gso: add protocol header parser

Type: feature

Change-Id: I7c6be2b96d19f82be237f6159944f3164ea512d0
Signed-off-by: Mohsin Kazmi <sykazmi@cisco.com>

6 files changed, 149 insertions, 90 deletions

diff --git a/src/vnet/devices/virtio/node.c b/src/vnet/devices/virtio/node.c
index ec28fbb5e08..fc2317ecc69 100644
--- a/src/vnet/devices/virtio/node.c
+++ b/src/vnet/devices/virtio/node.c
@@ -145,11 +145,11 @@ static_always_inline void
 fill_gso_buffer_flags (vlib_buffer_t * b0, struct virtio_net_hdr_v1 *hdr)
 {
   u8 l4_proto = 0;
-  u8 l4_hdr_sz = 0;
   if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM)
 
     {
-      ethernet_header_t *eh = (ethernet_header_t *) b0->data;
+      ethernet_header_t *eh =
+	(ethernet_header_t *) vlib_buffer_get_current (b0);
       u16 ethertype = clib_net_to_host_u16 (eh->type);
       u16 l2hdr_sz = sizeof (ethernet_header_t);
 
@@ -167,47 +167,29 @@ fill_gso_buffer_flags (vlib_buffer_t * b0, struct virtio_net_hdr_v1 *hdr)
 	    }
 	}
 
-      vnet_buffer (b0)->l2_hdr_offset = 0;
-      vnet_buffer (b0)->l3_hdr_offset = l2hdr_sz;
       if (PREDICT_TRUE (ethertype == ETHERNET_TYPE_IP4))
 	{
-	  ip4_header_t *ip4 = (ip4_header_t *) (b0->data + l2hdr_sz);
-	  vnet_buffer (b0)->l4_hdr_offset = l2hdr_sz + ip4_header_bytes (ip4);
+	  ip4_header_t *ip4 =
+	    (ip4_header_t *) (vlib_buffer_get_current (b0) + l2hdr_sz);
 	  l4_proto = ip4->protocol;
 	  b0->flags |=
-	    (VNET_BUFFER_F_IS_IP4 | VNET_BUFFER_F_L2_HDR_OFFSET_VALID
-	     | VNET_BUFFER_F_L3_HDR_OFFSET_VALID |
-	     VNET_BUFFER_F_L4_HDR_OFFSET_VALID);
-	  b0->flags |= VNET_BUFFER_F_OFFLOAD_IP_CKSUM;
+	    (VNET_BUFFER_F_IS_IP4 | VNET_BUFFER_F_OFFLOAD_IP_CKSUM);
 	}
       else if (PREDICT_TRUE (ethertype == ETHERNET_TYPE_IP6))
 	{
-	  ip6_header_t *ip6 = (ip6_header_t *) (b0->data + l2hdr_sz);
+	  ip6_header_t *ip6 =
+	    (ip6_header_t *) (vlib_buffer_get_current (b0) + l2hdr_sz);
 	  /* FIXME IPv6 EH traversal */
-	  vnet_buffer (b0)->l4_hdr_offset = l2hdr_sz + sizeof (ip6_header_t);
 	  l4_proto = ip6->protocol;
-	  b0->flags |=
-	    (VNET_BUFFER_F_IS_IP6 | VNET_BUFFER_F_L2_HDR_OFFSET_VALID
-	     | VNET_BUFFER_F_L3_HDR_OFFSET_VALID |
-	     VNET_BUFFER_F_L4_HDR_OFFSET_VALID);
+	  b0->flags |= VNET_BUFFER_F_IS_IP6;
 	}
       if (l4_proto == IP_PROTOCOL_TCP)
 	{
 	  b0->flags |= VNET_BUFFER_F_OFFLOAD_TCP_CKSUM;
-	  tcp_header_t *tcp = (tcp_header_t *) (b0->data +
-						vnet_buffer
-						(b0)->l4_hdr_offset);
-	  l4_hdr_sz = tcp_header_bytes (tcp);
-	  tcp->checksum = 0;
 	}
       else if (l4_proto == IP_PROTOCOL_UDP)
 	{
 	  b0->flags |= VNET_BUFFER_F_OFFLOAD_UDP_CKSUM;
-	  udp_header_t *udp = (udp_header_t *) (b0->data +
-						vnet_buffer
-						(b0)->l4_hdr_offset);
-	  l4_hdr_sz = sizeof (*udp);
-	  udp->checksum = 0;
 	}
     }
 
