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  * $DragonFly: src/sys/netgraph7/ng_l2tp.c,v 1.2 2008/06/26 23:05:35 dillon Exp $
  41  */
  42
  43 /*
  44  * L2TP netgraph node type.
  45  *
  46  * This node type implements the lower layer of the
  47  * L2TP protocol as specified in RFC 2661.
  48  */
  49
  50 #include <sys/param.h>
  51 #include <sys/systm.h>
  52 #include <sys/kernel.h>
  53 #include <sys/time.h>
  54 #include <sys/conf.h>
  55 #include <sys/mbuf.h>
  56 #include <sys/malloc.h>
  57 #include <sys/errno.h>
  58 #include <sys/libkern.h>
  59
  60 #include "ng_message.h"
  61 #include "netgraph.h"
  62 #include "ng_parse.h"
  63 #include "ng_l2tp.h"
  64
  65 #ifdef NG_SEPARATE_MALLOC
  66 MALLOC_DEFINE(M_NETGRAPH_L2TP, "netgraph_l2tp", "netgraph l2tp node");
  67 #else
  68 #define M_NETGRAPH_L2TP M_NETGRAPH
  69 #endif
  70
  71 /* L2TP header format (first 2 bytes only) */
  72 #define L2TP_HDR_CTRL           0x8000                  /* control packet */
  73 #define L2TP_HDR_LEN            0x4000                  /* has length field */
  74 #define L2TP_HDR_SEQ            0x0800                  /* has ns, nr fields */
  75 #define L2TP_HDR_OFF            0x0200                  /* has offset field */
  76 #define L2TP_HDR_PRIO           0x0100                  /* give priority */
  77 #define L2TP_HDR_VERS_MASK      0x000f                  /* version field mask */
  78 #define L2TP_HDR_VERSION        0x0002                  /* version field */
  79
  80 /* Bits that must be zero or one in first two bytes of header */
  81 #define L2TP_CTRL_0BITS         0x030d                  /* ctrl: must be 0 */
  82 #define L2TP_CTRL_1BITS         0xc802                  /* ctrl: must be 1 */
  83 #define L2TP_DATA_0BITS         0x800d                  /* data: must be 0 */
  84 #define L2TP_DATA_1BITS         0x0002                  /* data: must be 1 */
  85
  86 /* Standard xmit ctrl and data header bits */
  87 #define L2TP_CTRL_HDR           (L2TP_HDR_CTRL | L2TP_HDR_LEN \
  88                                     | L2TP_HDR_SEQ | L2TP_HDR_VERSION)
  89 #define L2TP_DATA_HDR           (L2TP_HDR_VERSION)      /* optional: len, seq */
  90
  91 /* Some hard coded values */
  92 #define L2TP_MAX_XWIN           128                     /* my max xmit window */
  93 #define L2TP_MAX_REXMIT         5                       /* default max rexmit */
  94 #define L2TP_MAX_REXMIT_TO      30                      /* default rexmit to */
  95 #define L2TP_DELAYED_ACK        ((hz + 19) / 20)        /* delayed ack: 50 ms */
  96
  97 /* Default data sequence number configuration for new sessions */
  98 #define L2TP_CONTROL_DSEQ       1                       /* we are the lns */
  99 #define L2TP_ENABLE_DSEQ        1                       /* enable data seq # */
 100
 101 /* Compare sequence numbers using circular math */
 102 #define L2TP_SEQ_DIFF(x, y)     ((int)((int16_t)(x) - (int16_t)(y)))
 103
 104 #define SESSHASHSIZE            0x0020
 105 #define SESSHASH(x)             (((x) ^ ((x) >> 8)) & (SESSHASHSIZE - 1))
 106
 107 /* Hook private data (data session hooks only) */
 108 struct ng_l2tp_hook_private {
 109         struct ng_l2tp_sess_config      conf;   /* hook/session config */
 110         struct ng_l2tp_session_stats    stats;  /* per sessions statistics */
 111         hook_p                          hook;   /* hook reference */
 112         u_int16_t                       ns;     /* data ns sequence number */
 113         u_int16_t                       nr;     /* data nr sequence number */
 114         LIST_ENTRY(ng_l2tp_hook_private) sessions;
 115 };
 116 typedef struct ng_l2tp_hook_private *hookpriv_p;
 117
 118 /*
 119  * Sequence number state
 120  *
 121  * Invariants:
 122  *    - If cwnd < ssth, we're doing slow start, otherwise congestion avoidance
 123  *    - The number of unacknowledged xmit packets is (ns - rack) <= seq->wmax
 124  *    - The first (ns - rack) mbuf's in xwin[] array are copies of these
 125  *      unacknowledged packets; the remainder of xwin[] consists first of
 126  *      zero or more further untransmitted packets in the transmit queue
 127  *    - We try to keep the peer's receive window as full as possible.
 128  *      Therefore, (i < cwnd && xwin[i] != NULL) implies (ns - rack) > i.
 129  *    - rack_timer is running iff (ns - rack) > 0 (unack'd xmit'd pkts)
 130  *    - If xack != nr, there are unacknowledged recv packet(s) (delayed ack)
 131  *    - xack_timer is running iff xack != nr (unack'd rec'd pkts)
 132  */
 133 struct l2tp_seq {
 134         u_int16_t               ns;             /* next xmit seq we send */
 135         u_int16_t               nr;             /* next recv seq we expect */
 136         u_int16_t               inproc;         /* packet is in processing */
 137         u_int16_t               rack;           /* last 'nr' we rec'd */
 138         u_int16_t               xack;           /* last 'nr' we sent */
 139         u_int16_t               wmax;           /* peer's max recv window */
 140         u_int16_t               cwnd;           /* current congestion window */
 141         u_int16_t               ssth;           /* slow start threshold */
 142         u_int16_t               acks;           /* # consecutive acks rec'd */
 143         u_int16_t               rexmits;        /* # retransmits sent */
 144         struct callout          rack_timer;     /* retransmit timer */
 145         struct callout          xack_timer;     /* delayed ack timer */
 146         struct mbuf             *xwin[L2TP_MAX_XWIN];   /* transmit window */
 147         struct mtx              mtx;                    /* seq mutex */
 148 };
 149
 150 /* Node private data */
 151 struct ng_l2tp_private {
 152         node_p                  node;           /* back pointer to node */
 153         hook_p                  ctrl;           /* hook to upper layers */
 154         hook_p                  lower;          /* hook to lower layers */
 155         struct ng_l2tp_config   conf;           /* node configuration */
 156         struct ng_l2tp_stats    stats;          /* node statistics */
 157         struct l2tp_seq         seq;            /* ctrl sequence number state */
 158         ng_ID_t                 ftarget;        /* failure message target */
 159         LIST_HEAD(, ng_l2tp_hook_private) sesshash[SESSHASHSIZE];
 160 };
 161 typedef struct ng_l2tp_private *priv_p;
 162
 163 /* Netgraph node methods */
 164 static ng_constructor_t ng_l2tp_constructor;
 165 static ng_rcvmsg_t      ng_l2tp_rcvmsg;
 166 static ng_shutdown_t    ng_l2tp_shutdown;
 167 static ng_newhook_t     ng_l2tp_newhook;
 168 static ng_rcvdata_t     ng_l2tp_rcvdata;
 169 static ng_rcvdata_t     ng_l2tp_rcvdata_lower;
 170 static ng_rcvdata_t     ng_l2tp_rcvdata_ctrl;
 171 static ng_disconnect_t  ng_l2tp_disconnect;
 172
 173 /* Internal functions */
 174 static int      ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns);
 175
 176 static void     ng_l2tp_seq_init(priv_p priv);
 177 static int      ng_l2tp_seq_set(priv_p priv,
 178                         const struct ng_l2tp_seq_config *conf);
