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

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    1 
    2 /*
    3  * ng_sample.c
    4  *
    5  * Copyright (c) 1996-1999 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: Julian Elischer <julian@freebsd.org>
   38  *
   39  * $FreeBSD: src/sys/netgraph/ng_sample.c,v 1.7.2.3 2002/07/02 23:44:03 archie Exp $
   40  * $Whistle: ng_sample.c,v 1.13 1999/11/01 09:24:52 julian Exp $
   41  */
   42 
   43 #include <sys/param.h>
   44 #include <sys/systm.h>
   45 #include <sys/kernel.h>
   46 #include <sys/mbuf.h>
   47 #include <sys/malloc.h>
   48 #include <sys/ctype.h>
   49 #include <sys/errno.h>
   50 #include <sys/syslog.h>
   51 
   52 #include <netgraph/ng_message.h>
   53 #include <netgraph/ng_parse.h>
   54 #include <netgraph/ng_sample.h>
   55 #include <netgraph/netgraph.h>
   56 
   57 /*
   58  * This section contains the netgraph method declarations for the
   59  * sample node. These methods define the netgraph 'type'.
   60  */
   61 
   62 static ng_constructor_t ng_xxx_constructor;
   63 static ng_rcvmsg_t      ng_xxx_rcvmsg;
   64 static ng_shutdown_t    ng_xxx_rmnode;
   65 static ng_newhook_t     ng_xxx_newhook;
   66 static ng_connect_t     ng_xxx_connect;
   67 static ng_rcvdata_t     ng_xxx_rcvdata;  /* note these are both ng_rcvdata_t */
   68 static ng_rcvdata_t     ng_xxx_rcvdataq; /* note these are both ng_rcvdata_t */
   69 static ng_disconnect_t  ng_xxx_disconnect;
   70 
   71 /* Parse type for struct ngxxxstat */
   72 static const struct ng_parse_struct_field ng_xxx_stat_type_fields[]
   73         = NG_XXX_STATS_TYPE_INFO;
   74 static const struct ng_parse_type ng_xxx_stat_type = {
   75         &ng_parse_struct_type,
   76         &ng_xxx_stat_type_fields
   77 };
   78 
   79 /* List of commands and how to convert arguments to/from ASCII */
   80 static const struct ng_cmdlist ng_xxx_cmdlist[] = {
   81         {
   82           NGM_XXX_COOKIE,
   83           NGM_XXX_GET_STATUS,
   84           "getstatus",
   85           NULL,
   86           &ng_xxx_stat_type,
   87         },
   88         {
   89           NGM_XXX_COOKIE,
   90           NGM_XXX_SET_FLAG,
   91           "setflag",
   92           &ng_parse_int32_type,
   93           NULL
   94         },
   95         { 0 }
   96 };
   97 
   98 /* Netgraph node type descriptor */
   99 static struct ng_type typestruct = {
  100         NG_VERSION,
  101         NG_XXX_NODE_TYPE,
  102         NULL,
  103         ng_xxx_constructor,
  104         ng_xxx_rcvmsg,
  105         ng_xxx_rmnode,
  106         ng_xxx_newhook,
  107         NULL,
  108         ng_xxx_connect,
  109         ng_xxx_rcvdata,
  110         ng_xxx_rcvdataq,
  111         ng_xxx_disconnect,
  112         ng_xxx_cmdlist
  113 };
  114 NETGRAPH_INIT(xxx, &typestruct);
  115 
  116 /* Information we store for each hook on each node */
  117 struct XXX_hookinfo {
  118         int     dlci;           /* The DLCI it represents, -1 == downstream */
  119         int     channel;        /* The channel representing this DLCI */
  120         hook_p  hook;
  121 };
  122 
  123 /* Information we store for each node */
  124 struct XXX {
  125         struct XXX_hookinfo channel[XXX_NUM_DLCIS];
  126         struct XXX_hookinfo downstream_hook;
  127         node_p          node;           /* back pointer to node */
  128         hook_p          debughook;
  129         u_int           packets_in;     /* packets in from downstream */
  130         u_int           packets_out;    /* packets out towards downstream */
  131         u_int32_t       flags;
  132 };
  133 typedef struct XXX *xxx_p;
  134 
  135 /*
  136  * Allocate the private data structure and the generic node
  137  * and link them together.
