Classify Infobip's SIGNALS_BLOCKED response as "rejected as fraud"

src/main/java/org/signal/registration/sender/infobip/InfobipExceptions.java

@@ -8,6 +8,7 @@
 import com.infobip.ApiException;
 import com.infobip.model.MessageStatus;
 import io.micronaut.http.HttpStatus;
+import org.signal.registration.sender.SenderFraudBlockException;
 import org.signal.registration.sender.SenderRejectedRequestException;
 import org.signal.registration.util.CompletionExceptions;
 import javax.annotation.Nullable;
@@ -21,6 +22,7 @@ public class InfobipExceptions {
       HttpStatus.UNAUTHORIZED
   );
 
+  // See https://www.infobip.com/docs/essentials/response-status-and-error-codes
   private static final Set<Integer> REJECTED_GROUP_IDS = Set.of(
       2, // Message not delivered
       4, // Expired
@@ -67,6 +69,14 @@ public static Exception toSenderException(final ApiException exception) {
     return null;
   }
 
+  public static void maybeThrowSenderFraudBlockException(final MessageStatus status) throws SenderFraudBlockException {
+    // Group 4 is "EXPIRED" and ID 87 is "SIGNALS_BLOCKED", which is defined as "Message has been rejected due to an
+    // anti-fraud mechanism"
+    if (status.getGroupId() == 4 && status.getId() == 87) {
+      throw new SenderFraudBlockException("Message has been rejected due to an anti-fraud mechanism");
+    }
+  }
+
   public static void maybeThrowInfobipRejectedRequestException(final MessageStatus status) throws InfobipRejectedRequestException {
     if (REJECTED_GROUP_IDS.contains(status.getGroupId())) {
       throw new InfobipRejectedRequestException(status);

src/main/java/org/signal/registration/sender/infobip/classic/InfobipSmsSender.java

@@ -164,8 +164,9 @@ private static String checkSenderRejectedAndExtractMessageId(@Nullable final Lis
         .findFirst()
         .orElseThrow(() -> new SenderRejectedRequestException("No SMS response with a message ID"));
 
-    // Infobip enabled our account to return a 200 response with groupId 5 ("rejected") in the response body
-    // for a create SMS request, so we check for that and convert it into an exception.
+    // Infobip enabled our account to return a 200 response with groupId 4 ("expired") or 5 ("rejected") in the response
+    // body for a create SMS request, so we check for that and convert it into an exception.
+    InfobipExceptions.maybeThrowSenderFraudBlockException(finalResponseDetail.getStatus());
     InfobipExceptions.maybeThrowInfobipRejectedRequestException(finalResponseDetail.getStatus());
     return finalResponseDetail.getMessageId();
   }

src/test/java/org/signal/registration/sender/infobip/classic/InfobipSmsSenderTest.java

@@ -1,6 +1,7 @@
 package org.signal.registration.sender.infobip.classic;
 
 import static org.junit.Assert.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertInstanceOf;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
@@ -17,11 +18,13 @@
 import java.util.List;
 import java.util.Locale;
 import java.util.concurrent.CompletionException;
+import org.apache.commons.lang3.RandomStringUtils;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.signal.registration.sender.ApiClientInstrumenter;
 import org.signal.registration.sender.ClientType;
 import org.signal.registration.sender.MessageTransport;
+import org.signal.registration.sender.SenderFraudBlockException;
 import org.signal.registration.sender.VerificationCodeGenerator;
 import org.signal.registration.sender.VerificationSmsBodyProvider;
 import org.signal.registration.sender.infobip.InfobipSenderConfiguration;
@@ -81,4 +84,29 @@ void sendAndVerify() throws ApiException {
 
     assertTrue(sender.checkVerificationCode("123456", senderData).join());
   }
+
+  @Test
+  void sendRejectedSignalsBlocked() throws ApiException {
+    final SmsApi.SendSmsMessageRequest messageRequest = mock(SmsApi.SendSmsMessageRequest.class);
+    final SmsResponse response = mock(SmsResponse.class);
+    final SmsResponseDetails details = mock(SmsResponseDetails.class);
+    final MessageStatus status = mock(MessageStatus.class);
+
+    when(codeGenerator.generateVerificationCode()).thenReturn("123456");
+    when(client.sendSmsMessage(any())).thenReturn(messageRequest);
+    when(messageRequest.execute()).thenReturn(response);
+    when(response.getMessages()).thenReturn(List.of(details));
+    when(details.getStatus()).thenReturn(status);
+    when(details.getMessageId()).thenReturn(RandomStringUtils.randomNumeric(22));
+    when(status.getGroupId()).thenReturn(4);
+    when(status.getId()).thenReturn(87);
+
+    final CompletionException completionException = assertThrows(CompletionException.class,
+        () -> sender.sendVerificationCode(MessageTransport.SMS,
+            PhoneNumberUtil.getInstance().getExampleNumber("US"),
+            Locale.LanguageRange.parse("en"), ClientType.UNKNOWN)
+        .join());
+
+    assertInstanceOf(SenderFraudBlockException.class, completionException.getCause());
+  }
 }