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

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    1 
    2 /*
    3  * ng_frame_relay.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/5.2/sys/netgraph/ng_frame_relay.c 111119 2003-02-19 05:47:46Z imp $
   40  * $Whistle: ng_frame_relay.c,v 1.20 1999/11/01 09:24:51 julian Exp $
   41  */
   42 
   43 /*
   44  * This node implements the frame relay protocol, not including
   45  * the LMI line management. This means basically keeping track
   46  * of which DLCI's are active, doing frame (de)multiplexing, etc.
   47  *
   48  * It has a 'downstream' hook that goes to the line, and a
   49  * hook for each DLCI (eg, 'dlci16').
   50  */
   51 
   52 #include <sys/param.h>
   53 #include <sys/systm.h>
   54 #include <sys/kernel.h>
   55 #include <sys/errno.h>
   56 #include <sys/malloc.h>
   57 #include <sys/mbuf.h>
   58 #include <sys/syslog.h>
   59 #include <sys/ctype.h>
   60 
   61 #include <netgraph/ng_message.h>
   62 #include <netgraph/netgraph.h>
   63 #include <netgraph/ng_frame_relay.h>
   64 
   65 /*
   66  * Line info, and status per channel.
   67  */
   68 struct ctxinfo {                /* one per active hook */
   69         u_int   flags;
   70 #define CHAN_VALID      0x01    /* assigned to a channel */
   71 #define CHAN_ACTIVE     0x02    /* bottom level active */
   72         int     dlci;           /* the dlci assigned to this context */
   73         hook_p  hook;           /* if there's a hook assigned.. */
   74 };
   75 
   76 #define MAX_CT 16               /* # of dlci's active at a time (POWER OF 2!) */
   77 struct frmrel_softc {
   78         int     unit;           /* which card are we? */
   79         int     datahooks;      /* number of data hooks attached */
   80         node_p  node;           /* netgraph node */
   81         int     addrlen;        /* address header length */
   82         int     flags;          /* state */
   83         int     mtu;            /* guess */
   84         u_char  remote_seq;     /* sequence number the remote sent */
   85         u_char  local_seq;      /* sequence number the remote rcvd */
   86         u_short ALT[1024];      /* map DLCIs to CTX */
   87 #define CTX_VALID       0x8000          /* this bit means it's a valid CTX */
   88 #define CTX_VALUE       (MAX_CT - 1)    /* mask for context part */
   89         struct  ctxinfo channel[MAX_CT];
   90         struct  ctxinfo downstream;
   91 };
   92 typedef struct frmrel_softc *sc_p;
   93 
   94 #define BYTEX_EA        0x01    /* End Address. Always 0 on byte1 */
   95 #define BYTE1_C_R       0x02
   96 #define BYTE2_FECN      0x08    /* forwards congestion notification */
   97 #define BYTE2_BECN      0x04    /* Backward congestion notification */
   98 #define BYTE2_DE        0x02    /* Discard elligability */
   99 #define LASTBYTE_D_C    0x02    /* last byte is dl_core or dlci info */
  100 
  101 /* Used to do headers */
  102 static struct segment {
  103         u_char  mask;
  104         u_char  shift;
  105         u_char  width;
  106 } makeup[] = {
  107         { 0xfc, 2, 6 },
  108         { 0xf0, 4, 4 },
  109         { 0xfe, 1, 7 },
  110         { 0xfc, 2, 6 }
  111 };
  112 
  113 #define SHIFTIN(segment, byte, dlci)                                         \
  114         {                                                                    \
  115                 (dlci) <<= (segment)->width;                                 \
  116                 (dlci) |=                                                    \
  117                         (((byte) & (segment)->mask) >> (segment)->shift);    \
  118         }
  119 
  120 #define SHIFTOUT(segment, byte, dlci)                                        \
  121         {                                                                    \
  122                 (byte) |= (((dlci) << (segment)->shift) & (segment)->mask);  \
  123                 (dlci) >>= (segment)->width;                                 \
  124         }
  125 
  126 /* Netgraph methods */
  127 static ng_constructor_t ngfrm_constructor;
  128 static ng_shutdown_t    ngfrm_shutdown;
  129 static ng_newhook_t     ngfrm_newhook;
  130 static ng_rcvdata_t     ngfrm_rcvdata;
  131 static ng_disconnect_t  ngfrm_disconnect;
  132 
  133 /* Other internal functions */
  134 static int ngfrm_decode(node_p node, item_p item);
  135 static int ngfrm_addrlen(char *hdr);
  136 static int ngfrm_allocate_CTX(sc_p sc, int dlci);
  137 
  138 /* Netgraph type */
  139 static struct ng_type typestruct = {
  140         NG_ABI_VERSION,
  141         NG_FRAMERELAY_NODE_TYPE,
  142         NULL,
  143         ngfrm_constructor,
  144         NULL,
  145         ngfrm_shutdown,
  146         ngfrm_newhook,
  147         NULL,
  148         NULL,
  149         ngfrm_rcvdata,
  150         ngfrm_disconnect,
  151         NULL
  152 };
  153 NETGRAPH_INIT(framerelay, &typestruct);
  154 
  155 /*
  156  * Given a DLCI, return the index of the  context table entry for it,
  157  * Allocating a new one if needs be, or -1 if none available.
