The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/netgraph/ng_device.c

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    1 /*-
    2  * Copyright (c) 2002 Mark Santcroos <marks@ripe.net>
    3  * Copyright (c) 2004 Gleb Smirnoff <glebius@FreeBSD.org>
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   15  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
   16  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
   17  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
   18  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
   19  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   20  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   21  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
   23  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   24  *
   25  * Netgraph "device" node
   26  *
   27  * This node presents a /dev/ngd%d device that interfaces to an other
   28  * netgraph node.
   29  *
   30  * $FreeBSD: releng/5.4/sys/netgraph/ng_device.c 142772 2005-02-28 09:54:28Z glebius $
   31  *
   32  */
   33 
   34 #if 0
   35 #define DBG do { printf("ng_device: %s\n", __func__ ); } while (0)
   36 #else
   37 #define DBG do {} while (0)
   38 #endif
   39 
   40 #include <sys/param.h>
   41 #include <sys/conf.h>
   42 #include <sys/ioccom.h>
   43 #include <sys/kernel.h>
   44 #include <sys/malloc.h>
   45 #include <sys/mbuf.h>
   46 #include <sys/poll.h>
   47 #include <sys/queue.h>
   48 #include <sys/socket.h>
   49 #include <sys/systm.h>
   50 #include <sys/uio.h>
   51 #include <sys/vnode.h>
   52 
   53 #include <net/if.h>
   54 #include <net/if_var.h>
   55 #include <netinet/in.h>
   56 #include <netinet/in_systm.h>
   57 #include <netinet/ip.h>
   58 
   59 #include <netgraph/ng_message.h>
   60 #include <netgraph/netgraph.h>
   61 #include <netgraph/ng_device.h>
   62 
   63 #define ERROUT(x) do { error = (x); goto done; } while (0)
   64 
   65 /* Netgraph methods */
   66 static ng_constructor_t ng_device_constructor;
   67 static ng_rcvmsg_t      ng_device_rcvmsg;
   68 static ng_shutdown_t    ng_device_shutdown;
   69 static ng_newhook_t     ng_device_newhook;
   70 static ng_rcvdata_t     ng_device_rcvdata;
   71 static ng_disconnect_t  ng_device_disconnect;
   72 
   73 /* Netgraph type */
   74 static struct ng_type ngd_typestruct = {
   75         .version =      NG_ABI_VERSION,
   76         .name =         NG_DEVICE_NODE_TYPE,
   77         .constructor =  ng_device_constructor,
   78         .rcvmsg =       ng_device_rcvmsg,
   79         .shutdown =     ng_device_shutdown,
   80         .newhook =      ng_device_newhook,
   81         .rcvdata =      ng_device_rcvdata,
   82         .disconnect =   ng_device_disconnect,
   83 };
   84 NETGRAPH_INIT(device, &ngd_typestruct);
   85 
   86 /* per node data */
   87 struct ngd_private {
   88         struct  ifqueue readq;
   89         SLIST_ENTRY(ngd_private) links;
   90         struct  ng_node *node;
   91         struct  ng_hook *hook;
   92         struct  cdev    *ngddev;
   93         struct  mtx     ngd_mtx;
   94         int             unit;
   95         uint16_t        flags;
   96 #define NGDF_OPEN       0x0001
   97 #define NGDF_RWAIT      0x0002
   98 };
   99 typedef struct ngd_private *priv_p;
  100 
  101 /* List of all active nodes and mutex to protect it */
  102 static SLIST_HEAD(, ngd_private) ngd_nodes = SLIST_HEAD_INITIALIZER(ngd_nodes);
  103 static struct mtx       ng_device_mtx;
  104 MTX_SYSINIT(ng_device, &ng_device_mtx, "ng_device", MTX_DEF);
  105 
  106 /* Maximum number of NGD devices */
  107 #define MAX_NGD 25      /* should be more than enough for now */
  108 
  109 static d_close_t ngdclose;
  110 static d_open_t ngdopen;
  111 static d_read_t ngdread;
  112 static d_write_t ngdwrite;
  113 #if 0
  114 static d_ioctl_t ngdioctl;
  115 #endif
  116 static d_poll_t ngdpoll;
  117 
  118 static struct cdevsw ngd_cdevsw = {
  119         .d_version =    D_VERSION,
  120         .d_open =       ngdopen,
  121         .d_close =      ngdclose,
  122         .d_read =       ngdread,
  123         .d_write =      ngdwrite,
  124 #if 0
  125         .d_ioctl =      ngdioctl,
