ASN1_STRING_LENGTH(3SSL)

📦
version 4.0.3 · 14 versions
, in ubuntu stonking

✨ ASN1_STRING_LENGTH ✨

okay bestie, welcome to the 3SSL manual, this one's all about the OpenSSL ASN1_STRING utility functions 💖 and honestly? it's giving "small but mighty" and i'm obsessed 💅

so the whole girl squad here is: ASN1_STRING_dup, ASN1_STRING_cmp, ASN1_STRING_set, ASN1_STRING_length, ASN1_STRING_type, ASN1_STRING_get0_data, and ASN1_STRING_to_UTF8 🎀

🌸 SYNOPSIS 🌸

#include <openssl/asn1.h>

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

like, write it down, screenshot it, whatever — just don't paraphrase it ✨

💜 DESCRIPTION 💜

so basically these functions let you mess with an ASN1_STRING structure 🫶 here's the rundown, one by one:

  • ASN1_STRING_length() — returns the length of the content of x. and x MUST NOT be NULL okay?? that's not a vibe, that's a rule 💀
  • ASN1_STRING_get0_data() — hands you an internal pointer to the data of x. and the 0 in the name is lowkey a warning fr fr: since it's an internal pointer, you should not free it and you should not modify it in any way 🙈 same energy: x MUST NOT be NULL.
  • ASN1_STRING_dup() — returns a copy of the structure a 🦋 clone her, respectfully.
  • ASN1_STRING_cmp() — compares a and b and returns 0 if the two are identical. it compares the string types AND the content, no shortcuts 😤
  • ASN1_STRING_set() — sets the data of string str to the buffer data or length len. the supplied data gets copied (no aliasing drama here 👑) and if len is -1 then the length is determined by strlen(data) ✨
  • ASN1_STRING_type() — returns the type of x, using the standard constants such as V_ASN1_OCTET_STRING 🌈
  • ASN1_STRING_to_UTF8() — converts the string in to UTF8 format, and the converted data gets allocated in a buffer in *out. it returns the length of out, or a negative error code if it's not giving 😭 and bestie, the buffer *out should be freed using OPENSSL_free() — do not forget, i'm literally begging 🙏

🎀 NOTES 🎀

okay this part matters, listen up:

  • 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. no cap 👑
  • ASN1_STRING is also used for some CHOICE types which consist entirely of primitive string types such as DirectoryString and Time ✨
  • 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. stay in your lane, bestie 💅
  • in general it cannot be assumed that the data returned by ASN1_STRING_get0_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 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 🦋
  • similar care should be taken to ensure the data is in the correct format when calling ASN1_STRING_set() 🌸
the way that embedded nulls can just ✨appear✨ in your data and ruin your whole strlen-based day... be careful out there 🙈

⭐ RETURN VALUES ⭐

  • ASN1_STRING_length() — returns the length of the content of x 📏
  • ASN1_STRING_get0_data() — returns 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 ⚖️
  • 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 one shipped in OpenSSL 4.0.3, dated 2026-09-29, and it's the ASN1_STRING_LENGTH(3SSL) manual — go forth and OPENSSL_free() responsibly 💅🎀💖

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