The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netgraph/ng_bridge.c

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    1 /*
    2  * ng_bridge.c
    3  */
    4 
    5 /*-
    6  * Copyright (c) 2000 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: Archie Cobbs <archie@freebsd.org>
   39  *
   40  * $FreeBSD: releng/11.0/sys/netgraph/ng_bridge.c 298813 2016-04-29 21:25:05Z pfg $
   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/lock.h>
   65 #include <sys/malloc.h>
   66 #include <sys/mbuf.h>
   67 #include <sys/errno.h>
   68 #include <sys/rwlock.h>
   69 #include <sys/syslog.h>
   70 #include <sys/socket.h>
   71 #include <sys/ctype.h>
   72 
   73 #include <net/if.h>
   74 #include <net/if_var.h>
   75 #include <net/ethernet.h>
   76 #include <net/vnet.h>
   77 
   78 #include <netinet/in.h>
   79 #if 0   /* not used yet */
   80 #include <netinet/ip_fw.h>
   81 #endif
   82 #include <netgraph/ng_message.h>
   83 #include <netgraph/netgraph.h>
   84 #include <netgraph/ng_parse.h>
   85 #include <netgraph/ng_bridge.h>
   86 
   87 #ifdef NG_SEPARATE_MALLOC
   88 static MALLOC_DEFINE(M_NETGRAPH_BRIDGE, "netgraph_bridge",
   89     "netgraph bridge node");
   90 #else
   91 #define M_NETGRAPH_BRIDGE M_NETGRAPH
   92 #endif
   93 
   94 /* Per-link private data */
   95 struct ng_bridge_link {
   96         hook_p                          hook;           /* netgraph hook */
   97         u_int16_t                       loopCount;      /* loop ignore timer */
   98         struct ng_bridge_link_stats     stats;          /* link stats */
   99 };
  100 
  101 /* Per-node private data */
  102 struct ng_bridge_private {
  103         struct ng_bridge_bucket *tab;           /* hash table bucket array */
  104         struct ng_bridge_link   *links[NG_BRIDGE_MAX_LINKS];
  105         struct ng_bridge_config conf;           /* node configuration */
  106         node_p                  node;           /* netgraph node */
  107         u_int                   numHosts;       /* num entries in table */
  108         u_int                   numBuckets;     /* num buckets in table */
  109         u_int                   hashMask;       /* numBuckets - 1 */
  110         int                     numLinks;       /* num connected links */
  111         int                     persistent;     /* can exist w/o hooks */
  112         struct callout          timer;          /* one second periodic timer */
  113 };
  114 typedef struct ng_bridge_private *priv_p;
  115 
  116 /* Information about a host, stored in a hash table entry */
  117 struct ng_bridge_hent {
  118         struct ng_bridge_host           host;   /* actual host info */
  119         SLIST_ENTRY(ng_bridge_hent)     next;   /* next entry in bucket */
  120 };
  121 
  122 /* Hash table bucket declaration */
  123 SLIST_HEAD(ng_bridge_bucket, ng_bridge_hent);
  124 
  125 /* Netgraph node methods */
  126 static ng_constructor_t ng_bridge_constructor;
  127 static ng_rcvmsg_t      ng_bridge_rcvmsg;
  128 static ng_shutdown_t    ng_bridge_shutdown;
  129 static ng_newhook_t     ng_bridge_newhook;
  130 static ng_rcvdata_t     ng_bridge_rcvdata;
  131 static ng_disconnect_t  ng_bridge_disconnect;
  132 
  133 /* Other internal functions */
  134 static struct   ng_bridge_host *ng_bridge_get(priv_p priv, const u_char *addr);
  135 static int      ng_bridge_put(priv_p priv, const u_char *addr, int linkNum);
  136 static void     ng_bridge_rehash(priv_p priv);
  137 static void     ng_bridge_remove_hosts(priv_p priv, int linkNum);
  138 static void     ng_bridge_timeout(node_p node, hook_p hook, void *arg1, int arg2);
  139 static const    char *ng_bridge_nodename(node_p node);
  140 
  141 /* Ethernet broadcast */
  142 static const u_char ng_bridge_bcast_addr[ETHER_ADDR_LEN] =
  143     { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
  144 
  145 /* Store each hook's link number in the private field */
  146 #define LINK_NUM(hook)          (*(u_int16_t *)(&(hook)->private))
  147 
  148 /* Compare Ethernet addresses using 32 and 16 bit words instead of bytewise */
  149 #define ETHER_EQUAL(a,b)        (((const u_int32_t *)(a))[0] \
  150                                         == ((const u_int32_t *)(b))[0] \
  151                                     && ((const u_int16_t *)(a))[2] \
  152                                         == ((const u_int16_t *)(b))[2])
  153 
  154 /* Minimum and maximum number of hash buckets. Must be a power of two. */
  155 #define MIN_BUCKETS             (1 << 5)        /* 32 */
  156 #define MAX_BUCKETS             (1 << 14)       /* 16384 */
  157 
  158 /* Configuration default values */
  159 #define DEFAULT_LOOP_TIMEOUT    60
  160 #define DEFAULT_MAX_STALENESS   (15 * 60)       /* same as ARP timeout */
  161 #define DEFAULT_MIN_STABLE_AGE  1
  162 
  163 /******************************************************************
  164                     NETGRAPH PARSE TYPES
  165 ******************************************************************/
  166 
  167 /*
  168  * How to determine the length of the table returned by NGM_BRIDGE_GET_TABLE
