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sys/netgraph/ng_pptpgre.c

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    1 /*
    2  * ng_pptpgre.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: Archie Cobbs <archie@freebsd.org>
   39  *
   40  * $FreeBSD: releng/8.1/sys/netgraph/ng_pptpgre.c 206661 2010-04-15 12:46:16Z mav $
   41  * $Whistle: ng_pptpgre.c,v 1.7 1999/12/08 00:10:06 archie Exp $
   42  */
   43 
   44 /*
   45  * PPTP/GRE netgraph node type.
   46  *
   47  * This node type does the GRE encapsulation as specified for the PPTP
   48  * protocol (RFC 2637, section 4).  This includes sequencing and
   49  * retransmission of frames, but not the actual packet delivery nor
   50  * any of the TCP control stream protocol.
   51  *
   52  * The "upper" hook of this node is suitable for attaching to a "ppp"
   53  * node link hook.  The "lower" hook of this node is suitable for attaching
   54  * to a "ksocket" node on hook "inet/raw/gre".
   55  */
   56 
   57 #include <sys/param.h>
   58 #include <sys/systm.h>
   59 #include <sys/kernel.h>
   60 #include <sys/time.h>
   61 #include <sys/lock.h>
   62 #include <sys/malloc.h>
   63 #include <sys/mbuf.h>
   64 #include <sys/mutex.h>
   65 #include <sys/endian.h>
   66 #include <sys/errno.h>
   67 
   68 #include <netinet/in.h>
   69 #include <netinet/in_systm.h>
   70 #include <netinet/ip.h>
   71 
   72 #include <netgraph/ng_message.h>
   73 #include <netgraph/netgraph.h>
   74 #include <netgraph/ng_parse.h>
   75 #include <netgraph/ng_pptpgre.h>
   76 
   77 /* GRE packet format, as used by PPTP */
   78 struct greheader {
   79 #if BYTE_ORDER == LITTLE_ENDIAN
   80         u_char          recursion:3;            /* recursion control */
   81         u_char          ssr:1;                  /* strict source route */
   82         u_char          hasSeq:1;               /* sequence number present */
   83         u_char          hasKey:1;               /* key present */
   84         u_char          hasRoute:1;             /* routing present */
   85         u_char          hasSum:1;               /* checksum present */
   86         u_char          vers:3;                 /* version */
   87         u_char          flags:4;                /* flags */
   88         u_char          hasAck:1;               /* acknowlege number present */
   89 #elif BYTE_ORDER == BIG_ENDIAN
   90         u_char          hasSum:1;               /* checksum present */
   91         u_char          hasRoute:1;             /* routing present */
   92         u_char          hasKey:1;               /* key present */
   93         u_char          hasSeq:1;               /* sequence number present */
   94         u_char          ssr:1;                  /* strict source route */
   95         u_char          recursion:3;            /* recursion control */
   96         u_char          hasAck:1;               /* acknowlege number present */
   97         u_char          flags:4;                /* flags */
   98         u_char          vers:3;                 /* version */
   99 #else
  100 #error BYTE_ORDER is not defined properly
  101 #endif
  102         u_int16_t       proto;                  /* protocol (ethertype) */
  103         u_int16_t       length;                 /* payload length */
  104         u_int16_t       cid;                    /* call id */
  105         u_int32_t       data[0];                /* opt. seq, ack, then data */
  106 };
  107 
  108 /* The PPTP protocol ID used in the GRE 'proto' field */
  109 #define PPTP_GRE_PROTO          0x880b
  110 
  111 /* Bits that must be set a certain way in all PPTP/GRE packets */
  112 #define PPTP_INIT_VALUE         ((0x2001 << 16) | PPTP_GRE_PROTO)
  113 #define PPTP_INIT_MASK          0xef7fffff
  114 
  115 /* Min and max packet length */
  116 #define PPTP_MAX_PAYLOAD        (0xffff - sizeof(struct greheader) - 8)
  117 
  118 /* All times are scaled by this (PPTP_TIME_SCALE time units = 1 sec.) */
  119 #define PPTP_TIME_SCALE         1024                    /* milliseconds */
  120 typedef u_int64_t               pptptime_t;
  121 
  122 /* Acknowledgment timeout parameters and functions */
  123 #define PPTP_XMIT_WIN           16                      /* max xmit window */
  124 #define PPTP_MIN_TIMEOUT        (PPTP_TIME_SCALE / 83)  /* 12 milliseconds */
  125 #define PPTP_MAX_TIMEOUT        (3 * PPTP_TIME_SCALE)   /* 3 seconds */
  126 
  127 /* When we recieve a packet, we wait to see if there's an outgoing packet
  128    we can piggy-back the ACK off of. These parameters determine the mimimum
  129    and maxmimum length of time we're willing to wait in order to do that.
