SSL_CTX_set_session_id_contexOpeSSL_CTX_set_session_id_context(3)NAME
SSL_CTX_set_session_id_context, SSL_set_session_id_context
- set context within which session can be reused (server
side only)
SYNOPSIS
#include <openssl/ssl.h>
int SSL_CTX_set_session_id_context(SSL_CTX *ctx, const unsigned char *sid_ctx,
unsigned int sid_ctx_len);
int SSL_set_session_id_context(SSL *ssl, const unsigned char *sid_ctx,
unsigned int sid_ctx_len);
DESCRIPTIONSSL_CTX_set_session_id_context() sets the context sid_ctx
of length sid_ctx_len within which a session can be reused
for the ctx object.
SSL_set_session_id_context() sets the context sid_ctx of
length sid_ctx_len within which a session can be reused
for the ssl object.
NOTES
Sessions are generated within a certain context. When
exporting/importing sessions with
i2d_SSL_SESSION/d2i_SSL_SESSION it would be possible, to
re-import a session generated from another context (e.g.
another application), which might lead to malfunctions.
Therefore each application must set its own session id
context sid_ctx which is used to distinguish the contexts
and is stored in exported sessions. The sid_ctx can be any
kind of binary data with a given length, it is therefore
possible to use e.g. the name of the application and/or
the hostname and/or service name ...
The session id context becomes part of the session. The
session id context is set by the SSL/TLS server. The
SSL_CTX_set_session_id_context() and
SSL_set_session_id_context() functions are therefore only
useful on the server side.
OpenSSL clients will check the session id context returned
by the server when reusing a session.
The maximum length of the sid_ctx is limited to
SSL_MAX_SSL_SESSION_ID_LENGTH.
WARNINGS
If the session id context is not set on an SSL/TLS server,
stored sessions will not be reused but a fatal error will
be flagged and the handshake will fail.
If a server returns a different session id context to an
OpenSSL client when reusing a session, an error will be
flagged and the handshake will fail. OpenSSL servers will
always return the correct session id context, as an
OpenSSL server checks the session id context itself before
reusing a session as described above.
RETURN VALUESSSL_CTX_set_session_id_context() and
SSL_set_session_id_context() return the following values:
0 The length sid_ctx_len of the session id context
sid_ctx exceeded the maximum allowed length of
SSL_MAX_SSL_SESSION_ID_LENGTH. The error is logged to
the error stack.
1 The operation succeeded.
SEE ALSOssl(3)31/Jan/2001 0.SSL_CTX_set_session_id_context(3)