 179 static int      ng_l2tp_seq_adjust(priv_p priv,
 180                         const struct ng_l2tp_config *conf);
 181 static void     ng_l2tp_seq_reset(priv_p priv);
 182 static void     ng_l2tp_seq_failure(priv_p priv);
 183 static void     ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr);
 184 static void     ng_l2tp_seq_xack_timeout(node_p node, hook_p hook,
 185                     void *arg1, int arg2);
 186 static void     ng_l2tp_seq_rack_timeout(node_p node, hook_p hook,
 187                     void *arg1, int arg2);
 188
 189 static hookpriv_p       ng_l2tp_find_session(priv_p privp, u_int16_t sid);
 190 static ng_fn_eachhook   ng_l2tp_reset_session;
 191
 192 #ifdef INVARIANTS
 193 static void     ng_l2tp_seq_check(struct l2tp_seq *seq);
 194 #endif
 195
 196 /* Parse type for struct ng_l2tp_seq_config. */
 197 static const struct ng_parse_struct_field
 198         ng_l2tp_seq_config_fields[] = NG_L2TP_SEQ_CONFIG_TYPE_INFO;
 199 static const struct ng_parse_type ng_l2tp_seq_config_type = {
 200         &ng_parse_struct_type,
 201         &ng_l2tp_seq_config_fields
 202 };
 203
 204 /* Parse type for struct ng_l2tp_config */
 205 static const struct ng_parse_struct_field
 206         ng_l2tp_config_type_fields[] = NG_L2TP_CONFIG_TYPE_INFO;
 207 static const struct ng_parse_type ng_l2tp_config_type = {
 208         &ng_parse_struct_type,
 209         &ng_l2tp_config_type_fields,
 210 };
 211
 212 /* Parse type for struct ng_l2tp_sess_config */
 213 static const struct ng_parse_struct_field
 214         ng_l2tp_sess_config_type_fields[] = NG_L2TP_SESS_CONFIG_TYPE_INFO;
 215 static const struct ng_parse_type ng_l2tp_sess_config_type = {
 216         &ng_parse_struct_type,
 217         &ng_l2tp_sess_config_type_fields,
 218 };
 219
 220 /* Parse type for struct ng_l2tp_stats */
 221 static const struct ng_parse_struct_field
 222         ng_l2tp_stats_type_fields[] = NG_L2TP_STATS_TYPE_INFO;
 223 static const struct ng_parse_type ng_l2tp_stats_type = {
 224         &ng_parse_struct_type,
 225         &ng_l2tp_stats_type_fields
 226 };
 227
 228 /* Parse type for struct ng_l2tp_session_stats. */
 229 static const struct ng_parse_struct_field
 230         ng_l2tp_session_stats_type_fields[] = NG_L2TP_SESSION_STATS_TYPE_INFO;
 231 static const struct ng_parse_type ng_l2tp_session_stats_type = {
 232         &ng_parse_struct_type,
 233         &ng_l2tp_session_stats_type_fields
 234 };
 235
 236 /* List of commands and how to convert arguments to/from ASCII */
 237 static const struct ng_cmdlist ng_l2tp_cmdlist[] = {
 238         {
 239           NGM_L2TP_COOKIE,
 240           NGM_L2TP_SET_CONFIG,
 241           "setconfig",
 242           &ng_l2tp_config_type,
 243           NULL
 244         },
 245         {
 246           NGM_L2TP_COOKIE,
 247           NGM_L2TP_GET_CONFIG,
 248           "getconfig",
 249           NULL,
 250           &ng_l2tp_config_type
 251         },
 252         {
 253           NGM_L2TP_COOKIE,
 254           NGM_L2TP_SET_SESS_CONFIG,
 255           "setsessconfig",
 256           &ng_l2tp_sess_config_type,
 257           NULL
 258         },
 259         {
 260           NGM_L2TP_COOKIE,
 261           NGM_L2TP_GET_SESS_CONFIG,
 262           "getsessconfig",
 263           &ng_parse_hint16_type,
 264           &ng_l2tp_sess_config_type
 265         },
 266         {
 267           NGM_L2TP_COOKIE,
 268           NGM_L2TP_GET_STATS,
 269           "getstats",
 270           NULL,
 271           &ng_l2tp_stats_type
 272         },
 273         {
 274           NGM_L2TP_COOKIE,
 275           NGM_L2TP_CLR_STATS,
 276           "clrstats",
 277           NULL,
 278           NULL
 279         },
 280         {
 281           NGM_L2TP_COOKIE,
 282           NGM_L2TP_GETCLR_STATS,
 283           "getclrstats",
 284           NULL,
 285           &ng_l2tp_stats_type
 286         },
 287         {
 288           NGM_L2TP_COOKIE,
 289           NGM_L2TP_GET_SESSION_STATS,
 290           "getsessstats",
 291           &ng_parse_int16_type,
 292           &ng_l2tp_session_stats_type
 293         },
 294         {
 295           NGM_L2TP_COOKIE,
 296           NGM_L2TP_CLR_SESSION_STATS,
 297           "clrsessstats",
 298           &ng_parse_int16_type,
 299           NULL
 300         },
 301         {
 302           NGM_L2TP_COOKIE,
 303           NGM_L2TP_GETCLR_SESSION_STATS,
 304           "getclrsessstats",
 305           &ng_parse_int16_type,
 306           &ng_l2tp_session_stats_type
 307         },
 308         {
 309           NGM_L2TP_COOKIE,
 310           NGM_L2TP_ACK_FAILURE,
 311           "ackfailure",
 312           NULL,
 313           NULL
 314         },
 315         {
 316           NGM_L2TP_COOKIE,
 317           NGM_L2TP_SET_SEQ,
 318           "setsequence",
 319           &ng_l2tp_seq_config_type,
 320           NULL
 321         },
 322         { 0 }
 323 };
 324
 325 /* Node type descriptor */
 326 static struct ng_type ng_l2tp_typestruct = {
 327         .version =      NG_ABI_VERSION,
 328         .name =         NG_L2TP_NODE_TYPE,
 329         .constructor =  ng_l2tp_constructor,
 330         .rcvmsg =       ng_l2tp_rcvmsg,
 331         .shutdown =     ng_l2tp_shutdown,
 332         .newhook =      ng_l2tp_newhook,
 333         .rcvdata =      ng_l2tp_rcvdata,
 334         .disconnect =   ng_l2tp_disconnect,
 335         .cmdlist =      ng_l2tp_cmdlist,
 336 };
 337 NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct);
 338
 339 /* Sequence number state sanity checking */
 340 #ifdef INVARIANTS
 341 #define L2TP_SEQ_CHECK(seq)     ng_l2tp_seq_check(seq)
 342 #else
 343 #define L2TP_SEQ_CHECK(x)       do { } while (0)
 344 #endif
 345
 346 /* memmove macro */
 347 #define memmove(d, s, l)        bcopy(s, d, l)
 348
 349 /* Whether to use m_copypacket() or m_dup() */
 350 #define L2TP_COPY_MBUF          m_copypacket
 351
 352 #define ERROUT(x)       do { error = (x); goto done; } while (0)
 353
 354 /************************************************************************
 355                         NETGRAPH NODE STUFF
 356 ************************************************************************/
 357
 358 /*
 359  * Node type constructor
 360  */
 361 static int
 362 ng_l2tp_constructor(node_p node)
 363 {
 364         priv_p priv;
 365         int     i;
 366
 367         /* Allocate private structure */
 368         MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH_L2TP, M_WAITOK | M_NULLOK | M_ZERO);
 369         if (priv == NULL)
 370                 return (ENOMEM);
 371         NG_NODE_SET_PRIVATE(node, priv);
 372         priv->node = node;
 373
 374         /* Apply a semi-reasonable default configuration */
 375         priv->conf.peer_win = 1;
 376         priv->conf.rexmit_max = L2TP_MAX_REXMIT;
 377         priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO;
 378
 379         /* Initialize sequence number state */
 380         ng_l2tp_seq_init(priv);
 381
 382         for (i = 0; i < SESSHASHSIZE; i++)
 383             LIST_INIT(&priv->sesshash[i]);
 384
 385         /* Done */
 386         return (0);
 387 }
 388
 389 /*
 390  * Give our OK for a hook to be added.
