sys/netgraph7/cisco/ng_cisco.c

   1 /*
   2  * ng_cisco.c
   3  */
   4
   5 /*-
   6  * Copyright (c) 1996-1999 Whistle Communications, Inc.
   7  * All rights reserved.
   8  *
   9  * Subject to the following obligations and disclaimer of warranty, use and
  10  * redistribution of this software, in source or object code forms, with or
  11  * without modifications are expressly permitted by Whistle Communications;
  12  * provided, however, that:
  13  * 1. Any and all reproductions of the source or object code must include the
  14  *    copyright notice above and the following disclaimer of warranties; and
  15  * 2. No rights are granted, in any manner or form, to use Whistle
  16  *    Communications, Inc. trademarks, including the mark "WHISTLE
  17  *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
  18  *    such appears in the above copyright notice or in the software.
  19  *
  20  * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
  21  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
  22  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
  23  * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
  24  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
  25  * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
  26  * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
  27  * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
  28  * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
  29  * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
  30  * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
  31  * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
  32  * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
  33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  35  * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
  36  * OF SUCH DAMAGE.
  37  *
  38  * Author: Julian Elischer <julian@freebsd.org>
  39  *
  40  * $FreeBSD: src/sys/netgraph/ng_cisco.c,v 1.29 2007/11/30 23:27:39 julian Exp $
  41  * $Whistle: ng_cisco.c,v 1.25 1999/11/01 09:24:51 julian Exp $
  42  */
  43
  44 #include <sys/param.h>
  45 #include <sys/systm.h>
  46 #include <sys/errno.h>
  47 #include <sys/kernel.h>
  48 #include <sys/socket.h>
  49 #include <sys/malloc.h>
  50 #include <sys/mbuf.h>
  51 #include <sys/syslog.h>
  52
  53 #include <net/if.h>
  54
  55 #include <netinet/in.h>
  56 #include <netinet/if_ether.h>
  57
  58 #include <netgraph7/ng_message.h>
  59 #include <netgraph7/netgraph.h>
  60 #include <netgraph7/ng_parse.h>
  61 #include "ng_cisco.h"
  62
  63 #define CISCO_MULTICAST         0x8f    /* Cisco multicast address */
  64 #define CISCO_UNICAST           0x0f    /* Cisco unicast address */
  65 #define CISCO_KEEPALIVE         0x8035  /* Cisco keepalive protocol */
  66 #define CISCO_ADDR_REQ          0       /* Cisco address request */
  67 #define CISCO_ADDR_REPLY        1       /* Cisco address reply */
  68 #define CISCO_KEEPALIVE_REQ     2       /* Cisco keepalive request */
  69
  70 #define KEEPALIVE_SECS          10
  71
  72 struct cisco_header {
  73         u_char  address;
  74         u_char  control;
  75         u_short protocol;
  76 };
  77
  78 #define CISCO_HEADER_LEN        sizeof (struct cisco_header)
  79
  80 struct cisco_packet {
  81         u_long  type;
  82         u_long  par1;
  83         u_long  par2;
  84         u_short rel;
  85         u_short time0;
  86         u_short time1;
  87 };
  88
  89 #define CISCO_PACKET_LEN (sizeof(struct cisco_packet))
  90
  91 struct protoent {
  92         hook_p  hook;           /* the hook for this proto */
  93         u_short af;             /* address family, -1 = downstream */
  94 };
  95
  96 struct cisco_priv {
  97         u_long  local_seq;
  98         u_long  remote_seq;
  99         u_long  seqRetries;     /* how many times we've been here throwing out
 100                                  * the same sequence number without ack */
 101         node_p  node;
 102         struct callout handle;
 103         struct protoent downstream;
 104         struct protoent inet;           /* IP information */
