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

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    1 /*
    2  * ng_bridge.c
    3  */
    4 
    5 /*-
    6  * Copyright (c) 2000 Whistle Communications, Inc.
    7  * All rights reserved.
    8  * 
    9  * Subject to the following obligations and disclaimer of warranty, use and
   10  * redistribution of this software, in source or object code forms, with or
   11  * without modifications are expressly permitted by Whistle Communications;
   12  * provided, however, that:
   13  * 1. Any and all reproductions of the source or object code must include the
   14  *    copyright notice above and the following disclaimer of warranties; and
   15  * 2. No rights are granted, in any manner or form, to use Whistle
   16  *    Communications, Inc. trademarks, including the mark "WHISTLE
   17  *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
   18  *    such appears in the above copyright notice or in the software.
   19  * 
   20  * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
   21  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
   22  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
   23  * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
   24  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
   25  * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
   26  * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
   27  * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
   28  * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
   29  * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
   30  * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
   31  * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
   32  * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
   33  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   34  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   35  * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
   36  * OF SUCH DAMAGE.
   37  *
   38  * Author: Archie Cobbs <archie@freebsd.org>
   39  *
   40  * $FreeBSD: releng/8.0/sys/netgraph/ng_bridge.c 196019 2009-08-01 19:26:27Z rwatson $
   41  */
   42 
   43 /*
   44  * ng_bridge(4) netgraph node type
   45  *
   46  * The node performs standard intelligent Ethernet bridging over
   47  * each of its connected hooks, or links.  A simple loop detection
   48  * algorithm is included which disables a link for priv->conf.loopTimeout
   49  * seconds when a host is seen to have jumped from one link to
   50  * another within priv->conf.minStableAge seconds.
   51  *
   52  * We keep a hashtable that maps Ethernet addresses to host info,
   53  * which is contained in struct ng_bridge_host's. These structures
   54  * tell us on which link the host may be found. A host's entry will
   55  * expire after priv->conf.maxStaleness seconds.
   56  *
   57  * This node is optimzed for stable networks, where machines jump
   58  * from one port to the other only rarely.
   59  */
   60 
   61 #include <sys/param.h>
   62 #include <sys/systm.h>
   63 #include <sys/kernel.h>
   64 #include <sys/lock.h>
   65 #include <sys/malloc.h>
   66 #include <sys/mbuf.h>
   67 #include <sys/errno.h>
   68 #include <sys/rwlock.h>
   69 #include <sys/syslog.h>
   70 #include <sys/socket.h>
   71 #include <sys/ctype.h>
   72 
   73 #include <net/if.h>
   74 #include <net/ethernet.h>
   75 #include <net/vnet.h>
   76 
   77 #include <netinet/in.h>
   78 #include <netinet/ip_fw.h>
   79 
   80 #include <netgraph/ng_message.h>
   81 #include <netgraph/netgraph.h>
   82 #include <netgraph/ng_parse.h>
   83 #include <netgraph/ng_bridge.h>
   84 
   85 #ifdef NG_SEPARATE_MALLOC
   86 MALLOC_DEFINE(M_NETGRAPH_BRIDGE, "netgraph_bridge", "netgraph bridge node ");
   87 #else
   88 #define M_NETGRAPH_BRIDGE M_NETGRAPH
   89 #endif
   90 
   91 /* Per-link private data */
   92 struct ng_bridge_link {
   93         hook_p                          hook;           /* netgraph hook */
   94         u_int16_t                       loopCount;      /* loop ignore timer */
   95         struct ng_bridge_link_stats     stats;          /* link stats */
   96 };
   97 
   98 /* Per-node private data */
   99 struct ng_bridge_private {
  100         struct ng_bridge_bucket *tab;           /* hash table bucket array */
  101         struct ng_bridge_link   *links[NG_BRIDGE_MAX_LINKS];
  102         struct ng_bridge_config conf;           /* node configuration */
  103         node_p                  node;           /* netgraph node */
  104         u_int                   numHosts;       /* num entries in table */
  105         u_int                   numBuckets;     /* num buckets in table */
  106         u_int                   hashMask;       /* numBuckets - 1 */
  107         int                     numLinks;       /* num connected links */
  108         struct callout          timer;          /* one second periodic timer */
  109 };
  110 typedef struct ng_bridge_private *priv_p;
  111 
  112 /* Information about a host, stored in a hash table entry */
  113 struct ng_bridge_hent {
  114         struct ng_bridge_host           host;   /* actual host info */
  115         SLIST_ENTRY(ng_bridge_hent)     next;   /* next entry in bucket */
  116 };
  117 
  118 /* Hash table bucket declaration */
  119 SLIST_HEAD(ng_bridge_bucket, ng_bridge_hent);
  120 
  121 /* Netgraph node methods */
  122 static ng_constructor_t ng_bridge_constructor;
  123 static ng_rcvmsg_t      ng_bridge_rcvmsg;
  124 static ng_shutdown_t    ng_bridge_shutdown;
