This type of instrumentation is much faster (several times over) and
supports much more features than afl-gcc/afl-g++, though it requires
a LLVM/clang installation.
olm::decode_base64 now returns the length of the raw decoded data on
success. When given input with an invalid base64 length, it fails early
(before decoding any input) and returns -1.
This also makes the C function _olm_decode_base64 an actual binding of
olm::decode_base64 instead of a wrapper with slightly different
behaviour.
_olm_decode_group_message should initialize all fields of the results
struct before returning. This is because its caller
_decrypt_max_plaintext_length relies on it having initialized these
fields.
Luckily, this only allows one to subvert the version check in
_decrypt_max_plaintext_length, but not the following check that the
ciphertext field is non-null because that field *is* initialized.
Consider the case when the input is size 0. In this case, `count` and
`buffer_pos` will be 0 as well. The `realloc` call in the `count == 0`
branch will then effectively become a free.
However, `realloc` can sometimes return `NULL` when a 0 is passed for
the size. The current code assumes that this only happens on a memory
allocation error and breaks out of the loop. This then becomes a double
free because the buffer is freed a second time, causing an abort.
The intent of the `realloc` is probably to downsize the buffer to fit
the data exactly in order to make incorrect memory access more obvious.
This commit skips this downsizing if the size of the input data is 0.
Improve ObjC wrappers so that they can use a pickle key provided by the olm lib user.
This new behavior is optional to not break existing usage.
It is retro compatible and use pickle versioning already in place.
Existing key will be unpickled with pickle v1 and pickled with pickle v2 if an external pickle key is provided.
Since it's important to keep backwards compatibility introduce a new
function to calculate the MAC using a SAS object.
Modifying the existing functions would break compatibility with older
releases of libolm.
