HttpBrowserCapabilities missing some information?

Question

I'd like to use the Request.Browser property ( HttpBrowserCapabilities class) to determine some properties of the client's system.

However I seem to run into some limitations of this class. I can't find some properties that should be relatively easy to parse from the UserAgent string, like the OS version ( Platform will only return WinNT for most Windows versions, but not Vista, XP, etc.) or whether it's x64 or not (only Win16 and Win32 properties).

I would have expected to see these properties in the HttpBrowserCapabilities class, because most other user agent information is there. Am I missing something? Can I find this information somewhere else? Or should I just parse it from the UserAgent string myself?

Answer 1

The browserCaps element is deprecated in ASP.NET 2.0 and higher. Unless you're using .NET 1 or 1.1, you should use a browser definition file instead.

Add the *App_Browsers* folder to your site, if it doesn't already exist, and create a new file called " Platforms.browser ". (The name doesn't matter; only the extension.)

Open the new .browser file and paste in the following:

<browsers>
    <gateway id="PlatformWinVista" parentID="PlatformWinnt">
        <identification>
            <userAgent match="Windows NT 6\.0" />
        </identification>
        <capabilities>
            <capability name="platform" value="Windows Vista" />
        </capabilities>
    </gateway>

    <gateway id="PlatformWin7" parentID="PlatformWinnt">
        <identification>
            <userAgent match="Windows NT 6\.1" />
        </identification>
        <capabilities>
            <capability name="platform" value="Windows 7" />
        </capabilities>
    </gateway>
</browsers>

You might need to trigger a recompilation of the site for the new file to take effect.

NB: These nodes have to be gateway nodes rather than browser nodes. If you try to create them as browser nodes, you'll get a parser error when your site recompiles .

Answer 2

You can extend the HttpBrowserCapabilities by adding/extending the browserCaps configuration section in your machine.config/web.config file. For example, to detect the OS version more accurately, add something like this to your config file:

<system.web>
    <browserCaps>
      <use var="HTTP_USER_AGENT" />
      <filter>
        <case match="Windows NT 6.1">
          platform=Windows7
        </case>
      </filter>
    </browserCaps>
  </system.web>

If you access the web site with Mozilla running on windows 7 (UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1") you'll see that Request.Browser.Platform will display "Windows7". See here for more information: http://msdn.microsoft.com/en-us/library/sk9az15a%28v=vs.71%29.aspx

Add a regex in the browserCaps section to match the WOW64 string in order to detect whether the client platform is 64 bit (I'm not sure what the WOW64-equivalent is for non-Windows platforms running on 64 bit).

...Of course, by using a regex in the element you're doing nothing else than actually parsing the UserAgent string yourself. However you can easily find predefined browseCaps on the web (eg http://owenbrady.net/browsercaps/CodeProject.xml ).

Keep in mind that even though this capability is quite powerful, it still is not 100% accurate. For example, both Windows 7 and Windows Server 2008 R2 will return Windows NT 6.1 as the platform.