sys/netgraph/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
  40 /*
  41  * L2TP netgraph node type.
  42  *
  43  * This node type implements the lower layer of the
  44  * L2TP protocol as specified in RFC 2661.
  45  */
  46
  47 #include <sys/param.h>
  48 #include <sys/systm.h>
  49 #include <sys/kernel.h>
  50 #include <sys/time.h>
  51 #include <sys/conf.h>
  52 #include <sys/mbuf.h>
  53 #include <sys/malloc.h>
  54 #include <sys/errno.h>
  55 #include <sys/epoch.h>
  56 #include <sys/libkern.h>
  57
  58 #include <net/vnet.h>
  59
  60 #include <netgraph/ng_message.h>
  61 #include <netgraph/netgraph.h>
  62 #include <netgraph/ng_parse.h>
  63 #include <netgraph/ng_l2tp.h>
  64
  65 #ifdef NG_SEPARATE_MALLOC
  66 static 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)     ((int16_t)((x) - (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(void *);
 185 static void     ng_l2tp_seq_rack_timeout(void *);
 186
 187 static hookpriv_p       ng_l2tp_find_session(priv_p privp, u_int16_t sid);
 188 static ng_fn_eachhook   ng_l2tp_reset_session;
 189
 190 /* Parse type for struct ng_l2tp_seq_config. */
 191 static const struct ng_parse_struct_field
 192         ng_l2tp_seq_config_fields[] = NG_L2TP_SEQ_CONFIG_TYPE_INFO;
 193 static const struct ng_parse_type ng_l2tp_seq_config_type = {
 194         &ng_parse_struct_type,
 195         &ng_l2tp_seq_config_fields
 196 };
 197
 198 /* Parse type for struct ng_l2tp_config */
 199 static const struct ng_parse_struct_field
 200         ng_l2tp_config_type_fields[] = NG_L2TP_CONFIG_TYPE_INFO;
 201 static const struct ng_parse_type ng_l2tp_config_type = {
 202         &ng_parse_struct_type,
 203         &ng_l2tp_config_type_fields,
 204 };
 205
 206 /* Parse type for struct ng_l2tp_sess_config */
 207 static const struct ng_parse_struct_field
 208         ng_l2tp_sess_config_type_fields[] = NG_L2TP_SESS_CONFIG_TYPE_INFO;
 209 static const struct ng_parse_type ng_l2tp_sess_config_type = {
 210         &ng_parse_struct_type,
 211         &ng_l2tp_sess_config_type_fields,
 212 };
 213
 214 /* Parse type for struct ng_l2tp_stats */
 215 static const struct ng_parse_struct_field
 216         ng_l2tp_stats_type_fields[] = NG_L2TP_STATS_TYPE_INFO;
 217 static const struct ng_parse_type ng_l2tp_stats_type = {
 218         &ng_parse_struct_type,
 219         &ng_l2tp_stats_type_fields
 220 };
 221
 222 /* Parse type for struct ng_l2tp_session_stats. */
 223 static const struct ng_parse_struct_field
 224         ng_l2tp_session_stats_type_fields[] = NG_L2TP_SESSION_STATS_TYPE_INFO;
 225 static const struct ng_parse_type ng_l2tp_session_stats_type = {
 226         &ng_parse_struct_type,
 227         &ng_l2tp_session_stats_type_fields
 228 };
 229
 230 /* List of commands and how to convert arguments to/from ASCII */
 231 static const struct ng_cmdlist ng_l2tp_cmdlist[] = {
 232         {
 233           NGM_L2TP_COOKIE,
 234           NGM_L2TP_SET_CONFIG,
 235           "setconfig",
 236           &ng_l2tp_config_type,
 237           NULL
 238         },
 239         {
 240           NGM_L2TP_COOKIE,
 241           NGM_L2TP_GET_CONFIG,
 242           "getconfig",
 243           NULL,
 244           &ng_l2tp_config_type
 245         },
 246         {
 247           NGM_L2TP_COOKIE,
 248           NGM_L2TP_SET_SESS_CONFIG,
 249           "setsessconfig",
 250           &ng_l2tp_sess_config_type,
 251           NULL
 252         },
 253         {
 254           NGM_L2TP_COOKIE,
 255           NGM_L2TP_GET_SESS_CONFIG,
 256           "getsessconfig",
 257           &ng_parse_hint16_type,
 258           &ng_l2tp_sess_config_type
 259         },
 260         {
 261           NGM_L2TP_COOKIE,
 262           NGM_L2TP_GET_STATS,
 263           "getstats",
 264           NULL,
 265           &ng_l2tp_stats_type
 266         },
 267         {
 268           NGM_L2TP_COOKIE,
 269           NGM_L2TP_CLR_STATS,
 270           "clrstats",
 271           NULL,
 272           NULL
 273         },
 274         {
 275           NGM_L2TP_COOKIE,
 276           NGM_L2TP_GETCLR_STATS,
 277           "getclrstats",
 278           NULL,
 279           &ng_l2tp_stats_type
 280         },
 281         {
 282           NGM_L2TP_COOKIE,
 283           NGM_L2TP_GET_SESSION_STATS,
 284           "getsessstats",
 285           &ng_parse_int16_type,
 286           &ng_l2tp_session_stats_type
 287         },
 288         {
 289           NGM_L2TP_COOKIE,
 290           NGM_L2TP_CLR_SESSION_STATS,
 291           "clrsessstats",
 292           &ng_parse_int16_type,
 293           NULL
 294         },
 295         {
 296           NGM_L2TP_COOKIE,
 297           NGM_L2TP_GETCLR_SESSION_STATS,
 298           "getclrsessstats",
 299           &ng_parse_int16_type,
 300           &ng_l2tp_session_stats_type
 301         },
 302         {
 303           NGM_L2TP_COOKIE,
 304           NGM_L2TP_ACK_FAILURE,
 305           "ackfailure",
 306           NULL,
 307           NULL
 308         },
 309         {
 310           NGM_L2TP_COOKIE,
 311           NGM_L2TP_SET_SEQ,
 312           "setsequence",
 313           &ng_l2tp_seq_config_type,
 314           NULL
 315         },
 316         { 0 }
 317 };
 318
 319 /* Node type descriptor */
 320 static struct ng_type ng_l2tp_typestruct = {
 321         .version =      NG_ABI_VERSION,
 322         .name =         NG_L2TP_NODE_TYPE,
 323         .constructor =  ng_l2tp_constructor,
 324         .rcvmsg =       ng_l2tp_rcvmsg,
 325         .shutdown =     ng_l2tp_shutdown,
 326         .newhook =      ng_l2tp_newhook,
 327         .rcvdata =      ng_l2tp_rcvdata,
 328         .disconnect =   ng_l2tp_disconnect,
 329         .cmdlist =      ng_l2tp_cmdlist,
 330 };
 331 NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct);
 332
 333 /* Sequence number state locking & sanity checking */
 334 #ifdef INVARIANTS
 335 static void     ng_l2tp_seq_check(struct l2tp_seq *seq);
 336 #define SEQ_LOCK(seq)   do {                                    \
 337                                 mtx_lock(&(seq)->mtx);          \
 338                                 ng_l2tp_seq_check(seq);         \
 339 } while (0)
 340 #define SEQ_UNLOCK(seq) do {                                    \
