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  * Copyright (c) 2000 Whistle Communications, Inc.
    3  * All rights reserved.
    4  * 
    5  * Subject to the following obligations and disclaimer of warranty, use and
    6  * redistribution of this software, in source or object code forms, with or
    7  * without modifications are expressly permitted by Whistle Communications;
    8  * provided, however, that:
    9  * 1. Any and all reproductions of the source or object code must include the
   10  *    copyright notice above and the following disclaimer of warranties; and
   11  * 2. No rights are granted, in any manner or form, to use Whistle
   12  *    Communications, Inc. trademarks, including the mark "WHISTLE
   13  *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
   14  *    such appears in the above copyright notice or in the software.
   15  * 
   16  * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
   17  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
   18  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
   19  * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
   20  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
   21  * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
   22  * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
   23  * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
   24  * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
   25  * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
   26  * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
   27  * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
   28  * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
   29  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   30  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   31  * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
   32  * OF SUCH DAMAGE.
   33  *
   34  * Author: Archie Cobbs <archie@freebsd.org>
   35  *
   36  * $FreeBSD: stable/12/sys/netgraph/ng_bridge.c 357206 2020-01-28 17:39:03Z bz $
   37  */
   38 
   39 /*
   40  * ng_bridge(4) netgraph node type
   41  *
   42  * The node performs standard intelligent Ethernet bridging over
   43  * each of its connected hooks, or links.  A simple loop detection
   44  * algorithm is included which disables a link for priv->conf.loopTimeout
   45  * seconds when a host is seen to have jumped from one link to
   46  * another within priv->conf.minStableAge seconds.
   47  *
   48  * We keep a hashtable that maps Ethernet addresses to host info,
   49  * which is contained in struct ng_bridge_host's. These structures
   50  * tell us on which link the host may be found. A host's entry will
   51  * expire after priv->conf.maxStaleness seconds.
   52  *
   53  * This node is optimzed for stable networks, where machines jump
   54  * from one port to the other only rarely.
   55  */
   56 
   57 #include <sys/param.h>
   58 #include <sys/systm.h>
   59 #include <sys/kernel.h>
   60 #include <sys/lock.h>
   61 #include <sys/malloc.h>
   62 #include <sys/mbuf.h>
   63 #include <sys/errno.h>
   64 #include <sys/rwlock.h>
   65 #include <sys/syslog.h>
   66 #include <sys/socket.h>
   67 #include <sys/ctype.h>
   68 
   69 #include <net/if.h>
   70 #include <net/if_var.h>
   71 #include <net/ethernet.h>
   72 #include <net/vnet.h>
   73 
   74 #include <netinet/in.h>
   75 #if 0   /* not used yet */
   76 #include <netinet/ip_fw.h>
   77 #endif
   78 #include <netgraph/ng_message.h>
   79 #include <netgraph/netgraph.h>
   80 #include <netgraph/ng_parse.h>
   81 #include <netgraph/ng_bridge.h>
   82 
   83 #ifdef NG_SEPARATE_MALLOC
   84 static MALLOC_DEFINE(M_NETGRAPH_BRIDGE, "netgraph_bridge",
   85     "netgraph bridge node");
   86 #else
   87 #define M_NETGRAPH_BRIDGE M_NETGRAPH
   88 #endif
   89 
   90 /* Per-link private data */
   91 struct ng_bridge_link {
   92         hook_p                          hook;           /* netgraph hook */
   93         u_int16_t                       loopCount;      /* loop ignore timer */
   94         struct ng_bridge_link_stats     stats;          /* link stats */
   95 };
   96 
   97 /* Per-node private data */
   98 struct ng_bridge_private {
   99         struct ng_bridge_bucket *tab;           /* hash table bucket array */
  100         struct ng_bridge_config conf;           /* node configuration */
  101         node_p                  node;           /* netgraph node */
  102         u_int                   numHosts;       /* num entries in table */
  103         u_int                   numBuckets;     /* num buckets in table */
  104         u_int                   hashMask;       /* numBuckets - 1 */
  105         int                     numLinks;       /* num connected links */
  106         int                     persistent;     /* can exist w/o hooks */
  107         struct callout          timer;          /* one second periodic timer */
  108 };
  109 typedef struct ng_bridge_private *priv_p;
  110 
  111 /* Information about a host, stored in a hash table entry */
  112 struct ng_bridge_hent {
  113         struct ng_bridge_host           host;   /* actual host info */
  114         SLIST_ENTRY(ng_bridge_hent)     next;   /* next entry in bucket */
