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 /*
    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: releng/5.3/sys/netgraph/ng_bridge.c 136588 2004-10-16 08:43:07Z cvs2svn $
   40  */
   41 
   42 /*
   43  * ng_bridge(4) netgraph node type
   44  *
   45  * The node performs standard intelligent Ethernet bridging over
   46  * each of its connected hooks, or links.  A simple loop detection
   47  * algorithm is included which disables a link for priv->conf.loopTimeout
   48  * seconds when a host is seen to have jumped from one link to
   49  * another within priv->conf.minStableAge seconds.
   50  *
   51  * We keep a hashtable that maps Ethernet addresses to host info,
   52  * which is contained in struct ng_bridge_host's. These structures
   53  * tell us on which link the host may be found. A host's entry will
   54  * expire after priv->conf.maxStaleness seconds.
   55  *
   56  * This node is optimzed for stable networks, where machines jump
   57  * from one port to the other only rarely.
   58  */
   59 
   60 #include <sys/param.h>
   61 #include <sys/systm.h>
   62 #include <sys/kernel.h>
   63 #include <sys/malloc.h>
   64 #include <sys/mbuf.h>
   65 #include <sys/errno.h>
   66 #include <sys/syslog.h>
   67 #include <sys/socket.h>
   68 #include <sys/ctype.h>
   69 
   70 #include <net/if.h>
   71 #include <net/ethernet.h>
   72 
   73 #include <netinet/in.h>
   74 #include <netinet/ip_fw.h>
   75 
   76 #include <netgraph/ng_message.h>
   77 #include <netgraph/netgraph.h>
   78 #include <netgraph/ng_parse.h>
   79 #include <netgraph/ng_bridge.h>
   80 
   81 #ifdef NG_SEPARATE_MALLOC
   82 MALLOC_DEFINE(M_NETGRAPH_BRIDGE, "netgraph_bridge", "netgraph bridge node ");
   83 #else
   84 #define M_NETGRAPH_BRIDGE M_NETGRAPH
   85 #endif
   86 
   87 /* Per-link private data */
   88 struct ng_bridge_link {
   89         hook_p                          hook;           /* netgraph hook */
   90         u_int16_t                       loopCount;      /* loop ignore timer */
   91         struct ng_bridge_link_stats     stats;          /* link stats */
   92 };
   93 
   94 /* Per-node private data */
   95 struct ng_bridge_private {
   96         struct ng_bridge_bucket *tab;           /* hash table bucket array */
   97         struct ng_bridge_link   *links[NG_BRIDGE_MAX_LINKS];
   98         struct ng_bridge_config conf;           /* node configuration */
   99         node_p                  node;           /* netgraph node */
  100         u_int                   numHosts;       /* num entries in table */
  101         u_int                   numBuckets;     /* num buckets in table */
  102         u_int                   hashMask;       /* numBuckets - 1 */
  103         int                     numLinks;       /* num connected links */
  104         struct callout          timer;          /* one second periodic timer */
  105 };
  106 typedef struct ng_bridge_private *priv_p;
  107 
  108 /* Information about a host, stored in a hash table entry */
  109 struct ng_bridge_hent {
  110         struct ng_bridge_host           host;   /* actual host info */
  111         SLIST_ENTRY(ng_bridge_hent)     next;   /* next entry in bucket */
  112 };
  113 
  114 /* Hash table bucket declaration */
  115 SLIST_HEAD(ng_bridge_bucket, ng_bridge_hent);
  116 
  117 /* Netgraph node methods */
  118 static ng_constructor_t ng_bridge_constructor;
  119 static ng_rcvmsg_t      ng_bridge_rcvmsg;
  120 static ng_shutdown_t    ng_bridge_shutdown;
  121 static ng_newhook_t     ng_bridge_newhook;
  122 static ng_rcvdata_t     ng_bridge_rcvdata;
  123 static ng_disconnect_t  ng_bridge_disconnect;
  124 
  125 /* Other internal functions */
  126 static struct   ng_bridge_host *ng_bridge_get(priv_p priv, const u_char *addr);
  127 static int      ng_bridge_put(priv_p priv, const u_char *addr, int linkNum);
  128 static void     ng_bridge_rehash(priv_p priv);
  129 static void     ng_bridge_remove_hosts(priv_p priv, int linkNum);
  130 static void     ng_bridge_timeout(void *arg);
  131 static const    char *ng_bridge_nodename(node_p node);
  132 
  133 /* Ethernet broadcast */
  134 static const u_char ng_bridge_bcast_addr[ETHER_ADDR_LEN] =
  135     { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
  136 
  137 /* Store each hook's link number in the private field */
  138 #define LINK_NUM(hook)          (*(u_int16_t *)(&(hook)->private))
  139 
  140 /* Compare Ethernet addresses using 32 and 16 bit words instead of bytewise */
  141 #define ETHER_EQUAL(a,b)        (((const u_int32_t *)(a))[0] \
  142                                         == ((const u_int32_t *)(b))[0] \
  143                                     && ((const u_int16_t *)(a))[2] \
  144                                         == ((const u_int16_t *)(b))[2])
  145 
  146 /* Minimum and maximum number of hash buckets. Must be a power of two. */
  147 #define MIN_BUCKETS             (1 << 5)        /* 32 */
  148 #define MAX_BUCKETS             (1 << 14)       /* 16384 */
  149 
  150 /* Configuration default values */
  151 #define DEFAULT_LOOP_TIMEOUT    60
