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: stable/3/sys/netgraph/ng_sample.c 67532 2000-10-24 22:45:12Z julian $
   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_info
   73         ng_xxx_stat_type_info = 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_info
   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         MALLOC(privdata, xxx_p, sizeof(*privdata), M_NETGRAPH, M_WAITOK);
  156         if (privdata == NULL)
  157                 return (ENOMEM);
  158         bzero(privdata, sizeof(struct XXX));
  159         for (i = 0; i < XXX_NUM_DLCIS; i++) {
  160                 privdata->channel[i].dlci = -2;
  161                 privdata->channel[i].channel = i;
  162         }
  163 
  164         /* Call the 'generic' (ie, superclass) node constructor */
  165         if ((error = ng_make_node_common(&typestruct, nodep))) {
  166                 FREE(privdata, M_NETGRAPH);
  167                 return (error);
  168         }
  169 
  170         /* Link structs together; this counts as our one reference to *nodep */
  171         (*nodep)->private = privdata;
  172         privdata->node = *nodep;
  173         return (0);
  174 }
  175 
  176 /*
  177  * Give our ok for a hook to be added...
  178  * If we are not running this might kick a device into life.
  179  * Possibly decode information out of the hook name.
  180  * Add the hook's private info to the hook structure.
  181  * (if we had some). In this example, we assume that there is a
  182  * an array of structs, called 'channel' in the private info,
  183  * one for each active channel. The private
  184  * pointer of each hook points to the appropriate XXX_hookinfo struct
  185  * so that the source of an input packet is easily identified.
  186  * (a dlci is a frame relay channel)
  187  */
  188 static int
  189 ng_xxx_newhook(node_p node, hook_p hook, const char *name)
  190 {
  191         const xxx_p xxxp = node->private;
  192         const char *cp;
  193         int dlci = 0;
  194         int chan;
  195 
  196 #if 0
  197         /* Possibly start up the device if it's not already going */
  198         if ((xxxp->flags & SCF_RUNNING) == 0) {
  199                 ng_xxx_start_hardware(xxxp);
  200         }
  201 #endif
  202 
  203         /* Example of how one might use hooks with embedded numbers: All
  204          * hooks start with 'dlci' and have a decimal trailing channel
  205          * number up to 4 digits Use the leadin defined int he associated .h
  206          * file. */
  207         if (strncmp(name,
  208             NG_XXX_HOOK_DLCI_LEADIN, strlen(NG_XXX_HOOK_DLCI_LEADIN)) == 0) {
  209                 char *eptr;
  210 
  211                 cp = name + sizeof(NG_XXX_HOOK_DLCI_LEADIN);
  212                 if (!isdigit(*cp) || (cp[0] == '' && cp[1] != '\0'))
  213                         return (EINVAL);
  214                 dlci = (int)strtoul(cp, &eptr, 10);
  215                 if (*eptr != '\0' || dlci < 0 || dlci > 1023)
  216                         return (EINVAL);
  217 
  218                 /* We have a dlci, now either find it, or allocate it */
  219                 for (chan = 0; chan < XXX_NUM_DLCIS; chan++)
  220                         if (xxxp->channel[chan].dlci == dlci)
  221                                 break;
  222                 if (chan == XXX_NUM_DLCIS) {
  223                         for (chan = 0; chan < XXX_NUM_DLCIS; chan++)
  224                                 if (xxxp->channel[chan].dlci != -2)
  225                                         continue;
  226                         if (chan == XXX_NUM_DLCIS)
  227                                 return (ENOBUFS);
  228                 }
  229                 if (xxxp->channel[chan].hook != NULL)
  230                         return (EADDRINUSE);
  231                 hook->private = xxxp->channel + chan;
  232                 xxxp->channel[chan].hook = hook;
  233                 return (0);
  234         } else if (strcmp(name, NG_XXX_HOOK_DOWNSTREAM) == 0) {
  235                 /* Example of simple predefined hooks. */
  236                 /* do something specific to the downstream connection */
  237                 xxxp->downstream_hook.hook = hook;
  238                 hook->private = &xxxp->downstream_hook;
  239         } else if (strcmp(name, NG_XXX_HOOK_DEBUG) == 0) {
  240                 /* do something specific to a debug connection */
  241                 xxxp->debughook = hook;
  242                 hook->private = NULL;
  243         } else
  244                 return (EINVAL);        /* not a hook we know about */
  245         return(0);
  246 }
  247 
  248 /*
  249  * Get a netgraph control message.
  250  * Check it is one we understand. If needed, send a response.
  251  * We could save the address for an async action later, but don't here.
  252  * Always free the message.
  253  * The response should be in a malloc'd region that the caller can 'free'.
  254  * A response is not required.
  255  * Theoretically you could respond defferently to old message types if
  256  * the cookie in the header didn't match what we consider to be current
  257  * (so that old userland programs could continue to work).