  115 };
  116 
  117 /* Hash table bucket declaration */
  118 SLIST_HEAD(ng_bridge_bucket, ng_bridge_hent);
  119 
  120 /* Netgraph node methods */
  121 static ng_constructor_t ng_bridge_constructor;
  122 static ng_rcvmsg_t      ng_bridge_rcvmsg;
  123 static ng_shutdown_t    ng_bridge_shutdown;
  124 static ng_newhook_t     ng_bridge_newhook;
  125 static ng_rcvdata_t     ng_bridge_rcvdata;
  126 static ng_disconnect_t  ng_bridge_disconnect;
  127 
  128 /* Other internal functions */
  129 static struct   ng_bridge_host *ng_bridge_get(priv_p priv, const u_char *addr);
  130 static int      ng_bridge_put(priv_p priv, const u_char *addr, link_p link);
  131 static void     ng_bridge_rehash(priv_p priv);
  132 static void     ng_bridge_remove_hosts(priv_p priv, link_p link);
  133 static void     ng_bridge_timeout(node_p node, hook_p hook, void *arg1, int arg2);
  134 static const    char *ng_bridge_nodename(node_p node);
  135 
  136 /* Ethernet broadcast */
  137 static const u_char ng_bridge_bcast_addr[ETHER_ADDR_LEN] =
  138     { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
  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_struct_field ng_bridge_config_type_fields[]
  196         = NG_BRIDGE_CONFIG_TYPE_INFO;
  197 static const struct ng_parse_type ng_bridge_config_type = {
  198         &ng_parse_struct_type,
  199         &ng_bridge_config_type_fields
  200 };
  201 
  202 /* Parse type for struct ng_bridge_link_stat */
  203 static const struct ng_parse_struct_field ng_bridge_stats_type_fields[]
  204         = NG_BRIDGE_STATS_TYPE_INFO;
  205 static const struct ng_parse_type ng_bridge_stats_type = {
  206         &ng_parse_struct_type,
  207         &ng_bridge_stats_type_fields
  208 };
  209 
  210 /* List of commands and how to convert arguments to/from ASCII */
  211 static const struct ng_cmdlist ng_bridge_cmdlist[] = {
  212         {
  213           NGM_BRIDGE_COOKIE,
  214           NGM_BRIDGE_SET_CONFIG,
  215           "setconfig",
  216           &ng_bridge_config_type,
  217           NULL
  218         },
  219         {
  220           NGM_BRIDGE_COOKIE,
  221           NGM_BRIDGE_GET_CONFIG,
  222           "getconfig",
  223           NULL,
  224           &ng_bridge_config_type
  225         },
  226         {
  227           NGM_BRIDGE_COOKIE,
  228           NGM_BRIDGE_RESET,
  229           "reset",
  230           NULL,
  231           NULL
  232         },
  233         {
  234           NGM_BRIDGE_COOKIE,
  235           NGM_BRIDGE_GET_STATS,
  236           "getstats",
  237           &ng_parse_uint32_type,
  238           &ng_bridge_stats_type
  239         },
  240         {
  241           NGM_BRIDGE_COOKIE,
  242           NGM_BRIDGE_CLR_STATS,
  243           "clrstats",
  244           &ng_parse_uint32_type,
  245           NULL
  246         },
  247         {
  248           NGM_BRIDGE_COOKIE,
  249           NGM_BRIDGE_GETCLR_STATS,
  250           "getclrstats",
  251           &ng_parse_uint32_type,
  252           &ng_bridge_stats_type
  253         },
  254         {
  255           NGM_BRIDGE_COOKIE,
  256           NGM_BRIDGE_GET_TABLE,
  257           "gettable",
  258           NULL,
  259           &ng_bridge_host_ary_type
  260         },
  261         {
  262           NGM_BRIDGE_COOKIE,
  263           NGM_BRIDGE_SET_PERSISTENT,
  264           "setpersistent",
  265           NULL,
  266           NULL
  267         },
  268         { 0 }
  269 };
  270 
  271 /* Node type descriptor */
  272 static struct ng_type ng_bridge_typestruct = {
  273         .version =      NG_ABI_VERSION,
  274         .name =         NG_BRIDGE_NODE_TYPE,
  275         .constructor =  ng_bridge_constructor,
  276         .rcvmsg =       ng_bridge_rcvmsg,
  277         .shutdown =     ng_bridge_shutdown,
  278         .newhook =      ng_bridge_newhook,
  279         .rcvdata =      ng_bridge_rcvdata,
  280         .disconnect =   ng_bridge_disconnect,
  281         .cmdlist =      ng_bridge_cmdlist,
  282 };
  283 NETGRAPH_INIT(bridge, &ng_bridge_typestruct);
  284 
  285 /******************************************************************
  286                     NETGRAPH NODE METHODS
  287 ******************************************************************/
  288 
  289 /*
  290  * Node constructor
  291  */
  292 static int
  293 ng_bridge_constructor(node_p node)
  294 {
  295         priv_p priv;
  296 
  297         /* Allocate and initialize private info */
  298         priv = malloc(sizeof(*priv), M_NETGRAPH_BRIDGE, M_WAITOK | M_ZERO);
  299         ng_callout_init(&priv->timer);
  300 
  301         /* Allocate and initialize hash table, etc. */
  302         priv->tab = malloc(MIN_BUCKETS * sizeof(*priv->tab),
  303             M_NETGRAPH_BRIDGE, M_WAITOK | M_ZERO);
  304         priv->numBuckets = MIN_BUCKETS;
  305         priv->hashMask = MIN_BUCKETS - 1;
  306         priv->conf.debugLevel = 1;
  307         priv->conf.loopTimeout = DEFAULT_LOOP_TIMEOUT;
  308         priv->conf.maxStaleness = DEFAULT_MAX_STALENESS;
  309         priv->conf.minStableAge = DEFAULT_MIN_STABLE_AGE;
  310 
  311         /*
  312          * This node has all kinds of stuff that could be screwed by SMP.