@@ -215,21 +197,16 @@ fill_gso_buffer_flags (vlib_buffer_t * b0, struct virtio_net_hdr_v1 *hdr)
     {
       ASSERT (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM);
       vnet_buffer2 (b0)->gso_size = hdr->gso_size;
-      vnet_buffer2 (b0)->gso_l4_hdr_sz = l4_hdr_sz;
-      b0->flags |= VNET_BUFFER_F_GSO;
-      b0->flags |= VNET_BUFFER_F_IS_IP4;
+      b0->flags |= VNET_BUFFER_F_GSO | VNET_BUFFER_F_IS_IP4;
     }
   if (hdr->gso_type == VIRTIO_NET_HDR_GSO_TCPV6)
     {
       ASSERT (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM);
       vnet_buffer2 (b0)->gso_size = hdr->gso_size;
-      vnet_buffer2 (b0)->gso_l4_hdr_sz = l4_hdr_sz;
-      b0->flags |= VNET_BUFFER_F_GSO;
-      b0->flags |= VNET_BUFFER_F_IS_IP6;
+      b0->flags |= VNET_BUFFER_F_GSO | VNET_BUFFER_F_IS_IP6;
     }
 }
 
-
 static_always_inline uword
 virtio_device_input_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
 			    vlib_frame_t * frame, virtio_if_t * vif, u16 qid,
diff --git a/src/vnet/gso/gso.c b/src/vnet/gso/gso.c
index c741b17bdd4..cf90d22696d 100644
--- a/src/vnet/gso/gso.c
+++ b/src/vnet/gso/gso.c
@@ -16,7 +16,6 @@
 #include <vlib/vlib.h>
 #include <vnet/vnet.h>
 #include <vppinfra/error.h>
-#include <vnet/ethernet/ethernet.h>
 #include <vnet/feature/feature.h>
 #include <vnet/l2/l2_in_out_feat_arc.h>
 #include <vnet/gso/gso.h>
diff --git a/src/vnet/gso/gso.h b/src/vnet/gso/gso.h
index 8e174dfd1f6..79869c2644b 100644
--- a/src/vnet/gso/gso.h
+++ b/src/vnet/gso/gso.h
@@ -16,10 +16,25 @@
 #ifndef included_gso_h
 #define included_gso_h
 
+#include <vnet/ethernet/ethernet.h>
+#include <vnet/ip/ip4_packet.h>
+#include <vnet/ip/ip6_packet.h>
+#include <vnet/udp/udp_packet.h>
 #include <vnet/vnet.h>
 
 typedef struct
 {
+  i16 l2_hdr_offset;
+  i16 l3_hdr_offset;
+  i16 l4_hdr_offset;
+  u16 l4_hdr_sz;
+  i16 outer_l2_hdr_offset;
+  i16 outer_l3_hdr_offset;
+  i16 outer_l4_hdr_offset;
+} gso_header_offset_t;
+
+typedef struct
+{
   vlib_main_t *vlib_main;
   vnet_main_t *vnet_main;
   u16 msg_id_base;
@@ -29,6 +44,86 @@ extern gso_main_t gso_main;
 
 int vnet_sw_interface_gso_enable_disable (u32 sw_if_index, u8 enable);
 
