From ea9ee985e85b0093ac5b14858b74c93883884024 Mon Sep 17 00:00:00 2001
From: Nabeel S <nabeelio@users.noreply.github.com>
Date: Fri, 28 Feb 2020 22:50:41 -0500
Subject: [PATCH] METAR parsing infinite loop bugfix #599 (#600)

METAR parsing infinite loop bugfix #599
---
 app/Services/Metar/AviationWeather.php | 24 +++++++++++++++++++++---
 app/Widgets/Weather.php                |  1 +
 tests/MetarTest.php                    | 11 +++++++++++
 tests/data/aviationweather/unknown.xml |  0
 4 files changed, 33 insertions(+), 3 deletions(-)
 create mode 100644 tests/data/aviationweather/unknown.xml

diff --git a/app/Services/Metar/AviationWeather.php b/app/Services/Metar/AviationWeather.php
index 8c894272..400ce1b3 100644
--- a/app/Services/Metar/AviationWeather.php
+++ b/app/Services/Metar/AviationWeather.php
@@ -4,6 +4,8 @@ namespace App\Services\Metar;
 
 use App\Contracts\Metar;
 use App\Support\HttpClient;
+use function count;
+use Exception;
 use Illuminate\Support\Facades\Log;
 
 /**
@@ -44,15 +46,31 @@ class AviationWeather extends Metar
         try {
             $res = $this->httpClient->get($url, []);
             $xml = simplexml_load_string($res);
-            if (\count($xml->data->METAR->raw_text) === 0) {
+
+            $attrs = $xml->data->attributes();
+            if (!isset($attrs['num_results'])) {
+                return '';
+            }
+
+            $num_results = $attrs['num_results'];
+            if (empty($num_results)) {
+                return '';
+            }
+
+            $num_results = (int) $num_results;
+            if ($num_results === 0) {
+                return '';
+            }
+
+            if (count($xml->data->METAR->raw_text) === 0) {
                 return '';
             }
 
             return $xml->data->METAR->raw_text->__toString();
-        } catch (\Exception $e) {
+        } catch (Exception $e) {
             Log::error('Error reading METAR: '.$e->getMessage());
 
-            throw $e;
+            return '';
         }
     }
 }
diff --git a/app/Widgets/Weather.php b/app/Widgets/Weather.php
index 1cf6491d..194e356e 100644
--- a/app/Widgets/Weather.php
+++ b/app/Widgets/Weather.php
@@ -19,6 +19,7 @@ class Weather extends Widget
      */
     public function run()
     {
+        /** @var \App\Services\AirportService $airportSvc */
         $airportSvc = app(AirportService::class);
         $metar = $airportSvc->getMetar($this->config['icao']);
 
diff --git a/tests/MetarTest.php b/tests/MetarTest.php
index c0472ea0..82f577a5 100644
--- a/tests/MetarTest.php
+++ b/tests/MetarTest.php
@@ -185,4 +185,15 @@ class MetarTest extends TestCase
 
         $this->assertNull($airportSvc->getMetar('idk'));
     }
+
+    public function testHttpCallUnknown()
+    {
+        $this->mockXmlResponse('aviationweather/unknown.xml');
+
+        /** @var AirportService $airportSvc */
+        $airportSvc = app(AirportService::class);
+
+        $metar = $airportSvc->getMetar('7AK4');
+        $this->assertNull($metar);
+    }
 }
diff --git a/tests/data/aviationweather/unknown.xml b/tests/data/aviationweather/unknown.xml
new file mode 100644
index 00000000..e69de29b