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         priv = kmalloc(sizeof(*priv), M_NETGRAPH_L2TP,
 369                        M_WAITOK | M_NULLOK | M_ZERO);
 370         if (priv == NULL)
 371                 return (ENOMEM);
 372         NG_NODE_SET_PRIVATE(node, priv);
 373         priv->node = node;
 374
 375         /* Apply a semi-reasonable default configuration */
 376         priv->conf.peer_win = 1;
 377         priv->conf.rexmit_max = L2TP_MAX_REXMIT;
 378         priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO;
 379
 380         /* Initialize sequence number state */
 381         ng_l2tp_seq_init(priv);
 382
 383         for (i = 0; i < SESSHASHSIZE; i++)
 384             LIST_INIT(&priv->sesshash[i]);
 385
 386         /* Done */
 387         return (0);
 388 }
 389
 390 /*
 391  * Give our OK for a hook to be added.
 392  */
 393 static int
 394 ng_l2tp_newhook(node_p node, hook_p hook, const char *name)
 395 {
 396         const priv_p priv = NG_NODE_PRIVATE(node);
 397
 398         /* Check hook name */
 399         if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) {
 400                 if (priv->ctrl != NULL)
 401                         return (EISCONN);
 402                 priv->ctrl = hook;
 403                 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_ctrl);
 404         } else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) {
 405                 if (priv->lower != NULL)
 406                         return (EISCONN);
 407                 priv->lower = hook;
 408                 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_lower);
 409         } else {
 410                 static const char hexdig[16] = "0123456789abcdef";
 411                 u_int16_t session_id;
 412                 hookpriv_p hpriv;
 413                 uint16_t hash;
 414                 const char *hex;
 415                 int i;
 416                 int j;
 417
 418                 /* Parse hook name to get session ID */
 419                 if (strncmp(name, NG_L2TP_HOOK_SESSION_P,
 420                     sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0)
 421                         return (EINVAL);
 422                 hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1;
 423                 for (session_id = i = 0; i < 4; i++) {
 424                         for (j = 0; j < 16 && hex[i] != hexdig[j]; j++);
 425                         if (j == 16)
 426                                 return (EINVAL);
 427                         session_id = (session_id << 4) | j;
 428                 }
 429                 if (hex[i] != '\0')
 430                         return (EINVAL);
 431
 432                 /* Create hook private structure */
 433                 hpriv = kmalloc(sizeof(*hpriv), M_NETGRAPH_L2TP,
 434                                 M_WAITOK | M_NULLOK | M_ZERO);
 435                 if (hpriv == NULL)
 436                         return (ENOMEM);
 437                 hpriv->conf.session_id = htons(session_id);
 438                 hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ;
 439                 hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ;
 440                 hpriv->hook = hook;
 441                 NG_HOOK_SET_PRIVATE(hook, hpriv);
 442                 hash = SESSHASH(hpriv->conf.session_id);
 443                 LIST_INSERT_HEAD(&priv->sesshash[hash], hpriv, sessions);
 444         }
 445
 446         /* Done */
 447         return (0);
 448 }
 449
 450 /*
 451  * Receive a control message.
 452  */
 453 static int
 454 ng_l2tp_rcvmsg(node_p node, item_p item, hook_p lasthook)
 455 {
 456         const priv_p priv = NG_NODE_PRIVATE(node);
 457         struct ng_mesg *resp = NULL;
 458         struct ng_mesg *msg;
 459         int error = 0;
 460
 461         NGI_GET_MSG(item, msg);
 462         switch (msg->header.typecookie) {
 463         case NGM_L2TP_COOKIE:
 464                 switch (msg->header.cmd) {
 465                 case NGM_L2TP_SET_CONFIG:
 466                     {
 467                         struct ng_l2tp_config *const conf =
 468                                 (struct ng_l2tp_config *)msg->data;
 469
 470                         /* Check for invalid or illegal config */
 471                         if (msg->header.arglen != sizeof(*conf)) {
 472                                 error = EINVAL;
 473                                 break;
 474                         }
 475                         conf->enabled = !!conf->enabled;
 476                         conf->match_id = !!conf->match_id;
 477                         conf->tunnel_id = htons(conf->tunnel_id);
 478                         conf->peer_id = htons(conf->peer_id);
 479                         if (priv->conf.enabled
 480                             && ((priv->conf.tunnel_id != 0
 481                                && conf->tunnel_id != priv->conf.tunnel_id)
 482                               || ((priv->conf.peer_id != 0
 483                                && conf->peer_id != priv->conf.peer_id)))) {
 484                                 error = EBUSY;
 485                                 break;
 486                         }
 487
 488                         /* Save calling node as failure target */
 489                         priv->ftarget = NGI_RETADDR(item);
 490
 491                         /* Adjust sequence number state */
 492                         if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0)
 493                                 break;
 494
 495                         /* Update node's config */
 496                         priv->conf = *conf;
 497                         break;
 498                     }
 499                 case NGM_L2TP_GET_CONFIG:
 500                     {
 501                         struct ng_l2tp_config *conf;
 502
 503                         NG_MKRESPONSE(resp, msg, sizeof(*conf), M_WAITOK | M_NULLOK);
 504                         if (resp == NULL) {
 505                                 error = ENOMEM;
 506                                 break;
 507                         }
 508                         conf = (struct ng_l2tp_config *)resp->data;
 509                         *conf = priv->conf;
 510
 511                         /* Put ID's in host order */
 512                         conf->tunnel_id = ntohs(conf->tunnel_id);
 513                         conf->peer_id = ntohs(conf->peer_id);
 514                         break;
 515                     }
 516                 case NGM_L2TP_SET_SESS_CONFIG:
 517                     {
 518                         struct ng_l2tp_sess_config *const conf =
 519                             (struct ng_l2tp_sess_config *)msg->data;
 520                         hookpriv_p hpriv;
 521
 522                         /* Check for invalid or illegal config. */
 523                         if (msg->header.arglen != sizeof(*conf)) {
 524                                 error = EINVAL;
 525                                 break;
 526                         }
 527
 528                         /* Put ID's in network order */
 529                         conf->session_id = htons(conf->session_id);
 530                         conf->peer_id = htons(conf->peer_id);
 531
 532                         /* Find matching hook */
 533                         hpriv = ng_l2tp_find_session(priv, conf->session_id);
 534                         if (hpriv == NULL) {
 535                                 error = ENOENT;
 536                                 break;
 537                         }
 538
 539                         /* Update hook's config */
 540                         hpriv->conf = *conf;
 541                         break;
 542                     }
