src/vnet/l2/l2_fwd.c

/*
 * l2_fwd.c : layer 2 forwarding using l2fib
 *
 * Copyright (c) 2013 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/vnet.h>
#include <vnet/pg/pg.h>
#include <vnet/ethernet/ethernet.h>
#include <vlib/cli.h>

#include <vnet/l2/l2_input.h>
#include <vnet/l2/l2_bvi.h>
#include <vnet/l2/l2_fwd.h>
#include <vnet/l2/l2_fib.h>

#include <vppinfra/error.h>
#include <vppinfra/hash.h>
#include <vppinfra/sparse_vec.h>


/**
 * @file
 * @brief Ethernet Forwarding.
 *
 * Code in this file handles forwarding Layer 2 packets. This file calls
 * the FIB lookup, packet learning and the packet flooding as necessary.
 * Packet is then sent to the next graph node.
 */

typedef struct
{

  /* Hash table */
  BVT (clib_bihash) * mac_table;

  /* next node index for the L3 input node of each ethertype */
  next_by_ethertype_t l3_next;

  /* Next nodes for each feature */
  u32 feat_next_node_index[32];

  /* convenience variables */
  vlib_main_t *vlib_main;
  vnet_main_t *vnet_main;
} l2fwd_main_t;

typedef struct
{
  /* per-pkt trace data */
  u8 src[6];
  u8 dst[6];
  u32 sw_if_index;
  u16 bd_index;
} l2fwd_trace_t;

/* packet trace format function */
static u8 *
format_l2fwd_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 *);
  l2fwd_trace_t *t = va_arg (*args, l2fwd_trace_t *);

  s = format (s, "l2-fwd:   sw_if_index %d dst %U src %U bd_index %d",
	      t->sw_if_index,
	      format_ethernet_address, t->dst,
	      format_ethernet_address, t->src, t->bd_index);
  return s;
}

l2fwd_main_t l2fwd_main;

static vlib_node_registration_t l2fwd_node;

#define foreach_l2fwd_error				\
_(L2FWD,         "L2 forward packets")			\
_(FLOOD,         "L2 forward misses")			\
_(HIT,           "L2 forward hits")			\
_(BVI_BAD_MAC,   "BVI L3 MAC mismatch")  		\
_(BVI_ETHERTYPE, "BVI packet with unhandled ethertype")	\
_(FILTER_DROP,   "Filter Mac Drop")			\
_(REFLECT_DROP,  "Reflection Drop")			\
_(STALE_DROP,    "Stale entry Drop")

typedef enum
{
#define _(sym,str) L2FWD_ERROR_##sym,
  foreach_l2fwd_error
#undef _
    L2FWD_N_ERROR,
} l2fwd_error_t;

static char *l2fwd_error_strings[] = {
#define _(sym,string) string,
  foreach_l2fwd_error
#undef _
};

typedef enum
{
  L2FWD_NEXT_L2_OUTPUT,
  L2FWD_NEXT_DROP,
  L2FWD_N_NEXT,
} l2fwd_next_t;

/** Forward one packet based on the mac table lookup result. */

static_always_inline void
l2fwd_process (vlib_main_t * vm,
	       vlib_node_runtime_t * node,
	       l2fwd_main_t * msm,
	       vlib_error_main_t * em,
	       vlib_buffer_t * b0,
	       u32 sw_if_index0, l2fib_entry_result_t * result0, u32 * next0)
{
  int try_flood = result0->raw == ~0;
  int flood_error;

  if (PREDICT_FALSE (try_flood))
    {
      flood_error = L2FWD_ERROR_FLOOD;
    }
  else
    {
      /* lookup hit, forward packet  */
#ifdef COUNTERS
      em->counters[node_counter_base_index + L2FWD_ERROR_HIT] += 1;
#endif

      vnet_buffer (b0)->sw_if_index[VLIB_TX] = result0->fields.sw_if_index;
      *next0 = L2FWD_NEXT_L2_OUTPUT;
      int l2fib_seq_num_valid = 1;

