Introduce an ASN-to-IP manager.

service/src/main/java/org/whispersystems/textsecuregcm/util/AsnManager.java

@@ -0,0 +1,98 @@
+/*
+ * Copyright 2013-2021 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.util;
+
+import static com.codahale.metrics.MetricRegistry.name;
+
+import com.amazonaws.services.s3.model.S3Object;
+import com.google.common.annotations.VisibleForTesting;
+import io.dropwizard.lifecycle.Managed;
+import io.micrometer.core.instrument.Counter;
+import io.micrometer.core.instrument.Metrics;
+import io.micrometer.core.instrument.Timer;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.net.Inet4Address;
+import java.net.UnknownHostException;
+import java.util.Optional;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.zip.GZIPInputStream;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.whispersystems.textsecuregcm.configuration.MonitoredS3ObjectConfiguration;
+
+public class AsnManager implements Managed {
+
+  private final S3ObjectMonitor asnTableMonitor;
+
+  private final AtomicReference<AsnTable> asnTable = new AtomicReference<>(AsnTable.EMPTY);
+
+  private static final Timer REFRESH_TIMER = Metrics.timer(name(AsnManager.class, "refresh"));
+  private static final Counter REFRESH_ERRORS = Metrics.counter(name(AsnManager.class, "refreshErrors"));
+
+  private static final Logger log = LoggerFactory.getLogger(AsnManager.class);
+
+  public AsnManager(
+      final ScheduledExecutorService scheduledExecutorService,
+      final MonitoredS3ObjectConfiguration configuration) {
+
+    this.asnTableMonitor = new S3ObjectMonitor(
+        configuration.getS3Region(),
+        configuration.getS3Bucket(),
+        configuration.getObjectKey(),
+        configuration.getMaxSize(),
+        scheduledExecutorService,
+        configuration.getRefreshInterval(),
+        this::handleAsnTableChanged);
+  }
+
+  @Override
+  public void start() throws Exception {
+    try {
+      handleAsnTableChanged(asnTableMonitor.getObject());
+    } catch (final Exception e) {
+      log.warn("Failed to load initial IP-to-ASN map", e);
+    }
+
+    asnTableMonitor.start();
+  }
+
+  @Override
+  public void stop() throws Exception {
+    asnTableMonitor.stop();
+  }
+
+  public Optional<Long> getAsn(final String address) {
+    try {
+      return asnTable.get().getAsn((Inet4Address) Inet4Address.getByName(address));
+    } catch (final UnknownHostException e) {
+      log.warn("Could not parse \"{}\" as an Inet4Address", address);
+      return Optional.empty();
+    }
+  }
+
+  private void handleAsnTableChanged(final S3Object asnTableObject) {
+    REFRESH_TIMER.record(() -> {
+      try {
+        handleAsnTableChanged(new GZIPInputStream(asnTableObject.getObjectContent()));
+      } catch (final IOException e) {
+        log.error("Retrieved object was not a gzip archive", e);
+      }
+    });
+  }
+
+  @VisibleForTesting
+  void handleAsnTableChanged(final InputStream inputStream) {
+    try (final InputStreamReader reader = new InputStreamReader(inputStream)) {
+      asnTable.set(new AsnTable(reader));
+    } catch (final Exception e) {
+      REFRESH_ERRORS.increment();
+      log.warn("Failed to refresh IP-to-ASN table", e);
+    }
+  }
+}

service/src/main/java/org/whispersystems/textsecuregcm/util/AsnTable.java

@@ -44,6 +44,8 @@ class AsnTable {
     }
   }
 
+  public static final AsnTable EMPTY = new AsnTable();
+
   public AsnTable(final Reader tsvReader) throws IOException {
     final TreeMap<Long, AsnRange> treeMap = new TreeMap<>();
 
@@ -60,6 +62,10 @@ class AsnTable {
     asnBlocksByFirstIp = treeMap;
   }
 
+  private AsnTable() {
+    asnBlocksByFirstIp = new TreeMap<>();
+  }
+
   public Optional<Long> getAsn(final Inet4Address address) {
     final long addressAsLong = ipToLong(address);
 

service/src/main/java/org/whispersystems/textsecuregcm/util/TorExitNodeManager.java

@@ -24,7 +24,7 @@ import java.util.concurrent.atomic.AtomicReference;
 import java.util.stream.Collectors;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
-import org.whispersystems.textsecuregcm.configuration.TorExitNodeConfiguration;
+import org.whispersystems.textsecuregcm.configuration.MonitoredS3ObjectConfiguration;
 
 /**
  * A utility for checking whether IP addresses belong to Tor exit nodes using the "bulk exit list."
@@ -44,7 +44,7 @@ public class TorExitNodeManager implements Managed {
 
   public TorExitNodeManager(
       final ScheduledExecutorService scheduledExecutorService,
-      final TorExitNodeConfiguration configuration) {
+      final MonitoredS3ObjectConfiguration configuration) {
 
     this.exitListMonitor = new S3ObjectMonitor(
         configuration.getS3Region(),