gso: fix the header parser to read only

Previously, header parser sets the tcp/udp checksum to 0.
It should be read only function for vlib_buffer_t.

Type: fix

Change-Id: I9c3398372f22998da3df188f0b7db13748303068
Signed-off-by: Mohsin Kazmi <sykazmi@cisco.com>

3 files changed, 44 insertions, 6 deletions

diff --git a/src/vnet/devices/virtio/device.c b/src/vnet/devices/virtio/device.c
index 856e5f275e3..76f85588ec8 100644
--- a/src/vnet/devices/virtio/device.c
+++ b/src/vnet/devices/virtio/device.c
@@ -158,9 +158,21 @@ set_checksum_offsets (vlib_main_t * vm, virtio_if_t * vif, vlib_buffer_t * b,
       hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
       hdr->csum_start = gho.l4_hdr_offset;	// 0x22;
       if (b->flags & VNET_BUFFER_F_OFFLOAD_TCP_CKSUM)
-	hdr->csum_offset = STRUCT_OFFSET_OF (tcp_header_t, checksum);
+	{
+	  tcp_header_t *tcp =
+	    (tcp_header_t *) (vlib_buffer_get_current (b) +
+			      gho.l4_hdr_offset);
+	  tcp->checksum = 0;
+	  hdr->csum_offset = STRUCT_OFFSET_OF (tcp_header_t, checksum);
+	}
       else if (b->flags & VNET_BUFFER_F_OFFLOAD_UDP_CKSUM)
-	hdr->csum_offset = STRUCT_OFFSET_OF (udp_header_t, checksum);
+	{
+	  udp_header_t *udp =
+	    (udp_header_t *) (vlib_buffer_get_current (b) +
+			      gho.l4_hdr_offset);
+	  udp->checksum = 0;
+	  hdr->csum_offset = STRUCT_OFFSET_OF (udp_header_t, checksum);
+	}
 
       /*
        * virtio devices do not support IP4 checksum offload. So driver takes care
@@ -177,9 +189,21 @@ set_checksum_offsets (vlib_main_t * vm, virtio_if_t * vif, vlib_buffer_t * b,
       hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
       hdr->csum_start = gho.l4_hdr_offset;	// 0x36;
       if (b->flags & VNET_BUFFER_F_OFFLOAD_TCP_CKSUM)
-	hdr->csum_offset = STRUCT_OFFSET_OF (tcp_header_t, checksum);
+	{
+	  tcp_header_t *tcp =
+	    (tcp_header_t *) (vlib_buffer_get_current (b) +
+			      gho.l4_hdr_offset);
+	  tcp->checksum = 0;
+	  hdr->csum_offset = STRUCT_OFFSET_OF (tcp_header_t, checksum);
+	}
       else if (b->flags & VNET_BUFFER_F_OFFLOAD_UDP_CKSUM)
-	hdr->csum_offset = STRUCT_OFFSET_OF (udp_header_t, checksum);
+	{
+	  udp_header_t *udp =
+	    (udp_header_t *) (vlib_buffer_get_current (b) +
+			      gho.l4_hdr_offset);
+	  udp->checksum = 0;
+	  hdr->csum_offset = STRUCT_OFFSET_OF (udp_header_t, checksum);
+	}
     }
 }
 
@@ -202,10 +226,15 @@ add_buffer_to_slot (vlib_main_t * vm, virtio_if_t * vif,
       if (b->flags & VNET_BUFFER_F_IS_IP4)
 	{
 	  ip4_header_t *ip4;
+	  tcp_header_t *tcp;
 	  gso_header_offset_t gho = vnet_gso_header_offset_parser (b, 0);
 	  hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
 	  hdr->gso_size = vnet_buffer2 (b)->gso_size;
 	  hdr->hdr_len = gho.l4_hdr_offset + gho.l4_hdr_sz;
+	  tcp =
+	    (tcp_header_t *) (vlib_buffer_get_current (b) +
+			      gho.l4_hdr_offset);
+	  tcp->checksum = 0;
 	  hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 	  hdr->csum_start = gho.l4_hdr_offset;	// 0x22;
 	  hdr->csum_offset = STRUCT_OFFSET_OF (tcp_header_t, checksum);
@@ -221,11 +250,16 @@ add_buffer_to_slot (vlib_main_t * vm, virtio_if_t * vif,
 	}
       else if (b->flags & VNET_BUFFER_F_IS_IP6)
 	{
+	  tcp_header_t *tcp;
 	  gso_header_offset_t gho = vnet_gso_header_offset_parser (b, 1);
 	  hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
 	  hdr->gso_size = vnet_buffer2 (b)->gso_size;
 	  hdr->hdr_len = gho.l4_hdr_offset + gho.l4_hdr_sz;
 	  hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
+	  tcp =
+	    (tcp_header_t *) (vlib_buffer_get_current (b) +
+			      gho.l4_hdr_offset);
+	  tcp->checksum = 0;
 	  hdr->csum_start = gho.l4_hdr_offset;	// 0x36;
 	  hdr->csum_offset = STRUCT_OFFSET_OF (tcp_header_t, checksum);
 	}
diff --git a/src/vnet/devices/virtio/vhost_user_output.c b/src/vnet/devices/virtio/vhost_user_output.c
index c1b8fe1a92a..e1f42ce1559 100644
--- a/src/vnet/devices/virtio/vhost_user_output.c
+++ b/src/vnet/devices/virtio/vhost_user_output.c
@@ -253,12 +253,18 @@ vhost_user_handle_tx_offload (vhost_user_intf_t * vui, vlib_buffer_t * b,
       hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
       hdr->csum_start = gho.l4_hdr_offset;
       hdr->csum_offset = offsetof (udp_header_t, checksum);
+      udp_header_t *udp =
+	(udp_header_t *) (vlib_buffer_get_current (b) + gho.l4_hdr_offset);
+      udp->checksum = 0;
     }
   else if (b->flags & VNET_BUFFER_F_OFFLOAD_TCP_CKSUM)
     {
       hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
       hdr->csum_start = gho.l4_hdr_offset;
       hdr->csum_offset = offsetof (tcp_header_t, checksum);
+      tcp_header_t *tcp =
+	(tcp_header_t *) (vlib_buffer_get_current (b) + gho.l4_hdr_offset);
+      tcp->checksum = 0;
     }
 
   /* GSO offload */
diff --git a/src/vnet/gso/gso.h b/src/vnet/gso/gso.h
index 79869c2644b..0e46c36f74d 100644
--- a/src/vnet/gso/gso.h
+++ b/src/vnet/gso/gso.h
@@ -106,14 +106,12 @@ vnet_gso_header_offset_parser (vlib_buffer_t * b0, int is_ip6)
       tcp_header_t *tcp = (tcp_header_t *) (vlib_buffer_get_current (b0) +
 					    gho.l4_hdr_offset);
       l4_hdr_sz = tcp_header_bytes (tcp);
-      tcp->checksum = 0;
     }
   else if (l4_proto == IP_PROTOCOL_UDP)
     {
       udp_header_t *udp = (udp_header_t *) (vlib_buffer_get_current (b0) +
 					    gho.l4_hdr_offset);
       l4_hdr_sz = sizeof (*udp);
-      udp->checksum = 0;
     }
 
   if (b0->flags & (VNET_BUFFER_F_IS_IP4 | VNET_BUFFER_F_IS_IP6))