.\" .\" $OpenBSD: d2i_SSL_SESSION.3,v 1.1 2016/11/05 15:32:20 schwarze Exp $ .\" .Dd $Mdocdate: November 5 2016 $ .Dt D2I_SSL_SESSION 3 .Os .Sh NAME .Nm d2i_SSL_SESSION , .Nm i2d_SSL_SESSION .Nd convert SSL_SESSION object from/to ASN1 representation .Sh SYNOPSIS .In openssl/ssl.h .Ft SSL_SESSION * .Fn d2i_SSL_SESSION "SSL_SESSION **a" "const unsigned char **pp" "long length" .Ft int .Fn i2d_SSL_SESSION "SSL_SESSION *in" "unsigned char **pp" .Sh DESCRIPTION .Fn d2i_SSL_SESSION transforms the external ASN1 representation of an SSL/TLS session, stored as binary data at location .Fa pp with length .Fa length , into an .Vt SSL_SESSION object. .Pp .Fn i2d_SSL_SESSION transforms the .Vt SSL_SESSION object .Fa in into the ASN1 representation and stores it into the memory location pointed to by .Fa pp . The length of the resulting ASN1 representation is returned. If .Fa pp is the .Dv NULL pointer, only the length is calculated and returned. .Sh NOTES The .Vt SSL_SESSION object is built from several .Xr malloc 3 Ns -ed parts; it can therefore not be moved, copied or stored directly. In order to store session data on disk or into a database, it must be transformed into a binary ASN1 representation. .Pp When using .Fn d2i_SSL_SESSION , the .Vt SSL_SESSION object is automatically allocated. The reference count is 1, so that the session must be explicitly removed using .Xr SSL_SESSION_free 3 , unless the .Vt SSL_SESSION object is completely taken over, when being called inside the .Xr get_session_cb 3 (see .Xr SSL_CTX_sess_set_get_cb 3 ) . .Pp .Vt SSL_SESSION objects keep internal link information about the session cache list when being inserted into one .Vt SSL_CTX object's session cache. One .Vt SSL_SESSION object, regardless of its reference count, must therefore only be used with one .Vt SSL_CTX object (and the .Vt SSL objects created from this .Vt SSL_CTX object). .Pp When using .Fn i2d_SSL_SESSION , the memory location pointed to by .Fa pp must be large enough to hold the binary representation of the session. There is no known limit on the size of the created ASN1 representation, so the necessary amount of space should be obtained by first calling .Fn i2d_SSL_SESSION with .Fa pp Ns = Ns .Dv NULL , and obtain the size needed, then allocate the memory and call .Fn i2d_SSL_SESSION again. Note that this will advance the value contained in .Fa *pp so it is necessary to save a copy of the original allocation. For example: .Bd -literal int i, j; char *p, *temp; i = i2d_SSL_SESSION(sess, NULL); p = temp = malloc(i); if (temp != NULL) { j = i2d_SSL_SESSION(sess, &temp); assert(i == j); assert(p + i == temp); } .Ed .Sh RETURN VALUES .Fn d2i_SSL_SESSION returns a pointer to the newly allocated .Vt SSL_SESSION object. In case of failure a .Dv NULL pointer is returned and the error message can be retrieved from the error stack. .Pp .Fn i2d_SSL_SESSION returns the size of the ASN1 representation in bytes. When the session is not valid, 0 is returned and no operation is performed. .Sh SEE ALSO .Xr ssl 3 , .Xr SSL_CTX_sess_set_get_cb 3 , .Xr SSL_SESSION_free 3