 391  */
 392 static int
 393 ng_l2tp_newhook(node_p node, hook_p hook, const char *name)
 394 {
 395         const priv_p priv = NG_NODE_PRIVATE(node);
 396
 397         /* Check hook name */
 398         if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) {
 399                 if (priv->ctrl != NULL)
 400                         return (EISCONN);
 401                 priv->ctrl = hook;
 402                 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_ctrl);
 403         } else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) {
 404                 if (priv->lower != NULL)
 405                         return (EISCONN);
 406                 priv->lower = hook;
 407                 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_lower);
 408         } else {
 409                 static const char hexdig[16] = "0123456789abcdef";
 410                 u_int16_t session_id;
 411                 hookpriv_p hpriv;
 412                 uint16_t hash;
 413                 const char *hex;
 414                 int i;
 415                 int j;
 416
 417                 /* Parse hook name to get session ID */
 418                 if (strncmp(name, NG_L2TP_HOOK_SESSION_P,
 419                     sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0)
 420                         return (EINVAL);
 421                 hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1;
 422                 for (session_id = i = 0; i < 4; i++) {
 423                         for (j = 0; j < 16 && hex[i] != hexdig[j]; j++);
 424                         if (j == 16)
 425                                 return (EINVAL);
 426                         session_id = (session_id << 4) | j;
 427                 }
 428                 if (hex[i] != '\0')
 429                         return (EINVAL);
 430
 431                 /* Create hook private structure */
 432                 MALLOC(hpriv, hookpriv_p,
 433                     sizeof(*hpriv), M_NETGRAPH_L2TP, M_WAITOK | M_NULLOK | M_ZERO);
 434                 if (hpriv == NULL)
 435                         return (ENOMEM);
 436                 hpriv->conf.session_id = htons(session_id);
 437                 hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ;
 438                 hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ;
 439                 hpriv->hook = hook;
 440                 NG_HOOK_SET_PRIVATE(hook, hpriv);
 441                 hash = SESSHASH(hpriv->conf.session_id);
 442                 LIST_INSERT_HEAD(&priv->sesshash[hash], hpriv, sessions);
 443         }
 444
 445         /* Done */
 446         return (0);
 447 }
 448
 449 /*
 450  * Receive a control message.
 451  */
 452 static int
 453 ng_l2tp_rcvmsg(node_p node, item_p item, hook_p lasthook)
 454 {
 455         const priv_p priv = NG_NODE_PRIVATE(node);
 456         struct ng_mesg *resp = NULL;
 457         struct ng_mesg *msg;
 458         int error = 0;
 459
 460         NGI_GET_MSG(item, msg);
 461         switch (msg->header.typecookie) {
 462         case NGM_L2TP_COOKIE:
 463                 switch (msg->header.cmd) {
 464                 case NGM_L2TP_SET_CONFIG:
 465                     {
 466                         struct ng_l2tp_config *const conf =
 467                                 (struct ng_l2tp_config *)msg->data;
 468
 469                         /* Check for invalid or illegal config */
 470                         if (msg->header.arglen != sizeof(*conf)) {
 471                                 error = EINVAL;
 472                                 break;
 473                         }
 474                         conf->enabled = !!conf->enabled;
 475                         conf->match_id = !!conf->match_id;
 476                         conf->tunnel_id = htons(conf->tunnel_id);
 477                         conf->peer_id = htons(conf->peer_id);
 478                         if (priv->conf.enabled
 479                             && ((priv->conf.tunnel_id != 0
 480                                && conf->tunnel_id != priv->conf.tunnel_id)
 481                               || ((priv->conf.peer_id != 0
 482                                && conf->peer_id != priv->conf.peer_id)))) {
 483                                 error = EBUSY;
 484                                 break;
 485                         }
 486
 487                         /* Save calling node as failure target */
 488                         priv->ftarget = NGI_RETADDR(item);
 489
 490                         /* Adjust sequence number state */
 491                         if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0)
 492                                 break;
 493
 494                         /* Update node's config */
 495                         priv->conf = *conf;
 496                         break;
 497                     }
 498                 case NGM_L2TP_GET_CONFIG:
 499                     {
 500                         struct ng_l2tp_config *conf;
 501
 502                         NG_MKRESPONSE(resp, msg, sizeof(*conf), M_WAITOK | M_NULLOK);
 503                         if (resp == NULL) {
 504                                 error = ENOMEM;
 505                                 break;
 506                         }
 507                         conf = (struct ng_l2tp_config *)resp->data;
 508                         *conf = priv->conf;
 509
 510                         /* Put ID's in host order */
 511                         conf->tunnel_id = ntohs(conf->tunnel_id);
 512                         conf->peer_id = ntohs(conf->peer_id);
 513                         break;
 514                     }
 515                 case NGM_L2TP_SET_SESS_CONFIG:
 516                     {
 517                         struct ng_l2tp_sess_config *const conf =
 518                             (struct ng_l2tp_sess_config *)msg->data;
 519                         hookpriv_p hpriv;
 520
 521                         /* Check for invalid or illegal config. */
 522                         if (msg->header.arglen != sizeof(*conf)) {
 523                                 error = EINVAL;
 524                                 break;
 525                         }
 526
 527                         /* Put ID's in network order */
 528                         conf->session_id = htons(conf->session_id);
 529                         conf->peer_id = htons(conf->peer_id);
 530
 531                         /* Find matching hook */
 532                         hpriv = ng_l2tp_find_session(priv, conf->session_id);
 533                         if (hpriv == NULL) {
 534                                 error = ENOENT;
 535                                 break;
 536                         }
 537
 538                         /* Update hook's config */
 539                         hpriv->conf = *conf;
 540                         break;
 541                     }
 542                 case NGM_L2TP_GET_SESS_CONFIG:
 543                     {
 544                         struct ng_l2tp_sess_config *conf;
 545                         u_int16_t session_id;
 546                         hookpriv_p hpriv;
 547
 548                         /* Get session ID */
 549                         if (msg->header.arglen != sizeof(session_id)) {
 550                                 error = EINVAL;
 551                                 break;
 552                         }
 553                         memcpy(&session_id, msg->data, 2);
 554                         session_id = htons(session_id);
 555
 556                         /* Find matching hook */
 557                         hpriv = ng_l2tp_find_session(priv, session_id);
 558                         if (hpriv == NULL) {
 559                                 error = ENOENT;
 560                                 break;
 561                         }
 562
