(UWP)如何在GET请求中添加不带Content-Length的Content-Type标头 [英] (UWP) How to add Content-Type header without Content-Length in GET request

问题描述

我正在处理一个第三方API，该第三方API的调用要求GET方法请求上的Content-Type标头，但是当标头集合包含"Content-Length"时返回错误响应.添加Content-Type标头的唯一方法是添加一个继承/实现IHttpContent接口的类(我使用HttpStringContent并将string.empty作为字符串内容).问题在于，添加空白HttpStringContent会添加ContentLength.即使该标头的值为"0"，他们的服务器也会非常生气.在调试时，Content-Length不会显示在标头集合中，但是当我通过Postman或Burp Proxy运行应用程序时，Content-Length标头就在那里.我尝试盲目使用.Remove摆脱Content-Length标头，但这不起作用.

I'm dealing with a third-party API who's calls require the Content-Type header on GET method requests, but return an error response when the header collection includes "Content-Length". The only way to add the Content-Type header is to add a class that inherits/implements the IHttpContent interface (I was using HttpStringContent with string.empty as the string content). The problem, is that adding a blank HttpStringContent adds ContentLength. Even though the value of that header is '0', their server gets super angry. Content-Length doesn't show up in the header collection while i'm debugging, but when i run my application through Postman or Burp Proxy, the Content-Length header is there. I've tried blindly using .Remove to get rid of the Content-Length header but that doesn't work.

我已经看到StackOverflow有关添加Content-Length的问题，但这不是我需要/想要的.有什么方法可以使GET请求中的Content-Type标头，没有具有Content-Length标头?或者....有没有办法删除Content-Length标头?我曾尝试创建自己的实现IHttpContent的内容类，但是我对IAsyncOperationWithProgress的实现陷入了困境.

I've seen StackOverflow questions about adding Content-Length, but that's not what i need/want. Is there any way to have the Content-Type header in a GET request, without having the Content-Length header? Or.... is there a way to remove the Content-Length header? I've tried creating my own content class that implements IHttpContent, but i'm getting stuck with the implementation of IAsyncOperationWithProgress.

我知道这不是标准，这就是为什么我对此有很多困难的原因.我还尝试了Flurl，它也没有添加Content-Type标头.

I understand this isn't standard, which is why i'm having so much difficulty with this. I've also tried Flurl which also didn't add the Content-Type header.

TL; DR:Content-Type(应用程序/json)是必需的，Content-Length会导致API错误(即使它为0).如何在不具有Content-Length的情况下将Content-Type添加到Windows.Web.Http.HttpRequestMessage/HttpClient?

为澄清起见，这是一个UWP应用程序

for clarification this is a UWP application

推荐答案

您已经知道，您需要做一些非标准的事情，所以我提出了一个非标准的解决方案来完成这项工作.

As you're aware, you're needing to do something non-standard, so I present a non-standard solution to get this done.

您可能尝试了client.DefaultRequestHeaders.Add()和client.DefaultRequestHeaders.TryAddWithoutValidation()均未成功.您可以使用反射来破坏进入HttpRequestHeaders的方式来修改验证行为.

You've likely tried client.DefaultRequestHeaders.Add() and client.DefaultRequestHeaders.TryAddWithoutValidation() without success. You can use reflection to evil your way into HttpRequestHeaders to modify the validation behavior.

static void AllowInvalidRequestHeader(string header)
{
    var headerType = typeof(HttpRequestHeaders);

    var field = headerType
        .GetField("invalidHeaders", System.Reflection.BindingFlags.NonPublic | 
                                    System.Reflection.BindingFlags.Static) ?? 
                headerType
        .GetField("s_invalidHeaders", System.Reflection.BindingFlags.NonPublic | 
                                      System.Reflection.BindingFlags.Static);

    if (field == null) return;

    var invalidFields = (HashSet<string>)field.GetValue(null);

    invalidFields.Remove(header);
}

在应用程序初始化中，调用AllowInvalidRequestHeader("Content-Type")一次，并使用以下方法初始化HttpClient实例:

In application initialization, call AllowInvalidRequestHeader("Content-Type") once, and initialize HttpClient instances with this:

var client = new HttpClient();
client.DefaultRequestHeaders.Add("Content-Type", "application/json");

在一个简单的服务器端页面中，回显具有请求标头，我回来了:

In a simple server side page that echos have request headers, I get back:

<div class="row">
    <p>Connection: Keep-Alive</p>
    <p>Content-Type: application/json</p>
    <p>Host: localhost:52975</p>
    <p>MS-ASPNETCORE-TOKEN: de3a3a58-eccc-407b-b5f7-9a6663631587</p>
    <p>X-Original-Proto: http</p>
    <p>X-Original-For: 127.0.0.1:53362</p>
</div>

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