Port /v1/archives/backupid/limits to gRPC

service/src/main/java/org/whispersystems/textsecuregcm/grpc/BackupsGrpcService.java

@@ -16,6 +16,7 @@ import java.util.Optional;
 import java.util.stream.Collectors;
 import org.signal.chat.backup.GetBackupAuthCredentialsRequest;
 import org.signal.chat.backup.GetBackupAuthCredentialsResponse;
+import org.signal.chat.backup.GetBackupIdLimitsResponse;
 import org.signal.chat.backup.RedeemReceiptRequest;
 import org.signal.chat.backup.RedeemReceiptResponse;
 import org.signal.chat.backup.SetBackupIdRequest;
@@ -138,6 +139,16 @@ public class BackupsGrpcService extends SimpleBackupsGrpc.BackupsImplBase {
     }
   }
 
+  @Override
+  public GetBackupIdLimitsResponse getBackupIdLimits(final Empty request) {
+    final Account account = authenticatedAccount();
+    final BackupAuthManager.BackupIdRotationLimit limit = backupAuthManager.checkBackupIdRotationLimit(account);
+    return GetBackupIdLimitsResponse.newBuilder()
+        .setHasPermitsRemaining(limit.hasPermitsRemaining())
+        .setRetryAfterSeconds(limit.nextPermitAvailable().getSeconds())
+        .build();
+  }
+
   @Override
   public Throwable mapException(final Throwable throwable) {
     return switch (throwable) {

service/src/main/proto/org/signal/chat/backups.proto

@@ -59,6 +59,9 @@ service Backups {
   // Clients must validate the receipt level on the credential matches a known
   // receipt level before using it.
   rpc GetBackupAuthCredentials(GetBackupAuthCredentialsRequest) returns (GetBackupAuthCredentialsResponse) {}
+
+  // Retrieve backup ID rotation limits
+  rpc GetBackupIdLimits(google.protobuf.Empty) returns (GetBackupIdLimitsResponse) {}
 }
 
 message SetBackupIdRequest {
@@ -125,6 +128,13 @@ message GetBackupAuthCredentialsResponse {
   Credentials credentials = 1;
 }
 
+message GetBackupIdLimitsResponse {
+  // If true, a call to SetBackupId may succeed without waiting
+  bool hasPermitsRemaining = 1;
+  // How long to wait before a permit becomes available, in seconds
+  uint64 retryAfterSeconds = 2;
+}
+
 // Service for backup operations with anonymous credentials
 //
 // This service never requires account authentication. It instead requires a

service/src/test/java/org/whispersystems/textsecuregcm/grpc/BackupsGrpcServiceTest.java

@@ -14,6 +14,7 @@ import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
 
 import com.google.protobuf.ByteString;
+import com.google.protobuf.Empty;
 import io.grpc.Status;
 import java.time.Clock;
 import java.time.Duration;
@@ -35,6 +36,7 @@ import org.mockito.Mock;
 import org.signal.chat.backup.BackupsGrpc;
 import org.signal.chat.backup.GetBackupAuthCredentialsRequest;
 import org.signal.chat.backup.GetBackupAuthCredentialsResponse;
+import org.signal.chat.backup.GetBackupIdLimitsResponse;
 import org.signal.chat.backup.RedeemReceiptRequest;
 import org.signal.chat.backup.RedeemReceiptResponse;
 import org.signal.chat.backup.SetBackupIdRequest;
@@ -263,4 +265,22 @@ class BackupsGrpcServiceTest extends SimpleBaseGrpcTest<BackupsGrpcService, Back
         () -> authenticatedServiceStub().getBackupAuthCredentials(builder.build()));
   }
 
+  @ParameterizedTest
+  @CsvSource({
+      "true, 0",
+      "false, 3600"
+  })
+  void getBackupIdLimits(final boolean hasPermitsRemaining, final long retryAfterSeconds) {
+    when(backupAuthManager.checkBackupIdRotationLimit(account))
+        .thenReturn(new BackupAuthManager.BackupIdRotationLimit(
+            hasPermitsRemaining, Duration.ofSeconds(retryAfterSeconds)));
+
+    final GetBackupIdLimitsResponse response =
+        authenticatedServiceStub().getBackupIdLimits(Empty.getDefaultInstance());
+
+    assertThat(response.getHasPermitsRemaining()).isEqualTo(hasPermitsRemaining);
+    assertThat(response.getRetryAfterSeconds()).isEqualTo(retryAfterSeconds);
+    verify(backupAuthManager).checkBackupIdRotationLimit(account);
+  }
+
 }