  258  */
  259 static int
  260 ng_xxx_rcvmsg(node_p node,
  261            struct ng_mesg *msg, const char *retaddr, struct ng_mesg **rptr)
  262 {
  263         const xxx_p xxxp = node->private;
  264         struct ng_mesg *resp = NULL;
  265         int error = 0;
  266 
  267         /* Deal with message according to cookie and command */
  268         switch (msg->header.typecookie) {
  269         case NGM_XXX_COOKIE: 
  270                 switch (msg->header.cmd) {
  271                 case NGM_XXX_GET_STATUS:
  272                     {
  273                         struct ngxxxstat *stats;
  274 
  275                         NG_MKRESPONSE(resp, msg, sizeof(*stats), M_NOWAIT);
  276                         if (!resp) {
  277                                 error = ENOMEM;
  278                                 break;
  279                         }
  280                         stats = (struct ngxxxstat *) resp->data;
  281                         stats->packets_in = xxxp->packets_in;
  282                         stats->packets_out = xxxp->packets_out;
  283                         break;
  284                     }
  285                 case NGM_XXX_SET_FLAG:
  286                         if (msg->header.arglen != sizeof(u_int32_t)) {
  287                                 error = EINVAL;
  288                                 break;
  289                         }
  290                         xxxp->flags = *((u_int32_t *) msg->data);
  291                         break;
  292                 default:
  293                         error = EINVAL;         /* unknown command */
  294                         break;
  295                 }
  296                 break;
  297         default:
  298                 error = EINVAL;                 /* unknown cookie type */
  299                 break;
  300         }
  301 
  302         /* Take care of synchronous response, if any */
  303         if (rptr)
  304                 *rptr = resp;
  305         else if (resp)
  306                 FREE(resp, M_NETGRAPH);
  307 
  308         /* Free the message and return */
  309         FREE(msg, M_NETGRAPH);
  310         return(error);
  311 }
  312 
  313 /*
  314  * Receive data, and do something with it.
  315  * Possibly send it out on another link after processing.
  316  * Possibly do something different if it comes from different
  317  * hooks. the caller will never free m or meta, so
  318  * if we use up this data or abort we must free BOTH of these.
  319  *
  320  * If we want, we may decide to force this data to be queued and reprocessed
  321  * at the netgraph NETISR time. (at which time it will be entered using ng_xxx_rcvdataq().
  322  */
  323 static int
  324 ng_xxx_rcvdata(hook_p hook, struct mbuf *m, meta_p meta)
  325 {
  326         int dlci = -2;
  327 
  328         if (hook->private) {
  329                 /* 
  330                  * If it's dlci 1023, requeue it so that it's handled
  331                  * at a lower priority. This is how a node decides to
  332                  * defer a data message.
  333                  */
  334                 dlci = ((struct XXX_hookinfo *) hook->private)->dlci;
  335                 if (dlci == 1023) {
  336                         return(ng_queue_data(hook->peer, m, meta));
  337                 }
  338         }
  339         return(ng_xxx_rcvdataq(hook, m, meta));
  340 }
  341 
  342 /*
  343  * Always accept the data. This version of rcvdata is called from the dequeueing routine.
  344  */
  345 static int
  346 ng_xxx_rcvdataq(hook_p hook, struct mbuf *m, meta_p meta)
  347 {
  348         const xxx_p xxxp = hook->node->private;
  349         int chan = -2;
  350         int dlci = -2;
  351         int error;
  352 
  353         if (hook->private) {
  354                 dlci = ((struct XXX_hookinfo *) hook->private)->dlci;
  355                 chan = ((struct XXX_hookinfo *) hook->private)->channel;
  356                 if (dlci != -1) {
  357                         /* If received on a DLCI hook process for this
  358                          * channel and pass it to the downstream module.
  359                          * Normally one would add a multiplexing header at
  360                          * the front here */
  361                         /* M_PREPEND(....)      ; */
  362                         /* mtod(m, xxxxxx)->dlci = dlci; */
  363                         error = ng_send_data(xxxp->downstream_hook.hook,
  364                             m, meta);
  365                         xxxp->packets_out++;
  366                 } else {
  367                         /* data came from the multiplexed link */
  368                         dlci = 1;       /* get dlci from header */
  369                         /* madjust(....) *//* chop off header */
  370                         for (chan = 0; chan < XXX_NUM_DLCIS; chan++)
  371                                 if (xxxp->channel[chan].dlci == dlci)
  372                                         break;
  373                         if (chan == XXX_NUM_DLCIS) {
  374                                 NG_FREE_DATA(m, meta);
  375                                 return (ENETUNREACH);
  376                         }
  377                         /* If we were called at splnet, use the following:
  378                          * NG_SEND_DATA(error, otherhook, m, meta); if this
  379                          * node is running at some SPL other than SPLNET
  380                          * then you should use instead: error =
  381                          * ng_queueit(otherhook, m, meta); m = NULL: meta =
  382                          * NULL; this queues the data using the standard
  383                          * NETISR system and schedules the data to be picked
  384                          * up again once the system has moved to SPLNET and
  385                          * the processing of the data can continue. after
  386                          * these are run 'm' and 'meta' should be considered
  387                          * as invalid and NG_SEND_DATA actually zaps them. */
  388                         NG_SEND_DATA(error, xxxp->channel[chan].hook, m, meta);
  389                         xxxp->packets_in++;
  390                 }
  391         } else {
  392                 /* It's the debug hook, throw it away.. */
  393                 if (hook == xxxp->downstream_hook.hook)
  394                         NG_FREE_DATA(m, meta);
  395         }
  396         return 0;
  397 }
  398 
  399 #if 0
  400 /*
  401  * If this were a device node, the data may have been received in response
  402  * to some interrupt.
  403  * in which case it would probably look as follows:
  404  */
  405 devintr()
  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         FREE(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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