 543                 case NGM_L2TP_GET_SESS_CONFIG:
 544                     {
 545                         struct ng_l2tp_sess_config *conf;
 546                         u_int16_t session_id;
 547                         hookpriv_p hpriv;
 548
 549                         /* Get session ID */
 550                         if (msg->header.arglen != sizeof(session_id)) {
 551                                 error = EINVAL;
 552                                 break;
 553                         }
 554                         memcpy(&session_id, msg->data, 2);
 555                         session_id = htons(session_id);
 556
 557                         /* Find matching hook */
 558                         hpriv = ng_l2tp_find_session(priv, session_id);
 559                         if (hpriv == NULL) {
 560                                 error = ENOENT;
 561                                 break;
 562                         }
 563
 564                         /* Send response */
 565                         NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_WAITOK | M_NULLOK);
 566                         if (resp == NULL) {
 567                                 error = ENOMEM;
 568                                 break;
 569                         }
 570                         conf = (struct ng_l2tp_sess_config *)resp->data;
 571                         *conf = hpriv->conf;
 572
 573                         /* Put ID's in host order */
 574                         conf->session_id = ntohs(conf->session_id);
 575                         conf->peer_id = ntohs(conf->peer_id);
 576                         break;
 577                     }
 578                 case NGM_L2TP_GET_STATS:
 579                 case NGM_L2TP_CLR_STATS:
 580                 case NGM_L2TP_GETCLR_STATS:
 581                     {
 582                         if (msg->header.cmd != NGM_L2TP_CLR_STATS) {
 583                                 NG_MKRESPONSE(resp, msg,
 584                                     sizeof(priv->stats), M_WAITOK | M_NULLOK);
 585                                 if (resp == NULL) {
 586                                         error = ENOMEM;
 587                                         break;
 588                                 }
 589                                 memcpy(resp->data,
 590                                     &priv->stats, sizeof(priv->stats));
 591                         }
 592                         if (msg->header.cmd != NGM_L2TP_GET_STATS)
 593                                 memset(&priv->stats, 0, sizeof(priv->stats));
 594                         break;
 595                     }
 596                 case NGM_L2TP_GET_SESSION_STATS:
 597                 case NGM_L2TP_CLR_SESSION_STATS:
 598                 case NGM_L2TP_GETCLR_SESSION_STATS:
 599                     {
 600                         uint16_t session_id;
 601                         hookpriv_p hpriv;
 602
 603                         /* Get session ID. */
 604                         if (msg->header.arglen != sizeof(session_id)) {
 605                                 error = EINVAL;
 606                                 break;
 607                         }
 608                         bcopy(msg->data, &session_id, sizeof(uint16_t));
 609                         session_id = htons(session_id);
 610
 611                         /* Find matching hook. */
 612                         hpriv = ng_l2tp_find_session(priv, session_id);
 613                         if (hpriv == NULL) {
 614                                 error = ENOENT;
 615                                 break;
 616                         }
 617
 618                         if (msg->header.cmd != NGM_L2TP_CLR_SESSION_STATS) {
 619                                 NG_MKRESPONSE(resp, msg,
 620                                     sizeof(hpriv->stats), M_WAITOK | M_NULLOK);
 621                                 if (resp == NULL) {
 622                                         error = ENOMEM;
 623                                         break;
 624                                 }
 625                                 bcopy(&hpriv->stats, resp->data,
 626                                         sizeof(hpriv->stats));
 627                         }
 628                         if (msg->header.cmd != NGM_L2TP_GET_SESSION_STATS)
 629                                 bzero(&hpriv->stats, sizeof(hpriv->stats));
 630                         break;
 631                     }
 632                 case NGM_L2TP_SET_SEQ:
 633                     {
 634                         struct ng_l2tp_seq_config *const conf =
 635                                 (struct ng_l2tp_seq_config *)msg->data;
 636
 637                         /* Check for invalid or illegal seq config. */
 638                         if (msg->header.arglen != sizeof(*conf)) {
 639                                 error = EINVAL;
 640                                 break;
 641                         }
 642                         conf->ns = htons(conf->ns);
 643                         conf->nr = htons(conf->nr);
 644                         conf->rack = htons(conf->rack);
 645                         conf->xack = htons(conf->xack);
 646
 647                         /* Set sequence numbers. */
 648                         error = ng_l2tp_seq_set(priv, conf);
 649                         break;
 650                     }
 651                 default:
 652                         error = EINVAL;
 653                         break;
 654                 }
 655                 break;
 656         default:
 657                 error = EINVAL;
 658                 break;
 659         }
 660
 661         /* Done */
 662         NG_RESPOND_MSG(error, node, item, resp);
 663         NG_FREE_MSG(msg);
 664         return (error);
 665 }
 666
 667 /*
 668  * Destroy node
 669  */
 670 static int
 671 ng_l2tp_shutdown(node_p node)
 672 {
 673         const priv_p priv = NG_NODE_PRIVATE(node);
 674         struct l2tp_seq *const seq = &priv->seq;
 675
 676         /* Sanity check */
 677         L2TP_SEQ_CHECK(seq);
 678
 679         /* Reset sequence number state */
 680         ng_l2tp_seq_reset(priv);
 681
 682         /* Free private data if neither timer is running */
 683         ng_uncallout(&seq->rack_timer, node);
 684         ng_uncallout(&seq->xack_timer, node);
 685
 686         mtx_destroy(&seq->mtx);
 687
 688         kfree(priv, M_NETGRAPH_L2TP);
 689
 690         /* Unref node */
 691         NG_NODE_UNREF(node);
 692         return (0);
 693 }
 694
 695 /*
 696  * Hook disconnection
 697  */
 698 static int
 699 ng_l2tp_disconnect(hook_p hook)
 700 {
 701         const node_p node = NG_HOOK_NODE(hook);
 702         const priv_p priv = NG_NODE_PRIVATE(node);
 703
 704         /* Zero out hook pointer */
 705         if (hook == priv->ctrl)
 706                 priv->ctrl = NULL;
 707         else if (hook == priv->lower)
 708                 priv->lower = NULL;
 709         else {
 710                 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
 711                 LIST_REMOVE(hpriv, sessions);
 712                 kfree(hpriv, M_NETGRAPH_L2TP);
 713                 NG_HOOK_SET_PRIVATE(hook, NULL);
 714         }
 715
 716         /* Go away if no longer connected to anything */
 717         if (NG_NODE_NUMHOOKS(node) == 0 && NG_NODE_IS_VALID(node))
 718                 ng_rmnode_self(node);
 719         return (0);
 720 }
 721
 722 /*************************************************************************
 723                         INTERNAL FUNCTIONS
 724 *************************************************************************/
 725
 726 /*
 727  * Find the hook with a given session ID (in network order).
