Save last-known server time offset.

app/src/main/java/org/thoughtcrime/securesms/jobs/RemoteConfigRefreshJob.java

@@ -5,14 +5,13 @@ import androidx.annotation.Nullable;
 
 import org.signal.core.util.logging.Log;
 import org.thoughtcrime.securesms.dependencies.ApplicationDependencies;
-import org.thoughtcrime.securesms.jobmanager.JsonJobData;
 import org.thoughtcrime.securesms.jobmanager.Job;
 import org.thoughtcrime.securesms.jobmanager.impl.NetworkConstraint;
 import org.thoughtcrime.securesms.keyvalue.SignalStore;
 import org.thoughtcrime.securesms.util.FeatureFlags;
+import org.whispersystems.signalservice.api.RemoteConfigResult;
 import org.whispersystems.signalservice.api.push.exceptions.PushNetworkException;
 
-import java.util.Map;
 import java.util.concurrent.TimeUnit;
 
 public class RemoteConfigRefreshJob extends BaseJob {
@@ -52,8 +51,9 @@ public class RemoteConfigRefreshJob extends BaseJob {
       return;
     }
 
-    Map<String, Object> config = ApplicationDependencies.getSignalServiceAccountManager().getRemoteConfig();
+    RemoteConfigResult result = ApplicationDependencies.getSignalServiceAccountManager().getRemoteConfig();
-    FeatureFlags.update(config);
+    FeatureFlags.update(result.getConfig());
+    SignalStore.misc().setLastKnownServerTime(TimeUnit.SECONDS.toMillis(result.getServerEpochTimeSeconds()), System.currentTimeMillis());
   }
 
   @Override

app/src/main/java/org/thoughtcrime/securesms/keyvalue/MiscellaneousValues.java

@@ -39,6 +39,8 @@ public final class MiscellaneousValues extends SignalStoreValues {
   private static final String KEYBOARD_LANDSCAPE_HEIGHT      = "misc.keyboard.landscape_height";
   private static final String KEYBOARD_PORTRAIT_HEIGHT       = "misc.keyboard.protrait_height";
   private static final String LAST_CONSISTENCY_CHECK_TIME    = "misc.last_consistency_check_time";
+  private static final String SERVER_TIME_OFFSET             = "misc.server_time_offset";
+  private static final String LAST_SERVER_TIME_OFFSET_UPDATE = "misc.last_server_time_offset_update";
 
   MiscellaneousValues(@NonNull KeyValueStore store) {
     super(store);
@@ -326,4 +328,31 @@ public final class MiscellaneousValues extends SignalStoreValues {
   public void setLastConsistencyCheckTime(long time) {
     putLong(LAST_CONSISTENCY_CHECK_TIME, time);
   }
+
+  /**
+   * Sets the last-known server time.
+   */
+  public void setLastKnownServerTime(long serverTime, long currentTime) {
+    getStore()
+        .beginWrite()
+        .putLong(SERVER_TIME_OFFSET, currentTime - serverTime)
+        .putLong(LAST_SERVER_TIME_OFFSET_UPDATE, System.currentTimeMillis())
+        .apply();
+  }
+
+  /**
+   * The last-known offset between our local clock and the server. To get an estimate of the server time, take your current time and subtract this offset. e.g.
+   *
+   * estimatedServerTime = System.currentTimeMillis() - SignalStore.misc().getLastKnownServerTimeOffset()
+   */
+  public long getLastKnownServerTimeOffset() {
+    return getLong(SERVER_TIME_OFFSET, 0);
+  }
+
+  /**
+   * The last time (using our local clock) we updated the server time offset returned by {@link #getLastKnownServerTimeOffset()}}.
+   */
+  public long getLastKnownServerTimeOffsetUpdateTime() {
+    return getLong(LAST_SERVER_TIME_OFFSET_UPDATE, 0);
+  }
 }

app/src/main/java/org/thoughtcrime/securesms/logsubmit/LogSectionSystemInfo.java

@@ -85,6 +85,7 @@ public class LogSectionSystemInfo implements LogSection {
     builder.append("Emoji Version     : ").append(getEmojiVersionString(context)).append("\n");
     builder.append("RenderBigEmoji    : ").append(FontUtil.canRenderEmojiAtFontSize(1024)).append("\n");
     builder.append("DontKeepActivities: ").append(getDontKeepActivities(context)).append("\n");
+    builder.append("Server Time Offset: ").append(SignalStore.misc().getLastKnownServerTimeOffset()).append(" ms (last updated: ").append(SignalStore.misc().getLastKnownServerTimeOffsetUpdateTime()).append(")").append("\n");
     builder.append("Telecom           : ").append(AndroidTelecomUtil.getTelecomSupported()).append("\n");
     builder.append("User-Agent        : ").append(StandardUserAgentInterceptor.USER_AGENT).append("\n");
     builder.append("App               : ");

app/src/main/java/org/thoughtcrime/securesms/util/FeatureFlags.java

@@ -18,6 +18,7 @@ import org.thoughtcrime.securesms.groups.SelectionLimits;
 import org.thoughtcrime.securesms.jobs.RemoteConfigRefreshJob;
 import org.thoughtcrime.securesms.keyvalue.SignalStore;
 import org.thoughtcrime.securesms.messageprocessingalarm.MessageProcessReceiver;
+import org.whispersystems.signalservice.api.RemoteConfigResult;
 
 import java.io.IOException;
 import java.util.HashMap;
@@ -293,8 +294,8 @@ public final class FeatureFlags {
 
   @WorkerThread
   public static void refreshSync() throws IOException {
-    Map<String, Object> config = ApplicationDependencies.getSignalServiceAccountManager().getRemoteConfig();
+    RemoteConfigResult result = ApplicationDependencies.getSignalServiceAccountManager().getRemoteConfig();
-    FeatureFlags.update(config);
+    FeatureFlags.update(result.getConfig());
   }
 
   public static synchronized void update(@NonNull Map<String, Object> config) {

libsignal/service/src/main/java/org/whispersystems/signalservice/api/RemoteConfigResult.kt

@@ -0,0 +1,11 @@
+/*
+ * Copyright 2023 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.signalservice.api
+
+data class RemoteConfigResult(
+  val config: Map<String, Any>,
+  val serverEpochTimeSeconds: Long
+)

libsignal/service/src/main/java/org/whispersystems/signalservice/api/SignalServiceAccountManager.java

@@ -626,7 +626,7 @@ public class SignalServiceAccountManager {
     }
   }
 
-  public Map<String, Object> getRemoteConfig() throws IOException {
+  public RemoteConfigResult getRemoteConfig() throws IOException {
     RemoteConfigResponse response = this.pushServiceSocket.getRemoteConfig();
     Map<String, Object>  out      = new HashMap<>();
 
@@ -634,7 +634,7 @@ public class SignalServiceAccountManager {
       out.put(config.getName(), config.getValue() != null ? config.getValue() : config.isEnabled());
     }
 
-    return out;
+    return new RemoteConfigResult(out, response.getServerEpochTime());
   }
 
   public String getAccountDataReport() throws IOException {

libsignal/service/src/main/java/org/whispersystems/signalservice/internal/push/RemoteConfigResponse.java

@@ -8,10 +8,17 @@ public class RemoteConfigResponse {
   @JsonProperty
   private List<Config> config;
 
+  @JsonProperty
+  private long serverEpochTime;
+
   public List<Config> getConfig() {
     return config;
   }
 
+  public long getServerEpochTime() {
+    return serverEpochTime;
+  }
+
   public static class Config {
     @JsonProperty
     private String name;