[Resolved] Verifying URL before displaying link

[sebconn]

Hi there I've got a basic script for a school that will list all the students in the school and provide links to their online portfolios.

I've got all the displaying and links all set up but I want to set it up so that a link will only be displayed if the student has in fact uploaded a portfolio, just a basic true false function would be fine. This would normally be perfectly easy but the students portfolios are on a remote server.

So what's the best function to use to verify a URL?

for example I guess it would look something like this:

<?php

//just pretend all the mysql stuff is here and everything is hunky dory

while($row = mysql_fetch_array($query)) {
if(whateverfunction(href=http://www.moriacps.vic.edu.au/home/$row[user_name])=true)
{
echo "<b><a href=http://www.moriacps.vic.edu.au/home/$row[user_name]>$row[first_name] $row[last_name] </a><a href=http://www.moriacps.vic.edu.au/home/$row[user_name]><img src=images/viewport.gif border=0></a><BR><BR>";
}else{
echo "$row[first_name] $row[last_name] Has no portfolio";
}
};
php?>

so what would be the best function to use in that situation?

[Weedpacket]

You could have your script try to request the portfolio itself (with fsockopen(), or fopen() and $http_response, or ) and see if you get a valid (200 OK) reponse.

Of course, that won't tell you the URL is correct; that would need someone to read it; it will tell you if the URL points to a valid resource, though.

[sebconn]

I tried the fopen() function in the following small test out script with a URL I know exists but it still returns false, why would It be doing that, do I need to add any other strings to the fopen() function?

<?php
$exists = "fopen('http://www.moriacps.vic.edu.au/home/jorgiaa/index.html','r')";
if($exists='FALSE')
{
echo "NOPE";
}else{
echo "YEP";
};

php?>

[drawmack]

	function isURL($Value) {
    $parsed = parse_url($Value);
    if($parsed['scheme'] != 'http' || $parsed['host'] == '') {
		  $parsed['scheme'] = 'http';
			$parsed['host'] = BASEURL;
		}
    elseif(!checkdnsrr($parsed['host'],'A')) {return 0;}

$fp = fsockopen ($parsed['host'], 80);
fputs($fp,"GET $Value HTTP/1.0\n\n");
$line = fgets($fp, 1024);
if (stristr($line, '200 OK')) {$end = 1;}
else{$end = 0;}
fclose($fp);
return $end;
} //end isURL

[sebconn]

please excuse my stupidity but...

buh?

that's slightly out of my area of n00biness

can you please explain what's going on with that code? I assume that $value is the URL it will be checking.

now I feel dopey

[Weedpacket]

More like this:

<?php
$exists = @fopen('http://www.moriacps.vic.edu.au/home/jorgiaa/index.html','r');
if($exists==false)
{
echo "NOPE";
}else{
echo "YEP";
}

?>

The @ is to stop PHP whingeing when it can't find a file that doesn't exist.

[Weedpacket]

Originally posted by sebconn
can you please explain what's going on with that code?

The first chunk (up to the elseif) is checking to see if $Value really is a proper-looking [url]http://[/url] URL (and not some random garbage someone thought it would be funny to try).

The line that starts with 'elseif' looks up the host specified in the URL to see that there really is a machine out there that answers to that name.

The bit down to and including fclose() opens a connection to the host and sends it an http request for the document the URL specifies, then looks at the response to see if it's 200 OK.

All in all, it returns true (or, rather, 1) if the URL is valid, and false (or 0) if it isn't.

[sebconn]

Hmm that first more simple code is coming up with the same thing as before, no matter what URL I put in the fopen area it returns false, does this mean I don't have the property "allow_url_fopen" set in my PHP.ini file? if that's the case I'm in trouble because I can't edit my PHP.ini file with my webhosting service.

[sebconn]

any other methods available? I just seems so simple it's driving me mad.

[drawmack]

yeah there's the method I posted, but it will return false on redirects look up the http specs if you want to make it a little more lienient

[sebconn]

so how would I implement that created function?

[drawmack]

sub,
it's a copy and paste function. just call it with the string you wish to validate.