  152 #define DEFAULT_MAX_STALENESS   (15 * 60)       /* same as ARP timeout */
  153 #define DEFAULT_MIN_STABLE_AGE  1
  154 
  155 /******************************************************************
  156                     NETGRAPH PARSE TYPES
  157 ******************************************************************/
  158 
  159 /*
  160  * How to determine the length of the table returned by NGM_BRIDGE_GET_TABLE
  161  */
  162 static int
  163 ng_bridge_getTableLength(const struct ng_parse_type *type,
  164         const u_char *start, const u_char *buf)
  165 {
  166         const struct ng_bridge_host_ary *const hary
  167             = (const struct ng_bridge_host_ary *)(buf - sizeof(u_int32_t));
  168 
  169         return hary->numHosts;
  170 }
  171 
  172 /* Parse type for struct ng_bridge_host_ary */
  173 static const struct ng_parse_struct_field ng_bridge_host_type_fields[]
  174         = NG_BRIDGE_HOST_TYPE_INFO(&ng_parse_enaddr_type);
  175 static const struct ng_parse_type ng_bridge_host_type = {
  176         &ng_parse_struct_type,
  177         &ng_bridge_host_type_fields
  178 };
  179 static const struct ng_parse_array_info ng_bridge_hary_type_info = {
  180         &ng_bridge_host_type,
  181         ng_bridge_getTableLength
  182 };
  183 static const struct ng_parse_type ng_bridge_hary_type = {
  184         &ng_parse_array_type,
  185         &ng_bridge_hary_type_info
  186 };
  187 static const struct ng_parse_struct_field ng_bridge_host_ary_type_fields[]
  188         = NG_BRIDGE_HOST_ARY_TYPE_INFO(&ng_bridge_hary_type);
  189 static const struct ng_parse_type ng_bridge_host_ary_type = {
  190         &ng_parse_struct_type,
  191         &ng_bridge_host_ary_type_fields
  192 };
  193 
  194 /* Parse type for struct ng_bridge_config */
  195 static const struct ng_parse_fixedarray_info ng_bridge_ipfwary_type_info = {
  196         &ng_parse_uint8_type,
  197         NG_BRIDGE_MAX_LINKS
  198 };
  199 static const struct ng_parse_type ng_bridge_ipfwary_type = {
  200         &ng_parse_fixedarray_type,
  201         &ng_bridge_ipfwary_type_info
  202 };
  203 static const struct ng_parse_struct_field ng_bridge_config_type_fields[]
  204         = NG_BRIDGE_CONFIG_TYPE_INFO(&ng_bridge_ipfwary_type);
  205 static const struct ng_parse_type ng_bridge_config_type = {
  206         &ng_parse_struct_type,
  207         &ng_bridge_config_type_fields
  208 };
  209 
  210 /* Parse type for struct ng_bridge_link_stat */
  211 static const struct ng_parse_struct_field ng_bridge_stats_type_fields[]
  212         = NG_BRIDGE_STATS_TYPE_INFO;
  213 static const struct ng_parse_type ng_bridge_stats_type = {
  214         &ng_parse_struct_type,
  215         &ng_bridge_stats_type_fields
  216 };
  217 
  218 /* List of commands and how to convert arguments to/from ASCII */
  219 static const struct ng_cmdlist ng_bridge_cmdlist[] = {
  220         {
  221           NGM_BRIDGE_COOKIE,
  222           NGM_BRIDGE_SET_CONFIG,
  223           "setconfig",
  224           &ng_bridge_config_type,
  225           NULL
  226         },
  227         {
  228           NGM_BRIDGE_COOKIE,
  229           NGM_BRIDGE_GET_CONFIG,
  230           "getconfig",
  231           NULL,
  232           &ng_bridge_config_type
  233         },
  234         {
  235           NGM_BRIDGE_COOKIE,
  236           NGM_BRIDGE_RESET,
  237           "reset",
  238           NULL,
  239           NULL
  240         },
  241         {
  242           NGM_BRIDGE_COOKIE,
  243           NGM_BRIDGE_GET_STATS,
  244           "getstats",
  245           &ng_parse_uint32_type,
  246           &ng_bridge_stats_type
  247         },
  248         {
  249           NGM_BRIDGE_COOKIE,
  250           NGM_BRIDGE_CLR_STATS,
  251           "clrstats",
  252           &ng_parse_uint32_type,
  253           NULL
  254         },
  255         {
  256           NGM_BRIDGE_COOKIE,
  257           NGM_BRIDGE_GETCLR_STATS,
  258           "getclrstats",
  259           &ng_parse_uint32_type,
  260           &ng_bridge_stats_type
  261         },
  262         {
  263           NGM_BRIDGE_COOKIE,
  264           NGM_BRIDGE_GET_TABLE,
  265           "gettable",
  266           NULL,
  267           &ng_bridge_host_ary_type
  268         },
  269         { 0 }
  270 };
  271 
  272 /* Node type descriptor */
  273 static struct ng_type ng_bridge_typestruct = {
  274         .version =      NG_ABI_VERSION,
  275         .name =         NG_BRIDGE_NODE_TYPE,
  276         .constructor =  ng_bridge_constructor,
  277         .rcvmsg =       ng_bridge_rcvmsg,
  278         .shutdown =     ng_bridge_shutdown,
  279         .newhook =      ng_bridge_newhook,
  280         .rcvdata =      ng_bridge_rcvdata,
  281         .disconnect =   ng_bridge_disconnect,
  282         .cmdlist =      ng_bridge_cmdlist,
  283 };
  284 NETGRAPH_INIT(bridge, &ng_bridge_typestruct);
  285 
  286 /******************************************************************
  287                     NETGRAPH NODE METHODS
  288 ******************************************************************/
