NAME

       vmod_h2 - Module to control the built-in HTTP2 transport

SYNOPSIS

          import h2 [as name] [from "path"]

          BOOL is()

          DURATION rapid_reset([DURATION threshold])

          INT rapid_reset_limit([INT number])

          DURATION rapid_reset_period([DURATION duration])

          REAL rapid_reset_budget()

DESCRIPTION

       This VMOD contains functions to control the HTTP2 transport built into Varnish-Cache.

   BOOL is()
       Restricted to: client.

       Returns true when called on a session handled by the built-in HTTP2 transport.

   DURATION rapid_reset([DURATION threshold])
       Restricted to: client.

       Get  and  optionally  set  the  h2_rapid_reset  parameter (See varnishd(1)) for this HTTP2
       session only.

       Returns -1 when used outside the HTTP2 transport. Otherwise returns the previous value.

       If the call leads to a change in the rate limit parameters, the current budget as  retuned
       by h2.rapid_reset_budget() is reset.

   INT rapid_reset_limit([INT number])
       Restricted to: client.

       Get and optionally set the h2_rapid_reset_limit parameter (See varnishd(1)) for this HTTP2
       session only.

       Returns -1 when used outside the HTTP2 transport. Otherwise returns the previous value.

       If the call leads to a change in the rate limit parameters, the current budget as  retuned
       by h2.rapid_reset_budget() is reset.

   DURATION rapid_reset_period([DURATION duration])
       Restricted to: client.

       Get  and  optionally  set  the  h2_rapid_reset_period parameter (See varnishd(1)) for this
       HTTP2 session only.

       Returns -1 when used outside the HTTP2 transport. Otherwise returns the previous value.

       If the call leads to a change in the rate limit parameters, the current budget as  retuned
       by h2.rapid_reset_budget() is reset.

   REAL rapid_reset_budget()
       Restricted to: client.

       Return  how  many  RST  frames  classified  as "rapid" the client is still allowed to send
       before the session is going to be closed.

SEE ALSO

       • varnishd(1)

       • vsl(7)

COPYRIGHT

          Copyright 2023 UPLEX - Nils Goroll Systemoptimierung
          All rights reserved.

          Author: Nils Goroll <nils.goroll@uplex.de>

          SPDX-License-Identifier: BSD-2-Clause

          Redistribution and use in source and binary forms, with or without
          modification, are permitted provided that the following conditions
          are met:
          1. Redistributions of source code must retain the above copyright
             notice, this list of conditions and the following disclaimer.
          2. Redistributions in binary form must reproduce the above copyright
             notice, this list of conditions and the following disclaimer in the
             documentation and/or other materials provided with the distribution.

          THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
          ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
          IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
          ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
          FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
          DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
          OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
          HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
          LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
          OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
          SUCH DAMAGE.

                                                                                       VMOD_H2(3)