Extending SMS Capabilities
I live in a place where wireless access points are few, mobile internet is expensive, but SMS is unlimited. Of course, I use SMS for communicating with my friends, family, girlfriend, colleagues, and for business. Then, one day it came to my mind, why not communicate with my personal computer?
My father brought home a USB dongle (Huawei E220), I unlocked it, and tried a sim card, and it worked! Now this, is what my computer will be using as a receiver. At first, it’s very frustrating to install the drivers for this dongle. Modern ones are just smooth on PnP (Plug ‘n Play) features. It took me a while to find out that I need to reconfigure the driver Windows installed by default.
Setting Up
Now it’s connected. But I need a way to make it receive SMS, and save it somehow. Then I stumbled upon Gammu luckily, it supports E220(see all supported devices). The configuration file is given, and pretty elementary.
[gammu] port = COM6 connection = at19200 model = at
You just need to replace COM6 with the COM port you have in your device manager.
COM Port used by the USB Dongle
And then, I intend to install gammu as a service. Luckily an SMS daemon is included, and using the previous gammu configuration:
[smsd] logfile=C:\smsd\smsd.log service=files inboxpath=C:\SMSData\data\ [gammu] port = COM6 connection = at19200 model = at [include_numbers] +000000000000
You can change the paths as you wish, but make sure your number is included in the [include_numbers] section. This is a nice feature that will block unwanted texts from other numbers.
Not that it’s all set, run the daemon and make it install itself as a service, then start the service.
gammu-smsd -i -c C:\smsd\gammu-smsdrc
It will now run automatically with windows. Your USB dongle must be connected all the time to your computer.
Processing Received Messages
Now here’s a tricky but fun part. How will you process the incoming messages? Notice that I used the Files mode instead of using DBMS to receive SMS message. This is because, I need to constantly check if there’s a new message, and checking the database tables every now and then for 24/7 is painful. So in files, we’re gonna use a Timer? No! Of course, we’re not using methods that will cause heavy CPU load.
Using the FileSystemWatcher class, we can check, in real-time, if there’s a new file created in a given directory. This is perfect, because gammu’s SMS daemon creates a new text file, with the message in it, in the specified directory we included in the configuration file.
if (!fpath.Equals(""))
watcher.Path = fpath + @"\";
watcher.Filter = "*.txt";
watcher.NotifyFilter = NotifyFilters.LastWrite | NotifyFilters.FileName;
watcher.Created += new FileSystemEventHandler(OnChanged);
watcher.EnableRaisingEvents = listenToolStripMenuItem.Checked;
Whenever a file is created inside the specified directory, it will execute the code inside the OnChanged() method. From this, we can process the content of each file and read them.
But not so fast. Sadly(although this seems like a right way), gammu splits the messages by 67 characters. Meaning, if your message exceeds 67 characters, it will be split into several files. For instance:
IN20120716_121927_00_+000000000000_00.txt IN20120716_121927_00_+000000000000_00.txt IN20120716_121930_00_+000000000000_01.txt
These are files the dongle received at one point in time. But they really are just 2 separate messages. How? If you look into the last two digits on the filename, it will tell you the sequence of the messages. 00 means the beginning of the message, if followed by another 00, it’s a new message. But if it’s followed by 01, it’s to be appended, and must be read as part two of the first one.
It took me sometime to figure out how to combine them into one. I can only receive one at a time, but the parts came both together with a very tiny interval. By this, I came up with a solution that will use a Timer.
timer.Enabled = false; timer.Interval = 1000; timer.Tick += new EventHandler(timer_Tick);
I allotted two seconds to wait for upcoming possible parts, then process them and verify if they really are parts of a long message.
private void OnChanged(object sender, FileSystemEventArgs e)
{
if (timer.Enabled)
{
tmp.Add(e.FullPath);
}
else
{
tmp = new List<string>();
this.Invoke(new MethodInvoker(delegate
{
timer.Enabled = true;
timer.Start();
}));
tmp.Add(e.FullPath);
}
}
private void timer_Tick(object sender, EventArgs e)
{
secs++;
if (secs >= 2)
{
timer.Enabled = false;
secs = 0;
procList(tmp);
}
}
private void procList(List<string> lst)
{
List<string> data = new List<string>();
string xdata = "";
bool app = true;
int prev = -1;
foreach (string fp in lst)
{
if (Regex.IsMatch(fp, @"_(d{2})\.txt$"))
{
Match m = Regex.Match(fp, @"_(d{2})\.txt$");
int x = Int32.Parse(m.Groups[1].Value);
if (x - prev != 1)
{
app = false;
prev = -1;
}
else
{
prev = x;
}
}
string datum = readContent(fp);
if (app)
{
xdata += datum;
}
else
{
data.Add(xdata);
xdata = datum;
}
}
data.Add(xdata);
foreach (string d in data)
{
processData(d);
}
}
It’s a pretty long process, and it took me hours to figure out what to do. But after that, it’s time to add some modules to boost its functionality.
Making Things Functional
As for now, I only have the twitter module working.
private void processData(string data)
{
Command cmd = parseString(data);
switch (cmd.id)
{
case "tweet":
tServ.SendTweet(cmd.arg);
break;
case "google":
// Google processing here
break;
}
}
private Command parseString(string str)
{
Command cmd = new Command();
if (str.Contains(' '))
{
cmd.id = str.Split(' ').FirstOrDefault();
cmd.arg = str.Remove(0, cmd.id.Length + 1);
}
return cmd;
}
// ...
class Command
{
public string id;
public string arg;
}
I have plenty of ideas in mind. I am currently working on a google module, then a file-search module for my computer, and many more. In the mean time, you can watch the development process and add your own modules as well. Fork it in GitHub.
I will update if I have something new. Cheers!
I named this project after Parker, my favorite Leverage character.