public static ReadOnlyMemory <byte> DecryptSegmentData(byte[] encryptedSegmentData, HlsMediaSegment segment, byte[] key, byte[] iv)
{
AesEngine engine = new AesEngine(); // TODO: See if this +2 can be made static.
CbcBlockCipher blockCipher = new CbcBlockCipher(engine);
PaddedBufferedBlockCipher cipher = new PaddedBufferedBlockCipher(blockCipher, new Pkcs7Padding());
KeyParameter keyParam = new KeyParameter(key);
ParametersWithIV keyParamWithIv = new ParametersWithIV(keyParam, iv, 0, 16);
cipher.Init(false, keyParamWithIv);
byte[] decryptedSegmentData = new byte[cipher.GetOutputSize(encryptedSegmentData.Length)];
int length = cipher.ProcessBytes(encryptedSegmentData, decryptedSegmentData, 0);
length += cipher.DoFinal(decryptedSegmentData, length);
return(new ReadOnlyMemory <byte>(decryptedSegmentData, 0, length));
}
public async Task <ReadOnlyMemory <byte> > GetNextSegmentAsync()
{
if (_nextSegment >= _mediaPlaylist.MediaSegments.Count)
{
throw new Exception();
}
HlsMediaSegment segment = _mediaPlaylist.MediaSegments[_nextSegment];
if (segment.Key != null && segment.Key.Method != HlsKeyMethod.None && !_keyCache.ContainsKey(segment.Key.Uri))
{
byte[] keyData;
if (OnKeyFetch != null)
{
keyData = await OnKeyFetch(segment.Key);
}
else
{
keyData = await HttpClient.GetByteArrayAsync(segment.Key.Uri);
}
if (keyData.Length != 16)
{
throw new Exception($"Key length not 16 ({keyData.Length}).");
}
_keyCache[segment.Key.Uri] = keyData;
}
byte[] segmentBytes;
if (OnSegmentFetch != null)
{
segmentBytes = await OnSegmentFetch(segment);
}
else
{
HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, segment.Uri.ToString());
if (segment.ByteRange != null)
{
string[] rangeParts = segment.ByteRange.Split('@');
int len = Int32.Parse(rangeParts[0]), start = Int32.Parse(rangeParts[1]);
request.Headers.Range = new RangeHeaderValue(start, start + len - 1);
}
HttpResponseMessage response = await HttpClient.SendAsync(request);
segmentBytes = await response.Content.ReadAsByteArrayAsync();
}
ReadOnlyMemory <byte> segmentData = segmentBytes;
if (segment.Key != null && segment.Key.Method == HlsKeyMethod.Aes128)
{
byte[] iv = new byte[16];
if (segment.Key.KeyFormat == "identity")
{
Buffer.BlockCopy(BitConverter.GetBytes(segment.SequenceNumber).Reverse().ToArray(), 0, iv, 12, 4);
}
segmentData = DecryptSegmentData(segmentBytes, segment, _keyCache[segment.Key.Uri], iv);
}
_nextSegment++;
return(segmentData);
}
private void HandleMediaPlaylistLine(string line)
{
if (_isMasterPlaylist.HasValue && _isMasterPlaylist.Value)
{
throw new HlsException("Unexpected tag in media playlist.");
}
if (!_isMasterPlaylist.HasValue)
{
_isMasterPlaylist = false;
_mediaPlaylist = new HlsMediaPlaylist {
Version = _version, IsIndependentSegments = _isIndependentSegments, Start = _start
};
}
if (line[0] != '#')
{
// A URI line for a media segment should be the only case when this happens.
_mediaSegment.Uri = new Uri(_baseUri, line);
_mediaSegment = null;
return;
}
int firstColonIndex = line.IndexOf(':');
string tag = (firstColonIndex > -1 ? line.Substring(1, firstColonIndex - 1) : line.Substring(1));
string value = (firstColonIndex > -1 ? line.Substring(firstColonIndex + 1, line.Length - firstColonIndex - 1) : null);
switch (tag)
{
// Media segment tags.
case "EXTINF":
int commaIndex = value.IndexOf(',');
_mediaSegment = new HlsMediaSegment
{
SequenceNumber = _mediaPlaylist.MediaSequence + _mediaPlaylist._mediaSegments.Count,
Duration = Convert.ToSingle((commaIndex != -1 ? value.Substring(0, commaIndex) : value)),
Title = (commaIndex != -1 ? value.Substring(commaIndex + 1) : null),
Key = _mediaSegmentKey
};
_mediaPlaylist._mediaSegments.Add(_mediaSegment);
break;
case "EXT-X-BYTERANGE":
_mediaSegment.ByteRange = value;
break;
case "EXT-X-DISCONTINUITY":
_mediaSegment.HasDiscontinuityAfter = true;
break;
case "EXT-X-KEY":
IReadOnlyDictionary <string, string> keyAttributes = AttributeList.Parse(value);
_mediaSegmentKey = new HlsMediaSegmentKey
{
Method = AttributeValueUtils.ParseEnum <HlsKeyMethod>(keyAttributes["METHOD"]),
Uri = AttributeValueUtils.GetUriOrNull(keyAttributes, _baseUri, "URI"),
KeyFormat = (AttributeValueUtils.GetStringOrNull(keyAttributes, "KEYFORMAT") ?? "identity"),
};
break;
case "EXT-X-MAP":
break;
case "EXT-X-PROGRAM-DATE-TIME":
_mediaSegment.ProgramDateTime = value;
break;
case "EXT-X-ALLOW-CACHE":
break;
case "EXT-X-DATERANGE":
break;
// Media playlist tags.
case "EXT-X-TARGETDURATION":
_mediaPlaylist.TargetDuration = Convert.ToInt32(value);
break;
case "EXT-X-MEDIA-SEQUENCE":
_mediaPlaylist.MediaSequence = Convert.ToInt32(value);
break;
case "EXT-X-DISCONTINUITY-SEQUENCE":
_mediaPlaylist.DiscontinuitySequence = Convert.ToInt32(value);
break;
case "EXT-X-ENDLIST":
_mediaSegment = null;
HasEndlist = true;
break;
case "EXT-X-PLAYLIST-TYPE":
_mediaPlaylist.PlaylistType = value;
break;
case "EXT-X-I-FRAMES-ONLY":
_mediaPlaylist.IsIFramesOnly = true;
break;
}
}