如果 5 次尝试失败，则锁定用户

如果您遵循您的方案，即当用户无效时，它只会减少您的无效尝试。除非用户正确输入登录凭据，否则它实际上不会挂起用户。

实际上，您的sudo逻辑应该去：

1. 验证凭据
   1. 凭据有效
      1. 检查帐户状态，被暂停，然后拒绝访问
      2. 将尝试重置回 5
      3. 允许用户进入应用程序
   2. 凭据无效
      1. 将尝试次数减少一次
      2. 如果需要，将帐户设置为已暂停

很多这样的逻辑实际上可以绑定到一两个方法中。同样在DecreaseAttempts()方法中，您有两个 SQL 命令，其中永远不会执行 sql 命令cmd

下面是一个在返回状态枚举的方法中执行此操作的示例。现在这是一个非常基本的示例，但只需要一种方法来执行您的完全授权方法。我已经注释了代码。

public partial class UserManager 
{
    const int MaxAttempts = 5;
    public LoginStatus ValidateUser(string username, string password)
    {
        if (string.IsNullOrWhiteSpace(username))
            throw new ArgumentNullException("username");
        //set the password to empty if it is null
        password = password ?? "";
        //create the connection
        using (var connection = new SqlConnection(Configuration.ConnectionString))
        {
            //assign some local variables
            int attemptsLeft = MaxAttempts;
            string currentStatus = "Active";
            string userPassword = null;
            //get the information for the user, only query by username so we have all the data. We will match the password later on
            string query = "SELECT TOP(1) [Username], [Password], [AttemptsLeft], [CurrentStatus] FROM [Information] WHERE Username = @username";
            using (var command = new SqlCommand(query, connection))
            {
                command.Parameters.AddWithValue("@username", username);
                command.CommandType = System.Data.CommandType.Text;
                connection.Open();
                using (var reader = command.ExecuteReader())
                {
                    //no rows.. Invalid username
                    if (!reader.HasRows)
                    {
                        connection.Close();
                        return LoginStatus.InvalidCredentials;
                    }
                    //read the first row (hence the break)
                    while (reader.Read())
                    {
                        attemptsLeft = (int)reader["AttemptsLeft"];
                        currentStatus = (string)reader["CurrentStatus"];
                        userPassword = (string)reader["Password"];
                        break;
                    }
                    reader.Close();
                }
                connection.Close();
            }
            //if the account is suspended then dont even bother with password checking
            if (currentStatus.Equals("Suspended", StringComparison.CurrentCultureIgnoreCase))
            {
                return LoginStatus.Suspended;
            }
            //invalid password lets handle the invalid credentials logic
            if (!password.Equals(userPassword))
            {
                attemptsLeft -= 1;
                //decrease the attempts, lets just stop at zero as we dont need negative attempts
                if(attemptsLeft >= 0)
                {
                    query = "UPDATE [Information] SET [AttemptsLeft] = @attemptsLeft WHERE Username = @username";
                    using (var command = new SqlCommand(query, connection))
                    {
                        command.Parameters.AddWithValue("@username", username);
                        command.Parameters.AddWithValue("@attemptsLeft", attemptsLeft);
                        connection.Open();
                        command.ExecuteNonQuery();
                        connection.Close();
                    }
                }
                //suspend the account when attempts less than or equal to zero
                if (attemptsLeft <= 0)
                {
                    query = "UPDATE [Information] SET [CurrentStatus] = @currentStatus WHERE Username = @username";
                    using (var command = new SqlCommand(query, connection))
                    {
                        command.Parameters.AddWithValue("@username", username);
                        command.Parameters.AddWithValue("@currentStatus", "Suspended");
                        connection.Open();
                        command.ExecuteNonQuery();
                        connection.Close();
                    }
                    //exit method as login account suspended
                    return LoginStatus.Suspended;
                }
                //exit as invalid login credentials
                return LoginStatus.InvalidCredentials;
            }
            //if we are here lets quickly reset the login attempts back to 5, and account status to active as this is a valid login
            query = "UPDATE [Information] SET [AttemptsLeft] = @attemptsLeft, [CurrentStatus] = @currentStatus WHERE Username = @username";
            using (var command = new SqlCommand(query, connection))
            {
                command.Parameters.AddWithValue("@username", username);
                command.Parameters.AddWithValue("@attemptsLeft", MaxAttempts);
                command.Parameters.AddWithValue("@currentStatus", "Active");
                connection.Open();
                command.ExecuteNonQuery();
                connection.Close();
            }
            //if we got here then every thing is a match
            return LoginStatus.Authorized;
        }
    }
}
public enum LoginStatus
{
    Authorized,
    InvalidCredentials,
    Suspended
}

要使用此功能，可以像下面一样简单（请注意，您必须更改视图重定向）

[HttpPost]
public ActionResult Index(string username, string password)
{
    if(string.IsNullOrWhiteSpace(username))
    {
        this.ModelState.AddModelError("", "Invalid Login Credential. No username sent.");
        return View();
    }
    var manager = new UserManager();
    var result = manager.ValidateUser(username, password);
    switch (result)
    {
        case LoginStatus.Authorized:
            return RedirectToAction("About", "Home");
        case LoginStatus.InvalidCredentials:
            this.ModelState.AddModelError("", "Invalid Login Credentials. Username or password incorrect");
            break;
        case LoginStatus.Suspended:
            this.ModelState.AddModelError("", "Account Suspeneded");
            break;
    }
    return View();
}