      /* check l2fib seq num for stale entries */
      if (!result0->fields.age_not)
	{
	  l2fib_seq_num_t in_sn = {.as_u16 = vnet_buffer (b0)->l2.l2fib_sn };
	  l2fib_seq_num_t expected_sn = {
	    .bd = in_sn.bd,
	    .swif = *l2fib_swif_seq_num (result0->fields.sw_if_index),
	  };
	  l2fib_seq_num_valid =
	    expected_sn.as_u16 == result0->fields.sn.as_u16;
	}

      if (PREDICT_FALSE (!l2fib_seq_num_valid))
	{
	  flood_error = L2FWD_ERROR_STALE_DROP;
	  try_flood = 1;
	}
      /* perform reflection check */
      else if (PREDICT_FALSE (sw_if_index0 == result0->fields.sw_if_index))
	{
	  b0->error = node->errors[L2FWD_ERROR_REFLECT_DROP];
	  *next0 = L2FWD_NEXT_DROP;
	}
      /* perform filter check */
      else if (PREDICT_FALSE (result0->fields.filter))
	{
	  b0->error = node->errors[L2FWD_ERROR_FILTER_DROP];
	  *next0 = L2FWD_NEXT_DROP;
	}
      /* perform BVI check */
      else if (PREDICT_FALSE (result0->fields.bvi))
	{
	  u32 rc;
	  rc = l2_to_bvi (vm,
			  msm->vnet_main,
			  b0,
			  vnet_buffer (b0)->sw_if_index[VLIB_TX],
			  &msm->l3_next, next0);

	  if (PREDICT_FALSE (rc))
	    {
	      if (rc == TO_BVI_ERR_BAD_MAC)
		{
		  b0->error = node->errors[L2FWD_ERROR_BVI_BAD_MAC];
		  *next0 = L2FWD_NEXT_DROP;
		}
	      else if (rc == TO_BVI_ERR_ETHERTYPE)
		{
		  b0->error = node->errors[L2FWD_ERROR_BVI_ETHERTYPE];
		  *next0 = L2FWD_NEXT_DROP;
		}
	    }
	}
    }

  /* flood */
  if (PREDICT_FALSE (try_flood))
    {
      /*
       * lookup miss, so flood which is typically the next feature
       * unless some other feature is inserted before uu_flood
       */
      if (vnet_buffer (b0)->l2.feature_bitmap & L2INPUT_FEAT_UU_FLOOD)
	{
	  *next0 = vnet_l2_feature_next (b0, msm->feat_next_node_index,
					 L2INPUT_FEAT_FWD);
	}
      else
	{
	  /* Flooding is disabled */
	  b0->error = node->errors[flood_error];
	  *next0 = L2FWD_NEXT_DROP;
	}
    }

}


static_always_inline uword
l2fwd_node_inline (vlib_main_t * vm, vlib_node_runtime_t * node,
		   vlib_frame_t * frame, int do_trace)
{
  u32 n_left_from, *from, *to_next;
  l2fwd_next_t next_index;
  l2fwd_main_t *msm = &l2fwd_main;
  vlib_node_t *n = vlib_get_node (vm, l2fwd_node.index);
  CLIB_UNUSED (u32 node_counter_base_index) = n->error_heap_index;
  vlib_error_main_t *em = &vm->error_main;
  l2fib_entry_key_t cached_key;
  l2fib_entry_result_t cached_result;

  /* Clear the one-entry cache in case mac table was updated */
  cached_key.raw = ~0;
  cached_result.raw = ~0;

  from = vlib_frame_vector_args (frame);
  n_left_from = frame->n_vectors;	/* number of packets to process */
  next_index = node->cached_next_index;

  while (n_left_from > 0)
    {
      u32 n_left_to_next;

