How to: Sample Role-Provider Implementation

using System.Web.Security;
using System.Configuration.Provider;
using System.Collections.Specialized;
using System;
using System.Data;
using System.Data.Odbc;
using System.Configuration;
using System.Diagnostics;
using System.Web;
using System.Globalization;

/*

This provider works with the following schema for the tables of role data.

CREATE TABLE Roles
(
  Rolename Text (255) NOT NULL,
  ApplicationName Text (255) NOT NULL,
    CONSTRAINT PKRoles PRIMARY KEY (Rolename, ApplicationName)
)

CREATE TABLE UsersInRoles
(
  Username Text (255) NOT NULL,
  Rolename Text (255) NOT NULL,
  ApplicationName Text (255) NOT NULL,
    CONSTRAINT PKUsersInRoles PRIMARY KEY (Username, Rolename, ApplicationName)
)

*/


namespace Samples.AspNet.Roles
{

  public sealed class OdbcRoleProvider: RoleProvider
  {

    //
    // Global connection string, generic exception message, event log info.
    //

    private string eventSource = "OdbcRoleProvider";
    private string eventLog = "Application";
    private string exceptionMessage = "An exception occurred. Please check the Event Log.";

    private ConnectionStringSettings pConnectionStringSettings;
    private string connectionString;


    //
    // If false, exceptions are thrown to the caller. If true,
    // exceptions are written to the event log.
    //

    private bool pWriteExceptionsToEventLog = false;

    public bool WriteExceptionsToEventLog
    {
      get { return pWriteExceptionsToEventLog; }
      set { pWriteExceptionsToEventLog = value; }
    }



    //
    // System.Configuration.Provider.ProviderBase.Initialize Method
    //

    public override void Initialize(string name, NameValueCollection config)
    {

      //
      // Initialize values from web.config.
      //

      if (config == null)
        throw new ArgumentNullException("config");

      if (name == null || name.Length == 0)
        name = "OdbcRoleProvider";

      if (String.IsNullOrEmpty(config["description"]))
      {
        config.Remove("description");
        config.Add("description", "Sample ODBC Role provider");
      }

      // Initialize the abstract base class.
      base.Initialize(name, config);


      if (config["applicationName"] == null || config["applicationName"].Trim() == "")
      {
        pApplicationName = System.Web.Hosting.HostingEnvironment.ApplicationVirtualPath;
      }
      else
      {
        pApplicationName = config["applicationName"];
      }


      if (config["writeExceptionsToEventLog"] != null)
      {
        if (config["writeExceptionsToEventLog"].ToUpper() == "TRUE")
        {
          pWriteExceptionsToEventLog = true;
        }
      }


      //
      // Initialize OdbcConnection.
      //

      pConnectionStringSettings = ConfigurationManager.
        ConnectionStrings[config["connectionStringName"]];

      if (pConnectionStringSettings == null || pConnectionStringSettings.ConnectionString.Trim() == "")
      {
        throw new ProviderException("Connection string cannot be blank.");
      }

      connectionString = pConnectionStringSettings.ConnectionString;
    }



    //
    // System.Web.Security.RoleProvider properties.
    //


    private string pApplicationName;


    public override string ApplicationName
    {
      get { return pApplicationName; }
      set { pApplicationName = value; }
    } 

    //
    // System.Web.Security.RoleProvider methods.
    //

    //
    // RoleProvider.AddUsersToRoles
    //

    public override void AddUsersToRoles(string[]  usernames, string[] rolenames)
    {
      foreach (string rolename in rolenames)
      {
        if (!RoleExists(rolename))
        {
          throw new ProviderException("Role name not found.");
        }
      }

      foreach (string username in usernames)
      {
        if (username.Contains(","))
        {
          throw new ArgumentException("User names cannot contain commas.");
        }

        foreach (string rolename in rolenames)
        {
          if (IsUserInRole(username, rolename))
          {
            throw new ProviderException("User is already in role.");
          }
        }
      }


      OdbcConnection conn = new OdbcConnection(connectionString);
      OdbcCommand cmd = new OdbcCommand("INSERT INTO UsersInRoles "  +
              " (Username, Rolename, ApplicationName) " +
              " Values(?, ?, ?)", conn);

      OdbcParameter userParm = cmd.Parameters.Add("@Username", OdbcType.VarChar, 255);
      OdbcParameter roleParm = cmd.Parameters.Add("@Rolename", OdbcType.VarChar, 255);
      cmd.Parameters.Add("@ApplicationName", OdbcType.VarChar, 255).Value = ApplicationName;

