DTLS_GET_DATA_MTU(3SSL)

💖 DTLS_GET_DATA_MTU 💖

okay bestie, welcome to the DTLS_get_data_mtu page from the OpenSSL manual, section 3SSL. yes it's a real manpage and yes it's about to be cute. grab a strawberry 🍓 and let's go.

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✨ NAME ✨

DTLS_get_data_mtu — get that maximum data payload size, periodt.

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🦋 SYNOPSIS 🦋

#include <openssl/ssl.h>

size_t DTLS_get_data_mtu(const SSL *ssl);

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🌸 DESCRIPTION 🌸

so, the way that this works: you call DTLS_get_data_mtu() and it hands you the maximum data payload size for the established DTLS connection ssl 💅

and how does it figure that out? slay question. it's based on:

• the DTLS record MTU, and
• the overhead of the DTLS record header, plus the encryption and authentication that are currently in use 🔥

basically it does the math so you don't have to, no cap.

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💀 RETURN VALUES 💀

• success → the maximum data payload size, iconic 👑
• failure → 0 😭

fr fr, check that zero. if you get 0 you got a failure, not a payload of size zero.

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🎀 HISTORY 🎀

not me telling you the lore: the DTLS_get_data_mtu() function was added in OpenSSL 1.1.1 🧚

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👑 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>.

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that's the whole vibe check, bestie 🫶 this was OpenSSL version 4.0.3, dated 2026-09-29, and that's the DTLS_GET_DATA_MTU page in section 3SSL — mwah, take care of her 💜✨