 341                                 ng_l2tp_seq_check(seq);         \
 342                                 mtx_unlock(&(seq)->mtx);        \
 343 } while (0)
 344 #else
 345 #define SEQ_LOCK(seq)           mtx_lock(&(seq)->mtx)
 346 #define SEQ_UNLOCK(seq)         mtx_unlock(&(seq)->mtx)
 347 #endif
 348 #define SEQ_LOCK_ASSERT(seq)    mtx_assert(&(seq)->mtx, MA_OWNED)
 349
 350 /* Whether to use m_copypacket() or m_dup() */
 351 #define L2TP_COPY_MBUF          m_copypacket
 352
 353 #define ERROUT(x)       do { error = (x); goto done; } while (0)
 354
 355 /************************************************************************
 356                         NETGRAPH NODE STUFF
 357 ************************************************************************/
 358
 359 /*
 360  * Node type constructor
 361  */
 362 static int
 363 ng_l2tp_constructor(node_p node)
 364 {
 365         priv_p priv;
 366         int     i;
 367
 368         /* Allocate private structure */
 369         priv = malloc(sizeof(*priv), M_NETGRAPH_L2TP, M_WAITOK | M_ZERO);
 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                 hpriv = malloc(sizeof(*hpriv),
 432                     M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
 433                 if (hpriv == NULL)
 434                         return (ENOMEM);
 435                 hpriv->conf.session_id = 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                         if (priv->conf.enabled
 476                             && ((priv->conf.tunnel_id != 0
 477                                && conf->tunnel_id != priv->conf.tunnel_id)
 478                               || ((priv->conf.peer_id != 0
 479                                && conf->peer_id != priv->conf.peer_id)))) {
 480                                 error = EBUSY;
 481                                 break;
 482                         }
 483
 484                         /* Save calling node as failure target */
 485                         priv->ftarget = NGI_RETADDR(item);
 486
 487                         /* Adjust sequence number state */
 488                         if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0)
 489                                 break;
 490
 491                         /* Update node's config */
 492                         priv->conf = *conf;
 493                         break;
 494                     }
 495                 case NGM_L2TP_GET_CONFIG:
 496                     {
 497                         struct ng_l2tp_config *conf;
 498
 499                         NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT);
 500                         if (resp == NULL) {
 501                                 error = ENOMEM;
 502                                 break;
 503                         }
 504                         conf = (struct ng_l2tp_config *)resp->data;
 505                         *conf = priv->conf;
 506                         break;
 507                     }
 508                 case NGM_L2TP_SET_SESS_CONFIG:
 509                     {
 510                         struct ng_l2tp_sess_config *const conf =
 511                             (struct ng_l2tp_sess_config *)msg->data;
 512                         hookpriv_p hpriv;
 513
 514                         /* Check for invalid or illegal config. */
 515                         if (msg->header.arglen != sizeof(*conf)) {
 516                                 error = EINVAL;
 517                                 break;
 518                         }
 519
 520                         /* Find matching hook */
 521                         hpriv = ng_l2tp_find_session(priv, conf->session_id);
 522                         if (hpriv == NULL) {
 523                                 error = ENOENT;
 524                                 break;
 525                         }
 526
 527                         /* Update hook's config */
 528                         hpriv->conf = *conf;
 529                         break;
 530                     }
 531                 case NGM_L2TP_GET_SESS_CONFIG:
 532                     {
 533                         struct ng_l2tp_sess_config *conf;
 534                         u_int16_t session_id;
 535                         hookpriv_p hpriv;
 536
 537                         /* Get session ID */
 538                         if (msg->header.arglen != sizeof(session_id)) {
 539                                 error = EINVAL;
 540                                 break;
 541                         }
 542                         memcpy(&session_id, msg->data, 2);
 543
 544                         /* Find matching hook */
 545                         hpriv = ng_l2tp_find_session(priv, session_id);
 546                         if (hpriv == NULL) {
 547                                 error = ENOENT;
 548                                 break;
 549                         }
 550
 551                         /* Send response */
 552                         NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_NOWAIT);
 553                         if (resp == NULL) {
 554                                 error = ENOMEM;
 555                                 break;
 556                         }
 557                         conf = (struct ng_l2tp_sess_config *)resp->data;
 558                         *conf = hpriv->conf;
 559                         break;
 560                     }
 561                 case NGM_L2TP_GET_STATS:
 562                 case NGM_L2TP_CLR_STATS:
 563                 case NGM_L2TP_GETCLR_STATS:
 564                     {
 565                         if (msg->header.cmd != NGM_L2TP_CLR_STATS) {
 566                                 NG_MKRESPONSE(resp, msg,
 567                                     sizeof(priv->stats), M_NOWAIT);
 568                                 if (resp == NULL) {
 569                                         error = ENOMEM;
 570                                         break;
 571                                 }
 572                                 memcpy(resp->data,
 573                                     &priv->stats, sizeof(priv->stats));
 574                         }
