/*
 * 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.
 */
/*
 * flow_report.c
 */
#include <vnet/flow/flow_report.h>
#include <vnet/api_errno.h>

flow_report_main_t flow_report_main;

static_always_inline u8 stream_index_valid (u32 index)
{
  flow_report_main_t * frm = &flow_report_main;
  return index < vec_len(frm->streams) &&
         frm->streams[index].domain_id != ~0;
}

static_always_inline flow_report_stream_t * add_stream (void)
{
  flow_report_main_t * frm = &flow_report_main;
  u32 i;
  for (i = 0; i < vec_len(frm->streams); i++)
    if (!stream_index_valid(i))
      return &frm->streams[i];
  u32 index = vec_len(frm->streams);
  vec_validate(frm->streams, index);
  return &frm->streams[index];
}

static_always_inline void delete_stream (u32 index)
{
  flow_report_main_t * frm = &flow_report_main;
  ASSERT (index < vec_len(frm->streams));
  ASSERT (frm->streams[index].domain_id != ~0);
  frm->streams[index].domain_id = ~0;
}

static i32 find_stream (u32 domain_id, u16 src_port)
{
  flow_report_main_t * frm = &flow_report_main;
  flow_report_stream_t * stream;
  u32 i;
  for (i = 0; i < vec_len(frm->streams); i++)
    if (stream_index_valid(i)) {
      stream = &frm->streams[i];
      if (domain_id == stream->domain_id) {
        if (src_port != stream->src_port)
          return -2;
        return i;
      } else if (src_port == stream->src_port) {
        return -2;
      }
    }
  return -1;
}

int send_template_packet (flow_report_main_t *frm, 
                          flow_report_t *fr,
                          u32 * buffer_indexp)
{
  u32 bi0;
  vlib_buffer_t * b0;
  ip4_ipfix_template_packet_t * tp;
  ipfix_message_header_t * h;
  ip4_header_t * ip;
  udp_header_t * udp;
  vlib_main_t * vm = frm->vlib_main;
  flow_report_stream_t * stream;

  ASSERT (buffer_indexp);

  if (fr->update_rewrite || fr->rewrite == 0)
    {
      if (frm->ipfix_collector.as_u32 == 0 
          || frm->src_address.as_u32 == 0)
        {
          clib_warning ("no collector: disabling flow collector process");
          vlib_node_set_state (frm->vlib_main, flow_report_process_node.index,
                               VLIB_NODE_STATE_DISABLED);
          return -1;
        }
      vec_free (fr->rewrite);
      fr->update_rewrite = 1;
    }

  if (fr->update_rewrite)
    {
      fr->rewrite = fr->rewrite_callback (frm, fr,
                                          &frm->ipfix_collector,
                                          &frm->src_address,
                                          frm->collector_port);
      fr->update_rewrite = 0;
    }

  if (vlib_buffer_alloc (vm, &bi0, 1) != 1)
    return -1;
  
  b0 = vlib_get_buffer (vm, bi0);

  ASSERT (vec_len (fr->rewrite) < VLIB_BUFFER_DEFAULT_FREE_LIST_BYTES);
    
  clib_memcpy (b0->data, fr->rewrite, vec_len (fr->rewrite));
  b0->current_data = 0;
  b0->current_length = vec_len (fr->rewrite);
  b0->flags |= VLIB_BUFFER_TOTAL_LENGTH_VALID;
  vnet_buffer (b0)->sw_if_index[VLIB_RX] = 0;
  vnet_buffer (b0)->sw_if_index[VLIB_TX] = frm->fib_index;

  tp = vlib_buffer_get_current (b0);
  ip = (ip4_header_t *) &tp->ip4;
  udp = (udp_header_t *) (ip+1);
  h = (ipfix_message_header_t *)(udp+1);

  /* FIXUP: message header export_time */ 
  h->export_time = (u32) 
    (((f64)frm->unix_time_0) + 
     (vlib_time_now(frm->vlib_main) - frm->vlib_time_0));
  h->export_time = clib_host_to_net_u32(h->export_time);

  stream = &frm->streams[fr->stream_index];

  /* FIXUP: message header sequence_number. Templates do not increase it */
  h->sequence_number = clib_host_to_net_u32(stream->sequence_number);

  /* FIXUP: udp length */
  udp->length = clib_host_to_net_u16 (b0->current_length - sizeof (*ip));

  if (frm->udp_checksum)
    {
      /* RFC 7011 section 10.3.2. */
      udp->checksum = ip4_tcp_udp_compute_checksum (vm, b0, ip);
      if (udp->checksum == 0)
        udp->checksum = 0xffff;
    }

  *buffer_indexp = bi0;

  fr->last_template_sent = vlib_time_now (vm);

  return 0;
}

static uword
flow_report_process (vlib_main_t * vm,
                     vlib_node_runtime_t * rt,
                     vlib_frame_t * f)
{
  flow_report_main_t * frm = &flow_report_main;
  flow_report_t * fr;
  u32 ip4_lookup_node_index;
  vlib_node_t * ip4_lookup_node;
  vlib_frame_t * nf = 0;
  u32 template_bi;
  u32 * to_next;
  int send_template;
  f64 now;
  int rv;
  uword event_type;
  uword *event_data = 0;

