src/plugins/nat/nat44-ei/nat44_ei_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
  23 #include <vnet/ip/ip.h>
  24 #include <vnet/udp/udp_local.h>
  25 #include <vnet/ethernet/ethernet.h>
  26 #include <vnet/fib/ip4_fib.h>
  27 #include <nat/nat.h>
  28 #include <nat/lib/ipfix_logging.h>
  29 #include <nat/nat_inlines.h>
  30 #include <nat/lib/nat_syslog.h>
  31 #include <nat/nat44-ei/nat44_ei_inlines.h>
  32 #include <nat/nat44-ei/nat44_ei.h>
  33
  34 #include <vppinfra/hash.h>
  35 #include <vppinfra/error.h>
  36 #include <vppinfra/elog.h>
  37
  38 typedef struct
  39 {
  40   u32 sw_if_index;
  41   u32 next_index;
  42   u32 session_index;
  43 } snat_out2in_trace_t;
  44
  45 /* packet trace format function */
  46 static u8 *
  47 format_snat_out2in_trace (u8 * s, va_list * args)
  48 {
  49   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  50   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  51   snat_out2in_trace_t *t = va_arg (*args, snat_out2in_trace_t *);
  52
  53   s =
  54     format (s,
  55             "NAT44_OUT2IN: sw_if_index %d, next index %d, session index %d",
  56             t->sw_if_index, t->next_index, t->session_index);
  57   return s;
  58 }
  59
  60 static u8 *
  61 format_snat_out2in_fast_trace (u8 * s, va_list * args)
  62 {
  63   CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  64   CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  65   snat_out2in_trace_t *t = va_arg (*args, snat_out2in_trace_t *);
  66
  67   s = format (s, "NAT44_OUT2IN_FAST: sw_if_index %d, next index %d",
  68               t->sw_if_index, t->next_index);
  69   return s;
  70 }
  71
  72 #define foreach_snat_out2in_error                       \
  73 _(UNSUPPORTED_PROTOCOL, "unsupported protocol")         \
  74 _(OUT_OF_PORTS, "out of ports")                         \
  75 _(BAD_ICMP_TYPE, "unsupported ICMP type")               \
  76 _(NO_TRANSLATION, "no translation")                     \
  77 _(MAX_SESSIONS_EXCEEDED, "maximum sessions exceeded")   \
  78 _(CANNOT_CREATE_USER, "cannot create NAT user")
  79
  80 typedef enum
  81 {
  82 #define _(sym,str) SNAT_OUT2IN_ERROR_##sym,
  83   foreach_snat_out2in_error
  84 #undef _
  85     SNAT_OUT2IN_N_ERROR,
  86 } snat_out2in_error_t;
  87
  88 static char *snat_out2in_error_strings[] = {
  89 #define _(sym,string) string,
  90   foreach_snat_out2in_error
  91 #undef _
  92 };
  93
  94 typedef enum
  95 {
  96   SNAT_OUT2IN_NEXT_DROP,
  97   SNAT_OUT2IN_NEXT_LOOKUP,
  98   SNAT_OUT2IN_NEXT_ICMP_ERROR,
  99   SNAT_OUT2IN_N_NEXT,
 100 } snat_out2in_next_t;
 101
 102 #ifndef CLIB_MARCH_VARIANT
 103 int
 104 nat44_o2i_is_idle_session_cb (clib_bihash_kv_8_8_t * kv, void *arg)
 105 {
 106   snat_main_t *sm = &snat_main;
 107   nat44_is_idle_session_ctx_t *ctx = arg;
 108   snat_session_t *s;
 109   u64 sess_timeout_time;
 110   snat_main_per_thread_data_t *tsm = vec_elt_at_index (sm->per_thread_data,
 111                                                        ctx->thread_index);
 112   clib_bihash_kv_8_8_t s_kv;
 113
 114   s = pool_elt_at_index (tsm->sessions, kv->value);
 115   sess_timeout_time = s->last_heard + (f64) nat44_session_get_timeout (sm, s);
 116   if (ctx->now >= sess_timeout_time)
 117     {
 118       init_nat_i2o_k (&s_kv, s);
 119       if (clib_bihash_add_del_8_8 (&sm->in2out, &s_kv, 0))
 120         nat_elog_warn ("out2in key del failed");
 121
 122       nat_ipfix_logging_nat44_ses_delete (ctx->thread_index,
 123                                           s->in2out.addr.as_u32,
 124                                           s->out2in.addr.as_u32,
 125                                           s->nat_proto,
 126                                           s->in2out.port,
 127                                           s->out2in.port,
 128                                           s->in2out.fib_index);
 129
 130       nat_syslog_nat44_apmdel (s->user_index, s->in2out.fib_index,
 131                                &s->in2out.addr, s->in2out.port,
 132                                &s->out2in.addr, s->out2in.port, s->nat_proto);
 133
 134       nat_ha_sdel (&s->out2in.addr, s->out2in.port, &s->ext_host_addr,
 135                    s->ext_host_port, s->nat_proto, s->out2in.fib_index,
 136                    ctx->thread_index);
 137
 138       if (!snat_is_session_static (s))
 139         snat_free_outside_address_and_port (sm->addresses, ctx->thread_index,
 140                                             &s->out2in.addr, s->out2in.port,
 141                                             s->nat_proto);
 142
 143       nat44_delete_session (sm, s, ctx->thread_index);
 144       return 1;
 145     }
 146
 147   return 0;
 148 }
 149 #endif
 150
 151 /**
 152  * @brief Create session for static mapping.
 153  *
 154  * Create NAT session initiated by host from external network with static
 155  * mapping.
 156  *
 157  * @param sm     NAT main.
 158  * @param b0     Vlib buffer.
 159  * @param in2out In2out NAT44 session key.
 160  * @param out2in Out2in NAT44 session key.
 161  * @param node   Vlib node.
 162  *
 163  * @returns SNAT session if successfully created otherwise 0.
