src/plugins/nat/out2in.c

   1 /*
   2  * Copyright (c) 2016 Cisco and/or its affiliates.
   3  * Licensed under the Apache License, Version 2.0 (the "License");
   4  * you may not use this file except in compliance with the License.
   5  * You may obtain a copy of the License at:
   6  *
   7  *     http://www.apache.org/licenses/LICENSE-2.0
   8  *
   9  * Unless required by applicable law or agreed to in writing, software
  10  * distributed under the License is distributed on an "AS IS" BASIS,
  11  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12  * See the License for the specific language governing permissions and
  13  * limitations under the License.
  14  */
  15 /**
  16  * @file
  17  * @brief NAT44 endpoint-dependent outside to inside network translation
  18  */
  19
  20 #include <vlib/vlib.h>
  21 #include <vnet/vnet.h>
  22 #include <vnet/pg/pg.h>
  23
  24 #include <vnet/ip/ip.h>
  25 #include <vnet/udp/udp.h>
  26 #include <vnet/ethernet/ethernet.h>
  27 #include <vnet/fib/ip4_fib.h>
  28 #include <nat/nat.h>
  29 #include <nat/nat_ipfix_logging.h>
  30 #include <nat/nat_reass.h>
  31 #include <nat/nat_inlines.h>
  32 #include <nat/nat_syslog.h>
  33 #include <nat/nat_ha.h>
  34
  35 #include <vppinfra/hash.h>
  36 #include <vppinfra/error.h>
  37 #include <vppinfra/elog.h>
  38
  39 typedef struct
  40 {
  41   u32 sw_if_index;
  42   u32 next_index;
  43   u32 session_index;
  44 } snat_out2in_trace_t;
  45
  46 /* packet trace format function */
  47 static u8 *
  48 format_snat_out2in_trace (u8 * s, va_list * args)
  49 {
  50   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  51   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  52   snat_out2in_trace_t *t = va_arg (*args, snat_out2in_trace_t *);
  53
  54   s =
  55     format (s,
  56             "NAT44_OUT2IN: sw_if_index %d, next index %d, session index %d",
  57             t->sw_if_index, t->next_index, t->session_index);
  58   return s;
  59 }
  60
  61 static u8 *
  62 format_snat_out2in_fast_trace (u8 * s, va_list * args)
  63 {
  64   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  65   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  66   snat_out2in_trace_t *t = va_arg (*args, snat_out2in_trace_t *);
  67
  68   s = format (s, "NAT44_OUT2IN_FAST: sw_if_index %d, next index %d",
  69               t->sw_if_index, t->next_index);
  70   return s;
  71 }
  72
  73 #define foreach_snat_out2in_error                       \
  74 _(UNSUPPORTED_PROTOCOL, "unsupported protocol")         \
  75 _(OUT2IN_PACKETS, "good out2in packets processed")      \
  76 _(OUT_OF_PORTS, "out of ports")                         \
  77 _(BAD_ICMP_TYPE, "unsupported ICMP type")               \
  78 _(NO_TRANSLATION, "no translation")                     \
  79 _(MAX_SESSIONS_EXCEEDED, "maximum sessions exceeded")   \
  80 _(DROP_FRAGMENT, "drop fragment")                       \
  81 _(MAX_REASS, "maximum reassemblies exceeded")           \
  82 _(MAX_FRAG, "maximum fragments per reassembly exceeded")\
  83 _(TCP_PACKETS, "TCP packets")                           \
  84 _(UDP_PACKETS, "UDP packets")                           \
  85 _(ICMP_PACKETS, "ICMP packets")                         \
  86 _(OTHER_PACKETS, "other protocol packets")              \
  87 _(FRAGMENTS, "fragments")                               \
  88 _(CACHED_FRAGMENTS, "cached fragments")                 \
  89 _(PROCESSED_FRAGMENTS, "processed fragments")
  90
  91 typedef enum
  92 {
  93 #define _(sym,str) SNAT_OUT2IN_ERROR_##sym,
  94   foreach_snat_out2in_error
  95 #undef _
  96     SNAT_OUT2IN_N_ERROR,
  97 } snat_out2in_error_t;
  98
  99 static char *snat_out2in_error_strings[] = {
 100 #define _(sym,string) string,
 101   foreach_snat_out2in_error
 102 #undef _
 103 };
 104
 105 typedef enum
 106 {
 107   SNAT_OUT2IN_NEXT_DROP,
 108   SNAT_OUT2IN_NEXT_LOOKUP,
 109   SNAT_OUT2IN_NEXT_ICMP_ERROR,
 110   SNAT_OUT2IN_NEXT_REASS,
 111   SNAT_OUT2IN_N_NEXT,
 112 } snat_out2in_next_t;
 113
 114 #ifndef CLIB_MARCH_VARIANT
 115 int
 116 nat44_o2i_is_idle_session_cb (clib_bihash_kv_8_8_t * kv, void *arg)
 117 {
 118   snat_main_t *sm = &snat_main;
 119   nat44_is_idle_session_ctx_t *ctx = arg;
 120   snat_session_t *s;
 121   u64 sess_timeout_time;
 122   snat_main_per_thread_data_t *tsm = vec_elt_at_index (sm->per_thread_data,
 123                                                        ctx->thread_index);
 124   clib_bihash_kv_8_8_t s_kv;
 125
 126   s = pool_elt_at_index (tsm->sessions, kv->value);
 127   sess_timeout_time = s->last_heard + (f64) nat44_session_get_timeout (sm, s);
 128   if (ctx->now >= sess_timeout_time)
 129     {
 130       s_kv.key = s->in2out.as_u64;
 131       if (clib_bihash_add_del_8_8 (&tsm->in2out, &s_kv, 0))
 132         nat_elog_warn ("out2in key del failed");
 133
 134       snat_ipfix_logging_nat44_ses_delete (ctx->thread_index,
 135                                            s->in2out.addr.as_u32,
 136                                            s->out2in.addr.as_u32,
 137                                            s->in2out.protocol,
 138                                            s->in2out.port,
 139                                            s->out2in.port,
 140                                            s->in2out.fib_index);
 141
 142       nat_syslog_nat44_apmdel (s->user_index, s->in2out.fib_index,
 143                                &s->in2out.addr, s->in2out.port,
 144                                &s->out2in.addr, s->out2in.port,
 145                                s->in2out.protocol);
 146
 147       nat_ha_sdel (&s->out2in.addr, s->out2in.port, &s->ext_host_addr,
 148                    s->ext_host_port, s->out2in.protocol, s->out2in.fib_index,
 149                    ctx->thread_index);
 150
 151       if (!snat_is_session_static (s))
 152         snat_free_outside_address_and_port (sm->addresses, ctx->thread_index,
 153                                             &s->out2in);
 154
 155       nat44_delete_session (sm, s, ctx->thread_index);
 156       return 1;
 157     }
 158
 159   return 0;
 160 }
 161 #endif
 162
 163 /**
 164  * @brief Create session for static mapping.
 165  *
 166  * Create NAT session initiated by host from external network with static
 167  * mapping.
 168  *
 169  * @param sm     NAT main.
 170  * @param b0     Vlib buffer.
 171  * @param in2out In2out NAT44 session key.
 172  * @param out2in Out2in NAT44 session key.
 173  * @param node   Vlib node.
 174  *
 175  * @returns SNAT session if successfully created otherwise 0.
