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  * $FreeBSD$
  40  */
  41
  42 /*
  43  * L2TP netgraph node type.
  44  *
  45  * This node type implements the lower layer of the
  46  * L2TP protocol as specified in RFC 2661.
  47  */
  48
  49 #include <sys/param.h>
  50 #include <sys/systm.h>
  51 #include <sys/kernel.h>
  52 #include <sys/time.h>
  53 #include <sys/conf.h>
  54 #include <sys/mbuf.h>
  55 #include <sys/malloc.h>
  56 #include <sys/errno.h>
  57 #include <sys/libkern.h>
  58
  59 #include <netgraph/ng_message.h>
  60 #include <netgraph/netgraph.h>
  61 #include <netgraph/ng_parse.h>
  62 #include <netgraph/ng_l2tp.h>
  63
  64 #ifdef NG_SEPARATE_MALLOC
  65 MALLOC_DEFINE(M_NETGRAPH_L2TP, "netgraph_l2tp", "netgraph l2tp node");
  66 #else
  67 #define M_NETGRAPH_L2TP M_NETGRAPH
  68 #endif
  69
  70 /* L2TP header format (first 2 bytes only) */
  71 #define L2TP_HDR_CTRL           0x8000                  /* control packet */
  72 #define L2TP_HDR_LEN            0x4000                  /* has length field */
  73 #define L2TP_HDR_SEQ            0x0800                  /* has ns, nr fields */
  74 #define L2TP_HDR_OFF            0x0200                  /* has offset field */
  75 #define L2TP_HDR_PRIO           0x0100                  /* give priority */
  76 #define L2TP_HDR_VERS_MASK      0x000f                  /* version field mask */
  77 #define L2TP_HDR_VERSION        0x0002                  /* version field */
  78
  79 /* Bits that must be zero or one in first two bytes of header */
  80 #define L2TP_CTRL_0BITS         0x030d                  /* ctrl: must be 0 */
  81 #define L2TP_CTRL_1BITS         0xc802                  /* ctrl: must be 1 */
  82 #define L2TP_DATA_0BITS         0x800d                  /* data: must be 0 */
  83 #define L2TP_DATA_1BITS         0x0002                  /* data: must be 1 */
  84
  85 /* Standard xmit ctrl and data header bits */
  86 #define L2TP_CTRL_HDR           (L2TP_HDR_CTRL | L2TP_HDR_LEN \
  87                                     | L2TP_HDR_SEQ | L2TP_HDR_VERSION)
  88 #define L2TP_DATA_HDR           (L2TP_HDR_VERSION)      /* optional: len, seq */
  89
  90 /* Some hard coded values */
  91 #define L2TP_MAX_XWIN           128                     /* my max xmit window */
  92 #define L2TP_MAX_REXMIT         5                       /* default max rexmit */
  93 #define L2TP_MAX_REXMIT_TO      30                      /* default rexmit to */
  94 #define L2TP_DELAYED_ACK        ((hz + 19) / 20)        /* delayed ack: 50 ms */
  95
  96 /* Default data sequence number configuration for new sessions */
  97 #define L2TP_CONTROL_DSEQ       1                       /* we are the lns */
  98 #define L2TP_ENABLE_DSEQ        1                       /* enable data seq # */
  99
 100 /* Compare sequence numbers using circular math */
 101 #define L2TP_SEQ_DIFF(x, y)     ((int)((int16_t)(x) - (int16_t)(y)))
 102
 103 #define SESSHASHSIZE            0x0020
 104 #define SESSHASH(x)             (((x) ^ ((x) >> 8)) & (SESSHASHSIZE - 1))
 105
 106 /* Hook private data (data session hooks only) */
 107 struct ng_l2tp_hook_private {
 108         struct ng_l2tp_sess_config      conf;   /* hook/session config */
 109         struct ng_l2tp_session_stats    stats;  /* per sessions statistics */
 110         hook_p                          hook;   /* hook reference */
 111         u_int16_t                       ns;     /* data ns sequence number */
 112         u_int16_t                       nr;     /* data nr sequence number */
 113         LIST_ENTRY(ng_l2tp_hook_private) sessions;
 114 };
 115 typedef struct ng_l2tp_hook_private *hookpriv_p;
 116
 117 /*
 118  * Sequence number state
 119  *
 120  * Invariants:
 121  *    - If cwnd < ssth, we're doing slow start, otherwise congestion avoidance
 122  *    - The number of unacknowledged xmit packets is (ns - rack) <= seq->wmax
 123  *    - The first (ns - rack) mbuf's in xwin[] array are copies of these
 124  *      unacknowledged packets; the remainder of xwin[] consists first of
 125  *      zero or more further untransmitted packets in the transmit queue
 126  *    - We try to keep the peer's receive window as full as possible.
 127  *      Therefore, (i < cwnd && xwin[i] != NULL) implies (ns - rack) > i.
 128  *    - rack_timer is running iff (ns - rack) > 0 (unack'd xmit'd pkts)
 129  *    - If xack != nr, there are unacknowledged recv packet(s) (delayed ack)
 130  *    - xack_timer is running iff xack != nr (unack'd rec'd pkts)
 131  */
 132 struct l2tp_seq {
 133         u_int16_t               ns;             /* next xmit seq we send */
 134         u_int16_t               nr;             /* next recv seq we expect */
 135         u_int16_t               inproc;         /* packet is in processing */
 136         u_int16_t               rack;           /* last 'nr' we rec'd */
 137         u_int16_t               xack;           /* last 'nr' we sent */
 138         u_int16_t               wmax;           /* peer's max recv window */
 139         u_int16_t               cwnd;           /* current congestion window */
 140         u_int16_t               ssth;           /* slow start threshold */
 141         u_int16_t               acks;           /* # consecutive acks rec'd */
 142         u_int16_t               rexmits;        /* # retransmits sent */
 143         struct callout          rack_timer;     /* retransmit timer */
 144         struct callout          xack_timer;     /* delayed ack timer */
 145         struct mbuf             *xwin[L2TP_MAX_XWIN];   /* transmit window */
 146         struct mtx              mtx;                    /* seq mutex */
 147 };
 148
 149 /* Node private data */
 150 struct ng_l2tp_private {
 151         node_p                  node;           /* back pointer to node */
 152         hook_p                  ctrl;           /* hook to upper layers */
 153         hook_p                  lower;          /* hook to lower layers */
 154         struct ng_l2tp_config   conf;           /* node configuration */
 155         struct ng_l2tp_stats    stats;          /* node statistics */
 156         struct l2tp_seq         seq;            /* ctrl sequence number state */
 157         ng_ID_t                 ftarget;        /* failure message target */
 158         LIST_HEAD(, ng_l2tp_hook_private) sesshash[SESSHASHSIZE];
 159 };
 160 typedef struct ng_l2tp_private *priv_p;
 161
 162 /* Netgraph node methods */
 163 static ng_constructor_t ng_l2tp_constructor;
 164 static ng_rcvmsg_t      ng_l2tp_rcvmsg;
 165 static ng_shutdown_t    ng_l2tp_shutdown;
 166 static ng_newhook_t     ng_l2tp_newhook;
 167 static ng_rcvdata_t     ng_l2tp_rcvdata;
 168 static ng_rcvdata_t     ng_l2tp_rcvdata_lower;
 169 static ng_rcvdata_t     ng_l2tp_rcvdata_ctrl;
 170 static ng_disconnect_t  ng_l2tp_disconnect;
 171
 172 /* Internal functions */
 173 static int      ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns);
 174
 175 static void     ng_l2tp_seq_init(priv_p priv);
 176 static int      ng_l2tp_seq_set(priv_p priv,
 177                         const struct ng_l2tp_seq_config *conf);