 728  */
 729 static hookpriv_p
 730 ng_l2tp_find_session(priv_p privp, u_int16_t sid)
 731 {
 732         uint16_t        hash = SESSHASH(sid);
 733         hookpriv_p      hpriv = NULL;
 734
 735         LIST_FOREACH(hpriv, &privp->sesshash[hash], sessions) {
 736                 if (hpriv->conf.session_id == sid)
 737                         break;
 738         }
 739
 740         return (hpriv);
 741 }
 742
 743 /*
 744  * Reset a hook's session state.
 745  */
 746 static int
 747 ng_l2tp_reset_session(hook_p hook, void *arg)
 748 {
 749         const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
 750
 751         if (hpriv != NULL) {
 752                 hpriv->conf.control_dseq = 0;
 753                 hpriv->conf.enable_dseq = 0;
 754                 bzero(&hpriv->conf, sizeof(struct ng_l2tp_session_stats));
 755                 hpriv->nr = 0;
 756                 hpriv->ns = 0;
 757         }
 758         return (-1);
 759 }
 760
 761 /*
 762  * Handle an incoming frame from below.
 763  */
 764 static int
 765 ng_l2tp_rcvdata_lower(hook_p h, item_p item)
 766 {
 767         static const u_int16_t req_bits[2][2] = {
 768                 { L2TP_DATA_0BITS, L2TP_DATA_1BITS },
 769                 { L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
 770         };
 771         const node_p node = NG_HOOK_NODE(h);
 772         const priv_p priv = NG_NODE_PRIVATE(node);
 773         hookpriv_p hpriv = NULL;
 774         hook_p hook = NULL;
 775         u_int16_t ids[2];
 776         struct mbuf *m;
 777         u_int16_t hdr;
 778         u_int16_t ns;
 779         u_int16_t nr;
 780         int is_ctrl;
 781         int error;
 782         int len, plen;
 783
 784         /* Sanity check */
 785         L2TP_SEQ_CHECK(&priv->seq);
 786
 787         /* If not configured, reject */
 788         if (!priv->conf.enabled) {
 789                 NG_FREE_ITEM(item);
 790                 ERROUT(ENXIO);
 791         }
 792
 793         /* Grab mbuf */
 794         NGI_GET_M(item, m);
 795
 796         /* Remember full packet length; needed for per session accounting. */
 797         plen = m->m_pkthdr.len;
 798
 799         /* Update stats */
 800         priv->stats.recvPackets++;
 801         priv->stats.recvOctets += plen;
 802
 803         /* Get initial header */
 804         if (m->m_pkthdr.len < 6) {
 805                 priv->stats.recvRunts++;
 806                 NG_FREE_ITEM(item);
 807                 NG_FREE_M(m);
 808                 ERROUT(EINVAL);
 809         }
 810         if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 811                 priv->stats.memoryFailures++;
 812                 NG_FREE_ITEM(item);
 813                 ERROUT(EINVAL);
 814         }
 815         hdr = ntohs(*mtod(m, u_int16_t *));
 816         m_adj(m, 2);
 817
 818         /* Check required header bits and minimum length */
 819         is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
 820         if ((hdr & req_bits[is_ctrl][0]) != 0
 821             || (~hdr & req_bits[is_ctrl][1]) != 0) {
 822                 priv->stats.recvInvalid++;
 823                 NG_FREE_ITEM(item);
 824                 NG_FREE_M(m);
 825                 ERROUT(EINVAL);
 826         }
 827         if (m->m_pkthdr.len < 4                         /* tunnel, session id */
 828             + (2 * ((hdr & L2TP_HDR_LEN) != 0))         /* length field */
 829             + (4 * ((hdr & L2TP_HDR_SEQ) != 0))         /* seq # fields */
 830             + (2 * ((hdr & L2TP_HDR_OFF) != 0))) {      /* offset field */
 831                 priv->stats.recvRunts++;
 832                 NG_FREE_ITEM(item);
 833                 NG_FREE_M(m);
 834                 ERROUT(EINVAL);
 835         }
 836
 837         /* Get and validate length field if present */
 838         if ((hdr & L2TP_HDR_LEN) != 0) {
 839                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 840                         priv->stats.memoryFailures++;
 841                         NG_FREE_ITEM(item);
 842                         ERROUT(EINVAL);
 843                 }
 844                 len = (u_int16_t)ntohs(*mtod(m, u_int16_t *)) - 4;
 845                 m_adj(m, 2);
 846                 if (len < 0 || len > m->m_pkthdr.len) {
 847                         priv->stats.recvInvalid++;
 848                         NG_FREE_ITEM(item);
 849                         NG_FREE_M(m);
 850                         ERROUT(EINVAL);
