Varriable in shell_exec

[chadrt]

Here is the script...

<?php
#### CHAD'S SCRIPT TO CHANGE VOLUME FROM A WEB PAGE ON IRLP NODES ####

$channel = $_GET['c'];
$amount = $_GET['a'];

echo $channel; //These Work Great
echo $amount;  //These Work Great

### PHP's Switch function to determine the command sent to the terminal ###
switch ($channel){
	case "vol":
		shell_exec('aumix -v $amount'); // When I use the varriable does not work!
                shell_exec('aumix -S');
		break;
        case "vol2": // Test case
                shell_exec('aumix -v 15'); // When I manually specify the volume amount it works great!
                shell_exec('aumix -S');
        break;
	case "pcm":
		shell_exec('aumix -w $amount');
                shell_exec('aumix -S');
		break;
	case "speaker":
		shell_exec('aumix -p $amount');
                shell_exec('aumix -S');
		break;	
	case "line":
		shell_exec('aumix -l $amount');
                shell_exec('aumix -S');
		break;	
	case "mic":
		shell_exec('aumix -m $amount');
                shell_exec('aumix -S');
		break;
	case "pcm2":
		shell_exec('aumix -W $amount');
                shell_exec('aumix -S');
		break;
	case "igain":
		shell_exec('aumix -i $amount');
                shell_exec('aumix -S');
		break;
        default:
		echo "";
                break;
}

### READ THE CONTENTS OF AUMIX     
$volumes = shell_exec('aumix -q');



### Begin echoing the HTML to provide the controls ###
echo "<b>Current Volume Levels:</b><br>";
echo "<pre>$volumes</pre><p>";

##### End of PHP Scripting the rest is pure HTML so we can close the PHP script tags here 
?>

<br><br><form method=get>
<p><b>Change Volume Level:</b><br>
<select name="c" id="c">
<option value="">CHOOSE CHANNEL</option>
<option value="vol">vol</option>
<option value="pcm">pcm</option>
<option value="speaker">speaker</option>
<option value="line">line</option>
<option value="mic">mic</option>
<option value="cd">cd</option>
<option value="pcm2">pcm2</option>
<option value="igain">igain</option>
<option value="line1">line1</option>
</select> <br>New Value:
<input type="text" value="" size="5" maxlength="3" name="a">
<br><input type="submit" value="Submit">
</form>

That is the entire script in all its "lack of glory".  I commented the script here to show what is working and what is not.  I can echo the varriables just fine but when I try to call it from with the shell_exec then I am assuming it is providing a blank response or one that the shell cannot understand.

 

 

[requinix]

Variables do not work in single-quoted strings. Use double-quoted strings or string concatenation.

 

But first your code is really, really unsafe. You may think the amount will be a certain thing (a number, I assume) but the code doesn't do anything to make sure that's the case. Someone could use

a=whatever command I want in here

and have you execute

aumix -v whatever command I want in here

If amount is supposed to be a number then make sure it's an actual number: cast it like

$amount = (int)$_GET['a'];

and then make sure it's a valid number, like amount>0 and amount

[chadrt]

@requinix

 

Thank you, changing the single quotes to double fixed the script!!!

 

The directory that all this is located in is only accessible by 3 people who are close friends of mine.  Secured by use of .htaccess  But I thought I would release the code to rest of the ham population so I will go ahead and impliment the other things you talked about to help secure the page a little bit better.  I was thinking about the fact that I am using $_GET and that while my page is only allowing 3 digits into the form or the select box that it could be used to inject malicious code by entering volume.php?c=<malicious code>&a=<malicious code> or someone could build their own page that POSTs the malicious code.  So I think that all the input should be striped?  As well as making sure that only integers are used in the volume

[chadrt]

OK so here is a small revision tell me what you think.  I had to do some digging in php manual but I think this will solve any hack like attempts...

