ioam_cache_node.c

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/*
 * Copyright (c) 2017 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.
 */
/*
 * This file implements caching of ioam header and reattaching
 * it in response message by performing request-response matching.
 *  Works for TCP SYN/SYN-ACK.
 * This feature is used for anycast server selection.
 * ioam data thus cached is used to measure and get complete round trip
 * network path to help in server selection.
 * There are 2 graph nodes defined to :
 * 1. process packets that contain iOAM header and cache it
 * 2. process TCP SYN-ACKs and reattach ioam header from the
 *    cache corresponding to TCP-SYN
 * These graph nodes are attached to the vnet graph based on
 * ioam cache and classifier configs.
 * e.g.
 * If db06::06 is the anycast service IP6 address:
 *
 * set ioam ip6 cache
 *
 * Apply this classifier on interface where requests for anycast service are received:
 * classify session acl-hit-next ip6-node ip6-lookup table-index 0 match l3 ip6 dst db06::06
 *    ioam-decap anycast <<< ioam-decap is hooked to cache when set ioam ip6 cache is enabled
 *
 * Apply this classifier on interface where responses from anycast service are received:
 * classify session acl-hit-next ip6-node ip6-add-from-cache-hop-by-hop table-index 0 match l3
 *    ip6 src db06::06 ioam-encap anycast-response
 *
 */
#include <vlib/vlib.h>
#include <vnet/vnet.h>
#include <vnet/pg/pg.h>
#include <vppinfra/error.h>
#include <vnet/ip/ip.h>
#include <ioam/ip6/ioam_cache.h>
#include <vnet/ip/ip6_hop_by_hop.h>
#include <vnet/ip/ip6_hop_by_hop_packet.h>

typedef struct
{
  u32 next_index;
  u32 flow_label;
} cache_trace_t;

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

  s = format (s, "CACHE: flow_label %d, next index %d",
              t->flow_label, t->next_index);
  return s;
}

#define foreach_cache_error \
_(RECORDED, "ip6 iOAM headers cached")

typedef enum
{
#define _(sym,str) CACHE_ERROR_##sym,
  foreach_cache_error
#undef _
    CACHE_N_ERROR,
} cache_error_t;

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

typedef enum
{
  IOAM_CACHE_NEXT_POP_HBYH,
  IOAM_CACHE_N_NEXT,
} cache_next_t;

static uword
ip6_ioam_cache_node_fn (vlib_main_t * vm,
                        vlib_node_runtime_t * node, vlib_frame_t * frame)
{
  u32 n_left_from, *from, *to_next;
  cache_next_t next_index;
  u32 recorded = 0;

  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);
      // TODO: Dual loop
      while (n_left_from > 0 && n_left_to_next > 0)
        {
          u32 bi0;
          vlib_buffer_t *p0;
          u32 next0 = IOAM_CACHE_NEXT_POP_HBYH;
          ip6_header_t *ip0;
          ip6_hop_by_hop_header_t *hbh0;
          tcp_header_t *tcp0;
          u32 tcp_offset0;

          /* speculatively enqueue p0 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;

          p0 = vlib_get_buffer (vm, bi0);
          ip0 = vlib_buffer_get_current (p0);
          if (IP_PROTOCOL_TCP ==
              ip6_locate_header (p0, ip0, IP_PROTOCOL_TCP, &tcp_offset0))
            {
              tcp0 = (tcp_header_t *) ((u8 *) ip0 + tcp_offset0);
              if ((tcp0->flags & TCP_FLAG_SYN) == TCP_FLAG_SYN &&
                  (tcp0->flags & TCP_FLAG_ACK) == 0)
                {
                  /* Cache the ioam hbh header */
                  hbh0 = (ip6_hop_by_hop_header_t *) (ip0 + 1);
                  if (0 == ioam_cache_add (p0,
                                           ip0,
                                           clib_net_to_host_u16
                                           (tcp0->src_port),
                                           clib_net_to_host_u16
                                           (tcp0->dst_port), hbh0,
                                           clib_net_to_host_u32
                                           (tcp0->seq_number) + 1))
                    {
                      recorded++;
                    }
                }
            }
          if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)))
            {
              if (p0->flags & VLIB_BUFFER_IS_TRACED)
                {
                  cache_trace_t *t =
                    vlib_add_trace (vm, node, p0, sizeof (*t));
                  t->flow_label =
                    clib_net_to_host_u32
                    (ip0->ip_version_traffic_class_and_flow_label);
                  t->next_index = 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);
    }

  vlib_node_increment_counter (vm, ioam_cache_node.index,
                               CACHE_ERROR_RECORDED, recorded);
  return frame->n_vectors;
}

