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

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    1 /*
    2  * ng_bridge.c
    3  */
    4 
    5 /*-
    6  * Copyright (c) 2000 Whistle Communications, Inc.
    7  * All rights reserved.
    8  * 
    9  * Subject to the following obligations and disclaimer of warranty, use and
   10  * redistribution of this software, in source or object code forms, with or
   11  * without modifications are expressly permitted by Whistle Communications;
   12  * provided, however, that:
   13  * 1. Any and all reproductions of the source or object code must include the
   14  *    copyright notice above and the following disclaimer of warranties; and
   15  * 2. No rights are granted, in any manner or form, to use Whistle
   16  *    Communications, Inc. trademarks, including the mark "WHISTLE
   17  *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
   18  *    such appears in the above copyright notice or in the software.
   19  * 
   20  * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
   21  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
   22  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
   23  * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
   24  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
   25  * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
   26  * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
   27  * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
   28  * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
   29  * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
   30  * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
   31  * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
   32  * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
   33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   35  * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
   36  * OF SUCH DAMAGE.
   37  *
   38  * Author: Archie Cobbs <archie@freebsd.org>
   39  *
   40  * $FreeBSD: releng/7.4/sys/netgraph/ng_bridge.c 141574 2005-02-09 15:14:44Z ru $
   41  */
   42 
   43 /*
   44  * ng_bridge(4) netgraph node type
   45  *
   46  * The node performs standard intelligent Ethernet bridging over
   47  * each of its connected hooks, or links.  A simple loop detection
   48  * algorithm is included which disables a link for priv->conf.loopTimeout
   49  * seconds when a host is seen to have jumped from one link to
   50  * another within priv->conf.minStableAge seconds.
   51  *
   52  * We keep a hashtable that maps Ethernet addresses to host info,
   53  * which is contained in struct ng_bridge_host's. These structures
   54  * tell us on which link the host may be found. A host's entry will
   55  * expire after priv->conf.maxStaleness seconds.
   56  *
   57  * This node is optimzed for stable networks, where machines jump
   58  * from one port to the other only rarely.
   59  */
   60 
   61 #include <sys/param.h>
   62 #include <sys/systm.h>
   63 #include <sys/kernel.h>
   64 #include <sys/malloc.h>
   65 #include <sys/mbuf.h>
   66 #include <sys/errno.h>
   67 #include <sys/syslog.h>
   68 #include <sys/socket.h>
   69 #include <sys/ctype.h>
   70 
   71 #include <net/if.h>
   72 #include <net/ethernet.h>
   73 
   74 #include <netinet/in.h>
   75 #include <netinet/ip_fw.h>
   76 
   77 #include <netgraph/ng_message.h>
   78 #include <netgraph/netgraph.h>
   79 #include <netgraph/ng_parse.h>
   80 #include <netgraph/ng_bridge.h>
   81 
   82 #ifdef NG_SEPARATE_MALLOC
   83 MALLOC_DEFINE(M_NETGRAPH_BRIDGE, "netgraph_bridge", "netgraph bridge node ");
   84 #else
   85 #define M_NETGRAPH_BRIDGE M_NETGRAPH
   86 #endif
   87 
   88 /* Per-link private data */
   89 struct ng_bridge_link {
   90         hook_p                          hook;           /* netgraph hook */
   91         u_int16_t                       loopCount;      /* loop ignore timer */
   92         struct ng_bridge_link_stats     stats;          /* link stats */
   93 };
   94 
   95 /* Per-node private data */
   96 struct ng_bridge_private {
   97         struct ng_bridge_bucket *tab;           /* hash table bucket array */
   98         struct ng_bridge_link   *links[NG_BRIDGE_MAX_LINKS];
   99         struct ng_bridge_config conf;           /* node configuration */
  100         node_p                  node;           /* netgraph node */
  101         u_int                   numHosts;       /* num entries in table */
  102         u_int                   numBuckets;     /* num buckets in table */
  103         u_int                   hashMask;       /* numBuckets - 1 */
  104         int                     numLinks;       /* num connected links */
  105         struct callout          timer;          /* one second periodic timer */
  106 };
  107 typedef struct ng_bridge_private *priv_p;
  108 
  109 /* Information about a host, stored in a hash table entry */
  110 struct ng_bridge_hent {
  111         struct ng_bridge_host           host;   /* actual host info */
  112         SLIST_ENTRY(ng_bridge_hent)     next;   /* next entry in bucket */
  113 };
  114 
  115 /* Hash table bucket declaration */
  116 SLIST_HEAD(ng_bridge_bucket, ng_bridge_hent);
  117 
  118 /* Netgraph node methods */
  119 static ng_constructor_t ng_bridge_constructor;
  120 static ng_rcvmsg_t      ng_bridge_rcvmsg;
  121 static ng_shutdown_t    ng_bridge_shutdown;
  122 static ng_newhook_t     ng_bridge_newhook;
  123 static ng_rcvdata_t     ng_bridge_rcvdata;
  124 static ng_disconnect_t  ng_bridge_disconnect;
