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sys/netgraph/ng_l2tp.c
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1 2 /* 3 * Copyright (c) 2001-2002 Packet Design, LLC. 4 * All rights reserved. 5 * 6 * Subject to the following obligations and disclaimer of warranty, 7 * use and redistribution of this software, in source or object code 8 * forms, with or without modifications are expressly permitted by 9 * Packet Design; provided, however, that: 10 * 11 * (i) Any and all reproductions of the source or object code 12 * must include the copyright notice above and the following 13 * disclaimer of warranties; and 14 * (ii) No rights are granted, in any manner or form, to use 15 * Packet Design trademarks, including the mark "PACKET DESIGN" 16 * on advertising, endorsements, or otherwise except as such 17 * appears in the above copyright notice or in the software. 18 * 19 * THIS SOFTWARE IS BEING PROVIDED BY PACKET DESIGN "AS IS", AND 20 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, PACKET DESIGN MAKES NO 21 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING 22 * THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED 23 * WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, 24 * OR NON-INFRINGEMENT. PACKET DESIGN DOES NOT WARRANT, GUARANTEE, 25 * OR MAKE ANY REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS 26 * OF THE USE OF THIS SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, 27 * RELIABILITY OR OTHERWISE. IN NO EVENT SHALL PACKET DESIGN BE 28 * LIABLE FOR ANY DAMAGES RESULTING FROM OR ARISING OUT OF ANY USE 29 * OF THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY DIRECT, 30 * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, PUNITIVE, OR CONSEQUENTIAL 31 * DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, LOSS OF 32 * USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY THEORY OF 33 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF 35 * THE USE OF THIS SOFTWARE, EVEN IF PACKET DESIGN IS ADVISED OF 36 * THE POSSIBILITY OF SUCH DAMAGE. 37 * 38 * Author: Archie Cobbs <archie@freebsd.org> 39 * 40 * $FreeBSD$ 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 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 16 /* 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 /* 104 * Sequence number state 105 * 106 * Invariants: 107 * - If cwnd < ssth, we're doing slow start, otherwise congestion avoidance 108 * - The number of unacknowledged xmit packets is (ns - rack) <= seq->wmax 109 * - The first (ns - rack) mbuf's in xwin[] array are copies of these 110 * unacknowledged packets; the remainder of xwin[] consists first of 111 * zero or more further untransmitted packets in the transmit queue 112 * - We try to keep the peer's receive window as full as possible. 113 * Therefore, (i < cwnd && xwin[i] != NULL) implies (ns - rack) > i. 114 * - rack_timer is running iff (ns - rack) > 0 (unack'd xmit'd pkts) 115 * - If xack != nr, there are unacknowledged recv packet(s) (delayed ack) 116 * - xack_timer is running iff xack != nr (unack'd rec'd pkts) 117 */ 118 struct l2tp_seq { 119 u_int16_t ns; /* next xmit seq we send */ 120 u_int16_t nr; /* next recv seq we expect */ 121 u_int16_t rack; /* last 'nr' we rec'd */ 122 u_int16_t xack; /* last 'nr' we sent */ 123 u_int16_t wmax; /* peer's max recv window */ 124 u_int16_t cwnd; /* current congestion window */ 125 u_int16_t ssth; /* slow start threshold */ 126 u_int16_t acks; /* # consecutive acks rec'd */ 127 u_int16_t rexmits; /* # retransmits sent */ 128 u_int16_t max_rexmits; /* max # retransmits sent */ 129 u_int16_t max_rexmit_to; /* max retransmit timeout */ 130 struct callout rack_timer; /* retransmit timer */ 131 struct callout xack_timer; /* delayed ack timer */ 132 u_char rack_timer_running; /* xmit timer running */ 133 u_char xack_timer_running; /* ack timer running */ 134 struct mbuf *xwin[L2TP_MAX_XWIN]; /* transmit window */ 135 }; 136 137 /* Node private data */ 138 struct ng_l2tp_private { 139 node_p node; /* back pointer to node */ 140 hook_p ctrl; /* hook to upper layers */ 141 hook_p lower; /* hook to lower layers */ 142 struct ng_l2tp_config conf; /* node configuration */ 143 struct ng_l2tp_stats stats; /* node statistics */ 144 struct l2tp_seq seq; /* ctrl sequence number state */ 145 char *ftarget; /* failure message target */ 146 }; 147 typedef struct ng_l2tp_private *priv_p; 148 149 /* Hook private data (data session hooks only) */ 150 struct ng_l2tp_hook_private { 151 struct ng_l2tp_sess_config conf; /* hook/session config */ 152 u_int16_t ns; /* data ns sequence number */ 153 u_int16_t nr; /* data nr sequence number */ 154 }; 155 typedef struct ng_l2tp_hook_private *hookpriv_p; 156 157 /* Netgraph node methods */ 158 static ng_constructor_t ng_l2tp_constructor; 159 static ng_rcvmsg_t ng_l2tp_rcvmsg; 160 static ng_shutdown_t ng_l2tp_shutdown; 161 static ng_newhook_t ng_l2tp_newhook; 162 static ng_rcvdata_t ng_l2tp_rcvdata; 163 static ng_disconnect_t ng_l2tp_disconnect; 164 165 /* Internal functions */ 166 static int ng_l2tp_recv_lower(node_p node, struct mbuf *m, meta_p meta); 167 static int ng_l2tp_recv_ctrl(node_p node, struct mbuf *m, meta_p meta); 168 static int ng_l2tp_recv_data(node_p node, 169 struct mbuf *m, meta_p meta, hookpriv_p hpriv); 170 171 static int ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns); 172 173 static void ng_l2tp_seq_init(priv_p priv); 174 static int ng_l2tp_seq_adjust(priv_p priv, 175 const struct ng_l2tp_config *conf); 176 static void ng_l2tp_seq_reset(priv_p priv); 177 static void ng_l2tp_seq_failure(priv_p priv); 178 static void ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr); 179 static int ng_l2tp_seq_recv_ns(priv_p priv, u_int16_t ns); 180 static void ng_l2tp_seq_xack_timeout(void *arg); 181 static void ng_l2tp_seq_rack_timeout(void *arg); 182 183 #ifdef INVARIANTS 184 static void ng_l2tp_seq_check(struct l2tp_seq *seq); 185 #endif 186 187 /* Parse type for struct ng_l2tp_config */ 188 static const struct ng_parse_struct_field 189 ng_l2tp_config_type_fields[] = NG_L2TP_CONFIG_TYPE_INFO; 190 static const struct ng_parse_type ng_l2tp_config_type = { 191 &ng_parse_struct_type, 192 &ng_l2tp_config_type_fields, 193 }; 194 195 /* Parse type for struct ng_l2tp_sess_config */ 196 static const struct ng_parse_struct_field 197 ng_l2tp_sess_config_type_fields[] = NG_L2TP_SESS_CONFIG_TYPE_INFO; 198 static const struct ng_parse_type ng_l2tp_sess_config_type = { 199 &ng_parse_struct_type, 200 &ng_l2tp_sess_config_type_fields, 201 }; 202 203 /* Parse type for struct ng_l2tp_stats */ 204 static const struct ng_parse_struct_field 205 ng_l2tp_stats_type_fields[] = NG_L2TP_STATS_TYPE_INFO; 206 static const struct ng_parse_type ng_l2tp_stats_type = { 207 &ng_parse_struct_type, 208 &ng_l2tp_stats_type_fields 209 }; 210 211 /* List of commands and how to convert arguments to/from ASCII */ 212 static const struct ng_cmdlist ng_l2tp_cmdlist[] = { 213 { 214 NGM_L2TP_COOKIE, 215 NGM_L2TP_SET_CONFIG, 216 "setconfig", 217 &ng_l2tp_config_type, 218 NULL 219 }, 220 { 221 NGM_L2TP_COOKIE, 222 NGM_L2TP_GET_CONFIG, 223 "getconfig", 224 NULL, 225 &ng_l2tp_config_type 226 }, 227 { 228 NGM_L2TP_COOKIE, 229 NGM_L2TP_SET_SESS_CONFIG, 230 "setsessconfig", 231 &ng_l2tp_sess_config_type, 232 NULL 233 }, 234 { 235 NGM_L2TP_COOKIE, 236 NGM_L2TP_GET_SESS_CONFIG, 237 "getsessconfig", 238 &ng_parse_hint16_type, 239 &ng_l2tp_sess_config_type 240 }, 241 { 242 NGM_L2TP_COOKIE, 243 NGM_L2TP_GET_STATS, 244 "getstats", 