/*
 * Copyright (c) 2016 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/tcp_pg: TCP packet-generator interface
 *
 * 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/pg/pg.h>

/* TCP flags bit 0 first. */
#define foreach_tcp_flag			\
  _ (FIN)					\
  _ (SYN)					\
  _ (RST)					\
  _ (PSH)					\
  _ (ACK)					\
  _ (URG)					\
  _ (ECE)					\
  _ (CWR)

static void
tcp_pg_edit_function (pg_main_t * pg,
		      pg_stream_t * s,
		      pg_edit_group_t * g, u32 * packets, u32 n_packets)
{
  vlib_main_t *vm = vlib_get_main ();
  u32 ip_offset, tcp_offset;

  tcp_offset = g->start_byte_offset;
  ip_offset = (g - 1)->start_byte_offset;

  while (n_packets >= 1)
    {
      vlib_buffer_t *p0;
      ip4_header_t *ip0;
      tcp_header_t *tcp0;
      ip_csum_t sum0;
      u32 tcp_len0;

      p0 = vlib_get_buffer (vm, packets[0]);
      n_packets -= 1;
      packets += 1;

      ASSERT (p0->current_data == 0);
      ip0 = (void *) (p0->data + ip_offset);
      tcp0 = (void *) (p0->data + tcp_offset);
      /* if IP length has been specified, then calculate the length based on buffer */
      if (ip0->length == 0)
	tcp_len0 = vlib_buffer_length_in_chain (vm, p0) - tcp_offset;
      else
	tcp_len0 = clib_net_to_host_u16 (ip0->length) - tcp_offset;

      /* Initialize checksum with header. */
      if (BITS (sum0) == 32)
	{
	  sum0 = clib_mem_unaligned (&ip0->src_address, u32);
	  sum0 =
	    ip_csum_with_carry (sum0,
				clib_mem_unaligned (&ip0->dst_address, u32));
	}
      else
	sum0 = clib_mem_unaligned (&ip0->src_address, u64);

      sum0 = ip_csum_with_carry
	(sum0, clib_host_to_net_u32 (tcp_len0 + (ip0->protocol << 16)));

      /* Invalidate possibly old checksum. */
      tcp0->checksum = 0;

      sum0 =
	ip_incremental_checksum_buffer (vm, p0, tcp_offset, tcp_len0, sum0);

      tcp0->checksum = ~ip_csum_fold (sum0);
    }
}

typedef struct
{
  pg_edit_t src, dst;
  pg_edit_t seq_number, ack_number;
  pg_edit_t data_offset_and_reserved;
#define _(f) pg_edit_t f##_flag;
    foreach_tcp_flag
#undef _
    pg_edit_t window;
  pg_edit_t checksum;
  pg_edit_t urgent_pointer;
} pg_tcp_header_t;

static inline void
pg_tcp_header_init (pg_tcp_header_t * p)
{
  /* Initialize fields that are not bit fields in the IP header. */
#define _(f) pg_edit_init (&p->f, tcp_header_t, f);
  _(src);
  _(dst);
  _(seq_number);
  _(ack_number);
  _(window);
  _(checksum);
  _(urgent_pointer);
#undef _

  /* Initialize bit fields. */
#define _(f)						\
  pg_edit_init_bitfield (&p->f##_flag, tcp_header_t,	\
			 flags,				\
			 TCP_FLAG_BIT_##f, 1);

  foreach_tcp_flag
#undef _
    pg_edit_init_bitfield (&p->data_offset_and_reserved, tcp_header_t,
			   data_offset_and_reserved, 4, 4);
}

uword
unformat_pg_tcp_header (unformat_input_t * input, va_list * args)
{
  pg_stream_t *s = va_arg (*args, pg_stream_t *);
  pg_tcp_header_t *p;
  u32 group_index;

  p = pg_create_edit_group (s, sizeof (p[0]), sizeof (tcp_header_t),
			    &group_index);
  pg_tcp_header_init (p);

  /* Defaults. */
  pg_edit_set_fixed (&p->seq_number, 0);
  pg_edit_set_fixed (&p->ack_number, 0);

  pg_edit_set_fixed (&p->data_offset_and_reserved,
		     sizeof (tcp_header_t) / sizeof (u32));

  pg_edit_set_fixed (&p->window, 4096);
  pg_edit_set_fixed (&p->urgent_pointer, 0);

#define _(f) pg_edit_set_fixed (&p->f##_flag, 0);
  foreach_tcp_flag
#undef _
    p->checksum.type = PG_EDIT_UNSPECIFIED;

  if (!unformat (input, "TCP: %U -> %U",
		 unformat_pg_edit,
		 unformat_tcp_udp_port, &p->src,
		 unformat_pg_edit, unformat_tcp_udp_port, &p->dst))
    goto error;

  /* Parse options. */
  while (1)
    {
      if (unformat (input, "window %U",
		    unformat_pg_edit, unformat_pg_number, &p->window))
	;

      else if (unformat (input, "checksum %U",
			 unformat_pg_edit, unformat_pg_number, &p->checksum))
	;

      else if (unformat (input, "seqnum %U", unformat_pg_edit,
			 unformat_pg_number, &p->seq_number))
	;
      else if (unformat (input, "acknum %U", unformat_pg_edit,
			 unformat_pg_number, &p->ack_number))
	;
      /* Flags. */
#define _(f) else if (unformat (input, #f)) pg_edit_set_fixed (&p->f##_flag, 1);
      foreach_tcp_flag
#undef _
	/* Can't parse input: try next protocol level. */
	else
	break;
    }

  {
    ip_main_t *im = &ip_main;
    u16 dst_port;
    tcp_udp_port_info_t *pi;

    pi = 0;
    if (p->dst.type == PG_EDIT_FIXED)
      {
	dst_port = pg_edit_get_value (&p->dst, PG_EDIT_LO);
	pi = ip_get_tcp_udp_port_info (im, dst_port);
      }

    if (pi && pi->unformat_pg_edit
	&& unformat_user (input, pi->unformat_pg_edit, s))
      ;

    else if (!unformat_user (input, unformat_pg_payload, s))
      goto error;

    if (p->checksum.type == PG_EDIT_UNSPECIFIED)
      {
	pg_edit_group_t *g = pg_stream_get_group (s, group_index);
	g->edit_function = tcp_pg_edit_function;
	g->edit_function_opaque = 0;
      }

    return 1;
  }

error:
  /* Free up any edits we may have added. */
  pg_free_edit_group (s);
  return 0;
}

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