Fix header __CRYPT_GNUTLS_H__ #define guard.
Do not return uninitialized char *.
replace deprecated gnutls_datum with gnutls_datum_t.
Correctly overwrite the diffie-helman shared secret memory buffer with 0 before free. sizeof(unsigned char *) is the size of the pointer not the size of the buffer it is pointint to.
Return null in error state when pass is not set to a vlaue.
Initialize type in utun_write(). Fix types definitions to remove clang compiler warning.