如何在 HttpClient 中向 Google Oauth2 SSO 发送 Rest 请求时修复“错误请求”错误

Question

我正在尝试学习如何实现 Google 的 Oauth2 SSO 登录功能。到目前为止，我已经到了一切正常的地步，除非我尝试使用 C# 中的 REST 向“https://accounts.google.com/o/oauth2/token”发送请求以获取 Access_code/Token。我已经在 google 上注册了我的本地主机和相应的端口，并且我设法让我的 POST 请求在 POSTMAN 中工作，但是当我尝试在 C# 中发送请求时，我的 HttpRequestMessage 返回 400 错误请求。

首先，我有一个 Authorization.aspx 页面，该页面运行一个命令，该命令将用户重定向到用户登录的 google 授权页面，然后重定向到我的页面 http://localhost:64716/GoogleCallBack.aspx 获取响应。在页面中，它获取授权码并尝试向基本 URL 发送 POST 请求。我试过在它工作的 POSTMAN 中运行它（尽管只有一个新的授权码）。所以我知道问题出在我的 C# 代码上。我尝试过使用 webrequest，也尝试过将媒体类型更改为 application/Json 和 application/x-www-form-urlencoded

    protected void Page_Load(object sender, EventArgs e)
    {

        string Error = Request.QueryString["error"];

        string Code = Request.QueryString["code"];
        if (Error != null) { }
        else if (Code != null)
        {

            string UserId = Request.QueryString["state"];
            int Id = Convert.ToInt32(UserId);
            string AccessToken = string.Empty;
            string RefreshToken = ExchangeAuthorizationCode(Id, Code, out AccessToken);
            string Url = "Authorize.aspx?UserId=" + UserId;
            Response.Redirect(Url, true);
        }
    }
    private string ExchangeAuthorizationCode(int userId, string code, out string accessToken)
    {
        string baseurl = "https://accounts.google.com/o/oauth2/token";
        accessToken = string.Empty;
        string ClientSecret = ConfigurationManager.AppSettings["ClientSecrete"];
        string ClientId = ConfigurationManager.AppSettings["ClientId"];

        string RedirectUrl = "http://localhost:64716/GoogleCallBack.aspx";

        using (var client = new HttpClient())
        {
            client.BaseAddress = new Uri(baseurl);
            client.DefaultRequestHeaders.Clear();
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/Json"));

            var nvc = new List<KeyValuePair<string, string>>();
            nvc.Add(new KeyValuePair<string, string>("Code", code));
            nvc.Add(new KeyValuePair<string, string>("Client_id", ClientId));
            nvc.Add(new KeyValuePair<string, string>("Client_secret", ClientSecret));
            nvc.Add(new KeyValuePair<string, string>("Redirect_uri", RedirectUrl));
            nvc.Add(new KeyValuePair<string, string>("Grant_type", "authorization_code"));
            nvc.Add(new KeyValuePair<string, string>("access_type", "offline"));

            var req = new HttpRequestMessage(HttpMethod.Post, client.BaseAddress) { Content = new FormUrlEncodedContent(nvc) };
            var resres = client.SendAsync(req).Result;

            return "temp";

        }

    }

我希望我的响应是状态码 200，带有来自 google 的 access_token（就像在 Postman 中一样）

Answer 1

[已解决]这就是我所做的（在几个朋友的帮助下）

1. 将标头更改为 JSON

2. 将基本 URI 移至 PostAsync()

3. 一旦我更改了所有内容，我可以看到错误出现在 redirect_Uri 中，然后我将其更改为与邮递员中的匹配。现在它可以工作了

   protected void Page_Load(object sender, EventArgs e)
       {
           //you will get this, when any error will occur while authorization otherwise null    
           string Error = Request.QueryString["error"];
           //authorization code after successful authorization    
           string Code = Request.QueryString["code"];
           if (Error != null) { }
           else if (Code != null)
           {
               //Remember, we have set userid in State    
               string UserId = Request.QueryString["state"];
               //Get AccessToken    
               int Id = Convert.ToInt32(UserId);
               string AccessToken = string.Empty;
               string RefreshToken = ExchangeAuthorizationCode(Id, Code, out AccessToken);
               //saving refresh token in database    
               SaveRefreshToken(Id, RefreshToken);
               //Get Email Id of the authorized user    
               string EmailId = FetchEmailId(AccessToken);
               //Saving Email Id    
               SaveEmailId(UserId, EmailId);
               //Redirect the user to Authorize.aspx with user id    
               string Url = "Authorize.aspx?UserId=" + UserId;
               Response.Redirect(Url, true);
           }
       }
   
       private string ExchangeAuthorizationCode(int userId, string code, out string accessToken)
       {
           string baseurl = "https://accounts.google.com/o/oauth2/token";
           accessToken = string.Empty;
           string ClientSecret = ConfigurationManager.AppSettings["ClientSecrete"];
           string ClientId = ConfigurationManager.AppSettings["ClientId"];
           // //get this value by opening your web app in browser.    
           string RedirectUrl = "http://localhost:64716/GoogleCallback.aspx"; //I changed this to match the one in Postman
   
           using (var client = new HttpClient())
           {
               //client.BaseAddress = new Uri("https://accounts.google.com/o/oauth2"); //I replaced the Uri to "var result = client.PostAsync("https://accounts.google.com/o/oauth2/token", nvc).Result;"
               client.DefaultRequestHeaders.Clear();
               client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json")); // I made this JSON
               // I removed this "client.DefaultRequestHeaders.Add("Content-Type", "application/x-www-form-urlencoded");"
   
               var nvc = new FormUrlEncodedContent(new[] {
               new KeyValuePair<string, string>("grant_type", "authorization_code"),
               new KeyValuePair<string, string>("code", code),
               new KeyValuePair<string, string>("client_id", ClientId),
               new KeyValuePair<string, string>("client_secret", ClientSecret),
               new KeyValuePair<string, string>("redirect_uri", RedirectUrl),
               new KeyValuePair<string, string>("access_type", "offline")
               });
   
               var result = client.PostAsync("https://accounts.google.com/o/oauth2/token", nvc).Result;
   
               var resultContent = result.Content.ReadAsStringAsync();
   
               var tokenResponse = JsonConvert.DeserializeObject<Authorization_request_body>(resultContent.ToString());
   
               return "temp";
   
               }
   
           }