Remove parts of a string with PHP

Question

I have an input box that tells uers to enter a link from imgur.com I want a script to check the link is for the specified site but I'm not sue how to do it?

The links are as follows: https://i.sstatic.net/RYnCi.jpg Please note that after the /, the text may vary e.g. not be a jpg but the main domain is always http://i.imgur.com/.

Any help appreciated. Thanks, Josh.(Novice)

cEz · Accepted Answer · 2012-02-24 12:15:14Z

3

Try parse_url()

try {
    if (!preg_match('/^(https?|ftp)://', $_POST['url']) AND !substr_count($_POST['url'], '://')) {
        // Handle URLs that do not have a scheme
        $url = sprintf("%s://%s", 'http', $_POST['url']);
    } else {
        $url = $_POST['url'];
    }

    $input = parse_url($url);

    if (!$input OR !isset($input['host'])) {
        // Either the parsing has failed, or the URL was not absolute
        throw new Exception("Invalid URL");
    } elseif ($input['host'] != 'i.imgur.com') {
        // The host does not match
        throw new Exception("Invalid domain");
    }

    // Prepend URL with scheme, e.g. http://domain.tld
    $host = sprintf("%s://%s", $input['scheme'], $input['host']);
} catch (Exception $e) {
    // Handle error
}

edited Feb 24, 2012 at 12:15

answered Feb 23, 2012 at 23:28

cEz

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7 Comments

simshaun Over a year ago

parse_url() can fail, therefore you need to make sure it !== false before checking $input['host']

cEz Over a year ago

@simshaun That is true, but not in the "quick" answer. I've enhanced the answer for you

simshaun Over a year ago

??? Quick answer or not, it's necessary or else you've introduced a potential bug in your code.

Blease Over a year ago

Is there anyway to get this to insert http:// dependent on whether its been provided or not?

cEz Over a year ago

@JoshLukeBlease parse_url will only work in full if the URL is absolute, but I have added a sanity check for http/https/ftp

|

simshaun · Accepted Answer · 2012-02-23 23:36:44Z

2

substr($input, 0, strlen('http://i.imgur.com/')) === 'http://i.imgur.com/'

edited Feb 23, 2012 at 23:36

simshaun

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answered Feb 23, 2012 at 23:24

miki

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Comments

Shiplu Mokaddim · Accepted Answer · 2012-02-24 12:21:39Z

2

Check this, using stripos

if(stripos(trim($url), "http://i.imgur.com")===0){
 // the link is from imgur.com
}

edited Feb 24, 2012 at 12:21

answered Feb 23, 2012 at 23:28

Shiplu Mokaddim

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Comments

Yoone · Accepted Answer · 2012-02-25 10:46:04Z

1

Try this:

<?php
if(preg_match('#^http\:\/\/i\.imgur.com\/#', $_POST['url']))
    echo 'Valid img!';
else
    echo 'Img not valid...';
?>

Where $_POST['url'] is the user input.

I haven't tested this code.

edited Feb 25, 2012 at 10:46

answered Feb 23, 2012 at 23:28

Yoone

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Comments

raina77ow · Accepted Answer · 2012-02-23 23:23:57Z

1

$url_input = $_POST['input_box_name'];
if ( strpos($url_input, 'http://i.imgur.com/') !== 0 )

...

answered Feb 23, 2012 at 23:23

raina77ow

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3 Comments

simshaun Over a year ago

Needs to be !== FALSE or == 0. I'd opt for the latter since you would expect it to be act the beginning of the string.

raina77ow Over a year ago

!== FALSE won't give us the position check, just the presence one. ) And ==0 is just not right, as it'd the same response for FALSE as well.

simshaun Over a year ago

I hinted the position check, and that the latter would be better. But yes you are right, it needs to be === 0. Edit: Just realized you probably meant the condition for throwing an error. Ignore me.

simshaun · Accepted Answer · 2012-02-23 23:24:58Z

1

Several ways of doing it.. Here's one:

if ('http://i.imgur.com/' == substr($link, 0, 19)) {
    ...
}

answered Feb 23, 2012 at 23:24

simshaun

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