  313          * Until it gets it's own internal protection, we go through in 
  314          * single file. This could hurt a machine bridging between two 
  315          * GB ethernets so it should be fixed. 
  316          * When it's fixed the process SHOULD NOT SLEEP, spinlocks please!
  317          * (and atomic ops )
  318          */
  319         NG_NODE_FORCE_WRITER(node);
  320         NG_NODE_SET_PRIVATE(node, priv);
  321         priv->node = node;
  322 
  323         /* Start timer; timer is always running while node is alive */
  324         ng_callout(&priv->timer, node, NULL, hz, ng_bridge_timeout, NULL, 0);
  325 
  326         /* Done */
  327         return (0);
  328 }
  329 
  330 /*
  331  * Method for attaching a new hook
  332  */
  333 static  int
  334 ng_bridge_newhook(node_p node, hook_p hook, const char *name)
  335 {
  336         const priv_p priv = NG_NODE_PRIVATE(node);
  337 
  338         /* Check for a link hook */
  339         if (strlen(name) > strlen(NG_BRIDGE_HOOK_LINK_PREFIX)) {
  340                 char linkName[NG_HOOKSIZ];
  341                 u_int32_t linkNum;
  342                 link_p link;
  343 
  344                 /* primitive parsing */
  345                 linkNum = strtoul(name + strlen(NG_BRIDGE_HOOK_LINK_PREFIX),
  346                                   NULL, 10);
  347                 /* validation by comparing against the reconstucted name  */
  348                 snprintf(linkName, sizeof(linkName),
  349                          "%s%u", NG_BRIDGE_HOOK_LINK_PREFIX,
  350                          linkNum);
  351                 if (strcmp(linkName, name) != 0)
  352                         return (EINVAL);
  353                 
  354                 if(NG_PEER_NODE(hook) == node)
  355                         return (ELOOP);
  356 
  357                 link = malloc(sizeof(*link), M_NETGRAPH_BRIDGE,
  358                               M_WAITOK|M_ZERO);
  359                 if (link == NULL)
  360                         return (ENOMEM);
  361                 link->hook = hook;
  362                 NG_HOOK_SET_PRIVATE(hook, link);
  363                 priv->numLinks++;
  364                 return (0);
  365         }
  366 
  367         /* Unknown hook name */
  368         return (EINVAL);
  369 }
  370 
  371 /*
  372  * Receive a control message
  373  */
  374 static int
  375 ng_bridge_reset_link(hook_p hook, void *arg __unused)
  376 {
  377         link_p priv = NG_HOOK_PRIVATE(hook);
  378 
  379         priv->loopCount = 0;
  380         bzero(&priv->stats, sizeof(priv->stats));
  381 
  382         return (1);
  383 }
  384 
  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 #ifdef NGM_BRIDGE_TABLE_ABI
  397         case NGM_BRIDGE_COOKIE_TBL:
  398                 switch (msg->header.cmd) {
  399                 case NGM_BRIDGE_GET_CONFIG:
  400                     {
  401                         struct ng_bridge_config_tbl *conf;
  402 
  403                         NG_MKRESPONSE(resp, msg, sizeof(*conf),
  404                             M_NOWAIT|M_ZERO);
  405                         if (resp == NULL) {
  406                                 error = ENOMEM;
  407                                 break;
  408                         }
  409                         conf = (struct ng_bridge_config_tbl *)resp->data;
  410                         conf->cfg = priv->conf;
  411                         break;
  412                     }
  413                 case NGM_BRIDGE_SET_CONFIG:
  414                     {
  415                         struct ng_bridge_config_tbl *conf;
  416 
  417                         if (msg->header.arglen != sizeof(*conf)) {
  418                                 error = EINVAL;
  419                                 break;
  420                         }
  421                         conf = (struct ng_bridge_config_tbl *)msg->data;
  422                         priv->conf = conf->cfg;
  423                         break;
  424                     }
  425                 case NGM_BRIDGE_GET_TABLE:
  426                     {
  427                         struct ng_bridge_host_tbl_ary *ary;
  428                         struct ng_bridge_hent *hent;
  429                         int i, bucket;
  430 
  431                         NG_MKRESPONSE(resp, msg, sizeof(*ary) +
  432                             (priv->numHosts * sizeof(*ary->hosts)), M_NOWAIT);
  433                         if (resp == NULL) {
  434                                 error = ENOMEM;
  435                                 break;
  436                         }
  437                         ary = (struct ng_bridge_host_tbl_ary *)resp->data;
  438                         ary->numHosts = priv->numHosts;
  439                         i = 0;
  440                         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  441                                 SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  442                                         memcpy(ary->hosts[i].addr,
  443                                             hent->host.addr,
  444                                             sizeof(ary->hosts[i].addr));
  445                                         ary->hosts[i].age = hent->host.age;
  446                                         ary->hosts[i].staleness =
  447                                              hent->host.staleness;
  448                                         ary->hosts[i].linkNum = strtol(
  449                                             NG_HOOK_NAME(hent->host.link->hook) +
  450                                             strlen(NG_BRIDGE_HOOK_LINK_PREFIX),
  451                                             NULL, 10);
  452                                         i++;
  453                                 }
  454                         }
  455                         break;
  456                     }
  457                 }
  458                 /* If already handled break, otherwise use new ABI. */
  459                 if (resp != NULL || error != 0)
  460                     break;
  461 #endif /* NGM_BRIDGE_TABLE_ABI */
  462         case NGM_BRIDGE_COOKIE:
  463                 switch (msg->header.cmd) {
  464                 case NGM_BRIDGE_GET_CONFIG:
  465                     {
  466                         struct ng_bridge_config *conf;
  467 
  468                         NG_MKRESPONSE(resp, msg,
  469                             sizeof(struct ng_bridge_config), M_NOWAIT);
  470                         if (resp == NULL) {
  471                                 error = ENOMEM;
