/*
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/*
 * decap.c : IPSec tunnel decapsulation
 *
 * 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.
 */

#include <vnet/vnet.h>
#include <vnet/api_errno.h>
#include <vnet/ip/ip.h>

#include <vnet/ipsec/ipsec.h>
#include <vnet/ipsec/esp.h>

#define foreach_ipsec_input_next                \
_(DROP, "error-drop")                           \
_(ESP_DECRYPT, "esp-decrypt")

#define _(v, s) IPSEC_INPUT_NEXT_##v,
typedef enum {
  foreach_ipsec_input_next
#undef _
  IPSEC_INPUT_N_NEXT,
} ipsec_input_next_t;


#define foreach_ipsec_input_error                   \
 _(RX_PKTS, "IPSEC pkts received")                  \
 _(DECRYPTION_FAILED, "IPSEC decryption failed")


typedef enum {
#define _(sym,str) IPSEC_INPUT_ERROR_##sym,
  foreach_ipsec_input_error
#undef _
  IPSEC_INPUT_N_ERROR,
} ipsec_input_error_t;

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

typedef struct {
  u32 tunnel_index;
  u32 spi;
  u32 seq;
} ipsec_input_trace_t;

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

  if (t->tunnel_index != ~0)
  {
    s = format (s, "esp: tunnel %u spi %u seq %u", t->tunnel_index, t->spi, t->seq);
  }
  else
  {
    s = format (s, "esp: no tunnel spi %u seq %u",t->spi, t->seq);
  }
  return s;
}

always_inline ipsec_policy_t *
ipsec_input_protect_policy_match(ipsec_spd_t * spd, u32 sa, u32 da, u32 spi)
{
  ipsec_main_t *im = &ipsec_main;
  ipsec_policy_t * p;
  ipsec_sa_t * s;
  u32 * i;

  vec_foreach(i, spd->ipv4_inbound_protect_policy_indices)
    {
      p = pool_elt_at_index(spd->policies, *i);
      s = pool_elt_at_index(im->sad, p->sa_index);

      if (spi != s->spi)
      	continue;

      if (s->is_tunnel)
        {
           if (da != clib_net_to_host_u32(s->tunnel_dst_addr.ip4.as_u32))
               continue;

           if (sa != clib_net_to_host_u32(s->tunnel_src_addr.ip4.as_u32))
               continue;

           return p;
        }

      if (da < clib_net_to_host_u32(p->laddr.start.ip4.as_u32))
      	continue;

      if (da > clib_net_to_host_u32(p->laddr.stop.ip4.as_u32))
      	continue;

      if (sa < clib_net_to_host_u32(p->raddr.start.ip4.as_u32))
      	continue;

      if (sa > clib_net_to_host_u32(p->raddr.stop.ip4.as_u32))
      	continue;

      return p;
    }
    return 0;
}

always_inline uword
ip6_addr_match_range (ip6_address_t * a, ip6_address_t * la, ip6_address_t * ua)
{
  if ((memcmp(a->as_u64, la->as_u64, 2 * sizeof(u64)) >= 0) &&
      (memcmp(a->as_u64, ua->as_u64, 2 * sizeof(u64)) <= 0))
    return 1;
  return 0;
}

always_inline ipsec_policy_t *
ipsec_input_ip6_protect_policy_match (ipsec_spd_t * spd,
                                      ip6_address_t * sa,
                                      ip6_address_t * da,
                                      u32 spi)
{
  ipsec_main_t *im = &ipsec_main;
  ipsec_policy_t * p;
  ipsec_sa_t * s;
  u32 * i;

  vec_foreach(i, spd->ipv6_inbound_protect_policy_indices)
    {
      p = pool_elt_at_index(spd->policies, *i);
      s = pool_elt_at_index(im->sad, p->sa_index);

      if (spi != s->spi)
        continue;

      if (s->is_tunnel)
        {
          if (!ip6_address_is_equal(sa, &s->tunnel_src_addr.ip6))
            continue;

          if (!ip6_address_is_equal(da, &s->tunnel_dst_addr.ip6))
            continue;

