sys/netgraph7/ng_nat.c

   1 /*-
   2  * Copyright 2005, Gleb Smirnoff <glebius@FreeBSD.org>
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  *
  14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  24  * SUCH DAMAGE.
  25  *
  26  * $FreeBSD: src/sys/netgraph/ng_nat.c,v 1.12 2008/06/01 15:13:32 mav Exp $
  27  */
  28
  29 #include <sys/param.h>
  30 #include <sys/systm.h>
  31 #include <sys/kernel.h>
  32 #include <sys/mbuf.h>
  33 #include <sys/malloc.h>
  34 #include <sys/ctype.h>
  35 #include <sys/errno.h>
  36 #include <sys/syslog.h>
  37
  38 #include <netinet/in_systm.h>
  39 #include <netinet/in.h>
  40 #include <netinet/ip.h>
  41 #include <netinet/ip_var.h>
  42 #include <netinet/tcp.h>
  43 #include <machine/in_cksum.h>
  44
  45 #include <netinet/libalias/alias.h>
  46
  47 #include "ng_message.h"
  48 #include "ng_parse.h"
  49 #include "ng_nat.h"
  50 #include "netgraph.h"
  51
  52 static ng_constructor_t ng_nat_constructor;
  53 static ng_rcvmsg_t      ng_nat_rcvmsg;
  54 static ng_shutdown_t    ng_nat_shutdown;
  55 static ng_newhook_t     ng_nat_newhook;
  56 static ng_rcvdata_t     ng_nat_rcvdata;
  57 static ng_disconnect_t  ng_nat_disconnect;
  58
  59 static unsigned int     ng_nat_translate_flags(unsigned int x);
  60
  61 /* Parse type for struct ng_nat_mode. */
  62 static const struct ng_parse_struct_field ng_nat_mode_fields[]
  63         = NG_NAT_MODE_INFO;
  64 static const struct ng_parse_type ng_nat_mode_type = {
  65         &ng_parse_struct_type,
  66         &ng_nat_mode_fields
  67 };
  68
  69 /* Parse type for 'description' field in structs. */
  70 static const struct ng_parse_fixedstring_info ng_nat_description_info
  71         = { NG_NAT_DESC_LENGTH };
  72 static const struct ng_parse_type ng_nat_description_type = {
  73         &ng_parse_fixedstring_type,
  74         &ng_nat_description_info
  75 };
  76
  77 /* Parse type for struct ng_nat_redirect_port. */
  78 static const struct ng_parse_struct_field ng_nat_redirect_port_fields[]
  79         = NG_NAT_REDIRECT_PORT_TYPE_INFO(&ng_nat_description_type);
  80 static const struct ng_parse_type ng_nat_redirect_port_type = {
  81         &ng_parse_struct_type,
  82         &ng_nat_redirect_port_fields
  83 };
  84
  85 /* Parse type for struct ng_nat_redirect_addr. */
  86 static const struct ng_parse_struct_field ng_nat_redirect_addr_fields[]
  87         = NG_NAT_REDIRECT_ADDR_TYPE_INFO(&ng_nat_description_type);
  88 static const struct ng_parse_type ng_nat_redirect_addr_type = {
  89         &ng_parse_struct_type,
  90         &ng_nat_redirect_addr_fields
  91 };
  92
  93 /* Parse type for struct ng_nat_redirect_proto. */
  94 static const struct ng_parse_struct_field ng_nat_redirect_proto_fields[]
  95         = NG_NAT_REDIRECT_PROTO_TYPE_INFO(&ng_nat_description_type);
  96 static const struct ng_parse_type ng_nat_redirect_proto_type = {
  97         &ng_parse_struct_type,
  98         &ng_nat_redirect_proto_fields
  99 };
 100
 101 /* Parse type for struct ng_nat_add_server. */
 102 static const struct ng_parse_struct_field ng_nat_add_server_fields[]
 103         = NG_NAT_ADD_SERVER_TYPE_INFO;
 104 static const struct ng_parse_type ng_nat_add_server_type = {
 105         &ng_parse_struct_type,
 106         &ng_nat_add_server_fields
 107 };
 108
