sys/netgraph7/ng_l2tp.c

   1 /*-
   2  * Copyright (c) 2001-2002 Packet Design, LLC.
   3  * All rights reserved.
   4  *
   5  * Subject to the following obligations and disclaimer of warranty,
   6  * use and redistribution of this software, in source or object code
   7  * forms, with or without modifications are expressly permitted by
   8  * Packet Design; provided, however, that:
   9  *
  10  *    (i)  Any and all reproductions of the source or object code
  11  *         must include the copyright notice above and the following
  12  *         disclaimer of warranties; and
  13  *    (ii) No rights are granted, in any manner or form, to use
  14  *         Packet Design trademarks, including the mark "PACKET DESIGN"
  15  *         on advertising, endorsements, or otherwise except as such
  16  *         appears in the above copyright notice or in the software.
  17  *
  18  * THIS SOFTWARE IS BEING PROVIDED BY PACKET DESIGN "AS IS", AND
  19  * TO THE MAXIMUM EXTENT PERMITTED BY LAW, PACKET DESIGN MAKES NO
  20  * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING
  21  * THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED
  22  * WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE,
  23  * OR NON-INFRINGEMENT.  PACKET DESIGN DOES NOT WARRANT, GUARANTEE,
  24  * OR MAKE ANY REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS
  25  * OF THE USE OF THIS SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY,
  26  * RELIABILITY OR OTHERWISE.  IN NO EVENT SHALL PACKET DESIGN BE
  27  * LIABLE FOR ANY DAMAGES RESULTING FROM OR ARISING OUT OF ANY USE
  28  * OF THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY DIRECT,
  29  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, PUNITIVE, OR CONSEQUENTIAL
  30  * DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, LOSS OF
  31  * USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY THEORY OF
  32  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  33  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
  34  * THE USE OF THIS SOFTWARE, EVEN IF PACKET DESIGN IS ADVISED OF
  35  * THE POSSIBILITY OF SUCH DAMAGE.
  36  *
  37  * Author: Archie Cobbs <archie@freebsd.org>
  38  *
  39  * $FreeBSD: src/sys/netgraph/ng_l2tp.c,v 1.25 2008/03/16 21:33:12 mav Exp $
  40  */
  41
  42 /*
  43  * L2TP netgraph node type.
  44  *
  45  * This node type implements the lower layer of the
  46  * L2TP protocol as specified in RFC 2661.
  47  */
  48
  49 #include <sys/param.h>
  50 #include <sys/systm.h>
  51 #include <sys/kernel.h>
  52 #include <sys/time.h>
  53 #include <sys/conf.h>
  54 #include <sys/mbuf.h>
  55 #include <sys/malloc.h>
  56 #include <sys/errno.h>
  57 #include <sys/libkern.h>
  58
  59 #include <netgraph/ng_message.h>
  60 #include <netgraph/netgraph.h>
  61 #include <netgraph/ng_parse.h>
  62 #include <netgraph/ng_l2tp.h>
  63
  64 #ifdef NG_SEPARATE_MALLOC
  65 MALLOC_DEFINE(M_NETGRAPH_L2TP, "netgraph_l2tp", "netgraph l2tp node");
  66 #else
  67 #define M_NETGRAPH_L2TP M_NETGRAPH
  68 #endif
  69
  70 /* L2TP header format (first 2 bytes only) */
  71 #define L2TP_HDR_CTRL           0x8000                  /* control packet */
  72 #define L2TP_HDR_LEN            0x4000                  /* has length field */
  73 #define L2TP_HDR_SEQ            0x0800                  /* has ns, nr fields */
  74 #define L2TP_HDR_OFF            0x0200                  /* has offset field */
  75 #define L2TP_HDR_PRIO           0x0100                  /* give priority */
  76 #define L2TP_HDR_VERS_MASK      0x000f                  /* version field mask */
  77 #define L2TP_HDR_VERSION        0x0002                  /* version field */
  78
  79 /* Bits that must be zero or one in first two bytes of header */
  80 #define L2TP_CTRL_0BITS         0x030d                  /* ctrl: must be 0 */
  81 #define L2TP_CTRL_1BITS         0xc802                  /* ctrl: must be 1 */
  82 #define L2TP_DATA_0BITS         0x800d                  /* data: must be 0 */
  83 #define L2TP_DATA_1BITS         0x0002                  /* data: must be 1 */
  84
  85 /* Standard xmit ctrl and data header bits */
  86 #define L2TP_CTRL_HDR           (L2TP_HDR_CTRL | L2TP_HDR_LEN \
  87                                     | L2TP_HDR_SEQ | L2TP_HDR_VERSION)
  88 #define L2TP_DATA_HDR           (L2TP_HDR_VERSION)      /* optional: len, seq */
  89
  90 /* Some hard coded values */
  91 #define L2TP_MAX_XWIN           128                     /* my max xmit window */
  92 #define L2TP_MAX_REXMIT         5                       /* default max rexmit */
  93 #define L2TP_MAX_REXMIT_TO      30                      /* default rexmit to */
  94 #define L2TP_DELAYED_ACK        ((hz + 19) / 20)        /* delayed ack: 50 ms */
  95
  96 /* Default data sequence number configuration for new sessions */
  97 #define L2TP_CONTROL_DSEQ       1                       /* we are the lns */
  98 #define L2TP_ENABLE_DSEQ        1                       /* enable data seq # */
  99
 100 /* Compare sequence numbers using circular math */
 101 #define L2TP_SEQ_DIFF(x, y)     ((int)((int16_t)(x) - (int16_t)(y)))
 102
 103 #define SESSHASHSIZE            0x0020
 104 #define SESSHASH(x)             (((x) ^ ((x) >> 8)) & (SESSHASHSIZE - 1))
 105
 106 /* Hook private data (data session hooks only) */
 107 struct ng_l2tp_hook_private {
 108         struct ng_l2tp_sess_config      conf;   /* hook/session config */
 109         struct ng_l2tp_session_stats    stats;  /* per sessions statistics */
 110         hook_p                          hook;   /* hook reference */
 111         u_int16_t                       ns;     /* data ns sequence number */
 112         u_int16_t                       nr;     /* data nr sequence number */
 113         LIST_ENTRY(ng_l2tp_hook_private) sessions;
 114 };
 115 typedef struct ng_l2tp_hook_private *hookpriv_p;
 116
 117 /*
 118  * Sequence number state
 119  *
 120  * Invariants:
 121  *    - If cwnd < ssth, we're doing slow start, otherwise congestion avoidance
 122  *    - The number of unacknowledged xmit packets is (ns - rack) <= seq->wmax
 123  *    - The first (ns - rack) mbuf's in xwin[] array are copies of these
 124  *      unacknowledged packets; the remainder of xwin[] consists first of
 125  *      zero or more further untransmitted packets in the transmit queue
 126  *    - We try to keep the peer's receive window as full as possible.
 127  *      Therefore, (i < cwnd && xwin[i] != NULL) implies (ns - rack) > i.