 164  */
 165 static inline snat_session_t *
 166 create_session_for_static_mapping (snat_main_t * sm,
 167                                    vlib_buffer_t * b0,
 168                                    ip4_address_t i2o_addr,
 169                                    u16 i2o_port,
 170                                    u32 i2o_fib_index,
 171                                    ip4_address_t o2i_addr,
 172                                    u16 o2i_port,
 173                                    u32 o2i_fib_index,
 174                                    nat_protocol_t proto,
 175                                    vlib_node_runtime_t * node,
 176                                    u32 thread_index, f64 now)
 177 {
 178   snat_user_t *u;
 179   snat_session_t *s;
 180   clib_bihash_kv_8_8_t kv0;
 181   ip4_header_t *ip0;
 182   udp_header_t *udp0;
 183   nat44_is_idle_session_ctx_t ctx0;
 184
 185   if (PREDICT_FALSE (nat44_ei_maximum_sessions_exceeded (sm, thread_index)))
 186     {
 187       b0->error = node->errors[SNAT_OUT2IN_ERROR_MAX_SESSIONS_EXCEEDED];
 188       nat_elog_notice ("maximum sessions exceeded");
 189       return 0;
 190     }
 191
 192   ip0 = vlib_buffer_get_current (b0);
 193   udp0 = ip4_next_header (ip0);
 194
 195   u = nat_user_get_or_create (sm, &i2o_addr, i2o_fib_index, thread_index);
 196   if (!u)
 197     {
 198       b0->error = node->errors[SNAT_OUT2IN_ERROR_CANNOT_CREATE_USER];
 199       return 0;
 200     }
 201
 202   s = nat_session_alloc_or_recycle (sm, u, thread_index, now);
 203   if (!s)
 204     {
 205       nat44_delete_user_with_no_session (sm, u, thread_index);
 206       nat_elog_warn ("create NAT session failed");
 207       return 0;
 208     }
 209
 210   s->flags |= SNAT_SESSION_FLAG_STATIC_MAPPING;
 211   s->ext_host_addr.as_u32 = ip0->src_address.as_u32;
 212   s->ext_host_port = udp0->src_port;
 213   user_session_increment (sm, u, 1 /* static */ );
 214   s->in2out.addr = i2o_addr;
 215   s->in2out.port = i2o_port;
 216   s->in2out.fib_index = i2o_fib_index;
 217   s->out2in.addr = o2i_addr;
 218   s->out2in.port = o2i_port;
 219   s->out2in.fib_index = o2i_fib_index;
 220   s->nat_proto = proto;
 221
 222   /* Add to translation hashes */
 223   ctx0.now = now;
 224   ctx0.thread_index = thread_index;
 225   init_nat_i2o_kv (&kv0, s, thread_index,
 226                    s - sm->per_thread_data[thread_index].sessions);
 227   if (clib_bihash_add_or_overwrite_stale_8_8 (
 228         &sm->in2out, &kv0, nat44_i2o_is_idle_session_cb, &ctx0))
 229     nat_elog_notice ("in2out key add failed");
 230
 231   init_nat_o2i_kv (&kv0, s, thread_index,
 232                    s - sm->per_thread_data[thread_index].sessions);
 233   if (clib_bihash_add_or_overwrite_stale_8_8 (
 234         &sm->out2in, &kv0, nat44_o2i_is_idle_session_cb, &ctx0))
 235     nat_elog_notice ("out2in key add failed");
 236
 237   /* log NAT event */
 238   nat_ipfix_logging_nat44_ses_create (thread_index,
 239                                       s->in2out.addr.as_u32,
 240                                       s->out2in.addr.as_u32,
 241                                       s->nat_proto,
 242                                       s->in2out.port,
 243                                       s->out2in.port, s->in2out.fib_index);
 244
 245   nat_syslog_nat44_apmadd (s->user_index, s->in2out.fib_index,
 246                            &s->in2out.addr, s->in2out.port, &s->out2in.addr,
 247                            s->out2in.port, s->nat_proto);
 248
 249   nat_ha_sadd (&s->in2out.addr, s->in2out.port, &s->out2in.addr,
 250                s->out2in.port, &s->ext_host_addr, s->ext_host_port,
 251                &s->ext_host_nat_addr, s->ext_host_nat_port,
 252                s->nat_proto, s->in2out.fib_index, s->flags, thread_index, 0);
 253
 254   return s;
 255 }
 256
 257 #ifndef CLIB_MARCH_VARIANT
 258 static_always_inline snat_out2in_error_t
 259 icmp_get_key (vlib_buffer_t * b, ip4_header_t * ip0,
 260               ip4_address_t * addr, u16 * port, nat_protocol_t * nat_proto)
 261 {
 262   icmp46_header_t *icmp0;
 263   icmp_echo_header_t *echo0, *inner_echo0 = 0;
 264   ip4_header_t *inner_ip0;
 265   void *l4_header = 0;
 266   icmp46_header_t *inner_icmp0;
 267
 268   icmp0 = (icmp46_header_t *) ip4_next_header (ip0);
 269   echo0 = (icmp_echo_header_t *) (icmp0 + 1);
 270
 271   if (!icmp_type_is_error_message
 272       (vnet_buffer (b)->ip.reass.icmp_type_or_tcp_flags))
 273     {
 274       *nat_proto = NAT_PROTOCOL_ICMP;
 275       *addr = ip0->dst_address;
 276       *port = vnet_buffer (b)->ip.reass.l4_src_port;
 277     }
 278   else
 279     {
 280       inner_ip0 = (ip4_header_t *) (echo0 + 1);
 281       l4_header = ip4_next_header (inner_ip0);
 282       *nat_proto = ip_proto_to_nat_proto (inner_ip0->protocol);
 283       *addr = inner_ip0->src_address;
 284       switch (*nat_proto)
 285         {
 286         case NAT_PROTOCOL_ICMP:
 287           inner_icmp0 = (icmp46_header_t *) l4_header;
 288           inner_echo0 = (icmp_echo_header_t *) (inner_icmp0 + 1);
 289           *port = inner_echo0->identifier;
 290           break;
 291         case NAT_PROTOCOL_UDP:
 292         case NAT_PROTOCOL_TCP:
 293           *port = ((tcp_udp_header_t *) l4_header)->src_port;
 294           break;
 295         default:
 296           return SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL;
 297         }
 298     }
 299   return -1;                    /* success */
 300 }
 301
 302 /**
 303  * Get address and port values to be used for ICMP packet translation
 304  * and create session if needed
 305  *
 306  * @param[in,out] sm             NAT main
 307  * @param[in,out] node           NAT node runtime
 308  * @param[in] thread_index       thread index
 309  * @param[in,out] b0             buffer containing packet to be translated
 310  * @param[in,out] ip0            ip header
 311  * @param[out] p_proto           protocol used for matching
 312  * @param[out] p_value           address and port after NAT translation
 313  * @param[out] p_dont_translate  if packet should not be translated
 314  * @param d                      optional parameter
 315  * @param e                      optional parameter
 316  */
 317 u32
 318 icmp_match_out2in_slow (snat_main_t *sm, vlib_node_runtime_t *node,
 319                         u32 thread_index, vlib_buffer_t *b0, ip4_header_t *ip0,
 320                         ip4_address_t *addr, u16 *port, u32 *fib_index,
 321                         nat_protocol_t *proto, snat_session_t **p_s0,
 322                         u8 *dont_translate)
 323 {
 324   snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
 325   u32 sw_if_index0;
 326   snat_session_t *s0 = 0;
 327   clib_bihash_kv_8_8_t kv0, value0;
 328   u8 is_addr_only;
 329   u32 next0 = ~0;
 330   int err;
 331   u8 identity_nat;
 332   vlib_main_t *vm = vlib_get_main ();
 333   *dont_translate = 0;
 334
 335   sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
 336   *fib_index = ip4_fib_table_get_index_for_sw_if_index (sw_if_index0);
 337
 338   *proto = 0;
 339
 340   err = icmp_get_key (b0, ip0, addr, port, proto);
 341   if (err != -1)
 342     {
 343       b0->error = node->errors[SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL];
 344       next0 = SNAT_OUT2IN_NEXT_DROP;
 345       goto out;
 346     }
 347
 348   ip4_address_t mapping_addr;
 349   u16 mapping_port;
 350   u32 mapping_fib_index;
 351
 352   init_nat_k (&kv0, *addr, *port, *fib_index, *proto);
 353   if (clib_bihash_search_8_8 (&sm->out2in, &kv0, &value0))
 354     {
 355       /* Try to match static mapping by external address and port,
 356          destination address and port in packet */
 357       if (nat44_ei_static_mapping_match (
 358             *addr, *port, *fib_index, *proto, &mapping_addr, &mapping_port,
 359             &mapping_fib_index, 1, &is_addr_only, &identity_nat))
 360         {
 361           if (!sm->forwarding_enabled)
 362             {
 363               /* Don't NAT packet aimed at the intfc address */
 364               if (PREDICT_FALSE (is_interface_addr (sm, node, sw_if_index0,
 365                                                     ip0->dst_address.as_u32)))
 366                 {
 367                   *dont_translate = 1;
 368                   goto out;
 369                 }
 370               b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
 371               next0 = SNAT_OUT2IN_NEXT_DROP;
 372               goto out;
 373             }
 374           else
 375             {
 376               *dont_translate = 1;
 377               goto out;
 378             }
 379         }
 380
 381       if (PREDICT_FALSE
 382           (vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags !=
 383            ICMP4_echo_reply
 384            && (vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags !=
 385                ICMP4_echo_request || !is_addr_only)))
 386         {
 387           b0->error = node->errors[SNAT_OUT2IN_ERROR_BAD_ICMP_TYPE];
 388           next0 = SNAT_OUT2IN_NEXT_DROP;
 389           goto out;
 390         }
 391
 392       if (PREDICT_FALSE (identity_nat))
 393         {
 394           *dont_translate = 1;
 395           goto out;
 396         }
 397       /* Create session initiated by host from external network */
 398       s0 =
 399         create_session_for_static_mapping (sm, b0, mapping_addr, mapping_port,
 400                                            mapping_fib_index, *addr, *port,
 401                                            *fib_index, *proto, node,
 402                                            thread_index, vlib_time_now (vm));
 403
 404       if (!s0)
 405         {
 406           next0 = SNAT_OUT2IN_NEXT_DROP;
 407           goto out;
 408         }
 409     }
 410   else
 411     {
 412       if (PREDICT_FALSE
 413           (vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags !=
 414            ICMP4_echo_reply
 415            && vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags !=
 416            ICMP4_echo_request
 417            && !icmp_type_is_error_message (vnet_buffer (b0)->ip.
