datapath-windows: Compute checksums for VXLAN inner packets.

Windows does not support VXLAN hardware offloading.

Currently we do not compute IP/TCP/UDP checksums for the inner packet. This
patch computes the checksums mentioned above in regards with the enabled
settings.

i.e. if IP checksum offloading is enabled for the inner packet we compute it.
The same applies for TCP and UDP packets.

This patch also revizes the computation of ones' complement over different
memory blocks, in the case the lengths are odd.

Also per documentation:
https://msdn.microsoft.com/en-us/library/windows/hardware/ff568840%28v=vs.85%29.aspx
set the TCP flags FIN and PSH only for the last segment in the case LSO is
enabled.

Signed-off-by: Alin Gabriel Serdean <aserdean@cloudbasesolutions.com>
Acked-by: Sairam Venugopal <vsairam@vmware.com>
Acked-by: Sorin Vinturis <svinturis@cloudbasesolutions.com>
Signed-off-by: Ben Pfaff <blp@nicira.com>

1 files changed, 29 insertions, 8 deletions

diff --git a/datapath-windows/ovsext/BufferMgmt.c b/datapath-windows/ovsext/BufferMgmt.c
index 3550e20cc..9a1cf96b1 100644
--- a/datapath-windows/ovsext/BufferMgmt.c
+++ b/datapath-windows/ovsext/BufferMgmt.c
@@ -1116,7 +1116,8 @@ GetSegmentHeaderInfo(PNET_BUFFER_LIST nbl,
  * --------------------------------------------------------------------------
  */
 static NDIS_STATUS
-FixSegmentHeader(PNET_BUFFER nb, UINT16 segmentSize, UINT32 seqNumber)
+FixSegmentHeader(PNET_BUFFER nb, UINT16 segmentSize, UINT32 seqNumber,
+                 BOOLEAN lastPacket, UINT16 packetCounter)
 {
     EthHdr *dstEth;
     IPHdr *dstIP;
@@ -1141,18 +1142,34 @@ FixSegmentHeader(PNET_BUFFER nb, UINT16 segmentSize, UINT32 seqNumber)
     /* Fix IP length and checksum */
     ASSERT(dstIP->protocol == IPPROTO_TCP);
     dstIP->tot_len = htons(segmentSize + dstIP->ihl * 4 + TCP_HDR_LEN(dstTCP));
+    dstIP->id += packetCounter;
     dstIP->check = 0;
     dstIP->check = IPChecksum((UINT8 *)dstIP, dstIP->ihl * 4, 0);
 
     /* Fix TCP checksum */
     dstTCP->seq = htonl(seqNumber);
-    dstTCP->check =
-        IPPseudoChecksum((UINT32 *)&dstIP->saddr,
-                         (UINT32 *)&dstIP->daddr,
-                         IPPROTO_TCP, segmentSize + TCP_HDR_LEN(dstTCP));
+
+    /*
+     * Set the TCP FIN and PSH bit only for the last packet
+     * More information can be found under:
+     * https://msdn.microsoft.com/en-us/library/windows/hardware/ff568840%28v=vs.85%29.aspx
+     */
+    if (dstTCP->fin) {
+        dstTCP->fin = lastPacket;
+    }
+    if (dstTCP->psh) {
+        dstTCP->psh = lastPacket;
+    }
+
+    UINT16 csumLength = segmentSize + TCP_HDR_LEN(dstTCP);
+    dstTCP->check = IPPseudoChecksum(&dstIP->saddr,
+                                     &dstIP->daddr,
+                                     IPPROTO_TCP,
+                                     csumLength);
     dstTCP->check = CalculateChecksumNB(nb,
-            (UINT16)(NET_BUFFER_DATA_LENGTH(nb) - sizeof *dstEth - dstIP->ihl * 4),
-            sizeof *dstEth + dstIP->ihl * 4);
+                                        csumLength,
+                                        sizeof *dstEth + dstIP->ihl * 4);
+
     return STATUS_SUCCESS;
 }
 
@@ -1190,6 +1207,7 @@ OvsTcpSegmentNBL(PVOID ovsContext,
     NDIS_STATUS status;
     UINT16 segmentSize;
     ULONG copiedSize;
+    UINT16 packetCounter = 0;
 
     srcCtx = (POVS_BUFFER_CONTEXT)NET_BUFFER_LIST_CONTEXT_DATA_START(nbl);
     if (srcCtx == NULL || srcCtx->magic != OVS_CTX_MAGIC) {
@@ -1232,7 +1250,9 @@ OvsTcpSegmentNBL(PVOID ovsContext,
             goto nblcopy_error;
         }
 
-        status = FixSegmentHeader(newNb, segmentSize, seqNumber);
+        status = FixSegmentHeader(newNb, segmentSize, seqNumber,
+                                  NET_BUFFER_NEXT_NB(newNb) == NULL,
+                                  packetCounter);
         if (status != NDIS_STATUS_SUCCESS) {
             goto nblcopy_error;
         }
@@ -1241,6 +1261,7 @@ OvsTcpSegmentNBL(PVOID ovsContext,
         /* Move on to the next segment */
         size -= segmentSize;
         seqNumber += segmentSize;
+        packetCounter++;
     }
 
     status = OvsAllocateNBLContext(context, newNbl);