      OdbcTransaction tran = null;

      try
      {
        conn.Open();
        tran = conn.BeginTransaction();
        cmd.Transaction = tran;

        foreach (string username in usernames)
        {
          foreach (string rolename in rolenames)
          {
            userParm.Value = username;
            roleParm.Value = rolename;
            cmd.ExecuteNonQuery();
          }
        }

        tran.Commit();
      }
      catch (OdbcException e)
      {
        try
        {
          tran.Rollback();
        }
        catch { }


        if (WriteExceptionsToEventLog)
        {
          WriteToEventLog(e, "AddUsersToRoles");
        }
        else
        {
          throw e;
        }
      }
      finally
      {
        conn.Close();      
      }
    }


    //
    // RoleProvider.CreateRole
    //

    public override void CreateRole(string rolename)
    { 
      if (rolename.Contains(","))
      {
        throw new ArgumentException("Role names cannot contain commas.");
      }

      if (RoleExists(rolename))
      {
        throw new ProviderException("Role name already exists.");
      }

      OdbcConnection conn = new OdbcConnection(connectionString);
      OdbcCommand cmd = new OdbcCommand("INSERT INTO Roles "  +
              " (Rolename, ApplicationName) " +
              " Values(?, ?)", conn);

      cmd.Parameters.Add("@Rolename", OdbcType.VarChar, 255).Value = rolename;
      cmd.Parameters.Add("@ApplicationName", OdbcType.VarChar, 255).Value = ApplicationName;

      try
      {
        conn.Open();

        cmd.ExecuteNonQuery();
      }
      catch (OdbcException e)
      {
        if (WriteExceptionsToEventLog)
        {
          WriteToEventLog(e, "CreateRole");
        }
        else
        {
          throw e;
        }
      }
      finally
      {
        conn.Close();      
      }
    }


    //
    // RoleProvider.DeleteRole
    //

    public override bool DeleteRole(string rolename, bool throwOnPopulatedRole)
    {
      if (!RoleExists(rolename))
      {
        throw new ProviderException("Role does not exist.");
      }

      if (throwOnPopulatedRole && GetUsersInRole(rolename).Length > 0)
      {
        throw new ProviderException("Cannot delete a populated role.");
      }

      OdbcConnection conn = new OdbcConnection(connectionString);
      OdbcCommand cmd = new OdbcCommand("DELETE FROM Roles "  +
              " WHERE Rolename = ? AND ApplicationName = ?", conn);

      cmd.Parameters.Add("@Rolename", OdbcType.VarChar, 255).Value = rolename;
      cmd.Parameters.Add("@ApplicationName", OdbcType.VarChar, 255).Value = ApplicationName;


      OdbcCommand cmd2 = new OdbcCommand("DELETE FROM UsersInRoles "  +
              " WHERE Rolename = ? AND ApplicationName = ?", conn);

      cmd2.Parameters.Add("@Rolename", OdbcType.VarChar, 255).Value = rolename;
      cmd2.Parameters.Add("@ApplicationName", OdbcType.VarChar, 255).Value = ApplicationName;

      OdbcTransaction tran = null;

      try
      {
        conn.Open();
        tran = conn.BeginTransaction();
        cmd.Transaction = tran;
        cmd2.Transaction = tran;

        cmd2.ExecuteNonQuery();
        cmd.ExecuteNonQuery();

        tran.Commit();
      }
      catch (OdbcException e)
      {
        try
        {
          tran.Rollback();
        }
        catch { }


        if (WriteExceptionsToEventLog)
        {
          WriteToEventLog(e, "DeleteRole");

          return false;
        }
        else
        {
          throw e;
        }
      }
      finally
      {
        conn.Close();      
      }

      return true;
    }


    //
    // RoleProvider.GetAllRoles
    //

    public override string[] GetAllRoles()
    {
      string tmpRoleNames = "";

      OdbcConnection conn = new OdbcConnection(connectionString);
      OdbcCommand cmd = new OdbcCommand("SELECT Rolename FROM Roles "  +
                " WHERE ApplicationName = ?", conn);

      cmd.Parameters.Add("@ApplicationName", OdbcType.VarChar, 255).Value = ApplicationName;

      OdbcDataReader reader = null;

      try
      {
        conn.Open();

        reader = cmd.ExecuteReader();

        while (reader.Read())
        {
          tmpRoleNames += reader.GetString(0) + ",";
        }
      }
      catch (OdbcException e)
      {
        if (WriteExceptionsToEventLog)
        {
          WriteToEventLog(e, "GetAllRoles");
        }
        else
        {
          throw e;
        }
      }
      finally
      {
        if (reader != null) { reader.Close(); }
        conn.Close();      
      }

      if (tmpRoleNames.Length > 0)
      {
        // Remove trailing comma.
        tmpRoleNames = tmpRoleNames.Substring(0, tmpRoleNames.Length - 1);
        return tmpRoleNames.Split(',');
      }

      return new string[0];
    }


    //
    // RoleProvider.GetRolesForUser
    //

    public override string[] GetRolesForUser(string username)
    {
      string tmpRoleNames = "";

