Python: Using a filter to find IMEI of a device?

Question

Summary

I am using an MT4000 telemetry device to broadcast data over port 30000, then a python udp listener to receive this data and insert it into a database. A PHP page then reads that data and displays the data, in JSON format currently.

The Goal

I would like to add a feature on the web page to allow the user to select which device they are seeing data from, as a filter.

The Method

I want to use python to programmatically extract the devices IMEI number, a way of uniquely identifying the device. I know the IMEI is located in each packet sent, and is a 15 digit number.

The Solution

What is the theory behind adding the filter to the page. If you want to down-vote (or even not), please leave a reason, so I can improve my question writing. Thanks.

Answer 1

Do you know where exactly the number is (i.e it's offset in the packet)? Or you know only that somewhere in the packet there are 15 digits in a row which are the IMEI?

If the answer to the first question is yes then there shouldn't be any problem to extract the IMEI, so I suppose this is not the case.

The following applies only if the packet structure is totally unknown, so all you can do is to search for 15 digits in a row and hope that these are the IMEI.

If the packet contents is represented as a string in your Python code (or if you can convert it to a string), again the easiest (but not the most effective) way might be to use regular expressions, like \d{15}.

Another approach is to manually traverse through packet (supposing it's a string):

def findImei(packet):
    start = -1;
    cnt = 0;
    for i, c in enumerate(packet):
        if not c.isdigit():
            cnt = 0;
            continue;
        if cnt == 0:
            start = i;
        cnt += 1;
       if cnt == 15:
           return packet[start : i + 1]
    return None;