Comparing Array with more than one row - php

Question

I'm trying to compare 2 Arrays and output the difference in a separate array.
I've made the following line of code to compare 2 Arrays;
$INPUTdifference = array_udiff($userINPUT, $iptablesINPUT, function ($userINPUT, $iptablesINPUT) { return (int) ($userINPUT != $iptablesINPUT); });
When userINPUT contains one row for testing, and iptablesINPUT a few, it works flawlessly.
However, whenever I add a second row in the userINPUT array, it completely stops working. It doesn't even give anything while I print the INPUTdifference anymore
What is wrong here?
EDIT;
The way userINPUT is acquired;
function getIPTablesINPUT() {
/* ------------------------------ */
// INPUT CHAIN
/* ------------------------------ */
$INPUTCOMMAND = popen('/usr/bin/sudo /sbin/iptables -L INPUT -nvx --line-numbers | tail -n +3', 'r');
$INPUTcontent = '';
while (!feof($INPUTCOMMAND)) {
$INPUTcontent .= fread($INPUTCOMMAND, 4096);
}
pclose($INPUTCOMMAND);
$INPUTlines = explode("\n", trim($INPUTcontent));
$INPUTresults = array();
$INPUTcounter = 0;
foreach ($INPUTlines as $line) {
$segments = preg_split('/[\s]+/', $line);
$INPUTArray = array(
'num' => $segments[0],
'pkts' => $segments[1],
'bytes' => $segments[2],
'target' => $segments[3],
'prot' => $segments[4],
'opt' => $segments[5],
'in' => $segments[6],
'out' => $segments[7],
'source' => $segments[8],
'destination' => $segments[9]
);
array_push($INPUTresults, $INPUTArray);
$INPUTcounter++;
}
return $INPUTresults;
}
then, outside of the function
$iptablesINPUT = getIPTablesINPUT();
Then, the way the rules in the data
$dbconnection = pg_connect("host=x port=x dbname=x user=x password=xxxx") or die("Unable to connect to Postgres");
// INPUT table from userDB
$userINPUTresult = pg_query($dbconnection, "SELECT * FROM \"INPUT\"");
if (pg_affected_rows($userINPUTresult) === 1) {
$userINPUTArray = pg_fetch_all($userINPUTresult);
echo "INPUT CHAIN RULES LOADED \n";
} else {
echo ("NO INPUT CHAIN RULES \n");
}
==== VAR DUMPS ====
var_dump $iptablesINPUT
NULL
array(2) {
[0]=>
array(10) {
["num"]=>
string(1) "1"
["pkts"]=>
string(1) "0"
["bytes"]=>
string(1) "0"
["target"]=>
string(4) "DROP"
["prot"]=>
string(3) "all"
["opt"]=>
string(2) "--"
["in"]=>
string(1) "*"
["out"]=>
string(1) "*"
["source"]=>
string(9) "192.0.0.1"
["destination"]=>
string(9) "0.0.0.0/0"
}
[1]=>
array(10) {
["num"]=>
string(1) "2"
["pkts"]=>
string(1) "0"
["bytes"]=>
string(1) "0"
["target"]=>
string(4) "DROP"
["prot"]=>
string(3) "all"
["opt"]=>
string(2) "--"
["in"]=>
string(1) "*"
["out"]=>
string(1) "*"
["source"]=>
string(9) "192.0.0.2"
["destination"]=>
string(9) "0.0.0.0/0"
}
}
var_dump $userINPUT
NULL
Apparentely this is the spot where something goes wrong...
==== EDIT 2 ======
This is the way I extract the arrays from the function out of the scope.
// Slice up userDB arrays for comparing
$userINPUT = $allRules[0];
$userOUTPUT = $allRules[1];
$userFORWARD = $allRules[2];
$userPOSTROUTING = $allRules[3];
$userPREROUTING = $allRules[4];

Answer 1

The array_udiff function returns you the elements which are in the first array and are not in the next arrays.
From array_udiff page:
array array_udiff ( array $array1 , array $array2 [, array $... ], callable $value_compare_func )
Returns an array containing all the values of array1 that are not present in any of the other arguments
Since the value of your first array ($userINPUT in your case) is null then the result of array_udiff will be also null.
Look, after execution of the following code
$a = array(1,2);
$b = array(1);
$c = array_udiff($a, $b, function($a, $b){return (int) $a != $b;});
// $c == array(2) now
the value of $c will be array(2), since the following code
$a = null;
$b = array(1);
$c = array_udiff($a, $b, function($a, $b){return (int) $a != $b;});
// $c == null now
will lead to $c equals null.