    #
    # Copyright (c) 2016-2018 Varnish Cache project
    # Copyright (c) 2012-2016 Varnish Software AS
    #
    # 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.
    #
    # detectdevice.vcl - regex based device detection for Varnish
    # https://github.com/varnishcache/varnish-devicedetect/
    #
    # Original author: Lasse Karstensen <lkarsten@varnish-software.com>

    sub devicedetect {
    	unset req.http.X-UA-Device;
    	set req.http.X-UA-Device = "pc";

    	# Handle that a cookie may override the detection alltogether.
    	if (req.http.Cookie ~ "(?i)X-UA-Device-force") {
    		/* ;?? means zero or one ;, non-greedy to match the first. */
    		set req.http.X-UA-Device = regsub(req.http.Cookie, "(?i).*X-UA-Device-force=([^;]+);??.*", "\1");
    		/* Clean up our mess in the cookie header */
    		set req.http.Cookie = regsuball(req.http.Cookie, "(^|; ) *X-UA-Device-force=[^;]+;? *", "\1");
    		/* If the cookie header is now empty, or just whitespace, unset it. */
    		if (req.http.Cookie ~ "^ *$") { unset req.http.Cookie; }
    	} else {
            if (req.http.User-Agent ~ "\(compatible; Googlebot-Mobile/2.1; \+http://www.google.com/bot.html\)" ||
                (req.http.User-Agent ~ "(Android|iPhone)" && req.http.User-Agent ~ "\(compatible.?; Googlebot/2.1.?; \+http://www.google.com/bot.html") ||
    			(req.http.User-Agent ~ "(iPhone|Windows Phone)" && req.http.User-Agent ~ "\(compatible; bingbot/2.0; \+http://www.bing.com/bingbot.htm")) {
                set req.http.X-UA-Device = "mobile-bot"; }
    		elsif (req.http.User-Agent ~ "(?i)(ads|google|bing|msn|yandex|baidu|ro|career|seznam|)bot" ||
    		    req.http.User-Agent ~ "(?i)(baidu|jike|symantec)spider" ||
    		    req.http.User-Agent ~ "(?i)pingdom" ||
    		    req.http.User-Agent ~ "(?i)facebookexternalhit" ||
    		    req.http.User-Agent ~ "(?i)scanner" ||
    		    req.http.User-Agent ~ "(?i)slurp" ||
    		    req.http.User-Agent ~ "(?i)(web)crawler") {
    			set req.http.X-UA-Device = "bot"; }
    		elsif (req.http.User-Agent ~ "(?i)ipad")        { set req.http.X-UA-Device = "tablet-ipad"; }
    		elsif (req.http.User-Agent ~ "(?i)ip(hone|od)") { set req.http.X-UA-Device = "mobile-iphone"; }
    		/* how do we differ between an android phone and an android tablet?
    		   http://stackoverflow.com/questions/5341637/how-do-detect-android-tablets-in-general-useragent */
    		elsif (req.http.User-Agent ~ "(?i)android.*(mobile|mini)") { set req.http.X-UA-Device = "mobile-android"; }
    		// android 3/honeycomb was just about tablet-only, and any phones will probably handle a bigger page layout.
    		elsif (req.http.User-Agent ~ "(?i)android 3")              { set req.http.X-UA-Device = "tablet-android"; }
    		/* Opera Mobile */
    		elsif (req.http.User-Agent ~ "Opera Mobi")                  { set req.http.X-UA-Device = "mobile-smartphone"; }
    		// May very well give false positives towards android tablets. Suggestions welcome.
    		elsif (req.http.User-Agent ~ "(?i)android")         { set req.http.X-UA-Device = "tablet-android"; }
    		elsif (req.http.User-Agent ~ "PlayBook; U; RIM Tablet")         { set req.http.X-UA-Device = "tablet-rim"; }
    		elsif (req.http.User-Agent ~ "hp-tablet.*TouchPad")         { set req.http.X-UA-Device = "tablet-hp"; }
    		elsif (req.http.User-Agent ~ "Kindle/3")         { set req.http.X-UA-Device = "tablet-kindle"; }
    		elsif (req.http.User-Agent ~ "Touch.+Tablet PC" ||
    		    req.http.User-Agent ~ "Windows NT [0-9.]+; ARM;" ) {
    		        set req.http.X-UA-Device = "tablet-microsoft";
    		}
    		elsif (req.http.User-Agent ~ "Mobile.+Firefox")     { set req.http.X-UA-Device = "mobile-firefoxos"; }
    		elsif (req.http.User-Agent ~ "^HTC" ||
    		    req.http.User-Agent ~ "Fennec" ||
    		    req.http.User-Agent ~ "IEMobile" ||
    		    req.http.User-Agent ~ "BlackBerry" ||
    		    req.http.User-Agent ~ "BB10.*Mobile" ||
    		    req.http.User-Agent ~ "GT-.*Build/GINGERBREAD" ||
    		    req.http.User-Agent ~ "SymbianOS.*AppleWebKit") {
    			set req.http.X-UA-Device = "mobile-smartphone";
    		}
    		elsif (req.http.User-Agent ~ "(?i)symbian" ||
    		    req.http.User-Agent ~ "(?i)^sonyericsson" ||
    		    req.http.User-Agent ~ "(?i)^nokia" ||
    		    req.http.User-Agent ~ "(?i)^samsung" ||
    		    req.http.User-Agent ~ "(?i)^lg" ||
    		    req.http.User-Agent ~ "(?i)bada" ||
    		    req.http.User-Agent ~ "(?i)blazer" ||
    		    req.http.User-Agent ~ "(?i)cellphone" ||
    		    req.http.User-Agent ~ "(?i)iemobile" ||
    		    req.http.User-Agent ~ "(?i)midp-2.0" ||
    		    req.http.User-Agent ~ "(?i)u990" ||
    		    req.http.User-Agent ~ "(?i)netfront" ||
    		    req.http.User-Agent ~ "(?i)opera mini" ||
    		    req.http.User-Agent ~ "(?i)palm" ||
    		    req.http.User-Agent ~ "(?i)nintendo wii" ||
    		    req.http.User-Agent ~ "(?i)playstation portable" ||
    		    req.http.User-Agent ~ "(?i)portalmmm" ||
    		    req.http.User-Agent ~ "(?i)proxinet" ||
    		    req.http.User-Agent ~ "(?i)windows\ ?ce" ||
    		    req.http.User-Agent ~ "(?i)winwap" ||
    		    req.http.User-Agent ~ "(?i)eudoraweb" ||
    		    req.http.User-Agent ~ "(?i)htc" ||
    		    req.http.User-Agent ~ "(?i)240x320" ||
    		    req.http.User-Agent ~ "(?i)avantgo") {
    			set req.http.X-UA-Device = "mobile-generic";
    		}
    	}
    }