  169  */
  170 static int
  171 ng_bridge_getTableLength(const struct ng_parse_type *type,
  172         const u_char *start, const u_char *buf)
  173 {
  174         const struct ng_bridge_host_ary *const hary
  175             = (const struct ng_bridge_host_ary *)(buf - sizeof(u_int32_t));
  176 
  177         return hary->numHosts;
  178 }
  179 
  180 /* Parse type for struct ng_bridge_host_ary */
  181 static const struct ng_parse_struct_field ng_bridge_host_type_fields[]
  182         = NG_BRIDGE_HOST_TYPE_INFO(&ng_parse_enaddr_type);
  183 static const struct ng_parse_type ng_bridge_host_type = {
  184         &ng_parse_struct_type,
  185         &ng_bridge_host_type_fields
  186 };
  187 static const struct ng_parse_array_info ng_bridge_hary_type_info = {
  188         &ng_bridge_host_type,
  189         ng_bridge_getTableLength
  190 };
  191 static const struct ng_parse_type ng_bridge_hary_type = {
  192         &ng_parse_array_type,
  193         &ng_bridge_hary_type_info
  194 };
  195 static const struct ng_parse_struct_field ng_bridge_host_ary_type_fields[]
  196         = NG_BRIDGE_HOST_ARY_TYPE_INFO(&ng_bridge_hary_type);
  197 static const struct ng_parse_type ng_bridge_host_ary_type = {
  198         &ng_parse_struct_type,
  199         &ng_bridge_host_ary_type_fields
  200 };
  201 
  202 /* Parse type for struct ng_bridge_config */
  203 static const struct ng_parse_fixedarray_info ng_bridge_ipfwary_type_info = {
  204         &ng_parse_uint8_type,
  205         NG_BRIDGE_MAX_LINKS
  206 };
  207 static const struct ng_parse_type ng_bridge_ipfwary_type = {
  208         &ng_parse_fixedarray_type,
  209         &ng_bridge_ipfwary_type_info
  210 };
  211 static const struct ng_parse_struct_field ng_bridge_config_type_fields[]
  212         = NG_BRIDGE_CONFIG_TYPE_INFO(&ng_bridge_ipfwary_type);
  213 static const struct ng_parse_type ng_bridge_config_type = {
  214         &ng_parse_struct_type,
  215         &ng_bridge_config_type_fields
  216 };
  217 
  218 /* Parse type for struct ng_bridge_link_stat */
  219 static const struct ng_parse_struct_field ng_bridge_stats_type_fields[]
  220         = NG_BRIDGE_STATS_TYPE_INFO;
  221 static const struct ng_parse_type ng_bridge_stats_type = {
  222         &ng_parse_struct_type,
  223         &ng_bridge_stats_type_fields
  224 };
  225 
  226 /* List of commands and how to convert arguments to/from ASCII */
  227 static const struct ng_cmdlist ng_bridge_cmdlist[] = {
  228         {
  229           NGM_BRIDGE_COOKIE,
  230           NGM_BRIDGE_SET_CONFIG,
  231           "setconfig",
  232           &ng_bridge_config_type,
  233           NULL
  234         },
  235         {
  236           NGM_BRIDGE_COOKIE,
  237           NGM_BRIDGE_GET_CONFIG,
  238           "getconfig",
  239           NULL,
  240           &ng_bridge_config_type
  241         },
  242         {
  243           NGM_BRIDGE_COOKIE,
  244           NGM_BRIDGE_RESET,
  245           "reset",
  246           NULL,
  247           NULL
  248         },
  249         {
  250           NGM_BRIDGE_COOKIE,
  251           NGM_BRIDGE_GET_STATS,
  252           "getstats",
  253           &ng_parse_uint32_type,
  254           &ng_bridge_stats_type
  255         },
  256         {
  257           NGM_BRIDGE_COOKIE,
  258           NGM_BRIDGE_CLR_STATS,
  259           "clrstats",
  260           &ng_parse_uint32_type,
  261           NULL
  262         },
  263         {
  264           NGM_BRIDGE_COOKIE,
  265           NGM_BRIDGE_GETCLR_STATS,
  266           "getclrstats",
  267           &ng_parse_uint32_type,
  268           &ng_bridge_stats_type
  269         },
  270         {
  271           NGM_BRIDGE_COOKIE,
  272           NGM_BRIDGE_GET_TABLE,
  273           "gettable",
  274           NULL,
  275           &ng_bridge_host_ary_type
  276         },
  277         {
  278           NGM_BRIDGE_COOKIE,
  279           NGM_BRIDGE_SET_PERSISTENT,
  280           "setpersistent",
  281           NULL,
  282           NULL
  283         },
  284         { 0 }
  285 };
  286 
  287 /* Node type descriptor */
  288 static struct ng_type ng_bridge_typestruct = {
  289         .version =      NG_ABI_VERSION,
  290         .name =         NG_BRIDGE_NODE_TYPE,
  291         .constructor =  ng_bridge_constructor,
  292         .rcvmsg =       ng_bridge_rcvmsg,
  293         .shutdown =     ng_bridge_shutdown,
  294         .newhook =      ng_bridge_newhook,
  295         .rcvdata =      ng_bridge_rcvdata,
  296         .disconnect =   ng_bridge_disconnect,
  297         .cmdlist =      ng_bridge_cmdlist,
  298 };
  299 NETGRAPH_INIT(bridge, &ng_bridge_typestruct);
  300 
  301 /******************************************************************
  302                     NETGRAPH NODE METHODS
  303 ******************************************************************/
  304 
  305 /*
  306  * Node constructor
  307  */
  308 static int
  309 ng_bridge_constructor(node_p node)
  310 {
  311         priv_p priv;
  312 
  313         /* Allocate and initialize private info */
