sys/netgraph/bridge/ng_bridge.c

   1
   2 /*
   3  * ng_bridge.c
   4  *
   5  * Copyright (c) 2000 Whistle Communications, Inc.
   6  * All rights reserved.
   7  *
   8  * Subject to the following obligations and disclaimer of warranty, use and
   9  * redistribution of this software, in source or object code forms, with or
  10  * without modifications are expressly permitted by Whistle Communications;
  11  * provided, however, that:
  12  * 1. Any and all reproductions of the source or object code must include the
  13  *    copyright notice above and the following disclaimer of warranties; and
  14  * 2. No rights are granted, in any manner or form, to use Whistle
  15  *    Communications, Inc. trademarks, including the mark "WHISTLE
  16  *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
  17  *    such appears in the above copyright notice or in the software.
  18  *
  19  * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
  20  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
  21  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
  22  * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
  23  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
  24  * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
  25  * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
  26  * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
  27  * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
  28  * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
  29  * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
  30  * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
  31  * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
  32  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  33  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  34  * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
  35  * OF SUCH DAMAGE.
  36  *
  37  * Author: Archie Cobbs <archie@freebsd.org>
  38  *
  39  * $FreeBSD: src/sys/netgraph/ng_bridge.c,v 1.1.2.5 2002/07/02 23:44:02 archie Exp $
  40  * $DragonFly: src/sys/netgraph/bridge/ng_bridge.c,v 1.11 2008/01/05 14:02:39 swildner Exp $
  41  */
  42
  43 /*
  44  * ng_bridge(4) netgraph node type
  45  *
  46  * The node performs standard intelligent Ethernet bridging over
  47  * each of its connected hooks, or links.  A simple loop detection
  48  * algorithm is included which disables a link for priv->conf.loopTimeout
  49  * seconds when a host is seen to have jumped from one link to
  50  * another within priv->conf.minStableAge seconds.
  51  *
  52  * We keep a hashtable that maps Ethernet addresses to host info,
  53  * which is contained in struct ng_bridge_host's. These structures
  54  * tell us on which link the host may be found. A host's entry will
  55  * expire after priv->conf.maxStaleness seconds.
  56  *
  57  * This node is optimzed for stable networks, where machines jump
  58  * from one port to the other only rarely.
  59  */
  60
  61 #include <sys/param.h>
  62 #include <sys/systm.h>
  63 #include <sys/kernel.h>
  64 #include <sys/malloc.h>
  65 #include <sys/mbuf.h>
  66 #include <sys/errno.h>
  67 #include <sys/syslog.h>
  68 #include <sys/socket.h>
  69 #include <sys/ctype.h>
  70 #include <sys/thread2.h>
  71
  72 #include <net/if.h>
  73 #include <net/ethernet.h>
  74
  75 #include <netinet/in.h>
  76 #include <net/ipfw/ip_fw.h>
  77
  78 #include <netgraph/ng_message.h>
  79 #include <netgraph/netgraph.h>
  80 #include <netgraph/ng_parse.h>
  81 #include "ng_bridge.h"
  82 #include <netgraph/ether/ng_ether.h>
  83
  84 /* Per-link private data */
  85 struct ng_bridge_link {
  86         hook_p                          hook;           /* netgraph hook */
  87         u_int16_t                       loopCount;      /* loop ignore timer */
  88         struct ng_bridge_link_stats     stats;          /* link stats */
  89 };
  90
  91 /* Per-node private data */
  92 struct ng_bridge_private {
  93         struct ng_bridge_bucket *tab;           /* hash table bucket array */
  94         struct ng_bridge_link   *links[NG_BRIDGE_MAX_LINKS];
  95         struct ng_bridge_config conf;           /* node configuration */
  96         node_p                  node;           /* netgraph node */
  97         u_int                   numHosts;       /* num entries in table */
  98         u_int                   numBuckets;     /* num buckets in table */
  99         u_int                   hashMask;       /* numBuckets - 1 */
 100         int                     numLinks;       /* num connected links */
 101         struct callout          timer;          /* one second periodic timer */
 102 };
 103 typedef struct ng_bridge_private *priv_p;
 104
 105 /* Information about a host, stored in a hash table entry */
 106 struct ng_bridge_hent {
 107         struct ng_bridge_host           host;   /* actual host info */
 108         SLIST_ENTRY(ng_bridge_hent)     next;   /* next entry in bucket */
 109 };
 110
 111 /* Hash table bucket declaration */
 112 SLIST_HEAD(ng_bridge_bucket, ng_bridge_hent);
 113
 114 /* Netgraph node methods */
 115 static ng_constructor_t ng_bridge_constructor;
 116 static ng_rcvmsg_t      ng_bridge_rcvmsg;
 117 static ng_shutdown_t    ng_bridge_rmnode;
 118 static ng_newhook_t     ng_bridge_newhook;
 119 static ng_rcvdata_t     ng_bridge_rcvdata;