  130    These have no effect unless "enableDelayedAck" is turned on. */
  131 #define PPTP_MIN_ACK_DELAY      (PPTP_TIME_SCALE / 500) /* 2 milliseconds */
  132 #define PPTP_MAX_ACK_DELAY      (PPTP_TIME_SCALE / 2)   /* 500 milliseconds */
  133 
  134 /* See RFC 2637 section 4.4 */
  135 #define PPTP_ACK_ALPHA(x)       (((x) + 4) >> 3)        /* alpha = 0.125 */
  136 #define PPTP_ACK_BETA(x)        (((x) + 2) >> 2)        /* beta = 0.25 */
  137 #define PPTP_ACK_CHI(x)         ((x) << 2)      /* chi = 4 */
  138 #define PPTP_ACK_DELTA(x)       ((x) << 1)      /* delta = 2 */
  139 
  140 #define PPTP_SEQ_DIFF(x,y)      ((int32_t)(x) - (int32_t)(y))
  141 
  142 #define SESSHASHSIZE            0x0020
  143 #define SESSHASH(x)             (((x) ^ ((x) >> 8)) & (SESSHASHSIZE - 1))
  144 
  145 /* We keep packet retransmit and acknowlegement state in this struct */
  146 struct ng_pptpgre_sess {
  147         node_p                  node;           /* this node pointer */
  148         hook_p                  hook;           /* hook to upper layers */
  149         struct ng_pptpgre_conf  conf;           /* configuration info */
  150         struct mtx              mtx;            /* session mutex */
  151         u_int32_t               recvSeq;        /* last seq # we rcv'd */
  152         u_int32_t               xmitSeq;        /* last seq # we sent */
  153         u_int32_t               recvAck;        /* last seq # peer ack'd */
  154         u_int32_t               xmitAck;        /* last seq # we ack'd */
  155         int32_t                 ato;            /* adaptive time-out value */
  156         int32_t                 rtt;            /* round trip time estimate */
  157         int32_t                 dev;            /* deviation estimate */
  158         u_int16_t               xmitWin;        /* size of xmit window */
  159         struct callout          sackTimer;      /* send ack timer */
  160         struct callout          rackTimer;      /* recv ack timer */
  161         u_int32_t               winAck;         /* seq when xmitWin will grow */
  162         pptptime_t              timeSent[PPTP_XMIT_WIN];
  163         LIST_ENTRY(ng_pptpgre_sess) sessions;
  164 };
  165 typedef struct ng_pptpgre_sess *hpriv_p;
  166 
  167 /* Node private data */
  168 struct ng_pptpgre_private {
  169         hook_p                  upper;          /* hook to upper layers */
  170         hook_p                  lower;          /* hook to lower layers */
  171         struct ng_pptpgre_sess  uppersess;      /* default session for compat */
  172         LIST_HEAD(, ng_pptpgre_sess) sesshash[SESSHASHSIZE];
  173         struct ng_pptpgre_stats stats;          /* node statistics */
  174 };
  175 typedef struct ng_pptpgre_private *priv_p;
  176 
  177 /* Netgraph node methods */
  178 static ng_constructor_t ng_pptpgre_constructor;
  179 static ng_rcvmsg_t      ng_pptpgre_rcvmsg;
  180 static ng_shutdown_t    ng_pptpgre_shutdown;
  181 static ng_newhook_t     ng_pptpgre_newhook;
  182 static ng_rcvdata_t     ng_pptpgre_rcvdata;
  183 static ng_rcvdata_t     ng_pptpgre_rcvdata_lower;
  184 static ng_disconnect_t  ng_pptpgre_disconnect;
  185 
  186 /* Helper functions */
  187 static int      ng_pptpgre_xmit(hpriv_p hpriv, item_p item);
  188 static void     ng_pptpgre_start_send_ack_timer(hpriv_p hpriv);
  189 static void     ng_pptpgre_start_recv_ack_timer(hpriv_p hpriv);
  190 static void     ng_pptpgre_recv_ack_timeout(node_p node, hook_p hook,
  191                     void *arg1, int arg2);
  192 static void     ng_pptpgre_send_ack_timeout(node_p node, hook_p hook,
  193                     void *arg1, int arg2);
  194 static hpriv_p  ng_pptpgre_find_session(priv_p privp, u_int16_t cid);
  195 static void     ng_pptpgre_reset(hpriv_p hpriv);
  196 static pptptime_t ng_pptpgre_time(void);
  197 
  198 /* Parse type for struct ng_pptpgre_conf */
  199 static const struct ng_parse_struct_field ng_pptpgre_conf_type_fields[]
  200         = NG_PPTPGRE_CONF_TYPE_INFO;
  201 static const struct ng_parse_type ng_pptpgre_conf_type = {
  202         &ng_parse_struct_type,
  203         &ng_pptpgre_conf_type_fields,
  204 };
  205 
  206 /* Parse type for struct ng_pptpgre_stats */
  207 static const struct ng_parse_struct_field ng_pptpgre_stats_type_fields[]
  208         = NG_PPTPGRE_STATS_TYPE_INFO;
  209 static const struct ng_parse_type ng_pptp_stats_type = {
  210         &ng_parse_struct_type,
  211         &ng_pptpgre_stats_type_fields
  212 };
  213 
  214 /* List of commands and how to convert arguments to/from ASCII */
  215 static const struct ng_cmdlist ng_pptpgre_cmdlist[] = {
  216         {
  217           NGM_PPTPGRE_COOKIE,
  218           NGM_PPTPGRE_SET_CONFIG,
  219           "setconfig",
  220           &ng_pptpgre_conf_type,
  221           NULL
  222         },
  223         {
  224           NGM_PPTPGRE_COOKIE,
  225           NGM_PPTPGRE_GET_CONFIG,
  226           "getconfig",
  227           &ng_parse_hint16_type,