  289 
  290 /*
  291  * Node constructor
  292  */
  293 static int
  294 ng_bridge_constructor(node_p node)
  295 {
  296         priv_p priv;
  297 
  298         /* Allocate and initialize private info */
  299         MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH_BRIDGE, M_NOWAIT | M_ZERO);
  300         if (priv == NULL)
  301                 return (ENOMEM);
  302         callout_init(&priv->timer, 0);
  303 
  304         /* Allocate and initialize hash table, etc. */
  305         MALLOC(priv->tab, struct ng_bridge_bucket *,
  306             MIN_BUCKETS * sizeof(*priv->tab), M_NETGRAPH_BRIDGE, M_NOWAIT | M_ZERO);
  307         if (priv->tab == NULL) {
  308                 FREE(priv, M_NETGRAPH_BRIDGE);
  309                 return (ENOMEM);
  310         }
  311         priv->numBuckets = MIN_BUCKETS;
  312         priv->hashMask = MIN_BUCKETS - 1;
  313         priv->conf.debugLevel = 1;
  314         priv->conf.loopTimeout = DEFAULT_LOOP_TIMEOUT;
  315         priv->conf.maxStaleness = DEFAULT_MAX_STALENESS;
  316         priv->conf.minStableAge = DEFAULT_MIN_STABLE_AGE;
  317 
  318         /*
  319          * This node has all kinds of stuff that could be screwed by SMP.
  320          * Until it gets it's own internal protection, we go through in 
  321          * single file. This could hurt a machine bridging beteen two 
  322          * GB ethernets so it should be fixed. 
  323          * When it's fixed the process SHOULD NOT SLEEP, spinlocks please!
  324          * (and atomic ops )
  325          */
  326         NG_NODE_FORCE_WRITER(node);
  327         NG_NODE_SET_PRIVATE(node, priv);
  328         priv->node = node;
  329 
  330         /* Start timer; timer is always running while node is alive */
  331         callout_reset(&priv->timer, hz, ng_bridge_timeout, priv->node);
  332 
  333         /* Done */
  334         return (0);
  335 }
  336 
  337 /*
  338  * Method for attaching a new hook
  339  */
  340 static  int
  341 ng_bridge_newhook(node_p node, hook_p hook, const char *name)
  342 {
  343         const priv_p priv = NG_NODE_PRIVATE(node);
  344 
  345         /* Check for a link hook */
  346         if (strncmp(name, NG_BRIDGE_HOOK_LINK_PREFIX,
  347             strlen(NG_BRIDGE_HOOK_LINK_PREFIX)) == 0) {
  348                 const char *cp;
  349                 char *eptr;
  350                 u_long linkNum;
  351 
  352                 cp = name + strlen(NG_BRIDGE_HOOK_LINK_PREFIX);
  353                 if (!isdigit(*cp) || (cp[0] == '' && cp[1] != '\0'))
  354                         return (EINVAL);
  355                 linkNum = strtoul(cp, &eptr, 10);
  356                 if (*eptr != '\0' || linkNum >= NG_BRIDGE_MAX_LINKS)
  357                         return (EINVAL);
  358                 if (priv->links[linkNum] != NULL)
  359                         return (EISCONN);
  360                 MALLOC(priv->links[linkNum], struct ng_bridge_link *,
  361                     sizeof(*priv->links[linkNum]), M_NETGRAPH_BRIDGE, M_NOWAIT|M_ZERO);
  362                 if (priv->links[linkNum] == NULL)
  363                         return (ENOMEM);
  364                 priv->links[linkNum]->hook = hook;
  365                 NG_HOOK_SET_PRIVATE(hook, (void *)linkNum);
  366                 priv->numLinks++;
  367                 return (0);
  368         }
  369 
  370         /* Unknown hook name */
  371         return (EINVAL);
  372 }
  373 
  374 /*
  375  * Receive a control message
  376  */
  377 static int
  378 ng_bridge_rcvmsg(node_p node, item_p item, hook_p lasthook)
  379 {
  380         const priv_p priv = NG_NODE_PRIVATE(node);
  381         struct ng_mesg *resp = NULL;
  382         int error = 0;
  383         struct ng_mesg *msg;
  384 
  385         NGI_GET_MSG(item, msg);
  386         switch (msg->header.typecookie) {
  387         case NGM_BRIDGE_COOKIE:
  388                 switch (msg->header.cmd) {
  389                 case NGM_BRIDGE_GET_CONFIG:
  390                     {
  391                         struct ng_bridge_config *conf;
  392 
  393                         NG_MKRESPONSE(resp, msg,
  394                             sizeof(struct ng_bridge_config), M_NOWAIT);
  395                         if (resp == NULL) {
  396                                 error = ENOMEM;
  397                                 break;
  398                         }
  399                         conf = (struct ng_bridge_config *)resp->data;
  400                         *conf = priv->conf;     /* no sanity checking needed */
  401                         break;
  402                     }
  403                 case NGM_BRIDGE_SET_CONFIG:
  404                     {
  405                         struct ng_bridge_config *conf;
  406                         int i;
  407 
  408                         if (msg->header.arglen
  409                             != sizeof(struct ng_bridge_config)) {
  410                                 error = EINVAL;
  411                                 break;
  412                         }
  413                         conf = (struct ng_bridge_config *)msg->data;
