src/vnet/ethernet/mac_swap.c - fdio/vpp - Gitiles

 /*
  * Copyright (c) 2015 Cisco and/or its affiliates.
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 #include <vlib/vlib.h>
 #include <vnet/pg/pg.h>
 #include <vnet/ethernet/ethernet.h>
 #include <vppinfra/error.h>
 #include <vnet/devices/pci/ige.h>
 #include <vnet/devices/pci/ixge.h>
 #include <vnet/devices/pci/ixgev.h>

 typedef struct
 {
   u32 cached_next_index;
   u32 cached_sw_if_index;

   /* Hash table to map sw_if_index to next node index */
   uword *next_node_index_by_sw_if_index;

   /* convenience */
   vlib_main_t *vlib_main;
   vnet_main_t *vnet_main;
 } mac_swap_main_t;

 typedef struct
 {
   u8 src[6];
   u8 dst[6];
   u32 sw_if_index;
   u32 next_index;
 } swap_trace_t;

 /* packet trace format function */
 static u8 *
 format_swap_trace (u8 * s, va_list * args)
 {
   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
   swap_trace_t *t = va_arg (*args, swap_trace_t *);

   s = format (s, "SWAP: dst now %U src now %U sw_if_index %d next_index %d",
 	      format_ethernet_address, t->dst,
 	      format_ethernet_address, t->src, t->sw_if_index, t->next_index);
   return s;
 }

 #define foreach_hw_driver_next                  \
   _(IP4)                                        \
   _(IP6)                                        \
   _(ETHERNET)

 mac_swap_main_t mac_swap_main;

 static vlib_node_registration_t mac_swap_node;

 #define foreach_mac_swap_error \
 _(SWAPS, "mac addresses swapped")

 typedef enum
 {
 #define _(sym,str) MAC_SWAP_ERROR_##sym,
   foreach_mac_swap_error
 #undef _
     MAC_SWAP_N_ERROR,
 } mac_swap_error_t;

 static char *mac_swap_error_strings[] = {
 #define _(sym,string) string,
   foreach_mac_swap_error
 #undef _
 };

 /*
  * To drop a pkt and increment one of the previous counters:
  *
  * set b0->error = error_node->errors[RANDOM_ERROR_SAMPLE];
  * set next0 to a disposition index bound to "error-drop".
  *
  * To manually increment the specific counter MAC_SWAP_ERROR_SAMPLE:
  *
  *  vlib_node_t *n = vlib_get_node (vm, mac_swap.index);
  *  u32 node_counter_base_index = n->error_heap_index;
  *  vlib_error_main_t * em = &vm->error_main;
  *  em->counters[node_counter_base_index + MAC_SWAP_ERROR_SAMPLE] += 1;
  *
  */

 typedef enum
 {
   MAC_SWAP_NEXT_DROP,
   MAC_SWAP_N_NEXT,
 } mac_swap_next_t;

 static uword
 mac_swap_node_fn (vlib_main_t * vm,
 		  vlib_node_runtime_t * node, vlib_frame_t * frame)
 {
   u32 n_left_from, *from, *to_next;
   mac_swap_next_t next_index;
   mac_swap_main_t *msm = &mac_swap_main;
   vlib_node_t *n = vlib_get_node (vm, mac_swap_node.index);
   u32 node_counter_base_index = n->error_heap_index;
   vlib_error_main_t *em = &vm->error_main;

   from = vlib_frame_vector_args (frame);
   n_left_from = frame->n_vectors;
   next_index = node->cached_next_index;

   while (n_left_from > 0)
     {
       u32 n_left_to_next;

       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

       while (n_left_from >= 4 && n_left_to_next >= 2)
 	{
 	  u32 bi0, bi1;
 	  vlib_buffer_t *b0, *b1;
 	  u32 next0, next1;
 	  u32 sw_if_index0, sw_if_index1;
 	  uword *p0, *p1;
 	  u64 tmp0a, tmp0b;
 	  u64 tmp1a, tmp1b;
 	  ethernet_header_t *h0, *h1;