 109 /* Parse type for one struct ng_nat_listrdrs_entry. */
 110 static const struct ng_parse_struct_field ng_nat_listrdrs_entry_fields[]
 111         = NG_NAT_LISTRDRS_ENTRY_TYPE_INFO(&ng_nat_description_type);
 112 static const struct ng_parse_type ng_nat_listrdrs_entry_type = {
 113         &ng_parse_struct_type,
 114         &ng_nat_listrdrs_entry_fields
 115 };
 116
 117 /* Parse type for 'redirects' array in struct ng_nat_list_redirects. */
 118 static int
 119 ng_nat_listrdrs_ary_getLength(const struct ng_parse_type *type,
 120         const u_char *start, const u_char *buf)
 121 {
 122         const struct ng_nat_list_redirects *lr;
 123
 124         lr = (const struct ng_nat_list_redirects *)
 125             (buf - offsetof(struct ng_nat_list_redirects, redirects));
 126         return lr->total_count;
 127 }
 128
 129 static const struct ng_parse_array_info ng_nat_listrdrs_ary_info = {
 130         &ng_nat_listrdrs_entry_type,
 131         &ng_nat_listrdrs_ary_getLength,
 132         NULL
 133 };
 134 static const struct ng_parse_type ng_nat_listrdrs_ary_type = {
 135         &ng_parse_array_type,
 136         &ng_nat_listrdrs_ary_info
 137 };
 138
 139 /* Parse type for struct ng_nat_list_redirects. */
 140 static const struct ng_parse_struct_field ng_nat_list_redirects_fields[]
 141         = NG_NAT_LIST_REDIRECTS_TYPE_INFO(&ng_nat_listrdrs_ary_type);
 142 static const struct ng_parse_type ng_nat_list_redirects_type = {
 143         &ng_parse_struct_type,
 144         &ng_nat_list_redirects_fields
 145 };
 146
 147 /* List of commands and how to convert arguments to/from ASCII. */
 148 static const struct ng_cmdlist ng_nat_cmdlist[] = {
 149         {
 150           NGM_NAT_COOKIE,
 151           NGM_NAT_SET_IPADDR,
 152           "setaliasaddr",
 153           &ng_parse_ipaddr_type,
 154           NULL
 155         },
 156         {
 157           NGM_NAT_COOKIE,
 158           NGM_NAT_SET_MODE,
 159           "setmode",
 160           &ng_nat_mode_type,
 161           NULL
 162         },
 163         {
 164           NGM_NAT_COOKIE,
 165           NGM_NAT_SET_TARGET,
 166           "settarget",
 167           &ng_parse_ipaddr_type,
 168           NULL
 169         },
 170         {
 171           NGM_NAT_COOKIE,
 172           NGM_NAT_REDIRECT_PORT,
 173           "redirectport",
 174           &ng_nat_redirect_port_type,
 175           &ng_parse_uint32_type
 176         },
 177         {
 178           NGM_NAT_COOKIE,
 179           NGM_NAT_REDIRECT_ADDR,
 180           "redirectaddr",
 181           &ng_nat_redirect_addr_type,
 182           &ng_parse_uint32_type
 183         },
 184         {
 185           NGM_NAT_COOKIE,
 186           NGM_NAT_REDIRECT_PROTO,
 187           "redirectproto",
 188           &ng_nat_redirect_proto_type,
 189           &ng_parse_uint32_type
 190         },
 191         {
 192           NGM_NAT_COOKIE,
 193           NGM_NAT_REDIRECT_DYNAMIC,
 194           "redirectdynamic",
 195           &ng_parse_uint32_type,
 196           NULL
 197         },
 198         {
 199           NGM_NAT_COOKIE,
 200           NGM_NAT_REDIRECT_DELETE,
 201           "redirectdelete",
 202           &ng_parse_uint32_type,
 203           NULL
 204         },
 205         {
 206           NGM_NAT_COOKIE,
 207           NGM_NAT_ADD_SERVER,
 208           "addserver",