  314         priv = malloc(sizeof(*priv), M_NETGRAPH_BRIDGE, M_WAITOK | M_ZERO);
  315         ng_callout_init(&priv->timer);
  316 
  317         /* Allocate and initialize hash table, etc. */
  318         priv->tab = malloc(MIN_BUCKETS * sizeof(*priv->tab),
  319             M_NETGRAPH_BRIDGE, M_WAITOK | M_ZERO);
  320         priv->numBuckets = MIN_BUCKETS;
  321         priv->hashMask = MIN_BUCKETS - 1;
  322         priv->conf.debugLevel = 1;
  323         priv->conf.loopTimeout = DEFAULT_LOOP_TIMEOUT;
  324         priv->conf.maxStaleness = DEFAULT_MAX_STALENESS;
  325         priv->conf.minStableAge = DEFAULT_MIN_STABLE_AGE;
  326 
  327         /*
  328          * This node has all kinds of stuff that could be screwed by SMP.
  329          * Until it gets it's own internal protection, we go through in 
  330          * single file. This could hurt a machine bridging between two 
  331          * GB ethernets so it should be fixed. 
  332          * When it's fixed the process SHOULD NOT SLEEP, spinlocks please!
  333          * (and atomic ops )
  334          */
  335         NG_NODE_FORCE_WRITER(node);
  336         NG_NODE_SET_PRIVATE(node, priv);
  337         priv->node = node;
  338 
  339         /* Start timer; timer is always running while node is alive */
  340         ng_callout(&priv->timer, node, NULL, hz, ng_bridge_timeout, NULL, 0);
  341 
  342         /* Done */
  343         return (0);
  344 }
  345 
  346 /*
  347  * Method for attaching a new hook
  348  */
  349 static  int
  350 ng_bridge_newhook(node_p node, hook_p hook, const char *name)
  351 {
  352         const priv_p priv = NG_NODE_PRIVATE(node);
  353 
  354         /* Check for a link hook */
  355         if (strncmp(name, NG_BRIDGE_HOOK_LINK_PREFIX,
  356             strlen(NG_BRIDGE_HOOK_LINK_PREFIX)) == 0) {
  357                 const char *cp;
  358                 char *eptr;
  359                 u_long linkNum;
  360 
  361                 cp = name + strlen(NG_BRIDGE_HOOK_LINK_PREFIX);
  362                 if (!isdigit(*cp) || (cp[0] == '' && cp[1] != '\0'))
  363                         return (EINVAL);
  364                 linkNum = strtoul(cp, &eptr, 10);
  365                 if (*eptr != '\0' || linkNum >= NG_BRIDGE_MAX_LINKS)
  366                         return (EINVAL);
  367                 if (priv->links[linkNum] != NULL)
  368                         return (EISCONN);
  369                 priv->links[linkNum] = malloc(sizeof(*priv->links[linkNum]),
  370                     M_NETGRAPH_BRIDGE, M_NOWAIT|M_ZERO);
  371                 if (priv->links[linkNum] == NULL)
  372                         return (ENOMEM);
  373                 priv->links[linkNum]->hook = hook;
  374                 NG_HOOK_SET_PRIVATE(hook, (void *)linkNum);
  375                 priv->numLinks++;
  376                 return (0);
  377         }
  378 
  379         /* Unknown hook name */
  380         return (EINVAL);
  381 }
  382 
  383 /*
  384  * Receive a control message
  385  */
  386 static int
  387 ng_bridge_rcvmsg(node_p node, item_p item, hook_p lasthook)
  388 {
  389         const priv_p priv = NG_NODE_PRIVATE(node);
  390         struct ng_mesg *resp = NULL;
  391         int error = 0;
  392         struct ng_mesg *msg;
  393 
  394         NGI_GET_MSG(item, msg);
  395         switch (msg->header.typecookie) {
  396         case NGM_BRIDGE_COOKIE:
  397                 switch (msg->header.cmd) {
  398                 case NGM_BRIDGE_GET_CONFIG:
  399                     {
  400                         struct ng_bridge_config *conf;
  401 
  402                         NG_MKRESPONSE(resp, msg,
  403                             sizeof(struct ng_bridge_config), M_NOWAIT);
  404                         if (resp == NULL) {
  405                                 error = ENOMEM;
  406                                 break;
  407                         }
  408                         conf = (struct ng_bridge_config *)resp->data;
  409                         *conf = priv->conf;     /* no sanity checking needed */
  410                         break;
  411                     }
  412                 case NGM_BRIDGE_SET_CONFIG:
  413                     {
  414                         struct ng_bridge_config *conf;
  415                         int i;
  416 
  417                         if (msg->header.arglen
  418                             != sizeof(struct ng_bridge_config)) {
  419                                 error = EINVAL;
  420                                 break;
  421                         }
  422                         conf = (struct ng_bridge_config *)msg->data;
  423                         priv->conf = *conf;
  424                         for (i = 0; i < NG_BRIDGE_MAX_LINKS; i++)
  425                                 priv->conf.ipfw[i] = !!priv->conf.ipfw[i];
  426                         break;
  427                     }
  428                 case NGM_BRIDGE_RESET:
  429                     {
  430                         int i;
  431 
  432                         /* Flush all entries in the hash table */
  433                         ng_bridge_remove_hosts(priv, -1);