  158  */
  159 static int
  160 ngfrm_allocate_CTX(sc_p sc, int dlci)
  161 {
  162         u_int   ctxnum = -1;    /* what ctx number we are using */
  163         volatile struct ctxinfo *CTXp = NULL;
  164 
  165         /* Sanity check the dlci value */
  166         if (dlci > 1023)
  167                 return (-1);
  168 
  169         /* Check to see if we already have an entry for this DLCI */
  170         if (sc->ALT[dlci]) {
  171                 if ((ctxnum = sc->ALT[dlci] & CTX_VALUE) < MAX_CT) {
  172                         CTXp = sc->channel + ctxnum;
  173                 } else {
  174                         ctxnum = -1;
  175                         sc->ALT[dlci] = 0;      /* paranoid but... */
  176                 }
  177         }
  178 
  179         /*
  180          * If the index has no valid entry yet, then we need to allocate a
  181          * CTX number to it
  182          */
  183         if (CTXp == NULL) {
  184                 for (ctxnum = 0; ctxnum < MAX_CT; ctxnum++) {
  185                         /*
  186                          * If the VALID flag is empty it is unused
  187                          */
  188                         if ((sc->channel[ctxnum].flags & CHAN_VALID) == 0) {
  189                                 bzero(sc->channel + ctxnum,
  190                                       sizeof(struct ctxinfo));
  191                                 CTXp = sc->channel + ctxnum;
  192                                 sc->ALT[dlci] = ctxnum | CTX_VALID;
  193                                 sc->channel[ctxnum].dlci = dlci;
  194                                 sc->channel[ctxnum].flags = CHAN_VALID;
  195                                 break;
  196                         }
  197                 }
  198         }
  199 
  200         /*
  201          * If we still don't have a CTX pointer, then we never found a free
  202          * spot so give up now..
  203          */
  204         if (!CTXp) {
  205                 log(LOG_ERR, "No CTX available for dlci %d\n", dlci);
  206                 return (-1);
  207         }
  208         return (ctxnum);
  209 }
  210 
  211 /*
  212  * Node constructor
  213  */
  214 static int
  215 ngfrm_constructor(node_p node)
  216 {
  217         sc_p sc;
  218 
  219         MALLOC(sc, sc_p, sizeof(*sc), M_NETGRAPH, M_NOWAIT | M_ZERO);
  220         if (!sc)
  221                 return (ENOMEM);
  222         sc->addrlen = 2;        /* default */
  223 
  224         /* Link the node and our private info */
  225         NG_NODE_SET_PRIVATE(node, sc);
  226         sc->node = node;
  227         return (0);
  228 }
  229 
  230 /*
  231  * Add a new hook
  232  *
  233  * We allow hooks called "debug", "downstream" and dlci[0-1023]
  234  * The hook's private info points to our stash of info about that
  235  * channel. A NULL pointer is debug and a DLCI of -1 means downstream.
  236  */
  237 static int
  238 ngfrm_newhook(node_p node, hook_p hook, const char *name)
  239 {
  240         const sc_p sc = NG_NODE_PRIVATE(node);
  241         const char *cp;
  242         char *eptr;
  243         int dlci = 0;
  244         int ctxnum;
  245 
  246         /* Check if it's our friend the control hook */
  247         if (strcmp(name, NG_FRAMERELAY_HOOK_DEBUG) == 0) {
  248                 NG_HOOK_SET_PRIVATE(hook, NULL);        /* paranoid */
  249                 return (0);
  250         }
  251 
  252         /*
  253          * All other hooks either start with 'dlci' and have a decimal
  254          * trailing channel number up to 4 digits, or are the downstream
  255          * hook.