      OdbcConnection conn = new OdbcConnection(connectionString);
      OdbcCommand cmd = new OdbcCommand("SELECT Rolename FROM UsersInRoles "  +
              " WHERE Username = ? AND ApplicationName = ?", conn);

      cmd.Parameters.Add("@Username", OdbcType.VarChar, 255).Value = username;
      cmd.Parameters.Add("@ApplicationName", OdbcType.VarChar, 255).Value = ApplicationName;

      OdbcDataReader reader = null;

      try
      {
        conn.Open();

        reader = cmd.ExecuteReader();

        while (reader.Read())
        {
          tmpRoleNames += reader.GetString(0) + ",";
        }
      }
      catch (OdbcException e)
      {
        if (WriteExceptionsToEventLog)
        {
          WriteToEventLog(e, "GetRolesForUser");
        }
        else
        {
          throw e;
        }
      }
      finally
      {
        if (reader != null) { reader.Close(); }
        conn.Close();      
      }

      if (tmpRoleNames.Length > 0)
      {
        // Remove trailing comma.
        tmpRoleNames = tmpRoleNames.Substring(0, tmpRoleNames.Length - 1);
        return tmpRoleNames.Split(',');
      }

      return new string[0];
    }


    //
    // RoleProvider.GetUsersInRole
    //

    public override string[] GetUsersInRole(string rolename)
    {
      string tmpUserNames = "";

      OdbcConnection conn = new OdbcConnection(connectionString);
      OdbcCommand cmd = new OdbcCommand("SELECT Username FROM UsersInRoles "  +
                " WHERE Rolename = ? AND ApplicationName = ?", conn);

      cmd.Parameters.Add("@Rolename", OdbcType.VarChar, 255).Value = rolename;
      cmd.Parameters.Add("@ApplicationName", OdbcType.VarChar, 255).Value = ApplicationName;

      OdbcDataReader reader = null;

      try
      {
        conn.Open();

        reader = cmd.ExecuteReader();

        while (reader.Read())
        {
          tmpUserNames += reader.GetString(0) + ",";
        }
      }
      catch (OdbcException e)
      {
        if (WriteExceptionsToEventLog)
        {
          WriteToEventLog(e, "GetUsersInRole");
        }
        else
        {
          throw e;
        }
      }
      finally
      {
        if (reader != null) { reader.Close(); }
        conn.Close();      
      }

      if (tmpUserNames.Length > 0)
      {
        // Remove trailing comma.
        tmpUserNames = tmpUserNames.Substring(0, tmpUserNames.Length - 1);
        return tmpUserNames.Split(',');
      }

      return new string[0];
    }


    //
    // RoleProvider.IsUserInRole
    //

    public override bool IsUserInRole(string username, string rolename)
    {
      bool userIsInRole = false;

      OdbcConnection conn = new OdbcConnection(connectionString);
      OdbcCommand cmd = new OdbcCommand("SELECT COUNT(*) FROM UsersInRoles "  +
              " WHERE Username = ? AND Rolename = ? AND ApplicationName = ?", conn);

      cmd.Parameters.Add("@Username", OdbcType.VarChar, 255).Value = username;
      cmd.Parameters.Add("@Rolename", OdbcType.VarChar, 255).Value = rolename;
      cmd.Parameters.Add("@ApplicationName", OdbcType.VarChar, 255).Value = ApplicationName;

      try
      {
        conn.Open();

        int numRecs = (int)cmd.ExecuteScalar();

        if (numRecs > 0)
        {
          userIsInRole = true;
        }
      }
      catch (OdbcException e)
      {
        if (WriteExceptionsToEventLog)
        {
          WriteToEventLog(e, "IsUserInRole");
        }
        else
        {
          throw e;
        }
      }
      finally
      {
        conn.Close();      
      }

      return userIsInRole;
    }


    //
    // RoleProvider.RemoveUsersFromRoles
    //

    public override void RemoveUsersFromRoles(string[] usernames, string[] rolenames)
    {
      foreach (string rolename in rolenames)
      {
        if (!RoleExists(rolename))
        {
          throw new ProviderException("Role name not found.");
        }
      }

      foreach (string username in usernames)
      {
        foreach (string rolename in rolenames)
        {
          if (!IsUserInRole(username, rolename))
          {
            throw new ProviderException("User is not in role.");
          }
        }
      }