 120 static ng_disconnect_t  ng_bridge_disconnect;
 121
 122 /* Other internal functions */
 123 static struct   ng_bridge_host *ng_bridge_get(priv_p priv, const u_char *addr);
 124 static int      ng_bridge_put(priv_p priv, const u_char *addr, int linkNum);
 125 static void     ng_bridge_rehash(priv_p priv);
 126 static void     ng_bridge_remove_hosts(priv_p priv, int linkNum);
 127 static void     ng_bridge_timeout(void *arg);
 128 static const    char *ng_bridge_nodename(node_p node);
 129
 130 /* Ethernet broadcast */
 131 static const u_char ng_bridge_bcast_addr[ETHER_ADDR_LEN] =
 132     { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
 133
 134 /* Store each hook's link number in the private field */
 135 #define LINK_NUM(hook)          (*(u_int16_t *)(&(hook)->private))
 136
 137 /* Compare Ethernet addresses using 32 and 16 bit words instead of bytewise */
 138 #define ETHER_EQUAL(a,b)        (((const u_int32_t *)(a))[0] \
 139                                         == ((const u_int32_t *)(b))[0] \
 140                                     && ((const u_int16_t *)(a))[2] \
 141                                         == ((const u_int16_t *)(b))[2])
 142
 143 /* Minimum and maximum number of hash buckets. Must be a power of two. */
 144 #define MIN_BUCKETS             (1 << 5)        /* 32 */
 145 #define MAX_BUCKETS             (1 << 14)       /* 16384 */
 146
 147 /* Configuration default values */
 148 #define DEFAULT_LOOP_TIMEOUT    60
 149 #define DEFAULT_MAX_STALENESS   (15 * 60)       /* same as ARP timeout */
 150 #define DEFAULT_MIN_STABLE_AGE  1
 151
 152 /******************************************************************
 153                     NETGRAPH PARSE TYPES
 154 ******************************************************************/
 155
 156 /*
 157  * How to determine the length of the table returned by NGM_BRIDGE_GET_TABLE
 158  */
 159 static int
 160 ng_bridge_getTableLength(const struct ng_parse_type *type,
 161         const u_char *start, const u_char *buf)
 162 {
 163         const struct ng_bridge_host_ary *const hary
 164             = (const struct ng_bridge_host_ary *)(buf - sizeof(u_int32_t));
 165
 166         return hary->numHosts;
 167 }
 168
 169 /* Parse type for struct ng_bridge_host_ary */
 170 static const struct ng_parse_struct_field ng_bridge_host_type_fields[]
 171         = NG_BRIDGE_HOST_TYPE_INFO(&ng_ether_enaddr_type);
 172 static const struct ng_parse_type ng_bridge_host_type = {
 173         &ng_parse_struct_type,
 174         &ng_bridge_host_type_fields
 175 };
 176 static const struct ng_parse_array_info ng_bridge_hary_type_info = {
 177         &ng_bridge_host_type,
 178         ng_bridge_getTableLength
 179 };
 180 static const struct ng_parse_type ng_bridge_hary_type = {
 181         &ng_parse_array_type,
 182         &ng_bridge_hary_type_info
 183 };
 184 static const struct ng_parse_struct_field ng_bridge_host_ary_type_fields[]
 185         = NG_BRIDGE_HOST_ARY_TYPE_INFO(&ng_bridge_hary_type);
 186 static const struct ng_parse_type ng_bridge_host_ary_type = {
 187         &ng_parse_struct_type,
 188         &ng_bridge_host_ary_type_fields
 189 };
 190
 191 /* Parse type for struct ng_bridge_config */
 192 static const struct ng_parse_fixedarray_info ng_bridge_ipfwary_type_info = {
 193         &ng_parse_uint8_type,
 194         NG_BRIDGE_MAX_LINKS
 195 };
 196 static const struct ng_parse_type ng_bridge_ipfwary_type = {
 197         &ng_parse_fixedarray_type,
 198         &ng_bridge_ipfwary_type_info
 199 };
 200 static const struct ng_parse_struct_field ng_bridge_config_type_fields[]
 201         = NG_BRIDGE_CONFIG_TYPE_INFO(&ng_bridge_ipfwary_type);
 202 static const struct ng_parse_type ng_bridge_config_type = {
 203         &ng_parse_struct_type,
 204         &ng_bridge_config_type_fields
 205 };
 206
 207 /* Parse type for struct ng_bridge_link_stat */
 208 static const struct ng_parse_struct_field ng_bridge_stats_type_fields[]
 209         = NG_BRIDGE_STATS_TYPE_INFO;
 210 static const struct ng_parse_type ng_bridge_stats_type = {
 211         &ng_parse_struct_type,
 212         &ng_bridge_stats_type_fields
 213 };
 214
 215 /* List of commands and how to convert arguments to/from ASCII */
 216 static const struct ng_cmdlist ng_bridge_cmdlist[] = {
 217         {
 218           NGM_BRIDGE_COOKIE,
 219           NGM_BRIDGE_SET_CONFIG,
 220           "setconfig",
 221           &ng_bridge_config_type,
 222           NULL
 223         },
 224         {
 225           NGM_BRIDGE_COOKIE,
 226           NGM_BRIDGE_GET_CONFIG,
 227           "getconfig",
 228           NULL,
 229           &ng_bridge_config_type
 230         },
 231         {
 232           NGM_BRIDGE_COOKIE,
 233           NGM_BRIDGE_RESET,
 234           "reset",
 235           NULL,
 236           NULL
 237         },
 238         {
 239           NGM_BRIDGE_COOKIE,
 240           NGM_BRIDGE_GET_STATS,
 241           "getstats",
 242           &ng_parse_uint32_type,
 243           &ng_bridge_stats_type
 244         },
 245         {
 246           NGM_BRIDGE_COOKIE,
 247           NGM_BRIDGE_CLR_STATS,
 248           "clrstats",
 249           &ng_parse_uint32_type,
 250           NULL
 251         },
 252         {
 253           NGM_BRIDGE_COOKIE,
 254           NGM_BRIDGE_GETCLR_STATS,