 851                 }
 852                 if (len < m->m_pkthdr.len)              /* trim extra bytes */
 853                         m_adj(m, -(m->m_pkthdr.len - len));
 854         }
 855
 856         /* Get tunnel ID and session ID */
 857         if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
 858                 priv->stats.memoryFailures++;
 859                 NG_FREE_ITEM(item);
 860                 ERROUT(EINVAL);
 861         }
 862         memcpy(ids, mtod(m, u_int16_t *), 4);
 863         m_adj(m, 4);
 864
 865         /* Check tunnel ID */
 866         if (ids[0] != priv->conf.tunnel_id
 867             && (priv->conf.match_id || ids[0] != 0)) {
 868                 priv->stats.recvWrongTunnel++;
 869                 NG_FREE_ITEM(item);
 870                 NG_FREE_M(m);
 871                 ERROUT(EADDRNOTAVAIL);
 872         }
 873
 874         /* Check session ID (for data packets only) */
 875         if ((hdr & L2TP_HDR_CTRL) == 0) {
 876                 hpriv = ng_l2tp_find_session(priv, ids[1]);
 877                 if (hpriv == NULL) {
 878                         priv->stats.recvUnknownSID++;
 879                         NG_FREE_ITEM(item);
 880                         NG_FREE_M(m);
 881                         ERROUT(ENOTCONN);
 882                 }
 883                 hook = hpriv->hook;
 884         }
 885
 886         /* Get Ns, Nr fields if present */
 887         if ((hdr & L2TP_HDR_SEQ) != 0) {
 888                 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
 889                         priv->stats.memoryFailures++;
 890                         NG_FREE_ITEM(item);
 891                         ERROUT(EINVAL);
 892                 }
 893                 memcpy(&ns, &mtod(m, u_int16_t *)[0], 2);
 894                 ns = ntohs(ns);
 895                 memcpy(&nr, &mtod(m, u_int16_t *)[1], 2);
 896                 nr = ntohs(nr);
 897                 m_adj(m, 4);
 898         }
 899
 900         /* Strip offset padding if present */
 901         if ((hdr & L2TP_HDR_OFF) != 0) {
 902                 u_int16_t offset;
 903
 904                 /* Get length of offset padding */
 905                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 906                         priv->stats.memoryFailures++;
 907                         NG_FREE_ITEM(item);
 908                         ERROUT(EINVAL);
 909                 }
 910                 memcpy(&offset, mtod(m, u_int16_t *), 2);
 911                 offset = ntohs(offset);
 912
 913                 /* Trim offset padding */
 914                 if ((2+offset) > m->m_pkthdr.len) {
 915                         priv->stats.recvInvalid++;
 916                         NG_FREE_ITEM(item);
 917                         NG_FREE_M(m);
 918                         ERROUT(EINVAL);
 919                 }
 920                 m_adj(m, 2+offset);
 921         }
 922
 923         /* Handle control packets */
 924         if ((hdr & L2TP_HDR_CTRL) != 0) {
 925                 struct l2tp_seq *const seq = &priv->seq;
 926
 927                 /* Handle receive ack sequence number Nr */
 928                 ng_l2tp_seq_recv_nr(priv, nr);
 929
 930                 /* Discard ZLB packets */
 931                 if (m->m_pkthdr.len == 0) {
 932                         priv->stats.recvZLBs++;
 933                         NG_FREE_ITEM(item);
 934                         NG_FREE_M(m);
 935                         ERROUT(0);
 936                 }
 937
 938                 mtx_lock(&seq->mtx);
 939                 /*
 940                  * If not what we expect or we are busy, drop packet and
 941                  * send an immediate ZLB ack.
 942                  */
 943                 if (ns != seq->nr || seq->inproc) {
 944                         if (L2TP_SEQ_DIFF(ns, seq->nr) <= 0)
 945                                 priv->stats.recvDuplicates++;
 946                         else
 947                                 priv->stats.recvOutOfOrder++;
 948                         mtx_unlock(&seq->mtx);
 949                         ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
 950                         NG_FREE_ITEM(item);
 951                         NG_FREE_M(m);
 952                         ERROUT(0);
 953                 }
 954                 /*
 955                  * Until we deliver this packet we can't receive next one as
 956                  * we have no information for sending ack.