  434 
  435                         /* Reset all loop detection counters and stats */
  436                         for (i = 0; i < NG_BRIDGE_MAX_LINKS; i++) {
  437                                 if (priv->links[i] == NULL)
  438                                         continue;
  439                                 priv->links[i]->loopCount = 0;
  440                                 bzero(&priv->links[i]->stats,
  441                                     sizeof(priv->links[i]->stats));
  442                         }
  443                         break;
  444                     }
  445                 case NGM_BRIDGE_GET_STATS:
  446                 case NGM_BRIDGE_CLR_STATS:
  447                 case NGM_BRIDGE_GETCLR_STATS:
  448                     {
  449                         struct ng_bridge_link *link;
  450                         int linkNum;
  451 
  452                         /* Get link number */
  453                         if (msg->header.arglen != sizeof(u_int32_t)) {
  454                                 error = EINVAL;
  455                                 break;
  456                         }
  457                         linkNum = *((u_int32_t *)msg->data);
  458                         if (linkNum < 0 || linkNum >= NG_BRIDGE_MAX_LINKS) {
  459                                 error = EINVAL;
  460                                 break;
  461                         }
  462                         if ((link = priv->links[linkNum]) == NULL) {
  463                                 error = ENOTCONN;
  464                                 break;
  465                         }
  466 
  467                         /* Get/clear stats */
  468                         if (msg->header.cmd != NGM_BRIDGE_CLR_STATS) {
  469                                 NG_MKRESPONSE(resp, msg,
  470                                     sizeof(link->stats), M_NOWAIT);
  471                                 if (resp == NULL) {
  472                                         error = ENOMEM;
  473                                         break;
  474                                 }
  475                                 bcopy(&link->stats,
  476                                     resp->data, sizeof(link->stats));
  477                         }
  478                         if (msg->header.cmd != NGM_BRIDGE_GET_STATS)
  479                                 bzero(&link->stats, sizeof(link->stats));
  480                         break;
  481                     }
  482                 case NGM_BRIDGE_GET_TABLE:
  483                     {
  484                         struct ng_bridge_host_ary *ary;
  485                         struct ng_bridge_hent *hent;
  486                         int i = 0, bucket;
  487 
  488                         NG_MKRESPONSE(resp, msg, sizeof(*ary)
  489                             + (priv->numHosts * sizeof(*ary->hosts)), M_NOWAIT);
  490                         if (resp == NULL) {
  491                                 error = ENOMEM;
  492                                 break;
  493                         }
  494                         ary = (struct ng_bridge_host_ary *)resp->data;
  495                         ary->numHosts = priv->numHosts;
  496                         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  497                                 SLIST_FOREACH(hent, &priv->tab[bucket], next)
  498                                         ary->hosts[i++] = hent->host;
  499                         }
  500                         break;
  501                     }
  502                 case NGM_BRIDGE_SET_PERSISTENT:
  503                     {
  504                         priv->persistent = 1;
  505                         break;
  506                     }
  507                 default:
  508                         error = EINVAL;
  509                         break;
  510                 }
  511                 break;
  512         default:
  513                 error = EINVAL;
  514                 break;
  515         }
  516 
  517         /* Done */
  518         NG_RESPOND_MSG(error, node, item, resp);
  519         NG_FREE_MSG(msg);
  520         return (error);
  521 }
  522 
  523 /*
  524  * Receive data on a hook
  525  */
  526 static int
  527 ng_bridge_rcvdata(hook_p hook, item_p item)
  528 {
  529         const node_p node = NG_HOOK_NODE(hook);
  530         const priv_p priv = NG_NODE_PRIVATE(node);
  531         struct ng_bridge_host *host;
  532         struct ng_bridge_link *link;
  533         struct ether_header *eh;
  534         int error = 0, linkNum, linksSeen;
  535         int manycast;
  536         struct mbuf *m;
  537         struct ng_bridge_link *firstLink;
  538 
  539         NGI_GET_M(item, m);
  540         /* Get link number */
  541         linkNum = (intptr_t)NG_HOOK_PRIVATE(hook);
  542         KASSERT(linkNum >= 0 && linkNum < NG_BRIDGE_MAX_LINKS,
  543             ("%s: linkNum=%u", __func__, linkNum));
  544         link = priv->links[linkNum];
  545         KASSERT(link != NULL, ("%s: link%d null", __func__, linkNum));
