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

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    1 /*
    2  * ng_sample.c
    3  */
    4 
    5 /*-
    6  * Copyright (c) 1996-1999 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: Julian Elischer <julian@freebsd.org>
   39  *
   40  * $FreeBSD: src/sys/netgraph/ng_sample.c,v 1.24.2.2 2005/01/31 23:26:29 imp Exp $
   41  * $Whistle: ng_sample.c,v 1.13 1999/11/01 09:24:52 julian Exp $
   42  */
   43 
   44 #include <sys/param.h>
   45 #include <sys/systm.h>
   46 #include <sys/kernel.h>
   47 #include <sys/mbuf.h>
   48 #include <sys/malloc.h>
   49 #include <sys/ctype.h>
   50 #include <sys/errno.h>
   51 #include <sys/syslog.h>
   52 
   53 #include <netgraph/ng_message.h>
   54 #include <netgraph/ng_parse.h>
   55 #include <netgraph/ng_sample.h>
   56 #include <netgraph/netgraph.h>
   57 
   58 /* If you do complicated mallocs you may want to do this */
   59 /* and use it for your mallocs */
   60 #ifdef NG_SEPARATE_MALLOC
   61 MALLOC_DEFINE(M_NETGRAPH_XXX, "netgraph_xxx", "netgraph xxx node ");
   62 #else
   63 #define M_NETGRAPH_XXX M_NETGRAPH
   64 #endif
   65 
   66 /*
   67  * This section contains the netgraph method declarations for the
   68  * sample node. These methods define the netgraph 'type'.
   69  */
   70 
   71 static ng_constructor_t ng_xxx_constructor;
   72 static ng_rcvmsg_t      ng_xxx_rcvmsg;
   73 static ng_shutdown_t    ng_xxx_shutdown;
   74 static ng_newhook_t     ng_xxx_newhook;
   75 static ng_connect_t     ng_xxx_connect;
   76 static ng_rcvdata_t     ng_xxx_rcvdata;  /* note these are both ng_rcvdata_t */
   77 static ng_disconnect_t  ng_xxx_disconnect;
   78 
   79 /* Parse type for struct ngxxxstat */
   80 static const struct ng_parse_struct_field ng_xxx_stat_type_fields[]
   81         = NG_XXX_STATS_TYPE_INFO;
   82 static const struct ng_parse_type ng_xxx_stat_type = {
   83         &ng_parse_struct_type,
   84         &ng_xxx_stat_type_fields
   85 };
   86 
   87 /* List of commands and how to convert arguments to/from ASCII */
   88 static const struct ng_cmdlist ng_xxx_cmdlist[] = {
   89         {
   90           NGM_XXX_COOKIE,
   91           NGM_XXX_GET_STATUS,
   92           "getstatus",
   93           NULL,
   94           &ng_xxx_stat_type,
   95         },
   96         {
   97           NGM_XXX_COOKIE,
   98           NGM_XXX_SET_FLAG,
   99           "setflag",
  100           &ng_parse_int32_type,
  101           NULL
  102         },
  103         { 0 }
  104 };
  105 
  106 /* Netgraph node type descriptor */
  107 static struct ng_type typestruct = {
  108         .version =      NG_ABI_VERSION,
  109         .name =         NG_XXX_NODE_TYPE,
  110         .constructor =  ng_xxx_constructor,
  111         .rcvmsg =       ng_xxx_rcvmsg,
  112         .shutdown =     ng_xxx_shutdown,
  113         .newhook =      ng_xxx_newhook,
  114 /*      .findhook =     ng_xxx_findhook,        */
  115         .connect =      ng_xxx_connect,
  116         .rcvdata =      ng_xxx_rcvdata,
  117         .disconnect =   ng_xxx_disconnect,
  118         .cmdlist =      ng_xxx_cmdlist,
  119 };
  120 NETGRAPH_INIT(xxx, &typestruct);
  121 
  122 /* Information we store for each hook on each node */
  123 struct XXX_hookinfo {
  124         int     dlci;           /* The DLCI it represents, -1 == downstream */
  125         int     channel;        /* The channel representing this DLCI */
  126         hook_p  hook;
  127 };
  128 
  129 /* Information we store for each node */
  130 struct XXX {
  131         struct XXX_hookinfo channel[XXX_NUM_DLCIS];
  132         struct XXX_hookinfo downstream_hook;
  133         node_p          node;           /* back pointer to node */
  134         hook_p          debughook;
  135         u_int           packets_in;     /* packets in from downstream */
  136         u_int           packets_out;    /* packets out towards downstream */
  137         u_int32_t       flags;
  138 };
  139 typedef struct XXX *xxx_p;
  140 
  141 /*
  142  * Allocate the private data structure. The generic node has already
  143  * been created. Link them together. We arrive with a reference to the node
  144  * i.e. the reference count is incremented for us already.