 255           "getclrstats",
 256           &ng_parse_uint32_type,
 257           &ng_bridge_stats_type
 258         },
 259         {
 260           NGM_BRIDGE_COOKIE,
 261           NGM_BRIDGE_GET_TABLE,
 262           "gettable",
 263           NULL,
 264           &ng_bridge_host_ary_type
 265         },
 266         { 0 }
 267 };
 268
 269 /* Node type descriptor */
 270 static struct ng_type ng_bridge_typestruct = {
 271         NG_VERSION,
 272         NG_BRIDGE_NODE_TYPE,
 273         NULL,
 274         ng_bridge_constructor,
 275         ng_bridge_rcvmsg,
 276         ng_bridge_rmnode,
 277         ng_bridge_newhook,
 278         NULL,
 279         NULL,
 280         ng_bridge_rcvdata,
 281         ng_bridge_rcvdata,
 282         ng_bridge_disconnect,
 283         ng_bridge_cmdlist,
 284 };
 285 NETGRAPH_INIT(bridge, &ng_bridge_typestruct);
 286
 287 /* Depend on ng_ether so we can use the Ethernet parse type */
 288 MODULE_DEPEND(ng_bridge, ng_ether, 1, 1, 1);
 289
 290 /******************************************************************
 291                     NETGRAPH NODE METHODS
 292 ******************************************************************/
 293
 294 /*
 295  * Node constructor
 296  */
 297 static int
 298 ng_bridge_constructor(node_p *nodep)
 299 {
 300         priv_p priv;
 301         int error;
 302
 303         /* Allocate and initialize private info */
 304         MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH, M_NOWAIT | M_ZERO);
 305         if (priv == NULL)
 306                 return (ENOMEM);
 307         callout_init(&priv->timer);
 308
 309         /* Allocate and initialize hash table, etc. */
 310         MALLOC(priv->tab, struct ng_bridge_bucket *,
 311             MIN_BUCKETS * sizeof(*priv->tab), M_NETGRAPH, M_NOWAIT | M_ZERO);
 312         if (priv->tab == NULL) {
 313                 FREE(priv, M_NETGRAPH);
 314                 return (ENOMEM);
 315         }
 316         priv->numBuckets = MIN_BUCKETS;
 317         priv->hashMask = MIN_BUCKETS - 1;
 318         priv->conf.debugLevel = 1;
 319         priv->conf.loopTimeout = DEFAULT_LOOP_TIMEOUT;
 320         priv->conf.maxStaleness = DEFAULT_MAX_STALENESS;
 321         priv->conf.minStableAge = DEFAULT_MIN_STABLE_AGE;
 322
 323         /* Call superclass constructor */
 324         if ((error = ng_make_node_common(&ng_bridge_typestruct, nodep))) {
 325                 FREE(priv, M_NETGRAPH);
 326                 return (error);
 327         }
 328         (*nodep)->private = priv;
 329         priv->node = *nodep;
 330
 331         /* Start timer; timer is always running while node is alive */
 332         callout_reset(&priv->timer, hz, ng_bridge_timeout, priv->node);
 333
 334         /* Done */
 335         return (0);
 336 }
 337
 338 /*
 339  * Method for attaching a new hook
 340  */
 341 static  int
 342 ng_bridge_newhook(node_p node, hook_p hook, const char *name)
 343 {
 344         const priv_p priv = node->private;
 345
 346         /* Check for a link hook */
 347         if (strncmp(name, NG_BRIDGE_HOOK_LINK_PREFIX,
 348             strlen(NG_BRIDGE_HOOK_LINK_PREFIX)) == 0) {
 349                 const char *cp;
 350                 char *eptr;
 351                 u_long linkNum;
 352
 353                 cp = name + strlen(NG_BRIDGE_HOOK_LINK_PREFIX);
 354                 if (!isdigit(*cp) || (cp[0] == '0' && cp[1] != '\0'))
 355                         return (EINVAL);
 356                 linkNum = strtoul(cp, &eptr, 10);
 357                 if (*eptr != '\0' || linkNum >= NG_BRIDGE_MAX_LINKS)
 358                         return (EINVAL);
 359                 if (priv->links[linkNum] != NULL)
 360                         return (EISCONN);
 361                 MALLOC(priv->links[linkNum], struct ng_bridge_link *,
 362                     sizeof(*priv->links[linkNum]), M_NETGRAPH, M_NOWAIT);
 363                 if (priv->links[linkNum] == NULL)
 364                         return (ENOMEM);
 365                 bzero(priv->links[linkNum], sizeof(*priv->links[linkNum]));
 366                 priv->links[linkNum]->hook = hook;
 367                 LINK_NUM(hook) = linkNum;
 368                 priv->numLinks++;
 369                 return (0);
 370         }
 371
 372         /* Unknown hook name */
 373         return (EINVAL);
 374 }
 375
 376 /*
 377  * Receive a control message
 378  */
 379 static int
 380 ng_bridge_rcvmsg(node_p node, struct ng_mesg *msg,
 381         const char *retaddr, struct ng_mesg **rptr)
 382 {
 383         const priv_p priv = node->private;
 384         struct ng_mesg *resp = NULL;
 385         int error = 0;
 386
 387         switch (msg->header.typecookie) {
 388         case NGM_BRIDGE_COOKIE:
 389                 switch (msg->header.cmd) {
 390                 case NGM_BRIDGE_GET_CONFIG:
 391                     {
 392                         struct ng_bridge_config *conf;
 393
 394                         NG_MKRESPONSE(resp, msg,
 395                             sizeof(struct ng_bridge_config), M_NOWAIT);
 396                         if (resp == NULL) {
 397                                 error = ENOMEM;
 398                                 break;
 399                         }
 400                         conf = (struct ng_bridge_config *)resp->data;