  125 static ng_newhook_t     ng_bridge_newhook;
  126 static ng_rcvdata_t     ng_bridge_rcvdata;
  127 static ng_disconnect_t  ng_bridge_disconnect;
  128 
  129 /* Other internal functions */
  130 static struct   ng_bridge_host *ng_bridge_get(priv_p priv, const u_char *addr);
  131 static int      ng_bridge_put(priv_p priv, const u_char *addr, int linkNum);
  132 static void     ng_bridge_rehash(priv_p priv);
  133 static void     ng_bridge_remove_hosts(priv_p priv, int linkNum);
  134 static void     ng_bridge_timeout(node_p node, hook_p hook, void *arg1, int arg2);
  135 static const    char *ng_bridge_nodename(node_p node);
  136 
  137 /* Ethernet broadcast */
  138 static const u_char ng_bridge_bcast_addr[ETHER_ADDR_LEN] =
  139     { 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
  140 
  141 /* Store each hook's link number in the private field */
  142 #define LINK_NUM(hook)          (*(u_int16_t *)(&(hook)->private))
  143 
  144 /* Compare Ethernet addresses using 32 and 16 bit words instead of bytewise */
  145 #define ETHER_EQUAL(a,b)        (((const u_int32_t *)(a))[0] \
  146                                         == ((const u_int32_t *)(b))[0] \
  147                                     && ((const u_int16_t *)(a))[2] \
  148                                         == ((const u_int16_t *)(b))[2])
  149 
  150 /* Minimum and maximum number of hash buckets. Must be a power of two. */
  151 #define MIN_BUCKETS             (1 << 5)        /* 32 */
  152 #define MAX_BUCKETS             (1 << 14)       /* 16384 */
  153 
  154 /* Configuration default values */
  155 #define DEFAULT_LOOP_TIMEOUT    60
  156 #define DEFAULT_MAX_STALENESS   (15 * 60)       /* same as ARP timeout */
  157 #define DEFAULT_MIN_STABLE_AGE  1
  158 
  159 /******************************************************************
  160                     NETGRAPH PARSE TYPES
  161 ******************************************************************/
  162 
  163 /*
  164  * How to determine the length of the table returned by NGM_BRIDGE_GET_TABLE
  165  */
  166 static int
  167 ng_bridge_getTableLength(const struct ng_parse_type *type,
  168         const u_char *start, const u_char *buf)
  169 {
  170         const struct ng_bridge_host_ary *const hary
  171             = (const struct ng_bridge_host_ary *)(buf - sizeof(u_int32_t));
  172 
  173         return hary->numHosts;
  174 }
  175 
  176 /* Parse type for struct ng_bridge_host_ary */
  177 static const struct ng_parse_struct_field ng_bridge_host_type_fields[]
  178         = NG_BRIDGE_HOST_TYPE_INFO(&ng_parse_enaddr_type);
  179 static const struct ng_parse_type ng_bridge_host_type = {
  180         &ng_parse_struct_type,
  181         &ng_bridge_host_type_fields
  182 };
  183 static const struct ng_parse_array_info ng_bridge_hary_type_info = {
  184         &ng_bridge_host_type,
  185         ng_bridge_getTableLength
  186 };
  187 static const struct ng_parse_type ng_bridge_hary_type = {
  188         &ng_parse_array_type,
  189         &ng_bridge_hary_type_info
  190 };
  191 static const struct ng_parse_struct_field ng_bridge_host_ary_type_fields[]
  192         = NG_BRIDGE_HOST_ARY_TYPE_INFO(&ng_bridge_hary_type);
  193 static const struct ng_parse_type ng_bridge_host_ary_type = {
  194         &ng_parse_struct_type,
  195         &ng_bridge_host_ary_type_fields
  196 };
  197 
  198 /* Parse type for struct ng_bridge_config */
  199 static const struct ng_parse_fixedarray_info ng_bridge_ipfwary_type_info = {
  200         &ng_parse_uint8_type,
  201         NG_BRIDGE_MAX_LINKS
  202 };
  203 static const struct ng_parse_type ng_bridge_ipfwary_type = {
  204         &ng_parse_fixedarray_type,
  205         &ng_bridge_ipfwary_type_info
  206 };
  207 static const struct ng_parse_struct_field ng_bridge_config_type_fields[]
  208         = NG_BRIDGE_CONFIG_TYPE_INFO(&ng_bridge_ipfwary_type);
  209 static const struct ng_parse_type ng_bridge_config_type = {
  210         &ng_parse_struct_type,
  211         &ng_bridge_config_type_fields
  212 };
  213 
  214 /* Parse type for struct ng_bridge_link_stat */
  215 static const struct ng_parse_struct_field ng_bridge_stats_type_fields[]
  216         = NG_BRIDGE_STATS_TYPE_INFO;
  217 static const struct ng_parse_type ng_bridge_stats_type = {
  218         &ng_parse_struct_type,
  219         &ng_bridge_stats_type_fields
  220 };
  221 
  222 /* List of commands and how to convert arguments to/from ASCII */
  223 static const struct ng_cmdlist ng_bridge_cmdlist[] = {
  224         {
  225           NGM_BRIDGE_COOKIE,
  226           NGM_BRIDGE_SET_CONFIG,
  227           "setconfig",
  228           &ng_bridge_config_type,
  229           NULL
  230         },
  231         {
  232           NGM_BRIDGE_COOKIE,
  233           NGM_BRIDGE_GET_CONFIG,
  234           "getconfig",
  235           NULL,
  236           &ng_bridge_config_type
  237         },
  238         {
  239           NGM_BRIDGE_COOKIE,
  240           NGM_BRIDGE_RESET,
  241           "reset",
  242           NULL,
  243           NULL
  244         },
  245         {
  246           NGM_BRIDGE_COOKIE,
  247           NGM_BRIDGE_GET_STATS,
  248           "getstats",
  249           &ng_parse_uint32_type,
  250           &ng_bridge_stats_type
  251         },
  252         {
  253           NGM_BRIDGE_COOKIE,
  254           NGM_BRIDGE_CLR_STATS,
  255           "clrstats",
  256           &ng_parse_uint32_type,
  257           NULL
  258         },
  259         {
  260           NGM_BRIDGE_COOKIE,
  261           NGM_BRIDGE_GETCLR_STATS,
