Add a simple utility class for testing if an IP belongs to a Tor exit node.

service/src/main/java/org/whispersystems/textsecuregcm/configuration/TorExitNodeConfiguration.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2021 Signal Messenger, LLC
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+package org.whispersystems.textsecuregcm.configuration;
+
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.google.common.annotations.VisibleForTesting;
+import javax.validation.Valid;
+import javax.validation.constraints.NotBlank;
+import java.time.Duration;
+
+public class TorExitNodeConfiguration {
+
+  @JsonProperty
+  @NotBlank
+  private String listUrl;
+
+  @JsonProperty
+  private Duration refreshInterval = Duration.ofMinutes(5);
+
+  @JsonProperty
+  @Valid
+  private CircuitBreakerConfiguration circuitBreakerConfiguration = new CircuitBreakerConfiguration();
+
+  @JsonProperty
+  @Valid
+  private RetryConfiguration retryConfiguration = new RetryConfiguration();
+
+  public String getListUrl() {
+    return listUrl;
+  }
+
+  @VisibleForTesting
+  public void setListUrl(final String listUrl) {
+    this.listUrl = listUrl;
+  }
+
+  public Duration getRefreshInterval() {
+    return refreshInterval;
+  }
+
+  public CircuitBreakerConfiguration getCircuitBreakerConfiguration() {
+    return circuitBreakerConfiguration;
+  }
+
+  public RetryConfiguration getRetryConfiguration() {
+    return retryConfiguration;
+  }
+}