          return p;
        }

      if (!ip6_addr_match_range(sa, &p->raddr.start.ip6, &p->raddr.stop.ip6))
        continue;

      if (!ip6_addr_match_range(da, &p->laddr.start.ip6, &p->laddr.stop.ip6))
        continue;

      return p;
    }
    return 0;
}

static vlib_node_registration_t ipsec_input_ip4_node;

static uword
ipsec_input_ip4_node_fn (vlib_main_t * vm,
		         vlib_node_runtime_t * node,
		         vlib_frame_t * from_frame)
{
  ip4_main_t * i4m = &ip4_main;
  ip_lookup_main_t * lm = &i4m->lookup_main;
  ip_config_main_t * cm = &lm->rx_config_mains[VNET_UNICAST];
  u32 n_left_from, *from, next_index, *to_next;
  ipsec_main_t *im = &ipsec_main;

  from = vlib_frame_vector_args (from_frame);
  n_left_from = 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);

      while (n_left_from > 0 && n_left_to_next > 0)
        {
          u32 bi0, next0;
          vlib_buffer_t * b0;
          ip4_header_t *ip0;
          esp_header_t *esp0;
          ip4_ipsec_config_t * c0;
          u32 tunnel_index0 = ~0;
          ipsec_spd_t * spd0;

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

          b0 = vlib_get_buffer (vm, bi0);
          c0 = vnet_get_config_data (&cm->config_main,
                                     &b0->current_config_index,
                                     &next0, sizeof (c0[0]));

          spd0 = pool_elt_at_index(im->spds, c0->spd_index);

          ip0 = vlib_buffer_get_current (b0);
          esp0 = (esp_header_t *) ((u8 *) ip0 + ip4_header_bytes (ip0));

          if (PREDICT_TRUE(ip0->protocol == IP_PROTOCOL_IPSEC_ESP))
            {
#if 0
              clib_warning("packet received from %U to %U spi %u size %u spd_id %u",
                           format_ip4_address, ip0->src_address.as_u8,
                           format_ip4_address, ip0->dst_address.as_u8,
                           clib_net_to_host_u32(esp0->spi),
                           clib_net_to_host_u16(ip0->length),
                           spd0->id);
#endif
              ipsec_policy_t * p0;
              p0 = ipsec_input_protect_policy_match(spd0,
                         clib_net_to_host_u32(ip0->src_address.as_u32),
                         clib_net_to_host_u32(ip0->dst_address.as_u32),
                         clib_net_to_host_u32(esp0->spi));

              if (PREDICT_TRUE(p0 != 0))
                {
                  p0->counter.packets++;
                  p0->counter.bytes += clib_net_to_host_u16(ip0->length);
                  vnet_buffer(b0)->output_features.ipsec_sad_index = p0->sa_index;
                  next0 = IPSEC_INPUT_NEXT_ESP_DECRYPT;
                  vlib_buffer_advance(b0, ip4_header_bytes (ip0));
                  goto trace0;
                }
            }

          /* FIXME bypass and discard */

trace0:
          if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED)) {
            ipsec_input_trace_t *tr = vlib_add_trace (vm, node, b0, sizeof (*tr));
            tr->tunnel_index = tunnel_index0;
            tr->spi = clib_host_to_net_u32(esp0->spi);
            tr->seq = clib_host_to_net_u32(esp0->seq);
          }

	        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, ipsec_input_ip4_node.index,
                               IPSEC_INPUT_ERROR_RX_PKTS,
                               from_frame->n_vectors);

  return from_frame->n_vectors;
}


VLIB_REGISTER_NODE (ipsec_input_ip4_node,static) = {
  .function = ipsec_input_ip4_node_fn,
  .name = "ipsec-input-ip4",
  .vector_size = sizeof (u32),
  .format_trace = format_ipsec_input_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

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

  .n_next_nodes = IPSEC_INPUT_N_NEXT,
  .next_nodes = {
#define _(s,n) [IPSEC_INPUT_NEXT_##s] = n,
    foreach_ipsec_input_next
#undef _
  },
};