  126 #endif
  127         .d_poll =       ngdpoll,
  128         .d_name =       NG_DEVICE_DEVNAME,
  129 };
  130 
  131 /* Helper functions */
  132 static int get_free_unit(void);
  133 
  134 /******************************************************************************
  135  *  Netgraph methods
  136  ******************************************************************************/
  137 
  138 /*
  139  * create new node
  140  */
  141 static int
  142 ng_device_constructor(node_p node)
  143 {
  144         priv_p  priv;
  145 
  146         DBG;
  147 
  148         MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH, M_NOWAIT | M_ZERO);
  149         if (priv == NULL)
  150                 return (ENOMEM);
  151 
  152         mtx_lock(&ng_device_mtx);
  153         priv->unit = get_free_unit();
  154         if(priv->unit < 0) {
  155                 printf("%s: No free unit found by get_free_unit(), "
  156                                 "increase MAX_NGD\n",__func__);
  157                 mtx_unlock(&ng_device_mtx);
  158                 FREE(priv, M_NETGRAPH);
  159                 return(EINVAL);
  160         }
  161         SLIST_INSERT_HEAD(&ngd_nodes, priv, links);
  162         mtx_unlock(&ng_device_mtx);
  163 
  164         /* Initialize mutexes and queue */
  165         mtx_init(&priv->ngd_mtx, "ng_device", NULL, MTX_DEF);
  166         mtx_init(&priv->readq.ifq_mtx, "ng_device queue", NULL, MTX_DEF);
  167         IFQ_SET_MAXLEN(&priv->readq, ifqmaxlen);
  168 
  169         /* Link everything together */
  170         NG_NODE_SET_PRIVATE(node, priv);
  171         priv->node = node;
  172 
  173         priv->ngddev = make_dev(&ngd_cdevsw, unit2minor(priv->unit), UID_ROOT,
  174             GID_WHEEL, 0600, NG_DEVICE_DEVNAME "%d", priv->unit);
  175         if(priv->ngddev == NULL) {
  176                 printf("%s(): make_dev() failed\n",__func__);
  177                 mtx_destroy(&priv->ngd_mtx);
  178                 mtx_destroy(&priv->readq.ifq_mtx);
  179                 FREE(priv, M_NETGRAPH);
  180                 return(EINVAL);
  181         }
  182         /* XXX: race here? */
  183         priv->ngddev->si_drv1 = priv;
  184 
  185         return(0);
  186 }
  187 
  188 /*
  189  * Process control message.
  190  */
  191 
  192 static int
  193 ng_device_rcvmsg(node_p node, item_p item, hook_p lasthook)
  194 {
  195         const priv_p priv = NG_NODE_PRIVATE(node);
  196         struct ng_mesg *msg;
  197         struct ng_mesg *resp = NULL;
  198         int error = 0;
  199 
  200         NGI_GET_MSG(item, msg);
  201 
  202         if (msg->header.typecookie == NGM_DEVICE_COOKIE) {
  203                 switch (msg->header.cmd) {
  204                 case NGM_DEVICE_GET_DEVNAME:
  205                         /* XXX: Fix when NGD_MAX us bigger */
  206                         NG_MKRESPONSE(resp, msg,
  207                             strlen(NG_DEVICE_DEVNAME) + 3, M_NOWAIT);
  208 
  209                         if (resp == NULL)
  210                                 ERROUT(ENOMEM);
  211 
  212                         strlcpy((char *)resp->data, priv->ngddev->si_name,
  213                             strlen(priv->ngddev->si_name) + 1);
  214                         break;
  215 
  216                 default:
  217                         error = EINVAL;
  218                         break;
  219                 }
  220         } else
  221                 error = EINVAL;
  222 
  223 done:
  224         NG_RESPOND_MSG(error, node, item, resp);
  225         NG_FREE_MSG(msg);
  226         return (error);
  227 }
  228 
  229 /*
  230  * Accept incoming hook. We support only one hook per node.
  231  */
  232 static int
  233 ng_device_newhook(node_p node, hook_p hook, const char *name)
  234 {
  235         priv_p priv = NG_NODE_PRIVATE(node);
  236 
  237         DBG;
  238 
  239         /* We have only one hook per node */
  240         if (priv->hook != NULL)
  241                 return (EISCONN);
  242 
  243         priv->hook = hook;
  244 
  245         return(0);
  246 }
  247 
  248 /*
  249  * Receive data from hook, write it to device.
