[Patch 1/2] MdeModulePke/Mtftp4Dxe: Add windowsize option support

[Jiaxin Wu <jiaxin.wu@intel.com>]

This patch is to support the tftp windowsize option that allows the
client and server to negotiate a window size of consecutive blocks to
send as an alternative for replacing the single-block lockstep schema.

Cc: Ye Ting <ting.ye@intel.com>
Cc: Fu Siyuan <siyuan.fu@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Wu Jiaxin <jiaxin.wu@intel.com>
---
 .../Universal/Network/Mtftp4Dxe/Mtftp4Impl.c       |  5 ++-
 .../Universal/Network/Mtftp4Dxe/Mtftp4Impl.h       | 11 +++++-
 .../Universal/Network/Mtftp4Dxe/Mtftp4Option.c     | 12 +++++-
 .../Universal/Network/Mtftp4Dxe/Mtftp4Option.h     |  6 ++-
 .../Universal/Network/Mtftp4Dxe/Mtftp4Rrq.c        | 44 ++++++++++++++++------
 .../Universal/Network/Mtftp4Dxe/Mtftp4Support.c    | 14 +++----
 .../Universal/Network/Mtftp4Dxe/Mtftp4Support.h    | 16 +-------
 .../Universal/Network/Mtftp4Dxe/Mtftp4Wrq.c        | 41 +++++++++++++++++---
 8 files changed, 104 insertions(+), 45 deletions(-)

diff --git a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Impl.c b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Impl.c
index a2583a4..9d4de42 100644
--- a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Impl.c
+++ b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Impl.c
@@ -1,10 +1,10 @@
 /** @file
   Interface routine for Mtftp4.
   
 (C) Copyright 2014 Hewlett-Packard Development Company, L.P.<BR>
-Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
 which accompanies this distribution.  The full text of the license may be found at
 http://opensource.org/licenses/bsd-license.php<BR>
 
@@ -78,10 +78,12 @@ Mtftp4CleanOperation (
   ZeroMem (&Instance->RequestOption, sizeof (MTFTP4_OPTION));
 
   Instance->Operation     = 0;
 
   Instance->BlkSize       = MTFTP4_DEFAULT_BLKSIZE;
+  Instance->SentAckNo     = 0;
+  Instance->WindowSize    = 1;
   Instance->LastBlock     = 0;
   Instance->ServerIp      = 0;
   Instance->ListeningPort = 0;
   Instance->ConnectedPort = 0;
   Instance->Gateway       = 0;
@@ -438,10 +440,11 @@ Mtftp4Start (
   // Set the operation parameters from the configuration or override data.
   //
   Config                  = &Instance->Config;
   Instance->Token         = Token;
   Instance->BlkSize       = MTFTP4_DEFAULT_BLKSIZE;
+  Instance->WindowSize    = MTFTP4_DEFAULT_WINDOWSIZE;
 
   CopyMem (&Instance->ServerIp, &Config->ServerIp, sizeof (IP4_ADDR));
   Instance->ServerIp      = NTOHL (Instance->ServerIp);
 
   Instance->ListeningPort = Config->InitialServerPort;
diff --git a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Impl.h b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Impl.h
index 527fd1d..733bc5d 100644
--- a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Impl.h
+++ b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Impl.h
@@ -6,12 +6,13 @@
   RFC1350 - THE TFTP PROTOCOL (REVISION 2)
   RFC2090 - TFTP Multicast Option
   RFC2347 - TFTP Option Extension
   RFC2348 - TFTP Blocksize Option
   RFC2349 - TFTP Timeout Interval and Transfer Size Options
+  RFC7440 - TFTP Windowsize Option
   
-Copyright (c) 2006 - 2012, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
 which accompanies this distribution.  The full text of the license may be found at
 http://opensource.org/licenses/bsd-license.php<BR>
 
@@ -54,10 +55,11 @@ typedef struct _MTFTP4_PROTOCOL MTFTP4_PROTOCOL;
 
 #define MTFTP4_DEFAULT_SERVER_PORT  69
 #define MTFTP4_DEFAULT_TIMEOUT      3
 #define MTFTP4_DEFAULT_RETRY        5
 #define MTFTP4_DEFAULT_BLKSIZE      512
+#define MTFTP4_DEFAULT_WINDOWSIZE   1
 #define MTFTP4_TIME_TO_GETMAP       5
 
