WCF请求过代理返回407 Proxy Authentication Required错误的解决方案

解决方案 #

经过长时间排查，我找到了可行的解决方案。截至2021年10月19日，System.ServiceModel.***包的最新稳定版本为4.8.1，而4.9.0的候选发布版本恰好可以解决此问题。
我查阅.NET WCF的GitHub源代码，找到了该候选版本（版本号4.9.0-rc1.21431.2）正好匹配需求。开发团队更新了HttpTransportBindingElement，新增了Proxy属性。虽然它不是稳定版本，但完全可以满足需求。借助该属性我成功解决了问题，实现代码如下：

using (var myWsdlClient = new MyWsdlGeneratedClient())
{
    var binding = myWsdlClient.Endpoint.Binding as BasicHttpBinding;
    var customBinding = new CustomBinding(binding);

    var htbe = customBinding.Elements.Find<HttpTransportBindingElement>();
    htbe.AuthenticationScheme = AuthenticationSchemes.Basic;
    htbe.ProxyAuthenticationScheme = AuthenticationSchemes.Basic;
    htbe.UseDefaultWebProxy = false;
    htbe.BypassProxyOnLocal = false;
    htbe.Proxy = new WebProxy
    {
        Address = new Uri("http://myproxyaddress.com:8080"),
        /* 代理凭据 */
        Credentials = new NetworkCredential("MyProxyUserName", "MyProxyPassword"),
        BypassProxyOnLocal = false
    };

    myWsdlClient.Endpoint.Binding = customBinding;

    /* 客户端凭据 */
    myWsdlClient.ClientCredentials.UserName.UserName = "MyClientUserName";
    myWsdlClient.ClientCredentials.UserName.Password = "MyClientPassword";

    /* 发送请求 */
    myWsdlClient.Endpoint.Address = new EndpointAddress("https://myclientaddress.com");
    myWsdlClient.doSomeAction(actionRequest); // <-- 运行成功！
}

原始问题 #

我尝试通过Web代理发送WCF服务请求时，收到错误提示“Remote Server returned an error: (407) Proxy Authentication Required”。我已经通过WSDL生成了代理类，在app.config中配置了绑定和端点等内容（使用的是BasicHttpBinding）。问题在于：客户端和代理都需要Basic Authentication认证，但我只能配置客户端凭据，无法单独配置代理的凭据。
我已经尝试过以下方案：

• 方案1：我在网上看到可以把凭据直接放到代理的URL中，所以我通过代码配置了绑定的ProxyAddress属性，实现代码如下：

using (var myWsdlClient = new MyWsdlGeneratedClient())
{
    var binding = myWsdlClient.Endpoint.Binding as BasicHttpBinding;

    /* 客户端凭据 */
    binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.Basic;
    myWsdlClient.ClientCredentials.UserName.UserName = "MyClientUserName";
    myWsdlClient.ClientCredentials.UserName.Password = "MyClientPassword";

    /* 代理凭据 */
    binding.Security.Transport.ProxyCredentialType = HttpProxyCredentialType.Basic;
    binding.UseDefaultWebProxy = false;
    binding.BypassProxyOnLocal = false;
    binding.ProxyAddress = new Uri("http://MyProxyUserName:MyProxyPassword@myproxyaddress.com:8080");

    /* 发送请求 */
    myWsdlClient.Endpoint.Address = new EndpointAddress("https://myclientaddress.com");
    myWsdlClient.doSomeAction(actionRequest); // <-- 此处抛出错误，内部异常为407 HTTP响应
}

• 方案2：我也尝试过修改默认Web代理，该方法可以正常运行，实现代码如下：

using (var myWsdlClient = new MyWsdlGeneratedClient())
{
    var binding = myWsdlClient.Endpoint.Binding as BasicHttpBinding;

    /* 客户端凭据 */
    binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.Basic;
    myWsdlClient.ClientCredentials.UserName.UserName = "MyClientUserName";
    myWsdlClient.ClientCredentials.UserName.Password = "MyClientPassword";

    /* 代理凭据 */
    binding.Security.Transport.ProxyCredentialType = HttpProxyCredentialType.Basic;
    binding.UseDefaultWebProxy = true;
    binding.BypassProxyOnLocal = false;

    var defaultProxyBefore = WebRequest.DefaultWebProxy;
    var newProxy = new WebProxy
    {
        Address = new Uri("http://myproxyaddress.com:8080"),
        Credentials = new NetworkCredential("MyProxyUserName", "MyProxyPassword"),
        BypassProxyOnLocal = false
    };
    WebRequest.DefaultWebProxy = newProxy;

    /* 发送请求 */
    myWsdlClient.Endpoint.Address = new EndpointAddress("https://myclientaddress.com");
    try
    {
        myWsdlClient.doSomeAction(actionRequest);
    }
    finally
    {
        WebRequest.DefaultWebProxy = defaultProxyBefore;
    }
}

第二种方案虽然可以正常运行，但不符合项目需求。我开发的应用每秒要处理多线程下的大量请求，部分请求需要走默认代理，我不希望无关请求走我临时设置的新代理，它们应该继续使用默认配置。
总结来看，我需要实现单请求独立配置代理，同时支持客户端和代理的双Basic Authentication认证。我对WCF不太熟悉，偶然了解到自定义绑定的概念，看起来可以解决问题，但我还没找到具体实现方法，希望能得到相关帮助。

内容的提问来源于stack exchange，提问作者jaw64