 209           &ng_nat_add_server_type,
 210           NULL
 211         },
 212         {
 213           NGM_NAT_COOKIE,
 214           NGM_NAT_LIST_REDIRECTS,
 215           "listredirects",
 216           NULL,
 217           &ng_nat_list_redirects_type
 218         },
 219         {
 220           NGM_NAT_COOKIE,
 221           NGM_NAT_PROXY_RULE,
 222           "proxyrule",
 223           &ng_parse_string_type,
 224           NULL
 225         },
 226         { 0 }
 227 };
 228
 229 /* Netgraph node type descriptor. */
 230 static struct ng_type typestruct = {
 231         .version =      NG_ABI_VERSION,
 232         .name =         NG_NAT_NODE_TYPE,
 233         .constructor =  ng_nat_constructor,
 234         .rcvmsg =       ng_nat_rcvmsg,
 235         .shutdown =     ng_nat_shutdown,
 236         .newhook =      ng_nat_newhook,
 237         .rcvdata =      ng_nat_rcvdata,
 238         .disconnect =   ng_nat_disconnect,
 239         .cmdlist =      ng_nat_cmdlist,
 240 };
 241 NETGRAPH_INIT(nat, &typestruct);
 242 MODULE_DEPEND(ng_nat, libalias, 1, 1, 1);
 243
 244 /* Element for list of redirects. */
 245 struct ng_nat_rdr_lst {
 246         STAILQ_ENTRY(ng_nat_rdr_lst) entries;
 247         struct alias_link       *lnk;
 248         struct ng_nat_listrdrs_entry rdr;
 249 };
 250 STAILQ_HEAD(rdrhead, ng_nat_rdr_lst);
 251
 252 /* Information we store for each node. */
 253 struct ng_nat_priv {
 254         node_p          node;           /* back pointer to node */
 255         hook_p          in;             /* hook for demasquerading */
 256         hook_p          out;            /* hook for masquerading */
 257         struct libalias *lib;           /* libalias handler */
 258         uint32_t        flags;          /* status flags */
 259         uint32_t        rdrcount;       /* number or redirects in list */
 260         uint32_t        nextid;         /* for next in turn in list */
 261         struct rdrhead  redirhead;      /* redirect list header */
 262 };
 263 typedef struct ng_nat_priv *priv_p;
 264
 265 /* Values of flags */
 266 #define NGNAT_CONNECTED         0x1     /* We have both hooks connected */
 267 #define NGNAT_ADDR_DEFINED      0x2     /* NGM_NAT_SET_IPADDR happened */
 268
 269 static int
 270 ng_nat_constructor(node_p node)
 271 {
 272         priv_p priv;
 273
 274         /* Initialize private descriptor. */
 275         priv = kmalloc(sizeof(*priv), M_NETGRAPH,
 276                        M_WAITOK | M_NULLOK | M_ZERO);
 277         if (priv == NULL)
 278                 return (ENOMEM);
 279
 280         /* Init aliasing engine. */
 281         priv->lib = LibAliasInit(NULL);
 282         if (priv->lib == NULL) {
 283                 kfree(priv, M_NETGRAPH);
 284                 return (ENOMEM);
 285         }
 286
 287         /* Set same ports on. */
 288         (void )LibAliasSetMode(priv->lib, PKT_ALIAS_SAME_PORTS,
 289             PKT_ALIAS_SAME_PORTS);
 290
 291         /* Init redirects housekeeping. */
 292         priv->rdrcount = 0;
 293         priv->nextid = 1;
 294         STAILQ_INIT(&priv->redirhead);
 295
 296         /* Link structs together. */
 297         NG_NODE_SET_PRIVATE(node, priv);
 298         priv->node = node;
 299
 300         /*
 301          * libalias is not thread safe, so our node
 302          * must be single threaded.
