Connecting to SharePoint subscription edition on-premise using CSOM in net6

Question

I have SharePoint subscription on-premise edition. Is there a way to connect to this instance using net6, csom and windows authentication?

I created console app and 'nuget' installed

<PackageReference Include="Microsoft.SharePointOnline.CSOM" Version="16.1.24009.12000" />

Then I tried following code

            using (var clientContext = new ClientContext("url"))
            {
                Web web = clientContext.Web;
                clientContext.Credentials = new NetworkCredential(@"userName", "Password");
                //clientContext.Credentials = System.Net.CredentialCache.DefaultNetworkCredentials;
                //clientContext.Credentials = System.Net.CredentialCache.DefaultCredentials;

                clientContext.Load(web);
                clientContext.ExecuteQuery();
            }

I tried using commented lines as well. Each time I get 401: Unauthorised.

1. Is it possible to use CSOM with net6 at all?
2. I referred to MS Article. However it is referring to Online edition of SharePoint with Azure Ad.

Thank you

Answer 1

I got it working as below -

using Microsoft.SharePoint.Client;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http.Headers;
using System.Net.Http;
using System.Security;
using System.Security.Policy;
using System.Security.Principal;
using System.Text;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using static System.Net.WebRequestMethods;


namespace TestCoreConsoleApp
{
    static class ProgramSP
    {
        private static string _siteUrl = "url of sp site";
        private static HttpWebRequest _webReq = null;
        private static Task<string> tokenTask = null;
        static void Main(string[] args)
        {
            tokenTask = GetDigestValueAsync(new CancellationToken());
            using (var clientContext = new ClientContext(_siteUrl))
            {
                clientContext.ExecutingWebRequest += new EventHandler<WebRequestEventArgs>(AddWindowsAuthRequestHeader);
                Web web = clientContext.Web;

                clientContext.Load(web);

                clientContext.ExecuteQuery();
                Console.WriteLine(web.Title);
                Console.ReadLine();
            }
        }
        private static void AddWindowsAuthRequestHeader(object sender, WebRequestEventArgs e)
        {
            try
            {
                e.WebRequestExecutor.WebRequest.UseDefaultCredentials = true;
                e.WebRequestExecutor.RequestHeaders["X-RequestDigest"] = tokenTask.Result;

            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.Message);
                Console.WriteLine(ex.StackTrace);
            }
        }

        private static SecureString ConvertToSecureString(string password)
        {
            SecureString securePassword = new SecureString();
            foreach (char c in password)
            {
                securePassword.AppendChar(c);
            }
            return securePassword;
        }

        private static async Task<string> GetDigestValueAsync(CancellationToken cancellationToken)
        {

            var endpointUrl = $"{_siteUrl}/_api/contextinfo";


            var handler = new HttpClientHandler
            {
                UseDefaultCredentials = true,
                PreAuthenticate = true
            };
            var client = new HttpClient(handler);

            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            var response = await client.PostAsync(endpointUrl, null, cancellationToken);

            if (!response.IsSuccessStatusCode)
                throw new Exception($"Error fetching digest value: {response.ReasonPhrase}");

            var responseContent = await response.Content.ReadAsStreamAsync(cancellationToken);
            var sharePointResp = await JsonSerializer.DeserializeAsync<DigestRoot>(responseContent,
                new JsonSerializerOptions { PropertyNameCaseInsensitive = true }, cancellationToken);

            return sharePointResp?.FormDigestValue ?? throw new Exception("Failed to extract FormDigestValue");
        }
        public class DigestRoot
        {
            public string odatametadata { get; set; }
            public int FormDigestTimeoutSeconds { get; set; }
            public string FormDigestValue { get; set; }
            public string LibraryVersion { get; set; }
            public string SiteFullUrl { get; set; }
            public List<string> SupportedSchemaVersions { get; set; }
            public string WebFullUrl { get; set; }
        }
    }

}

With nuget package -

    <PackageReference Include="Microsoft.SharePointOnline.CSOM" Version="16.1.24009.12000" />