  228           &ng_pptpgre_conf_type
  229         },
  230         {
  231           NGM_PPTPGRE_COOKIE,
  232           NGM_PPTPGRE_GET_STATS,
  233           "getstats",
  234           NULL,
  235           &ng_pptp_stats_type
  236         },
  237         {
  238           NGM_PPTPGRE_COOKIE,
  239           NGM_PPTPGRE_CLR_STATS,
  240           "clrstats",
  241           NULL,
  242           NULL
  243         },
  244         {
  245           NGM_PPTPGRE_COOKIE,
  246           NGM_PPTPGRE_GETCLR_STATS,
  247           "getclrstats",
  248           NULL,
  249           &ng_pptp_stats_type
  250         },
  251         { 0 }
  252 };
  253 
  254 /* Node type descriptor */
  255 static struct ng_type ng_pptpgre_typestruct = {
  256         .version =      NG_ABI_VERSION,
  257         .name =         NG_PPTPGRE_NODE_TYPE,
  258         .constructor =  ng_pptpgre_constructor,
  259         .rcvmsg =       ng_pptpgre_rcvmsg,
  260         .shutdown =     ng_pptpgre_shutdown,
  261         .newhook =      ng_pptpgre_newhook,
  262         .rcvdata =      ng_pptpgre_rcvdata,
  263         .disconnect =   ng_pptpgre_disconnect,
  264         .cmdlist =      ng_pptpgre_cmdlist,
  265 };
  266 NETGRAPH_INIT(pptpgre, &ng_pptpgre_typestruct);
  267 
  268 #define ERROUT(x)       do { error = (x); goto done; } while (0)
  269 
  270 /************************************************************************
  271                         NETGRAPH NODE STUFF
  272  ************************************************************************/
  273 
  274 /*
  275  * Node type constructor
  276  */
  277 static int
  278 ng_pptpgre_constructor(node_p node)
  279 {
  280         priv_p priv;
  281         int i;
  282 
  283         /* Allocate private structure */
  284         priv = malloc(sizeof(*priv), M_NETGRAPH, M_NOWAIT | M_ZERO);
  285         if (priv == NULL)
  286                 return (ENOMEM);
  287 
  288         NG_NODE_SET_PRIVATE(node, priv);
  289 
  290         /* Initialize state */
  291         mtx_init(&priv->uppersess.mtx, "ng_pptp", NULL, MTX_DEF);
  292         ng_callout_init(&priv->uppersess.sackTimer);
  293         ng_callout_init(&priv->uppersess.rackTimer);
  294         priv->uppersess.node = node;
  295 
  296         for (i = 0; i < SESSHASHSIZE; i++)
  297             LIST_INIT(&priv->sesshash[i]);
  298 
  299         LIST_INSERT_HEAD(&priv->sesshash[0], &priv->uppersess, sessions);
  300 
  301         /* Done */
  302         return (0);
  303 }
  304 
  305 /*
  306  * Give our OK for a hook to be added.
  307  */
  308 static int
  309 ng_pptpgre_newhook(node_p node, hook_p hook, const char *name)
  310 {
  311         const priv_p priv = NG_NODE_PRIVATE(node);
  312 
  313         /* Check hook name */
  314         if (strcmp(name, NG_PPTPGRE_HOOK_UPPER) == 0) {
  315                 priv->upper = hook;
  316                 priv->uppersess.hook = hook;
  317                 NG_HOOK_SET_PRIVATE(hook, &priv->uppersess);
  318         } else if (strcmp(name, NG_PPTPGRE_HOOK_LOWER) == 0) {
  319                 priv->lower = hook;
  320                 NG_HOOK_SET_RCVDATA(hook, ng_pptpgre_rcvdata_lower);
  321         } else {
  322                 static const char hexdig[16] = "0123456789abcdef";
  323                 const char *hex;
  324                 hpriv_p hpriv;
  325                 int i, j;
  326                 uint16_t cid, hash;
  327 
  328                 /* Parse hook name to get session ID */
  329                 if (strncmp(name, NG_PPTPGRE_HOOK_SESSION_P,
  330                     sizeof(NG_PPTPGRE_HOOK_SESSION_P) - 1) != 0)
  331                         return (EINVAL);
  332                 hex = name + sizeof(NG_PPTPGRE_HOOK_SESSION_P) - 1;
  333                 for (cid = i = 0; i < 4; i++) {
  334                         for (j = 0; j < 16 && hex[i] != hexdig[j]; j++);
  335                         if (j == 16)
  336                                 return (EINVAL);
  337                         cid = (cid << 4) | j;
  338                 }
  339                 if (hex[i] != '\0')
  340                         return (EINVAL);
  341 
  342                 hpriv = malloc(sizeof(*hpriv), M_NETGRAPH, M_NOWAIT | M_ZERO);
  343                 if (hpriv == NULL)
  344                         return (ENOMEM);
  345         
  346                 /* Initialize state */
  347                 mtx_init(&hpriv->mtx, "ng_pptp", NULL, MTX_DEF);
  348                 ng_callout_init(&hpriv->sackTimer);
  349                 ng_callout_init(&hpriv->rackTimer);
  350                 hpriv->conf.cid = cid;
  351                 hpriv->node = node;
  352                 hpriv->hook = hook;
  353                 NG_HOOK_SET_PRIVATE(hook, hpriv);
  354 
  355                 hash = SESSHASH(cid);
  356                 LIST_INSERT_HEAD(&priv->sesshash[hash], hpriv, sessions);
  357         }
  358 
  359         return (0);
  360 }
  361 
  362 /*
  363  * Receive a control message.
