gnutls_handshake(3) gnutls gnutls_handshake(3)
NAME
gnutls_handshake - API function
SYNOPSIS
#include <gnutls/gnutls.h>
int gnutls_handshake(gnutls_session_t session);
ARGUMENTS
gnutls_session_t session
is a gnutls_session_t type.
DESCRIPTION
This function performs the handshake of the TLS/SSL protocol, and ini-
tializes the TLS session parameters.
The non-fatal errors expected by this function are: GNUTLS_E_INTER-
RUPTED, GNUTLS_E_AGAIN, GNUTLS_E_WARNING_ALERT_RECEIVED. When this
function is called for re-handshake under TLS 1.2 or earlier, the
non-fatal error code GNUTLS_E_GOT_APPLICATION_DATA may also be re-
turned.
The former two interrupt the handshake procedure due to the transport
layer being interrupted, and the latter because of a "warning" alert
that was sent by the peer (it is always a good idea to check any re-
ceived alerts). On these non-fatal errors call this function again, un-
til it returns 0; cf. gnutls_record_get_direction() and gnutls_er-
ror_is_fatal(). In DTLS sessions the non-fatal error
GNUTLS_E_LARGE_PACKET is also possible, and indicates that the MTU
should be adjusted.
When this function is called by a server after a rehandshake request
under TLS 1.2 or earlier the GNUTLS_E_GOT_APPLICATION_DATA error code
indicates that some data were pending prior to peer initiating the
handshake. Under TLS 1.3 this function when called after a successful
handshake, is a no-op and always succeeds in server side; in client
side this function is equivalent to gnutls_session_key_update() with
GNUTLS_KU_PEER flag.
This function handles both full and abbreviated TLS handshakes (resump-
tion). For abbreviated handshakes, in client side, the gnutls_ses-
sion_set_data() should be called prior to this function to set parame-
ters from a previous session. In server side, resumption is handled by
either setting a DB back-end, or setting up keys for session tickets.
RETURNS
GNUTLS_E_SUCCESS on a successful handshake, otherwise a negative error
code.
REPORTING BUGS
Report bugs to <bugs@gnutls.org>.
Home page: https://www.gnutls.org
COPYRIGHT
Copyright © 2001- Free Software Foundation, Inc., and others.
Copying and distribution of this file, with or without modification,
are permitted in any medium without royalty provided the copyright no-
tice and this notice are preserved.
SEE ALSO
The full documentation for gnutls is maintained as a Texinfo manual.
If the /usr/share/doc/gnutls/ directory does not contain the HTML form
visit
https://www.gnutls.org/manual/
gnutls 3.7.3 gnutls_handshake(3)
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