 418                                            reass.icmp_type_or_tcp_flags)))
 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 (tsm->sessions,
 426                               nat_value_get_session_index (&value0));
 427     }
 428
 429 out:
 430   if (s0)
 431     {
 432       *addr = s0->in2out.addr;
 433       *port = s0->in2out.port;
 434       *fib_index = s0->in2out.fib_index;
 435     }
 436   if (p_s0)
 437     *p_s0 = s0;
 438   return next0;
 439 }
 440 #endif
 441
 442 #ifndef CLIB_MARCH_VARIANT
 443 /**
 444  * Get address and port values to be used for ICMP packet translation
 445  *
 446  * @param[in] sm                 NAT main
 447  * @param[in,out] node           NAT node runtime
 448  * @param[in] thread_index       thread index
 449  * @param[in,out] b0             buffer containing packet to be translated
 450  * @param[in,out] ip0            ip header
 451  * @param[out] p_proto           protocol used for matching
 452  * @param[out] p_value           address and port after NAT translation
 453  * @param[out] p_dont_translate  if packet should not be translated
 454  * @param d                      optional parameter
 455  * @param e                      optional parameter
 456  */
 457 u32
 458 icmp_match_out2in_fast (snat_main_t *sm, vlib_node_runtime_t *node,
 459                         u32 thread_index, vlib_buffer_t *b0, ip4_header_t *ip0,
 460                         ip4_address_t *mapping_addr, u16 *mapping_port,
 461                         u32 *mapping_fib_index, nat_protocol_t *proto,
 462                         snat_session_t **p_s0, u8 *dont_translate)
 463 {
 464   u32 sw_if_index0;
 465   u32 rx_fib_index0;
 466   u8 is_addr_only;
 467   u32 next0 = ~0;
 468   int err;
 469   ip4_address_t addr;
 470   u16 port;
 471   *dont_translate = 0;
 472
 473   sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
 474   rx_fib_index0 = ip4_fib_table_get_index_for_sw_if_index (sw_if_index0);
 475
 476   err = icmp_get_key (b0, ip0, &addr, &port, proto);
 477   if (err != -1)
 478     {
 479       b0->error = node->errors[err];
 480       next0 = SNAT_OUT2IN_NEXT_DROP;
 481       goto out;
 482     }
 483   if (nat44_ei_static_mapping_match (addr, port, rx_fib_index0, *proto,
 484                                      mapping_addr, mapping_port,
 485                                      mapping_fib_index, 1, &is_addr_only, 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
 499       (vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags != ICMP4_echo_reply
 500        && (vnet_buffer (b0)->ip.reass.icmp_type_or_tcp_flags !=
 501            ICMP4_echo_request || !is_addr_only)
 502        && !icmp_type_is_error_message (vnet_buffer (b0)->ip.
 503                                        reass.icmp_type_or_tcp_flags)))
 504     {
 505       b0->error = node->errors[SNAT_OUT2IN_ERROR_BAD_ICMP_TYPE];
 506       next0 = SNAT_OUT2IN_NEXT_DROP;
 507       goto out;
 508     }
 509
 510 out:
 511   return next0;
 512 }
 513 #endif
 514
 515 u32 icmp_out2in (snat_main_t *sm, vlib_buffer_t *b0, ip4_header_t *ip0,
 516                  icmp46_header_t *icmp0, u32 sw_if_index0, u32 rx_fib_index0,
 517                  vlib_node_runtime_t *node, u32 next0, u32 thread_index,
 518                  snat_session_t **p_s0);
 519
 520 #ifndef CLIB_MARCH_VARIANT
 521 u32
 522 icmp_out2in (snat_main_t *sm, vlib_buffer_t *b0, ip4_header_t *ip0,
 523              icmp46_header_t *icmp0, u32 sw_if_index0, u32 rx_fib_index0,
 524              vlib_node_runtime_t *node, u32 next0, u32 thread_index,
 525              snat_session_t **p_s0)
 526 {
 527   icmp_echo_header_t *echo0, *inner_echo0 = 0;
 528   ip4_header_t *inner_ip0 = 0;
 529   void *l4_header = 0;
 530   icmp46_header_t *inner_icmp0;
 531   u8 dont_translate;
 532   u32 new_addr0, old_addr0;
 533   u16 old_id0, new_id0;
 534   ip_csum_t sum0;
 535   u16 checksum0;
 536   u32 next0_tmp;
 537   vlib_main_t *vm = vlib_get_main ();
 538   ip4_address_t addr;
 539   u16 port;
 540   u32 fib_index;
 541   nat_protocol_t proto;
 542
 543   echo0 = (icmp_echo_header_t *) (icmp0 + 1);
 544
 545   next0_tmp =
 546     sm->icmp_match_out2in_cb (sm, node, thread_index, b0, ip0, &addr, &port,
 547                               &fib_index, &proto, p_s0, &dont_translate);
 548   if (next0_tmp != ~0)
 549     next0 = next0_tmp;
 550   if (next0 == SNAT_OUT2IN_NEXT_DROP || dont_translate)
 551     goto out;
 552
 553   if (PREDICT_TRUE (!ip4_is_fragment (ip0)))
 554     {
 555       sum0 =
 556         ip_incremental_checksum_buffer (vm, b0,
 557                                         (u8 *) icmp0 -
 558                                         (u8 *) vlib_buffer_get_current (b0),
 559                                         ntohs (ip0->length) -
 560                                         ip4_header_bytes (ip0), 0);
 561       checksum0 = ~ip_csum_fold (sum0);
 562       if (checksum0 != 0 && checksum0 != 0xffff)
 563         {
 564           next0 = SNAT_OUT2IN_NEXT_DROP;
 565           goto out;
 566         }
 567     }
 568
 569   old_addr0 = ip0->dst_address.as_u32;
 570   new_addr0 = ip0->dst_address.as_u32 = addr.as_u32;
 571   vnet_buffer (b0)->sw_if_index[VLIB_TX] = fib_index;
 572
 573   sum0 = ip0->checksum;
 574   sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
 575                          dst_address /* changed member */ );
 576   ip0->checksum = ip_csum_fold (sum0);
 577
 578
 579   if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment)
 580     {
 581       if (icmp0->checksum == 0)
 582         icmp0->checksum = 0xffff;
 583
 584       if (!icmp_type_is_error_message (icmp0->type))
 585         {
 586           new_id0 = port;
 587           if (PREDICT_FALSE (new_id0 != echo0->identifier))
 588             {
 589               old_id0 = echo0->identifier;
 590               new_id0 = port;
 591               echo0->identifier = new_id0;
 592
 593               sum0 = icmp0->checksum;
 594               sum0 =
 595                 ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t,
 596                                 identifier /* changed member */ );
 597               icmp0->checksum = ip_csum_fold (sum0);
 598             }
 599         }
 600       else
 601         {
 602           inner_ip0 = (ip4_header_t *) (echo0 + 1);
 603           l4_header = ip4_next_header (inner_ip0);
 604
 605           if (!ip4_header_checksum_is_valid (inner_ip0))
 606             {
 607               next0 = SNAT_OUT2IN_NEXT_DROP;
 608               goto out;
 609             }
 610
 611           old_addr0 = inner_ip0->src_address.as_u32;
 612           inner_ip0->src_address = addr;
 613           new_addr0 = inner_ip0->src_address.as_u32;
 614
 615           sum0 = icmp0->checksum;
 616           sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t,
 617                                  src_address /* changed member */ );
 618           icmp0->checksum = ip_csum_fold (sum0);
 619
 620           switch (proto)
 621             {
 622             case NAT_PROTOCOL_ICMP:
 623               inner_icmp0 = (icmp46_header_t *) l4_header;
 624               inner_echo0 = (icmp_echo_header_t *) (inner_icmp0 + 1);
 625
 626               old_id0 = inner_echo0->identifier;
 627               new_id0 = port;
 628               inner_echo0->identifier = new_id0;
 629
 630               sum0 = icmp0->checksum;
 631               sum0 =
 632                 ip_csum_update (sum0, old_id0, new_id0, icmp_echo_header_t,