 176  */
 177 static inline snat_session_t *
 178 create_session_for_static_mapping (snat_main_t * sm,
 179                                    vlib_buffer_t * b0,
 180                                    snat_session_key_t in2out,
 181                                    snat_session_key_t out2in,
 182                                    vlib_node_runtime_t * node,
 183                                    u32 thread_index, f64 now)
 184 {
 185   snat_user_t *u;
 186   snat_session_t *s;
 187   clib_bihash_kv_8_8_t kv0;
 188   ip4_header_t *ip0;
 189   udp_header_t *udp0;
 190   nat44_is_idle_session_ctx_t ctx0;
 191
 192   if (PREDICT_FALSE (maximum_sessions_exceeded (sm, thread_index)))
 193     {
 194       b0->error = node->errors[SNAT_OUT2IN_ERROR_MAX_SESSIONS_EXCEEDED];
 195       nat_elog_notice ("maximum sessions exceeded");
 196       return 0;
 197     }
 198
 199   ip0 = vlib_buffer_get_current (b0);
 200   udp0 = ip4_next_header (ip0);
 201
 202   u =
 203     nat_user_get_or_create (sm, &in2out.addr, in2out.fib_index, thread_index);
 204   if (!u)
 205     {
 206       nat_elog_warn ("create NAT user failed");
 207       return 0;
 208     }
 209
 210   s = nat_session_alloc_or_recycle (sm, u, thread_index, now);
 211   if (!s)
 212     {
 213       nat44_delete_user_with_no_session (sm, u, thread_index);
 214       nat_elog_warn ("create NAT session failed");
 215       return 0;
 216     }
 217
 218   s->flags |= SNAT_SESSION_FLAG_STATIC_MAPPING;
 219   s->ext_host_addr.as_u32 = ip0->src_address.as_u32;
 220   s->ext_host_port = udp0->src_port;
 221   user_session_increment (sm, u, 1 /* static */ );
 222   s->in2out = in2out;
 223   s->out2in = out2in;
 224   s->in2out.protocol = out2in.protocol;
 225
 226   /* Add to translation hashes */
 227   ctx0.now = now;
 228   ctx0.thread_index = thread_index;
 229   kv0.key = s->in2out.as_u64;
 230   kv0.value = s - sm->per_thread_data[thread_index].sessions;
 231   if (clib_bihash_add_or_overwrite_stale_8_8
 232       (&sm->per_thread_data[thread_index].in2out, &kv0,
 233        nat44_i2o_is_idle_session_cb, &ctx0))
 234     nat_elog_notice ("in2out key add failed");
 235
 236   kv0.key = s->out2in.as_u64;
 237
 238   if (clib_bihash_add_or_overwrite_stale_8_8
 239       (&sm->per_thread_data[thread_index].out2in, &kv0,
 240        nat44_o2i_is_idle_session_cb, &ctx0))
 241     nat_elog_notice ("out2in key add failed");
 242
 243   /* log NAT event */
 244   snat_ipfix_logging_nat44_ses_create (thread_index,
 245                                        s->in2out.addr.as_u32,
 246                                        s->out2in.addr.as_u32,
 247                                        s->in2out.protocol,
 248                                        s->in2out.port,
 249                                        s->out2in.port, s->in2out.fib_index);
 250
 251   nat_syslog_nat44_apmadd (s->user_index, s->in2out.fib_index,
 252                            &s->in2out.addr, s->in2out.port, &s->out2in.addr,
 253                            s->out2in.port, s->in2out.protocol);
 254
 255   nat_ha_sadd (&s->in2out.addr, s->in2out.port, &s->out2in.addr,
 256                s->out2in.port, &s->ext_host_addr, s->ext_host_port,
 257                &s->ext_host_nat_addr, s->ext_host_nat_port,
 258                s->in2out.protocol, s->in2out.fib_index, s->flags,
 259                thread_index, 0);
 260
 261   return s;
 262 }
 263
 264 #ifndef CLIB_MARCH_VARIANT
 265 static_always_inline
 266   snat_out2in_error_t icmp_get_key (ip4_header_t * ip0,
 267                                     snat_session_key_t * p_key0)
 268 {
 269   icmp46_header_t *icmp0;
 270   snat_session_key_t key0;
 271   icmp_echo_header_t *echo0, *inner_echo0 = 0;
 272   ip4_header_t *inner_ip0;
 273   void *l4_header = 0;
 274   icmp46_header_t *inner_icmp0;
 275
 276   icmp0 = (icmp46_header_t *) ip4_next_header (ip0);
 277   echo0 = (icmp_echo_header_t *) (icmp0 + 1);
 278
 279   if (!icmp_is_error_message (icmp0))
 280     {
 281       key0.protocol = SNAT_PROTOCOL_ICMP;
 282       key0.addr = ip0->dst_address;
 283       key0.port = echo0->identifier;
 284     }
 285   else
 286     {
 287       inner_ip0 = (ip4_header_t *) (echo0 + 1);
 288       l4_header = ip4_next_header (inner_ip0);
 289       key0.protocol = ip_proto_to_snat_proto (inner_ip0->protocol);
 290       key0.addr = inner_ip0->src_address;
 291       switch (key0.protocol)
 292         {
 293         case SNAT_PROTOCOL_ICMP:
 294           inner_icmp0 = (icmp46_header_t *) l4_header;
 295           inner_echo0 = (icmp_echo_header_t *) (inner_icmp0 + 1);
 296           key0.port = inner_echo0->identifier;
 297           break;
 298         case SNAT_PROTOCOL_UDP:
 299         case SNAT_PROTOCOL_TCP:
 300           key0.port = ((tcp_udp_header_t *) l4_header)->src_port;
 301           break;
 302         default:
 303           return SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL;
 304         }
 305     }
 306   *p_key0 = key0;
 307   return -1;                    /* success */
 308 }
 309
 310 /**
 311  * Get address and port values to be used for ICMP packet translation
 312  * and create session if needed
 313  *
 314  * @param[in,out] sm             NAT main
 315  * @param[in,out] node           NAT node runtime
 316  * @param[in] thread_index       thread index
 317  * @param[in,out] b0             buffer containing packet to be translated
 318  * @param[out] p_proto           protocol used for matching
 319  * @param[out] p_value           address and port after NAT translation
 320  * @param[out] p_dont_translate  if packet should not be translated
 321  * @param d                      optional parameter
 322  * @param e                      optional parameter
 323  */
 324 u32
 325 icmp_match_out2in_slow (snat_main_t * sm, vlib_node_runtime_t * node,
 326                         u32 thread_index, vlib_buffer_t * b0,
 327                         ip4_header_t * ip0, u8 * p_proto,
 328                         snat_session_key_t * p_value,
 329                         u8 * p_dont_translate, void *d, void *e)
 330 {
 331   icmp46_header_t *icmp0;
 332   u32 sw_if_index0;
 333   u32 rx_fib_index0;
 334   snat_session_key_t key0;
 335   snat_session_key_t sm0;
 336   snat_session_t *s0 = 0;
 337   u8 dont_translate = 0;
 338   clib_bihash_kv_8_8_t kv0, value0;
 339   u8 is_addr_only;
 340   u32 next0 = ~0;
 341   int err;
 342   u8 identity_nat;
 343
 344   icmp0 = (icmp46_header_t *) ip4_next_header (ip0);
 345   sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
 346   rx_fib_index0 = ip4_fib_table_get_index_for_sw_if_index (sw_if_index0);
 347
 348   key0.protocol = 0;
 349
 350   err = icmp_get_key (ip0, &key0);
 351   if (err != -1)
 352     {
 353       b0->error = node->errors[SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL];
 354       next0 = SNAT_OUT2IN_NEXT_DROP;
 355       goto out;
 356     }
 357   key0.fib_index = rx_fib_index0;
 358
 359   kv0.key = key0.as_u64;
 360
 361   if (clib_bihash_search_8_8 (&sm->per_thread_data[thread_index].out2in, &kv0,
 362                               &value0))
 363     {
 364       /* Try to match static mapping by external address and port,
 365          destination address and port in packet */
 366       if (snat_static_mapping_match
 367           (sm, key0, &sm0, 1, &is_addr_only, 0, 0, 0, &identity_nat))
 368         {
 369           if (!sm->forwarding_enabled)
 370             {
 371               /* Don't NAT packet aimed at the intfc address */
 372               if (PREDICT_FALSE (is_interface_addr (sm, node, sw_if_index0,
 373                                                     ip0->dst_address.as_u32)))
 374                 {
 375                   dont_translate = 1;
 376                   goto out;
 377                 }
 378               b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
 379               next0 = SNAT_OUT2IN_NEXT_DROP;
 380               goto out;
 381             }
 382           else
 383             {
 384               dont_translate = 1;
 385               goto out;
 386             }
 387         }
 388
 389       if (PREDICT_FALSE (icmp0->type != ICMP4_echo_reply &&
 390                          (icmp0->type != ICMP4_echo_request
 391                           || !is_addr_only)))
 392         {
 393           b0->error = node->errors[SNAT_OUT2IN_ERROR_BAD_ICMP_TYPE];
 394           next0 = SNAT_OUT2IN_NEXT_DROP;
 395           goto out;
 396         }
 397
 398       if (PREDICT_FALSE (identity_nat))
 399         {
 400           dont_translate = 1;
 401           goto out;
 402         }
 403       /* Create session initiated by host from external network */
 404       s0 = create_session_for_static_mapping (sm, b0, sm0, key0,
 405                                               node, thread_index,
 406                                               vlib_time_now (sm->vlib_main));
 407
 408       if (!s0)
 409         {
 410           next0 = SNAT_OUT2IN_NEXT_DROP;
 411           goto out;
 412         }
 413     }
 414   else
 415     {
 416       if (PREDICT_FALSE (icmp0->type != ICMP4_echo_reply &&
 417                          icmp0->type != ICMP4_echo_request &&
 418                          !icmp_is_error_message (icmp0)))
 419         {
 420           b0->error = node->errors[SNAT_OUT2IN_ERROR_BAD_ICMP_TYPE];
 421           next0 = SNAT_OUT2IN_NEXT_DROP;
 422           goto out;
 423         }
 424
 425       s0 = pool_elt_at_index (sm->per_thread_data[thread_index].sessions,
 426                               value0.value);
 427     }
 428
 429 out:
 430   *p_proto = key0.protocol;
 431   if (s0)
 432     *p_value = s0->in2out;
 433   *p_dont_translate = dont_translate;
 434   if (d)
 435     *(snat_session_t **) d = s0;
 436   return next0;
 437 }
 438 #endif
 439
 440 #ifndef CLIB_MARCH_VARIANT
 441 /**
 442  * Get address and port values to be used for ICMP packet translation
 443  *
 444  * @param[in] sm                 NAT main
 445  * @param[in,out] node           NAT node runtime
 446  * @param[in] thread_index       thread index
 447  * @param[in,out] b0             buffer containing packet to be translated
 448  * @param[out] p_proto           protocol used for matching