 178 static int      ng_l2tp_seq_adjust(priv_p priv,
 179                         const struct ng_l2tp_config *conf);
 180 static void     ng_l2tp_seq_reset(priv_p priv);
 181 static void     ng_l2tp_seq_failure(priv_p priv);
 182 static void     ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr);
 183 static void     ng_l2tp_seq_xack_timeout(node_p node, hook_p hook,
 184                     void *arg1, int arg2);
 185 static void     ng_l2tp_seq_rack_timeout(node_p node, hook_p hook,
 186                     void *arg1, int arg2);
 187
 188 static hookpriv_p       ng_l2tp_find_session(priv_p privp, u_int16_t sid);
 189 static ng_fn_eachhook   ng_l2tp_reset_session;
 190
 191 #ifdef INVARIANTS
 192 static void     ng_l2tp_seq_check(struct l2tp_seq *seq);
 193 #endif
 194
 195 /* Parse type for struct ng_l2tp_seq_config. */
 196 static const struct ng_parse_struct_field
 197         ng_l2tp_seq_config_fields[] = NG_L2TP_SEQ_CONFIG_TYPE_INFO;
 198 static const struct ng_parse_type ng_l2tp_seq_config_type = {
 199         &ng_parse_struct_type,
 200         &ng_l2tp_seq_config_fields
 201 };
 202
 203 /* Parse type for struct ng_l2tp_config */
 204 static const struct ng_parse_struct_field
 205         ng_l2tp_config_type_fields[] = NG_L2TP_CONFIG_TYPE_INFO;
 206 static const struct ng_parse_type ng_l2tp_config_type = {
 207         &ng_parse_struct_type,
 208         &ng_l2tp_config_type_fields,
 209 };
 210
 211 /* Parse type for struct ng_l2tp_sess_config */
 212 static const struct ng_parse_struct_field
 213         ng_l2tp_sess_config_type_fields[] = NG_L2TP_SESS_CONFIG_TYPE_INFO;
 214 static const struct ng_parse_type ng_l2tp_sess_config_type = {
 215         &ng_parse_struct_type,
 216         &ng_l2tp_sess_config_type_fields,
 217 };
 218
 219 /* Parse type for struct ng_l2tp_stats */
 220 static const struct ng_parse_struct_field
 221         ng_l2tp_stats_type_fields[] = NG_L2TP_STATS_TYPE_INFO;
 222 static const struct ng_parse_type ng_l2tp_stats_type = {
 223         &ng_parse_struct_type,
 224         &ng_l2tp_stats_type_fields
 225 };
 226
 227 /* Parse type for struct ng_l2tp_session_stats. */
 228 static const struct ng_parse_struct_field
 229         ng_l2tp_session_stats_type_fields[] = NG_L2TP_SESSION_STATS_TYPE_INFO;
 230 static const struct ng_parse_type ng_l2tp_session_stats_type = {
 231         &ng_parse_struct_type,
 232         &ng_l2tp_session_stats_type_fields
 233 };
 234
 235 /* List of commands and how to convert arguments to/from ASCII */
 236 static const struct ng_cmdlist ng_l2tp_cmdlist[] = {
 237         {
 238           NGM_L2TP_COOKIE,
 239           NGM_L2TP_SET_CONFIG,
 240           "setconfig",
 241           &ng_l2tp_config_type,
 242           NULL
 243         },
 244         {
 245           NGM_L2TP_COOKIE,
 246           NGM_L2TP_GET_CONFIG,
 247           "getconfig",
 248           NULL,
 249           &ng_l2tp_config_type
 250         },
 251         {
 252           NGM_L2TP_COOKIE,
 253           NGM_L2TP_SET_SESS_CONFIG,
 254           "setsessconfig",
 255           &ng_l2tp_sess_config_type,
 256           NULL
 257         },
 258         {
 259           NGM_L2TP_COOKIE,
 260           NGM_L2TP_GET_SESS_CONFIG,
 261           "getsessconfig",
 262           &ng_parse_hint16_type,
 263           &ng_l2tp_sess_config_type
 264         },
 265         {
 266           NGM_L2TP_COOKIE,
 267           NGM_L2TP_GET_STATS,
 268           "getstats",
 269           NULL,
 270           &ng_l2tp_stats_type
 271         },
 272         {
 273           NGM_L2TP_COOKIE,
 274           NGM_L2TP_CLR_STATS,
 275           "clrstats",
 276           NULL,
 277           NULL
 278         },
 279         {
 280           NGM_L2TP_COOKIE,
 281           NGM_L2TP_GETCLR_STATS,
 282           "getclrstats",
 283           NULL,
 284           &ng_l2tp_stats_type
 285         },
 286         {
 287           NGM_L2TP_COOKIE,
 288           NGM_L2TP_GET_SESSION_STATS,
 289           "getsessstats",
 290           &ng_parse_int16_type,
 291           &ng_l2tp_session_stats_type
 292         },
 293         {
 294           NGM_L2TP_COOKIE,
 295           NGM_L2TP_CLR_SESSION_STATS,
 296           "clrsessstats",
 297           &ng_parse_int16_type,
 298           NULL
 299         },
 300         {
 301           NGM_L2TP_COOKIE,
 302           NGM_L2TP_GETCLR_SESSION_STATS,
 303           "getclrsessstats",
 304           &ng_parse_int16_type,
 305           &ng_l2tp_session_stats_type
 306         },
 307         {
 308           NGM_L2TP_COOKIE,
 309           NGM_L2TP_ACK_FAILURE,
 310           "ackfailure",
 311           NULL,
 312           NULL
 313         },
 314         {
 315           NGM_L2TP_COOKIE,
 316           NGM_L2TP_SET_SEQ,
 317           "setsequence",
 318           &ng_l2tp_seq_config_type,
 319           NULL
 320         },
 321         { 0 }
 322 };
 323
 324 /* Node type descriptor */
 325 static struct ng_type ng_l2tp_typestruct = {
 326         .version =      NG_ABI_VERSION,
 327         .name =         NG_L2TP_NODE_TYPE,
 328         .constructor =  ng_l2tp_constructor,
 329         .rcvmsg =       ng_l2tp_rcvmsg,
 330         .shutdown =     ng_l2tp_shutdown,
 331         .newhook =      ng_l2tp_newhook,
 332         .rcvdata =      ng_l2tp_rcvdata,
 333         .disconnect =   ng_l2tp_disconnect,
 334         .cmdlist =      ng_l2tp_cmdlist,
 335 };
 336 NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct);
 337
 338 /* Sequence number state sanity checking */
 339 #ifdef INVARIANTS
 340 #define L2TP_SEQ_CHECK(seq)     ng_l2tp_seq_check(seq)
 341 #else
 342 #define L2TP_SEQ_CHECK(x)       do { } while (0)
 343 #endif
 344
 345 /* Whether to use m_copypacket() or m_dup() */
 346 #define L2TP_COPY_MBUF          m_copypacket
 347
 348 #define ERROUT(x)       do { error = (x); goto done; } while (0)
 349
 350 /************************************************************************
 351                         NETGRAPH NODE STUFF
 352 ************************************************************************/
 353
 354 /*
 355  * Node type constructor
 356  */
 357 static int
 358 ng_l2tp_constructor(node_p node)
 359 {
 360         priv_p priv;
 361         int     i;
 362
 363         /* Allocate private structure */
 364         priv = malloc(sizeof(*priv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
 365         if (priv == NULL)
 366                 return (ENOMEM);
 367         NG_NODE_SET_PRIVATE(node, priv);
 368         priv->node = node;
 369
 370         /* Apply a semi-reasonable default configuration */
 371         priv->conf.peer_win = 1;
 372         priv->conf.rexmit_max = L2TP_MAX_REXMIT;
 373         priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO;
 374
 375         /* Initialize sequence number state */
 376         ng_l2tp_seq_init(priv);
 377
 378         for (i = 0; i < SESSHASHSIZE; i++)
 379             LIST_INIT(&priv->sesshash[i]);
 380
 381         /* Done */
 382         return (0);
 383 }
 384
 385 /*
 386  * Give our OK for a hook to be added.
