SSL_CTX_ADD_SESSION(3) | Library Functions Manual | SSL_CTX_ADD_SESSION(3)

# NAME

`SSL_CTX_add_session`, `SSL_CTX_remove_session` — manipulate session cache

# SYNOPSIS

library “libssl” libcrypto
`#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);

# DESCRIPTION

`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.

# RETURN VALUES

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.

# SEE ALSO

ssl(3), SSL_CTX_set_session_cache_mode(3), SSL_SESSION_free(3)

# HISTORY

`SSL_CTX_add_session`() and `SSL_CTX_remove_session`() first appeared in SSLeay 0.8.0 and have been available since OpenBSD 2.4.

June 8, 2025 | Debian