 563                         /* Send response */
 564                         NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_WAITOK | M_NULLOK);
 565                         if (resp == NULL) {
 566                                 error = ENOMEM;
 567                                 break;
 568                         }
 569                         conf = (struct ng_l2tp_sess_config *)resp->data;
 570                         *conf = hpriv->conf;
 571
 572                         /* Put ID's in host order */
 573                         conf->session_id = ntohs(conf->session_id);
 574                         conf->peer_id = ntohs(conf->peer_id);
 575                         break;
 576                     }
 577                 case NGM_L2TP_GET_STATS:
 578                 case NGM_L2TP_CLR_STATS:
 579                 case NGM_L2TP_GETCLR_STATS:
 580                     {
 581                         if (msg->header.cmd != NGM_L2TP_CLR_STATS) {
 582                                 NG_MKRESPONSE(resp, msg,
 583                                     sizeof(priv->stats), M_WAITOK | M_NULLOK);
 584                                 if (resp == NULL) {
 585                                         error = ENOMEM;
 586                                         break;
 587                                 }
 588                                 memcpy(resp->data,
 589                                     &priv->stats, sizeof(priv->stats));
 590                         }
 591                         if (msg->header.cmd != NGM_L2TP_GET_STATS)
 592                                 memset(&priv->stats, 0, sizeof(priv->stats));
 593                         break;
 594                     }
 595                 case NGM_L2TP_GET_SESSION_STATS:
 596                 case NGM_L2TP_CLR_SESSION_STATS:
 597                 case NGM_L2TP_GETCLR_SESSION_STATS:
 598                     {
 599                         uint16_t session_id;
 600                         hookpriv_p hpriv;
 601
 602                         /* Get session ID. */
 603                         if (msg->header.arglen != sizeof(session_id)) {
 604                                 error = EINVAL;
 605                                 break;
 606                         }
 607                         bcopy(msg->data, &session_id, sizeof(uint16_t));
 608                         session_id = htons(session_id);
 609
 610                         /* Find matching hook. */
 611                         hpriv = ng_l2tp_find_session(priv, session_id);
 612                         if (hpriv == NULL) {
 613                                 error = ENOENT;
 614                                 break;
 615                         }
 616
 617                         if (msg->header.cmd != NGM_L2TP_CLR_SESSION_STATS) {
 618                                 NG_MKRESPONSE(resp, msg,
 619                                     sizeof(hpriv->stats), M_WAITOK | M_NULLOK);
 620                                 if (resp == NULL) {
 621                                         error = ENOMEM;
 622                                         break;
 623                                 }
 624                                 bcopy(&hpriv->stats, resp->data,
 625                                         sizeof(hpriv->stats));
 626                         }
 627                         if (msg->header.cmd != NGM_L2TP_GET_SESSION_STATS)
 628                                 bzero(&hpriv->stats, sizeof(hpriv->stats));
 629                         break;
 630                     }
 631                 case NGM_L2TP_SET_SEQ:
 632                     {
 633                         struct ng_l2tp_seq_config *const conf =
 634                                 (struct ng_l2tp_seq_config *)msg->data;
 635
 636                         /* Check for invalid or illegal seq config. */
 637                         if (msg->header.arglen != sizeof(*conf)) {
 638                                 error = EINVAL;
 639                                 break;
 640                         }
 641                         conf->ns = htons(conf->ns);
 642                         conf->nr = htons(conf->nr);
 643                         conf->rack = htons(conf->rack);
 644                         conf->xack = htons(conf->xack);
 645
 646                         /* Set sequence numbers. */
 647                         error = ng_l2tp_seq_set(priv, conf);
 648                         break;
 649                     }
 650                 default:
 651                         error = EINVAL;
 652                         break;
 653                 }
 654                 break;
 655         default:
 656                 error = EINVAL;
 657                 break;
 658         }
 659
 660         /* Done */
 661         NG_RESPOND_MSG(error, node, item, resp);
 662         NG_FREE_MSG(msg);
 663         return (error);
 664 }
 665
 666 /*
 667  * Destroy node
 668  */
 669 static int
 670 ng_l2tp_shutdown(node_p node)
 671 {
 672         const priv_p priv = NG_NODE_PRIVATE(node);
 673         struct l2tp_seq *const seq = &priv->seq;
 674
 675         /* Sanity check */
 676         L2TP_SEQ_CHECK(seq);
 677
 678         /* Reset sequence number state */
 679         ng_l2tp_seq_reset(priv);
 680
 681         /* Free private data if neither timer is running */
 682         ng_uncallout(&seq->rack_timer, node);
 683         ng_uncallout(&seq->xack_timer, node);
 684
 685         mtx_destroy(&seq->mtx);
 686
 687         FREE(priv, M_NETGRAPH_L2TP);
 688
 689         /* Unref node */
 690         NG_NODE_UNREF(node);
 691         return (0);
 692 }
 693
 694 /*
 695  * Hook disconnection
 696  */
 697 static int
 698 ng_l2tp_disconnect(hook_p hook)
 699 {
 700         const node_p node = NG_HOOK_NODE(hook);
 701         const priv_p priv = NG_NODE_PRIVATE(node);
 702
 703         /* Zero out hook pointer */
 704         if (hook == priv->ctrl)
 705                 priv->ctrl = NULL;
 706         else if (hook == priv->lower)
 707                 priv->lower = NULL;
 708         else {
 709                 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
 710                 LIST_REMOVE(hpriv, sessions);
 711                 FREE(hpriv, M_NETGRAPH_L2TP);
 712                 NG_HOOK_SET_PRIVATE(hook, NULL);
 713         }
 714
 715         /* Go away if no longer connected to anything */
 716         if (NG_NODE_NUMHOOKS(node) == 0 && NG_NODE_IS_VALID(node))
 717                 ng_rmnode_self(node);
 718         return (0);
 719 }
 720
 721 /*************************************************************************
 722                         INTERNAL FUNCTIONS
 723 *************************************************************************/
 724
 725 /*
 726  * Find the hook with a given session ID (in network order).
 727  */
 728 static hookpriv_p
 729 ng_l2tp_find_session(priv_p privp, u_int16_t sid)
 730 {
 731         uint16_t        hash = SESSHASH(sid);
 732         hookpriv_p      hpriv = NULL;
 733
 734         LIST_FOREACH(hpriv, &privp->sesshash[hash], sessions) {
 735                 if (hpriv->conf.session_id == sid)
 736                         break;
 737         }
 738
 739         return (hpriv);
 740 }
 741
 742 /*
 743  * Reset a hook's session state.
 744  */
 745 static int
 746 ng_l2tp_reset_session(hook_p hook, void *arg)
 747 {
 748         const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
 749
 750         if (hpriv != NULL) {
 751                 hpriv->conf.control_dseq = 0;
 752                 hpriv->conf.enable_dseq = 0;
 753                 bzero(&hpriv->conf, sizeof(struct ng_l2tp_session_stats));
 754                 hpriv->nr = 0;
 755                 hpriv->ns = 0;
 756         }
 757         return (-1);
 758 }
 759
 760 /*
 761  * Handle an incoming frame from below.
