BIO_F_NULL(3ossl)

💖 BIO_F_NULL — the null filter, aka the BIO that literally does nothing 💖

okay bestie so this is BIO_f_null from the OpenSSL manual (that's the 3ossl section, third section, the library-calls one 🎀), and ngl it's kind of the funniest little function in the whole stack. it's a filter BIO. it filters... nothing. it's giving ✨*the void*✨. let's get into it.

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🌸 NAME 🌸

BIO_f_null — the null filter 🦋

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✨ SYNOPSIS ✨

#include <openssl/bio.h>

const BIO_METHOD *BIO_f_null(void);

that's it. that's the whole thing. two lines. iconic behaviour honestly 💅

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💜 DESCRIPTION 💜

so BIO_f_null() returns the null filter BIO method. and what is a null filter BIO, you ask? it's a filter BIO that does nothing. like, genuinely. zero. nada. the bare minimum. it's the friend who shows up to the group project and contributes vibes. 😭

every single request sent to a null filter BIO gets passed straight through to the next BIO in the chain. which means — and this is the important part, so stay with me — a BIO chain that contains a null filter BIO behaves exactly like the BIO just wasn't there at all. same energy as adding 0 to a number. the chain keeps its shape, the null filter just chills in the middle contributing nothing to the conversation 🫶

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🎀 NOTES 🎀

and, like... as may be apparent 🙈, a null filter BIO is not particularly useful. that's the actual note. the manpage said it. we're just saying it cuter. it's a placeholder. it's a stand-in. it's the "we'll fix it in post" of BIOs. no cap.

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⭐ RETURN VALUES ⭐

BIO_f_null() returns the null filter BIO method. that's the return value. the null filter BIO method. the whole thing. one job, done beautifully 👑

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👑 COPYRIGHT 👑

Copyright 2000-2016 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 grab a copy in the file LICENSE in the source distribution, or at <https://www.openssl.org/source/license.html>. read your licenses bestie, it's self care 🌸

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and that's the whole page, fr fr 🦋 this was OpenSSL 3.5.9, dated 2026-09-29, and yes we read an entire manpage about a function whose whole personality is doing nothing — and honestly? ate. periodt. 💅✨