c# - AppDomain 证据没有区域？

Question

什么在控制当前应用程序域的证据？

var evidence = Thread.GetDomain().Evidence;

什么控制它是空还是非空，什么决定它的内容？

当我的应用程序从域证据查询这些主机证据对象时

var z = evidence.GetHostEvidence<Zone> 
var p = evidence.GetHostEvidence<Publisher>
var s = evidence.GetHostEvidence<Site>
var n = evidence.GetHostEvidence<StrongName>
var u = evidence.GetHostEvidence<Url>

在某些环境中执行时，它们有时似乎全部为空。我之所以相信这是在 IsolatedStorage._GetAccountingInfo(...) 内部抛出的异常，通过查看反射器中的代码可以清楚地看出，只有在域证据包含 null 时才会抛出此异常对于所有上述主机证据对象。这将导致隔离存储无法初始化。

不幸的是，我无法在我自己的系统上重现它。例如，区域值始终是一个正确的值，表示“我的电脑”，所以我正在努力解决这个问题。

什么控制 Windows 窗体桌面应用程序的默认应用程序域中这些值的内容？

Answer 1

当您的代码是 COM object accessed by a native Win32 application 时，会发生类似的情况(默认 AppDomain 的 Evidence 为空)，或者加载时 run inside of the command line version of PowerShell.exe 。我在使用 OpenXML(特别是 EPPlus )程序集时遇到了这个问题，当 Office 文档超过一定的文件大小时，该程序集使用isolatedStorage。

我更喜欢使用反射来处理当前的 AppDomain，而不是在默认的 AppDomain 内部旋转另一个 AppDomain 并处理额外级别的编码/远程处理。的证据。

这是 C# 中的概念证明:

using System;

namespace AppDomainEvidence
{
    class Program
    {
        static void Main(string[] args)
        {
            var initialAppDomainEvidence = System.Threading.Thread.GetDomain().Evidence; // Setting a breakpoint here will let you inspect the current AppDomain's evidence
            try
            {
                var usfdAttempt1 = System.IO.IsolatedStorage.IsolatedStorageFile.GetUserStoreForDomain(); // This will fail when the current AppDomain Evidence is instantiated via COM or in PowerShell
            }
            catch (Exception e)
            {
                // Set breakpoint here to inspect Exception "e"
            }

            // Create a new Evidence that include the MyComputer zone
            var replacementEvidence = new System.Security.Policy.Evidence();
            replacementEvidence.AddHostEvidence(new System.Security.Policy.Zone(System.Security.SecurityZone.MyComputer));

            // Replace the current AppDomain's evidence using reflection
            var currentAppDomain = System.Threading.Thread.GetDomain();
            var securityIdentityField = currentAppDomain.GetType().GetField("_SecurityIdentity", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic);
            securityIdentityField.SetValue(currentAppDomain,replacementEvidence);

            var latestAppDomainEvidence = System.Threading.Thread.GetDomain().Evidence; // Setting a breakpoint here will let you inspect the current AppDomain's evidence

            var usfdAttempt2 = System.IO.IsolatedStorage.IsolatedStorageFile.GetUserStoreForDomain(); // This should work
        }
    }
}

这是我在 PowerShell 中实现的解决方法:

# This one will fail
$usfd = [System.IO.IsolatedStorage.IsolatedStorageFile]::GetUserStoreForDomain()

# Inspect the current AppDomain's Evidence
[threading.thread]::GetDomain().Evidence


# Modify the current AppDomain's Evidence
$evidence = new-object System.Security.Policy.Evidence
$zone = new-object System.Security.Policy.Zone('MyComputer')
$evidence.AddHost($zone)
$currentAppDomain = [threading.thread]::GetDomain()
$securityIdentityField=$currentAppDomain.GetType().GetField('_SecurityIdentity','Instance,NonPublic')
$securityIdentityField.SetValue($currentAppDomain, $evidence)

# Inspect the current AppDomain's Evidence
[threading.thread]::GetDomain().Evidence

# This one will succeed
$usfd = [System.IO.IsolatedStorage.IsolatedStorageFile]::GetUserStoreForDomain()