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 /*
    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: releng/5.3/sys/netgraph/ng_sample.c 136588 2004-10-16 08:43:07Z cvs2svn $
   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 /* If you do complicated mallocs you may want to do this */
   58 /* and use it for your mallocs */
   59 #ifdef NG_SEPARATE_MALLOC
   60 MALLOC_DEFINE(M_NETGRAPH_XXX, "netgraph_xxx", "netgraph xxx node ");
   61 #else
   62 #define M_NETGRAPH_XXX M_NETGRAPH
   63 #endif
   64 
   65 /*
   66  * This section contains the netgraph method declarations for the
   67  * sample node. These methods define the netgraph 'type'.
   68  */
   69 
   70 static ng_constructor_t ng_xxx_constructor;
   71 static ng_rcvmsg_t      ng_xxx_rcvmsg;
   72 static ng_shutdown_t    ng_xxx_shutdown;
   73 static ng_newhook_t     ng_xxx_newhook;
   74 static ng_connect_t     ng_xxx_connect;
   75 static ng_rcvdata_t     ng_xxx_rcvdata;  /* note these are both ng_rcvdata_t */
   76 static ng_disconnect_t  ng_xxx_disconnect;
   77 
   78 /* Parse type for struct ngxxxstat */
   79 static const struct ng_parse_struct_field ng_xxx_stat_type_fields[]
   80         = NG_XXX_STATS_TYPE_INFO;
   81 static const struct ng_parse_type ng_xxx_stat_type = {
   82         &ng_parse_struct_type,
   83         &ng_xxx_stat_type_fields
   84 };
   85 
   86 /* List of commands and how to convert arguments to/from ASCII */
   87 static const struct ng_cmdlist ng_xxx_cmdlist[] = {
   88         {
   89           NGM_XXX_COOKIE,
   90           NGM_XXX_GET_STATUS,
   91           "getstatus",
   92           NULL,
   93           &ng_xxx_stat_type,
   94         },
   95         {
   96           NGM_XXX_COOKIE,
   97           NGM_XXX_SET_FLAG,
   98           "setflag",
   99           &ng_parse_int32_type,
  100           NULL
  101         },
  102         { 0 }
  103 };
  104 
  105 /* Netgraph node type descriptor */
  106 static struct ng_type typestruct = {
  107         .version =      NG_ABI_VERSION,
  108         .name =         NG_XXX_NODE_TYPE,
  109         .constructor =  ng_xxx_constructor,
  110         .rcvmsg =       ng_xxx_rcvmsg,
  111         .shutdown =     ng_xxx_shutdown,
  112         .newhook =      ng_xxx_newhook,
  113 /*      .findhook =     ng_xxx_findhook,        */
  114         .connect =      ng_xxx_connect,
  115         .rcvdata =      ng_xxx_rcvdata,
  116         .disconnect =   ng_xxx_disconnect,
  117         .cmdlist =      ng_xxx_cmdlist,
  118 };
  119 NETGRAPH_INIT(xxx, &typestruct);
  120 
  121 /* Information we store for each hook on each node */
  122 struct XXX_hookinfo {
  123         int     dlci;           /* The DLCI it represents, -1 == downstream */
  124         int     channel;        /* The channel representing this DLCI */
  125         hook_p  hook;
  126 };
  127 
  128 /* Information we store for each node */
  129 struct XXX {
  130         struct XXX_hookinfo channel[XXX_NUM_DLCIS];
  131         struct XXX_hookinfo downstream_hook;
  132         node_p          node;           /* back pointer to node */
  133         hook_p          debughook;
  134         u_int           packets_in;     /* packets in from downstream */
  135         u_int           packets_out;    /* packets out towards downstream */
  136         u_int32_t       flags;
  137 };
  138 typedef struct XXX *xxx_p;
  139 
  140 /*
  141  * Allocate the private data structure. The generic node has already
  142  * been created. Link them together. We arrive with a reference to the node
  143  * i.e. the reference count is incremented for us already.
  144  *
  145  * If this were a device node than this work would be done in the attach()
  146  * routine and the constructor would return EINVAL as you should not be able
  147  * to creatednodes that depend on hardware (unless you can add the hardware :)
  148  */
  149 static int
  150 ng_xxx_constructor(node_p node)
  151 {
  152         xxx_p privdata;
  153         int i;
  154 
  155         /* Initialize private descriptor */
  156         MALLOC(privdata, xxx_p, sizeof(*privdata), M_NETGRAPH,
  157                 M_NOWAIT | M_ZERO);
  158         if (privdata == NULL)
  159                 return (ENOMEM);
  160         for (i = 0; i < XXX_NUM_DLCIS; i++) {
  161                 privdata->channel[i].dlci = -2;
  162                 privdata->channel[i].channel = i;
  163         }
  164 
  165         /* Link structs together; this counts as our one reference to *nodep */
  166         NG_NODE_SET_PRIVATE(node, privdata);
  167         privdata->node = node;
  168         return (0);
  169 }
  170 
  171 /*
  172  * Give our ok for a hook to be added...