  125 
  126 /* Other internal functions */
  127 static struct   ng_bridge_host *ng_bridge_get(priv_p priv, const u_char *addr);
  128 static int      ng_bridge_put(priv_p priv, const u_char *addr, int linkNum);
  129 static void     ng_bridge_rehash(priv_p priv);
  130 static void     ng_bridge_remove_hosts(priv_p priv, int linkNum);
  131 static void     ng_bridge_timeout(node_p node, hook_p hook, void *arg1, int arg2);
  132 static const    char *ng_bridge_nodename(node_p node);
  133 
  134 /* Ethernet broadcast */
  135 static const u_char ng_bridge_bcast_addr[ETHER_ADDR_LEN] =
  136     { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
  137 
  138 /* Store each hook's link number in the private field */
  139 #define LINK_NUM(hook)          (*(u_int16_t *)(&(hook)->private))
  140 
  141 /* Compare Ethernet addresses using 32 and 16 bit words instead of bytewise */
  142 #define ETHER_EQUAL(a,b)        (((const u_int32_t *)(a))[0] \
  143                                         == ((const u_int32_t *)(b))[0] \
  144                                     && ((const u_int16_t *)(a))[2] \
  145                                         == ((const u_int16_t *)(b))[2])
  146 
  147 /* Minimum and maximum number of hash buckets. Must be a power of two. */
  148 #define MIN_BUCKETS             (1 << 5)        /* 32 */
  149 #define MAX_BUCKETS             (1 << 14)       /* 16384 */
  150 
  151 /* Configuration default values */
  152 #define DEFAULT_LOOP_TIMEOUT    60
  153 #define DEFAULT_MAX_STALENESS   (15 * 60)       /* same as ARP timeout */
  154 #define DEFAULT_MIN_STABLE_AGE  1
  155 
  156 /******************************************************************
  157                     NETGRAPH PARSE TYPES
  158 ******************************************************************/
  159 
  160 /*
  161  * How to determine the length of the table returned by NGM_BRIDGE_GET_TABLE
  162  */
  163 static int
  164 ng_bridge_getTableLength(const struct ng_parse_type *type,
  165         const u_char *start, const u_char *buf)
  166 {
  167         const struct ng_bridge_host_ary *const hary
  168             = (const struct ng_bridge_host_ary *)(buf - sizeof(u_int32_t));
  169 
  170         return hary->numHosts;
  171 }
  172 
  173 /* Parse type for struct ng_bridge_host_ary */
  174 static const struct ng_parse_struct_field ng_bridge_host_type_fields[]
  175         = NG_BRIDGE_HOST_TYPE_INFO(&ng_parse_enaddr_type);
  176 static const struct ng_parse_type ng_bridge_host_type = {
  177         &ng_parse_struct_type,
  178         &ng_bridge_host_type_fields
  179 };
  180 static const struct ng_parse_array_info ng_bridge_hary_type_info = {
  181         &ng_bridge_host_type,
  182         ng_bridge_getTableLength
  183 };
  184 static const struct ng_parse_type ng_bridge_hary_type = {
  185         &ng_parse_array_type,
  186         &ng_bridge_hary_type_info
  187 };
  188 static const struct ng_parse_struct_field ng_bridge_host_ary_type_fields[]
  189         = NG_BRIDGE_HOST_ARY_TYPE_INFO(&ng_bridge_hary_type);
  190 static const struct ng_parse_type ng_bridge_host_ary_type = {
  191         &ng_parse_struct_type,
  192         &ng_bridge_host_ary_type_fields
  193 };
  194 
  195 /* Parse type for struct ng_bridge_config */
  196 static const struct ng_parse_fixedarray_info ng_bridge_ipfwary_type_info = {
  197         &ng_parse_uint8_type,
  198         NG_BRIDGE_MAX_LINKS
  199 };
  200 static const struct ng_parse_type ng_bridge_ipfwary_type = {
  201         &ng_parse_fixedarray_type,
  202         &ng_bridge_ipfwary_type_info
  203 };
  204 static const struct ng_parse_struct_field ng_bridge_config_type_fields[]
  205         = NG_BRIDGE_CONFIG_TYPE_INFO(&ng_bridge_ipfwary_type);
  206 static const struct ng_parse_type ng_bridge_config_type = {
  207         &ng_parse_struct_type,
  208         &ng_bridge_config_type_fields
  209 };
  210 
  211 /* Parse type for struct ng_bridge_link_stat */
  212 static const struct ng_parse_struct_field ng_bridge_stats_type_fields[]
  213         = NG_BRIDGE_STATS_TYPE_INFO;
  214 static const struct ng_parse_type ng_bridge_stats_type = {
  215         &ng_parse_struct_type,
  216         &ng_bridge_stats_type_fields
  217 };
  218 
  219 /* List of commands and how to convert arguments to/from ASCII */
  220 static const struct ng_cmdlist ng_bridge_cmdlist[] = {
  221         {
  222           NGM_BRIDGE_COOKIE,
  223           NGM_BRIDGE_SET_CONFIG,
  224           "setconfig",
  225           &ng_bridge_config_type,
  226           NULL
  227         },
  228         {
  229           NGM_BRIDGE_COOKIE,
  230           NGM_BRIDGE_GET_CONFIG,
  231           "getconfig",
  232           NULL,
  233           &ng_bridge_config_type
  234         },
  235         {
  236           NGM_BRIDGE_COOKIE,
  237           NGM_BRIDGE_RESET,
  238           "reset",
  239           NULL,
  240           NULL
  241         },
  242         {
  243           NGM_BRIDGE_COOKIE,
  244           NGM_BRIDGE_GET_STATS,
  245           "getstats",
  246           &ng_parse_uint32_type,
  247           &ng_bridge_stats_type
  248         },
  249         {
  250           NGM_BRIDGE_COOKIE,
  251           NGM_BRIDGE_CLR_STATS,
  252           "clrstats",
  253           &ng_parse_uint32_type,
  254           NULL
  255         },
  256         {
  257           NGM_BRIDGE_COOKIE,
  258           NGM_BRIDGE_GETCLR_STATS,
  259           "getclrstats",
  260           &ng_parse_uint32_type,
  261           &ng_bridge_stats_type
  262         },
