gnutls_handshake(3) — Linux manual page


gnutls_handshake(3)                gnutls                gnutls_handshake(3)

NAME         top

       gnutls_handshake - API function

SYNOPSIS         top

       #include <gnutls/gnutls.h>

       int gnutls_handshake(gnutls_session_t session);

ARGUMENTS         top

       gnutls_session_t session
                   is a gnutls_session_t type.

DESCRIPTION         top

       This function performs the handshake of the TLS/SSL protocol, and
       initializes the TLS session parameters.

       The non-fatal errors expected by this function are:
       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 returned.

       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
       received alerts). On these non-fatal errors call this function again,
       until it returns 0; cf.  gnutls_record_get_direction() and
       gnutls_error_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
       (resumption).  For abbreviated handshakes, in client side, the
       gnutls_session_set_data() should be called prior to this function to
       set parameters 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         top

       GNUTLS_E_SUCCESS on a successful handshake, otherwise a negative
       error code.

REPORTING BUGS         top

       Report bugs to <>.
       Home page:

COPYRIGHT         top

       Copyright © 2001-2019 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
       notice and this notice are preserved.

SEE ALSO         top

       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 

COLOPHON         top

       This page is part of the GnuTLS (GnuTLS Transport Layer Security
       Library) project.  Information about the project can be found at 
       ⟨⟩.  If you have a bug report for this manual
       page, send it to  This page was obtained from the
       tarball gnutls-3.6.9.tar.xz fetched from
       ⟨⟩ on 2020-09-18.  If you discover
       any rendering problems in this HTML version of the page, or you
       believe there is a better or more up-to-date source for the page, or
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       COLOPHON (which is not part of the original manual page), send a mail

gnutls                              3.6.9                gnutls_handshake(3)