      OdbcConnection conn = new OdbcConnection(connectionString);
      OdbcCommand cmd = new OdbcCommand("DELETE FROM UsersInRoles "  +
              " WHERE Username = ? AND Rolename = ? AND ApplicationName = ?", conn);

      OdbcParameter userParm = cmd.Parameters.Add("@Username", OdbcType.VarChar, 255);
      OdbcParameter roleParm = cmd.Parameters.Add("@Rolename", OdbcType.VarChar, 255);
      cmd.Parameters.Add("@ApplicationName", OdbcType.VarChar, 255).Value = ApplicationName;

      OdbcTransaction tran = null;

      try
      {
        conn.Open();
        tran = conn.BeginTransaction();
        cmd.Transaction = tran;

        foreach (string username in usernames)
        {
          foreach (string rolename in rolenames)
          {
            userParm.Value = username;
            roleParm.Value = rolename;
            cmd.ExecuteNonQuery();
          }
        }

        tran.Commit();
      }
      catch (OdbcException e)
      {
        try
        {
          tran.Rollback();
        }
        catch { }


        if (WriteExceptionsToEventLog)
        {
          WriteToEventLog(e, "RemoveUsersFromRoles");
        }
        else
        {
          throw e;
        }
      }
      finally
      {
        conn.Close();      
      }
    }


    //
    // RoleProvider.RoleExists
    //

    public override bool RoleExists(string rolename)
    {
      bool exists = false;

      OdbcConnection conn = new OdbcConnection(connectionString);
      OdbcCommand cmd = new OdbcCommand("SELECT COUNT(*) FROM Roles "  +
                " WHERE Rolename = ? AND ApplicationName = ?", conn);

      cmd.Parameters.Add("@Rolename", OdbcType.VarChar, 255).Value = rolename;
      cmd.Parameters.Add("@ApplicationName", OdbcType.VarChar, 255).Value = ApplicationName;

      try
      {
        conn.Open();

        int numRecs = (int)cmd.ExecuteScalar();

        if (numRecs > 0)
        {
          exists = true;
        }
      }
      catch (OdbcException e)
      {
        if (WriteExceptionsToEventLog)
        {
          WriteToEventLog(e, "RoleExists");
        }
        else
        {
          throw e;
        }
      }
      finally
      {
        conn.Close();      
      }

      return exists;
    }

    //
    // RoleProvider.FindUsersInRole
    //

    public override string[] FindUsersInRole(string rolename, string usernameToMatch)
    {
      OdbcConnection conn = new OdbcConnection(connectionString);
      OdbcCommand cmd = new OdbcCommand("SELECT Username FROM UsersInRoles  " +
                "WHERE Username LIKE ? AND RoleName = ? AND ApplicationName = ?", conn);
      cmd.Parameters.Add("@UsernameSearch", OdbcType.VarChar, 255).Value = usernameToMatch;
      cmd.Parameters.Add("@RoleName", OdbcType.VarChar, 255).Value = rolename;
      cmd.Parameters.Add("@ApplicationName", OdbcType.VarChar, 255).Value = pApplicationName;

      string tmpUserNames = "";
      OdbcDataReader reader = null;

      try
      {
        conn.Open();

        reader = cmd.ExecuteReader();

        while (reader.Read())
        {
          tmpUserNames += reader.GetString(0) + ",";
        }
      }
      catch (OdbcException e)
      {
        if (WriteExceptionsToEventLog)
        {
          WriteToEventLog(e, "FindUsersInRole");
        }
        else
        {
          throw e;
        }
      }
      finally
      {
        if (reader != null) { reader.Close(); }

        conn.Close();
      }

      if (tmpUserNames.Length > 0)
      {
        // Remove trailing comma.
        tmpUserNames = tmpUserNames.Substring(0, tmpUserNames.Length - 1);
        return tmpUserNames.Split(',');
      }

      return new string[0];
    }

    //
    // WriteToEventLog
    //   A helper function that writes exception detail to the event log. Exceptions
    // are written to the event log as a security measure to avoid private database
    // details from being returned to the browser. If a method does not return a status
    // or boolean indicating the action succeeded or failed, a generic exception is also 
    // thrown by the caller.
    //

    private void WriteToEventLog(OdbcException e, string action)
    {
      EventLog log = new EventLog();
      log.Source = eventSource;
      log.Log = eventLog;

      string message = exceptionMessage + "\n\n";
      message += "Action: " + action + "\n\n";
      message += "Exception: " + e.ToString();

      log.WriteEntry(message);
    }

  }
}