  138  *
  139  * ng_make_node_common() returns with a generic node struct
  140  * with a single reference for us.. we transfer it to the
  141  * private structure.. when we free the private struct we must
  142  * unref the node so it gets freed too.
  143  *
  144  * If this were a device node than this work would be done in the attach()
  145  * routine and the constructor would return EINVAL as you should not be able
  146  * to creatednodes that depend on hardware (unless you can add the hardware :)
  147  */
  148 static int
  149 ng_xxx_constructor(node_p *nodep)
  150 {
  151         xxx_p privdata;
  152         int i, error;
  153 
  154         /* Initialize private descriptor */
  155         privdata = kmalloc(sizeof(*privdata), M_NETGRAPH, M_NOWAIT | M_ZERO);
  156         if (privdata == NULL)
  157                 return (ENOMEM);
  158         for (i = 0; i < XXX_NUM_DLCIS; i++) {
  159                 privdata->channel[i].dlci = -2;
  160                 privdata->channel[i].channel = i;
  161         }
  162 
  163         /* Call the 'generic' (ie, superclass) node constructor */
  164         if ((error = ng_make_node_common(&typestruct, nodep))) {
  165                 kfree(privdata, M_NETGRAPH);
  166                 return (error);
  167         }
  168 
  169         /* Link structs together; this counts as our one reference to *nodep */
  170         (*nodep)->private = privdata;
  171         privdata->node = *nodep;
  172         return (0);
  173 }
  174 
  175 /*
  176  * Give our ok for a hook to be added...
  177  * If we are not running this might kick a device into life.
  178  * Possibly decode information out of the hook name.
  179  * Add the hook's private info to the hook structure.
  180  * (if we had some). In this example, we assume that there is a
  181  * an array of structs, called 'channel' in the private info,
  182  * one for each active channel. The private
  183  * pointer of each hook points to the appropriate XXX_hookinfo struct
  184  * so that the source of an input packet is easily identified.
  185  * (a dlci is a frame relay channel)
  186  */
  187 static int
  188 ng_xxx_newhook(node_p node, hook_p hook, const char *name)
  189 {
  190         const xxx_p xxxp = node->private;
  191         const char *cp;
  192         int dlci = 0;
  193         int chan;
  194 
  195 #if 0
  196         /* Possibly start up the device if it's not already going */
  197         if ((xxxp->flags & SCF_RUNNING) == 0) {
  198                 ng_xxx_start_hardware(xxxp);
  199         }
  200 #endif
  201 
  202         /* Example of how one might use hooks with embedded numbers: All
  203          * hooks start with 'dlci' and have a decimal trailing channel
  204          * number up to 4 digits Use the leadin defined int he associated .h
  205          * file. */
  206         if (strncmp(name,
  207             NG_XXX_HOOK_DLCI_LEADIN, strlen(NG_XXX_HOOK_DLCI_LEADIN)) == 0) {
  208                 char *eptr;
  209 
  210                 cp = name + sizeof(NG_XXX_HOOK_DLCI_LEADIN);
  211                 if (!isdigit(*cp) || (cp[0] == '' && cp[1] != '\0'))
  212                         return (EINVAL);
  213                 dlci = (int)strtoul(cp, &eptr, 10);
  214                 if (*eptr != '\0' || dlci < 0 || dlci > 1023)
  215                         return (EINVAL);
  216 
  217                 /* We have a dlci, now either find it, or allocate it */
  218                 for (chan = 0; chan < XXX_NUM_DLCIS; chan++)
  219                         if (xxxp->channel[chan].dlci == dlci)
  220                                 break;
  221                 if (chan == XXX_NUM_DLCIS) {
  222                         for (chan = 0; chan < XXX_NUM_DLCIS; chan++)
  223                                 if (xxxp->channel[chan].dlci != -2)
  224                                         continue;
  225                         if (chan == XXX_NUM_DLCIS)
  226                                 return (ENOBUFS);
  227                 }
  228                 if (xxxp->channel[chan].hook != NULL)
  229                         return (EADDRINUSE);
  230                 hook->private = xxxp->channel + chan;
  231                 xxxp->channel[chan].hook = hook;
  232                 return (0);
  233         } else if (strcmp(name, NG_XXX_HOOK_DOWNSTREAM) == 0) {
  234                 /* Example of simple predefined hooks. */
  235                 /* do something specific to the downstream connection */
  236                 xxxp->downstream_hook.hook = hook;
  237                 hook->private = &xxxp->downstream_hook;
  238         } else if (strcmp(name, NG_XXX_HOOK_DEBUG) == 0) {
  239                 /* do something specific to a debug connection */
  240                 xxxp->debughook = hook;
  241                 hook->private = NULL;
  242         } else
  243                 return (EINVAL);        /* not a hook we know about */
  244         return(0);
  245 }
  246 
  247 /*
  248  * Get a netgraph control message.