 449  * @param[out] p_value           address and port after NAT translation
 450  * @param[out] p_dont_translate  if packet should not be translated
 451  * @param d                      optional parameter
 452  * @param e                      optional parameter
 453  */
 454 u32
 455 icmp_match_out2in_fast (snat_main_t * sm, vlib_node_runtime_t * node,
 456                         u32 thread_index, vlib_buffer_t * b0,
 457                         ip4_header_t * ip0, u8 * p_proto,
 458                         snat_session_key_t * p_value,
 459                         u8 * p_dont_translate, void *d, void *e)
 460 {
 461   icmp46_header_t *icmp0;
 462   u32 sw_if_index0;
 463   u32 rx_fib_index0;
 464   snat_session_key_t key0;
 465   snat_session_key_t sm0;
 466   u8 dont_translate = 0;
 467   u8 is_addr_only;
 468   u32 next0 = ~0;
 469   int err;
 470
 471   icmp0 = (icmp46_header_t *) ip4_next_header (ip0);
 472   sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
 473   rx_fib_index0 = ip4_fib_table_get_index_for_sw_if_index (sw_if_index0);
 474
 475   err = icmp_get_key (ip0, &key0);
 476   if (err != -1)
 477     {
 478       b0->error = node->errors[err];
 479       next0 = SNAT_OUT2IN_NEXT_DROP;
 480       goto out2;
 481     }
 482   key0.fib_index = rx_fib_index0;
 483
 484   if (snat_static_mapping_match
 485       (sm, key0, &sm0, 1, &is_addr_only, 0, 0, 0, 0))
 486     {
 487       /* Don't NAT packet aimed at the intfc address */
 488       if (is_interface_addr (sm, node, sw_if_index0, ip0->dst_address.as_u32))
 489         {
 490           dont_translate = 1;
 491           goto out;
 492         }
 493       b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
 494       next0 = SNAT_OUT2IN_NEXT_DROP;
 495       goto out;
 496     }
 497
 498   if (PREDICT_FALSE (icmp0->type != ICMP4_echo_reply &&
 499                      (icmp0->type != ICMP4_echo_request || !is_addr_only) &&
 500                      !icmp_is_error_message (icmp0)))
 501     {
 502       b0->error = node->errors[SNAT_OUT2IN_ERROR_BAD_ICMP_TYPE];
 503       next0 = SNAT_OUT2IN_NEXT_DROP;
 504       goto out;
 505     }
 506
 507 out:
 508   *p_value = sm0;
 509 out2:
 510   *p_proto = key0.protocol;
 511   *p_dont_translate = dont_translate;
 512   return next0;
 513 }
 514 #endif
 515
 516 #ifndef CLIB_MARCH_VARIANT
 517 u32
 518 icmp_out2in (snat_main_t * sm,
 519              vlib_buffer_t * b0,
 520              ip4_header_t * ip0,
 521              icmp46_header_t * icmp0,
 522              u32 sw_if_index0,
 523              u32 rx_fib_index0,
 524              vlib_node_runtime_t * node,
 525              u32 next0, u32 thread_index, void *d, void *e)
 526 {
 527   snat_session_key_t sm0;
 528   u8 protocol;
 529   icmp_echo_header_t *echo0, *inner_echo0 = 0;
 530   ip4_header_t *inner_ip0 = 0;
 531   void *l4_header = 0;
 532   icmp46_header_t *inner_icmp0;
 533   u8 dont_translate;
 534   u32 new_addr0, old_addr0;
 535   u16 old_id0, new_id0;
 536   ip_csum_t sum0;
 537   u16 checksum0;
 538   u32 next0_tmp;
 539
 540   echo0 = (icmp_echo_header_t *) (icmp0 + 1);
 541
 542   next0_tmp = sm->icmp_match_out2in_cb (sm, node, thread_index, b0, ip0,
 543                                         &protocol, &sm0, &dont_translate, d,
 544                                         e);
 545   if (next0_tmp != ~0)
 546     next0 = next0_tmp;
 547   if (next0 == SNAT_OUT2IN_NEXT_DROP || dont_translate)
 548     goto out;
 549
 550   if (PREDICT_TRUE (!ip4_is_fragment (ip0)))
 551     {
 552       sum0 = ip_incremental_checksum_buffer (sm->vlib_main, b0, (u8 *) icmp0 -
 553                                              (u8 *)
 554                                              vlib_buffer_get_current (b0),
 555                                              ntohs (ip0->length) -
 556                                              ip4_header_bytes (ip0), 0);
 557       checksum0 = ~ip_csum_fold (sum0);
 558       if (checksum0 != 0 && checksum0 != 0xffff)
 559         {
 560           next0 = SNAT_OUT2IN_NEXT_DROP;
 561           goto out;
 562         }
 563     }
 564
 565   old_addr0 = ip0->dst_address.as_u32;
 566   new_addr0 = ip0->dst_address.as_u32 = sm0.addr.as_u32;
 567   vnet_buffer (b0)->sw_if_index[VLIB_TX] = sm0.fib_index;
 568
 569   sum0 = ip0->checksum;
 570   sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
 571                          dst_address /* changed member */ );
 572   ip0->checksum = ip_csum_fold (sum0);
 573
 574   if (icmp0->checksum == 0)
 575     icmp0->checksum = 0xffff;
 576
 577   if (!icmp_is_error_message (icmp0))
 578     {
 579       new_id0 = sm0.port;
 580       if (PREDICT_FALSE (new_id0 != echo0->identifier))
 581         {
 582           old_id0 = echo0->identifier;
 583           new_id0 = sm0.port;
 584           echo0->identifier = new_id0;
 585
 586           sum0 = icmp0->checksum;
 587           sum0 = ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t,
 588                                  identifier /* changed member */ );
 589           icmp0->checksum = ip_csum_fold (sum0);
 590         }
 591     }
 592   else
 593     {
 594       inner_ip0 = (ip4_header_t *) (echo0 + 1);
 595       l4_header = ip4_next_header (inner_ip0);
 596
 597       if (!ip4_header_checksum_is_valid (inner_ip0))
 598         {
 599           next0 = SNAT_OUT2IN_NEXT_DROP;
 600           goto out;
 601         }
 602
 603       old_addr0 = inner_ip0->src_address.as_u32;
 604       inner_ip0->src_address = sm0.addr;
 605       new_addr0 = inner_ip0->src_address.as_u32;
 606
 607       sum0 = icmp0->checksum;
 608       sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
 609                              src_address /* changed member */ );
 610       icmp0->checksum = ip_csum_fold (sum0);
 611
 612       switch (protocol)
 613         {
 614         case SNAT_PROTOCOL_ICMP:
 615           inner_icmp0 = (icmp46_header_t *) l4_header;
 616           inner_echo0 = (icmp_echo_header_t *) (inner_icmp0 + 1);
 617
 618           old_id0 = inner_echo0->identifier;
 619           new_id0 = sm0.port;
 620           inner_echo0->identifier = new_id0;
 621
 622           sum0 = icmp0->checksum;
 623           sum0 = ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t,
 624                                  identifier);
 625           icmp0->checksum = ip_csum_fold (sum0);
 626           break;
 627         case SNAT_PROTOCOL_UDP:
 628         case SNAT_PROTOCOL_TCP:
 629           old_id0 = ((tcp_udp_header_t *) l4_header)->src_port;
 630           new_id0 = sm0.port;
 631           ((tcp_udp_header_t *) l4_header)->src_port = new_id0;
 632
 633           sum0 = icmp0->checksum;
 634           sum0 = ip_csum_update (sum0, old_id0, new_id0, tcp_udp_header_t,
 635                                  src_port);
 636           icmp0->checksum = ip_csum_fold (sum0);
 637           break;
 638         default:
 639           ASSERT (0);
 640         }
 641     }
 642
 643 out:
 644   return next0;
 645 }
 646 #endif
 647
 648 static inline u32
 649 icmp_out2in_slow_path (snat_main_t * sm,
 650                        vlib_buffer_t * b0,
 651                        ip4_header_t * ip0,
 652                        icmp46_header_t * icmp0,
 653                        u32 sw_if_index0,
 654                        u32 rx_fib_index0,
 655                        vlib_node_runtime_t * node,
 656                        u32 next0, f64 now,
 657                        u32 thread_index, snat_session_t ** p_s0)
 658 {
 659   next0 = icmp_out2in (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
 660                        next0, thread_index, p_s0, 0);
 661   snat_session_t *s0 = *p_s0;
 662   if (PREDICT_TRUE (next0 != SNAT_OUT2IN_NEXT_DROP && s0))
 663     {
 664       /* Accounting */
 665       nat44_session_update_counters (s0, now,
 666                                      vlib_buffer_length_in_chain
 667                                      (sm->vlib_main, b0), thread_index);
 668       /* Per-user LRU list maintenance */
 669       nat44_session_update_lru (sm, s0, thread_index);
 670     }
 671   return next0;
 672 }
 673
 674 static int
 675 nat_out2in_sm_unknown_proto (snat_main_t * sm,
 676                              vlib_buffer_t * b,
 677                              ip4_header_t * ip, u32 rx_fib_index)
 678 {
 679   clib_bihash_kv_8_8_t kv, value;
 680   snat_static_mapping_t *m;
 681   snat_session_key_t m_key;
 682   u32 old_addr, new_addr;
 683   ip_csum_t sum;
 684
 685   m_key.addr = ip->dst_address;
 686   m_key.port = 0;
 687   m_key.protocol = 0;
 688   m_key.fib_index = 0;
 689   kv.key = m_key.as_u64;
 690   if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
 691     return 1;
 692
 693   m = pool_elt_at_index (sm->static_mappings, value.value);
 694
 695   old_addr = ip->dst_address.as_u32;
 696   new_addr = ip->dst_address.as_u32 = m->local_addr.as_u32;
 697   sum = ip->checksum;
 698   sum = ip_csum_update (sum, old_addr, new_addr, ip4_header_t, dst_address);
 699   ip->checksum = ip_csum_fold (sum);
 700
 701   vnet_buffer (b)->sw_if_index[VLIB_TX] = m->fib_index;
 702   return 0;
 703 }
 704
 705 VLIB_NODE_FN (snat_out2in_node) (vlib_main_t * vm,
 706                                  vlib_node_runtime_t * node,
 707                                  vlib_frame_t * frame)
 708 {
 709   u32 n_left_from, *from, *to_next;
 710   snat_out2in_next_t next_index;
 711   u32 pkts_processed = 0;
 712   snat_main_t *sm = &snat_main;
 713   f64 now = vlib_time_now (vm);
 714   u32 thread_index = vm->thread_index;
 715   u32 tcp_packets = 0, udp_packets = 0, icmp_packets = 0, other_packets =
 716     0, fragments = 0;
 717
 718   from = vlib_frame_vector_args (frame);
 719   n_left_from = frame->n_vectors;
 720   next_index = node->cached_next_index;
 721
 722   while (n_left_from > 0)
 723     {
 724       u32 n_left_to_next;
 725
 726       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
 727
 728       while (n_left_from >= 4 && n_left_to_next >= 2)
 729         {
 730           u32 bi0, bi1;
 731           vlib_buffer_t *b0, *b1;
 732           u32 next0 = SNAT_OUT2IN_NEXT_LOOKUP;
 733           u32 next1 = SNAT_OUT2IN_NEXT_LOOKUP;