 #define MTFTP4_STATE_UNCONFIGED     0
 #define MTFTP4_STATE_CONFIGED       1
 #define MTFTP4_STATE_DESTROY        2
@@ -119,10 +121,17 @@ struct _MTFTP4_PROTOCOL {
   UINT16                        BlkSize;
   UINT16                        LastBlock;
   LIST_ENTRY                    Blocks;
 
   //
+  // The last sent ack number. 
+  //
+  UINT16                        SentAckNo;
+
+  UINT16                        WindowSize;
+
+  //
   // The server's communication end point: IP and two ports. one for
   // initial request, one for its selected port.
   //
   IP4_ADDR                      ServerIp;
   UINT16                        ListeningPort;
diff --git a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Option.c b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Option.c
index e40561a..da6aee0 100644
--- a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Option.c
+++ b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Option.c
@@ -1,9 +1,9 @@
 /** @file
   Routines to process MTFTP4 options.
 
-Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
 which accompanies this distribution.  The full text of the license may be found at
 http://opensource.org/licenses/bsd-license.php<BR>
 
@@ -14,10 +14,11 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 
 #include "Mtftp4Impl.h"
 
 CHAR8 *mMtftp4SupportedOptions[MTFTP4_SUPPORTED_OPTIONS] = {
   "blksize",
+  "windowsize",
   "timeout",
   "tsize",
   "multicast"
 };
 
@@ -479,10 +480,19 @@ Mtftp4ParseOption (
         }
       }
 
       MtftpOption->Exist |= MTFTP4_MCAST_EXIST;
 
+    } else if (NetStringEqualNoCase (This->OptionStr, (UINT8 *) "windowsize")) {
+      Value = NetStringToU32 (This->ValueStr);
+
+      if (Value < 1) {
+        return EFI_INVALID_PARAMETER;
+      }
+
+      MtftpOption->WindowSize = (UINT16) Value;
+      MtftpOption->Exist |= MTFTP4_WINDOWSIZE_EXIST;
     } else if (Request) {
       //
       // Ignore the unsupported option if it is a reply, and return
       // EFI_UNSUPPORTED if it's a request according to the UEFI spec.
       //
diff --git a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Option.h b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Option.h
index b7fdbf2..b86d77d 100644
--- a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Option.h
+++ b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Option.h
@@ -1,9 +1,9 @@
 /** @file
   Routines to process MTFTP4 options.
   
-Copyright (c) 2006 - 2009, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
 which accompanies this distribution.  The full text of the license may be found at
 http://opensource.org/licenses/bsd-license.php<BR>
 
@@ -14,23 +14,25 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 
 
 #ifndef __EFI_MTFTP4_OPTION_H__
 #define __EFI_MTFTP4_OPTION_H__
 
-#define MTFTP4_SUPPORTED_OPTIONS  4
+#define MTFTP4_SUPPORTED_OPTIONS  5
 #define MTFTP4_OPCODE_LEN         2
 #define MTFTP4_ERRCODE_LEN        2
 #define MTFTP4_BLKNO_LEN          2
 #define MTFTP4_DATA_HEAD_LEN      4
 
 #define MTFTP4_BLKSIZE_EXIST      0x01
 #define MTFTP4_TIMEOUT_EXIST      0x02
 #define MTFTP4_TSIZE_EXIST        0x04
 #define MTFTP4_MCAST_EXIST        0x08
+#define MTFTP4_WINDOWSIZE_EXIST   0x10
 
 typedef struct {
   UINT16                    BlkSize;
+  UINT16                    WindowSize;
   UINT8                     Timeout;
   UINT32                    Tsize;
   IP4_ADDR                  McastIp;
   UINT16                    McastPort;
   BOOLEAN                   Master;
diff --git a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Rrq.c b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Rrq.c
index e983d79..5454d6c 100644
--- a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Rrq.c
+++ b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Rrq.c
@@ -1,10 +1,10 @@
 /** @file
   Routines to process Rrq (download).
   