+static_always_inline gso_header_offset_t
+vnet_gso_header_offset_parser (vlib_buffer_t * b0, int is_ip6)
+{
+  gso_header_offset_t gho = { 0 };
+  u8 l4_proto = 0;
+  u8 l4_hdr_sz = 0;
+
+  if (PREDICT_TRUE ((b0->flags & (VNET_BUFFER_F_L2_HDR_OFFSET_VALID |
+				  VNET_BUFFER_F_L3_HDR_OFFSET_VALID |
+				  VNET_BUFFER_F_L4_HDR_OFFSET_VALID)) ==
+		    (VNET_BUFFER_F_L2_HDR_OFFSET_VALID |
+		     VNET_BUFFER_F_L3_HDR_OFFSET_VALID |
+		     VNET_BUFFER_F_L4_HDR_OFFSET_VALID)))
+    {
+      gho.l2_hdr_offset = vnet_buffer (b0)->l2_hdr_offset;
+      gho.l3_hdr_offset = vnet_buffer (b0)->l3_hdr_offset;
+      gho.l4_hdr_offset = vnet_buffer (b0)->l4_hdr_offset;
+      gho.l4_hdr_sz = vnet_buffer2 (b0)->gso_l4_hdr_sz;
+      return gho;
+    }
+
+  ethernet_header_t *eh = (ethernet_header_t *) vlib_buffer_get_current (b0);
+  u16 ethertype = clib_net_to_host_u16 (eh->type);
+  u16 l2hdr_sz = sizeof (ethernet_header_t);
+
+  if (ethernet_frame_is_tagged (ethertype))
+    {
+      ethernet_vlan_header_t *vlan = (ethernet_vlan_header_t *) (eh + 1);
+
+      ethertype = clib_net_to_host_u16 (vlan->type);
+      l2hdr_sz += sizeof (*vlan);
+      if (ethertype == ETHERNET_TYPE_VLAN)
+	{
+	  vlan++;
+	  ethertype = clib_net_to_host_u16 (vlan->type);
+	  l2hdr_sz += sizeof (*vlan);
+	}
+    }
+
+  gho.l2_hdr_offset = b0->current_data;
+  gho.l3_hdr_offset = l2hdr_sz;
+
+  if (PREDICT_TRUE (is_ip6 == 0))
+    {
+      ip4_header_t *ip4 =
+	(ip4_header_t *) (vlib_buffer_get_current (b0) + l2hdr_sz);
+      gho.l4_hdr_offset = l2hdr_sz + ip4_header_bytes (ip4);
+      l4_proto = ip4->protocol;
+    }
+  else if (PREDICT_TRUE (is_ip6))
+    {
+      ip6_header_t *ip6 =
+	(ip6_header_t *) (vlib_buffer_get_current (b0) + l2hdr_sz);
+      /* FIXME IPv6 EH traversal */
+      gho.l4_hdr_offset = l2hdr_sz + sizeof (ip6_header_t);
+      l4_proto = ip6->protocol;
+    }
+  if (l4_proto == IP_PROTOCOL_TCP)
+    {
+      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))
+    {
+      gho.l4_hdr_sz = l4_hdr_sz;
+    }
+
+  return gho;
+}
+
 #endif /* included_gso_h */
 
 /*
diff --git a/src/vnet/gso/node.c b/src/vnet/gso/node.c
index 069016147d4..548189ee04c 100644
--- a/src/vnet/gso/node.c
+++ b/src/vnet/gso/node.c
@@ -90,7 +90,8 @@ static_always_inline void
 tso_init_buf_from_template (vlib_main_t * vm, vlib_buffer_t * nb0,
 			    vlib_buffer_t * b0, u16 template_data_sz,
 			    u16 gso_size, u8 ** p_dst_ptr, u16 * p_dst_left,
-			    u32 next_tcp_seq, u32 flags)
+			    u32 next_tcp_seq, u32 flags,
+			    gso_header_offset_t * gho)
 {
   tso_init_buf_from_template_base (nb0, b0, flags, template_data_sz);
 
@@ -101,29 +102,31 @@ tso_init_buf_from_template (vlib_main_t * vm, vlib_buffer_t * nb0,
   *p_dst_ptr = vlib_buffer_get_current (nb0) + template_data_sz;
 
   tcp_header_t *tcp =
-    (tcp_header_t *) (nb0->data + vnet_buffer (nb0)->l4_hdr_offset);
+    (tcp_header_t *) (vlib_buffer_get_current (nb0) + gho->l4_hdr_offset);
   tcp->seq_number = clib_host_to_net_u32 (next_tcp_seq);
 }
 
 static_always_inline void
-tso_fixup_segmented_buf (vlib_buffer_t * b0, u8 tcp_flags, int is_ip6)
+tso_fixup_segmented_buf (vlib_buffer_t * b0, u8 tcp_flags, int is_ip6,
+			 gso_header_offset_t * gho)
 {
-  u16 l3_hdr_offset = vnet_buffer (b0)->l3_hdr_offset;
-  u16 l4_hdr_offset = vnet_buffer (b0)->l4_hdr_offset;
-  ip4_header_t *ip4 = (ip4_header_t *) (b0->data + l3_hdr_offset);
-  ip6_header_t *ip6 = (ip6_header_t *) (b0->data + l3_hdr_offset);
-  tcp_header_t *tcp = (tcp_header_t *) (b0->data + l4_hdr_offset);
+  ip4_header_t *ip4 =
+    (ip4_header_t *) (vlib_buffer_get_current (b0) + gho->l3_hdr_offset);
+  ip6_header_t *ip6 =
+    (ip6_header_t *) (vlib_buffer_get_current (b0) + gho->l3_hdr_offset);
+  tcp_header_t *tcp =
+    (tcp_header_t *) (vlib_buffer_get_current (b0) + gho->l4_hdr_offset);
 