 633                                 identifier);
 634               icmp0->checksum = ip_csum_fold (sum0);
 635               break;
 636             case NAT_PROTOCOL_UDP:
 637             case NAT_PROTOCOL_TCP:
 638               old_id0 = ((tcp_udp_header_t *) l4_header)->src_port;
 639               new_id0 = port;
 640               ((tcp_udp_header_t *) l4_header)->src_port = new_id0;
 641
 642               sum0 = icmp0->checksum;
 643               sum0 = ip_csum_update (sum0, old_id0, new_id0, tcp_udp_header_t,
 644                                      src_port);
 645               icmp0->checksum = ip_csum_fold (sum0);
 646               break;
 647             default:
 648               ASSERT (0);
 649             }
 650         }
 651     }
 652
 653 out:
 654   return next0;
 655 }
 656 #endif
 657
 658 static inline u32
 659 icmp_out2in_slow_path (snat_main_t * sm,
 660                        vlib_buffer_t * b0,
 661                        ip4_header_t * ip0,
 662                        icmp46_header_t * icmp0,
 663                        u32 sw_if_index0,
 664                        u32 rx_fib_index0,
 665                        vlib_node_runtime_t * node,
 666                        u32 next0, f64 now,
 667                        u32 thread_index, snat_session_t ** p_s0)
 668 {
 669   vlib_main_t *vm = vlib_get_main ();
 670
 671   next0 = icmp_out2in (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
 672                        next0, thread_index, p_s0);
 673   snat_session_t *s0 = *p_s0;
 674   if (PREDICT_TRUE (next0 != SNAT_OUT2IN_NEXT_DROP && s0))
 675     {
 676       /* Accounting */
 677       nat44_ei_session_update_counters (
 678         s0, now, vlib_buffer_length_in_chain (vm, b0), thread_index);
 679       /* Per-user LRU list maintenance */
 680       nat44_session_update_lru (sm, s0, thread_index);
 681     }
 682   return next0;
 683 }
 684
 685 static int
 686 nat_out2in_sm_unknown_proto (snat_main_t * sm,
 687                              vlib_buffer_t * b,
 688                              ip4_header_t * ip, u32 rx_fib_index)
 689 {
 690   clib_bihash_kv_8_8_t kv, value;
 691   snat_static_mapping_t *m;
 692   u32 old_addr, new_addr;
 693   ip_csum_t sum;
 694
 695   init_nat_k (&kv, ip->dst_address, 0, 0, 0);
 696   if (clib_bihash_search_8_8 (&sm->static_mapping_by_external, &kv, &value))
 697     return 1;
 698
 699   m = pool_elt_at_index (sm->static_mappings, value.value);
 700
 701   old_addr = ip->dst_address.as_u32;
 702   new_addr = ip->dst_address.as_u32 = m->local_addr.as_u32;
 703   sum = ip->checksum;
 704   sum = ip_csum_update (sum, old_addr, new_addr, ip4_header_t, dst_address);
 705   ip->checksum = ip_csum_fold (sum);
 706
 707   vnet_buffer (b)->sw_if_index[VLIB_TX] = m->fib_index;
 708   return 0;
 709 }
 710
 711 VLIB_NODE_FN (snat_out2in_node) (vlib_main_t * vm,
 712                                  vlib_node_runtime_t * node,
 713                                  vlib_frame_t * frame)
 714 {
 715   u32 n_left_from, *from;
 716   snat_main_t *sm = &snat_main;
 717   f64 now = vlib_time_now (vm);
 718   u32 thread_index = vm->thread_index;
 719   snat_main_per_thread_data_t *tsm = &sm->per_thread_data[thread_index];
 720
 721   from = vlib_frame_vector_args (frame);
 722   n_left_from = frame->n_vectors;
 723
 724   vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs;
 725   u16 nexts[VLIB_FRAME_SIZE], *next = nexts;
 726   vlib_get_buffers (vm, from, b, n_left_from);
 727
 728   while (n_left_from >= 2)
 729     {
 730       vlib_buffer_t *b0, *b1;
 731       u32 next0 = SNAT_OUT2IN_NEXT_LOOKUP;
 732       u32 next1 = SNAT_OUT2IN_NEXT_LOOKUP;
 733       u32 sw_if_index0, sw_if_index1;
 734       ip4_header_t *ip0, *ip1;
 735       ip_csum_t sum0, sum1;
 736       u32 new_addr0, old_addr0;
 737       u16 new_port0, old_port0;
 738       u32 new_addr1, old_addr1;
 739       u16 new_port1, old_port1;
 740       udp_header_t *udp0, *udp1;
 741       tcp_header_t *tcp0, *tcp1;
 742       icmp46_header_t *icmp0, *icmp1;
 743       u32 rx_fib_index0, rx_fib_index1;
 744       u32 proto0, proto1;
 745       snat_session_t *s0 = 0, *s1 = 0;
 746       clib_bihash_kv_8_8_t kv0, kv1, value0, value1;
 747       u8 identity_nat0, identity_nat1;
 748       ip4_address_t sm_addr0, sm_addr1;
 749       u16 sm_port0, sm_port1;
 750       u32 sm_fib_index0, sm_fib_index1;
 751
 752       b0 = *b;
 753       b++;
 754       b1 = *b;
 755       b++;
 756
 757       /* Prefetch next iteration. */
 758       if (PREDICT_TRUE (n_left_from >= 4))
 759         {
 760           vlib_buffer_t *p2, *p3;
 761
 762           p2 = *b;
 763           p3 = *(b + 1);
 764
 765           vlib_prefetch_buffer_header (p2, LOAD);
 766           vlib_prefetch_buffer_header (p3, LOAD);
 767
 768           CLIB_PREFETCH (p2->data, CLIB_CACHE_LINE_BYTES, LOAD);
 769           CLIB_PREFETCH (p3->data, CLIB_CACHE_LINE_BYTES, LOAD);
 770         }
 771
 772       vnet_buffer (b0)->snat.flags = 0;
 773       vnet_buffer (b1)->snat.flags = 0;
 774
 775       ip0 = vlib_buffer_get_current (b0);
 776       udp0 = ip4_next_header (ip0);
 777       tcp0 = (tcp_header_t *) udp0;
 778       icmp0 = (icmp46_header_t *) udp0;
 779
 780       sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
 781       rx_fib_index0 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index,
 782                                sw_if_index0);
 783
 784       if (PREDICT_FALSE (ip0->ttl == 1))
 785         {
 786           vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
 787           icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
 788                                        ICMP4_time_exceeded_ttl_exceeded_in_transit,
 789                                        0);
 790           next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
 791           goto trace0;
 792         }
 793
 794       proto0 = ip_proto_to_nat_proto (ip0->protocol);
 795
 796       if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_OTHER))
 797         {
 798           if (nat_out2in_sm_unknown_proto (sm, b0, ip0, rx_fib_index0))
 799             {
 800               if (!sm->forwarding_enabled)
 801                 {
 802                   b0->error =
 803                     node->errors[SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL];
 804                   next0 = SNAT_OUT2IN_NEXT_DROP;
 805                 }
 806             }
 807           vlib_increment_simple_counter (&sm->counters.slowpath.out2in.other,
 808                                          thread_index, sw_if_index0, 1);
 809
 810           goto trace0;
 811         }
 812
 813       if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_ICMP))
 814         {
 815           next0 = icmp_out2in_slow_path
 816             (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
 817              next0, now, thread_index, &s0);
 818           vlib_increment_simple_counter (&sm->counters.slowpath.out2in.icmp,
 819                                          thread_index, sw_if_index0, 1);
 820           goto trace0;
 821         }
 822
 823       init_nat_k (&kv0, ip0->dst_address,
 824                   vnet_buffer (b0)->ip.reass.l4_dst_port, rx_fib_index0,
 825                   proto0);
 826       if (clib_bihash_search_8_8 (&sm->out2in, &kv0, &value0))
 827         {
 828           /* Try to match static mapping by external address and port,
 829              destination address and port in packet */
