node.c

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/*
 * 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.
 */
/*
 * llc_node.c: llc packet processing
 *
 * Copyright (c) 2010 Eliot Dresselhaus
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 *  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 *  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 *  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 *  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 *  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 *  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 *  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include <vlib/vlib.h>
#include <vnet/pg/pg.h>
#include <vnet/llc/llc.h>

#define foreach_llc_input_next                  \
  _ (PUNT, "error-punt")                        \
  _ (DROP, "error-drop")

typedef enum {
#define _(s,n) LLC_INPUT_NEXT_##s,
  foreach_llc_input_next
#undef _
  LLC_INPUT_N_NEXT,
} llc_input_next_t;

typedef struct {
  u8 packet_data[32];
} llc_input_trace_t;

static u8 * format_llc_input_trace (u8 * s, va_list * va)
{
  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*va, vlib_main_t *);
  CLIB_UNUSED (vlib_node_t * node) = va_arg (*va, vlib_node_t *);
  llc_input_trace_t * t = va_arg (*va, llc_input_trace_t *);

  s = format (s, "%U", format_llc_header, t->packet_data);

  return s;
}

static uword
llc_input (vlib_main_t * vm,
           vlib_node_runtime_t * node,
           vlib_frame_t * from_frame)
{
  llc_main_t * lm = &llc_main;
  u32 n_left_from, next_index, * from, * to_next;

  from = vlib_frame_vector_args (from_frame);
  n_left_from = from_frame->n_vectors;

  if (node->flags & VLIB_NODE_FLAG_TRACE)
    vlib_trace_frame_buffers_only (vm, node,
                                   from,
                                   n_left_from,
                                   sizeof (from[0]),
                                   sizeof (llc_input_trace_t));

  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;
          llc_header_t * h0, * h1;
          u8 next0, next1, len0, len1, enqueue_code;

          /* Prefetch next iteration. */
          {
            vlib_buffer_t * b2, * b3;

            b2 = vlib_get_buffer (vm, from[2]);
            b3 = vlib_get_buffer (vm, from[3]);

            vlib_prefetch_buffer_header (b2, LOAD);
            vlib_prefetch_buffer_header (b3, LOAD);

            CLIB_PREFETCH (b2->data, sizeof (h0[0]), LOAD);
            CLIB_PREFETCH (b3->data, sizeof (h1[0]), LOAD);
          }

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

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

          h0 = (void *) (b0->data + b0->current_data);
          h1 = (void *) (b1->data + b1->current_data);

          len0 = llc_header_length (h0);
          len1 = llc_header_length (h1);

          b0->current_data += len0;
          b1->current_data += len1;

          b0->current_length -= len0;
          b1->current_length -= len1;

          next0 = lm->input_next_by_protocol[h0->dst_sap];
          next1 = lm->input_next_by_protocol[h1->dst_sap];

          b0->error = node->errors[next0 == LLC_INPUT_NEXT_DROP ? LLC_ERROR_UNKNOWN_PROTOCOL : LLC_ERROR_NONE];
          b1->error = node->errors[next1 == LLC_INPUT_NEXT_DROP ? LLC_ERROR_UNKNOWN_PROTOCOL : LLC_ERROR_NONE];

          enqueue_code = (next0 != next_index) + 2*(next1 != next_index);

          if (PREDICT_FALSE (enqueue_code != 0))
            {
              switch (enqueue_code)
                {
                case 1:
                  /* A B A */
                  to_next[-2] = bi1;
                  to_next -= 1;
                  n_left_to_next += 1;
                  vlib_set_next_frame_buffer (vm, node, next0, bi0);
                  break;

                case 2:
                  /* A A B */
                  to_next -= 1;
                  n_left_to_next += 1;
                  vlib_set_next_frame_buffer (vm, node, next1, bi1);
                  break;

                case 3:
                  /* A B B or A B C */
                  to_next -= 2;
                  n_left_to_next += 2;
                  vlib_set_next_frame_buffer (vm, node, next0, bi0);
                  vlib_set_next_frame_buffer (vm, node, next1, bi1);
                  if (next0 == next1)
                    {
                      vlib_put_next_frame (vm, node, next_index,
                                           n_left_to_next);
                      next_index = next1;
                      vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
                    }
                }
            }
        }
    
      while (n_left_from > 0 && n_left_to_next > 0)
        {
          u32 bi0;
          vlib_buffer_t * b0;
          llc_header_t * h0;
          u8 next0, len0;

          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);

          h0 = (void *) (b0->data + b0->current_data);

          len0 = llc_header_length (h0);

          b0->current_data += len0;

          b0->current_length -= len0;

          next0 = lm->input_next_by_protocol[h0->dst_sap];

          b0->error = node->errors[next0 == LLC_INPUT_NEXT_DROP ? LLC_ERROR_UNKNOWN_PROTOCOL : LLC_ERROR_NONE];

          /* Sent packet to wrong next? */
          if (PREDICT_FALSE (next0 != next_index))
            {
              /* Return old frame; remove incorrectly enqueued packet. */
              vlib_put_next_frame (vm, node, next_index, n_left_to_next + 1);

              /* Send to correct next. */
              next_index = next0;
              vlib_get_next_frame (vm, node, next_index,
                                   to_next, n_left_to_next);

              to_next[0] = bi0;
              to_next += 1;
              n_left_to_next -= 1;
            }
        }

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

  return from_frame->n_vectors;
}

static char * llc_error_strings[] = {
#define _(f,s) s,
  foreach_llc_error
#undef _
};

VLIB_REGISTER_NODE (llc_input_node) = {
  .function = llc_input,
  .name = "llc-input",
  /* Takes a vector of packets. */
  .vector_size = sizeof (u32),

  .n_errors = LLC_N_ERROR,
  .error_strings = llc_error_strings,

  .n_next_nodes = LLC_INPUT_N_NEXT,
  .next_nodes = {
#define _(s,n) [LLC_INPUT_NEXT_##s] = n,
    foreach_llc_input_next
#undef _
  },

  .format_buffer = format_llc_header_with_length,
  .format_trace = format_llc_input_trace,
  .unformat_buffer = unformat_llc_header,
};

static clib_error_t * llc_input_init (vlib_main_t * vm)
{
  llc_main_t * lm = &llc_main;

  {
    clib_error_t * error = vlib_call_init_function (vm, llc_init);
    if (error)
      clib_error_report (error);
  }

  llc_setup_node (vm, llc_input_node.index);

  {
    int i;
    for (i = 0; i < ARRAY_LEN (lm->input_next_by_protocol); i++)
      lm->input_next_by_protocol[i] = LLC_INPUT_NEXT_DROP;
  }

  return 0;
}

VLIB_INIT_FUNCTION (llc_input_init);

void
llc_register_input_protocol (vlib_main_t * vm,
                             llc_protocol_t protocol,
                             u32 node_index)
{
  llc_main_t * lm = &llc_main;
  llc_protocol_info_t * pi;

  {
    clib_error_t * error = vlib_call_init_function (vm, llc_input_init);
    if (error)
      clib_error_report (error);
    /* Otherwise, osi_input_init will wipe out e.g. the snap init */
    error = vlib_call_init_function (vm, osi_input_init);
    if (error)
      clib_error_report (error);
  }

  pi = llc_get_protocol_info (lm, protocol);
  pi->node_index = node_index;
  pi->next_index = vlib_node_add_next (vm, 
                                       llc_input_node.index,
                                       node_index);

  lm->input_next_by_protocol[protocol] = pi->next_index;
}