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

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    1 
    2 /*
    3  * ng_bridge.c
    4  *
    5  * Copyright (c) 2000 Whistle Communications, Inc.
    6  * All rights reserved.
    7  * 
    8  * Subject to the following obligations and disclaimer of warranty, use and
    9  * redistribution of this software, in source or object code forms, with or
   10  * without modifications are expressly permitted by Whistle Communications;
   11  * provided, however, that:
   12  * 1. Any and all reproductions of the source or object code must include the
   13  *    copyright notice above and the following disclaimer of warranties; and
   14  * 2. No rights are granted, in any manner or form, to use Whistle
   15  *    Communications, Inc. trademarks, including the mark "WHISTLE
   16  *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
   17  *    such appears in the above copyright notice or in the software.
   18  * 
   19  * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
   20  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
   21  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
   22  * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
   23  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
   24  * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
   25  * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
   26  * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
   27  * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
   28  * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
   29  * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
   30  * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
   31  * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
   32  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   33  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   34  * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
   35  * OF SUCH DAMAGE.
   36  *
   37  * Author: Archie Cobbs <archie@freebsd.org>
   38  *
   39  * $FreeBSD: releng/5.2/sys/netgraph/ng_bridge.c 121816 2003-10-31 18:32:15Z brooks $
   40  */
   41 
   42 /*
   43  * ng_bridge(4) netgraph node type
   44  *
   45  * The node performs standard intelligent Ethernet bridging over
   46  * each of its connected hooks, or links.  A simple loop detection
   47  * algorithm is included which disables a link for priv->conf.loopTimeout
   48  * seconds when a host is seen to have jumped from one link to
   49  * another within priv->conf.minStableAge seconds.
   50  *
   51  * We keep a hashtable that maps Ethernet addresses to host info,
   52  * which is contained in struct ng_bridge_host's. These structures
   53  * tell us on which link the host may be found. A host's entry will
   54  * expire after priv->conf.maxStaleness seconds.
   55  *
   56  * This node is optimzed for stable networks, where machines jump
   57  * from one port to the other only rarely.
   58  */
   59 
   60 #include <sys/param.h>
   61 #include <sys/systm.h>
   62 #include <sys/kernel.h>
   63 #include <sys/malloc.h>
   64 #include <sys/mbuf.h>
   65 #include <sys/errno.h>
   66 #include <sys/syslog.h>
   67 #include <sys/socket.h>
   68 #include <sys/ctype.h>
   69 
   70 #include <net/if.h>
   71 #include <net/ethernet.h>
   72 
   73 #include <netinet/in.h>
   74 #include <netinet/ip_fw.h>
   75 
   76 #include <netgraph/ng_message.h>
   77 #include <netgraph/netgraph.h>
   78 #include <netgraph/ng_parse.h>
   79 #include <netgraph/ng_bridge.h>
   80 #include <netgraph/ng_ether.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(void *arg);
  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_ether_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         NG_ABI_VERSION,
  276         NG_BRIDGE_NODE_TYPE,
  277         NULL,
  278         ng_bridge_constructor,
  279         ng_bridge_rcvmsg,
  280         ng_bridge_shutdown,
  281         ng_bridge_newhook,
  282         NULL,
  283         NULL,
  284         ng_bridge_rcvdata,
  285         ng_bridge_disconnect,
  286         ng_bridge_cmdlist,
  287 };
  288 NETGRAPH_INIT(bridge, &ng_bridge_typestruct);
  289 
  290 /* Depend on ng_ether so we can use the Ethernet parse type */
  291 MODULE_DEPEND(ng_bridge, ng_ether, 1, 1, 1);
  292 
  293 /******************************************************************
  294                     NETGRAPH NODE METHODS
  295 ******************************************************************/
  296 
  297 /*
  298  * Node constructor
  299  */
  300 static int
  301 ng_bridge_constructor(node_p node)
  302 {
  303         priv_p priv;
  304 
  305         /* Allocate and initialize private info */
  306         MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH_BRIDGE, M_NOWAIT | M_ZERO);
  307         if (priv == NULL)
  308                 return (ENOMEM);
  309         callout_init(&priv->timer, 0);
  310 
  311         /* Allocate and initialize hash table, etc. */
  312         MALLOC(priv->tab, struct ng_bridge_bucket *,
  313             MIN_BUCKETS * sizeof(*priv->tab), M_NETGRAPH_BRIDGE, M_NOWAIT | M_ZERO);
  314         if (priv->tab == NULL) {
  315                 FREE(priv, M_NETGRAPH_BRIDGE);
  316                 return (ENOMEM);
  317         }
  318         priv->numBuckets = MIN_BUCKETS;
  319         priv->hashMask = MIN_BUCKETS - 1;
  320         priv->conf.debugLevel = 1;
  321         priv->conf.loopTimeout = DEFAULT_LOOP_TIMEOUT;
  322         priv->conf.maxStaleness = DEFAULT_MAX_STALENESS;
  323         priv->conf.minStableAge = DEFAULT_MIN_STABLE_AGE;
  324 
  325         /*
  326          * This node has all kinds of stuff that could be screwed by SMP.
