Function CPACE_process_msg 

pub unsafe extern "C" fn CPACE_process_msg(
    ctx: *mut CPACE_CTX,
    in_msg: *const u8,
    peer_assoc_data: *const u8,
    peer_assoc_data_len: usize,
    shared_secret: *mut u8,
    sid_out: *mut u8,
) -> c_int