Core: Remove potential NPE while resolving concrete indices from MetaData

Prevents a current edge case resolving concrete aliases or index names in cluster MetaData
that could potentialy lead to NullPointerException when the IndicesOptions don't allow
wildcard expansion and the method is called with aliasesOrIndices argument null or emtpy list.
This change adds a check for that and introduces randomized test that catches this.

Closes #10342
Closes #10339

src/main/java/org/elasticsearch/cluster/metadata/MetaData.java

@@ -674,6 +674,15 @@ public class MetaData implements Iterable<IndexMetaData> {
 
             aliasesOrIndices = convertFromWildcards(aliasesOrIndices, indicesOptions);
         }
+
+        if (aliasesOrIndices == null || aliasesOrIndices.length == 0) {
+            if (!indicesOptions.allowNoIndices()) {
+                throw new ElasticsearchIllegalArgumentException("no indices were specified and wildcard expansion is disabled.");
+            } else {
+                return Strings.EMPTY_ARRAY;
+            }
+        }
+
         boolean failClosed = indicesOptions.forbidClosedIndices() && !indicesOptions.ignoreUnavailable();
 
         // optimize for single element index (common case)
@@ -1058,7 +1067,7 @@ public class MetaData implements Iterable<IndexMetaData> {
      * @param types the array containing index names
      * @return true if the provided array maps to all indices, false otherwise
      */
-    public boolean isAllTypes(String[] types) {
+    public static boolean isAllTypes(String[] types) {
         return types == null || types.length == 0 || isExplicitAllPattern(types);
     }
 

src/test/java/org/elasticsearch/cluster/metadata/MetaDataTests.java

@@ -20,6 +20,8 @@
 package org.elasticsearch.cluster.metadata;
 
 import com.google.common.collect.Sets;
+
+import org.apache.tools.ant.taskdefs.condition.IsTrue;
 import org.elasticsearch.ElasticsearchIllegalArgumentException;
 import org.elasticsearch.Version;
 import org.elasticsearch.action.support.IndicesOptions;
@@ -107,9 +109,15 @@ public class MetaDataTests extends ElasticsearchTestCase {
         String[] results = md.concreteIndices(IndicesOptions.strictExpandOpen(), Strings.EMPTY_ARRAY);
         assertEquals(3, results.length);
 
+        results = md.concreteIndices(IndicesOptions.strictExpandOpen(), null);
+        assertEquals(3, results.length);
+
         results = md.concreteIndices(IndicesOptions.strictExpand(), Strings.EMPTY_ARRAY);
         assertEquals(4, results.length);
 
+        results = md.concreteIndices(IndicesOptions.strictExpand(), null);
+        assertEquals(4, results.length);
+
         results = md.concreteIndices(IndicesOptions.strictExpandOpen(), "foofoo*");
         assertEquals(3, results.length);
         assertThat(results, arrayContainingInAnyOrder("foo", "foobar", "foofoo"));
@@ -320,6 +328,12 @@ public class MetaDataTests extends ElasticsearchTestCase {
             results = md.concreteIndices(noExpandLenient, "foofoobar");
             assertEquals(2, results.length);
             assertThat(results, arrayContainingInAnyOrder("foo", "foobar"));
+
+            results = md.concreteIndices(noExpandLenient, null);
+            assertEquals(0, results.length);
+
+            results = md.concreteIndices(noExpandLenient, Strings.EMPTY_ARRAY);
+            assertEquals(0, results.length);
         }
 
         //ignore unavailable but don't allow no indices
@@ -478,7 +492,7 @@ public class MetaDataTests extends ElasticsearchTestCase {
     }
 
     @Test
-    public void convertWildcardsJustIndicesTests() {
+    public void testConvertWildcardsJustIndicesTests() {
         MetaData.Builder mdBuilder = MetaData.builder()
                 .put(indexBuilder("testXXX"))
                 .put(indexBuilder("testXYY"))
@@ -494,7 +508,7 @@ public class MetaDataTests extends ElasticsearchTestCase {
     }
 
     @Test
-    public void convertWildcardsTests() {
+    public void testConvertWildcardsTests() {
         MetaData.Builder mdBuilder = MetaData.builder()
                 .put(indexBuilder("testXXX").putAlias(AliasMetaData.builder("alias1")).putAlias(AliasMetaData.builder("alias2")))
                 .put(indexBuilder("testXYY").putAlias(AliasMetaData.builder("alias2")))
@@ -509,7 +523,7 @@ public class MetaDataTests extends ElasticsearchTestCase {
     }
 