VLIB_NODE_FUNCTION_MULTIARCH (ipsec_input_ip4_node,
			      ipsec_input_ip4_node_fn)


static vlib_node_registration_t ipsec_input_ip6_node;

static uword
ipsec_input_ip6_node_fn (vlib_main_t * vm,
                         vlib_node_runtime_t * node,
                         vlib_frame_t * from_frame)
{
  ip6_main_t * i6m = &ip6_main;
  ip_lookup_main_t * lm = &i6m->lookup_main;
  ip_config_main_t * cm = &lm->rx_config_mains[VNET_UNICAST];
  u32 n_left_from, *from, next_index, *to_next;
  ipsec_main_t *im = &ipsec_main;

  from = vlib_frame_vector_args (from_frame);
  n_left_from = 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);

      while (n_left_from > 0 && n_left_to_next > 0)
        {
          u32 bi0, next0;
          vlib_buffer_t * b0;
          ip6_header_t *ip0;
          esp_header_t *esp0;
          ip4_ipsec_config_t * c0;
          u32 tunnel_index0 = ~0;
          ipsec_spd_t * spd0;
          u32 header_size = sizeof(ip0[0]);

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

          b0 = vlib_get_buffer (vm, bi0);
          c0 = vnet_get_config_data (&cm->config_main,
                                     &b0->current_config_index,
                                     &next0, sizeof (c0[0]));

          spd0 = pool_elt_at_index(im->spds, c0->spd_index);

          ip0 = vlib_buffer_get_current (b0);
          esp0 = (esp_header_t *) ((u8 *) ip0 + header_size);

          if (PREDICT_TRUE(ip0->protocol == IP_PROTOCOL_IPSEC_ESP))
            {
#if 0
              clib_warning("packet received from %U to %U spi %u size %u spd_id %u",
                           format_ip6_address, &ip0->src_address,
                           format_ip6_address, &ip0->dst_address,
                           clib_net_to_host_u32(esp0->spi),
                           clib_net_to_host_u16(ip0->payload_length) + header_size,
                           spd0->id);
#endif
              ipsec_policy_t * p0;
              p0 = ipsec_input_ip6_protect_policy_match(spd0,
                         &ip0->src_address,
                         &ip0->dst_address,
                         clib_net_to_host_u32(esp0->spi));

              if (PREDICT_TRUE(p0 != 0))
                {
                  p0->counter.packets++;
                  p0->counter.bytes += clib_net_to_host_u16(ip0->payload_length);
                  p0->counter.bytes += header_size;
                  vnet_buffer(b0)->output_features.ipsec_sad_index = p0->sa_index;
                  next0 = IPSEC_INPUT_NEXT_ESP_DECRYPT;
                  vlib_buffer_advance(b0, header_size);
                  goto trace0;
                }
            }

trace0:
          if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED)) {
            ipsec_input_trace_t *tr = vlib_add_trace (vm, node, b0, sizeof (*tr));
            tr->tunnel_index = tunnel_index0;
            tr->spi = clib_host_to_net_u32(esp0->spi);
            tr->seq = clib_host_to_net_u32(esp0->seq);
          }

          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, ipsec_input_ip6_node.index,
                               IPSEC_INPUT_ERROR_RX_PKTS,
                               from_frame->n_vectors);

  return from_frame->n_vectors;
}


VLIB_REGISTER_NODE (ipsec_input_ip6_node,static) = {
  .function = ipsec_input_ip6_node_fn,
  .name = "ipsec-input-ip6",
  .vector_size = sizeof (u32),
  .format_trace = format_ipsec_input_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

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

  .n_next_nodes = IPSEC_INPUT_N_NEXT,
  .next_nodes = {
#define _(s,n) [IPSEC_INPUT_NEXT_##s] = n,
    foreach_ipsec_input_next
#undef _
  },
};

VLIB_NODE_FUNCTION_MULTIARCH (ipsec_input_ip6_node,
			      ipsec_input_ip6_node_fn)