  472                                 break;
  473                         }
  474                         conf = (struct ng_bridge_config *)resp->data;
  475                         *conf = priv->conf;     /* no sanity checking needed */
  476                         break;
  477                     }
  478                 case NGM_BRIDGE_SET_CONFIG:
  479                     {
  480                         struct ng_bridge_config *conf;
  481 
  482                         if (msg->header.arglen
  483                             != sizeof(struct ng_bridge_config)) {
  484                                 error = EINVAL;
  485                                 break;
  486                         }
  487                         conf = (struct ng_bridge_config *)msg->data;
  488                         priv->conf = *conf;
  489                         break;
  490                     }
  491                 case NGM_BRIDGE_RESET:
  492                     {
  493                         hook_p rethook;
  494 
  495                         /* Flush all entries in the hash table */
  496                         ng_bridge_remove_hosts(priv, NULL);
  497 
  498                         /* Reset all loop detection counters and stats */
  499                         NG_NODE_FOREACH_HOOK(node, ng_bridge_reset_link, NULL,
  500                             rethook);
  501                         break;
  502                     }
  503                 case NGM_BRIDGE_GET_STATS:
  504                 case NGM_BRIDGE_CLR_STATS:
  505                 case NGM_BRIDGE_GETCLR_STATS:
  506                     {
  507                         hook_p hook;
  508                         link_p link;
  509                         char linkName[NG_HOOKSIZ];
  510                             
  511                         /* Get link number */
  512                         if (msg->header.arglen != sizeof(u_int32_t)) {
  513                                 error = EINVAL;
  514                                 break;
  515                         }
  516                         snprintf(linkName, sizeof(linkName),
  517                                  "%s%u", NG_BRIDGE_HOOK_LINK_PREFIX,
  518                                  *((u_int32_t *)msg->data));
  519                             
  520                         if ((hook = ng_findhook(node, linkName)) == NULL) {
  521                                 error = ENOTCONN;
  522                                 break;
  523                         }
  524                         link = NG_HOOK_PRIVATE(hook);
  525 
  526                         /* Get/clear stats */
  527                         if (msg->header.cmd != NGM_BRIDGE_CLR_STATS) {
  528                                 NG_MKRESPONSE(resp, msg,
  529                                     sizeof(link->stats), M_NOWAIT);
  530                                 if (resp == NULL) {
  531                                         error = ENOMEM;
  532                                         break;
  533                                 }
  534                                 bcopy(&link->stats,
  535                                     resp->data, sizeof(link->stats));
  536                         }
  537                         if (msg->header.cmd != NGM_BRIDGE_GET_STATS)
  538                                 bzero(&link->stats, sizeof(link->stats));
  539                         break;
  540                     }
  541                 case NGM_BRIDGE_GET_TABLE:
  542                     {
  543                         struct ng_bridge_host_ary *ary;
  544                         struct ng_bridge_hent *hent;
  545                         int i = 0, bucket;
  546 
  547                         NG_MKRESPONSE(resp, msg, sizeof(*ary)
  548                             + (priv->numHosts * sizeof(*ary->hosts)), M_NOWAIT);
  549                         if (resp == NULL) {
  550                                 error = ENOMEM;
  551                                 break;
  552                         }
  553                         ary = (struct ng_bridge_host_ary *)resp->data;
  554                         ary->numHosts = priv->numHosts;
  555                         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  556                                 SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  557                                         memcpy(ary->hosts[i].addr,
  558                                                hent->host.addr,
  559                                                sizeof(ary->hosts[i].addr));
  560                                         ary->hosts[i].age       = hent->host.age;
  561                                         ary->hosts[i].staleness = hent->host.staleness;
  562                                         strncpy(ary->hosts[i].hook,
  563                                                 NG_HOOK_NAME(hent->host.link->hook),
  564                                                 sizeof(ary->hosts[i].hook));
  565                                         i++;
  566                                 }
  567                         }
  568                         break;
  569                     }
  570                 case NGM_BRIDGE_SET_PERSISTENT:
  571                     {
  572                         priv->persistent = 1;
  573                         break;
  574                     }
  575                 default:
  576                         error = EINVAL;
  577                         break;
  578                 }
  579                 break;
  580         default:
  581                 error = EINVAL;
  582                 break;
  583         }
  584 
  585         /* Done */
  586         NG_RESPOND_MSG(error, node, item, resp);
  587         NG_FREE_MSG(msg);
  588         return (error);
  589 }
  590 
  591 /*
  592  * Receive data on a hook
  593  */
  594 struct ng_bridge_send_ctx {
  595         link_p foundFirst, incoming;
  596         struct mbuf * m;
  597         int manycast, error;
  598 };
  599 
  600 static int
  601 ng_bridge_send_ctx(hook_p dst, void *arg)
  602 {
  603         struct ng_bridge_send_ctx *ctx = arg;
  604         link_p destLink = NG_HOOK_PRIVATE(dst);
  605         struct mbuf *m2 = NULL;
  606         int error = 0;
  607 
  608         /* Skip incoming link */
  609         if (destLink == ctx->incoming) {
  610                 return (1);
  611         }
  612 
  613         if (ctx->foundFirst == NULL) {
  614                 /*
  615                  * This is the first usable link we have found.
