ip4_input.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.
 */
/*
 * ip/ip4_input.c: IP v4 input node
 *
 * Copyright (c) 2008 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 <vnet/ip/ip.h>
#include <vnet/ethernet/ethernet.h>
#include <vnet/ppp/ppp.h>
#include <vnet/hdlc/hdlc.h>

typedef struct {
  u8 packet_data[64];
} ip4_input_trace_t;

static u8 * format_ip4_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 *);
  ip4_input_trace_t * t = va_arg (*va, ip4_input_trace_t *);

  s = format (s, "%U",
              format_ip4_header,
              t->packet_data, sizeof (t->packet_data));

  return s;
}

typedef enum {
  IP4_INPUT_NEXT_DROP,
  IP4_INPUT_NEXT_PUNT,
  IP4_INPUT_NEXT_LOOKUP,
  IP4_INPUT_NEXT_LOOKUP_MULTICAST,
  IP4_INPUT_NEXT_ICMP_ERROR,
  IP4_INPUT_N_NEXT,
} ip4_input_next_t;

/* Validate IP v4 packets and pass them either to forwarding code
   or drop/punt exception packets. */
always_inline uword
ip4_input_inline (vlib_main_t * vm,
                  vlib_node_runtime_t * node,
                  vlib_frame_t * frame,
                  int verify_checksum)
{
  ip4_main_t * im = &ip4_main;
  vnet_main_t * vnm = vnet_get_main();
  ip_lookup_main_t * lm = &im->lookup_main;
  u32 n_left_from, * from, * to_next;
  ip4_input_next_t next_index;
  vlib_node_runtime_t * error_node = vlib_node_get_runtime (vm, ip4_input_node.index);
  vlib_simple_counter_main_t * cm;
  u32 cpu_index = os_get_cpu_number();

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

  if (node->flags & VLIB_NODE_FLAG_TRACE)
    vlib_trace_frame_buffers_only (vm, node, from, frame->n_vectors,
                                   /* stride */ 1,
                                   sizeof (ip4_input_trace_t));

  cm = vec_elt_at_index (vnm->interface_main.sw_if_counters,
                         VNET_INTERFACE_COUNTER_IP4);

  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)
        {
          vlib_buffer_t * p0, * p1;
          ip4_header_t * ip0, * ip1;
          ip_config_main_t * cm0, * cm1;
          u32 sw_if_index0, pi0, ip_len0, cur_len0, next0;
          u32 sw_if_index1, pi1, ip_len1, cur_len1, next1;
          i32 len_diff0, len_diff1;
          u8 error0, error1, cast0, cast1;

          /* 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, sizeof (ip0[0]), LOAD);
            CLIB_PREFETCH (p3->data, sizeof (ip1[0]), LOAD);
          }

          to_next[0] = pi0 = from[0];
          to_next[1] = pi1 = from[1];
          from += 2;
          to_next += 2;
          n_left_from -= 2;
          n_left_to_next -= 2;

          p0 = vlib_get_buffer (vm, pi0);
          p1 = vlib_get_buffer (vm, pi1);

          ip0 = vlib_buffer_get_current (p0);
          ip1 = vlib_buffer_get_current (p1);

          sw_if_index0 = vnet_buffer (p0)->sw_if_index[VLIB_RX];
          sw_if_index1 = vnet_buffer (p1)->sw_if_index[VLIB_RX];

          cast0 = ip4_address_is_multicast (&ip0->dst_address) ? VNET_MULTICAST : VNET_UNICAST;
          cast1 = ip4_address_is_multicast (&ip1->dst_address) ? VNET_MULTICAST : VNET_UNICAST;

          cm0 = lm->rx_config_mains + cast0;
          cm1 = lm->rx_config_mains + cast1;

          p0->current_config_index = vec_elt (cm0->config_index_by_sw_if_index, sw_if_index0);
          p1->current_config_index = vec_elt (cm1->config_index_by_sw_if_index, sw_if_index1);

          vnet_buffer (p0)->ip.adj_index[VLIB_RX] = ~0;
          vnet_buffer (p1)->ip.adj_index[VLIB_RX] = ~0;

          vnet_get_config_data (&cm0->config_main,
                                &p0->current_config_index,
                                &next0,
                                /* # bytes of config data */ 0);
          vnet_get_config_data (&cm1->config_main,
                                &p1->current_config_index,
                                &next1,
                                /* # bytes of config data */ 0);

          vlib_increment_simple_counter (cm, cpu_index, sw_if_index0, 1);
          vlib_increment_simple_counter (cm, cpu_index, sw_if_index1, 1);

          error0 = error1 = IP4_ERROR_NONE;