      /* get space to enqueue frame to graph node "next_index" */
      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);

      while (n_left_from >= 8 && n_left_to_next >= 4)
	{
	  u32 bi0, bi1, bi2, bi3;
	  vlib_buffer_t *b0, *b1, *b2, *b3;
	  u32 next0, next1, next2, next3;
	  u32 sw_if_index0, sw_if_index1, sw_if_index2, sw_if_index3;
	  ethernet_header_t *h0, *h1, *h2, *h3;
	  l2fib_entry_key_t key0, key1, key2, key3;
	  l2fib_entry_result_t result0, result1, result2, result3;
	  u32 bucket0, bucket1, bucket2, bucket3;

	  /* Prefetch next iteration. */
	  {
	    vlib_buffer_t *p4, *p5, *p6, *p7;

	    p4 = vlib_get_buffer (vm, from[4]);
	    p5 = vlib_get_buffer (vm, from[5]);
	    p6 = vlib_get_buffer (vm, from[6]);
	    p7 = vlib_get_buffer (vm, from[7]);

	    vlib_prefetch_buffer_header (p4, LOAD);
	    vlib_prefetch_buffer_header (p5, LOAD);
	    vlib_prefetch_buffer_header (p6, LOAD);
	    vlib_prefetch_buffer_header (p7, LOAD);

	    CLIB_PREFETCH (p4->data, CLIB_CACHE_LINE_BYTES, STORE);
	    CLIB_PREFETCH (p5->data, CLIB_CACHE_LINE_BYTES, STORE);
	    CLIB_PREFETCH (p6->data, CLIB_CACHE_LINE_BYTES, STORE);
	    CLIB_PREFETCH (p7->data, CLIB_CACHE_LINE_BYTES, STORE);
	  }

	  /* speculatively enqueue b0 and b1 to the current next frame */
	  /* bi is "buffer index", b is pointer to the buffer */
	  to_next[0] = bi0 = from[0];
	  to_next[1] = bi1 = from[1];
	  to_next[2] = bi2 = from[2];
	  to_next[3] = bi3 = from[3];
	  from += 4;
	  to_next += 4;
	  n_left_from -= 4;
	  n_left_to_next -= 4;

	  b0 = vlib_get_buffer (vm, bi0);
	  b1 = vlib_get_buffer (vm, bi1);
	  b2 = vlib_get_buffer (vm, bi2);
	  b3 = vlib_get_buffer (vm, bi3);

	  /* RX interface handles */
	  sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
	  sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
	  sw_if_index2 = vnet_buffer (b2)->sw_if_index[VLIB_RX];
	  sw_if_index3 = vnet_buffer (b3)->sw_if_index[VLIB_RX];

	  h0 = vlib_buffer_get_current (b0);
	  h1 = vlib_buffer_get_current (b1);
	  h2 = vlib_buffer_get_current (b2);
	  h3 = vlib_buffer_get_current (b3);

	  if (do_trace)
	    {
	      if (b0->flags & VLIB_BUFFER_IS_TRACED)
		{
		  l2fwd_trace_t *t =
		    vlib_add_trace (vm, node, b0, sizeof (*t));
		  t->sw_if_index = sw_if_index0;
		  t->bd_index = vnet_buffer (b0)->l2.bd_index;
		  clib_memcpy (t->src, h0->src_address, 6);
		  clib_memcpy (t->dst, h0->dst_address, 6);
		}
	      if (b1->flags & VLIB_BUFFER_IS_TRACED)
		{
		  l2fwd_trace_t *t =
		    vlib_add_trace (vm, node, b1, sizeof (*t));
		  t->sw_if_index = sw_if_index1;
		  t->bd_index = vnet_buffer (b1)->l2.bd_index;
		  clib_memcpy (t->src, h1->src_address, 6);
		  clib_memcpy (t->dst, h1->dst_address, 6);
		}
	      if (b2->flags & VLIB_BUFFER_IS_TRACED)
		{
		  l2fwd_trace_t *t =
		    vlib_add_trace (vm, node, b2, sizeof (*t));
		  t->sw_if_index = sw_if_index2;
		  t->bd_index = vnet_buffer (b2)->l2.bd_index;
		  clib_memcpy (t->src, h2->src_address, 6);
		  clib_memcpy (t->dst, h2->dst_address, 6);
		}
	      if (b3->flags & VLIB_BUFFER_IS_TRACED)
		{
		  l2fwd_trace_t *t =
		    vlib_add_trace (vm, node, b3, sizeof (*t));
		  t->sw_if_index = sw_if_index3;
		  t->bd_index = vnet_buffer (b3)->l2.bd_index;
		  clib_memcpy (t->src, h3->src_address, 6);
		  clib_memcpy (t->dst, h3->dst_address, 6);
		}
	    }

