Guard against teleporting back to the arena on death.

The /back command in Essentials - and similar commands from other plugins that allow you to warp back to your location of death - makes it possible to re-enter the arena after dying.

This commit builds upon the "leaving players" of commit 02f75d0 and introduces a more general notion of players being "moved". The arena is "moving" a player if the player is being teleported somewhere by MobArena (to any arena warp), and in this case, all teleports of a player are permitted. This takes care of the cases where MobArena "might be doing it". The rest of the cases are due to commands, plugins, ender pearls, etc., and they are a little easier to deal with separately. The new logic is more straightforward and should prevent most exploits and permit most legit warp cases.

This (hopefully) fixes #313.

src/main/java/com/garbagemule/MobArena/ArenaImpl.java

@@ -97,6 +97,7 @@ public class ArenaImpl implements Arena
     private Map<Player,PlayerData> playerData = new HashMap<>();
 
     private Set<Player> arenaPlayers, lobbyPlayers, readyPlayers, specPlayers, deadPlayers;
+    private Set<Player> movingPlayers;
     private Set<Player> leavingPlayers;
     private Set<Player> randoms;
 
@@ -165,6 +166,7 @@ public ArenaImpl(MobArena plugin, ConfigurationSection section, String name, Wor
         this.specPlayers    = new HashSet<>();
         this.deadPlayers    = new HashSet<>();
         this.randoms        = new HashSet<>();
+        this.movingPlayers  = new HashSet<>();
         this.leavingPlayers = new HashSet<>();
 
         // Classes, items and permissions
@@ -518,7 +520,9 @@ public boolean startArena() {
                 System.out.println("[MobArena] Invincibility glitch attempt stopped!");
             }
 
+            movingPlayers.add(p);
             p.teleport(region.getArenaWarp());
+            movingPlayers.remove(p);
             p.setAllowFlight(false);
             p.setFlying(false);
             //movePlayerToLocation(p, region.getArenaWarp());
@@ -663,6 +667,11 @@ public boolean playerJoin(Player p, Location loc)
             return false;
         }
 
+        if (movingPlayers.contains(p)) {
+            return false;
+        }
+        movingPlayers.add(p);
+
         // Announce globally (must happen before moving player)
         if (settings.getBoolean("global-join-announce", false)) {
             if (lobbyPlayers.isEmpty()) {
@@ -710,6 +719,7 @@ public boolean playerJoin(Player p, Location loc)
             }
         }
 
+        movingPlayers.remove(p);
         return true;
     }
 
@@ -785,6 +795,11 @@ public boolean playerLeave(Player p)
         return true;
     }
 
+    @Override
+    public boolean isMoving(Player p) {
+        return movingPlayers.contains(p) || leavingPlayers.contains(p);
+    }
+
     @Override
     public boolean isLeaving(Player p) {
         return leavingPlayers.contains(p);
@@ -878,11 +893,17 @@ public Location getRespawnLocation(Player p) {
 
     @Override
     public void playerSpec(Player p, Location loc) {
+        if (movingPlayers.contains(p)) {
+            return;
+        }
+        movingPlayers.add(p);
+
         storePlayerData(p, loc);
         MAUtils.sitPets(p);
         movePlayerToSpec(p);
 
         messenger.tell(p, Msg.SPEC_PLAYER_SPECTATE);
+        movingPlayers.remove(p);
     }
 
     private void spawnPets() {

src/main/java/com/garbagemule/MobArena/ArenaListener.java

@@ -1173,44 +1173,54 @@ public TeleportResponse onPlayerTeleport(PlayerTeleportEvent event) {
             return TeleportResponse.IDGAF;
         }
 
-        Location to = event.getTo();
-        Location from = event.getFrom();
         Player p = event.getPlayer();
 
-        if (region.contains(from)) {
-            // Players with proper admin permission can warp out
-            if (p.hasPermission("mobarena.admin.teleport")) {
-                return TeleportResponse.ALLOW;
-            }
-
-            // Players not in the arena are free to warp out.
-            if (!arena.inArena(p) && !arena.inLobby(p) && !arena.inSpec(p)) {
-                return TeleportResponse.ALLOW;
-            }
+        /*
+         * Players that are being moved around by the arena are always allowed
+         * to teleport. They stay in this "moving" state only during the actual
+         * transition and are removed from that state as soon as the transition
+         * is complete.
+         */
+        if (arena.isMoving(p) || p.hasPermission("mobarena.admin.teleport")) {
+            return TeleportResponse.ALLOW;
+        }
 
-            // Covers the case in which both locations are in the arena.
-            if (region.contains(to) || region.isWarp(to) || to.equals(arena.getPlayerEntry(p))) {
-                return TeleportResponse.ALLOW;
-            }
+        Location to = event.getTo();
+        Location from = event.getFrom();
 
-            arena.getMessenger().tell(p, Msg.WARP_FROM_ARENA);
-            return TeleportResponse.REJECT;
-        }
-        else if (region.contains(to)) {
-            // Players with proper admin permission can warp in
-            if (p.hasPermission("mobarena.admin.teleport")) {
+        /*
+         * At this point we're looking at warping of players that are either in
+         * the arena - but not in the "moving" state - or not in the arena. The
+         * tricky bit here is to figure out the edge cases. This is essentially
+         * a matter of players "teleporting on their own" (or with assistance
+         * from other plugins).
+         */
+        if (region.contains(from)) {
+            if (region.contains(to)) {
+                // Inside -> inside
+                if (!arena.inArena(p)) {
+                    arena.getMessenger().tell(p, Msg.WARP_TO_ARENA);
+                    return TeleportResponse.REJECT;
+                }
                 return TeleportResponse.ALLOW;
+            } else {
+                // Inside -> outside
+                if (arena.getAllPlayers().contains(p)) {
+                    arena.getMessenger().tell(p, Msg.WARP_FROM_ARENA);
+                    return TeleportResponse.REJECT;
+                }
+                return TeleportResponse.IDGAF;
             }
-
-            if (region.isWarp(from) || region.isWarp(to) || to.equals(arena.getPlayerEntry(p))) {
-                return TeleportResponse.ALLOW;
+        } else {
+            if (region.contains(to)) {
+                // Outside -> inside
+                arena.getMessenger().tell(p, Msg.WARP_TO_ARENA);
+                return TeleportResponse.REJECT;
+            } else {
+                // Outside -> outside
+                return TeleportResponse.IDGAF;
             }
-
-            arena.getMessenger().tell(p, Msg.WARP_TO_ARENA);
-            return TeleportResponse.REJECT;
         }
-
-        return TeleportResponse.IDGAF;
     }
 
     public void onPlayerCommandPreprocess(PlayerCommandPreprocessEvent event) {

src/main/java/com/garbagemule/MobArena/framework/Arena.java

@@ -154,6 +154,8 @@ public interface Arena
 
     boolean playerLeave(Player p);
 
+    boolean isMoving(Player p);
+
     boolean isLeaving(Player p);
 
     void playerDeath(Player p);