  145  *
  146  * If this were a device node than this work would be done in the attach()
  147  * routine and the constructor would return EINVAL as you should not be able
  148  * to creatednodes that depend on hardware (unless you can add the hardware :)
  149  */
  150 static int
  151 ng_xxx_constructor(node_p node)
  152 {
  153         xxx_p privdata;
  154         int i;
  155 
  156         /* Initialize private descriptor */
  157         MALLOC(privdata, xxx_p, sizeof(*privdata), M_NETGRAPH,
  158                 M_NOWAIT | M_ZERO);
  159         if (privdata == NULL)
  160                 return (ENOMEM);
  161         for (i = 0; i < XXX_NUM_DLCIS; i++) {
  162                 privdata->channel[i].dlci = -2;
  163                 privdata->channel[i].channel = i;
  164         }
  165 
  166         /* Link structs together; this counts as our one reference to *nodep */
  167         NG_NODE_SET_PRIVATE(node, privdata);
  168         privdata->node = node;
  169         return (0);
  170 }
  171 
  172 /*
  173  * Give our ok for a hook to be added...
  174  * If we are not running this might kick a device into life.
  175  * Possibly decode information out of the hook name.
  176  * Add the hook's private info to the hook structure.
  177  * (if we had some). In this example, we assume that there is a
  178  * an array of structs, called 'channel' in the private info,
  179  * one for each active channel. The private
  180  * pointer of each hook points to the appropriate XXX_hookinfo struct
  181  * so that the source of an input packet is easily identified.
  182  * (a dlci is a frame relay channel)
  183  */
  184 static int
  185 ng_xxx_newhook(node_p node, hook_p hook, const char *name)
  186 {
  187         const xxx_p xxxp = NG_NODE_PRIVATE(node);
  188         const char *cp;
  189         int dlci = 0;
  190         int chan;
  191 
  192 #if 0
  193         /* Possibly start up the device if it's not already going */
  194         if ((xxxp->flags & SCF_RUNNING) == 0) {
  195                 ng_xxx_start_hardware(xxxp);
  196         }
  197 #endif
  198 
  199         /* Example of how one might use hooks with embedded numbers: All
  200          * hooks start with 'dlci' and have a decimal trailing channel
  201          * number up to 4 digits Use the leadin defined int he associated .h
  202          * file. */
  203         if (strncmp(name,
  204             NG_XXX_HOOK_DLCI_LEADIN, strlen(NG_XXX_HOOK_DLCI_LEADIN)) == 0) {
  205                 char *eptr;
  206 
  207                 cp = name + strlen(NG_XXX_HOOK_DLCI_LEADIN);
  208                 if (!isdigit(*cp) || (cp[0] == '' && cp[1] != '\0'))
  209                         return (EINVAL);
  210                 dlci = (int)strtoul(cp, &eptr, 10);
  211                 if (*eptr != '\0' || dlci < 0 || dlci > 1023)
  212                         return (EINVAL);
  213 
  214                 /* We have a dlci, now either find it, or allocate it */
  215                 for (chan = 0; chan < XXX_NUM_DLCIS; chan++)
  216                         if (xxxp->channel[chan].dlci == dlci)
  217                                 break;
  218                 if (chan == XXX_NUM_DLCIS) {
  219                         for (chan = 0; chan < XXX_NUM_DLCIS; chan++)
  220                                 if (xxxp->channel[chan].dlci == -2)
  221                                         break;
  222                         if (chan == XXX_NUM_DLCIS)
  223                                 return (ENOBUFS);
  224                         xxxp->channel[chan].dlci = dlci;
  225                 }
  226                 if (xxxp->channel[chan].hook != NULL)
  227                         return (EADDRINUSE);
  228                 NG_HOOK_SET_PRIVATE(hook, xxxp->channel + chan);
  229                 xxxp->channel[chan].hook = hook;