	  /* process 2 pkts */
#ifdef COUNTERS
	  em->counters[node_counter_base_index + L2FWD_ERROR_L2FWD] += 4;
#endif
	  /* *INDENT-OFF* */
	  l2fib_lookup_4 (msm->mac_table, &cached_key, &cached_result,
			  h0->dst_address, h1->dst_address,
			  h2->dst_address, h3->dst_address,
			  vnet_buffer (b0)->l2.bd_index,
			  vnet_buffer (b1)->l2.bd_index,
			  vnet_buffer (b2)->l2.bd_index,
			  vnet_buffer (b3)->l2.bd_index,
			  &key0,	/* not used */
			  &key1,	/* not used */
			  &key2,	/* not used */
			  &key3,	/* not used */
			  &bucket0,	/* not used */
			  &bucket1,	/* not used */
			  &bucket2,	/* not used */
			  &bucket3,	/* not used */
			  &result0,
			  &result1,
			  &result2,
			  &result3);
	  /* *INDENT-ON* */
	  l2fwd_process (vm, node, msm, em, b0, sw_if_index0, &result0,
			 &next0);
	  l2fwd_process (vm, node, msm, em, b1, sw_if_index1, &result1,
			 &next1);
	  l2fwd_process (vm, node, msm, em, b2, sw_if_index2, &result2,
			 &next2);
	  l2fwd_process (vm, node, msm, em, b3, sw_if_index3, &result3,
			 &next3);

	  /* verify speculative enqueues, maybe switch current next frame */
	  /* if next0==next1==next_index then nothing special needs to be done */
	  vlib_validate_buffer_enqueue_x4 (vm, node, next_index,
					   to_next, n_left_to_next,
					   bi0, bi1, bi2, bi3,
					   next0, next1, next2, next3);
	}

      while (n_left_from > 0 && n_left_to_next > 0)
	{
	  u32 bi0;
	  vlib_buffer_t *b0;
	  u32 next0;
	  u32 sw_if_index0;
	  ethernet_header_t *h0;
	  l2fib_entry_key_t key0;
	  l2fib_entry_result_t result0;
	  u32 bucket0;

	  /* speculatively enqueue b0 to the current next frame */
	  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];

	  h0 = vlib_buffer_get_current (b0);

	  if (do_trace && PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
	    {
	      l2fwd_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
	      t->sw_if_index = sw_if_index0;
	      t->bd_index = vnet_buffer (b0)->l2.bd_index;
	      clib_memcpy (t->src, h0->src_address, 6);
	      clib_memcpy (t->dst, h0->dst_address, 6);
	    }

	  /* process 1 pkt */
#ifdef COUNTERS
	  em->counters[node_counter_base_index + L2FWD_ERROR_L2FWD] += 1;
#endif
	  l2fib_lookup_1 (msm->mac_table, &cached_key, &cached_result, h0->dst_address, vnet_buffer (b0)->l2.bd_index, &key0,	/* not used */
			  &bucket0,	/* not used */
			  &result0);
	  l2fwd_process (vm, node, msm, em, b0, sw_if_index0, &result0,
			 &next0);

	  /* verify speculative enqueue, maybe switch current next frame */
	  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;
}

static uword
l2fwd_node_fn (vlib_main_t * vm,
	       vlib_node_runtime_t * node, vlib_frame_t * frame)
{
  if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
    return l2fwd_node_inline (vm, node, frame, 1 /* do_trace */ );
  return l2fwd_node_inline (vm, node, frame, 0 /* do_trace */ );
}