  364  */
  365 static int
  366 ng_pptpgre_rcvmsg(node_p node, item_p item, hook_p lasthook)
  367 {
  368         const priv_p priv = NG_NODE_PRIVATE(node);
  369         struct ng_mesg *resp = NULL;
  370         int error = 0;
  371         struct ng_mesg *msg;
  372 
  373         NGI_GET_MSG(item, msg);
  374         switch (msg->header.typecookie) {
  375         case NGM_PPTPGRE_COOKIE:
  376                 switch (msg->header.cmd) {
  377                 case NGM_PPTPGRE_SET_CONFIG:
  378                     {
  379                         struct ng_pptpgre_conf *const newConf =
  380                                 (struct ng_pptpgre_conf *) msg->data;
  381                         hpriv_p hpriv;
  382                         uint16_t hash;
  383 
  384                         /* Check for invalid or illegal config */
  385                         if (msg->header.arglen != sizeof(*newConf))
  386                                 ERROUT(EINVAL);
  387                         /* Try to find session by cid. */
  388                         hpriv = ng_pptpgre_find_session(priv, newConf->cid);
  389                         /* If not present - use upper. */
  390                         if (hpriv == NULL) {
  391                                 hpriv = &priv->uppersess;
  392                                 LIST_REMOVE(hpriv, sessions);
  393                                 hash = SESSHASH(newConf->cid);
  394                                 LIST_INSERT_HEAD(&priv->sesshash[hash], hpriv,
  395                                     sessions);
  396                         }
  397                         ng_pptpgre_reset(hpriv);        /* reset on configure */
  398                         hpriv->conf = *newConf;
  399                         break;
  400                     }
  401                 case NGM_PPTPGRE_GET_CONFIG:
  402                     {
  403                         hpriv_p hpriv;
  404 
  405                         if (msg->header.arglen == 2) {
  406                                 /* Try to find session by cid. */
  407                                 hpriv = ng_pptpgre_find_session(priv,
  408                                     *((uint16_t *)msg->data));
  409                                 if (hpriv == NULL)
  410                                         ERROUT(EINVAL);
  411                         } else if (msg->header.arglen == 0) {
  412                                 /* Use upper. */
  413                                 hpriv = &priv->uppersess;
  414                         } else
  415                                 ERROUT(EINVAL);
  416                         NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_NOWAIT);
  417                         if (resp == NULL)
  418                                 ERROUT(ENOMEM);
  419                         bcopy(&hpriv->conf, resp->data, sizeof(hpriv->conf));
  420                         break;
  421                     }
  422                 case NGM_PPTPGRE_GET_STATS:
  423                 case NGM_PPTPGRE_CLR_STATS:
  424                 case NGM_PPTPGRE_GETCLR_STATS:
  425                     {
  426                         if (msg->header.cmd != NGM_PPTPGRE_CLR_STATS) {
  427                                 NG_MKRESPONSE(resp, msg,
  428                                     sizeof(priv->stats), M_NOWAIT);
  429                                 if (resp == NULL)
  430                                         ERROUT(ENOMEM);
  431                                 bcopy(&priv->stats,
  432                                     resp->data, sizeof(priv->stats));
  433                         }
  434                         if (msg->header.cmd != NGM_PPTPGRE_GET_STATS)
  435                                 bzero(&priv->stats, sizeof(priv->stats));
  436                         break;
  437                     }
  438                 default:
  439                         error = EINVAL;
  440                         break;
  441                 }
  442                 break;
  443         default:
  444                 error = EINVAL;
  445                 break;
  446         }
  447 done:
  448         NG_RESPOND_MSG(error, node, item, resp);
  449         NG_FREE_MSG(msg);
  450         return (error);
  451 }
  452 
  453 /*
  454  * Receive incoming data on a hook.
  455  */
  456 static int
  457 ng_pptpgre_rcvdata(hook_p hook, item_p item)
  458 {
  459         const hpriv_p hpriv = NG_HOOK_PRIVATE(hook);
  460         int rval;
  461 
  462         /* If not configured, reject */
  463         if (!hpriv->conf.enabled) {
  464                 NG_FREE_ITEM(item);
  465                 return (ENXIO);
  466         }
  467 
  468         mtx_lock(&hpriv->mtx);
  469 
  470         rval = ng_pptpgre_xmit(hpriv, item);
  471 
  472         mtx_assert(&hpriv->mtx, MA_NOTOWNED);
  473 
  474         return (rval);
  475 }
  476 
  477 /*
  478  * Hook disconnection
  479  */
  480 static int
  481 ng_pptpgre_disconnect(hook_p hook)
  482 {
  483         const node_p node = NG_HOOK_NODE(hook);
  484         const priv_p priv = NG_NODE_PRIVATE(node);
  485         const hpriv_p hpriv = NG_HOOK_PRIVATE(hook);
  486 
  487         /* Zero out hook pointer */
  488         if (hook == priv->upper) {
  489                 priv->upper = NULL;
  490                 priv->uppersess.hook = NULL;
  491         } else if (hook == priv->lower) {
  492                 priv->lower = NULL;
  493         } else {
  494                 /* Reset node (stops timers) */
  495                 ng_pptpgre_reset(hpriv);
  496 
  497                 LIST_REMOVE(hpriv, sessions);
  498                 mtx_destroy(&hpriv->mtx);
  499                 free(hpriv, M_NETGRAPH);
  500         }
  501 
  502         /* Go away if no longer connected to anything */
  503         if ((NG_NODE_NUMHOOKS(node) == 0)
  504         && (NG_NODE_IS_VALID(node)))
  505                 ng_rmnode_self(node);
  506         return (0);
  507 }
  508 
  509 /*
  510  * Destroy node
  511  */
  512 static int
  513 ng_pptpgre_shutdown(node_p node)
  514 {
  515         const priv_p priv = NG_NODE_PRIVATE(node);
  516 
  517         /* Reset node (stops timers) */
  518         ng_pptpgre_reset(&priv->uppersess);
  519 
  520         LIST_REMOVE(&priv->uppersess, sessions);
  521         mtx_destroy(&priv->uppersess.mtx);
  522 
  523         free(priv, M_NETGRAPH);
  524 
  525         /* Decrement ref count */
  526         NG_NODE_UNREF(node);
  527         return (0);
  528 }
  529 
  530 /*************************************************************************
  531                     TRANSMIT AND RECEIVE FUNCTIONS
  532 *************************************************************************/
  533 
  534 /*
  535  * Transmit an outgoing frame, or just an ack if m is NULL.
