/*
 * esp_encrypt.c : IPSec ESP encrypt node
 *
 * 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 ESP_SEQ_MAX (4294967295UL)

#define foreach_esp_encrypt_next                   \
_(DROP, "error-drop")                              \
_(IP4_INPUT, "ip4-input")                          \
_(IP6_INPUT, "ip6-input")                          \
_(INTERFACE_OUTPUT, "interface-output")

#define _(v, s) ESP_ENCRYPT_NEXT_##v,
typedef enum
{
  foreach_esp_encrypt_next
#undef _
    ESP_ENCRYPT_N_NEXT,
} esp_encrypt_next_t;

#define foreach_esp_encrypt_error                   \
 _(RX_PKTS, "ESP pkts received")                    \
 _(NO_BUFFER, "No buffer (packet dropped)")         \
 _(DECRYPTION_FAILED, "ESP encryption failed")      \
 _(SEQ_CYCLED, "sequence number cycled")


typedef enum
{
#define _(sym,str) ESP_ENCRYPT_ERROR_##sym,
  foreach_esp_encrypt_error
#undef _
    ESP_ENCRYPT_N_ERROR,
} esp_encrypt_error_t;

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

vlib_node_registration_t esp_encrypt_node;

typedef struct
{
  u32 spi;
  u32 seq;
  ipsec_crypto_alg_t crypto_alg;
  ipsec_integ_alg_t integ_alg;
} esp_encrypt_trace_t;

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

  s = format (s, "esp: spi %u seq %u crypto %U integrity %U",
	      t->spi, t->seq,
	      format_ipsec_crypto_alg, t->crypto_alg,
	      format_ipsec_integ_alg, t->integ_alg);
  return s;
}

always_inline void
esp_encrypt_aes_cbc (ipsec_crypto_alg_t alg,
		     u8 * in, u8 * out, size_t in_len, u8 * key, u8 * iv)
{
  esp_main_t *em = &esp_main;
  u32 cpu_index = os_get_cpu_number ();
  EVP_CIPHER_CTX *ctx = &(em->per_thread_data[cpu_index].encrypt_ctx);
  const EVP_CIPHER *cipher = NULL;
  int out_len;

  ASSERT (alg < IPSEC_CRYPTO_N_ALG);

  if (PREDICT_FALSE (em->esp_crypto_algs[alg].type == IPSEC_CRYPTO_ALG_NONE))
    return;

  if (PREDICT_FALSE (alg != em->per_thread_data[cpu_index].last_encrypt_alg))
    {
      cipher = em->esp_crypto_algs[alg].type;
      em->per_thread_data[cpu_index].last_encrypt_alg = alg;
    }

  EVP_EncryptInit_ex (ctx, cipher, NULL, key, iv);

  EVP_EncryptUpdate (ctx, out, &out_len, in, in_len);
  EVP_EncryptFinal_ex (ctx, out + out_len, &out_len);
}

always_inline int
esp_seq_advance (ipsec_sa_t * sa)
{
  if (PREDICT_TRUE (sa->use_esn))
    {
      if (PREDICT_FALSE (sa->seq == ESP_SEQ_MAX))
	{
	  if (PREDICT_FALSE
	      (sa->use_anti_replay && sa->seq_hi == ESP_SEQ_MAX))
	    return 1;
	  sa->seq_hi++;
	}
      sa->seq++;
    }
  else
    {
      if (PREDICT_FALSE (sa->use_anti_replay && sa->seq == ESP_SEQ_MAX))
	return 1;
      sa->seq++;
    }

  return 0;
}

static uword
esp_encrypt_node_fn (vlib_main_t * vm,
		     vlib_node_runtime_t * node, vlib_frame_t * from_frame)
{
  u32 n_left_from, *from, *to_next = 0, next_index;
  from = vlib_frame_vector_args (from_frame);
  n_left_from = from_frame->n_vectors;
  ipsec_main_t *im = &ipsec_main;
  u32 *recycle = 0;
  u32 cpu_index = os_get_cpu_number ();

  ipsec_alloc_empty_buffers (vm, im);

  u32 *empty_buffers = im->empty_buffers[cpu_index];

  if (PREDICT_FALSE (vec_len (empty_buffers) < n_left_from))
    {
      vlib_node_increment_counter (vm, esp_encrypt_node.index,
				   ESP_ENCRYPT_ERROR_NO_BUFFER, n_left_from);
      clib_warning ("no enough empty buffers. discarding frame");
      goto free_buffers_and_exit;
    }