 303          */
 304         NG_NODE_FORCE_WRITER(node);
 305
 306         return (0);
 307 }
 308
 309 static int
 310 ng_nat_newhook(node_p node, hook_p hook, const char *name)
 311 {
 312         const priv_p priv = NG_NODE_PRIVATE(node);
 313
 314         if (strcmp(name, NG_NAT_HOOK_IN) == 0) {
 315                 priv->in = hook;
 316         } else if (strcmp(name, NG_NAT_HOOK_OUT) == 0) {
 317                 priv->out = hook;
 318         } else
 319                 return (EINVAL);
 320
 321         if (priv->out != NULL &&
 322             priv->in != NULL)
 323                 priv->flags |= NGNAT_CONNECTED;
 324
 325         return(0);
 326 }
 327
 328 static int
 329 ng_nat_rcvmsg(node_p node, item_p item, hook_p lasthook)
 330 {
 331         const priv_p priv = NG_NODE_PRIVATE(node);
 332         struct ng_mesg *resp = NULL;
 333         struct ng_mesg *msg;
 334         int error = 0;
 335
 336         NGI_GET_MSG(item, msg);
 337
 338         switch (msg->header.typecookie) {
 339         case NGM_NAT_COOKIE:
 340                 switch (msg->header.cmd) {
 341                 case NGM_NAT_SET_IPADDR:
 342                     {
 343                         struct in_addr *const ia = (struct in_addr *)msg->data;
 344
 345                         if (msg->header.arglen < sizeof(*ia)) {
 346                                 error = EINVAL;
 347                                 break;
 348                         }
 349
 350                         LibAliasSetAddress(priv->lib, *ia);
 351
 352                         priv->flags |= NGNAT_ADDR_DEFINED;
 353                     }
 354                         break;
 355                 case NGM_NAT_SET_MODE:
 356                     {
 357                         struct ng_nat_mode *const mode =
 358                             (struct ng_nat_mode *)msg->data;
 359
 360                         if (msg->header.arglen < sizeof(*mode)) {
 361                                 error = EINVAL;
 362                                 break;
 363                         }
 364
 365                         if (LibAliasSetMode(priv->lib,
 366                             ng_nat_translate_flags(mode->flags),
 367                             ng_nat_translate_flags(mode->mask)) < 0) {
 368                                 error = ENOMEM;
 369                                 break;
 370                         }
 371                     }
 372                         break;
 373                 case NGM_NAT_SET_TARGET:
 374                     {
 375                         struct in_addr *const ia = (struct in_addr *)msg->data;
 376
 377                         if (msg->header.arglen < sizeof(*ia)) {
 378                                 error = EINVAL;
 379                                 break;
 380                         }
 381
 382                         LibAliasSetTarget(priv->lib, *ia);
 383                     }
 384                         break;
 385                 case NGM_NAT_REDIRECT_PORT:
 386                     {
 387                         struct ng_nat_rdr_lst *entry;
 388                         struct ng_nat_redirect_port *const rp =
 389                             (struct ng_nat_redirect_port *)msg->data;
 390
 391                         if (msg->header.arglen < sizeof(*rp)) {
 392                                 error = EINVAL;
 393                                 break;
 394                         }
 395
 396                         if ((entry = kmalloc(sizeof(struct ng_nat_rdr_lst),
 397                             M_NETGRAPH, M_WAITOK | M_NULLOK | M_ZERO)) == NULL) {
 398                                 error = ENOMEM;
 399                                 break;
 400                         }
 401
 402                         /* Try actual redirect. */
 403                         entry->lnk = LibAliasRedirectPort(priv->lib,
 404                                 rp->local_addr, htons(rp->local_port),
 405                                 rp->remote_addr, htons(rp->remote_port),
 406                                 rp->alias_addr, htons(rp->alias_port),
 407                                 rp->proto);
 408
 409                         if (entry->lnk == NULL) {
 410                                 error = ENOMEM;
 411                                 kfree(entry, M_NETGRAPH);
 412                                 break;
 413                         }
 414
 415                         /* Successful, save info in our internal list. */
 416                         entry->rdr.local_addr = rp->local_addr;
 417                         entry->rdr.alias_addr = rp->alias_addr;
 418                         entry->rdr.remote_addr = rp->remote_addr;
 419                         entry->rdr.local_port = rp->local_port;