 	  /* Prefetch next iteration. */
 	  {
 	    vlib_buffer_t *p2, *p3;

 	    p2 = vlib_get_buffer (vm, from[2]);
 	    p3 = vlib_get_buffer (vm, from[3]);

 	    vlib_prefetch_buffer_header (p2, LOAD);
 	    vlib_prefetch_buffer_header (p3, LOAD);

 	    CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, STORE);
 	    CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, STORE);
 	  }

 	  to_next[0] = bi0 = from[0];
 	  to_next[1] = bi1 = from[1];
 	  from += 2;
 	  to_next += 2;
 	  n_left_from -= 2;
 	  n_left_to_next -= 2;

 	  b0 = vlib_get_buffer (vm, bi0);
 	  b1 = vlib_get_buffer (vm, bi1);

 	  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
 	  next0 = msm->cached_next_index;
 	  sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
 	  next1 = msm->cached_next_index;

 	  if (PREDICT_FALSE (msm->cached_sw_if_index != sw_if_index0))
 	    {
 	      p0 =
 		hash_get (msm->next_node_index_by_sw_if_index, sw_if_index0);
 	      if (p0 == 0)
 		{
 		  vnet_hw_interface_t *hw0;

 		  hw0 = vnet_get_sup_hw_interface (msm->vnet_main,
 						   sw_if_index0);

 		  next0 = vlib_node_add_next (msm->vlib_main,
 					      mac_swap_node.index,
 					      hw0->output_node_index);
 		  hash_set (msm->next_node_index_by_sw_if_index,
 			    sw_if_index0, next0);
 		}
 	      else
 		next0 = p0[0];
 	      msm->cached_sw_if_index = sw_if_index0;
 	      msm->cached_next_index = next0;
 	      next1 = next0;
 	    }
 	  if (PREDICT_FALSE (msm->cached_sw_if_index != sw_if_index1))
 	    {
 	      p1 =
 		hash_get (msm->next_node_index_by_sw_if_index, sw_if_index1);
 	      if (p1 == 0)
 		{
 		  vnet_hw_interface_t *hw1;

 		  hw1 = vnet_get_sup_hw_interface (msm->vnet_main,
 						   sw_if_index1);

 		  next1 = vlib_node_add_next (msm->vlib_main,
 					      mac_swap_node.index,
 					      hw1->output_node_index);
 		  hash_set (msm->next_node_index_by_sw_if_index,
 			    sw_if_index1, next1);
 		}
 	      else
 		next1 = p1[0];
 	      msm->cached_sw_if_index = sw_if_index1;
 	      msm->cached_next_index = next1;
 	    }

 	  em->counters[node_counter_base_index + MAC_SWAP_ERROR_SWAPS] += 2;

 	  /* reset buffer so we always point at the MAC hdr */
 	  vlib_buffer_reset (b0);
 	  vlib_buffer_reset (b1);
 	  h0 = vlib_buffer_get_current (b0);
 	  h1 = vlib_buffer_get_current (b1);

 	  /* Swap 2 x src and dst mac addresses using 8-byte load/stores */
 	  tmp0a = clib_net_to_host_u64 (((u64 *) (h0->dst_address))[0]);
 	  tmp1a = clib_net_to_host_u64 (((u64 *) (h1->dst_address))[0]);
 	  tmp0b = clib_net_to_host_u64 (((u64 *) (h0->src_address))[0]);
 	  tmp1b = clib_net_to_host_u64 (((u64 *) (h1->src_address))[0]);
 	  ((u64 *) (h0->dst_address))[0] = clib_host_to_net_u64 (tmp0b);
 	  ((u64 *) (h1->dst_address))[0] = clib_host_to_net_u64 (tmp1b);
 	  /* Move the ethertype from "b" to "a" */
 	  tmp0a &= ~(0xFFFF);
 	  tmp1a &= ~(0xFFFF);
 	  tmp0a |= tmp0b & 0xFFFF;
 	  ((u64 *) (h0->src_address))[0] = clib_host_to_net_u64 (tmp0a);
 	  tmp1a |= tmp1b & 0xFFFF;
 	  ((u64 *) (h1->src_address))[0] = clib_host_to_net_u64 (tmp1a);