  327          * Until it gets it's own internal protection, we go through in 
  328          * single file. This could hurt a machine bridging beteen two 
  329          * GB ethernets so it should be fixed. 
  330          * When it's fixed the process SHOULD NOT SLEEP, spinlocks please!
  331          * (and atomic ops )
  332          */
  333         NG_NODE_FORCE_WRITER(node);
  334         NG_NODE_SET_PRIVATE(node, priv);
  335         priv->node = node;
  336 
  337         /* Start timer; timer is always running while node is alive */
  338         callout_reset(&priv->timer, hz, ng_bridge_timeout, priv->node);
  339 
  340         /* Done */
  341         return (0);
  342 }
  343 
  344 /*
  345  * Method for attaching a new hook
  346  */
  347 static  int
  348 ng_bridge_newhook(node_p node, hook_p hook, const char *name)
  349 {
  350         const priv_p priv = NG_NODE_PRIVATE(node);
  351 
  352         /* Check for a link hook */
  353         if (strncmp(name, NG_BRIDGE_HOOK_LINK_PREFIX,
  354             strlen(NG_BRIDGE_HOOK_LINK_PREFIX)) == 0) {
  355                 const char *cp;
  356                 char *eptr;
  357                 u_long linkNum;
  358 
  359                 cp = name + strlen(NG_BRIDGE_HOOK_LINK_PREFIX);
  360                 if (!isdigit(*cp) || (cp[0] == '' && cp[1] != '\0'))
  361                         return (EINVAL);
  362                 linkNum = strtoul(cp, &eptr, 10);
  363                 if (*eptr != '\0' || linkNum >= NG_BRIDGE_MAX_LINKS)
  364                         return (EINVAL);
  365                 if (priv->links[linkNum] != NULL)
  366                         return (EISCONN);
  367                 MALLOC(priv->links[linkNum], struct ng_bridge_link *,
  368                     sizeof(*priv->links[linkNum]), M_NETGRAPH_BRIDGE, M_NOWAIT|M_ZERO);
  369                 if (priv->links[linkNum] == NULL)
  370                         return (ENOMEM);
  371                 priv->links[linkNum]->hook = hook;
  372                 NG_HOOK_SET_PRIVATE(hook, (void *)linkNum);
  373                 priv->numLinks++;
  374                 return (0);
  375         }
  376 
  377         /* Unknown hook name */
  378         return (EINVAL);
  379 }
  380 
  381 /*
  382  * Receive a control message
  383  */
  384 static int
  385 ng_bridge_rcvmsg(node_p node, item_p item, hook_p lasthook)
  386 {
  387         const priv_p priv = NG_NODE_PRIVATE(node);
  388         struct ng_mesg *resp = NULL;
  389         int error = 0;
  390         struct ng_mesg *msg;
  391 
  392         NGI_GET_MSG(item, msg);
  393         switch (msg->header.typecookie) {
  394         case NGM_BRIDGE_COOKIE:
  395                 switch (msg->header.cmd) {
  396                 case NGM_BRIDGE_GET_CONFIG:
  397                     {
  398                         struct ng_bridge_config *conf;
  399 
  400                         NG_MKRESPONSE(resp, msg,
  401                             sizeof(struct ng_bridge_config), M_NOWAIT);
  402                         if (resp == NULL) {
  403                                 error = ENOMEM;
  404                                 break;
  405                         }
  406                         conf = (struct ng_bridge_config *)resp->data;
  407                         *conf = priv->conf;     /* no sanity checking needed */
  408                         break;
  409                     }
  410                 case NGM_BRIDGE_SET_CONFIG:
  411                     {
  412                         struct ng_bridge_config *conf;
  413                         int i;
  414 
  415                         if (msg->header.arglen
  416                             != sizeof(struct ng_bridge_config)) {
  417                                 error = EINVAL;
  418                                 break;
  419                         }
  420                         conf = (struct ng_bridge_config *)msg->data;
  421                         priv->conf = *conf;
  422                         for (i = 0; i < NG_BRIDGE_MAX_LINKS; i++)
  423                                 priv->conf.ipfw[i] = !!priv->conf.ipfw[i];
  424                         break;
  425                     }
  426                 case NGM_BRIDGE_RESET:
  427                     {
  428                         int i;
  429 
  430                         /* Flush all entries in the hash table */
  431                         ng_bridge_remove_hosts(priv, -1);
  432 
  433                         /* Reset all loop detection counters and stats */
  434                         for (i = 0; i < NG_BRIDGE_MAX_LINKS; i++) {
  435                                 if (priv->links[i] == NULL)
  436                                         continue;
  437                                 priv->links[i]->loopCount = 0;
