Hi all, I'm not really sure if this is the correct list to place this
on. Apologies if it is not. I've come across some un-expected
behaviour in the new filter_var function but i'm not really sure if
it's just me not understanding the documentation correctly.
I have the following two functions which should filter the HIGH ascii
chars and manually strip the LOW ascii chars (so as to allow through
\r \n"
If the line
$input = filter_var( $input, FILTER_SANITIZE_STRING,
FILTER_FLAG_STRIP_HIGH | FILTER_FLAG_ENCODE_AMP |
FILTER_NULL_ON_FAILURE);
is executed before manually searching for characters like \0 , it
appears to effect the ability for mb_strpos to identify low numbered
ascii characters.
Is the filter_var function automagically removing the \0 ? I'm not
saying this is bad in anyway. I can't imagine what you would want/need
a null byte for in PHP :)
just wanted to check that this is in fact the behaviour that is
expected, as I wasn't expecting it from what the docs said.
#!/usr/bin/php
<?php
function test1( $input )
{
// we want the outcome to be false
$haslownum = false;
for( $i = 0; $i< 32 ;$i++)
{
// 13 is CR carriage return
if( ($i != 10 && $i != 13 ) && mb_strpos($input,chr($i)) )
{
$haslownum = true;
$input = null;
break;
}
}
$input = filter_var( $input, FILTER_SANITIZE_STRING,
FILTER_FLAG_STRIP_HIGH | FILTER_FLAG_ENCODE_AMP |
FILTER_NULL_ON_FAILURE);
return $input;
}
function test2( $input )
{
$input = filter_var( $input, FILTER_SANITIZE_STRING,
FILTER_FLAG_STRIP_HIGH | FILTER_FLAG_ENCODE_AMP |
FILTER_NULL_ON_FAILURE);
// we want the outcome to be false
$haslownum = false;
for( $i = 0; $i< 32 ;$i++)
{
// 13 is CR carriage return
if( ($i != 10 && $i != 13 ) && mb_strpos($input,chr($i)) )
{
$haslownum = true;
$input = null;
}
}
return $input;
} // end filter_for_db_allow_cr
$input = "myname\0.php";
$input = test1($input);
echo "Test #1 should be null : ".$input."\n";
$input = "myname\0.php";
$input = test2($input);
echo "Test #2 should be null? : ".$input."\n";
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