 128  *    - rack_timer is running iff (ns - rack) > 0 (unack'd xmit'd pkts)
 129  *    - If xack != nr, there are unacknowledged recv packet(s) (delayed ack)
 130  *    - xack_timer is running iff xack != nr (unack'd rec'd pkts)
 131  */
 132 struct l2tp_seq {
 133         u_int16_t               ns;             /* next xmit seq we send */
 134         u_int16_t               nr;             /* next recv seq we expect */
 135         u_int16_t               inproc;         /* packet is in processing */
 136         u_int16_t               rack;           /* last 'nr' we rec'd */
 137         u_int16_t               xack;           /* last 'nr' we sent */
 138         u_int16_t               wmax;           /* peer's max recv window */
 139         u_int16_t               cwnd;           /* current congestion window */
 140         u_int16_t               ssth;           /* slow start threshold */
 141         u_int16_t               acks;           /* # consecutive acks rec'd */
 142         u_int16_t               rexmits;        /* # retransmits sent */
 143         struct callout          rack_timer;     /* retransmit timer */
 144         struct callout          xack_timer;     /* delayed ack timer */
 145         struct mbuf             *xwin[L2TP_MAX_XWIN];   /* transmit window */
 146         struct mtx              mtx;                    /* seq mutex */
 147 };
 148
 149 /* Node private data */
 150 struct ng_l2tp_private {
 151         node_p                  node;           /* back pointer to node */
 152         hook_p                  ctrl;           /* hook to upper layers */
 153         hook_p                  lower;          /* hook to lower layers */
 154         struct ng_l2tp_config   conf;           /* node configuration */
 155         struct ng_l2tp_stats    stats;          /* node statistics */
 156         struct l2tp_seq         seq;            /* ctrl sequence number state */
 157         ng_ID_t                 ftarget;        /* failure message target */
 158         LIST_HEAD(, ng_l2tp_hook_private) sesshash[SESSHASHSIZE];
 159 };
 160 typedef struct ng_l2tp_private *priv_p;
 161
 162 /* Netgraph node methods */
 163 static ng_constructor_t ng_l2tp_constructor;
 164 static ng_rcvmsg_t      ng_l2tp_rcvmsg;
 165 static ng_shutdown_t    ng_l2tp_shutdown;
 166 static ng_newhook_t     ng_l2tp_newhook;
 167 static ng_rcvdata_t     ng_l2tp_rcvdata;
 168 static ng_rcvdata_t     ng_l2tp_rcvdata_lower;
 169 static ng_rcvdata_t     ng_l2tp_rcvdata_ctrl;
 170 static ng_disconnect_t  ng_l2tp_disconnect;
 171
 172 /* Internal functions */
 173 static int      ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns);
 174
 175 static void     ng_l2tp_seq_init(priv_p priv);
 176 static int      ng_l2tp_seq_set(priv_p priv,
 177                         const struct ng_l2tp_seq_config *conf);
 178 static int      ng_l2tp_seq_adjust(priv_p priv,
 179                         const struct ng_l2tp_config *conf);
 180 static void     ng_l2tp_seq_reset(priv_p priv);
 181 static void     ng_l2tp_seq_failure(priv_p priv);
 182 static void     ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr);
 183 static void     ng_l2tp_seq_xack_timeout(node_p node, hook_p hook,
 184                     void *arg1, int arg2);
 185 static void     ng_l2tp_seq_rack_timeout(node_p node, hook_p hook,
 186                     void *arg1, int arg2);
 187
 188 static hookpriv_p       ng_l2tp_find_session(priv_p privp, u_int16_t sid);
 189 static ng_fn_eachhook   ng_l2tp_reset_session;
 190
 191 #ifdef INVARIANTS
 192 static void     ng_l2tp_seq_check(struct l2tp_seq *seq);
 193 #endif
 194
 195 /* Parse type for struct ng_l2tp_seq_config. */
 196 static const struct ng_parse_struct_field
 197         ng_l2tp_seq_config_fields[] = NG_L2TP_SEQ_CONFIG_TYPE_INFO;
 198 static const struct ng_parse_type ng_l2tp_seq_config_type = {
 199         &ng_parse_struct_type,
 200         &ng_l2tp_seq_config_fields
 201 };
 202
 203 /* Parse type for struct ng_l2tp_config */
 204 static const struct ng_parse_struct_field
 205         ng_l2tp_config_type_fields[] = NG_L2TP_CONFIG_TYPE_INFO;
 206 static const struct ng_parse_type ng_l2tp_config_type = {
 207         &ng_parse_struct_type,
 208         &ng_l2tp_config_type_fields,
 209 };
 210
 211 /* Parse type for struct ng_l2tp_sess_config */
 212 static const struct ng_parse_struct_field
 213         ng_l2tp_sess_config_type_fields[] = NG_L2TP_SESS_CONFIG_TYPE_INFO;
 214 static const struct ng_parse_type ng_l2tp_sess_config_type = {
 215         &ng_parse_struct_type,
 216         &ng_l2tp_sess_config_type_fields,
 217 };
 218
 219 /* Parse type for struct ng_l2tp_stats */
 220 static const struct ng_parse_struct_field
 221         ng_l2tp_stats_type_fields[] = NG_L2TP_STATS_TYPE_INFO;
 222 static const struct ng_parse_type ng_l2tp_stats_type = {
 223         &ng_parse_struct_type,
 224         &ng_l2tp_stats_type_fields
 225 };
 226
 227 /* Parse type for struct ng_l2tp_session_stats. */
 228 static const struct ng_parse_struct_field
 229         ng_l2tp_session_stats_type_fields[] = NG_L2TP_SESSION_STATS_TYPE_INFO;
 230 static const struct ng_parse_type ng_l2tp_session_stats_type = {
 231         &ng_parse_struct_type,
 232         &ng_l2tp_session_stats_type_fields
 233 };
 234
 235 /* List of commands and how to convert arguments to/from ASCII */
 236 static const struct ng_cmdlist ng_l2tp_cmdlist[] = {
 237         {
 238           NGM_L2TP_COOKIE,
 239           NGM_L2TP_SET_CONFIG,
 240           "setconfig",
 241           &ng_l2tp_config_type,
 242           NULL
 243         },
 244         {
 245           NGM_L2TP_COOKIE,
 246           NGM_L2TP_GET_CONFIG,
 247           "getconfig",
 248           NULL,
 249           &ng_l2tp_config_type
 250         },
 251         {
 252           NGM_L2TP_COOKIE,
 253           NGM_L2TP_SET_SESS_CONFIG,
 254           "setsessconfig",
 255           &ng_l2tp_sess_config_type,
 256           NULL
 257         },
 258         {
 259           NGM_L2TP_COOKIE,
 260           NGM_L2TP_GET_SESS_CONFIG,
 261           "getsessconfig",
 262           &ng_parse_hint16_type,
 263           &ng_l2tp_sess_config_type
 264         },
 265         {
 266           NGM_L2TP_COOKIE,
 267           NGM_L2TP_GET_STATS,
 268           "getstats",
 269           NULL,
 270           &ng_l2tp_stats_type
 271         },
 272         {
 273           NGM_L2TP_COOKIE,
 274           NGM_L2TP_CLR_STATS,
 275           "clrstats",
 276           NULL,
 277           NULL
 278         },
 279         {
 280           NGM_L2TP_COOKIE,
 281           NGM_L2TP_GETCLR_STATS,
 282           "getclrstats",
 283           NULL,
 284           &ng_l2tp_stats_type
 285         },
 286         {
 287           NGM_L2TP_COOKIE,
 288           NGM_L2TP_GET_SESSION_STATS,
 289           "getsessstats",
 290           &ng_parse_int16_type,
 291           &ng_l2tp_session_stats_type
 292         },
 293         {
 294           NGM_L2TP_COOKIE,
 295           NGM_L2TP_CLR_SESSION_STATS,
 296           "clrsessstats",
 297           &ng_parse_int16_type,
 298           NULL
 299         },
 300         {
 301           NGM_L2TP_COOKIE,
 302           NGM_L2TP_GETCLR_SESSION_STATS,
 303           "getclrsessstats",
 304           &ng_parse_int16_type,
 305           &ng_l2tp_session_stats_type
 306         },
 307         {
 308           NGM_L2TP_COOKIE,
 309           NGM_L2TP_ACK_FAILURE,
 310           "ackfailure",
 311           NULL,
 312           NULL
 313         },
 314         {
 315           NGM_L2TP_COOKIE,
 316           NGM_L2TP_SET_SEQ,
 317           "setsequence",
 318           &ng_l2tp_seq_config_type,
 319           NULL
 320         },
 321         { 0 }
 322 };
 323
 324 /* Node type descriptor */
 325 static struct ng_type ng_l2tp_typestruct = {
 326         .version =      NG_ABI_VERSION,
 327         .name =         NG_L2TP_NODE_TYPE,
 328         .constructor =  ng_l2tp_constructor,
 329         .rcvmsg =       ng_l2tp_rcvmsg,
 330         .shutdown =     ng_l2tp_shutdown,
 331         .newhook =      ng_l2tp_newhook,
 332         .rcvdata =      ng_l2tp_rcvdata,
 333         .disconnect =   ng_l2tp_disconnect,
 334         .cmdlist =      ng_l2tp_cmdlist,
 335 };
 336 NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct);
 337
 338 /* Sequence number state sanity checking */
 339 #ifdef INVARIANTS
 340 #define L2TP_SEQ_CHECK(seq)     ng_l2tp_seq_check(seq)
 341 #else
 342 #define L2TP_SEQ_CHECK(x)       do { } while (0)
 343 #endif
 344
 345 /* memmove macro */
 346 #define memmove(d, s, l)        bcopy(s, d, l)
 347
 348 /* Whether to use m_copypacket() or m_dup() */
 349 #define L2TP_COPY_MBUF          m_copypacket
 350
 351 #define ERROUT(x)       do { error = (x); goto done; } while (0)
 352
 353 /************************************************************************
 354                         NETGRAPH NODE STUFF
 355 ************************************************************************/
 356
 357 /*
 358  * Node type constructor
 359  */
 360 static int
 361 ng_l2tp_constructor(node_p node)
 362 {
 363         priv_p priv;
 364         int     i;
 365
 366         /* Allocate private structure */
 367         MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
 368         if (priv == NULL)
 369                 return (ENOMEM);
 370         NG_NODE_SET_PRIVATE(node, priv);
 371         priv->node = node;
 372
 373         /* Apply a semi-reasonable default configuration */
 374         priv->conf.peer_win = 1;
 375         priv->conf.rexmit_max = L2TP_MAX_REXMIT;
 376         priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO;
 377
 378         /* Initialize sequence number state */
 379         ng_l2tp_seq_init(priv);
 380
 381         for (i = 0; i < SESSHASHSIZE; i++)
 382             LIST_INIT(&priv->sesshash[i]);
 383
 384         /* Done */
 385         return (0);
 386 }
 387
 388 /*
 389  * Give our OK for a hook to be added.