  438                                 bzero(&priv->links[i]->stats,
  439                                     sizeof(priv->links[i]->stats));
  440                         }
  441                         break;
  442                     }
  443                 case NGM_BRIDGE_GET_STATS:
  444                 case NGM_BRIDGE_CLR_STATS:
  445                 case NGM_BRIDGE_GETCLR_STATS:
  446                     {
  447                         struct ng_bridge_link *link;
  448                         int linkNum;
  449 
  450                         /* Get link number */
  451                         if (msg->header.arglen != sizeof(u_int32_t)) {
  452                                 error = EINVAL;
  453                                 break;
  454                         }
  455                         linkNum = *((u_int32_t *)msg->data);
  456                         if (linkNum < 0 || linkNum >= NG_BRIDGE_MAX_LINKS) {
  457                                 error = EINVAL;
  458                                 break;
  459                         }
  460                         if ((link = priv->links[linkNum]) == NULL) {
  461                                 error = ENOTCONN;
  462                                 break;
  463                         }
  464 
  465                         /* Get/clear stats */
  466                         if (msg->header.cmd != NGM_BRIDGE_CLR_STATS) {
  467                                 NG_MKRESPONSE(resp, msg,
  468                                     sizeof(link->stats), M_NOWAIT);
  469                                 if (resp == NULL) {
  470                                         error = ENOMEM;
  471                                         break;
  472                                 }
  473                                 bcopy(&link->stats,
  474                                     resp->data, sizeof(link->stats));
  475                         }
  476                         if (msg->header.cmd != NGM_BRIDGE_GET_STATS)
  477                                 bzero(&link->stats, sizeof(link->stats));
  478                         break;
  479                     }
  480                 case NGM_BRIDGE_GET_TABLE:
  481                     {
  482                         struct ng_bridge_host_ary *ary;
  483                         struct ng_bridge_hent *hent;
  484                         int i = 0, bucket;
  485 
  486                         NG_MKRESPONSE(resp, msg, sizeof(*ary)
  487                             + (priv->numHosts * sizeof(*ary->hosts)), M_NOWAIT);
  488                         if (resp == NULL) {
  489                                 error = ENOMEM;
  490                                 break;
  491                         }
  492                         ary = (struct ng_bridge_host_ary *)resp->data;
  493                         ary->numHosts = priv->numHosts;
  494                         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  495                                 SLIST_FOREACH(hent, &priv->tab[bucket], next)
  496                                         ary->hosts[i++] = hent->host;
  497                         }
  498                         break;
  499                     }
  500                 default:
  501                         error = EINVAL;
  502                         break;
  503                 }
  504                 break;
  505         default:
  506                 error = EINVAL;
  507                 break;
  508         }
  509 
  510         /* Done */
  511         NG_RESPOND_MSG(error, node, item, resp);
  512         NG_FREE_MSG(msg);
  513         return (error);
  514 }
  515 
  516 /*
  517  * Receive data on a hook
  518  */
  519 static int
  520 ng_bridge_rcvdata(hook_p hook, item_p item)
  521 {
  522         const node_p node = NG_HOOK_NODE(hook);
  523         const priv_p priv = NG_NODE_PRIVATE(node);
  524         struct ng_bridge_host *host;
  525         struct ng_bridge_link *link;
  526         struct ether_header *eh;
  527         int error = 0, linkNum;
  528         int manycast;
  529         struct mbuf *m;
  530         meta_p meta;
  531         struct ng_bridge_link *firstLink;
  532 
  533         NGI_GET_M(item, m);
  534         /* Get link number */
  535         linkNum = (intptr_t)NG_HOOK_PRIVATE(hook);
  536         KASSERT(linkNum >= 0 && linkNum < NG_BRIDGE_MAX_LINKS,
  537             ("%s: linkNum=%u", __func__, linkNum));
  538         link = priv->links[linkNum];
  539         KASSERT(link != NULL, ("%s: link%d null", __func__, linkNum));
  540 
  541         /* Sanity check packet and pull up header */
  542         if (m->m_pkthdr.len < ETHER_HDR_LEN) {
  543                 link->stats.recvRunts++;
  544                 NG_FREE_ITEM(item);
  545                 NG_FREE_M(m);
  546                 return (EINVAL);