 575                         if (msg->header.cmd != NGM_L2TP_GET_STATS)
 576                                 memset(&priv->stats, 0, sizeof(priv->stats));
 577                         break;
 578                     }
 579                 case NGM_L2TP_GET_SESSION_STATS:
 580                 case NGM_L2TP_CLR_SESSION_STATS:
 581                 case NGM_L2TP_GETCLR_SESSION_STATS:
 582                     {
 583                         uint16_t session_id;
 584                         hookpriv_p hpriv;
 585
 586                         /* Get session ID. */
 587                         if (msg->header.arglen != sizeof(session_id)) {
 588                                 error = EINVAL;
 589                                 break;
 590                         }
 591                         bcopy(msg->data, &session_id, sizeof(uint16_t));
 592
 593                         /* Find matching hook. */
 594                         hpriv = ng_l2tp_find_session(priv, session_id);
 595                         if (hpriv == NULL) {
 596                                 error = ENOENT;
 597                                 break;
 598                         }
 599
 600                         if (msg->header.cmd != NGM_L2TP_CLR_SESSION_STATS) {
 601                                 NG_MKRESPONSE(resp, msg,
 602                                     sizeof(hpriv->stats), M_NOWAIT);
 603                                 if (resp == NULL) {
 604                                         error = ENOMEM;
 605                                         break;
 606                                 }
 607                                 bcopy(&hpriv->stats, resp->data,
 608                                         sizeof(hpriv->stats));
 609                         }
 610                         if (msg->header.cmd != NGM_L2TP_GET_SESSION_STATS)
 611                                 bzero(&hpriv->stats, sizeof(hpriv->stats));
 612                         break;
 613                     }
 614                 case NGM_L2TP_SET_SEQ:
 615                     {
 616                         struct ng_l2tp_seq_config *const conf =
 617                                 (struct ng_l2tp_seq_config *)msg->data;
 618
 619                         /* Check for invalid or illegal seq config. */
 620                         if (msg->header.arglen != sizeof(*conf)) {
 621                                 error = EINVAL;
 622                                 break;
 623                         }
 624                         conf->ns = htons(conf->ns);
 625                         conf->nr = htons(conf->nr);
 626                         conf->rack = htons(conf->rack);
 627                         conf->xack = htons(conf->xack);
 628
 629                         /* Set sequence numbers. */
 630                         error = ng_l2tp_seq_set(priv, conf);
 631                         break;
 632                     }
 633                 default:
 634                         error = EINVAL;
 635                         break;
 636                 }
 637                 break;
 638         default:
 639                 error = EINVAL;
 640                 break;
 641         }
 642
 643         /* Done */
 644         NG_RESPOND_MSG(error, node, item, resp);
 645         NG_FREE_MSG(msg);
 646         return (error);
 647 }
 648
 649 /*
 650  * Destroy node
 651  */
 652 static int
 653 ng_l2tp_shutdown(node_p node)
 654 {
 655         const priv_p priv = NG_NODE_PRIVATE(node);
 656         struct l2tp_seq *const seq = &priv->seq;
 657
 658         /* Reset sequence number state */
 659         SEQ_LOCK(seq);
 660         ng_l2tp_seq_reset(priv);
 661         SEQ_UNLOCK(seq);
 662
 663         /* Free private data if neither timer is running */
 664         callout_drain(&seq->rack_timer);
 665         callout_drain(&seq->xack_timer);
 666
 667         mtx_destroy(&seq->mtx);
 668
 669         free(priv, M_NETGRAPH_L2TP);
 670
 671         /* Unref node */
 672         NG_NODE_UNREF(node);
 673         return (0);
 674 }
 675
 676 /*
 677  * Hook disconnection
 678  */
 679 static int
 680 ng_l2tp_disconnect(hook_p hook)
 681 {
 682         const node_p node = NG_HOOK_NODE(hook);
 683         const priv_p priv = NG_NODE_PRIVATE(node);
 684
 685         /* Zero out hook pointer */
 686         if (hook == priv->ctrl)
 687                 priv->ctrl = NULL;
 688         else if (hook == priv->lower)
 689                 priv->lower = NULL;
 690         else {
 691                 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
 692                 LIST_REMOVE(hpriv, sessions);
 693                 free(hpriv, M_NETGRAPH_L2TP);
 694                 NG_HOOK_SET_PRIVATE(hook, NULL);
 695         }
 696
 697         /* Go away if no longer connected to anything */
 698         if (NG_NODE_NUMHOOKS(node) == 0 && NG_NODE_IS_VALID(node))
 699                 ng_rmnode_self(node);
 700         return (0);
 701 }
 702
 703 /*************************************************************************
 704                         INTERNAL FUNCTIONS
 705 *************************************************************************/
 706
 707 /*
 708  * Find the hook with a given session ID.
 709  */
 710 static hookpriv_p
 711 ng_l2tp_find_session(priv_p privp, u_int16_t sid)
 712 {
 713         uint16_t        hash = SESSHASH(sid);
 714         hookpriv_p      hpriv = NULL;
 715
 716         LIST_FOREACH(hpriv, &privp->sesshash[hash], sessions) {
 717                 if (hpriv->conf.session_id == sid)
 718                         break;
 719         }
 720
 721         return (hpriv);
 722 }
 723
 724 /*
 725  * Reset a hook's session state.
 726  */
 727 static int
 728 ng_l2tp_reset_session(hook_p hook, void *arg)
 729 {
 730         const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
 731
 732         if (hpriv != NULL) {
 733                 hpriv->conf.control_dseq = 0;
 734                 hpriv->conf.enable_dseq = 0;
 735                 bzero(&hpriv->stats, sizeof(struct ng_l2tp_session_stats));
 736                 hpriv->nr = 0;
 737                 hpriv->ns = 0;
 738         }
 739         return (-1);
 740 }
 741
 742 /*
 743  * Handle an incoming frame from below.