 420                         entry->rdr.alias_port = rp->alias_port;
 421                         entry->rdr.remote_port = rp->remote_port;
 422                         entry->rdr.proto = rp->proto;
 423                         bcopy(rp->description, entry->rdr.description,
 424                             NG_NAT_DESC_LENGTH);
 425
 426                         /* Safety precaution. */
 427                         entry->rdr.description[NG_NAT_DESC_LENGTH-1] = '\0';
 428
 429                         entry->rdr.id = priv->nextid++;
 430                         priv->rdrcount++;
 431
 432                         /* Link to list of redirects. */
 433                         STAILQ_INSERT_TAIL(&priv->redirhead, entry, entries);
 434
 435                         /* Response with id of newly added entry. */
 436                         NG_MKRESPONSE(resp, msg, sizeof(entry->rdr.id), M_WAITOK | M_NULLOK);
 437                         if (resp == NULL) {
 438                                 error = ENOMEM;
 439                                 break;
 440                         }
 441                         bcopy(&entry->rdr.id, resp->data, sizeof(entry->rdr.id));
 442                     }
 443                         break;
 444                 case NGM_NAT_REDIRECT_ADDR:
 445                     {
 446                         struct ng_nat_rdr_lst *entry;
 447                         struct ng_nat_redirect_addr *const ra =
 448                             (struct ng_nat_redirect_addr *)msg->data;
 449
 450                         if (msg->header.arglen < sizeof(*ra)) {
 451                                 error = EINVAL;
 452                                 break;
 453                         }
 454
 455                         if ((entry = kmalloc(sizeof(struct ng_nat_rdr_lst),
 456                             M_NETGRAPH, M_WAITOK | M_NULLOK | M_ZERO)) == NULL) {
 457                                 error = ENOMEM;
 458                                 break;
 459                         }
 460
 461                         /* Try actual redirect. */
 462                         entry->lnk = LibAliasRedirectAddr(priv->lib,
 463                                 ra->local_addr, ra->alias_addr);
 464
 465                         if (entry->lnk == NULL) {
 466                                 error = ENOMEM;
 467                                 kfree(entry, M_NETGRAPH);
 468                                 break;
 469                         }
 470
 471                         /* Successful, save info in our internal list. */
 472                         entry->rdr.local_addr = ra->local_addr;
 473                         entry->rdr.alias_addr = ra->alias_addr;
 474                         entry->rdr.proto = NG_NAT_REDIRPROTO_ADDR;
 475                         bcopy(ra->description, entry->rdr.description,
 476                             NG_NAT_DESC_LENGTH);
 477
 478                         /* Safety precaution. */
 479                         entry->rdr.description[NG_NAT_DESC_LENGTH-1] = '\0';
 480
 481                         entry->rdr.id = priv->nextid++;
 482                         priv->rdrcount++;
 483
 484                         /* Link to list of redirects. */
 485                         STAILQ_INSERT_TAIL(&priv->redirhead, entry, entries);
 486
 487                         /* Response with id of newly added entry. */
 488                         NG_MKRESPONSE(resp, msg, sizeof(entry->rdr.id), M_WAITOK | M_NULLOK);
 489                         if (resp == NULL) {
 490                                 error = ENOMEM;
 491                                 break;
 492                         }
 493                         bcopy(&entry->rdr.id, resp->data, sizeof(entry->rdr.id));
 494                     }
 495                         break;
 496                 case NGM_NAT_REDIRECT_PROTO:
 497                     {
 498                         struct ng_nat_rdr_lst *entry;
 499                         struct ng_nat_redirect_proto *const rp =
 500                             (struct ng_nat_redirect_proto *)msg->data;
 501
 502                         if (msg->header.arglen < sizeof(*rp)) {
 503                                 error = EINVAL;
 504                                 break;
 505                         }
 506
 507                         if ((entry = kmalloc(sizeof(struct ng_nat_rdr_lst),
 508                             M_NETGRAPH, M_WAITOK | M_NULLOK | M_ZERO)) == NULL) {
 509                                 error = ENOMEM;
 510                                 break;
 511                         }
 512
 513                         /* Try actual redirect. */
 514                         entry->lnk = LibAliasRedirectProto(priv->lib,