  249  * Check it is one we understand. If needed, send a response.
  250  * We could save the address for an async action later, but don't here.
  251  * Always free the message.
  252  * The response should be in a malloc'd region that the caller can 'free'.
  253  * A response is not required.
  254  * Theoretically you could respond defferently to old message types if
  255  * the cookie in the header didn't match what we consider to be current
  256  * (so that old userland programs could continue to work).
  257  */
  258 static int
  259 ng_xxx_rcvmsg(node_p node,
  260            struct ng_mesg *msg, const char *retaddr, struct ng_mesg **rptr)
  261 {
  262         const xxx_p xxxp = node->private;
  263         struct ng_mesg *resp = NULL;
  264         int error = 0;
  265 
  266         /* Deal with message according to cookie and command */
  267         switch (msg->header.typecookie) {
  268         case NGM_XXX_COOKIE: 
  269                 switch (msg->header.cmd) {
  270                 case NGM_XXX_GET_STATUS:
  271                     {
  272                         struct ngxxxstat *stats;
  273 
  274                         NG_MKRESPONSE(resp, msg, sizeof(*stats), M_NOWAIT);
  275                         if (!resp) {
  276                                 error = ENOMEM;
  277                                 break;
  278                         }
  279                         stats = (struct ngxxxstat *) resp->data;
  280                         stats->packets_in = xxxp->packets_in;
  281                         stats->packets_out = xxxp->packets_out;
  282                         break;
  283                     }
  284                 case NGM_XXX_SET_FLAG:
  285                         if (msg->header.arglen != sizeof(u_int32_t)) {
  286                                 error = EINVAL;
  287                                 break;
  288                         }
  289                         xxxp->flags = *((u_int32_t *) msg->data);
  290                         break;
  291                 default:
  292                         error = EINVAL;         /* unknown command */
  293                         break;
  294                 }
  295                 break;
  296         default:
  297                 error = EINVAL;                 /* unknown cookie type */
  298                 break;
  299         }
  300 
  301         /* Take care of synchronous response, if any */
  302         if (rptr)
  303                 *rptr = resp;
  304         else if (resp)
  305                 kfree(resp, M_NETGRAPH);
  306 
  307         /* Free the message and return */
  308         kfree(msg, M_NETGRAPH);
  309         return(error);
  310 }
  311 
  312 /*
  313  * Receive data, and do something with it.
  314  * Possibly send it out on another link after processing.
  315  * Possibly do something different if it comes from different
  316  * hooks. the caller will never free m or meta, so
  317  * if we use up this data or abort we must free BOTH of these.
  318  *
  319  * If we want, we may decide to force this data to be queued and reprocessed
  320  * at the netgraph NETISR time. (at which time it will be entered using ng_xxx_rcvdataq().
  321  */
  322 static int
  323 ng_xxx_rcvdata(hook_p hook, struct mbuf *m, meta_p meta)
  324 {
  325         int dlci = -2;
  326 
  327         if (hook->private) {
  328                 /* 
  329                  * If it's dlci 1023, requeue it so that it's handled
  330                  * at a lower priority. This is how a node decides to
  331                  * defer a data message.
  332                  */
  333                 dlci = ((struct XXX_hookinfo *) hook->private)->dlci;
  334                 if (dlci == 1023) {
  335                         return(ng_queue_data(hook->peer, m, meta));
  336                 }
  337         }
  338         return(ng_xxx_rcvdataq(hook, m, meta));
  339 }
  340 
  341 /*
  342  * Always accept the data. This version of rcvdata is called from the dequeueing routine.
  343  */
  344 static int
  345 ng_xxx_rcvdataq(hook_p hook, struct mbuf *m, meta_p meta)
  346 {
  347         const xxx_p xxxp = hook->node->private;
  348         int chan = -2;
  349         int dlci = -2;
  350         int error;
  351 
  352         if (hook->private) {
  353                 dlci = ((struct XXX_hookinfo *) hook->private)->dlci;
  354                 chan = ((struct XXX_hookinfo *) hook->private)->channel;
  355                 if (dlci != -1) {
  356                         /* If received on a DLCI hook process for this
  357                          * channel and pass it to the downstream module.