  616                  * Reserve it for the originals.
  617                  * If we never find another we save a copy.
  618                  */
  619                 ctx->foundFirst = destLink;
  620                 return (1);
  621         }
  622 
  623         /*
  624          * It's usable link but not the reserved (first) one.
  625          * Copy mbuf info for sending.
  626          */
  627         m2 = m_dup(ctx->m, M_NOWAIT);   /* XXX m_copypacket() */
  628         if (m2 == NULL) {
  629                 ctx->incoming->stats.memoryFailures++;
  630                 ctx->error = ENOBUFS;
  631                 return (0);            /* abort loop */
  632         }
  633 
  634 
  635         /* Update stats */
  636         destLink->stats.xmitPackets++;
  637         destLink->stats.xmitOctets += m2->m_pkthdr.len;
  638         switch (ctx->manycast) {
  639          default:                                       /* unknown unicast */
  640                 break;
  641          case 1:                                        /* multicast */
  642                 destLink->stats.xmitMulticasts++;
  643                 break;
  644          case 2:                                        /* broadcast */
  645                 destLink->stats.xmitBroadcasts++;
  646                 break;
  647         }
  648 
  649         /* Send packet */
  650         NG_SEND_DATA_ONLY(error, destLink->hook, m2);
  651         if(error)
  652           ctx->error = error;
  653         return (1);
  654 }
  655 
  656 static int
  657 ng_bridge_rcvdata(hook_p hook, item_p item)
  658 {
  659         const node_p node = NG_HOOK_NODE(hook);
  660         const priv_p priv = NG_NODE_PRIVATE(node);
  661         struct ng_bridge_host *host;
  662         struct ether_header *eh;
  663         struct ng_bridge_send_ctx ctx = { 0 };
  664         hook_p ret;
  665 
  666         NGI_GET_M(item, ctx.m);
  667 
  668         ctx.incoming = NG_HOOK_PRIVATE(hook);
  669         /* Sanity check packet and pull up header */
  670         if (ctx.m->m_pkthdr.len < ETHER_HDR_LEN) {
  671                 ctx.incoming->stats.recvRunts++;
  672                 NG_FREE_ITEM(item);
  673                 NG_FREE_M(ctx.m);
  674                 return (EINVAL);
  675         }
  676         if (ctx.m->m_len < ETHER_HDR_LEN && !(ctx.m = m_pullup(ctx.m, ETHER_HDR_LEN))) {
  677                 ctx.incoming->stats.memoryFailures++;
  678                 NG_FREE_ITEM(item);
  679                 return (ENOBUFS);
  680         }
  681         eh = mtod(ctx.m, struct ether_header *);
  682         if ((eh->ether_shost[0] & 1) != 0) {
  683                 ctx.incoming->stats.recvInvalid++;
  684                 NG_FREE_ITEM(item);
  685                 NG_FREE_M(ctx.m);
  686                 return (EINVAL);
  687         }
  688 
  689         /* Is link disabled due to a loopback condition? */
  690         if (ctx.incoming->loopCount != 0) {
  691                 ctx.incoming->stats.loopDrops++;
  692                 NG_FREE_ITEM(item);
  693                 NG_FREE_M(ctx.m);
  694                 return (ELOOP);         /* XXX is this an appropriate error? */
  695         }
  696 
  697         /* Update stats */
  698         ctx.incoming->stats.recvPackets++;
  699         ctx.incoming->stats.recvOctets += ctx.m->m_pkthdr.len;
  700         if ((ctx.manycast = (eh->ether_dhost[0] & 1)) != 0) {
  701                 if (ETHER_EQUAL(eh->ether_dhost, ng_bridge_bcast_addr)) {
  702                         ctx.incoming->stats.recvBroadcasts++;
  703                         ctx.manycast = 2;
  704                 } else
  705                         ctx.incoming->stats.recvMulticasts++;
  706         }
  707 
  708         /* Look up packet's source Ethernet address in hashtable */
  709         if ((host = ng_bridge_get(priv, eh->ether_shost)) != NULL) {
  710 
  711                 /* Update time since last heard from this host */
  712                 host->staleness = 0;
  713 
  714                 /* Did host jump to a different link? */
  715                 if (host->link != ctx.incoming) {
  716 
  717                         /*
  718                          * If the host's old link was recently established
  719                          * on the old link and it's already jumped to a new
  720                          * link, declare a loopback condition.
