Make ID3 GEOB frames parsing more robust

Issue:#3792

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=185668919

RELEASENOTES.md

@@ -109,6 +109,8 @@
 * Release `Extractor`s on the loading thread to avoid potentially leaking
   resources when the playback thread has quit by the time the loading task has
   completed.
+* ID3: Better handle malformed ID3 data
+  ([#3792](https://github.com/google/ExoPlayer/issues/3792).
 
 ### 2.6.1 ###
 

library/core/src/main/java/com/google/android/exoplayer2/metadata/id3/Id3Decoder.java

@@ -405,14 +405,9 @@ private static TextInformationFrame decodeTxxxFrame(ParsableByteArray id3Data, i
     int descriptionEndIndex = indexOfEos(data, 0, encoding);
     String description = new String(data, 0, descriptionEndIndex, charset);
 
-    String value;
     int valueStartIndex = descriptionEndIndex + delimiterLength(encoding);
-    if (valueStartIndex < data.length) {
-      int valueEndIndex = indexOfEos(data, valueStartIndex, encoding);
-      value = new String(data, valueStartIndex, valueEndIndex - valueStartIndex, charset);
-    } else {
-      value = "";
-    }
+    int valueEndIndex = indexOfEos(data, valueStartIndex, encoding);
+    String value = decodeStringIfValid(data, valueStartIndex, valueEndIndex, charset);
 
     return new TextInformationFrame("TXXX", description, value);
   }
@@ -452,14 +447,9 @@ private static UrlLinkFrame decodeWxxxFrame(ParsableByteArray id3Data, int frame
     int descriptionEndIndex = indexOfEos(data, 0, encoding);
     String description = new String(data, 0, descriptionEndIndex, charset);
 
-    String url;
     int urlStartIndex = descriptionEndIndex + delimiterLength(encoding);
-    if (urlStartIndex < data.length) {
-      int urlEndIndex = indexOfZeroByte(data, urlStartIndex);
-      url = new String(data, urlStartIndex, urlEndIndex - urlStartIndex, "ISO-8859-1");
-    } else {
-      url = "";
-    }
+    int urlEndIndex = indexOfZeroByte(data, urlStartIndex);
+    String url = decodeStringIfValid(data, urlStartIndex, urlEndIndex, "ISO-8859-1");
 
     return new UrlLinkFrame("WXXX", description, url);
   }
@@ -502,13 +492,12 @@ private static GeobFrame decodeGeobFrame(ParsableByteArray id3Data, int frameSiz
 
     int filenameStartIndex = mimeTypeEndIndex + 1;
     int filenameEndIndex = indexOfEos(data, filenameStartIndex, encoding);
-    String filename = new String(data, filenameStartIndex, filenameEndIndex - filenameStartIndex,
-        charset);
+    String filename = decodeStringIfValid(data, filenameStartIndex, filenameEndIndex, charset);
 
     int descriptionStartIndex = filenameEndIndex + delimiterLength(encoding);
     int descriptionEndIndex = indexOfEos(data, descriptionStartIndex, encoding);
-    String description = new String(data, descriptionStartIndex,
-        descriptionEndIndex - descriptionStartIndex, charset);
+    String description =
+        decodeStringIfValid(data, descriptionStartIndex, descriptionEndIndex, charset);
 
     int objectDataStartIndex = descriptionEndIndex + delimiterLength(encoding);
     byte[] objectData = copyOfRangeIfValid(data, objectDataStartIndex, data.length);
@@ -573,14 +562,9 @@ private static CommentFrame decodeCommentFrame(ParsableByteArray id3Data, int fr
     int descriptionEndIndex = indexOfEos(data, 0, encoding);
     String description = new String(data, 0, descriptionEndIndex, charset);
 
-    String text;
     int textStartIndex = descriptionEndIndex + delimiterLength(encoding);
-    if (textStartIndex < data.length) {
-      int textEndIndex = indexOfEos(data, textStartIndex, encoding);
-      text = new String(data, textStartIndex, textEndIndex - textStartIndex, charset);
-    } else {
-      text = "";
-    }
+    int textEndIndex = indexOfEos(data, textStartIndex, encoding);
+    String text = decodeStringIfValid(data, textStartIndex, textEndIndex, charset);
 
     return new CommentFrame(language, description, text);
   }
@@ -760,6 +744,25 @@ private static byte[] copyOfRangeIfValid(byte[] data, int from, int to) {
     return Arrays.copyOfRange(data, from, to);
   }
 
+  /**
+   * Returns a string obtained by decoding the specified range of {@code data} using the specified
+   * {@code charsetName}. An empty string is returned if the range is invalid.
+   *
+   * @param data The array from which to decode the string.
+   * @param from The start of the range.
+   * @param to The end of the range (exclusive).
+   * @param charsetName The name of the Charset to use.
+   * @return The decoded string, or an empty string if the range is invalid.
+   * @throws UnsupportedEncodingException If the Charset is not supported.
+   */
+  private static String decodeStringIfValid(byte[] data, int from, int to, String charsetName)
+      throws UnsupportedEncodingException {
+    if (to <= from || to > data.length) {
+      return "";
+    }
+    return new String(data, from, to - from, charsetName);
+  }
+
   private static final class Id3Header {
 
     private final int majorVersion;