  547         }
  548         if (m->m_len < ETHER_HDR_LEN && !(m = m_pullup(m, ETHER_HDR_LEN))) {
  549                 link->stats.memoryFailures++;
  550                 NG_FREE_ITEM(item);
  551                 return (ENOBUFS);
  552         }
  553         eh = mtod(m, struct ether_header *);
  554         if ((eh->ether_shost[0] & 1) != 0) {
  555                 link->stats.recvInvalid++;
  556                 NG_FREE_ITEM(item);
  557                 NG_FREE_M(m);
  558                 return (EINVAL);
  559         }
  560 
  561         /* Is link disabled due to a loopback condition? */
  562         if (link->loopCount != 0) {
  563                 link->stats.loopDrops++;
  564                 NG_FREE_ITEM(item);
  565                 NG_FREE_M(m);
  566                 return (ELOOP);         /* XXX is this an appropriate error? */
  567         }
  568 
  569         /* Update stats */
  570         link->stats.recvPackets++;
  571         link->stats.recvOctets += m->m_pkthdr.len;
  572         if ((manycast = (eh->ether_dhost[0] & 1)) != 0) {
  573                 if (ETHER_EQUAL(eh->ether_dhost, ng_bridge_bcast_addr)) {
  574                         link->stats.recvBroadcasts++;
  575                         manycast = 2;
  576                 } else
  577                         link->stats.recvMulticasts++;
  578         }
  579 
  580         /* Look up packet's source Ethernet address in hashtable */
  581         if ((host = ng_bridge_get(priv, eh->ether_shost)) != NULL) {
  582 
  583                 /* Update time since last heard from this host */
  584                 host->staleness = 0;
  585 
  586                 /* Did host jump to a different link? */
  587                 if (host->linkNum != linkNum) {
  588 
  589                         /*
  590                          * If the host's old link was recently established
  591                          * on the old link and it's already jumped to a new
  592                          * link, declare a loopback condition.
  593                          */
  594                         if (host->age < priv->conf.minStableAge) {
  595 
  596                                 /* Log the problem */
  597                                 if (priv->conf.debugLevel >= 2) {
  598                                         struct ifnet *ifp = m->m_pkthdr.rcvif;
  599                                         char suffix[32];
  600 
  601                                         if (ifp != NULL)
  602                                                 snprintf(suffix, sizeof(suffix),
  603                                                     " (%s)", ifp->if_xname);
  604                                         else
  605                                                 *suffix = '\0';
  606                                         log(LOG_WARNING, "ng_bridge: %s:"
  607                                             " loopback detected on %s%s\n",
  608                                             ng_bridge_nodename(node),
  609                                             NG_HOOK_NAME(hook), suffix);
  610                                 }
  611 
  612                                 /* Mark link as linka non grata */
  613                                 link->loopCount = priv->conf.loopTimeout;
  614                                 link->stats.loopDetects++;
  615 
  616                                 /* Forget all hosts on this link */
  617                                 ng_bridge_remove_hosts(priv, linkNum);
  618 
  619                                 /* Drop packet */
  620                                 link->stats.loopDrops++;
  621                                 NG_FREE_ITEM(item);
  622                                 NG_FREE_M(m);
  623                                 return (ELOOP);         /* XXX appropriate? */
  624                         }
  625 
  626                         /* Move host over to new link */
  627                         host->linkNum = linkNum;
  628                         host->age = 0;
  629                 }
  630         } else {
  631                 if (!ng_bridge_put(priv, eh->ether_shost, linkNum)) {
  632                         link->stats.memoryFailures++;
  633                         NG_FREE_ITEM(item);
  634                         NG_FREE_M(m);
  635                         return (ENOMEM);
  636                 }
  637         }
  638 
  639         /* Run packet through ipfw processing, if enabled */
  640         if (priv->conf.ipfw[linkNum] && fw_enable && ip_fw_chk_ptr != NULL) {
  641                 /* XXX not implemented yet */
  642         }
  643 
  644         /*
  645          * If unicast and destination host known, deliver to host's link,
  646          * unless it is the same link as the packet came in on.