 387  */
 388 static int
 389 ng_l2tp_newhook(node_p node, hook_p hook, const char *name)
 390 {
 391         const priv_p priv = NG_NODE_PRIVATE(node);
 392
 393         /* Check hook name */
 394         if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) {
 395                 if (priv->ctrl != NULL)
 396                         return (EISCONN);
 397                 priv->ctrl = hook;
 398                 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_ctrl);
 399         } else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) {
 400                 if (priv->lower != NULL)
 401                         return (EISCONN);
 402                 priv->lower = hook;
 403                 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_lower);
 404         } else {
 405                 static const char hexdig[16] = "0123456789abcdef";
 406                 u_int16_t session_id;
 407                 hookpriv_p hpriv;
 408                 uint16_t hash;
 409                 const char *hex;
 410                 int i;
 411                 int j;
 412
 413                 /* Parse hook name to get session ID */
 414                 if (strncmp(name, NG_L2TP_HOOK_SESSION_P,
 415                     sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0)
 416                         return (EINVAL);
 417                 hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1;
 418                 for (session_id = i = 0; i < 4; i++) {
 419                         for (j = 0; j < 16 && hex[i] != hexdig[j]; j++);
 420                         if (j == 16)
 421                                 return (EINVAL);
 422                         session_id = (session_id << 4) | j;
 423                 }
 424                 if (hex[i] != '\0')
 425                         return (EINVAL);
 426
 427                 /* Create hook private structure */
 428                 hpriv = malloc(sizeof(*hpriv),
 429                     M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
 430                 if (hpriv == NULL)
 431                         return (ENOMEM);
 432                 hpriv->conf.session_id = session_id;
 433                 hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ;
 434                 hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ;
 435                 hpriv->hook = hook;
 436                 NG_HOOK_SET_PRIVATE(hook, hpriv);
 437                 hash = SESSHASH(hpriv->conf.session_id);
 438                 LIST_INSERT_HEAD(&priv->sesshash[hash], hpriv, sessions);
 439         }
 440
 441         /* Done */
 442         return (0);
 443 }
 444
 445 /*
 446  * Receive a control message.
 447  */
 448 static int
 449 ng_l2tp_rcvmsg(node_p node, item_p item, hook_p lasthook)
 450 {
 451         const priv_p priv = NG_NODE_PRIVATE(node);
 452         struct ng_mesg *resp = NULL;
 453         struct ng_mesg *msg;
 454         int error = 0;
 455
 456         NGI_GET_MSG(item, msg);
 457         switch (msg->header.typecookie) {
 458         case NGM_L2TP_COOKIE:
 459                 switch (msg->header.cmd) {
 460                 case NGM_L2TP_SET_CONFIG:
 461                     {
 462                         struct ng_l2tp_config *const conf =
 463                                 (struct ng_l2tp_config *)msg->data;
 464
 465                         /* Check for invalid or illegal config */
 466                         if (msg->header.arglen != sizeof(*conf)) {
 467                                 error = EINVAL;
 468                                 break;
 469                         }
 470                         conf->enabled = !!conf->enabled;
 471                         conf->match_id = !!conf->match_id;
 472                         if (priv->conf.enabled
 473                             && ((priv->conf.tunnel_id != 0
 474                                && conf->tunnel_id != priv->conf.tunnel_id)
 475                               || ((priv->conf.peer_id != 0
 476                                && conf->peer_id != priv->conf.peer_id)))) {
 477                                 error = EBUSY;
 478                                 break;
 479                         }
 480
 481                         /* Save calling node as failure target */
 482                         priv->ftarget = NGI_RETADDR(item);
 483
 484                         /* Adjust sequence number state */
 485                         if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0)
 486                                 break;
 487
 488                         /* Update node's config */
 489                         priv->conf = *conf;
 490                         break;
 491                     }
 492                 case NGM_L2TP_GET_CONFIG:
 493                     {
 494                         struct ng_l2tp_config *conf;
 495
 496                         NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT);
 497                         if (resp == NULL) {
 498                                 error = ENOMEM;
 499                                 break;
 500                         }
 501                         conf = (struct ng_l2tp_config *)resp->data;
 502                         *conf = priv->conf;
 503                         break;
 504                     }
 505                 case NGM_L2TP_SET_SESS_CONFIG:
 506                     {
 507                         struct ng_l2tp_sess_config *const conf =
 508                             (struct ng_l2tp_sess_config *)msg->data;
 509                         hookpriv_p hpriv;
 510
 511                         /* Check for invalid or illegal config. */
 512                         if (msg->header.arglen != sizeof(*conf)) {
 513                                 error = EINVAL;
 514                                 break;
 515                         }
 516
 517                         /* Find matching hook */
 518                         hpriv = ng_l2tp_find_session(priv, conf->session_id);
 519                         if (hpriv == NULL) {
 520                                 error = ENOENT;
 521                                 break;
 522                         }
 523
 524                         /* Update hook's config */
 525                         hpriv->conf = *conf;
 526                         break;
 527                     }
 528                 case NGM_L2TP_GET_SESS_CONFIG:
 529                     {
 530                         struct ng_l2tp_sess_config *conf;
 531                         u_int16_t session_id;
 532                         hookpriv_p hpriv;
 533
 534                         /* Get session ID */
 535                         if (msg->header.arglen != sizeof(session_id)) {
 536                                 error = EINVAL;
 537                                 break;
 538                         }
 539                         memcpy(&session_id, msg->data, 2);
 540
 541                         /* Find matching hook */
 542                         hpriv = ng_l2tp_find_session(priv, session_id);
 543                         if (hpriv == NULL) {
 544                                 error = ENOENT;
 545                                 break;
 546                         }
 547
 548                         /* Send response */
 549                         NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_NOWAIT);