 734           u32 sw_if_index0, sw_if_index1;
 735           ip4_header_t *ip0, *ip1;
 736           ip_csum_t sum0, sum1;
 737           u32 new_addr0, old_addr0;
 738           u16 new_port0, old_port0;
 739           u32 new_addr1, old_addr1;
 740           u16 new_port1, old_port1;
 741           udp_header_t *udp0, *udp1;
 742           tcp_header_t *tcp0, *tcp1;
 743           icmp46_header_t *icmp0, *icmp1;
 744           snat_session_key_t key0, key1, sm0, sm1;
 745           u32 rx_fib_index0, rx_fib_index1;
 746           u32 proto0, proto1;
 747           snat_session_t *s0 = 0, *s1 = 0;
 748           clib_bihash_kv_8_8_t kv0, kv1, value0, value1;
 749           u8 identity_nat0, identity_nat1;
 750
 751           /* Prefetch next iteration. */
 752           {
 753             vlib_buffer_t *p2, *p3;
 754
 755             p2 = vlib_get_buffer (vm, from[2]);
 756             p3 = vlib_get_buffer (vm, from[3]);
 757
 758             vlib_prefetch_buffer_header (p2, LOAD);
 759             vlib_prefetch_buffer_header (p3, LOAD);
 760
 761             CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, STORE);
 762             CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, STORE);
 763           }
 764
 765           /* speculatively enqueue b0 and b1 to the current next frame */
 766           to_next[0] = bi0 = from[0];
 767           to_next[1] = bi1 = from[1];
 768           from += 2;
 769           to_next += 2;
 770           n_left_from -= 2;
 771           n_left_to_next -= 2;
 772
 773           b0 = vlib_get_buffer (vm, bi0);
 774           b1 = vlib_get_buffer (vm, bi1);
 775
 776           vnet_buffer (b0)->snat.flags = 0;
 777           vnet_buffer (b1)->snat.flags = 0;
 778
 779           ip0 = vlib_buffer_get_current (b0);
 780           udp0 = ip4_next_header (ip0);
 781           tcp0 = (tcp_header_t *) udp0;
 782           icmp0 = (icmp46_header_t *) udp0;
 783
 784           sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
 785           rx_fib_index0 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index,
 786                                    sw_if_index0);
 787
 788           if (PREDICT_FALSE (ip0->ttl == 1))
 789             {
 790               vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
 791               icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
 792                                            ICMP4_time_exceeded_ttl_exceeded_in_transit,
 793                                            0);
 794               next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
 795               goto trace0;
 796             }
 797
 798           proto0 = ip_proto_to_snat_proto (ip0->protocol);
 799
 800           if (PREDICT_FALSE (proto0 == ~0))
 801             {
 802               if (nat_out2in_sm_unknown_proto (sm, b0, ip0, rx_fib_index0))
 803                 {
 804                   if (!sm->forwarding_enabled)
 805                     {
 806                       b0->error =
 807                         node->errors[SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL];
 808                       next0 = SNAT_OUT2IN_NEXT_DROP;
 809                     }
 810                 }
 811               other_packets++;
 812               goto trace0;
 813             }
 814
 815           if (PREDICT_FALSE (ip4_is_fragment (ip0)))
 816             {
 817               next0 = SNAT_OUT2IN_NEXT_REASS;
 818               fragments++;
 819               goto trace0;
 820             }
 821
 822           if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
 823             {
 824               next0 = icmp_out2in_slow_path
 825                 (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
 826                  next0, now, thread_index, &s0);
 827               icmp_packets++;
 828               goto trace0;
 829             }
 830
 831           key0.addr = ip0->dst_address;
 832           key0.port = udp0->dst_port;
 833           key0.protocol = proto0;
 834           key0.fib_index = rx_fib_index0;
 835
 836           kv0.key = key0.as_u64;
 837
 838           if (clib_bihash_search_8_8
 839               (&sm->per_thread_data[thread_index].out2in, &kv0, &value0))
 840             {
 841               /* Try to match static mapping by external address and port,
 842                  destination address and port in packet */
 843               if (snat_static_mapping_match
 844                   (sm, key0, &sm0, 1, 0, 0, 0, 0, &identity_nat0))
 845                 {
 846                   /*
 847                    * Send DHCP packets to the ipv4 stack, or we won't
 848                    * be able to use dhcp client on the outside interface
 849                    */
 850                   if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_UDP
 851                                      && (udp0->dst_port ==
 852                                          clib_host_to_net_u16
 853                                          (UDP_DST_PORT_dhcp_to_client))))
 854                     {
 855                       vnet_feature_next (&next0, b0);
 856                       goto trace0;
 857                     }
 858
 859                   if (!sm->forwarding_enabled)
 860                     {
 861                       b0->error =
 862                         node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
 863                       next0 = SNAT_OUT2IN_NEXT_DROP;
 864                     }
 865                   goto trace0;
 866                 }
 867
 868               if (PREDICT_FALSE (identity_nat0))
 869                 goto trace0;
 870
 871               /* Create session initiated by host from external network */
 872               s0 = create_session_for_static_mapping (sm, b0, sm0, key0, node,
 873                                                       thread_index, now);
 874               if (!s0)
 875                 {
 876                   next0 = SNAT_OUT2IN_NEXT_DROP;
 877                   goto trace0;
 878                 }
 879             }
 880           else
 881             s0 =
 882               pool_elt_at_index (sm->per_thread_data[thread_index].sessions,
 883                                  value0.value);
 884
 885           old_addr0 = ip0->dst_address.as_u32;
 886           ip0->dst_address = s0->in2out.addr;
 887           new_addr0 = ip0->dst_address.as_u32;
 888           vnet_buffer (b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
 889
 890           sum0 = ip0->checksum;
 891           sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
 892                                  ip4_header_t,
 893                                  dst_address /* changed member */ );
 894           ip0->checksum = ip_csum_fold (sum0);
 895
 896           old_port0 = udp0->dst_port;
 897           new_port0 = udp0->dst_port = s0->in2out.port;
 898
 899           if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
 900             {
 901               sum0 = tcp0->checksum;
 902               sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
 903                                      ip4_header_t,
 904                                      dst_address /* changed member */ );
 905
 906               sum0 = ip_csum_update (sum0, old_port0, new_port0,
 907                                      ip4_header_t /* cheat */ ,
 908                                      length /* changed member */ );
 909               tcp0->checksum = ip_csum_fold (sum0);
 910               tcp_packets++;
 911             }
 912           else
 913             {
 914               if (PREDICT_FALSE (udp0->checksum))
 915                 {
 916                   sum0 = udp0->checksum;
 917                   sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
 918                                          ip4_header_t,
 919                                          dst_address /* changed member */ );
 920                   sum0 = ip_csum_update (sum0, old_port0, new_port0,
 921                                          ip4_header_t /* cheat */ ,
 922                                          length /* changed member */ );
 923                   udp0->checksum = ip_csum_fold (sum0);
 924                 }
 925               udp_packets++;
 926             }
 927
 928           /* Accounting */
 929           nat44_session_update_counters (s0, now,
 930                                          vlib_buffer_length_in_chain (vm, b0),
 931                                          thread_index);
 932           /* Per-user LRU list maintenance */
 933           nat44_session_update_lru (sm, s0, thread_index);
 934         trace0:
 935
 936           if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
 937                              && (b0->flags & VLIB_BUFFER_IS_TRACED)))
 938             {
 939               snat_out2in_trace_t *t =
 940                 vlib_add_trace (vm, node, b0, sizeof (*t));
 941               t->sw_if_index = sw_if_index0;
 942               t->next_index = next0;
 943               t->session_index = ~0;
 944               if (s0)
 945                 t->session_index =
 946                   s0 - sm->per_thread_data[thread_index].sessions;
 947             }
 948
 949           pkts_processed += next0 == SNAT_OUT2IN_NEXT_LOOKUP;
 950
 951
 952           ip1 = vlib_buffer_get_current (b1);
 953           udp1 = ip4_next_header (ip1);
 954           tcp1 = (tcp_header_t *) udp1;
 955           icmp1 = (icmp46_header_t *) udp1;
 956
 957           sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
 958           rx_fib_index1 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index,
 959                                    sw_if_index1);
 960
 961           if (PREDICT_FALSE (ip1->ttl == 1))
 962             {
 963               vnet_buffer (b1)->sw_if_index[VLIB_TX] = (u32) ~ 0;
 964               icmp4_error_set_vnet_buffer (b1, ICMP4_time_exceeded,
 965                                            ICMP4_time_exceeded_ttl_exceeded_in_transit,
 966                                            0);
 967               next1 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
 968               goto trace1;
 969             }
 970