 744  */
 745 static int
 746 ng_l2tp_rcvdata_lower(hook_p h, item_p item)
 747 {
 748         static const u_int16_t req_bits[2][2] = {
 749                 { L2TP_DATA_0BITS, L2TP_DATA_1BITS },
 750                 { L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
 751         };
 752         const node_p node = NG_HOOK_NODE(h);
 753         const priv_p priv = NG_NODE_PRIVATE(node);
 754         hookpriv_p hpriv = NULL;
 755         hook_p hook = NULL;
 756         struct mbuf *m;
 757         u_int16_t tid, sid;
 758         u_int16_t hdr;
 759         u_int16_t ns, nr;
 760         int is_ctrl;
 761         int error;
 762         int len, plen;
 763
 764         /* If not configured, reject */
 765         if (!priv->conf.enabled) {
 766                 NG_FREE_ITEM(item);
 767                 ERROUT(ENXIO);
 768         }
 769
 770         /* Grab mbuf */
 771         NGI_GET_M(item, m);
 772
 773         /* Remember full packet length; needed for per session accounting. */
 774         plen = m->m_pkthdr.len;
 775
 776         /* Update stats */
 777         priv->stats.recvPackets++;
 778         priv->stats.recvOctets += plen;
 779
 780         /* Get initial header */
 781         if (m->m_pkthdr.len < 6) {
 782                 priv->stats.recvRunts++;
 783                 NG_FREE_ITEM(item);
 784                 NG_FREE_M(m);
 785                 ERROUT(EINVAL);
 786         }
 787         if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 788                 priv->stats.memoryFailures++;
 789                 NG_FREE_ITEM(item);
 790                 ERROUT(EINVAL);
 791         }
 792         hdr = (mtod(m, uint8_t *)[0] << 8) + mtod(m, uint8_t *)[1];
 793         m_adj(m, 2);
 794
 795         /* Check required header bits and minimum length */
 796         is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
 797         if ((hdr & req_bits[is_ctrl][0]) != 0
 798             || (~hdr & req_bits[is_ctrl][1]) != 0) {
 799                 priv->stats.recvInvalid++;
 800                 NG_FREE_ITEM(item);
 801                 NG_FREE_M(m);
 802                 ERROUT(EINVAL);
 803         }
 804         if (m->m_pkthdr.len < 4                         /* tunnel, session id */
 805             + (2 * ((hdr & L2TP_HDR_LEN) != 0))         /* length field */
 806             + (4 * ((hdr & L2TP_HDR_SEQ) != 0))         /* seq # fields */
 807             + (2 * ((hdr & L2TP_HDR_OFF) != 0))) {      /* offset field */
 808                 priv->stats.recvRunts++;
 809                 NG_FREE_ITEM(item);
 810                 NG_FREE_M(m);
 811                 ERROUT(EINVAL);
 812         }
 813
 814         /* Get and validate length field if present */
 815         if ((hdr & L2TP_HDR_LEN) != 0) {
 816                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 817                         priv->stats.memoryFailures++;
 818                         NG_FREE_ITEM(item);
 819                         ERROUT(EINVAL);
 820                 }
 821                 len = (mtod(m, uint8_t *)[0] << 8) + mtod(m, uint8_t *)[1] - 4;
 822                 m_adj(m, 2);
 823                 if (len < 0 || len > m->m_pkthdr.len) {
 824                         priv->stats.recvInvalid++;
 825                         NG_FREE_ITEM(item);
 826                         NG_FREE_M(m);
 827                         ERROUT(EINVAL);
 828                 }
 829                 if (len < m->m_pkthdr.len)              /* trim extra bytes */
 830                         m_adj(m, -(m->m_pkthdr.len - len));
 831         }
 832
 833         /* Get tunnel ID and session ID */
 834         if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
 835                 priv->stats.memoryFailures++;
 836                 NG_FREE_ITEM(item);
 837                 ERROUT(EINVAL);
 838         }
 839         tid = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
 840         sid = (mtod(m, u_int8_t *)[2] << 8) + mtod(m, u_int8_t *)[3];
 841         m_adj(m, 4);
 842
 843         /* Check tunnel ID */
 844         if (tid != priv->conf.tunnel_id &&
 845             (priv->conf.match_id || tid != 0)) {
 846                 priv->stats.recvWrongTunnel++;
 847                 NG_FREE_ITEM(item);
 848                 NG_FREE_M(m);
 849                 ERROUT(EADDRNOTAVAIL);
 850         }
 851
 852         /* Check session ID (for data packets only) */
 853         if ((hdr & L2TP_HDR_CTRL) == 0) {
 854                 hpriv = ng_l2tp_find_session(priv, sid);
 855                 if (hpriv == NULL) {
 856                         priv->stats.recvUnknownSID++;
 857                         NG_FREE_ITEM(item);
 858                         NG_FREE_M(m);
 859                         ERROUT(ENOTCONN);
 860                 }
 861                 hook = hpriv->hook;
 862         }
 863
 864         /* Get Ns, Nr fields if present */
 865         if ((hdr & L2TP_HDR_SEQ) != 0) {
 866                 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
 867                         priv->stats.memoryFailures++;
 868                         NG_FREE_ITEM(item);
 869                         ERROUT(EINVAL);
 870                 }
 871                 ns = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
 872                 nr = (mtod(m, u_int8_t *)[2] << 8) + mtod(m, u_int8_t *)[3];
 873                 m_adj(m, 4);
 874         } else
 875                 ns = nr = 0;
 876
 877         /* Strip offset padding if present */
 878         if ((hdr & L2TP_HDR_OFF) != 0) {
 879                 u_int16_t offset;
 880
 881                 /* Get length of offset padding */
 882                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 883                         priv->stats.memoryFailures++;
 884                         NG_FREE_ITEM(item);
 885                         ERROUT(EINVAL);
 886                 }
 887                 offset = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
 888
 889                 /* Trim offset padding */
 890                 if ((2+offset) > m->m_pkthdr.len) {
 891                         priv->stats.recvInvalid++;
 892                         NG_FREE_ITEM(item);
 893                         NG_FREE_M(m);
 894                         ERROUT(EINVAL);
 895                 }
 896                 m_adj(m, 2+offset);
 897         }
 898
 899         /* Handle control packets */
 900         if ((hdr & L2TP_HDR_CTRL) != 0) {
 901                 struct l2tp_seq *const seq = &priv->seq;
 902
 903                 SEQ_LOCK(seq);
 904
 905                 /* Handle receive ack sequence number Nr */
 906                 ng_l2tp_seq_recv_nr(priv, nr);
 907
 908                 /* Discard ZLB packets */
 909                 if (m->m_pkthdr.len == 0) {
 910                         SEQ_UNLOCK(seq);
 911                         priv->stats.recvZLBs++;
 912                         NG_FREE_ITEM(item);
 913                         NG_FREE_M(m);
 914                         ERROUT(0);
 915                 }
 916
 917                 /*
 918                  * If not what we expect or we are busy, drop packet and
 919                  * send an immediate ZLB ack.
