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SSL_CTX_set_session_id_context(3)   OpenSSL  SSL_CTX_set_session_id_context(3)

NAME

SSL_CTX_set_session_id_context, SSL_set_session_id_context - set con- text 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);

DESCRIPTION

SSL_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/import- ing 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 applica- tion must set its own session id context sid_ctx which is used to dis- tinguish 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 con- text 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_SES- SION_ID_LENGTH.

WARNINGS

If the session id context is not set on an SSL/TLS server and client certificates are used, 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 con- text, as an OpenSSL server checks the session id context itself before reusing a session as described above.

RETURN VALUES

SSL_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 ALSO

ssl(3) 0.9.8e-rhel5 2004-06-14 SSL_CTX_set_session_id_context(3)

1994 Man-cgi 1.15, Panagiotis Christias <christia@theseas.ntua.gr>