 550                         if (resp == NULL) {
 551                                 error = ENOMEM;
 552                                 break;
 553                         }
 554                         conf = (struct ng_l2tp_sess_config *)resp->data;
 555                         *conf = hpriv->conf;
 556                         break;
 557                     }
 558                 case NGM_L2TP_GET_STATS:
 559                 case NGM_L2TP_CLR_STATS:
 560                 case NGM_L2TP_GETCLR_STATS:
 561                     {
 562                         if (msg->header.cmd != NGM_L2TP_CLR_STATS) {
 563                                 NG_MKRESPONSE(resp, msg,
 564                                     sizeof(priv->stats), M_NOWAIT);
 565                                 if (resp == NULL) {
 566                                         error = ENOMEM;
 567                                         break;
 568                                 }
 569                                 memcpy(resp->data,
 570                                     &priv->stats, sizeof(priv->stats));
 571                         }
 572                         if (msg->header.cmd != NGM_L2TP_GET_STATS)
 573                                 memset(&priv->stats, 0, sizeof(priv->stats));
 574                         break;
 575                     }
 576                 case NGM_L2TP_GET_SESSION_STATS:
 577                 case NGM_L2TP_CLR_SESSION_STATS:
 578                 case NGM_L2TP_GETCLR_SESSION_STATS:
 579                     {
 580                         uint16_t session_id;
 581                         hookpriv_p hpriv;
 582
 583                         /* Get session ID. */
 584                         if (msg->header.arglen != sizeof(session_id)) {
 585                                 error = EINVAL;
 586                                 break;
 587                         }
 588                         bcopy(msg->data, &session_id, sizeof(uint16_t));
 589
 590                         /* Find matching hook. */
 591                         hpriv = ng_l2tp_find_session(priv, session_id);
 592                         if (hpriv == NULL) {
 593                                 error = ENOENT;
 594                                 break;
 595                         }
 596
 597                         if (msg->header.cmd != NGM_L2TP_CLR_SESSION_STATS) {
 598                                 NG_MKRESPONSE(resp, msg,
 599                                     sizeof(hpriv->stats), M_NOWAIT);
 600                                 if (resp == NULL) {
 601                                         error = ENOMEM;
 602                                         break;
 603                                 }
 604                                 bcopy(&hpriv->stats, resp->data,
 605                                         sizeof(hpriv->stats));
 606                         }
 607                         if (msg->header.cmd != NGM_L2TP_GET_SESSION_STATS)
 608                                 bzero(&hpriv->stats, sizeof(hpriv->stats));
 609                         break;
 610                     }
 611                 case NGM_L2TP_SET_SEQ:
 612                     {
 613                         struct ng_l2tp_seq_config *const conf =
 614                                 (struct ng_l2tp_seq_config *)msg->data;
 615
 616                         /* Check for invalid or illegal seq config. */
 617                         if (msg->header.arglen != sizeof(*conf)) {
 618                                 error = EINVAL;
 619                                 break;
 620                         }
 621                         conf->ns = htons(conf->ns);
 622                         conf->nr = htons(conf->nr);
 623                         conf->rack = htons(conf->rack);
 624                         conf->xack = htons(conf->xack);
 625
 626                         /* Set sequence numbers. */
 627                         error = ng_l2tp_seq_set(priv, conf);
 628                         break;
 629                     }
 630                 default:
 631                         error = EINVAL;
 632                         break;
 633                 }
 634                 break;
 635         default:
 636                 error = EINVAL;
 637                 break;
 638         }
 639
 640         /* Done */
 641         NG_RESPOND_MSG(error, node, item, resp);
 642         NG_FREE_MSG(msg);
 643         return (error);
 644 }
 645
 646 /*
 647  * Destroy node
 648  */
 649 static int
 650 ng_l2tp_shutdown(node_p node)
 651 {
 652         const priv_p priv = NG_NODE_PRIVATE(node);
 653         struct l2tp_seq *const seq = &priv->seq;
 654
 655         /* Sanity check */
 656         L2TP_SEQ_CHECK(seq);
 657
 658         /* Reset sequence number state */
 659         ng_l2tp_seq_reset(priv);
 660
 661         /* Free private data if neither timer is running */
 662         ng_uncallout(&seq->rack_timer, node);
 663         ng_uncallout(&seq->xack_timer, node);
 664
 665         mtx_destroy(&seq->mtx);
 666
 667         free(priv, M_NETGRAPH_L2TP);
 668
 669         /* Unref node */
 670         NG_NODE_UNREF(node);
 671         return (0);
 672 }
 673
 674 /*
 675  * Hook disconnection
 676  */
 677 static int
 678 ng_l2tp_disconnect(hook_p hook)
 679 {
 680         const node_p node = NG_HOOK_NODE(hook);
 681         const priv_p priv = NG_NODE_PRIVATE(node);
 682
 683         /* Zero out hook pointer */
 684         if (hook == priv->ctrl)
 685                 priv->ctrl = NULL;
 686         else if (hook == priv->lower)
 687                 priv->lower = NULL;
 688         else {
 689                 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
 690                 LIST_REMOVE(hpriv, sessions);
 691                 free(hpriv, M_NETGRAPH_L2TP);
 692                 NG_HOOK_SET_PRIVATE(hook, NULL);
 693         }
 694
 695         /* Go away if no longer connected to anything */
 696         if (NG_NODE_NUMHOOKS(node) == 0 && NG_NODE_IS_VALID(node))
 697                 ng_rmnode_self(node);
 698         return (0);
 699 }
 700
 701 /*************************************************************************
 702                         INTERNAL FUNCTIONS
 703 *************************************************************************/
 704
 705 /*
 706  * Find the hook with a given session ID.
 707  */
 708 static hookpriv_p
 709 ng_l2tp_find_session(priv_p privp, u_int16_t sid)
 710 {
 711         uint16_t        hash = SESSHASH(sid);
 712         hookpriv_p      hpriv = NULL;
 713
 714         LIST_FOREACH(hpriv, &privp->sesshash[hash], sessions) {
 715                 if (hpriv->conf.session_id == sid)
 716                         break;
 717         }
 718
 719         return (hpriv);
 720 }
 721
 722 /*
 723  * Reset a hook's session state.
 724  */
 725 static int
 726 ng_l2tp_reset_session(hook_p hook, void *arg)
 727 {
 728         const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
 729
 730         if (hpriv != NULL) {
 731                 hpriv->conf.control_dseq = 0;
 732                 hpriv->conf.enable_dseq = 0;
 733                 bzero(&hpriv->stats, sizeof(struct ng_l2tp_session_stats));
 734                 hpriv->nr = 0;
 735                 hpriv->ns = 0;
 736         }
 737         return (-1);
 738 }
 739
 740 /*
 741  * Handle an incoming frame from below.