245 NULL, 246 &ng_l2tp_stats_type 247 }, 248 { 249 NGM_L2TP_COOKIE, 250 NGM_L2TP_CLR_STATS, 251 "clrstats", 252 NULL, 253 NULL 254 }, 255 { 256 NGM_L2TP_COOKIE, 257 NGM_L2TP_GETCLR_STATS, 258 "getclrstats", 259 NULL, 260 &ng_l2tp_stats_type 261 }, 262 { 263 NGM_L2TP_COOKIE, 264 NGM_L2TP_ACK_FAILURE, 265 "ackfailure", 266 NULL, 267 NULL 268 }, 269 { 0 } 270 }; 271 272 /* Node type descriptor */ 273 static struct ng_type ng_l2tp_typestruct = { 274 NG_VERSION, 275 NG_L2TP_NODE_TYPE, 276 NULL, 277 ng_l2tp_constructor, 278 ng_l2tp_rcvmsg, 279 ng_l2tp_shutdown, 280 ng_l2tp_newhook, 281 NULL, 282 NULL, 283 ng_l2tp_rcvdata, 284 ng_l2tp_rcvdata, 285 ng_l2tp_disconnect, 286 ng_l2tp_cmdlist 287 }; 288 NETGRAPH_INIT(l2tp, &ng_l2tp_typestruct); 289 290 /* Sequence number state sanity checking */ 291 #ifdef INVARIANTS 292 #define L2TP_SEQ_CHECK(seq) ng_l2tp_seq_check(seq) 293 #else 294 #define L2TP_SEQ_CHECK(x) do { } while (0) 295 #endif 296 297 /* mem*() macros */ 298 #define memmove(d, s, l) ovbcopy(s, d, l) 299 #define memset(d, z, l) bzero(d, l) /* XXX */ 300 301 /* Whether to use m_copypacket() or m_dup() */ 302 #define L2TP_COPY_MBUF m_copypacket 303 304 /************************************************************************ 305 NETGRAPH NODE STUFF 306 ************************************************************************/ 307 308 /* 309 * Node type constructor 310 */ 311 static int 312 ng_l2tp_constructor(node_p *nodep) 313 { 314 priv_p priv; 315 int error; 316 317 /* Allocate private structure */ 318 MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO); 319 if (priv == NULL) 320 return (ENOMEM); 321 322 /* Apply a semi-reasonable default configuration */ 323 priv->conf.peer_win = 1; 324 priv->conf.rexmit_max = L2TP_MAX_REXMIT; 325 priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO; 326 327 /* Initialize sequence number state */ 328 ng_l2tp_seq_init(priv); 329 330 /* Call generic node constructor */ 331 if ((error = ng_make_node_common(&ng_l2tp_typestruct, nodep))) { 332 FREE(priv, M_NETGRAPH_L2TP); 333 return (error); 334 } 335 NG_NODE_SET_PRIVATE(*nodep, priv); 336 priv->node = *nodep; 337 338 /* Done */ 339 return (0); 340 } 341 342 /* 343 * Give our OK for a hook to be added. 344 */ 345 static int 346 ng_l2tp_newhook(node_p node, hook_p hook, const char *name) 347 { 348 const priv_p priv = NG_NODE_PRIVATE(node); 349 350 /* Check hook name */ 351 if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) { 352 if (priv->ctrl != NULL) 353 return (EISCONN); 354 priv->ctrl = hook; 355 } else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) { 356 if (priv->lower != NULL) 357 return (EISCONN); 358 priv->lower = hook; 359 } else { 360 static const char hexdig[16] = "0123456789abcdef"; 361 u_int16_t session_id; 362 hookpriv_p hpriv; 363 const char *hex; 364 int i; 365 int j; 366 367 /* Parse hook name to get session ID */ 368 if (strncmp(name, NG_L2TP_HOOK_SESSION_P, 369 sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0) 370 return (EINVAL); 371 hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1; 372 for (session_id = i = 0; i < 4; i++) { 373 for (j = 0; j < 16 && hex[i] != hexdig[j]; j++); 374 if (j == 16) 375 return (EINVAL); 376 session_id = (session_id << 4) | j; 377 } 378 if (hex[i] != '\0') 379 return (EINVAL); 380 381 /* Create hook private structure */ 382 MALLOC(hpriv, hookpriv_p, 383 sizeof(*hpriv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO); 384 if (hpriv == NULL) 385 return (ENOMEM); 386 hpriv->conf.session_id = htons(session_id); 387 hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ; 388 hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ; 389 NG_HOOK_SET_PRIVATE(hook, hpriv); 390 } 391 392 /* Done */ 393 return (0); 394 } 395 396 /* 397 * Receive a control message. 