  230                 return (0);
  231         } else if (strcmp(name, NG_XXX_HOOK_DOWNSTREAM) == 0) {
  232                 /* Example of simple predefined hooks. */
  233                 /* do something specific to the downstream connection */
  234                 xxxp->downstream_hook.hook = hook;
  235                 NG_HOOK_SET_PRIVATE(hook, &xxxp->downstream_hook);
  236         } else if (strcmp(name, NG_XXX_HOOK_DEBUG) == 0) {
  237                 /* do something specific to a debug connection */
  238                 xxxp->debughook = hook;
  239                 NG_HOOK_SET_PRIVATE(hook, NULL);
  240         } else
  241                 return (EINVAL);        /* not a hook we know about */
  242         return(0);
  243 }
  244 
  245 /*
  246  * Get a netgraph control message.
  247  * We actually recieve a queue item that has a pointer to the message.
  248  * If we free the item, the message will be freed too, unless we remove
  249  * it from the item using NGI_GET_MSG();
  250  * The return address is also stored in the item, as an ng_ID_t,
  251  * accessible as NGI_RETADDR(item);
  252  * Check it is one we understand. If needed, send a response.
  253  * We could save the address for an async action later, but don't here.
  254  * Always free the message.
  255  * The response should be in a malloc'd region that the caller can 'free'.
  256  * A response is not required.
  257  * Theoretically you could respond defferently to old message types if
  258  * the cookie in the header didn't match what we consider to be current
  259  * (so that old userland programs could continue to work).
  260  */
  261 static int
  262 ng_xxx_rcvmsg(node_p node, item_p item, hook_p lasthook)
  263 {
  264         const xxx_p xxxp = NG_NODE_PRIVATE(node);
  265         struct ng_mesg *resp = NULL;
  266         int error = 0;
  267         struct ng_mesg *msg;
  268 
  269         NGI_GET_MSG(item, msg);
  270         /* Deal with message according to cookie and command */
  271         switch (msg->header.typecookie) {
  272         case NGM_XXX_COOKIE: 
  273                 switch (msg->header.cmd) {
  274                 case NGM_XXX_GET_STATUS:
  275                     {
  276                         struct ngxxxstat *stats;
  277 
  278                         NG_MKRESPONSE(resp, msg, sizeof(*stats), M_NOWAIT);
  279                         if (!resp) {
  280                                 error = ENOMEM;
  281                                 break;
  282                         }
  283                         stats = (struct ngxxxstat *) resp->data;
  284                         stats->packets_in = xxxp->packets_in;
  285                         stats->packets_out = xxxp->packets_out;
  286                         break;
  287                     }
  288                 case NGM_XXX_SET_FLAG:
  289                         if (msg->header.arglen != sizeof(u_int32_t)) {
  290                                 error = EINVAL;
  291                                 break;
  292                         }
  293                         xxxp->flags = *((u_int32_t *) msg->data);
  294                         break;
  295                 default:
  296                         error = EINVAL;         /* unknown command */
  297                         break;
  298                 }
  299                 break;
  300         default:
  301                 error = EINVAL;                 /* unknown cookie type */
  302                 break;
  303         }
  304 
  305         /* Take care of synchronous response, if any */
  306         NG_RESPOND_MSG(error, node, item, resp);
  307         /* Free the message and return */
  308         NG_FREE_MSG(msg);
  309         return(error);
  310 }
  311 
  312 /*
  313  * Receive data, and do something with it.