  263         {
  264           NGM_BRIDGE_COOKIE,
  265           NGM_BRIDGE_GET_TABLE,
  266           "gettable",
  267           NULL,
  268           &ng_bridge_host_ary_type
  269         },
  270         { 0 }
  271 };
  272 
  273 /* Node type descriptor */
  274 static struct ng_type ng_bridge_typestruct = {
  275         .version =      NG_ABI_VERSION,
  276         .name =         NG_BRIDGE_NODE_TYPE,
  277         .constructor =  ng_bridge_constructor,
  278         .rcvmsg =       ng_bridge_rcvmsg,
  279         .shutdown =     ng_bridge_shutdown,
  280         .newhook =      ng_bridge_newhook,
  281         .rcvdata =      ng_bridge_rcvdata,
  282         .disconnect =   ng_bridge_disconnect,
  283         .cmdlist =      ng_bridge_cmdlist,
  284 };
  285 NETGRAPH_INIT(bridge, &ng_bridge_typestruct);
  286 
  287 /******************************************************************
  288                     NETGRAPH NODE METHODS
  289 ******************************************************************/
  290 
  291 /*
  292  * Node constructor
  293  */
  294 static int
  295 ng_bridge_constructor(node_p node)
  296 {
  297         priv_p priv;
  298 
  299         /* Allocate and initialize private info */
  300         MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH_BRIDGE, M_NOWAIT | M_ZERO);
  301         if (priv == NULL)
  302                 return (ENOMEM);
  303         ng_callout_init(&priv->timer);
  304 
  305         /* Allocate and initialize hash table, etc. */
  306         MALLOC(priv->tab, struct ng_bridge_bucket *,
  307             MIN_BUCKETS * sizeof(*priv->tab), M_NETGRAPH_BRIDGE, M_NOWAIT | M_ZERO);
  308         if (priv->tab == NULL) {
  309                 FREE(priv, M_NETGRAPH_BRIDGE);
  310                 return (ENOMEM);
  311         }
  312         priv->numBuckets = MIN_BUCKETS;
  313         priv->hashMask = MIN_BUCKETS - 1;
  314         priv->conf.debugLevel = 1;
  315         priv->conf.loopTimeout = DEFAULT_LOOP_TIMEOUT;
  316         priv->conf.maxStaleness = DEFAULT_MAX_STALENESS;
  317         priv->conf.minStableAge = DEFAULT_MIN_STABLE_AGE;
  318 
  319         /*
  320          * This node has all kinds of stuff that could be screwed by SMP.
  321          * Until it gets it's own internal protection, we go through in 
  322          * single file. This could hurt a machine bridging beteen two 
  323          * GB ethernets so it should be fixed. 
  324          * When it's fixed the process SHOULD NOT SLEEP, spinlocks please!
  325          * (and atomic ops )
  326          */
  327         NG_NODE_FORCE_WRITER(node);
  328         NG_NODE_SET_PRIVATE(node, priv);
  329         priv->node = node;
  330 
  331         /* Start timer; timer is always running while node is alive */
  332         ng_callout(&priv->timer, node, NULL, hz, ng_bridge_timeout, NULL, 0);
  333 
  334         /* Done */
  335         return (0);
  336 }
  337 
  338 /*
  339  * Method for attaching a new hook
  340  */
  341 static  int
  342 ng_bridge_newhook(node_p node, hook_p hook, const char *name)
  343 {
  344         const priv_p priv = NG_NODE_PRIVATE(node);
  345 
  346         /* Check for a link hook */
  347         if (strncmp(name, NG_BRIDGE_HOOK_LINK_PREFIX,
  348             strlen(NG_BRIDGE_HOOK_LINK_PREFIX)) == 0) {
  349                 const char *cp;
  350                 char *eptr;
  351                 u_long linkNum;
  352 
  353                 cp = name + strlen(NG_BRIDGE_HOOK_LINK_PREFIX);
  354                 if (!isdigit(*cp) || (cp[0] == '' && cp[1] != '\0'))
  355                         return (EINVAL);
  356                 linkNum = strtoul(cp, &eptr, 10);
  357                 if (*eptr != '\0' || linkNum >= NG_BRIDGE_MAX_LINKS)
  358                         return (EINVAL);
  359                 if (priv->links[linkNum] != NULL)
  360                         return (EISCONN);
  361                 MALLOC(priv->links[linkNum], struct ng_bridge_link *,
  362                     sizeof(*priv->links[linkNum]), M_NETGRAPH_BRIDGE, M_NOWAIT|M_ZERO);
  363                 if (priv->links[linkNum] == NULL)
  364                         return (ENOMEM);
  365                 priv->links[linkNum]->hook = hook;
  366                 NG_HOOK_SET_PRIVATE(hook, (void *)linkNum);
  367                 priv->numLinks++;
  368                 return (0);
  369         }
  370 
  371         /* Unknown hook name */
  372         return (EINVAL);
  373 }
  374 
  375 /*
  376  * Receive a control message
  377  */
  378 static int
  379 ng_bridge_rcvmsg(node_p node, item_p item, hook_p lasthook)
  380 {
  381         const priv_p priv = NG_NODE_PRIVATE(node);
  382         struct ng_mesg *resp = NULL;
  383         int error = 0;
  384         struct ng_mesg *msg;
  385 
  386         NGI_GET_MSG(item, msg);
  387         switch (msg->header.typecookie) {
  388         case NGM_BRIDGE_COOKIE:
  389                 switch (msg->header.cmd) {
  390                 case NGM_BRIDGE_GET_CONFIG:
  391                     {
  392                         struct ng_bridge_config *conf;
  393 
  394                         NG_MKRESPONSE(resp, msg,
  395                             sizeof(struct ng_bridge_config), M_NOWAIT);
  396                         if (resp == NULL) {
  397                                 error = ENOMEM;
  398                                 break;
  399                         }
  400                         conf = (struct ng_bridge_config *)resp->data;
  401                         *conf = priv->conf;     /* no sanity checking needed */
