add Nginx secure link md5 pattern valid check function

lib/DirScanner.php

@@ -81,6 +81,26 @@ Class DirScanner {
         return !empty($realpath) ? md5($realpath) : '';
     }
 
+    //判断Nginx防盗链MD5加密方式字符串是否合格
+    private function isNginxSecureLinkMd5PatternValid($pattern) {
+        $valid = true;
+
+        $fieldsNeeded = [
+                '{secure_link_expires}',
+                '{uri}',
+                '{remote_addr}',
+                '{secret}',
+            ];
+        foreach($fieldsNeeded as $needle) {
+            if (strstr($pattern, $needle) === false) {
+                $valid = false;
+                break;
+            }
+        }
+
+        return $valid;
+    }
+
 
     //根据文件生成防盗链网址
     //参考：https://nginx.org/en/docs/http/ngx_http_secure_link_module.html#secure_link
@@ -159,6 +179,9 @@ Class DirScanner {
         }
 
         if (!empty($pattern) && is_string($pattern)) {
+            if ($this->isNginxSecureLinkMd5PatternValid($pattern) == false) {
+                throw new Exception("Invalid Nginx secure link md5 pattern: {$pattern}", 500);
+            }
             $this->nginxSecureLinkMd5Pattern = $pattern;
         }
 
@@ -204,6 +227,9 @@ Class DirScanner {
      */
     public function setNginxSecureLinkMd5Pattern($pattern) {
         if (!empty($pattern) && is_string($pattern)) {
+            if ($this->isNginxSecureLinkMd5PatternValid($pattern) == false) {
+                throw new Exception("Invalid Nginx secure link md5 pattern: {$pattern}", 500);
+            }
             $this->nginxSecureLinkMd5Pattern = $pattern;
         }
     }

test/DirScannerTest.php

@@ -53,7 +53,10 @@ class DirScannerTest extends DirScanner {
 
 //--调用测试方法--
 $scanner = new DirScannerTest();
-$scanner->secureLinkTest('/default/', 'foo=bar', '127.0.0.1');
+//$scanner->secureLinkTest('/default/', 'foo=bar', '127.0.0.1', '{test}hello');
+//$scanner->secureLinkTest('/default/', 'foo=bar', '127.0.0.1', '');
+//$scanner->secureLinkTest('/default/', 'foo=bar', '127.0.0.1', '{secret} {secure_link_expires}{uri}{remote_addr}');
+
 $scanner->getFilePathTest('/content/小说/金庸/', '书剑恩仇录', 'md');
 $scanner->getFilePathTest('/content/小说/金庸/', '封面图', 'jpg');
 $scanner->getFilePathTest('/content/视频/游戏/', 'demo', 'm3u8');