Ticket #3254: t3254_arbitrary_observer_limit_v1.patch

binaries/data/config/default.cfg

@@ -352 +352 @@
 enabledmods = "mod public"
 
 [network]
 duplicateplayernames = false      ; Rename joining player to "User (2)" if "User" is already connected, otherwise prohibit join.
 lateobserverjoins = false         ; Allow observers to join the game after it started
+observerlimit = 5                 ; Allow observers to join the game after it started
 
 [overlay]
 fps = "false"                     ; Show frames per second in top right corner
 realtime = "false"                ; Show current system time in top right corner
 netwarnings = "true"              ; Show warnings if the network connection is bad

binaries/data/mods/public/gui/common/network.js

@@ -56 +56 @@
     case 3: return translate("Game is loading, please try later");
     case 4: return translate("Game has already started, no observers allowed");
     case 5: return translate("You have been kicked");
     case 6: return translate("You have been banned");
     case 7: return translate("Playername in use. If you were disconnected, retry in few seconds");
+    case 8: return translate("Server full");
     default:
         warn("Unknown disconnect-reason ID received: " + id);
         return sprintf(translate("\\[Invalid value %(id)s]"), { "id": id });
     }
 }

binaries/data/mods/public/gui/options/options.json

@@ -64 +64 @@
         {
             "type": "boolean",
             "label": "Late Observer Joins",
             "tooltip": "Allow observers to join the game after it started",
             "parameters": { "config": "network.lateobserverjoins" }
+        },
+        {
+            "type": "number",
+            "label": "Observer Limit",
+            "tooltip": "Prevent further observer from joining if the limit is reached",
+            "parameters": { "config": "network.observerlimit", "min": 0, "max": 16 }
         }
     ],
     "graphicsSetting":
     [
         {

source/network/NetHost.h

@@ -64 +64 @@
     NDR_INCORRECT_PROTOCOL_VERSION,
     NDR_SERVER_LOADING,
     NDR_SERVER_ALREADY_IN_GAME,
     NDR_KICKED,
     NDR_BANNED,
-    NDR_PLAYERNAME_IN_USE
+    NDR_PLAYERNAME_IN_USE,
+    NDR_SERVER_FULL
 };
 
 class CNetHost
 {
 public:

source/network/NetServer.cpp

@@ -37 +37 @@
 #include <miniupnpc/miniupnpc.h>
 #include <miniupnpc/upnpcommands.h>
 #include <miniupnpc/upnperrors.h>
 #endif
 
+/**
+ * Number of peers to allocate for the enet host.
+ * Limited by ENET_PROTOCOL_MAXIMUM_PEER_ID (4096).
+ *
+ * At most 8 players, 16 observers and 1 temporary connection to send the "server full" disconnect-reason.
+ */
+#define MAX_CLIENTS 25
+
 #define DEFAULT_SERVER_NAME         L"Unnamed Server"
 #define DEFAULT_WELCOME_MESSAGE     L"Welcome"
-#define MAX_CLIENTS                 10
 
 static const int CHANNEL_COUNT = 1;
 
 /**
  * enet_host_service timeout (msecs).
@@ -927 +934 @@
 
     // Optionally allow observers to join after the game has started
     bool observerLateJoin = false;
     CFG_GET_VAL("network.lateobserverjoins", observerLateJoin);
 
-    // If the game has already started, only allow rejoins
+    int maxObservers = 0;
+    CFG_GET_VAL("network.observerlimit", maxObservers);
+
     bool isRejoining = false;
-    if (server.m_State != SERVER_STATE_PREGAME)
+    bool serverFull = false;
+    if (server.m_State == SERVER_STATE_PREGAME)
     {
-        // Search for an old disconnected player of the same name
-        // (TODO: if GUIDs were stable, we should use them instead)
-        isRejoining =
-            observerLateJoin ||
-            std::find_if(
-                server.m_PlayerAssignments.begin(), server.m_PlayerAssignments.end(),
-                [&username] (const std::pair<CStr, PlayerAssignment>& pair)
-                { return !pair.second.m_Enabled && pair.second.m_Name == username; })
-            != server.m_PlayerAssignments.end();
+        // Don't check for maxObservers in the gamesetup, as we don't know who will be assigned
+        serverFull = server.m_Sessions.size() >= MAX_CLIENTS;
+    }
+    else
+    {
+        isRejoining = observerLateJoin;
+        bool isObserver = true;
+        int disconnectedPlayers = 0;
+        int connectedPlayers = 0;
+        for (PlayerAssignmentMap::iterator it = server.m_PlayerAssignments.begin(); it != server.m_PlayerAssignments.end(); ++it)
+        {
+            // (TODO: if GUIDs were stable, we should use them instead)
+            if (!it->second.m_Enabled && it->second.m_Name == username)
+            {
+                isObserver = it->second.m_PlayerID == -1;
+                isRejoining = true;
+            }
+
+            if (it->second.m_PlayerID == -1)
+                continue;
 
+            if (it->second.m_Enabled)
+                ++connectedPlayers;
+            else
+                ++disconnectedPlayers;
+        }
+
+        // If the game has already started, only allow rejoins
         // Players who weren't already in the game are not allowed to join now that it's started
         if (!isRejoining)
         {
             LOGMESSAGE("Refused connection after game start from not-previously-known user \"%s\"", utf8_from_wstring(username));
             session->Disconnect(NDR_SERVER_ALREADY_IN_GAME);
             return true;
         }
+
+        // Ensure all players will be able to rejoin
+        serverFull = isObserver && (
+            (int) server.m_Sessions.size() - connectedPlayers > maxObservers ||
+            (int) server.m_Sessions.size() + disconnectedPlayers >= MAX_CLIENTS);
+    }
+
+    if (serverFull)
+    {
+        session->Disconnect(NDR_SERVER_FULL);
+        return true;
     }
 
     // TODO: check server password etc?
 
     u32 newHostID = server.m_NextHostID++;