 742  */
 743 static int
 744 ng_l2tp_rcvdata_lower(hook_p h, item_p item)
 745 {
 746         static const u_int16_t req_bits[2][2] = {
 747                 { L2TP_DATA_0BITS, L2TP_DATA_1BITS },
 748                 { L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
 749         };
 750         const node_p node = NG_HOOK_NODE(h);
 751         const priv_p priv = NG_NODE_PRIVATE(node);
 752         hookpriv_p hpriv = NULL;
 753         hook_p hook = NULL;
 754         struct mbuf *m;
 755         u_int16_t tid, sid;
 756         u_int16_t hdr;
 757         u_int16_t ns, nr;
 758         int is_ctrl;
 759         int error;
 760         int len, plen;
 761
 762         /* Sanity check */
 763         L2TP_SEQ_CHECK(&priv->seq);
 764
 765         /* If not configured, reject */
 766         if (!priv->conf.enabled) {
 767                 NG_FREE_ITEM(item);
 768                 ERROUT(ENXIO);
 769         }
 770
 771         /* Grab mbuf */
 772         NGI_GET_M(item, m);
 773
 774         /* Remember full packet length; needed for per session accounting. */
 775         plen = m->m_pkthdr.len;
 776
 777         /* Update stats */
 778         priv->stats.recvPackets++;
 779         priv->stats.recvOctets += plen;
 780
 781         /* Get initial header */
 782         if (m->m_pkthdr.len < 6) {
 783                 priv->stats.recvRunts++;
 784                 NG_FREE_ITEM(item);
 785                 NG_FREE_M(m);
 786                 ERROUT(EINVAL);
 787         }
 788         if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 789                 priv->stats.memoryFailures++;
 790                 NG_FREE_ITEM(item);
 791                 ERROUT(EINVAL);
 792         }
 793         hdr = ntohs(*mtod(m, u_int16_t *));
 794         m_adj(m, 2);
 795
 796         /* Check required header bits and minimum length */
 797         is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
 798         if ((hdr & req_bits[is_ctrl][0]) != 0
 799             || (~hdr & req_bits[is_ctrl][1]) != 0) {
 800                 priv->stats.recvInvalid++;
 801                 NG_FREE_ITEM(item);
 802                 NG_FREE_M(m);
 803                 ERROUT(EINVAL);
 804         }
 805         if (m->m_pkthdr.len < 4                         /* tunnel, session id */
 806             + (2 * ((hdr & L2TP_HDR_LEN) != 0))         /* length field */
 807             + (4 * ((hdr & L2TP_HDR_SEQ) != 0))         /* seq # fields */
 808             + (2 * ((hdr & L2TP_HDR_OFF) != 0))) {      /* offset field */
 809                 priv->stats.recvRunts++;
 810                 NG_FREE_ITEM(item);
 811                 NG_FREE_M(m);
 812                 ERROUT(EINVAL);
 813         }
 814
 815         /* Get and validate length field if present */
 816         if ((hdr & L2TP_HDR_LEN) != 0) {
 817                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 818                         priv->stats.memoryFailures++;
 819                         NG_FREE_ITEM(item);
 820                         ERROUT(EINVAL);
 821                 }
 822                 len = (u_int16_t)ntohs(*mtod(m, u_int16_t *)) - 4;
 823                 m_adj(m, 2);
 824                 if (len < 0 || len > m->m_pkthdr.len) {
 825                         priv->stats.recvInvalid++;
 826                         NG_FREE_ITEM(item);
 827                         NG_FREE_M(m);
 828                         ERROUT(EINVAL);
 829                 }
 830                 if (len < m->m_pkthdr.len)              /* trim extra bytes */
 831                         m_adj(m, -(m->m_pkthdr.len - len));
 832         }
 833
 834         /* Get tunnel ID and session ID */
 835         if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
 836                 priv->stats.memoryFailures++;
 837                 NG_FREE_ITEM(item);
 838                 ERROUT(EINVAL);
 839         }
 840         tid = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
 841         sid = (mtod(m, u_int8_t *)[2] << 8) + mtod(m, u_int8_t *)[3];
 842         m_adj(m, 4);
 843
 844         /* Check tunnel ID */
 845         if (tid != priv->conf.tunnel_id &&
 846             (priv->conf.match_id || tid != 0)) {
 847                 priv->stats.recvWrongTunnel++;
 848                 NG_FREE_ITEM(item);
 849                 NG_FREE_M(m);
 850                 ERROUT(EADDRNOTAVAIL);
 851         }
 852
 853         /* Check session ID (for data packets only) */
 854         if ((hdr & L2TP_HDR_CTRL) == 0) {
 855                 hpriv = ng_l2tp_find_session(priv, sid);
 856                 if (hpriv == NULL) {
 857                         priv->stats.recvUnknownSID++;
 858                         NG_FREE_ITEM(item);
 859                         NG_FREE_M(m);
 860                         ERROUT(ENOTCONN);
 861                 }
 862                 hook = hpriv->hook;
 863         }
 864
 865         /* Get Ns, Nr fields if present */
 866         if ((hdr & L2TP_HDR_SEQ) != 0) {
 867                 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
 868                         priv->stats.memoryFailures++;
 869                         NG_FREE_ITEM(item);
 870                         ERROUT(EINVAL);
 871                 }
 872                 ns = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
 873                 nr = (mtod(m, u_int8_t *)[2] << 8) + mtod(m, u_int8_t *)[3];
 874                 m_adj(m, 4);
 875         } else
 876                 ns = nr = 0;
 877
 878         /* Strip offset padding if present */
 879         if ((hdr & L2TP_HDR_OFF) != 0) {
 880                 u_int16_t offset;
 881
 882                 /* Get length of offset padding */
 883                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
 884                         priv->stats.memoryFailures++;
 885                         NG_FREE_ITEM(item);
 886                         ERROUT(EINVAL);
 887                 }
 888                 offset = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
 889
 890                 /* Trim offset padding */
 891                 if ((2+offset) > m->m_pkthdr.len) {
 892                         priv->stats.recvInvalid++;
 893                         NG_FREE_ITEM(item);
 894                         NG_FREE_M(m);
 895                         ERROUT(EINVAL);
 896                 }
 897                 m_adj(m, 2+offset);
 898         }
 899
 900         /* Handle control packets */
 901         if ((hdr & L2TP_HDR_CTRL) != 0) {
 902                 struct l2tp_seq *const seq = &priv->seq;
 903
 904                 /* Handle receive ack sequence number Nr */
 905                 ng_l2tp_seq_recv_nr(priv, nr);
 906
 907                 /* Discard ZLB packets */
 908                 if (m->m_pkthdr.len == 0) {
 909                         priv->stats.recvZLBs++;
 910                         NG_FREE_ITEM(item);
 911                         NG_FREE_M(m);
 912                         ERROUT(0);
 913                 }
 914
 915                 mtx_lock(&seq->mtx);
 916                 /*
 917                  * If not what we expect or we are busy, drop packet and
 918                  * send an immediate ZLB ack.
 919                  */
 920                 if (ns != seq->nr || seq->inproc) {
 921                         if (L2TP_SEQ_DIFF(ns, seq->nr) <= 0)
 922                                 priv->stats.recvDuplicates++;
 923                         else
 924                                 priv->stats.recvOutOfOrder++;
 925                         mtx_unlock(&seq->mtx);
 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                  * Until we deliver this packet we can't receive next one as
 933                  * we have no information for sending ack.
 934                  */
 935                 seq->inproc = 1;
 936                 mtx_unlock(&seq->mtx);
 937
 938                 /* Prepend session ID to packet. */
 939                 M_PREPEND(m, 2, M_DONTWAIT);
 940                 if (m == NULL) {
 941                         seq->inproc = 0;
 942                         priv->stats.memoryFailures++;
 943                         NG_FREE_ITEM(item);
 944                         ERROUT(ENOBUFS);
 945                 }
 946                 mtod(m, u_int8_t *)[0] = sid >> 8;
 947                 mtod(m, u_int8_t *)[1] = sid & 0xff;
 948
 949                 /* Deliver packet to upper layers */
 950                 NG_FWD_NEW_DATA(error, item, priv->ctrl, m);
 951
 952                 mtx_lock(&seq->mtx);
 953                 /* Ready to process next packet. */
 954                 seq->inproc = 0;
 955
 956                 /* If packet was successfully delivered send ack. */
 957                 if (error == 0) {
 958                         /* Update recv sequence number */
 959                         seq->nr++;
 960                         /* Start receive ack timer, if not already running */
 961                         if (!callout_active(&seq->xack_timer)) {
 962                                 ng_callout(&seq->xack_timer, priv->node, NULL,
 963                                     L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout,
 964                                     NULL, 0);
 965                         }
 966                 }
 967                 mtx_unlock(&seq->mtx);
 968
 969                 ERROUT(error);
 970         }
 971
 972         /* Per session packet, account it. */
 973         hpriv->stats.recvPackets++;
 974         hpriv->stats.recvOctets += plen;
 975
 976         /* Follow peer's lead in data sequencing, if configured to do so */
 977         if (!hpriv->conf.control_dseq)
 978                 hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0);
 979
 980         /* Handle data sequence numbers if present and enabled */
 981         if ((hdr & L2TP_HDR_SEQ) != 0) {
 982                 if (hpriv->conf.enable_dseq
 983                     && L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) {
 984                         NG_FREE_ITEM(item);     /* duplicate or out of order */
 985                         NG_FREE_M(m);
 986                         priv->stats.recvDataDrops++;
 987                         ERROUT(0);
 988                 }
 989                 hpriv->nr = ns + 1;
 990         }
 991
 992         /* Drop empty data packets */
 993         if (m->m_pkthdr.len == 0) {
 994                 NG_FREE_ITEM(item);
 995                 NG_FREE_M(m);
 996                 ERROUT(0);
 997         }
 998
 999         /* Deliver data */
1000         NG_FWD_NEW_DATA(error, item, hook, m);
1001 done:
1002         /* Done */
1003         L2TP_SEQ_CHECK(&priv->seq);
1004         return (error);
1005 }
1006
1007 /*
1008  * Handle an outgoing control frame.