 390  */
 391 static int
 392 ng_l2tp_newhook(node_p node, hook_p hook, const char *name)
 393 {
 394         const priv_p priv = NG_NODE_PRIVATE(node);
 395
 396         /* Check hook name */
 397         if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) {
 398                 if (priv->ctrl != NULL)
 399                         return (EISCONN);
 400                 priv->ctrl = hook;
 401                 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_ctrl);
 402         } else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) {
 403                 if (priv->lower != NULL)
 404                         return (EISCONN);
 405                 priv->lower = hook;
 406                 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_lower);
 407         } else {
 408                 static const char hexdig[16] = "0123456789abcdef";
 409                 u_int16_t session_id;
 410                 hookpriv_p hpriv;
 411                 uint16_t hash;
 412                 const char *hex;
 413                 int i;
 414                 int j;
 415
 416                 /* Parse hook name to get session ID */
 417                 if (strncmp(name, NG_L2TP_HOOK_SESSION_P,
 418                     sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0)
 419                         return (EINVAL);
 420                 hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1;
 421                 for (session_id = i = 0; i < 4; i++) {
 422                         for (j = 0; j < 16 && hex[i] != hexdig[j]; j++);
 423                         if (j == 16)
 424                                 return (EINVAL);
 425                         session_id = (session_id << 4) | j;
 426                 }
 427                 if (hex[i] != '\0')
 428                         return (EINVAL);
 429
 430                 /* Create hook private structure */
 431                 MALLOC(hpriv, hookpriv_p,
 432                     sizeof(*hpriv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
 433                 if (hpriv == NULL)
 434                         return (ENOMEM);
 435                 hpriv->conf.session_id = htons(session_id);
 436                 hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ;
 437                 hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ;
 438                 hpriv->hook = hook;
 439                 NG_HOOK_SET_PRIVATE(hook, hpriv);
 440                 hash = SESSHASH(hpriv->conf.session_id);
 441                 LIST_INSERT_HEAD(&priv->sesshash[hash], hpriv, sessions);
 442         }
 443
 444         /* Done */
 445         return (0);
 446 }
 447
 448 /*
 449  * Receive a control message.
 450  */
 451 static int
 452 ng_l2tp_rcvmsg(node_p node, item_p item, hook_p lasthook)
 453 {
 454         const priv_p priv = NG_NODE_PRIVATE(node);
 455         struct ng_mesg *resp = NULL;
 456         struct ng_mesg *msg;
 457         int error = 0;
 458
 459         NGI_GET_MSG(item, msg);
 460         switch (msg->header.typecookie) {
 461         case NGM_L2TP_COOKIE:
 462                 switch (msg->header.cmd) {
 463                 case NGM_L2TP_SET_CONFIG:
 464                     {
 465                         struct ng_l2tp_config *const conf =
 466                                 (struct ng_l2tp_config *)msg->data;
 467
 468                         /* Check for invalid or illegal config */
 469                         if (msg->header.arglen != sizeof(*conf)) {
 470                                 error = EINVAL;
 471                                 break;
 472                         }
 473                         conf->enabled = !!conf->enabled;
 474                         conf->match_id = !!conf->match_id;
 475                         conf->tunnel_id = htons(conf->tunnel_id);
 476                         conf->peer_id = htons(conf->peer_id);
 477                         if (priv->conf.enabled
 478                             && ((priv->conf.tunnel_id != 0
 479                                && conf->tunnel_id != priv->conf.tunnel_id)
 480                               || ((priv->conf.peer_id != 0
 481                                && conf->peer_id != priv->conf.peer_id)))) {
 482                                 error = EBUSY;
 483                                 break;
 484                         }
 485
 486                         /* Save calling node as failure target */
 487                         priv->ftarget = NGI_RETADDR(item);
 488
 489                         /* Adjust sequence number state */
 490                         if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0)
 491                                 break;
 492
 493                         /* Update node's config */
 494                         priv->conf = *conf;
 495                         break;
 496                     }
 497                 case NGM_L2TP_GET_CONFIG:
 498                     {
 499                         struct ng_l2tp_config *conf;
 500
 501                         NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT);
 502                         if (resp == NULL) {
 503                                 error = ENOMEM;
 504                                 break;
 505                         }
 506                         conf = (struct ng_l2tp_config *)resp->data;
 507                         *conf = priv->conf;
 508
 509                         /* Put ID's in host order */
 510                         conf->tunnel_id = ntohs(conf->tunnel_id);
 511                         conf->peer_id = ntohs(conf->peer_id);
 512                         break;
 513                     }
 514                 case NGM_L2TP_SET_SESS_CONFIG:
 515                     {
 516                         struct ng_l2tp_sess_config *const conf =
 517                             (struct ng_l2tp_sess_config *)msg->data;
 518                         hookpriv_p hpriv;
 519
 520                         /* Check for invalid or illegal config. */
 521                         if (msg->header.arglen != sizeof(*conf)) {
 522                                 error = EINVAL;
 523                                 break;
 524                         }
 525
 526                         /* Put ID's in network order */
 527                         conf->session_id = htons(conf->session_id);
 528                         conf->peer_id = htons(conf->peer_id);
 529
 530                         /* Find matching hook */
 531                         hpriv = ng_l2tp_find_session(priv, conf->session_id);
 532                         if (hpriv == NULL) {
 533                                 error = ENOENT;
 534                                 break;
 535                         }
 536
 537                         /* Update hook's config */
 538                         hpriv->conf = *conf;
 539                         break;
 540                     }
 541                 case NGM_L2TP_GET_SESS_CONFIG:
 542                     {
 543                         struct ng_l2tp_sess_config *conf;
 544                         u_int16_t session_id;
 545                         hookpriv_p hpriv;
 546
 547                         /* Get session ID */
 548                         if (msg->header.arglen != sizeof(session_id)) {
 549                                 error = EINVAL;
 550                                 break;
 551                         }
 552                         memcpy(&session_id, msg->data, 2);
 553                         session_id = htons(session_id);
 554
 555                         /* Find matching hook */
 556                         hpriv = ng_l2tp_find_session(priv, session_id);
 557                         if (hpriv == NULL) {
 558                                 error = ENOENT;
 559                                 break;
 560                         }