  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 i_bi0, o_bi0, next0;
	  vlib_buffer_t *i_b0, *o_b0 = 0;
	  u32 sa_index0;
	  ipsec_sa_t *sa0;
	  ip4_and_esp_header_t *ih0, *oh0 = 0;
	  ip6_and_esp_header_t *ih6_0, *oh6_0 = 0;
	  uword last_empty_buffer;
	  esp_header_t *o_esp0;
	  esp_footer_t *f0;
	  u8 is_ipv6;
	  u8 ip_hdr_size;
	  u8 next_hdr_type;
	  u32 ip_proto = 0;
	  u8 transport_mode = 0;

	  i_bi0 = from[0];
	  from += 1;
	  n_left_from -= 1;
	  n_left_to_next -= 1;

	  next0 = ESP_ENCRYPT_NEXT_DROP;

	  i_b0 = vlib_get_buffer (vm, i_bi0);
	  sa_index0 = vnet_buffer (i_b0)->output_features.ipsec_sad_index;
	  sa0 = pool_elt_at_index (im->sad, sa_index0);

	  if (PREDICT_FALSE (esp_seq_advance (sa0)))
	    {
	      clib_warning ("sequence number counter has cycled SPI %u",
			    sa0->spi);
	      vlib_node_increment_counter (vm, esp_encrypt_node.index,
					   ESP_ENCRYPT_ERROR_SEQ_CYCLED, 1);
	      //TODO: rekey SA
	      o_bi0 = i_bi0;
	      to_next[0] = o_bi0;
	      to_next += 1;
	      goto trace;
	    }

	  /* grab free buffer */
	  last_empty_buffer = vec_len (empty_buffers) - 1;
	  o_bi0 = empty_buffers[last_empty_buffer];
	  o_b0 = vlib_get_buffer (vm, o_bi0);
	  o_b0->flags = VLIB_BUFFER_TOTAL_LENGTH_VALID;
	  o_b0->current_data = sizeof (ethernet_header_t);
	  ih0 = vlib_buffer_get_current (i_b0);
	  vlib_prefetch_buffer_with_index (vm,
					   empty_buffers[last_empty_buffer -
							 1], STORE);
	  _vec_len (empty_buffers) = last_empty_buffer;
	  to_next[0] = o_bi0;
	  to_next += 1;

	  /* add old buffer to the recycle list */
	  vec_add1 (recycle, i_bi0);

	  /* is ipv6 */
	  if (PREDICT_FALSE
	      ((ih0->ip4.ip_version_and_header_length & 0xF0) == 0x60))
	    {
	      is_ipv6 = 1;
	      ih6_0 = vlib_buffer_get_current (i_b0);
	      ip_hdr_size = sizeof (ip6_header_t);
	      next_hdr_type = IP_PROTOCOL_IPV6;
	      oh6_0 = vlib_buffer_get_current (o_b0);
	      o_esp0 = vlib_buffer_get_current (o_b0) + sizeof (ip6_header_t);

	      oh6_0->ip6.ip_version_traffic_class_and_flow_label =
		ih6_0->ip6.ip_version_traffic_class_and_flow_label;
	      oh6_0->ip6.protocol = IP_PROTOCOL_IPSEC_ESP;
	      oh6_0->ip6.hop_limit = 254;
	      oh6_0->ip6.src_address.as_u64[0] =
		ih6_0->ip6.src_address.as_u64[0];
	      oh6_0->ip6.src_address.as_u64[1] =
		ih6_0->ip6.src_address.as_u64[1];
	      oh6_0->ip6.dst_address.as_u64[0] =
		ih6_0->ip6.dst_address.as_u64[0];
	      oh6_0->ip6.dst_address.as_u64[1] =
		ih6_0->ip6.dst_address.as_u64[1];
	      oh6_0->esp.spi = clib_net_to_host_u32 (sa0->spi);
	      oh6_0->esp.seq = clib_net_to_host_u32 (sa0->seq);
	      ip_proto = ih6_0->ip6.protocol;