 971           proto1 = ip_proto_to_snat_proto (ip1->protocol);
 972
 973           if (PREDICT_FALSE (proto1 == ~0))
 974             {
 975               if (nat_out2in_sm_unknown_proto (sm, b1, ip1, rx_fib_index1))
 976                 {
 977                   if (!sm->forwarding_enabled)
 978                     {
 979                       b1->error =
 980                         node->errors[SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL];
 981                       next1 = SNAT_OUT2IN_NEXT_DROP;
 982                     }
 983                 }
 984               other_packets++;
 985               goto trace1;
 986             }
 987
 988           if (PREDICT_FALSE (ip4_is_fragment (ip1)))
 989             {
 990               next1 = SNAT_OUT2IN_NEXT_REASS;
 991               fragments++;
 992               goto trace1;
 993             }
 994
 995           if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_ICMP))
 996             {
 997               next1 = icmp_out2in_slow_path
 998                 (sm, b1, ip1, icmp1, sw_if_index1, rx_fib_index1, node,
 999                  next1, now, thread_index, &s1);
1000               icmp_packets++;
1001               goto trace1;
1002             }
1003
1004           key1.addr = ip1->dst_address;
1005           key1.port = udp1->dst_port;
1006           key1.protocol = proto1;
1007           key1.fib_index = rx_fib_index1;
1008
1009           kv1.key = key1.as_u64;
1010
1011           if (clib_bihash_search_8_8
1012               (&sm->per_thread_data[thread_index].out2in, &kv1, &value1))
1013             {
1014               /* Try to match static mapping by external address and port,
1015                  destination address and port in packet */
1016               if (snat_static_mapping_match
1017                   (sm, key1, &sm1, 1, 0, 0, 0, 0, &identity_nat1))
1018                 {
1019                   /*
1020                    * Send DHCP packets to the ipv4 stack, or we won't
1021                    * be able to use dhcp client on the outside interface
1022                    */
1023                   if (PREDICT_FALSE (proto1 == SNAT_PROTOCOL_UDP
1024                                      && (udp1->dst_port ==
1025                                          clib_host_to_net_u16
1026                                          (UDP_DST_PORT_dhcp_to_client))))
1027                     {
1028                       vnet_feature_next (&next1, b1);
1029                       goto trace1;
1030                     }
1031
1032                   if (!sm->forwarding_enabled)
1033                     {
1034                       b1->error =
1035                         node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
1036                       next1 = SNAT_OUT2IN_NEXT_DROP;
1037                     }
1038                   goto trace1;
1039                 }
1040
1041               if (PREDICT_FALSE (identity_nat1))
1042                 goto trace1;
1043
1044               /* Create session initiated by host from external network */
1045               s1 = create_session_for_static_mapping (sm, b1, sm1, key1, node,
1046                                                       thread_index, now);
1047               if (!s1)
1048                 {
1049                   next1 = SNAT_OUT2IN_NEXT_DROP;
1050                   goto trace1;
1051                 }
1052             }
1053           else
1054             s1 =
1055               pool_elt_at_index (sm->per_thread_data[thread_index].sessions,
1056                                  value1.value);
1057
1058           old_addr1 = ip1->dst_address.as_u32;
1059           ip1->dst_address = s1->in2out.addr;
1060           new_addr1 = ip1->dst_address.as_u32;
1061           vnet_buffer (b1)->sw_if_index[VLIB_TX] = s1->in2out.fib_index;
1062
1063           sum1 = ip1->checksum;
1064           sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
1065                                  ip4_header_t,
1066                                  dst_address /* changed member */ );
1067           ip1->checksum = ip_csum_fold (sum1);
1068
1069           old_port1 = udp1->dst_port;
1070           new_port1 = udp1->dst_port = s1->in2out.port;
1071
1072           if (PREDICT_TRUE (proto1 == SNAT_PROTOCOL_TCP))
1073             {
1074               sum1 = tcp1->checksum;
1075               sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
1076                                      ip4_header_t,
1077                                      dst_address /* changed member */ );
1078
1079               sum1 = ip_csum_update (sum1, old_port1, new_port1,
1080                                      ip4_header_t /* cheat */ ,
1081                                      length /* changed member */ );
1082               tcp1->checksum = ip_csum_fold (sum1);
1083               tcp_packets++;
1084             }
1085           else
1086             {
1087               if (PREDICT_FALSE (udp1->checksum))
1088                 {
1089                   sum1 = udp1->checksum;
1090                   sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
1091                                          ip4_header_t,
1092                                          dst_address /* changed member */ );
1093                   sum1 = ip_csum_update (sum1, old_port1, new_port1,
1094                                          ip4_header_t /* cheat */ ,
1095                                          length /* changed member */ );
1096                   udp1->checksum = ip_csum_fold (sum1);
1097                 }
1098               udp_packets++;
1099             }
1100
1101           /* Accounting */
1102           nat44_session_update_counters (s1, now,
1103                                          vlib_buffer_length_in_chain (vm, b1),
1104                                          thread_index);
1105           /* Per-user LRU list maintenance */
1106           nat44_session_update_lru (sm, s1, thread_index);
1107         trace1:
1108
1109           if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
1110                              && (b1->flags & VLIB_BUFFER_IS_TRACED)))
1111             {
1112               snat_out2in_trace_t *t =
1113                 vlib_add_trace (vm, node, b1, sizeof (*t));
1114               t->sw_if_index = sw_if_index1;
1115               t->next_index = next1;
1116               t->session_index = ~0;
1117               if (s1)
1118                 t->session_index =
1119                   s1 - sm->per_thread_data[thread_index].sessions;
1120             }
1121
1122           pkts_processed += next1 == SNAT_OUT2IN_NEXT_LOOKUP;
1123
1124           /* verify speculative enqueues, maybe switch current next frame */
1125           vlib_validate_buffer_enqueue_x2 (vm, node, next_index,
1126                                            to_next, n_left_to_next,
1127                                            bi0, bi1, next0, next1);
1128         }
1129
1130       while (n_left_from > 0 && n_left_to_next > 0)
1131         {
1132           u32 bi0;
1133           vlib_buffer_t *b0;
1134           u32 next0 = SNAT_OUT2IN_NEXT_LOOKUP;
1135           u32 sw_if_index0;
1136           ip4_header_t *ip0;
1137           ip_csum_t sum0;
1138           u32 new_addr0, old_addr0;
1139           u16 new_port0, old_port0;
1140           udp_header_t *udp0;
1141           tcp_header_t *tcp0;
1142           icmp46_header_t *icmp0;
1143           snat_session_key_t key0, sm0;
1144           u32 rx_fib_index0;
1145           u32 proto0;
1146           snat_session_t *s0 = 0;
1147           clib_bihash_kv_8_8_t kv0, value0;
1148           u8 identity_nat0;
1149
1150           /* speculatively enqueue b0 to the current next frame */
1151           bi0 = from[0];
1152           to_next[0] = bi0;
1153           from += 1;
1154           to_next += 1;
1155           n_left_from -= 1;
1156           n_left_to_next -= 1;
1157
1158           b0 = vlib_get_buffer (vm, bi0);
1159
1160           vnet_buffer (b0)->snat.flags = 0;
1161
1162           ip0 = vlib_buffer_get_current (b0);
1163           udp0 = ip4_next_header (ip0);
1164           tcp0 = (tcp_header_t *) udp0;
1165           icmp0 = (icmp46_header_t *) udp0;
1166
1167           sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
1168           rx_fib_index0 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index,
1169                                    sw_if_index0);
1170
1171           proto0 = ip_proto_to_snat_proto (ip0->protocol);
1172
1173           if (PREDICT_FALSE (proto0 == ~0))
1174             {
1175               if (nat_out2in_sm_unknown_proto (sm, b0, ip0, rx_fib_index0))
1176                 {
1177                   if (!sm->forwarding_enabled)
1178                     {
1179                       b0->error =
1180                         node->errors[SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL];
1181                       next0 = SNAT_OUT2IN_NEXT_DROP;
1182                     }
1183                 }
1184               other_packets++;
1185               goto trace00;
1186             }
1187
1188           if (PREDICT_FALSE (ip0->ttl == 1))
1189             {
1190               vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
1191               icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
1192                                            ICMP4_time_exceeded_ttl_exceeded_in_transit,
1193                                            0);
1194               next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
1195               goto trace00;
1196             }
1197
1198           if (PREDICT_FALSE (ip4_is_fragment (ip0)))
1199             {
1200               next0 = SNAT_OUT2IN_NEXT_REASS;
1201               fragments++;
1202               goto trace00;
1203             }
1204
1205           if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
1206             {
1207               next0 = icmp_out2in_slow_path
1208                 (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
1209                  next0, now, thread_index, &s0);
1210               icmp_packets++;
1211               goto trace00;
1212             }
1213
1214           key0.addr = ip0->dst_address;
1215           key0.port = udp0->dst_port;
