[Youtube] Adjust throttling function extraction to changes (#1191)

* [Youtube] Adjust throttling function extraction to changes

---------

Co-authored-by: Stypox <[email protected]>

Author: XiangRongLin

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

@@ -1,5 +1,7 @@
 package org.schabi.newpipe.extractor.services.youtube;
 
+import static org.schabi.newpipe.extractor.utils.Parser.matchGroup1MultiplePatterns;
+
 import org.schabi.newpipe.extractor.exceptions.ParsingException;
 import org.schabi.newpipe.extractor.utils.JavaScript;
 import org.schabi.newpipe.extractor.utils.Parser;
@@ -20,13 +22,13 @@ final class YoutubeSignatureUtils {
      */
     static final String DEOBFUSCATION_FUNCTION_NAME = "deobfuscate";
 
-    private static final String[] FUNCTION_REGEXES = {
-            "\\bm=([a-zA-Z0-9$]{2,})\\(decodeURIComponent\\(h\\.s\\)\\)",
-            "\\bc&&\\(c=([a-zA-Z0-9$]{2,})\\(decodeURIComponent\\(c\\)\\)",
+    private static final Pattern[] FUNCTION_REGEXES = {
             // CHECKSTYLE:OFF
-            "(?:\\b|[^a-zA-Z0-9$])([a-zA-Z0-9$]{2,})\\s*=\\s*function\\(\\s*a\\s*\\)\\s*\\{\\s*a\\s*=\\s*a\\.split\\(\\s*\"\"\\s*\\)",
+            Pattern.compile("\\bm=([a-zA-Z0-9$]{2,})\\(decodeURIComponent\\(h\\.s\\)\\)"),
+            Pattern.compile("\\bc&&\\(c=([a-zA-Z0-9$]{2,})\\(decodeURIComponent\\(c\\)\\)"),
+            Pattern.compile("(?:\\b|[^a-zA-Z0-9$])([a-zA-Z0-9$]{2,})\\s*=\\s*function\\(\\s*a\\s*\\)\\s*\\{\\s*a\\s*=\\s*a\\.split\\(\\s*\"\"\\s*\\)"),
+            Pattern.compile("([\\w$]+)\\s*=\\s*function\\((\\w+)\\)\\{\\s*\\2=\\s*\\2\\.split\\(\"\"\\)\\s*;")
             // CHECKSTYLE:ON
-            "([\\w$]+)\\s*=\\s*function\\((\\w+)\\)\\{\\s*\\2=\\s*\\2\\.split\\(\"\"\\)\\s*;"
     };
 
     private static final String STS_REGEX = "signatureTimestamp[=:](\\d+)";
@@ -104,19 +106,12 @@ static String getDeobfuscationCode(@Nonnull final String javaScriptPlayerCode)
     @Nonnull
     private static String getDeobfuscationFunctionName(@Nonnull final String javaScriptPlayerCode)
             throws ParsingException {
-        Parser.RegexException exception = null;
-        for (final String regex : FUNCTION_REGEXES) {
-            try {
-                return Parser.matchGroup1(regex, javaScriptPlayerCode);
-            } catch (final Parser.RegexException e) {
-                if (exception == null) {
-                    exception = e;
-                }
-            }
+        try {
+            return matchGroup1MultiplePatterns(FUNCTION_REGEXES, javaScriptPlayerCode);
+        } catch (final Parser.RegexException e) {
+            throw new ParsingException(
+                    "Could not find deobfuscation function with any of the known patterns", e);
         }
-
-        throw new ParsingException(
-                "Could not find deobfuscation function with any of the known patterns", exception);
     }
 
     @Nonnull

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

@@ -1,5 +1,7 @@
 package org.schabi.newpipe.extractor.services.youtube;
 
+import static org.schabi.newpipe.extractor.utils.Parser.matchMultiplePatterns;
+
 import org.schabi.newpipe.extractor.exceptions.ParsingException;
 import org.schabi.newpipe.extractor.utils.JavaScript;
 import org.schabi.newpipe.extractor.utils.Parser;
@@ -18,10 +20,33 @@ final class YoutubeThrottlingParameterUtils {
 
     private static final Pattern THROTTLING_PARAM_PATTERN = Pattern.compile("[&?]n=([^&]+)");
 