  262           "getclrstats",
  263           &ng_parse_uint32_type,
  264           &ng_bridge_stats_type
  265         },
  266         {
  267           NGM_BRIDGE_COOKIE,
  268           NGM_BRIDGE_GET_TABLE,
  269           "gettable",
  270           NULL,
  271           &ng_bridge_host_ary_type
  272         },
  273         { 0 }
  274 };
  275 
  276 /* Node type descriptor */
  277 static struct ng_type ng_bridge_typestruct = {
  278         .version =      NG_ABI_VERSION,
  279         .name =         NG_BRIDGE_NODE_TYPE,
  280         .constructor =  ng_bridge_constructor,
  281         .rcvmsg =       ng_bridge_rcvmsg,
  282         .shutdown =     ng_bridge_shutdown,
  283         .newhook =      ng_bridge_newhook,
  284         .rcvdata =      ng_bridge_rcvdata,
  285         .disconnect =   ng_bridge_disconnect,
  286         .cmdlist =      ng_bridge_cmdlist,
  287 };
  288 NETGRAPH_INIT(bridge, &ng_bridge_typestruct);
  289 
  290 /******************************************************************
  291                     NETGRAPH NODE METHODS
  292 ******************************************************************/
  293 
  294 /*
  295  * Node constructor
  296  */
  297 static int
  298 ng_bridge_constructor(node_p node)
  299 {
  300         priv_p priv;
  301 
  302         /* Allocate and initialize private info */
  303         priv = malloc(sizeof(*priv), M_NETGRAPH_BRIDGE, M_NOWAIT | M_ZERO);
  304         if (priv == NULL)
  305                 return (ENOMEM);
  306         ng_callout_init(&priv->timer);
  307 
  308         /* Allocate and initialize hash table, etc. */
  309         priv->tab = malloc(MIN_BUCKETS * sizeof(*priv->tab),
  310             M_NETGRAPH_BRIDGE, M_NOWAIT | M_ZERO);
  311         if (priv->tab == NULL) {
  312                 free(priv, M_NETGRAPH_BRIDGE);
  313                 return (ENOMEM);
  314         }
  315         priv->numBuckets = MIN_BUCKETS;
  316         priv->hashMask = MIN_BUCKETS - 1;
  317         priv->conf.debugLevel = 1;
  318         priv->conf.loopTimeout = DEFAULT_LOOP_TIMEOUT;
  319         priv->conf.maxStaleness = DEFAULT_MAX_STALENESS;
  320         priv->conf.minStableAge = DEFAULT_MIN_STABLE_AGE;
  321 
  322         /*
  323          * This node has all kinds of stuff that could be screwed by SMP.
  324          * Until it gets it's own internal protection, we go through in 
  325          * single file. This could hurt a machine bridging beteen two 
  326          * GB ethernets so it should be fixed. 
  327          * When it's fixed the process SHOULD NOT SLEEP, spinlocks please!
  328          * (and atomic ops )
  329          */
  330         NG_NODE_FORCE_WRITER(node);
  331         NG_NODE_SET_PRIVATE(node, priv);
  332         priv->node = node;
  333 
  334         /* Start timer; timer is always running while node is alive */
  335         ng_callout(&priv->timer, node, NULL, hz, ng_bridge_timeout, NULL, 0);
  336 
  337         /* Done */
  338         return (0);
  339 }
  340 
  341 /*
  342  * Method for attaching a new hook
  343  */
  344 static  int
  345 ng_bridge_newhook(node_p node, hook_p hook, const char *name)
  346 {
  347         const priv_p priv = NG_NODE_PRIVATE(node);
  348 
  349         /* Check for a link hook */
  350         if (strncmp(name, NG_BRIDGE_HOOK_LINK_PREFIX,
  351             strlen(NG_BRIDGE_HOOK_LINK_PREFIX)) == 0) {
  352                 const char *cp;
  353                 char *eptr;
  354                 u_long linkNum;
  355 
  356                 cp = name + strlen(NG_BRIDGE_HOOK_LINK_PREFIX);
  357                 if (!isdigit(*cp) || (cp[0] == '' && cp[1] != '\0'))
  358                         return (EINVAL);
  359                 linkNum = strtoul(cp, &eptr, 10);
  360                 if (*eptr != '\0' || linkNum >= NG_BRIDGE_MAX_LINKS)
  361                         return (EINVAL);
  362                 if (priv->links[linkNum] != NULL)
  363                         return (EISCONN);
  364                 priv->links[linkNum] = malloc(sizeof(*priv->links[linkNum]),
  365                     M_NETGRAPH_BRIDGE, M_NOWAIT|M_ZERO);
  366                 if (priv->links[linkNum] == NULL)
  367                         return (ENOMEM);
  368                 priv->links[linkNum]->hook = hook;
  369                 NG_HOOK_SET_PRIVATE(hook, (void *)linkNum);
  370                 priv->numLinks++;
  371                 return (0);
  372         }
  373 
  374         /* Unknown hook name */
  375         return (EINVAL);
  376 }
  377 
  378 /*
  379  * Receive a control message
  380  */
  381 static int
  382 ng_bridge_rcvmsg(node_p node, item_p item, hook_p lasthook)
  383 {
  384         const priv_p priv = NG_NODE_PRIVATE(node);
  385         struct ng_mesg *resp = NULL;
  386         int error = 0;
  387         struct ng_mesg *msg;
  388 
  389         NGI_GET_MSG(item, msg);
  390         switch (msg->header.typecookie) {
  391         case NGM_BRIDGE_COOKIE:
  392                 switch (msg->header.cmd) {
  393                 case NGM_BRIDGE_GET_CONFIG:
  394                     {
  395                         struct ng_bridge_config *conf;
  396 
  397                         NG_MKRESPONSE(resp, msg,
  398                             sizeof(struct ng_bridge_config), M_NOWAIT);
  399                         if (resp == NULL) {
  400                                 error = ENOMEM;
  401                                 break;
  402                         }
  403                         conf = (struct ng_bridge_config *)resp->data;