  402                         break;
  403                     }
  404                 case NGM_BRIDGE_SET_CONFIG:
  405                     {
  406                         struct ng_bridge_config *conf;
  407                         int i;
  408 
  409                         if (msg->header.arglen
  410                             != sizeof(struct ng_bridge_config)) {
  411                                 error = EINVAL;
  412                                 break;
  413                         }
  414                         conf = (struct ng_bridge_config *)msg->data;
  415                         priv->conf = *conf;
  416                         for (i = 0; i < NG_BRIDGE_MAX_LINKS; i++)
  417                                 priv->conf.ipfw[i] = !!priv->conf.ipfw[i];
  418                         break;
  419                     }
  420                 case NGM_BRIDGE_RESET:
  421                     {
  422                         int i;
  423 
  424                         /* Flush all entries in the hash table */
  425                         ng_bridge_remove_hosts(priv, -1);
  426 
  427                         /* Reset all loop detection counters and stats */
  428                         for (i = 0; i < NG_BRIDGE_MAX_LINKS; i++) {
  429                                 if (priv->links[i] == NULL)
  430                                         continue;
  431                                 priv->links[i]->loopCount = 0;
  432                                 bzero(&priv->links[i]->stats,
  433                                     sizeof(priv->links[i]->stats));
  434                         }
  435                         break;
  436                     }
  437                 case NGM_BRIDGE_GET_STATS:
  438                 case NGM_BRIDGE_CLR_STATS:
  439                 case NGM_BRIDGE_GETCLR_STATS:
  440                     {
  441                         struct ng_bridge_link *link;
  442                         int linkNum;
  443 
  444                         /* Get link number */
  445                         if (msg->header.arglen != sizeof(u_int32_t)) {
  446                                 error = EINVAL;
  447                                 break;
  448                         }
  449                         linkNum = *((u_int32_t *)msg->data);
  450                         if (linkNum < 0 || linkNum >= NG_BRIDGE_MAX_LINKS) {
  451                                 error = EINVAL;
  452                                 break;
  453                         }
  454                         if ((link = priv->links[linkNum]) == NULL) {
  455                                 error = ENOTCONN;
  456                                 break;
  457                         }
  458 
  459                         /* Get/clear stats */
  460                         if (msg->header.cmd != NGM_BRIDGE_CLR_STATS) {
  461                                 NG_MKRESPONSE(resp, msg,
  462                                     sizeof(link->stats), M_NOWAIT);
  463                                 if (resp == NULL) {
  464                                         error = ENOMEM;
  465                                         break;
  466                                 }
  467                                 bcopy(&link->stats,
  468                                     resp->data, sizeof(link->stats));
  469                         }
  470                         if (msg->header.cmd != NGM_BRIDGE_GET_STATS)
  471                                 bzero(&link->stats, sizeof(link->stats));
  472                         break;
  473                     }
  474                 case NGM_BRIDGE_GET_TABLE:
  475                     {
  476                         struct ng_bridge_host_ary *ary;
  477                         struct ng_bridge_hent *hent;
  478                         int i = 0, bucket;
  479 
  480                         NG_MKRESPONSE(resp, msg, sizeof(*ary)
  481                             + (priv->numHosts * sizeof(*ary->hosts)), M_NOWAIT);
  482                         if (resp == NULL) {
  483                                 error = ENOMEM;
  484                                 break;
  485                         }
  486                         ary = (struct ng_bridge_host_ary *)resp->data;
  487                         ary->numHosts = priv->numHosts;
  488                         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  489                                 SLIST_FOREACH(hent, &priv->tab[bucket], next)
  490                                         ary->hosts[i++] = hent->host;
  491                         }
  492                         break;
  493                     }
  494                 default:
  495                         error = EINVAL;
  496                         break;
  497                 }
  498                 break;
  499         default:
  500                 error = EINVAL;
  501                 break;
  502         }
  503 
  504         /* Done */
  505         NG_RESPOND_MSG(error, node, item, resp);
  506         NG_FREE_MSG(msg);
  507         return (error);
  508 }
  509 
  510 /*
  511  * Receive data on a hook
  512  */
  513 static int
  514 ng_bridge_rcvdata(hook_p hook, item_p item)
  515 {
  516         const node_p node = NG_HOOK_NODE(hook);
  517         const priv_p priv = NG_NODE_PRIVATE(node);
  518         struct ng_bridge_host *host;
  519         struct ng_bridge_link *link;
  520         struct ether_header *eh;
  521         int error = 0, linkNum, linksSeen;
  522         int manycast;