 401                         *conf = priv->conf;     /* no sanity checking needed */
 402                         break;
 403                     }
 404                 case NGM_BRIDGE_SET_CONFIG:
 405                     {
 406                         struct ng_bridge_config *conf;
 407                         int i;
 408
 409                         if (msg->header.arglen
 410                             != sizeof(struct ng_bridge_config)) {
 411                                 error = EINVAL;
 412                                 break;
 413                         }
 414                         conf = (struct ng_bridge_config *)msg->data;
 415                         priv->conf = *conf;
 416                         for (i = 0; i < NG_BRIDGE_MAX_LINKS; i++)
 417                                 priv->conf.ipfw[i] = !!priv->conf.ipfw[i];
 418                         break;
 419                     }
 420                 case NGM_BRIDGE_RESET:
 421                     {
 422                         int i;
 423
 424                         /* Flush all entries in the hash table */
 425                         ng_bridge_remove_hosts(priv, -1);
 426
 427                         /* Reset all loop detection counters and stats */
 428                         for (i = 0; i < NG_BRIDGE_MAX_LINKS; i++) {
 429                                 if (priv->links[i] == NULL)
 430                                         continue;
 431                                 priv->links[i]->loopCount = 0;
 432                                 bzero(&priv->links[i]->stats,
 433                                     sizeof(priv->links[i]->stats));
 434                         }
 435                         break;
 436                     }
 437                 case NGM_BRIDGE_GET_STATS:
 438                 case NGM_BRIDGE_CLR_STATS:
 439                 case NGM_BRIDGE_GETCLR_STATS:
 440                     {
 441                         struct ng_bridge_link *link;
 442                         int linkNum;
 443
 444                         /* Get link number */
 445                         if (msg->header.arglen != sizeof(u_int32_t)) {
 446                                 error = EINVAL;
 447                                 break;
 448                         }
 449                         linkNum = *((u_int32_t *)msg->data);
 450                         if (linkNum < 0 || linkNum >= NG_BRIDGE_MAX_LINKS) {
 451                                 error = EINVAL;
 452                                 break;
 453                         }
 454                         if ((link = priv->links[linkNum]) == NULL) {
 455                                 error = ENOTCONN;
 456                                 break;
 457                         }
 458
 459                         /* Get/clear stats */
 460                         if (msg->header.cmd != NGM_BRIDGE_CLR_STATS) {
 461                                 NG_MKRESPONSE(resp, msg,
 462                                     sizeof(link->stats), M_NOWAIT);
 463                                 if (resp == NULL) {
 464                                         error = ENOMEM;
 465                                         break;
 466                                 }
 467                                 bcopy(&link->stats,
 468                                     resp->data, sizeof(link->stats));
 469                         }
 470                         if (msg->header.cmd != NGM_BRIDGE_GET_STATS)
 471                                 bzero(&link->stats, sizeof(link->stats));
 472                         break;
 473                     }
 474                 case NGM_BRIDGE_GET_TABLE:
 475                     {
 476                         struct ng_bridge_host_ary *ary;
 477                         struct ng_bridge_hent *hent;
 478                         int i = 0, bucket;
 479
 480                         NG_MKRESPONSE(resp, msg, sizeof(*ary)
 481                             + (priv->numHosts * sizeof(*ary->hosts)), M_NOWAIT);
 482                         if (resp == NULL) {
 483                                 error = ENOMEM;
 484                                 break;
 485                         }
 486                         ary = (struct ng_bridge_host_ary *)resp->data;
 487                         ary->numHosts = priv->numHosts;
 488                         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
 489                                 SLIST_FOREACH(hent, &priv->tab[bucket], next)
 490                                         ary->hosts[i++] = hent->host;
 491                         }
 492                         break;
 493                     }
 494                 default:
 495                         error = EINVAL;
 496                         break;
 497                 }
 498                 break;
 499         default:
 500                 error = EINVAL;
 501                 break;
 502         }
 503
 504         /* Done */
 505         if (rptr)
 506                 *rptr = resp;
 507         else if (resp != NULL)
 508                 FREE(resp, M_NETGRAPH);
 509         FREE(msg, M_NETGRAPH);
 510         return (error);
 511 }
 512
 513 /*
 514  * Receive data on a hook
 515  */
 516 static int
 517 ng_bridge_rcvdata(hook_p hook, struct mbuf *m, meta_p meta)
 518 {
 519         const node_p node = hook->node;