  647          */
  648         if (!manycast) {
  649 
  650                 /* Determine packet destination link */
  651                 if ((host = ng_bridge_get(priv, eh->ether_dhost)) != NULL) {
  652                         struct ng_bridge_link *const destLink
  653                             = priv->links[host->linkNum];
  654 
  655                         /* If destination same as incoming link, do nothing */
  656                         KASSERT(destLink != NULL,
  657                             ("%s: link%d null", __func__, host->linkNum));
  658                         if (destLink == link) {
  659                                 NG_FREE_ITEM(item);
  660                                 NG_FREE_M(m);
  661                                 return (0);
  662                         }
  663 
  664                         /* Deliver packet out the destination link */
  665                         destLink->stats.xmitPackets++;
  666                         destLink->stats.xmitOctets += m->m_pkthdr.len;
  667                         NG_FWD_NEW_DATA(error, item, destLink->hook, m);
  668                         return (error);
  669                 }
  670 
  671                 /* Destination host is not known */
  672                 link->stats.recvUnknown++;
  673         }
  674 
  675         /* Distribute unknown, multicast, broadcast pkts to all other links */
  676         meta = NGI_META(item); /* peek.. */
  677         firstLink = NULL;
  678         for (linkNum = 0; linkNum <= priv->numLinks; linkNum++) {
  679                 struct ng_bridge_link *destLink;
  680                 meta_p meta2 = NULL;
  681                 struct mbuf *m2 = NULL;
  682 
  683                 /*
  684                  * If we have checked all the links then now
  685                  * send the original on its reserved link
  686                  */
  687                 if (linkNum == priv->numLinks) {
  688                         /* If we never saw a good link, leave. */
  689                         if (firstLink == NULL) {
  690                                 NG_FREE_ITEM(item);
  691                                 NG_FREE_M(m);
  692                                 return (0);
  693                         }       
  694                         destLink = firstLink;
  695                 } else {
  696                         destLink = priv->links[linkNum];
  697                         /* Skip incoming link and disconnected links */
  698                         if (destLink == NULL || destLink == link) {
  699                                 continue;
  700                         }
  701                         if (firstLink == NULL) {
  702                                 /*
  703                                  * This is the first usable link we have found.
  704                                  * Reserve it for the originals.
  705                                  * If we never find another we save a copy.
  706                                  */
  707                                 firstLink = destLink;
  708                                 continue;
  709                         }
  710 
  711                         /*
  712                          * It's usable link but not the reserved (first) one.
  713                          * Copy mbuf and meta info for sending.
  714                          */
  715                         m2 = m_dup(m, M_DONTWAIT);      /* XXX m_copypacket() */
  716                         if (m2 == NULL) {
  717                                 link->stats.memoryFailures++;
  718                                 NG_FREE_ITEM(item);
  719                                 NG_FREE_M(m);
  720                                 return (ENOBUFS);
  721                         }
  722                         if (meta != NULL
  723                             && (meta2 = ng_copy_meta(meta)) == NULL) {
  724                                 link->stats.memoryFailures++;
  725                                 m_freem(m2);
  726                                 NG_FREE_ITEM(item);
  727                                 NG_FREE_M(m);
  728                                 return (ENOMEM);
  729                         }
  730                 }
  731 
  732                 /* Update stats */
  733                 destLink->stats.xmitPackets++;
  734                 destLink->stats.xmitOctets += m->m_pkthdr.len;
  735                 switch (manycast) {
  736                 case 0:                                 /* unicast */
  737                         break;
  738                 case 1:                                 /* multicast */
  739                         destLink->stats.xmitMulticasts++;
  740                         break;
  741                 case 2:                                 /* broadcast */
  742                         destLink->stats.xmitBroadcasts++;
  743                         break;
  744                 }
  745 
  746                 /* Send packet */
  747                 if (destLink == firstLink) { 
  748                         /*
  749                          * If we've sent all the others, send the original
  750                          * on the first link we found.
