Validating IP address and ip address ranges delimited by semicolon - php

Question

Here's the problem, I allow users to input an IP whitelist or list of IPs or IP ranges separated by semicolon.
So they can put
74.122.31.233; 76.233.12.222 - 80.788.888.111; 72.203.44.209
74.122.31.233; 76.233.12.222; 72.203.44.209
74.122.31.233 - 76.233.12.222; 72.203.44.209
74.122.31.233-76.233.12.222; 72.203.44.209
74.122.31.233-76.233.12.222;72.203.44.209
They can choose to use spaces or not to use spaces between ranges and before/after semicolons.
So they can either put IP addresses separated by semicolon or IP address ranges separated by semicolons or IP addresses and IP ranges separated by semi colons.
I am new to regular expresses. Does anyone know the right way to validate if they input the IP whitelist correctly to adhere to the rules above?
Thanks.

Answer 1

I'm not convinced regular expressions are necessary or even helpful in this case, especially as PHP has filter_var():
function isValid($ranges) {
// remove all spaces
$ranges = str_replace(' ', '', $ranges);
// iterate over individual ranges and IP addresses
foreach(explode(';', $ranges) as $range) {
// single address
if(strpos($range, '-') === false) {
if(!filter_var($range, FILTER_VALIDATE_IP)) {
return false;
}
}
// range
else {
$addresses = explode('-', $range, 3);
if(count($addresses) != 2) {
return false;
}
if(!filter_var($addresses[0], FILTER_VALIDATE_IP) || !filter_var($addresses[1], FILTER_VALIDATE_IP)) {
return false;
}
}
}
return true;
}
$tests = array(
'74.122.31.233; 76.233.12.222 - 80.788.888.111; 72.203.44.209',
'74.122.31.233; 76.233.12.222; 72.203.44.209',
'74.122.31.233 - 76.233.12.222; 72.203.44.209',
'74.122.31.233-76.233.12.222; 72.203.44.209',
'74.122.31.233-76.233.12.222;72.203.44.209');
foreach($tests as $test) {
echo $test;
echo isValid($test) ? ' is valid' : ' is invalid';
echo "\n";
}
Output:
74.122.31.233; 76.233.12.222 - 80.788.888.111; 72.203.44.209 is invalid // 80.788.888.111 is an invalid IP address
74.122.31.233; 76.233.12.222; 72.203.44.209 is valid
74.122.31.233 - 76.233.12.222; 72.203.44.209 is valid
74.122.31.233-76.233.12.222; 72.203.44.209 is valid
74.122.31.233-76.233.12.222;72.203.44.209 is valid

Answer 2

Don't try to cram everything into a single regular expression. I know you're thinking that, classic rookie mistake.
Remove the whitespace from the input: $input = preg_replace('/\s/', '', $input);
Split on semicolons: $in_arr = explode(';', $input);
Loop through the array and if( preg_match('/-/', $in_arr[index]) ) then explode('-', $in_arr[index]); and then process it like a range
To validate IP addresses don't use a regular expression. Use ip2long().
Every valid IP address is really a 32-bit integer, the 'dotted quad' notation just breaks that integer into four 8-bit chunks from 0-255.
If you feed an invalid address like 80.788.888.111 into ip2long() it will return false, no complicated regex needed.
Using ip2long() makes it way easier to compare IP addresses as well, '123.123.123.3' > '123.123.123.10' [string comparison, bad], but ip2long('123.123.123.3') < ip2long('123.123.123.10') [integer comparison, good]

Answer 3

Explode them by ;, and then trim the array values to remove the spaces. That way, you can make sure both the spaced-version and non-spaced versions of the user input is treated equally.
$parts = explode(';', $text);
$parts = array_map('trim', $parts);
//or $parts = array_map('trim', explode(';', $text));
//check if IP is valid
For validating the IP, you don't need a regular expression. PHP already has a built-in function filter_var() which does exactly what you want.
$parts = array_map('trim', explode(';', $text));
foreach ($parts as $ip) {
if(strpos($ip, '-')) {
list($range1, $range2) = explode('-', $ip);
// validate IP range here
}
elseif (filter_var($ip, FILTER_VALIDATE_IP) ) {
echo "$ip is valid<br/>";
}
}
That should get you started.

Answer 4

Here is one simple function :
function validateInput($s) {
foreach (explode(';', $s) as $v) {
$v = array_map('trim', explode('-', $v));
if (count($v) > 2) return false;
$valid = true;
foreach ($v as $ip) $valid = $valid && filter_var($ip, FILTER_VALIDATE_IP);
if (!$valid) return false;
}
return true;
}
Use example :
$inputs = [
'74.122.31.233; 76.233.12.222 - 80.788.888.111; 72.203.44.209',
'74.122.31.233; 76.233.12.222; 72.203.44.209',
'74.122.31.233-76.233.12.222;72.203.44.209',
'274.122.31.233-76.233.12.222',
'74.122.31.233-76.233.12.222-77.233.12.222',
];
foreach ($inputs as $input) {
echo (validateInput($input) ? 'TRUE ' : 'FALSE') . " : $input\n";
}
Output :
FALSE : 74.122.31.233; 76.233.12.222 - 80.788.888.111; 72.203.44.209
TRUE : 74.122.31.233; 76.233.12.222; 72.203.44.209
TRUE : 74.122.31.233-76.233.12.222;72.203.44.209
FALSE : 274.122.31.233-76.233.12.222
FALSE : 74.122.31.233-76.233.12.222-77.233.12.222