 520         const priv_p priv = node->private;
 521         struct ng_bridge_host *host;
 522         struct ng_bridge_link *link;
 523         struct ether_header *eh;
 524         int error = 0, linkNum;
 525         int i, manycast;
 526
 527         /* Get link number */
 528         linkNum = LINK_NUM(hook);
 529         KASSERT(linkNum >= 0 && linkNum < NG_BRIDGE_MAX_LINKS,
 530             ("%s: linkNum=%u", __func__, linkNum));
 531         link = priv->links[linkNum];
 532         KASSERT(link != NULL, ("%s: link%d null", __func__, linkNum));
 533
 534         /* Sanity check packet and pull up header */
 535         if (m->m_pkthdr.len < ETHER_HDR_LEN) {
 536                 link->stats.recvRunts++;
 537                 NG_FREE_DATA(m, meta);
 538                 return (EINVAL);
 539         }
 540         if (m->m_len < ETHER_HDR_LEN && !(m = m_pullup(m, ETHER_HDR_LEN))) {
 541                 link->stats.memoryFailures++;
 542                 NG_FREE_META(meta);
 543                 return (ENOBUFS);
 544         }
 545         eh = mtod(m, struct ether_header *);
 546         if ((eh->ether_shost[0] & 1) != 0) {
 547                 link->stats.recvInvalid++;
 548                 NG_FREE_DATA(m, meta);
 549                 return (EINVAL);
 550         }
 551
 552         /* Is link disabled due to a loopback condition? */
 553         if (link->loopCount != 0) {
 554                 link->stats.loopDrops++;
 555                 NG_FREE_DATA(m, meta);
 556                 return (ELOOP);         /* XXX is this an appropriate error? */
 557         }
 558
 559         /* Update stats */
 560         link->stats.recvPackets++;
 561         link->stats.recvOctets += m->m_pkthdr.len;
 562         if ((manycast = (eh->ether_dhost[0] & 1)) != 0) {
 563                 if (ETHER_EQUAL(eh->ether_dhost, ng_bridge_bcast_addr)) {
 564                         link->stats.recvBroadcasts++;
 565                         manycast = 2;
 566                 } else
 567                         link->stats.recvMulticasts++;
 568         }
 569
 570         /* Look up packet's source Ethernet address in hashtable */
 571         if ((host = ng_bridge_get(priv, eh->ether_shost)) != NULL) {
 572
 573                 /* Update time since last heard from this host */
 574                 host->staleness = 0;
 575
 576                 /* Did host jump to a different link? */
 577                 if (host->linkNum != linkNum) {
 578
 579                         /*
 580                          * If the host's old link was recently established
 581                          * on the old link and it's already jumped to a new
 582                          * link, declare a loopback condition.
 583                          */
 584                         if (host->age < priv->conf.minStableAge) {
 585
 586                                 /* Log the problem */
 587                                 if (priv->conf.debugLevel >= 2) {
 588                                         struct ifnet *ifp = m->m_pkthdr.rcvif;
 589                                         char suffix[32];
 590
 591                                         if (ifp != NULL)
 592                                                 ksnprintf(suffix, sizeof(suffix),
 593                                                     " (%s)", ifp->if_xname);
 594                                         else
 595                                                 *suffix = '\0';
 596                                         log(LOG_WARNING, "ng_bridge: %s:"
 597                                             " loopback detected on %s%s\n",
 598                                             ng_bridge_nodename(node),
 599                                             hook->name, suffix);
 600                                 }
 601
 602                                 /* Mark link as linka non grata */
 603                                 link->loopCount = priv->conf.loopTimeout;
 604                                 link->stats.loopDetects++;
 605
 606                                 /* Forget all hosts on this link */
 607                                 ng_bridge_remove_hosts(priv, linkNum);
 608
 609                                 /* Drop packet */
 610                                 link->stats.loopDrops++;
 611                                 NG_FREE_DATA(m, meta);
 612                                 return (ELOOP);         /* XXX appropriate? */
 613                         }
 614
 615                         /* Move host over to new link */
 616                         host->linkNum = linkNum;
 617                         host->age = 0;
 618                 }
 619         } else {
 620                 if (!ng_bridge_put(priv, eh->ether_shost, linkNum)) {
 621                         link->stats.memoryFailures++;
 622                         NG_FREE_DATA(m, meta);
 623                         return (ENOMEM);
 624                 }
 625         }
 626
 627         /* Run packet through ipfw processing, if enabled */
 628         if (priv->conf.ipfw[linkNum] && fw_enable && ip_fw_chk_ptr != NULL) {
 629                 /* XXX not implemented yet */
 630         }
 631
 632         /*
 633          * If unicast and destination host known, deliver to host's link,
 634          * unless it is the same link as the packet came in on.