  751                          */
  752                         NG_FWD_NEW_DATA(error, item, destLink->hook, m);
  753                         break; /* always done last - not really needed. */
  754                 } else {
  755                         NG_SEND_DATA(error, destLink->hook, m2, meta2);
  756                 }
  757         }
  758         return (error);
  759 }
  760 
  761 /*
  762  * Shutdown node
  763  */
  764 static int
  765 ng_bridge_shutdown(node_p node)
  766 {
  767         const priv_p priv = NG_NODE_PRIVATE(node);
  768 
  769         /*
  770          * Shut down everything except the timer. There's no way to
  771          * avoid another possible timeout event (it may have already
  772          * been dequeued), so we can't free the node yet.
  773          */
  774         KASSERT(priv->numLinks == 0 && priv->numHosts == 0,
  775             ("%s: numLinks=%d numHosts=%d",
  776             __func__, priv->numLinks, priv->numHosts));
  777         FREE(priv->tab, M_NETGRAPH_BRIDGE);
  778 
  779         /* NG_INVALID flag is now set so node will be freed at next timeout */
  780         return (0);
  781 }
  782 
  783 /*
  784  * Hook disconnection.
  785  */
  786 static int
  787 ng_bridge_disconnect(hook_p hook)
  788 {
  789         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  790         int linkNum;
  791 
  792         /* Get link number */
  793         linkNum = (intptr_t)NG_HOOK_PRIVATE(hook);
  794         KASSERT(linkNum >= 0 && linkNum < NG_BRIDGE_MAX_LINKS,
  795             ("%s: linkNum=%u", __func__, linkNum));
  796 
  797         /* Remove all hosts associated with this link */
  798         ng_bridge_remove_hosts(priv, linkNum);
  799 
  800         /* Free associated link information */
  801         KASSERT(priv->links[linkNum] != NULL, ("%s: no link", __func__));
  802         FREE(priv->links[linkNum], M_NETGRAPH_BRIDGE);
  803         priv->links[linkNum] = NULL;
  804         priv->numLinks--;
  805 
  806         /* If no more hooks, go away */
  807         if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
  808         && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) {
  809                 ng_rmnode_self(NG_HOOK_NODE(hook));
  810         }
  811         return (0);
  812 }
  813 
  814 /******************************************************************
  815                     HASH TABLE FUNCTIONS
  816 ******************************************************************/
  817 
  818 /*
  819  * Hash algorithm
  820  *
  821  * Only hashing bytes 3-6 of the Ethernet address is sufficient and fast.
  822  */
  823 #define HASH(addr,mask)         ( (((const u_int16_t *)(addr))[0]       \
  824                                  ^ ((const u_int16_t *)(addr))[1]       \
  825                                  ^ ((const u_int16_t *)(addr))[2]) & (mask) )
  826 
  827 /*
  828  * Find a host entry in the table.
  829  */
  830 static struct ng_bridge_host *
  831 ng_bridge_get(priv_p priv, const u_char *addr)
  832 {
  833         const int bucket = HASH(addr, priv->hashMask);
  834         struct ng_bridge_hent *hent;
  835 
  836         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  837                 if (ETHER_EQUAL(hent->host.addr, addr))
  838                         return (&hent->host);
  839         }
  840         return (NULL);
  841 }
  842 
  843 /*
  844  * Add a new host entry to the table. This assumes the host doesn't
  845  * already exist in the table. Returns 1 on success, 0 if there
  846  * was a memory allocation failure.