  256          */
  257         if (strncmp(name, NG_FRAMERELAY_HOOK_DLCI,
  258             strlen(NG_FRAMERELAY_HOOK_DLCI)) != 0) {
  259 
  260                 /* It must be the downstream connection */
  261                 if (strcmp(name, NG_FRAMERELAY_HOOK_DOWNSTREAM) != 0)
  262                         return EINVAL;
  263 
  264                 /* Make sure we haven't already got one (paranoid) */
  265                 if (sc->downstream.hook)
  266                         return (EADDRINUSE);
  267 
  268                 /* OK add it */
  269                 NG_HOOK_SET_PRIVATE(hook, &sc->downstream);
  270                 sc->downstream.hook = hook;
  271                 sc->downstream.dlci = -1;
  272                 sc->downstream.flags |= CHAN_ACTIVE;
  273                 sc->datahooks++;
  274                 return (0);
  275         }
  276 
  277         /* Must be a dlci hook at this point */
  278         cp = name + strlen(NG_FRAMERELAY_HOOK_DLCI);
  279         if (!isdigit(*cp) || (cp[0] == '' && cp[1] != '\0'))
  280                 return (EINVAL);
  281         dlci = (int)strtoul(cp, &eptr, 10);
  282         if (*eptr != '\0' || dlci < 0 || dlci > 1023)
  283                 return (EINVAL);
  284 
  285         /*
  286          * We have a dlci, now either find it, or allocate it. It's possible
  287          * that we might have seen packets for it already and made an entry
  288          * for it.
  289          */
  290         ctxnum = ngfrm_allocate_CTX(sc, dlci);
  291         if (ctxnum == -1)
  292                 return (ENOBUFS);
  293 
  294         /*
  295          * Be paranoid: if it's got a hook already, that dlci is in use .
  296          * Generic code can not catch all the synonyms (e.g. dlci016 vs
  297          * dlci16)
  298          */
  299         if (sc->channel[ctxnum].hook != NULL)
  300                 return (EADDRINUSE);
  301 
  302         /*
  303          * Put our hooks into it (pun not intended)
  304          */
  305         sc->channel[ctxnum].flags |= CHAN_ACTIVE;
  306         NG_HOOK_SET_PRIVATE(hook, sc->channel + ctxnum);
  307         sc->channel[ctxnum].hook = hook;
  308         sc->datahooks++;
  309         return (0);
  310 }
  311 
  312 /*
  313  * Count up the size of the address header if we don't already know
  314  */
  315 int
  316 ngfrm_addrlen(char *hdr)
  317 {
  318         if (hdr[0] & BYTEX_EA)
  319                 return 0;
  320         if (hdr[1] & BYTEX_EA)
  321                 return 2;
  322         if (hdr[2] & BYTEX_EA)
  323                 return 3;
  324         if (hdr[3] & BYTEX_EA)
  325                 return 4;
  326         return 0;
  327 }
  328 
  329 /*
  330  * Receive data packet
  331  */
  332 static int
  333 ngfrm_rcvdata(hook_p hook, item_p item)
  334 {
  335         struct  ctxinfo *const ctxp = NG_HOOK_PRIVATE(hook);
  336         int     error = 0;
  337         int     dlci;
  338         sc_p    sc;
  339         int     alen;
  340         char   *data;
  341         struct mbuf *m;
  342 
  343         /* Data doesn't come in from just anywhere (e.g debug hook) */
  344         if (ctxp == NULL) {
  345                 error = ENETDOWN;
  346                 goto bad;
  347         }
  348 
  349         /* If coming from downstream, decode it to a channel */
  350         dlci = ctxp->dlci;
  351         if (dlci == -1)
  352                 return (ngfrm_decode(NG_HOOK_NODE(hook), item));
  353 
  354         NGI_GET_M(item, m);
  355         /* Derive the softc we will need */
  356         sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  357 
  358         /* If there is no live channel, throw it away */
  359         if ((sc->downstream.hook == NULL)
  360             || ((ctxp->flags & CHAN_ACTIVE) == 0)) {
  361                 error = ENETDOWN;
  362                 goto bad;
  363         }
  364 
  365         /* Store the DLCI on the front of the packet */
  366         alen = sc->addrlen;
  367         if (alen == 0)
  368                 alen = 2;       /* default value for transmit */
  369         M_PREPEND(m, alen, M_DONTWAIT);
  370         if (m == NULL) {
  371                 error = ENOBUFS;
  372                 goto bad;
  373         }
  374         data = mtod(m, char *);
  375 
  376         /*
  377          * Shift the lowest bits into the address field untill we are done.
  378          * First byte is MSBits of addr so work backwards.
