无法在响应中添加"Vary"标头

Question

我正在尝试为Vary: Accept-Encoding我压缩的文件添加一个标头,如前所述.

但是,由于某种原因,无法从Visual Studio测试服务器或IIS服务器进行此操作.

我有以下代码:

if (url.Contains(".js") || url.Contains(".aspx") || url.Contains(".css"))
{
    app.Response.AppendHeader("Vary", "Accept-Encoding");
    app.Response.AppendHeader("Varye", "Accept-Encoding"); // for testing
    app.Response.AppendHeader("Varye", "Accept-Things");   // for testing
    app.Response.AppendHeader("Vary", "Accept-Stuff");     // for testing
    app.Response.AppendHeader("Var", "Accept-Items");      // for testing

    encodings = encodings.ToLower();

    if (encodings.Contains("gzip") || encodings == "*")
    {
        app.Response.Filter = new GZipStream(baseStream, CompressionMode.Compress);
        app.Response.AppendHeader("Content-Encoding", "gzip");

    }
}

这导致以下响应头:

Status=OK - 200
Server=ASP.NET Development Server/10.0.0.0
Date=Fri, 21 Oct 2011 12:24:11 GMT
X-AspNet-Version=4.0.30319
Varye=Accept-Encoding, Accept-Things
Var=Accept-Items
Content-Encoding=gzip
Cache-Control=public
Etag="1CC8F2E9D772300"
Content-Type=text/css
Content-Length=16200
Connection=Close

如您所见,Vary标题不存在.存在具有类似语法的无意义标头,因此必须有某些东西,在发送之前取出Vary标头.

我不知道它是否相关,但这里是我在web.config中定义压缩模块的地方:

<httpModules>
    <add name="CompressionModule" type="Utility.HttpCompressionModule"/>
</httpModules>

(其中Utility.HttpCompressionModule是我上面提供的代码摘录所属的类.)

为什么我不能添加Vary标题？

编辑: Eric C的解决方案给我留下了这样的代码:

if (url.Contains(".js") || url.Contains(".aspx") || url.Contains(".css"))
{
    app.Response.Cache.SetVaryByCustom("Accept-Encoding");

    encodings = encodings.ToLower();

    if (encodings.Contains("gzip") || encodings == "*")
    {
        app.Response.Filter = new GZipStream(baseStream, CompressionMode.Compress);
        app.Response.AppendHeader("Content-Encoding", "gzip");

    }

但是,标题看起来像这样:

Status=OK - 200
Server=ASP.NET Development Server/10.0.0.0
Date=Mon, 24 Oct 2011 09:26:37 GMT
Content-Encoding=gzip
Cache-Control=public
Etag="1CC7A09FDE77300"
Vary=*
Content-Type=application/x-javascript
Content-Length=44447
Connection=Close

(不知道为什么这是application/x-javascriptHTML中的设置text/javascript,但这是无关紧要的.)

正如您所看到的,我现在有一个不同的标题,但它被设置为Vary=*而不是Vary=Accept-Encoding像您在压缩模块中的代码所期望的那样.

这里发生了什么？如何Vary正确设置标头？

第二次编辑: 我要粘贴整个类的源代码.它没有比我已发布的更多,但它可能有助于准确掌握我正在做的事情:

public class HttpCompressionModule : IHttpModule
{
    /// <summary>
    /// Initializes a new instance of the <see cref="AjaxHttpCompressionModule"/> class.
    /// </summary>
    public HttpCompressionModule()
    {
    }

    #region IHttpModule Members

    /// <summary>
    /// Disposes of the resources (other than memory) used by the module that implements <see cref="T:System.Web.IHttpModule"/>.
    /// </summary>
    void IHttpModule.Dispose()
    {

    }

    /// <summary>
    /// Initializes a module and prepares it to handle requests.
    /// </summary>
    /// <param name="context">An <see cref="T:System.Web.HttpApplication"/> that provides access to the methods, properties, and events common to all application objects within an ASP.NET application</param>
    void IHttpModule.Init(HttpApplication context)
    {
        context.BeginRequest += (new EventHandler(this.context_BeginRequest));
    }

    #endregion

    /// <summary>
    /// Handles the BeginRequest event of the context control.
    /// </summary>
    /// <param name="sender">The source of the event.</param>
    /// <param name="e">The <see cref="System.EventArgs"/> instance containing the event data.</param>
    void context_BeginRequest(object sender, EventArgs e)
    {            
        HttpApplication app = (HttpApplication)sender;
        string encodings = app.Request.Headers.Get("Accept-Encoding");
        Stream baseStream = app.Response.Filter;


        if (string.IsNullOrEmpty(encodings))
            return;


        string url = app.Request.RawUrl.ToLower();

        if (url.Contains(".js") || url.Contains(".css") || url.Contains("ajax.ashx"))
        {
            app.Response.Cache.SetVaryByCustom("Accept-Encoding");

            encodings = encodings.ToLower();

            if (encodings.Contains("gzip") || encodings == "*")
            {
                app.Response.Filter = new GZipStream(baseStream, CompressionMode.Compress);
                app.Response.AppendHeader("Content-Encoding", "gzip");