 	  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
 	    {
 	      if (b0->flags & VLIB_BUFFER_IS_TRACED)
 		{
 		  swap_trace_t *t =
 		    vlib_add_trace (vm, node, b0, sizeof (*t));
 		  clib_memcpy (t->src, h0->src_address, 6);
 		  clib_memcpy (t->dst, h0->dst_address, 6);
 		  t->sw_if_index = sw_if_index0;
 		  t->next_index = next0;
 		}
 	      if (b1->flags & VLIB_BUFFER_IS_TRACED)
 		{
 		  swap_trace_t *t =
 		    vlib_add_trace (vm, node, b1, sizeof (*t));
 		  clib_memcpy (t->src, h1->src_address, 6);
 		  clib_memcpy (t->dst, h1->dst_address, 6);
 		  t->sw_if_index = sw_if_index1;
 		  t->next_index = next1;
 		}
 	    }

 	  vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
 					   to_next, n_left_to_next,
 					   bi0, bi1, next0, next1);
 	}

       while (n_left_from > 0 && n_left_to_next > 0)
 	{
 	  u32 bi0;
 	  vlib_buffer_t *b0;
 	  u32 next0;
 	  u32 sw_if_index0;
 	  uword *p0;
 	  u64 tmp0a, tmp0b;
 	  ethernet_header_t *h0;

 	  bi0 = from[0];
 	  to_next[0] = bi0;
 	  from += 1;
 	  to_next += 1;
 	  n_left_from -= 1;
 	  n_left_to_next -= 1;

 	  b0 = vlib_get_buffer (vm, bi0);

 	  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
 	  next0 = msm->cached_next_index;

 	  if (PREDICT_FALSE (msm->cached_sw_if_index != sw_if_index0))
 	    {
 	      p0 =
 		hash_get (msm->next_node_index_by_sw_if_index, sw_if_index0);
 	      if (p0 == 0)
 		{
 		  vnet_hw_interface_t *hw0;

 		  hw0 = vnet_get_sup_hw_interface (msm->vnet_main,
 						   sw_if_index0);

 		  next0 = vlib_node_add_next (msm->vlib_main,
 					      mac_swap_node.index,
 					      hw0->output_node_index);
 		  hash_set (msm->next_node_index_by_sw_if_index,
 			    sw_if_index0, next0);
 		}
 	      else
 		next0 = p0[0];
 	      msm->cached_sw_if_index = sw_if_index0;
 	      msm->cached_next_index = next0;
 	    }

 	  em->counters[node_counter_base_index + MAC_SWAP_ERROR_SWAPS] += 1;

 	  /* reset buffer so we always point at the MAC hdr */
 	  vlib_buffer_reset (b0);
 	  h0 = vlib_buffer_get_current (b0);

 	  /* Exchange src and dst, preserve the ethertype */
 	  tmp0a = clib_net_to_host_u64 (((u64 *) (h0->dst_address))[0]);
 	  tmp0b = clib_net_to_host_u64 (((u64 *) (h0->src_address))[0]);
 	  ((u64 *) (h0->dst_address))[0] = clib_host_to_net_u64 (tmp0b);
 	  tmp0a &= ~(0xFFFF);
 	  tmp0a |= tmp0b & 0xFFFF;
 	  ((u64 *) (h0->src_address))[0] = clib_host_to_net_u64 (tmp0a);