 762  */
 763 static int
 764 ng_l2tp_rcvdata_lower(hook_p h, item_p item)
 765 {
 766         static const u_int16_t req_bits[2][2] = {
 767                 { L2TP_DATA_0BITS, L2TP_DATA_1BITS },
 768                 { L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
 769         };
 770         const node_p node = NG_HOOK_NODE(h);
 771         const priv_p priv = NG_NODE_PRIVATE(node);
 772         hookpriv_p hpriv = NULL;
 773         hook_p hook = NULL;
 774         u_int16_t ids[2];
 775         struct mbuf *m;
 776         u_int16_t hdr;
 777         u_int16_t ns;
 778         u_int16_t nr;
 779         int is_ctrl;
 780         int error;
 781         int len, plen;
 782
 783         /* Sanity check */
 784         L2TP_SEQ_CHECK(&priv->seq);
 785
 786         /* If not configured, reject */
 787         if (!priv->conf.enabled) {
 788                 NG_FREE_ITEM(item);
 789                 ERROUT(ENXIO);
 790         }
 791
 792         /* Grab mbuf */
 793         NGI_GET_M(item, m);
 794
 795         /* Remember full packet length; needed for per session accounting. */
 796         plen = m->m_pkthdr.len;
 797
 798         /* Update stats */
 799         priv->stats.recvPackets++;
 800         priv->stats.recvOctets += plen;
 801
 802         /* Get initial header */
 803         if (m->m_pkthdr.len < 6) {
 804                 priv->stats.recvRunts++;
 805                 NG_FREE_ITEM(item);
 806                 NG_FREE_M(m);
 807                 ERROUT(EINVAL);
 808         }
 809         if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 810                 priv->stats.memoryFailures++;
 811                 NG_FREE_ITEM(item);
 812                 ERROUT(EINVAL);
 813         }
 814         hdr = ntohs(*mtod(m, u_int16_t *));
 815         m_adj(m, 2);
 816
 817         /* Check required header bits and minimum length */
 818         is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
 819         if ((hdr & req_bits[is_ctrl][0]) != 0
 820             || (~hdr & req_bits[is_ctrl][1]) != 0) {
 821                 priv->stats.recvInvalid++;
 822                 NG_FREE_ITEM(item);
 823                 NG_FREE_M(m);
 824                 ERROUT(EINVAL);
 825         }
 826         if (m->m_pkthdr.len < 4                         /* tunnel, session id */
 827             + (2 * ((hdr & L2TP_HDR_LEN) != 0))         /* length field */
 828             + (4 * ((hdr & L2TP_HDR_SEQ) != 0))         /* seq # fields */
 829             + (2 * ((hdr & L2TP_HDR_OFF) != 0))) {      /* offset field */
 830                 priv->stats.recvRunts++;
 831                 NG_FREE_ITEM(item);
 832                 NG_FREE_M(m);
 833                 ERROUT(EINVAL);
 834         }
 835
 836         /* Get and validate length field if present */
 837         if ((hdr & L2TP_HDR_LEN) != 0) {
 838                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 839                         priv->stats.memoryFailures++;
 840                         NG_FREE_ITEM(item);
 841                         ERROUT(EINVAL);
 842                 }
 843                 len = (u_int16_t)ntohs(*mtod(m, u_int16_t *)) - 4;
 844                 m_adj(m, 2);
 845                 if (len < 0 || len > m->m_pkthdr.len) {
 846                         priv->stats.recvInvalid++;
 847                         NG_FREE_ITEM(item);
 848                         NG_FREE_M(m);
 849                         ERROUT(EINVAL);
 850                 }
 851                 if (len < m->m_pkthdr.len)              /* trim extra bytes */
 852                         m_adj(m, -(m->m_pkthdr.len - len));
 853         }
 854
 855         /* Get tunnel ID and session ID */
 856         if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
 857                 priv->stats.memoryFailures++;
 858                 NG_FREE_ITEM(item);
 859                 ERROUT(EINVAL);
 860         }
 861         memcpy(ids, mtod(m, u_int16_t *), 4);
 862         m_adj(m, 4);
 863
 864         /* Check tunnel ID */
 865         if (ids[0] != priv->conf.tunnel_id
 866             && (priv->conf.match_id || ids[0] != 0)) {
 867                 priv->stats.recvWrongTunnel++;
 868                 NG_FREE_ITEM(item);
 869                 NG_FREE_M(m);
 870                 ERROUT(EADDRNOTAVAIL);
 871         }
 872
 873         /* Check session ID (for data packets only) */
 874         if ((hdr & L2TP_HDR_CTRL) == 0) {
 875                 hpriv = ng_l2tp_find_session(priv, ids[1]);
 876                 if (hpriv == NULL) {
 877                         priv->stats.recvUnknownSID++;
 878                         NG_FREE_ITEM(item);
 879                         NG_FREE_M(m);
 880                         ERROUT(ENOTCONN);
 881                 }
 882                 hook = hpriv->hook;
 883         }
 884
 885         /* Get Ns, Nr fields if present */
 886         if ((hdr & L2TP_HDR_SEQ) != 0) {
 887                 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
 888                         priv->stats.memoryFailures++;
 889                         NG_FREE_ITEM(item);
 890                         ERROUT(EINVAL);
 891                 }
 892                 memcpy(&ns, &mtod(m, u_int16_t *)[0], 2);
 893                 ns = ntohs(ns);
 894                 memcpy(&nr, &mtod(m, u_int16_t *)[1], 2);
 895                 nr = ntohs(nr);
 896                 m_adj(m, 4);
 897         }
 898
 899         /* Strip offset padding if present */
 900         if ((hdr & L2TP_HDR_OFF) != 0) {
 901                 u_int16_t offset;
 902
 903                 /* Get length of offset padding */
 904                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 905                         priv->stats.memoryFailures++;
 906                         NG_FREE_ITEM(item);
 907                         ERROUT(EINVAL);
 908                 }
 909                 memcpy(&offset, mtod(m, u_int16_t *), 2);
 910                 offset = ntohs(offset);
 911
 912                 /* Trim offset padding */
 913                 if ((2+offset) > m->m_pkthdr.len) {
 914                         priv->stats.recvInvalid++;
 915                         NG_FREE_ITEM(item);
 916                         NG_FREE_M(m);
 917                         ERROUT(EINVAL);
 918                 }
 919                 m_adj(m, 2+offset);
 920         }
 921
 922         /* Handle control packets */
 923         if ((hdr & L2TP_HDR_CTRL) != 0) {
 924                 struct l2tp_seq *const seq = &priv->seq;
 925
 926                 /* Handle receive ack sequence number Nr */
 927                 ng_l2tp_seq_recv_nr(priv, nr);
 928
 929                 /* Discard ZLB packets */
 930                 if (m->m_pkthdr.len == 0) {
 931                         priv->stats.recvZLBs++;
 932                         NG_FREE_ITEM(item);
 933                         NG_FREE_M(m);
 934                         ERROUT(0);
 935                 }
 936
 937                 mtx_lock(&seq->mtx);
 938                 /*
 939                  * If not what we expect or we are busy, drop packet and
 940                  * send an immediate ZLB ack.
 941                  */
 942                 if (ns != seq->nr || seq->inproc) {
 943                         if (L2TP_SEQ_DIFF(ns, seq->nr) <= 0)
 944                                 priv->stats.recvDuplicates++;
 945                         else
 946                                 priv->stats.recvOutOfOrder++;
 947                         mtx_unlock(&seq->mtx);
 948                         ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
 949                         NG_FREE_ITEM(item);
 950                         NG_FREE_M(m);
 951                         ERROUT(0);
 952                 }
 953                 /*
 954                  * Until we deliver this packet we can't receive next one as
 955                  * we have no information for sending ack.