  414                         priv->conf = *conf;
  415                         for (i = 0; i < NG_BRIDGE_MAX_LINKS; i++)
  416                                 priv->conf.ipfw[i] = !!priv->conf.ipfw[i];
  417                         break;
  418                     }
  419                 case NGM_BRIDGE_RESET:
  420                     {
  421                         int i;
  422 
  423                         /* Flush all entries in the hash table */
  424                         ng_bridge_remove_hosts(priv, -1);
  425 
  426                         /* Reset all loop detection counters and stats */
  427                         for (i = 0; i < NG_BRIDGE_MAX_LINKS; i++) {
  428                                 if (priv->links[i] == NULL)
  429                                         continue;
  430                                 priv->links[i]->loopCount = 0;
  431                                 bzero(&priv->links[i]->stats,
  432                                     sizeof(priv->links[i]->stats));
  433                         }
  434                         break;
  435                     }
  436                 case NGM_BRIDGE_GET_STATS:
  437                 case NGM_BRIDGE_CLR_STATS:
  438                 case NGM_BRIDGE_GETCLR_STATS:
  439                     {
  440                         struct ng_bridge_link *link;
  441                         int linkNum;
  442 
  443                         /* Get link number */
  444                         if (msg->header.arglen != sizeof(u_int32_t)) {
  445                                 error = EINVAL;
  446                                 break;
  447                         }
  448                         linkNum = *((u_int32_t *)msg->data);
  449                         if (linkNum < 0 || linkNum >= NG_BRIDGE_MAX_LINKS) {
  450                                 error = EINVAL;
  451                                 break;
  452                         }
  453                         if ((link = priv->links[linkNum]) == NULL) {
  454                                 error = ENOTCONN;
  455                                 break;
  456                         }
  457 
  458                         /* Get/clear stats */
  459                         if (msg->header.cmd != NGM_BRIDGE_CLR_STATS) {
  460                                 NG_MKRESPONSE(resp, msg,
  461                                     sizeof(link->stats), M_NOWAIT);
  462                                 if (resp == NULL) {
  463                                         error = ENOMEM;
  464                                         break;
  465                                 }
  466                                 bcopy(&link->stats,
  467                                     resp->data, sizeof(link->stats));
  468                         }
  469                         if (msg->header.cmd != NGM_BRIDGE_GET_STATS)
  470                                 bzero(&link->stats, sizeof(link->stats));
  471                         break;
  472                     }
  473                 case NGM_BRIDGE_GET_TABLE:
  474                     {
  475                         struct ng_bridge_host_ary *ary;
  476                         struct ng_bridge_hent *hent;
  477                         int i = 0, bucket;
  478 
  479                         NG_MKRESPONSE(resp, msg, sizeof(*ary)
  480                             + (priv->numHosts * sizeof(*ary->hosts)), M_NOWAIT);
  481                         if (resp == NULL) {
  482                                 error = ENOMEM;
  483                                 break;
  484                         }
  485                         ary = (struct ng_bridge_host_ary *)resp->data;
  486                         ary->numHosts = priv->numHosts;
  487                         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  488                                 SLIST_FOREACH(hent, &priv->tab[bucket], next)
  489                                         ary->hosts[i++] = hent->host;
  490                         }
  491                         break;
  492                     }
  493                 default:
  494                         error = EINVAL;
  495                         break;
  496                 }
  497                 break;
  498         default:
  499                 error = EINVAL;
  500                 break;
  501         }
  502 
  503         /* Done */
  504         NG_RESPOND_MSG(error, node, item, resp);
  505         NG_FREE_MSG(msg);
  506         return (error);
  507 }
  508 
  509 /*
  510  * Receive data on a hook
  511  */
  512 static int
  513 ng_bridge_rcvdata(hook_p hook, item_p item)
  514 {
  515         const node_p node = NG_HOOK_NODE(hook);
  516         const priv_p priv = NG_NODE_PRIVATE(node);
  517         struct ng_bridge_host *host;
  518         struct ng_bridge_link *link;
  519         struct ether_header *eh;
  520         int error = 0, linkNum, linksSeen;
  521         int manycast;
  522         struct mbuf *m;
  523         struct ng_bridge_link *firstLink;
  524 
  525         NGI_GET_M(item, m);