  546 
  547         /* Sanity check packet and pull up header */
  548         if (m->m_pkthdr.len < ETHER_HDR_LEN) {
  549                 link->stats.recvRunts++;
  550                 NG_FREE_ITEM(item);
  551                 NG_FREE_M(m);
  552                 return (EINVAL);
  553         }
  554         if (m->m_len < ETHER_HDR_LEN && !(m = m_pullup(m, ETHER_HDR_LEN))) {
  555                 link->stats.memoryFailures++;
  556                 NG_FREE_ITEM(item);
  557                 return (ENOBUFS);
  558         }
  559         eh = mtod(m, struct ether_header *);
  560         if ((eh->ether_shost[0] & 1) != 0) {
  561                 link->stats.recvInvalid++;
  562                 NG_FREE_ITEM(item);
  563                 NG_FREE_M(m);
  564                 return (EINVAL);
  565         }
  566 
  567         /* Is link disabled due to a loopback condition? */
  568         if (link->loopCount != 0) {
  569                 link->stats.loopDrops++;
  570                 NG_FREE_ITEM(item);
  571                 NG_FREE_M(m);
  572                 return (ELOOP);         /* XXX is this an appropriate error? */
  573         }
  574 
  575         /* Update stats */
  576         link->stats.recvPackets++;
  577         link->stats.recvOctets += m->m_pkthdr.len;
  578         if ((manycast = (eh->ether_dhost[0] & 1)) != 0) {
  579                 if (ETHER_EQUAL(eh->ether_dhost, ng_bridge_bcast_addr)) {
  580                         link->stats.recvBroadcasts++;
  581                         manycast = 2;
  582                 } else
  583                         link->stats.recvMulticasts++;
  584         }
  585 
  586         /* Look up packet's source Ethernet address in hashtable */
  587         if ((host = ng_bridge_get(priv, eh->ether_shost)) != NULL) {
  588 
  589                 /* Update time since last heard from this host */
  590                 host->staleness = 0;
  591 
  592                 /* Did host jump to a different link? */
  593                 if (host->linkNum != linkNum) {
  594 
  595                         /*
  596                          * If the host's old link was recently established
  597                          * on the old link and it's already jumped to a new
  598                          * link, declare a loopback condition.
  599                          */
  600                         if (host->age < priv->conf.minStableAge) {
  601 
  602                                 /* Log the problem */
  603                                 if (priv->conf.debugLevel >= 2) {
  604                                         struct ifnet *ifp = m->m_pkthdr.rcvif;
  605                                         char suffix[32];
  606 
  607                                         if (ifp != NULL)
  608                                                 snprintf(suffix, sizeof(suffix),
  609                                                     " (%s)", ifp->if_xname);
  610                                         else
  611                                                 *suffix = '\0';
  612                                         log(LOG_WARNING, "ng_bridge: %s:"
  613                                             " loopback detected on %s%s\n",
  614                                             ng_bridge_nodename(node),
  615                                             NG_HOOK_NAME(hook), suffix);
  616                                 }
  617 
  618                                 /* Mark link as linka non grata */
  619                                 link->loopCount = priv->conf.loopTimeout;
  620                                 link->stats.loopDetects++;
  621 
  622                                 /* Forget all hosts on this link */
  623                                 ng_bridge_remove_hosts(priv, linkNum);
  624 
  625                                 /* Drop packet */
  626                                 link->stats.loopDrops++;
  627                                 NG_FREE_ITEM(item);
  628                                 NG_FREE_M(m);
  629                                 return (ELOOP);         /* XXX appropriate? */
  630                         }
  631 
  632                         /* Move host over to new link */
  633                         host->linkNum = linkNum;
  634                         host->age = 0;
  635                 }
  636         } else {
  637                 if (!ng_bridge_put(priv, eh->ether_shost, linkNum)) {
  638                         link->stats.memoryFailures++;
  639                         NG_FREE_ITEM(item);
  640                         NG_FREE_M(m);
  641                         return (ENOMEM);
  642                 }
  643         }
  644 
  645         /* Run packet through ipfw processing, if enabled */
  646 #if 0
  647         if (priv->conf.ipfw[linkNum] && V_fw_enable && V_ip_fw_chk_ptr != NULL) {
  648                 /* XXX not implemented yet */
  649         }
  650 #endif
  651 
  652         /*
  653          * If unicast and destination host known, deliver to host's link,
  654          * unless it is the same link as the packet came in on.