/* *INDENT-OFF* */
VLIB_REGISTER_NODE (l2fwd_node,static) = {
  .function = l2fwd_node_fn,
  .name = "l2-fwd",
  .vector_size = sizeof (u32),
  .format_trace = format_l2fwd_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

  .n_errors = ARRAY_LEN(l2fwd_error_strings),
  .error_strings = l2fwd_error_strings,

  .n_next_nodes = L2FWD_N_NEXT,

  /* edit / add dispositions here */
  .next_nodes = {
    [L2FWD_NEXT_L2_OUTPUT] = "l2-output",
    [L2FWD_NEXT_DROP] = "error-drop",
  },
};
/* *INDENT-ON* */

VLIB_NODE_FUNCTION_MULTIARCH (l2fwd_node, l2fwd_node_fn)
     clib_error_t *l2fwd_init (vlib_main_t * vm)
{
  l2fwd_main_t *mp = &l2fwd_main;

  mp->vlib_main = vm;
  mp->vnet_main = vnet_get_main ();

  /* Initialize the feature next-node indexes */
  feat_bitmap_init_next_nodes (vm,
			       l2fwd_node.index,
			       L2INPUT_N_FEAT,
			       l2input_get_feat_names (),
			       mp->feat_next_node_index);

  /* init the hash table ptr */
  mp->mac_table = get_mac_table ();

  /* Initialize the next nodes for each ethertype */
  next_by_ethertype_init (&mp->l3_next);

  return 0;
}

VLIB_INIT_FUNCTION (l2fwd_init);


/** Add the L3 input node for this ethertype to the next nodes structure. */
void
l2fwd_register_input_type (vlib_main_t * vm,
			   ethernet_type_t type, u32 node_index)
{
  l2fwd_main_t *mp = &l2fwd_main;
  u32 next_index;

  next_index = vlib_node_add_next (vm, l2fwd_node.index, node_index);

  next_by_ethertype_register (&mp->l3_next, type, next_index);
}


/**
 * Set subinterface forward enable/disable.
 * The CLI format is:
 *   set interface l2 forward <interface> [disable]
 */
static clib_error_t *
int_fwd (vlib_main_t * vm, unformat_input_t * input, vlib_cli_command_t * cmd)
{
  vnet_main_t *vnm = vnet_get_main ();
  clib_error_t *error = 0;
  u32 sw_if_index;
  u32 enable;

  if (!unformat_user (input, unformat_vnet_sw_interface, vnm, &sw_if_index))
    {
      error = clib_error_return (0, "unknown interface `%U'",
				 format_unformat_error, input);
      goto done;
    }

  enable = 1;
  if (unformat (input, "disable"))
    {
      enable = 0;
    }

  /* set the interface flag */
  if (l2input_intf_config (sw_if_index)->xconnect)
    {
      l2input_intf_bitmap_enable (sw_if_index, L2INPUT_FEAT_XCONNECT, enable);
    }
  else
    {
      l2input_intf_bitmap_enable (sw_if_index, L2INPUT_FEAT_FWD, enable);
    }

done:
  return error;
}

/*?
 * Layer 2 unicast forwarding can be enabled and disabled on each
 * interface and on each bridge-domain. Use this command to
 * manage interfaces. It is enabled by default.
 *
 * @cliexpar
 * Example of how to enable fowarding:
 * @cliexcmd{set interface l2 forward GigabitEthernet0/8/0}
 * Example of how to disable fowarding:
 * @cliexcmd{set interface l2 forward GigabitEthernet0/8/0 disable}
?*/
/* *INDENT-OFF* */
VLIB_CLI_COMMAND (int_fwd_cli, static) = {
  .path = "set interface l2 forward",
  .short_help = "set interface l2 forward <interface> [disable]",
  .function = int_fwd,
};
/* *INDENT-ON* */

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