  721                          */
  722                         if (host->age < priv->conf.minStableAge) {
  723 
  724                                 /* Log the problem */
  725                                 if (priv->conf.debugLevel >= 2) {
  726                                         struct ifnet *ifp = ctx.m->m_pkthdr.rcvif;
  727                                         char suffix[32];
  728 
  729                                         if (ifp != NULL)
  730                                                 snprintf(suffix, sizeof(suffix),
  731                                                     " (%s)", ifp->if_xname);
  732                                         else
  733                                                 *suffix = '\0';
  734                                         log(LOG_WARNING, "ng_bridge: %s:"
  735                                             " loopback detected on %s%s\n",
  736                                             ng_bridge_nodename(node),
  737                                             NG_HOOK_NAME(hook), suffix);
  738                                 }
  739 
  740                                 /* Mark link as linka non grata */
  741                                 ctx.incoming->loopCount = priv->conf.loopTimeout;
  742                                 ctx.incoming->stats.loopDetects++;
  743 
  744                                 /* Forget all hosts on this link */
  745                                 ng_bridge_remove_hosts(priv, ctx.incoming);
  746 
  747                                 /* Drop packet */
  748                                 ctx.incoming->stats.loopDrops++;
  749                                 NG_FREE_ITEM(item);
  750                                 NG_FREE_M(ctx.m);
  751                                 return (ELOOP);         /* XXX appropriate? */
  752                         }
  753 
  754                         /* Move host over to new link */
  755                         host->link = ctx.incoming;
  756                         host->age = 0;
  757                 }
  758         } else {
  759                 if (!ng_bridge_put(priv, eh->ether_shost, ctx.incoming)) {
  760                         ctx.incoming->stats.memoryFailures++;
  761                         NG_FREE_ITEM(item);
  762                         NG_FREE_M(ctx.m);
  763                         return (ENOMEM);
  764                 }
  765         }
  766 
  767         /* Run packet through ipfw processing, if enabled */
  768 #if 0
  769         if (priv->conf.ipfw[linkNum] && V_fw_enable && V_ip_fw_chk_ptr != NULL) {
  770                 /* XXX not implemented yet */
  771         }
  772 #endif
  773 
  774         /*
  775          * If unicast and destination host known, deliver to host's link,
  776          * unless it is the same link as the packet came in on.
  777          */
  778         if (!ctx.manycast) {
  779 
  780                 /* Determine packet destination link */
  781                 if ((host = ng_bridge_get(priv, eh->ether_dhost)) != NULL) {
  782                         link_p destLink = host->link;
  783 
  784                         /* If destination same as incoming link, do nothing */
  785                         if (destLink == ctx.incoming) {
  786                                 NG_FREE_ITEM(item);
  787                                 NG_FREE_M(ctx.m);
  788                                 return (0);
  789                         }
  790 
  791                         /* Deliver packet out the destination link */
  792                         destLink->stats.xmitPackets++;
  793                         destLink->stats.xmitOctets += ctx.m->m_pkthdr.len;
  794                         NG_FWD_NEW_DATA(ctx.error, item, destLink->hook, ctx.m);
  795                         return (ctx.error);
  796                 }
  797 
  798                 /* Destination host is not known */
  799                 ctx.incoming->stats.recvUnknown++;
  800         }
  801 
  802         /* Distribute unknown, multicast, broadcast pkts to all other links */
  803         NG_NODE_FOREACH_HOOK(node, ng_bridge_send_ctx, &ctx, ret);
  804 
  805         /* If we never saw a good link, leave. */
  806         if (ctx.foundFirst == NULL || ctx.error != 0) {
  807                 NG_FREE_ITEM(item);
  808                 NG_FREE_M(ctx.m);
  809                 return (ctx.error);
  810         }
  811         
  812         /*
  813          * If we've sent all the others, send the original
  814          * on the first link we found.
  815          */
  816         NG_FWD_NEW_DATA(ctx.error, item, ctx.foundFirst->hook, ctx.m);
  817         return (ctx.error);
  818 }
  819 
  820 /*
  821  * Shutdown node
  822  */
  823 static int
  824 ng_bridge_shutdown(node_p node)
  825 {
  826         const priv_p priv = NG_NODE_PRIVATE(node);
  827 
  828         /*
  829          * Shut down everything including the timer.  Even if the
  830          * callout has already been dequeued and is about to be
  831          * run, ng_bridge_timeout() won't be fired as the node
  832          * is already marked NGF_INVALID, so we're safe to free
  833          * the node now.
  834          */
  835         KASSERT(priv->numLinks == 0 && priv->numHosts == 0,
  836             ("%s: numLinks=%d numHosts=%d",
  837             __func__, priv->numLinks, priv->numHosts));
  838         ng_uncallout(&priv->timer, node);
  839         NG_NODE_SET_PRIVATE(node, NULL);
  840         NG_NODE_UNREF(node);
  841         free(priv->tab, M_NETGRAPH_BRIDGE);
  842         free(priv, M_NETGRAPH_BRIDGE);
  843         return (0);
  844 }
  845 
  846 /*
  847  * Hook disconnection.