  173  * If we are not running this might kick a device into life.
  174  * Possibly decode information out of the hook name.
  175  * Add the hook's private info to the hook structure.
  176  * (if we had some). In this example, we assume that there is a
  177  * an array of structs, called 'channel' in the private info,
  178  * one for each active channel. The private
  179  * pointer of each hook points to the appropriate XXX_hookinfo struct
  180  * so that the source of an input packet is easily identified.
  181  * (a dlci is a frame relay channel)
  182  */
  183 static int
  184 ng_xxx_newhook(node_p node, hook_p hook, const char *name)
  185 {
  186         const xxx_p xxxp = NG_NODE_PRIVATE(node);
  187         const char *cp;
  188         int dlci = 0;
  189         int chan;
  190 
  191 #if 0
  192         /* Possibly start up the device if it's not already going */
  193         if ((xxxp->flags & SCF_RUNNING) == 0) {
  194                 ng_xxx_start_hardware(xxxp);
  195         }
  196 #endif
  197 
  198         /* Example of how one might use hooks with embedded numbers: All
  199          * hooks start with 'dlci' and have a decimal trailing channel
  200          * number up to 4 digits Use the leadin defined int he associated .h
  201          * file. */
  202         if (strncmp(name,
  203             NG_XXX_HOOK_DLCI_LEADIN, strlen(NG_XXX_HOOK_DLCI_LEADIN)) == 0) {
  204                 char *eptr;
  205 
  206                 cp = name + sizeof(NG_XXX_HOOK_DLCI_LEADIN);
  207                 if (!isdigit(*cp) || (cp[0] == '' && cp[1] != '\0'))
  208                         return (EINVAL);
  209                 dlci = (int)strtoul(cp, &eptr, 10);
  210                 if (*eptr != '\0' || dlci < 0 || dlci > 1023)
  211                         return (EINVAL);
  212 
  213                 /* We have a dlci, now either find it, or allocate it */
  214                 for (chan = 0; chan < XXX_NUM_DLCIS; chan++)
  215                         if (xxxp->channel[chan].dlci == dlci)
  216                                 break;
  217                 if (chan == XXX_NUM_DLCIS) {
  218                         for (chan = 0; chan < XXX_NUM_DLCIS; chan++)
  219                                 if (xxxp->channel[chan].dlci != -2)
  220                                         continue;
  221                         if (chan == XXX_NUM_DLCIS)
  222                                 return (ENOBUFS);
  223                 }
  224                 if (xxxp->channel[chan].hook != NULL)
  225                         return (EADDRINUSE);
  226                 NG_HOOK_SET_PRIVATE(hook, xxxp->channel + chan);
  227                 xxxp->channel[chan].hook = hook;
  228                 return (0);
  229         } else if (strcmp(name, NG_XXX_HOOK_DOWNSTREAM) == 0) {
  230                 /* Example of simple predefined hooks. */
  231                 /* do something specific to the downstream connection */
  232                 xxxp->downstream_hook.hook = hook;
  233                 NG_HOOK_SET_PRIVATE(hook, &xxxp->downstream_hook);
  234         } else if (strcmp(name, NG_XXX_HOOK_DEBUG) == 0) {
  235                 /* do something specific to a debug connection */
  236                 xxxp->debughook = hook;
  237                 NG_HOOK_SET_PRIVATE(hook, NULL);
  238         } else
  239                 return (EINVAL);        /* not a hook we know about */
  240         return(0);
  241 }
  242 
  243 /*
  244  * Get a netgraph control message.
  245  * We actually recieve a queue item that has a pointer to the message.
