search

adafruit / Adafruit_BluefruitLE_nRF51

Arduino library for nRF51822-based Adafruit Bluefruit LE modules
197 stars 122 forks source link

flaw in packetParser.cpp 'readPacket' rejects valid packets #23

Open ScottFerg56 opened 7 years ago

ScottFerg56 commented 7 years ago

This file and function appear in three examples that I could find.

The 'readPacket' function resets the packet when a '!' byte is seen: if (c == '!') { replyidx = 0; } (line 101 after ble->read) Unfortunately, '!' can be a valid value for a parameter or checksum byte in the packet. This flaw causes certain valid packets to be rejected with a "Checksum mismatch". For example, a color picker packet with any of the RGB values set to 33 ('!') will be rejected. Likewise a color picker packet whose RGB values sum to 122 will generate a checksum value of '!' and be rejected.

petermichaux commented 7 years ago

I agree this is confusing. It could very well be that a byte contains the value 33 as a color.

petermichaux commented 7 years ago

@hathach, any insights you can share on this?

ladyada commented 7 years ago

hathach didnt write it, i did :)