reject clients on version mismatch (#2106)

src/main/java/emu/grasscutter/server/http/dispatch/RegionHandler.java

@@ -1,12 +1,15 @@
 package emu.grasscutter.server.http.dispatch;
 
 import com.google.protobuf.ByteString;
+import emu.grasscutter.GameConstants;
 import emu.grasscutter.Grasscutter;
 import emu.grasscutter.Grasscutter.ServerRunMode;
 import emu.grasscutter.net.proto.QueryRegionListHttpRspOuterClass.QueryRegionListHttpRsp;
 import emu.grasscutter.net.proto.QueryCurrRegionHttpRspOuterClass.QueryCurrRegionHttpRsp;
 import emu.grasscutter.net.proto.RegionSimpleInfoOuterClass.RegionSimpleInfo;
 import emu.grasscutter.net.proto.RegionInfoOuterClass.RegionInfo;
+import emu.grasscutter.net.proto.RetcodeOuterClass.Retcode;
+import emu.grasscutter.net.proto.StopServerInfoOuterClass.StopServerInfo;
 import emu.grasscutter.server.event.dispatch.QueryAllRegionsEvent;
 import emu.grasscutter.server.event.dispatch.QueryCurrentRegionEvent;
 import emu.grasscutter.server.http.Router;
@@ -16,6 +19,7 @@ import emu.grasscutter.utils.Utils;
 import io.javalin.Javalin;
 import io.javalin.http.Context;
 
+import java.time.Instant;
 import javax.crypto.Cipher;
 import java.io.ByteArrayOutputStream;
 import java.util.*;
@@ -202,7 +206,8 @@ public final class RegionHandler implements Router {
                 regionData = region.getBase64();
         }
 
-        String[] versionCode = versionName.replaceAll(Pattern.compile("[a-zA-Z]").pattern(), "").split("\\.");
+        String clientVersion = versionName.replaceAll(Pattern.compile("[a-zA-Z]").pattern(), "");
+        String[] versionCode = clientVersion.split("\\.");
         int versionMajor = Integer.parseInt(versionCode[0]);
         int versionMinor = Integer.parseInt(versionCode[1]);
         int versionFix   = Integer.parseInt(versionCode[2]);
@@ -211,6 +216,30 @@ public final class RegionHandler implements Router {
             try {
                 QueryCurrentRegionEvent event = new QueryCurrentRegionEvent(regionData); event.call();
 
+                String key_id = ctx.queryParam("key_id");
+
+                if (!clientVersion.equals(GameConstants.VERSION)) { // Reject clients when there is a version mismatch
+
+                    boolean updateClient = GameConstants.VERSION.compareTo(clientVersion) > 0;
+
+                    QueryCurrRegionHttpRsp rsp = QueryCurrRegionHttpRsp.newBuilder()
+                        .setRetcode(Retcode.RET_STOP_SERVER_VALUE)
+                        .setMsg("Connection Failed!")
+                        .setRegionInfo(RegionInfo.newBuilder())
+                        .setStopServer(StopServerInfo.newBuilder()
+                            .setUrl("https://discord.gg/grasscutters")
+                            .setStopBeginTime((int) Instant.now().getEpochSecond())
+                            .setStopEndTime((int) Instant.now().getEpochSecond()*2)
+                            .setContentMsg(updateClient ? "\nVersion mismatch outdated client! \n\nServer version: %s\nClient version: %s".formatted(GameConstants.VERSION, clientVersion) : "\nVersion mismatch outdated server! \n\nServer version: %s\nClient version: %s".formatted(GameConstants.VERSION, clientVersion))
+                            .build())
+                        .buildPartial();
+
+                    Grasscutter.getLogger().info(String.format("Connection denied for %s due to %s", ctx.ip(), updateClient ? "outdated client!" : "outdated server!"));
+
+                    ctx.json(Crypto.encryptAndSignRegionData(rsp.toByteArray(), key_id));
+                    return;
+                }
+
                 if (ctx.queryParam("dispatchSeed") == null) {
                     // More love for UA Patch players
                     var rsp = new QueryCurRegionRspJson();
@@ -222,39 +251,10 @@ public final class RegionHandler implements Router {
                     return;
                 }
 
-                String key_id = ctx.queryParam("key_id");
 
-                if (key_id == null)
-                    throw new Exception("Key ID was not set");
-
-                Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
-                cipher.init(Cipher.ENCRYPT_MODE, Crypto.EncryptionKeys.get(Integer.valueOf(key_id)));
                 var regionInfo = Utils.base64Decode(event.getRegionInfo());
 
