C#实现登录某web进而获取其token数据

实习在学C#,记录一下学习过程！

首先是需求描述（基于C#的.net core MVC实现）：

User:
Resource Owner

Agent:
Brower

auth.brightspace.com:
Authorization Server

politemalltest.brightspace.com:
Resource Server

1. Web Page:
　　1.1 host must be https://localhost:3434
2. Button:
　　2.1 onclick <a href="/d2lauth">
　　2.2 get https://localhost:3434/d2lauth
　　2.3 response 302 https://auth.brightspace.com/oauth2/auth?response_type=code&client_id=*******&state=ssss&scope=core%3A*%3A*&redirect_uri=https%3A%2F%2Flocalhost%3A3434%2Fredirecturi

3. Api:
　　3.1 build api for POST https://localhost:3434/redirecturi to received Auth Code
　　3.2 Use Auth code to get Token from [POST https://auth.brightspace.com/core/connect/token] (use HttpClient)
　　3.3 Save Token to database

URL:
https://politemalltest.brightspace.com/d2l/login?noredirect=1
Username:***********
Password: ************

首先将本地服务器端口号设置为3434，具体操作为，找到lunchsettings文件，修改url

然后我们要向https://localhost:3434/d2lauth发送get请求，然后跳转到 https://auth.brightspace.com/oauth2/auth?response_type=code&client_id=0055e1d6-0d67-47b3-9169-　　　　　　               　　　　　　                       b329a4af7eae&state=ssss&scope=core%3A*%3A*&redirect_uri=https%3A%2F%2Flocalhost%3A3434%2Fredirecturi

然后我们要向 https://localhost:3434/redirecturi发送post请求，来获取鉴权码，也就是authcode，因为我们是基于Oauth2.0协议的。要获取token，首先服务端会验证客户端身份，验证成功后，会返给一个authcode，然后客户端拿着authcode，去换取token，进而在服务端获取相关资源！

接下来就是主要获取token的操作，我们在controller下的文件，编写一个控制器，发送请求，代码如下：

             string authcode = this.HttpContext.Request.Query["code"];

            HttpClient client = new HttpClient();

            Dictionary<string, string> headers = new Dictionary<string, string>();

            headers["grant_type"] = "authorization_code";
            //headers["grant_type"] = "refresh_token";
            headers["client_id"] = "*************";
            headers["client_secret"] = "********************888";
            headers["code"] = authcode;
            //headers["refresh_token"] = "rt.ap-southeast-1.z9I0S2XTQ9EMCRUVaAil8_4C83X7X8yt_6ExSF6VRyk";
            headers["redirect_uri"] = "https://localhost:3434/redirecturi";

            FormUrlEncodedContent content = new FormUrlEncodedContent(headers);

            var url = "https:****************/connect/token";

            var response = await client.PostAsync(url, content);

            string result = response.Content.ReadAsStringAsync().Result;
            Dictionary<string, string> values = JsonConvert.DeserializeObject<Dictionary<string, string>>(result);

            string access_token = values["access_token"];        

代码结构很清晰，逻辑就是获取重定向后的authcode，然后我们使用httpclient实例话一个对象，用来发送请求，然后创建一个字典结构，用来存放请求头信息，获取token的必要参数如代码所示，client_id,client_sercet,grant_type,redirect_uri,code,然后我们对这些内容进行编码。之后的操作也很容易理解，response表示发送请求之后的回应，result表示获取到的结果，然后反序列化内容，进而等到token数据中的access_token.

如图，我们就获取了token中的access_token数据了！

上述代码表达了获取token的大致思路，下面看一下结构化代码：

using Microsoft.AspNetCore.Mvc;
using System.Net.Http.Headers;
using System.Text;

namespace TokenRequester.Controllers
{
    public class Token_Get : Controller

    {
        public class AccessTokenSend
        {
            public string client_id { get; set; }
            public string client_secret { get; set; }
            public string code { get; set; }
            public string grant_type { get; set; }
            public string redirect_url { get; set; }
        }
        public IActionResult Index()
        {
            return Redirect("https://auth.brightspace.com/oauth2/auth?response_type=code&client_id=0055e1d6-0d67-47b3-9169-b329a4af7eae&state=ssss&scope=core%3A*%3A*&redirect_uri=https%3A%2F%2Flocalhost%3A3434%2Fredirecturi");
        }
        public async Task<string> GetAccess()
        {
            using (var client = new HttpClient())
            {
                client.BaseAddress = new Uri("https://auth.brightspace.com/core/connect/token");
                var contentType = new MediaTypeWithQualityHeaderValue("application/json");
                client.DefaultRequestHeaders.Accept.Add(contentType);

                AccessTokenSend accessTokenSend = new AccessTokenSend()
                {
                    client_id = "_client_id_",
                    client_secret = "_client_secret",
                    code = "_authorisation_code_from_url",
                    grant_type = "authorization_code",
                    redirect_url = "_redirect_url"
                };
                var json = Newtonsoft.Json.JsonConvert.SerializeObject(accessTokenSend);
                var data = new System.Net.Http.StringContent(json, Encoding.UTF8, "application/x-www-from-urlencoded");

                var result = await client.PostAsync("https://auth.brightspace.com/core/connect/token", data);
                string resultContent = await result.Content.ReadAsStringAsync();

                return resultContent;
            }
        }
    }
}