UPnP Port Forwarding

Co-authored-by: omega24 <ben@omega24.dev>

purpur-server/build.gradle.kts.patch

@@ -51,12 +51,13 @@
      implementation("ca.spottedleaf:concurrentutil:0.0.2") // Paper - Add ConcurrentUtil dependency
      // Paper start
      implementation("org.jline:jline-terminal-ffm:3.27.1") // use ffm on java 22+
-@@ -155,6 +_,9 @@
+@@ -155,6 +_,10 @@
      }
      // Paper end - Use Velocity cipher
  
 +    implementation("org.mozilla:rhino-runtime:1.7.14") // Purpur
 +    implementation("org.mozilla:rhino-engine:1.7.14") // Purpur
++    implementation("dev.omega24:upnp4j:1.0") // Purpur
 +
      runtimeOnly("org.apache.maven:maven-resolver-provider:3.9.6")
      runtimeOnly("org.apache.maven.resolver:maven-resolver-connector-basic:1.9.18")

purpur-server/minecraft-patches/sources/net/minecraft/server/MinecraftServer.java.patch

@@ -17,14 +17,32 @@
      // Spigot end
      public volatile boolean hasFullyShutdown; // Paper - Improved watchdog support
      public volatile boolean abnormalExit; // Paper - Improved watchdog support
-@@ -302,6 +_,7 @@
+@@ -302,7 +_,9 @@
      public final io.papermc.paper.configuration.PaperConfigurations paperConfigurations; // Paper - add paper configuration files
      public boolean isIteratingOverLevels = false; // Paper - Throw exception on world create while being ticked
      private final Set<String> pluginsBlockingSleep = new java.util.HashSet<>(); // Paper - API to allow/disallow tick sleeping
 +    public boolean lagging = false; // Purpur - Lagging threshold
      public static final long SERVER_INIT = System.nanoTime(); // Paper - Lag compensation
++    protected boolean upnp = false; // Purpur - UPnP Port Forwarding
  
      public static <S extends MinecraftServer> S spin(Function<Thread, S> threadFunction) {
+         ca.spottedleaf.dataconverter.minecraft.datatypes.MCTypeRegistry.init(); // Paper - rewrite data converter system
+@@ -1001,6 +_,15 @@
+ 
+         LOGGER.info("Stopping server");
+         Commands.COMMAND_SENDING_POOL.shutdownNow(); // Paper - Perf: Async command map building; Shutdown and don't bother finishing
++        // Purpur start - UPnP Port Forwarding
++        if (upnp) {
++            if (dev.omega24.upnp4j.UPnP4J.close(this.getPort(), dev.omega24.upnp4j.util.Protocol.TCP)) {
++                LOGGER.info("[UPnP] Port {} closed", this.getPort());
++            } else {
++                LOGGER.error("[UPnP] Failed to close port {}", this.getPort());
++            }
++        }
++        // Purpur end - UPnP Port Forwarding
+         // CraftBukkit start
+         if (this.server != null) {
+             this.server.spark.disable(); // Paper - spark
 @@ -1093,6 +_,7 @@
          this.safeShutdown(waitForServer, false);
      }

purpur-server/minecraft-patches/sources/net/minecraft/server/dedicated/DedicatedServer.java.patch

@@ -16,6 +16,37 @@
          com.destroystokyo.paper.VersionHistoryManager.INSTANCE.getClass(); // Paper - load version history now
  
          this.setPvpAllowed(properties.pvp);
+@@ -271,6 +_,30 @@
+             if (true) throw new IllegalStateException("Failed to bind to port", var10); // Paper - Propagate failed to bind to port error
+             return false;
+         }
++        // Purpur start - UPnP Port Forwarding
++        if (org.purpurmc.purpur.PurpurConfig.useUPnP) {
++            LOGGER.info("[UPnP] Attempting to start UPnP port forwarding service...");
++            if (dev.omega24.upnp4j.UPnP4J.isUPnPAvailable()) {
++                if (dev.omega24.upnp4j.UPnP4J.isOpen(this.getPort(), dev.omega24.upnp4j.util.Protocol.TCP)) {
++                    this.upnp = false;
++                    LOGGER.info("[UPnP] Port {} is already open", this.getPort());
++                } else if (dev.omega24.upnp4j.UPnP4J.open(this.getPort(), dev.omega24.upnp4j.util.Protocol.TCP)) {
++                    this.upnp = true;
++                    LOGGER.info("[UPnP] Successfully opened port {}", this.getPort());
++                } else {
++                    this.upnp = false;
++                    LOGGER.info("[UPnP] Failed to open port {}", this.getPort());
++                }
++
++                if (upnp) {
++                    LOGGER.info("[UPnP] {}:{}", dev.omega24.upnp4j.UPnP4J.getExternalIP(), this.getPort());
++                }
++            } else {
++                this.upnp = false;
++                LOGGER.error("[UPnP] Service is unavailable");
++            }
++        }
++        // Purpur end - UPnP Port Forwarding
+ 
+         // CraftBukkit start
+         // this.setPlayerList(new DedicatedPlayerList(this, this.registries(), this.playerDataStorage)); // Spigot - moved up
 @@ -350,6 +_,7 @@
                  LOGGER.info("JMX monitoring enabled");
              }

purpur-server/src/main/java/org/purpurmc/purpur/PurpurConfig.java

@@ -414,4 +414,9 @@ public class PurpurConfig {
     private static void tpsCatchup() {
         tpsCatchup = getBoolean("settings.tps-catchup", tpsCatchup);
     }
+
+    public static boolean useUPnP = false;
+    private static void networkSettings() {
+        useUPnP = getBoolean("settings.network.upnp-port-forwarding", useUPnP);
+    }
 }