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1.\" $OpenBSD: SSL_set_session.3,v 1.5 2025/06/08 22:52:00 schwarze Exp $
2.\" OpenSSL 05ea606a May 20 20:52:46 2016 -0400
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51.Dd $Mdocdate: June 8 2025 $
52.Dt SSL_SET_SESSION 3
53.Os
54.Sh NAME
55.Nm SSL_set_session
56.Nd set a TLS/SSL session to be used during TLS/SSL connect
57.Sh SYNOPSIS
58.Lb libssl libcrypto
59.In openssl/ssl.h
60.Ft int
61.Fn SSL_set_session "SSL *ssl" "SSL_SESSION *session"
62.Sh DESCRIPTION
63.Fn SSL_set_session
64sets
65.Fa session
66to be used when the TLS/SSL connection is to be established.
67.Fn SSL_set_session
68is only useful for TLS/SSL clients.
69When the session is set, the reference count of
70.Fa session
71is incremented
72by 1.
73If the session is not reused, the reference count is decremented again during
74.Fn SSL_connect .
75Whether the session was reused can be queried with the
76.Xr SSL_session_reused 3
77call.
78.Pp
79If there is already a session set inside
80.Fa ssl
81(because it was set with
82.Fn SSL_set_session
83before or because the same
84.Fa ssl
85was already used for a connection),
86.Xr SSL_SESSION_free 3
87will be called for that session.
88.Pp
89.Vt SSL_SESSION
90objects keep internal link information about the session cache list when being
91inserted into one
92.Vt SSL_CTX
93object's session cache.
94One
95.Vt SSL_SESSION
96object, regardless of its reference count, must therefore only be used with one
97.Vt SSL_CTX
98object (and the
99.Vt SSL
100objects created from this
101.Vt SSL_CTX
102object).
103.Sh RETURN VALUES
104The following return values can occur:
105.Bl -tag -width Ds
106.It 0
107The operation failed; check the error stack to find out the reason.
108.It 1
109The operation succeeded.
110.El
111.Sh SEE ALSO
112.Xr ssl 3 ,
113.Xr SSL_CTX_set_session_cache_mode 3 ,
114.Xr SSL_get_session 3 ,
115.Xr SSL_SESSION_free 3 ,
116.Xr SSL_session_reused 3
117.Sh HISTORY
118.Fn SSL_set_session
119first appeared in SSLeay 0.5.2 and has been available since
120.Ox 2.4 .