 920                  */
 921                 if (ns != seq->nr || seq->inproc) {
 922                         if (L2TP_SEQ_DIFF(ns, seq->nr) <= 0)
 923                                 priv->stats.recvDuplicates++;
 924                         else
 925                                 priv->stats.recvOutOfOrder++;
 926                         ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
 927                         NG_FREE_ITEM(item);
 928                         NG_FREE_M(m);
 929                         ERROUT(0);
 930                 }
 931
 932                 /* Prepend session ID to packet. */
 933                 M_PREPEND(m, 2, M_NOWAIT);
 934                 if (m == NULL) {
 935                         SEQ_UNLOCK(seq);
 936                         priv->stats.memoryFailures++;
 937                         NG_FREE_ITEM(item);
 938                         ERROUT(ENOBUFS);
 939                 }
 940                 mtod(m, u_int8_t *)[0] = sid >> 8;
 941                 mtod(m, u_int8_t *)[1] = sid & 0xff;
 942
 943                 /*
 944                  * Until we deliver this packet we can't receive next one as
 945                  * we have no information for sending ack.
 946                  */
 947                 seq->inproc = 1;
 948                 SEQ_UNLOCK(seq);
 949
 950                 /* Deliver packet to upper layers */
 951                 NG_FWD_NEW_DATA(error, item, priv->ctrl, m);
 952
 953                 SEQ_LOCK(seq);
 954                 /* Ready to process next packet. */
 955                 seq->inproc = 0;
 956
 957                 /* If packet was successfully delivered send ack. */
 958                 if (error == 0) {
 959                         /* Update recv sequence number */
 960                         seq->nr++;
 961                         /* Start receive ack timer, if not already running */
 962                         if (!callout_active(&seq->xack_timer)) {
 963                                 callout_reset(&seq->xack_timer,
 964                                     L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout,
 965                                     node);
 966                         }
 967                 }
 968                 SEQ_UNLOCK(seq);
 969
 970                 ERROUT(error);
 971         }
 972
 973         /* Per session packet, account it. */
 974         hpriv->stats.recvPackets++;
 975         hpriv->stats.recvOctets += plen;
 976
 977         /* Follow peer's lead in data sequencing, if configured to do so */
 978         if (!hpriv->conf.control_dseq)
 979                 hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0);
 980
 981         /* Handle data sequence numbers if present and enabled */
 982         if ((hdr & L2TP_HDR_SEQ) != 0) {
 983                 if (hpriv->conf.enable_dseq
 984                     && L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) {
 985                         NG_FREE_ITEM(item);     /* duplicate or out of order */
 986                         NG_FREE_M(m);
 987                         priv->stats.recvDataDrops++;
 988                         ERROUT(0);
 989                 }
 990                 hpriv->nr = ns + 1;
 991         }
 992
 993         /* Drop empty data packets */
 994         if (m->m_pkthdr.len == 0) {
 995                 NG_FREE_ITEM(item);
 996                 NG_FREE_M(m);
 997                 ERROUT(0);
 998         }
 999
1000         /* Deliver data */
1001         NG_FWD_NEW_DATA(error, item, hook, m);
1002 done:
1003         return (error);
1004 }
1005
1006 /*
1007  * Handle an outgoing control frame.
1008  */
1009 static int
1010 ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item)
1011 {
1012         const node_p node = NG_HOOK_NODE(hook);
1013         const priv_p priv = NG_NODE_PRIVATE(node);
1014         struct l2tp_seq *const seq = &priv->seq;
1015         struct mbuf *m;
1016         int error;
1017         int i;
1018         u_int16_t       ns;
1019
1020         /* If not configured, reject */
1021         if (!priv->conf.enabled) {
1022                 NG_FREE_ITEM(item);
1023                 ERROUT(ENXIO);
1024         }
1025
1026         /* Grab mbuf and discard other stuff XXX */
1027         NGI_GET_M(item, m);
1028         NG_FREE_ITEM(item);
1029
1030         /* Packet should have session ID prepended */
1031         if (m->m_pkthdr.len < 2) {
1032                 priv->stats.xmitInvalid++;
1033                 m_freem(m);
1034                 ERROUT(EINVAL);
1035         }
1036
1037         /* Check max length */
1038         if (m->m_pkthdr.len >= 0x10000 - 14) {
1039                 priv->stats.xmitTooBig++;
1040                 m_freem(m);
1041                 ERROUT(EOVERFLOW);
1042         }
1043
1044         SEQ_LOCK(seq);
1045
1046         /* Find next empty slot in transmit queue */
1047         for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
1048         if (i == L2TP_MAX_XWIN) {
1049                 SEQ_UNLOCK(seq);
1050                 priv->stats.xmitDrops++;
1051                 m_freem(m);
1052                 ERROUT(ENOBUFS);
1053         }
1054         seq->xwin[i] = m;
1055
1056         /* If peer's receive window is already full, nothing else to do */
1057         if (i >= seq->cwnd) {
1058                 SEQ_UNLOCK(seq);
1059                 ERROUT(0);
1060         }
1061
1062         /* Start retransmit timer if not already running */
1063         if (!callout_active(&seq->rack_timer))
1064                 callout_reset(&seq->rack_timer, hz, ng_l2tp_seq_rack_timeout,
1065                     node);
1066
1067         ns = seq->ns++;
1068
1069         /* Copy packet */
1070         if ((m = L2TP_COPY_MBUF(m, M_NOWAIT)) == NULL) {
1071                 SEQ_UNLOCK(seq);
1072                 priv->stats.memoryFailures++;
1073                 ERROUT(ENOBUFS);
1074         }
1075
1076         /* Send packet and increment xmit sequence number */
1077         error = ng_l2tp_xmit_ctrl(priv, m, ns);
1078 done:
1079         return (error);
1080 }
1081
1082 /*
1083  * Handle an outgoing data frame.