  404                         *conf = priv->conf;     /* no sanity checking needed */
  405                         break;
  406                     }
  407                 case NGM_BRIDGE_SET_CONFIG:
  408                     {
  409                         struct ng_bridge_config *conf;
  410                         int i;
  411 
  412                         if (msg->header.arglen
  413                             != sizeof(struct ng_bridge_config)) {
  414                                 error = EINVAL;
  415                                 break;
  416                         }
  417                         conf = (struct ng_bridge_config *)msg->data;
  418                         priv->conf = *conf;
  419                         for (i = 0; i < NG_BRIDGE_MAX_LINKS; i++)
  420                                 priv->conf.ipfw[i] = !!priv->conf.ipfw[i];
  421                         break;
  422                     }
  423                 case NGM_BRIDGE_RESET:
  424                     {
  425                         int i;
  426 
  427                         /* Flush all entries in the hash table */
  428                         ng_bridge_remove_hosts(priv, -1);
  429 
  430                         /* Reset all loop detection counters and stats */
  431                         for (i = 0; i < NG_BRIDGE_MAX_LINKS; i++) {
  432                                 if (priv->links[i] == NULL)
  433                                         continue;
  434                                 priv->links[i]->loopCount = 0;
  435                                 bzero(&priv->links[i]->stats,
  436                                     sizeof(priv->links[i]->stats));
  437                         }
  438                         break;
  439                     }
  440                 case NGM_BRIDGE_GET_STATS:
  441                 case NGM_BRIDGE_CLR_STATS:
  442                 case NGM_BRIDGE_GETCLR_STATS:
  443                     {
  444                         struct ng_bridge_link *link;
  445                         int linkNum;
  446 
  447                         /* Get link number */
  448                         if (msg->header.arglen != sizeof(u_int32_t)) {
  449                                 error = EINVAL;
  450                                 break;
  451                         }
  452                         linkNum = *((u_int32_t *)msg->data);
  453                         if (linkNum < 0 || linkNum >= NG_BRIDGE_MAX_LINKS) {
  454                                 error = EINVAL;
  455                                 break;
  456                         }
  457                         if ((link = priv->links[linkNum]) == NULL) {
  458                                 error = ENOTCONN;
  459                                 break;
  460                         }
  461 
  462                         /* Get/clear stats */
  463                         if (msg->header.cmd != NGM_BRIDGE_CLR_STATS) {
  464                                 NG_MKRESPONSE(resp, msg,
  465                                     sizeof(link->stats), M_NOWAIT);
  466                                 if (resp == NULL) {
  467                                         error = ENOMEM;
  468                                         break;
  469                                 }
  470                                 bcopy(&link->stats,
  471                                     resp->data, sizeof(link->stats));
  472                         }
  473                         if (msg->header.cmd != NGM_BRIDGE_GET_STATS)
  474                                 bzero(&link->stats, sizeof(link->stats));
  475                         break;
  476                     }
  477                 case NGM_BRIDGE_GET_TABLE:
  478                     {
  479                         struct ng_bridge_host_ary *ary;
  480                         struct ng_bridge_hent *hent;
  481                         int i = 0, bucket;
  482 
  483                         NG_MKRESPONSE(resp, msg, sizeof(*ary)
  484                             + (priv->numHosts * sizeof(*ary->hosts)), M_NOWAIT);
  485                         if (resp == NULL) {
  486                                 error = ENOMEM;
  487                                 break;
  488                         }
  489                         ary = (struct ng_bridge_host_ary *)resp->data;
  490                         ary->numHosts = priv->numHosts;
  491                         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  492                                 SLIST_FOREACH(hent, &priv->tab[bucket], next)
  493                                         ary->hosts[i++] = hent->host;
  494                         }
  495                         break;
  496                     }
  497                 default:
  498                         error = EINVAL;
  499                         break;
  500                 }
  501                 break;
  502         default:
  503                 error = EINVAL;
  504                 break;
  505         }
  506 
  507         /* Done */
  508         NG_RESPOND_MSG(error, node, item, resp);
  509         NG_FREE_MSG(msg);
  510         return (error);
  511 }
  512 
  513 /*
  514  * Receive data on a hook
  515  */
  516 static int
  517 ng_bridge_rcvdata(hook_p hook, item_p item)
  518 {
  519         const node_p node = NG_HOOK_NODE(hook);
  520         const priv_p priv = NG_NODE_PRIVATE(node);
  521         struct ng_bridge_host *host;
  522         struct ng_bridge_link *link;
  523         struct ether_header *eh;
  524         int error = 0, linkNum, linksSeen;
  525         int manycast;
