NAME
ASN1_item_new,
ASN1_item_free —
generic ASN.1 value constructor and
destructor
SYNOPSIS
#include
<openssl/asn1.h>
ASN1_VALUE *
ASN1_item_new(const ASN1_ITEM
*it);
void
ASN1_item_free(ASN1_VALUE
*val_in, const ASN1_ITEM *it);
DESCRIPTION
ASN1_item_new()
allocates and initializes an empty ASN.1 value of the type described by the
global static object it.
If the item type described by
it is reference counted,
ASN1_item_free()
decrements the reference count of val_in. Otherwise,
or if the reference count reaches 0,
ASN1_item_free() frees val_in,
assuming that it is of the type described by it. If
the true type of val_in fails to match the specified
it, buffer overflows and segmentation faults are
likely to occur. It is not possible to recover the type of an
ASN1_VALUE object by inspecting it; the type always
needs to be remembered separately.
ASN1_VALUE is an incomplete type, and pointers to it always require casting to the correct complete type before they can be dereferenced. For all practical purposes, a pointer to ASN1_VALUE is equivalent to a void pointer.
Depending on it, there
are more than 150 different types that
ASN1_item_new()
may return. Most of them are pointers to structures or pointers to arrays of
structures, but there are a few exceptions, for example: If
it is ASN1_NULL_it,
ASN1_item_new() returns a specific invalid pointer
representing the unique ASN1_NULL object. If
it is LONG_it,
ASN1_item_new() does not return a pointer at all,
but a long value cast to ASN1_VALUE
*.
RETURN VALUES
The ASN1_item_new() function returns the
new ASN1_VALUE object if successful; otherwise
NULL is returned and an error code can be retrieved
with ERR_get_error(3).
SEE ALSO
ASN1_get_object(3), ASN1_item_d2i(3), ASN1_item_digest(3), ASN1_item_pack(3), ASN1_item_sign(3), ASN1_item_verify(3), ASN1_NULL_new(3), ASN1_TYPE_new(3), d2i_ASN1_NULL(3), OBJ_nid2obj(3)
HISTORY
ASN1_item_new() and
ASN1_item_free() first appeared in OpenSSL 0.9.7 and
have been available since OpenBSD 3.2.
BUGS
The ASN1_VALUE type compromises type safety and invites programming mistakes that will typically have severe consequences.