     @Test
-    public void convertWildcardsOpenClosedIndicesTests() {
+    public void testConvertWildcardsOpenClosedIndicesTests() {
         MetaData.Builder mdBuilder = MetaData.builder()
                 .put(indexBuilder("testXXX").state(State.OPEN))
                 .put(indexBuilder("testXXY").state(State.OPEN))
@@ -529,7 +543,7 @@ public class MetaDataTests extends ElasticsearchTestCase {
     }
 
     @Test(expected = IndexMissingException.class)
-    public void concreteIndicesIgnoreIndicesOneMissingIndex() {
+    public void testConcreteIndicesIgnoreIndicesOneMissingIndex() {
         MetaData.Builder mdBuilder = MetaData.builder()
                 .put(indexBuilder("testXXX"))
                 .put(indexBuilder("kuku"));
@@ -538,7 +552,7 @@ public class MetaDataTests extends ElasticsearchTestCase {
     }
 
     @Test
-    public void concreteIndicesIgnoreIndicesOneMissingIndexOtherFound() {
+    public void testConcreteIndicesIgnoreIndicesOneMissingIndexOtherFound() {
         MetaData.Builder mdBuilder = MetaData.builder()
                 .put(indexBuilder("testXXX"))
                 .put(indexBuilder("kuku"));
@@ -547,7 +561,7 @@ public class MetaDataTests extends ElasticsearchTestCase {
     }
 
     @Test(expected = IndexMissingException.class)
-    public void concreteIndicesIgnoreIndicesAllMissing() {
+    public void testConcreteIndicesIgnoreIndicesAllMissing() {
         MetaData.Builder mdBuilder = MetaData.builder()
                 .put(indexBuilder("testXXX"))
                 .put(indexBuilder("kuku"));
@@ -556,7 +570,7 @@ public class MetaDataTests extends ElasticsearchTestCase {
     }
 
     @Test
-    public void concreteIndicesIgnoreIndicesEmptyRequest() {
+    public void testConcreteIndicesIgnoreIndicesEmptyRequest() {
         MetaData.Builder mdBuilder = MetaData.builder()
                 .put(indexBuilder("testXXX"))
                 .put(indexBuilder("kuku"));
@@ -565,7 +579,7 @@ public class MetaDataTests extends ElasticsearchTestCase {
     }
 
     @Test
-    public void concreteIndicesWildcardExpansion() {
+    public void testConcreteIndicesWildcardExpansion() {
         MetaData.Builder mdBuilder = MetaData.builder()
                 .put(indexBuilder("testXXX").state(State.OPEN))
                 .put(indexBuilder("testXXY").state(State.OPEN))
@@ -579,6 +593,113 @@ public class MetaDataTests extends ElasticsearchTestCase {
         assertThat(newHashSet(md.concreteIndices(IndicesOptions.fromOptions(true, true, true, true), "testX*")), equalTo(newHashSet("testXXX", "testXXY", "testXYY")));
     }
 