 956                  */
 957                 seq->inproc = 1;
 958                 mtx_unlock(&seq->mtx);
 959
 960                 /* Prepend session ID to packet. */
 961                 M_PREPEND(m, 2, MB_DONTWAIT);
 962                 if (m == NULL) {
 963                         seq->inproc = 0;
 964                         priv->stats.memoryFailures++;
 965                         NG_FREE_ITEM(item);
 966                         ERROUT(ENOBUFS);
 967                 }
 968                 memcpy(mtod(m, u_int16_t *), &ids[1], 2);
 969
 970                 /* Deliver packet to upper layers */
 971                 NG_FWD_NEW_DATA(error, item, priv->ctrl, m);
 972
 973                 mtx_lock(&seq->mtx);
 974                 /* Ready to process next packet. */
 975                 seq->inproc = 0;
 976
 977                 /* If packet was successfully delivered send ack. */
 978                 if (error == 0) {
 979                         /* Update recv sequence number */
 980                         seq->nr++;
 981                         /* Start receive ack timer, if not already running */
 982                         if (!callout_active(&seq->xack_timer)) {
 983                                 ng_callout(&seq->xack_timer, priv->node, NULL,
 984                                     L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout,
 985                                     NULL, 0);
 986                         }
 987                 }
 988                 mtx_unlock(&seq->mtx);
 989
 990                 ERROUT(error);
 991         }
 992
 993         /* Per session packet, account it. */
 994         hpriv->stats.recvPackets++;
 995         hpriv->stats.recvOctets += plen;
 996
 997         /* Follow peer's lead in data sequencing, if configured to do so */
 998         if (!hpriv->conf.control_dseq)
 999                 hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0);
1000
1001         /* Handle data sequence numbers if present and enabled */
1002         if ((hdr & L2TP_HDR_SEQ) != 0) {
1003                 if (hpriv->conf.enable_dseq
1004                     && L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) {
1005                         NG_FREE_ITEM(item);     /* duplicate or out of order */
1006                         NG_FREE_M(m);
1007                         priv->stats.recvDataDrops++;
1008                         ERROUT(0);
1009                 }
1010                 hpriv->nr = ns + 1;
1011         }
1012
1013         /* Drop empty data packets */
1014         if (m->m_pkthdr.len == 0) {
1015                 NG_FREE_ITEM(item);
1016                 NG_FREE_M(m);
1017                 ERROUT(0);
1018         }
1019
1020         /* Deliver data */
1021         NG_FWD_NEW_DATA(error, item, hook, m);
1022 done:
1023         /* Done */
1024         L2TP_SEQ_CHECK(&priv->seq);
1025         return (error);
1026 }
1027
1028 /*
1029  * Handle an outgoing control frame.
1030  */
1031 static int
1032 ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item)
1033 {
1034         const node_p node = NG_HOOK_NODE(hook);
1035         const priv_p priv = NG_NODE_PRIVATE(node);
1036         struct l2tp_seq *const seq = &priv->seq;
1037         struct mbuf *m;
1038         int error;
1039         int i;
1040         u_int16_t       ns;
1041
1042         /* Sanity check */
1043         L2TP_SEQ_CHECK(&priv->seq);
1044
1045         /* If not configured, reject */
1046         if (!priv->conf.enabled) {
1047                 NG_FREE_ITEM(item);
1048                 ERROUT(ENXIO);
1049         }
1050
1051         /* Grab mbuf and discard other stuff XXX */
1052         NGI_GET_M(item, m);
1053         NG_FREE_ITEM(item);
1054
1055         /* Packet should have session ID prepended */
1056         if (m->m_pkthdr.len < 2) {
1057                 priv->stats.xmitInvalid++;
1058                 m_freem(m);
1059                 ERROUT(EINVAL);
1060         }
1061
1062         /* Check max length */
1063         if (m->m_pkthdr.len >= 0x10000 - 14) {
1064                 priv->stats.xmitTooBig++;
1065                 m_freem(m);
1066                 ERROUT(EOVERFLOW);
1067         }
1068
1069         mtx_lock(&seq->mtx);
1070
1071         /* Find next empty slot in transmit queue */
1072         for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
1073         if (i == L2TP_MAX_XWIN) {
1074                 mtx_unlock(&seq->mtx);
1075                 priv->stats.xmitDrops++;
1076                 m_freem(m);
1077                 ERROUT(ENOBUFS);
1078         }
1079         seq->xwin[i] = m;
1080
1081         /* If peer's receive window is already full, nothing else to do */
1082         if (i >= seq->cwnd) {
1083                 mtx_unlock(&seq->mtx);
1084                 ERROUT(0);
1085         }
1086
1087         /* Start retransmit timer if not already running */
1088         if (!callout_active(&seq->rack_timer))
1089                 ng_callout(&seq->rack_timer, node, NULL,
1090                     hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1091
1092         ns = seq->ns++;
1093
1094         mtx_unlock(&seq->mtx);
1095
1096         /* Copy packet */
1097         if ((m = L2TP_COPY_MBUF(m, MB_DONTWAIT)) == NULL) {
1098                 priv->stats.memoryFailures++;
1099                 ERROUT(ENOBUFS);
1100         }
1101
1102         /* Send packet and increment xmit sequence number */
1103         error = ng_l2tp_xmit_ctrl(priv, m, ns);
1104 done:
1105         /* Done */
1106         L2TP_SEQ_CHECK(&priv->seq);
1107         return (error);
1108 }
1109
1110 /*
1111  * Handle an outgoing data frame.
1112  */
1113 static int
1114 ng_l2tp_rcvdata(hook_p hook, item_p item)
1115 {
1116         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
1117         const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
1118         struct mbuf *m;
1119         u_int16_t hdr;
1120         int error;
1121         int i = 1;
1122
1123         /* Sanity check */
1124         L2TP_SEQ_CHECK(&priv->seq);
1125
1126         /* If not configured, reject */
1127         if (!priv->conf.enabled) {
1128                 NG_FREE_ITEM(item);
1129                 ERROUT(ENXIO);
1130         }
1131
1132         /* Get mbuf */
1133         NGI_GET_M(item, m);
1134
1135         /* Check max length */
1136         if (m->m_pkthdr.len >= 0x10000 - 12) {
1137                 priv->stats.xmitDataTooBig++;
1138                 NG_FREE_ITEM(item);
1139                 NG_FREE_M(m);
1140                 ERROUT(EOVERFLOW);
1141         }
1142
1143         /* Prepend L2TP header */
1144         M_PREPEND(m, 6
1145             + (2 * (hpriv->conf.include_length != 0))
1146             + (4 * (hpriv->conf.enable_dseq != 0)),
1147             MB_DONTWAIT);
1148         if (m == NULL) {
1149                 priv->stats.memoryFailures++;
1150                 NG_FREE_ITEM(item);
1151                 ERROUT(ENOBUFS);
1152         }
1153         hdr = L2TP_DATA_HDR;
1154         if (hpriv->conf.include_length) {
1155                 hdr |= L2TP_HDR_LEN;
1156                 mtod(m, u_int16_t *)[i++] = htons(m->m_pkthdr.len);
1157         }
1158         mtod(m, u_int16_t *)[i++] = priv->conf.peer_id;
1159         mtod(m, u_int16_t *)[i++] = hpriv->conf.peer_id;
1160         if (hpriv->conf.enable_dseq) {
1161                 hdr |= L2TP_HDR_SEQ;
1162                 mtod(m, u_int16_t *)[i++] = htons(hpriv->ns);
1163                 mtod(m, u_int16_t *)[i++] = htons(hpriv->nr);
1164                 hpriv->ns++;
1165         }
1166         mtod(m, u_int16_t *)[0] = htons(hdr);
1167
1168         /* Update per session stats. */
1169         hpriv->stats.xmitPackets++;
1170         hpriv->stats.xmitOctets += m->m_pkthdr.len;
1171
1172         /* And the global one. */
1173         priv->stats.xmitPackets++;
1174         priv->stats.xmitOctets += m->m_pkthdr.len;
1175
1176         /* Send packet */
1177         NG_FWD_NEW_DATA(error, item, priv->lower, m);
1178 done:
1179         /* Done */
1180         L2TP_SEQ_CHECK(&priv->seq);
1181         return (error);
1182 }
1183
1184 /*
1185  * Send a message to our controlling node that we've failed.
1186  */
1187 static void
1188 ng_l2tp_seq_failure(priv_p priv)
1189 {
1190         struct ng_mesg *msg;
1191         int error;
1192
1193         NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_WAITOK | M_NULLOK);
1194         if (msg == NULL)
1195                 return;
1196         NG_SEND_MSG_ID(error, priv->node, msg, priv->ftarget, 0);
1197 }
1198
1199 /************************************************************************
1200                         SEQUENCE NUMBER HANDLING
1201 ************************************************************************/
1202
1203 /*
1204  * Initialize sequence number state.