/*
 * Node for IP6 iOAM header cache
 */
/* *INDENT-OFF* */
VLIB_REGISTER_NODE (ioam_cache_node) =
{
  .function = ip6_ioam_cache_node_fn,
  .name = "ip6-ioam-cache",
  .vector_size = sizeof (u32),
  .format_trace = format_cache_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN (cache_error_strings),
  .error_strings = cache_error_strings,
  .n_next_nodes = IOAM_CACHE_N_NEXT,
  /* edit / add dispositions here */
  .next_nodes =
  {
    [IOAM_CACHE_NEXT_POP_HBYH] = "ip6-pop-hop-by-hop"
  },
};
/* *INDENT-ON* */

typedef struct
{
  u32 next_index;
} ip6_add_from_cache_hbh_trace_t;

/* packet trace format function */
static u8 *
format_ip6_add_from_cache_hbh_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 *);
  ip6_add_from_cache_hbh_trace_t *t = va_arg (*args,
                                              ip6_add_from_cache_hbh_trace_t
                                              *);

  s = format (s, "IP6_ADD_FROM_CACHE_HBH: next index %d", t->next_index);
  return s;
}

vlib_node_registration_t ip6_add_from_cache_hbh_node;

#define foreach_ip6_add_from_cache_hbh_error \
_(PROCESSED, "Pkts w/ added ip6 hop-by-hop options")

typedef enum
{
#define _(sym,str) IP6_ADD_FROM_CACHE_HBH_ERROR_##sym,
  foreach_ip6_add_from_cache_hbh_error
#undef _
    IP6_ADD_FROM_CACHE_HBH_N_ERROR,
} ip6_add_from_cache_hbh_error_t;

static char *ip6_add_from_cache_hbh_error_strings[] = {
#define _(sym,string) string,
  foreach_ip6_add_from_cache_hbh_error
#undef _
};

#define foreach_ip6_ioam_cache_input_next        \
  _(IP6_LOOKUP, "ip6-lookup")                   \
  _(DROP, "error-drop")

typedef enum
{
#define _(s,n) IP6_IOAM_CACHE_INPUT_NEXT_##s,
  foreach_ip6_ioam_cache_input_next
#undef _
    IP6_IOAM_CACHE_INPUT_N_NEXT,
} ip6_ioam_cache_input_next_t;


static uword
ip6_add_from_cache_hbh_node_fn (vlib_main_t * vm,
                                vlib_node_runtime_t * node,
                                vlib_frame_t * frame)
{
  ioam_cache_main_t *cm = &ioam_cache_main;
  u32 n_left_from, *from, *to_next;
  ip_lookup_next_t next_index;
  u32 processed = 0;
  u8 *rewrite = 0;
  u32 rewrite_len = 0;
  u32 sr_rewrite_len = vec_len (cm->sr_rewrite_template);

  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);
      // TODO: Dual loop
      while (n_left_from > 0 && n_left_to_next > 0)
        {
          u32 bi0;
          vlib_buffer_t *b0;
          u32 next0;
          ip6_header_t *ip0;
          ip6_hop_by_hop_header_t *hbh0;
          ip6_sr_header_t *srh0 = 0;
          u64 *copy_src0, *copy_dst0;
          u16 new_l0;
          tcp_header_t *tcp0;
          u32 tcp_offset0;
          ioam_cache_entry_t *entry = 0;

          next0 = IP6_IOAM_CACHE_INPUT_NEXT_IP6_LOOKUP;
          /* 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);