   tcp->flags = tcp_flags;
 
   if (is_ip6)
     ip6->payload_length =
       clib_host_to_net_u16 (b0->current_length -
-			    (l4_hdr_offset - b0->current_data));
+			    (gho->l4_hdr_offset - gho->l2_hdr_offset));
   else
     ip4->length =
       clib_host_to_net_u16 (b0->current_length -
-			    (l3_hdr_offset - b0->current_data));
+			    (gho->l3_hdr_offset - gho->l2_hdr_offset));
 }
 
 /**
@@ -137,21 +140,19 @@ tso_fixup_segmented_buf (vlib_buffer_t * b0, u8 tcp_flags, int is_ip6)
 
 static_always_inline u32
 tso_segment_buffer (vlib_main_t * vm, vnet_interface_per_thread_data_t * ptd,
-		    u32 sbi0, vlib_buffer_t * sb0, u32 n_bytes_b0, int is_ip6)
+		    u32 sbi0, vlib_buffer_t * sb0, gso_header_offset_t * gho,
+		    u32 n_bytes_b0, int is_ip6)
 {
   u32 n_tx_bytes = 0;
-  ASSERT (sb0->flags & VNET_BUFFER_F_L2_HDR_OFFSET_VALID);
-  ASSERT (sb0->flags & VNET_BUFFER_F_L3_HDR_OFFSET_VALID);
-  ASSERT (sb0->flags & VNET_BUFFER_F_L4_HDR_OFFSET_VALID);
   u16 gso_size = vnet_buffer2 (sb0)->gso_size;
 
-  int l4_hdr_sz = vnet_buffer2 (sb0)->gso_l4_hdr_sz;
+  int l4_hdr_sz = gho->l4_hdr_sz;
   u8 save_tcp_flags = 0;
   u8 tcp_flags_no_fin_psh = 0;
   u32 next_tcp_seq = 0;
 
   tcp_header_t *tcp =
-    (tcp_header_t *) (sb0->data + vnet_buffer (sb0)->l4_hdr_offset);
+    (tcp_header_t *) (vlib_buffer_get_current (sb0) + gho->l4_hdr_offset);
   next_tcp_seq = clib_net_to_host_u32 (tcp->seq_number);
   /* store original flags for last packet and reset FIN and PSH */
   save_tcp_flags = tcp->flags;
@@ -160,8 +161,7 @@ tso_segment_buffer (vlib_main_t * vm, vnet_interface_per_thread_data_t * ptd,
 
   u32 default_bflags =
     sb0->flags & ~(VNET_BUFFER_F_GSO | VLIB_BUFFER_NEXT_PRESENT);
-  u16 l234_sz = vnet_buffer (sb0)->l4_hdr_offset + l4_hdr_sz
-    - sb0->current_data;
+  u16 l234_sz = gho->l4_hdr_offset + l4_hdr_sz - gho->l2_hdr_offset;
   int first_data_size = clib_min (gso_size, sb0->current_length - l234_sz);
   next_tcp_seq += first_data_size;
 
@@ -189,13 +189,14 @@ tso_segment_buffer (vlib_main_t * vm, vnet_interface_per_thread_data_t * ptd,
       src_ptr = vlib_buffer_get_current (sb0) + l234_sz + first_data_size;
       src_left = sb0->current_length - l234_sz - first_data_size;
 
-      tso_fixup_segmented_buf (b0, tcp_flags_no_fin_psh, is_ip6);
+      tso_fixup_segmented_buf (b0, tcp_flags_no_fin_psh, is_ip6, gho);
 
       /* grab a second buffer and prepare the loop */
       ASSERT (dbi < vec_len (ptd->split_buffers));
       cdb0 = vlib_get_buffer (vm, ptd->split_buffers[dbi++]);
       tso_init_buf_from_template (vm, cdb0, b0, l234_sz, gso_size, &dst_ptr,
-				  &dst_left, next_tcp_seq, default_bflags);
+				  &dst_left, next_tcp_seq, default_bflags,
+				  gho);
 
