Web 请求 - 基础连接已关闭：连接意外关闭

Question

当我运行在 Curl 中执行以下命令时，我得到了正确的预期结果：

curl -d "client_secret=VALUE" -d "client_id=VALUE" -d "username=VALUE" -d "password=VALUE" -d "grant_type=VALUE" "https://<host>/auth/realms/test-rai/protocol/openid-connect/token"

（同样的请求用Postman触发时，结果也是正确的。）

但是，当我从 C# 发出（相同的）请求时，我运行进入异常：

using System.Collections.Generic;
using System.Net;
using System.Net.Http;
using System.Threading.Tasks;

namespace HttpClientPost
{
    class Program
    {
        static async Task Main(string[] args)
        {
            var url = "https://<host>/auth/realms/test-rai/protocol/openid-connect/token";

            var values = new List<KeyValuePair<string, string>>()
            {
                new KeyValuePair<string, string>("client_secret", "VALUE"),
                new KeyValuePair<string, string>("client_id", "VALUE"),
                new KeyValuePair<string, string>("username", "VALUE"),
                new KeyValuePair<string, string>("password", "VALUE"),
                new KeyValuePair<string, string>("grant_type", "VALUE")
            };

            ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls |
                                                   SecurityProtocolType.Tls11 |
                                                   SecurityProtocolType.Tls12 |
                                                   SecurityProtocolType.Ssl3;

            using (var httpClient = new HttpClient())
            {
                using (var content = new FormUrlEncodedContent(values))
                {
                    content.Headers.Clear();
                    content.Headers.Add("Content-Type", "application/x-www-form-urlencoded");

                    // Throws exception: An error occurred while sending the request. The underlying connection was closed: The connection was closed unexpectedly.
                    HttpResponseMessage response = await httpClient.PostAsync(url, content);

                    var result = await response.Content.ReadAsStringAsync();
                }
            }
        }
    }
}

抛出的异常是：

An error occurred while sending the request. The underlying connection was closed: The connection was closed unexpectedly.

在网上搜索时，我发现了很多关于设置 'ServicePointManager.SecurityProtocol' 的参考资料，我也这样做了。（测试了所有选项。）

由于 Curl 和 Postman 都给出了 correct/expected 结果：我在这里缺少什么？

Answer 1

我自己找到了答案：

由于我的请求在 Postman 和 Curl 中按预期工作，我注意到 Postman 中有一个选项可以转换 Postman 请求转换成特定语言：在 'Save' 按钮下方，您会找到一个 'Code' 按钮来实现此目的。

我生成的 - 运行良好 - C# 代码是：

static void Main(string[] args)
{
    var client = new RestClient("https://<host>/auth/realms/test-rai/protocol/openid-connect/token");
    client.Timeout = -1;
    var request = new RestRequest(Method.POST);
    request.AddHeader("Content-Type", "application/x-www-form-urlencoded");
    request.AddParameter("grant_type", "password");
    request.AddParameter("client_id", "VALUE");
    request.AddParameter("username", "VALUE");
    request.AddParameter("password", "VALUE");
    request.AddParameter("client_secret", "VALUE");
    IRestResponse response = client.Execute(request);
    Console.WriteLine(response.Content);
}

Web 请求 - 基础连接已关闭：连接意外关闭

Web Request - The underlying connection was closed: The connection was closed unexpectedly

c#

curl

httpclient

postman

keycloak