ASN1_STRING_LENGTH(3ossl)

📦 version 3.5.0, in opensuse-leap 16.0

💅 ASN1_STRING_LENGTH (3ossl) — the OpenSSL string-utility glow-up

okay bestie, welcome to the 3ossl corner of the manual, and buckle up because this page is all about the ASN1_STRING utility functions ✨

🌸 NAME

ASN1_STRING_dup, ASN1_STRING_cmp, ASN1_STRING_set, ASN1_STRING_length, ASN1_STRING_type, ASN1_STRING_get0_data, ASN1_STRING_data, ASN1_STRING_to_UTF8 — the whole ASN1_STRING utility-functions friend group 🫶

🎀 SYNOPSIS

#include <openssl/asn1.h>

int ASN1_STRING_length(ASN1_STRING *x);
const unsigned char *ASN1_STRING_get0_data(const ASN1_STRING *x);
unsigned char *ASN1_STRING_data(ASN1_STRING *x);

ASN1_STRING *ASN1_STRING_dup(const ASN1_STRING *a);

int ASN1_STRING_cmp(ASN1_STRING *a, ASN1_STRING *b);

int ASN1_STRING_set(ASN1_STRING *str, const void *data, int len);

int ASN1_STRING_type(const ASN1_STRING *x);

int ASN1_STRING_to_UTF8(unsigned char **out, const ASN1_STRING *in);

✨ DESCRIPTION ✨

These functions are literally your whole toolkit for manipulating an ASN1_STRING structure 💖

  • ASN1_STRING_length() — returns the length of the content of x. and x MUST NOT be NULL, bestie, don't do that to me 😭
  • ASN1_STRING_get0_data() — hands you an internal pointer to the data of x. Since it's internal, do not free it and do not modify it in any way, no cap. x MUST NOT be NULL.
  • ASN1_STRING_data() — same vibe as ASN1_STRING_get0_data() except the returned value is not constant. This function is deprecated: applications should use ASN1_STRING_get0_data() instead. she's retired, respect her legacy but move on 💅
  • ASN1_STRING_dup() — returns a copy of the structure a. dupe era 👯
  • ASN1_STRING_cmp() — compares a and b, returning 0 if the two are identical. The string types and the content are compared.
  • ASN1_STRING_set() — sets the data of string str to the buffer data or length len. The supplied data is copied (iconic, non-destructive behaviour). If len is -1 then the length is determined by strlen(data).
  • ASN1_STRING_type() — returns the type of x, using standard constants such as V_ASN1_OCTET_STRING.
  • ASN1_STRING_to_UTF8() — converts the string in to UTF8 format, and the converted data is allocated in a buffer in *out. The length of out is returned, or a negative error code. The buffer *out should be freed using OPENSSL_free() 🧚

🦋 NOTES 🦋

Almost all ASN1 types in OpenSSL are represented as an ASN1_STRING structure. Other types such as ASN1_OCTET_STRING are simply typedef'ed to ASN1_STRING and the functions call the ASN1_STRING equivalents. ASN1_STRING is also used for some CHOICE types which consist entirely of primitive string types such as DirectoryString and Time. main character energy for a humble struct, honestly 👑

⚠️ These functions should not be used to examine or modify ASN1_INTEGER or ASN1_ENUMERATED types: the relevant INTEGER or ENUMERATED utility functions should be used instead. wrong tool for the job, babes 🙈

In general it cannot be assumed that the data returned by ASN1_STRING_data() is null terminated or does not contain embedded nulls. The actual format of the data will depend on the actual string type itself: for example for an IA5String the data will be ASCII, for a BMPString two bytes per character in big endian format, and for a UTF8String it will be in UTF8 format. it's giving "read the room, know your encoding" 🔥

Similar care should be take to ensure the data is in the correct format when calling ASN1_STRING_set(). (yes, the original says "take" — we keep it exactly as-is, periodt 💀)

💖 RETURN VALUES 💖

  • ASN1_STRING_length() — returns the length of the content of x.
  • ASN1_STRING_get0_data() and ASN1_STRING_data() — return an internal pointer to the data of x.
  • ASN1_STRING_dup() — returns a valid ASN1_STRING structure or NULL if an error occurred.
  • ASN1_STRING_cmp() — returns an integer greater than, equal to, or less than 0, according to whether a is greater than, equal to, or less than b. the classic three-way slay 🫶
  • ASN1_STRING_set() — returns 1 on success or 0 on error.
  • ASN1_STRING_type() — returns the type of x.
  • ASN1_STRING_to_UTF8() — returns the number of bytes in output string out or a negative value if an error occurred.

🍓 SEE ALSO

Copyright 2002-2020 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

and that's the whole page, bestie 🌈 this was 3.5.0, dated 2026-09-25, straight from the ASN1_STRING_LENGTH(3ossl) manual — go forth and handle your strings responsibly, ily ⭐🎀

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