', 'bv', 'bw', 'by', 'bz', 'ca', 'cc', 'cd', 'cf', 'cg', 'ch',
> 'ci', 'ck', 'cl', 'cm', 'cn', 'co', 'cr', 'cu', 'cv', 'cx', 'cy', 'cz',
> 'de', 'dj', 'dk', 'dm', 'do', 'dz', 'ec', 'ee', 'eg', 'er', 'es', 'et',
> 'eu', 'fi', 'fj', 'fk', 'fm', 'fo', 'fr', 'ga', 'gb', 'gd', 'ge', 'gf',
> 'gg', 'gh', 'gi', 'gl', 'gm', 'gn', 'gp', 'gq', 'gr', 'gs', 'gt', 'gu',
> 'gw', 'gy', 'hk', 'hm', 'hn', 'hr', 'ht', 'hu', 'id', 'ie', 'il', 'im',
> 'in', 'io', 'iq', 'ir', 'is', 'it', 'je', 'jm', 'jo', 'jp', 'ke', 'kg',
> 'kh', 'ki', 'km', 'kn', 'kp', 'kr', 'kw', 'ky', 'kz', 'la', 'lb', 'lc',
> 'li', 'lk', 'lr', 'ls', 'lt', 'lu', 'lv', 'ly', 'ma', 'mc', 'md', 'me',
> 'mg', 'mh', 'mk', 'ml', 'mm', 'mn', 'mo', 'mp', 'mq', 'mr', 'ms', 'mt',
> 'mu', 'mv', 'mw', 'mx', 'my', 'mz', 'na', 'nc', 'ne', 'nf', 'ng', 'ni',
> 'nl', 'no', 'np', 'nr', 'nu', 'nz', 'om', 'pa', 'pe', 'pf', 'pg', 'ph',
> 'pk', 'pl', 'pm', 'pn', 'pr', 'ps', 'pt', 'pw', 'py', 'qa', 're', 'ro',
> 'rs', 'ru', 'rw', 'sa', 'sb', 'sc', 'sd', 'se', 'sg', 'sh', 'si', 'sj',
> 'sk', 'sl', 'sm', 'sn', 'so', 'sr', 'st', 'su', 'sv', 'sy', 'sz', 'tc',
> 'td', 'tf', 'tg', 'th', 'tj', 'tk', 'tl', 'tm', 'tn', 'to', 'tp', 'tr',
> 'tt', 'tv', 'tw', 'tz', 'ua', 'ug', 'uk', 'us', 'uy', 'uz', 'va', 'vc',
> 've', 'vg', 'vi', 'vn', 'vu', 'wf', 'ws', 'ye', 'yt', 'za', 'zm',
> 'zw', );
>
>
> if(strlen($domain <= 253))
> {
> $labels = explode('.', $domain);
> if(in_array($labels[count($labels)-1], $tlds))
> {
> for($i=0; $i<count($labels) -1; $i++)
> {
> if(strlen($labels[$i]) <= 63 && (!preg_match('/^[a-z0-9][a-z0-9
> \-]*?[a-z0-9]$/', $labels[$i]) || preg_match('/^[0-9]+$/',
> $labels[$i]) ))
> {
> $valid = false;
> break; // no point continuing if one label is wrong
> }
> else
> {
> $valid = true;
> }
> }
> }
> }
>
> var_dump($valid);
>
>
> This matches the last label with a TLD, and each label thereafter
> against the standard a-z0-9 and hyphen rule as indicated in the
> preferred characters allowed in a label (LDH rule), with the start and
> end character in a label isn't a hyphen (oddly enough it doesn't mention
> starting with a digit!)
>
> Also, each label is checked to ensure it doesn't run over 63 characters,
> and the whole thing isn't over 253 characters. Lastly, each label is
> checked to ensure it doesn't completely consist of digits.
>
> I've tested it only with my domain so far, but it should work fairly
> well. As I said before, I couldn't think of a way to do it all with one
> regex. It could probably be done, but would you really want to create a
> huge and difficult to read/understand expression just because it's
> possible?
Ash
I doubt its possible since the ccTLD's have valid 3 and more dotted domain names. You should see .us And .uk doesn't follow the ccTLS rules for .tk for example.
Now, if the purpose is to write a regex for a host name then that's a different story.
Tom
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