       /* an arbitrary large number to catch the runaway loops */
       int nloops = 2000;
@@ -241,11 +242,11 @@ tso_segment_buffer (vlib_main_t * vm, vnet_interface_per_thread_data_t * ptd,
 	      cdb0 = vlib_get_buffer (vm, ptd->split_buffers[dbi++]);
 	      tso_init_buf_from_template (vm, cdb0, b0, l234_sz,
 					  gso_size, &dst_ptr, &dst_left,
-					  next_tcp_seq, default_bflags);
+					  next_tcp_seq, default_bflags, gho);
 	    }
 	}
 
-      tso_fixup_segmented_buf (cdb0, save_tcp_flags, is_ip6);
+      tso_fixup_segmented_buf (cdb0, save_tcp_flags, is_ip6, gho);
 
       n_tx_bytes += cdb0->current_length;
     }
@@ -446,11 +447,13 @@ vnet_gso_node_inline (vlib_main_t * vm,
 		  to_next -= 1;
 		  n_left_to_next += 1;
 		  /* undo the counting. */
+		  gso_header_offset_t gho;
 		  u32 n_bytes_b0 = vlib_buffer_length_in_chain (vm, b[0]);
 		  u32 n_tx_bytes = 0;
 
+		  gho = vnet_gso_header_offset_parser (b[0], is_ip6);
 		  n_tx_bytes =
-		    tso_segment_buffer (vm, ptd, bi0, b[0], n_bytes_b0,
+		    tso_segment_buffer (vm, ptd, bi0, b[0], &gho, n_bytes_b0,
 					is_ip6);
 
 		  if (PREDICT_FALSE (n_tx_bytes == 0))
diff --git a/src/vnet/interface_output.c b/src/vnet/interface_output.c
index 49775d58d80..73c7a31f010 100644
--- a/src/vnet/interface_output.c
+++ b/src/vnet/interface_output.c
@@ -38,6 +38,7 @@
  */
 
 #include <vnet/vnet.h>
+#include <vnet/gso/gso.h>
 #include <vnet/ip/icmp46_packet.h>
 #include <vnet/ip/ip4.h>
 #include <vnet/ip/ip6.h>
@@ -163,20 +164,23 @@ calc_checksums (vlib_main_t * vm, vlib_buffer_t * b)
 {
   tcp_header_t *th;
   udp_header_t *uh;
+  gso_header_offset_t gho = { 0 };
 
   int is_ip4 = (b->flags & VNET_BUFFER_F_IS_IP4) != 0;
   int is_ip6 = (b->flags & VNET_BUFFER_F_IS_IP6) != 0;
 
   ASSERT (!(is_ip4 && is_ip6));
 
-  th = (tcp_header_t *) (b->data + vnet_buffer (b)->l4_hdr_offset);
-  uh = (udp_header_t *) (b->data + vnet_buffer (b)->l4_hdr_offset);
+  gho = vnet_gso_header_offset_parser (b, is_ip6);
+  th = (tcp_header_t *) (vlib_buffer_get_current (b) + gho.l4_hdr_offset);
+  uh = (udp_header_t *) (vlib_buffer_get_current (b) + gho.l4_hdr_offset);
 
   if (is_ip4)
     {
       ip4_header_t *ip4;
 
-      ip4 = (ip4_header_t *) (b->data + vnet_buffer (b)->l3_hdr_offset);
+      ip4 =
+	(ip4_header_t *) (vlib_buffer_get_current (b) + gho.l3_hdr_offset);
       if (b->flags & VNET_BUFFER_F_OFFLOAD_IP_CKSUM)
 	ip4->checksum = ip4_header_checksum (ip4);
       if (b->flags & VNET_BUFFER_F_OFFLOAD_TCP_CKSUM)
@@ -192,7 +196,8 @@ calc_checksums (vlib_main_t * vm, vlib_buffer_t * b)
       int bogus;
       ip6_header_t *ip6;
 
-      ip6 = (ip6_header_t *) (b->data + vnet_buffer (b)->l3_hdr_offset);
+      ip6 =
+	(ip6_header_t *) (vlib_buffer_get_current (b) + gho.l3_hdr_offset);
       if (b->flags & VNET_BUFFER_F_OFFLOAD_TCP_CKSUM)
 	{
 	  th->checksum = 0;
diff --git a/src/vnet/pg/input.c b/src/vnet/pg/input.c
index c47dfe270e7..f4f6bd46fe7 100644
--- a/src/vnet/pg/input.c
+++ b/src/vnet/pg/input.c
@@ -1535,9 +1535,9 @@ fill_gso_buffer_flags (vlib_main_t * vm, u32 * buffers, u32 n_buffers,
     {
       vlib_buffer_t *b0 = vlib_get_buffer (vm, buffers[i]);
       u8 l4_proto = 0;
-      u8 l4_hdr_sz = 0;
 