  526         /* Get link number */
  527         linkNum = (intptr_t)NG_HOOK_PRIVATE(hook);
  528         KASSERT(linkNum >= 0 && linkNum < NG_BRIDGE_MAX_LINKS,
  529             ("%s: linkNum=%u", __func__, linkNum));
  530         link = priv->links[linkNum];
  531         KASSERT(link != NULL, ("%s: link%d null", __func__, linkNum));
  532 
  533         /* Sanity check packet and pull up header */
  534         if (m->m_pkthdr.len < ETHER_HDR_LEN) {
  535                 link->stats.recvRunts++;
  536                 NG_FREE_ITEM(item);
  537                 NG_FREE_M(m);
  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_ITEM(item);
  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_ITEM(item);
  549                 NG_FREE_M(m);
  550                 return (EINVAL);
  551         }
  552 
  553         /* Is link disabled due to a loopback condition? */
  554         if (link->loopCount != 0) {
  555                 link->stats.loopDrops++;
  556                 NG_FREE_ITEM(item);
  557                 NG_FREE_M(m);
  558                 return (ELOOP);         /* XXX is this an appropriate error? */
  559         }
  560 
  561         /* Update stats */
  562         link->stats.recvPackets++;
  563         link->stats.recvOctets += m->m_pkthdr.len;
  564         if ((manycast = (eh->ether_dhost[0] & 1)) != 0) {
  565                 if (ETHER_EQUAL(eh->ether_dhost, ng_bridge_bcast_addr)) {
  566                         link->stats.recvBroadcasts++;
  567                         manycast = 2;
  568                 } else
  569                         link->stats.recvMulticasts++;
  570         }
  571 
  572         /* Look up packet's source Ethernet address in hashtable */
  573         if ((host = ng_bridge_get(priv, eh->ether_shost)) != NULL) {
  574 
  575                 /* Update time since last heard from this host */
  576                 host->staleness = 0;
  577 
  578                 /* Did host jump to a different link? */
  579                 if (host->linkNum != linkNum) {
  580 
  581                         /*
  582                          * If the host's old link was recently established
  583                          * on the old link and it's already jumped to a new
  584                          * link, declare a loopback condition.
  585                          */
  586                         if (host->age < priv->conf.minStableAge) {
  587 
  588                                 /* Log the problem */
  589                                 if (priv->conf.debugLevel >= 2) {
  590                                         struct ifnet *ifp = m->m_pkthdr.rcvif;
  591                                         char suffix[32];
  592 
  593                                         if (ifp != NULL)
  594                                                 snprintf(suffix, sizeof(suffix),
  595                                                     " (%s)", ifp->if_xname);
  596                                         else
  597                                                 *suffix = '\0';
  598                                         log(LOG_WARNING, "ng_bridge: %s:"
  599                                             " loopback detected on %s%s\n",
  600                                             ng_bridge_nodename(node),
  601                                             NG_HOOK_NAME(hook), suffix);
  602                                 }
  603 
  604                                 /* Mark link as linka non grata */
  605                                 link->loopCount = priv->conf.loopTimeout;
  606                                 link->stats.loopDetects++;
  607 
  608                                 /* Forget all hosts on this link */
  609                                 ng_bridge_remove_hosts(priv, linkNum);
  610 
  611                                 /* Drop packet */
  612                                 link->stats.loopDrops++;
  613                                 NG_FREE_ITEM(item);
  614                                 NG_FREE_M(m);
  615                                 return (ELOOP);         /* XXX appropriate? */
  616                         }
  617 
  618                         /* Move host over to new link */
  619                         host->linkNum = linkNum;
  620                         host->age = 0;
  621                 }
  622         } else {
  623                 if (!ng_bridge_put(priv, eh->ether_shost, linkNum)) {
  624                         link->stats.memoryFailures++;
  625                         NG_FREE_ITEM(item);
  626                         NG_FREE_M(m);
  627                         return (ENOMEM);
  628                 }
  629         }
  630 
  631         /* Run packet through ipfw processing, if enabled */
  632 #if 0
  633         if (priv->conf.ipfw[linkNum] && fw_enable && ip_fw_chk_ptr != NULL) {
  634                 /* XXX not implemented yet */
  635         }
  636 #endif
  637 
  638         /*
  639          * If unicast and destination host known, deliver to host's link,
  640          * unless it is the same link as the packet came in on.
