Proxy 164 byte packet expectation

[kb1lqd]

Proxy.py: https://github.com/FaradayRF/Faraday-Software/blob/master/proxy/proxy.py

While writing the device configuration program I found that the Proxy program POST expected 164 byte items and this doesn't make much sense. @kb1lqc informed me that this was because of the fixed packet length of the UART layer 4 protocol.

This doesn't make sense because fixed packets are 128 byte's in total prior to framing. The only reasonable explanation is that 164 bytes were a chance length from his testing of telemetry packets and are a result of the specific case of testing and BASE64 encoding size increase. This length would likely change with different data POSTed.

The POST command filtering data for fixed length to avoid random data is pretty useless because:

• It's the UART network stack's job to filter out random data
• Unlikely to pass random unwanted data (noise)
• Just because a layer if fixed length doesn't mean the tranmission medium (FLASK) should expect it. If the byte length is increased the FLASK proxy server will also need to be changed. Decoupling is a good idea.

total = len(data["data"])
            sent = 0
            for item in data['data']:
                if len(item) != 164:
                    logger.warning("Packet not 164 characters long!")
                    logger.warning(str(item))
                else:
                    # Correct length packet, send it by putting on the queue!
                    try:
                        postDicts[station][port].append(item)
                    except:
                        postDicts[station][port] = deque([], maxlen=100)
                        postDicts[station][port].append(item)
                    sent += 1
            return json.dumps(
                {"status": "Posted {0} of {1} Packet(s)"
                    .format(sent, total)}), 200

[kb1lqd]

I rigged up a test to figure out what was going on and the summary is:

• An "application" (device configuration) program was setup to accept a POST command that caused a POST of text string to Proxy
• I modified proxy to print data/item information

Application This was the snippet of code that sent a POST command to the Proxy server:

using a POSTMAN test call:

Proxy

The code was modified to print data information and shows:

• Length of data calculation uses the BASE64 encoded string
• The POSTed string "Testing new application!" was the variable length data item received by proxy
• Length of BASE64 = 32 bytes
• Length of RAW data = 24 bytes

[kb1lqd]

I modified Proxy to NOT filter packet length and the results were a success!

The text string "Testing new application!" was successfully received on the CC430 Faraday!

I see no harm in removing the POSTed data check for data in Proxy and it will follow the methodology of isolating layers and mediums from eachother when possible.

[kb1lqd]

This bug was resolved by removing the 164 byte check completely in merger #28