 561
 562                         /* Send response */
 563                         NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_NOWAIT);
 564                         if (resp == NULL) {
 565                                 error = ENOMEM;
 566                                 break;
 567                         }
 568                         conf = (struct ng_l2tp_sess_config *)resp->data;
 569                         *conf = hpriv->conf;
 570
 571                         /* Put ID's in host order */
 572                         conf->session_id = ntohs(conf->session_id);
 573                         conf->peer_id = ntohs(conf->peer_id);
 574                         break;
 575                     }
 576                 case NGM_L2TP_GET_STATS:
 577                 case NGM_L2TP_CLR_STATS:
 578                 case NGM_L2TP_GETCLR_STATS:
 579                     {
 580                         if (msg->header.cmd != NGM_L2TP_CLR_STATS) {
 581                                 NG_MKRESPONSE(resp, msg,
 582                                     sizeof(priv->stats), M_NOWAIT);
 583                                 if (resp == NULL) {
 584                                         error = ENOMEM;
 585                                         break;
 586                                 }
 587                                 memcpy(resp->data,
 588                                     &priv->stats, sizeof(priv->stats));
 589                         }
 590                         if (msg->header.cmd != NGM_L2TP_GET_STATS)
 591                                 memset(&priv->stats, 0, sizeof(priv->stats));
 592                         break;
 593                     }
 594                 case NGM_L2TP_GET_SESSION_STATS:
 595                 case NGM_L2TP_CLR_SESSION_STATS:
 596                 case NGM_L2TP_GETCLR_SESSION_STATS:
 597                     {
 598                         uint16_t session_id;
 599                         hookpriv_p hpriv;
 600
 601                         /* Get session ID. */
 602                         if (msg->header.arglen != sizeof(session_id)) {
 603                                 error = EINVAL;
 604                                 break;
 605                         }
 606                         bcopy(msg->data, &session_id, sizeof(uint16_t));
 607                         session_id = htons(session_id);
 608
 609                         /* Find matching hook. */
 610                         hpriv = ng_l2tp_find_session(priv, session_id);
 611                         if (hpriv == NULL) {
 612                                 error = ENOENT;
 613                                 break;
 614                         }
 615
 616                         if (msg->header.cmd != NGM_L2TP_CLR_SESSION_STATS) {
 617                                 NG_MKRESPONSE(resp, msg,
 618                                     sizeof(hpriv->stats), M_NOWAIT);
 619                                 if (resp == NULL) {
 620                                         error = ENOMEM;
 621                                         break;
 622                                 }
 623                                 bcopy(&hpriv->stats, resp->data,
 624                                         sizeof(hpriv->stats));
 625                         }
 626                         if (msg->header.cmd != NGM_L2TP_GET_SESSION_STATS)
 627                                 bzero(&hpriv->stats, sizeof(hpriv->stats));
 628                         break;
 629                     }
 630                 case NGM_L2TP_SET_SEQ:
 631                     {
 632                         struct ng_l2tp_seq_config *const conf =
 633                                 (struct ng_l2tp_seq_config *)msg->data;
 634
 635                         /* Check for invalid or illegal seq config. */
 636                         if (msg->header.arglen != sizeof(*conf)) {
 637                                 error = EINVAL;
 638                                 break;
 639                         }
 640                         conf->ns = htons(conf->ns);
 641                         conf->nr = htons(conf->nr);
 642                         conf->rack = htons(conf->rack);
 643                         conf->xack = htons(conf->xack);
 644
 645                         /* Set sequence numbers. */
 646                         error = ng_l2tp_seq_set(priv, conf);
 647                         break;
 648                     }
 649                 default:
 650                         error = EINVAL;
 651                         break;
 652                 }
 653                 break;
 654         default:
 655                 error = EINVAL;
 656                 break;
 657         }
 658
 659         /* Done */
 660         NG_RESPOND_MSG(error, node, item, resp);
 661         NG_FREE_MSG(msg);
 662         return (error);
 663 }
 664
 665 /*
 666  * Destroy node
 667  */
 668 static int
 669 ng_l2tp_shutdown(node_p node)
 670 {
 671         const priv_p priv = NG_NODE_PRIVATE(node);
 672         struct l2tp_seq *const seq = &priv->seq;
 673
 674         /* Sanity check */
 675         L2TP_SEQ_CHECK(seq);
 676
 677         /* Reset sequence number state */
 678         ng_l2tp_seq_reset(priv);
 679
 680         /* Free private data if neither timer is running */
 681         ng_uncallout(&seq->rack_timer, node);
 682         ng_uncallout(&seq->xack_timer, node);
 683
 684         mtx_destroy(&seq->mtx);
 685
 686         FREE(priv, M_NETGRAPH_L2TP);
 687
 688         /* Unref node */
 689         NG_NODE_UNREF(node);
 690         return (0);
 691 }
 692
 693 /*
 694  * Hook disconnection
 695  */
 696 static int
 697 ng_l2tp_disconnect(hook_p hook)
 698 {
 699         const node_p node = NG_HOOK_NODE(hook);
 700         const priv_p priv = NG_NODE_PRIVATE(node);
 701
 702         /* Zero out hook pointer */
 703         if (hook == priv->ctrl)
 704                 priv->ctrl = NULL;
 705         else if (hook == priv->lower)
 706                 priv->lower = NULL;
 707         else {
 708                 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
 709                 LIST_REMOVE(hpriv, sessions);
 710                 FREE(hpriv, M_NETGRAPH_L2TP);
 711                 NG_HOOK_SET_PRIVATE(hook, NULL);
 712         }
 713
 714         /* Go away if no longer connected to anything */
 715         if (NG_NODE_NUMHOOKS(node) == 0 && NG_NODE_IS_VALID(node))
 716                 ng_rmnode_self(node);
 717         return (0);
 718 }
 719
 720 /*************************************************************************
 721                         INTERNAL FUNCTIONS
 722 *************************************************************************/
 723
 724 /*
 725  * Find the hook with a given session ID (in network order).
 726  */
 727 static hookpriv_p
 728 ng_l2tp_find_session(priv_p privp, u_int16_t sid)
 729 {
 730         uint16_t        hash = SESSHASH(sid);
 731         hookpriv_p      hpriv = NULL;
 732
 733         LIST_FOREACH(hpriv, &privp->sesshash[hash], sessions) {
 734                 if (hpriv->conf.session_id == sid)
 735                         break;
 736         }
 737
 738         return (hpriv);
 739 }
 740
 741 /*
 742  * Reset a hook's session state.
 743  */
 744 static int
 745 ng_l2tp_reset_session(hook_p hook, void *arg)
 746 {
 747         const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
 748
 749         if (hpriv != NULL) {
 750                 hpriv->conf.control_dseq = 0;
 751                 hpriv->conf.enable_dseq = 0;
 752                 bzero(&hpriv->conf, sizeof(struct ng_l2tp_session_stats));
 753                 hpriv->nr = 0;
 754                 hpriv->ns = 0;
 755         }
 756         return (-1);
 757 }
 758
 759 /*
 760  * Handle an incoming frame from below.