          /* Punt packets with options. */
          error0 = (ip0->ip_version_and_header_length & 0xf) != 5 ? IP4_ERROR_OPTIONS : error0;
          error1 = (ip1->ip_version_and_header_length & 0xf) != 5 ? IP4_ERROR_OPTIONS : error1;

          /* Version != 4?  Drop it. */
          error0 = (ip0->ip_version_and_header_length >> 4) != 4 ? IP4_ERROR_VERSION : error0;
          error1 = (ip1->ip_version_and_header_length >> 4) != 4 ? IP4_ERROR_VERSION : error1;

          /* Verify header checksum. */
          if (verify_checksum)
            {
              ip_csum_t sum0, sum1;

              ip4_partial_header_checksum_x1 (ip0, sum0);
              ip4_partial_header_checksum_x1 (ip1, sum1);

              error0 = 0xffff != ip_csum_fold (sum0) ? IP4_ERROR_BAD_CHECKSUM : error0;
              error1 = 0xffff != ip_csum_fold (sum1) ? IP4_ERROR_BAD_CHECKSUM : error1;
            }

          /* Drop fragmentation offset 1 packets. */
          error0 = ip4_get_fragment_offset (ip0) == 1 ? IP4_ERROR_FRAGMENT_OFFSET_ONE : error0;
          error1 = ip4_get_fragment_offset (ip1) == 1 ? IP4_ERROR_FRAGMENT_OFFSET_ONE : error1;

          /* TTL < 1? Drop it. */
          error0 = (ip0->ttl < 1 && cast0 == VNET_UNICAST) ? IP4_ERROR_TIME_EXPIRED : error0;
          error1 = (ip1->ttl < 1 && cast1 == VNET_UNICAST) ? IP4_ERROR_TIME_EXPIRED : error1;

          /* Verify lengths. */
          ip_len0 = clib_net_to_host_u16 (ip0->length);
          ip_len1 = clib_net_to_host_u16 (ip1->length);

          /* IP length must be at least minimal IP header. */
          error0 = ip_len0 < sizeof (ip0[0]) ? IP4_ERROR_TOO_SHORT : error0;
          error1 = ip_len1 < sizeof (ip1[0]) ? IP4_ERROR_TOO_SHORT : error1;

          cur_len0 = vlib_buffer_length_in_chain (vm, p0);
          cur_len1 = vlib_buffer_length_in_chain (vm, p1);

          len_diff0 = cur_len0 - ip_len0;
          len_diff1 = cur_len1 - ip_len1;

          error0 = len_diff0 < 0 ? IP4_ERROR_BAD_LENGTH : error0;
          error1 = len_diff1 < 0 ? IP4_ERROR_BAD_LENGTH : error1;

          p0->error = error_node->errors[error0];
          p1->error = error_node->errors[error1];

      if (PREDICT_FALSE(error0 != IP4_ERROR_NONE))
        {
          if (error0 == IP4_ERROR_TIME_EXPIRED) {
            icmp4_error_set_vnet_buffer(p0, ICMP4_time_exceeded,
                                        ICMP4_time_exceeded_ttl_exceeded_in_transit, 0);
            next0 = IP4_INPUT_NEXT_ICMP_ERROR;
          } else
            next0 = error0 != IP4_ERROR_OPTIONS ? IP4_INPUT_NEXT_DROP : IP4_INPUT_NEXT_PUNT;
        }
      if (PREDICT_FALSE(error1 != IP4_ERROR_NONE))
        {
          if (error1 == IP4_ERROR_TIME_EXPIRED) {
            icmp4_error_set_vnet_buffer(p1, ICMP4_time_exceeded,
                                        ICMP4_time_exceeded_ttl_exceeded_in_transit, 0);
            next1 = IP4_INPUT_NEXT_ICMP_ERROR;
          } else
            next1 = error1 != IP4_ERROR_OPTIONS ? IP4_INPUT_NEXT_DROP : IP4_INPUT_NEXT_PUNT;
        }

          vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
                                           to_next, n_left_to_next,
                                           pi0, pi1, next0, next1);
        }    
      while (n_left_from > 0 && n_left_to_next > 0)
        {
          vlib_buffer_t * p0;
          ip4_header_t * ip0;
          ip_config_main_t * cm0;
          u32 sw_if_index0, pi0, ip_len0, cur_len0, next0;
          i32 len_diff0;
          u8 error0, cast0;

          pi0 = from[0];
          to_next[0] = pi0;
          from += 1;
          to_next += 1;
          n_left_from -= 1;
          n_left_to_next -= 1;

          p0 = vlib_get_buffer (vm, pi0);
          ip0 = vlib_buffer_get_current (p0);

          sw_if_index0 = vnet_buffer (p0)->sw_if_index[VLIB_RX];

          cast0 = ip4_address_is_multicast (&ip0->dst_address) ? VNET_MULTICAST : VNET_UNICAST;
          cm0 = lm->rx_config_mains + cast0;
          p0->current_config_index = vec_elt (cm0->config_index_by_sw_if_index, sw_if_index0);
          vnet_buffer (p0)->ip.adj_index[VLIB_RX] = ~0;
          vnet_get_config_data (&cm0->config_main,
                                &p0->current_config_index,
                                &next0,
                                /* # bytes of config data */ 0);

          vlib_increment_simple_counter (cm, cpu_index, sw_if_index0, 1);

          error0 = IP4_ERROR_NONE;

          /* Punt packets with options. */
          error0 = (ip0->ip_version_and_header_length & 0xf) != 5 ? IP4_ERROR_OPTIONS : error0;

          /* Version != 4?  Drop it. */
          error0 = (ip0->ip_version_and_header_length >> 4) != 4 ? IP4_ERROR_VERSION : error0;

          /* Verify header checksum. */
          if (verify_checksum)
            {
              ip_csum_t sum0;

              ip4_partial_header_checksum_x1 (ip0, sum0);
              error0 = 0xffff != ip_csum_fold (sum0) ? IP4_ERROR_BAD_CHECKSUM : error0;
            }

          /* Drop fragmentation offset 1 packets. */
          error0 = ip4_get_fragment_offset (ip0) == 1 ? IP4_ERROR_FRAGMENT_OFFSET_ONE : error0;

          /* TTL < 1? Drop it. */
          error0 = (ip0->ttl < 1 && cast0 == VNET_UNICAST) ? IP4_ERROR_TIME_EXPIRED : error0;

          /* Verify lengths. */
          ip_len0 = clib_net_to_host_u16 (ip0->length);

          /* IP length must be at least minimal IP header. */
          error0 = ip_len0 < sizeof (ip0[0]) ? IP4_ERROR_TOO_SHORT : error0;

          cur_len0 = vlib_buffer_length_in_chain (vm, p0);
          len_diff0 = cur_len0 - ip_len0;
          error0 = len_diff0 < 0 ? IP4_ERROR_BAD_LENGTH : error0;

          p0->error = error_node->errors[error0];
      if (PREDICT_FALSE(error0 != IP4_ERROR_NONE))
        {
          if (error0 == IP4_ERROR_TIME_EXPIRED) {
            icmp4_error_set_vnet_buffer(p0, ICMP4_time_exceeded,
                                        ICMP4_time_exceeded_ttl_exceeded_in_transit, 0);
            next0 = IP4_INPUT_NEXT_ICMP_ERROR;
          } else
            next0 = error0 != IP4_ERROR_OPTIONS ? IP4_INPUT_NEXT_DROP : IP4_INPUT_NEXT_PUNT;
        }

          vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
                                           to_next, n_left_to_next,
                                           pi0, next0);
        }

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

  return frame->n_vectors;
}

/** \brief IPv4 input node.
    @node ip4-input

    This is the IPv4 input node: validates ip4 header checksums,
    verifies ip header lengths, discards pkts with expired TTLs,
    and sends pkts to the set of ip feature nodes configured on
    the rx interface.

    @param vm vlib_main_t corresponding to the current thread
    @param node vlib_node_runtime_t
    @param frame vlib_frame_t whose contents should be dispatched

    @par Graph mechanics: buffer metadata, next index usage

    @em Uses:
    - ip_config_main_t cm corresponding to each pkt's dst address unicast / 
      multicast status.
    - <code>b->current_config_index</code> corresponding to each pkt's
      rx sw_if_index. 
         - This sets the per-packet graph trajectory, ensuring that
           each packet visits the per-interface features in order.