1084  */
1085 static int
1086 ng_l2tp_rcvdata(hook_p hook, item_p item)
1087 {
1088         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
1089         const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
1090         struct mbuf *m;
1091         uint8_t *p;
1092         u_int16_t hdr;
1093         int error;
1094         int i = 2;
1095
1096         /* If not configured, reject */
1097         if (!priv->conf.enabled) {
1098                 NG_FREE_ITEM(item);
1099                 ERROUT(ENXIO);
1100         }
1101
1102         /* Get mbuf */
1103         NGI_GET_M(item, m);
1104
1105         /* Check max length */
1106         if (m->m_pkthdr.len >= 0x10000 - 12) {
1107                 priv->stats.xmitDataTooBig++;
1108                 NG_FREE_ITEM(item);
1109                 NG_FREE_M(m);
1110                 ERROUT(EOVERFLOW);
1111         }
1112
1113         /* Prepend L2TP header */
1114         M_PREPEND(m, 6
1115             + (2 * (hpriv->conf.include_length != 0))
1116             + (4 * (hpriv->conf.enable_dseq != 0)),
1117             M_NOWAIT);
1118         if (m == NULL) {
1119                 priv->stats.memoryFailures++;
1120                 NG_FREE_ITEM(item);
1121                 ERROUT(ENOBUFS);
1122         }
1123         p = mtod(m, uint8_t *);
1124         hdr = L2TP_DATA_HDR;
1125         if (hpriv->conf.include_length) {
1126                 hdr |= L2TP_HDR_LEN;
1127                 p[i++] = m->m_pkthdr.len >> 8;
1128                 p[i++] = m->m_pkthdr.len & 0xff;
1129         }
1130         p[i++] = priv->conf.peer_id >> 8;
1131         p[i++] = priv->conf.peer_id & 0xff;
1132         p[i++] = hpriv->conf.peer_id >> 8;
1133         p[i++] = hpriv->conf.peer_id & 0xff;
1134         if (hpriv->conf.enable_dseq) {
1135                 hdr |= L2TP_HDR_SEQ;
1136                 p[i++] = hpriv->ns >> 8;
1137                 p[i++] = hpriv->ns & 0xff;
1138                 p[i++] = hpriv->nr >> 8;
1139                 p[i++] = hpriv->nr & 0xff;
1140                 hpriv->ns++;
1141         }
1142         p[0] = hdr >> 8;
1143         p[1] = hdr & 0xff;
1144
1145         /* Update per session stats. */
1146         hpriv->stats.xmitPackets++;
1147         hpriv->stats.xmitOctets += m->m_pkthdr.len;
1148
1149         /* And the global one. */
1150         priv->stats.xmitPackets++;
1151         priv->stats.xmitOctets += m->m_pkthdr.len;
1152
1153         /* Send packet */
1154         NG_FWD_NEW_DATA(error, item, priv->lower, m);
1155 done:
1156         return (error);
1157 }
1158
1159 /*
1160  * Send a message to our controlling node that we've failed.
1161  */
1162 static void
1163 ng_l2tp_seq_failure(priv_p priv)
1164 {
1165         struct ng_mesg *msg;
1166         int error;
1167
1168         NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_NOWAIT);
1169         if (msg == NULL)
1170                 return;
1171         NG_SEND_MSG_ID(error, priv->node, msg, priv->ftarget, 0);
1172 }
1173
1174 /************************************************************************
1175                         SEQUENCE NUMBER HANDLING
1176 ************************************************************************/
1177
1178 /*
1179  * Initialize sequence number state.
1180  */
1181 static void
1182 ng_l2tp_seq_init(priv_p priv)
1183 {
1184         struct l2tp_seq *const seq = &priv->seq;
1185
1186         KASSERT(priv->conf.peer_win >= 1,
1187             ("%s: peer_win is zero", __func__));
1188         memset(seq, 0, sizeof(*seq));
1189         seq->cwnd = 1;
1190         seq->wmax = priv->conf.peer_win;
1191         if (seq->wmax > L2TP_MAX_XWIN)
1192                 seq->wmax = L2TP_MAX_XWIN;
1193         seq->ssth = seq->wmax;
1194         mtx_init(&seq->mtx, "ng_l2tp", NULL, MTX_DEF);
1195         callout_init_mtx(&seq->rack_timer, &seq->mtx, CALLOUT_RETURNUNLOCKED);
1196         callout_init_mtx(&seq->xack_timer, &seq->mtx, CALLOUT_RETURNUNLOCKED);
1197 }
1198
1199 /*
1200  * Set sequence number state as given from user.
1201  */
1202 static int
1203 ng_l2tp_seq_set(priv_p priv, const struct ng_l2tp_seq_config *conf)
1204 {
1205         struct l2tp_seq *const seq = &priv->seq;
1206
1207         /* If node is enabled, deny update to sequence numbers. */
1208         if (priv->conf.enabled)
1209                 return (EBUSY);
1210
1211         /* We only can handle the simple cases. */
1212         if (conf->xack != conf->nr || conf->ns != conf->rack)
1213                 return (EINVAL);
1214
1215         /* Set ns,nr,rack,xack parameters. */
1216         seq->ns = conf->ns;
1217         seq->nr = conf->nr;
1218         seq->rack = conf->rack;
1219         seq->xack = conf->xack;
1220
1221         return (0);
1222 }
1223
1224 /*
1225  * Adjust sequence number state accordingly after reconfiguration.
1226  */
1227 static int
1228 ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf)
1229 {
1230         struct l2tp_seq *const seq = &priv->seq;
1231         u_int16_t new_wmax;
1232         int error = 0;
1233
1234         SEQ_LOCK(seq);
1235         /* If disabling node, reset state sequence number */
1236         if (!conf->enabled) {
1237                 ng_l2tp_seq_reset(priv);
1238                 SEQ_UNLOCK(seq);
1239                 return (0);
1240         }
1241
1242         /* Adjust peer's max recv window; it can only increase */
1243         new_wmax = conf->peer_win;
1244         if (new_wmax > L2TP_MAX_XWIN)
1245                 new_wmax = L2TP_MAX_XWIN;
1246         if (new_wmax == 0)
1247                 ERROUT(EINVAL);
1248         if (new_wmax < seq->wmax)
1249                 ERROUT(EBUSY);
1250         seq->wmax = new_wmax;
1251
1252 done:
1253         SEQ_UNLOCK(seq);
1254         return (error);
1255 }
1256
1257 /*
1258  * Reset sequence number state.