 	  /* ship it */
 	  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
 			     && (b0->flags & VLIB_BUFFER_IS_TRACED)))
 	    {
 	      swap_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
 	      clib_memcpy (t->src, h0->src_address, 6);
 	      clib_memcpy (t->dst, h0->dst_address, 6);
 	      t->sw_if_index = sw_if_index0;
 	      t->next_index = next0;
 	    }

 	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
 					   to_next, n_left_to_next,
 					   bi0, next0);
 	}

       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
     }

   return frame->n_vectors;
 }

 /* *INDENT-OFF* */
 VLIB_REGISTER_NODE (mac_swap_node,static) = {
   .function = mac_swap_node_fn,
   .name = "mac-swap",
   .vector_size = sizeof (u32),
   .format_trace = format_swap_trace,
   .type = VLIB_NODE_TYPE_INTERNAL,

   .n_errors = ARRAY_LEN(mac_swap_error_strings),
   .error_strings = mac_swap_error_strings,

   .n_next_nodes = MAC_SWAP_N_NEXT,

   /* edit / add dispositions here */
   .next_nodes = {
         [MAC_SWAP_NEXT_DROP] = "error-drop",
   },
 };
 /* *INDENT-ON* */

 clib_error_t *
 mac_swap_init (vlib_main_t * vm)
 {
   mac_swap_main_t *msm = &mac_swap_main;

   msm->next_node_index_by_sw_if_index = hash_create (0, sizeof (uword));
   msm->cached_next_index = (u32) ~ 0;
   msm->cached_sw_if_index = (u32) ~ 0;
   msm->vlib_main = vm;
   msm->vnet_main = vnet_get_main ();

   /* Driver RX nodes send pkts here... */
 #define _(a) ixge_set_next_node (IXGE_RX_NEXT_##a##_INPUT, "mac-swap");
   foreach_hw_driver_next
 #undef _
 #define _(a) ixgev_set_next_node (IXGEV_RX_NEXT_##a##_INPUT, "mac-swap");
     foreach_hw_driver_next
 #undef _
 #define _(a) ige_set_next_node (IGE_RX_NEXT_##a##_INPUT, "mac-swap");
     foreach_hw_driver_next
 #undef _
     return 0;
 }

 VLIB_INIT_FUNCTION (mac_swap_init);


 /*
  * fd.io coding-style-patch-verification: ON
  *
  * Local Variables:
  * eval: (c-set-style "gnu")
  * End:
  */
	/*
	* Copyright (c) 2015 Cisco and/or its affiliates.
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at:
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	#include <vlib/vlib.h>
	#include <vnet/pg/pg.h>
	#include <vnet/ethernet/ethernet.h>
	#include <vppinfra/error.h>
	#include <vnet/devices/pci/ige.h>
	#include <vnet/devices/pci/ixge.h>
	#include <vnet/devices/pci/ixgev.h>

	typedef struct
	{
	u32 cached_next_index;
	u32 cached_sw_if_index;

	/* Hash table to map sw_if_index to next node index */
	uword *next_node_index_by_sw_if_index;

	/* convenience */
	vlib_main_t *vlib_main;
	vnet_main_t *vnet_main;
	} mac_swap_main_t;

	typedef struct
	{
	u8 src[6];
	u8 dst[6];
	u32 sw_if_index;
	u32 next_index;
	} swap_trace_t;

	/* packet trace format function */
	static u8 *
	format_swap_trace (u8 * s, va_list * args)
	{
	CLIB_UNUSED (vlib_main_t * vm) = va_arg (args, vlib_main_t );
	CLIB_UNUSED (vlib_node_t * node) = va_arg (args, vlib_node_t );
	swap_trace_t t = va_arg (args, swap_trace_t *);

	s = format (s, "SWAP: dst now %U src now %U sw_if_index %d next_index %d",
	format_ethernet_address, t->dst,
	format_ethernet_address, t->src, t->sw_if_index, t->next_index);
	return s;
	}

	#define foreach_hw_driver_next \
	_(IP4) \
	_(IP6) \
	_(ETHERNET)

	mac_swap_main_t mac_swap_main;

	static vlib_node_registration_t mac_swap_node;

