From 99b4f7c16886803c0af5e0b5862d85ad6dac95f7 Mon Sep 17 00:00:00 2001
From: Serge Latyntcev <dnsl48@gmail.com>
Date: Mon, 1 Jul 2019 10:27:09 +1200
Subject: [PATCH] FIX DatabaseStore binary safety

---
 src/Store/DatabaseStore.php | 48 +++++++++++++++++++++++++++++++++++--
 1 file changed, 46 insertions(+), 2 deletions(-)

diff --git a/src/Store/DatabaseStore.php b/src/Store/DatabaseStore.php
index fdb1536..4563df2 100644
--- a/src/Store/DatabaseStore.php
+++ b/src/Store/DatabaseStore.php
@@ -61,7 +61,8 @@ public function read($session_id)
 
         if ($result && $result->numRecords()) {
             $data = $result->first();
-            return $data['Data'];
+            $decoded = $this->binaryDataJsonDecode($data['Data']);
+            return is_null($decoded) ? $data['Data'] : $decoded;
         }
     }
 
@@ -79,7 +80,7 @@ public function write($session_id, $session_data)
             ON DUPLICATE KEY UPDATE "Expiry" = %2$u, "Data" = \'%3$s\'',
             Convert::raw2sql($session_id),
             $expiry,
-            Convert::raw2sql($session_data)
+            Convert::raw2sql($this->binaryDataJsonEncode($session_data))
         ));
 
         return true;
@@ -101,4 +102,47 @@ public function gc($maxlifetime)
             $this->getNow()
         ));
     }
+
+    /**
+    * Encode binary data into ASCII string (a subset of UTF-8)
+    *
+    * Silverstripe <= 4.4 does not have a binary db field implementation, so we have to store
+    * binary data as text
+    *
+    * @param string $data This is a binary blob
+    *
+    * @return string
+    */
+    private function binaryDataJsonEncode($data)
+    {
+        return json_encode([
+            self::class,
+            base64_encode($data)
+        ]);
+    }
+
+    /**
+     * Decode ASCII string into original binary data (a php string)
+     *
+     * Silverstripe <= 4.4 does not have a binary db field implementation, so we have to store
+     * binary data as text
+     *
+     * @param string $text
+     *
+     * @param null|string
+     */
+    private function binaryDataJsonDecode($text)
+    {
+        $struct = json_decode($text, true, 2);
+
+        if (!is_array($struct) || count($struct) !== 2) {
+            return null;
+        }
+
+        if (!isset($struct[0]) || !isset($struct[1]) || $struct[0] !== self::class) {
+            return null;
+        }
+
+        return base64_decode($struct[1]);
+    }
 }