 105         struct in_addr localip;
 106         struct in_addr localmask;
 107         struct protoent inet6;          /* IPv6 information */
 108         struct protoent ipx;            /* IPX information */
 109 };
 110 typedef struct cisco_priv *sc_p;
 111
 112 /* Netgraph methods */
 113 static ng_constructor_t         cisco_constructor;
 114 static ng_rcvmsg_t              cisco_rcvmsg;
 115 static ng_shutdown_t            cisco_shutdown;
 116 static ng_newhook_t             cisco_newhook;
 117 static ng_rcvdata_t             cisco_rcvdata;
 118 static ng_disconnect_t          cisco_disconnect;
 119
 120 /* Other functions */
 121 static int      cisco_input(sc_p sc, item_p item);
 122 static void     cisco_keepalive(node_p node, hook_p hook, void *arg1, int arg2);
 123 static int      cisco_send(sc_p sc, int type, long par1, long par2);
 124 static void     cisco_notify(sc_p sc, uint32_t cmd);
 125
 126 /* Parse type for struct ng_cisco_ipaddr */
 127 static const struct ng_parse_struct_field ng_cisco_ipaddr_type_fields[]
 128         = NG_CISCO_IPADDR_TYPE_INFO;
 129 static const struct ng_parse_type ng_cisco_ipaddr_type = {
 130         &ng_parse_struct_type,
 131         &ng_cisco_ipaddr_type_fields
 132 };
 133
 134 /* Parse type for struct ng_async_stat */
 135 static const struct ng_parse_struct_field ng_cisco_stats_type_fields[]
 136         = NG_CISCO_STATS_TYPE_INFO;
 137 static const struct ng_parse_type ng_cisco_stats_type = {
 138         &ng_parse_struct_type,
 139         &ng_cisco_stats_type_fields
 140 };
 141
 142 /* List of commands and how to convert arguments to/from ASCII */
 143 static const struct ng_cmdlist ng_cisco_cmdlist[] = {
 144         {
 145           NGM_CISCO_COOKIE,
 146           NGM_CISCO_SET_IPADDR,
 147           "setipaddr",
 148           &ng_cisco_ipaddr_type,
 149           NULL
 150         },
 151         {
 152           NGM_CISCO_COOKIE,
 153           NGM_CISCO_GET_IPADDR,
 154           "getipaddr",
 155           NULL,
 156           &ng_cisco_ipaddr_type
 157         },
 158         {
 159           NGM_CISCO_COOKIE,
 160           NGM_CISCO_GET_STATUS,
 161           "getstats",
 162           NULL,
 163           &ng_cisco_stats_type
 164         },
 165         { 0 }
 166 };
 167
 168 /* Node type */
 169 static struct ng_type typestruct = {
 170         .version =      NG_ABI_VERSION,
 171         .name =         NG_CISCO_NODE_TYPE,
 172         .constructor =  cisco_constructor,
 173         .rcvmsg =       cisco_rcvmsg,
 174         .shutdown =     cisco_shutdown,
 175         .newhook =      cisco_newhook,
 176         .rcvdata =      cisco_rcvdata,
 177         .disconnect =   cisco_disconnect,
 178         .cmdlist =      ng_cisco_cmdlist,
 179 };
 180 NETGRAPH_INIT(cisco, &typestruct);
 181
 182 /*
 183  * Node constructor
 184  */
 185 static int
 186 cisco_constructor(node_p node)
 187 {
 188         sc_p sc;
 189
 190         sc = kmalloc(sizeof(*sc), M_NETGRAPH, M_WAITOK | M_NULLOK | M_ZERO);
 191         if (sc == NULL)
 192                 return (ENOMEM);
 193
 194         ng_callout_init(&sc->handle);
 195         NG_NODE_SET_PRIVATE(node, sc);
 196         sc->node = node;
 197
 198         /* Initialise the varous protocol hook holders */
 199         sc->downstream.af = 0xffff;
 200         sc->inet.af = AF_INET;
 201         sc->inet6.af = AF_INET6;
 202         sc->ipx.af = AF_IPX;
 203         return (0);
 204 }
 205
 206 /*
 207  * Check new hook
 208  */
 209 static int
 210 cisco_newhook(node_p node, hook_p hook, const char *name)
 211 {
 212         const sc_p sc = NG_NODE_PRIVATE(node);
 213
 214         if (strcmp(name, NG_CISCO_HOOK_DOWNSTREAM) == 0) {
 215                 sc->downstream.hook = hook;
 216                 NG_HOOK_SET_PRIVATE(hook, &sc->downstream);
 217
 218                 /* Start keepalives */
 219                 ng_callout(&sc->handle, node, NULL, (hz * KEEPALIVE_SECS),
 220                     &cisco_keepalive, (void *)sc, 0);
 221         } else if (strcmp(name, NG_CISCO_HOOK_INET) == 0) {