  847  */
  848 static int
  849 ng_bridge_put(priv_p priv, const u_char *addr, int linkNum)
  850 {
  851         const int bucket = HASH(addr, priv->hashMask);
  852         struct ng_bridge_hent *hent;
  853 
  854 #ifdef INVARIANTS
  855         /* Assert that entry does not already exist in hashtable */
  856         SLIST_FOREACH(hent, &priv->tab[bucket], next) {
  857                 KASSERT(!ETHER_EQUAL(hent->host.addr, addr),
  858                     ("%s: entry %6D exists in table", __func__, addr, ":"));
  859         }
  860 #endif
  861 
  862         /* Allocate and initialize new hashtable entry */
  863         MALLOC(hent, struct ng_bridge_hent *,
  864             sizeof(*hent), M_NETGRAPH_BRIDGE, M_NOWAIT);
  865         if (hent == NULL)
  866                 return (0);
  867         bcopy(addr, hent->host.addr, ETHER_ADDR_LEN);
  868         hent->host.linkNum = linkNum;
  869         hent->host.staleness = 0;
  870         hent->host.age = 0;
  871 
  872         /* Add new element to hash bucket */
  873         SLIST_INSERT_HEAD(&priv->tab[bucket], hent, next);
  874         priv->numHosts++;
  875 
  876         /* Resize table if necessary */
  877         ng_bridge_rehash(priv);
  878         return (1);
  879 }
  880 
  881 /*
  882  * Resize the hash table. We try to maintain the number of buckets
  883  * such that the load factor is in the range 0.25 to 1.0.
  884  *
  885  * If we can't get the new memory then we silently fail. This is OK
  886  * because things will still work and we'll try again soon anyway.
  887  */
  888 static void
  889 ng_bridge_rehash(priv_p priv)
  890 {
  891         struct ng_bridge_bucket *newTab;
  892         int oldBucket, newBucket;
  893         int newNumBuckets;
  894         u_int newMask;
  895 
  896         /* Is table too full or too empty? */
  897         if (priv->numHosts > priv->numBuckets
  898             && (priv->numBuckets << 1) <= MAX_BUCKETS)
  899                 newNumBuckets = priv->numBuckets << 1;
  900         else if (priv->numHosts < (priv->numBuckets >> 2)
  901             && (priv->numBuckets >> 2) >= MIN_BUCKETS)
  902                 newNumBuckets = priv->numBuckets >> 2;
  903         else
  904                 return;
  905         newMask = newNumBuckets - 1;
  906 
  907         /* Allocate and initialize new table */
  908         MALLOC(newTab, struct ng_bridge_bucket *,
  909             newNumBuckets * sizeof(*newTab), M_NETGRAPH_BRIDGE, M_NOWAIT | M_ZERO);
  910         if (newTab == NULL)
  911                 return;
  912 
  913         /* Move all entries from old table to new table */
  914         for (oldBucket = 0; oldBucket < priv->numBuckets; oldBucket++) {
  915                 struct ng_bridge_bucket *const oldList = &priv->tab[oldBucket];
  916 
  917                 while (!SLIST_EMPTY(oldList)) {
  918                         struct ng_bridge_hent *const hent
  919                             = SLIST_FIRST(oldList);
  920 
  921                         SLIST_REMOVE_HEAD(oldList, next);
  922                         newBucket = HASH(hent->host.addr, newMask);
  923                         SLIST_INSERT_HEAD(&newTab[newBucket], hent, next);
  924                 }
  925         }
  926 
  927         /* Replace old table with new one */
  928         if (priv->conf.debugLevel >= 3) {
  929                 log(LOG_INFO, "ng_bridge: %s: table size %d -> %d\n",
  930                     ng_bridge_nodename(priv->node),
  931                     priv->numBuckets, newNumBuckets);
  932         }
  933         FREE(priv->tab, M_NETGRAPH_BRIDGE);
  934         priv->numBuckets = newNumBuckets;
  935         priv->hashMask = newMask;
  936         priv->tab = newTab;
  937         return;
  938 }
  939 
  940 /******************************************************************
  941                     MISC FUNCTIONS
  942 ******************************************************************/
  943 
  944 /*
  945  * Remove all hosts associated with a specific link from the hashtable.
  946  * If linkNum == -1, then remove all hosts in the table.
  947  */
  948 static void
  949 ng_bridge_remove_hosts(priv_p priv, int linkNum)
  950 {
  951         int bucket;
  952 
  953         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
  954                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
  955 
  956                 while (*hptr != NULL) {
  957                         struct ng_bridge_hent *const hent = *hptr;
  958 
  959                         if (linkNum == -1 || hent->host.linkNum == linkNum) {
  960                                 *hptr = SLIST_NEXT(hent, next);
  961                                 FREE(hent, M_NETGRAPH_BRIDGE);
  962                                 priv->numHosts--;
  963                         } else
  964                                 hptr = &SLIST_NEXT(hent, next);
  965                 }
  966         }
  967 }
  968 
  969 /*
  970  * Handle our once-per-second timeout event. We do two things:
  971  * we decrement link->loopCount for those links being muted due to
  972  * a detected loopback condition, and we remove any hosts from
  973  * the hashtable whom we haven't heard from in a long while.