  250  */
  251 static int
  252 ng_device_rcvdata(hook_p hook, item_p item)
  253 {
  254         priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  255         struct mbuf *m;
  256 
  257         DBG;
  258 
  259         NGI_GET_M(item, m);
  260         NG_FREE_ITEM(item);
  261 
  262         IF_LOCK(&priv->readq);
  263         if (_IF_QFULL(&priv->readq)) {
  264                 _IF_DROP(&priv->readq);
  265                 IF_UNLOCK(&priv->readq);
  266                 NG_FREE_M(m);
  267                 return (ENOBUFS);
  268         }
  269 
  270         _IF_ENQUEUE(&priv->readq, m);
  271         IF_UNLOCK(&priv->readq);
  272         mtx_lock(&priv->ngd_mtx);
  273         if (priv->flags & NGDF_RWAIT) {
  274                 priv->flags &= ~NGDF_RWAIT;
  275                 wakeup(priv);
  276         }
  277         mtx_unlock(&priv->ngd_mtx);
  278 
  279         return(0);
  280 }
  281 
  282 /*
  283  * Removal of the hook destroys the node.
  284  */
  285 static int
  286 ng_device_disconnect(hook_p hook)
  287 {
  288         priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  289 
  290         DBG;
  291 
  292         destroy_dev(priv->ngddev);
  293         mtx_destroy(&priv->ngd_mtx);
  294 
  295         mtx_lock(&ng_device_mtx);
  296         SLIST_REMOVE(&ngd_nodes, priv, ngd_private, links);
  297         mtx_unlock(&ng_device_mtx);
  298 
  299         IF_DRAIN(&priv->readq);
  300         mtx_destroy(&(priv)->readq.ifq_mtx);
  301 
  302         FREE(priv, M_NETGRAPH);
  303 
  304         ng_rmnode_self(NG_HOOK_NODE(hook));
  305 
  306         return(0);
  307 }
  308 
  309 /*
  310  * Node shutdown. Everything is already done in disconnect method.
  311  */
  312 static int
  313 ng_device_shutdown(node_p node)
  314 {
  315         NG_NODE_UNREF(node);
  316         return (0);
  317 }
  318 
  319 /******************************************************************************
  320  *  Device methods
  321  ******************************************************************************/
  322 
  323 /*
  324  * the device is opened
  325  */
  326 static int
  327 ngdopen(struct cdev *dev, int flag, int mode, struct thread *td)
  328 {
  329         priv_p  priv = (priv_p )dev->si_drv1;
  330 
  331         DBG;
  332 
  333         mtx_lock(&priv->ngd_mtx);
  334         priv->flags |= NGDF_OPEN;
  335         mtx_unlock(&priv->ngd_mtx);
  336 
  337         return(0);
  338 }
  339 
  340 /*
  341  * the device is closed
  342  */
  343 static int
  344 ngdclose(struct cdev *dev, int flag, int mode, struct thread *td)
  345 {
  346         priv_p  priv = (priv_p )dev->si_drv1;
  347 
  348         DBG;
  349         mtx_lock(&priv->ngd_mtx);
  350         priv->flags &= ~NGDF_OPEN;
  351         mtx_unlock(&priv->ngd_mtx);
  352 
  353         return(0);
  354 }
  355 
  356 #if 0   /*
  357          * The ioctl is transformed into netgraph control message.
  358          * We do not process them, yet.
  359          */
  360 /*
  361  * process ioctl
  362  *
  363  * they are translated into netgraph messages and passed on
  364  *
  365  */
  366 static int
  367 ngdioctl(struct cdev *dev, u_long cmd, caddr_t addr, int flag, struct thread *td)
  368 {
  369         struct ngd_softc *sc = &ngd_softc;
  370         struct ngd_connection * connection = NULL;
  371         struct ngd_connection * tmp;
  372         int error = 0;
  373         struct ng_mesg *msg;
  374         struct ngd_param_s * datap;
  375 
  376         DBG;
  377 
  378         SLIST_FOREACH(tmp,&sc->head,links) {
  379                 if(tmp->ngddev == dev) {
  380                         connection = tmp;
  381                 }
  382         }
  383         if(connection == NULL) {
  384                 printf("%s(): connection is still NULL, no dev found\n",__func__);
  385                 return(-1);
  386         }
  387 
  388         NG_MKMESSAGE(msg, NGM_DEVICE_COOKIE, cmd, sizeof(struct ngd_param_s),
  389                         M_NOWAIT);
  390         if (msg == NULL) {
  391                 printf("%s(): msg == NULL\n",__func__);
  392                 goto nomsg;
  393         }
  394 
  395         /* pass the ioctl data into the ->data area */
  396         datap = (struct ngd_param_s *)msg->data;
  397         datap->p = addr;
  398 
  399         NG_SEND_MSG_HOOK(error, sc->node, msg, connection->active_hook, 0);
  400         if(error)
  401                 printf("%s(): NG_SEND_MSG_HOOK error: %d\n",__func__,error);
  402 
  403 nomsg:
  404 
  405         return(0);
  406 }
  407 #endif /* if 0 */
  408 
  409 /*
  410  * This function is called when a read(2) is done to our device.
