NAME
d2i_SSL_SESSION,
i2d_SSL_SESSION —
convert SSL_SESSION object from/to ASN1
representation
SYNOPSIS
#include
<openssl/ssl.h>
SSL_SESSION *
d2i_SSL_SESSION(SSL_SESSION
**a, const unsigned char
**pp, long
length);
int
i2d_SSL_SESSION(SSL_SESSION
*in, unsigned char
**pp);
DESCRIPTION
d2i_SSL_SESSION()
transforms the external ASN1 representation of an SSL/TLS session, stored as
binary data at location pp with length
length, into an SSL_SESSION
object.
i2d_SSL_SESSION()
transforms the SSL_SESSION object
in into the ASN1 representation and stores it into the
memory location pointed to by pp. The length of the
resulting ASN1 representation is returned. If pp is
the NULL pointer, only the length is calculated and
returned.
The SSL_SESSION object is built from several malloc(3)-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.
When using
d2i_SSL_SESSION(),
the SSL_SESSION object is automatically allocated. The
reference count is 1, so that the session must be explicitly removed using
SSL_SESSION_free(3), unless the
SSL_SESSION object is completely taken over, when
being called inside the
get_session_cb(),
see
SSL_CTX_sess_set_get_cb(3).
SSL_SESSION objects keep internal link information about the session cache list when being inserted into one SSL_CTX object's session cache. One SSL_SESSION object, regardless of its reference count, must therefore only be used with one SSL_CTX object (and the SSL objects created from this SSL_CTX object).
When using
i2d_SSL_SESSION(),
the memory location pointed to by 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 call
i2d_SSL_SESSION() first with
pp=NULL to obtain the encoded
size, before allocating the required amount of memory and calling
i2d_SSL_SESSION() again. Note that this will advance
the value contained in *pp so it is necessary to save
a copy of the original allocation. For example:
char *p, *pp;
int elen, len;
elen = i2d_SSL_SESSION(sess, NULL);
p = pp = malloc(elen);
if (p != NULL) {
len = i2d_SSL_SESSION(sess, &pp);
assert(elen == len);
assert(p + len == pp);
}
RETURN VALUES
d2i_SSL_SESSION() returns a pointer to the
newly allocated SSL_SESSION object. In case of failure
a NULL pointer is returned and the error message can
be retrieved from the error stack.
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.
SEE ALSO
d2i_X509(3), ssl(3), SSL_CTX_sess_set_get_cb(3), SSL_SESSION_free(3)
HISTORY
d2i_SSL_SESSION() and
i2d_SSL_SESSION() first appeared in SSLeay 0.5.2 and
have been available since OpenBSD 2.4.