  523         struct mbuf *m;
  524         struct ng_bridge_link *firstLink;
  525 
  526         NGI_GET_M(item, m);
  527         /* Get link number */
  528         linkNum = (intptr_t)NG_HOOK_PRIVATE(hook);
  529         KASSERT(linkNum >= 0 && linkNum < NG_BRIDGE_MAX_LINKS,
  530             ("%s: linkNum=%u", __func__, linkNum));
  531         link = priv->links[linkNum];
  532         KASSERT(link != NULL, ("%s: link%d null", __func__, linkNum));
  533 
  534         /* Sanity check packet and pull up header */
  535         if (m->m_pkthdr.len < ETHER_HDR_LEN) {
  536                 link->stats.recvRunts++;
  537                 NG_FREE_ITEM(item);
  538                 NG_FREE_M(m);
  539                 return (EINVAL);
  540         }
  541         if (m->m_len < ETHER_HDR_LEN && !(m = m_pullup(m, ETHER_HDR_LEN))) {
  542                 link->stats.memoryFailures++;
  543                 NG_FREE_ITEM(item);
  544                 return (ENOBUFS);
  545         }
  546         eh = mtod(m, struct ether_header *);
  547         if ((eh->ether_shost[0] & 1) != 0) {
  548                 link->stats.recvInvalid++;
  549                 NG_FREE_ITEM(item);
  550                 NG_FREE_M(m);
  551                 return (EINVAL);
  552         }
  553 
  554         /* Is link disabled due to a loopback condition? */
  555         if (link->loopCount != 0) {
  556                 link->stats.loopDrops++;
  557                 NG_FREE_ITEM(item);
  558                 NG_FREE_M(m);
  559                 return (ELOOP);         /* XXX is this an appropriate error? */
  560         }
  561 
  562         /* Update stats */
  563         link->stats.recvPackets++;
  564         link->stats.recvOctets += m->m_pkthdr.len;
  565         if ((manycast = (eh->ether_dhost[0] & 1)) != 0) {
  566                 if (ETHER_EQUAL(eh->ether_dhost, ng_bridge_bcast_addr)) {
  567                         link->stats.recvBroadcasts++;
  568                         manycast = 2;
  569                 } else
  570                         link->stats.recvMulticasts++;
  571         }
  572 
  573         /* Look up packet's source Ethernet address in hashtable */
  574         if ((host = ng_bridge_get(priv, eh->ether_shost)) != NULL) {
  575 
  576                 /* Update time since last heard from this host */
  577                 host->staleness = 0;
  578 
  579                 /* Did host jump to a different link? */
  580                 if (host->linkNum != linkNum) {
  581 
  582                         /*
  583                          * If the host's old link was recently established
  584                          * on the old link and it's already jumped to a new
  585                          * link, declare a loopback condition.
  586                          */
  587                         if (host->age < priv->conf.minStableAge) {
  588 
  589                                 /* Log the problem */
  590                                 if (priv->conf.debugLevel >= 2) {
  591                                         struct ifnet *ifp = m->m_pkthdr.rcvif;
  592                                         char suffix[32];
  593 
  594                                         if (ifp != NULL)
  595                                                 snprintf(suffix, sizeof(suffix),
  596                                                     " (%s)", ifp->if_xname);
  597                                         else
  598                                                 *suffix = '\0';
  599                                         log(LOG_WARNING, "ng_bridge: %s:"
  600                                             " loopback detected on %s%s\n",
  601                                             ng_bridge_nodename(node),
  602                                             NG_HOOK_NAME(hook), suffix);
  603                                 }
  604 
  605                                 /* Mark link as linka non grata */
  606                                 link->loopCount = priv->conf.loopTimeout;
  607                                 link->stats.loopDetects++;
  608 
  609                                 /* Forget all hosts on this link */
  610                                 ng_bridge_remove_hosts(priv, linkNum);
  611 
  612                                 /* Drop packet */
  613                                 link->stats.loopDrops++;
  614                                 NG_FREE_ITEM(item);
  615                                 NG_FREE_M(m);
  616                                 return (ELOOP);         /* XXX appropriate? */
  617                         }
  618 
  619                         /* Move host over to new link */
  620                         host->linkNum = linkNum;
  621                         host->age = 0;
  622                 }
  623         } else {
  624                 if (!ng_bridge_put(priv, eh->ether_shost, linkNum)) {
  625                         link->stats.memoryFailures++;
  626                         NG_FREE_ITEM(item);
  627                         NG_FREE_M(m);
  628                         return (ENOMEM);
  629                 }
  630         }
  631 
  632         /* Run packet through ipfw processing, if enabled */
  633 #if 0
  634         if (priv->conf.ipfw[linkNum] && fw_enable && ip_fw_chk_ptr != NULL) {
  635                 /* XXX not implemented yet */
  636         }
  637 #endif
  638 
  639         /*
  640          * If unicast and destination host known, deliver to host's link,
  641          * unless it is the same link as the packet came in on.
