/// <summary>
/// Request a part of the encrypted file from the server.
///
/// The data should be decrypted using AES key in CTR mode
/// with AES key provided and a static IV, incremented for
/// each 16 byte data processed.
/// </summary>
public void SendSubstreamRequest(IChannelListener listener, Sharpotify.Media.File file, int offset, int length)
{
/* Create channel and buffer. */
Channel.Channel channel = new Channel.Channel("Substream-Channel", Channel.ChannelType.TYPE_SUBSTREAM, listener);
ByteBuffer buffer = ByteBuffer.Allocate(2 + 2 + 2 + 2 + 2 + 2 + 2 + 4 + 20 + 4 + 4);
/* Append channel id. */
buffer.PutShort((short)channel.Id);
/* Unknown 10 bytes. */
buffer.PutShort((short)0x0800);
buffer.PutShort((short)0x0000);
buffer.PutShort((short)0x0000);
buffer.PutShort((short)0x0000);
buffer.PutShort((short)0x0000);
buffer.PutShort((short)0x4e20);
/* Unknown (static value) */
buffer.PutInt(200 * 1000);
/* 20 bytes file id. */
buffer.Put(Hex.ToBytes(file.Id));
if (offset % 4096 != 0 || length % 4096 != 0 || length == 0)
{
throw new ArgumentException("Offset and length need to be a multiple of 4096.");
}
offset >>= 2;
length >>= 2;
/* Append offset and length. */
buffer.PutInt(offset);
buffer.PutInt(offset + length);
buffer.Flip();
/* Register channel. */
Channel.Channel.Register(channel);
/* Send packet. */
this.SendPacket(Command.COMMAND_GETSUBSTREAM, buffer);
}
/// <summary>
/// Request AES key for a track.
/// </summary>
public void SendAesKeyRequest(IChannelListener listener, Track track, Sharpotify.Media.File file)
{
/* Create channel and buffer. */
Channel.Channel channel = new Channel.Channel("AES-Key-Channel", Channel.ChannelType.TYPE_AESKEY, listener);
ByteBuffer buffer = ByteBuffer.Allocate(20 + 16 + 2 + 2 + 2);
/* Request the AES key for this file by sending the file id and track id. */
buffer.Put(Hex.ToBytes(file.Id)); /* 20 bytes */
buffer.Put(Hex.ToBytes(track.Id)); /* 16 bytes */
buffer.PutShort((short)0x0000);
buffer.PutShort((short)channel.Id);
buffer.PutShort((short)0x0000);
buffer.Flip();
/* Register channel. */
Channel.Channel.Register(channel);
/* Send packet. */
this.SendPacket(Command.COMMAND_REQKEY, buffer);
}