            }
            else if (encodings.Contains("deflate"))
            {
                app.Response.Filter = new DeflateStream(baseStream, CompressionMode.Compress);
                app.Response.AppendHeader("Content-Encoding", "deflate");
            }
        }
    }
}

此外,这是我的web.config文件的System.Web部分:

<system.web>
    <!--<compilation debug="true"></compilation>-->
    <trace enabled="true" traceMode="SortByTime"/>
    <httpRuntime executionTimeout="180"/>
    <globalization culture="en-GB" uiCulture="en-GB"/>
    <!-- custom errors-->
    <customErrors mode="Off">
    </customErrors>
    <!-- Membership -->
    <membership defaultProvider="SqlProvider" userIsOnlineTimeWindow="15">
        <providers>
            <clear/>
            <add name="SqlProvider" type="System.Web.Security.SqlMembershipProvider" connectionStringName="SQLServerAuth" applicationName="mycompany" minRequiredPasswordLength="4" minRequiredNonalphanumericCharacters="0" enablePasswordRetrieval="false" enablePasswordReset="true" requiresQuestionAndAnswer="false" requiresUniqueEmail="true" passwordFormat="Hashed" maxInvalidPasswordAttempts="1024"/>
        </providers>
    </membership>
    <!-- Roles -->
    <roleManager enabled="true" cacheRolesInCookie="true" defaultProvider="SqlProvider">
        <providers>
            <clear/>
            <add connectionStringName="SQLServerAuth" applicationName="mycompany" name="SqlProvider" type="System.Web.Security.SqlRoleProvider"/>
        </providers>
    </roleManager>
    <!-- Authentication -->
    <anonymousIdentification enabled="false"/>
    <authentication mode="Forms">
        <forms name=".AUTH" protection="All" timeout="2" path="/">
        </forms>
    </authentication>
    <httpModules>
        <add name="CompressionModule" type="Utility.HttpCompressionModule"/>
    </httpModules>
</system.web>

没有更多的话要说.我所知道的,没有其他非标准的东西我们正在使用该网站.有任何想法吗？

Answer 1

从IIS 7.5开始,Vary标头被gzip IIS过滤器(gzip.dll)覆盖,该过滤器实现了DyanamicCompressionModule.无论ASP.NET代码中的更改如何,过滤器始终将标头设置为"Vary:Accept-Encoding".截至今天,唯一的解决方法是禁用动态内容的压缩,然后在代码中实现它.这是如何做:

1. 从Web.config中删除以下行:

   <add name="CompressionModule" type="Utility.HttpCompressionModule"/>

2. 然后转到IIS管理控制台并确保未对动态内容启用压缩.

3. Global.asax.cs方法HttpApplication.Application_BeginRequest:手动实现压缩:

   protected void Application_BeginRequest(object sender, EventArgs e)
   {
       HttpContext context = HttpContext.Current;
       context.Response.Filter 
          = new GZipStream(context.Response.Filter, CompressionMode.Compress);
       context.Response.AppendHeader("Content-Encoding", "gzip");
       context.Response.Cache.VaryByHeaders["Accept-Encoding"] = true;

       // We can now set additional Vary headers...
       context.Response.Cache.VaryByHeaders.UserAgent = true;
       context.Response.Cache.VaryByHeaders["X-Requested-With"] = true;
   }

这是最近向Microsoft报告的问题.

Answer 2

正如其他人提到的，这是IIS 压缩模块专门覆盖标头的一个已知问题Vary，并已通过修补程序解决。

如果您无法确保安装了修补程序，则另一种解决方法是在 Web.config 中使用IIS URL 重写附加标头：

<configuration>
  <system.webServer>
    <rewrite>
      <outboundRules>
        <rule name="Append 'Vary: X-Requested-With' header" patternSyntax="ECMAScript">
          <match serverVariable="RESPONSE_VARY" pattern=".+" />
          <action type="Rewrite" value="{R:0}, X-Requested-With" replace="true" />
        </rule>
        <rule name="Set 'Vary: X-Requested-With' header if no others" patternSyntax="ECMAScript">
          <match serverVariable="RESPONSE_VARY" pattern=".+" negate="true" />
          <action type="Rewrite" value="X-Requested-With" />
        </rule>
      </outboundRules>
    </rewrite>
  </system.webServer>
</configuration>