 761  */
 762 static int
 763 ng_l2tp_rcvdata_lower(hook_p h, item_p item)
 764 {
 765         static const u_int16_t req_bits[2][2] = {
 766                 { L2TP_DATA_0BITS, L2TP_DATA_1BITS },
 767                 { L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
 768         };
 769         const node_p node = NG_HOOK_NODE(h);
 770         const priv_p priv = NG_NODE_PRIVATE(node);
 771         hookpriv_p hpriv = NULL;
 772         hook_p hook = NULL;
 773         u_int16_t ids[2];
 774         struct mbuf *m;
 775         u_int16_t hdr;
 776         u_int16_t ns;
 777         u_int16_t nr;
 778         int is_ctrl;
 779         int error;
 780         int len, plen;
 781
 782         /* Sanity check */
 783         L2TP_SEQ_CHECK(&priv->seq);
 784
 785         /* If not configured, reject */
 786         if (!priv->conf.enabled) {
 787                 NG_FREE_ITEM(item);
 788                 ERROUT(ENXIO);
 789         }
 790
 791         /* Grab mbuf */
 792         NGI_GET_M(item, m);
 793
 794         /* Remember full packet length; needed for per session accounting. */
 795         plen = m->m_pkthdr.len;
 796
 797         /* Update stats */
 798         priv->stats.recvPackets++;
 799         priv->stats.recvOctets += plen;
 800
 801         /* Get initial header */
 802         if (m->m_pkthdr.len < 6) {
 803                 priv->stats.recvRunts++;
 804                 NG_FREE_ITEM(item);
 805                 NG_FREE_M(m);
 806                 ERROUT(EINVAL);
 807         }
 808         if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 809                 priv->stats.memoryFailures++;
 810                 NG_FREE_ITEM(item);
 811                 ERROUT(EINVAL);
 812         }
 813         hdr = ntohs(*mtod(m, u_int16_t *));
 814         m_adj(m, 2);
 815
 816         /* Check required header bits and minimum length */
 817         is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
 818         if ((hdr & req_bits[is_ctrl][0]) != 0
 819             || (~hdr & req_bits[is_ctrl][1]) != 0) {
 820                 priv->stats.recvInvalid++;
 821                 NG_FREE_ITEM(item);
 822                 NG_FREE_M(m);
 823                 ERROUT(EINVAL);
 824         }
 825         if (m->m_pkthdr.len < 4                         /* tunnel, session id */
 826             + (2 * ((hdr & L2TP_HDR_LEN) != 0))         /* length field */
 827             + (4 * ((hdr & L2TP_HDR_SEQ) != 0))         /* seq # fields */
 828             + (2 * ((hdr & L2TP_HDR_OFF) != 0))) {      /* offset field */
 829                 priv->stats.recvRunts++;
 830                 NG_FREE_ITEM(item);
 831                 NG_FREE_M(m);
 832                 ERROUT(EINVAL);
 833         }
 834
 835         /* Get and validate length field if present */
 836         if ((hdr & L2TP_HDR_LEN) != 0) {
 837                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 838                         priv->stats.memoryFailures++;
 839                         NG_FREE_ITEM(item);
 840                         ERROUT(EINVAL);
 841                 }
 842                 len = (u_int16_t)ntohs(*mtod(m, u_int16_t *)) - 4;
 843                 m_adj(m, 2);
 844                 if (len < 0 || len > m->m_pkthdr.len) {
 845                         priv->stats.recvInvalid++;
 846                         NG_FREE_ITEM(item);
 847                         NG_FREE_M(m);
 848                         ERROUT(EINVAL);
 849                 }
 850                 if (len < m->m_pkthdr.len)              /* trim extra bytes */
 851                         m_adj(m, -(m->m_pkthdr.len - len));
 852         }
 853
 854         /* Get tunnel ID and session ID */
 855         if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
 856                 priv->stats.memoryFailures++;
 857                 NG_FREE_ITEM(item);
 858                 ERROUT(EINVAL);
 859         }
 860         memcpy(ids, mtod(m, u_int16_t *), 4);
 861         m_adj(m, 4);
 862
 863         /* Check tunnel ID */
 864         if (ids[0] != priv->conf.tunnel_id
 865             && (priv->conf.match_id || ids[0] != 0)) {
 866                 priv->stats.recvWrongTunnel++;
 867                 NG_FREE_ITEM(item);
 868                 NG_FREE_M(m);
 869                 ERROUT(EADDRNOTAVAIL);
 870         }
 871
 872         /* Check session ID (for data packets only) */
 873         if ((hdr & L2TP_HDR_CTRL) == 0) {
 874                 hpriv = ng_l2tp_find_session(priv, ids[1]);
 875                 if (hpriv == NULL) {
 876                         priv->stats.recvUnknownSID++;
 877                         NG_FREE_ITEM(item);
 878                         NG_FREE_M(m);
 879                         ERROUT(ENOTCONN);
 880                 }
 881                 hook = hpriv->hook;
 882         }
 883
 884         /* Get Ns, Nr fields if present */
 885         if ((hdr & L2TP_HDR_SEQ) != 0) {
 886                 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
 887                         priv->stats.memoryFailures++;
 888                         NG_FREE_ITEM(item);
 889                         ERROUT(EINVAL);
 890                 }
 891                 memcpy(&ns, &mtod(m, u_int16_t *)[0], 2);
 892                 ns = ntohs(ns);
 893                 memcpy(&nr, &mtod(m, u_int16_t *)[1], 2);
 894                 nr = ntohs(nr);
 895                 m_adj(m, 4);
 896         }
 897
 898         /* Strip offset padding if present */
 899         if ((hdr & L2TP_HDR_OFF) != 0) {
 900                 u_int16_t offset;
 901
 902                 /* Get length of offset padding */
 903                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 904                         priv->stats.memoryFailures++;
 905                         NG_FREE_ITEM(item);
 906                         ERROUT(EINVAL);
 907                 }
 908                 memcpy(&offset, mtod(m, u_int16_t *), 2);
 909                 offset = ntohs(offset);
 910
 911                 /* Trim offset padding */
 912                 if ((2+offset) > m->m_pkthdr.len) {
 913                         priv->stats.recvInvalid++;
 914                         NG_FREE_ITEM(item);
 915                         NG_FREE_M(m);
 916                         ERROUT(EINVAL);
 917                 }
 918                 m_adj(m, 2+offset);
 919         }
 920
 921         /* Handle control packets */
 922         if ((hdr & L2TP_HDR_CTRL) != 0) {
 923                 struct l2tp_seq *const seq = &priv->seq;
 924
 925                 /* Handle receive ack sequence number Nr */
 926                 ng_l2tp_seq_recv_nr(priv, nr);
 927
 928                 /* Discard ZLB packets */
 929                 if (m->m_pkthdr.len == 0) {
 930                         priv->stats.recvZLBs++;
 931                         NG_FREE_ITEM(item);
 932                         NG_FREE_M(m);
 933                         ERROUT(0);
 934                 }
 935
 936                 mtx_lock(&seq->mtx);
 937                 /*
 938                  * If not what we expect or we are busy, drop packet and
 939                  * send an immediate ZLB ack.
 940                  */
 941                 if (ns != seq->nr || seq->inproc) {
 942                         if (L2TP_SEQ_DIFF(ns, seq->nr) <= 0)
 943                                 priv->stats.recvDuplicates++;
 944                         else
 945                                 priv->stats.recvOutOfOrder++;
 946                         mtx_unlock(&seq->mtx);
 947                         ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
 948                         NG_FREE_ITEM(item);
 949                         NG_FREE_M(m);
 950                         ERROUT(0);
 951                 }
 952                 /*
 953                  * Until we deliver this packet we can't receive next one as
 954                  * we have no information for sending ack.