	      next0 = ESP_ENCRYPT_NEXT_IP6_INPUT;
	    }
	  else
	    {
	      is_ipv6 = 0;
	      ip_hdr_size = sizeof (ip4_header_t);
	      next_hdr_type = IP_PROTOCOL_IP_IN_IP;
	      oh0 = vlib_buffer_get_current (o_b0);
	      o_esp0 = vlib_buffer_get_current (o_b0) + sizeof (ip4_header_t);

	      oh0->ip4.ip_version_and_header_length = 0x45;
	      oh0->ip4.tos = ih0->ip4.tos;
	      oh0->ip4.fragment_id = 0;
	      oh0->ip4.flags_and_fragment_offset = 0;
	      oh0->ip4.ttl = 254;
	      oh0->ip4.protocol = IP_PROTOCOL_IPSEC_ESP;
	      oh0->ip4.src_address.as_u32 = ih0->ip4.src_address.as_u32;
	      oh0->ip4.dst_address.as_u32 = ih0->ip4.dst_address.as_u32;
	      oh0->esp.spi = clib_net_to_host_u32 (sa0->spi);
	      oh0->esp.seq = clib_net_to_host_u32 (sa0->seq);
	      ip_proto = ih0->ip4.protocol;

	      next0 = ESP_ENCRYPT_NEXT_IP4_INPUT;
	    }

	  if (PREDICT_TRUE
	      (!is_ipv6 && sa0->is_tunnel && !sa0->is_tunnel_ip6))
	    {
	      oh0->ip4.src_address.as_u32 = sa0->tunnel_src_addr.ip4.as_u32;
	      oh0->ip4.dst_address.as_u32 = sa0->tunnel_dst_addr.ip4.as_u32;

	      vnet_buffer (o_b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
	    }
	  else if (is_ipv6 && sa0->is_tunnel && sa0->is_tunnel_ip6)
	    {
	      oh6_0->ip6.src_address.as_u64[0] =
		sa0->tunnel_src_addr.ip6.as_u64[0];
	      oh6_0->ip6.src_address.as_u64[1] =
		sa0->tunnel_src_addr.ip6.as_u64[1];
	      oh6_0->ip6.dst_address.as_u64[0] =
		sa0->tunnel_dst_addr.ip6.as_u64[0];
	      oh6_0->ip6.dst_address.as_u64[1] =
		sa0->tunnel_dst_addr.ip6.as_u64[1];

	      vnet_buffer (o_b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
	    }
	  else
	    {
	      vlib_buffer_advance (i_b0, ip_hdr_size);
	      next_hdr_type = ip_proto;
	      if (vnet_buffer (i_b0)->sw_if_index[VLIB_TX] != ~0)
		{
		  transport_mode = 1;
		  ethernet_header_t *ieh0, *oeh0;
		  ieh0 = (ethernet_header_t *) i_b0->data;
		  oeh0 = (ethernet_header_t *) o_b0->data;
		  clib_memcpy (oeh0, ieh0, sizeof (ethernet_header_t));
		  next0 = ESP_ENCRYPT_NEXT_INTERFACE_OUTPUT;
		  o_b0->flags |= BUFFER_OUTPUT_FEAT_DONE;
		  vnet_buffer (o_b0)->sw_if_index[VLIB_TX] =
		    vnet_buffer (i_b0)->sw_if_index[VLIB_TX];
		  vnet_buffer (o_b0)->output_features.bitmap =
		    vnet_buffer (i_b0)->output_features.bitmap;
		}
	    }

	  ASSERT (sa0->crypto_alg < IPSEC_CRYPTO_N_ALG);

	  if (PREDICT_TRUE (sa0->crypto_alg != IPSEC_CRYPTO_ALG_NONE))
	    {

	      const int BLOCK_SIZE = 16;
	      const int IV_SIZE = 16;
	      int blocks = 1 + (i_b0->current_length + 1) / BLOCK_SIZE;

