private static Message GetBlock(Message msg, Int32 num, Int32 szx)
{
Int32 blockSize = BlockOption.DecodeSZX(szx);
Int32 payloadOffset = num * blockSize;
Int32 payloadLeft = msg.PayloadSize - payloadOffset;
if (payloadLeft > 0)
{
Message block = null;
if (msg is Request)
{
block = new Request(msg.Code, msg.IsConfirmable);
}
else
{
block = new Response(msg.Code);
if (num == 0 && msg.Type == MessageType.CON)
{
block.Type = MessageType.CON;
}
else
{
block.Type = msg.IsNonConfirmable ? MessageType.NON : MessageType.ACK;
}
block.ID = msg.ID;
}
block.PeerAddress = msg.PeerAddress;
block.Token = msg.Token;
// use same options
foreach (Option opt in msg.GetOptions())
{
block.AddOption(opt);
}
// calculate 'more' bit
Boolean m = blockSize < payloadLeft;
// limit block size to size of payload left
if (!m)
{
blockSize = payloadLeft;
}
// copy payload block
Byte[] blockPayload = new Byte[blockSize];
Array.Copy(msg.Payload, payloadOffset, blockPayload, 0, blockSize);
block.Payload = blockPayload;
Option blockOpt = null;
if (msg is Request)
{
blockOpt = new BlockOption(OptionType.Block1, num, szx, m);
}
else
{
blockOpt = new BlockOption(OptionType.Block2, num, szx, m);
}
block.SetOption(blockOpt);
return(block);
}
else
{
return(null);
}
}
/// <summary>
/// Sending a message.
/// </summary>
/// <param name="msg">The message to be sent</param>
protected override void DoSendMessage(Message msg)
{
int sendSZX = _defaultSZX;
int sendNUM = 0;
// block negotiation
if ((msg is Response) && ((Response)msg).Request != null)
{
BlockOption buddyBlock = (BlockOption)((Response)msg).Request.GetFirstOption(OptionType.Block2);
if (buddyBlock != null)
{
if (buddyBlock.SZX < sendSZX)
{
sendSZX = buddyBlock.SZX;
}
sendNUM = buddyBlock.NUM;
}
}
// check if transfer needs to be split up
if (msg.PayloadSize > BlockOption.DecodeSZX(sendSZX))
{
// split message up using block1 for requests and block2 for responses
Message msgBlock = GetBlock(msg, sendNUM, sendSZX);
if (msgBlock != null)
{
BlockOption block1 = (BlockOption)msgBlock.GetFirstOption(OptionType.Block1);
BlockOption block2 = (BlockOption)msgBlock.GetFirstOption(OptionType.Block2);
// only cache if blocks remaining for request
if ((block1 != null && block1.M) || (block2 != null && block2.M))
{
msg.SetOption(block1);
msg.SetOption(block2);
TransferContext transfer = new TransferContext(msg);
_outgoing[msg.SequenceKey] = transfer;
if (log.IsDebugEnabled)
{
log.Debug(String.Format("TransferLayer - Caching blockwise transfer for NUM {0} : {1}", sendNUM, msg.SequenceKey));
}
}
else
{
// must be block2 by client
if (log.IsDebugEnabled)
{
log.Debug(String.Format("TransferLayer - Answering block request without caching: {0} | {1}", msg.SequenceKey, block2));
}
}
// send block and wait for reply
SendMessageOverLowerLayer(msgBlock);
}
else
{
// must be block2 by client
if (log.IsInfoEnabled)
{
log.Info(String.Format("TransferLayer - Rejecting initial out-of-scope request: {0} | NUM: {1}, SZX: {2} ({3} bytes), M: n/a, {4} bytes available",
msg.SequenceKey, sendNUM, sendSZX, BlockOption.DecodeSZX(sendSZX), msg.PayloadSize));
}
HandleOutOfScopeError(msg.NewReply(true));
}
}
else
{
// send complete message
SendMessageOverLowerLayer(msg);
}
}
/// <summary>
/// Initializes a transfer layer.
/// </summary>
/// <param name="defaultBlockSize">The default block size used for block-wise transfers or -1 to disable outgoing block-wise transfers</param>
public TransferLayer(Int32 defaultBlockSize)
{
if (defaultBlockSize == 0)
{
defaultBlockSize = CoapConstants.DefaultBlockSize;
}
if (defaultBlockSize > 0)
{
_defaultSZX = BlockOption.EncodeSZX(defaultBlockSize);
if (!BlockOption.ValidSZX(_defaultSZX))
{
_defaultSZX = defaultBlockSize > 1024 ? 6 : BlockOption.EncodeSZX(defaultBlockSize & 0x07f0);
if (log.IsWarnEnabled)
{
log.Warn(String.Format("TransferLayer - Unsupported block size {0}, using {1} instead", defaultBlockSize, BlockOption.DecodeSZX(_defaultSZX)));
}
}
}
else
{
// disable outgoing blockwise transfers
_defaultSZX = -1;
}
}