1216           key0.protocol = proto0;
1217           key0.fib_index = rx_fib_index0;
1218
1219           kv0.key = key0.as_u64;
1220
1221           if (clib_bihash_search_8_8
1222               (&sm->per_thread_data[thread_index].out2in, &kv0, &value0))
1223             {
1224               /* Try to match static mapping by external address and port,
1225                  destination address and port in packet */
1226               if (snat_static_mapping_match
1227                   (sm, key0, &sm0, 1, 0, 0, 0, 0, &identity_nat0))
1228                 {
1229                   /*
1230                    * Send DHCP packets to the ipv4 stack, or we won't
1231                    * be able to use dhcp client on the outside interface
1232                    */
1233                   if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_UDP
1234                                      && (udp0->dst_port ==
1235                                          clib_host_to_net_u16
1236                                          (UDP_DST_PORT_dhcp_to_client))))
1237                     {
1238                       vnet_feature_next (&next0, b0);
1239                       goto trace00;
1240                     }
1241
1242                   if (!sm->forwarding_enabled)
1243                     {
1244                       b0->error =
1245                         node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
1246                       next0 = SNAT_OUT2IN_NEXT_DROP;
1247                     }
1248                   goto trace00;
1249                 }
1250
1251               if (PREDICT_FALSE (identity_nat0))
1252                 goto trace00;
1253
1254               /* Create session initiated by host from external network */
1255               s0 = create_session_for_static_mapping (sm, b0, sm0, key0, node,
1256                                                       thread_index, now);
1257               if (!s0)
1258                 {
1259                   next0 = SNAT_OUT2IN_NEXT_DROP;
1260                   goto trace00;
1261                 }
1262             }
1263           else
1264             s0 =
1265               pool_elt_at_index (sm->per_thread_data[thread_index].sessions,
1266                                  value0.value);
1267
1268           old_addr0 = ip0->dst_address.as_u32;
1269           ip0->dst_address = s0->in2out.addr;
1270           new_addr0 = ip0->dst_address.as_u32;
1271           vnet_buffer (b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
1272
1273           sum0 = ip0->checksum;
1274           sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1275                                  ip4_header_t,
1276                                  dst_address /* changed member */ );
1277           ip0->checksum = ip_csum_fold (sum0);
1278
1279           old_port0 = udp0->dst_port;
1280           new_port0 = udp0->dst_port = s0->in2out.port;
1281
1282           if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
1283             {
1284               sum0 = tcp0->checksum;
1285               sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1286                                      ip4_header_t,
1287                                      dst_address /* changed member */ );
1288
1289               sum0 = ip_csum_update (sum0, old_port0, new_port0,
1290                                      ip4_header_t /* cheat */ ,
1291                                      length /* changed member */ );
1292               tcp0->checksum = ip_csum_fold (sum0);
1293               tcp_packets++;
1294             }
1295           else
1296             {
1297               if (PREDICT_FALSE (udp0->checksum))
1298                 {
1299                   sum0 = udp0->checksum;
1300                   sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1301                                          ip4_header_t,
1302                                          dst_address /* changed member */ );
1303                   sum0 = ip_csum_update (sum0, old_port0, new_port0,
1304                                          ip4_header_t /* cheat */ ,
1305                                          length /* changed member */ );
1306                   udp0->checksum = ip_csum_fold (sum0);
1307                 }
1308               udp_packets++;
1309             }
1310
1311           /* Accounting */
1312           nat44_session_update_counters (s0, now,
1313                                          vlib_buffer_length_in_chain (vm, b0),
1314                                          thread_index);
1315           /* Per-user LRU list maintenance */
1316           nat44_session_update_lru (sm, s0, thread_index);
1317         trace00:
1318
1319           if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
1320                              && (b0->flags & VLIB_BUFFER_IS_TRACED)))
1321             {
1322               snat_out2in_trace_t *t =
1323                 vlib_add_trace (vm, node, b0, sizeof (*t));
1324               t->sw_if_index = sw_if_index0;
1325               t->next_index = next0;
1326               t->session_index = ~0;
1327               if (s0)
1328                 t->session_index =
1329                   s0 - sm->per_thread_data[thread_index].sessions;
1330             }
1331
1332           pkts_processed += next0 == SNAT_OUT2IN_NEXT_LOOKUP;
1333
1334           /* verify speculative enqueue, maybe switch current next frame */
1335           vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
1336                                            to_next, n_left_to_next,
1337                                            bi0, next0);
1338         }
1339
1340       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
1341     }
1342
1343   vlib_node_increment_counter (vm, sm->out2in_node_index,
1344                                SNAT_OUT2IN_ERROR_OUT2IN_PACKETS,
1345                                pkts_processed);
1346   vlib_node_increment_counter (vm, sm->out2in_node_index,
1347                                SNAT_OUT2IN_ERROR_TCP_PACKETS, tcp_packets);
1348   vlib_node_increment_counter (vm, sm->out2in_node_index,
1349                                SNAT_OUT2IN_ERROR_UDP_PACKETS, udp_packets);
1350   vlib_node_increment_counter (vm, sm->out2in_node_index,
1351                                SNAT_OUT2IN_ERROR_ICMP_PACKETS, icmp_packets);
1352   vlib_node_increment_counter (vm, sm->out2in_node_index,
1353                                SNAT_OUT2IN_ERROR_OTHER_PACKETS,
1354                                other_packets);
1355   vlib_node_increment_counter (vm, sm->out2in_node_index,
1356                                SNAT_OUT2IN_ERROR_FRAGMENTS, fragments);
1357
1358   return frame->n_vectors;
1359 }
1360
1361 /* *INDENT-OFF* */
1362 VLIB_REGISTER_NODE (snat_out2in_node) = {
1363   .name = "nat44-out2in",
1364   .vector_size = sizeof (u32),
1365   .format_trace = format_snat_out2in_trace,
1366   .type = VLIB_NODE_TYPE_INTERNAL,
1367
1368   .n_errors = ARRAY_LEN(snat_out2in_error_strings),
1369   .error_strings = snat_out2in_error_strings,
1370
1371   .runtime_data_bytes = sizeof (snat_runtime_t),
1372
1373   .n_next_nodes = SNAT_OUT2IN_N_NEXT,
1374
1375   /* edit / add dispositions here */
1376   .next_nodes = {
1377     [SNAT_OUT2IN_NEXT_DROP] = "error-drop",
1378     [SNAT_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
1379     [SNAT_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
1380     [SNAT_OUT2IN_NEXT_REASS] = "nat44-out2in-reass",
1381   },
1382 };
1383 /* *INDENT-ON* */
1384
1385 VLIB_NODE_FN (nat44_out2in_reass_node) (vlib_main_t * vm,
1386                                         vlib_node_runtime_t * node,
1387                                         vlib_frame_t * frame)
1388 {
1389   u32 n_left_from, *from, *to_next;
1390   snat_out2in_next_t next_index;
1391   u32 pkts_processed = 0, cached_fragments = 0;
1392   snat_main_t *sm = &snat_main;
1393   f64 now = vlib_time_now (vm);
1394   u32 thread_index = vm->thread_index;
1395   snat_main_per_thread_data_t *per_thread_data =
1396     &sm->per_thread_data[thread_index];
1397   u32 *fragments_to_drop = 0;
1398   u32 *fragments_to_loopback = 0;
1399
1400   from = vlib_frame_vector_args (frame);
1401   n_left_from = frame->n_vectors;
1402   next_index = node->cached_next_index;
1403
1404   while (n_left_from > 0)
1405     {
1406       u32 n_left_to_next;
1407
1408       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
1409
1410       while (n_left_from > 0 && n_left_to_next > 0)
1411         {
1412           u32 bi0, sw_if_index0, proto0, rx_fib_index0, new_addr0, old_addr0;
1413           vlib_buffer_t *b0;
1414           u32 next0;
1415           u8 cached0 = 0;
1416           ip4_header_t *ip0;
1417           nat_reass_ip4_t *reass0;
1418           udp_header_t *udp0;
1419           tcp_header_t *tcp0;
1420           icmp46_header_t *icmp0;
1421           snat_session_key_t key0, sm0;
1422           clib_bihash_kv_8_8_t kv0, value0;
1423           snat_session_t *s0 = 0;
1424           u16 old_port0, new_port0;
1425           ip_csum_t sum0;
1426           u8 identity_nat0;
1427
1428           /* speculatively enqueue b0 to the current next frame */
1429           bi0 = from[0];
1430           to_next[0] = bi0;
1431           from += 1;
1432           to_next += 1;
1433           n_left_from -= 1;
1434           n_left_to_next -= 1;
1435
1436           b0 = vlib_get_buffer (vm, bi0);
1437           next0 = SNAT_OUT2IN_NEXT_LOOKUP;
1438
1439           sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
1440           rx_fib_index0 =
1441             fib_table_get_index_for_sw_if_index (FIB_PROTOCOL_IP4,
1442                                                  sw_if_index0);
1443
1444           if (PREDICT_FALSE (nat_reass_is_drop_frag (0)))
1445             {
1446               next0 = SNAT_OUT2IN_NEXT_DROP;
1447               b0->error = node->errors[SNAT_OUT2IN_ERROR_DROP_FRAGMENT];
1448               goto trace0;
1449             }
1450
1451           ip0 = (ip4_header_t *) vlib_buffer_get_current (b0);
1452           udp0 = ip4_next_header (ip0);
1453           tcp0 = (tcp_header_t *) udp0;
1454           icmp0 = (icmp46_header_t *) udp0;