	#define foreach_mac_swap_error \
	_(SWAPS, "mac addresses swapped")

	typedef enum
	{
	#define _(sym,str) MAC_SWAP_ERROR_##sym,
	foreach_mac_swap_error
	#undef _
	MAC_SWAP_N_ERROR,
	} mac_swap_error_t;

	static char *mac_swap_error_strings[] = {
	#define _(sym,string) string,
	foreach_mac_swap_error
	#undef _
	};

	/*
	* To drop a pkt and increment one of the previous counters:
	*
	* set b0->error = error_node->errors[RANDOM_ERROR_SAMPLE];
	* set next0 to a disposition index bound to "error-drop".
	*
	* To manually increment the specific counter MAC_SWAP_ERROR_SAMPLE:
	*
	* vlib_node_t *n = vlib_get_node (vm, mac_swap.index);
	* u32 node_counter_base_index = n->error_heap_index;
	* vlib_error_main_t * em = &vm->error_main;
	* em->counters[node_counter_base_index + MAC_SWAP_ERROR_SAMPLE] += 1;
	*
	*/

	typedef enum
	{
	MAC_SWAP_NEXT_DROP,
	MAC_SWAP_N_NEXT,
	} mac_swap_next_t;

	static uword
	mac_swap_node_fn (vlib_main_t * vm,
	vlib_node_runtime_t * node, vlib_frame_t * frame)
	{
	u32 n_left_from, from, to_next;
	mac_swap_next_t next_index;
	mac_swap_main_t *msm = &mac_swap_main;
	vlib_node_t *n = vlib_get_node (vm, mac_swap_node.index);
	u32 node_counter_base_index = n->error_heap_index;
	vlib_error_main_t *em = &vm->error_main;

	from = vlib_frame_vector_args (frame);
	n_left_from = frame->n_vectors;
	next_index = node->cached_next_index;

	while (n_left_from > 0)
	{
	u32 n_left_to_next;

	vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

	while (n_left_from >= 4 && n_left_to_next >= 2)
	{
	u32 bi0, bi1;
	vlib_buffer_t b0, b1;
	u32 next0, next1;
	u32 sw_if_index0, sw_if_index1;
	uword p0, p1;
	u64 tmp0a, tmp0b;
	u64 tmp1a, tmp1b;
	ethernet_header_t h0, h1;


	/* Prefetch next iteration. */
	{
	vlib_buffer_t p2, p3;

	p2 = vlib_get_buffer (vm, from[2]);
	p3 = vlib_get_buffer (vm, from[3]);

	vlib_prefetch_buffer_header (p2, LOAD);
	vlib_prefetch_buffer_header (p3, LOAD);

	CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, STORE);
	CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, STORE);
	}

	to_next[0] = bi0 = from[0];
	to_next[1] = bi1 = from[1];
	from += 2;
	to_next += 2;
	n_left_from -= 2;
	n_left_to_next -= 2;

	b0 = vlib_get_buffer (vm, bi0);
	b1 = vlib_get_buffer (vm, bi1);

	sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
	next0 = msm->cached_next_index;
	sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
	next1 = msm->cached_next_index;

	if (PREDICT_FALSE (msm->cached_sw_if_index != sw_if_index0))
	{
	p0 =
	hash_get (msm->next_node_index_by_sw_if_index, sw_if_index0);
	if (p0 == 0)
	{
	vnet_hw_interface_t *hw0;

	hw0 = vnet_get_sup_hw_interface (msm->vnet_main,
	sw_if_index0);

