From 8fd9acb2ce336a07a185339b8a7b273145928f40 Mon Sep 17 00:00:00 2001
From: Romain Quetiez <romain.quetiez@combodo.com>
Date: Mon, 26 Sep 2016 19:11:08 +0000
Subject: [PATCH] N.440 Remote troubleshooting: when the REST/JSON API fails
 due to malformed utf8 characters, return a meaningful json error message
 (explain + debug information) instead of an empty response

SVN:trunk[4417]
---
 webservices/rest.php | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/webservices/rest.php b/webservices/rest.php
index a307bd878c..9a49c3bd03 100644
--- a/webservices/rest.php
+++ b/webservices/rest.php
@@ -86,6 +86,22 @@ class RestResultListOperations extends RestResult
 	}
 }
 
+if (!function_exists('json_last_error_msg')) {
+	function json_last_error_msg() {
+		static $ERRORS = array(
+			JSON_ERROR_NONE => 'No error',
+			JSON_ERROR_DEPTH => 'Maximum stack depth exceeded',
+			JSON_ERROR_STATE_MISMATCH => 'State mismatch (invalid or malformed JSON)',
+			JSON_ERROR_CTRL_CHAR => 'Control character error, possibly incorrectly encoded',
+			JSON_ERROR_SYNTAX => 'Syntax error',
+			JSON_ERROR_UTF8 => 'Malformed UTF-8 characters, possibly incorrectly encoded'
+		);
+
+		$error = json_last_error();
+		return isset($ERRORS[$error]) ? $ERRORS[$error] : 'Unknown error';
+	}
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 //
 // Main
@@ -215,6 +231,14 @@ catch(Exception $e)
 //
 $sResponse = json_encode($oResult);
 
+if ($sResponse === false)
+{
+	$oJsonIssue = new RestResult();
+	$oJsonIssue->code = RestResult::INTERNAL_ERROR;
+	$oJsonIssue->message = 'json encoding failed with message: '.json_last_error_msg().'. Full response structure for debugging purposes (print_r+bin2hex): '.bin2hex(print_r($oResult, true));
+	$sResponse = json_encode($oJsonIssue);
+}
+
 $oP->add_header('Access-Control-Allow-Origin: *');
 
 $sCallback = utils::ReadParam('callback', null);