/*
 * 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 <vppinfra/error.h>
#include <vppinfra/hash.h>
#include <vnet/vnet.h>
#include <vnet/ip/ip.h>
#include <vnet/ethernet/ethernet.h>
#include <vnet/lisp-gpe/lisp_gpe.h>

/* Statistics (not really errors) */
#define foreach_lisp_gpe_encap_error    \
_(ENCAPSULATED, "good packets encapsulated")

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

typedef enum {
#define _(sym,str) LISP_GPE_ENCAP_ERROR_##sym,
    foreach_lisp_gpe_encap_error
#undef _
    LISP_GPE_ENCAP_N_ERROR,
} lisp_gpe_encap_error_t;

typedef enum {
    LISP_GPE_ENCAP_NEXT_IP4_LOOKUP,
    LISP_GPE_ENCAP_NEXT_DROP,
    LISP_GPE_ENCAP_N_NEXT,
} lisp_gpe_encap_next_t;

typedef struct {
  u32 tunnel_index;
} lisp_gpe_encap_trace_t;

u8 * format_lisp_gpe_encap_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 *);
  lisp_gpe_encap_trace_t * t 
      = va_arg (*args, lisp_gpe_encap_trace_t *);

  s = format (s, "LISP-GPE-ENCAP: tunnel %d", t->tunnel_index);
  return s;
}

#define foreach_fixed_header_offset             \
_(0) _(1) _(2) _(3) 

static uword
lisp_gpe_encap (vlib_main_t * vm,
               vlib_node_runtime_t * node,
               vlib_frame_t * from_frame)
{
  u32 n_left_from, next_index, * from, * to_next;
  lisp_gpe_main_t * ngm = &lisp_gpe_main;
  vnet_main_t * vnm = ngm->vnet_main;
  u32 pkts_encapsulated = 0;
  u16 old_l0 = 0;

  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);

#if 0
      while (n_left_from >= 4 && n_left_to_next >= 2)
	{
	  u32 bi0, bi1;
	  vlib_buffer_t * b0, * b1;
	  nsh_unicast_header_t * h0, * h1;
          u32 label0, label1;
	  u32 next0, next1;
	  uword * p0, * p1;

	  /* 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, 2*CLIB_CACHE_LINE_BYTES, LOAD);
	    CLIB_PREFETCH (p3->data, 2*CLIB_CACHE_LINE_BYTES, 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 = vlib_buffer_get_current (b0);
          h1 = vlib_buffer_get_current (b1);
          
          next0 = next1 = NSH_INPUT_NEXT_IP4_INPUT;

          label0 = clib_net_to_host_u32 (h0->label_exp_s_ttl);
          label1 = clib_net_to_host_u32 (h1->label_exp_s_ttl);

	  /* 
	   * Translate label contents into a fib index.
	   * This is a decent sanity check, and guarantees
	   * a sane FIB for the downstream lookup
	   */
          label0 = vnet_nsh_uc_get_label (label0);
          label1 = vnet_nsh_uc_get_label (label1);

          /* If 2xlabels match, and match the 1-wide cache, use it */
          if (label0 == label1 && rt->last_label == label0)
            {
              vnet_buffer(b0)->sw_if_index[VLIB_TX] = rt->last_fib_index;
              vnet_buffer(b1)->sw_if_index[VLIB_TX] = rt->last_fib_index;
            }
          else
            {
              p0 = hash_get (rt->mm->fib_index_by_nsh_label, label0);
              if (PREDICT_FALSE (p0 == 0))
                {
                  next0 = NSH_INPUT_NEXT_DROP;
                  b0->error = node->errors[NSH_ERROR_BAD_LABEL];
                }
              else
                vnet_buffer(b0)->sw_if_index[VLIB_TX] = p0[0];
              
              p1 = hash_get (rt->mm->fib_index_by_nsh_label, label1);
              if (PREDICT_FALSE (p1 == 0))
                {
                  next1 = NSH_INPUT_NEXT_DROP;
                  b1->error = node->errors[NSH_ERROR_BAD_LABEL];
                }
              else
                {
                  vnet_buffer(b1)->sw_if_index[VLIB_TX] = p1[0];
                  rt->last_fib_index = p1[0];
                  rt->last_label = label1;
                }
            }