 830           if (nat44_ei_static_mapping_match (
 831                 ip0->dst_address, vnet_buffer (b0)->ip.reass.l4_dst_port,
 832                 rx_fib_index0, proto0, &sm_addr0, &sm_port0, &sm_fib_index0, 1,
 833                 0, &identity_nat0))
 834             {
 835               /*
 836                * Send DHCP packets to the ipv4 stack, or we won't
 837                * be able to use dhcp client on the outside interface
 838                */
 839               if (PREDICT_FALSE
 840                   (proto0 == NAT_PROTOCOL_UDP
 841                    && (vnet_buffer (b0)->ip.reass.l4_dst_port ==
 842                        clib_host_to_net_u16 (UDP_DST_PORT_dhcp_to_client))))
 843                 {
 844                   vnet_feature_next (&next0, b0);
 845                   goto trace0;
 846                 }
 847
 848               if (!sm->forwarding_enabled)
 849                 {
 850                   b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
 851                   next0 = SNAT_OUT2IN_NEXT_DROP;
 852                 }
 853               goto trace0;
 854             }
 855
 856           if (PREDICT_FALSE (identity_nat0))
 857             goto trace0;
 858
 859           /* Create session initiated by host from external network */
 860           s0 = create_session_for_static_mapping (sm, b0,
 861                                                   sm_addr0, sm_port0,
 862                                                   sm_fib_index0,
 863                                                   ip0->dst_address,
 864                                                   vnet_buffer (b0)->ip.
 865                                                   reass.l4_dst_port,
 866                                                   rx_fib_index0, proto0, node,
 867                                                   thread_index, now);
 868           if (!s0)
 869             {
 870               next0 = SNAT_OUT2IN_NEXT_DROP;
 871               goto trace0;
 872             }
 873         }
 874       else
 875         s0 = pool_elt_at_index (tsm->sessions,
 876                                 nat_value_get_session_index (&value0));
 877
 878       old_addr0 = ip0->dst_address.as_u32;
 879       ip0->dst_address = s0->in2out.addr;
 880       new_addr0 = ip0->dst_address.as_u32;
 881       vnet_buffer (b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
 882
 883       sum0 = ip0->checksum;
 884       sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
 885                              ip4_header_t, dst_address /* changed member */ );
 886       ip0->checksum = ip_csum_fold (sum0);
 887
 888       if (PREDICT_TRUE (proto0 == NAT_PROTOCOL_TCP))
 889         {
 890           if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment)
 891             {
 892               old_port0 = vnet_buffer (b0)->ip.reass.l4_dst_port;
 893               new_port0 = udp0->dst_port = s0->in2out.port;
 894               sum0 = tcp0->checksum;
 895               sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
 896                                      ip4_header_t,
 897                                      dst_address /* changed member */ );
 898
 899               sum0 = ip_csum_update (sum0, old_port0, new_port0,
 900                                      ip4_header_t /* cheat */ ,
 901                                      length /* changed member */ );
 902               tcp0->checksum = ip_csum_fold (sum0);
 903             }
 904           vlib_increment_simple_counter (&sm->counters.slowpath.out2in.tcp,
 905                                          thread_index, sw_if_index0, 1);
 906         }
 907       else
 908         {
 909           if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment)
 910             {
 911               old_port0 = vnet_buffer (b0)->ip.reass.l4_dst_port;
 912               new_port0 = udp0->dst_port = s0->in2out.port;
 913               if (PREDICT_FALSE (udp0->checksum))
 914                 {
 915                   sum0 = udp0->checksum;
 916                   sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t, dst_address  /* changed member */
 917                     );
 918                   sum0 =
 919                     ip_csum_update (sum0, old_port0, new_port0,
 920                                     ip4_header_t /* cheat */ ,
 921                                     length /* changed member */ );
 922                   udp0->checksum = ip_csum_fold (sum0);
 923                 }
 924             }
 925           vlib_increment_simple_counter (&sm->counters.slowpath.out2in.udp,
 926                                          thread_index, sw_if_index0, 1);
 927         }
 928
 929       /* Accounting */
 930       nat44_ei_session_update_counters (
 931         s0, now, vlib_buffer_length_in_chain (vm, b0), 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 = vlib_add_trace (vm, node, b0, sizeof (*t));
 940           t->sw_if_index = sw_if_index0;
 941           t->next_index = next0;
 942           t->session_index = ~0;
 943           if (s0)
 944             t->session_index =
 945               s0 - sm->per_thread_data[thread_index].sessions;
 946         }
 947
 948       if (next0 == SNAT_OUT2IN_NEXT_DROP)
 949         {
 950           vlib_increment_simple_counter (&sm->counters.slowpath.out2in.drops,
 951                                          thread_index, sw_if_index0, 1);
 952         }
 953
 954
 955       ip1 = vlib_buffer_get_current (b1);
 956       udp1 = ip4_next_header (ip1);
 957       tcp1 = (tcp_header_t *) udp1;
 958       icmp1 = (icmp46_header_t *) udp1;
 959
 960       sw_if_index1 = vnet_buffer (b1)->sw_if_index[VLIB_RX];
 961       rx_fib_index1 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index,
 962                                sw_if_index1);
 963
 964       if (PREDICT_FALSE (ip1->ttl == 1))
 965         {
 966           vnet_buffer (b1)->sw_if_index[VLIB_TX] = (u32) ~ 0;
 967           icmp4_error_set_vnet_buffer (b1, ICMP4_time_exceeded,
 968                                        ICMP4_time_exceeded_ttl_exceeded_in_transit,
 969                                        0);
 970           next1 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
 971           goto trace1;
 972         }
 973
 974       proto1 = ip_proto_to_nat_proto (ip1->protocol);
 975
 976       if (PREDICT_FALSE (proto1 == NAT_PROTOCOL_OTHER))
 977         {
 978           if (nat_out2in_sm_unknown_proto (sm, b1, ip1, rx_fib_index1))
 979             {
 980               if (!sm->forwarding_enabled)
 981                 {
 982                   b1->error =
 983                     node->errors[SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL];
 984                   next1 = SNAT_OUT2IN_NEXT_DROP;
 985                 }
 986             }
 987           vlib_increment_simple_counter (&sm->counters.slowpath.out2in.other,
 988                                          thread_index, sw_if_index1, 1);
 989           goto trace1;
 990         }
 991
 992       if (PREDICT_FALSE (proto1 == NAT_PROTOCOL_ICMP))
 993         {
 994           next1 = icmp_out2in_slow_path
 995             (sm, b1, ip1, icmp1, sw_if_index1, rx_fib_index1, node,
 996              next1, now, thread_index, &s1);
 997           vlib_increment_simple_counter (&sm->counters.slowpath.out2in.icmp,
 998                                          thread_index, sw_if_index1, 1);
 999           goto trace1;
