DTLS_GET_DATA_MTU(3ossl)

💅 DTLS_GET_DATA_MTU 💅

okay so real talk, this is a page from the OpenSSL manual, section 3ossl, and it's about one (1) very specific little function that tells you how much actual data you can shove into a DTLS packet. slay. let's get into it 🎀

---

✨ NAME ✨

DTLS_get_data_mtu — get the maximum data payload size, bestie. that's it. that's the whole vibe.

---

🦋 SYNOPSIS 🦋

#include <openssl/ssl.h>

size_t DTLS_get_data_mtu(const SSL *ssl);

literally just one include and one call, we love a low-effort icon 👑

---

🌸 DESCRIPTION 🌸

so. DTLS_get_data_mtu() obtains the maximum data payload size for the established DTLS connection ssl. and it's not just making a number up, no cap — it works it out based on:

• the DTLS record MTU, and
• the overhead of the DTLS record header, encryption and authentication currently in use

like, the packet's got a whole outfit on (header + crypto) and this function is measuring how much room is left for the actual data underneath. main character energy for the payload fr fr 💖

---

🔥 RETURN VALUES 🔥

• returns the maximum data payload size on success 💫
• returns 0 on failure 😭

that's the whole return contract. a number or a zero. no in-between, iykyk.

---

⭐ HISTORY ⭐

the DTLS_get_data_mtu() function was added in OpenSSL 1.1.1. vintage but still iconic 🫶

---

👑 COPYRIGHT 👑

Copyright 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 obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

ok bestie gentle reminder: read the license before you go copy-pasting, it's giving "please respect the paperwork" 💅

---

and that's the whole page!! mwah 💜 this was OpenSSL 3.5.6, dated 2026-04-07, filed under DTLS_GET_DATA_MTU(3ossl) — go forth and size your payloads responsibly 🧚✨