XmlRpcOid

Well, I just needed to control my home debian server from my mobile device. There you have a simple app to do it, using xml-rpc, java, perl on the server side -despite you can use any XML-RPC server/language you want on the server side-. This uses plain xml over http, so the connection is plain, non-encripted. I don't need it because this runs inside a VPN, so I run it without encryption. Don't run this over the open web!

Warning: This application does not encrypt data. If you don't know what you are doing, buy a Windows box and a Windows phone and write [email protected] to provide you of an app like this. You can open a door to hackers by writing open XML-RPC services. You've been warned, now it's your full responsibility.

What is XML-RPC?

XML RPC is just a communications protocol that uses XML to execute remote procedures (RPC stands for Remote Procedure Call). You can send two numbers to the server and it can answer with the sum, or you can ask a server to reboot.

This is a simple example: asking the uptime. A os.uptime RPC call is executed, it requires no parameters.

<?xml version='1.0'?>
<methodCall>
        <methodName>os.uptime</methodName>
        <params><param><value>
                        <struct/>
                        </value>
                </param>
        </params>
</methodCall>

So, the server answers something like:

<?xml.version="1.0"?>
<methodResponse>
        <params> <param> <value> <struct> 
                                        <member>
                                                <name>status</name>
                                                <value>
                                                        <string>11:56:24 up 9 days, 1 2:01,  2 users,   load average: 0.02, 0.02, 0.05. </string>
                                                </value>
                                        </member>
                                </struct>
                        </value>
                </param>
        </params>
</methodResponse>

---

Now, an example of using two parameters. The rpc.ProductTest RPC call is executed with two parameters: var1=5 and var2=12.

<?xml.version='1.0'.?>
<methodCall>
    <methodName>
	    rpc.ProductTest
    </methodName>
    <params> <param> <value> <struct>
				    <member>
					    <name>var1</name>
					    <value>
						    <string>5</string>
					    </value>
				    </member>
				    <member>
					    <name>var 2</name>
					    <value>
						    <string>12</string>
					    </value>
				    </member>
			    </struct>
		    </value>
	    </param>
    </params>
</methodCall>

So, the server answers with the product: 5 * 12 = 60.

<?xml.version="1.0"?>
<methodResponse>
    <params> <param> <value> <struct>
				    <member>
					    <name>status</name>
					    <value>
						    <string>60</string>
					    </value>
				    </member>
			    </struct>
		    </value>
	    </param>
    </params>
</methodResponse>

---

Server side

You can use any XML-RPC server. This example uses a perl daemon to test the two previous XML dumps.

Paste this on a file named xmlrpcserver.pl:

---

use Frontier::Daemon;
use Data::Dumper;

sub rpcTest {

    %params = %{@_[0]};
    $var1=$params{'var1'};
    $var2=$params{'var2'};
    $prod=$var1*$var2;

    # Always return the 'status' variable, it is used to show the result on android screen.
    return {'status' => "$prod"};
}

sub osUptime {
    return {'status' => `uptime`};
}

$methods = {
    'rpc.ProductTest' 	=> \&rpcTest,
    'os.uptime' 		=> \&osUptime
};
Frontier::Daemon->new(LocalPort => 8080, methods => $methods, ReuseAddr => 1);

---

Execute it:

# perl xmlrpcserver.pl

You can find a bigger example on the /lib directory of this repository. You can replace the uptime command with shutdown, a process kill, a service start, a useradd, a grep log, whatever you can imagine. The only drawback is your security.

Client side

1. Install the apk on your phone (find it on the /apk dir of this repository). Better if you can compile it yourself with Android Studio.

2. Start the appplication.

3. Go to SETTINGS.

   • On Service URL, enter the URL of your server. The Perl Example uses something like

   http://your.server.address:8080/RPC2

   

   • On Command 7, write this:

   os.uptime

   • On Command 8, write this:

   rpc.ProductTest var1:5 var2:12

   

4. Explanation:

• The first line is the xml-rpc command that will be called (see the $methods variable on the perl server). Be sure to choose a clear name, the RPC command name is shown on the main screen combo box.

• The second and further lines are interpreted as parameters. They should have the format VARIABLE:VALUE (word, colon, value, which is transmitted as a string, always, so you can interpret it as you like on the server).

• If the Command entry is empty, it will not be shown on the main screen commands combo box.

• More lines can be added by using the ENTER key on the android keyboard.

5. Test the application:

   • Choose a command from the combo box
   • Press the "Execute" button.

   

Credits

• Background: http://www.xanadu-fx.com/tiles/fractals.php

• Android Xml-Rpc lib: http://code.google.com/p/android-xmlrpc

Current version

20150816: v1.1.3 20150816: v1.1.2 (broken) 20150727: v1.0.2