将 POST 请求从 asp.net core 控制器转发到不同的 URL

Question

我想将传入的 POST 请求“按原样”（包括标头、正文、来自数据）转发到我的 asp.net core 控制器到不同的 URL，而不使用中间件。

我找到了一个为 asp.net 执行此操作的示例：https://philsversion.com/2012/09/06/creating-a-proxy-with-apicontroller/

但这不适用于 ASP.NET Core，因为调用 return wait http.SendAsync(this.Request); 在asp.net core中接受一个HttpRequestMessage，Request对象的类型是HttpRequest。

我还找到了一些代码，它从 HttpRequest 创建 HttpRequestMessage，请参阅：Convert Microsoft.AspNetCore.Http.HttpRequest to HttpRequestMessage

使用此代码，接收端点（我转发到的）将获取正文，但不会获取表单字段。

检查 HttpRequestMessage 类，我发现它不包含 FormFields 的属性。

[Microsoft.AspNetCore.Mvc.HttpPost]
[NrgsRoute("api/redirect-v1/{key}")]
public async Task<HttpResponseMessage> Forward(
   [FromUri] string key,
   CancellationToken cancellationToken)
{
   // the URL was shortened, we need to get the original URL to which we want to forward the POST request
   var url = await _shortenUrlService.GetUrlFromToken(key, cancellationToken).ConfigureAwait(false);

     using (var httpClient = new HttpClient())
     {
         var forwardUrl = new Uri(url);
         Request.Path = new PathString(forwardUrl.PathAndQuery);

         // see: /sf/ask/3203159221/
         var requestMessage = Request.ToHttpRequestMessage();
         return await httpClient.SendAsync(requestMessage, cancellationToken);

         // Problem: Forwards header and body but NOT form fields
     }
 }

预期的结果是，在我的接收端点，我具有与原始 POST 请求中相同的 - headers - body - form 字段。

Answer 1

我最终做了以下事情：

[HttpPost]
[NrgsRoute("api/redirect-v1/{key}")]
public async Task<RedirectResult> Forward(string key, CancellationToken cancellationToken)
{
    var url = await _shortenUrlService.GetUrlFromToken(key, cancellationToken).ConfigureAwait(false);
    if (string.IsNullOrEmpty(url))
        throw new BadRequestException($"Could not create forward URL from parameter {key}", "redirect-error");

    using (var httpClient = new HttpClient())
    {
        var forwardUrl = new Uri(url);
        Request.Path = new PathString(forwardUrl.PathAndQuery);

        HttpResponseMessage responseMessage;
        if (Request.HasFormContentType)
            responseMessage = await ForwardFormData(key, httpClient, forwardUrl, cancellationToken);
        else
            responseMessage = await ForwardBody(key, httpClient, cancellationToken);

        var queryParams = forwardUrl.GetQueryStringParams();
        var lUlr = queryParams["lurl"];
        return new RedirectResult(lUlr);
    }
}

private async Task<HttpResponseMessage> ForwardFormData(string key, HttpClient httpClient, Uri forwardUrl, CancellationToken cancellationToken)
{
    var formContent = new List<KeyValuePair<string, string>>();
    HttpResponseMessage result;

    if (Request.ContentType == "application/x-www-form-urlencoded")
    {
        foreach (var formKey in Request.Form.Keys)
        {
            var content = Request.Form[formKey].FirstOrDefault();
            if (content != null)
                formContent.Add(new KeyValuePair<string, string>(formKey, content));
        }
        var formUrlEncodedContent = new FormUrlEncodedContent(formContent);
        result = await httpClient.PostAsync(forwardUrl, formUrlEncodedContent, cancellationToken);
    }
    else
    {
        var multipartFormDataContent = new MultipartFormDataContent();
        foreach (var formKey in Request.Form.Keys)
        {
            var content = Request.Form[formKey].FirstOrDefault();
            if (content != null)
                multipartFormDataContent.Add(new StringContent(content), formKey);
        }

        result = await httpClient.PostAsync(forwardUrl, multipartFormDataContent, cancellationToken);
    }

    return result;
}

private async Task<HttpResponseMessage> ForwardBody(string key, HttpClient httpClient, CancellationToken cancellationToken)
{
    // we do not have direct access to Content, see: https://stackoverflow.com/questions/41508664/net-core-forward-a-local-api-form-data-post-request-to-remote-api

    var requestMessage = Request.ToHttpRequestMessage();
    return await httpClient.SendAsync(requestMessage, cancellationToken);
}