1455           proto0 = ip_proto_to_snat_proto (ip0->protocol);
1456
1457           reass0 = nat_ip4_reass_find_or_create (ip0->src_address,
1458                                                  ip0->dst_address,
1459                                                  ip0->fragment_id,
1460                                                  ip0->protocol,
1461                                                  1, &fragments_to_drop);
1462
1463           if (PREDICT_FALSE (!reass0))
1464             {
1465               next0 = SNAT_OUT2IN_NEXT_DROP;
1466               b0->error = node->errors[SNAT_OUT2IN_ERROR_MAX_REASS];
1467               nat_elog_notice ("maximum reassemblies exceeded");
1468               goto trace0;
1469             }
1470
1471           if (PREDICT_FALSE (ip4_is_first_fragment (ip0)))
1472             {
1473               if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
1474                 {
1475                   next0 = icmp_out2in_slow_path
1476                     (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
1477                      next0, now, thread_index, &s0);
1478
1479                   if (PREDICT_TRUE (next0 != SNAT_OUT2IN_NEXT_DROP))
1480                     {
1481                       if (s0)
1482                         reass0->sess_index = s0 - per_thread_data->sessions;
1483                       else
1484                         reass0->flags |= NAT_REASS_FLAG_ED_DONT_TRANSLATE;
1485                       reass0->thread_index = thread_index;
1486                       nat_ip4_reass_get_frags (reass0,
1487                                                &fragments_to_loopback);
1488                     }
1489
1490                   goto trace0;
1491                 }
1492
1493               key0.addr = ip0->dst_address;
1494               key0.port = udp0->dst_port;
1495               key0.protocol = proto0;
1496               key0.fib_index = rx_fib_index0;
1497               kv0.key = key0.as_u64;
1498
1499               if (clib_bihash_search_8_8
1500                   (&per_thread_data->out2in, &kv0, &value0))
1501                 {
1502                   /* Try to match static mapping by external address and port,
1503                      destination address and port in packet */
1504                   if (snat_static_mapping_match
1505                       (sm, key0, &sm0, 1, 0, 0, 0, 0, &identity_nat0))
1506                     {
1507                       /*
1508                        * Send DHCP packets to the ipv4 stack, or we won't
1509                        * be able to use dhcp client on the outside interface
1510                        */
1511                       if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_UDP
1512                                          && (udp0->dst_port
1513                                              ==
1514                                              clib_host_to_net_u16
1515                                              (UDP_DST_PORT_dhcp_to_client))))
1516                         {
1517                           vnet_feature_next (&next0, b0);
1518                           goto trace0;
1519                         }
1520
1521                       if (!sm->forwarding_enabled)
1522                         {
1523                           b0->error =
1524                             node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
1525                           next0 = SNAT_OUT2IN_NEXT_DROP;
1526                         }
1527                       else
1528                         {
1529                           reass0->flags |= NAT_REASS_FLAG_ED_DONT_TRANSLATE;
1530                           nat_ip4_reass_get_frags (reass0,
1531                                                    &fragments_to_loopback);
1532                         }
1533                       goto trace0;
1534                     }
1535
1536                   if (PREDICT_FALSE (identity_nat0))
1537                     goto trace0;
1538
1539                   /* Create session initiated by host from external network */
1540                   s0 =
1541                     create_session_for_static_mapping (sm, b0, sm0, key0,
1542                                                        node, thread_index,
1543                                                        now);
1544                   if (!s0)
1545                     {
1546                       b0->error =
1547                         node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
1548                       next0 = SNAT_OUT2IN_NEXT_DROP;
1549                       goto trace0;
1550                     }
1551                   reass0->sess_index = s0 - per_thread_data->sessions;
1552                   reass0->thread_index = thread_index;
1553                 }
1554               else
1555                 {
1556                   s0 = pool_elt_at_index (per_thread_data->sessions,
1557                                           value0.value);
1558                   reass0->sess_index = value0.value;
1559                 }
1560               nat_ip4_reass_get_frags (reass0, &fragments_to_loopback);
1561             }
1562           else
1563             {
1564               if (reass0->flags & NAT_REASS_FLAG_ED_DONT_TRANSLATE)
1565                 goto trace0;
1566               if (PREDICT_FALSE (reass0->sess_index == (u32) ~ 0))
1567                 {
1568                   if (nat_ip4_reass_add_fragment
1569                       (thread_index, reass0, bi0, &fragments_to_drop))
1570                     {
1571                       b0->error = node->errors[SNAT_OUT2IN_ERROR_MAX_FRAG];
1572                       nat_elog_notice
1573                         ("maximum fragments per reassembly exceeded");
1574                       next0 = SNAT_OUT2IN_NEXT_DROP;
1575                       goto trace0;
1576                     }
1577                   cached0 = 1;
1578                   goto trace0;
1579                 }
1580               s0 = pool_elt_at_index (per_thread_data->sessions,
1581                                       reass0->sess_index);
1582             }
1583
1584           old_addr0 = ip0->dst_address.as_u32;
1585           ip0->dst_address = s0->in2out.addr;
1586           new_addr0 = ip0->dst_address.as_u32;
1587           vnet_buffer (b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
1588
1589           sum0 = ip0->checksum;
1590           sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1591                                  ip4_header_t,
1592                                  dst_address /* changed member */ );
1593           ip0->checksum = ip_csum_fold (sum0);
1594
1595           if (PREDICT_FALSE (ip4_is_first_fragment (ip0)))
1596             {
1597               old_port0 = udp0->dst_port;
1598               new_port0 = udp0->dst_port = s0->in2out.port;
1599
1600               if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
1601                 {
1602                   sum0 = tcp0->checksum;
1603                   sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1604                                          ip4_header_t,
1605                                          dst_address /* changed member */ );
1606
1607                   sum0 = ip_csum_update (sum0, old_port0, new_port0,
1608                                          ip4_header_t /* cheat */ ,
1609                                          length /* changed member */ );
1610                   tcp0->checksum = ip_csum_fold (sum0);
1611                 }
1612               else if (udp0->checksum)
1613                 {
1614                   sum0 = udp0->checksum;
1615                   sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1616                                          ip4_header_t,
1617                                          dst_address /* changed member */ );
1618                   sum0 = ip_csum_update (sum0, old_port0, new_port0,
1619                                          ip4_header_t /* cheat */ ,
1620                                          length /* changed member */ );
1621                   udp0->checksum = ip_csum_fold (sum0);
1622                 }
1623             }
1624
1625           /* Accounting */
1626           nat44_session_update_counters (s0, now,
1627                                          vlib_buffer_length_in_chain (vm, b0),
1628                                          thread_index);
1629           /* Per-user LRU list maintenance */
1630           nat44_session_update_lru (sm, s0, thread_index);
1631
1632         trace0:
1633           if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
1634                              && (b0->flags & VLIB_BUFFER_IS_TRACED)))
1635             {
1636               nat44_reass_trace_t *t =
1637                 vlib_add_trace (vm, node, b0, sizeof (*t));
1638               t->cached = cached0;
1639               t->sw_if_index = sw_if_index0;
1640               t->next_index = next0;
1641             }
1642
1643           if (cached0)
1644             {
1645               n_left_to_next++;
1646               to_next--;
1647               cached_fragments++;
1648             }
1649           else
1650             {
1651               pkts_processed += next0 != SNAT_OUT2IN_NEXT_DROP;
1652
1653               /* verify speculative enqueue, maybe switch current next frame */
1654               vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
1655                                                to_next, n_left_to_next,
1656                                                bi0, next0);
1657             }
1658
1659           if (n_left_from == 0 && vec_len (fragments_to_loopback))
1660             {
1661               from = vlib_frame_vector_args (frame);
1662               u32 len = vec_len (fragments_to_loopback);
1663               if (len <= VLIB_FRAME_SIZE)
1664                 {
1665                   clib_memcpy_fast (from, fragments_to_loopback,
1666                                     sizeof (u32) * len);
1667                   n_left_from = len;
1668                   vec_reset_length (fragments_to_loopback);
1669                 }
1670               else
1671                 {
1672                   clib_memcpy_fast (from, fragments_to_loopback +
