Changed login event to prelogin and postlogin, if you set the args of prelogin to true, the login is ignored. In this case, if the server is loginbeforejoin, you need to kick the player with whatever reason otherwise bad things will happen.

TShockAPI/Commands.cs

@@ -381,17 +381,22 @@ namespace TShockAPI
 				TShock.Utils.Kick(args.Player, "Too many invalid login attempts.");
 				return;
 			}
-
+            
 			User user = TShock.Users.GetUserByName(args.Player.Name);
 			string encrPass = "";
 
 			if (args.Parameters.Count == 1)
 			{
+                if (Hooks.PlayerHooks.OnPlayerPreLogin(args.Player, args.Player.Name, args.Parameters[0]))
+                    return;
 				user = TShock.Users.GetUserByName(args.Player.Name);
 				encrPass = TShock.Utils.HashPassword(args.Parameters[0]);
 			}
 			else if (args.Parameters.Count == 2 && TShock.Config.AllowLoginAnyUsername)
 			{
+                if (Hooks.PlayerHooks.OnPlayerPreLogin(args.Player, args.Parameters[0], args.Parameters[1]))
+                    return;
+
 				user = TShock.Users.GetUserByName(args.Parameters[0]);
 				encrPass = TShock.Utils.HashPassword(args.Parameters[1]);
 				if (String.IsNullOrEmpty(args.Parameters[0]))
@@ -408,6 +413,7 @@ namespace TShockAPI
 			}
 			try
 			{
+                // TODO: Is this needed? It seems to be an unreachable case
 				if (user == null)
 				{
 					args.Player.SendErrorMessage("A user by that name does not exist.");
@@ -464,7 +470,7 @@ namespace TShockAPI
 
 					}
 
-				    Hooks.PlayerHooks.OnPlayerLogin(args.Player);
+				    Hooks.PlayerHooks.OnPlayerPostLogin(args.Player);
 				}
 				else
 				{

TShockAPI/GetDataHandlers.cs

@@ -1336,6 +1336,10 @@ namespace TShockAPI
 				return true;
 
 			string password = Encoding.UTF8.GetString(args.Data.ReadBytes((int) (args.Data.Length - args.Data.Position - 1)));
+
+            if (Hooks.PlayerHooks.OnPlayerPreLogin(args.Player, args.Player.Name, password))
+                return true;
+
 			var user = TShock.Users.GetUserByName(args.Player.Name);
             if (user != null && !TShock.Config.DisableLoginBeforeJoin)
 			{
@@ -1385,7 +1389,7 @@ namespace TShockAPI
 			        }
 			        args.Player.SendMessage("Authenticated as " + args.Player.Name + " successfully.", Color.LimeGreen);
 					Log.ConsoleInfo(args.Player.Name + " authenticated successfully as user " + args.Player.Name + ".");
-                    Hooks.PlayerHooks.OnPlayerLogin(args.Player);
+                    Hooks.PlayerHooks.OnPlayerPostLogin(args.Player);
 					return true;
 				}
 				TShock.Utils.ForceKick(args.Player, "Invalid user account password.", true);

TShockAPI/Hooks/PlayerHooks.cs

@@ -6,15 +6,22 @@ using System.Text;
 
 namespace TShockAPI.Hooks
 {
-    public class PlayerLoginEventArgs
+    public class PlayerPostLoginEventArgs
     {
         public TSPlayer Player { get; set; }
-        public PlayerLoginEventArgs(TSPlayer ply)
+        public PlayerPostLoginEventArgs(TSPlayer ply)
         {
             Player = ply;
         }
     }
 
+    public class PlayerPreLoginEventArgs : HandledEventArgs
+    {
+        public TSPlayer Player { get; set; }
+        public string LoginName { get; set; }
+        public string Password { get; set; }
+    }
+
     public class PlayerCommandEventArgs : HandledEventArgs
     {
         public TSPlayer Player { get; set; }
@@ -25,20 +32,24 @@ namespace TShockAPI.Hooks
 
     public static class PlayerHooks
     {
-        public delegate void PlayerLoginD(PlayerLoginEventArgs e);
+        public delegate void PlayerPostLoginD(PlayerPostLoginEventArgs e);
-        public static event PlayerLoginD PlayerLogin;
+        public static event PlayerPostLoginD PlayerPostLogin;
+
+        public delegate void PlayerPreLoginD(PlayerPreLoginEventArgs e);
+        public static event PlayerPreLoginD PlayerPreLogin;
+
         public delegate void PlayerCommandD(PlayerCommandEventArgs e);
         public static event PlayerCommandD PlayerCommand;
 
-        public static void OnPlayerLogin(TSPlayer ply)
+        public static void OnPlayerPostLogin(TSPlayer ply)
         {
-            if(PlayerLogin == null)
+            if(PlayerPostLogin == null)
             {
                 return;
             }
 
-            PlayerLoginEventArgs args = new PlayerLoginEventArgs(ply);
+            PlayerPostLoginEventArgs args = new PlayerPostLoginEventArgs(ply);
-            PlayerLogin(args);
+            PlayerPostLogin(args);
         }
 
         public static bool OnPlayerCommand(TSPlayer player, string cmdName, string cmdText, List<string> args)
@@ -58,5 +69,15 @@ namespace TShockAPI.Hooks
             PlayerCommand(playerCommandEventArgs);
             return playerCommandEventArgs.Handled;
         }
+
+        public static bool OnPlayerPreLogin(TSPlayer ply, string name, string pass)
+        {
+            if (PlayerPreLogin == null)
+                return false;
+
+            var args = new PlayerPreLoginEventArgs {Player = ply, LoginName = name, Password = pass};
+            PlayerPreLogin(args);
+            return args.Handled;
+        }
     }
 }