<?php
#### CHAD'S (K0KAD) SCRIPT TO CHANGE VOLUME FROM A WEB PAGE ON IRLP NODES ####
#### Place script into the control directory so it is protected by Apache from outsiders
#### Put a link into the index.php file that will take you to this page.
#### Place a "--exclude index.php" into the custom/update-files-list file so that it wont get replaced each night
#### Make sure you have a suitable entry in your sudoers file /etc/sudoers so that user "repeater" can use save
#### aumix settings.  Else it will revert anytime the node reboots or power failure etc.



if((int)$_GET['a'] >=1 && (int)$_GET['a'] <=100) {
$amount =  (int)$_GET['a'];
}else{
$error = "<font color=red>Please enter a value between 1 and 100 only!<br></font>";
}

if((int)$_GET['c'] >=1 && (int)$_GET['c'] <=10) {
$channel =  (int)$_GET['c'];


### PHP's Switch function to determine the command sent to the terminal ###
switch ($channel){
	case "1":
		shell_exec("aumix -v $amount");
                shell_exec('sudo aumix -S');
                $success = "<font color=blue><b>Successfully updated volume!</b></font>";
		break;
	case "2":
		shell_exec("aumix -w $amount");
                shell_exec('sudo aumix -S');
                $success = "<font color=blue><b>Successfully updated volume!</b></font>";
		break;
	case "3":
		shell_exec("aumix -p $amount");
                shell_exec('sudo aumix -S');
                $success = "<font color=blue><b>Successfully updated volume!</b></font>";
		break;	
	case "4":
		shell_exec("aumix -l $amount");
                shell_exec('sudo aumix -S');
                $success = "<font color=blue><b>Successfully updated volume!</b></font>";
		break;	
	case "5":
		shell_exec("aumix -m $amount");
                shell_exec('sudo aumix -S');
                $success = "<font color=blue><b>Successfully updated volume!</b></font>";
		break;
	case "6":
		shell_exec("aumix -W $amount");
                shell_exec('sudo aumix -S');
                $success = "<font color=blue><b>Successfully updated volume!</b></font>";
		break;
	case "7":
		shell_exec("aumix -i $amount");
                shell_exec('sudo aumix -S');
                $success = "<font color=blue><b>Successfully updated volume!</b></font>";
		break;
	case "8":
		shell_exec("aumix -1 $amount");
                shell_exec('sudo aumix -S');
                $success = "<font color=blue><b>Successfully updated volume!</b></font>";
		break;
        default:
		echo "";
                break;
}
}else{
$error2 = "<font color=red>Please select an appropriate channel from the drop down list!<br></font>";
}

### READ THE CONTENTS OF AUMIX     
$volumes = shell_exec('aumix -q');


echo "<b>Current Volume Levels:</b><br>";
echo "<pre>$volumes</pre><p>";
echo $error;
echo $error2;
echo $success;

##### End of PHP Scripting the rest is pure HTML so we can close the PHP script tag here 
?>

<form method=get>
<p><b>Change Volume Level:</b><br>
<select name="c" id="c">
<option value="">CHOOSE CHANNEL</option>
<option value="1">vol</option>
<option value="2">pcm</option>
<option value="3">speaker</option>
<option value="4">line</option>
<option value="5">mic</option>
<option value="6">pcm2</option>
<option value="7">igain</option>
<option value="8">line1</option>
</select> <br>New Value:
<input type="text" value="" size="5" maxlength="3" name="a">
<br><input type="submit" value="Submit">
</form><br><p><br><a href="index.php">Return to Control Page</a>

[requinix]

You need to make sure that you don't run the command if there was an error. Right now you set $error if a is bad, but as long as c is valid you'll execute the command.

 

The code structure I prefer for this kind of thing goes like this:

errors = array()

if a is not valid {
    add error message for a
}

if c is not valid {
    add error message for c
}

if no errors {
    do stuff
}

[chadrt]

That worked really well!!!  Especially given that I used your first suggestion setting it as (int) for both.  I have it running now on mine and a friends nodes and it works great!!  Thank you requinix for the help!