Access Certain Key Value in PHP Array - php

Question

I am new to PHP and got confused, I wrote a PHP script to log the server environment variables when user make request, and my code looks like this:
<?php
$req_dump = print_r($_SERVER, TRUE);
$fp = fopen('/tmp/request.log', 'a');
fwrite($fp, $req_dump);
fclose($fp);
echo "hello world";
However, the output looks like below:
Array
(
[HTTP_USER_AGENT] => anaconda/13.21.195
[HTTP_HOST] => 10.0.188.97
[HTTP_ACCEPT] => */*
[HTTP_X_ANACONDA_ARCHITECTURE] => x86_64
[HTTP_X_ANACONDA_SYSTEM_RELEASE] => Red Hat Enterprise Linux
[HTTP_X_RHN_PROVISIONING_MAC_0] => eth0 B4:99:BA:07:xx:xx
[HTTP_X_RHN_PROVISIONING_MAC_1] => eth1 B4:99:BA:07:xx:xx
[HTTP_X_RHN_PROVISIONING_MAC_2] => eth2 B4:99:BA:07:xx:xx
[HTTP_X_RHN_PROVISIONING_MAC_3] => eth3 B4:99:BA:07:xx:xx
[HTTP_X_RHN_PROVISIONING_MAC_4] => eth4 00:02:C9:4F:xx:xx
[HTTP_X_RHN_PROVISIONING_MAC_5] => eth5 00:02:C9:4F:xx:xx
[PATH] => /sbin:/usr/sbin:/bin:/usr/bin
[SERVER_SIGNATURE] => <address>Apache/2.2.15 (Red Hat) Server at 10.0.188.97 Port 80</address>
[SERVER_SOFTWARE] => Apache/2.2.15 (Red Hat)
[SERVER_NAME] => 10.0.188.97
[SERVER_ADDR] => 10.0.188.97
[SERVER_PORT] => 80
[REMOTE_ADDR] => 10.0.188.212
[DOCUMENT_ROOT] => /var/www/html
[SERVER_ADMIN] => root#localhost
[SCRIPT_FILENAME] => /var/www/html/ks.php
[REMOTE_PORT] => 59188
[GATEWAY_INTERFACE] => CGI/1.1
[SERVER_PROTOCOL] => HTTP/1.1
[REQUEST_METHOD] => GET
[QUERY_STRING] =>
[REQUEST_URI] => /ks.php/images/install.img
[SCRIPT_NAME] => /ks.php
[PATH_INFO] => /images/install.img
[PATH_TRANSLATED] => /var/www/html/images/install.img
[PHP_SELF] => /ks.php/images/install.img
[REQUEST_TIME] => 1402439673
)
How I tried to access the array:
FYI, here is the code how I tried to access that array:
# ks.php
<?php
$Table = array(
"00:02:C9:10:aa:bb" => "10.0.188.91",
"00:02:C9:4F:aa:bb" => "10.0.188.92",
"00:02:C9:53:aa:bb" => "10.0.188.93",
"00:02:C9:56:aa:bb" => "10.0.188.94",
"00:02:C9:53:aa:bb" => "10.0.188.95",
"00:02:C9:4E:aa:bb" => "10.0.188.96",
"00:02:C9:5A:aa:bb" => "10.0.188.97",
);
?>
...
%post
...
printf 'DEVICE=eth4 \nIPADDR=<?php echo $Table[$_SERVER["HTTP_X_RHN_PROVISIONING_MAC_4"]]; ?>' > /etc/sysconfig/network-scripts/ifcfg-eth4
service network restart
...
%end
The output doesn't look like straight forward to me. Say I want to get the MAC address of ethernet4, and $_SERVER["HTTP_X_RHN_PROVISIONING_MAC_4"] doesn't work for me.
Can anyone help me explain how to achieve that in PHP?