          if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED)) 
            {
              nsh_rx_trace_t *tr = vlib_add_trace (vm, node, 
                                                   b0, sizeof (*tr));
              tr->label_exp_s_ttl = label0;
            }
          if (PREDICT_FALSE(b1->flags & VLIB_BUFFER_IS_TRACED)) 
            {
              nsh_rx_trace_t *tr = vlib_add_trace (vm, node, 
                                                   b1, sizeof (*tr));
              tr->label_exp_s_ttl = label1;
            }

          vlib_buffer_advance (b0, sizeof (*h0));
          vlib_buffer_advance (b1, sizeof (*h1));

	  vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
					   to_next, n_left_to_next,
					   bi0, bi1, next0, next1);
	}
#endif 
    
      while (n_left_from > 0 && n_left_to_next > 0)
	{
	  u32 bi0;
	  vlib_buffer_t * b0;
	  u32 next0 = LISP_GPE_ENCAP_NEXT_IP4_LOOKUP;
          vnet_hw_interface_t * hi0;
          ip4_header_t * ip0;
          udp_header_t * udp0;
          u64 * copy_src0, * copy_dst0;
          u32 * copy_src_last0, * copy_dst_last0;
          lisp_gpe_tunnel_t * t0;
          u16 new_l0;
          ip_csum_t sum0;

	  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);

          /* 1-wide cache? */
          hi0 = vnet_get_sup_hw_interface 
            (vnm, vnet_buffer(b0)->sw_if_index[VLIB_TX]);

          t0 = pool_elt_at_index (ngm->tunnels, hi0->dev_instance);

          ASSERT(vec_len(t0->rewrite) >= 24);

          /* Apply the rewrite string. $$$$ vnet_rewrite? */
          vlib_buffer_advance (b0, -(word)_vec_len(t0->rewrite));

          ip0 = vlib_buffer_get_current(b0);
          /* Copy the fixed header */
          copy_dst0 = (u64 *) ip0;
          copy_src0 = (u64 *) t0->rewrite;

          ASSERT (sizeof (ip4_udp_lisp_gpe_header_t) == 36);

          /* Copy first 32 octets 8-bytes at a time */
#define _(offs) copy_dst0[offs] = copy_src0[offs];
          foreach_fixed_header_offset;
#undef _
          /* Last 4 octets. Hopefully gcc will be our friend */
          copy_dst_last0 = (u32 *)(&copy_dst0[4]);
          copy_src_last0 = (u32 *)(&copy_src0[4]);
          
          copy_dst_last0[0] = copy_src_last0[0];

          /* fix the <bleep>ing outer-IP checksum */
          sum0 = ip0->checksum;
          /* old_l0 always 0, see the rewrite setup */
          new_l0 = 
            clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b0));
          
          sum0 = ip_csum_update (sum0, old_l0, new_l0, ip4_header_t,
                                 length /* changed member */);
          ip0->checksum = ip_csum_fold (sum0);
          ip0->length = new_l0;
          
          /* Fix UDP length */
          udp0 = (udp_header_t *)(ip0+1);
          new_l0 = clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b0)
                                         - sizeof (*ip0));
          
          udp0->length = new_l0;

          /* Reset to look up tunnel partner in the configured FIB */
          vnet_buffer(b0)->sw_if_index[VLIB_TX] = t0->encap_fib_index;
          pkts_encapsulated ++;

          if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED)) 
            {
              lisp_gpe_encap_trace_t *tr = 
                vlib_add_trace (vm, node, b0, sizeof (*tr));
              tr->tunnel_index = t0 - ngm->tunnels;
            }
	  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, node->node_index, 
                               LISP_GPE_ENCAP_ERROR_ENCAPSULATED, 
                               pkts_encapsulated);
  return from_frame->n_vectors;
}

VLIB_REGISTER_NODE (lisp_gpe_encap_node) = {
  .function = lisp_gpe_encap,
  .name = "lisp-gpe-encap",
  .vector_size = sizeof (u32),
  .format_trace = format_lisp_gpe_encap_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

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

  .n_next_nodes = LISP_GPE_ENCAP_N_NEXT,

  .next_nodes = {
        [LISP_GPE_ENCAP_NEXT_IP4_LOOKUP] = "ip4-lookup",
        [LISP_GPE_ENCAP_NEXT_DROP] = "error-drop",
  },
};