 635          */
 636         if (!manycast) {
 637
 638                 /* Determine packet destination link */
 639                 if ((host = ng_bridge_get(priv, eh->ether_dhost)) != NULL) {
 640                         struct ng_bridge_link *const destLink
 641                             = priv->links[host->linkNum];
 642
 643                         /* If destination same as incoming link, do nothing */
 644                         KASSERT(destLink != NULL,
 645                             ("%s: link%d null", __func__, host->linkNum));
 646                         if (destLink == link) {
 647                                 NG_FREE_DATA(m, meta);
 648                                 return (0);
 649                         }
 650
 651                         /* Deliver packet out the destination link */
 652                         destLink->stats.xmitPackets++;
 653                         destLink->stats.xmitOctets += m->m_pkthdr.len;
 654                         NG_SEND_DATA(error, destLink->hook, m, meta);
 655                         return (error);
 656                 }
 657
 658                 /* Destination host is not known */
 659                 link->stats.recvUnknown++;
 660         }
 661
 662         /* Distribute unknown, multicast, broadcast pkts to all other links */
 663         for (linkNum = i = 0; i < priv->numLinks - 1; linkNum++) {
 664                 struct ng_bridge_link *const destLink = priv->links[linkNum];
 665                 meta_p meta2 = NULL;
 666                 struct mbuf *m2;
 667
 668                 /* Skip incoming link and disconnected links */
 669                 if (destLink == NULL || destLink == link)
 670                         continue;
 671
 672                 /* Copy mbuf and meta info */
 673                 if (++i == priv->numLinks - 1) {                /* last link */
 674                         m2 = m;
 675                         meta2 = meta;
 676                 }  else {
 677                         m2 = m_dup(m, M_NOWAIT);        /* XXX m_copypacket() */
 678                         if (m2 == NULL) {
 679                                 link->stats.memoryFailures++;
 680                                 NG_FREE_DATA(m, meta);
 681                                 return (ENOBUFS);
 682                         }
 683                         if (meta != NULL
 684                             && (meta2 = ng_copy_meta(meta)) == NULL) {
 685                                 link->stats.memoryFailures++;
 686                                 m_freem(m2);
 687                                 NG_FREE_DATA(m, meta);
 688                                 return (ENOMEM);
 689                         }
 690                 }
 691
 692                 /* Update stats */
 693                 destLink->stats.xmitPackets++;
 694                 destLink->stats.xmitOctets += m->m_pkthdr.len;
 695                 switch (manycast) {
 696                 case 0:                                 /* unicast */
 697                         break;
 698                 case 1:                                 /* multicast */
 699                         destLink->stats.xmitMulticasts++;
 700                         break;
 701                 case 2:                                 /* broadcast */
 702                         destLink->stats.xmitBroadcasts++;
 703                         break;
 704                 }
 705
 706                 /* Send packet */
 707                 NG_SEND_DATA(error, destLink->hook, m2, meta2);
 708         }
 709         return (error);
 710 }
 711
 712 /*
 713  * Shutdown node
 714  */
 715 static int
 716 ng_bridge_rmnode(node_p node)
 717 {
 718         const priv_p priv = node->private;
 719
 720         /*
 721          * Shut down everything except the timer. There's no way to
 722          * avoid another possible timeout event (it may have already
 723          * been dequeued), so we can't free the node yet.
 724          */
 725         ng_unname(node);
 726         ng_cutlinks(node);              /* frees all link and host info */
 727         KASSERT(priv->numLinks == 0 && priv->numHosts == 0,
 728             ("%s: numLinks=%d numHosts=%d",
 729             __func__, priv->numLinks, priv->numHosts));
 730         FREE(priv->tab, M_NETGRAPH);
 731
 732         /* NG_INVALID flag is now set so node will be freed at next timeout */
 733         return (0);
 734 }
 735
 736 /*
 737  * Hook disconnection.