1009  */
1010 static int
1011 ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item)
1012 {
1013         const node_p node = NG_HOOK_NODE(hook);
1014         const priv_p priv = NG_NODE_PRIVATE(node);
1015         struct l2tp_seq *const seq = &priv->seq;
1016         struct mbuf *m;
1017         int error;
1018         int i;
1019         u_int16_t       ns;
1020
1021         /* Sanity check */
1022         L2TP_SEQ_CHECK(&priv->seq);
1023
1024         /* If not configured, reject */
1025         if (!priv->conf.enabled) {
1026                 NG_FREE_ITEM(item);
1027                 ERROUT(ENXIO);
1028         }
1029
1030         /* Grab mbuf and discard other stuff XXX */
1031         NGI_GET_M(item, m);
1032         NG_FREE_ITEM(item);
1033
1034         /* Packet should have session ID prepended */
1035         if (m->m_pkthdr.len < 2) {
1036                 priv->stats.xmitInvalid++;
1037                 m_freem(m);
1038                 ERROUT(EINVAL);
1039         }
1040
1041         /* Check max length */
1042         if (m->m_pkthdr.len >= 0x10000 - 14) {
1043                 priv->stats.xmitTooBig++;
1044                 m_freem(m);
1045                 ERROUT(EOVERFLOW);
1046         }
1047
1048         mtx_lock(&seq->mtx);
1049
1050         /* Find next empty slot in transmit queue */
1051         for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
1052         if (i == L2TP_MAX_XWIN) {
1053                 mtx_unlock(&seq->mtx);
1054                 priv->stats.xmitDrops++;
1055                 m_freem(m);
1056                 ERROUT(ENOBUFS);
1057         }
1058         seq->xwin[i] = m;
1059
1060         /* If peer's receive window is already full, nothing else to do */
1061         if (i >= seq->cwnd) {
1062                 mtx_unlock(&seq->mtx);
1063                 ERROUT(0);
1064         }
1065
1066         /* Start retransmit timer if not already running */
1067         if (!callout_active(&seq->rack_timer))
1068                 ng_callout(&seq->rack_timer, node, NULL,
1069                     hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1070
1071         ns = seq->ns++;
1072
1073         mtx_unlock(&seq->mtx);
1074
1075         /* Copy packet */
1076         if ((m = L2TP_COPY_MBUF(m, M_DONTWAIT)) == NULL) {
1077                 priv->stats.memoryFailures++;
1078                 ERROUT(ENOBUFS);
1079         }
1080
1081         /* Send packet and increment xmit sequence number */
1082         error = ng_l2tp_xmit_ctrl(priv, m, ns);
1083 done:
1084         /* Done */
1085         L2TP_SEQ_CHECK(&priv->seq);
1086         return (error);
1087 }
1088
1089 /*
1090  * Handle an outgoing data frame.
1091  */
1092 static int
1093 ng_l2tp_rcvdata(hook_p hook, item_p item)
1094 {
1095         const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
1096         const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
1097         struct mbuf *m;
1098         u_int16_t hdr;
1099         int error;
1100         int i = 1;
1101
1102         /* Sanity check */
1103         L2TP_SEQ_CHECK(&priv->seq);
1104
1105         /* If not configured, reject */
1106         if (!priv->conf.enabled) {
1107                 NG_FREE_ITEM(item);
1108                 ERROUT(ENXIO);
1109         }
1110
1111         /* Get mbuf */
1112         NGI_GET_M(item, m);
1113
1114         /* Check max length */
1115         if (m->m_pkthdr.len >= 0x10000 - 12) {
1116                 priv->stats.xmitDataTooBig++;
1117                 NG_FREE_ITEM(item);
1118                 NG_FREE_M(m);
1119                 ERROUT(EOVERFLOW);
1120         }
1121
1122         /* Prepend L2TP header */
1123         M_PREPEND(m, 6
1124             + (2 * (hpriv->conf.include_length != 0))
1125             + (4 * (hpriv->conf.enable_dseq != 0)),
1126             M_DONTWAIT);
1127         if (m == NULL) {
1128                 priv->stats.memoryFailures++;
1129                 NG_FREE_ITEM(item);
1130                 ERROUT(ENOBUFS);
1131         }
1132         hdr = L2TP_DATA_HDR;
1133         if (hpriv->conf.include_length) {
1134                 hdr |= L2TP_HDR_LEN;
1135                 mtod(m, u_int16_t *)[i++] = htons(m->m_pkthdr.len);
1136         }
1137         mtod(m, u_int16_t *)[i++] = htons(priv->conf.peer_id);
1138         mtod(m, u_int16_t *)[i++] = htons(hpriv->conf.peer_id);
1139         if (hpriv->conf.enable_dseq) {
1140                 hdr |= L2TP_HDR_SEQ;
1141                 mtod(m, u_int16_t *)[i++] = htons(hpriv->ns);
1142                 mtod(m, u_int16_t *)[i++] = htons(hpriv->nr);
1143                 hpriv->ns++;
1144         }
1145         mtod(m, u_int16_t *)[0] = htons(hdr);
1146
1147         /* Update per session stats. */
1148         hpriv->stats.xmitPackets++;
1149         hpriv->stats.xmitOctets += m->m_pkthdr.len;
1150
1151         /* And the global one. */
1152         priv->stats.xmitPackets++;
1153         priv->stats.xmitOctets += m->m_pkthdr.len;
1154
1155         /* Send packet */
1156         NG_FWD_NEW_DATA(error, item, priv->lower, m);
1157 done:
1158         /* Done */
1159         L2TP_SEQ_CHECK(&priv->seq);
1160         return (error);
1161 }
1162
1163 /*
1164  * Send a message to our controlling node that we've failed.
1165  */
1166 static void
1167 ng_l2tp_seq_failure(priv_p priv)
1168 {
1169         struct ng_mesg *msg;
1170         int error;
1171
1172         NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_NOWAIT);
1173         if (msg == NULL)
1174                 return;
1175         NG_SEND_MSG_ID(error, priv->node, msg, priv->ftarget, 0);
1176 }
1177
1178 /************************************************************************
1179                         SEQUENCE NUMBER HANDLING
1180 ************************************************************************/
1181
1182 /*
1183  * Initialize sequence number state.