  642          */
  643         if (!manycast) {
  644 
  645                 /* Determine packet destination link */
  646                 if ((host = ng_bridge_get(priv, eh->ether_dhost)) != NULL) {
  647                         struct ng_bridge_link *const destLink
  648                             = priv->links[host->linkNum];
  649 
  650                         /* If destination same as incoming link, do nothing */
  651                         KASSERT(destLink != NULL,
  652                             ("%s: link%d null", __func__, host->linkNum));
  653                         if (destLink == link) {
  654                                 NG_FREE_ITEM(item);
  655                                 NG_FREE_M(m);
  656                                 return (0);
  657                         }
  658 
  659                         /* Deliver packet out the destination link */
  660                         destLink->stats.xmitPackets++;
  661                         destLink->stats.xmitOctets += m->m_pkthdr.len;
  662                         NG_FWD_NEW_DATA(error, item, destLink->hook, m);
  663                         return (error);
  664                 }
  665 
  666                 /* Destination host is not known */
  667                 link->stats.recvUnknown++;
  668         }
  669 
  670         /* Distribute unknown, multicast, broadcast pkts to all other links */
  671         firstLink = NULL;
  672         for (linkNum = linksSeen = 0; linksSeen <= priv->numLinks; linkNum++) {
  673                 struct ng_bridge_link *destLink;
  674                 struct mbuf *m2 = NULL;
  675 
  676                 /*
  677                  * If we have checked all the links then now
  678                  * send the original on its reserved link
  679                  */
  680                 if (linksSeen == priv->numLinks) {
  681                         /* If we never saw a good link, leave. */
  682                         if (firstLink == NULL) {
  683                                 NG_FREE_ITEM(item);
  684                                 NG_FREE_M(m);
  685                                 return (0);
  686                         }       
  687                         destLink = firstLink;
  688                 } else {
  689                         destLink = priv->links[linkNum];
  690                         if (destLink != NULL)
  691                                 linksSeen++;
  692                         /* Skip incoming link and disconnected links */
  693                         if (destLink == NULL || destLink == link) {
  694                                 continue;
  695                         }
  696                         if (firstLink == NULL) {
  697                                 /*
  698                                  * This is the first usable link we have found.
  699                                  * Reserve it for the originals.
  700                                  * If we never find another we save a copy.
  701                                  */
  702                                 firstLink = destLink;
  703                                 continue;
  704                         }
  705 
  706                         /*
  707                          * It's usable link but not the reserved (first) one.
  708                          * Copy mbuf info for sending.
  709                          */
  710                         m2 = m_dup(m, M_DONTWAIT);      /* XXX m_copypacket() */
  711                         if (m2 == NULL) {
  712                                 link->stats.memoryFailures++;
  713                                 NG_FREE_ITEM(item);
  714                                 NG_FREE_M(m);
  715                                 return (ENOBUFS);
  716                         }
  717                 }
  718 
  719                 /* Update stats */
  720                 destLink->stats.xmitPackets++;
  721                 destLink->stats.xmitOctets += m->m_pkthdr.len;
  722                 switch (manycast) {
  723                 case 0:                                 /* unicast */
  724                         break;
  725                 case 1:                                 /* multicast */
  726                         destLink->stats.xmitMulticasts++;
  727                         break;
  728                 case 2:                                 /* broadcast */
  729                         destLink->stats.xmitBroadcasts++;
  730                         break;
  731                 }
  732 
  733                 /* Send packet */
  734                 if (destLink == firstLink) { 
  735                         /*
  736                          * If we've sent all the others, send the original
  737                          * on the first link we found.
  738                          */
  739                         NG_FWD_NEW_DATA(error, item, destLink->hook, m);
  740                         break; /* always done last - not really needed. */
  741                 } else {
  742                         NG_SEND_DATA_ONLY(error, destLink->hook, m2);
  743                 }
  744         }
  745         return (error);
  746 }
  747 
  748 /*
  749  * Shutdown node
  750  */
  751 static int
  752 ng_bridge_shutdown(node_p node)
  753 {
  754         const priv_p priv = NG_NODE_PRIVATE(node);
  755 
  756         /*
  757          * Shut down everything including the timer.  Even if the
  758          * callout has already been dequeued and is about to be
  759          * run, ng_bridge_timeout() won't be fired as the node
  760          * is already marked NGF_INVALID, so we're safe to free
  761          * the node now.
  762          */
  763         KASSERT(priv->numLinks == 0 && priv->numHosts == 0,
  764             ("%s: numLinks=%d numHosts=%d",
  765             __func__, priv->numLinks, priv->numHosts));
  766         ng_uncallout(&priv->timer, node);
  767         NG_NODE_SET_PRIVATE(node, NULL);
  768         NG_NODE_UNREF(node);
  769         FREE(priv->tab, M_NETGRAPH_BRIDGE);
  770         FREE(priv, M_NETGRAPH_BRIDGE);
  771         return (0);
  772 }
  773 
  774 /*
  775  * Hook disconnection.