 (C) Copyright 2014 Hewlett-Packard Development Company, L.P.<BR>
-Copyright (c) 2006 - 2014, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
 which accompanies this distribution.  The full text of the license may be found at
 http://opensource.org/licenses/bsd-license.php<BR>
 
@@ -97,10 +97,13 @@ Mtftp4RrqSendAck (
   IN UINT16                 BlkNo
   )
 {
   EFI_MTFTP4_PACKET         *Ack;
   NET_BUF                   *Packet;
+  EFI_STATUS                Status;
+
+  Status = EFI_SUCCESS;
 
   Packet = NetbufAlloc (sizeof (EFI_MTFTP4_ACK_HEADER));
   if (Packet == NULL) {
     return EFI_OUT_OF_RESOURCES;
   }
@@ -113,11 +116,16 @@ Mtftp4RrqSendAck (
   ASSERT (Ack != NULL);
 
   Ack->Ack.OpCode   = HTONS (EFI_MTFTP4_OPCODE_ACK);
   Ack->Ack.Block[0] = HTONS (BlkNo);
 
-  return Mtftp4SendPacket (Instance, Packet);
+  Status = Mtftp4SendPacket (Instance, Packet);
+  if (!EFI_ERROR (Status)) {
+    Instance->SentAckNo = BlkNo;
+  }
+
+  return Status;
 }
 
 
 /**
   Deliver the received data block to the user, which can be saved
@@ -156,11 +164,11 @@ Mtftp4RrqSaveBlock (
 
   //
   // This is the last block, save the block no
   //
   if (DataLen < Instance->BlkSize) {
-	Completed = TRUE;
+    Completed = TRUE;
     Instance->LastBlock = Block;
     Mtftp4SetLastBlockNum (&Instance->Blocks, Block);
   }
 
   //
@@ -255,23 +263,23 @@ Mtftp4RrqHandleData (
   EFI_STATUS                Status;
   UINT16                    BlockNum;
   INTN                      Expected;
 
   *Completed  = FALSE;
+  Status      = EFI_SUCCESS;
   BlockNum    = NTOHS (Packet->Data.Block);
   Expected    = Mtftp4GetNextBlockNum (&Instance->Blocks);
 
   ASSERT (Expected >= 0);
 
   //
-  // If we are active and received an unexpected packet, retransmit
-  // the last ACK then restart receiving. If we are passive, save
-  // the block.
+  // If we are active and received an unexpected packet, transmit
+  // the ACK for the block we received, then restart receiving the 
+  // expected one. If we are passive, save the block.
   //
   if (Instance->Master && (Expected != BlockNum)) {
-    Mtftp4Retransmit (Instance);
-    return EFI_SUCCESS;
+    return Mtftp4RrqSendAck (Instance,  (UINT16) (Expected - 1));
   }
 
   Status = Mtftp4RrqSaveBlock (Instance, Packet, Len);
 
   if (EFI_ERROR (Status)) {
@@ -307,14 +315,17 @@ Mtftp4RrqHandleData (
 
     } else {
       BlockNum = (UINT16) (Expected - 1);
     }
 
-    Mtftp4RrqSendAck (Instance, BlockNum);
+    if (Instance->WindowSize == (BlockNum - Instance->SentAckNo) || Expected < 0) {
+      Status = Mtftp4RrqSendAck (Instance, BlockNum);
+    }
+    
   }
 
-  return EFI_SUCCESS;
+  return Status;
 }
 
 
 /**
   Validate whether the options received in the server's OACK packet is valid.
@@ -347,14 +358,15 @@ Mtftp4RrqOackValid (
   if ((Reply->Exist &~Request->Exist) != 0) {
     return FALSE;
   }
 
   //
-  // Server can only specify a smaller block size to be used and
+  // Server can only specify a smaller block size and window size to be used and
   // return the timeout matches that requested.
   //
   if ((((Reply->Exist & MTFTP4_BLKSIZE_EXIST) != 0)&& (Reply->BlkSize > Request->BlkSize)) ||
+     (((Reply->Exist & MTFTP4_WINDOWSIZE_EXIST) != 0)&& (Reply->WindowSize > Request->WindowSize)) ||
       (((Reply->Exist & MTFTP4_TIMEOUT_EXIST) != 0) && (Reply->Timeout != Request->Timeout))) {
     return FALSE;
   }
 
   //
@@ -527,11 +539,11 @@ Mtftp4RrqHandleOack (
 
   if ((Reply.Exist & MTFTP4_MCAST_EXIST) != 0) {
 
     //
     // Save the multicast info. Always update the Master, only update the
-    // multicast IP address, block size, timeoute at the first time. If IP
+    // multicast IP address, block size, window size, timeoute at the first time. If IP
     // address is updated, create a UDP child to receive the multicast.
     //
     Instance->Master = Reply.Master;
 
