.net - 删除期望 : 100-continue from basicHttpBinding

Question

我想删除由 basicHttpBinding 中使用的基础 HttpWebRequest 添加的 Expect: 100-continue header 。我知道只需将 ServicePointManager.Expect100Continue 设置为 false 的选项。然而，这种方法的问题在于它是全局的，即它适用于进程中发起的所有 Web 请求。我想将其范围限制为特定的 WCF 代理。使用 ASMX 代理，这过去很容易 - 我将简单地子类化生成的代理，它是 SoapHttpClientProtocol 的子类并覆盖 GetWebRequest。然后我将调用基本实现并在返回的 Web 请求对象上设置 Expect100Continue。

我正在尝试对 WCF 应用类似的方法，但无法完全找到一种方法来“拦截”由传输 channel 创建的 HttpWebRequest。这可能吗？

Answer 1

对于 System.ServiceModel.Http 4.5，我们可以创建一个自定义的 BasicHttpBinding，在 HttpClient 中注入(inject)一个 HttpMessageHandler > 管道:

class CustomHttpBinding: BasicHttpBinding
{
    public override BindingElementCollection CreateBindingElements()
    {
        var elements =  base.CreateBindingElements();
        var transport = elements.Find<HttpsTransportBindingElement>();
        if (transport != null)
        {
            elements.Remove(transport);
            elements.Add(CustomHttpsTransportBindingElement.CreateFromHttpsTransportBindingElement(transport));
        }
        return elements;
    }       
}

class CustomHttpsTransportBindingElement: HttpsTransportBindingElement
{
    private Func<HttpClientHandler, HttpMessageHandler> _createDelegatingHandler = client => new CustomHttpMessageHandler(client);
    public override IChannelFactory<TChannel> BuildChannelFactory<TChannel>(BindingContext context)
    {            
        context.BindingParameters.Add(_createDelegatingHandler);
        return base.BuildChannelFactory<TChannel>(context);
    }        

    public override BindingElement Clone()
    {
        return CreateFromHttpsTransportBindingElement(this);
    }

    public static CustomHttpsTransportBindingElement CreateFromHttpsTransportBindingElement(HttpsTransportBindingElement from)
    {
        return new CustomHttpsTransportBindingElement
        {
            AllowCookies = from.AllowCookies,
            AuthenticationScheme = from.AuthenticationScheme,
            BypassProxyOnLocal = from.BypassProxyOnLocal,
            ManualAddressing = from.ManualAddressing,
            MaxBufferSize = from.MaxBufferSize,
            MaxReceivedMessageSize = from.MaxReceivedMessageSize,
            ProxyAddress = from.ProxyAddress,
            ProxyAuthenticationScheme = from.ProxyAuthenticationScheme,
            RequireClientCertificate = from.RequireClientCertificate,
            TransferMode = from.TransferMode,
            UseDefaultWebProxy = from.UseDefaultWebProxy,
            WebSocketSettings = from.WebSocketSettings
        };
    }
}

class CustomHttpMessageHandler: DelegatingHandler
{
    public CustomHttpMessageHandler(HttpMessageHandler innerHandler): base(innerHandler)
    {            
    }
    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        request.Headers.ExpectContinue = false;
        return base.SendAsync(request, cancellationToken);
    }
}

如果您不使用 HTTPS，请覆盖 HttpTransportBindingElement 而不是 HttpsTransportBindingElement