void HandleKey(SubStreamSegment segment, IEnumerable<ExtKeyTagInstance> extKeys, CancellationToken cancellationToken)
{
var keys = extKeys.ToArray();
if (keys.Length < 1)
return;
string keyUri = null;
byte[] iv = null;
foreach (var key in keys)
{
var method = key.AttributeObject(ExtKeySupport.AttrMethod);
if (string.Equals(MethodNone, method, StringComparison.OrdinalIgnoreCase))
{
keyUri = null;
continue;
}
if (!string.Equals(MethodAes, method, StringComparison.OrdinalIgnoreCase))
{
if (string.Equals(MethodSampleAes, method, StringComparison.OrdinalIgnoreCase))
throw new NotImplementedException("Method SAMPLE-AES decryption is not implemented");
throw new NotSupportedException("Unknown decryption method type: " + method);
}
var newUri = key.AttributeObject(ExtKeySupport.AttrUri);
if (null != newUri)
keyUri = newUri;
var newIv = key.AttributeObject(ExtKeySupport.AttrIv);
if (null != newIv)
iv = newIv;
}
if (null == keyUri)
return;
if (null == iv)
{
iv = new byte[16];
var ms = segment.MediaSequence ?? (_segmentIndex - 1);
iv[15] = (byte)(ms & 0xff);
iv[14] = (byte)((ms >> 8) & 0xff);
iv[13] = (byte)((ms >> 16) & 0xff);
iv[12] = (byte)((ms >> 24) & 0xff);
}
var filter = segment.AsyncStreamFilter;
var uri = _parser.ResolveUrl(keyUri);
segment.AsyncStreamFilter =
async (stream, ct) =>
{
if (null != filter)
stream = await filter(stream, ct).ConfigureAwait(false);
byte[] key;
if (!_keyCache.TryGetValue(uri, out key))
{
key = await LoadKeyAsync(uri, cancellationToken).ConfigureAwait(false);
if (16 != key.Length)
throw new FormatException("AES-128 key length mismatch: " + key.Length);
_keyCache[uri] = key;
}
Debug.WriteLine("Segment AES-128: key {0} iv {1}", BitConverter.ToString(key), BitConverter.ToString(iv));
return _platformServices.Aes128DecryptionFilter(stream, key, iv);
};
}
ISegment CreateStreamSegment(M3U8Parser.M3U8Uri uri, CancellationToken cancellationToken)
{
var url = _parser.ResolveUrl(uri.Uri);
var segment = new SubStreamSegment(url, _parser.BaseUrl);
if (_mediaSequence.HasValue)
segment.MediaSequence = _mediaSequence + _segmentIndex;
++_segmentIndex;
var tags = uri.Tags;
if (null == tags || 0 == tags.Length)
return segment;
var info = M3U8Tags.ExtXInf.Find(tags);
if (null != info)
segment.Duration = TimeSpan.FromSeconds((double)info.Duration);
var byteRange = M3U8Tags.ExtXByteRange.Find(tags);
if (null != byteRange)
HandleByteRange(segment, byteRange);
var extKeys = M3U8Tags.ExtXKey.FindAll(tags);
if (null != extKeys)
HandleKey(segment, extKeys, cancellationToken);
return segment;
}
void HandleByteRange(SubStreamSegment segment, ByterangeTagInstance byteRange)
{
if (byteRange.Offset.HasValue)
{
segment.Offset = byteRange.Offset.Value;
_byteRangeOffset = byteRange.Offset.Value;
}
else
segment.Offset = _byteRangeOffset;
segment.Length = byteRange.Length;
_byteRangeOffset += byteRange.Length;
}
