---
name: "d2i_SSL_SESSION"
section: "3ssl"
platform: "linux"
package: "openssl"
version: "3.6.5-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/d2i_SSL_SESSION"
---

# d2i\_SSL\_SESSION(3ssl)

convert SSL\_SESSION object from/to ASN1 representation

## NAME

d2i\_SSL\_SESSION, d2i\_SSL\_SESSION\_ex, i2d\_SSL\_SESSION - convert SSL\_SESSION object from/to ASN1 representation

## 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

These functions decode and encode an SSL\_SESSION object. For encoding details see **d2i\_X509**(3).

SSL\_SESSION objects keep internal link information about the session cache list, when being inserted into one SSL\_CTX object's session cache. One SSL\_SESSION object, regardless of its reference count, must therefore only be used with one SSL\_CTX object (and the SSL objects created from this SSL\_CTX object).

## RETURN VALUES

**d2i\_SSL\_SESSION()** and **d2i\_SSL\_SESSION\_ex()** return a pointer to the newly allocated SSL\_SESSION object. 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. When the session is not valid, **0** is returned and no operation is performed.

## SEE ALSO

[**ssl**(7)](/ssl/7.md), **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.

## 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\>.