ServiceStack Proxy 特性代码优化

Question

我的任务是为内部系统创建代理。代理需要为每个请求添加基本身份验证 header 并记录它和响应。

我正在使用 ServiceStack 的代理功能插件，但感觉代码重复，因为我对每个操作执行以下操作：

Plugins.Add(new ProxyFeature(matchingRequests: req => req.PathInfo.ToLower().StartsWith("/opretaftale"), resolveUrl: req => gensamOpretaftaleUrl)
{
    ProxyRequestFilter = (req, httpWebRequest) =>
    {
        try
        {
            httpWebRequest.AddBasicAuth(clientId, clientPassword);
        }
        catch (System.Exception ex)
        {
            Log.Error(ex, "...");
        }
    },

    TransformRequest = async (res, requestStream) =>
    {
        using (var reader = new StreamReader(requestStream, Encoding.UTF8))
        {
            var requestBody = await reader.ReadToEndAsync();
            Log.Information("request: " + requestBody);
            return MemoryStreamFactory.GetStream(requestBody.ToUtf8Bytes());
        }
    },

    TransformResponse = async (res, responseStream) =>
    {
        using (var reader = new StreamReader(responseStream, Encoding.UTF8))
        {
            var responseBody = await reader.ReadToEndAsync();
            Log.Information("response: " + responseBody);
            return MemoryStreamFactory.GetStream(responseBody.ToUtf8Bytes());
        }
    }
});

是否可以对多个请求执行相同的操作？我真的需要 TransformRequest/TransformResponse 来记录 request/response 吗？我很难从 ProxyRequestFilter/ProxyResponseFilter 操作中获取流内容...

谢谢！

Answer 1

您可以使用普通的 C# 进行重构，例如通过将内联 lambda 提取到通用方法中并改为引用它们：

private Func<IHttpRequest, Stream, Task<Stream>> TransformRequest =>
    async (res, requestStream) => {
        using var reader = new StreamReader(requestStream, Encoding.UTF8);
        var requestBody = await reader.ReadToEndAsync();
        Log.Information("request: " + requestBody);
        return MemoryStreamFactory.GetStream(requestBody.ToUtf8Bytes());
    };

你可以在哪里：

Plugins.Add(new ProxyFeature(...) {
    TransformRequest = TransformRequest,
});

尽管在这种情况下您可能希望创建一个构造 PluginFeature 的工厂方法，例如：

ProxyFeature CreateProxyRule(Func<IHttpRequest, bool> matchingRequests,
    Func<IHttpRequest, string> resolveUrl)
{
    return new ProxyFeature(matchingRequests, resolveUrl)
    {
        ProxyRequestFilter = (req, httpWebRequest) => {
            httpWebRequest.AddBasicAuth(clientId, clientPassword);
        },
        TransformRequest = async (res, requestStream) => {
            using var reader = new StreamReader(requestStream, Encoding.UTF8);
            var requestBody = await reader.ReadToEndAsync();
            Log.Information("request: " + requestBody);
            return MemoryStreamFactory.GetStream(requestBody.ToUtf8Bytes());
        },
        TransformResponse = async (res, responseStream) => {
            using var reader = new StreamReader(responseStream, Encoding.UTF8);
            var responseBody = await reader.ReadToEndAsync();
            Log.Information("response: " + responseBody);
            return MemoryStreamFactory.GetStream(responseBody.ToUtf8Bytes());
        }
    };
}

然后只需传入所有可在不同代理之间配置的部分，例如：

Plugins.Add(CreateProxyRule(
    matchingRequests: req => req.PathInfo.ToLower().StartsWith("/opretaftale"), 
    resolveUrl: req => gensamOpretaftaleUrl));

由于 HTTP 请求通常是仅转发流，如果您想记录正文，则需要缓冲 Request/Response，因此对于代理请求，您需要在 TransformRequest/TransformResponse 中执行此操作。

如果您只是想记录 ServiceStack 请求，您可以注册一个启用了 EnableRequestBodyTracking 的 Request Logger，例如：

Plugins.Add(new RequestLogsFeature { EnableRequestBodyTracking = true });

这将 enable Request Buffering 以便能够缓冲请求主体以进行日志记录和反序列化。

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