  641          */
  642         if (!manycast) {
  643 
  644                 /* Determine packet destination link */
  645                 if ((host = ng_bridge_get(priv, eh->ether_dhost)) != NULL) {
  646                         struct ng_bridge_link *const destLink
  647                             = priv->links[host->linkNum];
  648 
  649                         /* If destination same as incoming link, do nothing */
  650                         KASSERT(destLink != NULL,
  651                             ("%s: link%d null", __func__, host->linkNum));
  652                         if (destLink == link) {
  653                                 NG_FREE_ITEM(item);
  654                                 NG_FREE_M(m);
  655                                 return (0);
  656                         }
  657 
  658                         /* Deliver packet out the destination link */
  659                         destLink->stats.xmitPackets++;
  660                         destLink->stats.xmitOctets += m->m_pkthdr.len;
  661                         NG_FWD_NEW_DATA(error, item, destLink->hook, m);
  662                         return (error);
  663                 }
  664 
  665                 /* Destination host is not known */
  666                 link->stats.recvUnknown++;
  667         }
  668 
  669         /* Distribute unknown, multicast, broadcast pkts to all other links */
  670         firstLink = NULL;
  671         for (linkNum = linksSeen = 0; linksSeen <= priv->numLinks; linkNum++) {
  672                 struct ng_bridge_link *destLink;
  673                 struct mbuf *m2 = NULL;
  674 
  675                 /*
  676                  * If we have checked all the links then now
  677                  * send the original on its reserved link
  678                  */
  679                 if (linksSeen == priv->numLinks) {
  680                         /* If we never saw a good link, leave. */
  681                         if (firstLink == NULL) {
  682                                 NG_FREE_ITEM(item);
  683                                 NG_FREE_M(m);
  684                                 return (0);
  685                         }       
  686                         destLink = firstLink;
  687                 } else {
  688                         destLink = priv->links[linkNum];
  689                         if (destLink != NULL)
  690                                 linksSeen++;
  691                         /* Skip incoming link and disconnected links */
  692                         if (destLink == NULL || destLink == link) {
  693                                 continue;
  694                         }
  695                         if (firstLink == NULL) {
  696                                 /*
  697                                  * This is the first usable link we have found.
  698                                  * Reserve it for the originals.
  699                                  * If we never find another we save a copy.
  700                                  */
  701                                 firstLink = destLink;
  702                                 continue;
  703                         }
  704 
  705                         /*
  706                          * It's usable link but not the reserved (first) one.
  707                          * Copy mbuf info for sending.
  708                          */
  709                         m2 = m_dup(m, M_DONTWAIT);      /* XXX m_copypacket() */
  710                         if (m2 == NULL) {
  711                                 link->stats.memoryFailures++;
  712                                 NG_FREE_ITEM(item);
  713                                 NG_FREE_M(m);
  714                                 return (ENOBUFS);
  715                         }
  716                 }
  717 
  718                 /* Update stats */
  719                 destLink->stats.xmitPackets++;
  720                 destLink->stats.xmitOctets += m->m_pkthdr.len;
  721                 switch (manycast) {
  722                 case 0:                                 /* unicast */
  723                         break;
  724                 case 1:                                 /* multicast */
  725                         destLink->stats.xmitMulticasts++;
  726                         break;
  727                 case 2:                                 /* broadcast */
  728                         destLink->stats.xmitBroadcasts++;
  729                         break;
  730                 }
  731 
  732                 /* Send packet */
  733                 if (destLink == firstLink) { 
  734                         /*
  735                          * If we've sent all the others, send the original
  736                          * on the first link we found.
  737                          */
  738                         NG_FWD_NEW_DATA(error, item, destLink->hook, m);
  739                         break; /* always done last - not really needed. */
  740                 } else {
  741                         NG_SEND_DATA_ONLY(error, destLink->hook, m2);
  742                 }
  743         }
  744         return (error);
  745 }
  746 
  747 /*
  748  * Shutdown node
  749  */
  750 static int
  751 ng_bridge_shutdown(node_p node)
  752 {
  753         const priv_p priv = NG_NODE_PRIVATE(node);
  754 
  755         /*
  756          * Shut down everything except the timer. There's no way to
  757          * avoid another possible timeout event (it may have already
  758          * been dequeued), so we can't free the node yet.
  759          */
  760         KASSERT(priv->numLinks == 0 && priv->numHosts == 0,
  761             ("%s: numLinks=%d numHosts=%d",
  762             __func__, priv->numLinks, priv->numHosts));
  763         FREE(priv->tab, M_NETGRAPH_BRIDGE);
  764 
  765         /* NGF_INVALID flag is now set so node will be freed at next timeout */
  766         return (0);
  767 }
  768 
  769 /*
  770  * Hook disconnection.
  771  */
  772 static int
  773 ng_bridge_disconnect(hook_p hook)
  774 {
  775         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  776         int linkNum;
  777 
  778         /* Get link number */
  779         linkNum = (intptr_t)NG_HOOK_PRIVATE(hook);
  780         KASSERT(linkNum >= 0 && linkNum < NG_BRIDGE_MAX_LINKS,
  781             ("%s: linkNum=%u", __func__, linkNum));
  782 
  783         /* Remove all hosts associated with this link */
  784         ng_bridge_remove_hosts(priv, linkNum);
  785 
  786         /* Free associated link information */
  787         KASSERT(priv->links[linkNum] != NULL, ("%s: no link", __func__));
  788         FREE(priv->links[linkNum], M_NETGRAPH_BRIDGE);
  789         priv->links[linkNum] = NULL;
  790         priv->numLinks--;
  791 
  792         /* If no more hooks, go away */
  793         if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
  794         && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) {
  795                 ng_rmnode_self(NG_HOOK_NODE(hook));
  796         }
  797         return (0);
  798 }
  799 
  800 /******************************************************************
  801                     HASH TABLE FUNCTIONS
  802 ******************************************************************/
  803 
  804 /*
  805  * Hash algorithm
  806  */
  807 #define HASH(addr,mask)         ( (((const u_int16_t *)(addr))[0]       \
  808                                  ^ ((const u_int16_t *)(addr))[1]       \
  809                                  ^ ((const u_int16_t *)(addr))[2]) & (mask) )
  810 
  811 /*
  812  * Find a host entry in the table.
