path: root/src/plugins/sflow/node.c

/*
 * Copyright (c) 2024 InMon Corp.
 * 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 <vlibmemory/api.h>
#include <vnet/vnet.h>
#include <vnet/pg/pg.h>
#include <vppinfra/error.h>
#include <sflow/sflow.h>

typedef struct
{
  u32 next_index;
  u32 sw_if_index;
  u8 new_src_mac[6];
  u8 new_dst_mac[6];
} sflow_trace_t;

#ifndef CLIB_MARCH_VARIANT
static u8 *
my_format_mac_address (u8 *s, va_list *args)
{
  u8 *a = va_arg (*args, u8 *);
  return format (s, "%02x:%02x:%02x:%02x:%02x:%02x", a[0], a[1], a[2], a[3],
		 a[4], a[5]);
}

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

  s = format (s, "SFLOW: sw_if_index %d, next index %d\n", t->sw_if_index,
	      t->next_index);
  s = format (s, "  src %U -> dst %U", my_format_mac_address, t->new_src_mac,
	      my_format_mac_address, t->new_dst_mac);
  return s;
}

vlib_node_registration_t sflow_node;

#endif /* CLIB_MARCH_VARIANT */

#ifndef CLIB_MARCH_VARIANT
static char *sflow_error_strings[] = {
#define _(sym, string) string,
  foreach_sflow_error
#undef _
};
#endif /* CLIB_MARCH_VARIANT */

typedef enum
{
  SFLOW_NEXT_ETHERNET_INPUT,
  SFLOW_N_NEXT,
} sflow_next_t;

VLIB_NODE_FN (sflow_node)
(vlib_main_t *vm, vlib_node_runtime_t *node, vlib_frame_t *frame)
{
  u32 n_left_from, *from, *to_next;
  sflow_next_t next_index;

  sflow_main_t *smp = &sflow_main;
  from = vlib_frame_vector_args (frame);
  n_left_from = frame->n_vectors;

  uword thread_index = os_get_thread_index ();
  sflow_per_thread_data_t *sfwk =
    vec_elt_at_index (smp->per_thread_data, thread_index);

  /* note that sfwk->skip==1 means "take the next packet",
     so we never see sfwk->skip==0. */

  u32 pkts = n_left_from;
  if (PREDICT_TRUE (sfwk->skip > pkts))
    {
      /* skip the whole frame-vector */
      sfwk->skip -= pkts;
      sfwk->pool += pkts;
    }
  else
    {
      while (pkts >= sfwk->skip)
	{
	  /* reach in to get the one we want. */
	  vlib_buffer_t *bN = vlib_get_buffer (vm, from[sfwk->skip - 1]);

	  /* Sample this packet header. */
	  u32 hdr = bN->current_length;
	  if (hdr > smp->headerB)
	    hdr = smp->headerB;

	  ethernet_header_t *en = vlib_buffer_get_current (bN);
	  u32 if_index = vnet_buffer (bN)->sw_if_index[VLIB_RX];
	  vnet_hw_interface_t *hw =
	    vnet_get_sup_hw_interface (smp->vnet_main, if_index);
	  if (hw)
	    if_index = hw->hw_if_index;
	  else
	    {
	      // TODO: can we get interfaces that have no hw interface?
	      // If so,  should we ignore the sample?
	    }

	  sflow_sample_t sample = {
	    .samplingN = sfwk->smpN,
	    .input_if_index = if_index,
	    .sampled_packet_size =
	      bN->current_length + bN->total_length_not_including_first_buffer,
	    .header_bytes = hdr
	  };

	  // TODO: what bit in the buffer can we set right here to indicate
	  // that this packet was sampled (and perhaps another bit to say if it
	  // was dropped or sucessfully enqueued)? That way we can check it
	  // below if the packet is traced, and indicate that in the trace
	  // output.

	  // TODO: we end up copying the header twice here. Consider allowing
	  // the enqueue to be just a little more complex.  Like this:
	  // if(!sflow_fifo_enqueue(&sfwk->fifo, &sample, en, hdr).
	  // With headerB==128 that would be memcpy(,,24) plus memcpy(,,128)
	  // instead of the memcpy(,,128) plus memcpy(,,24+256) that we do
	  // here. (We also know that it could be done as a multiple of 8
	  // (aligned) bytes because the sflow_sample_t fields are (6xu32) and
	  // the headerB setting is quantized to the nearest 32 bytes, so there
	  // may be ways to make it even easier for the compiler.)
	  sfwk->smpl++;
	  memcpy (sample.header, en, hdr);
	  if (PREDICT_FALSE (!sflow_fifo_enqueue (&sfwk->fifo, &sample)))
	    sfwk->drop++;

	  pkts -= sfwk->skip;
	  sfwk->pool += sfwk->skip;
	  sfwk->skip = sflow_next_random_skip (sfwk);
	}
      /* We took a sample (or several) from this frame-vector, but now we are
	 skipping the rest. */
      sfwk->skip -= pkts;
      sfwk->pool += pkts;
    }

  /* the rest of this is boilerplate code just to make sure
   * that packets are passed on the same way as they would
   * have been if this node were not enabled.
   * TODO: If there is ever a way to do this in one step
   * (i.e. pass on the whole frame-vector unchanged) then it
   * might help performance.
   */

