internal static List <ReadyToTransferPDU> GetReadyToTransferPDUs(SCSICommandPDU command, ConnectionParameters connection, out List <SCSICommandPDU> commandsToExecute)
{
// We return either SCSIResponsePDU or List<SCSIDataInPDU>
List <ReadyToTransferPDU> responseList = new List <ReadyToTransferPDU>();
commandsToExecute = new List <SCSICommandPDU>();
ISCSISession session = connection.Session;
if (command.Write && command.DataSegmentLength < command.ExpectedDataTransferLength)
{
uint transferTag = session.GetNextTransferTag();
// Create buffer for next segments (we only execute the command after receiving all of its data)
Array.Resize <byte>(ref command.Data, (int)command.ExpectedDataTransferLength);
// Send R2Ts:
uint bytesLeft = command.ExpectedDataTransferLength - command.DataSegmentLength;
uint nextOffset = command.DataSegmentLength;
if (!session.InitialR2T)
{
uint firstDataPDULength = Math.Min((uint)session.FirstBurstLength, command.ExpectedDataTransferLength) - command.DataSegmentLength;
bytesLeft -= firstDataPDULength;
nextOffset += firstDataPDULength;
}
int totalR2Ts = (int)Math.Ceiling((double)bytesLeft / connection.TargetMaxRecvDataSegmentLength);
int outgoingR2Ts = Math.Min(session.MaxOutstandingR2T, totalR2Ts);
for (uint index = 0; index < outgoingR2Ts; index++)
{
ReadyToTransferPDU response = new ReadyToTransferPDU();
response.InitiatorTaskTag = command.InitiatorTaskTag;
response.R2TSN = index; // R2Ts are sequenced per command and must start with 0 for each new command;
response.TargetTransferTag = transferTag;
response.BufferOffset = nextOffset;
response.DesiredDataTransferLength = Math.Min((uint)connection.TargetMaxRecvDataSegmentLength, command.ExpectedDataTransferLength - response.BufferOffset);
responseList.Add(response);
nextOffset += (uint)connection.TargetMaxRecvDataSegmentLength;
}
connection.AddTransfer(transferTag, command, (uint)outgoingR2Ts, nextOffset, (uint)totalR2Ts);
session.CommandsInTransfer.Add(command.CmdSN);
return(responseList);
}
if (session.IsPrecedingCommandPending(command.CmdSN))
{
session.DelayedCommands.Add(command);
}
else
{
commandsToExecute.Add(command);
}
return(responseList);
}
internal static List <ReadyToTransferPDU> GetReadyToTransferPDUs(SCSIDataOutPDU request, ConnectionParameters connection, out List <SCSICommandPDU> commandsToExecute)
{
List <ReadyToTransferPDU> responseList = new List <ReadyToTransferPDU>();
commandsToExecute = new List <SCSICommandPDU>();
ISCSISession session = connection.Session;
TransferEntry transfer = connection.GetTransferEntry(request.TargetTransferTag);
if (transfer == null)
{
throw new InvalidTargetTransferTagException(request.TargetTransferTag);
}
uint offset = request.BufferOffset;
uint totalLength = (uint)transfer.Command.ExpectedDataTransferLength;
// Store segment (we only execute the command after receiving all of its data)
Array.Copy(request.Data, 0, transfer.Command.Data, offset, request.DataSegmentLength);
if (offset + request.DataSegmentLength == totalLength)
{
// Last Data-out PDU
connection.RemoveTransfer(request.TargetTransferTag);
session.CommandsInTransfer.Remove(transfer.Command.CmdSN);
if (session.IsPrecedingCommandPending(transfer.Command.CmdSN))
{
session.DelayedCommands.Add(transfer.Command);
}
else
{
commandsToExecute.Add(transfer.Command);
// Check if delayed commands are ready to be executed
List <SCSICommandPDU> pendingCommands = session.GetDelayedCommandsReadyForExecution();
foreach (SCSICommandPDU pendingCommand in pendingCommands)
{
commandsToExecute.Add(pendingCommand);
}
}
return(responseList);
}
else
{
// RFC 3720: An R2T MAY be answered with one or more SCSI Data-Out PDUs with a matching Target Transfer Tag.
// If an R2T is answered with a single Data-Out PDU, the Buffer Offset in the Data PDU MUST be the same as the one specified
// by the R2T, and the data length of the Data PDU MUST be the same as the Desired Data Transfer Length specified in the R2T.
// If the R2T is answered with a sequence of Data PDUs, the Buffer Offset and Length MUST be within
// the range of those specified by R2T, and the last PDU MUST have the F bit set to 1.
// An R2T is considered outstanding until the last data PDU is transferred.
if (request.Final)
{
// We already sent as many R2T as we could, we will only send R2T if any remained.
if (transfer.NextR2TSN < transfer.TotalR2Ts)
{
// Send R2T
ReadyToTransferPDU response = new ReadyToTransferPDU();
response.InitiatorTaskTag = request.InitiatorTaskTag;
response.TargetTransferTag = request.TargetTransferTag;
response.R2TSN = transfer.NextR2TSN;
response.BufferOffset = transfer.NextOffset; // where we left off
response.DesiredDataTransferLength = Math.Min((uint)connection.TargetMaxRecvDataSegmentLength, totalLength - response.BufferOffset);
responseList.Add(response);
transfer.NextR2TSN++;
transfer.NextOffset += (uint)connection.TargetMaxRecvDataSegmentLength;
}
}
return(responseList);
}
}