1000         }
1001
1002       init_nat_k (&kv1, ip1->dst_address,
1003                   vnet_buffer (b1)->ip.reass.l4_dst_port, rx_fib_index1,
1004                   proto1);
1005       if (clib_bihash_search_8_8 (&sm->out2in, &kv1, &value1))
1006         {
1007           /* Try to match static mapping by external address and port,
1008              destination address and port in packet */
1009           if (nat44_ei_static_mapping_match (
1010                 ip1->dst_address, vnet_buffer (b1)->ip.reass.l4_dst_port,
1011                 rx_fib_index1, proto1, &sm_addr1, &sm_port1, &sm_fib_index1, 1,
1012                 0, &identity_nat1))
1013             {
1014               /*
1015                * Send DHCP packets to the ipv4 stack, or we won't
1016                * be able to use dhcp client on the outside interface
1017                */
1018               if (PREDICT_FALSE
1019                   (proto1 == NAT_PROTOCOL_UDP
1020                    && (vnet_buffer (b1)->ip.reass.l4_dst_port ==
1021                        clib_host_to_net_u16 (UDP_DST_PORT_dhcp_to_client))))
1022                 {
1023                   vnet_feature_next (&next1, b1);
1024                   goto trace1;
1025                 }
1026
1027               if (!sm->forwarding_enabled)
1028                 {
1029                   b1->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
1030                   next1 = SNAT_OUT2IN_NEXT_DROP;
1031                 }
1032               goto trace1;
1033             }
1034
1035           if (PREDICT_FALSE (identity_nat1))
1036             goto trace1;
1037
1038           /* Create session initiated by host from external network */
1039           s1 =
1040             create_session_for_static_mapping (sm, b1, sm_addr1, sm_port1,
1041                                                sm_fib_index1,
1042                                                ip1->dst_address,
1043                                                vnet_buffer (b1)->ip.
1044                                                reass.l4_dst_port,
1045                                                rx_fib_index1, proto1, node,
1046                                                thread_index, now);
1047           if (!s1)
1048             {
1049               next1 = SNAT_OUT2IN_NEXT_DROP;
1050               goto trace1;
1051             }
1052         }
1053       else
1054         s1 = pool_elt_at_index (sm->per_thread_data[thread_index].sessions,
1055                                 nat_value_get_session_index (&value1));
1056
1057       old_addr1 = ip1->dst_address.as_u32;
1058       ip1->dst_address = s1->in2out.addr;
1059       new_addr1 = ip1->dst_address.as_u32;
1060       vnet_buffer (b1)->sw_if_index[VLIB_TX] = s1->in2out.fib_index;
1061
1062       sum1 = ip1->checksum;
1063       sum1 = ip_csum_update (sum1, old_addr1, new_addr1,
1064                              ip4_header_t, dst_address /* changed member */ );
1065       ip1->checksum = ip_csum_fold (sum1);
1066
1067       if (PREDICT_TRUE (proto1 == NAT_PROTOCOL_TCP))
1068         {
1069           if (!vnet_buffer (b1)->ip.reass.is_non_first_fragment)
1070             {
1071               old_port1 = vnet_buffer (b1)->ip.reass.l4_dst_port;
1072               new_port1 = udp1->dst_port = s1->in2out.port;
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             }
1084           vlib_increment_simple_counter (&sm->counters.slowpath.out2in.tcp,
1085                                          thread_index, sw_if_index1, 1);
1086         }
1087       else
1088         {
1089           if (!vnet_buffer (b1)->ip.reass.is_non_first_fragment)
1090             {
1091               old_port1 = vnet_buffer (b1)->ip.reass.l4_dst_port;
1092               new_port1 = udp1->dst_port = s1->in2out.port;
1093               if (PREDICT_FALSE (udp1->checksum))
1094                 {
1095
1096                   sum1 = udp1->checksum;
1097                   sum1 =
1098                     ip_csum_update (sum1, old_addr1, new_addr1,
1099                                     ip4_header_t,
1100                                     dst_address /* changed member */ );
1101                   sum1 =
1102                     ip_csum_update (sum1, old_port1, new_port1,
1103                                     ip4_header_t /* cheat */ ,
1104                                     length /* changed member */ );
1105                   udp1->checksum = ip_csum_fold (sum1);
1106                 }
1107             }
1108           vlib_increment_simple_counter (&sm->counters.slowpath.out2in.udp,
1109                                          thread_index, sw_if_index1, 1);
1110         }
1111
1112       /* Accounting */
1113       nat44_ei_session_update_counters (
1114         s1, now, vlib_buffer_length_in_chain (vm, b1), thread_index);
1115       /* Per-user LRU list maintenance */
1116       nat44_session_update_lru (sm, s1, thread_index);
1117     trace1:
1118
1119       if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
1120                          && (b1->flags & VLIB_BUFFER_IS_TRACED)))
1121         {
1122           snat_out2in_trace_t *t = vlib_add_trace (vm, node, b1, sizeof (*t));
1123           t->sw_if_index = sw_if_index1;
1124           t->next_index = next1;
1125           t->session_index = ~0;
1126           if (s1)
1127             t->session_index =
1128               s1 - sm->per_thread_data[thread_index].sessions;
1129         }
1130
1131       if (next1 == SNAT_OUT2IN_NEXT_DROP)
1132         {
1133           vlib_increment_simple_counter (&sm->counters.slowpath.out2in.drops,
1134                                          thread_index, sw_if_index1, 1);
1135         }
1136
1137       n_left_from -= 2;
1138       next[0] = next0;
1139       next[1] = next1;
1140       next += 2;
1141     }
1142
1143   while (n_left_from > 0)
1144     {
1145       vlib_buffer_t *b0;
1146       u32 next0 = SNAT_OUT2IN_NEXT_LOOKUP;
1147       u32 sw_if_index0;
1148       ip4_header_t *ip0;
1149       ip_csum_t sum0;
1150       u32 new_addr0, old_addr0;
1151       u16 new_port0, old_port0;
1152       udp_header_t *udp0;
1153       tcp_header_t *tcp0;
1154       icmp46_header_t *icmp0;
1155       u32 rx_fib_index0;
1156       u32 proto0;
1157       snat_session_t *s0 = 0;
1158       clib_bihash_kv_8_8_t kv0, value0;
1159       u8 identity_nat0;
1160       ip4_address_t sm_addr0;
1161       u16 sm_port0;
1162       u32 sm_fib_index0;
1163
1164       b0 = *b;
1165       ++b;
1166
1167       vnet_buffer (b0)->snat.flags = 0;
1168
1169       ip0 = vlib_buffer_get_current (b0);
1170       udp0 = ip4_next_header (ip0);
1171       tcp0 = (tcp_header_t *) udp0;
1172       icmp0 = (icmp46_header_t *) udp0;
1173
1174       sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
1175       rx_fib_index0 = vec_elt (sm->ip4_main->fib_index_by_sw_if_index,
1176                                sw_if_index0);
1177
1178       proto0 = ip_proto_to_nat_proto (ip0->protocol);
1179
1180       if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_OTHER))
1181         {
1182           if (nat_out2in_sm_unknown_proto (sm, b0, ip0, rx_fib_index0))
1183             {
1184               if (!sm->forwarding_enabled)
1185                 {
1186                   b0->error =
1187                     node->errors[SNAT_OUT2IN_ERROR_UNSUPPORTED_PROTOCOL];
1188                   next0 = SNAT_OUT2IN_NEXT_DROP;
1189                 }
1190             }
1191           vlib_increment_simple_counter (&sm->counters.slowpath.out2in.other,