    - <code>vnet_buffer(b)->sw_if_index[VLIB_RX]</code>
        - Indicates the @c sw_if_index value of the interface that the
          packet was received on.

    @em Sets:
    - <code>vnet_buffer(b)->ip.adj_index[VLIB_TX]</code>
        - The lookup result adjacency index.

    <em>Next Indices:</em>
    - Dispatches pkts to the (first) feature node:
      <code> vnet_get_config_data (... &next0 ...); </code>
      or @c error-drop 
*/
static uword
ip4_input (vlib_main_t * vm,
           vlib_node_runtime_t * node,
           vlib_frame_t * frame)
{
  return ip4_input_inline (vm, node, frame, /* verify_checksum */ 1);
}

static uword
ip4_input_no_checksum (vlib_main_t * vm,
                       vlib_node_runtime_t * node,
                       vlib_frame_t * frame)
{
  return ip4_input_inline (vm, node, frame, /* verify_checksum */ 0);
}

static char * ip4_error_strings[] = {
#define _(sym,string) string,
  foreach_ip4_error
#undef _
};

VLIB_REGISTER_NODE (ip4_input_node) = {
  .function = ip4_input,
  .name = "ip4-input",
  .vector_size = sizeof (u32),

  .n_errors = IP4_N_ERROR,
  .error_strings = ip4_error_strings,

  .n_next_nodes = IP4_INPUT_N_NEXT,
  .next_nodes = {
    [IP4_INPUT_NEXT_DROP] = "error-drop",
    [IP4_INPUT_NEXT_PUNT] = "error-punt",
    [IP4_INPUT_NEXT_LOOKUP] = "ip4-lookup",
    [IP4_INPUT_NEXT_LOOKUP_MULTICAST] = "ip4-lookup-multicast",
    [IP4_INPUT_NEXT_ICMP_ERROR] = "ip4-icmp-error",
  },

  .format_buffer = format_ip4_header,
  .format_trace = format_ip4_input_trace,
};

VLIB_NODE_FUNCTION_MULTIARCH (ip4_input_node, ip4_input)

VLIB_REGISTER_NODE (ip4_input_no_checksum_node,static) = {
  .function = ip4_input_no_checksum,
  .name = "ip4-input-no-checksum",
  .vector_size = sizeof (u32),

  .n_next_nodes = IP4_INPUT_N_NEXT,
  .next_nodes = {
    [IP4_INPUT_NEXT_DROP] = "error-drop",
    [IP4_INPUT_NEXT_PUNT] = "error-punt",
    [IP4_INPUT_NEXT_LOOKUP] = "ip4-lookup",
    [IP4_INPUT_NEXT_LOOKUP_MULTICAST] = "ip4-lookup-multicast",
    [IP4_INPUT_NEXT_ICMP_ERROR] = "ip4-icmp-error",
  },

  .format_buffer = format_ip4_header,
  .format_trace = format_ip4_input_trace,
};

VLIB_NODE_FUNCTION_MULTIARCH (ip4_input_no_checksum_node, ip4_input_no_checksum)

static clib_error_t * ip4_init (vlib_main_t * vm)
{
  clib_error_t * error;

  ethernet_register_input_type (vm, ETHERNET_TYPE_IP4,
                                ip4_input_node.index);
  ppp_register_input_protocol (vm, PPP_PROTOCOL_ip4,
                               ip4_input_node.index);
  hdlc_register_input_protocol (vm, HDLC_PROTOCOL_ip4,
                                ip4_input_node.index);

  {
    pg_node_t * pn;
    pn = pg_get_node (ip4_input_node.index);
    pn->unformat_edit = unformat_pg_ip4_header;
    pn = pg_get_node (ip4_input_no_checksum_node.index);
    pn->unformat_edit = unformat_pg_ip4_header;
  }

  if ((error = vlib_call_init_function (vm, ip4_cli_init)))
    return error;

  if ((error = vlib_call_init_function (vm, ip4_source_check_init)))
    return error;

  if ((error = vlib_call_init_function 
       (vm, ip4_source_and_port_range_check_init)))
    return error;

  /* Set flow hash to something non-zero. */
  ip4_main.flow_hash_seed = 0xdeadbeef;

  /* Default TTL for packets we generate. */
  ip4_main.host_config.ttl = 64;

  return error;
}

VLIB_INIT_FUNCTION (ip4_init);