  /* Wait for Godot... */
  vlib_process_wait_for_event_or_clock (vm, 1e9);
  event_type = vlib_process_get_events (vm, &event_data);
  if (event_type != 1)
      clib_warning ("bogus kickoff event received, %d", event_type);
  vec_reset_length (event_data);

  /* Enqueue pkts to ip4-lookup */
  ip4_lookup_node = vlib_get_node_by_name (vm, (u8 *) "ip4-lookup");
  ip4_lookup_node_index = ip4_lookup_node->index;

  while (1) 
    {
      vlib_process_suspend (vm, 5.0);
      
      vec_foreach (fr, frm->reports)
        {
          now = vlib_time_now (vm);

          /* Need to send a template packet? */
          send_template =
              now > (fr->last_template_sent + frm->template_interval);
          send_template += fr->last_template_sent == 0;
          template_bi = ~0;
	  rv = 0;

          if (send_template)
            rv = send_template_packet (frm, fr, &template_bi);

          if (rv < 0)
            continue;

          nf = vlib_get_frame_to_node (vm, ip4_lookup_node_index);
          nf->n_vectors = 0;
          to_next = vlib_frame_vector_args (nf);

          if (template_bi != ~0)
            {
              to_next[0] = template_bi;
              to_next++;
              nf->n_vectors++;
            }
      
          nf = fr->flow_data_callback (frm, fr, 
                                       nf, to_next, ip4_lookup_node_index);
          if (nf)
            vlib_put_frame_to_node (vm, ip4_lookup_node_index, nf);
        }
    }

  return 0; /* not so much */
}

VLIB_REGISTER_NODE (flow_report_process_node) = {
    .function = flow_report_process,
    .type = VLIB_NODE_TYPE_PROCESS,
    .name = "flow-report-process",
};

int vnet_flow_report_add_del (flow_report_main_t *frm, 
                              vnet_flow_report_add_del_args_t *a)
{
  int i;
  int found_index = ~0;
  flow_report_t *fr;
  flow_report_stream_t * stream;
  u32 si;
  
  si = find_stream(a->domain_id, a->src_port);
  if (si == -2)
    return VNET_API_ERROR_INVALID_VALUE;
  if (si == -1 && a->is_add == 0)
    return VNET_API_ERROR_NO_SUCH_ENTRY;

  for (i = 0; i < vec_len(frm->reports); i++)
    {
      fr = vec_elt_at_index (frm->reports, i);
      if (fr->opaque.as_uword == a->opaque.as_uword
          && fr->rewrite_callback == a->rewrite_callback
          && fr->flow_data_callback == a->flow_data_callback)
        {
          found_index = i;
          break;
        }
    }

  if (a->is_add == 0)
    {
      if (found_index != ~0)
        {
          vec_delete (frm->reports, 1, found_index);
          stream = &frm->streams[si];
          stream->n_reports--;
          if (stream->n_reports == 0)
            delete_stream(si);
          return 0;
        }
      return VNET_API_ERROR_NO_SUCH_ENTRY;
    }

  if (found_index != ~0)
    return VNET_API_ERROR_VALUE_EXIST;

  if (si == -1)
    {
      stream = add_stream();
      stream->domain_id = a->domain_id;
      stream->src_port = a->src_port;
      stream->sequence_number = 0;
      stream->n_reports = 0;
      si = stream - frm->streams;
    }
  else
    stream = &frm->streams[si];

  stream->n_reports++;

  vec_add2 (frm->reports, fr, 1);

  fr->stream_index = si;
  fr->template_id = 256 + stream->next_template_no;
  stream->next_template_no = (stream->next_template_no + 1) % (65536 - 256);
  fr->update_rewrite = 1;
  fr->opaque = a->opaque;
  fr->rewrite_callback = a->rewrite_callback;
  fr->flow_data_callback = a->flow_data_callback;
  
  return 0;
}

clib_error_t * flow_report_add_del_error_to_clib_error (int error)
{
    switch (error)
      {
      case 0:
	return 0;
      case VNET_API_ERROR_NO_SUCH_ENTRY:
        return clib_error_return (0, "Flow report not found");
      case VNET_API_ERROR_VALUE_EXIST:
        return clib_error_return (0, "Flow report already exists");
      case VNET_API_ERROR_INVALID_VALUE:
        return clib_error_return (0, "Expecting either still unused values "
                                     "for both domain_id and src_port "
                                     "or already used values for both fields");
      default:
        return clib_error_return (0, "vnet_flow_report_add_del returned %d",
                                  error);
      }
}

void vnet_flow_reports_reset (flow_report_main_t * frm)
{
  flow_report_t *fr;
  u32 i;

  for (i = 0; i < vec_len(frm->streams); i++)
    if (stream_index_valid(i))
      frm->streams[i].sequence_number = 0;