  813  */
  814 static struct ng_bridge_host *
  815 ng_bridge_get(priv_p priv, const u_char *addr)
  816 {
  817         const int bucket = HASH(addr, priv->hashMask);
  818         struct ng_bridge_hent *hent;
  819 
  820         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  821                 if (ETHER_EQUAL(hent->host.addr, addr))
  822                         return (&hent->host);
  823         }
  824         return (NULL);
  825 }
  826 
  827 /*
  828  * Add a new host entry to the table. This assumes the host doesn't
  829  * already exist in the table. Returns 1 on success, 0 if there
  830  * was a memory allocation failure.
  831  */
  832 static int
  833 ng_bridge_put(priv_p priv, const u_char *addr, int linkNum)
  834 {
  835         const int bucket = HASH(addr, priv->hashMask);
  836         struct ng_bridge_hent *hent;
  837 
  838 #ifdef INVARIANTS
  839         /* Assert that entry does not already exist in hashtable */
  840         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  841                 KASSERT(!ETHER_EQUAL(hent->host.addr, addr),
  842                     ("%s: entry %6D exists in table", __func__, addr, ":"));
  843         }
  844 #endif
  845 
  846         /* Allocate and initialize new hashtable entry */
  847         MALLOC(hent, struct ng_bridge_hent *,
  848             sizeof(*hent), M_NETGRAPH_BRIDGE, M_NOWAIT);
  849         if (hent == NULL)
  850                 return (0);
  851         bcopy(addr, hent->host.addr, ETHER_ADDR_LEN);
  852         hent->host.linkNum = linkNum;
  853         hent->host.staleness = 0;
  854         hent->host.age = 0;
  855 
  856         /* Add new element to hash bucket */
  857         SLIST_INSERT_HEAD(&priv->tab[bucket], hent, next);
  858         priv->numHosts++;
  859 
  860         /* Resize table if necessary */
  861         ng_bridge_rehash(priv);
  862         return (1);
  863 }
  864 
  865 /*
  866  * Resize the hash table. We try to maintain the number of buckets
  867  * such that the load factor is in the range 0.25 to 1.0.
  868  *
  869  * If we can't get the new memory then we silently fail. This is OK
  870  * because things will still work and we'll try again soon anyway.
  871  */
  872 static void
  873 ng_bridge_rehash(priv_p priv)
  874 {
  875         struct ng_bridge_bucket *newTab;
  876         int oldBucket, newBucket;
  877         int newNumBuckets;
  878         u_int newMask;
  879 
  880         /* Is table too full or too empty? */
  881         if (priv->numHosts > priv->numBuckets
  882             && (priv->numBuckets << 1) <= MAX_BUCKETS)
  883                 newNumBuckets = priv->numBuckets << 1;
  884         else if (priv->numHosts < (priv->numBuckets >> 2)
  885             && (priv->numBuckets >> 2) >= MIN_BUCKETS)
  886                 newNumBuckets = priv->numBuckets >> 2;
  887         else
  888                 return;
  889         newMask = newNumBuckets - 1;
  890 
  891         /* Allocate and initialize new table */
  892         MALLOC(newTab, struct ng_bridge_bucket *,
  893             newNumBuckets * sizeof(*newTab), M_NETGRAPH_BRIDGE, M_NOWAIT | M_ZERO);
  894         if (newTab == NULL)
  895                 return;
  896 
  897         /* Move all entries from old table to new table */
  898         for (oldBucket = 0; oldBucket < priv->numBuckets; oldBucket++) {
  899                 struct ng_bridge_bucket *const oldList = &priv->tab[oldBucket];
  900 
  901                 while (!SLIST_EMPTY(oldList)) {
  902                         struct ng_bridge_hent *const hent
  903                             = SLIST_FIRST(oldList);
  904 
  905                         SLIST_REMOVE_HEAD(oldList, next);
  906                         newBucket = HASH(hent->host.addr, newMask);
  907                         SLIST_INSERT_HEAD(&newTab[newBucket], hent, next);
  908                 }
  909         }
  910 
  911         /* Replace old table with new one */
  912         if (priv->conf.debugLevel >= 3) {
  913                 log(LOG_INFO, "ng_bridge: %s: table size %d -> %d\n",
  914                     ng_bridge_nodename(priv->node),
  915                     priv->numBuckets, newNumBuckets);
  916         }
  917         FREE(priv->tab, M_NETGRAPH_BRIDGE);
  918         priv->numBuckets = newNumBuckets;
  919         priv->hashMask = newMask;
  920         priv->tab = newTab;
  921         return;
  922 }
  923 
  924 /******************************************************************
  925                     MISC FUNCTIONS
  926 ******************************************************************/
  927 
  928 /*
  929  * Remove all hosts associated with a specific link from the hashtable.