 955                  */
 956                 seq->inproc = 1;
 957                 mtx_unlock(&seq->mtx);
 958
 959                 /* Prepend session ID to packet. */
 960                 M_PREPEND(m, 2, M_DONTWAIT);
 961                 if (m == NULL) {
 962                         seq->inproc = 0;
 963                         priv->stats.memoryFailures++;
 964                         NG_FREE_ITEM(item);
 965                         ERROUT(ENOBUFS);
 966                 }
 967                 memcpy(mtod(m, u_int16_t *), &ids[1], 2);
 968
 969                 /* Deliver packet to upper layers */
 970                 NG_FWD_NEW_DATA(error, item, priv->ctrl, m);
 971
 972                 mtx_lock(&seq->mtx);
 973                 /* Ready to process next packet. */
 974                 seq->inproc = 0;
 975
 976                 /* If packet was successfully delivered send ack. */
 977                 if (error == 0) {
 978                         /* Update recv sequence number */
 979                         seq->nr++;
 980                         /* Start receive ack timer, if not already running */
 981                         if (!callout_active(&seq->xack_timer)) {
 982                                 ng_callout(&seq->xack_timer, priv->node, NULL,
 983                                     L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout,
 984                                     NULL, 0);
 985                         }
 986                 }
 987                 mtx_unlock(&seq->mtx);
 988
 989                 ERROUT(error);
 990         }
 991
 992         /* Per session packet, account it. */
 993         hpriv->stats.recvPackets++;
 994         hpriv->stats.recvOctets += plen;
 995
 996         /* Follow peer's lead in data sequencing, if configured to do so */
 997         if (!hpriv->conf.control_dseq)
 998                 hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0);
 999
1000         /* Handle data sequence numbers if present and enabled */
1001         if ((hdr & L2TP_HDR_SEQ) != 0) {
1002                 if (hpriv->conf.enable_dseq
1003                     && L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) {
1004                         NG_FREE_ITEM(item);     /* duplicate or out of order */
1005                         NG_FREE_M(m);
1006                         priv->stats.recvDataDrops++;
1007                         ERROUT(0);
1008                 }
1009                 hpriv->nr = ns + 1;
1010         }
1011
1012         /* Drop empty data packets */
1013         if (m->m_pkthdr.len == 0) {
1014                 NG_FREE_ITEM(item);
1015                 NG_FREE_M(m);
1016                 ERROUT(0);
1017         }
1018
1019         /* Deliver data */
1020         NG_FWD_NEW_DATA(error, item, hook, m);
1021 done:
1022         /* Done */
1023         L2TP_SEQ_CHECK(&priv->seq);
1024         return (error);
1025 }
1026
1027 /*
1028  * Handle an outgoing control frame.
1029  */
1030 static int
1031 ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item)
1032 {
1033         const node_p node = NG_HOOK_NODE(hook);
1034         const priv_p priv = NG_NODE_PRIVATE(node);
1035         struct l2tp_seq *const seq = &priv->seq;
1036         struct mbuf *m;
1037         int error;
1038         int i;
1039         u_int16_t       ns;
1040
1041         /* Sanity check */
1042         L2TP_SEQ_CHECK(&priv->seq);
1043
1044         /* If not configured, reject */
1045         if (!priv->conf.enabled) {
1046                 NG_FREE_ITEM(item);
1047                 ERROUT(ENXIO);
1048         }
1049
1050         /* Grab mbuf and discard other stuff XXX */
1051         NGI_GET_M(item, m);
1052         NG_FREE_ITEM(item);
1053
1054         /* Packet should have session ID prepended */
1055         if (m->m_pkthdr.len < 2) {
1056                 priv->stats.xmitInvalid++;
1057                 m_freem(m);
1058                 ERROUT(EINVAL);
1059         }
1060
1061         /* Check max length */
1062         if (m->m_pkthdr.len >= 0x10000 - 14) {
1063                 priv->stats.xmitTooBig++;
1064                 m_freem(m);
1065                 ERROUT(EOVERFLOW);
1066         }
1067
1068         mtx_lock(&seq->mtx);
1069
1070         /* Find next empty slot in transmit queue */
1071         for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
1072         if (i == L2TP_MAX_XWIN) {
1073                 mtx_unlock(&seq->mtx);
1074                 priv->stats.xmitDrops++;
1075                 m_freem(m);
1076                 ERROUT(ENOBUFS);
1077         }
1078         seq->xwin[i] = m;
1079
1080         /* If peer's receive window is already full, nothing else to do */
1081         if (i >= seq->cwnd) {
1082                 mtx_unlock(&seq->mtx);
1083                 ERROUT(0);
1084         }
1085
1086         /* Start retransmit timer if not already running */
1087         if (!callout_active(&seq->rack_timer))
1088                 ng_callout(&seq->rack_timer, node, NULL,
1089                     hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1090
1091         ns = seq->ns++;
1092
1093         mtx_unlock(&seq->mtx);
1094
1095         /* Copy packet */
1096         if ((m = L2TP_COPY_MBUF(m, M_DONTWAIT)) == NULL) {
1097                 priv->stats.memoryFailures++;
1098                 ERROUT(ENOBUFS);
1099         }
1100
1101         /* Send packet and increment xmit sequence number */
1102         error = ng_l2tp_xmit_ctrl(priv, m, ns);
1103 done:
1104         /* Done */
1105         L2TP_SEQ_CHECK(&priv->seq);
1106         return (error);
1107 }
1108
1109 /*
1110  * Handle an outgoing data frame.
1111  */
1112 static int
1113 ng_l2tp_rcvdata(hook_p hook, item_p item)
1114 {
1115         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
1116         const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
1117         struct mbuf *m;
1118         u_int16_t hdr;
1119         int error;
1120         int i = 1;
1121
1122         /* Sanity check */
1123         L2TP_SEQ_CHECK(&priv->seq);
1124
1125         /* If not configured, reject */
1126         if (!priv->conf.enabled) {
1127                 NG_FREE_ITEM(item);
1128                 ERROUT(ENXIO);
1129         }
1130
1131         /* Get mbuf */
1132         NGI_GET_M(item, m);
1133
1134         /* Check max length */
1135         if (m->m_pkthdr.len >= 0x10000 - 12) {
1136                 priv->stats.xmitDataTooBig++;
1137                 NG_FREE_ITEM(item);
1138                 NG_FREE_M(m);
1139                 ERROUT(EOVERFLOW);
1140         }
1141
1142         /* Prepend L2TP header */
1143         M_PREPEND(m, 6
1144             + (2 * (hpriv->conf.include_length != 0))
1145             + (4 * (hpriv->conf.enable_dseq != 0)),
1146             M_DONTWAIT);
1147         if (m == NULL) {
1148                 priv->stats.memoryFailures++;
1149                 NG_FREE_ITEM(item);
1150                 ERROUT(ENOBUFS);
1151         }
1152         hdr = L2TP_DATA_HDR;
1153         if (hpriv->conf.include_length) {
1154                 hdr |= L2TP_HDR_LEN;
1155                 mtod(m, u_int16_t *)[i++] = htons(m->m_pkthdr.len);
1156         }
1157         mtod(m, u_int16_t *)[i++] = priv->conf.peer_id;
1158         mtod(m, u_int16_t *)[i++] = hpriv->conf.peer_id;
1159         if (hpriv->conf.enable_dseq) {
1160                 hdr |= L2TP_HDR_SEQ;
1161                 mtod(m, u_int16_t *)[i++] = htons(hpriv->ns);
1162                 mtod(m, u_int16_t *)[i++] = htons(hpriv->nr);
1163                 hpriv->ns++;
1164         }
1165         mtod(m, u_int16_t *)[0] = htons(hdr);
1166
1167         /* Update per session stats. */
1168         hpriv->stats.xmitPackets++;
1169         hpriv->stats.xmitOctets += m->m_pkthdr.len;
1170
1171         /* And the global one. */
1172         priv->stats.xmitPackets++;
1173         priv->stats.xmitOctets += m->m_pkthdr.len;
1174
1175         /* Send packet */
1176         NG_FWD_NEW_DATA(error, item, priv->lower, m);
1177 done:
1178         /* Done */
1179         L2TP_SEQ_CHECK(&priv->seq);
1180         return (error);
1181 }
1182
1183 /*
1184  * Send a message to our controlling node that we've failed.