 222                 sc->inet.hook = hook;
 223                 NG_HOOK_SET_PRIVATE(hook, &sc->inet);
 224         } else if (strcmp(name, NG_CISCO_HOOK_INET6) == 0) {
 225                 sc->inet6.hook = hook;
 226                 NG_HOOK_SET_PRIVATE(hook, &sc->inet6);
 227         } else if (strcmp(name, NG_CISCO_HOOK_IPX) == 0) {
 228                 sc->ipx.hook = hook;
 229                 NG_HOOK_SET_PRIVATE(hook, &sc->ipx);
 230         } else if (strcmp(name, NG_CISCO_HOOK_DEBUG) == 0) {
 231                 NG_HOOK_SET_PRIVATE(hook, NULL);        /* unimplemented */
 232         } else
 233                 return (EINVAL);
 234         return 0;
 235 }
 236
 237 /*
 238  * Receive control message.
 239  */
 240 static int
 241 cisco_rcvmsg(node_p node, item_p item, hook_p lasthook)
 242 {
 243         struct ng_mesg *msg;
 244         const sc_p sc = NG_NODE_PRIVATE(node);
 245         struct ng_mesg *resp = NULL;
 246         int error = 0;
 247
 248         NGI_GET_MSG(item, msg);
 249         switch (msg->header.typecookie) {
 250         case NGM_GENERIC_COOKIE:
 251                 switch (msg->header.cmd) {
 252                 case NGM_TEXT_STATUS:
 253                     {
 254                         char *arg;
 255                         int pos;
 256
 257                         NG_MKRESPONSE(resp, msg, NG_TEXTRESPONSE, M_WAITOK | M_NULLOK);
 258                         if (resp == NULL) {
 259                                 error = ENOMEM;
 260                                 break;
 261                         }
 262                         arg = (char *) resp->data;
 263                         pos = ksprintf(arg,
 264                           "keepalive period: %d sec; ", KEEPALIVE_SECS);
 265                         pos += ksprintf(arg + pos,
 266                           "unacknowledged keepalives: %ld", sc->seqRetries);
 267                         resp->header.arglen = pos + 1;
 268                         break;
 269                     }
 270                 default:
 271                         error = EINVAL;
 272                         break;
 273                 }
 274                 break;
 275         case NGM_CISCO_COOKIE:
 276                 switch (msg->header.cmd) {
 277                 case NGM_CISCO_GET_IPADDR:      /* could be a late reply! */
 278                         if ((msg->header.flags & NGF_RESP) == 0) {
 279                                 struct in_addr *ips;
 280
 281                                 NG_MKRESPONSE(resp, msg,
 282                                     2 * sizeof(*ips), M_WAITOK | M_NULLOK);
 283                                 if (!resp) {
 284                                         error = ENOMEM;
 285                                         break;
 286                                 }
 287                                 ips = (struct in_addr *) resp->data;
 288                                 ips[0] = sc->localip;
 289                                 ips[1] = sc->localmask;
 290                                 break;
 291                         }
 292                         /* FALLTHROUGH */       /* ...if it's a reply */
 293                 case NGM_CISCO_SET_IPADDR:
 294                     {
 295                         struct in_addr *const ips = (struct in_addr *)msg->data;
 296
 297                         if (msg->header.arglen < 2 * sizeof(*ips)) {
 298                                 error = EINVAL;
 299                                 break;
 300                         }
 301                         sc->localip = ips[0];
 302                         sc->localmask = ips[1];
 303                         break;
 304                     }
 305                 case NGM_CISCO_GET_STATUS:
 306                     {
 307                         struct ng_cisco_stats *stat;
 308
 309                         NG_MKRESPONSE(resp, msg, sizeof(*stat), M_WAITOK | M_NULLOK);
 310                         if (!resp) {
 311                                 error = ENOMEM;
 312                                 break;