  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 >= 8 && n_left_to_next >= 4)
	{
	  u32 next0 = SFLOW_NEXT_ETHERNET_INPUT;
	  u32 next1 = SFLOW_NEXT_ETHERNET_INPUT;
	  u32 next2 = SFLOW_NEXT_ETHERNET_INPUT;
	  u32 next3 = SFLOW_NEXT_ETHERNET_INPUT;
	  ethernet_header_t *en0, *en1, *en2, *en3;
	  u32 bi0, bi1, bi2, bi3;
	  vlib_buffer_t *b0, *b1, *b2, *b3;

	  /* 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-b3 to the current next frame */
	  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);

	  /* do this to always pass on to the next node on feature arc */
	  vnet_feature_next (&next0, b0);
	  vnet_feature_next (&next1, b1);
	  vnet_feature_next (&next2, b2);
	  vnet_feature_next (&next3, b3);

	  ASSERT (b0->current_data == 0);
	  ASSERT (b1->current_data == 0);
	  ASSERT (b2->current_data == 0);
	  ASSERT (b3->current_data == 0);

	  en0 = vlib_buffer_get_current (b0);
	  en1 = vlib_buffer_get_current (b1);
	  en2 = vlib_buffer_get_current (b2);
	  en3 = vlib_buffer_get_current (b3);

	  if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
	    {
	      sflow_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
	      t->sw_if_index = vnet_buffer (b0)->sw_if_index[VLIB_RX];
	      t->next_index = next0;
	      clib_memcpy (t->new_src_mac, en0->src_address,
			   sizeof (t->new_src_mac));
	      clib_memcpy (t->new_dst_mac, en0->dst_address,
			   sizeof (t->new_dst_mac));
	    }

	  if (PREDICT_FALSE (b1->flags & VLIB_BUFFER_IS_TRACED))
	    {
	      sflow_trace_t *t = vlib_add_trace (vm, node, b1, sizeof (*t));
	      t->sw_if_index = vnet_buffer (b1)->sw_if_index[VLIB_RX];
	      t->next_index = next1;
	      clib_memcpy (t->new_src_mac, en1->src_address,
			   sizeof (t->new_src_mac));
	      clib_memcpy (t->new_dst_mac, en1->dst_address,
			   sizeof (t->new_dst_mac));
	    }

	  if (PREDICT_FALSE (b2->flags & VLIB_BUFFER_IS_TRACED))
	    {
	      sflow_trace_t *t = vlib_add_trace (vm, node, b2, sizeof (*t));
	      t->sw_if_index = vnet_buffer (b2)->sw_if_index[VLIB_RX];
	      t->next_index = next2;
	      clib_memcpy (t->new_src_mac, en2->src_address,
			   sizeof (t->new_src_mac));
	      clib_memcpy (t->new_dst_mac, en2->dst_address,
			   sizeof (t->new_dst_mac));
	    }

	  if (PREDICT_FALSE (b3->flags & VLIB_BUFFER_IS_TRACED))
	    {
	      sflow_trace_t *t = vlib_add_trace (vm, node, b3, sizeof (*t));
	      t->sw_if_index = vnet_buffer (b3)->sw_if_index[VLIB_RX];
	      t->next_index = next3;
	      clib_memcpy (t->new_src_mac, en3->src_address,
			   sizeof (t->new_src_mac));
	      clib_memcpy (t->new_dst_mac, en3->dst_address,
			   sizeof (t->new_dst_mac));
	    }

	  /* verify speculative enqueues, maybe switch current next frame */
	  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 = SFLOW_NEXT_ETHERNET_INPUT;
	  ethernet_header_t *en0;

	  /* 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);

	  /* do this to always pass on to the next node on feature arc */
	  vnet_feature_next (&next0, b0);

	  /*
	   * Direct from the driver, we should be at offset 0
	   * aka at &b0->data[0]
	   */
	  ASSERT (b0->current_data == 0);

	  en0 = vlib_buffer_get_current (b0);

	  if (PREDICT_FALSE (b0->flags & VLIB_BUFFER_IS_TRACED))
	    {
	      sflow_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
	      t->sw_if_index = vnet_buffer (b0)->sw_if_index[VLIB_RX];
	      t->next_index = next0;
	      clib_memcpy (t->new_src_mac, en0->src_address,
			   sizeof (t->new_src_mac));
	      clib_memcpy (t->new_dst_mac, en0->dst_address,
			   sizeof (t->new_dst_mac));
	    }

	  /* 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;
}

#ifndef CLIB_MARCH_VARIANT
VLIB_REGISTER_NODE (sflow_node) =
{
  .name = "sflow",
  .vector_size = sizeof (u32),
  .format_trace = format_sflow_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN(sflow_error_strings),
  .error_strings = sflow_error_strings,
  .n_next_nodes = SFLOW_N_NEXT,
  /* edit / add dispositions here */
  .next_nodes = {
    [SFLOW_NEXT_ETHERNET_INPUT] = "ethernet-input",
  },
};
#endif /* CLIB_MARCH_VARIANT */
/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */