How to remove wrong schema from an URL (with PHP) - php

Question

I need to remove a wrong schema from an URL submitted as a string.
I start with this consideration:
The only two allowed schemas are http:// and https://
Starting from this consideration, I need to remove from the string all wrongly formatted schemas like:
htp://example.com
htps://example.com
http:/example.com
https:/example.com
htpexample.com
htps://example.com
http:/example.com
https:/example.com
... many many more ...
My questions are:
Is there a way to calculate all possible variation of wrong schemas?
Which is the best approach to remove them from the given string?
ABOUT QUESTION 2
My first approach would be to create an array with all the wrong schemas and then use something like this:
$wrongSchemas = [/* here all the possible wrong schemas calculated from question 1 */];
$url = str_replace($wrongSchemas, '', $url);
But this approach relies on a correct order, because instead I risk to remove partial schemas and make it wrong anyway.
And anyway I need to find a way to create the array $wrongSchemas!
Any suggestion or any further consideration on the topic that I'm missing, is well appreciated.

Answer 1

use strpos check in your $url
if(strpos($url,"http://")!==0 && strpos($url,"https://")!==0){
//wrong schemas
$exp_string = "";
// $exp_string = strpos($url,"//")?"//":"/";
if(strpos($url,"://"))
$exp_string = "://";
elseif(strpos($url,":/"))
$exp_string = ":/";
elseif(strpos($url,":"))
$exp_string = ":";
elseif(strpos($url,"//"))
$exp_string = "//";
$temp = explode($exp_string,$url);
if(count($temp)>1){
$url = '';
for($i=1;$i<count($temp);$i++){
$url = $url.$temp[$i];
}
//if needed you can add http:// here: $url = 'http://'.$url;
}
}
echo $url;
//process for right schemas
If you need more validations like url starting with ht,htp,etc you can use checkdnsrr or gethostbyname functions to validate domains

Answer 2

After some more thoughts, thanks also to some of your comments (thank you #Frédéric Clausset), I decided that the best approach would be to build the array of wrong schemas on the fly:
$schemas = ['http', 'htp', 'htt', 'ht', 'hp', 'ttp', 'tp'];
$delimiters = ['://', ':/', ':', '//', '/'];
$wrongCombinations = [];
foreach ($schemas as $wrongSchema) {
foreach ($delimiters as $wrongDelimiter) {
$combination = $wrongSchema . $wrongDelimiter;
$combinationSecure = $wrongSchema . 's' . $wrongDelimiter;
if ('http://' !== $combination) {
$wrongCombinations[] = $combination;
}
if ('https://' !== $combinationSecure) {
$wrongCombinations[] = $combinationSecure;
}
}
}
This generates a long array like this:
array:68 [▼
0 => "http:/"
1 => "https:/"
2 => "http:"
3 => "https:"
4 => "http//"
5 => "https//"
6 => "http/"
7 => "https/"
8 => "htp://"
9 => "htps://"
10 => "htp:/"
11 => "htps:/"
12 => "htp:"
13 => "htps:"
14 => "htp//"
15 => "htps//"
16 => "htp/"
17 => "htps/"
18 => "htt://"
19 => "htts://"
20 => "htt:/"
21 => "htts:/"
22 => "htt:"
23 => "htts:"
24 => "htt//"
25 => "htts//"
26 => "htt/"
27 => "htts/"
28 => "ht://"
29 => "hts://"
30 => "ht:/"
31 => "hts:/"
32 => "ht:"
33 => "hts:"
34 => "ht//"
35 => "hts//"
36 => "ht/"
37 => "hts/"
38 => "hp://"
39 => "hps://"
40 => "hp:/"
41 => "hps:/"
42 => "hp:"
43 => "hps:"
44 => "hp//"
45 => "hps//"
46 => "hp/"
47 => "hps/"
48 => "ttp://"
49 => "ttps://"
50 => "ttp:/"
51 => "ttps:/"
52 => "ttp:"
53 => "ttps:"
54 => "ttp//"
55 => "ttps//"
56 => "ttp/"
57 => "ttps/"
58 => "tp://"
59 => "tps://"
60 => "tp:/"
61 => "tps:/"
62 => "tp:"
63 => "tps:"
64 => "tp//"
65 => "tps//"
66 => "tp/"
67 => "tps/"
]
Those 68 combinations are all the possible wrong ones.
Now, a simple str_replace removes the schema if it is one of the wrong ones:
str_replace($combinations, '', $domain);
This intercept wrong URLs like:
htp://example.com > example.com
http:/example.com > example.com
htps:/example.com > example.com
hps:/example.com > example.com
htp:example.com > example.com
many many more
all possible variations
Thank you to all of you for your answers that helped me to better clarify the problem and find my solution! :)
PS
If you find bugs or drawbacks in this code, please, let me know!

Answer 3

I would search for :// if exists in string, after a then a simple in_array with the substring
$url="https://www.example.com";
$validschemas=array("http","https");
$pos=strpos($url,"://");
if($pos)
{
$valid=in_array(substr($url,0,$pos),$validschemas)?true:false;
//If not valid schema, remove schema from url, if it os ok dont touch it.
if(!$valid)
$url=substr($url,$pos+3);
}
else
{
//No schema, then url continues being the same
}