 313                         }
 314                         stat = (struct ng_cisco_stats *)resp->data;
 315                         stat->seqRetries = sc->seqRetries;
 316                         stat->keepAlivePeriod = KEEPALIVE_SECS;
 317                         break;
 318                     }
 319                 default:
 320                         error = EINVAL;
 321                         break;
 322                 }
 323                 break;
 324         default:
 325                 error = EINVAL;
 326                 break;
 327         }
 328         NG_RESPOND_MSG(error, node, item, resp);
 329         NG_FREE_MSG(msg);
 330         return (error);
 331 }
 332
 333 /*
 334  * Receive data
 335  */
 336 static int
 337 cisco_rcvdata(hook_p hook, item_p item)
 338 {
 339         const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
 340         struct protoent *pep;
 341         struct cisco_header *h;
 342         struct mbuf *m;
 343         int error = 0;
 344
 345         if ((pep = NG_HOOK_PRIVATE(hook)) == NULL)
 346                 goto out;
 347
 348         /* If it came from our downlink, deal with it separately */
 349         if (pep->af == 0xffff)
 350                 return (cisco_input(sc, item));
 351
 352         /* OK so it came from a protocol, heading out. Prepend general data
 353            packet header. For now, IP,IPX only  */
 354         m = NGI_M(item); /* still associated with item */
 355         M_PREPEND(m, CISCO_HEADER_LEN, MB_DONTWAIT);
 356         if (!m) {
 357                 error = ENOBUFS;
 358                 goto out;
 359         }
 360         h = mtod(m, struct cisco_header *);
 361         h->address = CISCO_UNICAST;
 362         h->control = 0;
 363
 364         switch (pep->af) {
 365         case AF_INET:           /* Internet Protocol */
 366                 h->protocol = htons(ETHERTYPE_IP);
 367                 break;
 368         case AF_INET6:
 369                 h->protocol = htons(ETHERTYPE_IPV6);
 370                 break;
 371         case AF_IPX:            /* Novell IPX Protocol */
 372                 h->protocol = htons(ETHERTYPE_IPX);
 373                 break;
 374         default:
 375                 error = EAFNOSUPPORT;
 376                 goto out;
 377         }
 378
 379         /* Send it */
 380         NG_FWD_NEW_DATA(error, item,  sc->downstream.hook, m);
 381         return (error);
 382
 383 out:
 384         NG_FREE_ITEM(item);
 385         return (error);
 386 }
 387
 388 /*
 389  * Shutdown node
 390  */
 391 static int
 392 cisco_shutdown(node_p node)
 393 {
 394         const sc_p sc = NG_NODE_PRIVATE(node);
 395
 396         NG_NODE_SET_PRIVATE(node, NULL);
 397         NG_NODE_UNREF(sc->node);
 398         kfree(sc, M_NETGRAPH);
 399         return (0);
 400 }
 401
 402 /*
 403  * Disconnection of a hook
 404  *
 405  * For this type, removal of the last link destroys the node
 406  */
 407 static int
 408 cisco_disconnect(hook_p hook)
 409 {
 410         const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
 411         struct protoent *pep;
 412
 413         /* Check it's not the debug hook */
 414         if ((pep = NG_HOOK_PRIVATE(hook))) {
 415                 pep->hook = NULL;
 416                 if (pep->af == 0xffff)
 417                         /* If it is the downstream hook, stop the timers */
 418                         ng_uncallout(&sc->handle, NG_HOOK_NODE(hook));
 419         }
 420
 421         /* If no more hooks, remove the node */
 422         if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
 423         && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook))))
 424                 ng_rmnode_self(NG_HOOK_NODE(hook));
 425         return (0);
 426 }
 427
 428 /*
 429  * Receive data
 430  */
 431 static int
 432 cisco_input(sc_p sc, item_p item)
 433 {
 434         const struct cisco_header *h;
 435         struct cisco_header hdrbuf;
 436         struct protoent *pep;
 437         struct mbuf *m;
 438         int error = 0;
 439
 440         /* Get data */
