Styjun

I´m trying to learn how to implement Googles Oauth2 SSO login function. So far I´ve gotten to the point where everything works except when I try to send a request to "https://accounts.google.com/o/oauth2/token" using REST in C# to get the Access_code/Token. I´ve registered my localhost and the corresponding port on google and I´ve managed to get my POST request to work in POSTMAN however when i try sending a request in C# my HttpRequestMessage returns 400 bad request.

First I have an Authorization.aspx page that runs a command that redirects the users to googles authorization page where the user login and then gets redirected to my page http://localhost:64716/GoogleCallBack.aspx which picks up the response. In the page it picks up the authorization code and tries to send a POST request to the base URL. I´ve tried running it in POSTMAN where it works (although only with a new authorization code). So I know it is my C# code that is the problem. I´ve tried using webrequest and I´ve also tried changing the Media type to application/Json and 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";

 

 

I want my response to be statuscode 200 with an access_token from google (Like it does in Postman)

[resolved] This is what I did (With the help from a few friends)

1. Changed Headers to JSON




2. Moved the Base URI to PostAsync()



3. 
   

   Once I had change all that I could see that the error was in the redirect_Uri and I then changed it to match the one in postman. And now it works

   
   
   

   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";