  526         struct mbuf *m;
  527         struct ng_bridge_link *firstLink;
  528 
  529         NGI_GET_M(item, m);
  530         /* Get link number */
  531         linkNum = (intptr_t)NG_HOOK_PRIVATE(hook);
  532         KASSERT(linkNum >= 0 && linkNum < NG_BRIDGE_MAX_LINKS,
  533             ("%s: linkNum=%u", __func__, linkNum));
  534         link = priv->links[linkNum];
  535         KASSERT(link != NULL, ("%s: link%d null", __func__, linkNum));
  536 
  537         /* Sanity check packet and pull up header */
  538         if (m->m_pkthdr.len < ETHER_HDR_LEN) {
  539                 link->stats.recvRunts++;
  540                 NG_FREE_ITEM(item);
  541                 NG_FREE_M(m);
  542                 return (EINVAL);
  543         }
  544         if (m->m_len < ETHER_HDR_LEN && !(m = m_pullup(m, ETHER_HDR_LEN))) {
  545                 link->stats.memoryFailures++;
  546                 NG_FREE_ITEM(item);
  547                 return (ENOBUFS);
  548         }
  549         eh = mtod(m, struct ether_header *);
  550         if ((eh->ether_shost[0] & 1) != 0) {
  551                 link->stats.recvInvalid++;
  552                 NG_FREE_ITEM(item);
  553                 NG_FREE_M(m);
  554                 return (EINVAL);
  555         }
  556 
  557         /* Is link disabled due to a loopback condition? */
  558         if (link->loopCount != 0) {
  559                 link->stats.loopDrops++;
  560                 NG_FREE_ITEM(item);
  561                 NG_FREE_M(m);
  562                 return (ELOOP);         /* XXX is this an appropriate error? */
  563         }
  564 
  565         /* Update stats */
  566         link->stats.recvPackets++;
  567         link->stats.recvOctets += m->m_pkthdr.len;
  568         if ((manycast = (eh->ether_dhost[0] & 1)) != 0) {
  569                 if (ETHER_EQUAL(eh->ether_dhost, ng_bridge_bcast_addr)) {
  570                         link->stats.recvBroadcasts++;
  571                         manycast = 2;
  572                 } else
  573                         link->stats.recvMulticasts++;
  574         }
  575 
  576         /* Look up packet's source Ethernet address in hashtable */
  577         if ((host = ng_bridge_get(priv, eh->ether_shost)) != NULL) {
  578 
  579                 /* Update time since last heard from this host */
  580                 host->staleness = 0;
  581 
  582                 /* Did host jump to a different link? */
  583                 if (host->linkNum != linkNum) {
  584 
  585                         /*
  586                          * If the host's old link was recently established
  587                          * on the old link and it's already jumped to a new
  588                          * link, declare a loopback condition.
  589                          */
  590                         if (host->age < priv->conf.minStableAge) {
  591 
  592                                 /* Log the problem */
  593                                 if (priv->conf.debugLevel >= 2) {
  594                                         struct ifnet *ifp = m->m_pkthdr.rcvif;
  595                                         char suffix[32];
  596 
  597                                         if (ifp != NULL)
  598                                                 snprintf(suffix, sizeof(suffix),
  599                                                     " (%s)", ifp->if_xname);
  600                                         else
  601                                                 *suffix = '\0';
  602                                         log(LOG_WARNING, "ng_bridge: %s:"
  603                                             " loopback detected on %s%s\n",
  604                                             ng_bridge_nodename(node),
  605                                             NG_HOOK_NAME(hook), suffix);
  606                                 }
  607 
  608                                 /* Mark link as linka non grata */
  609                                 link->loopCount = priv->conf.loopTimeout;
  610                                 link->stats.loopDetects++;
  611 
  612                                 /* Forget all hosts on this link */
  613                                 ng_bridge_remove_hosts(priv, linkNum);
  614 
  615                                 /* Drop packet */
  616                                 link->stats.loopDrops++;
  617                                 NG_FREE_ITEM(item);
  618                                 NG_FREE_M(m);
  619                                 return (ELOOP);         /* XXX appropriate? */
  620                         }
  621 
  622                         /* Move host over to new link */
  623                         host->linkNum = linkNum;
  624                         host->age = 0;
  625                 }
  626         } else {
  627                 if (!ng_bridge_put(priv, eh->ether_shost, linkNum)) {
  628                         link->stats.memoryFailures++;
  629                         NG_FREE_ITEM(item);
  630                         NG_FREE_M(m);
  631                         return (ENOMEM);
  632                 }
  633         }
  634 
  635         /* Run packet through ipfw processing, if enabled */
  636 #if 0
  637         if (priv->conf.ipfw[linkNum] && V_fw_enable && ip_fw_chk_ptr != NULL) {
  638                 /* XXX not implemented yet */
  639         }
  640 #endif
  641 
  642         /*
  643          * If unicast and destination host known, deliver to host's link,
  644          * unless it is the same link as the packet came in on.