 441         m = NGI_M(item);
 442
 443         /* Sanity check header length */
 444         if (m->m_pkthdr.len < sizeof(*h)) {
 445                 error = EINVAL;
 446                 goto drop;
 447         }
 448
 449         /* Get cisco header */
 450         if (m->m_len >= sizeof(*h))                     /* the common case */
 451                 h = mtod(m, const struct cisco_header *);
 452         else {
 453                 m_copydata(m, 0, sizeof(*h), (caddr_t)&hdrbuf);
 454                 h = &hdrbuf;
 455         }
 456         m_adj(m, sizeof(*h));
 457
 458         /* Check header address */
 459         switch (h->address) {
 460         default:                /* Invalid Cisco packet. */
 461                 goto drop;
 462         case CISCO_UNICAST:
 463         case CISCO_MULTICAST:
 464                 /* Don't check the control field here (RFC 1547). */
 465                 switch (ntohs(h->protocol)) {
 466                 default:
 467                         goto drop;
 468                 case CISCO_KEEPALIVE:
 469                     {
 470                         const struct cisco_packet *p;
 471                         struct cisco_packet pktbuf;
 472
 473                         /* Sanity check packet length */
 474                         if (m->m_pkthdr.len < sizeof(*p)) {
 475                                 error = EINVAL;
 476                                 goto drop;
 477                         }
 478
 479                         /* Get cisco packet */
 480                         if (m->m_len >= sizeof(*p))     /* the common case */
 481                                 p = mtod(m, const struct cisco_packet *);
 482                         else {
 483                                 m_copydata(m, 0, sizeof(*p), (caddr_t)&pktbuf);
 484                                 p = &pktbuf;
 485                         }
 486
 487                         /* Check packet type */
 488                         switch (ntohl(p->type)) {
 489                         default:
 490                                 log(LOG_WARNING,
 491                                     "cisco: unknown cisco packet type: 0x%lx\n",
 492                                        (long)ntohl(p->type));
 493                                 break;
 494                         case CISCO_ADDR_REPLY:
 495                                 /* Reply on address request, ignore */
 496                                 break;
 497                         case CISCO_KEEPALIVE_REQ:
 498                                 sc->remote_seq = ntohl(p->par1);
 499                                 if (sc->local_seq == ntohl(p->par2)) {
 500                                         sc->local_seq++;
 501                                         if (sc->seqRetries > 1)
 502                                                 cisco_notify(sc, NGM_LINK_IS_UP);
 503                                         sc->seqRetries = 0;
 504                                 }
 505                                 break;
 506                         case CISCO_ADDR_REQ:
 507                             {
 508                                 struct ng_mesg *msg;
 509                                 int dummy_error = 0;
 510
 511                                 /* Ask inet peer for IP address information */
 512                                 if (sc->inet.hook == NULL)
 513                                         goto nomsg;
 514                                 NG_MKMESSAGE(msg, NGM_CISCO_COOKIE,
 515                                     NGM_CISCO_GET_IPADDR, 0, M_WAITOK | M_NULLOK);
 516                                 if (msg == NULL)
 517                                         goto nomsg;
 518                                 NG_SEND_MSG_HOOK(dummy_error,
 519                                     sc->node, msg, sc->inet.hook, 0);
 520                 /*
 521                  * XXX Now maybe we should set a flag telling
 522                  * our receiver to send this message when the response comes in
 523                  * instead of now when the data may be bad.