  536  */
  537 static int
  538 ng_pptpgre_xmit(hpriv_p hpriv, item_p item)
  539 {
  540         const priv_p priv = NG_NODE_PRIVATE(hpriv->node);
  541         u_char buf[sizeof(struct greheader) + 2 * sizeof(u_int32_t)];
  542         struct greheader *const gre = (struct greheader *)buf;
  543         int grelen, error;
  544         struct mbuf *m;
  545 
  546         mtx_assert(&hpriv->mtx, MA_OWNED);
  547 
  548         if (item) {
  549                 NGI_GET_M(item, m);
  550         } else {
  551                 m = NULL;
  552         }
  553         /* Check if there's data */
  554         if (m != NULL) {
  555 
  556                 /* Check if windowing is enabled */
  557                 if (hpriv->conf.enableWindowing) {
  558                         /* Is our transmit window full? */
  559                         if ((u_int32_t)PPTP_SEQ_DIFF(hpriv->xmitSeq,
  560                             hpriv->recvAck) >= hpriv->xmitWin) {
  561                                 priv->stats.xmitDrops++;
  562                                 ERROUT(ENOBUFS);
  563                         }
  564                 }
  565 
  566                 /* Sanity check frame length */
  567                 if (m != NULL && m->m_pkthdr.len > PPTP_MAX_PAYLOAD) {
  568                         priv->stats.xmitTooBig++;
  569                         ERROUT(EMSGSIZE);
  570                 }
  571         } else {
  572                 priv->stats.xmitLoneAcks++;
  573         }
  574 
  575         /* Build GRE header */
  576         be32enc(gre, PPTP_INIT_VALUE);
  577         be16enc(&gre->length, (m != NULL) ? m->m_pkthdr.len : 0);
  578         be16enc(&gre->cid, hpriv->conf.peerCid);
  579 
  580         /* Include sequence number if packet contains any data */
  581         if (m != NULL) {
  582                 gre->hasSeq = 1;
  583                 if (hpriv->conf.enableWindowing) {
  584                         hpriv->timeSent[hpriv->xmitSeq - hpriv->recvAck]
  585                             = ng_pptpgre_time();
  586                 }
  587                 hpriv->xmitSeq++;
  588                 be32enc(&gre->data[0], hpriv->xmitSeq);
  589         }
  590 
  591         /* Include acknowledgement (and stop send ack timer) if needed */
  592         if (hpriv->conf.enableAlwaysAck || hpriv->xmitAck != hpriv->recvSeq) {
  593                 gre->hasAck = 1;
  594                 be32enc(&gre->data[gre->hasSeq], hpriv->recvSeq);
  595                 hpriv->xmitAck = hpriv->recvSeq;
  596                 if (hpriv->conf.enableDelayedAck)
  597                         ng_uncallout(&hpriv->sackTimer, hpriv->node);
  598         }
  599 
  600         /* Prepend GRE header to outgoing frame */
  601         grelen = sizeof(*gre) + sizeof(u_int32_t) * (gre->hasSeq + gre->hasAck);
  602         if (m == NULL) {
  603                 MGETHDR(m, M_DONTWAIT, MT_DATA);
  604                 if (m == NULL) {
  605                         priv->stats.memoryFailures++;
  606                         ERROUT(ENOBUFS);
  607                 }
  608                 m->m_len = m->m_pkthdr.len = grelen;
  609                 m->m_pkthdr.rcvif = NULL;
  610         } else {
  611                 M_PREPEND(m, grelen, M_DONTWAIT);
  612                 if (m == NULL || (m->m_len < grelen
  613                     && (m = m_pullup(m, grelen)) == NULL)) {
  614                         priv->stats.memoryFailures++;
  615                         ERROUT(ENOBUFS);
  616                 }
  617         }
  618         bcopy(gre, mtod(m, u_char *), grelen);
  619 
  620         /* Update stats */
  621         priv->stats.xmitPackets++;
  622         priv->stats.xmitOctets += m->m_pkthdr.len;
  623 
  624         /*
  625          * XXX: we should reset timer only after an item has been sent
  626          * successfully.