1205  */
1206 static void
1207 ng_l2tp_seq_init(priv_p priv)
1208 {
1209         struct l2tp_seq *const seq = &priv->seq;
1210
1211         KASSERT(priv->conf.peer_win >= 1,
1212             ("%s: peer_win is zero", __func__));
1213         memset(seq, 0, sizeof(*seq));
1214         seq->cwnd = 1;
1215         seq->wmax = priv->conf.peer_win;
1216         if (seq->wmax > L2TP_MAX_XWIN)
1217                 seq->wmax = L2TP_MAX_XWIN;
1218         seq->ssth = seq->wmax;
1219         ng_callout_init(&seq->rack_timer);
1220         ng_callout_init(&seq->xack_timer);
1221         mtx_init(&seq->mtx, "ng_l2tp", NULL, MTX_DEF);
1222         L2TP_SEQ_CHECK(seq);
1223 }
1224
1225 /*
1226  * Set sequence number state as given from user.
1227  */
1228 static int
1229 ng_l2tp_seq_set(priv_p priv, const struct ng_l2tp_seq_config *conf)
1230 {
1231         struct l2tp_seq *const seq = &priv->seq;
1232
1233         /* If node is enabled, deny update to sequence numbers. */
1234         if (priv->conf.enabled)
1235                 return (EBUSY);
1236
1237         /* We only can handle the simple cases. */
1238         if (conf->xack != conf->nr || conf->ns != conf->rack)
1239                 return (EINVAL);
1240
1241         /* Set ns,nr,rack,xack parameters. */
1242         seq->ns = conf->ns;
1243         seq->nr = conf->nr;
1244         seq->rack = conf->rack;
1245         seq->xack = conf->xack;
1246
1247         return (0);
1248 }
1249
1250 /*
1251  * Adjust sequence number state accordingly after reconfiguration.
1252  */
1253 static int
1254 ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf)
1255 {
1256         struct l2tp_seq *const seq = &priv->seq;
1257         u_int16_t new_wmax;
1258
1259         /* If disabling node, reset state sequence number */
1260         if (!conf->enabled) {
1261                 ng_l2tp_seq_reset(priv);
1262                 return (0);
1263         }
1264
1265         /* Adjust peer's max recv window; it can only increase */
1266         new_wmax = conf->peer_win;
1267         if (new_wmax > L2TP_MAX_XWIN)
1268                 new_wmax = L2TP_MAX_XWIN;
1269         if (new_wmax == 0)
1270                 return (EINVAL);
1271         if (new_wmax < seq->wmax)
1272                 return (EBUSY);
1273         seq->wmax = new_wmax;
1274
1275         /* Done */
1276         return (0);
1277 }
1278
1279 /*
1280  * Reset sequence number state.
1281  */
1282 static void
1283 ng_l2tp_seq_reset(priv_p priv)
1284 {
1285         struct l2tp_seq *const seq = &priv->seq;
1286         hook_p hook;
1287         int i;
1288
1289         /* Sanity check */
1290         L2TP_SEQ_CHECK(seq);
1291
1292         /* Stop timers */
1293         ng_uncallout(&seq->rack_timer, priv->node);
1294         ng_uncallout(&seq->xack_timer, priv->node);
1295
1296         /* Free retransmit queue */
1297         for (i = 0; i < L2TP_MAX_XWIN; i++) {
1298                 if (seq->xwin[i] == NULL)
1299                         break;
1300                 m_freem(seq->xwin[i]);
1301         }
1302
1303         /* Reset session hooks' sequence number states */
1304         NG_NODE_FOREACH_HOOK(priv->node, ng_l2tp_reset_session, NULL, hook);
1305
1306         /* Reset node's sequence number state */
1307         seq->ns = 0;
1308         seq->nr = 0;
1309         seq->rack = 0;
1310         seq->xack = 0;
1311         seq->wmax = L2TP_MAX_XWIN;
1312         seq->cwnd = 1;
1313         seq->ssth = seq->wmax;
1314         seq->acks = 0;
1315         seq->rexmits = 0;
1316         bzero(seq->xwin, sizeof(seq->xwin));
1317
1318         /* Done */
1319         L2TP_SEQ_CHECK(seq);
1320 }
1321
1322 /*
1323  * Handle receipt of an acknowledgement value (Nr) from peer.
1324  */
1325 static void
1326 ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr)
1327 {
1328         struct l2tp_seq *const seq = &priv->seq;
1329         struct mbuf     *xwin[L2TP_MAX_XWIN];   /* partial local copy */
1330         int             nack;
1331         int             i, j;
1332         uint16_t        ns;
1333
1334         mtx_lock(&seq->mtx);
1335
1336         /* Verify peer's ACK is in range */
1337         if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0) {
1338                 mtx_unlock(&seq->mtx);
1339                 return;                         /* duplicate ack */
1340         }
1341         if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) {
1342                 mtx_unlock(&seq->mtx);
1343                 priv->stats.recvBadAcks++;      /* ack for packet not sent */
1344                 return;
1345         }
1346         KASSERT(nack <= L2TP_MAX_XWIN,
1347             ("%s: nack=%d > %d", __func__, nack, L2TP_MAX_XWIN));
1348
1349         /* Update receive ack stats */
1350         seq->rack = nr;
1351         seq->rexmits = 0;
1352
1353         /* Free acknowledged packets and shift up packets in the xmit queue */
1354         for (i = 0; i < nack; i++)
1355                 m_freem(seq->xwin[i]);
1356         memmove(seq->xwin, seq->xwin + nack,
1357             (L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin));
1358         memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0,
1359             nack * sizeof(*seq->xwin));
1360
1361         /*
1362          * Do slow-start/congestion avoidance windowing algorithm described
1363          * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
1364          * ACK had arrived separately.
1365          */
1366         if (seq->cwnd < seq->wmax) {
1367
1368                 /* Handle slow start phase */
1369                 if (seq->cwnd < seq->ssth) {
1370                         seq->cwnd += nack;
1371                         nack = 0;
1372                         if (seq->cwnd > seq->ssth) {    /* into cg.av. phase */
1373                                 nack = seq->cwnd - seq->ssth;
1374                                 seq->cwnd = seq->ssth;
1375                         }
1376                 }
1377
1378                 /* Handle congestion avoidance phase */
1379                 if (seq->cwnd >= seq->ssth) {
1380                         seq->acks += nack;
1381                         while (seq->acks >= seq->cwnd) {
1382                                 seq->acks -= seq->cwnd;
1383                                 if (seq->cwnd < seq->wmax)
1384                                         seq->cwnd++;
1385                         }
1386                 }
1387         }
1388
1389         /* Stop xmit timer */
1390         if (callout_active(&seq->rack_timer))
1391                 ng_uncallout(&seq->rack_timer, priv->node);
1392
1393         /* If transmit queue is empty, we're done for now */
1394         if (seq->xwin[0] == NULL) {
1395                 mtx_unlock(&seq->mtx);
1396                 return;
1397         }
1398
1399         /* Start restransmit timer again */
1400         ng_callout(&seq->rack_timer, priv->node, NULL,
1401             hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1402
1403         /*
1404          * Send more packets, trying to keep peer's receive window full.
1405          * Make copy of everything we need before lock release.
1406          */
1407         ns = seq->ns;
1408         j = 0;
1409         while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd
1410             && seq->xwin[i] != NULL) {
1411                 xwin[j++] = seq->xwin[i];
1412                 seq->ns++;
1413         }
1414
1415         mtx_unlock(&seq->mtx);
1416
1417         /*
1418          * Send prepared.
1419          * If there is a memory error, pretend packet was sent, as it
1420          * will get retransmitted later anyway.
