要的HttpModule头添加请求 [英] HttpModule to add headers to request

问题描述

这似乎是一个简单的操作。

This seems like a simple operation.

我们有必要在我们的开发环境（在XP / IIS 5上运行），以一些头添加到每个Htt的prequest在我们的应用程序到达。 （这是为了模拟生产环境，我们没有在dev的可用）。乍一看，这似乎是一个简单的HttpModule，沿着线：

We have a need in our development environment (running on XP/IIS 5) to add some headers into each HttpRequest arriving at our application. (This is to simulate a production environment that we don't have available in dev). At first blush, this seemed like a simple HttpModule, along the lines of:

public class Dev_Sim: IHttpModule
{
    public void Init(HttpApplication app)
    {
        app.BeginRequest += delegate { app.Context.Request.Headers.Add("UserName", "XYZZY"); };
    }

    public void Dispose(){}
}

但在试图做到这一点，我发现请求的标题集合是只读的，而Add方法失败，出现OperationNotSupported例外。

But on trying to do that, I find that the Headers collection of the Request is read-only, and the Add method fails with an OperationNotSupported exception.

花费一两个小时在谷歌研究这个，我来了没有简单的答案是什么应该是一个比较直接的问题。

Spending a couple hours researching this on Google, I've come up with no easy answer to what should be a relatively straight-forward problem.

有没有人有任何指针？

推荐答案

好吧，与同事和一些实验的协助下，我发现，这可能与一些保护属性和方法，通过反射访问的协助下完成

Okay, with the assistance of a co-worker and some experimentation, I found that this can be done with the assistance of some protected properties and methods accessed through reflection:

var headers = app.Context.Request.Headers;
Type hdr = headers.GetType();
PropertyInfo ro = hdr.GetProperty("IsReadOnly", 
    BindingFlags.Instance | BindingFlags.NonPublic | BindingFlags.IgnoreCase | BindingFlags.FlattenHierarchy);
// Remove the ReadOnly property
ro.SetValue(headers, false, null);
// Invoke the protected InvalidateCachedArrays method 
hdr.InvokeMember("InvalidateCachedArrays", 
    BindingFlags.InvokeMethod | BindingFlags.NonPublic | BindingFlags.Instance, 
    null, headers, null);
// Now invoke the protected "BaseAdd" method of the base class to add the
// headers you need. The header content needs to be an ArrayList or the
// the web application will choke on it.
hdr.InvokeMember("BaseAdd", 
    BindingFlags.InvokeMethod | BindingFlags.NonPublic | BindingFlags.Instance, 
    null, headers, 
    new object[] { "CustomHeaderKey", new ArrayList {"CustomHeaderContent"}} );
// repeat BaseAdd invocation for any other headers to be added
// Then set the collection back to ReadOnly
ro.SetValue(headers, true, null);

这工作对我来说，至少。

This works for me, at least.

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