  848  */
  849 static int
  850 ng_bridge_disconnect(hook_p hook)
  851 {
  852         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  853         link_p link = NG_HOOK_PRIVATE(hook);
  854 
  855         /* Remove all hosts associated with this link */
  856         ng_bridge_remove_hosts(priv, link);
  857 
  858         /* Free associated link information */
  859         free(link, M_NETGRAPH_BRIDGE);
  860         priv->numLinks--;
  861 
  862         /* If no more hooks, go away */
  863         if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
  864             && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))
  865             && !priv->persistent) {
  866                 ng_rmnode_self(NG_HOOK_NODE(hook));
  867         }
  868         return (0);
  869 }
  870 
  871 /******************************************************************
  872                     HASH TABLE FUNCTIONS
  873 ******************************************************************/
  874 
  875 /*
  876  * Hash algorithm
  877  */
  878 #define HASH(addr,mask)         ( (((const u_int16_t *)(addr))[0]       \
  879                                  ^ ((const u_int16_t *)(addr))[1]       \
  880                                  ^ ((const u_int16_t *)(addr))[2]) & (mask) )
  881 
  882 /*
  883  * Find a host entry in the table.
  884  */
  885 static struct ng_bridge_host *
  886 ng_bridge_get(priv_p priv, const u_char *addr)
  887 {
  888         const int bucket = HASH(addr, priv->hashMask);
  889         struct ng_bridge_hent *hent;
  890 
  891         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  892                 if (ETHER_EQUAL(hent->host.addr, addr))
  893                         return (&hent->host);
  894         }
  895         return (NULL);
  896 }
  897 
  898 /*
  899  * Add a new host entry to the table. This assumes the host doesn't
  900  * already exist in the table. Returns 1 on success, 0 if there
  901  * was a memory allocation failure.
  902  */
  903 static int
  904 ng_bridge_put(priv_p priv, const u_char *addr, link_p link)
  905 {
  906         const int bucket = HASH(addr, priv->hashMask);
  907         struct ng_bridge_hent *hent;
  908 
  909 #ifdef INVARIANTS
  910         /* Assert that entry does not already exist in hashtable */
  911         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  912                 KASSERT(!ETHER_EQUAL(hent->host.addr, addr),
  913                     ("%s: entry %6D exists in table", __func__, addr, ":"));
  914         }
  915 #endif
  916 
  917         /* Allocate and initialize new hashtable entry */
  918         hent = malloc(sizeof(*hent), M_NETGRAPH_BRIDGE, M_NOWAIT);
  919         if (hent == NULL)
  920                 return (0);
  921         bcopy(addr, hent->host.addr, ETHER_ADDR_LEN);
  922         hent->host.link = link;
  923         hent->host.staleness = 0;
  924         hent->host.age = 0;
  925 
  926         /* Add new element to hash bucket */
  927         SLIST_INSERT_HEAD(&priv->tab[bucket], hent, next);
  928         priv->numHosts++;
  929 
  930         /* Resize table if necessary */
  931         ng_bridge_rehash(priv);
  932         return (1);
  933 }
  934 
  935 /*
  936  * Resize the hash table. We try to maintain the number of buckets
  937  * such that the load factor is in the range 0.25 to 1.0.
  938  *
  939  * If we can't get the new memory then we silently fail. This is OK
  940  * because things will still work and we'll try again soon anyway.
  941  */
  942 static void
  943 ng_bridge_rehash(priv_p priv)
  944 {
  945         struct ng_bridge_bucket *newTab;
  946         int oldBucket, newBucket;
  947         int newNumBuckets;
  948         u_int newMask;
  949 
  950         /* Is table too full or too empty? */
  951         if (priv->numHosts > priv->numBuckets
  952             && (priv->numBuckets << 1) <= MAX_BUCKETS)
  953                 newNumBuckets = priv->numBuckets << 1;
  954         else if (priv->numHosts < (priv->numBuckets >> 2)
  955             && (priv->numBuckets >> 2) >= MIN_BUCKETS)
  956                 newNumBuckets = priv->numBuckets >> 2;
  957         else
  958                 return;
  959         newMask = newNumBuckets - 1;
  960 
  961         /* Allocate and initialize new table */
  962         newTab = malloc(newNumBuckets * sizeof(*newTab),
  963             M_NETGRAPH_BRIDGE, M_NOWAIT | M_ZERO);
  964         if (newTab == NULL)
  965                 return;
  966 
  967         /* Move all entries from old table to new table */
  968         for (oldBucket = 0; oldBucket < priv->numBuckets; oldBucket++) {
  969                 struct ng_bridge_bucket *const oldList = &priv->tab[oldBucket];
  970 
  971                 while (!SLIST_EMPTY(oldList)) {
  972                         struct ng_bridge_hent *const hent
  973                             = SLIST_FIRST(oldList);
  974 
  975                         SLIST_REMOVE_HEAD(oldList, next);
  976                         newBucket = HASH(hent->host.addr, newMask);
  977                         SLIST_INSERT_HEAD(&newTab[newBucket], hent, next);
  978                 }
  979         }
  980 
  981         /* Replace old table with new one */
  982         if (priv->conf.debugLevel >= 3) {
  983                 log(LOG_INFO, "ng_bridge: %s: table size %d -> %d\n",
  984                     ng_bridge_nodename(priv->node),
  985                     priv->numBuckets, newNumBuckets);
  986         }
  987         free(priv->tab, M_NETGRAPH_BRIDGE);
  988         priv->numBuckets = newNumBuckets;
  989         priv->hashMask = newMask;
  990         priv->tab = newTab;
  991         return;
  992 }
  993 
  994 /******************************************************************
  995                     MISC FUNCTIONS
  996 ******************************************************************/
  997 
  998 
  999 /*
 1000  * Remove all hosts associated with a specific link from the hashtable.