	next0 = vlib_node_add_next (msm->vlib_main,
	mac_swap_node.index,
	hw0->output_node_index);
	hash_set (msm->next_node_index_by_sw_if_index,
	sw_if_index0, next0);
	}
	else
	next0 = p0[0];
	msm->cached_sw_if_index = sw_if_index0;
	msm->cached_next_index = next0;
	next1 = next0;
	}
	if (PREDICT_FALSE (msm->cached_sw_if_index != sw_if_index1))
	{
	p1 =
	hash_get (msm->next_node_index_by_sw_if_index, sw_if_index1);
	if (p1 == 0)
	{
	vnet_hw_interface_t *hw1;

	hw1 = vnet_get_sup_hw_interface (msm->vnet_main,
	sw_if_index1);

	next1 = vlib_node_add_next (msm->vlib_main,
	mac_swap_node.index,
	hw1->output_node_index);
	hash_set (msm->next_node_index_by_sw_if_index,
	sw_if_index1, next1);
	}
	else
	next1 = p1[0];
	msm->cached_sw_if_index = sw_if_index1;
	msm->cached_next_index = next1;
	}

	em->counters[node_counter_base_index + MAC_SWAP_ERROR_SWAPS] += 2;

	/* reset buffer so we always point at the MAC hdr */
	vlib_buffer_reset (b0);
	vlib_buffer_reset (b1);
	h0 = vlib_buffer_get_current (b0);
	h1 = vlib_buffer_get_current (b1);

	/* Swap 2 x src and dst mac addresses using 8-byte load/stores */
	tmp0a = clib_net_to_host_u64 (((u64 *) (h0->dst_address))[0]);
	tmp1a = clib_net_to_host_u64 (((u64 *) (h1->dst_address))[0]);
	tmp0b = clib_net_to_host_u64 (((u64 *) (h0->src_address))[0]);
	tmp1b = clib_net_to_host_u64 (((u64 *) (h1->src_address))[0]);
	((u64 *) (h0->dst_address))[0] = clib_host_to_net_u64 (tmp0b);
	((u64 *) (h1->dst_address))[0] = clib_host_to_net_u64 (tmp1b);
	/* Move the ethertype from "b" to "a" */
	tmp0a &= ~(0xFFFF);
	tmp1a &= ~(0xFFFF);
	tmp0a \|= tmp0b & 0xFFFF;
	((u64 *) (h0->src_address))[0] = clib_host_to_net_u64 (tmp0a);
	tmp1a \|= tmp1b & 0xFFFF;
	((u64 *) (h1->src_address))[0] = clib_host_to_net_u64 (tmp1a);

	if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
	{
	if (b0->flags & VLIB_BUFFER_IS_TRACED)
	{
	swap_trace_t *t =
	vlib_add_trace (vm, node, b0, sizeof (*t));
	clib_memcpy (t->src, h0->src_address, 6);
	clib_memcpy (t->dst, h0->dst_address, 6);
	t->sw_if_index = sw_if_index0;
	t->next_index = next0;
	}
	if (b1->flags & VLIB_BUFFER_IS_TRACED)
	{
	swap_trace_t *t =
	vlib_add_trace (vm, node, b1, sizeof (*t));
	clib_memcpy (t->src, h1->src_address, 6);
	clib_memcpy (t->dst, h1->dst_address, 6);
	t->sw_if_index = sw_if_index1;
	t->next_index = next1;
	}
	}

	vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
	to_next, n_left_to_next,
	bi0, bi1, next0, next1);
	}

	while (n_left_from > 0 && n_left_to_next > 0)
	{
	u32 bi0;
	vlib_buffer_t *b0;
	u32 next0;
	u32 sw_if_index0;
	uword *p0;
	u64 tmp0a, tmp0b;
	ethernet_header_t *h0;

	bi0 = from[0];
	to_next[0] = bi0;
	from += 1;
	to_next += 1;
	n_left_from -= 1;
	n_left_to_next -= 1;

	b0 = vlib_get_buffer (vm, bi0);

	sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
	next0 = msm->cached_next_index;

	if (PREDICT_FALSE (msm->cached_sw_if_index != sw_if_index0))
	{
	p0 =
	hash_get (msm->next_node_index_by_sw_if_index, sw_if_index0);
	if (p0 == 0)
	{
	vnet_hw_interface_t *hw0;

