- * YouTube's media is protected with a cipher, - * which modifies the "n" query parameter of it's video playback urls. - * This class handles extracting that "n" query parameter, - * applying the cipher on it and returning the resulting url which is not throttled. + * This class handles extracting that {@code n} query parameter, applying the cipher on it and + * returning the resulting URL which is not throttled. *
* - *- * https://r5---sn-4g5ednsz.googlevideo.com/videoplayback?n=VVF2xyZLVRZZxHXZ&other=other - *- * becomes - *
- * https://r5---sn-4g5ednsz.googlevideo.com/videoplayback?n=iHywZkMipkszqA&other=other - *- *
- * Decoding the "n" parameter is time intensive. For this reason, the results are cached. - * The cache can be cleared using {@link #clearCache()} + * For instance, + * {@code https://r5---sn-4g5ednsz.googlevideo.com/videoplayback?n=VVF2xyZLVRZZxHXZ&other=other} + * becomes + * {@code https://r5---sn-4g5ednsz.googlevideo.com/videoplayback?n=iHywZkMipkszqA&other=other}. + *
+ * + *+ * Decoding the {@code n} parameter is time intensive. For this reason, the results are cached. + * The cache can be cleared using {@link #clearCache()}. *
* */ @@ -73,13 +73,35 @@ public class YoutubeThrottlingDecrypter { } /** + * Try to decrypt a YouTube streaming URL protected with a throttling parameter. + * *- * The videoId is only used to fetch the decryption function. - * It can be a constant value of any existing video. - * A constant value is discouraged, because it could allow tracking. + * If the streaming URL provided doesn't contain a throttling parameter, it is returned as it + * is; otherwise, the encrypted value is decrypted and this value is replaced by the decrypted + * one. + *
+ * + *+ * If the JavaScript code has been not extracted, it is extracted with the given video ID using + * {@link YoutubeJavaScriptExtractor#extractJavaScriptCode(String)}. + *
+ * + * @param streamingUrl The streaming URL to decrypt, if needed. + * @param videoId A video ID, used to fetch the JavaScript code to get the decryption + * function. It can be a constant value of any existing video, but a + * constant value is discouraged, because it could allow tracking. + * @return A streaming URL with the decrypted parameter or the streaming URL itself if no + * throttling parameter has been found + * @throws ParsingException If the streaming URL contains a throttling parameter and its + * decryption failed */ - public static String apply(final String url, final String videoId) throws ParsingException { - if (containsNParam(url)) { + public static String apply(@Nonnull final String streamingUrl, + @Nonnull final String videoId) throws ParsingException { + if (!containsNParam(streamingUrl)) { + return streamingUrl; + } + + try { if (FUNCTION == null) { final String playerJsCode = YoutubeJavaScriptExtractor.extractJavaScriptCode(videoId); @@ -88,11 +110,11 @@ public class YoutubeThrottlingDecrypter { FUNCTION = parseDecodeFunction(playerJsCode, FUNCTION_NAME); } - final String oldNParam = parseNParam(url); + final String oldNParam = parseNParam(streamingUrl); final String newNParam = decryptNParam(FUNCTION, FUNCTION_NAME, oldNParam); - return replaceNParam(url, oldNParam, newNParam); - } else { - return url; + return replaceNParam(streamingUrl, oldNParam, newNParam); + } catch (final Exception e) { + throw new ParsingException("Could not parse, decrypt or replace n parameter", e); } } diff --git a/extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeStreamExtractor.java b/extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeStreamExtractor.java index 5b9ae5801..82a5d0168 100644 --- a/extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeStreamExtractor.java +++ b/extractor/src/main/java/org/schabi/newpipe/extractor/services/youtube/extractors/YoutubeStreamExtractor.java @@ -602,15 +602,21 @@ public class YoutubeStreamExtractor extends StreamExtractor { } /** - * Try to decrypt url and fallback to given url, because decryption is not - * always needed. + * Try to decrypt a streaming URL and fallback to the given URL, because decryption may fail if + * YouTube do breaking changes. + * + ** This way a breaking change from YouTube does not result in a broken extractor. + *
+ * + * @param streamingUrl the streaming URL to decrypt with {@link YoutubeThrottlingDecrypter} + * @param videoId the video ID to use when extracting JavaScript player code, if needed */ - private String tryDecryptUrl(final String url, final String videoId) { + private String tryDecryptUrl(final String streamingUrl, final String videoId) { try { - return YoutubeThrottlingDecrypter.apply(url, videoId); + return YoutubeThrottlingDecrypter.apply(streamingUrl, videoId); } catch (final ParsingException e) { - return url; + return streamingUrl; } }