tcp_pg.c

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/*
 * 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);
      tcp_len0 = clib_net_to_host_u16 (ip0->length) - sizeof (ip0[0]);

      /* 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))
        ;

      /* 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;
}