	hw0 = vnet_get_sup_hw_interface (msm->vnet_main,
	sw_if_index0);

	next0 = vlib_node_add_next (msm->vlib_main,
	mac_swap_node.index,
	hw0->output_node_index);
	hash_set (msm->next_node_index_by_sw_if_index,
	sw_if_index0, next0);
	}
	else
	next0 = p0[0];
	msm->cached_sw_if_index = sw_if_index0;
	msm->cached_next_index = next0;
	}

	em->counters[node_counter_base_index + MAC_SWAP_ERROR_SWAPS] += 1;

	/* reset buffer so we always point at the MAC hdr */
	vlib_buffer_reset (b0);
	h0 = vlib_buffer_get_current (b0);

	/* Exchange src and dst, preserve the ethertype */
	tmp0a = clib_net_to_host_u64 (((u64 *) (h0->dst_address))[0]);
	tmp0b = clib_net_to_host_u64 (((u64 *) (h0->src_address))[0]);
	((u64 *) (h0->dst_address))[0] = clib_host_to_net_u64 (tmp0b);
	tmp0a &= ~(0xFFFF);
	tmp0a \|= tmp0b & 0xFFFF;
	((u64 *) (h0->src_address))[0] = clib_host_to_net_u64 (tmp0a);

	/* ship it */
	if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
	&& (b0->flags & VLIB_BUFFER_IS_TRACED)))
	{
	swap_trace_t t = vlib_add_trace (vm, node, b0, sizeof (t));
	clib_memcpy (t->src, h0->src_address, 6);
	clib_memcpy (t->dst, h0->dst_address, 6);
	t->sw_if_index = sw_if_index0;
	t->next_index = next0;
	}

	vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
	to_next, n_left_to_next,
	bi0, next0);
	}

	vlib_put_next_frame (vm, node, next_index, n_left_to_next);
	}

	return frame->n_vectors;
	}

	/* INDENT-OFF */
	VLIB_REGISTER_NODE (mac_swap_node,static) = {
	.function = mac_swap_node_fn,
	.name = "mac-swap",
	.vector_size = sizeof (u32),
	.format_trace = format_swap_trace,
	.type = VLIB_NODE_TYPE_INTERNAL,

	.n_errors = ARRAY_LEN(mac_swap_error_strings),
	.error_strings = mac_swap_error_strings,

	.n_next_nodes = MAC_SWAP_N_NEXT,

	/* edit / add dispositions here */
	.next_nodes = {
	[MAC_SWAP_NEXT_DROP] = "error-drop",
	},
	};
	/* INDENT-ON */

	clib_error_t *
	mac_swap_init (vlib_main_t * vm)
	{
	mac_swap_main_t *msm = &mac_swap_main;

	msm->next_node_index_by_sw_if_index = hash_create (0, sizeof (uword));
	msm->cached_next_index = (u32) ~ 0;
	msm->cached_sw_if_index = (u32) ~ 0;
	msm->vlib_main = vm;
	msm->vnet_main = vnet_get_main ();

	/* Driver RX nodes send pkts here... */
	#define _(a) ixge_set_next_node (IXGE_RX_NEXT_##a##_INPUT, "mac-swap");
	foreach_hw_driver_next
	#undef _
	#define _(a) ixgev_set_next_node (IXGEV_RX_NEXT_##a##_INPUT, "mac-swap");
	foreach_hw_driver_next
	#undef _
	#define _(a) ige_set_next_node (IGE_RX_NEXT_##a##_INPUT, "mac-swap");
	foreach_hw_driver_next
	#undef _
	return 0;
	}

	VLIB_INIT_FUNCTION (mac_swap_init);


	/*
	* fd.io coding-style-patch-verification: ON
	*
	* Local Variables:
	* eval: (c-set-style "gnu")
	* End:
	*/