	      /* pad packet in input buffer */
	      u8 pad_bytes = BLOCK_SIZE * blocks - 2 - i_b0->current_length;
	      u8 i;
	      u8 *padding =
		vlib_buffer_get_current (i_b0) + i_b0->current_length;
	      i_b0->current_length = BLOCK_SIZE * blocks;
	      for (i = 0; i < pad_bytes; ++i)
		{
		  padding[i] = i + 1;
		}
	      f0 = vlib_buffer_get_current (i_b0) + i_b0->current_length - 2;
	      f0->pad_length = pad_bytes;
	      f0->next_header = next_hdr_type;

	      o_b0->current_length = ip_hdr_size + sizeof (esp_header_t) +
		BLOCK_SIZE * blocks + IV_SIZE;

	      vnet_buffer (o_b0)->sw_if_index[VLIB_RX] =
		vnet_buffer (i_b0)->sw_if_index[VLIB_RX];

	      u8 iv[16];
	      RAND_bytes (iv, sizeof (iv));

	      clib_memcpy ((u8 *) vlib_buffer_get_current (o_b0) +
			   ip_hdr_size + sizeof (esp_header_t), iv, 16);

	      esp_encrypt_aes_cbc (sa0->crypto_alg,
				   (u8 *) vlib_buffer_get_current (i_b0),
				   (u8 *) vlib_buffer_get_current (o_b0) +
				   ip_hdr_size + sizeof (esp_header_t) +
				   IV_SIZE, BLOCK_SIZE * blocks,
				   sa0->crypto_key, iv);
	    }

	  o_b0->current_length += hmac_calc (sa0->integ_alg, sa0->integ_key,
					     sa0->integ_key_len,
					     (u8 *) o_esp0,
					     o_b0->current_length -
					     ip_hdr_size,
					     vlib_buffer_get_current (o_b0) +
					     o_b0->current_length,
					     sa0->use_esn, sa0->seq_hi);


	  if (PREDICT_FALSE (is_ipv6))
	    {
	      oh6_0->ip6.payload_length =
		clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, o_b0) -
				      sizeof (ip6_header_t));
	    }
	  else
	    {
	      oh0->ip4.length =
		clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, o_b0));
	      oh0->ip4.checksum = ip4_header_checksum (&oh0->ip4);
	    }

	  if (transport_mode)
	    vlib_buffer_reset (o_b0);

	trace:
	  if (PREDICT_FALSE (i_b0->flags & VLIB_BUFFER_IS_TRACED))
	    {
	      if (o_b0)
		{
		  o_b0->flags |= VLIB_BUFFER_IS_TRACED;
		  o_b0->trace_index = i_b0->trace_index;
		  esp_encrypt_trace_t *tr =
		    vlib_add_trace (vm, node, o_b0, sizeof (*tr));
		  tr->spi = sa0->spi;
		  tr->seq = sa0->seq - 1;
		  tr->crypto_alg = sa0->crypto_alg;
		  tr->integ_alg = sa0->integ_alg;
		}
	    }

	  vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
					   to_next, n_left_to_next, o_bi0,
					   next0);
	}
      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
    }
  vlib_node_increment_counter (vm, esp_encrypt_node.index,
			       ESP_ENCRYPT_ERROR_RX_PKTS,
			       from_frame->n_vectors);

free_buffers_and_exit:
  if (recycle)
    vlib_buffer_free (vm, recycle, vec_len (recycle));
  vec_free (recycle);
  return from_frame->n_vectors;
}


/* *INDENT-OFF* */
VLIB_REGISTER_NODE (esp_encrypt_node) = {
  .function = esp_encrypt_node_fn,
  .name = "esp-encrypt",
  .vector_size = sizeof (u32),
  .format_trace = format_esp_encrypt_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,

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

  .n_next_nodes = ESP_ENCRYPT_N_NEXT,
  .next_nodes = {
#define _(s,n) [ESP_ENCRYPT_NEXT_##s] = n,
    foreach_esp_encrypt_next
#undef _
  },
};
/* *INDENT-ON* */

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