 515                                 rp->local_addr, rp->remote_addr,
 516                                 rp->alias_addr, rp->proto);
 517
 518                         if (entry->lnk == NULL) {
 519                                 error = ENOMEM;
 520                                 kfree(entry, M_NETGRAPH);
 521                                 break;
 522                         }
 523
 524                         /* Successful, save info in our internal list. */
 525                         entry->rdr.local_addr = rp->local_addr;
 526                         entry->rdr.alias_addr = rp->alias_addr;
 527                         entry->rdr.remote_addr = rp->remote_addr;
 528                         entry->rdr.proto = rp->proto;
 529                         bcopy(rp->description, entry->rdr.description,
 530                             NG_NAT_DESC_LENGTH);
 531
 532                         /* Safety precaution. */
 533                         entry->rdr.description[NG_NAT_DESC_LENGTH-1] = '\0';
 534
 535                         entry->rdr.id = priv->nextid++;
 536                         priv->rdrcount++;
 537
 538                         /* Link to list of redirects. */
 539                         STAILQ_INSERT_TAIL(&priv->redirhead, entry, entries);
 540
 541                         /* Response with id of newly added entry. */
 542                         NG_MKRESPONSE(resp, msg, sizeof(entry->rdr.id), M_WAITOK | M_NULLOK);
 543                         if (resp == NULL) {
 544                                 error = ENOMEM;
 545                                 break;
 546                         }
 547                         bcopy(&entry->rdr.id, resp->data, sizeof(entry->rdr.id));
 548                     }
 549                         break;
 550                 case NGM_NAT_REDIRECT_DYNAMIC:
 551                 case NGM_NAT_REDIRECT_DELETE:
 552                     {
 553                         struct ng_nat_rdr_lst *entry;
 554                         uint32_t *const id = (uint32_t *)msg->data;
 555
 556                         if (msg->header.arglen < sizeof(*id)) {
 557                                 error = EINVAL;
 558                                 break;
 559                         }
 560
 561                         /* Find entry with supplied id. */
 562                         STAILQ_FOREACH(entry, &priv->redirhead, entries) {
 563                                 if (entry->rdr.id == *id)
 564                                         break;
 565                         }
 566
 567                         /* Not found. */
 568                         if (entry == NULL) {
 569                                 error = ENOENT;
 570                                 break;
 571                         }
 572
 573                         if (msg->header.cmd == NGM_NAT_REDIRECT_DYNAMIC) {
 574                                 if (LibAliasRedirectDynamic(priv->lib,
 575                                     entry->lnk) == -1) {
 576                                         error = ENOTTY; /* XXX Something better? */
 577                                         break;
 578                                 }
 579                         } else {        /* NGM_NAT_REDIRECT_DELETE */
 580                                 LibAliasRedirectDelete(priv->lib, entry->lnk);
 581                         }
 582
 583                         /* Delete entry from our internal list. */
 584                         priv->rdrcount--;
 585                         STAILQ_REMOVE(&priv->redirhead, entry, ng_nat_rdr_lst, entries);
 586                         kfree(entry, M_NETGRAPH);
 587                     }
 588                         break;
 589                 case NGM_NAT_ADD_SERVER:
 590                     {
 591                         struct ng_nat_rdr_lst *entry;
 592                         struct ng_nat_add_server *const as =
 593                             (struct ng_nat_add_server *)msg->data;
 594
 595                         if (msg->header.arglen < sizeof(*as)) {
 596                                 error = EINVAL;
 597                                 break;
 598                         }
 599
 600                         /* Find entry with supplied id. */
 601                         STAILQ_FOREACH(entry, &priv->redirhead, entries) {
 602                                 if (entry->rdr.id == as->id)
 603                                         break;
 604                         }
 605
 606                         /* Not found. */
 607                         if (entry == NULL) {
 608                                 error = ENOENT;
 609                                 break;
 610                         }
 611