-      ethernet_header_t *eh = (ethernet_header_t *) b0->data;
+      ethernet_header_t *eh =
+	(ethernet_header_t *) vlib_buffer_get_current (b0);
       u16 ethertype = clib_net_to_host_u16 (eh->type);
       u16 l2hdr_sz = sizeof (ethernet_header_t);
 
@@ -1555,50 +1555,30 @@ fill_gso_buffer_flags (vlib_main_t * vm, u32 * buffers, u32 n_buffers,
 	    }
 	}
 
-      vnet_buffer (b0)->l2_hdr_offset = 0;
-      vnet_buffer (b0)->l3_hdr_offset = l2hdr_sz;
       if (PREDICT_TRUE (ethertype == ETHERNET_TYPE_IP4))
 	{
-	  ip4_header_t *ip4 = (ip4_header_t *) (b0->data + l2hdr_sz);
-	  vnet_buffer (b0)->l4_hdr_offset = l2hdr_sz + ip4_header_bytes (ip4);
+	  ip4_header_t *ip4 =
+	    (ip4_header_t *) (vlib_buffer_get_current (b0) + l2hdr_sz);
 	  l4_proto = ip4->protocol;
 	  b0->flags |=
-	    (VNET_BUFFER_F_IS_IP4 | VNET_BUFFER_F_L2_HDR_OFFSET_VALID
-	     | VNET_BUFFER_F_L3_HDR_OFFSET_VALID |
-	     VNET_BUFFER_F_L4_HDR_OFFSET_VALID);
-	  b0->flags |= VNET_BUFFER_F_OFFLOAD_IP_CKSUM;
+	    (VNET_BUFFER_F_IS_IP4 | VNET_BUFFER_F_OFFLOAD_IP_CKSUM);
 	}
       else if (PREDICT_TRUE (ethertype == ETHERNET_TYPE_IP6))
 	{
-	  ip6_header_t *ip6 = (ip6_header_t *) (b0->data + l2hdr_sz);
+	  ip6_header_t *ip6 =
+	    (ip6_header_t *) (vlib_buffer_get_current (b0) + l2hdr_sz);
 	  /* FIXME IPv6 EH traversal */
-	  vnet_buffer (b0)->l4_hdr_offset = l2hdr_sz + sizeof (ip6_header_t);
 	  l4_proto = ip6->protocol;
-	  b0->flags |=
-	    (VNET_BUFFER_F_IS_IP6 | VNET_BUFFER_F_L2_HDR_OFFSET_VALID
-	     | VNET_BUFFER_F_L3_HDR_OFFSET_VALID |
-	     VNET_BUFFER_F_L4_HDR_OFFSET_VALID);
+	  b0->flags |= VNET_BUFFER_F_IS_IP6;
 	}
       if (l4_proto == IP_PROTOCOL_TCP)
 	{
-	  b0->flags |= VNET_BUFFER_F_OFFLOAD_TCP_CKSUM;
-	  tcp_header_t *tcp = (tcp_header_t *) (b0->data +
-						vnet_buffer
-						(b0)->l4_hdr_offset);
-	  l4_hdr_sz = tcp_header_bytes (tcp);
-	  tcp->checksum = 0;
-	  vnet_buffer2 (b0)->gso_l4_hdr_sz = l4_hdr_sz;
+	  b0->flags |= (VNET_BUFFER_F_OFFLOAD_TCP_CKSUM | VNET_BUFFER_F_GSO);
 	  vnet_buffer2 (b0)->gso_size = packet_data_size;
-	  b0->flags |= VNET_BUFFER_F_GSO;
 	}
       else if (l4_proto == IP_PROTOCOL_UDP)
 	{
 	  b0->flags |= VNET_BUFFER_F_OFFLOAD_UDP_CKSUM;
-	  udp_header_t *udp = (udp_header_t *) (b0->data +
-						vnet_buffer
-						(b0)->l4_hdr_offset);
-	  vnet_buffer2 (b0)->gso_l4_hdr_sz = sizeof (*udp);
-	  udp->checksum = 0;
 	}
     }
 }