[sebconn]

Ok I've tried using the functions and calling it, but it still returns 0 when I know that the address exists

here's the code to see if I've made any mistakes:

<?php

function isURL($Value) { 
    $parsed = parse_url($Value); 
    if($parsed['scheme'] != 'http' || $parsed['host'] == '') { 
          $parsed['scheme'] = 'http'; 
            $parsed['host'] = BASEURL; 
        } 
    elseif(!checkdnsrr($parsed['host'],'A')) {return 0;} 

$fp = fsockopen ($parsed['host'], 80); 
fputs($fp,"GET $Value HTTP/1.0\n\n"); 
$line = fgets($fp, 1024); 
if (stristr($line, '200 OK')) {$end = 1;} 
else{$end = 0;} 
fclose($fp); 
return $end; 
} //end isURL

if (isURL('http://www.moriacps.ic.edu.au/home/jorgiaa/index.html')=='1')
{
echo "YEP!";
}else{
echo "NOPE!";
}

?>

[Arc]

I just tested it and it seems to work fine...

I think your error was treating the 1 as a string by putting quotes around...But I think PhP converts that anyway...Not sure what else it could be other than maybe your server is case sensitive. If you have a file with an upper case letter in it and you use lower case it may not find it.

<?php 

function isURL($Value) {  

    $parsed = parse_url($Value);  

    if($parsed['scheme'] != 'http' || $parsed['host'] == '') {  

          $parsed['scheme'] = 'http';  

            $parsed['host'] = BASEURL;  

        }  

    elseif(!checkdnsrr($parsed['host'],'A')) {return 0;}  

$fp = fsockopen ($parsed['host'], 80);  
fputs($fp,"GET $Value HTTP/1.0\n\n");  
$line = fgets($fp, 1024);  
if (stristr($line, '200 OK')) {$end = 1;}  
else{$end = 0;}  
fclose($fp);  
return $end;  
} //end isURL 

if (isURL("http://www.wildhorsesaloon.com/index.php")==1) 
{ 
echo "YEP!"; 
}else{ 
echo "NOPE!"; 
} 

?> 

[sebconn]

ok this is getting weird now, the script works for all domains except for anything on www.moriacps.vic.edu.au. What is stopping the script from accessing this server?

Is there some sort of block on the domain to stop spiders and bots that would effect it?

[Weedpacket]

Well, the code you posted just now says "www.moriacps.ic.edu.au" That could be it.

[sebconn]

yeah I know I corrected that and still not finding the domain

[sebconn]

Ok this is just getting annoying, I rang the web host that runs the server that I'm trying to connect to with the script, and they said they had no security settings which would stop such a request. So what the hell is it? this script works with every other address I've used.

<?php  

function isURL($Value) {   

    $parsed = parse_url($Value);   

    if($parsed['scheme'] != 'http' || $parsed['host'] == '') {   

          $parsed['scheme'] = 'http';   

            $parsed['host'] = BASEURL;   

        }   

    elseif(!checkdnsrr($parsed['host'],'A')) {return 0;}   

$fp = fsockopen ($parsed['host'], 80);   
fputs($fp,"GET $Value HTTP/1.0\n\n");   
$line = fgets($fp, 1024);   
if (stristr($line, '200 OK')) {$end = 1;}   
else{$end = 0;}   
fclose($fp);   
return $end;   
} //end isURL 

if (isURL("http://www.moriacps.vic.edu.au/home/jorgiaa/index.html")==1)  

{  

echo "YEP!";  

}else{  

echo "NOPE!";  

}
?>

check the URL, it's perfectly legit,

could it have something to do with the fact that the domain name is .vic.edu.au and not your standard .com or .com.au? <-----Scratch that I tried another vic.edu.au URL and it worked.

[Weedpacket]

I too get the desired response; it may be something about your network. (I have to start shrugging mutely: network administration has always seemed like a black art to me).

Just as a wild guess, take the DNS lookup out of the test buy commenting out that line:

// elseif(!checkdnsrr($parsed['host'],'A')) {return 0;}   

and seeing how far you get then.

[sebconn]

Nope, no go unfortunatly,

god damn this is frustrating, I'm so close

just for the hell of it here it is again:

<?php  

function isURL($Value) {   

    $parsed = parse_url($Value);   

    if($parsed['scheme'] != 'http' || $parsed['host'] == '') {   

          $parsed['scheme'] = 'http';   

            $parsed['host'] = BASEURL;   

        }   

 //   elseif(!checkdnsrr($parsed['host'],'A')) {return 0;}   

$fp = fsockopen ($parsed['host'], 80);   
fputs($fp,"GET $Value HTTP/1.0\n\n");   
$line = fgets($fp, 1024);   
if (stristr($line, '200 OK')) {$end = 1;}   
else{$end = 0;}   
fclose($fp);   
return $end;   
} //end isURL 

if (isURL("http://www.moriacps.vic.edu.au/home/jorgiaa/index.html")==1)  

{  

echo "YEP!";  

}else{  

echo "NOPE!";  

}
?>