 957                  */
 958                 seq->inproc = 1;
 959                 mtx_unlock(&seq->mtx);
 960
 961                 /* Prepend session ID to packet. */
 962                 M_PREPEND(m, 2, MB_DONTWAIT);
 963                 if (m == NULL) {
 964                         seq->inproc = 0;
 965                         priv->stats.memoryFailures++;
 966                         NG_FREE_ITEM(item);
 967                         ERROUT(ENOBUFS);
 968                 }
 969                 memcpy(mtod(m, u_int16_t *), &ids[1], 2);
 970
 971                 /* Deliver packet to upper layers */
 972                 NG_FWD_NEW_DATA(error, item, priv->ctrl, m);
 973
 974                 mtx_lock(&seq->mtx);
 975                 /* Ready to process next packet. */
 976                 seq->inproc = 0;
 977
 978                 /* If packet was successfully delivered send ack. */
 979                 if (error == 0) {
 980                         /* Update recv sequence number */
 981                         seq->nr++;
 982                         /* Start receive ack timer, if not already running */
 983                         if (!callout_active(&seq->xack_timer)) {
 984                                 ng_callout(&seq->xack_timer, priv->node, NULL,
 985                                     L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout,
 986                                     NULL, 0);
 987                         }
 988                 }
 989                 mtx_unlock(&seq->mtx);
 990
 991                 ERROUT(error);
 992         }
 993
 994         /* Per session packet, account it. */
 995         hpriv->stats.recvPackets++;
 996         hpriv->stats.recvOctets += plen;
 997
 998         /* Follow peer's lead in data sequencing, if configured to do so */
 999         if (!hpriv->conf.control_dseq)
1000                 hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0);
1001
1002         /* Handle data sequence numbers if present and enabled */
1003         if ((hdr & L2TP_HDR_SEQ) != 0) {
1004                 if (hpriv->conf.enable_dseq
1005                     && L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) {
1006                         NG_FREE_ITEM(item);     /* duplicate or out of order */
1007                         NG_FREE_M(m);
1008                         priv->stats.recvDataDrops++;
1009                         ERROUT(0);
1010                 }
1011                 hpriv->nr = ns + 1;
1012         }
1013
1014         /* Drop empty data packets */
1015         if (m->m_pkthdr.len == 0) {
1016                 NG_FREE_ITEM(item);
1017                 NG_FREE_M(m);
1018                 ERROUT(0);
1019         }
1020
1021         /* Deliver data */
1022         NG_FWD_NEW_DATA(error, item, hook, m);
1023 done:
1024         /* Done */
1025         L2TP_SEQ_CHECK(&priv->seq);
1026         return (error);
1027 }
1028
1029 /*
1030  * Handle an outgoing control frame.
1031  */
1032 static int
1033 ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item)
1034 {
1035         const node_p node = NG_HOOK_NODE(hook);
1036         const priv_p priv = NG_NODE_PRIVATE(node);
1037         struct l2tp_seq *const seq = &priv->seq;
1038         struct mbuf *m;
1039         int error;
1040         int i;
1041         u_int16_t       ns;
1042
1043         /* Sanity check */
1044         L2TP_SEQ_CHECK(&priv->seq);
1045
1046         /* If not configured, reject */
1047         if (!priv->conf.enabled) {
1048                 NG_FREE_ITEM(item);
1049                 ERROUT(ENXIO);
1050         }
1051
1052         /* Grab mbuf and discard other stuff XXX */
1053         NGI_GET_M(item, m);
1054         NG_FREE_ITEM(item);
1055
1056         /* Packet should have session ID prepended */
1057         if (m->m_pkthdr.len < 2) {
1058                 priv->stats.xmitInvalid++;
1059                 m_freem(m);
1060                 ERROUT(EINVAL);
1061         }
1062
1063         /* Check max length */
1064         if (m->m_pkthdr.len >= 0x10000 - 14) {
1065                 priv->stats.xmitTooBig++;
1066                 m_freem(m);
1067                 ERROUT(EOVERFLOW);
1068         }
1069
1070         mtx_lock(&seq->mtx);
1071
1072         /* Find next empty slot in transmit queue */
1073         for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
1074         if (i == L2TP_MAX_XWIN) {
1075                 mtx_unlock(&seq->mtx);
1076                 priv->stats.xmitDrops++;
1077                 m_freem(m);
1078                 ERROUT(ENOBUFS);
1079         }
1080         seq->xwin[i] = m;
1081
1082         /* If peer's receive window is already full, nothing else to do */
1083         if (i >= seq->cwnd) {
1084                 mtx_unlock(&seq->mtx);
1085                 ERROUT(0);
1086         }
1087
1088         /* Start retransmit timer if not already running */
1089         if (!callout_active(&seq->rack_timer))
1090                 ng_callout(&seq->rack_timer, node, NULL,
1091                     hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1092
1093         ns = seq->ns++;
1094
1095         mtx_unlock(&seq->mtx);
1096
1097         /* Copy packet */
1098         if ((m = L2TP_COPY_MBUF(m, MB_DONTWAIT)) == NULL) {
1099                 priv->stats.memoryFailures++;
1100                 ERROUT(ENOBUFS);
1101         }
1102
1103         /* Send packet and increment xmit sequence number */
1104         error = ng_l2tp_xmit_ctrl(priv, m, ns);
1105 done:
1106         /* Done */
1107         L2TP_SEQ_CHECK(&priv->seq);
1108         return (error);
1109 }
1110
1111 /*
1112  * Handle an outgoing data frame.