1184  */
1185 static void
1186 ng_l2tp_seq_init(priv_p priv)
1187 {
1188         struct l2tp_seq *const seq = &priv->seq;
1189
1190         KASSERT(priv->conf.peer_win >= 1,
1191             ("%s: peer_win is zero", __func__));
1192         memset(seq, 0, sizeof(*seq));
1193         seq->cwnd = 1;
1194         seq->wmax = priv->conf.peer_win;
1195         if (seq->wmax > L2TP_MAX_XWIN)
1196                 seq->wmax = L2TP_MAX_XWIN;
1197         seq->ssth = seq->wmax;
1198         ng_callout_init(&seq->rack_timer);
1199         ng_callout_init(&seq->xack_timer);
1200         mtx_init(&seq->mtx, "ng_l2tp", NULL, MTX_DEF);
1201         L2TP_SEQ_CHECK(seq);
1202 }
1203
1204 /*
1205  * Set sequence number state as given from user.
1206  */
1207 static int
1208 ng_l2tp_seq_set(priv_p priv, const struct ng_l2tp_seq_config *conf)
1209 {
1210         struct l2tp_seq *const seq = &priv->seq;
1211
1212         /* If node is enabled, deny update to sequence numbers. */
1213         if (priv->conf.enabled)
1214                 return (EBUSY);
1215
1216         /* We only can handle the simple cases. */
1217         if (conf->xack != conf->nr || conf->ns != conf->rack)
1218                 return (EINVAL);
1219
1220         /* Set ns,nr,rack,xack parameters. */
1221         seq->ns = conf->ns;
1222         seq->nr = conf->nr;
1223         seq->rack = conf->rack;
1224         seq->xack = conf->xack;
1225
1226         return (0);
1227 }
1228
1229 /*
1230  * Adjust sequence number state accordingly after reconfiguration.
1231  */
1232 static int
1233 ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf)
1234 {
1235         struct l2tp_seq *const seq = &priv->seq;
1236         u_int16_t new_wmax;
1237
1238         /* If disabling node, reset state sequence number */
1239         if (!conf->enabled) {
1240                 ng_l2tp_seq_reset(priv);
1241                 return (0);
1242         }
1243
1244         /* Adjust peer's max recv window; it can only increase */
1245         new_wmax = conf->peer_win;
1246         if (new_wmax > L2TP_MAX_XWIN)
1247                 new_wmax = L2TP_MAX_XWIN;
1248         if (new_wmax == 0)
1249                 return (EINVAL);
1250         if (new_wmax < seq->wmax)
1251                 return (EBUSY);
1252         seq->wmax = new_wmax;
1253
1254         /* Done */
1255         return (0);
1256 }
1257
1258 /*
1259  * Reset sequence number state.
1260  */
1261 static void
1262 ng_l2tp_seq_reset(priv_p priv)
1263 {
1264         struct l2tp_seq *const seq = &priv->seq;
1265         hook_p hook;
1266         int i;
1267
1268         /* Sanity check */
1269         L2TP_SEQ_CHECK(seq);
1270
1271         /* Stop timers */
1272         ng_uncallout(&seq->rack_timer, priv->node);
1273         ng_uncallout(&seq->xack_timer, priv->node);
1274
1275         /* Free retransmit queue */
1276         for (i = 0; i < L2TP_MAX_XWIN; i++) {
1277                 if (seq->xwin[i] == NULL)
1278                         break;
1279                 m_freem(seq->xwin[i]);
1280         }
1281
1282         /* Reset session hooks' sequence number states */
1283         NG_NODE_FOREACH_HOOK(priv->node, ng_l2tp_reset_session, NULL, hook);
1284
1285         /* Reset node's sequence number state */
1286         seq->ns = 0;
1287         seq->nr = 0;
1288         seq->rack = 0;
1289         seq->xack = 0;
1290         seq->wmax = L2TP_MAX_XWIN;
1291         seq->cwnd = 1;
1292         seq->ssth = seq->wmax;
1293         seq->acks = 0;
1294         seq->rexmits = 0;
1295         bzero(seq->xwin, sizeof(seq->xwin));
1296
1297         /* Done */
1298         L2TP_SEQ_CHECK(seq);
1299 }
1300
1301 /*
1302  * Handle receipt of an acknowledgement value (Nr) from peer.
1303  */
1304 static void
1305 ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr)
1306 {
1307         struct l2tp_seq *const seq = &priv->seq;
1308         struct mbuf     *xwin[L2TP_MAX_XWIN];   /* partial local copy */
1309         int             nack;
1310         int             i, j;
1311         uint16_t        ns;
1312
1313         mtx_lock(&seq->mtx);
1314
1315         /* Verify peer's ACK is in range */
1316         if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0) {
1317                 mtx_unlock(&seq->mtx);
1318                 return;                         /* duplicate ack */
1319         }
1320         if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) {
1321                 mtx_unlock(&seq->mtx);
1322                 priv->stats.recvBadAcks++;      /* ack for packet not sent */
1323                 return;
1324         }
1325         KASSERT(nack <= L2TP_MAX_XWIN,
1326             ("%s: nack=%d > %d", __func__, nack, L2TP_MAX_XWIN));
1327
1328         /* Update receive ack stats */
1329         seq->rack = nr;
1330         seq->rexmits = 0;
1331
1332         /* Free acknowledged packets and shift up packets in the xmit queue */
1333         for (i = 0; i < nack; i++)
1334                 m_freem(seq->xwin[i]);
1335         memmove(seq->xwin, seq->xwin + nack,
1336             (L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin));
1337         memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0,
1338             nack * sizeof(*seq->xwin));
1339
1340         /*
1341          * Do slow-start/congestion avoidance windowing algorithm described
1342          * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
1343          * ACK had arrived separately.
1344          */
1345         if (seq->cwnd < seq->wmax) {
1346
1347                 /* Handle slow start phase */
1348                 if (seq->cwnd < seq->ssth) {
1349                         seq->cwnd += nack;
1350                         nack = 0;
1351                         if (seq->cwnd > seq->ssth) {    /* into cg.av. phase */
1352                                 nack = seq->cwnd - seq->ssth;
1353                                 seq->cwnd = seq->ssth;
1354                         }
1355                 }
1356
1357                 /* Handle congestion avoidance phase */
1358                 if (seq->cwnd >= seq->ssth) {
1359                         seq->acks += nack;
1360                         while (seq->acks >= seq->cwnd) {
1361                                 seq->acks -= seq->cwnd;
1362                                 if (seq->cwnd < seq->wmax)
1363                                         seq->cwnd++;
1364                         }
1365                 }
1366         }
1367
1368         /* Stop xmit timer */
1369         if (callout_active(&seq->rack_timer))
1370                 ng_uncallout(&seq->rack_timer, priv->node);
1371
1372         /* If transmit queue is empty, we're done for now */
1373         if (seq->xwin[0] == NULL) {
1374                 mtx_unlock(&seq->mtx);
1375                 return;
1376         }
1377
1378         /* Start restransmit timer again */
1379         ng_callout(&seq->rack_timer, priv->node, NULL,
1380             hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1381
1382         /*
1383          * Send more packets, trying to keep peer's receive window full.
1384          * Make copy of everything we need before lock release.
1385          */
1386         ns = seq->ns;
1387         j = 0;
1388         while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd
1389             && seq->xwin[i] != NULL) {
1390                 xwin[j++] = seq->xwin[i];
1391                 seq->ns++;
1392         }
1393
1394         mtx_unlock(&seq->mtx);
1395
1396         /*
1397          * Send prepared.
1398          * If there is a memory error, pretend packet was sent, as it
1399          * will get retransmitted later anyway.
1400          */
1401         for (i = 0; i < j; i++) {
1402                 struct mbuf     *m;
1403                 if ((m = L2TP_COPY_MBUF(xwin[i], M_DONTWAIT)) == NULL)
1404                         priv->stats.memoryFailures++;
1405                 else
1406                         ng_l2tp_xmit_ctrl(priv, m, ns);
1407                 ns++;
1408         }
1409 }
1410
1411 /*
1412  * Handle an ack timeout. We have an outstanding ack that we
1413  * were hoping to piggy-back, but haven't, so send a ZLB.