-    private static final Pattern DEOBFUSCATION_FUNCTION_NAME_PATTERN = Pattern.compile(
-            // CHECKSTYLE:OFF
-            "\\.get\\(\"n\"\\)\\)&&\\([a-zA-Z0-9$_]=([a-zA-Z0-9$_]+)(?:\\[(\\d+)])?\\([a-zA-Z0-9$_]\\)");
-            // CHECKSTYLE:ON
+    private static final String SINGLE_CHAR_VARIABLE_REGEX = "[a-zA-Z0-9$_]";
+
+    private static final String FUNCTION_NAME_REGEX = SINGLE_CHAR_VARIABLE_REGEX + "+";
+
+    private static final String ARRAY_ACCESS_REGEX = "\\[(\\d+)]";
+
+    /**
+     * The first regex matches this, where we want BDa:
+     * <p>
+     * (b=String.fromCharCode(110),c=a.get(b))&&(c=<strong>BDa</strong><strong>[0]</strong>(c)
+     * <p>
+     * Array access is optional, but needs to be handled, since the actual function is inside the
+     * array.
+     */
+    // CHECKSTYLE:OFF
+    private static final Pattern[] DEOBFUSCATION_FUNCTION_NAME_REGEXES = {
+            Pattern.compile("\\(" + SINGLE_CHAR_VARIABLE_REGEX + "=String\\.fromCharCode\\(110\\),"
+                    + SINGLE_CHAR_VARIABLE_REGEX + "=" + SINGLE_CHAR_VARIABLE_REGEX + "\\.get\\("
+                    + SINGLE_CHAR_VARIABLE_REGEX + "\\)\\)" + "&&\\(" + SINGLE_CHAR_VARIABLE_REGEX
+                    + "=(" + FUNCTION_NAME_REGEX + ")" + "(?:" + ARRAY_ACCESS_REGEX + ")?\\("
+                    + SINGLE_CHAR_VARIABLE_REGEX + "\\)"),
+            Pattern.compile("\\.get\\(\"n\"\\)\\)&&\\(" + SINGLE_CHAR_VARIABLE_REGEX
+                    + "=(" + FUNCTION_NAME_REGEX + ")(?:" + ARRAY_ACCESS_REGEX + ")?\\("
+                    + SINGLE_CHAR_VARIABLE_REGEX + "\\)"),
+    };
+    // CHECKSTYLE:ON
+
 
     // Escape the curly end brace to allow compatibility with Android's regex engine
     // See https://stackoverflow.com/q/45074813
@@ -48,11 +73,13 @@ private YoutubeThrottlingParameterUtils() {
     @Nonnull
     static String getDeobfuscationFunctionName(@Nonnull final String javaScriptPlayerCode)
             throws ParsingException {
-        final Matcher matcher = DEOBFUSCATION_FUNCTION_NAME_PATTERN.matcher(javaScriptPlayerCode);
-        if (!matcher.find()) {
-            throw new ParsingException("Failed to find deobfuscation function name pattern \""
-                    + DEOBFUSCATION_FUNCTION_NAME_PATTERN
-                    + "\" in the base JavaScript player code");
+        final Matcher matcher;
+        try {
+            matcher = matchMultiplePatterns(DEOBFUSCATION_FUNCTION_NAME_REGEXES,
+                    javaScriptPlayerCode);
+        } catch (final Parser.RegexException e) {
+            throw new ParsingException("Could not find deobfuscation function with any of the "
+                    + "known patterns in the base JavaScript player code", e);
         }
 
         final String functionName = matcher.group(1);

extractor/src/main/java/org/schabi/newpipe/extractor/utils/Parser.java

@@ -78,6 +78,37 @@ public static String matchGroup(@Nonnull final Pattern pat,
         }
     }
 
+    public static String matchGroup1MultiplePatterns(final Pattern[] patterns, final String input)
+            throws RegexException {
+        return matchMultiplePatterns(patterns, input).group(1);
+    }
+
+    public static Matcher matchMultiplePatterns(final Pattern[] patterns, final String input)
+            throws RegexException {
+        Parser.RegexException exception = null;
+        for (final Pattern pattern : patterns) {
+            final Matcher matcher = pattern.matcher(input);
+            if (matcher.find()) {
+                return matcher;
+            } else if (exception == null) {
+                // only pass input to exception message when it is not too long
+                if (input.length() > 1024) {
+                    exception = new RegexException("Failed to find pattern \"" + pattern.pattern()
+                            + "\"");
+                } else {
+                    exception = new RegexException("Failed to find pattern \"" + pattern.pattern()
+                            + "\" inside of \"" + input + "\"");
+                }
+            }
+        }
+
+        if (exception == null) {
+            throw new RegexException("Empty patterns array passed to matchMultiplePatterns");
+        } else {
+            throw exception;
+        }
+    }
+
     public static boolean isMatch(final String pattern, final String input) {
         final Pattern pat = Pattern.compile(pattern);
         final Matcher mat = pat.matcher(input);