fix: add null checks for getCause() usages in exception handling

Author: emmileaf

jib-core/src/main/java/com/google/cloud/tools/jib/api/RegistryUnauthorizedException.java

@@ -18,6 +18,7 @@
 
 import com.google.api.client.http.HttpResponseException;
 import com.google.cloud.tools.jib.http.ResponseException;
+import javax.annotation.Nullable;
 
 /** Thrown when a registry request was unauthorized and therefore authentication is needed. */
 public class RegistryUnauthorizedException extends RegistryException {
@@ -43,7 +44,12 @@ public String getImageReference() {
     return registry + "/" + repository;
   }
 
+  @Nullable
   public HttpResponseException getHttpResponseException() {
-    return (HttpResponseException) getCause().getCause();
+    if (getCause() != null && getCause().getCause() != null) {
+      return (HttpResponseException) getCause().getCause();
+    } else {
+      return null;
+    }
   }
 }

jib-core/src/main/java/com/google/cloud/tools/jib/builder/steps/PullBaseImageStep.java

@@ -172,7 +172,10 @@ public ImagesAndRegistryClient call()
                 .setCredential(credential)
                 .newRegistryClient();
 
-        String wwwAuthenticate = ex.getHttpResponseException().getHeaders().getAuthenticate();
+        String wwwAuthenticate =
+            ex.getHttpResponseException() != null
+                ? ex.getHttpResponseException().getHeaders().getAuthenticate()
+                : null;
         if (wwwAuthenticate != null) {
           eventHandlers.dispatch(
               LogEvent.debug("WWW-Authenticate for " + imageReference + ": " + wwwAuthenticate));

jib-core/src/main/java/com/google/cloud/tools/jib/registry/RegistryClient.java

@@ -623,16 +623,20 @@ private <T> T callRegistryEndpoint(RegistryEndpointProvider<T> registryEndpointP
             .call();
 
       } catch (RegistryUnauthorizedException ex) {
-        if (ex.getHttpResponseException().getStatusCode()
-                != HttpStatusCodes.STATUS_CODE_UNAUTHORIZED
+        if ((ex.getHttpResponseException() != null
+                && ex.getHttpResponseException().getStatusCode()
+                    != HttpStatusCodes.STATUS_CODE_UNAUTHORIZED)
             || !isBearerAuth(authorization.get())
             || ++bearerTokenRefreshes >= MAX_BEARER_TOKEN_REFRESH_TRIES) {
           throw ex;
         }
 
         // Because we successfully did bearer authentication initially, getting 401 here probably
         // means the token was expired.
-        String wwwAuthenticate = ex.getHttpResponseException().getHeaders().getAuthenticate();
+        String wwwAuthenticate =
+            ex.getHttpResponseException() != null
+                ? ex.getHttpResponseException().getHeaders().getAuthenticate()
+                : null;
         authorization.set(refreshBearerAuth(wwwAuthenticate));
       }
     }

jib-plugins-common/src/main/java/com/google/cloud/tools/jib/plugins/common/JibBuildRunner.java

@@ -170,8 +170,9 @@ private static void handleRegistryUnauthorizedException(
       RegistryUnauthorizedException registryUnauthorizedException,
       HelpfulSuggestions helpfulSuggestions)
       throws BuildStepsExecutionException {
-    if (registryUnauthorizedException.getHttpResponseException().getStatusCode()
-        == HttpStatusCodes.STATUS_CODE_FORBIDDEN) {
+    if (registryUnauthorizedException.getHttpResponseException() != null
+        && registryUnauthorizedException.getHttpResponseException().getStatusCode()
+            == HttpStatusCodes.STATUS_CODE_FORBIDDEN) {
       // No permissions for registry/repository.
       throw new BuildStepsExecutionException(
           helpfulSuggestions.forHttpStatusCodeForbidden(
@@ -280,10 +281,14 @@ public JibContainer runBuild()
       throw new BuildStepsExecutionException(message, ex);
 
     } catch (ExecutionException ex) {
-      String message = ex.getCause().getMessage();
-      throw new BuildStepsExecutionException(
-          message == null ? "(null exception message)" : message, ex.getCause());
-
+      if (ex.getCause() != null) {
+        String message =ex.getCause().getMessage();
+        throw new BuildStepsExecutionException(
+                message == null ? "(null exception message)" : message, ex.getCause());
+      } else {
+        // Unknown cause
+        throw new BuildStepsExecutionException(helpfulSuggestions.none(), ex);
+      }
     } catch (InterruptedException ex) {
       Thread.currentThread().interrupt();
       throw new BuildStepsExecutionException(helpfulSuggestions.none(), ex);