 612                         if (LibAliasAddServer(priv->lib, entry->lnk,
 613                             as->addr, htons(as->port)) == -1) {
 614                                 error = ENOMEM;
 615                                 break;
 616                         }
 617
 618                         entry->rdr.lsnat++;
 619                     }
 620                         break;
 621                 case NGM_NAT_LIST_REDIRECTS:
 622                     {
 623                         struct ng_nat_rdr_lst *entry;
 624                         struct ng_nat_list_redirects *ary;
 625                         int i = 0;
 626
 627                         NG_MKRESPONSE(resp, msg, sizeof(*ary) +
 628                             (priv->rdrcount) * sizeof(*entry), M_WAITOK | M_NULLOK);
 629                         if (resp == NULL) {
 630                                 error = ENOMEM;
 631                                 break;
 632                         }
 633
 634                         ary = (struct ng_nat_list_redirects *)resp->data;
 635                         ary->total_count = priv->rdrcount;
 636
 637                         STAILQ_FOREACH(entry, &priv->redirhead, entries) {
 638                                 bcopy(&entry->rdr, &ary->redirects[i++],
 639                                     sizeof(struct ng_nat_listrdrs_entry));
 640                         }
 641                     }
 642                         break;
 643                 case NGM_NAT_PROXY_RULE:
 644                     {
 645                         char *cmd = (char *)msg->data;
 646
 647                         if (msg->header.arglen < 6) {
 648                                 error = EINVAL;
 649                                 break;
 650                         }
 651
 652                         if (LibAliasProxyRule(priv->lib, cmd) != 0)
 653                                 error = ENOMEM;
 654                     }
 655                         break;
 656                 default:
 657                         error = EINVAL;         /* unknown command */
 658                         break;
 659                 }
 660                 break;
 661         default:
 662                 error = EINVAL;                 /* unknown cookie type */
 663                 break;
 664         }
 665
 666         NG_RESPOND_MSG(error, node, item, resp);
 667         NG_FREE_MSG(msg);
 668         return (error);
 669 }
 670
 671 static int
 672 ng_nat_rcvdata(hook_p hook, item_p item )
 673 {
 674         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
 675         struct mbuf     *m;
 676         struct ip       *ip;
 677         int rval, error = 0;
 678         char *c;
 679
 680         /* We have no required hooks. */
 681         if (!(priv->flags & NGNAT_CONNECTED)) {
 682                 NG_FREE_ITEM(item);
 683                 return (ENXIO);
 684         }
 685
 686         /* We have no alias address yet to do anything. */
 687         if (!(priv->flags & NGNAT_ADDR_DEFINED))
 688                 goto send;
 689
 690         m = NGI_M(item);
 691
 692         if ((m = m_megapullup(m, m->m_pkthdr.len)) == NULL) {
 693                 NGI_M(item) = NULL;     /* avoid double free */
 694                 NG_FREE_ITEM(item);
 695                 return (ENOBUFS);
 696         }
 697
 698         NGI_M(item) = m;
 699
 700         c = mtod(m, char *);
 701         ip = mtod(m, struct ip *);
 702
 703         KASSERT(m->m_pkthdr.len == ntohs(ip->ip_len),
 704             ("ng_nat: ip_len != m_pkthdr.len"));
 705
 706         if (hook == priv->in) {
 707                 rval = LibAliasIn(priv->lib, c, m->m_len + M_TRAILINGSPACE(m));
 708                 if (rval != PKT_ALIAS_OK &&
 709                     rval != PKT_ALIAS_FOUND_HEADER_FRAGMENT) {
 710                         NG_FREE_ITEM(item);
 711                         return (EINVAL);
 712                 }
 713         } else if (hook == priv->out) {
 714                 rval = LibAliasOut(priv->lib, c, m->m_len + M_TRAILINGSPACE(m));
 715                 if (rval != PKT_ALIAS_OK) {
 716                         NG_FREE_ITEM(item);
 717                         return (EINVAL);
 718                 }
 719         } else
 720                 panic("ng_nat: unknown hook!");
 721
 722         m->m_pkthdr.len = m->m_len = ntohs(ip->ip_len);
 723
 724         if ((ip->ip_off & htons(IP_OFFMASK)) == 0 &&
 725             ip->ip_p == IPPROTO_TCP) {
 726                 struct tcphdr *th = (struct tcphdr *)((caddr_t)ip +
 727                     (ip->ip_hl << 2));
 728
 729                 /*
 730                  * Here is our terrible HACK.
 731                  *
 732                  * Sometimes LibAlias edits contents of TCP packet.
