add callback handler for setting DTLS timer interval

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
(Merged from https://github.com/openssl/openssl/pull/4011)

1 files changed, 40 insertions, 0 deletions

diff --git a/doc/man3/DTLS_set_timer_cb.pod b/doc/man3/DTLS_set_timer_cb.pod
new file mode 100644
index 0000000000..6e1347213e
--- /dev/null
+++ b/doc/man3/DTLS_set_timer_cb.pod
@@ -0,0 +1,40 @@
+=pod
+
+=head1 NAME
+
+DTLS_timer_cb,
+DTLS_set_timer_cb
+- Set callback for controlling DTLS timer duration
+
+=head1 SYNOPSIS
+
+ #include <openssl/ssl.h>
+
+ typedef unsigned int (*DTLS_timer_cb)(SSL *s, unsigned int timer_us);
+
+ void DTLS_set_timer_cb(SSL *s, DTLS_timer_cb cb);
+
+=head1 DESCRIPTION
+
+This function sets an optional callback function for controlling the
+timeout interval on the DTLS protocol. The callback function will be
+called by DTLS for every new DTLS packet that is sent.
+
+=head1 RETURN VALUES
+
+Returns void.
+
+=head1 HISTORY
+
+This function was added in OpenSSL 1.1.1
+
+=head1 COPYRIGHT
+
+Copyright 2017 The OpenSSL Project Authors. All Rights Reserved.
+
+Licensed under the OpenSSL license (the "License").  You may not use
+this file except in compliance with the License.  You can obtain a copy
+in the file LICENSE in the source distribution or at
+L<https://www.openssl.org/source/license.html>.
+
+=cut