Warn if we were unable to check if the system clock is accurate

common/src/main/java/org/geysermc/floodgate/time/TimeSyncer.java

@@ -37,7 +37,7 @@ public final class TimeSyncer {
     public TimeSyncer(String timeServer) {
         ScheduledExecutorService service = Executors.newScheduledThreadPool(1);
         service.scheduleWithFixedDelay(() -> {
-            // 5 tries to get the time offset
+            // 5 tries to get the time offset, since UDP doesn't guaranty a response
             for (int i = 0; i < 5; i++) {
                 long offset = SntpClientUtils.requestTimeOffset(timeServer, 3000);
                 if (offset != Long.MIN_VALUE) {
@@ -56,4 +56,15 @@ public final class TimeSyncer {
     public long getTimeOffset() {
         return timeOffset;
     }
+
+    public long getRealMillis() {
+        if (hasUsefulOffset()) {
+            return System.currentTimeMillis() + getTimeOffset();
+        }
+        return System.currentTimeMillis();
+    }
+
+    public boolean hasUsefulOffset() {
+        return timeOffset != Long.MIN_VALUE;
+    }
 }

common/src/main/java/org/geysermc/floodgate/util/BedrockData.java

@@ -62,15 +62,9 @@ public final class BedrockData implements Cloneable {
             String languageCode, int uiProfile, int inputMode, String ip,
             LinkedPlayer linkedPlayer, boolean fromProxy, int subscribeId,
             String verifyCode, TimeSyncer timeSyncer) {
-
-        long realMillis = System.currentTimeMillis();
-        if (timeSyncer.getTimeOffset() != Long.MIN_VALUE) {
-            realMillis += timeSyncer.getTimeOffset();
-        }
-
         return new BedrockData(version, username, xuid, deviceOs, languageCode, inputMode,
                 uiProfile, ip, linkedPlayer, fromProxy, subscribeId, verifyCode,
-                realMillis, EXPECTED_LENGTH);
+                timeSyncer.getRealMillis(), EXPECTED_LENGTH);
     }
 
     public static BedrockData of(

connector/src/main/java/org/geysermc/connector/network/session/GeyserSession.java

@@ -695,6 +695,14 @@ public class GeyserSession implements CommandSender {
                                     skinUploader.getVerifyCode(),
                                     connector.getTimeSyncer()
                             ).toString());
+
+                            if (!connector.getTimeSyncer().hasUsefulOffset()) {
+                                connector.getLogger().warning(
+                                        "We couldn't make sure that your system clock is accurate. " +
+                                        "This can cause issues with logging in."
+                                );
+                            }
+
                         } catch (Exception e) {
                             connector.getLogger().error(LanguageUtils.getLocaleStringLog("geyser.auth.floodgate.encrypt_fail"), e);
                             disconnect(LanguageUtils.getPlayerLocaleString("geyser.auth.floodgate.encryption_fail", getClientData().getLanguageCode()));