          ip0 = vlib_buffer_get_current (b0);
          if (IP_PROTOCOL_TCP !=
              ip6_locate_header (b0, ip0, IP_PROTOCOL_TCP, &tcp_offset0))
            {
              goto TRACE0;
            }
          tcp0 = (tcp_header_t *) ((u8 *) ip0 + tcp_offset0);
          if (((tcp0->flags & TCP_FLAG_SYN) == TCP_FLAG_SYN &&
               (tcp0->flags & TCP_FLAG_ACK) == TCP_FLAG_ACK) ||
              (tcp0->flags & TCP_FLAG_RST) == TCP_FLAG_RST)
            {
              if (0 != (entry = ioam_cache_lookup (ip0,
                                                   clib_net_to_host_u16
                                                   (tcp0->src_port),
                                                   clib_net_to_host_u16
                                                   (tcp0->dst_port),
                                                   clib_net_to_host_u32
                                                   (tcp0->ack_number))))
                {
                  rewrite = entry->ioam_rewrite_string;
                  rewrite_len = vec_len (rewrite);
                }
              else
                {
                  next0 = IP6_IOAM_CACHE_INPUT_NEXT_DROP;
                  goto TRACE0;
                }
            }
          else
            goto TRACE0;


          /* Copy the ip header left by the required amount */
          copy_dst0 = (u64 *) (((u8 *) ip0) - (rewrite_len + sr_rewrite_len));
          copy_src0 = (u64 *) ip0;

          copy_dst0[0] = copy_src0[0];
          copy_dst0[1] = copy_src0[1];
          copy_dst0[2] = copy_src0[2];
          copy_dst0[3] = copy_src0[3];
          copy_dst0[4] = copy_src0[4];
          vlib_buffer_advance (b0, -(word) (rewrite_len + sr_rewrite_len));
          ip0 = vlib_buffer_get_current (b0);

          hbh0 = (ip6_hop_by_hop_header_t *) (ip0 + 1);
          srh0 = (ip6_sr_header_t *) ((u8 *) hbh0 + rewrite_len);
          /* $$$ tune, rewrite_len is a multiple of 8 */
          clib_memcpy (hbh0, rewrite, rewrite_len);
          clib_memcpy (srh0, cm->sr_rewrite_template, sr_rewrite_len);
          /* Copy dst address into the DA slot in the segment list */
          clib_memcpy (srh0->segments, ip0->dst_address.as_u64,
                       sizeof (ip6_address_t));
          /* Rewrite the ip6 dst address with the first hop */
          clib_memcpy (ip0->dst_address.as_u64, entry->next_hop.as_u64,
                       sizeof (ip6_address_t));
          clib_memcpy (&srh0->segments[1],
                       (u8 *) hbh0 + entry->my_address_offset,
                       sizeof (ip6_address_t));
          ioam_cache_entry_free (entry);

          /* Patch the protocol chain, insert the h-b-h (type 0) header */
          srh0->protocol = ip0->protocol;
          hbh0->protocol = IPPROTO_IPV6_ROUTE;
          ip0->protocol = 0;
          new_l0 =
            clib_net_to_host_u16 (ip0->payload_length) + rewrite_len +
            sr_rewrite_len;
          ip0->payload_length = clib_host_to_net_u16 (new_l0);
          processed++;
        TRACE0:
          if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
                             && (b0->flags & VLIB_BUFFER_IS_TRACED)))
            {
              ip6_add_from_cache_hbh_trace_t *t =
                vlib_add_trace (vm, node, b0, sizeof (*t));
              t->next_index = 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);
    }

  vlib_node_increment_counter (vm, ip6_add_from_cache_hbh_node.index,
                               IP6_ADD_FROM_CACHE_HBH_ERROR_PROCESSED,
                               processed);
  return frame->n_vectors;
}
/* *INDENT-OFF* */
VLIB_REGISTER_NODE (ip6_add_from_cache_hbh_node) =
{
  .function = ip6_add_from_cache_hbh_node_fn,
  .name = "ip6-add-from-cache-hop-by-hop",
  .vector_size = sizeof (u32),
  .format_trace = format_ip6_add_from_cache_hbh_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN (ip6_add_from_cache_hbh_error_strings),
  .error_strings =  ip6_add_from_cache_hbh_error_strings,
  /* See ip/lookup.h */
  .n_next_nodes = IP6_IOAM_CACHE_INPUT_N_NEXT,
  .next_nodes =
  {
#define _(s,n) [IP6_IOAM_CACHE_INPUT_NEXT_##s] = n,
    foreach_ip6_ioam_cache_input_next
#undef _
  },
};
/* *INDENT-ON* */

VLIB_NODE_FUNCTION_MULTIARCH (ip6_add_from_cache_hbh_node,
                              ip6_add_from_cache_hbh_node_fn)
/*
 * fd.io coding-style-patch-verification: ON
 *
 * Local Variables:
 * eval: (c-set-style "gnu")
 * End:
 */