osmo_bsc_bssap: check bssmap length field

At the moment the length field of the bssmap header is not parsed.
Instead the length is computed out of the known header length and the
number of bytes received. This is prone to error, lets make sure that
extranous data at the end of a message is ignored by parsing the bssmap
length correctly.

Change-Id: Idef2e783d2377a2ad1f697ea4d26491a32b3e549
Related: OS#3806
1 file changed