Microsoft Modern Authentication - SSO

 In some company, getting application level permissions might be hard to do due to security reason.  Within those environment, setting up a job that runs periodically could be difficult.  One of the way to do it is to make sure your job running account has enough permissions and you have a SPN with enough delegated permissions.

The below code show how to use the logged in account to get access token for SharePoint scope.

public async Task<string> GetSSOUserAccessToken(Uri spSiteUrl) {

var _clientId = "";

var _tenantId = "";

var _scheme = siteUrl.Scheme;

var _hostUrl = siteUrl.host;

var _scope = "AllSites.FullControl";

string[] _scopes = new string[] {string.Format("{0}://{1}/{2}", _schem, _hostUrl, _scope);

var authority = string.Format(CultureInfo.InvariantCulture, "{0}/{1}/", "https://login.microsoftonline.com", _tenantId);

try {

    IPublicClientApplication app = PublicClientApplicationBuilder.Create(_clientId).WithAurhority(new     Uri(authority)).Build();

    var accounts = await app.GetAccountsAsync();

    if (accounts.Any()){

        AuthResult = await app.AcquireTokenSilent(_scopes, accounts.FirstOrDefault()).ExecuteAsync();

    }

    else{

        AuthResult = await app.AcquireTokenByIntegratedWindowsAuth(_scope).ExecuteAsync(CancellationToken.None);

    }

    return AuthResult.AccessToken;

    }

    catch (Exception ex){

        Log.Log(ex.ToString());

    }

}

And then below code would be how to create SharePoint ClientContext from the access token

public async Task<ClientContext> GetSSOUserContext(string spUrl, string userAgent, string clientTag = ""){

    var context = new ClientContext(spUrl);

    string token = await GetSSOUserAccessToken(new Uri(spUrl));

    context.ExecutingWebRequest += (s, e) => {

        e.WebRequestExecutor.RequestHeaders["Authorization"] = "Bearer " + token;

        e.WebRequestExecutor.WebRequest.UserAgent = userAgent;

    };

    if (!String.InNullOrEmpty(clientTag)){

        context.CliengTag = clientTag;

    }

    return   context; 

}