  930  * If linkNum == -1, then remove all hosts in the table.
  931  */
  932 static void
  933 ng_bridge_remove_hosts(priv_p priv, int linkNum)
  934 {
  935         int bucket;
  936 
  937         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  938                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
  939 
  940                 while (*hptr != NULL) {
  941                         struct ng_bridge_hent *const hent = *hptr;
  942 
  943                         if (linkNum == -1 || hent->host.linkNum == linkNum) {
  944                                 *hptr = SLIST_NEXT(hent, next);
  945                                 FREE(hent, M_NETGRAPH_BRIDGE);
  946                                 priv->numHosts--;
  947                         } else
  948                                 hptr = &SLIST_NEXT(hent, next);
  949                 }
  950         }
  951 }
  952 
  953 /*
  954  * Handle our once-per-second timeout event. We do two things:
  955  * we decrement link->loopCount for those links being muted due to
  956  * a detected loopback condition, and we remove any hosts from
  957  * the hashtable whom we haven't heard from in a long while.
  958  *
  959  * If the node has the NGF_INVALID flag set, our job is to kill it.
  960  */
  961 static void
  962 ng_bridge_timeout(void *arg)
  963 {
  964         const node_p node = arg;
  965         const priv_p priv = NG_NODE_PRIVATE(node);
  966         int s, bucket;
  967         int counter = 0;
  968         int linkNum;
  969 
  970         /* If node was shut down, this is the final lingering timeout */
  971         s = splnet();
  972         if (NG_NODE_NOT_VALID(node)) {
  973                 FREE(priv, M_NETGRAPH_BRIDGE);
  974                 NG_NODE_SET_PRIVATE(node, NULL);
  975                 NG_NODE_UNREF(node);
  976                 splx(s);
  977                 return;
  978         }
  979 
  980         /* Register a new timeout, keeping the existing node reference */
  981         callout_reset(&priv->timer, hz, ng_bridge_timeout, node);
  982 
  983         /* Update host time counters and remove stale entries */
  984         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  985                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
  986 
  987                 while (*hptr != NULL) {
  988                         struct ng_bridge_hent *const hent = *hptr;
  989 
  990                         /* Make sure host's link really exists */
  991                         KASSERT(priv->links[hent->host.linkNum] != NULL,
  992                             ("%s: host %6D on nonexistent link %d\n",
  993                             __func__, hent->host.addr, ":",
  994                             hent->host.linkNum));
  995 
  996                         /* Remove hosts we haven't heard from in a while */
  997                         if (++hent->host.staleness >= priv->conf.maxStaleness) {
  998                                 *hptr = SLIST_NEXT(hent, next);
  999                                 FREE(hent, M_NETGRAPH_BRIDGE);
 1000                                 priv->numHosts--;
 1001                         } else {
 1002                                 if (hent->host.age < 0xffff)
 1003                                         hent->host.age++;
 1004                                 hptr = &SLIST_NEXT(hent, next);
 1005                                 counter++;
 1006                         }
 1007                 }
 1008         }
 1009         KASSERT(priv->numHosts == counter,
 1010             ("%s: hosts: %d != %d", __func__, priv->numHosts, counter));
 1011 
 1012         /* Decrease table size if necessary */
 1013         ng_bridge_rehash(priv);
 1014 
 1015         /* Decrease loop counter on muted looped back links */
 1016         for (counter = linkNum = 0; linkNum < NG_BRIDGE_MAX_LINKS; linkNum++) {
 1017                 struct ng_bridge_link *const link = priv->links[linkNum];
 1018 
 1019                 if (link != NULL) {
 1020                         if (link->loopCount != 0) {
 1021                                 link->loopCount--;
 1022                                 if (link->loopCount == 0
 1023                                     && priv->conf.debugLevel >= 2) {
 1024                                         log(LOG_INFO, "ng_bridge: %s:"
 1025                                             " restoring looped back link%d\n",
 1026                                             ng_bridge_nodename(node), linkNum);
 1027                                 }
 1028                         }
 1029                         counter++;
 1030                 }
 1031         }
 1032         KASSERT(priv->numLinks == counter,
 1033             ("%s: links: %d != %d", __func__, priv->numLinks, counter));
 1034 
 1035         /* Done */
 1036         splx(s);
 1037 }
 1038 
 1039 /*
 1040  * Return node's "name", even if it doesn't have one.
 1041  */
 1042 static const char *
 1043 ng_bridge_nodename(node_p node)
 1044 {
 1045         static char name[NG_NODESIZ];
 1046 
 1047         if (NG_NODE_NAME(node) != NULL)
 1048                 snprintf(name, sizeof(name), "%s", NG_NODE_NAME(node));
 1049         else
 1050                 snprintf(name, sizeof(name), "[%x]", ng_node2ID(node));
 1051         return name;
 1052 }
 1053 

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