+    /**
+     * test resolving _all pattern (null, empty array or "_all") for random IndicesOptions
+     */
+    @Test
+    public void testConcreteIndicesAllPatternRandom() {
+        for (int i = 0; i < 10; i++) {
+            String[] allIndices = null;
+            switch (randomIntBetween(0, 2)) {
+            case 0:
+                break;
+            case 1:
+                allIndices = new String[0];
+                break;
+            case 2:
+                allIndices = new String[] { MetaData.ALL };
+                break;
+            }
+
+            IndicesOptions indicesOptions = IndicesOptions.fromOptions(randomBoolean(), randomBoolean(), randomBoolean(), randomBoolean());
+            MetaData metadata = MetaData.builder().build();
+
+            // with no indices, asking for all indices should return empty list or exception, depending on indices options
+            if (indicesOptions.allowNoIndices()) {
+                String[] concreteIndices = metadata.concreteIndices(indicesOptions, allIndices);
+                assertThat(concreteIndices, notNullValue());
+                assertThat(concreteIndices.length, equalTo(0));
+            } else {
+                checkCorrectException(metadata, indicesOptions, allIndices);
+            }
+
+            // with existing indices, asking for all indices should return all open/closed indices depending on options
+            metadata = MetaData.builder()
+                    .put(indexBuilder("aaa").state(State.OPEN).putAlias(AliasMetaData.builder("aaa_alias1")))
+                    .put(indexBuilder("bbb").state(State.OPEN).putAlias(AliasMetaData.builder("bbb_alias1")))
+                    .put(indexBuilder("ccc").state(State.CLOSE).putAlias(AliasMetaData.builder("ccc_alias1")))
+                    .build();
+            if (indicesOptions.expandWildcardsOpen() || indicesOptions.expandWildcardsClosed() || indicesOptions.allowNoIndices()) {
+                String[] concreteIndices = metadata.concreteIndices(indicesOptions, allIndices);
+                assertThat(concreteIndices, notNullValue());
+                int expectedNumberOfIndices = 0;
+                if (indicesOptions.expandWildcardsOpen()) {
+                    expectedNumberOfIndices += 2;
+                }
+                if (indicesOptions.expandWildcardsClosed()) {
+                    expectedNumberOfIndices += 1;
+                }
+                assertThat(concreteIndices.length, equalTo(expectedNumberOfIndices));
+            } else {
+                checkCorrectException(metadata, indicesOptions, allIndices);
+            }
+        }
+    }
+
+    /**
+     * check for correct exception type depending on indicesOptions and provided index name list
+     */
+    private void checkCorrectException(MetaData metadata, IndicesOptions indicesOptions, String[] allIndices) {
+     // two different exception types possible
+        if (!(indicesOptions.expandWildcardsOpen() || indicesOptions.expandWildcardsClosed())
+                && (allIndices == null || allIndices.length == 0)) {
+            try {
+                metadata.concreteIndices(indicesOptions, allIndices);
+                fail("no wildcard expansion and null or empty list argument should trigger ElasticsearchIllegalArgumentException");
+            } catch (ElasticsearchIllegalArgumentException e) {
+                // expected
+            }
+        } else {
+            try {
+                metadata.concreteIndices(indicesOptions, allIndices);
+                fail("wildcard expansion on should trigger IndexMissingException");
+            } catch (IndexMissingException e) {
+                // expected
+            }
+        }
+    }
+
+    /**
+     * test resolving wildcard pattern that matches no index of alias for random IndicesOptions
+     */
+    @Test
+    public void testConcreteIndicesWildcardNoMatch() {
+        for (int i = 0; i < 10; i++) {
+            IndicesOptions indicesOptions = IndicesOptions.fromOptions(randomBoolean(), randomBoolean(), randomBoolean(), randomBoolean());
+            MetaData metadata = MetaData.builder().build();
+
+            metadata = MetaData.builder()
+                    .put(indexBuilder("aaa").state(State.OPEN).putAlias(AliasMetaData.builder("aaa_alias1")))
+                    .put(indexBuilder("bbb").state(State.OPEN).putAlias(AliasMetaData.builder("bbb_alias1")))
+                    .put(indexBuilder("ccc").state(State.CLOSE).putAlias(AliasMetaData.builder("ccc_alias1")))
+                    .build();
+
+            // asking for non existing wildcard pattern should return empty list or exception
+            if (indicesOptions.allowNoIndices()) {
+                String[] concreteIndices = metadata.concreteIndices(indicesOptions, "Foo*");
+                assertThat(concreteIndices, notNullValue());
+                assertThat(concreteIndices.length, equalTo(0));
+            } else {
+                try {
+                    metadata.concreteIndices(indicesOptions, "Foo*");
+                    fail("expecting exeption when result empty and allowNoIndicec=false");
+                } catch (IndexMissingException e) {
+                    // expected exception
+                }
+            }
+        }
+    }
+
     @Test
     public void testIsAllIndices_null() throws Exception {
         assertThat(MetaData.isAllIndices(null), equalTo(true));
@@ -636,7 +757,6 @@ public class MetaDataTests extends ElasticsearchTestCase {
 
     @Test
     public void testIsExplicitAllIndices_wildcard() throws Exception {
-        MetaData metaData = MetaData.builder().build();
         assertThat(MetaData.isExplicitAllPattern(new String[]{"*"}), equalTo(false));
     }