Validate SharePoint credentials using Client Object Model

Recently I wrote a simple console application in C# to modify certain parts of SharePoint sites.

Its job was to simply do the following:

• Collect data from a spreadsheet
• Modify SharePoint list based on the data

The program was intended to be used both as a standalone exe as well as from a web application. Another requirement was that the user of the program might not have SharePoint server installed.

This means that CSOM or Client-side Object Model needs to be used. Since the application was also supposed to be used as a standalone exe, I felt it would require validation of the user.

If the Sharepoint site is an intranet site or is on-premise, we can use the following piece of code.

private bool ValidateCredentials(string siteUrl, string username, string password)
{
    ClientContext context = new ClientContext(siteUrl);
    Web web = context.Web;

    context.Credentials = new NetworkCredential(username, password, "domain");

    try
    {
        context.Load(web);
        context.ExecuteQuery();
        return true;
    }
    catch(Exception e)
    {
        logger.Error(e, e.Message);
        return false;
    }
}

If the SharePoint site is on the internet or a Sharepoint Online site, we would need to use SecureString for wrapping the password.

private bool ValidateCredentials(string siteUrl, string username, string password)
{
    ClientContext context = new ClientContext(siteUrl);
    Web web = context.Web;

    SecureString securePass = new SecureString();
    foreach(char c in password.ToCharArray())
    {
        securePass.Append(c);
    }

    context.Credentials = new SharePointOnlineCredentials(username, securePass);

    try
    {
        context.Load(web);
        context.ExecuteQuery();
        return true;
    }
    catch(Exception e)
    {
        logger.Error(e, e.Message);
        return false;
    }
}

Then we can use this method as follows:

if(!ValidateCredentials(spUrl, user, pass))
{
    Exit(message: "Invalid Credentials");
}

Exit method is a handy method I added to provide exit points from several parts of the program.

private void Exit(string message = null, bool error = true)
{
    if(message != null)
        logger.Info(message);

    if(error)
        Environment.Exit(exitCode: 1)
    else
        Environment.Exit(exitCode: 0)
}