  974  *
  975  * If the node has the NG_INVALID flag set, our job is to kill it.
  976  */
  977 static void
  978 ng_bridge_timeout(void *arg)
  979 {
  980         const node_p node = arg;
  981         const priv_p priv = NG_NODE_PRIVATE(node);
  982         int s, bucket;
  983         int counter = 0;
  984         int linkNum;
  985 
  986         /* If node was shut down, this is the final lingering timeout */
  987         s = splnet();
  988         if (NG_NODE_NOT_VALID(node)) {
  989                 FREE(priv, M_NETGRAPH_BRIDGE);
  990                 NG_NODE_SET_PRIVATE(node, NULL);
  991                 NG_NODE_UNREF(node);
  992                 splx(s);
  993                 return;
  994         }
  995 
  996         /* Register a new timeout, keeping the existing node reference */
  997         callout_reset(&priv->timer, hz, ng_bridge_timeout, node);
  998 
  999         /* Update host time counters and remove stale entries */
 1000         for (bucket = 0; bucket < priv->numBuckets; bucket++) {
 1001                 struct ng_bridge_hent **hptr = &SLIST_FIRST(&priv->tab[bucket]);
 1002 
 1003                 while (*hptr != NULL) {
 1004                         struct ng_bridge_hent *const hent = *hptr;
 1005 
 1006                         /* Make sure host's link really exists */
 1007                         KASSERT(priv->links[hent->host.linkNum] != NULL,
 1008                             ("%s: host %6D on nonexistent link %d\n",
 1009                             __func__, hent->host.addr, ":",
 1010                             hent->host.linkNum));
 1011 
 1012                         /* Remove hosts we haven't heard from in a while */
 1013                         if (++hent->host.staleness >= priv->conf.maxStaleness) {
 1014                                 *hptr = SLIST_NEXT(hent, next);
 1015                                 FREE(hent, M_NETGRAPH_BRIDGE);
 1016                                 priv->numHosts--;
 1017                         } else {
 1018                                 if (hent->host.age < 0xffff)
 1019                                         hent->host.age++;
 1020                                 hptr = &SLIST_NEXT(hent, next);
 1021                                 counter++;
 1022                         }
 1023                 }
 1024         }
 1025         KASSERT(priv->numHosts == counter,
 1026             ("%s: hosts: %d != %d", __func__, priv->numHosts, counter));
 1027 
 1028         /* Decrease table size if necessary */
 1029         ng_bridge_rehash(priv);
 1030 
 1031         /* Decrease loop counter on muted looped back links */
 1032         for (counter = linkNum = 0; linkNum < NG_BRIDGE_MAX_LINKS; linkNum++) {
 1033                 struct ng_bridge_link *const link = priv->links[linkNum];
 1034 
 1035                 if (link != NULL) {
 1036                         if (link->loopCount != 0) {
 1037                                 link->loopCount--;
 1038                                 if (link->loopCount == 0
 1039                                     && priv->conf.debugLevel >= 2) {
 1040                                         log(LOG_INFO, "ng_bridge: %s:"
 1041                                             " restoring looped back link%d\n",
 1042                                             ng_bridge_nodename(node), linkNum);
 1043                                 }
 1044                         }
 1045                         counter++;
 1046                 }
 1047         }
 1048         KASSERT(priv->numLinks == counter,
 1049             ("%s: links: %d != %d", __func__, priv->numLinks, counter));
 1050 
 1051         /* Done */
 1052         splx(s);
 1053 }
 1054 
 1055 /*
 1056  * Return node's "name", even if it doesn't have one.
 1057  */
 1058 static const char *
 1059 ng_bridge_nodename(node_p node)
 1060 {
 1061         static char name[NG_NODELEN+1];
 1062 
 1063         if (NG_NODE_NAME(node) != NULL)
 1064                 snprintf(name, sizeof(name), "%s", NG_NODE_NAME(node));
 1065         else
 1066                 snprintf(name, sizeof(name), "[%x]", ng_node2ID(node));
 1067         return name;
 1068 }
 1069 

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