  776  */
  777 static int
  778 ng_bridge_disconnect(hook_p hook)
  779 {
  780         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  781         int linkNum;
  782 
  783         /* Get link number */
  784         linkNum = (intptr_t)NG_HOOK_PRIVATE(hook);
  785         KASSERT(linkNum >= 0 && linkNum < NG_BRIDGE_MAX_LINKS,
  786             ("%s: linkNum=%u", __func__, linkNum));
  787 
  788         /* Remove all hosts associated with this link */
  789         ng_bridge_remove_hosts(priv, linkNum);
  790 
  791         /* Free associated link information */
  792         KASSERT(priv->links[linkNum] != NULL, ("%s: no link", __func__));
  793         FREE(priv->links[linkNum], M_NETGRAPH_BRIDGE);
  794         priv->links[linkNum] = NULL;
  795         priv->numLinks--;
  796 
  797         /* If no more hooks, go away */
  798         if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
  799         && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) {
  800                 ng_rmnode_self(NG_HOOK_NODE(hook));
  801         }
  802         return (0);
  803 }
  804 
  805 /******************************************************************
  806                     HASH TABLE FUNCTIONS
  807 ******************************************************************/
  808 
  809 /*
  810  * Hash algorithm
  811  */
  812 #define HASH(addr,mask)         ( (((const u_int16_t *)(addr))[0]       \
  813                                  ^ ((const u_int16_t *)(addr))[1]       \
  814                                  ^ ((const u_int16_t *)(addr))[2]) & (mask) )
  815 
  816 /*
  817  * Find a host entry in the table.
  818  */
  819 static struct ng_bridge_host *
  820 ng_bridge_get(priv_p priv, const u_char *addr)
  821 {
  822         const int bucket = HASH(addr, priv->hashMask);
  823         struct ng_bridge_hent *hent;
  824 
  825         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  826                 if (ETHER_EQUAL(hent->host.addr, addr))
  827                         return (&hent->host);
  828         }
  829         return (NULL);
  830 }
  831 
  832 /*
  833  * Add a new host entry to the table. This assumes the host doesn't
  834  * already exist in the table. Returns 1 on success, 0 if there
  835  * was a memory allocation failure.
  836  */
  837 static int
  838 ng_bridge_put(priv_p priv, const u_char *addr, int linkNum)
  839 {
  840         const int bucket = HASH(addr, priv->hashMask);
  841         struct ng_bridge_hent *hent;
  842 
  843 #ifdef INVARIANTS
  844         /* Assert that entry does not already exist in hashtable */
  845         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  846                 KASSERT(!ETHER_EQUAL(hent->host.addr, addr),
  847                     ("%s: entry %6D exists in table", __func__, addr, ":"));
  848         }
  849 #endif
  850 
  851         /* Allocate and initialize new hashtable entry */
  852         MALLOC(hent, struct ng_bridge_hent *,
  853             sizeof(*hent), M_NETGRAPH_BRIDGE, M_NOWAIT);
  854         if (hent == NULL)
  855                 return (0);
  856         bcopy(addr, hent->host.addr, ETHER_ADDR_LEN);
  857         hent->host.linkNum = linkNum;
  858         hent->host.staleness = 0;
  859         hent->host.age = 0;
  860 
  861         /* Add new element to hash bucket */
  862         SLIST_INSERT_HEAD(&priv->tab[bucket], hent, next);
  863         priv->numHosts++;
  864 
  865         /* Resize table if necessary */
  866         ng_bridge_rehash(priv);
  867         return (1);
  868 }
  869 
  870 /*
  871  * Resize the hash table. We try to maintain the number of buckets
  872  * such that the load factor is in the range 0.25 to 1.0.
  873  *
  874  * If we can't get the new memory then we silently fail. This is OK
  875  * because things will still work and we'll try again soon anyway.
  876  */
  877 static void
  878 ng_bridge_rehash(priv_p priv)
  879 {
  880         struct ng_bridge_bucket *newTab;
  881         int oldBucket, newBucket;
  882         int newNumBuckets;
  883         u_int newMask;
  884 
  885         /* Is table too full or too empty? */
  886         if (priv->numHosts > priv->numBuckets
  887             && (priv->numBuckets << 1) <= MAX_BUCKETS)
  888                 newNumBuckets = priv->numBuckets << 1;
  889         else if (priv->numHosts < (priv->numBuckets >> 2)
  890             && (priv->numBuckets >> 2) >= MIN_BUCKETS)
  891                 newNumBuckets = priv->numBuckets >> 2;
  892         else
  893                 return;
  894         newMask = newNumBuckets - 1;
  895 
  896         /* Allocate and initialize new table */
  897         MALLOC(newTab, struct ng_bridge_bucket *,
  898             newNumBuckets * sizeof(*newTab), M_NETGRAPH_BRIDGE, M_NOWAIT | M_ZERO);
  899         if (newTab == NULL)
  900                 return;
  901 
  902         /* Move all entries from old table to new table */
  903         for (oldBucket = 0; oldBucket < priv->numBuckets; oldBucket++) {
  904                 struct ng_bridge_bucket *const oldList = &priv->tab[oldBucket];
  905 
  906                 while (!SLIST_EMPTY(oldList)) {
  907                         struct ng_bridge_hent *const hent
  908                             = SLIST_FIRST(oldList);
  909 
  910                         SLIST_REMOVE_HEAD(oldList, next);
  911                         newBucket = HASH(hent->host.addr, newMask);
  912                         SLIST_INSERT_HEAD(&newTab[newBucket], hent, next);
  913                 }
  914         }
  915 
  916         /* Replace old table with new one */
  917         if (priv->conf.debugLevel >= 3) {
  918                 log(LOG_INFO, "ng_bridge: %s: table size %d -> %d\n",
  919                     ng_bridge_nodename(priv->node),
  920                     priv->numBuckets, newNumBuckets);
  921         }
  922         FREE(priv->tab, M_NETGRAPH_BRIDGE);
  923         priv->numBuckets = newNumBuckets;
  924         priv->hashMask = newMask;
  925         priv->tab = newTab;
  926         return;
  927 }
  928 
  929 /******************************************************************
  930                     MISC FUNCTIONS
  931 ******************************************************************/
  932 
  933 /*
  934  * Remove all hosts associated with a specific link from the hashtable.