  246  * If we free the item, the message will be freed too, unless we remove
  247  * it from the item using NGI_GET_MSG();
  248  * The return address is also stored in the item, as an ng_ID_t,
  249  * accessible as NGI_RETADDR(item);
  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, item_p item, hook_p lasthook)
  261 {
  262         const xxx_p xxxp = NG_NODE_PRIVATE(node);
  263         struct ng_mesg *resp = NULL;
  264         int error = 0;
  265         struct ng_mesg *msg;
  266 
  267         NGI_GET_MSG(item, msg);
  268         /* Deal with message according to cookie and command */
  269         switch (msg->header.typecookie) {
  270         case NGM_XXX_COOKIE: 
  271                 switch (msg->header.cmd) {
  272                 case NGM_XXX_GET_STATUS:
  273                     {
  274                         struct ngxxxstat *stats;
  275 
  276                         NG_MKRESPONSE(resp, msg, sizeof(*stats), M_NOWAIT);
  277                         if (!resp) {
  278                                 error = ENOMEM;
  279                                 break;
  280                         }
  281                         stats = (struct ngxxxstat *) resp->data;
  282                         stats->packets_in = xxxp->packets_in;
  283                         stats->packets_out = xxxp->packets_out;
  284                         break;
  285                     }
  286                 case NGM_XXX_SET_FLAG:
  287                         if (msg->header.arglen != sizeof(u_int32_t)) {
  288                                 error = EINVAL;
  289                                 break;
  290                         }
  291                         xxxp->flags = *((u_int32_t *) msg->data);
  292                         break;
  293                 default:
  294                         error = EINVAL;         /* unknown command */
  295                         break;
  296                 }
  297                 break;
  298         default:
  299                 error = EINVAL;                 /* unknown cookie type */
  300                 break;
  301         }
  302 
  303         /* Take care of synchronous response, if any */
  304         NG_RESPOND_MSG(error, node, item, resp);
  305         /* Free the message and return */
  306         NG_FREE_MSG(msg);
  307         return(error);
  308 }
  309 
  310 /*
  311  * Receive data, and do something with it.
  312  * Actually we receive a queue item which holds the data.
  313  * If we free the item it will also free the data unless we have
  314  * previously disassociated it using the NGI_GET_M() macro.
  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, so if we use up this data or
  318  * abort we must free it.
  319  *
  320  * If we want, we may decide to force this data to be queued and reprocessed
  321  * at the netgraph NETISR time.
  322  * We would do that by setting the HK_QUEUE flag on our hook. We would do that
  323  * in the connect() method. 
  324  */
  325 static int
  326 ng_xxx_rcvdata(hook_p hook, item_p item )
  327 {
  328         const xxx_p xxxp = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  329         int chan = -2;
  330         int dlci = -2;
  331         int error;
  332         struct mbuf *m;
  333 
  334         NGI_GET_M(item, m);
  335         if (NG_HOOK_PRIVATE(hook)) {
  336                 dlci = ((struct XXX_hookinfo *) NG_HOOK_PRIVATE(hook))->dlci;
  337                 chan = ((struct XXX_hookinfo *) NG_HOOK_PRIVATE(hook))->channel;
  338                 if (dlci != -1) {
  339                         /* If received on a DLCI hook process for this
  340                          * channel and pass it to the downstream module.
  341                          * Normally one would add a multiplexing header at
  342                          * the front here */
  343                         /* M_PREPEND(....)      ; */
  344                         /* mtod(m, xxxxxx)->dlci = dlci; */
  345                         NG_FWD_NEW_DATA(error, item, 
  346                                 xxxp->downstream_hook.hook, m);
  347                         xxxp->packets_out++;
  348                 } else {
  349                         /* data came from the multiplexed link */
  350                         dlci = 1;       /* get dlci from header */
  351                         /* madjust(....) *//* chop off header */
  352                         for (chan = 0; chan < XXX_NUM_DLCIS; chan++)
  353                                 if (xxxp->channel[chan].dlci == dlci)
  354                                         break;
  355                         if (chan == XXX_NUM_DLCIS) {
  356                                 NG_FREE_ITEM(item);
  357                                 NG_FREE_M(m);
  358                                 return (ENETUNREACH);
  359                         }
  360                         /* If we were called at splnet, use the following:
  361                          * NG_SEND_DATA_ONLY(error, otherhook, m); if this
  362                          * node is running at some SPL other than SPLNET
  363                          * then you should use instead: error =
  364                          * ng_queueit(otherhook, m, NULL); m = NULL;
  365                          * This queues the data using the standard NETISR
  366                          * system and schedules the data to be picked
  367                          * up again once the system has moved to SPLNET and
  368                          * the processing of the data can continue. After
  369                          * these are run 'm' should be considered
  370                          * as invalid and NG_SEND_DATA actually zaps them. */
  371                         NG_FWD_NEW_DATA(error, item,
  372                                 xxxp->channel[chan].hook, m);
  373                         xxxp->packets_in++;
  374                 }
  375         } else {
  376                 /* It's the debug hook, throw it away.. */
  377                 if (hook == xxxp->downstream_hook.hook) {
  378                         NG_FREE_ITEM(item);
  379                         NG_FREE_M(m);
  380                 }
  381         }
  382         return 0;
  383 }
  384 
  385 #if 0
  386 /*
  387  * If this were a device node, the data may have been received in response
  388  * to some interrupt.