Answer 1

your $_SERVER['HTTP_X_RHN_PROVISIONING_MAC_4'] output is eth4 00:02:C9:4F:xx:xx which also has a prefix eth4 where as your $Table has 00:02:C9:4F:aa:bb which makes the keys mismatch and actually you are trying to get $Table['eth4 00:02:C9:4F:xx:xx'] which is non existent in your $Table array
Try this:
// We are splitting the mac address by space so that $macAddress contains '00:02:C9:4F:xx:xx' and $eth contains eth4
list($eth,$macAddress) = explode(' ',$_SERVER['HTTP_X_RHN_PROVISIONING_MAC_4']);
// Make sure the value in $macAddress => 00:02:C9:4F:xx:xx is 00:02:C9:4F:aa:bb or change your array accordingly
$Table = array(
"00:02:C9:10:aa:bb" => "10.0.188.91",
"00:02:C9:4F:aa:bb" => "10.0.188.92",
"00:02:C9:53:aa:bb" => "10.0.188.93",
"00:02:C9:56:aa:bb" => "10.0.188.94",
"00:02:C9:53:aa:bb" => "10.0.188.95",
"00:02:C9:4E:aa:bb" => "10.0.188.96",
"00:02:C9:5A:aa:bb" => "10.0.188.97",
);
$finalAddress = $Table[$macAddress];
printf 'DEVICE=eth4 \nIPADDR=<?php echo $finalAddress ; ?>' > /etc/sysconfig/network-scripts/ifcfg-eth4 '

Answer 2

If you just save the array, it becomes like a useless print out. To make it accessible, use json_encode when you save it:
$fp = fopen('/tmp/request.log', 'w');
fwrite($fp, json_encode($_SERVER));
fclose($fp);
Note how I removed the print_r since it’s unnecessary for a task like this. I also changed fopen to overwrite the file using w instead of a so the saved JSON is valid.
Then when you open the file, just use json_decode like this:
$server_variables_json = file_get_contents('/tmp/request.log');
$server_variables = json_decode($server_variables_json , true);
Then $server_variables is an actual array you can act on like this:
if (array_key_exists('HTTP_X_RHN_PROVISIONING_MAC_4', $server_variables)) {
echo $server_variables['HTTP_X_RHN_PROVISIONING_MAC_4'];
}
The if (array_key_exists(…)) is something I put in place to help me debug this locally on my machine since I don’t have HTTP_X_RHN_PROVISIONING_MAC_4 set in my $_SERVER values.
A simple check I did locally to debug this—since I don’t have HTTP_X_RHN_PROVISIONING_MAC_4 in my setup—was just to get the HTTP_HOST like this:
if (array_key_exists('HTTP_HOST', $server_variables)) {
echo $server_variables['HTTP_HOST'];
}

Answer 3

If you want to put the var $_SERVER["HTTP_X_RHN_PROVISIONING_MAC_4"], don't forgot the quotes.

Answer 4

You need to use quotes to identify a non-numeric index:
echo $_SERVER['HTTP_X_RHN_PROVISIONING_MAC_4'];
You can get more basic information from the docs themselves.
Edit: I am not sure what you mean:
<?php
$array=array(
'HTTP_X_RHN_PROVISIONING_MAC_0' => 'eth0 B4:99:BA:07:xx:xx',
'HTTP_X_RHN_PROVISIONING_MAC_1' => 'eth1 B4:99:BA:07:xx:xx',
'HTTP_X_RHN_PROVISIONING_MAC_2' => 'eth2 B4:99:BA:07:xx:xx',
'HTTP_X_RHN_PROVISIONING_MAC_3' => 'eth3 B4:99:BA:07:xx:xx',
'HTTP_X_RHN_PROVISIONING_MAC_4' => 'eth4 00:02:C9:4F:xx:xx',
'HTTP_X_RHN_PROVISIONING_MAC_5' => 'eth5 00:02:C9:4F:xx:xx'
);
echo "Printing just a single element.\r\n";
echo $array['HTTP_X_RHN_PROVISIONING_MAC_4'];
echo "Printing the whole variable:\r\n";
print_r($array);
?>
Outputs the following:
Printing just a single element.
eth4 00:02:C9:4F:xx:xx
Printing the whole variable:
Array
(
[HTTP_X_RHN_PROVISIONING_MAC_0] => eth0 B4:99:BA:07:xx:xx
[HTTP_X_RHN_PROVISIONING_MAC_1] => eth1 B4:99:BA:07:xx:xx
[HTTP_X_RHN_PROVISIONING_MAC_2] => eth2 B4:99:BA:07:xx:xx
[HTTP_X_RHN_PROVISIONING_MAC_3] => eth3 B4:99:BA:07:xx:xx
[HTTP_X_RHN_PROVISIONING_MAC_4] => eth4 00:02:C9:4F:xx:xx
[HTTP_X_RHN_PROVISIONING_MAC_5] => eth5 00:02:C9:4F:xx:xx
)