 738  */
 739 static int
 740 ng_bridge_disconnect(hook_p hook)
 741 {
 742         const priv_p priv = hook->node->private;
 743         int linkNum;
 744
 745         /* Get link number */
 746         linkNum = LINK_NUM(hook);
 747         KASSERT(linkNum >= 0 && linkNum < NG_BRIDGE_MAX_LINKS,
 748             ("%s: linkNum=%u", __func__, linkNum));
 749
 750         /* Remove all hosts associated with this link */
 751         ng_bridge_remove_hosts(priv, linkNum);
 752
 753         /* Free associated link information */
 754         KASSERT(priv->links[linkNum] != NULL, ("%s: no link", __func__));
 755         FREE(priv->links[linkNum], M_NETGRAPH);
 756         priv->links[linkNum] = NULL;
 757         priv->numLinks--;
 758
 759         /* If no more hooks, go away */
 760         if (hook->node->numhooks == 0)
 761                 ng_rmnode(hook->node);
 762         return (0);
 763 }
 764
 765 /******************************************************************
 766                     HASH TABLE FUNCTIONS
 767 ******************************************************************/
 768
 769 /*
 770  * Hash algorithm
 771  *
 772  * Only hashing bytes 3-6 of the Ethernet address is sufficient and fast.
 773  */
 774 #define HASH(addr,mask)         ( (((const u_int16_t *)(addr))[0]       \
 775                                  ^ ((const u_int16_t *)(addr))[1]       \
 776                                  ^ ((const u_int16_t *)(addr))[2]) & (mask) )
 777
 778 /*
 779  * Find a host entry in the table.
 780  */
 781 static struct ng_bridge_host *
 782 ng_bridge_get(priv_p priv, const u_char *addr)
 783 {
 784         const int bucket = HASH(addr, priv->hashMask);
 785         struct ng_bridge_hent *hent;
 786
 787         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
 788                 if (ETHER_EQUAL(hent->host.addr, addr))
 789                         return (&hent->host);
 790         }
 791         return (NULL);
 792 }
 793
 794 /*
 795  * Add a new host entry to the table. This assumes the host doesn't
 796  * already exist in the table. Returns 1 on success, 0 if there
 797  * was a memory allocation failure.
 798  */
 799 static int
 800 ng_bridge_put(priv_p priv, const u_char *addr, int linkNum)
 801 {
 802         const int bucket = HASH(addr, priv->hashMask);
 803         struct ng_bridge_hent *hent;
 804
 805 #ifdef INVARIANTS
 806         /* Assert that entry does not already exist in hashtable */
 807         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
 808                 KASSERT(!ETHER_EQUAL(hent->host.addr, addr),
 809                     ("%s: entry %6D exists in table", __func__, addr, ":"));
 810         }
 811 #endif
 812
 813         /* Allocate and initialize new hashtable entry */
 814         MALLOC(hent, struct ng_bridge_hent *,
 815             sizeof(*hent), M_NETGRAPH, M_NOWAIT);
 816         if (hent == NULL)
 817                 return (0);
 818         bcopy(addr, hent->host.addr, ETHER_ADDR_LEN);
 819         hent->host.linkNum = linkNum;
 820         hent->host.staleness = 0;
 821         hent->host.age = 0;
 822
 823         /* Add new element to hash bucket */
 824         SLIST_INSERT_HEAD(&priv->tab[bucket], hent, next);
 825         priv->numHosts++;
 826
 827         /* Resize table if necessary */
 828         ng_bridge_rehash(priv);
 829         return (1);
 830 }
 831
 832 /*
 833  * Resize the hash table. We try to maintain the number of buckets
 834  * such that the load factor is in the range 0.25 to 1.0.
 835  *
 836  * If we can't get the new memory then we silently fail. This is OK
 837  * because things will still work and we'll try again soon anyway.
 838  */
 839 static void
 840 ng_bridge_rehash(priv_p priv)
 841 {
 842         struct ng_bridge_bucket *newTab;
 843         int oldBucket, newBucket;
 844         int newNumBuckets;
 845         u_int newMask;
 846
 847         /* Is table too full or too empty? */
 848         if (priv->numHosts > priv->numBuckets
 849             && (priv->numBuckets << 1) <= MAX_BUCKETS)
 850                 newNumBuckets = priv->numBuckets << 1;
 851         else if (priv->numHosts < (priv->numBuckets >> 2)
 852             && (priv->numBuckets >> 2) >= MIN_BUCKETS)
 853                 newNumBuckets = priv->numBuckets >> 2;
 854         else
 855                 return;
 856         newMask = newNumBuckets - 1;
 857
 858         /* Allocate and initialize new table */
 859         MALLOC(newTab, struct ng_bridge_bucket *,
 860             newNumBuckets * sizeof(*newTab), M_NETGRAPH, M_NOWAIT | M_ZERO);
 861         if (newTab == NULL)
 862                 return;
 863
 864         /* Move all entries from old table to new table */
 865         for (oldBucket = 0; oldBucket < priv->numBuckets; oldBucket++) {
 866                 struct ng_bridge_bucket *const oldList = &priv->tab[oldBucket];
 867
 868                 while (!SLIST_EMPTY(oldList)) {
 869                         struct ng_bridge_hent *const hent
 870                             = SLIST_FIRST(oldList);
 871
 872                         SLIST_REMOVE_HEAD(oldList, next);
 873                         newBucket = HASH(hent->host.addr, newMask);
 874                         SLIST_INSERT_HEAD(&newTab[newBucket], hent, next);
 875                 }
 876         }
 877
 878         /* Replace old table with new one */
 879         if (priv->conf.debugLevel >= 3) {
 880                 log(LOG_INFO, "ng_bridge: %s: table size %d -> %d\n",
 881                     ng_bridge_nodename(priv->node),
 882                     priv->numBuckets, newNumBuckets);
 883         }
 884         FREE(priv->tab, M_NETGRAPH);
 885         priv->numBuckets = newNumBuckets;
 886         priv->hashMask = newMask;
 887         priv->tab = newTab;
 888         return;
 889 }
 890
 891 /******************************************************************
 892                     MISC FUNCTIONS
 893 ******************************************************************/
 894
 895 /*
 896  * Remove all hosts associated with a specific link from the hashtable.