  645          */
  646         if (!manycast) {
  647 
  648                 /* Determine packet destination link */
  649                 if ((host = ng_bridge_get(priv, eh->ether_dhost)) != NULL) {
  650                         struct ng_bridge_link *const destLink
  651                             = priv->links[host->linkNum];
  652 
  653                         /* If destination same as incoming link, do nothing */
  654                         KASSERT(destLink != NULL,
  655                             ("%s: link%d null", __func__, host->linkNum));
  656                         if (destLink == link) {
  657                                 NG_FREE_ITEM(item);
  658                                 NG_FREE_M(m);
  659                                 return (0);
  660                         }
  661 
  662                         /* Deliver packet out the destination link */
  663                         destLink->stats.xmitPackets++;
  664                         destLink->stats.xmitOctets += m->m_pkthdr.len;
  665                         NG_FWD_NEW_DATA(error, item, destLink->hook, m);
  666                         return (error);
  667                 }
  668 
  669                 /* Destination host is not known */
  670                 link->stats.recvUnknown++;
  671         }
  672 
  673         /* Distribute unknown, multicast, broadcast pkts to all other links */
  674         firstLink = NULL;
  675         for (linkNum = linksSeen = 0; linksSeen <= priv->numLinks; linkNum++) {
  676                 struct ng_bridge_link *destLink;
  677                 struct mbuf *m2 = NULL;
  678 
  679                 /*
  680                  * If we have checked all the links then now
  681                  * send the original on its reserved link
  682                  */
  683                 if (linksSeen == priv->numLinks) {
  684                         /* If we never saw a good link, leave. */
  685                         if (firstLink == NULL) {
  686                                 NG_FREE_ITEM(item);
  687                                 NG_FREE_M(m);
  688                                 return (0);
  689                         }       
  690                         destLink = firstLink;
  691                 } else {
  692                         destLink = priv->links[linkNum];
  693                         if (destLink != NULL)
  694                                 linksSeen++;
  695                         /* Skip incoming link and disconnected links */
  696                         if (destLink == NULL || destLink == link) {
  697                                 continue;
  698                         }
  699                         if (firstLink == NULL) {
  700                                 /*
  701                                  * This is the first usable link we have found.
  702                                  * Reserve it for the originals.
  703                                  * If we never find another we save a copy.
  704                                  */
  705                                 firstLink = destLink;
  706                                 continue;
  707                         }
  708 
  709                         /*
  710                          * It's usable link but not the reserved (first) one.
  711                          * Copy mbuf info for sending.
  712                          */
  713                         m2 = m_dup(m, M_DONTWAIT);      /* XXX m_copypacket() */
  714                         if (m2 == NULL) {
  715                                 link->stats.memoryFailures++;
  716                                 NG_FREE_ITEM(item);
  717                                 NG_FREE_M(m);
  718                                 return (ENOBUFS);
  719                         }
  720                 }
  721 
  722                 /* Update stats */
  723                 destLink->stats.xmitPackets++;
  724                 destLink->stats.xmitOctets += m->m_pkthdr.len;
  725                 switch (manycast) {
  726                 case 0:                                 /* unicast */
  727                         break;
  728                 case 1:                                 /* multicast */
  729                         destLink->stats.xmitMulticasts++;
  730                         break;
  731                 case 2:                                 /* broadcast */
  732                         destLink->stats.xmitBroadcasts++;
  733                         break;
  734                 }
  735 
  736                 /* Send packet */
  737                 if (destLink == firstLink) { 
  738                         /*
  739                          * If we've sent all the others, send the original
  740                          * on the first link we found.
  741                          */
  742                         NG_FWD_NEW_DATA(error, item, destLink->hook, m);
  743                         break; /* always done last - not really needed. */
  744                 } else {
  745                         NG_SEND_DATA_ONLY(error, destLink->hook, m2);
  746                 }
  747         }
  748         return (error);
  749 }
  750 
  751 /*
  752  * Shutdown node
  753  */
  754 static int
  755 ng_bridge_shutdown(node_p node)
  756 {
  757         const priv_p priv = NG_NODE_PRIVATE(node);
  758 
  759         /*
  760          * Shut down everything including the timer.  Even if the
  761          * callout has already been dequeued and is about to be
  762          * run, ng_bridge_timeout() won't be fired as the node
  763          * is already marked NGF_INVALID, so we're safe to free
  764          * the node now.
  765          */
  766         KASSERT(priv->numLinks == 0 && priv->numHosts == 0,
  767             ("%s: numLinks=%d numHosts=%d",
  768             __func__, priv->numLinks, priv->numHosts));
  769         ng_uncallout(&priv->timer, node);
  770         NG_NODE_SET_PRIVATE(node, NULL);
  771         NG_NODE_UNREF(node);
  772         free(priv->tab, M_NETGRAPH_BRIDGE);
  773         free(priv, M_NETGRAPH_BRIDGE);
  774         return (0);
  775 }
  776 
  777 /*
  778  * Hook disconnection.