1414  */
1415 static void
1416 ng_l2tp_seq_xack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1417 {
1418         const priv_p priv = NG_NODE_PRIVATE(node);
1419         struct l2tp_seq *const seq = &priv->seq;
1420
1421         /* Make sure callout is still active before doing anything */
1422         if (callout_pending(&seq->xack_timer) ||
1423             (!callout_active(&seq->xack_timer)))
1424                 return;
1425
1426         /* Sanity check */
1427         L2TP_SEQ_CHECK(seq);
1428
1429         /* Send a ZLB */
1430         ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1431
1432         /* callout_deactivate() is not needed here
1433             as ng_uncallout() was called by ng_l2tp_xmit_ctrl() */
1434
1435         /* Sanity check */
1436         L2TP_SEQ_CHECK(seq);
1437 }
1438
1439 /*
1440  * Handle a transmit timeout. The peer has failed to respond
1441  * with an ack for our packet, so retransmit it.
1442  */
1443 static void
1444 ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1445 {
1446         const priv_p priv = NG_NODE_PRIVATE(node);
1447         struct l2tp_seq *const seq = &priv->seq;
1448         struct mbuf *m;
1449         u_int delay;
1450
1451         /* Make sure callout is still active before doing anything */
1452         if (callout_pending(&seq->rack_timer) ||
1453             (!callout_active(&seq->rack_timer)))
1454                 return;
1455
1456         /* Sanity check */
1457         L2TP_SEQ_CHECK(seq);
1458
1459         priv->stats.xmitRetransmits++;
1460
1461         /* Have we reached the retransmit limit? If so, notify owner. */
1462         if (seq->rexmits++ >= priv->conf.rexmit_max)
1463                 ng_l2tp_seq_failure(priv);
1464
1465         /* Restart timer, this time with an increased delay */
1466         delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
1467         if (delay > priv->conf.rexmit_max_to)
1468                 delay = priv->conf.rexmit_max_to;
1469         ng_callout(&seq->rack_timer, node, NULL,
1470             hz * delay, ng_l2tp_seq_rack_timeout, NULL, 0);
1471
1472         /* Do slow-start/congestion algorithm windowing algorithm */
1473         seq->ns = seq->rack;
1474         seq->ssth = (seq->cwnd + 1) / 2;
1475         seq->cwnd = 1;
1476         seq->acks = 0;
1477
1478         /* Retransmit oldest unack'd packet */
1479         if ((m = L2TP_COPY_MBUF(seq->xwin[0], M_DONTWAIT)) == NULL)
1480                 priv->stats.memoryFailures++;
1481         else
1482                 ng_l2tp_xmit_ctrl(priv, m, seq->ns++);
1483
1484         /* callout_deactivate() is not needed here
1485             as ng_callout() is getting called each time */
1486
1487         /* Sanity check */
1488         L2TP_SEQ_CHECK(seq);
1489 }
1490
1491 /*
1492  * Transmit a control stream packet, payload optional.
1493  * The transmit sequence number is not incremented.
1494  */
1495 static int
1496 ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns)
1497 {
1498         struct l2tp_seq *const seq = &priv->seq;
1499         u_int16_t session_id = 0;
1500         int error;
1501
1502         mtx_lock(&seq->mtx);
1503
1504         /* Stop ack timer: we're sending an ack with this packet.
1505            Doing this before to keep state predictable after error. */
1506         if (callout_active(&seq->xack_timer))
1507                 ng_uncallout(&seq->xack_timer, priv->node);
1508
1509         seq->xack = seq->nr;
1510
1511         mtx_unlock(&seq->mtx);
1512
1513         /* If no mbuf passed, send an empty packet (ZLB) */
1514         if (m == NULL) {
1515
1516                 /* Create a new mbuf for ZLB packet */
1517                 MGETHDR(m, M_DONTWAIT, MT_DATA);
1518                 if (m == NULL) {
1519                         priv->stats.memoryFailures++;
1520                         return (ENOBUFS);
1521                 }
1522                 m->m_len = m->m_pkthdr.len = 12;
1523                 m->m_pkthdr.rcvif = NULL;
1524                 priv->stats.xmitZLBs++;
1525         } else {
1526
1527                 /* Strip off session ID */
1528                 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
1529                         priv->stats.memoryFailures++;
1530                         return (ENOBUFS);
1531                 }
1532                 session_id = (mtod(m, u_int8_t *)[0] << 8) + mtod(m, u_int8_t *)[1];
1533
1534                 /* Make room for L2TP header */
1535                 M_PREPEND(m, 10, M_DONTWAIT);   /* - 2 + 12 = 10 */
1536                 if (m == NULL) {
1537                         priv->stats.memoryFailures++;
1538                         return (ENOBUFS);
1539                 }
1540         }
1541
1542         /* Fill in L2TP header */
1543         mtod(m, u_int16_t *)[0] = htons(L2TP_CTRL_HDR);
1544         mtod(m, u_int16_t *)[1] = htons(m->m_pkthdr.len);
1545         mtod(m, u_int16_t *)[2] = htons(priv->conf.peer_id);
1546         mtod(m, u_int16_t *)[3] = htons(session_id);
1547         mtod(m, u_int16_t *)[4] = htons(ns);
1548         mtod(m, u_int16_t *)[5] = htons(seq->nr);
1549
1550         /* Update sequence number info and stats */
1551         priv->stats.xmitPackets++;
1552         priv->stats.xmitOctets += m->m_pkthdr.len;
1553
1554         /* Send packet */
1555         NG_SEND_DATA_ONLY(error, priv->lower, m);
1556         return (error);
1557 }
1558
1559 #ifdef INVARIANTS
1560 /*
1561  * Sanity check sequence number state.
1562  */
1563 static void
1564 ng_l2tp_seq_check(struct l2tp_seq *seq)
1565 {
1566         int self_unack, peer_unack;
1567         int i;
1568
1569 #define CHECK(p)        KASSERT((p), ("%s: not: %s", __func__, #p))
1570
1571         mtx_lock(&seq->mtx);
1572
1573         self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack);
1574         peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack);
1575         CHECK(seq->wmax <= L2TP_MAX_XWIN);
1576         CHECK(seq->cwnd >= 1);
1577         CHECK(seq->cwnd <= seq->wmax);
1578         CHECK(seq->ssth >= 1);
1579         CHECK(seq->ssth <= seq->wmax);
1580         if (seq->cwnd < seq->ssth)
1581                 CHECK(seq->acks == 0);
1582         else
1583                 CHECK(seq->acks <= seq->cwnd);
1584         CHECK(self_unack >= 0);
1585         CHECK(peer_unack >= 0);
1586         CHECK(peer_unack <= seq->wmax);
1587         CHECK((self_unack == 0) ^ callout_active(&seq->xack_timer));
1588         CHECK((peer_unack == 0) ^ callout_active(&seq->rack_timer));
1589         for (i = 0; i < peer_unack; i++)
1590                 CHECK(seq->xwin[i] != NULL);
1591         for ( ; i < seq->cwnd; i++)         /* verify peer's recv window full */
1592                 CHECK(seq->xwin[i] == NULL);
1593
1594         mtx_unlock(&seq->mtx);
1595
1596 #undef CHECK
1597 }
1598 #endif  /* INVARIANTS */