  935  * If linkNum == -1, then remove all hosts in the table.
  936  */
  937 static void
  938 ng_bridge_remove_hosts(priv_p priv, int linkNum)
  939 {
  940         int bucket;
  941 
  942         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  943                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
  944 
  945                 while (*hptr != NULL) {
  946                         struct ng_bridge_hent *const hent = *hptr;
  947 
  948                         if (linkNum == -1 || hent->host.linkNum == linkNum) {
  949                                 *hptr = SLIST_NEXT(hent, next);
  950                                 FREE(hent, M_NETGRAPH_BRIDGE);
  951                                 priv->numHosts--;
  952                         } else
  953                                 hptr = &SLIST_NEXT(hent, next);
  954                 }
  955         }
  956 }
  957 
  958 /*
  959  * Handle our once-per-second timeout event. We do two things:
  960  * we decrement link->loopCount for those links being muted due to
  961  * a detected loopback condition, and we remove any hosts from
  962  * the hashtable whom we haven't heard from in a long while.
  963  */
  964 static void
  965 ng_bridge_timeout(node_p node, hook_p hook, void *arg1, int arg2)
  966 {
  967         const priv_p priv = NG_NODE_PRIVATE(node);
  968         int bucket;
  969         int counter = 0;
  970         int linkNum;
  971 
  972         /* Update host time counters and remove stale entries */
  973         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  974                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
  975 
  976                 while (*hptr != NULL) {
  977                         struct ng_bridge_hent *const hent = *hptr;
  978 
  979                         /* Make sure host's link really exists */
  980                         KASSERT(priv->links[hent->host.linkNum] != NULL,
  981                             ("%s: host %6D on nonexistent link %d\n",
  982                             __func__, hent->host.addr, ":",
  983                             hent->host.linkNum));
  984 
  985                         /* Remove hosts we haven't heard from in a while */
  986                         if (++hent->host.staleness >= priv->conf.maxStaleness) {
  987                                 *hptr = SLIST_NEXT(hent, next);
  988                                 FREE(hent, M_NETGRAPH_BRIDGE);
  989                                 priv->numHosts--;
  990                         } else {
  991                                 if (hent->host.age < 0xffff)
  992                                         hent->host.age++;
  993                                 hptr = &SLIST_NEXT(hent, next);
  994                                 counter++;
  995                         }
  996                 }
  997         }
  998         KASSERT(priv->numHosts == counter,
  999             ("%s: hosts: %d != %d", __func__, priv->numHosts, counter));
 1000 
 1001         /* Decrease table size if necessary */
 1002         ng_bridge_rehash(priv);
 1003 
 1004         /* Decrease loop counter on muted looped back links */
 1005         for (counter = linkNum = 0; linkNum < NG_BRIDGE_MAX_LINKS; linkNum++) {
 1006                 struct ng_bridge_link *const link = priv->links[linkNum];
 1007 
 1008                 if (link != NULL) {
 1009                         if (link->loopCount != 0) {
 1010                                 link->loopCount--;
 1011                                 if (link->loopCount == 0
 1012                                     && priv->conf.debugLevel >= 2) {
 1013                                         log(LOG_INFO, "ng_bridge: %s:"
 1014                                             " restoring looped back link%d\n",
 1015                                             ng_bridge_nodename(node), linkNum);
 1016                                 }
 1017                         }
 1018                         counter++;
 1019                 }
 1020         }
 1021         KASSERT(priv->numLinks == counter,
 1022             ("%s: links: %d != %d", __func__, priv->numLinks, counter));
 1023 
 1024         /* Register a new timeout, keeping the existing node reference */
 1025         ng_callout(&priv->timer, node, NULL, hz, ng_bridge_timeout, NULL, 0);
 1026 }
 1027 
 1028 /*
 1029  * Return node's "name", even if it doesn't have one.
 1030  */
 1031 static const char *
 1032 ng_bridge_nodename(node_p node)
 1033 {
 1034         static char name[NG_NODESIZ];
 1035 
 1036         if (NG_NODE_NAME(node) != NULL)
 1037                 snprintf(name, sizeof(name), "%s", NG_NODE_NAME(node));
 1038         else
 1039                 snprintf(name, sizeof(name), "[%x]", ng_node2ID(node));
 1040         return name;
 1041 }
 1042 

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