1185  */
1186 static void
1187 ng_l2tp_seq_failure(priv_p priv)
1188 {
1189         struct ng_mesg *msg;
1190         int error;
1191
1192         NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_NOWAIT);
1193         if (msg == NULL)
1194                 return;
1195         NG_SEND_MSG_ID(error, priv->node, msg, priv->ftarget, 0);
1196 }
1197
1198 /************************************************************************
1199                         SEQUENCE NUMBER HANDLING
1200 ************************************************************************/
1201
1202 /*
1203  * Initialize sequence number state.
1204  */
1205 static void
1206 ng_l2tp_seq_init(priv_p priv)
1207 {
1208         struct l2tp_seq *const seq = &priv->seq;
1209
1210         KASSERT(priv->conf.peer_win >= 1,
1211             ("%s: peer_win is zero", __func__));
1212         memset(seq, 0, sizeof(*seq));
1213         seq->cwnd = 1;
1214         seq->wmax = priv->conf.peer_win;
1215         if (seq->wmax > L2TP_MAX_XWIN)
1216                 seq->wmax = L2TP_MAX_XWIN;
1217         seq->ssth = seq->wmax;
1218         ng_callout_init(&seq->rack_timer);
1219         ng_callout_init(&seq->xack_timer);
1220         mtx_init(&seq->mtx, "ng_l2tp", NULL, MTX_DEF);
1221         L2TP_SEQ_CHECK(seq);
1222 }
1223
1224 /*
1225  * Set sequence number state as given from user.
1226  */
1227 static int
1228 ng_l2tp_seq_set(priv_p priv, const struct ng_l2tp_seq_config *conf)
1229 {
1230         struct l2tp_seq *const seq = &priv->seq;
1231
1232         /* If node is enabled, deny update to sequence numbers. */
1233         if (priv->conf.enabled)
1234                 return (EBUSY);
1235
1236         /* We only can handle the simple cases. */
1237         if (conf->xack != conf->nr || conf->ns != conf->rack)
1238                 return (EINVAL);
1239
1240         /* Set ns,nr,rack,xack parameters. */
1241         seq->ns = conf->ns;
1242         seq->nr = conf->nr;
1243         seq->rack = conf->rack;
1244         seq->xack = conf->xack;
1245
1246         return (0);
1247 }
1248
1249 /*
1250  * Adjust sequence number state accordingly after reconfiguration.
1251  */
1252 static int
1253 ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf)
1254 {
1255         struct l2tp_seq *const seq = &priv->seq;
1256         u_int16_t new_wmax;
1257
1258         /* If disabling node, reset state sequence number */
1259         if (!conf->enabled) {
1260                 ng_l2tp_seq_reset(priv);
1261                 return (0);
1262         }
1263
1264         /* Adjust peer's max recv window; it can only increase */
1265         new_wmax = conf->peer_win;
1266         if (new_wmax > L2TP_MAX_XWIN)
1267                 new_wmax = L2TP_MAX_XWIN;
1268         if (new_wmax == 0)
1269                 return (EINVAL);
1270         if (new_wmax < seq->wmax)
1271                 return (EBUSY);
1272         seq->wmax = new_wmax;
1273
1274         /* Done */
1275         return (0);
1276 }
1277
1278 /*
1279  * Reset sequence number state.
1280  */
1281 static void
1282 ng_l2tp_seq_reset(priv_p priv)
1283 {
1284         struct l2tp_seq *const seq = &priv->seq;
1285         hook_p hook;
1286         int i;
1287
1288         /* Sanity check */
1289         L2TP_SEQ_CHECK(seq);
1290
1291         /* Stop timers */
1292         ng_uncallout(&seq->rack_timer, priv->node);
1293         ng_uncallout(&seq->xack_timer, priv->node);
1294
1295         /* Free retransmit queue */
1296         for (i = 0; i < L2TP_MAX_XWIN; i++) {
1297                 if (seq->xwin[i] == NULL)
1298                         break;
1299                 m_freem(seq->xwin[i]);
1300         }
1301
1302         /* Reset session hooks' sequence number states */
1303         NG_NODE_FOREACH_HOOK(priv->node, ng_l2tp_reset_session, NULL, hook);
1304
1305         /* Reset node's sequence number state */
1306         seq->ns = 0;
1307         seq->nr = 0;
1308         seq->rack = 0;
1309         seq->xack = 0;
1310         seq->wmax = L2TP_MAX_XWIN;
1311         seq->cwnd = 1;
1312         seq->ssth = seq->wmax;
1313         seq->acks = 0;
1314         seq->rexmits = 0;
1315         bzero(seq->xwin, sizeof(seq->xwin));
1316
1317         /* Done */
1318         L2TP_SEQ_CHECK(seq);
1319 }
1320
1321 /*
1322  * Handle receipt of an acknowledgement value (Nr) from peer.
1323  */
1324 static void
1325 ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr)
1326 {
1327         struct l2tp_seq *const seq = &priv->seq;
1328         struct mbuf     *xwin[L2TP_MAX_XWIN];   /* partial local copy */
1329         int             nack;
1330         int             i, j;
1331         uint16_t        ns;
1332
1333         mtx_lock(&seq->mtx);
1334
1335         /* Verify peer's ACK is in range */
1336         if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0) {
1337                 mtx_unlock(&seq->mtx);
1338                 return;                         /* duplicate ack */
1339         }
1340         if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) {
1341                 mtx_unlock(&seq->mtx);
1342                 priv->stats.recvBadAcks++;      /* ack for packet not sent */
1343                 return;
1344         }
1345         KASSERT(nack <= L2TP_MAX_XWIN,
1346             ("%s: nack=%d > %d", __func__, nack, L2TP_MAX_XWIN));
1347
1348         /* Update receive ack stats */
1349         seq->rack = nr;
1350         seq->rexmits = 0;
1351
1352         /* Free acknowledged packets and shift up packets in the xmit queue */
1353         for (i = 0; i < nack; i++)
1354                 m_freem(seq->xwin[i]);
1355         memmove(seq->xwin, seq->xwin + nack,
1356             (L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin));
1357         memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0,
1358             nack * sizeof(*seq->xwin));
1359
1360         /*
1361          * Do slow-start/congestion avoidance windowing algorithm described
1362          * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
1363          * ACK had arrived separately.
1364          */
1365         if (seq->cwnd < seq->wmax) {
1366
1367                 /* Handle slow start phase */
1368                 if (seq->cwnd < seq->ssth) {
1369                         seq->cwnd += nack;
1370                         nack = 0;
1371                         if (seq->cwnd > seq->ssth) {    /* into cg.av. phase */
1372                                 nack = seq->cwnd - seq->ssth;
1373                                 seq->cwnd = seq->ssth;
1374                         }
1375                 }
1376
1377                 /* Handle congestion avoidance phase */
1378                 if (seq->cwnd >= seq->ssth) {
1379                         seq->acks += nack;
1380                         while (seq->acks >= seq->cwnd) {
1381                                 seq->acks -= seq->cwnd;
1382                                 if (seq->cwnd < seq->wmax)
1383                                         seq->cwnd++;
1384                         }
1385                 }
1386         }
1387
1388         /* Stop xmit timer */
1389         if (callout_active(&seq->rack_timer))
1390                 ng_uncallout(&seq->rack_timer, priv->node);
1391
1392         /* If transmit queue is empty, we're done for now */
1393         if (seq->xwin[0] == NULL) {
1394                 mtx_unlock(&seq->mtx);
1395                 return;
1396         }
1397
1398         /* Start restransmit timer again */
1399         ng_callout(&seq->rack_timer, priv->node, NULL,
1400             hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1401
1402         /*
1403          * Send more packets, trying to keep peer's receive window full.
1404          * Make copy of everything we need before lock release.
1405          */
1406         ns = seq->ns;
1407         j = 0;
1408         while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd
1409             && seq->xwin[i] != NULL) {
1410                 xwin[j++] = seq->xwin[i];
1411                 seq->ns++;
1412         }
1413
1414         mtx_unlock(&seq->mtx);
1415
1416         /*
1417          * Send prepared.