1673                                     (len - VLIB_FRAME_SIZE),
1674                                     sizeof (u32) * VLIB_FRAME_SIZE);
1675                   n_left_from = VLIB_FRAME_SIZE;
1676                   _vec_len (fragments_to_loopback) = len - VLIB_FRAME_SIZE;
1677                 }
1678             }
1679         }
1680
1681       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
1682     }
1683
1684   vlib_node_increment_counter (vm, sm->out2in_reass_node_index,
1685                                SNAT_OUT2IN_ERROR_PROCESSED_FRAGMENTS,
1686                                pkts_processed);
1687   vlib_node_increment_counter (vm, sm->out2in_reass_node_index,
1688                                SNAT_OUT2IN_ERROR_CACHED_FRAGMENTS,
1689                                cached_fragments);
1690
1691   nat_send_all_to_node (vm, fragments_to_drop, node,
1692                         &node->errors[SNAT_OUT2IN_ERROR_DROP_FRAGMENT],
1693                         SNAT_OUT2IN_NEXT_DROP);
1694
1695   vec_free (fragments_to_drop);
1696   vec_free (fragments_to_loopback);
1697   return frame->n_vectors;
1698 }
1699
1700 /* *INDENT-OFF* */
1701 VLIB_REGISTER_NODE (nat44_out2in_reass_node) = {
1702   .name = "nat44-out2in-reass",
1703   .vector_size = sizeof (u32),
1704   .format_trace = format_nat44_reass_trace,
1705   .type = VLIB_NODE_TYPE_INTERNAL,
1706
1707   .n_errors = ARRAY_LEN(snat_out2in_error_strings),
1708   .error_strings = snat_out2in_error_strings,
1709
1710   .n_next_nodes = SNAT_OUT2IN_N_NEXT,
1711
1712   /* edit / add dispositions here */
1713   .next_nodes = {
1714     [SNAT_OUT2IN_NEXT_DROP] = "error-drop",
1715     [SNAT_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
1716     [SNAT_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
1717     [SNAT_OUT2IN_NEXT_REASS] = "nat44-out2in-reass",
1718   },
1719 };
1720 /* *INDENT-ON* */
1721
1722 VLIB_NODE_FN (snat_out2in_fast_node) (vlib_main_t * vm,
1723                                       vlib_node_runtime_t * node,
1724                                       vlib_frame_t * frame)
1725 {
1726   u32 n_left_from, *from, *to_next;
1727   snat_out2in_next_t next_index;
1728   u32 pkts_processed = 0;
1729   snat_main_t *sm = &snat_main;
1730
1731   from = vlib_frame_vector_args (frame);
1732   n_left_from = frame->n_vectors;
1733   next_index = node->cached_next_index;
1734
1735   while (n_left_from > 0)
1736     {
1737       u32 n_left_to_next;
1738
1739       vlib_get_next_frame (vm, node, next_index, to_next, n_left_to_next);
1740
1741       while (n_left_from > 0 && n_left_to_next > 0)
1742         {
1743           u32 bi0;
1744           vlib_buffer_t *b0;
1745           u32 next0 = SNAT_OUT2IN_NEXT_DROP;
1746           u32 sw_if_index0;
1747           ip4_header_t *ip0;
1748           ip_csum_t sum0;
1749           u32 new_addr0, old_addr0;
1750           u16 new_port0, old_port0;
1751           udp_header_t *udp0;
1752           tcp_header_t *tcp0;
1753           icmp46_header_t *icmp0;
1754           snat_session_key_t key0, sm0;
1755           u32 proto0;
1756           u32 rx_fib_index0;
1757
1758           /* speculatively enqueue b0 to the current next frame */
1759           bi0 = from[0];
1760           to_next[0] = bi0;
1761           from += 1;
1762           to_next += 1;
1763           n_left_from -= 1;
1764           n_left_to_next -= 1;
1765
1766           b0 = vlib_get_buffer (vm, bi0);
1767
1768           ip0 = vlib_buffer_get_current (b0);
1769           udp0 = ip4_next_header (ip0);
1770           tcp0 = (tcp_header_t *) udp0;
1771           icmp0 = (icmp46_header_t *) udp0;
1772
1773           sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
1774           rx_fib_index0 =
1775             ip4_fib_table_get_index_for_sw_if_index (sw_if_index0);
1776
1777           vnet_feature_next (&next0, b0);
1778
1779           if (PREDICT_FALSE (ip0->ttl == 1))
1780             {
1781               vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
1782               icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
1783                                            ICMP4_time_exceeded_ttl_exceeded_in_transit,
1784                                            0);
1785               next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
1786               goto trace00;
1787             }
1788
1789           proto0 = ip_proto_to_snat_proto (ip0->protocol);
1790
1791           if (PREDICT_FALSE (proto0 == ~0))
1792             goto trace00;
1793
1794           if (PREDICT_FALSE (proto0 == SNAT_PROTOCOL_ICMP))
1795             {
1796               next0 = icmp_out2in (sm, b0, ip0, icmp0, sw_if_index0,
1797                                    rx_fib_index0, node, next0, ~0, 0, 0);
1798               goto trace00;
1799             }
1800
1801           key0.addr = ip0->dst_address;
1802           key0.port = udp0->dst_port;
1803           key0.fib_index = rx_fib_index0;
1804
1805           if (snat_static_mapping_match (sm, key0, &sm0, 1, 0, 0, 0, 0, 0))
1806             {
1807               b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
1808               goto trace00;
1809             }
1810
1811           new_addr0 = sm0.addr.as_u32;
1812           new_port0 = sm0.port;
1813           vnet_buffer (b0)->sw_if_index[VLIB_TX] = sm0.fib_index;
1814           old_addr0 = ip0->dst_address.as_u32;
1815           ip0->dst_address.as_u32 = new_addr0;
1816
1817           sum0 = ip0->checksum;
1818           sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1819                                  ip4_header_t,
1820                                  dst_address /* changed member */ );
1821           ip0->checksum = ip_csum_fold (sum0);
1822
1823           if (PREDICT_FALSE (new_port0 != udp0->dst_port))
1824             {
1825               old_port0 = udp0->dst_port;
1826               udp0->dst_port = new_port0;
1827
1828               if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
1829                 {
1830                   sum0 = tcp0->checksum;
1831                   sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1832                                          ip4_header_t,
1833                                          dst_address /* changed member */ );
1834                   sum0 = ip_csum_update (sum0, old_port0, new_port0,
1835                                          ip4_header_t /* cheat */ ,
1836                                          length /* changed member */ );
1837                   tcp0->checksum = ip_csum_fold (sum0);
1838                 }
1839               else if (udp0->checksum)
1840                 {
1841                   sum0 = udp0->checksum;
1842                   sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1843                                          ip4_header_t,
1844                                          dst_address /* changed member */ );
1845                   sum0 = ip_csum_update (sum0, old_port0, new_port0,
1846                                          ip4_header_t /* cheat */ ,
1847                                          length /* changed member */ );
1848                   udp0->checksum = ip_csum_fold (sum0);
1849                 }
1850             }
1851           else
1852             {
1853               if (PREDICT_TRUE (proto0 == SNAT_PROTOCOL_TCP))
1854                 {
1855                   sum0 = tcp0->checksum;
1856                   sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1857                                          ip4_header_t,
1858                                          dst_address /* changed member */ );
1859                   tcp0->checksum = ip_csum_fold (sum0);
1860                 }
1861               else if (udp0->checksum)
1862                 {
1863                   sum0 = udp0->checksum;
1864                   sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1865                                          ip4_header_t,
1866                                          dst_address /* changed member */ );
1867                   udp0->checksum = ip_csum_fold (sum0);
1868                 }
1869             }
1870
1871         trace00:
1872
1873           if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
1874                              && (b0->flags & VLIB_BUFFER_IS_TRACED)))
1875             {
1876               snat_out2in_trace_t *t =
1877                 vlib_add_trace (vm, node, b0, sizeof (*t));
1878               t->sw_if_index = sw_if_index0;
1879               t->next_index = next0;
1880             }
1881
1882           pkts_processed += next0 != SNAT_OUT2IN_NEXT_DROP;
1883
1884           /* verify speculative enqueue, maybe switch current next frame */
1885           vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
1886                                            to_next, n_left_to_next,
1887                                            bi0, next0);
1888         }
1889
1890       vlib_put_next_frame (vm, node, next_index, n_left_to_next);
1891     }
1892
1893   vlib_node_increment_counter (vm, sm->out2in_fast_node_index,
1894                                SNAT_OUT2IN_ERROR_OUT2IN_PACKETS,
1895                                pkts_processed);
1896   return frame->n_vectors;
1897 }
1898
1899 /* *INDENT-OFF* */
1900 VLIB_REGISTER_NODE (snat_out2in_fast_node) = {
1901   .name = "nat44-out2in-fast",
1902   .vector_size = sizeof (u32),
1903   .format_trace = format_snat_out2in_fast_trace,
1904   .type = VLIB_NODE_TYPE_INTERNAL,
1905
1906   .n_errors = ARRAY_LEN(snat_out2in_error_strings),
1907   .error_strings = snat_out2in_error_strings,
1908
1909   .runtime_data_bytes = sizeof (snat_runtime_t),
1910
1911   .n_next_nodes = SNAT_OUT2IN_N_NEXT,
1912
1913   /* edit / add dispositions here */
1914   .next_nodes = {
1915     [SNAT_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
1916     [SNAT_OUT2IN_NEXT_DROP] = "error-drop",
1917     [SNAT_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
1918     [SNAT_OUT2IN_NEXT_REASS] = "nat44-out2in-reass",
1919   },
1920 };
1921 /* *INDENT-ON* */
1922
1923 /*
1924  * fd.io coding-style-patch-verification: ON
1925  *
1926  * Local Variables:
1927  * eval: (c-set-style "gnu")
1928  * End:
1929  */