- NAME
- SYNOPSIS
- DESCRIPTION
- RETURN VALUES
- SEE ALSO
- COPYRIGHT

# NAME

SSL_dup, SSL_new, SSL_up_ref - create an SSL structure for a connection

# SYNOPSIS

    #include <openssl/ssl.h>

    SSL *SSL_dup(SSL *s);
    SSL *SSL_new(SSL_CTX *ctx);
    int SSL_up_ref(SSL *s);

# DESCRIPTION

SSL_new() creates a new SSL structure which is needed to hold the data for a TLS/SSL connection. The new structure inherits the settings of the underlying context ctx: connection method, options, verification settings, timeout settings. An SSL structure is reference counted. Creating an SSL structure for the first time increments the reference count. Freeing it (using SSL_free) decrements it. When the reference count drops to zero, any memory or resources allocated to the SSL structure are freed.

SSL_up_ref() increments the reference count for an existing SSL structure.

The function SSL_dup() creates and returns a new SSL structure from the same SSL_CTX that was used to create s. It additionally duplicates a subset of the settings in s into the new SSL object.

For SSL_dup() to work, the connection MUST be in its initial state and MUST NOT have yet started the SSL handshake. For connections that are not in their initial state SSL_dup() just increments an internal reference count and returns the same handle. It may be possible to use SSL_clear(3) to recycle an SSL handle that is not in its initial state for reuse, but this is best avoided. Instead, save and restore the session, if desired, and construct a fresh handle for each connection.

The subset of settings in s that are duplicated are:

any session data if configured (including the session_id_context)
any tmp_dh settings set via SSL_set_tmp_dh(3), SSL_set_tmp_dh_callback(3), or SSL_set_dh_auto(3)
any configured certificates, private keys or certificate chains
any configured signature algorithms, or client signature algorithms
any DANE settings
any Options set via SSL_set_options(3)
any Mode set via SSL_set_mode(3)
any minimum or maximum protocol settings set via SSL_set_min_proto_version(3) or SSL_set_max_proto_version(3) (Note: Only from OpenSSL 1.1.1h and above)
any verify mode, callback or depth set via SSL_set_verify(3) or SSL_set_verify_depth(3) or any configured X509 verification parameters
any msg callback or info callback set via SSL_set_msg_callback(3) or SSL_set_info_callback(3)
any default password callback set via SSL_set_default_passwd_cb(3)
any session id generation callback set via SSL_set_generate_session_id(3)
any configured Cipher List
initial accept (server) or connect (client) state
the max cert list value set via SSL_set_max_cert_list(3)
the read_ahead value set via SSL_set_read_ahead(3)
application specific data set via SSL_set_ex_data(3)
any CA list or client CA list set via SSL_set0_CA_list(3), SSL_set0_client_CA_list() or similar functions
any security level settings or callbacks
any configured serverinfo data
any configured PSK identity hint
any configured custom extensions
any client certificate types configured via SSL_set1_client_certificate_types
any Encrypted Client Hello (ECH) settings (see SSL_set1_echstore(3)).

SSL_dup() is not supported on QUIC SSL objects and returns NULL if called on such an object.

# RETURN VALUES

The following return values can occur:

NULL

  The creation of a new SSL structure failed. Check the error stack to find out the reason.

Pointer to an SSL structure

  The return value points to an allocated SSL structure.

  SSL_up_ref() returns 1 for success and 0 for failure.

# SEE ALSO

SSL_free(3), SSL_clear(3), SSL_CTX_set_options(3), SSL_get_SSL_CTX(3), ssl(7)

# COPYRIGHT

Copyright 2000-2026 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.