  627          */
  628         if (hpriv->conf.enableWindowing &&
  629             gre->hasSeq && hpriv->xmitSeq == hpriv->recvAck + 1)
  630                 ng_pptpgre_start_recv_ack_timer(hpriv);
  631 
  632         mtx_unlock(&hpriv->mtx);
  633 
  634         /* Deliver packet */
  635         if (item) {
  636                 NG_FWD_NEW_DATA(error, item, priv->lower, m);
  637         } else {
  638                 NG_SEND_DATA_ONLY(error, priv->lower, m);
  639         }
  640 
  641         return (error);
  642 
  643 done:
  644         mtx_unlock(&hpriv->mtx);
  645         NG_FREE_M(m);
  646         if (item)
  647                 NG_FREE_ITEM(item);
  648         return (error);
  649 }
  650 
  651 /*
  652  * Handle an incoming packet.  The packet includes the IP header.
  653  */
  654 static int
  655 ng_pptpgre_rcvdata_lower(hook_p hook, item_p item)
  656 {
  657         hpriv_p hpriv;
  658         node_p node = NG_HOOK_NODE(hook);
  659         const priv_p priv = NG_NODE_PRIVATE(node);
  660         int iphlen, grelen, extralen;
  661         const struct greheader *gre;
  662         const struct ip *ip;
  663         int error = 0;
  664         struct mbuf *m;
  665 
  666         NGI_GET_M(item, m);
  667         /* Update stats */
  668         priv->stats.recvPackets++;
  669         priv->stats.recvOctets += m->m_pkthdr.len;
  670 
  671         /* Sanity check packet length */
  672         if (m->m_pkthdr.len < sizeof(*ip) + sizeof(*gre)) {
  673                 priv->stats.recvRunts++;
  674                 ERROUT(EINVAL);
  675         }
  676 
  677         /* Safely pull up the complete IP+GRE headers */
  678         if (m->m_len < sizeof(*ip) + sizeof(*gre)
  679             && (m = m_pullup(m, sizeof(*ip) + sizeof(*gre))) == NULL) {
  680                 priv->stats.memoryFailures++;
  681                 ERROUT(ENOBUFS);
  682         }
  683         ip = mtod(m, const struct ip *);
  684         iphlen = ip->ip_hl << 2;
  685         if (m->m_len < iphlen + sizeof(*gre)) {
  686                 if ((m = m_pullup(m, iphlen + sizeof(*gre))) == NULL) {
  687                         priv->stats.memoryFailures++;
  688                         ERROUT(ENOBUFS);
  689                 }
  690                 ip = mtod(m, const struct ip *);
  691         }
  692         gre = (const struct greheader *)((const u_char *)ip + iphlen);
  693         grelen = sizeof(*gre) + sizeof(u_int32_t) * (gre->hasSeq + gre->hasAck);
  694         if (m->m_pkthdr.len < iphlen + grelen) {
  695                 priv->stats.recvRunts++;
  696                 ERROUT(EINVAL);
  697         }
  698         if (m->m_len < iphlen + grelen) {
  699                 if ((m = m_pullup(m, iphlen + grelen)) == NULL) {
  700                         priv->stats.memoryFailures++;
  701                         ERROUT(ENOBUFS);
  702                 }
  703                 ip = mtod(m, const struct ip *);
  704                 gre = (const struct greheader *)((const u_char *)ip + iphlen);
  705         }
  706 
  707         /* Sanity check packet length and GRE header bits */
  708         extralen = m->m_pkthdr.len
  709             - (iphlen + grelen + gre->hasSeq * be16dec(&gre->length));
  710         if (extralen < 0) {
  711                 priv->stats.recvBadGRE++;
  712                 ERROUT(EINVAL);
  713         }
  714         if ((be32dec(gre) & PPTP_INIT_MASK) != PPTP_INIT_VALUE) {
  715                 priv->stats.recvBadGRE++;
  716                 ERROUT(EINVAL);
  717         }
  718 
  719         hpriv = ng_pptpgre_find_session(priv, be16dec(&gre->cid));
  720         if (hpriv == NULL || hpriv->hook == NULL || !hpriv->conf.enabled) {
  721                 priv->stats.recvBadCID++;
  722                 ERROUT(EINVAL);
  723         }
  724         mtx_lock(&hpriv->mtx);
  725 
  726         /* Look for peer ack */
  727         if (gre->hasAck) {
  728                 const u_int32_t ack = be32dec(&gre->data[gre->hasSeq]);
  729                 const int index = ack - hpriv->recvAck - 1;
  730                 long sample;
  731                 long diff;
  732 
  733                 /* Sanity check ack value */
  734                 if (PPTP_SEQ_DIFF(ack, hpriv->xmitSeq) > 0) {
  735                         priv->stats.recvBadAcks++;
  736                         goto badAck;            /* we never sent it! */
  737                 }
  738                 if (PPTP_SEQ_DIFF(ack, hpriv->recvAck) <= 0)
  739                         goto badAck;            /* ack already timed out */
  740                 hpriv->recvAck = ack;
  741 
  742                 /* Update adaptive timeout stuff */
  743                 if (hpriv->conf.enableWindowing) {
  744                         sample = ng_pptpgre_time() - hpriv->timeSent[index];
  745                         diff = sample - hpriv->rtt;
  746                         hpriv->rtt += PPTP_ACK_ALPHA(diff);
  747                         if (diff < 0)
  748                                 diff = -diff;
  749                         hpriv->dev += PPTP_ACK_BETA(diff - hpriv->dev);
  750                             /* +2 to compensate low precision of int math */