  655          */
  656         if (!manycast) {
  657 
  658                 /* Determine packet destination link */
  659                 if ((host = ng_bridge_get(priv, eh->ether_dhost)) != NULL) {
  660                         struct ng_bridge_link *const destLink
  661                             = priv->links[host->linkNum];
  662 
  663                         /* If destination same as incoming link, do nothing */
  664                         KASSERT(destLink != NULL,
  665                             ("%s: link%d null", __func__, host->linkNum));
  666                         if (destLink == link) {
  667                                 NG_FREE_ITEM(item);
  668                                 NG_FREE_M(m);
  669                                 return (0);
  670                         }
  671 
  672                         /* Deliver packet out the destination link */
  673                         destLink->stats.xmitPackets++;
  674                         destLink->stats.xmitOctets += m->m_pkthdr.len;
  675                         NG_FWD_NEW_DATA(error, item, destLink->hook, m);
  676                         return (error);
  677                 }
  678 
  679                 /* Destination host is not known */
  680                 link->stats.recvUnknown++;
  681         }
  682 
  683         /* Distribute unknown, multicast, broadcast pkts to all other links */
  684         firstLink = NULL;
  685         for (linkNum = linksSeen = 0; linksSeen <= priv->numLinks; linkNum++) {
  686                 struct ng_bridge_link *destLink;
  687                 struct mbuf *m2 = NULL;
  688 
  689                 /*
  690                  * If we have checked all the links then now
  691                  * send the original on its reserved link
  692                  */
  693                 if (linksSeen == priv->numLinks) {
  694                         /* If we never saw a good link, leave. */
  695                         if (firstLink == NULL) {
  696                                 NG_FREE_ITEM(item);
  697                                 NG_FREE_M(m);
  698                                 return (0);
  699                         }       
  700                         destLink = firstLink;
  701                 } else {
  702                         destLink = priv->links[linkNum];
  703                         if (destLink != NULL)
  704                                 linksSeen++;
  705                         /* Skip incoming link and disconnected links */
  706                         if (destLink == NULL || destLink == link) {
  707                                 continue;
  708                         }
  709                         if (firstLink == NULL) {
  710                                 /*
  711                                  * This is the first usable link we have found.
  712                                  * Reserve it for the originals.
  713                                  * If we never find another we save a copy.
  714                                  */
  715                                 firstLink = destLink;
  716                                 continue;
  717                         }
  718 
  719                         /*
  720                          * It's usable link but not the reserved (first) one.
  721                          * Copy mbuf info for sending.
  722                          */
  723                         m2 = m_dup(m, M_NOWAIT);        /* XXX m_copypacket() */
  724                         if (m2 == NULL) {
  725                                 link->stats.memoryFailures++;
  726                                 NG_FREE_ITEM(item);
  727                                 NG_FREE_M(m);
  728                                 return (ENOBUFS);
  729                         }
  730                 }
  731 
  732                 /* Update stats */
  733                 destLink->stats.xmitPackets++;
  734                 destLink->stats.xmitOctets += m->m_pkthdr.len;
  735                 switch (manycast) {
  736                 case 0:                                 /* unicast */
  737                         break;
  738                 case 1:                                 /* multicast */
  739                         destLink->stats.xmitMulticasts++;
  740                         break;
  741                 case 2:                                 /* broadcast */
  742                         destLink->stats.xmitBroadcasts++;
  743                         break;
  744                 }
  745 
  746                 /* Send packet */
  747                 if (destLink == firstLink) { 
  748                         /*
  749                          * If we've sent all the others, send the original
  750                          * on the first link we found.
  751                          */
  752                         NG_FWD_NEW_DATA(error, item, destLink->hook, m);
  753                         break; /* always done last - not really needed. */
  754                 } else {
  755                         NG_SEND_DATA_ONLY(error, destLink->hook, m2);
  756                 }
  757         }
  758         return (error);
  759 }
  760 
  761 /*
  762  * Shutdown node
  763  */
  764 static int
  765 ng_bridge_shutdown(node_p node)
  766 {
  767         const priv_p priv = NG_NODE_PRIVATE(node);
  768 
  769         /*
  770          * Shut down everything including the timer.  Even if the
  771          * callout has already been dequeued and is about to be
  772          * run, ng_bridge_timeout() won't be fired as the node
  773          * is already marked NGF_INVALID, so we're safe to free
  774          * the node now.
  775          */
  776         KASSERT(priv->numLinks == 0 && priv->numHosts == 0,
  777             ("%s: numLinks=%d numHosts=%d",
  778             __func__, priv->numLinks, priv->numHosts));
  779         ng_uncallout(&priv->timer, node);
  780         NG_NODE_SET_PRIVATE(node, NULL);
  781         NG_NODE_UNREF(node);
  782         free(priv->tab, M_NETGRAPH_BRIDGE);
  783         free(priv, M_NETGRAPH_BRIDGE);
  784         return (0);
  785 }
  786 
  787 /*
  788  * Hook disconnection.