     if (Instance->McastIp == 0) {
@@ -596,10 +608,14 @@ Mtftp4RrqHandleOack (
       // Update the parameters used.
       //
       if (Reply.BlkSize != 0) {
         Instance->BlkSize = Reply.BlkSize;
       }
+
+      if (Reply.WindowSize != 0) {
+        Instance->WindowSize = Reply.WindowSize;
+      }
       
       if (Reply.Timeout != 0) {
         Instance->Timeout = Reply.Timeout;
       }  
     }    
@@ -609,10 +625,14 @@ Mtftp4RrqHandleOack (
     
     if (Reply.BlkSize != 0) {
       Instance->BlkSize = Reply.BlkSize;
     }
 
+    if (Reply.WindowSize != 0) {
+      Instance->WindowSize = Reply.WindowSize;
+    }
+
     if (Reply.Timeout != 0) {
       Instance->Timeout = Reply.Timeout;
     }
   }
   
diff --git a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Support.c b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Support.c
index c625fda..83e6837 100644
--- a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Support.c
+++ b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Support.c
@@ -1,9 +1,9 @@
 /** @file
   Support routines for Mtftp.
   
-Copyright (c) 2006 - 2015, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
 which accompanies this distribution.  The full text of the license may be found at
 http://opensource.org/licenses/bsd-license.php<BR>
 
@@ -218,19 +218,19 @@ Mtftp4RemoveBlockNum (
       // transfers of unlimited size. There is no consensus, however, whether 
       // the counter should wrap around to zero or to one. Many implementations 
       // wrap to zero, because this is the simplest to implement. Here we choose 
       // this solution.
       //
-	  *TotalBlock  = Num;
-	  
+      *TotalBlock  = Num;
+
       if (Range->Round > 0) {
-	    *TotalBlock += Range->Bound +  MultU64x32 ((UINTN) (Range->Round -1), (UINT32) (Range->Bound + 1)) + 1;
-	  }
+        *TotalBlock += Range->Bound +  MultU64x32 ((UINTN) (Range->Round -1), (UINT32) (Range->Bound + 1)) + 1;
+      }
 
       if (Range->Start > Range->Bound) {
-	  	  Range->Start = 0;
-		  Range->Round ++;
+        Range->Start = 0;
+        Range->Round ++;
       }
 
       if ((Range->Start > Range->End) || Completed) {
         RemoveEntryList (&Range->Link);
         FreePool (Range);
diff --git a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Support.h b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Support.h
index 802e386..4b7e2b0 100644
--- a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Support.h
+++ b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Support.h
@@ -1,9 +1,9 @@
 /** @file
   Support routines for MTFTP.
   
-Copyright (c) 2006 - 2010, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
 which accompanies this distribution.  The full text of the license may be found at
 http://opensource.org/licenses/bsd-license.php<BR>
 
@@ -172,24 +172,10 @@ Mtftp4SendError (
   IN UINT16                 ErrCode,
   IN UINT8                  *ErrInfo
   );
 
 /**
-  Retransmit the last packet for the instance.
-
-  @param  Instance              The Mtftp instance
-
-  @retval EFI_SUCCESS           The last packet is retransmitted.
-  @retval Others                Failed to retransmit.
-
-**/
-EFI_STATUS
-Mtftp4Retransmit (
-  IN MTFTP4_PROTOCOL        *Instance
-  );
-
-/**
   The timer ticking function for the Mtftp service instance.
 
   @param  Event                 The ticking event
   @param  Context               The Mtftp service instance
 
diff --git a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Wrq.c b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Wrq.c
index e825714..ea4de93 100644
--- a/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Wrq.c
+++ b/MdeModulePkg/Universal/Network/Mtftp4Dxe/Mtftp4Wrq.c
@@ -1,9 +1,9 @@
 /** @file
   Routines to process Wrq (upload).
   
-Copyright (c) 2006 - 2014, Intel Corporation. All rights reserved.<BR>
+Copyright (c) 2006 - 2017, Intel Corporation. All rights reserved.<BR>
 This program and the accompanying materials
 are licensed and made available under the terms and conditions of the BSD License
 which accompanies this distribution.  The full text of the license may be found at
 http://opensource.org/licenses/bsd-license.php<BR>
 
@@ -19,21 +19,23 @@ WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
 /**
   Build then send a MTFTP data packet for the MTFTP upload session.
 
   @param  Instance              The MTFTP upload session.
   @param  BlockNum              The block number to send.
+  @param  Completed             Return whether the upload has finished.
 