  751                         hpriv->ato = hpriv->rtt + PPTP_ACK_CHI(hpriv->dev + 2);
  752                         if (hpriv->ato > PPTP_MAX_TIMEOUT)
  753                                 hpriv->ato = PPTP_MAX_TIMEOUT;
  754                         else if (hpriv->ato < PPTP_MIN_TIMEOUT)
  755                                 hpriv->ato = PPTP_MIN_TIMEOUT;
  756 
  757                         /* Shift packet transmit times in our transmit window */
  758                         bcopy(hpriv->timeSent + index + 1, hpriv->timeSent,
  759                             sizeof(*hpriv->timeSent)
  760                               * (PPTP_XMIT_WIN - (index + 1)));
  761 
  762                         /* If we sent an entire window, increase window size */
  763                         if (PPTP_SEQ_DIFF(ack, hpriv->winAck) >= 0
  764                             && hpriv->xmitWin < PPTP_XMIT_WIN) {
  765                                 hpriv->xmitWin++;
  766                                 hpriv->winAck = ack + hpriv->xmitWin;
  767                         }
  768 
  769                         /* Stop/(re)start receive ACK timer as necessary */
  770                         ng_uncallout(&hpriv->rackTimer, hpriv->node);
  771                         if (hpriv->recvAck != hpriv->xmitSeq)
  772                                 ng_pptpgre_start_recv_ack_timer(hpriv);
  773                 }
  774         }
  775 badAck:
  776 
  777         /* See if frame contains any data */
  778         if (gre->hasSeq) {
  779                 const u_int32_t seq = be32dec(&gre->data[0]);
  780 
  781                 /* Sanity check sequence number */
  782                 if (PPTP_SEQ_DIFF(seq, hpriv->recvSeq) <= 0) {
  783                         if (seq == hpriv->recvSeq)
  784                                 priv->stats.recvDuplicates++;
  785                         else
  786                                 priv->stats.recvOutOfOrder++;
  787                         mtx_unlock(&hpriv->mtx);
  788                         ERROUT(EINVAL);
  789                 }
  790                 hpriv->recvSeq = seq;
  791 
  792                 /* We need to acknowledge this packet; do it soon... */
  793                 if (!(callout_pending(&hpriv->sackTimer))) {
  794                         /* If delayed ACK is disabled, send it now */
  795                         if (!hpriv->conf.enableDelayedAck) {    /* ack now */
  796                                 ng_pptpgre_xmit(hpriv, NULL);
  797                                 /* ng_pptpgre_xmit() drops the mutex */
  798                         } else {                                /* ack later */
  799                                 ng_pptpgre_start_send_ack_timer(hpriv);
  800                                 mtx_unlock(&hpriv->mtx);
  801                         }
  802                 } else
  803                         mtx_unlock(&hpriv->mtx);
  804 
  805                 /* Trim mbuf down to internal payload */
  806                 m_adj(m, iphlen + grelen);
  807                 if (extralen > 0)
  808                         m_adj(m, -extralen);
  809 
  810                 mtx_assert(&hpriv->mtx, MA_NOTOWNED);
  811 
  812                 /* Deliver frame to upper layers */
  813                 NG_FWD_NEW_DATA(error, item, hpriv->hook, m);
  814         } else {
  815                 priv->stats.recvLoneAcks++;
  816                 mtx_unlock(&hpriv->mtx);
  817                 NG_FREE_ITEM(item);
  818                 NG_FREE_M(m);           /* no data to deliver */
  819         }
  820 
  821         return (error);
  822 
  823 done:
  824         NG_FREE_ITEM(item);
  825         NG_FREE_M(m);
  826         return (error);
  827 }
  828 
  829 /*************************************************************************
  830                     TIMER RELATED FUNCTIONS
  831 *************************************************************************/
  832 
  833 /*
  834  * Start a timer for the peer's acknowledging our oldest unacknowledged
  835  * sequence number.  If we get an ack for this sequence number before
  836  * the timer goes off, we cancel the timer.  Resets currently running
  837  * recv ack timer, if any.
  838  */
  839 static void
  840 ng_pptpgre_start_recv_ack_timer(hpriv_p hpriv)
  841 {
  842         int remain, ticks;
  843 
  844         /* Compute how long until oldest unack'd packet times out,
  845            and reset the timer to that time. */
  846         remain = (hpriv->timeSent[0] + hpriv->ato) - ng_pptpgre_time();
  847         if (remain < 0)
  848                 remain = 0;
  849 
  850         /* Be conservative: timeout can happen up to 1 tick early */
  851         ticks = (((remain * hz) + PPTP_TIME_SCALE - 1) / PPTP_TIME_SCALE) + 1;
  852         ng_callout(&hpriv->rackTimer, hpriv->node, hpriv->hook,
  853             ticks, ng_pptpgre_recv_ack_timeout, hpriv, 0);
  854 }
  855 
  856 /*
  857  * The peer has failed to acknowledge the oldest unacknowledged sequence
  858  * number within the time allotted.  Update our adaptive timeout parameters
  859  * and reset/restart the recv ack timer.