只是为了好玩，我把它重写成一个简单的存储过程。

CREATE PROCEDURE ValidateUser
    @username nvarchar(50),
    @password nvarchar(50)
AS
BEGIN
    SET NOCOUNT ON;
    DECLARE @userPassword nvarchar(50) = NULL
    DECLARE @maxAttempts int  = 5
    DECLARE @attemptsLeft int = 5
    DECLARE @currentStatus nvarchar(50)
    /*
        RETURN CODES:
        0 = Authorized
        1 = InvalidCredentials
        2 = Suspended
    */

    SELECT TOP(1) @userPassword = [UserName], @attemptsLeft = [AttemptsLeft], @currentStatus = [CurrentStatus] FROM [Information] WHERE UserName = @username
    IF @userPassword IS NULL
        BEGIN
            SELECT 1 as [Result], @maxAttempts as [AttemptsRemaining]
            RETURN
        END
    --account suspended.. Return a suspended result
    If @currentStatus = 'Suspended'
        BEGIN
            SELECT 2 as [Result], 0 as [AttemptsRemaining]
            RETURN
        END
    --passwords dont match (note this is case insensitive on default collation)
    If @password IS NULL OR @password <> @userPassword
        BEGIN
            --decrease attempts
            SET @attemptsLeft = @attemptsLeft - 1
            --if the attempts left are greater than 0 then set the account active and decrease the attempts remaining
            IF @attemptsLeft > 0
                BEGIN
                    UPDATE [Information] SET [CurrentStatus] = 'Active', AttemptsLeft = @attemptsLeft WHERE UserName = @username
                    SELECT 1 as [Result], @attemptsLeft as [AttemptsRemaining]
                    RETURN
                END
            --else the attempts left are less than or equal to zero therefore they should be suspended and attempts left set to zero (dont want negative attempts)
            ELSE
                BEGIN
                    UPDATE [Information] SET [CurrentStatus] = 'Suspended', AttemptsLeft = 0 WHERE UserName = @username
                    SELECT 2 as [Result], 0 as [AttemptsRemaining]
                    RETURN
                END
        END
    --if we get here then all is good and we can just reset the account status and max attempts for the next login attempt
    UPDATE [Information] SET [CurrentStatus] = 'Active', AttemptsLeft = @maxAttempts WHERE UserName = @username
    SELECT 0 as [Result], @maxAttempts AS [AttemptsRemaining]
END
GO

然后调用它非常简单（注意，我还将返回类型更改为返回状态和剩余尝试的调用。

方法

public LoginResult ValidateUserStoredProcedure(string username, string password)
{
    if (string.IsNullOrWhiteSpace(username))
        throw new ArgumentNullException("username");
    //set the password to empty if it is null
    password = password ?? "";
    //create the connection
    using (var connection = new SqlConnection(Configuration.ConnectionString))
    {
        var result = new LoginResult
        {
            AttemptsRemaining = 5,
            Status = LoginStatus.InvalidCredentials
        };
        try
        {
            using (var command = new SqlCommand("EXEC ValidateUser @username, @password", connection))
            {
                command.Parameters.AddWithValue("@username", username);
                command.Parameters.AddWithValue("@password", password);
                command.CommandType = System.Data.CommandType.Text;
                connection.Open();
                using (var reader = command.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        result.Status = ((LoginStatus)(int)reader["Result"]);
                        result.AttemptsRemaining = (int)reader["AttemptsRemaining"];
                        break;
                    }
                    reader.Close();
                }
                connection.Close();
            }
            return result;
        }
        catch (Exception ex)
        {
            if (connection.State != System.Data.ConnectionState.Closed)
                connection.Close();
            Debug.WriteLine("Error on sql query:" + ex.Message);
            return result;
        }
    }
}

结果类

public class LoginResult
{
    public LoginStatus Status { get; set; }
    public int AttemptsRemaining { get; set; }
}
public enum LoginStatus : int
{
    Authorized = 0,
    InvalidCredentials = 1,
    Suspended = 2
}

控制器

[HttpPost]
public ActionResult Index(string username, string password)
{
    if (string.IsNullOrWhiteSpace(username))
    {
        this.ModelState.AddModelError("", "Invalid Login Credential. No username sent.");
        return View();
    }
    var manager = new UserManager();
    var result = manager.ValidateUserStoredProcedure(username, password);
    switch (result.Status)
    {
        case LoginStatus.Authorized:
            return RedirectToAction("About", "Home");
        case LoginStatus.InvalidCredentials:
            if (result.AttemptsRemaining < 5)
                this.ModelState.AddModelError("", "Invalid Login Credentials. Username or password incorrect. Attempts remaining:" + result.AttemptsRemaining);
            else
                this.ModelState.AddModelError("", "Invalid Login Credentials. Username or password incorrect.");
            break;
        case LoginStatus.Suspended:
            this.ModelState.AddModelError("", "Account Suspeneded");
            break;
    }
    return View();
}

如何优化取决于您，但这种授权级别相当弱。它还显示您将密码存储为纯文本。但这是另一个话题。