  411  * We process one mbuf from queue.
  412  */
  413 static int
  414 ngdread(struct cdev *dev, struct uio *uio, int flag)
  415 {
  416         priv_p  priv = (priv_p )dev->si_drv1;
  417         struct mbuf *m;
  418         int len, error = 0;
  419 
  420         DBG;
  421 
  422         /* get an mbuf */
  423         do {
  424                 IF_DEQUEUE(&priv->readq, m);
  425                 if (m == NULL) {
  426                         if (flag & IO_NDELAY)
  427                                 return (EWOULDBLOCK);
  428                         mtx_lock(&priv->ngd_mtx);
  429                         priv->flags |= NGDF_RWAIT;
  430                         if ((error = msleep(priv, &priv->ngd_mtx,
  431                             PDROP | PCATCH | (PZERO + 1),
  432                             "ngdread", 0)) != 0)
  433                                 return (error);
  434                 }
  435         } while (m == NULL);
  436 
  437         while (m && uio->uio_resid > 0 && error == 0) {
  438                 len = MIN(uio->uio_resid, m->m_len);
  439                 if (len != 0)
  440                         error = uiomove(mtod(m, void *), len, uio);
  441                 m = m_free(m);
  442         }
  443 
  444         if (m)
  445                 m_freem(m);
  446 
  447         return (error);
  448 }
  449 
  450 
  451 /*
  452  * This function is called when our device is written to.
  453  * We read the data from userland into mbuf chain and pass it to the remote hook.
  454  *
  455  */
  456 static int
  457 ngdwrite(struct cdev *dev, struct uio *uio, int flag)
  458 {
  459         priv_p  priv = (priv_p )dev->si_drv1;
  460         struct mbuf *m;
  461         int error = 0;
  462 
  463         DBG;
  464 
  465         if (uio->uio_resid == 0)
  466                 return (0);
  467 
  468         if (uio->uio_resid < 0 || uio->uio_resid > IP_MAXPACKET)
  469                 return (EIO);
  470 
  471         if ((m = m_uiotombuf(uio, M_DONTWAIT, 0)) == NULL)
  472                 return (ENOBUFS);
  473 
  474         NG_SEND_DATA_ONLY(error, priv->hook, m);
  475 
  476         return (error);
  477 }
  478 
  479 /*
  480  * we are being polled/selected
  481  * check if there is data available for read
  482  */
  483 static int
  484 ngdpoll(struct cdev *dev, int events, struct thread *td)
  485 {
  486         priv_p  priv = (priv_p )dev->si_drv1;
  487         int revents = 0;
  488 
  489         if (events & (POLLIN | POLLRDNORM) &&
  490             !IFQ_IS_EMPTY(&priv->readq))
  491                 revents |= events & (POLLIN | POLLRDNORM);
  492 
  493         return (revents);
  494 }
  495 
  496 /******************************************************************************
  497  *  Helper subroutines
  498  ******************************************************************************/
  499 
  500 static int
  501 get_free_unit()
  502 {
  503         struct ngd_private *priv = NULL;
  504         int n = 0;
  505         int unit = -1;
  506 
  507         DBG;
  508 
  509         mtx_assert(&ng_device_mtx, MA_OWNED);
  510 
  511         /* When there is no list yet, the first device unit is always 0. */
  512         if SLIST_EMPTY(&ngd_nodes)
  513                 return(0);
  514 
  515         /* Just do a brute force loop to find the first free unit that is
  516          * smaller than MAX_NGD.
  517          * Set MAX_NGD to a large value, doesn't impact performance.
  518          */
  519         for(n = 0; n<MAX_NGD && unit == -1; n++) {
  520                 SLIST_FOREACH(priv, &ngd_nodes, links) {
  521 
  522                         if(priv->unit == n) {
  523                                 unit = -1;
  524                                 break;
  525                         }
  526                         unit = n;
  527                 }
  528         }
  529 
  530         return (unit);
  531 }

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