SSL_CTX_add_session, SSL_CTX_remove_session - manipulate session cache
 #include <openssl/ssl.h>
 int SSL_CTX_add_session(SSL_CTX *ctx, SSL_SESSION *c);
 int SSL_CTX_remove_session(SSL_CTX *ctx, SSL_SESSION *c);
SSL_CTX_add_session() adds the session c to the context
  ctx. The reference count for session c is incremented by 1. If a
  session with the same session id already exists, the old session is removed by
  calling SSL_SESSION_free(3).
SSL_CTX_remove_session() removes the session c from
    the context ctx and marks it as non-resumable.
    SSL_SESSION_free(3) is called once for c.
When adding a new session to the internal session cache, it is examined whether
  a session with the same session id already exists. In this case it is assumed
  that both sessions are identical. If the same session is stored in a different
  SSL_SESSION object, The old session is removed and replaced by the new
  session. If the session is actually identical (the SSL_SESSION object is
  identical), SSL_CTX_add_session() is a no-op, and the return value is
  0.
If a server SSL_CTX is configured with the
    SSL_SESS_CACHE_NO_INTERNAL_STORE flag then the internal cache will not be
    populated automatically by new sessions negotiated by the SSL/TLS
    implementation, even though the internal cache will be searched
    automatically for session-resume requests (the latter can be suppressed by
    SSL_SESS_CACHE_NO_INTERNAL_LOOKUP). So the application can use
    SSL_CTX_add_session() directly to have full control over the sessions
    that can be resumed if desired.
The following values are returned by all functions:
  - 0
- The operation failed. In case of the add operation, it was tried to add
      the same (identical) session twice. In case of the remove operation, the
      session was not found in the cache.
- 1
- The operation succeeded.
ssl(7), SSL_CTX_set_session_cache_mode(3),
  SSL_SESSION_free(3)
Copyright 2001-2016 The OpenSSL Project Authors. All Rights Reserved.Licensed under the OpenSSL license (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>.