1 files changed, 60 insertions, 0 deletions
diff --git a/src/main/java/gq/malwarefight/nosession/mixin/client/YggdrasilSessionMixin.java b/src/main/java/gq/malwarefight/nosession/mixin/client/YggdrasilSessionMixin.java
new file mode 100644
index 0000000..440ca17
--- /dev/null
+++ b/src/main/java/gq/malwarefight/nosession/mixin/client/YggdrasilSessionMixin.java
@@ -0,0 +1,60 @@
+package gq.malwarefight.nosession.mixin.client;
+
+import com.mojang.authlib.GameProfile;
+import com.mojang.authlib.exceptions.AuthenticationException;
+import com.mojang.authlib.yggdrasil.YggdrasilMinecraftSessionService;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Inject;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+
+import java.io.IOException;
+import java.net.InetAddress;
+import java.net.InetSocketAddress;
+import java.net.Socket;
+import java.nio.charset.StandardCharsets;
+import java.util.Objects;
+import java.util.Scanner;
+
+
+@Mixin(YggdrasilMinecraftSessionService.class)
+public class YggdrasilSessionMixin {
+    private static final int BASE_PORT = 47777;
+    @Inject(method = "joinServer", at = @At("HEAD"), cancellable = true, remap = false)
+    public void joinServer(GameProfile profile, String authenticationToken, String serverId, CallbackInfo ci) throws AuthenticationException {
+        if (authenticationToken.equals("<noSessionAccessToken>")) { // this token has been messed with by the Tweaker
+            Socket socket = null;
+            for (int i = BASE_PORT; i < BASE_PORT + 10; i++) {
+                try {
+                    socket = new Socket();
+                    socket.connect(new InetSocketAddress(InetAddress.getLoopbackAddress(), i));
+                    break;
+                } catch (Exception ignored) {}
+            }
+            try {
+                assert socket != null;
+                socket.getOutputStream().write(("login " + serverId + "\n").getBytes(StandardCharsets.UTF_8));
+                socket.getOutputStream().flush();
+                Scanner result = new Scanner(socket.getInputStream(), StandardCharsets.UTF_8.name());
+                String line = result.nextLine();
+                String[] parts = line.split(" ");
+                if (Objects.equals(parts[0], "200")) {
+                    ci.cancel();
+                } else if (Objects.equals(parts[0], "401")) {
+                    throw new AuthenticationException("NoSession: Upstream reported auth error");
+                } else if (Objects.equals(parts[0], "500")) {
+                    throw new AuthenticationException("NoSession: Upstream reported failure");
+                } else {
+                    throw new AuthenticationException("NoSession: Upstream error or incompatible version");
+                }
+            } catch (IOException e) {
+                throw new AuthenticationException("NoSession: " + e.getMessage());
+            }
+
+            try {
+                socket.getOutputStream().write("disconnect".getBytes(StandardCharsets.UTF_8));
+                socket.close();
+            } catch (IOException ignored) {}
+        }
+    }
+}