1192                                          thread_index, sw_if_index0, 1);
1193           goto trace00;
1194         }
1195
1196       if (PREDICT_FALSE (ip0->ttl == 1))
1197         {
1198           vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
1199           icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
1200                                        ICMP4_time_exceeded_ttl_exceeded_in_transit,
1201                                        0);
1202           next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
1203           goto trace00;
1204         }
1205
1206       if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_ICMP))
1207         {
1208           next0 = icmp_out2in_slow_path
1209             (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0, node,
1210              next0, now, thread_index, &s0);
1211           vlib_increment_simple_counter (&sm->counters.slowpath.out2in.icmp,
1212                                          thread_index, sw_if_index0, 1);
1213           goto trace00;
1214         }
1215
1216       init_nat_k (&kv0, ip0->dst_address,
1217                   vnet_buffer (b0)->ip.reass.l4_dst_port, rx_fib_index0,
1218                   proto0);
1219
1220       if (clib_bihash_search_8_8 (&sm->out2in, &kv0, &value0))
1221         {
1222           /* Try to match static mapping by external address and port,
1223              destination address and port in packet */
1224           if (nat44_ei_static_mapping_match (
1225                 ip0->dst_address, vnet_buffer (b0)->ip.reass.l4_dst_port,
1226                 rx_fib_index0, proto0, &sm_addr0, &sm_port0, &sm_fib_index0, 1,
1227                 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
1234                   (proto0 == NAT_PROTOCOL_UDP
1235                    && (vnet_buffer (b0)->ip.reass.l4_dst_port ==
1236                        clib_host_to_net_u16 (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 = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
1245                   next0 = SNAT_OUT2IN_NEXT_DROP;
1246                 }
1247               goto trace00;
1248             }
1249
1250           if (PREDICT_FALSE (identity_nat0))
1251             goto trace00;
1252
1253           /* Create session initiated by host from external network */
1254           s0 = create_session_for_static_mapping (sm, b0,
1255                                                   sm_addr0, sm_port0,
1256                                                   sm_fib_index0,
1257                                                   ip0->dst_address,
1258                                                   vnet_buffer (b0)->ip.
1259                                                   reass.l4_dst_port,
1260                                                   rx_fib_index0, proto0, node,
1261                                                   thread_index, now);
1262           if (!s0)
1263             {
1264               next0 = SNAT_OUT2IN_NEXT_DROP;
1265               goto trace00;
1266             }
1267         }
1268       else
1269         s0 = pool_elt_at_index (sm->per_thread_data[thread_index].sessions,
1270                                 nat_value_get_session_index (&value0));
1271
1272       old_addr0 = ip0->dst_address.as_u32;
1273       ip0->dst_address = s0->in2out.addr;
1274       new_addr0 = ip0->dst_address.as_u32;
1275       vnet_buffer (b0)->sw_if_index[VLIB_TX] = s0->in2out.fib_index;
1276
1277       sum0 = ip0->checksum;
1278       sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1279                              ip4_header_t, dst_address /* changed member */ );
1280       ip0->checksum = ip_csum_fold (sum0);
1281
1282       if (PREDICT_TRUE (proto0 == NAT_PROTOCOL_TCP))
1283         {
1284           if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment)
1285             {
1286               old_port0 = vnet_buffer (b0)->ip.reass.l4_dst_port;
1287               new_port0 = udp0->dst_port = s0->in2out.port;
1288
1289               sum0 = tcp0->checksum;
1290               sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1291                                      ip4_header_t,
1292                                      dst_address /* changed member */ );
1293
1294               sum0 = ip_csum_update (sum0, old_port0, new_port0,
1295                                      ip4_header_t /* cheat */ ,
1296                                      length /* changed member */ );
1297               tcp0->checksum = ip_csum_fold (sum0);
1298             }
1299           vlib_increment_simple_counter (&sm->counters.slowpath.out2in.tcp,
1300                                          thread_index, sw_if_index0, 1);
1301         }
1302       else
1303         {
1304           if (!vnet_buffer (b0)->ip.reass.is_non_first_fragment)
1305             {
1306               old_port0 = vnet_buffer (b0)->ip.reass.l4_dst_port;
1307               new_port0 = udp0->dst_port = s0->in2out.port;
1308               if (PREDICT_FALSE (udp0->checksum))
1309                 {
1310                   sum0 = udp0->checksum;
1311                   sum0 = ip_csum_update (sum0, old_addr0, new_addr0, ip4_header_t, dst_address  /* changed member */
1312                     );
1313                   sum0 =
1314                     ip_csum_update (sum0, old_port0, new_port0,
1315                                     ip4_header_t /* cheat */ ,
1316                                     length /* changed member */ );
1317                   udp0->checksum = ip_csum_fold (sum0);
1318                 }
1319             }
1320           vlib_increment_simple_counter (&sm->counters.slowpath.out2in.udp,
1321                                          thread_index, sw_if_index0, 1);
1322         }
1323
1324       /* Accounting */
1325       nat44_ei_session_update_counters (
1326         s0, now, vlib_buffer_length_in_chain (vm, b0), thread_index);
1327       /* Per-user LRU list maintenance */
1328       nat44_session_update_lru (sm, s0, thread_index);
1329     trace00:
1330
1331       if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
1332                          && (b0->flags & VLIB_BUFFER_IS_TRACED)))
1333         {
1334           snat_out2in_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
1335           t->sw_if_index = sw_if_index0;
1336           t->next_index = next0;
1337           t->session_index = ~0;
1338           if (s0)
1339             t->session_index =
1340               s0 - sm->per_thread_data[thread_index].sessions;
1341         }
1342
1343       if (next0 == SNAT_OUT2IN_NEXT_DROP)
1344         {
1345           vlib_increment_simple_counter (&sm->counters.slowpath.out2in.drops,
1346                                          thread_index, sw_if_index0, 1);
1347         }
1348
1349       n_left_from--;
1350       next[0] = next0;
1351       next++;
1352     }
1353
1354   vlib_buffer_enqueue_to_next (vm, node, from, (u16 *) nexts,
1355                                frame->n_vectors);
1356
1357   return frame->n_vectors;
1358 }
1359
1360 /* *INDENT-OFF* */
1361 VLIB_REGISTER_NODE (snat_out2in_node) = {
1362   .name = "nat44-out2in",
1363   .vector_size = sizeof (u32),
1364   .format_trace = format_snat_out2in_trace,
1365   .type = VLIB_NODE_TYPE_INTERNAL,
1366
1367   .n_errors = ARRAY_LEN(snat_out2in_error_strings),
1368   .error_strings = snat_out2in_error_strings,
1369
1370   .runtime_data_bytes = sizeof (snat_runtime_t),
1371
