SQL: Improve error message for huge error responses (elastic/x-pack-elasticsearch#3049)

If the user has a funky proxy or something that throws back a massive
error message to the CLI or JDBC then return a sensible error message.

Original commit: elastic/x-pack-elasticsearch@94219969ea

sql/shared-client/src/main/java/org/elasticsearch/xpack/sql/client/shared/RemoteFailure.java

@@ -27,9 +27,14 @@ import static java.util.Collections.emptyMap;
 public class RemoteFailure {
     /**
      * The maximum number of bytes before we no longer include the raw response if
-     * there is a catastrophic error parsing the remote failure.
+     * there is a catastrophic error parsing the remote failure. The actual value
+     * was chosen because it is ten times larger then a "normal" elasticsearch
+     * failure but not so big that we'll consume a ton of memory on huge errors.
+     * It <strong>will</strong> produce huge error messages but the user might
+     * want all that because it is <strong>probably</strong> being thrown by
+     * their proxy.
      */
-    private static final int MAX_RAW_RESPONSE = 50*1024;
+    static final int MAX_RAW_RESPONSE = 512 * 1024;
 
     private static final JsonFactory JSON_FACTORY = new JsonFactory();
     static {
@@ -247,7 +252,12 @@ public class RemoteFailure {
     private static String parseErrorMessage(String message, InputStream stream, JsonParser parser) {
         String responseMessage;
         try {
-            stream.reset();
+            try {
+                stream.reset();
+            } catch (IOException e) {
+                // So far as I know, this is always caused by the response being too large
+                throw new IOException("Response too large", e);
+            }
             try (Reader reader = new InputStreamReader(stream, StandardCharsets.UTF_8)) {
                 StringBuilder builder = new StringBuilder();
                 builder.append("Response:\n");
@@ -259,7 +269,6 @@ public class RemoteFailure {
                 responseMessage = builder.toString();
             }
         } catch (IOException replayException) {
-            // TODO check for failed reset and return different error
             responseMessage = "Attempted to include response but failed because [" + replayException.getMessage() + "].";
         }
         String parserLocation = "";

sql/shared-client/src/test/java/org/elasticsearch/xpack/sql/client/shared/RemoteFailureTests.java

@@ -7,7 +7,9 @@ package org.elasticsearch.xpack.sql.client.shared;
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.lang.StringBuilder;
 import java.nio.file.Files;
+import java.util.Locale;
 
 import org.elasticsearch.common.bytes.BytesArray;
 import org.elasticsearch.test.ESTestCase;
@@ -118,6 +120,29 @@ public class RemoteFailureTests extends ESTestCase {
                 + "was expecting ('true', 'false' or 'null')] at [line 1 col 1]. Response:\n"));
     }
 
+    public void testTooBig() throws IOException {
+        StringBuilder tooBig = new StringBuilder(RemoteFailure.MAX_RAW_RESPONSE);
+        tooBig.append("{\n");
+        tooBig.append("\"error\" : {\n");
+        tooBig.append("  \"type\" : \"illegal_argument_exception\",\n");
+        tooBig.append("  \"reason\" : \"something\",\n");
+        tooBig.append("  \"header\" : {\n");
+        int i = 0;
+        while (tooBig.length() < RemoteFailure.MAX_RAW_RESPONSE) {
+            tooBig.append("    \"").append(String.format(Locale.ROOT, "%04d", i++))
+                .append("\" : \"lots and lots and lots and lots and lots of words\",\n");
+        }
+        tooBig.append("    \"end\" : \"lots and lots and lots and lots and lots of words\"\n");
+        tooBig.append("  }\n");
+        tooBig.append("}\n");
+        IOException e = expectThrows(IOException.class, () ->
+            RemoteFailure.parseFromResponse(new BytesArray(tooBig.toString()).streamInput()));
+        assertEquals(
+            "Can't parse error from Elasticearch [expected [stack_trace] cannot but didn't see it] "
+                + "at [line 7951 col 1]. Attempted to include response but failed because [Response too large].",
+            e.getMessage());
+    }
+
     private RemoteFailure parse(String fileName) throws IOException {
         try (InputStream in = Files.newInputStream(getDataPath("/remote_failure/" + fileName))) {
             return RemoteFailure.parseFromResponse(in);