如何使用 System.Net.Http 从 OAuth 请求访问令牌？ 401 错误

Question

Context

I am developing a simple application that requires to receive List Data from a company Online SharePoint site. In order to make REST requests, I must first retrieve an access token from Microsoft's access control service. Despite attempting some tutorials and reading documentation, I am new to REST/HTTP am am failing to do so.

What have I tried?

• Used SharePoint appregnew.aspx to register my app, and generate "Client ID" and "Client Secret" values. https://[sitename].sharepoint.com/_layouts/15/appregnew.aspx
• Used Sharepoint appinv.aspx to authorize my app with read control and generate a "Tenant ID". https://[sitename].sharepoint.com/_layouts/15/appinv.aspx

<AppPermissionRequests AllowAppOnlyPolicy="true">
    <AppPermissionRequest Scope="http://sharepoint/content/sitecollection/web" Right="Read"/>
</AppPermissionRequests>

• Used SharePoint AppPrincipals.aspx to verify Tenant ID. https://[sitename].sharepoint.com/_layouts/15/AppPrincipals.aspx
• Attempted several methods of formatting the request with the following being the latest:

Updated

// Variables removed for security
class Program
{
    static void Main(string[] args)
    {               
        WebRequest myWebRequest;
        string stGetAccessTokenUrl = "https://accounts.accesscontrol.windows.net/{0}/tokens/OAuth/2";

        string tenantID         = "myTenantID";
        string resourceID       = "00000003-0000-0ff1-ce00-000000000000";
        string stClientID       = "myClientID";
        string stClientSecret   = "myClientSecret";
        string stSiteDomain     = "[myCompany].sharepoint.com";

        // URL Format
        stGetAccessTokenUrl = string.Format(stGetAccessTokenUrl, tenantID);
        myWebRequest = WebRequest.Create(stGetAccessTokenUrl);
        myWebRequest.ContentType = "application/x-www-form-urlencoded";
        myWebRequest.Method = "POST";

        // Add the below body attributes to the request
        var postData = "grant_type=client_credentials";
        postData += "&client_id=" + stClientID + "@" + tenantID;
        postData += "&client_secret=" + stClientSecret;
        postData += "&resource=" + resourceID + "/" + stSiteDomain + "@" + tenantID;
        var data = Encoding.ASCII.GetBytes(postData);

        using (var stream = myWebRequest.GetRequestStream())
        {
            stream.Write(data, 0, data.Length);
        }
            
        var response = (HttpWebResponse)myWebRequest.GetResponse();
    }
}

What doesn't work?

I receive a 401 Unauthorized error despite the app having been assigned permissions.

Any help would be greatly appreciated!

Answer 1

You could refer to this article to get the access token: https://social.technet.microsoft.com/wiki/contents/articles/51982.sharepoint-read-online-list-data-from-c-console-application-using-access-token.aspx

 #region Get Access Token using TenantID and App secret ID & Password
 // URL Format
 //https://accounts.accesscontrol.windows.net/tenant_ID/tokens/OAuth/2 Jump
 
 stGetAccessTokenUrl = string.Format(stGetAccessTokenUrl, tenantID);
 myWebRequest = WebRequest.Create(stGetAccessTokenUrl);
 myWebRequest.ContentType = "application/x-www-form-urlencoded";
 myWebRequest.Method = "POST";
  
   
 // Add the below body attributes to the request
 /*
  *  grant_type  client_credentials  client_credentials
  client_id  ClientID@TenantID 
  client_secret  ClientSecret 
  resource  resource/SiteDomain@TenantID  resourceid/abc.sharepoint.com@tenantID
  */
  
 
 var postData = "grant_type=client_credentials";
 postData += "&client_id=" + stClientID +"@" +tenantID;
 postData += "&client_secret=" + stClientSecret;
 postData += "&resource=" + resourceID + "/" + stSiteDomain + "@" + tenantID;
 var data = Encoding.ASCII.GetBytes(postData);
 
 using (var stream = myWebRequest.GetRequestStream())
 {
  stream.Write(data, 0, data.Length);
 }
 var response = (HttpWebResponse)myWebRequest.GetResponse();
 
 var responseString = new StreamReader(response.GetResponseStream()).ReadToEnd();
 
 string[] stArrResponse = responseString.Split(',');
  
 //get the access token and expiry time ,etc
  
 foreach(var stValues in stArrResponse)
 {
   
  if(stValues.StartsWith("\"access_token\":"))
  {
  //Console.WriteLine(" Result => " + stValues);
  accessToken = stValues.Substring(16);
  //Console.WriteLine(" Result => " + accessToken);
  accessToken = accessToken.Substring(0,accessToken.Length-2);
  // Console.WriteLine(" Result => " + accessToken);
  }
 }