1372   .n_next_nodes = SNAT_OUT2IN_N_NEXT,
1373
1374   /* edit / add dispositions here */
1375   .next_nodes = {
1376     [SNAT_OUT2IN_NEXT_DROP] = "error-drop",
1377     [SNAT_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
1378     [SNAT_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
1379   },
1380 };
1381 /* *INDENT-ON* */
1382
1383 VLIB_NODE_FN (snat_out2in_fast_node) (vlib_main_t * vm,
1384                                       vlib_node_runtime_t * node,
1385                                       vlib_frame_t * frame)
1386 {
1387   u32 n_left_from, *from;
1388   snat_main_t *sm = &snat_main;
1389
1390   from = vlib_frame_vector_args (frame);
1391   n_left_from = frame->n_vectors;
1392
1393   vlib_buffer_t *bufs[VLIB_FRAME_SIZE], **b = bufs;
1394   u16 nexts[VLIB_FRAME_SIZE], *next = nexts;
1395   vlib_get_buffers (vm, from, b, n_left_from);
1396   while (n_left_from > 0)
1397     {
1398       vlib_buffer_t *b0;
1399       u32 next0 = SNAT_OUT2IN_NEXT_DROP;
1400       u32 sw_if_index0;
1401       ip4_header_t *ip0;
1402       ip_csum_t sum0;
1403       u32 new_addr0, old_addr0;
1404       u16 new_port0, old_port0;
1405       udp_header_t *udp0;
1406       tcp_header_t *tcp0;
1407       icmp46_header_t *icmp0;
1408       u32 proto0;
1409       u32 rx_fib_index0;
1410       ip4_address_t sm_addr0;
1411       u16 sm_port0;
1412       u32 sm_fib_index0;
1413
1414       b0 = *b;
1415       b++;
1416
1417       ip0 = vlib_buffer_get_current (b0);
1418       udp0 = ip4_next_header (ip0);
1419       tcp0 = (tcp_header_t *) udp0;
1420       icmp0 = (icmp46_header_t *) udp0;
1421
1422       sw_if_index0 = vnet_buffer (b0)->sw_if_index[VLIB_RX];
1423       rx_fib_index0 = ip4_fib_table_get_index_for_sw_if_index (sw_if_index0);
1424
1425       vnet_feature_next (&next0, b0);
1426
1427       if (PREDICT_FALSE (ip0->ttl == 1))
1428         {
1429           vnet_buffer (b0)->sw_if_index[VLIB_TX] = (u32) ~ 0;
1430           icmp4_error_set_vnet_buffer (b0, ICMP4_time_exceeded,
1431                                        ICMP4_time_exceeded_ttl_exceeded_in_transit,
1432                                        0);
1433           next0 = SNAT_OUT2IN_NEXT_ICMP_ERROR;
1434           goto trace00;
1435         }
1436
1437       proto0 = ip_proto_to_nat_proto (ip0->protocol);
1438
1439       if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_OTHER))
1440         goto trace00;
1441
1442       if (PREDICT_FALSE (proto0 == NAT_PROTOCOL_ICMP))
1443         {
1444           next0 = icmp_out2in (sm, b0, ip0, icmp0, sw_if_index0, rx_fib_index0,
1445                                node, next0, ~0, 0);
1446           goto trace00;
1447         }
1448
1449       if (nat44_ei_static_mapping_match (ip0->dst_address, udp0->dst_port,
1450                                          rx_fib_index0, proto0, &sm_addr0,
1451                                          &sm_port0, &sm_fib_index0, 1, 0, 0))
1452         {
1453           b0->error = node->errors[SNAT_OUT2IN_ERROR_NO_TRANSLATION];
1454           goto trace00;
1455         }
1456
1457       new_addr0 = sm_addr0.as_u32;
1458       new_port0 = sm_port0;
1459       vnet_buffer (b0)->sw_if_index[VLIB_TX] = sm_fib_index0;
1460       old_addr0 = ip0->dst_address.as_u32;
1461       ip0->dst_address.as_u32 = new_addr0;
1462
1463       sum0 = ip0->checksum;
1464       sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1465                              ip4_header_t, dst_address /* changed member */ );
1466       ip0->checksum = ip_csum_fold (sum0);
1467
1468       if (PREDICT_FALSE (new_port0 != udp0->dst_port))
1469         {
1470           old_port0 = udp0->dst_port;
1471           udp0->dst_port = new_port0;
1472
1473           if (PREDICT_TRUE (proto0 == NAT_PROTOCOL_TCP))
1474             {
1475               sum0 = tcp0->checksum;
1476               sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1477                                      ip4_header_t,
1478                                      dst_address /* changed member */ );
1479               sum0 = ip_csum_update (sum0, old_port0, new_port0,
1480                                      ip4_header_t /* cheat */ ,
1481                                      length /* changed member */ );
1482               tcp0->checksum = ip_csum_fold (sum0);
1483             }
1484           else if (udp0->checksum)
1485             {
1486               sum0 = udp0->checksum;
1487               sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1488                                      ip4_header_t,
1489                                      dst_address /* changed member */ );
1490               sum0 = ip_csum_update (sum0, old_port0, new_port0,
1491                                      ip4_header_t /* cheat */ ,
1492                                      length /* changed member */ );
1493               udp0->checksum = ip_csum_fold (sum0);
1494             }
1495         }
1496       else
1497         {
1498           if (PREDICT_TRUE (proto0 == NAT_PROTOCOL_TCP))
1499             {
1500               sum0 = tcp0->checksum;
1501               sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1502                                      ip4_header_t,
1503                                      dst_address /* changed member */ );
1504               tcp0->checksum = ip_csum_fold (sum0);
1505             }
1506           else if (udp0->checksum)
1507             {
1508               sum0 = udp0->checksum;
1509               sum0 = ip_csum_update (sum0, old_addr0, new_addr0,
1510                                      ip4_header_t,
1511                                      dst_address /* changed member */ );
1512               udp0->checksum = ip_csum_fold (sum0);
1513             }
1514         }
1515
1516     trace00:
1517
1518       if (PREDICT_FALSE ((node->flags & VLIB_NODE_FLAG_TRACE)
1519                          && (b0->flags & VLIB_BUFFER_IS_TRACED)))
1520         {
1521           snat_out2in_trace_t *t = vlib_add_trace (vm, node, b0, sizeof (*t));
1522           t->sw_if_index = sw_if_index0;
1523           t->next_index = next0;
1524         }
1525
1526       if (next0 == SNAT_OUT2IN_NEXT_DROP)
1527         {
1528           vlib_increment_simple_counter (&sm->counters.fastpath.out2in.drops,
1529                                          vm->thread_index, sw_if_index0, 1);
1530         }
1531
1532       n_left_from--;
1533       next[0] = next0;
1534       next++;
1535     }
1536
1537   vlib_buffer_enqueue_to_next (vm, node, from, (u16 *) nexts,
1538                                frame->n_vectors);
1539
1540   return frame->n_vectors;
1541 }
1542
1543 /* *INDENT-OFF* */
1544 VLIB_REGISTER_NODE (snat_out2in_fast_node) = {
1545   .name = "nat44-out2in-fast",
1546   .vector_size = sizeof (u32),
1547   .format_trace = format_snat_out2in_fast_trace,
1548   .type = VLIB_NODE_TYPE_INTERNAL,
1549
1550   .n_errors = ARRAY_LEN(snat_out2in_error_strings),
1551   .error_strings = snat_out2in_error_strings,
1552
1553   .runtime_data_bytes = sizeof (snat_runtime_t),
1554
1555   .n_next_nodes = SNAT_OUT2IN_N_NEXT,
1556
1557   /* edit / add dispositions here */
1558   .next_nodes = {
1559     [SNAT_OUT2IN_NEXT_LOOKUP] = "ip4-lookup",
1560     [SNAT_OUT2IN_NEXT_DROP] = "error-drop",
1561     [SNAT_OUT2IN_NEXT_ICMP_ERROR] = "ip4-icmp-error",
1562   },
1563 };
1564 /* *INDENT-ON* */
1565
1566 /*
1567  * fd.io coding-style-patch-verification: ON
1568  *
1569  * Local Variables:
1570  * eval: (c-set-style "gnu")
1571  * End:
1572  */