The current USSD code is not doing any size checks, add a test
case to find out how easily we access the data out of bounds.
Begin to use the length in some places.
This file format will be used to store per country code,
per network code messages. This will be used for various
things ranging from access control, to messages...
make sure to return the number of actually written bytes gsm_7bit_decode:
calculate length of resulting septets from input length before decoding
The input length to gsm_7bit_decode reflects the number of encoded bytes
to be decoded. As the decoding is done on the input in septetes we need
to take this into account and recalculate the length.