[Phpwm] Simple PHP Contact Form

[Pete Graham]

I'd only found out about the filter_var function recently. I curious
if general consensus is to now use this for validation instead of
regular expressions. Below is the function that I use for email
validation:

function _email($email) {
	if (preg_match ( '/^\w[-.\w]*@(\w[-._\w]*\.[a-zA-Z]{2,}.*)$/',
$email, $matches )) {
		if (function_exists ( 'checkdnsrr' )) {
			if (checkdnsrr ( $matches [1] . '.', 'MX' ))
			return true; // If a 'mail exchange' record exists
			if (checkdnsrr ( $matches [1] . '.', 'A' ))
			return true; // Mail servers can fall back on 'A' records
		}
		else {
			return true; // For Windows
		}
	}
	return false;
}

Would I be better off swapping the regular expression for this:
filter_var($email, FILTER_VALIDATE_EMAIL)
If so should what would then be the best method to get the host name
for the dns check, or is the dns check overkill?

Thanks,
Pete

2009/10/14 Alex Mace <alex at hollytree.co.uk>:
> I think the point was there is no point writing and maintaining a
> regex for email address validation when PHP's built in filter
> functions have an email address checker will validate email addresses
> correctly against the spec.
>
> Alex
>
> On 14 Oct 2009, at 09:35, <phil at infolinkelectronics.co.uk> <phil at infolinkelectronics.co.uk
>  > wrote:
>
>>
>>
>> Regards,
>>
>> Phil Beynon
>> Sales & Operations Director
>>
>> ** Infolink Electronic Systems Ltd.
>> ** S/W Birmingham's Longest Established ISV & VAR
>> ** http://www.infolinkelectronics.co.uk
>> ** Professional Web 2.0 Design & Advanced Hosting Platforms
>> ** http://www.coeus-computica.co.uk
>> ** Affordable Knowledgebase Solutions
>> ** Contact: Sales at infolinkelectronics.co.uk
>> ** Tel / Fax 0121 441 3558
>>
>>
>>>> if (!eregi ("^([a-z0-9_]|\\-|\\.)+@(([a-z0-9_]|\\-)+\\.)+[a-z]
>>>> {2,4}$",
>>>> $emaila)) error_alert("Invalid Email Address");
>>>
>>> My understanding is that there are a million and one regexps to
>>> validate email addresses and it'd not the right one unless it is
>>> very,
>>> very long.
>>>
>>> Yours will fail on eg adresses which look like foo.o'reilly at ....
>>> (valid) or foo+bar at ... (valid).
>>
>> Apostrophes in teh first part are also likely to break other things
>> as they
>> can be seen as a delimiter. Many ISPs thus limit their use.
>>
>>> And it allows an _ in a domain name which isn't possible. I think
>>> there are also tlds longer than 4 characters.
>>
>> Yup there can be trade offs, it will fail on say .museum addresses,
>> however
>> the only real way to do that is look up the tld against a definitive
>> list
>> It has to be said when I wrote the code originally I doubt many > 3
>> char
>> TLDs actually did exist! :-)
>>
>>> And ereg is deprecated, as has already been pointed out. Use
>>> preg_match
>>
>> I only actually got that pointed out to me last night by Alex :-)
>>
>>> You'd have made the regexp easier to write in ' rather than " -
>>> avoiding \\ escaping blah blah too i think.
>>
>> Yes but if I had made it perfect as per RFC 2822 it would have
>> looked like;
>>
>> (?:[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\.[a-z0-9!#$%&'*+/=?^_`{|}~-]
>> +)*|"(?:[\x01
>> -\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\x7f]|\\[\x01-\x09\x0b\x0c
>> \x0e-\x7f]
>> )*")@(?:(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\.)+[a-z0-9](?:[a-
>> z0-9-]*[a-z0-9])
>> ?|\[(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|
>> 2[0-4][0-9]|
>> [01]?[0-9][0-9]?|[a-z0-9-]*[a-z0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f
>> \x21-\x5a\
>> x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])
>>
>> So yes mine is a lot shorter and is a compromise in some respects -
>> but it
>> pretty much works in real world environments!
>>
>>> Sorry if I sound bitchy,
>>
>> Dont worry about it.
>>
>> Phil
>> <Phil Beynon.vcf>_______________________________________________
>> Phpwm mailing list
>> Website : http://www.phpwm.org
>> Twitter : http://www.twitter.com/phpwm
>> Facebook: http://www.facebook.com/group.php?gid=2361609907
>>
>> Post to list: Phpwm at mailman.lug.org.uk
>> Archive etc : https://mailman.lug.org.uk/mailman/listinfo/phpwm
>
>
> _______________________________________________
> Phpwm mailing list
> Website : http://www.phpwm.org
> Twitter : http://www.twitter.com/phpwm
> Facebook: http://www.facebook.com/group.php?gid=2361609907
>
> Post to list: Phpwm at mailman.lug.org.uk
> Archive etc : https://mailman.lug.org.uk/mailman/listinfo/phpwm
>