  vec_foreach (fr, frm->reports)
    {
      fr->update_rewrite = 1;
      fr->last_template_sent = 0;
    }
}

void vnet_stream_reset (flow_report_main_t * frm, u32 stream_index)
{
  flow_report_t *fr;

  frm->streams[stream_index].sequence_number = 0;

  vec_foreach (fr, frm->reports)
    if (frm->reports->stream_index == stream_index) {
      fr->update_rewrite = 1;
      fr->last_template_sent = 0;
    }
}

int vnet_stream_change (flow_report_main_t * frm,
                        u32 old_domain_id, u16 old_src_port,
                        u32 new_domain_id, u16 new_src_port)
{
  i32 stream_index = find_stream (old_domain_id, old_src_port);
  if (stream_index < 0)
    return 1;
  flow_report_stream_t * stream = &frm->streams[stream_index];
  stream->domain_id = new_domain_id;
  stream->src_port = new_src_port;
  if (old_domain_id != new_domain_id || old_src_port != new_src_port)
    vnet_stream_reset (frm, stream_index);
  return 0;
}

static clib_error_t *
set_ipfix_exporter_command_fn (vlib_main_t * vm,
                               unformat_input_t * input,
                               vlib_cli_command_t * cmd)
{
  flow_report_main_t * frm = &flow_report_main;
  ip4_address_t collector, src;
  u16 collector_port = UDP_DST_PORT_ipfix;
  u32 fib_id;
  u32 fib_index = ~0;
  
  collector.as_u32 = 0;
  src.as_u32 = 0;
  u32 path_mtu = 512; // RFC 7011 section 10.3.3.
  u32 template_interval = 20;
  u8 udp_checksum = 0;

  while (unformat_check_input (input) != UNFORMAT_END_OF_INPUT) {
    if (unformat (input, "collector %U", unformat_ip4_address, &collector))
      ;
    else if (unformat (input, "port %u", &collector_port))
      ;
    else if (unformat (input, "src %U", unformat_ip4_address, &src))
      ;
    else if (unformat (input, "fib-id %u", &fib_id))
      {
        ip4_main_t * im = &ip4_main;
        uword * p = hash_get (im->fib_index_by_table_id, fib_id);
        if (! p)
          return clib_error_return (0, "fib ID %d doesn't exist\n",
                                    fib_id);
        fib_index = p[0];
      }
    else if (unformat (input, "path-mtu %u", &path_mtu))
      ;
    else if (unformat (input, "template-interval %u", &template_interval))
      ;
    else if (unformat (input, "udp-checksum"))
      udp_checksum = 1;
    else
      break;
  }
  
  if (collector.as_u32 == 0)
    return clib_error_return (0, "collector address required");

  if (src.as_u32 == 0)
    return clib_error_return (0, "src address required");

  if (path_mtu > 1450 /* vpp does not support fragmentation */)
	return clib_error_return (0, "too big path-mtu value, maximum is 1450");

  if (path_mtu < 68)
	return clib_error_return (0, "too small path-mtu value, minimum is 68");

  /* Reset report streams if we are reconfiguring IP addresses */
  if (frm->ipfix_collector.as_u32 != collector.as_u32 ||
      frm->src_address.as_u32 != src.as_u32 ||
      frm->collector_port != collector_port)
    vnet_flow_reports_reset(frm);

  frm->ipfix_collector.as_u32 = collector.as_u32;
  frm->collector_port = collector_port;
  frm->src_address.as_u32 = src.as_u32;
  frm->fib_index = fib_index;
  frm->path_mtu = path_mtu;
  frm->template_interval = template_interval;
  frm->udp_checksum = udp_checksum;
  
  vlib_cli_output (vm, "Collector %U, src address %U, "
		           "fib index %d, path MTU %u, "
		           "template resend interval %us, "
		           "udp checksum %s",
                   format_ip4_address, &frm->ipfix_collector,
                   format_ip4_address, &frm->src_address,
                   fib_index, path_mtu, template_interval,
                   udp_checksum ? "enabled" : "disabled");

  /* Turn on the flow reporting process */
  vlib_process_signal_event (vm, flow_report_process_node.index,
                             1, 0);
  return 0;
}

VLIB_CLI_COMMAND (set_ipfix_exporter_command, static) = {
    .path = "set ipfix exporter",
    .short_help = "set ipfix exporter "
                  "collector <ip4-address> [port <port>] "
                  "src <ip4-address> [fib-id <fib-id>] "
                  "[path-mtu <path-mtu>] "
                  "[template-interval <template-interval>]",
                  "[udp-checksum]",
    .function = set_ipfix_exporter_command_fn,
};

static clib_error_t * 
flow_report_init (vlib_main_t *vm)
{
  flow_report_main_t * frm = &flow_report_main;

  frm->vlib_main = vm;
  frm->vnet_main = vnet_get_main();
  frm->unix_time_0 = time(0);
  frm->vlib_time_0 = vlib_time_now(frm->vlib_main);
  frm->fib_index = ~0;

  return 0;
}

VLIB_INIT_FUNCTION (flow_report_init)