 897  * If linkNum == -1, then remove all hosts in the table.
 898  */
 899 static void
 900 ng_bridge_remove_hosts(priv_p priv, int linkNum)
 901 {
 902         int bucket;
 903
 904         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
 905                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
 906
 907                 while (*hptr != NULL) {
 908                         struct ng_bridge_hent *const hent = *hptr;
 909
 910                         if (linkNum == -1 || hent->host.linkNum == linkNum) {
 911                                 *hptr = SLIST_NEXT(hent, next);
 912                                 FREE(hent, M_NETGRAPH);
 913                                 priv->numHosts--;
 914                         } else
 915                                 hptr = &SLIST_NEXT(hent, next);
 916                 }
 917         }
 918 }
 919
 920 /*
 921  * Handle our once-per-second timeout event. We do two things:
 922  * we decrement link->loopCount for those links being muted due to
 923  * a detected loopback condition, and we remove any hosts from
 924  * the hashtable whom we haven't heard from in a long while.
 925  *
 926  * If the node has the NG_INVALID flag set, our job is to kill it.
 927  */
 928 static void
 929 ng_bridge_timeout(void *arg)
 930 {
 931         const node_p node = arg;
 932         const priv_p priv = node->private;
 933         int bucket;
 934         int counter = 0;
 935         int linkNum;
 936
 937         /* If node was shut down, this is the final lingering timeout */
 938         crit_enter();
 939         if ((node->flags & NG_INVALID) != 0) {
 940                 FREE(priv, M_NETGRAPH);
 941                 node->private = NULL;
 942                 ng_unref(node);
 943                 crit_exit();
 944                 return;
 945         }
 946
 947         /* Register a new timeout, keeping the existing node reference */
 948         callout_reset(&priv->timer, hz, ng_bridge_timeout, node);
 949
 950         /* Update host time counters and remove stale entries */
 951         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
 952                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
 953
 954                 while (*hptr != NULL) {
 955                         struct ng_bridge_hent *const hent = *hptr;
 956
 957                         /* Make sure host's link really exists */
 958                         KASSERT(priv->links[hent->host.linkNum] != NULL,
 959                             ("%s: host %6D on nonexistent link %d\n",
 960                             __func__, hent->host.addr, ":",
 961                             hent->host.linkNum));
 962
 963                         /* Remove hosts we haven't heard from in a while */
 964                         if (++hent->host.staleness >= priv->conf.maxStaleness) {
 965                                 *hptr = SLIST_NEXT(hent, next);
 966                                 FREE(hent, M_NETGRAPH);
 967                                 priv->numHosts--;
 968                         } else {
 969                                 if (hent->host.age < 0xffff)
 970                                         hent->host.age++;
 971                                 hptr = &SLIST_NEXT(hent, next);
 972                                 counter++;
 973                         }
 974                 }
 975         }
 976         KASSERT(priv->numHosts == counter,
 977             ("%s: hosts: %d != %d", __func__, priv->numHosts, counter));
 978
 979         /* Decrease table size if necessary */
 980         ng_bridge_rehash(priv);
 981
 982         /* Decrease loop counter on muted looped back links */
 983         for (counter = linkNum = 0; linkNum < NG_BRIDGE_MAX_LINKS; linkNum++) {
 984                 struct ng_bridge_link *const link = priv->links[linkNum];
 985
 986                 if (link != NULL) {
 987                         if (link->loopCount != 0) {
 988                                 link->loopCount--;
 989                                 if (link->loopCount == 0
 990                                     && priv->conf.debugLevel >= 2) {
 991                                         log(LOG_INFO, "ng_bridge: %s:"
 992                                             " restoring looped back link%d\n",
 993                                             ng_bridge_nodename(node), linkNum);
 994                                 }
 995                         }
 996                         counter++;
 997                 }
 998         }
 999         KASSERT(priv->numLinks == counter,
1000             ("%s: links: %d != %d", __func__, priv->numLinks, counter));
1001
1002         /* Done */
1003         crit_exit();
1004 }
1005
1006 /*
1007  * Return node's "name", even if it doesn't have one.
1008  */
1009 static const char *
1010 ng_bridge_nodename(node_p node)
1011 {
1012         static char name[NG_NODESIZ];
1013
1014         if (node->name != NULL)
1015                 ksnprintf(name, sizeof(name), "%s", node->name);
1016         else
1017                 ksnprintf(name, sizeof(name), "[%x]", ng_node2ID(node));
1018         return name;
1019 }
1020