Validating the Root Domain Name URL using PHP - PHP

It is highly important to validate user input on the root domain URL after they have entered it on the web form. If this is not validated, or not in the proper URL syntax as required by the Yahoo Site Explorer API, the API won't be able to process the request, or it will return inaccurate data.

The API currently accepts URLs that start with a protocol (http:// or https://) and do not end with a trailing slash. Of course the URL should also be in the correct format (domain name + '.' + TLD). Examples of TLDs (top level domain) are .com, .gov, .net, .org.

The first thing to be checked is that the domain URL field is not empty:

if (empty($domainurl)) {

//name field is blank

echo 'ERROR: The homepage URL field is empty.';

die ();

}

If the URL is not empty, we will need to validate that the user correctly entered the protocol (http:// or https://) as well as whether or not there are trailing slashes on the end:

$httpprotocol= substr($domainurl, 0, 7);

$httpprotocolwrong=substr($domainurl, 0, 8);

$httpsprotocol =substr($domainurl, 0, 8);

$httpsprotocolwrong= substr($domainurl, 0, 9);

$trailingslash = substr($domainurl, -1);

$firstdot= strpos($domainurl, '.');

$offset=$firstdot + 1;

$seconddot= strpos($domainurl,'.',$offset);

The substr function will extract the first seven characters if the protocol of the root domain is http:// or extract the first eight characters if the protocol is https://.

Also, you need to check other errors commonly made by the user when inputting domain URLs, such as http:/// or https:///.

There should only be two slashes in the protocol. These are defined via:

$httpprotocolwrong=substr($domainurl, 0, 8);

$httpsprotocolwrong= substr($domainurl, 0, 9);

The presence of a trailing slash at the end of the URL is defined by:

$trailingslash = substr($domainurl, -1);

If there are no dots in the URL, then it is considered a malformed URL, which is defined by these PHP variables:

$firstdot= strpos($domainurl, '.');

$offset=$firstdot + 1;

$seconddot= strpos($domainurl,'.',$offset);

The actual validation script for detecting allowable and correct protocols:

if (!(($httpprotocol=='http://') || ($httpsprotocol=='https://'))) {

echo 'ERROR: Root domain URL protocol should either only be http:// or https://';

die ();

}

This means that, if the user input domain URL does not contain either http:// or https://, then an error will be displayed to them so they can correct the entry.

Detecting malformed protocol such as https:/// or http:/// follows a similar concept of validation:

if (($httpprotocolwrong=='http:///') || ($httpsprotocolwrong=='https:///')) {

echo 'ERROR: Root domain URL protocol should either only be http:// or https://';

die ();

}

If the user inputs a trailing slash at the end of the URL, then an error will also display:

if ($trailingslash=='/') {

echo 'ERROR: Do not include trailing slash "/" at the end of the URL';

die ();

}

Please note that all of the validating variables used in the above validation script are first defined earlier.

To determine whether or not the domain URL is malformed (for example: http://wwwphpdeveloperorg or http://www.phpdeveloperorg), the validation line will be:

if (($firstdot=='') && ($seconddot=='')) {

echo 'ERROR: Malformed domain root URL';

die ();

}

Finally, one of the additional user input items is the options (whether to get backlinks data pointing to the entire site or just to a specific URL):

if ($options1==1) {

$options=1;

}

elseif ($options2==2) {

$options='';

}

else {

echo 'ERROR: The options field is empty.';

die ();

}

According to the Yahoo Site Explorer API guide, if the entire_site parameter is set to "1," then it will return backlinks pointing to the entire site; otherwise, if left empty "", then it will retrieve back links pointing to that specific URL only. These definitions have been included above. So if the $options1 variable value from the form is 1, assign 1 to the final $options variable (to be passed to the Yahoo inlinks API); otherwise, if it is 2, then assign it to be empty ""."

In the third part, you will learn the PHP script pertaining to the details of API communication and data analysis.