/* Copyright (C) 2012-2016 Tal Aloni <tal.aloni.il@gmail.com>. All rights reserved.
*
* You can redistribute this program and/or modify it under the terms of
* the GNU Lesser Public License as published by the Free Software Foundation,
* either version 3 of the License, or (at your option) any later version.
*/
using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Runtime.InteropServices;
using DiskAccessLibrary;
using SCSI;
using Utilities;
namespace ISCSI.Server
{
internal class TargetResponseHelper
{
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
if (session.IsPrecedingCommandPending(transfer.Command.CmdSN))
{
session.DelayedCommands.Add(transfer.Command);
}
else
{
commandsToExecute.Add(transfer.Command);
connection.RemoveTransfer(request.TargetTransferTag);
session.CommandsInTransfer.Remove(transfer.Command.CmdSN);
// 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 + request.DataSegmentLength; // 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;
}
}
internal static List<ISCSIPDU> PrepareSCSICommandResponse(SCSICommandPDU command, SCSIStatusCodeName status, byte[] scsiResponse, ConnectionParameters connection)
{
List<ISCSIPDU> responseList = new List<ISCSIPDU>();
if (!command.Read || status != SCSIStatusCodeName.Good)
{
// RFC 3720: if the command is completed with an error, then the response and sense data MUST be sent in a SCSI Response PDU
SCSIResponsePDU response = new SCSIResponsePDU();
response.InitiatorTaskTag = command.InitiatorTaskTag;
response.Status = status;
response.Data = scsiResponse;
if (command.Read)
{
EnforceExpectedDataTransferLength(response, command.ExpectedDataTransferLength);
}
responseList.Add(response);
}
else if (scsiResponse.Length <= connection.InitiatorMaxRecvDataSegmentLength)
{
SCSIDataInPDU response = new SCSIDataInPDU();
response.InitiatorTaskTag = command.InitiatorTaskTag;
response.Status = status;
response.StatusPresent = true;
response.Final = true;
response.Data = scsiResponse;
EnforceExpectedDataTransferLength(response, command.ExpectedDataTransferLength);
responseList.Add(response);
}
else // we have to split the response to multiple Data-In PDUs
{
int bytesLeftToSend = scsiResponse.Length;
uint dataSN = 0;
while (bytesLeftToSend > 0)
{
int dataSegmentLength = Math.Min(connection.InitiatorMaxRecvDataSegmentLength, bytesLeftToSend);
int dataOffset = scsiResponse.Length - bytesLeftToSend;
SCSIDataInPDU response = new SCSIDataInPDU();
response.InitiatorTaskTag = command.InitiatorTaskTag;
if (bytesLeftToSend == dataSegmentLength)
{
// last Data-In PDU
response.Status = status;
response.StatusPresent = true;
response.Final = true;
}
response.BufferOffset = (uint)dataOffset;
response.DataSN = dataSN;
dataSN++;
response.Data = new byte[dataSegmentLength];
Array.Copy(scsiResponse, dataOffset, response.Data, 0, dataSegmentLength);
responseList.Add(response);
bytesLeftToSend -= dataSegmentLength;
}
}
return responseList;
}
public static void EnforceExpectedDataTransferLength(SCSIResponsePDU response, uint expectedDataTransferLength)
{
if (response.Data.Length > expectedDataTransferLength)
{
response.ResidualOverflow = true;
response.ResidualCount = (uint)(response.Data.Length - expectedDataTransferLength);
response.Data = ByteReader.ReadBytes(response.Data, 0, (int)expectedDataTransferLength);
}
else if (response.Data.Length < expectedDataTransferLength)
{
response.ResidualUnderflow = true;
response.ResidualCount = (uint)(expectedDataTransferLength - response.Data.Length);
}
}
public static void EnforceExpectedDataTransferLength(SCSIDataInPDU response, uint expectedDataTransferLength)
{
if (response.Data.Length > expectedDataTransferLength)
{
response.ResidualOverflow = true;
response.ResidualCount = (uint)(response.Data.Length - expectedDataTransferLength);
response.Data = ByteReader.ReadBytes(response.Data, 0, (int)expectedDataTransferLength);
}
else if (response.Data.Length < expectedDataTransferLength)
{
response.ResidualUnderflow = true;
response.ResidualCount = (uint)(expectedDataTransferLength - response.Data.Length);
}
}
}
}