1259  */
1260 static void
1261 ng_l2tp_seq_reset(priv_p priv)
1262 {
1263         struct l2tp_seq *const seq = &priv->seq;
1264         int i;
1265
1266         SEQ_LOCK_ASSERT(seq);
1267
1268         /* Stop timers */
1269         (void )callout_stop(&seq->rack_timer);
1270         (void )callout_stop(&seq->xack_timer);
1271
1272         /* Free retransmit queue */
1273         for (i = 0; i < L2TP_MAX_XWIN; i++) {
1274                 if (seq->xwin[i] == NULL)
1275                         break;
1276                 m_freem(seq->xwin[i]);
1277         }
1278
1279         /* Reset session hooks' sequence number states */
1280         NG_NODE_FOREACH_HOOK(priv->node, ng_l2tp_reset_session, NULL);
1281
1282         /* Reset node's sequence number state */
1283         seq->ns = 0;
1284         seq->nr = 0;
1285         seq->rack = 0;
1286         seq->xack = 0;
1287         seq->wmax = L2TP_MAX_XWIN;
1288         seq->cwnd = 1;
1289         seq->ssth = seq->wmax;
1290         seq->acks = 0;
1291         seq->rexmits = 0;
1292         bzero(seq->xwin, sizeof(seq->xwin));
1293 }
1294
1295 /*
1296  * Handle receipt of an acknowledgement value (Nr) from peer.
1297  */
1298 static void
1299 ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr)
1300 {
1301         struct l2tp_seq *const seq = &priv->seq;
1302         struct mbuf     *xwin[L2TP_MAX_XWIN];   /* partial local copy */
1303         int             nack;
1304         int             i, j;
1305         uint16_t        ns;
1306
1307         SEQ_LOCK_ASSERT(seq);
1308
1309         /* Verify peer's ACK is in range */
1310         if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0)
1311                 return;                         /* duplicate ack */
1312         if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) {
1313                 priv->stats.recvBadAcks++;      /* ack for packet not sent */
1314                 return;
1315         }
1316         KASSERT(nack <= L2TP_MAX_XWIN,
1317             ("%s: nack=%d > %d", __func__, nack, L2TP_MAX_XWIN));
1318
1319         /* Update receive ack stats */
1320         seq->rack = nr;
1321         seq->rexmits = 0;
1322
1323         /* Free acknowledged packets and shift up packets in the xmit queue */
1324         for (i = 0; i < nack; i++)
1325                 m_freem(seq->xwin[i]);
1326         memmove(seq->xwin, seq->xwin + nack,
1327             (L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin));
1328         memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0,
1329             nack * sizeof(*seq->xwin));
1330
1331         /*
1332          * Do slow-start/congestion avoidance windowing algorithm described
1333          * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
1334          * ACK had arrived separately.
1335          */
1336         if (seq->cwnd < seq->wmax) {
1337                 /* Handle slow start phase */
1338                 if (seq->cwnd < seq->ssth) {
1339                         seq->cwnd += nack;
1340                         nack = 0;
1341                         if (seq->cwnd > seq->ssth) {    /* into cg.av. phase */
1342                                 nack = seq->cwnd - seq->ssth;
1343                                 seq->cwnd = seq->ssth;
1344                         }
1345                 }
1346
1347                 /* Handle congestion avoidance phase */
1348                 if (seq->cwnd >= seq->ssth) {
1349                         seq->acks += nack;
1350                         while (seq->acks >= seq->cwnd) {
1351                                 seq->acks -= seq->cwnd;
1352                                 if (seq->cwnd < seq->wmax)
1353                                         seq->cwnd++;
1354                         }
1355                 }
1356         }
1357
1358         /* Stop xmit timer */
1359         if (callout_active(&seq->rack_timer))
1360                 (void )callout_stop(&seq->rack_timer);
1361
1362         /* If transmit queue is empty, we're done for now */
1363         if (seq->xwin[0] == NULL)
1364                 return;
1365
1366         /* Start restransmit timer again */
1367         callout_reset(&seq->rack_timer, hz, ng_l2tp_seq_rack_timeout,
1368             priv->node);
1369
1370         /*
1371          * Send more packets, trying to keep peer's receive window full.
1372          * Make copy of everything we need before lock release.
1373          */
1374         ns = seq->ns;
1375         j = 0;
1376         while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd
1377             && seq->xwin[i] != NULL) {
1378                 xwin[j++] = seq->xwin[i];
1379                 seq->ns++;
1380         }
1381
1382         /*
1383          * Send prepared.
1384          * If there is a memory error, pretend packet was sent, as it
1385          * will get retransmitted later anyway.
1386          */
1387         for (i = 0; i < j; i++) {
1388                 struct mbuf     *m;
1389                 if ((m = L2TP_COPY_MBUF(xwin[i], M_NOWAIT)) == NULL)
1390                         priv->stats.memoryFailures++;
1391                 else {
1392                         ng_l2tp_xmit_ctrl(priv, m, ns);
1393                         SEQ_LOCK(seq);
1394                 }
1395                 ns++;
1396         }
1397 }
1398
1399 /*
1400  * Handle an ack timeout. We have an outstanding ack that we
1401  * were hoping to piggy-back, but haven't, so send a ZLB.
1402  */
1403 static void
1404 ng_l2tp_seq_xack_timeout(void *arg)
1405 {
1406         const node_p node = arg;
1407         const priv_p priv = NG_NODE_PRIVATE(node);
1408         struct epoch_tracker et;
1409         struct l2tp_seq *const seq = &priv->seq;
1410
1411         SEQ_LOCK_ASSERT(seq);
1412         MPASS(!callout_pending(&seq->xack_timer));
1413         MPASS(callout_active(&seq->xack_timer));
1414
1415         NET_EPOCH_ENTER(et);
1416         CURVNET_SET(node->nd_vnet);
1417         /* Send a ZLB */
1418         ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1419         CURVNET_RESTORE();
1420         NET_EPOCH_EXIT(et);
1421
1422         /* callout_deactivate() is not needed here
1423             as callout_stop() was called by ng_l2tp_xmit_ctrl() */
1424 }
1425
1426 /*
1427  * Handle a transmit timeout. The peer has failed to respond
1428  * with an ack for our packet, so retransmit it.
