Search for a value in a long string

iNFERiON

I am building a formmailer with an admin panel in which you can control a banlist.
However I was wondering what the best way is to have PHP check if the IP of the sender is in the blacklist.

For example:

$bannedip = "1.2.3.4,";
$bannedip .= "5.6.7.8,";

What I want PHP to do is to check if the IP exists in the $bannedip string, but as you see, it seperates IP's by comma, so it should see the comma as a seperator.

Is there any way to have it do that ?

iNFERiON

Someone suggested me to use the split function, seems to be what I need although I have a weird problem, first let me show the source I have now:

$bannedip = "1.2.3.4,";
$bannedip .= "5.6.7.8,";
$bannedip .= "0.0.0.0,";
$meh = split(',', $bannedip);
$test = array_search($_GET['ip'], $meh);
if(!$test) { echo "IP Allowed"; } else { echo "IP Blacklisted"; }

Note: The $GET['ip'] is for debugging, I know the real command is $SERVER['REMOTE_ADDR']. However, in the above example, when I try ?ip=5.6.7.8 or ?ip=0.0.0.0 it says "IP Blacklisted, which is good. But when I use ?ip=1.2.3.4, it says IP allowed, which is not good :o

Any suggestions what might be causing this ?

esukf

use in_array instead.

$test = in_array($_GET['ip'], $meh);

array_search returns the array key when it finds a match, so 1.2.3.4 returns 0

laserlight

The reason is that [man]array_search/man returns the key if the element is found, and false if it is not found.

!$test evaluates to true when $test is false, but also when $test is 0. "1.2.3.4" is at position 0 in the array, hence when it is found, $test = 0. To correct this problem, one would test with ($test === false).

However, in this case, since you do not need to know the position of the element, you should use [man]in_array/man, as esukf suggested. You should use [man]explode/man instead of [man]split/man, since you do not need the regular expression capability of split().

$bannedip = "1.2.3.4,";
$bannedip .= "5.6.7.8,";
$bannedip .= "0.0.0.0,";

if (in_array($_GET['ip'], explode(',', $bannedip))) {
	echo "IP Blacklisted";
} else {
	echo "IP Allowed";
}

There is an alternative, and that is to use [man]strpos/man. In this case, you would not need to generate an array at all.

$bannedip = "1.2.3.4,";
$bannedip .= "5.6.7.8,";
$bannedip .= "0.0.0.0,";

if (strpos($bannedip, $_GET['ip']) === false) {
	echo "IP Blacklisted";
} else {
	echo "IP Allowed";
}