  314  * Actually we receive a queue item which holds the data.
  315  * If we free the item it will also free the data unless we have
  316  * previously disassociated it using the NGI_GET_M() macro.
  317  * Possibly send it out on another link after processing.
  318  * Possibly do something different if it comes from different
  319  * hooks. The caller will never free m, so if we use up this data or
  320  * abort we must free it.
  321  *
  322  * If we want, we may decide to force this data to be queued and reprocessed
  323  * at the netgraph NETISR time.
  324  * We would do that by setting the HK_QUEUE flag on our hook. We would do that
  325  * in the connect() method. 
  326  */
  327 static int
  328 ng_xxx_rcvdata(hook_p hook, item_p item )
  329 {
  330         const xxx_p xxxp = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  331         int chan = -2;
  332         int dlci = -2;
  333         int error;
  334         struct mbuf *m;
  335 
  336         NGI_GET_M(item, m);
  337         if (NG_HOOK_PRIVATE(hook)) {
  338                 dlci = ((struct XXX_hookinfo *) NG_HOOK_PRIVATE(hook))->dlci;
  339                 chan = ((struct XXX_hookinfo *) NG_HOOK_PRIVATE(hook))->channel;
  340                 if (dlci != -1) {
  341                         /* If received on a DLCI hook process for this
  342                          * channel and pass it to the downstream module.
  343                          * Normally one would add a multiplexing header at
  344                          * the front here */
  345                         /* M_PREPEND(....)      ; */
  346                         /* mtod(m, xxxxxx)->dlci = dlci; */
  347                         NG_FWD_NEW_DATA(error, item, 
  348                                 xxxp->downstream_hook.hook, m);
  349                         xxxp->packets_out++;
  350                 } else {
  351                         /* data came from the multiplexed link */
  352                         dlci = 1;       /* get dlci from header */
  353                         /* madjust(....) *//* chop off header */
  354                         for (chan = 0; chan < XXX_NUM_DLCIS; chan++)
  355                                 if (xxxp->channel[chan].dlci == dlci)
  356                                         break;
  357                         if (chan == XXX_NUM_DLCIS) {
  358                                 NG_FREE_ITEM(item);
  359                                 NG_FREE_M(m);
  360                                 return (ENETUNREACH);
  361                         }
  362                         /* If we were called at splnet, use the following:
  363                          * NG_SEND_DATA_ONLY(error, otherhook, m); if this
  364                          * node is running at some SPL other than SPLNET
  365                          * then you should use instead: error =
  366                          * ng_queueit(otherhook, m, NULL); m = NULL;
  367                          * This queues the data using the standard NETISR
  368                          * system and schedules the data to be picked
  369                          * up again once the system has moved to SPLNET and
  370                          * the processing of the data can continue. After
  371                          * these are run 'm' should be considered
  372                          * as invalid and NG_SEND_DATA actually zaps them. */
  373                         NG_FWD_NEW_DATA(error, item,
  374                                 xxxp->channel[chan].hook, m);
  375                         xxxp->packets_in++;
  376                 }
  377         } else {
  378                 /* It's the debug hook, throw it away.. */
  379                 if (hook == xxxp->downstream_hook.hook) {
  380                         NG_FREE_ITEM(item);
  381                         NG_FREE_M(m);
  382                 }
  383         }
  384         return 0;
  385 }
  386 
  387 #if 0
  388 /*
  389  * If this were a device node, the data may have been received in response
  390  * to some interrupt.