  789  */
  790 static int
  791 ng_bridge_disconnect(hook_p hook)
  792 {
  793         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  794         int linkNum;
  795 
  796         /* Get link number */
  797         linkNum = (intptr_t)NG_HOOK_PRIVATE(hook);
  798         KASSERT(linkNum >= 0 && linkNum < NG_BRIDGE_MAX_LINKS,
  799             ("%s: linkNum=%u", __func__, linkNum));
  800 
  801         /* Remove all hosts associated with this link */
  802         ng_bridge_remove_hosts(priv, linkNum);
  803 
  804         /* Free associated link information */
  805         KASSERT(priv->links[linkNum] != NULL, ("%s: no link", __func__));
  806         free(priv->links[linkNum], M_NETGRAPH_BRIDGE);
  807         priv->links[linkNum] = NULL;
  808         priv->numLinks--;
  809 
  810         /* If no more hooks, go away */
  811         if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
  812             && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))
  813             && !priv->persistent) {
  814                 ng_rmnode_self(NG_HOOK_NODE(hook));
  815         }
  816         return (0);
  817 }
  818 
  819 /******************************************************************
  820                     HASH TABLE FUNCTIONS
  821 ******************************************************************/
  822 
  823 /*
  824  * Hash algorithm
  825  */
  826 #define HASH(addr,mask)         ( (((const u_int16_t *)(addr))[0]       \
  827                                  ^ ((const u_int16_t *)(addr))[1]       \
  828                                  ^ ((const u_int16_t *)(addr))[2]) & (mask) )
  829 
  830 /*
  831  * Find a host entry in the table.
  832  */
  833 static struct ng_bridge_host *
  834 ng_bridge_get(priv_p priv, const u_char *addr)
  835 {
  836         const int bucket = HASH(addr, priv->hashMask);
  837         struct ng_bridge_hent *hent;
  838 
  839         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  840                 if (ETHER_EQUAL(hent->host.addr, addr))
  841                         return (&hent->host);
  842         }
  843         return (NULL);
  844 }
  845 
  846 /*
  847  * Add a new host entry to the table. This assumes the host doesn't
  848  * already exist in the table. Returns 1 on success, 0 if there
  849  * was a memory allocation failure.
  850  */
  851 static int
  852 ng_bridge_put(priv_p priv, const u_char *addr, int linkNum)
  853 {
  854         const int bucket = HASH(addr, priv->hashMask);
  855         struct ng_bridge_hent *hent;
  856 
  857 #ifdef INVARIANTS
  858         /* Assert that entry does not already exist in hashtable */
  859         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  860                 KASSERT(!ETHER_EQUAL(hent->host.addr, addr),
  861                     ("%s: entry %6D exists in table", __func__, addr, ":"));
  862         }
  863 #endif
  864 
  865         /* Allocate and initialize new hashtable entry */
  866         hent = malloc(sizeof(*hent), M_NETGRAPH_BRIDGE, M_NOWAIT);
  867         if (hent == NULL)
  868                 return (0);
  869         bcopy(addr, hent->host.addr, ETHER_ADDR_LEN);
  870         hent->host.linkNum = linkNum;
  871         hent->host.staleness = 0;
  872         hent->host.age = 0;
  873 
  874         /* Add new element to hash bucket */
  875         SLIST_INSERT_HEAD(&priv->tab[bucket], hent, next);
  876         priv->numHosts++;
  877 
  878         /* Resize table if necessary */
  879         ng_bridge_rehash(priv);
  880         return (1);
  881 }
  882 
  883 /*
  884  * Resize the hash table. We try to maintain the number of buckets
  885  * such that the load factor is in the range 0.25 to 1.0.
  886  *
  887  * If we can't get the new memory then we silently fail. This is OK
  888  * because things will still work and we'll try again soon anyway.
  889  */
  890 static void
  891 ng_bridge_rehash(priv_p priv)
  892 {
  893         struct ng_bridge_bucket *newTab;
  894         int oldBucket, newBucket;
  895         int newNumBuckets;
  896         u_int newMask;
  897 
  898         /* Is table too full or too empty? */
  899         if (priv->numHosts > priv->numBuckets
  900             && (priv->numBuckets << 1) <= MAX_BUCKETS)
  901                 newNumBuckets = priv->numBuckets << 1;
  902         else if (priv->numHosts < (priv->numBuckets >> 2)
  903             && (priv->numBuckets >> 2) >= MIN_BUCKETS)
  904                 newNumBuckets = priv->numBuckets >> 2;
  905         else
  906                 return;
  907         newMask = newNumBuckets - 1;
  908 
  909         /* Allocate and initialize new table */
  910         newTab = malloc(newNumBuckets * sizeof(*newTab),
  911             M_NETGRAPH_BRIDGE, M_NOWAIT | M_ZERO);
  912         if (newTab == NULL)
  913                 return;
  914 
  915         /* Move all entries from old table to new table */
  916         for (oldBucket = 0; oldBucket < priv->numBuckets; oldBucket++) {
  917                 struct ng_bridge_bucket *const oldList = &priv->tab[oldBucket];
  918 
  919                 while (!SLIST_EMPTY(oldList)) {
  920                         struct ng_bridge_hent *const hent
  921                             = SLIST_FIRST(oldList);
  922 
  923                         SLIST_REMOVE_HEAD(oldList, next);
  924                         newBucket = HASH(hent->host.addr, newMask);
  925                         SLIST_INSERT_HEAD(&newTab[newBucket], hent, next);
  926                 }
  927         }
  928 
  929         /* Replace old table with new one */
  930         if (priv->conf.debugLevel >= 3) {
  931                 log(LOG_INFO, "ng_bridge: %s: table size %d -> %d\n",
  932                     ng_bridge_nodename(priv->node),
  933                     priv->numBuckets, newNumBuckets);
  934         }
  935         free(priv->tab, M_NETGRAPH_BRIDGE);
  936         priv->numBuckets = newNumBuckets;
  937         priv->hashMask = newMask;
  938         priv->tab = newTab;
  939         return;
  940 }
  941 
  942 /******************************************************************
  943                     MISC FUNCTIONS
  944 ******************************************************************/
  945 
  946 /*
  947  * Remove all hosts associated with a specific link from the hashtable.