1429  */
1430 static void
1431 ng_l2tp_seq_rack_timeout(void *arg)
1432 {
1433         const node_p node = arg;
1434         const priv_p priv = NG_NODE_PRIVATE(node);
1435         struct epoch_tracker et;
1436         struct l2tp_seq *const seq = &priv->seq;
1437         struct mbuf *m;
1438         u_int delay;
1439
1440         SEQ_LOCK_ASSERT(seq);
1441         MPASS(seq->xwin[0]);
1442         MPASS(!callout_pending(&seq->rack_timer));
1443         MPASS(callout_active(&seq->rack_timer));
1444
1445         NET_EPOCH_ENTER(et);
1446         CURVNET_SET(node->nd_vnet);
1447
1448         priv->stats.xmitRetransmits++;
1449
1450         /* Have we reached the retransmit limit? If so, notify owner. */
1451         if (seq->rexmits++ >= priv->conf.rexmit_max)
1452                 ng_l2tp_seq_failure(priv);
1453
1454         /* Restart timer, this time with an increased delay */
1455         delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
1456         if (delay > priv->conf.rexmit_max_to)
1457                 delay = priv->conf.rexmit_max_to;
1458         callout_reset(&seq->rack_timer, hz * delay, ng_l2tp_seq_rack_timeout,
1459             node);
1460
1461         /* Do slow-start/congestion algorithm windowing algorithm */
1462         seq->ns = seq->rack;
1463         seq->ssth = (seq->cwnd + 1) / 2;
1464         seq->cwnd = 1;
1465         seq->acks = 0;
1466
1467         /* Retransmit oldest unack'd packet */
1468         m = L2TP_COPY_MBUF(seq->xwin[0], M_NOWAIT);
1469         if (m == NULL) {
1470                 SEQ_UNLOCK(seq);
1471                 priv->stats.memoryFailures++;
1472         } else
1473                 ng_l2tp_xmit_ctrl(priv, m, seq->ns++);
1474
1475         CURVNET_RESTORE();
1476         NET_EPOCH_EXIT(et);
1477
1478         /* callout_deactivate() is not needed here
1479             as ng_callout() is getting called each time */
1480 }
1481
1482 /*
1483  * Transmit a control stream packet, payload optional.
1484  * The transmit sequence number is not incremented.
1485  * Requires seq lock, returns unlocked.
1486  */
1487 static int
1488 ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns)
1489 {
1490         struct l2tp_seq *const seq = &priv->seq;
1491         uint8_t *p;
1492         uint16_t nr, session_id = 0;
1493         int error;
1494
1495         SEQ_LOCK_ASSERT(seq);
1496
1497         /* Stop ack timer: we're sending an ack with this packet.
1498            Doing this before to keep state predictable after error. */
1499         if (callout_active(&seq->xack_timer))
1500                 (void )callout_stop(&seq->xack_timer);
1501
1502         nr = seq->xack = seq->nr;
1503
1504         SEQ_UNLOCK(seq);
1505
1506         /* If no mbuf passed, send an empty packet (ZLB) */
1507         if (m == NULL) {
1508                 /* Create a new mbuf for ZLB packet */
1509                 MGETHDR(m, M_NOWAIT, MT_DATA);
1510                 if (m == NULL) {
1511                         priv->stats.memoryFailures++;
1512                         return (ENOBUFS);
1513                 }
1514                 m->m_len = m->m_pkthdr.len = 12;
1515                 m->m_pkthdr.rcvif = NULL;
1516                 priv->stats.xmitZLBs++;
1517         } else {
1518                 /* Strip off session ID */
1519                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
1520                         priv->stats.memoryFailures++;
1521                         return (ENOBUFS);
1522                 }
1523                 session_id = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
1524
1525                 /* Make room for L2TP header */
1526                 M_PREPEND(m, 10, M_NOWAIT);     /* - 2 + 12 = 10 */
1527                 if (m == NULL) {
1528                         priv->stats.memoryFailures++;
1529                         return (ENOBUFS);
1530                 }
1531
1532                 /*
1533                  * The below requires 12 contiguous bytes for the L2TP header
1534                  * to be written into.
1535                  */
1536                 m = m_pullup(m, 12);
1537                 if (m == NULL) {
1538                         priv->stats.memoryFailures++;
1539                         return (ENOBUFS);
1540                 }
1541         }
1542
1543         /* Fill in L2TP header */
1544         p = mtod(m, u_int8_t *);
1545         p[0] = L2TP_CTRL_HDR >> 8;
1546         p[1] = L2TP_CTRL_HDR & 0xff;
1547         p[2] = m->m_pkthdr.len >> 8;
1548         p[3] = m->m_pkthdr.len & 0xff;
1549         p[4] = priv->conf.peer_id >> 8;
1550         p[5] = priv->conf.peer_id & 0xff;
1551         p[6] = session_id >> 8;
1552         p[7] = session_id & 0xff;
1553         p[8] = ns >> 8;
1554         p[9] = ns & 0xff;
1555         p[10] = nr >> 8;
1556         p[11] = nr & 0xff;
1557
1558         /* Update sequence number info and stats */
1559         priv->stats.xmitPackets++;
1560         priv->stats.xmitOctets += m->m_pkthdr.len;
1561
1562         /* Send packet */
1563         NG_SEND_DATA_ONLY(error, priv->lower, m);
1564         return (error);
1565 }
1566
1567 #ifdef INVARIANTS
1568 /*
1569  * Sanity check sequence number state.
1570  */
1571 static void
1572 ng_l2tp_seq_check(struct l2tp_seq *seq)
1573 {
1574         int self_unack, peer_unack;
1575         int i;
1576
1577 #define CHECK(p)        KASSERT((p), ("%s: not: %s", __func__, #p))
1578
1579         SEQ_LOCK_ASSERT(seq);
1580
1581         self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack);
1582         peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack);
1583         CHECK(seq->wmax <= L2TP_MAX_XWIN);
1584         CHECK(seq->cwnd >= 1);
1585         CHECK(seq->cwnd <= seq->wmax);
1586         CHECK(seq->ssth >= 1);
1587         CHECK(seq->ssth <= seq->wmax);
1588         if (seq->cwnd < seq->ssth)
1589                 CHECK(seq->acks == 0);
1590         else
1591                 CHECK(seq->acks <= seq->cwnd);
1592         CHECK(self_unack >= 0);
1593         CHECK(peer_unack >= 0);
1594         CHECK(peer_unack <= seq->wmax);
1595         CHECK((self_unack == 0) ^ callout_active(&seq->xack_timer));
1596         CHECK((peer_unack == 0) ^ callout_active(&seq->rack_timer));
1597         for (i = 0; i < peer_unack; i++)
1598                 CHECK(seq->xwin[i] != NULL);
1599         for ( ; i < seq->cwnd; i++)         /* verify peer's recv window full */
1600                 CHECK(seq->xwin[i] == NULL);
1601
1602 #undef CHECK
1603 }
1604 #endif  /* INVARIANTS */