  389  * in which case it would probably look as follows:
  390  */
  391 devintr()
  392 {
  393         int error;
  394                                  * here */
  395 
  396         /* get packet from device and send on */
  397         m = MGET(blah blah)
  398         
  399         NG_SEND_DATA_ONLY(error, xxxp->upstream_hook.hook, m);
  400                                 /* see note above in xxx_rcvdata() */
  401                                 /* and ng_xxx_connect() */
  402 }
  403 
  404 #endif                          /* 0 */
  405 
  406 /*
  407  * Do local shutdown processing..
  408  * All our links and the name have already been removed.
  409  * If we are a persistant device, we might refuse to go away.
  410  * In the case of a persistant node we signal the framework that we
  411  * are still in business by clearing the NGF_INVALID bit. However
  412  * If we find the NGF_REALLY_DIE bit set, this means that
  413  * we REALLY need to die (e.g. hardware removed).
  414  * This would have been set using the NG_NODE_REALLY_DIE(node)
  415  * macro in some device dependent function (not shown here) before
  416  * calling ng_rmnode_self().
  417  */
  418 static int
  419 ng_xxx_shutdown(node_p node)
  420 {
  421         const xxx_p privdata = NG_NODE_PRIVATE(node);
  422 
  423 #ifndef PERSISTANT_NODE
  424         NG_NODE_SET_PRIVATE(node, NULL);
  425         NG_NODE_UNREF(node);
  426         FREE(privdata, M_NETGRAPH);
  427 #else
  428         if (node->nd_flags & NGF_REALLY_DIE) {
  429                 /*
  430                  * WE came here because the widget card is being unloaded,
  431                  * so stop being persistant.
  432                  * Actually undo all the things we did on creation.
  433                  */
  434                 NG_NODE_SET_PRIVATE(node, NULL);
  435                 NG_NODE_UNREF(privdata->node);
  436                 FREE(privdata, M_NETGRAPH);
  437                 return (0);   
  438         }
  439         NG_NODE_REVIVE(node);           /* tell ng_rmnode() we will persist */
  440 #endif /* PERSISTANT_NODE */
  441         return (0);
  442 }
  443 
  444 /*
  445  * This is called once we've already connected a new hook to the other node.
  446  * It gives us a chance to balk at the last minute.
  447  */
  448 static int
  449 ng_xxx_connect(hook_p hook)
  450 {
  451 #if 0
  452         /*
  453          * If we were a driver running at other than splnet then
  454          * we should set the QUEUE bit on the edge so that we
  455          * will deliver by queing.
  456          */
  457         if /*it is the upstream hook */
  458         NG_HOOK_FORCE_QUEUE(NG_HOOK_PEER(hook));
  459 #endif
  460 #if 0
  461         /*
  462          * If for some reason we want incoming date to be queued
  463          * by the NETISR system and delivered later we can set the same bit on
  464          * OUR hook. (maybe to allow unwinding of the stack)
  465          */
  466 
  467         if (NG_HOOK_PRIVATE(hook)) {
  468                 int dlci;
  469                 /* 
  470                  * If it's dlci 1023, requeue it so that it's handled
  471                  * at a lower priority. This is how a node decides to
  472                  * defer a data message.
  473                  */
  474                 dlci = ((struct XXX_hookinfo *) NG_HOOK_PRIVATE(hook))->dlci;
  475                 if (dlci == 1023) {
  476                         NG_HOOK_FORCE_QUEUE(hook);
  477                 }
  478 #endif
  479         /* otherwise be really amiable and just say "YUP that's OK by me! " */
  480         return (0);
  481 }
  482 
  483 /*
  484  * Hook disconnection
  485  *
  486  * For this type, removal of the last link destroys the node
  487  */
  488 static int
  489 ng_xxx_disconnect(hook_p hook)
  490 {
  491         if (NG_HOOK_PRIVATE(hook))
  492                 ((struct XXX_hookinfo *) (NG_HOOK_PRIVATE(hook)))->hook = NULL;
  493         if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
  494         && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) /* already shutting down? */
  495                 ng_rmnode_self(NG_HOOK_NODE(hook));
  496         return (0);
  497 }
  498 

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