14.11. Verifying that an Assembly Has Been Granted Specific Permissions
Problem
When your assembly requests
optional permissions (such as asking for disk access to enable users
to export data to disk as a product feature) using the
SecurityAction.RequestOptional
flag, it might or
might not get those permissions. Regardless, your assembly will still
load and execute. You need a way to verify whether your assembly
actually obtained those permissions. This can help prevent many
security exceptions from being thrown. For example, if you optionally
requested read/write permissions on the registry, but did not receive
them, you could disable the user interface controls that are used to
read and store application settings in the registry.
Solution
Check to see if your
assembly received the optional permissions using the
SecurityManager.IsGranted
method like this:
using System; using System.Text.RegularExpressions; using System.Web; using System.Net; using System.Security; Regex regex = new Regex(@"http://www\.oreilly\.com/.*"); WebPermission webConnectPerm = new WebPermission(NetworkAccess.Connect,regex); if(SecurityManager.IsGranted(webConnectPerm)) { // connect to the oreilly site }
This code would set up a Regex
for the
O’Reilly web site and then use it to create a
WebPermission
for connecting to that site and all
sites containing the www.oreilly.com
string. We
would then check the WebPermission
against the
SecurityManager
to see whether we have the
permission to do this.
Discussion ...
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