 1001  * If linkNum == -1, then remove all hosts in the table.
 1002  */
 1003 static void
 1004 ng_bridge_remove_hosts(priv_p priv, link_p link)
 1005 {
 1006         int bucket;
 1007 
 1008         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
 1009                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
 1010 
 1011                 while (*hptr != NULL) {
 1012                         struct ng_bridge_hent *const hent = *hptr;
 1013 
 1014                         if (link == NULL || hent->host.link == link) {
 1015                                 *hptr = SLIST_NEXT(hent, next);
 1016                                 free(hent, M_NETGRAPH_BRIDGE);
 1017                                 priv->numHosts--;
 1018                         } else
 1019                                 hptr = &SLIST_NEXT(hent, next);
 1020                 }
 1021         }
 1022 }
 1023 
 1024 /*
 1025  * Handle our once-per-second timeout event. We do two things:
 1026  * we decrement link->loopCount for those links being muted due to
 1027  * a detected loopback condition, and we remove any hosts from
 1028  * the hashtable whom we haven't heard from in a long while.
 1029  */
 1030 static int
 1031 ng_bridge_unmute(hook_p hook, void *arg)
 1032 {
 1033         link_p link = NG_HOOK_PRIVATE(hook);
 1034         node_p node = NG_HOOK_NODE(hook);
 1035         priv_p priv = NG_NODE_PRIVATE(node);
 1036         int *counter = arg;
 1037 
 1038         if (link->loopCount != 0) {
 1039                 link->loopCount--;
 1040                 if (link->loopCount == 0 && priv->conf.debugLevel >= 2) {
 1041                         log(LOG_INFO, "ng_bridge: %s:"
 1042                             " restoring looped back %s\n",
 1043                             ng_bridge_nodename(node), NG_HOOK_NAME(hook));
 1044                 }
 1045         }
 1046         (*counter)++;
 1047         return (1);
 1048 }
 1049 
 1050 static void
 1051 ng_bridge_timeout(node_p node, hook_p hook, void *arg1, int arg2)
 1052 {
 1053         const priv_p priv = NG_NODE_PRIVATE(node);
 1054         int bucket;
 1055         int counter = 0;
 1056         hook_p ret;
 1057 
 1058         /* Update host time counters and remove stale entries */
 1059         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
 1060                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
 1061 
 1062                 while (*hptr != NULL) {
 1063                         struct ng_bridge_hent *const hent = *hptr;
 1064 
 1065                         /* Remove hosts we haven't heard from in a while */
 1066                         if (++hent->host.staleness >= priv->conf.maxStaleness) {
 1067                                 *hptr = SLIST_NEXT(hent, next);
 1068                                 free(hent, M_NETGRAPH_BRIDGE);
 1069                                 priv->numHosts--;
 1070                         } else {
 1071                                 if (hent->host.age < 0xffff)
 1072                                         hent->host.age++;
 1073                                 hptr = &SLIST_NEXT(hent, next);
 1074                                 counter++;
 1075                         }
 1076                 }
 1077         }
 1078         KASSERT(priv->numHosts == counter,
 1079             ("%s: hosts: %d != %d", __func__, priv->numHosts, counter));
 1080 
 1081         /* Decrease table size if necessary */
 1082         ng_bridge_rehash(priv);
 1083 
 1084         /* Decrease loop counter on muted looped back links */
 1085         counter = 0;
 1086         NG_NODE_FOREACH_HOOK(node, ng_bridge_unmute, &counter, ret);
 1087         KASSERT(priv->numLinks == counter,
 1088             ("%s: links: %d != %d", __func__, priv->numLinks, counter));
 1089 
 1090         /* Register a new timeout, keeping the existing node reference */
 1091         ng_callout(&priv->timer, node, NULL, hz, ng_bridge_timeout, NULL, 0);
 1092 }
 1093 
 1094 /*
 1095  * Return node's "name", even if it doesn't have one.
 1096  */
 1097 static const char *
 1098 ng_bridge_nodename(node_p node)
 1099 {
 1100         static char name[NG_NODESIZ];
 1101 
 1102         if (NG_NODE_HAS_NAME(node))
 1103                 snprintf(name, sizeof(name), "%s", NG_NODE_NAME(node));
 1104         else
 1105                 snprintf(name, sizeof(name), "[%x]", ng_node2ID(node));
 1106         return name;
 1107 }
 1108 

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