ASN1_ITEM_NEW(3)

🌸 NAME 🌸

okay so this is the ASN1_ITEM_NEW(3) page from the Library Functions Manual, and it’s giving generic ASN.1 value constructor and destructor energy — the main characters are ASN1_item_new and ASN1_item_free, and they are literally the constructor/destructor duo for generic ASN.1 values. 🎀

✨ SYNOPSIS ✨

bestie, you’re linking the library “libcrypto” — here’s the include and the exact signatures, no cap:

#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. that’s the whole main-character move here. ✨

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. 🫶

⚠️ okay but for real: 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. so keep that type info safe, bestie 😭

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. iykyk. 🦋

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). slay when it works, check that error when it doesn’t. 💅

🔥 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. vintage but still iconic, fr fr. 👑

💀 BUGS 💀

The ASN1_VALUE type compromises type safety and invites programming mistakes that will typically have severe consequences. not me calling out the whole type system, but it’s true 😭💀

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mwah 💋 this has been the Debian source/version, dated June 8, 2025, for the ASN1_ITEM_NEW(3) manual page — bye bestie, go cast your pointers correctly 🫶🌈