  779  */
  780 static int
  781 ng_bridge_disconnect(hook_p hook)
  782 {
  783         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  784         int linkNum;
  785 
  786         /* Get link number */
  787         linkNum = (intptr_t)NG_HOOK_PRIVATE(hook);
  788         KASSERT(linkNum >= 0 && linkNum < NG_BRIDGE_MAX_LINKS,
  789             ("%s: linkNum=%u", __func__, linkNum));
  790 
  791         /* Remove all hosts associated with this link */
  792         ng_bridge_remove_hosts(priv, linkNum);
  793 
  794         /* Free associated link information */
  795         KASSERT(priv->links[linkNum] != NULL, ("%s: no link", __func__));
  796         free(priv->links[linkNum], M_NETGRAPH_BRIDGE);
  797         priv->links[linkNum] = NULL;
  798         priv->numLinks--;
  799 
  800         /* If no more hooks, go away */
  801         if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
  802         && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) {
  803                 ng_rmnode_self(NG_HOOK_NODE(hook));
  804         }
  805         return (0);
  806 }
  807 
  808 /******************************************************************
  809                     HASH TABLE FUNCTIONS
  810 ******************************************************************/
  811 
  812 /*
  813  * Hash algorithm
  814  */
  815 #define HASH(addr,mask)         ( (((const u_int16_t *)(addr))[0]       \
  816                                  ^ ((const u_int16_t *)(addr))[1]       \
  817                                  ^ ((const u_int16_t *)(addr))[2]) & (mask) )
  818 
  819 /*
  820  * Find a host entry in the table.
  821  */
  822 static struct ng_bridge_host *
  823 ng_bridge_get(priv_p priv, const u_char *addr)
  824 {
  825         const int bucket = HASH(addr, priv->hashMask);
  826         struct ng_bridge_hent *hent;
  827 
  828         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  829                 if (ETHER_EQUAL(hent->host.addr, addr))
  830                         return (&hent->host);
  831         }
  832         return (NULL);
  833 }
  834 
  835 /*
  836  * Add a new host entry to the table. This assumes the host doesn't
  837  * already exist in the table. Returns 1 on success, 0 if there
  838  * was a memory allocation failure.
  839  */
  840 static int
  841 ng_bridge_put(priv_p priv, const u_char *addr, int linkNum)
  842 {
  843         const int bucket = HASH(addr, priv->hashMask);
  844         struct ng_bridge_hent *hent;
  845 
  846 #ifdef INVARIANTS
  847         /* Assert that entry does not already exist in hashtable */
  848         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  849                 KASSERT(!ETHER_EQUAL(hent->host.addr, addr),
  850                     ("%s: entry %6D exists in table", __func__, addr, ":"));
  851         }
  852 #endif
  853 
  854         /* Allocate and initialize new hashtable entry */
  855         hent = malloc(sizeof(*hent), M_NETGRAPH_BRIDGE, M_NOWAIT);
  856         if (hent == NULL)
  857                 return (0);
  858         bcopy(addr, hent->host.addr, ETHER_ADDR_LEN);
  859         hent->host.linkNum = linkNum;
  860         hent->host.staleness = 0;
  861         hent->host.age = 0;
  862 
  863         /* Add new element to hash bucket */
  864         SLIST_INSERT_HEAD(&priv->tab[bucket], hent, next);
  865         priv->numHosts++;
  866 
  867         /* Resize table if necessary */
  868         ng_bridge_rehash(priv);
  869         return (1);
  870 }
  871 
  872 /*
  873  * Resize the hash table. We try to maintain the number of buckets
  874  * such that the load factor is in the range 0.25 to 1.0.
  875  *
  876  * If we can't get the new memory then we silently fail. This is OK
  877  * because things will still work and we'll try again soon anyway.
  878  */
  879 static void
  880 ng_bridge_rehash(priv_p priv)
  881 {
  882         struct ng_bridge_bucket *newTab;
  883         int oldBucket, newBucket;
  884         int newNumBuckets;
  885         u_int newMask;
  886 
  887         /* Is table too full or too empty? */
  888         if (priv->numHosts > priv->numBuckets
  889             && (priv->numBuckets << 1) <= MAX_BUCKETS)
  890                 newNumBuckets = priv->numBuckets << 1;
  891         else if (priv->numHosts < (priv->numBuckets >> 2)
  892             && (priv->numBuckets >> 2) >= MIN_BUCKETS)
  893                 newNumBuckets = priv->numBuckets >> 2;
  894         else
  895                 return;
  896         newMask = newNumBuckets - 1;
  897 
  898         /* Allocate and initialize new table */
  899         newTab = malloc(newNumBuckets * sizeof(*newTab),
  900             M_NETGRAPH_BRIDGE, M_NOWAIT | M_ZERO);
  901         if (newTab == NULL)
  902                 return;
  903 
  904         /* Move all entries from old table to new table */
  905         for (oldBucket = 0; oldBucket < priv->numBuckets; oldBucket++) {
  906                 struct ng_bridge_bucket *const oldList = &priv->tab[oldBucket];
  907 
  908                 while (!SLIST_EMPTY(oldList)) {
  909                         struct ng_bridge_hent *const hent
  910                             = SLIST_FIRST(oldList);
  911 
  912                         SLIST_REMOVE_HEAD(oldList, next);
  913                         newBucket = HASH(hent->host.addr, newMask);
  914                         SLIST_INSERT_HEAD(&newTab[newBucket], hent, next);
  915                 }
  916         }
  917 
  918         /* Replace old table with new one */
  919         if (priv->conf.debugLevel >= 3) {
  920                 log(LOG_INFO, "ng_bridge: %s: table size %d -> %d\n",
  921                     ng_bridge_nodename(priv->node),
  922                     priv->numBuckets, newNumBuckets);
  923         }
  924         free(priv->tab, M_NETGRAPH_BRIDGE);
  925         priv->numBuckets = newNumBuckets;
  926         priv->hashMask = newMask;
  927         priv->tab = newTab;
  928         return;
  929 }
  930 
  931 /******************************************************************
  932                     MISC FUNCTIONS
  933 ******************************************************************/
  934 
  935 /*
  936  * Remove all hosts associated with a specific link from the hashtable.