1113  */
1114 static int
1115 ng_l2tp_rcvdata(hook_p hook, item_p item)
1116 {
1117         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
1118         const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
1119         struct mbuf *m;
1120         u_int16_t hdr;
1121         int error;
1122         int i = 1;
1123
1124         /* Sanity check */
1125         L2TP_SEQ_CHECK(&priv->seq);
1126
1127         /* If not configured, reject */
1128         if (!priv->conf.enabled) {
1129                 NG_FREE_ITEM(item);
1130                 ERROUT(ENXIO);
1131         }
1132
1133         /* Get mbuf */
1134         NGI_GET_M(item, m);
1135
1136         /* Check max length */
1137         if (m->m_pkthdr.len >= 0x10000 - 12) {
1138                 priv->stats.xmitDataTooBig++;
1139                 NG_FREE_ITEM(item);
1140                 NG_FREE_M(m);
1141                 ERROUT(EOVERFLOW);
1142         }
1143
1144         /* Prepend L2TP header */
1145         M_PREPEND(m, 6
1146             + (2 * (hpriv->conf.include_length != 0))
1147             + (4 * (hpriv->conf.enable_dseq != 0)),
1148             MB_DONTWAIT);
1149         if (m == NULL) {
1150                 priv->stats.memoryFailures++;
1151                 NG_FREE_ITEM(item);
1152                 ERROUT(ENOBUFS);
1153         }
1154         hdr = L2TP_DATA_HDR;
1155         if (hpriv->conf.include_length) {
1156                 hdr |= L2TP_HDR_LEN;
1157                 mtod(m, u_int16_t *)[i++] = htons(m->m_pkthdr.len);
1158         }
1159         mtod(m, u_int16_t *)[i++] = priv->conf.peer_id;
1160         mtod(m, u_int16_t *)[i++] = hpriv->conf.peer_id;
1161         if (hpriv->conf.enable_dseq) {
1162                 hdr |= L2TP_HDR_SEQ;
1163                 mtod(m, u_int16_t *)[i++] = htons(hpriv->ns);
1164                 mtod(m, u_int16_t *)[i++] = htons(hpriv->nr);
1165                 hpriv->ns++;
1166         }
1167         mtod(m, u_int16_t *)[0] = htons(hdr);
1168
1169         /* Update per session stats. */
1170         hpriv->stats.xmitPackets++;
1171         hpriv->stats.xmitOctets += m->m_pkthdr.len;
1172
1173         /* And the global one. */
1174         priv->stats.xmitPackets++;
1175         priv->stats.xmitOctets += m->m_pkthdr.len;
1176
1177         /* Send packet */
1178         NG_FWD_NEW_DATA(error, item, priv->lower, m);
1179 done:
1180         /* Done */
1181         L2TP_SEQ_CHECK(&priv->seq);
1182         return (error);
1183 }
1184
1185 /*
1186  * Send a message to our controlling node that we've failed.
1187  */
1188 static void
1189 ng_l2tp_seq_failure(priv_p priv)
1190 {
1191         struct ng_mesg *msg;
1192         int error;
1193
1194         NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_WAITOK | M_NULLOK);
1195         if (msg == NULL)
1196                 return;
1197         NG_SEND_MSG_ID(error, priv->node, msg, priv->ftarget, 0);
1198 }
1199
1200 /************************************************************************
1201                         SEQUENCE NUMBER HANDLING
1202 ************************************************************************/
1203
1204 /*
1205  * Initialize sequence number state.
1206  */
1207 static void
1208 ng_l2tp_seq_init(priv_p priv)
1209 {
1210         struct l2tp_seq *const seq = &priv->seq;
1211
1212         KASSERT(priv->conf.peer_win >= 1,
1213             ("%s: peer_win is zero", __func__));
1214         memset(seq, 0, sizeof(*seq));
1215         seq->cwnd = 1;
1216         seq->wmax = priv->conf.peer_win;
1217         if (seq->wmax > L2TP_MAX_XWIN)
1218                 seq->wmax = L2TP_MAX_XWIN;
1219         seq->ssth = seq->wmax;
1220         ng_callout_init(&seq->rack_timer);
1221         ng_callout_init(&seq->xack_timer);
1222         mtx_init(&seq->mtx, "ng_l2tp", NULL, MTX_DEF);
1223         L2TP_SEQ_CHECK(seq);
1224 }
1225
1226 /*
1227  * Set sequence number state as given from user.
1228  */
1229 static int
1230 ng_l2tp_seq_set(priv_p priv, const struct ng_l2tp_seq_config *conf)
1231 {
1232         struct l2tp_seq *const seq = &priv->seq;
1233
1234         /* If node is enabled, deny update to sequence numbers. */
1235         if (priv->conf.enabled)
1236                 return (EBUSY);
1237
1238         /* We only can handle the simple cases. */
1239         if (conf->xack != conf->nr || conf->ns != conf->rack)
1240                 return (EINVAL);
1241
1242         /* Set ns,nr,rack,xack parameters. */
1243         seq->ns = conf->ns;
1244         seq->nr = conf->nr;
1245         seq->rack = conf->rack;
1246         seq->xack = conf->xack;
1247
1248         return (0);
1249 }
1250
1251 /*
1252  * Adjust sequence number state accordingly after reconfiguration.
1253  */
1254 static int
1255 ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf)
1256 {
1257         struct l2tp_seq *const seq = &priv->seq;
1258         u_int16_t new_wmax;
1259
1260         /* If disabling node, reset state sequence number */
1261         if (!conf->enabled) {
1262                 ng_l2tp_seq_reset(priv);
1263                 return (0);
1264         }
1265
1266         /* Adjust peer's max recv window; it can only increase */
1267         new_wmax = conf->peer_win;
1268         if (new_wmax > L2TP_MAX_XWIN)
1269                 new_wmax = L2TP_MAX_XWIN;
1270         if (new_wmax == 0)
1271                 return (EINVAL);
1272         if (new_wmax < seq->wmax)
1273                 return (EBUSY);
1274         seq->wmax = new_wmax;
1275
1276         /* Done */
1277         return (0);
1278 }
1279
1280 /*
1281  * Reset sequence number state.
1282  */
1283 static void
1284 ng_l2tp_seq_reset(priv_p priv)
1285 {
1286         struct l2tp_seq *const seq = &priv->seq;
1287         hook_p hook;
1288         int i;
1289
1290         /* Sanity check */
1291         L2TP_SEQ_CHECK(seq);
1292
1293         /* Stop timers */
1294         ng_uncallout(&seq->rack_timer, priv->node);
1295         ng_uncallout(&seq->xack_timer, priv->node);
1296
1297         /* Free retransmit queue */
1298         for (i = 0; i < L2TP_MAX_XWIN; i++) {
1299                 if (seq->xwin[i] == NULL)
1300                         break;
1301                 m_freem(seq->xwin[i]);
1302         }
1303
1304         /* Reset session hooks' sequence number states */
1305         NG_NODE_FOREACH_HOOK(priv->node, ng_l2tp_reset_session, NULL, hook);
1306
1307         /* Reset node's sequence number state */
1308         seq->ns = 0;
1309         seq->nr = 0;
1310         seq->rack = 0;
1311         seq->xack = 0;
1312         seq->wmax = L2TP_MAX_XWIN;
1313         seq->cwnd = 1;
1314         seq->ssth = seq->wmax;
1315         seq->acks = 0;
1316         seq->rexmits = 0;
1317         bzero(seq->xwin, sizeof(seq->xwin));
1318
1319         /* Done */
1320         L2TP_SEQ_CHECK(seq);
1321 }
1322
1323 /*
1324  * Handle receipt of an acknowledgement value (Nr) from peer.