1421          */
1422         for (i = 0; i < j; i++) {
1423                 struct mbuf     *m;
1424                 if ((m = L2TP_COPY_MBUF(xwin[i], MB_DONTWAIT)) == NULL)
1425                         priv->stats.memoryFailures++;
1426                 else
1427                         ng_l2tp_xmit_ctrl(priv, m, ns);
1428                 ns++;
1429         }
1430 }
1431
1432 /*
1433  * Handle an ack timeout. We have an outstanding ack that we
1434  * were hoping to piggy-back, but haven't, so send a ZLB.
1435  */
1436 static void
1437 ng_l2tp_seq_xack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1438 {
1439         const priv_p priv = NG_NODE_PRIVATE(node);
1440         struct l2tp_seq *const seq = &priv->seq;
1441
1442         /* Make sure callout is still active before doing anything */
1443         if (callout_pending(&seq->xack_timer) ||
1444             (!callout_active(&seq->xack_timer)))
1445                 return;
1446
1447         /* Sanity check */
1448         L2TP_SEQ_CHECK(seq);
1449
1450         /* Send a ZLB */
1451         ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1452
1453         /* callout_deactivate() is not needed here
1454             as ng_uncallout() was called by ng_l2tp_xmit_ctrl() */
1455
1456         /* Sanity check */
1457         L2TP_SEQ_CHECK(seq);
1458 }
1459
1460 /*
1461  * Handle a transmit timeout. The peer has failed to respond
1462  * with an ack for our packet, so retransmit it.
1463  */
1464 static void
1465 ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1466 {
1467         const priv_p priv = NG_NODE_PRIVATE(node);
1468         struct l2tp_seq *const seq = &priv->seq;
1469         struct mbuf *m;
1470         u_int delay;
1471
1472         /* Make sure callout is still active before doing anything */
1473         if (callout_pending(&seq->rack_timer) ||
1474             (!callout_active(&seq->rack_timer)))
1475                 return;
1476
1477         /* Sanity check */
1478         L2TP_SEQ_CHECK(seq);
1479
1480         priv->stats.xmitRetransmits++;
1481
1482         /* Have we reached the retransmit limit? If so, notify owner. */
1483         if (seq->rexmits++ >= priv->conf.rexmit_max)
1484                 ng_l2tp_seq_failure(priv);
1485
1486         /* Restart timer, this time with an increased delay */
1487         delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
1488         if (delay > priv->conf.rexmit_max_to)
1489                 delay = priv->conf.rexmit_max_to;
1490         ng_callout(&seq->rack_timer, node, NULL,
1491             hz * delay, ng_l2tp_seq_rack_timeout, NULL, 0);
1492
1493         /* Do slow-start/congestion algorithm windowing algorithm */
1494         seq->ns = seq->rack;
1495         seq->ssth = (seq->cwnd + 1) / 2;
1496         seq->cwnd = 1;
1497         seq->acks = 0;
1498
1499         /* Retransmit oldest unack'd packet */
1500         if ((m = L2TP_COPY_MBUF(seq->xwin[0], MB_DONTWAIT)) == NULL)
1501                 priv->stats.memoryFailures++;
1502         else
1503                 ng_l2tp_xmit_ctrl(priv, m, seq->ns++);
1504
1505         /* callout_deactivate() is not needed here
1506             as ng_callout() is getting called each time */
1507
1508         /* Sanity check */
1509         L2TP_SEQ_CHECK(seq);
1510 }
1511
1512 /*
1513  * Transmit a control stream packet, payload optional.
1514  * The transmit sequence number is not incremented.
1515  */
1516 static int
1517 ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns)
1518 {
1519         struct l2tp_seq *const seq = &priv->seq;
1520         u_int16_t session_id = 0;
1521         int error;
1522
1523         mtx_lock(&seq->mtx);
1524
1525         /* Stop ack timer: we're sending an ack with this packet.
1526            Doing this before to keep state predictable after error. */
1527         if (callout_active(&seq->xack_timer))
1528                 ng_uncallout(&seq->xack_timer, priv->node);
1529
1530         seq->xack = seq->nr;
1531
1532         mtx_unlock(&seq->mtx);
1533
1534         /* If no mbuf passed, send an empty packet (ZLB) */
1535         if (m == NULL) {
1536
1537                 /* Create a new mbuf for ZLB packet */
1538                 MGETHDR(m, MB_DONTWAIT, MT_DATA);
1539                 if (m == NULL) {
1540                         priv->stats.memoryFailures++;
1541                         return (ENOBUFS);
1542                 }
1543                 m->m_len = m->m_pkthdr.len = 12;
1544                 m->m_pkthdr.rcvif = NULL;
1545                 priv->stats.xmitZLBs++;
1546         } else {
1547
1548                 /* Strip off session ID */
1549                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
1550                         priv->stats.memoryFailures++;
1551                         return (ENOBUFS);
1552                 }
1553                 memcpy(&session_id, mtod(m, u_int16_t *), 2);
1554                 m_adj(m, 2);
1555
1556                 /* Make room for L2TP header */
1557                 M_PREPEND(m, 12, MB_DONTWAIT);
1558                 if (m == NULL) {
1559                         priv->stats.memoryFailures++;
1560                         return (ENOBUFS);
1561                 }
1562         }
1563
1564         /* Fill in L2TP header */
1565         mtod(m, u_int16_t *)[0] = htons(L2TP_CTRL_HDR);
1566         mtod(m, u_int16_t *)[1] = htons(m->m_pkthdr.len);
1567         mtod(m, u_int16_t *)[2] = priv->conf.peer_id;
1568         mtod(m, u_int16_t *)[3] = session_id;
1569         mtod(m, u_int16_t *)[4] = htons(ns);
1570         mtod(m, u_int16_t *)[5] = htons(seq->nr);
1571
1572         /* Update sequence number info and stats */
1573         priv->stats.xmitPackets++;
1574         priv->stats.xmitOctets += m->m_pkthdr.len;
1575
1576         /* Send packet */
1577         NG_SEND_DATA_ONLY(error, priv->lower, m);
1578         return (error);
1579 }
1580
1581 #ifdef INVARIANTS
1582 /*
1583  * Sanity check sequence number state.
1584  */
1585 static void
1586 ng_l2tp_seq_check(struct l2tp_seq *seq)
1587 {
1588         int self_unack, peer_unack;
1589         int i;
1590
1591 #define CHECK(p)        KASSERT((p), ("%s: not: %s", __func__, #p))
1592
1593         mtx_lock(&seq->mtx);
1594
1595         self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack);
1596         peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack);
1597         CHECK(seq->wmax <= L2TP_MAX_XWIN);
1598         CHECK(seq->cwnd >= 1);
1599         CHECK(seq->cwnd <= seq->wmax);
1600         CHECK(seq->ssth >= 1);
1601         CHECK(seq->ssth <= seq->wmax);
1602         if (seq->cwnd < seq->ssth)
1603                 CHECK(seq->acks == 0);
1604         else
1605                 CHECK(seq->acks <= seq->cwnd);
1606         CHECK(self_unack >= 0);
1607         CHECK(peer_unack >= 0);
1608         CHECK(peer_unack <= seq->wmax);
1609         CHECK((self_unack == 0) ^ callout_active(&seq->xack_timer));
1610         CHECK((peer_unack == 0) ^ callout_active(&seq->rack_timer));
1611         for (i = 0; i < peer_unack; i++)
1612                 CHECK(seq->xwin[i] != NULL);
1613         for ( ; i < seq->cwnd; i++)         /* verify peer's recv window full */
1614                 CHECK(seq->xwin[i] == NULL);
1615
1616         mtx_unlock(&seq->mtx);
1617
1618 #undef CHECK
1619 }
1620 #endif  /* INVARIANTS */