  379          */
  380         switch (alen) {
  381         case 2:
  382                 data[0] = data[1] = '\0';
  383                 SHIFTOUT(makeup + 1, data[1], dlci);
  384                 SHIFTOUT(makeup + 0, data[0], dlci);
  385                 data[1] |= BYTEX_EA;
  386                 break;
  387         case 3:
  388                 data[0] = data[1] = data[2] = '\0';
  389                 SHIFTOUT(makeup + 3, data[2], dlci);    /* 3 and 2 is correct */
  390                 SHIFTOUT(makeup + 1, data[1], dlci);
  391                 SHIFTOUT(makeup + 0, data[0], dlci);
  392                 data[2] |= BYTEX_EA;
  393                 break;
  394         case 4:
  395                 data[0] = data[1] = data[2] = data[3] = '\0';
  396                 SHIFTOUT(makeup + 3, data[3], dlci);
  397                 SHIFTOUT(makeup + 2, data[2], dlci);
  398                 SHIFTOUT(makeup + 1, data[1], dlci);
  399                 SHIFTOUT(makeup + 0, data[0], dlci);
  400                 data[3] |= BYTEX_EA;
  401                 break;
  402         default:
  403                 panic(__func__);
  404         }
  405 
  406         /* Send it */
  407         NG_FWD_NEW_DATA(error, item, sc->downstream.hook, m);
  408         return (error);
  409 
  410 bad:
  411         NG_FREE_ITEM(item);
  412         NG_FREE_M(m);
  413         return (error);
  414 }
  415 
  416 /*
  417  * Decode an incoming frame coming from the switch
  418  */
  419 static int
  420 ngfrm_decode(node_p node, item_p item)
  421 {
  422         const sc_p  sc = NG_NODE_PRIVATE(node);
  423         char       *data;
  424         int         alen;
  425         u_int       dlci = 0;
  426         int         error = 0;
  427         int         ctxnum;
  428         struct mbuf *m;
  429 
  430         NGI_GET_M(item, m);
  431         if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
  432                 error = ENOBUFS;
  433                 goto out;
  434         }
  435         data = mtod(m, char *);
  436         if ((alen = sc->addrlen) == 0) {
  437                 sc->addrlen = alen = ngfrm_addrlen(data);
  438         }
  439         switch (alen) {
  440         case 2:
  441                 SHIFTIN(makeup + 0, data[0], dlci);
  442                 SHIFTIN(makeup + 1, data[1], dlci);
  443                 break;
  444         case 3:
  445                 SHIFTIN(makeup + 0, data[0], dlci);
  446                 SHIFTIN(makeup + 1, data[1], dlci);
  447                 SHIFTIN(makeup + 3, data[2], dlci);     /* 3 and 2 is correct */
  448                 break;
  449         case 4:
  450                 SHIFTIN(makeup + 0, data[0], dlci);
  451                 SHIFTIN(makeup + 1, data[1], dlci);
  452                 SHIFTIN(makeup + 2, data[2], dlci);
  453                 SHIFTIN(makeup + 3, data[3], dlci);
  454                 break;
  455         default:
  456                 error = EINVAL;
  457                 goto out;
  458         }
  459 
  460         if (dlci > 1023) {
  461                 error = EINVAL;
  462                 goto out;
  463         }
  464         ctxnum = sc->ALT[dlci];
  465         if ((ctxnum & CTX_VALID) && sc->channel[ctxnum &= CTX_VALUE].hook) {
  466                 /* Send it */
  467                 m_adj(m, alen);
  468                 NG_FWD_NEW_DATA(error, item, sc->channel[ctxnum].hook, m);
  469                 return (error);
  470         } else {
  471                 error = ENETDOWN;
  472         }
  473 out:
  474         NG_FREE_ITEM(item);
  475         NG_FREE_M(m);
  476         return (error);
  477 }
  478 
  479 /*
  480  * Shutdown node
  481  */
  482 static int
  483 ngfrm_shutdown(node_p node)
  484 {
  485         const sc_p sc = NG_NODE_PRIVATE(node);
  486 
  487         NG_NODE_SET_PRIVATE(node, NULL);
  488         FREE(sc, M_NETGRAPH);
  489         NG_NODE_UNREF(node);
  490         return (0);
  491 }
  492 
  493 /*
  494  * Hook disconnection
  495  *
  496  * Invalidate the private data associated with this dlci.
  497  * For this type, removal of the last link resets tries to destroy the node.
  498  */
  499 static int
  500 ngfrm_disconnect(hook_p hook)
  501 {
  502         const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  503         struct ctxinfo *const cp = NG_HOOK_PRIVATE(hook);
  504         int dlci;
  505 
  506         /* If it's a regular dlci hook, then free resources etc.. */
  507         if (cp != NULL) {
  508                 cp->hook = NULL;
  509                 dlci = cp->dlci;
  510                 if (dlci != -1)
  511                         sc->ALT[dlci] = 0;
  512                 cp->flags = 0;
  513                 sc->datahooks--;
  514         }
  515         if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
  516         && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook))))
  517                 ng_rmnode_self(NG_HOOK_NODE(hook));
  518         return (0);
  519 }

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