-                //Encrypt regionInfo in chunks
+                ctx.json(Crypto.encryptAndSignRegionData(regionInfo, key_id));
-                ByteArrayOutputStream encryptedRegionInfoStream = new ByteArrayOutputStream();
-
-                //Thank you so much GH Copilot
-                int chunkSize = 256 - 11;
-                int regionInfoLength = regionInfo.length;
-                int numChunks = (int) Math.ceil(regionInfoLength / (double) chunkSize);
-
-                for (int i = 0; i < numChunks; i++) {
-                    byte[] chunk = Arrays.copyOfRange(regionInfo, i * chunkSize, Math.min((i + 1) * chunkSize, regionInfoLength));
-                    byte[] encryptedChunk = cipher.doFinal(chunk);
-                    encryptedRegionInfoStream.write(encryptedChunk);
-                }
-
-                Signature privateSignature = Signature.getInstance("SHA256withRSA");
-                privateSignature.initSign(Crypto.CUR_SIGNING_KEY);
-                privateSignature.update(regionInfo);
-
-                var rsp = new QueryCurRegionRspJson();
-
-                rsp.content = Utils.base64Encode(encryptedRegionInfoStream.toByteArray());
-                rsp.sign = Utils.base64Encode(privateSignature.sign());
-
-                ctx.json(rsp);
             }
             catch (Exception e) {
                 Grasscutter.getLogger().error("An error occurred while handling query_cur_region.", e);

src/main/java/emu/grasscutter/utils/Crypto.java

@@ -1,20 +1,26 @@
 package emu.grasscutter.utils;
 
+import emu.grasscutter.server.http.objects.QueryCurRegionRspJson;
+import java.io.ByteArrayOutputStream;
 import java.io.File;
 import java.nio.file.Path;
 import java.security.KeyFactory;
 import java.security.PrivateKey;
 import java.security.PublicKey;
 import java.security.SecureRandom;
+import java.security.Signature;
 import java.security.spec.PKCS8EncodedKeySpec;
 import java.security.spec.X509EncodedKeySpec;
+import java.util.Arrays;
 import java.util.Map;
 import java.util.HashMap;
 import java.util.regex.Pattern;
 
 import emu.grasscutter.Grasscutter;
+import javax.crypto.Cipher;
 
 public final class Crypto {
+
     private static final SecureRandom secureRandom = new SecureRandom();
 
     public static byte[] DISPATCH_KEY;
@@ -45,8 +51,7 @@ public final class Crypto {
 
                     var m = pattern.matcher(path.getFileName().toString());
 
-                    if (m.matches())
+                    if (m.matches()) {
-                    {
                         var key = KeyFactory.getInstance("RSA")
                             .generatePublic(new X509EncodedKeySpec(FileUtils.read(path)));
 
@@ -54,8 +59,7 @@ public final class Crypto {
                     }
                 }
             }
-        }
+        } catch (Exception e) {
-        catch (Exception e) {
             Grasscutter.getLogger().error("An error occurred while loading keys.", e);
         }
     }
@@ -75,4 +79,38 @@ public final class Crypto {
         secureRandom.nextBytes(bytes);
         return bytes;
     }
+
+    public static QueryCurRegionRspJson encryptAndSignRegionData(byte[] regionInfo, String key_id) throws Exception {
+        if (key_id == null) {
+            throw new Exception("Key ID was not set");
+        }
+
+        Cipher cipher = Cipher.getInstance("RSA/ECB/PKCS1Padding");
+        cipher.init(Cipher.ENCRYPT_MODE, EncryptionKeys.get(Integer.valueOf(key_id)));
+
+        //Encrypt regionInfo in chunks
+        ByteArrayOutputStream encryptedRegionInfoStream = new ByteArrayOutputStream();
+
+        //Thank you so much GH Copilot
+        int chunkSize = 256 - 11;
+        int regionInfoLength = regionInfo.length;
+        int numChunks = (int) Math.ceil(regionInfoLength / (double) chunkSize);
+
+        for (int i = 0; i < numChunks; i++) {
+            byte[] chunk = Arrays.copyOfRange(regionInfo, i * chunkSize,
+                Math.min((i + 1) * chunkSize, regionInfoLength));
+            byte[] encryptedChunk = cipher.doFinal(chunk);
+            encryptedRegionInfoStream.write(encryptedChunk);
+        }
+
+        Signature privateSignature = Signature.getInstance("SHA256withRSA");
+        privateSignature.initSign(CUR_SIGNING_KEY);
+        privateSignature.update(regionInfo);
+
+        var rsp = new QueryCurRegionRspJson();
+
+        rsp.content = Utils.base64Encode(encryptedRegionInfoStream.toByteArray());
+        rsp.sign = Utils.base64Encode(privateSignature.sign());
+        return rsp;
+    }
 }