  358                          * Normally one would add a multiplexing header at
  359                          * the front here */
  360                         /* M_PREPEND(....)      ; */
  361                         /* mtod(m, xxxxxx)->dlci = dlci; */
  362                         error = ng_send_data(xxxp->downstream_hook.hook,
  363                             m, meta);
  364                         xxxp->packets_out++;
  365                 } else {
  366                         /* data came from the multiplexed link */
  367                         dlci = 1;       /* get dlci from header */
  368                         /* madjust(....) *//* chop off header */
  369                         for (chan = 0; chan < XXX_NUM_DLCIS; chan++)
  370                                 if (xxxp->channel[chan].dlci == dlci)
  371                                         break;
  372                         if (chan == XXX_NUM_DLCIS) {
  373                                 NG_FREE_DATA(m, meta);
  374                                 return (ENETUNREACH);
  375                         }
  376                         /* If we were called at splnet, use the following:
  377                          * NG_SEND_DATA(error, otherhook, m, meta); if this
  378                          * node is running at some SPL other than SPLNET
  379                          * then you should use instead: error =
  380                          * ng_queueit(otherhook, m, meta); m = NULL: meta =
  381                          * NULL; this queues the data using the standard
  382                          * NETISR system and schedules the data to be picked
  383                          * up again once the system has moved to SPLNET and
  384                          * the processing of the data can continue. after
  385                          * these are run 'm' and 'meta' should be considered
  386                          * as invalid and NG_SEND_DATA actually zaps them. */
  387                         NG_SEND_DATA(error, xxxp->channel[chan].hook, m, meta);
  388                         xxxp->packets_in++;
  389                 }
  390         } else {
  391                 /* It's the debug hook, throw it away.. */
  392                 if (hook == xxxp->downstream_hook.hook)
  393                         NG_FREE_DATA(m, meta);
  394         }
  395         return 0;
  396 }
  397 
  398 #if 0
  399 /*
  400  * If this were a device node, the data may have been received in response
  401  * to some interrupt.
  402  * in which case it would probably look as follows:
  403  */
  404 void
  405 devintr(void)
  406 {
  407         meta_p  meta = NULL;    /* whatever metadata we might imagine goes
  408                                  * here */
  409 
  410         /* get packet from device and send on */
  411         m = MGET(blah blah)
  412             error = ng_queueit(upstream, m, meta);      /* see note above in
  413                                                          * xxx_rcvdata() */
  414 }
  415 
  416 #endif                          /* 0 */
  417 
  418 /*
  419  * Do local shutdown processing..
  420  * If we are a persistant device, we might refuse to go away, and
  421  * we'd only remove our links and reset ourself.
  422  */
  423 static int
  424 ng_xxx_rmnode(node_p node)
  425 {
  426         const xxx_p privdata = node->private;
  427 
  428         node->flags |= NG_INVALID;
  429         ng_cutlinks(node);
  430 #ifndef PERSISTANT_NODE
  431         ng_unname(node);
  432         node->private = NULL;
  433         ng_unref(privdata->node);
  434         kfree(privdata, M_NETGRAPH);
  435 #else
  436         privdata->packets_in = 0;               /* reset stats */
  437         privdata->packets_out = 0;
  438         node->flags &= ~NG_INVALID;             /* reset invalid flag */
  439 #endif /* PERSISTANT_NODE */
  440         return (0);
  441 }
  442 
  443 /*
  444  * This is called once we've already connected a new hook to the other node.
  445  * It gives us a chance to balk at the last minute.
  446  */
  447 static int
  448 ng_xxx_connect(hook_p hook)
  449 {
  450         /* be really amiable and just say "YUP that's OK by me! " */
  451         return (0);
  452 }
  453 
  454 /*
  455  * Dook disconnection
  456  *
  457  * For this type, removal of the last link destroys the node
  458  */
  459 static int
  460 ng_xxx_disconnect(hook_p hook)
  461 {
  462         if (hook->private)
  463                 ((struct XXX_hookinfo *) (hook->private))->hook = NULL;
  464         if (hook->node->numhooks == 0)
  465                 ng_rmnode(hook->node);
  466         return (0);
  467 }
  468 

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