  948  * If linkNum == -1, then remove all hosts in the table.
  949  */
  950 static void
  951 ng_bridge_remove_hosts(priv_p priv, int linkNum)
  952 {
  953         int bucket;
  954 
  955         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  956                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
  957 
  958                 while (*hptr != NULL) {
  959                         struct ng_bridge_hent *const hent = *hptr;
  960 
  961                         if (linkNum == -1 || hent->host.linkNum == linkNum) {
  962                                 *hptr = SLIST_NEXT(hent, next);
  963                                 free(hent, M_NETGRAPH_BRIDGE);
  964                                 priv->numHosts--;
  965                         } else
  966                                 hptr = &SLIST_NEXT(hent, next);
  967                 }
  968         }
  969 }
  970 
  971 /*
  972  * Handle our once-per-second timeout event. We do two things:
  973  * we decrement link->loopCount for those links being muted due to
  974  * a detected loopback condition, and we remove any hosts from
  975  * the hashtable whom we haven't heard from in a long while.
  976  */
  977 static void
  978 ng_bridge_timeout(node_p node, hook_p hook, void *arg1, int arg2)
  979 {
  980         const priv_p priv = NG_NODE_PRIVATE(node);
  981         int bucket;
  982         int counter = 0;
  983         int linkNum;
  984 
  985         /* Update host time counters and remove stale entries */
  986         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  987                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
  988 
  989                 while (*hptr != NULL) {
  990                         struct ng_bridge_hent *const hent = *hptr;
  991 
  992                         /* Make sure host's link really exists */
  993                         KASSERT(priv->links[hent->host.linkNum] != NULL,
  994                             ("%s: host %6D on nonexistent link %d\n",
  995                             __func__, hent->host.addr, ":",
  996                             hent->host.linkNum));
  997 
  998                         /* Remove hosts we haven't heard from in a while */
  999                         if (++hent->host.staleness >= priv->conf.maxStaleness) {
 1000                                 *hptr = SLIST_NEXT(hent, next);
 1001                                 free(hent, M_NETGRAPH_BRIDGE);
 1002                                 priv->numHosts--;
 1003                         } else {
 1004                                 if (hent->host.age < 0xffff)
 1005                                         hent->host.age++;
 1006                                 hptr = &SLIST_NEXT(hent, next);
 1007                                 counter++;
 1008                         }
 1009                 }
 1010         }
 1011         KASSERT(priv->numHosts == counter,
 1012             ("%s: hosts: %d != %d", __func__, priv->numHosts, counter));
 1013 
 1014         /* Decrease table size if necessary */
 1015         ng_bridge_rehash(priv);
 1016 
 1017         /* Decrease loop counter on muted looped back links */
 1018         for (counter = linkNum = 0; linkNum < NG_BRIDGE_MAX_LINKS; linkNum++) {
 1019                 struct ng_bridge_link *const link = priv->links[linkNum];
 1020 
 1021                 if (link != NULL) {
 1022                         if (link->loopCount != 0) {
 1023                                 link->loopCount--;
 1024                                 if (link->loopCount == 0
 1025                                     && priv->conf.debugLevel >= 2) {
 1026                                         log(LOG_INFO, "ng_bridge: %s:"
 1027                                             " restoring looped back link%d\n",
 1028                                             ng_bridge_nodename(node), linkNum);
 1029                                 }
 1030                         }
 1031                         counter++;
 1032                 }
 1033         }
 1034         KASSERT(priv->numLinks == counter,
 1035             ("%s: links: %d != %d", __func__, priv->numLinks, counter));
 1036 
 1037         /* Register a new timeout, keeping the existing node reference */
 1038         ng_callout(&priv->timer, node, NULL, hz, ng_bridge_timeout, NULL, 0);
 1039 }
 1040 
 1041 /*
 1042  * Return node's "name", even if it doesn't have one.
 1043  */
 1044 static const char *
 1045 ng_bridge_nodename(node_p node)
 1046 {
 1047         static char name[NG_NODESIZ];
 1048 
 1049         if (NG_NODE_HAS_NAME(node))
 1050                 snprintf(name, sizeof(name), "%s", NG_NODE_NAME(node));
 1051         else
 1052                 snprintf(name, sizeof(name), "[%x]", ng_node2ID(node));
 1053         return name;
 1054 }
 1055 

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