1418          * If there is a memory error, pretend packet was sent, as it
1419          * will get retransmitted later anyway.
1420          */
1421         for (i = 0; i < j; i++) {
1422                 struct mbuf     *m;
1423                 if ((m = L2TP_COPY_MBUF(xwin[i], M_DONTWAIT)) == NULL)
1424                         priv->stats.memoryFailures++;
1425                 else
1426                         ng_l2tp_xmit_ctrl(priv, m, ns);
1427                 ns++;
1428         }
1429 }
1430
1431 /*
1432  * Handle an ack timeout. We have an outstanding ack that we
1433  * were hoping to piggy-back, but haven't, so send a ZLB.
1434  */
1435 static void
1436 ng_l2tp_seq_xack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1437 {
1438         const priv_p priv = NG_NODE_PRIVATE(node);
1439         struct l2tp_seq *const seq = &priv->seq;
1440
1441         /* Make sure callout is still active before doing anything */
1442         if (callout_pending(&seq->xack_timer) ||
1443             (!callout_active(&seq->xack_timer)))
1444                 return;
1445
1446         /* Sanity check */
1447         L2TP_SEQ_CHECK(seq);
1448
1449         /* Send a ZLB */
1450         ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1451
1452         /* callout_deactivate() is not needed here
1453             as ng_uncallout() was called by ng_l2tp_xmit_ctrl() */
1454
1455         /* Sanity check */
1456         L2TP_SEQ_CHECK(seq);
1457 }
1458
1459 /*
1460  * Handle a transmit timeout. The peer has failed to respond
1461  * with an ack for our packet, so retransmit it.
1462  */
1463 static void
1464 ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1465 {
1466         const priv_p priv = NG_NODE_PRIVATE(node);
1467         struct l2tp_seq *const seq = &priv->seq;
1468         struct mbuf *m;
1469         u_int delay;
1470
1471         /* Make sure callout is still active before doing anything */
1472         if (callout_pending(&seq->rack_timer) ||
1473             (!callout_active(&seq->rack_timer)))
1474                 return;
1475
1476         /* Sanity check */
1477         L2TP_SEQ_CHECK(seq);
1478
1479         priv->stats.xmitRetransmits++;
1480
1481         /* Have we reached the retransmit limit? If so, notify owner. */
1482         if (seq->rexmits++ >= priv->conf.rexmit_max)
1483                 ng_l2tp_seq_failure(priv);
1484
1485         /* Restart timer, this time with an increased delay */
1486         delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
1487         if (delay > priv->conf.rexmit_max_to)
1488                 delay = priv->conf.rexmit_max_to;
1489         ng_callout(&seq->rack_timer, node, NULL,
1490             hz * delay, ng_l2tp_seq_rack_timeout, NULL, 0);
1491
1492         /* Do slow-start/congestion algorithm windowing algorithm */
1493         seq->ns = seq->rack;
1494         seq->ssth = (seq->cwnd + 1) / 2;
1495         seq->cwnd = 1;
1496         seq->acks = 0;
1497
1498         /* Retransmit oldest unack'd packet */
1499         if ((m = L2TP_COPY_MBUF(seq->xwin[0], M_DONTWAIT)) == NULL)
1500                 priv->stats.memoryFailures++;
1501         else
1502                 ng_l2tp_xmit_ctrl(priv, m, seq->ns++);
1503
1504         /* callout_deactivate() is not needed here
1505             as ng_callout() is getting called each time */
1506
1507         /* Sanity check */
1508         L2TP_SEQ_CHECK(seq);
1509 }
1510
1511 /*
1512  * Transmit a control stream packet, payload optional.
1513  * The transmit sequence number is not incremented.
1514  */
1515 static int
1516 ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns)
1517 {
1518         struct l2tp_seq *const seq = &priv->seq;
1519         u_int16_t session_id = 0;
1520         int error;
1521
1522         mtx_lock(&seq->mtx);
1523
1524         /* Stop ack timer: we're sending an ack with this packet.
1525            Doing this before to keep state predictable after error. */
1526         if (callout_active(&seq->xack_timer))
1527                 ng_uncallout(&seq->xack_timer, priv->node);
1528
1529         seq->xack = seq->nr;
1530
1531         mtx_unlock(&seq->mtx);
1532
1533         /* If no mbuf passed, send an empty packet (ZLB) */
1534         if (m == NULL) {
1535
1536                 /* Create a new mbuf for ZLB packet */
1537                 MGETHDR(m, M_DONTWAIT, MT_DATA);
1538                 if (m == NULL) {
1539                         priv->stats.memoryFailures++;
1540                         return (ENOBUFS);
1541                 }
1542                 m->m_len = m->m_pkthdr.len = 12;
1543                 m->m_pkthdr.rcvif = NULL;
1544                 priv->stats.xmitZLBs++;
1545         } else {
1546
1547                 /* Strip off session ID */
1548                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
1549                         priv->stats.memoryFailures++;
1550                         return (ENOBUFS);
1551                 }
1552                 memcpy(&session_id, mtod(m, u_int16_t *), 2);
1553                 m_adj(m, 2);
1554
1555                 /* Make room for L2TP header */
1556                 M_PREPEND(m, 12, M_DONTWAIT);
1557                 if (m == NULL) {
1558                         priv->stats.memoryFailures++;
1559                         return (ENOBUFS);
1560                 }
1561         }
1562
1563         /* Fill in L2TP header */
1564         mtod(m, u_int16_t *)[0] = htons(L2TP_CTRL_HDR);
1565         mtod(m, u_int16_t *)[1] = htons(m->m_pkthdr.len);
1566         mtod(m, u_int16_t *)[2] = priv->conf.peer_id;
1567         mtod(m, u_int16_t *)[3] = session_id;
1568         mtod(m, u_int16_t *)[4] = htons(ns);
1569         mtod(m, u_int16_t *)[5] = htons(seq->nr);
1570
1571         /* Update sequence number info and stats */
1572         priv->stats.xmitPackets++;
1573         priv->stats.xmitOctets += m->m_pkthdr.len;
1574
1575         /* Send packet */
1576         NG_SEND_DATA_ONLY(error, priv->lower, m);
1577         return (error);
1578 }
1579
1580 #ifdef INVARIANTS
1581 /*
1582  * Sanity check sequence number state.
1583  */
1584 static void
1585 ng_l2tp_seq_check(struct l2tp_seq *seq)
1586 {
1587         int self_unack, peer_unack;
1588         int i;
1589
1590 #define CHECK(p)        KASSERT((p), ("%s: not: %s", __func__, #p))
1591
1592         mtx_lock(&seq->mtx);
1593
1594         self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack);
1595         peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack);
1596         CHECK(seq->wmax <= L2TP_MAX_XWIN);
1597         CHECK(seq->cwnd >= 1);
1598         CHECK(seq->cwnd <= seq->wmax);
1599         CHECK(seq->ssth >= 1);
1600         CHECK(seq->ssth <= seq->wmax);
1601         if (seq->cwnd < seq->ssth)
1602                 CHECK(seq->acks == 0);
1603         else
1604                 CHECK(seq->acks <= seq->cwnd);
1605         CHECK(self_unack >= 0);
1606         CHECK(peer_unack >= 0);
1607         CHECK(peer_unack <= seq->wmax);
1608         CHECK((self_unack == 0) ^ callout_active(&seq->xack_timer));
1609         CHECK((peer_unack == 0) ^ callout_active(&seq->rack_timer));
1610         for (i = 0; i < peer_unack; i++)
1611                 CHECK(seq->xwin[i] != NULL);
1612         for ( ; i < seq->cwnd; i++)         /* verify peer's recv window full */
1613                 CHECK(seq->xwin[i] == NULL);
1614
1615         mtx_unlock(&seq->mtx);
1616
1617 #undef CHECK
1618 }
1619 #endif  /* INVARIANTS */