Merge pull request #934 from AudricV/fix-yt-throttling-decryption-function-regex

[YouTube] Fix throttling decryption function regex

Author: Stypox

extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/YoutubeThrottlingDecrypter.java

@@ -38,7 +38,15 @@ public final class YoutubeThrottlingDecrypter {
 
     private static final Pattern N_PARAM_PATTERN = Pattern.compile("[&?]n=([^&]+)");
     private static final Pattern DECRYPT_FUNCTION_NAME_PATTERN = Pattern.compile(
-            "\\.get\\(\"n\"\\)\\)&&\\(b=([a-zA-Z0-9$]+)(?:\\[(\\d+)])?\\([a-zA-Z0-9]\\)");
+            // CHECKSTYLE:OFF
+            "\\.get\\(\"n\"\\)\\)&&\\([a-zA-Z0-9$_]=([a-zA-Z0-9$_]+)(?:\\[(\\d+)])?\\([a-zA-Z0-9$_]\\)");
+            // CHECKSTYLE:ON
+
+    // Escape the curly end brace to allow compatibility with Android's regex engine
+    // See https://stackoverflow.com/q/45074813
+    @SuppressWarnings("RegExpRedundantEscape")
+    private static final String DECRYPT_FUNCTION_BODY_REGEX =
+            "=\\s*function([\\S\\s]*?\\}\\s*return [\\w$]+?\\.join\\(\"\"\\)\\s*\\};)";
 
     private static final Map<String, String> N_PARAMS_CACHE = new HashMap<>();
     private static String decryptFunction;
@@ -128,11 +136,9 @@ private static String parseDecodeFunction(final String playerJsCode, final Strin
     @Nonnull
     private static String parseWithRegex(final String playerJsCode, final String functionName)
             throws Parser.RegexException {
-        // Escape the curly end brace to allow compatibility with Android's regex engine
-        // See https://stackoverflow.com/q/45074813
-        //noinspection RegExpRedundantEscape
-        final Pattern functionPattern = Pattern.compile(functionName + "=function(.*?\\};)\n",
-                Pattern.DOTALL);
+        // Quote the function name, as it may contain special regex characters such as dollar
+        final Pattern functionPattern = Pattern.compile(
+                Pattern.quote(functionName) + DECRYPT_FUNCTION_BODY_REGEX, Pattern.DOTALL);
         return validateFunction("function "
                 + functionName
                 + Parser.matchGroup1(functionPattern, playerJsCode));