 524                  */
 525                 nomsg:
 526                                 /* Send reply to peer device */
 527                                 error = cisco_send(sc, CISCO_ADDR_REPLY,
 528                                             ntohl(sc->localip.s_addr),
 529                                             ntohl(sc->localmask.s_addr));
 530                                 break;
 531                             }
 532                         }
 533                         goto drop;
 534                     }
 535                 case ETHERTYPE_IP:
 536                         pep = &sc->inet;
 537                         break;
 538                 case ETHERTYPE_IPV6:
 539                         pep = &sc->inet6;
 540                         break;
 541                 case ETHERTYPE_IPX:
 542                         pep = &sc->ipx;
 543                         break;
 544                 }
 545                 break;
 546         }
 547
 548         /* Drop if payload is empty */
 549         if (m->m_pkthdr.len == 0) {
 550                 error = EINVAL;
 551                 goto drop;
 552         }
 553
 554         /* Send it on */
 555         if (pep->hook == NULL)
 556                 goto drop;
 557         NG_FWD_NEW_DATA(error, item, pep->hook, m);
 558         return (error);
 559
 560 drop:
 561         NG_FREE_ITEM(item);
 562         return (error);
 563 }
 564
 565
 566 /*
 567  * Send keepalive packets, every 10 seconds.
 568  */
 569 static void
 570 cisco_keepalive(node_p node, hook_p hook, void *arg1, int arg2)
 571 {
 572         const sc_p sc = arg1;
 573
 574         cisco_send(sc, CISCO_KEEPALIVE_REQ, sc->local_seq, sc->remote_seq);
 575         if (sc->seqRetries++ > 1)
 576                 cisco_notify(sc, NGM_LINK_IS_DOWN);
 577         ng_callout(&sc->handle, node, NULL, (hz * KEEPALIVE_SECS),
 578             &cisco_keepalive, (void *)sc, 0);
 579 }
 580
 581 /*
 582  * Send Cisco keepalive packet.
 583  */
 584 static int
 585 cisco_send(sc_p sc, int type, long par1, long par2)
 586 {
 587         struct cisco_header *h;
 588         struct cisco_packet *ch;
 589         struct mbuf *m;
 590         struct timeval time;
 591         u_long  t;
 592         int     error = 0;
 593
 594         getmicrouptime(&time);
 595
 596         MGETHDR(m, MB_DONTWAIT, MT_DATA);
 597         if (!m)
 598                 return (ENOBUFS);
 599
 600         t = time.tv_sec * 1000 + time.tv_usec / 1000;
 601         m->m_pkthdr.len = m->m_len = CISCO_HEADER_LEN + CISCO_PACKET_LEN;
 602         m->m_pkthdr.rcvif = 0;
 603
 604         h = mtod(m, struct cisco_header *);
 605         h->address = CISCO_MULTICAST;
 606         h->control = 0;
 607         h->protocol = htons(CISCO_KEEPALIVE);
 608
 609         ch = (struct cisco_packet *) (h + 1);
 610         ch->type = htonl(type);
 611         ch->par1 = htonl(par1);
 612         ch->par2 = htonl(par2);
 613         ch->rel = -1;
 614         ch->time0 = htons((u_short) (t >> 16));
 615         ch->time1 = htons((u_short) t);
 616
 617         NG_SEND_DATA_ONLY(error, sc->downstream.hook, m);
 618         return (error);
 619 }
 620
 621 /*
 622  * Send linkstate to upstream node.
 623  */
 624 static void
 625 cisco_notify(sc_p sc, uint32_t cmd)
 626 {
 627         struct ng_mesg *msg;
 628         int dummy_error = 0;
 629
 630         if (sc->inet.hook == NULL) /* nothing to notify */
 631                 return;
 632
 633         NG_MKMESSAGE(msg, NGM_FLOW_COOKIE, cmd, 0, M_WAITOK | M_NULLOK);
 634         if (msg != NULL)
 635                 NG_SEND_MSG_HOOK(dummy_error, sc->node, msg, sc->inet.hook, 0);
 636 }