  937  * If linkNum == -1, then remove all hosts in the table.
  938  */
  939 static void
  940 ng_bridge_remove_hosts(priv_p priv, int linkNum)
  941 {
  942         int bucket;
  943 
  944         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  945                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
  946 
  947                 while (*hptr != NULL) {
  948                         struct ng_bridge_hent *const hent = *hptr;
  949 
  950                         if (linkNum == -1 || hent->host.linkNum == linkNum) {
  951                                 *hptr = SLIST_NEXT(hent, next);
  952                                 free(hent, M_NETGRAPH_BRIDGE);
  953                                 priv->numHosts--;
  954                         } else
  955                                 hptr = &SLIST_NEXT(hent, next);
  956                 }
  957         }
  958 }
  959 
  960 /*
  961  * Handle our once-per-second timeout event. We do two things:
  962  * we decrement link->loopCount for those links being muted due to
  963  * a detected loopback condition, and we remove any hosts from
  964  * the hashtable whom we haven't heard from in a long while.
  965  */
  966 static void
  967 ng_bridge_timeout(node_p node, hook_p hook, void *arg1, int arg2)
  968 {
  969         const priv_p priv = NG_NODE_PRIVATE(node);
  970         int bucket;
  971         int counter = 0;
  972         int linkNum;
  973 
  974         /* Update host time counters and remove stale entries */
  975         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  976                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
  977 
  978                 while (*hptr != NULL) {
  979                         struct ng_bridge_hent *const hent = *hptr;
  980 
  981                         /* Make sure host's link really exists */
  982                         KASSERT(priv->links[hent->host.linkNum] != NULL,
  983                             ("%s: host %6D on nonexistent link %d\n",
  984                             __func__, hent->host.addr, ":",
  985                             hent->host.linkNum));
  986 
  987                         /* Remove hosts we haven't heard from in a while */
  988                         if (++hent->host.staleness >= priv->conf.maxStaleness) {
  989                                 *hptr = SLIST_NEXT(hent, next);
  990                                 free(hent, M_NETGRAPH_BRIDGE);
  991                                 priv->numHosts--;
  992                         } else {
  993                                 if (hent->host.age < 0xffff)
  994                                         hent->host.age++;
  995                                 hptr = &SLIST_NEXT(hent, next);
  996                                 counter++;
  997                         }
  998                 }
  999         }
 1000         KASSERT(priv->numHosts == counter,
 1001             ("%s: hosts: %d != %d", __func__, priv->numHosts, counter));
 1002 
 1003         /* Decrease table size if necessary */
 1004         ng_bridge_rehash(priv);
 1005 
 1006         /* Decrease loop counter on muted looped back links */
 1007         for (counter = linkNum = 0; linkNum < NG_BRIDGE_MAX_LINKS; linkNum++) {
 1008                 struct ng_bridge_link *const link = priv->links[linkNum];
 1009 
 1010                 if (link != NULL) {
 1011                         if (link->loopCount != 0) {
 1012                                 link->loopCount--;
 1013                                 if (link->loopCount == 0
 1014                                     && priv->conf.debugLevel >= 2) {
 1015                                         log(LOG_INFO, "ng_bridge: %s:"
 1016                                             " restoring looped back link%d\n",
 1017                                             ng_bridge_nodename(node), linkNum);
 1018                                 }
 1019                         }
 1020                         counter++;
 1021                 }
 1022         }
 1023         KASSERT(priv->numLinks == counter,
 1024             ("%s: links: %d != %d", __func__, priv->numLinks, counter));
 1025 
 1026         /* Register a new timeout, keeping the existing node reference */
 1027         ng_callout(&priv->timer, node, NULL, hz, ng_bridge_timeout, NULL, 0);
 1028 }
 1029 
 1030 /*
 1031  * Return node's "name", even if it doesn't have one.
 1032  */
 1033 static const char *
 1034 ng_bridge_nodename(node_p node)
 1035 {
 1036         static char name[NG_NODESIZ];
 1037 
 1038         if (NG_NODE_NAME(node) != NULL)
 1039                 snprintf(name, sizeof(name), "%s", NG_NODE_NAME(node));
 1040         else
 1041                 snprintf(name, sizeof(name), "[%x]", ng_node2ID(node));
 1042         return name;
 1043 }
 1044 

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