D2I_SSL_SESSION(3ossl)

💖 D2I_SSL_SESSION(3ossl) 💖

okay bestie, welcome to the d2i_SSL_SESSION(3ossl) page, the little corner of OpenSSL where your SSL_SESSION object gets yeeted into bytes and back again 🦋

---

✨ NAME ✨

d2i_SSL_SESSION, d2i_SSL_SESSION_ex, i2d_SSL_SESSION — convert an SSL_SESSION object from/to ASN1 representation, no cap 🔥

---

🎀 SYNOPSIS 🎀

#include <openssl/ssl.h>

SSL_SESSION *d2i_SSL_SESSION(SSL_SESSION **a, const unsigned char **pp,
                             long length);
SSL_SESSION *d2i_SSL_SESSION_ex(SSL_SESSION **a, const unsigned char **pp,
                                long length, OSSL_LIB_CTX *libctx,
                                const char *propq);
int i2d_SSL_SESSION(SSL_SESSION *in, unsigned char **pp);

---

🌸 DESCRIPTION 🌸

So basically these functions decode and encode an SSL_SESSION object. For the encoding deets, go look at d2i_X509(3) — she's the blueprint, iykyk 💅

Now the part you need to hear, bestie, because it's giving "read the fine print or perish":

SSL_SESSION objects keep internal link information about the session cache list when they get inserted into one SSL_CTX object's session cache. So one single SSL_SESSION object — no matter what its reference count is — must therefore only be used with one SSL_CTX object (and the SSL objects created from that SSL_CTX object). One session, one context. Periodt. 👑

---

🫶 RETURN VALUES 🫶

• d2i_SSL_SESSION() and d2i_SSL_SESSION_ex() — return a pointer to the newly allocated SSL_SESSION object, slay ✨. In case of failure the NULL-pointer is returned and the error message can be retrieved from the error stack 😭
• i2d_SSL_SESSION() — returns the size of the ASN1 representation in bytes, iconic 💖. When the session is not valid, 0 is returned and no operation is performed 🙈

---

🌈 SEE ALSO 🌈

• ssl(7)
• SSL_SESSION_free(3)
• SSL_CTX_sess_set_get_cb(3)
• d2i_X509(3)

---

👑 HISTORY 👑

The function d2i_SSL_SESSION_ex() was added in OpenSSL 3.2 — she's the newer sister, main character energy, arrived in 3.2 ⭐

---

💜 COPYRIGHT 💜

Copyright 2001-2024 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 vibe check, bestie — go forth and serialise responsibly 💖

kisses from the OpenSSL docs, version 3.5.9, dated 2026-09-29 — that's a wrap on D2I_SSL_SESSION(3ossl) 🎀✨