ASN.1 NULL value
returns a specific invalid pointer that represents the ASN.1 NULL value,
which is the only possible value of the ASN.1 NULL type. That pointer is
different from a
NULL pointer. Dereferencing it
almost certainly results in a segmentation fault. This function does not
allocate memory and cannot fail.
has no effect whatsoever. In particular, it ignores the
val_in argument and does not free any memory. In
normal use, application programs only pass the invalid pointer obtained from
ASN1_NULL_new() to this function. But even if a
valid pointer is passed, that pointer does not become invalid.
The ASN.1 NULL type is also represented by the
V_ASN1_NULL type identifier constant.
ITU-T Recommendation X.208, also known as ISO/IEC 8824-1: Specification of Abstract Syntax Notation One (ASN.1), section 19: Notation for the null type
ASN1_NULL_free() first appeared in OpenSSL 0.9.5 and
have been available since OpenBSD 2.7.