1325  */
1326 static void
1327 ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr)
1328 {
1329         struct l2tp_seq *const seq = &priv->seq;
1330         struct mbuf     *xwin[L2TP_MAX_XWIN];   /* partial local copy */
1331         int             nack;
1332         int             i, j;
1333         uint16_t        ns;
1334
1335         mtx_lock(&seq->mtx);
1336
1337         /* Verify peer's ACK is in range */
1338         if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0) {
1339                 mtx_unlock(&seq->mtx);
1340                 return;                         /* duplicate ack */
1341         }
1342         if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) {
1343                 mtx_unlock(&seq->mtx);
1344                 priv->stats.recvBadAcks++;      /* ack for packet not sent */
1345                 return;
1346         }
1347         KASSERT(nack <= L2TP_MAX_XWIN,
1348             ("%s: nack=%d > %d", __func__, nack, L2TP_MAX_XWIN));
1349
1350         /* Update receive ack stats */
1351         seq->rack = nr;
1352         seq->rexmits = 0;
1353
1354         /* Free acknowledged packets and shift up packets in the xmit queue */
1355         for (i = 0; i < nack; i++)
1356                 m_freem(seq->xwin[i]);
1357         memmove(seq->xwin, seq->xwin + nack,
1358             (L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin));
1359         memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0,
1360             nack * sizeof(*seq->xwin));
1361
1362         /*
1363          * Do slow-start/congestion avoidance windowing algorithm described
1364          * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
1365          * ACK had arrived separately.
1366          */
1367         if (seq->cwnd < seq->wmax) {
1368
1369                 /* Handle slow start phase */
1370                 if (seq->cwnd < seq->ssth) {
1371                         seq->cwnd += nack;
1372                         nack = 0;
1373                         if (seq->cwnd > seq->ssth) {    /* into cg.av. phase */
1374                                 nack = seq->cwnd - seq->ssth;
1375                                 seq->cwnd = seq->ssth;
1376                         }
1377                 }
1378
1379                 /* Handle congestion avoidance phase */
1380                 if (seq->cwnd >= seq->ssth) {
1381                         seq->acks += nack;
1382                         while (seq->acks >= seq->cwnd) {
1383                                 seq->acks -= seq->cwnd;
1384                                 if (seq->cwnd < seq->wmax)
1385                                         seq->cwnd++;
1386                         }
1387                 }
1388         }
1389
1390         /* Stop xmit timer */
1391         if (callout_active(&seq->rack_timer))
1392                 ng_uncallout(&seq->rack_timer, priv->node);
1393
1394         /* If transmit queue is empty, we're done for now */
1395         if (seq->xwin[0] == NULL) {
1396                 mtx_unlock(&seq->mtx);
1397                 return;
1398         }
1399
1400         /* Start restransmit timer again */
1401         ng_callout(&seq->rack_timer, priv->node, NULL,
1402             hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1403
1404         /*
1405          * Send more packets, trying to keep peer's receive window full.
1406          * Make copy of everything we need before lock release.
1407          */
1408         ns = seq->ns;
1409         j = 0;
1410         while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd
1411             && seq->xwin[i] != NULL) {
1412                 xwin[j++] = seq->xwin[i];
1413                 seq->ns++;
1414         }
1415
1416         mtx_unlock(&seq->mtx);
1417
1418         /*
1419          * Send prepared.
1420          * If there is a memory error, pretend packet was sent, as it
1421          * will get retransmitted later anyway.
1422          */
1423         for (i = 0; i < j; i++) {
1424                 struct mbuf     *m;
1425                 if ((m = L2TP_COPY_MBUF(xwin[i], MB_DONTWAIT)) == NULL)
1426                         priv->stats.memoryFailures++;
1427                 else
1428                         ng_l2tp_xmit_ctrl(priv, m, ns);
1429                 ns++;
1430         }
1431 }
1432
1433 /*
1434  * Handle an ack timeout. We have an outstanding ack that we
1435  * were hoping to piggy-back, but haven't, so send a ZLB.
1436  */
1437 static void
1438 ng_l2tp_seq_xack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1439 {
1440         const priv_p priv = NG_NODE_PRIVATE(node);
1441         struct l2tp_seq *const seq = &priv->seq;
1442
1443         /* Make sure callout is still active before doing anything */
1444         if (callout_pending(&seq->xack_timer) ||
1445             (!callout_active(&seq->xack_timer)))
1446                 return;
1447
1448         /* Sanity check */
1449         L2TP_SEQ_CHECK(seq);
1450
1451         /* Send a ZLB */
1452         ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1453
1454         /* callout_deactivate() is not needed here
1455             as ng_uncallout() was called by ng_l2tp_xmit_ctrl() */
1456
1457         /* Sanity check */
1458         L2TP_SEQ_CHECK(seq);
1459 }
1460
1461 /*
1462  * Handle a transmit timeout. The peer has failed to respond
1463  * with an ack for our packet, so retransmit it.