  391  * in which case it would probably look as follows:
  392  */
  393 devintr()
  394 {
  395         int error;
  396 
  397         /* get packet from device and send on */
  398         m = MGET(blah blah)
  399         
  400         NG_SEND_DATA_ONLY(error, xxxp->upstream_hook.hook, m);
  401                                 /* see note above in xxx_rcvdata() */
  402                                 /* and ng_xxx_connect() */
  403 }
  404 
  405 #endif                          /* 0 */
  406 
  407 /*
  408  * Do local shutdown processing..
  409  * All our links and the name have already been removed.
  410  * If we are a persistant device, we might refuse to go away.
  411  * In the case of a persistant node we signal the framework that we
  412  * are still in business by clearing the NGF_INVALID bit. However
  413  * If we find the NGF_REALLY_DIE bit set, this means that
  414  * we REALLY need to die (e.g. hardware removed).
  415  * This would have been set using the NG_NODE_REALLY_DIE(node)
  416  * macro in some device dependent function (not shown here) before
  417  * calling ng_rmnode_self().
  418  */
  419 static int
  420 ng_xxx_shutdown(node_p node)
  421 {
  422         const xxx_p privdata = NG_NODE_PRIVATE(node);
  423 
  424 #ifndef PERSISTANT_NODE
  425         NG_NODE_SET_PRIVATE(node, NULL);
  426         NG_NODE_UNREF(node);
  427         FREE(privdata, M_NETGRAPH);
  428 #else
  429         if (node->nd_flags & NGF_REALLY_DIE) {
  430                 /*
  431                  * WE came here because the widget card is being unloaded,
  432                  * so stop being persistant.
  433                  * Actually undo all the things we did on creation.
  434                  */
  435                 NG_NODE_SET_PRIVATE(node, NULL);
  436                 NG_NODE_UNREF(privdata->node);
  437                 FREE(privdata, M_NETGRAPH);
  438                 return (0);   
  439         }
  440         NG_NODE_REVIVE(node);           /* tell ng_rmnode() we will persist */
  441 #endif /* PERSISTANT_NODE */
  442         return (0);
  443 }
  444 
  445 /*
  446  * This is called once we've already connected a new hook to the other node.
  447  * It gives us a chance to balk at the last minute.
  448  */
  449 static int
  450 ng_xxx_connect(hook_p hook)
  451 {
  452 #if 0
  453         /*
  454          * If we were a driver running at other than splnet then
  455          * we should set the QUEUE bit on the edge so that we
  456          * will deliver by queing.
  457          */
  458         if /*it is the upstream hook */
  459         NG_HOOK_FORCE_QUEUE(NG_HOOK_PEER(hook));
  460 #endif
  461 #if 0
  462         /*
  463          * If for some reason we want incoming date to be queued
  464          * by the NETISR system and delivered later we can set the same bit on
  465          * OUR hook. (maybe to allow unwinding of the stack)
  466          */
  467 
  468         if (NG_HOOK_PRIVATE(hook)) {
  469                 int dlci;
  470                 /* 
  471                  * If it's dlci 1023, requeue it so that it's handled
  472                  * at a lower priority. This is how a node decides to
  473                  * defer a data message.
  474                  */
  475                 dlci = ((struct XXX_hookinfo *) NG_HOOK_PRIVATE(hook))->dlci;
  476                 if (dlci == 1023) {
  477                         NG_HOOK_FORCE_QUEUE(hook);
  478                 }
  479 #endif
  480         /* otherwise be really amiable and just say "YUP that's OK by me! " */
  481         return (0);
  482 }
  483 
  484 /*
  485  * Hook disconnection
  486  *
  487  * For this type, removal of the last link destroys the node
  488  */
  489 static int
  490 ng_xxx_disconnect(hook_p hook)
  491 {
  492         if (NG_HOOK_PRIVATE(hook))
  493                 ((struct XXX_hookinfo *) (NG_HOOK_PRIVATE(hook)))->hook = NULL;
  494         if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
  495         && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) /* already shutting down? */
  496                 ng_rmnode_self(NG_HOOK_NODE(hook));
  497         return (0);
  498 }
  499 

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