InDataExchange() has wrong size limits

[mhaberler]

This is the signature of inDataExchange():

bool Adafruit_PN532::inDataExchange(uint8_t *send, uint8_t sendLength,
                                    uint8_t *response,
                                    uint8_t *responseLength) 

Further down in the code the response is limited to 64 bytes (size of packet_buffer)

Please see section 7.3.8 InDataExchange of the PN532 User Manual which states:

DataOut is an array of raw data (from 0 up to 262 bytes) to be sent to the target
by the PN532 ...
DataIn is an array of raw data (from 0 up to 262 bytes) received by the PN532..

so we have:

• packet_buffer is too small (I guess this was a mixup with the PN532 FIFO size)
• with uint8_t sendLength, *responseLength the limit is still to low at 255

This shows up if you try to read an NDEF message which wont fit the packet_buffer limit, and eventually causes a crash of the NDEF parser.

I will post code which shows the error and a PR for a fix later.

unfortunately this means a signature change buf IMO cannot be avoided.

Michael