1464  */
1465 static void
1466 ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1467 {
1468         const priv_p priv = NG_NODE_PRIVATE(node);
1469         struct l2tp_seq *const seq = &priv->seq;
1470         struct mbuf *m;
1471         u_int delay;
1472
1473         /* Make sure callout is still active before doing anything */
1474         if (callout_pending(&seq->rack_timer) ||
1475             (!callout_active(&seq->rack_timer)))
1476                 return;
1477
1478         /* Sanity check */
1479         L2TP_SEQ_CHECK(seq);
1480
1481         priv->stats.xmitRetransmits++;
1482
1483         /* Have we reached the retransmit limit? If so, notify owner. */
1484         if (seq->rexmits++ >= priv->conf.rexmit_max)
1485                 ng_l2tp_seq_failure(priv);
1486
1487         /* Restart timer, this time with an increased delay */
1488         delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
1489         if (delay > priv->conf.rexmit_max_to)
1490                 delay = priv->conf.rexmit_max_to;
1491         ng_callout(&seq->rack_timer, node, NULL,
1492             hz * delay, ng_l2tp_seq_rack_timeout, NULL, 0);
1493
1494         /* Do slow-start/congestion algorithm windowing algorithm */
1495         seq->ns = seq->rack;
1496         seq->ssth = (seq->cwnd + 1) / 2;
1497         seq->cwnd = 1;
1498         seq->acks = 0;
1499
1500         /* Retransmit oldest unack'd packet */
1501         if ((m = L2TP_COPY_MBUF(seq->xwin[0], MB_DONTWAIT)) == NULL)
1502                 priv->stats.memoryFailures++;
1503         else
1504                 ng_l2tp_xmit_ctrl(priv, m, seq->ns++);
1505
1506         /* callout_deactivate() is not needed here
1507             as ng_callout() is getting called each time */
1508
1509         /* Sanity check */
1510         L2TP_SEQ_CHECK(seq);
1511 }
1512
1513 /*
1514  * Transmit a control stream packet, payload optional.
1515  * The transmit sequence number is not incremented.
1516  */
1517 static int
1518 ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns)
1519 {
1520         struct l2tp_seq *const seq = &priv->seq;
1521         u_int16_t session_id = 0;
1522         int error;
1523
1524         mtx_lock(&seq->mtx);
1525
1526         /* Stop ack timer: we're sending an ack with this packet.
1527            Doing this before to keep state predictable after error. */
1528         if (callout_active(&seq->xack_timer))
1529                 ng_uncallout(&seq->xack_timer, priv->node);
1530
1531         seq->xack = seq->nr;
1532
1533         mtx_unlock(&seq->mtx);
1534
1535         /* If no mbuf passed, send an empty packet (ZLB) */
1536         if (m == NULL) {
1537
1538                 /* Create a new mbuf for ZLB packet */
1539                 MGETHDR(m, MB_DONTWAIT, MT_DATA);
1540                 if (m == NULL) {
1541                         priv->stats.memoryFailures++;
1542                         return (ENOBUFS);
1543                 }
1544                 m->m_len = m->m_pkthdr.len = 12;
1545                 m->m_pkthdr.rcvif = NULL;
1546                 priv->stats.xmitZLBs++;
1547         } else {
1548
1549                 /* Strip off session ID */
1550                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
1551                         priv->stats.memoryFailures++;
1552                         return (ENOBUFS);
1553                 }
1554                 memcpy(&session_id, mtod(m, u_int16_t *), 2);
1555                 m_adj(m, 2);
1556
1557                 /* Make room for L2TP header */
1558                 M_PREPEND(m, 12, MB_DONTWAIT);
1559                 if (m == NULL) {
1560                         priv->stats.memoryFailures++;
1561                         return (ENOBUFS);
1562                 }
1563         }
1564
1565         /* Fill in L2TP header */
1566         mtod(m, u_int16_t *)[0] = htons(L2TP_CTRL_HDR);
1567         mtod(m, u_int16_t *)[1] = htons(m->m_pkthdr.len);
1568         mtod(m, u_int16_t *)[2] = priv->conf.peer_id;
1569         mtod(m, u_int16_t *)[3] = session_id;
1570         mtod(m, u_int16_t *)[4] = htons(ns);
1571         mtod(m, u_int16_t *)[5] = htons(seq->nr);
1572
1573         /* Update sequence number info and stats */
1574         priv->stats.xmitPackets++;
1575         priv->stats.xmitOctets += m->m_pkthdr.len;
1576
1577         /* Send packet */
1578         NG_SEND_DATA_ONLY(error, priv->lower, m);
1579         return (error);
1580 }
1581
1582 #ifdef INVARIANTS
1583 /*
1584  * Sanity check sequence number state.
1585  */
1586 static void
1587 ng_l2tp_seq_check(struct l2tp_seq *seq)
1588 {
1589         int self_unack, peer_unack;
1590         int i;
1591
1592 #define CHECK(p)        KASSERT((p), ("%s: not: %s", __func__, #p))
1593
1594         mtx_lock(&seq->mtx);
1595
1596         self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack);
1597         peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack);
1598         CHECK(seq->wmax <= L2TP_MAX_XWIN);
1599         CHECK(seq->cwnd >= 1);
1600         CHECK(seq->cwnd <= seq->wmax);
1601         CHECK(seq->ssth >= 1);
1602         CHECK(seq->ssth <= seq->wmax);
1603         if (seq->cwnd < seq->ssth)
1604                 CHECK(seq->acks == 0);
1605         else
1606                 CHECK(seq->acks <= seq->cwnd);
1607         CHECK(self_unack >= 0);
1608         CHECK(peer_unack >= 0);
1609         CHECK(peer_unack <= seq->wmax);
1610         CHECK((self_unack == 0) ^ callout_active(&seq->xack_timer));
1611         CHECK((peer_unack == 0) ^ callout_active(&seq->rack_timer));
1612         for (i = 0; i < peer_unack; i++)
1613                 CHECK(seq->xwin[i] != NULL);
1614         for ( ; i < seq->cwnd; i++)         /* verify peer's recv window full */
1615                 CHECK(seq->xwin[i] == NULL);
1616
1617         mtx_unlock(&seq->mtx);
1618
1619 #undef CHECK
1620 }
1621 #endif  /* INVARIANTS */