Return empty lists instead of null in GetCallingRelaysV2

service/src/main/java/org/whispersystems/textsecuregcm/auth/CloudflareTurnCredentialsManager.java

@@ -16,6 +16,7 @@ import java.net.URI;
 import java.net.http.HttpRequest;
 import java.net.http.HttpResponse;
 import java.util.List;
+import java.util.Optional;
 import java.util.concurrent.CompletionException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.ScheduledExecutorService;
@@ -126,8 +127,12 @@ public class CloudflareTurnCredentialsManager {
     final CloudflareTurnResponse cloudflareTurnResponse = SystemMapper.jsonMapper()
         .readValue(response.body(), CloudflareTurnResponse.class);
 
-    return new TurnToken(cloudflareTurnResponse.iceServers().username(),
+    return TurnTokenGenerator.from(
+        cloudflareTurnResponse.iceServers().username(),
         cloudflareTurnResponse.iceServers().credential(),
-        cloudflareTurnUrls, cloudflareTurnComposedUrls, cloudflareTurnHostname);
+        Optional.ofNullable(cloudflareTurnUrls),
+        Optional.ofNullable(cloudflareTurnComposedUrls),
+        cloudflareTurnHostname
+    );
   }
 }

service/src/main/java/org/whispersystems/textsecuregcm/auth/TurnToken.java

@@ -5,9 +5,14 @@
 
 package org.whispersystems.textsecuregcm.auth;
 
+import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.List;
 
-public record TurnToken(String username, String password, List<String> urls, @Nullable List<String> urlsWithIps,
-                        @Nullable String hostname) {
+public record TurnToken(
+    String username,
+    String password,
+    @Nonnull List<String> urls,
+    @Nonnull List<String> urlsWithIps,
+    @Nullable String hostname) {
 }

service/src/main/java/org/whispersystems/textsecuregcm/auth/TurnTokenGenerator.java

@@ -11,19 +11,13 @@ import java.security.SecureRandom;
 import java.time.Duration;
 import java.time.Instant;
 import java.util.Base64;
+import java.util.Collections;
 import java.util.List;
 import java.util.Optional;
-import java.util.UUID;
 import javax.crypto.Mac;
 import javax.crypto.spec.SecretKeySpec;
 import org.whispersystems.textsecuregcm.calls.routing.TurnServerOptions;
-import org.whispersystems.textsecuregcm.configuration.TurnUriConfiguration;
-import org.whispersystems.textsecuregcm.configuration.dynamic.DynamicConfiguration;
-import org.whispersystems.textsecuregcm.configuration.dynamic.DynamicTurnConfiguration;
-import org.whispersystems.textsecuregcm.storage.DynamicConfigurationManager;
-import org.whispersystems.textsecuregcm.util.Pair;
 import org.whispersystems.textsecuregcm.util.Util;
-import org.whispersystems.textsecuregcm.util.WeightedRandomSelect;
 
 public class TurnTokenGenerator {
 
@@ -43,23 +37,51 @@ public class TurnTokenGenerator {
     return generateToken(options.hostname(), options.urlsWithIps(), options.urlsWithHostname());
   }
 
-  private TurnToken generateToken(String hostname, List<String> urlsWithIps, List<String> urlsWithHostname) {
+  @SuppressWarnings("OptionalUsedAsFieldOrParameterType")
+  private TurnToken generateToken(
+      String hostname,
+      Optional<List<String>> urlsWithIps,
+      Optional<List<String>> urlsWithHostname
+  ) {
     try {
       final Mac mac = Mac.getInstance(ALGORITHM);
       final long validUntilSeconds = Instant.now().plus(Duration.ofDays(1)).getEpochSecond();
       final long user = Util.ensureNonNegativeInt(new SecureRandom().nextInt());
       final String userTime = validUntilSeconds + ":" + user;
-      final String protocol = urlsWithIps != null && !urlsWithIps.isEmpty()
-          ? WithIpsProtocol
-          : WithUrlsProtocol;
+      final String protocol = urlsWithIps.isEmpty() || urlsWithIps.get().isEmpty()
+          ? WithUrlsProtocol
+          : WithIpsProtocol;
       final String protocolUserTime = userTime + "#" + protocol;
 
       mac.init(new SecretKeySpec(turnSecret, ALGORITHM));
       final String password = Base64.getEncoder().encodeToString(mac.doFinal(protocolUserTime.getBytes()));
 
-      return new TurnToken(protocolUserTime, password, urlsWithHostname, urlsWithIps, hostname);
+      return from(
+          protocolUserTime,
+          password,
+          urlsWithHostname,
+          urlsWithIps,
+          hostname
+      );
     } catch (final NoSuchAlgorithmException | InvalidKeyException e) {
       throw new AssertionError(e);
     }
   }
+
+  @SuppressWarnings("OptionalUsedAsFieldOrParameterType")
+  public static TurnToken from(
+      String username,
+      String password,
+      Optional<List<String>> urls,
+      Optional<List<String>> urlsWithIps,
+      String hostname
+  ) {
+    return new TurnToken(
+        username,
+        password,
+        urls.orElse(Collections.emptyList()),
+        urlsWithIps.orElse(Collections.emptyList()),
+        hostname
+    );
+  }
 }

service/src/main/java/org/whispersystems/textsecuregcm/calls/routing/TurnCallRouter.java

@@ -77,7 +77,7 @@ public class TurnCallRouter {
       return getRoutingForInner(aci, clientAddress, instanceLimit);
     } catch(Exception e) {
       logger.error("Failed to perform routing", e);
-      return new TurnServerOptions(this.configTurnRouter.getHostname(), null, this.configTurnRouter.randomUrls());
+      return new TurnServerOptions(this.configTurnRouter.getHostname(), null, Optional.of(this.configTurnRouter.randomUrls()));
     }
   }
 
@@ -90,11 +90,11 @@ public class TurnCallRouter {
 
     List<String> targetedUrls = this.configTurnRouter.targetedUrls(aci);
     if(!targetedUrls.isEmpty()) {
-      return new TurnServerOptions(hostname, null, targetedUrls);
+      return new TurnServerOptions(hostname, Optional.empty(), Optional.ofNullable(targetedUrls));
     }
 
     if(clientAddress.isEmpty() || this.configTurnRouter.shouldRandomize() || instanceLimit < 1) {
-      return new TurnServerOptions(hostname, null, this.configTurnRouter.randomUrls());
+      return new TurnServerOptions(hostname, Optional.empty(), Optional.ofNullable(this.configTurnRouter.randomUrls()));
     }
 
     CityResponse geoInfo;
@@ -128,7 +128,7 @@ public class TurnCallRouter {
             datacenters,
             instanceLimit
         ));
-    return new TurnServerOptions(hostname, urlsWithIps, minimalRandomUrls());
+    return new TurnServerOptions(hostname, Optional.of(urlsWithIps), Optional.of(minimalRandomUrls()));
   }
 
   // Includes only the udp options in the randomUrls

service/src/main/java/org/whispersystems/textsecuregcm/calls/routing/TurnServerOptions.java

@@ -6,6 +6,11 @@
 package org.whispersystems.textsecuregcm.calls.routing;
 
 import java.util.List;
+import java.util.Optional;
 
-public record TurnServerOptions(String hostname, List<String> urlsWithIps, List<String> urlsWithHostname) {
+public record TurnServerOptions(
+    String hostname,
+    Optional<List<String>> urlsWithIps,
+    Optional<List<String>> urlsWithHostname
+) {
 }