  860  */
  861 static void
  862 ng_pptpgre_recv_ack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
  863 {
  864         const priv_p priv = NG_NODE_PRIVATE(node);
  865         const hpriv_p hpriv = arg1;
  866 
  867         /* Update adaptive timeout stuff */
  868         priv->stats.recvAckTimeouts++;
  869         hpriv->rtt = PPTP_ACK_DELTA(hpriv->rtt) + 1; /* +1 to avoid delta*0 case */
  870         hpriv->ato = hpriv->rtt + PPTP_ACK_CHI(hpriv->dev);
  871         if (hpriv->ato > PPTP_MAX_TIMEOUT)
  872                 hpriv->ato = PPTP_MAX_TIMEOUT;
  873         else if (hpriv->ato < PPTP_MIN_TIMEOUT)
  874                 hpriv->ato = PPTP_MIN_TIMEOUT;
  875 
  876         /* Reset ack and sliding window */
  877         hpriv->recvAck = hpriv->xmitSeq;                /* pretend we got the ack */
  878         hpriv->xmitWin = (hpriv->xmitWin + 1) / 2;      /* shrink transmit window */
  879         hpriv->winAck = hpriv->recvAck + hpriv->xmitWin;        /* reset win expand time */
  880 }
  881 
  882 /*
  883  * Start the send ack timer. This assumes the timer is not
  884  * already running.
  885  */
  886 static void
  887 ng_pptpgre_start_send_ack_timer(hpriv_p hpriv)
  888 {
  889         int ackTimeout, ticks;
  890 
  891         /* Take 1/4 of the estimated round trip time */
  892         ackTimeout = (hpriv->rtt >> 2);
  893         if (ackTimeout < PPTP_MIN_ACK_DELAY)
  894                 ackTimeout = PPTP_MIN_ACK_DELAY;
  895         else if (ackTimeout > PPTP_MAX_ACK_DELAY)
  896                 ackTimeout = PPTP_MAX_ACK_DELAY;
  897 
  898         /* Be conservative: timeout can happen up to 1 tick early */
  899         ticks = (((ackTimeout * hz) + PPTP_TIME_SCALE - 1) / PPTP_TIME_SCALE);
  900         ng_callout(&hpriv->sackTimer, hpriv->node, hpriv->hook,
  901             ticks, ng_pptpgre_send_ack_timeout, hpriv, 0);
  902 }
  903 
  904 /*
  905  * We've waited as long as we're willing to wait before sending an
  906  * acknowledgement to the peer for received frames. We had hoped to
  907  * be able to piggy back our acknowledgement on an outgoing data frame,
  908  * but apparently there haven't been any since. So send the ack now.
  909  */
  910 static void
  911 ng_pptpgre_send_ack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
  912 {
  913         const hpriv_p hpriv = arg1;
  914 
  915         mtx_lock(&hpriv->mtx);
  916         /* Send a frame with an ack but no payload */
  917         ng_pptpgre_xmit(hpriv, NULL);
  918         mtx_assert(&hpriv->mtx, MA_NOTOWNED);
  919 }
  920 
  921 /*************************************************************************
  922                     MISC FUNCTIONS
  923 *************************************************************************/
  924 
  925 /*
  926  * Find the hook with a given session ID.
  927  */
  928 static hpriv_p
  929 ng_pptpgre_find_session(priv_p privp, u_int16_t cid)
  930 {
  931         uint16_t        hash = SESSHASH(cid);
  932         hpriv_p hpriv = NULL;
  933 
  934         LIST_FOREACH(hpriv, &privp->sesshash[hash], sessions) {
  935                 if (hpriv->conf.cid == cid)
  936                         break;
  937         }
  938 
  939         return (hpriv);
  940 }
  941 
  942 /*
  943  * Reset state (must be called with lock held or from writer)
  944  */
  945 static void
  946 ng_pptpgre_reset(hpriv_p hpriv)
  947 {
  948         /* Reset adaptive timeout state */
  949         hpriv->ato = PPTP_MAX_TIMEOUT;
  950         hpriv->rtt = PPTP_TIME_SCALE / 10;
  951         if (hpriv->conf.peerPpd > 1)    /* ppd = 0 treat as = 1 */
  952                 hpriv->rtt *= hpriv->conf.peerPpd;
  953         hpriv->dev = 0;
  954         hpriv->xmitWin = (hpriv->conf.recvWin + 1) / 2;
  955         if (hpriv->xmitWin < 2)         /* often the first packet is lost */
  956                 hpriv->xmitWin = 2;             /*   because the peer isn't ready */
  957         else if (hpriv->xmitWin > PPTP_XMIT_WIN)
  958                 hpriv->xmitWin = PPTP_XMIT_WIN;
  959         hpriv->winAck = hpriv->xmitWin;
  960 
  961         /* Reset sequence numbers */
  962         hpriv->recvSeq = ~0;
  963         hpriv->recvAck = ~0;
  964         hpriv->xmitSeq = ~0;
  965         hpriv->xmitAck = ~0;
  966 
  967         /* Stop timers */
  968         ng_uncallout(&hpriv->sackTimer, hpriv->node);
  969         ng_uncallout(&hpriv->rackTimer, hpriv->node);
  970 }
  971 
  972 /*
  973  * Return the current time scaled & translated to our internally used format.
  974  */
  975 static pptptime_t
  976 ng_pptpgre_time(void)
  977 {
  978         struct timeval tv;
  979         pptptime_t t;
  980 
  981         microuptime(&tv);
  982         t = (pptptime_t)tv.tv_sec * PPTP_TIME_SCALE;
  983         t += tv.tv_usec / (1000000 / PPTP_TIME_SCALE);
  984         return(t);
  985 }

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