   @retval EFI_OUT_OF_RESOURCES  Failed to build the packet.
   @retval EFI_ABORTED           The consumer of this child directs to abort the
                                 transmission by return an error through PacketNeeded.
   @retval EFI_SUCCESS           The data is sent.
 
 **/
 EFI_STATUS
 Mtftp4WrqSendBlock (
   IN OUT MTFTP4_PROTOCOL        *Instance,
-  IN     UINT16                 BlockNum
+  IN     UINT16                 BlockNum,
+     OUT BOOLEAN                *Completed
   )
 {
   EFI_MTFTP4_PACKET         *Packet;
   EFI_MTFTP4_TOKEN          *Token;
   NET_BUF                   *UdpPacket;
@@ -66,19 +68,23 @@ Mtftp4WrqSendBlock (
   if (Token->Buffer != NULL) {
     Start = MultU64x32 (BlockNum - 1, Instance->BlkSize);
 
     if (Token->BufferSize < Start + Instance->BlkSize) {
       DataLen             = (UINT16) (Token->BufferSize - Start);
+      if (DataLen == 0) {
+        *Completed = TRUE;
+        return EFI_SUCCESS;
+      }
+      
       Instance->LastBlock = BlockNum;
       Mtftp4SetLastBlockNum (&Instance->Blocks, BlockNum);
     }
 
     if (DataLen > 0) {
       NetbufAllocSpace (UdpPacket, DataLen, FALSE);
       CopyMem (Packet->Data.Data, (UINT8 *) Token->Buffer + Start, DataLen);
-    }
-
+    } 
   } else {
     //
     // Get data from PacketNeeded
     //
     DataBuf = NULL;
@@ -101,10 +107,15 @@ Mtftp4WrqSendBlock (
         );
 
       return EFI_ABORTED;
     }
 
+    if (DataLen == 0) {
+      *Completed = TRUE;
+      return EFI_SUCCESS;
+    }
+
     if (DataLen < Instance->BlkSize) {
       Instance->LastBlock = BlockNum;
       Mtftp4SetLastBlockNum (&Instance->Blocks, BlockNum);
     }
 
@@ -144,10 +155,15 @@ Mtftp4WrqHandleAck (
   )
 {
   UINT16                    AckNum;
   INTN                      Expected;
   UINT64                    TotalBlock;
+
+  INTN                      Index;
+  EFI_STATUS                Status;
+
+  Status      = EFI_SUCCESS;
  
   *Completed  = FALSE;
   AckNum      = NTOHS (Packet->Ack.Block[0]);
   Expected    = Mtftp4GetNextBlockNum (&Instance->Blocks);
 
@@ -191,11 +207,19 @@ Mtftp4WrqHandleAck (
 
       return EFI_TFTP_ERROR;
     }
   }
 
-  return Mtftp4WrqSendBlock (Instance, (UINT16) Expected);
+  for (Index = 0; Index < Instance->WindowSize; Index++) {
+    if (!EFI_ERROR (Status) && !(*Completed)) {
+      Status = Mtftp4WrqSendBlock (Instance, (UINT16) (Expected + Index), Completed);
+    } else {
+      break;
+    }
+  }
+
+  return Status;
 }
 
 
 /**
   Check whether the received OACK is valid. 
@@ -225,14 +249,15 @@ Mtftp4WrqOackValid (
   if ((Reply->Exist & ~Request->Exist) != 0) {
     return FALSE;
   }
 
   //
-  // Server can only specify a smaller block size to be used and
+  // Server can only specify a smaller block size and window size to be used and
   // return the timeout matches that requested.
   //
   if ((((Reply->Exist & MTFTP4_BLKSIZE_EXIST) != 0) && (Reply->BlkSize > Request->BlkSize)) ||
+     (((Reply->Exist & MTFTP4_WINDOWSIZE_EXIST) != 0)&& (Reply->WindowSize > Request->WindowSize)) ||
       (((Reply->Exist & MTFTP4_TIMEOUT_EXIST) != 0) && (Reply->Timeout != Request->Timeout))) {
     return FALSE;
   }
 
   return TRUE;
@@ -302,10 +327,14 @@ Mtftp4WrqHandleOack (
 
   if (Reply.BlkSize != 0) {
     Instance->BlkSize = Reply.BlkSize;
   }
 
+  if (Reply.WindowSize != 0) {
+    Instance->WindowSize = Reply.WindowSize;
+  }
+
   if (Reply.Timeout != 0) {
     Instance->Timeout = Reply.Timeout;
   }
 
   //
-- 
1.9.5.msysgit.1