WCF UriTemplate UrlEncode

Question

假设我想使用WCF调用一个外部的REST服务(这意味着我无法控制合同)。我有以下合同

[ServiceContract]
public interface ISomeRestApi
{
    [OperationContract]
    [WebInvoke(Method = "PUT", UriTemplate = "blablabla/{parameter1}/{parameter2}")]
    void PutSomething(string parameter1, string parameter2);
}

假设我的一个参数是正斜杠(/)

public class Test{

    [Fact]
    public void TestPutSomething()
    {
        ISomeRestApi api = CreateApi();

        //this results in the url: http://server/blablabla///someotherparam
        api.PutSomething("/", "someotherparam");

        //this also results in the url: http://server/blablabla///someotherparam
        api.PutSomething(HttpUtility.UrlEncode("/"), "someotherparam");

        //but i want: http://server/blablabla/%2F/someotherparam
    }
}

如何强制WCF UrlEncode我的UriTemplate路径参数？

Answer 1

经过大量的尝试和错误，我找到了一个非常丑陋和完全不合逻辑的解决方案。但还是..。也许这篇文章能对未来的人有所帮助。请注意，在.NET 4.5中，这个“解决方案”对我有效。我不保证它会对你有用。

问题的关键在于：

• 在.NET中将转义的正斜杠放入Uri是不可能的
• 为了与外部服务(RabbitMQ)通信，我确实需要能够在请求Url中放置%2f (即正斜杠)

下面的帖子让我走上了“正确”的方向：如何阻止System.Uri未转义正斜杠字符

我试过了文章中提出的解决方案，但是.徒劳无功

然后，经过大量的咒骂、谷歌搜索、逆向工程等等之后，我想出了以下代码：

/// <summary>
/// Client enpoint behavior that enables the use of a escaped forward slash between 2 forward slashes in a url
/// </summary>
public class EncodeForwardSlashBehavior:IEndpointBehavior
{
    public void Validate(ServiceEndpoint endpoint)
    {

    }

    public void AddBindingParameters(ServiceEndpoint endpoint, BindingParameterCollection bindingParameters)
    {

    }

    public void ApplyDispatchBehavior(ServiceEndpoint endpoint, EndpointDispatcher endpointDispatcher)
    {

    }

    public void ApplyClientBehavior(ServiceEndpoint endpoint, ClientRuntime clientRuntime)
    {
        clientRuntime.ClientMessageInspectors.Add(new ForwardSlashUrlInspector());
    }
}

/// <summary>
/// Inspector that modifies a an Url replacing /// with /%2f/
/// </summary>
public class ForwardSlashUrlInspector:IClientMessageInspector
{
    public object BeforeSendRequest(ref Message request, IClientChannel channel)
    {
        string uriString = request.Headers.To.ToString().Replace("///", "/%2f/");
        request.Headers.To = new Uri(uriString);
        AddAllowAnyOtherHostFlagToHttpUriParser();

        return null;
    }

    /// <summary>
    /// This is one of the weirdest hacks I ever had to do, so no guarantees can be given to this working all possible scenarios
    /// What this does is, it adds the AllowAnyOtherHost flag to the private field m_Flag on the UriParser for the http scheme.
    /// Replacing /// with /%2f/ in the request.Headers.To uri BEFORE calling this method will make sure %2f remains unescaped in your Uri
    /// Why does this work, I don't know!
    /// </summary>
    private void AddAllowAnyOtherHostFlagToHttpUriParser()
    {
        var getSyntaxMethod =
            typeof(UriParser).GetMethod("GetSyntax", BindingFlags.Static | BindingFlags.NonPublic);
        if (getSyntaxMethod == null)
        {
            throw new MissingMethodException("UriParser", "GetSyntax");
        }
        var uriParser = getSyntaxMethod.Invoke(null, new object[] { "http" });

        var flagsField =
            uriParser.GetType().BaseType.GetField("m_Flags", BindingFlags.Instance|BindingFlags.NonPublic);
        if (flagsField == null)
        {
            throw new MissingFieldException("UriParser", "m_Flags");
        }
        int oldValue = (int)flagsField.GetValue(uriParser);
        oldValue += 4096;
        flagsField.SetValue(uriParser, oldValue);
    }


    public void AfterReceiveReply(ref Message reply, object correlationState)
    {

    }
}

因此，基本上，我正在创建一个自定义EndpointBehavior，它使用反射向UriParser中的私有变量添加枚举标志。这显然防止了我的request.Headers.To uri中的转义正斜杠不被转义。