 733                  * In this case it needs to recompute full TCP
 734                  * checksum. However, the problem is that LibAlias
 735                  * doesn't have any idea about checksum offloading
 736                  * in kernel. To workaround this, we do not do
 737                  * checksumming in LibAlias, but only mark the
 738                  * packets in th_x2 field. If we receive a marked
 739                  * packet, we calculate correct checksum for it
 740                  * aware of offloading.
 741                  *
 742                  * Why do I do such a terrible hack instead of
 743                  * recalculating checksum for each packet?
 744                  * Because the previous checksum was not checked!
 745                  * Recalculating checksums for EVERY packet will
 746                  * hide ALL transmission errors. Yes, marked packets
 747                  * still suffer from this problem. But, sigh, natd(8)
 748                  * has this problem, too.
 749                  */
 750
 751                 if (th->th_x2) {
 752                         th->th_x2 = 0;
 753                         ip->ip_len = ntohs(ip->ip_len);
 754                         th->th_sum = in_pseudo(ip->ip_src.s_addr,
 755                             ip->ip_dst.s_addr, htons(IPPROTO_TCP +
 756                             ip->ip_len - (ip->ip_hl << 2)));
 757
 758                         if ((m->m_pkthdr.csum_flags & CSUM_TCP) == 0) {
 759                                 m->m_pkthdr.csum_data = offsetof(struct tcphdr,
 760                                     th_sum);
 761                                 in_delayed_cksum(m);
 762                         }
 763                         ip->ip_len = htons(ip->ip_len);
 764                 }
 765         }
 766
 767 send:
 768         if (hook == priv->in)
 769                 NG_FWD_ITEM_HOOK(error, item, priv->out);
 770         else
 771                 NG_FWD_ITEM_HOOK(error, item, priv->in);
 772
 773         return (error);
 774 }
 775
 776 static int
 777 ng_nat_shutdown(node_p node)
 778 {
 779         const priv_p priv = NG_NODE_PRIVATE(node);
 780
 781         NG_NODE_SET_PRIVATE(node, NULL);
 782         NG_NODE_UNREF(node);
 783
 784         /* Free redirects list. */
 785         while (!STAILQ_EMPTY(&priv->redirhead)) {
 786                 struct ng_nat_rdr_lst *entry = STAILQ_FIRST(&priv->redirhead);
 787                 STAILQ_REMOVE_HEAD(&priv->redirhead, entries);
 788                 kfree(entry, M_NETGRAPH);
 789         }
 790
 791         /* Final free. */
 792         LibAliasUninit(priv->lib);
 793         kfree(priv, M_NETGRAPH);
 794
 795         return (0);
 796 }
 797
 798 static int
 799 ng_nat_disconnect(hook_p hook)
 800 {
 801         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
 802
 803         priv->flags &= ~NGNAT_CONNECTED;
 804
 805         if (hook == priv->out)
 806                 priv->out = NULL;
 807         if (hook == priv->in)
 808                 priv->in = NULL;
 809
 810         if (priv->out == NULL && priv->in == NULL)
 811                 ng_rmnode_self(NG_HOOK_NODE(hook));
 812
 813         return (0);
 814 }
 815
 816 static unsigned int
 817 ng_nat_translate_flags(unsigned int x)
 818 {
 819         unsigned int    res = 0;
 820
 821         if (x & NG_NAT_LOG)
 822                 res |= PKT_ALIAS_LOG;
 823         if (x & NG_NAT_DENY_INCOMING)
 824                 res |= PKT_ALIAS_DENY_INCOMING;
 825         if (x & NG_NAT_SAME_PORTS)
 826                 res |= PKT_ALIAS_SAME_PORTS;
 827         if (x & NG_NAT_UNREGISTERED_ONLY)
 828                 res |= PKT_ALIAS_UNREGISTERED_ONLY;
 829         if (x & NG_NAT_RESET_ON_ADDR_CHANGE)
 830                 res |= PKT_ALIAS_RESET_ON_ADDR_CHANGE;
 831         if (x & NG_NAT_PROXY_ONLY)
 832                 res |= PKT_ALIAS_PROXY_ONLY;
 833         if (x & NG_NAT_REVERSE)
 834                 res |= PKT_ALIAS_REVERSE;
 835
 836         return (res);
 837 }