398 */ 399 static int 400 ng_l2tp_rcvmsg(node_p node, struct ng_mesg *msg, 401 const char *raddr, struct ng_mesg **rptr) 402 { 403 const priv_p priv = NG_NODE_PRIVATE(node); 404 struct ng_mesg *resp = NULL; 405 int error = 0; 406 407 switch (msg->header.typecookie) { 408 case NGM_L2TP_COOKIE: 409 switch (msg->header.cmd) { 410 case NGM_L2TP_SET_CONFIG: 411 { 412 struct ng_l2tp_config *const conf = 413 (struct ng_l2tp_config *)msg->data; 414 415 /* Check for invalid or illegal config */ 416 if (msg->header.arglen != sizeof(*conf)) { 417 error = EINVAL; 418 break; 419 } 420 conf->enabled = !!conf->enabled; 421 conf->match_id = !!conf->match_id; 422 conf->tunnel_id = htons(conf->tunnel_id); 423 conf->peer_id = htons(conf->peer_id); 424 if (priv->conf.enabled 425 && ((priv->conf.tunnel_id != 0 426 && conf->tunnel_id != priv->conf.tunnel_id) 427 || ((priv->conf.peer_id != 0 428 && conf->peer_id != priv->conf.peer_id)))) { 429 error = EBUSY; 430 break; 431 } 432 433 /* Save calling node as failure target */ 434 if (priv->ftarget != NULL) 435 FREE(priv->ftarget, M_NETGRAPH_L2TP); 436 MALLOC(priv->ftarget, char *, 437 strlen(raddr) + 1, M_NETGRAPH_L2TP, M_NOWAIT); 438 if (priv->ftarget == NULL) { 439 error = ENOMEM; 440 break; 441 } 442 strcpy(priv->ftarget, raddr); 443 444 /* Adjust sequence number state */ 445 if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0) 446 break; 447 448 /* Update node's config */ 449 priv->conf = *conf; 450 break; 451 } 452 case NGM_L2TP_GET_CONFIG: 453 { 454 struct ng_l2tp_config *conf; 455 456 NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT); 457 if (resp == NULL) { 458 error = ENOMEM; 459 break; 460 } 461 conf = (struct ng_l2tp_config *)resp->data; 462 *conf = priv->conf; 463 464 /* Put ID's in host order */ 465 conf->tunnel_id = ntohs(conf->tunnel_id); 466 conf->peer_id = ntohs(conf->peer_id); 467 break; 468 } 469 case NGM_L2TP_SET_SESS_CONFIG: 470 { 471 struct ng_l2tp_sess_config *const conf = 472 (struct ng_l2tp_sess_config *)msg->data; 473 hookpriv_p hpriv = NULL; 474 hook_p hook; 475 476 /* Check for invalid or illegal config */ 477 if (msg->header.arglen != sizeof(*conf)) { 478 error = EINVAL; 479 break; 480 } 481 482 /* Put ID's in network order */ 483 conf->session_id = htons(conf->session_id); 484 conf->peer_id = htons(conf->peer_id); 485 486 /* Find matching hook */ 487 LIST_FOREACH(hook, &node->hooks, hooks) { 488 if ((hpriv = NG_HOOK_PRIVATE(hook)) == NULL) 489 continue; 490 if (hpriv->conf.session_id == conf->session_id) 491 break; 492 } 493 if (hook == NULL) { 494 error = ENOENT; 495 break; 496 } 497 498 /* Update hook's config */ 499 hpriv->conf = *conf; 500 break; 501 } 502 case NGM_L2TP_GET_SESS_CONFIG: 503 { 504 struct ng_l2tp_sess_config *conf; 505 hookpriv_p hpriv = NULL; 506 u_int16_t session_id; 507 hook_p hook; 508 509 /* Get session ID */ 510 if (msg->header.arglen != sizeof(session_id)) { 511 error = EINVAL; 512 break; 513 } 514 memcpy(&session_id, msg->data, 2); 515 session_id = htons(session_id); 516 517 /* Find matching hook */ 518 LIST_FOREACH(hook, &node->hooks, hooks) { 519 if ((hpriv = NG_HOOK_PRIVATE(hook)) == NULL) 520 continue; 521 if (hpriv->conf.session_id == session_id) 522 break; 523 } 524 if (hook == NULL) { 525 error = ENOENT; 526 break; 527 } 528 529 /* Send response */ 530 NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_NOWAIT); 531 if (resp == NULL) { 532 error = ENOMEM; 533 break; 534 } 535 conf = (struct ng_l2tp_sess_config *)resp->data; 536 *conf = hpriv->conf; 537 538 /* Put ID's in host order */ 539 conf->session_id = ntohs(conf->session_id); 540 conf->peer_id = ntohs(conf->peer_id); 541 break; 542 } 543 case NGM_L2TP_GET_STATS: 544 case NGM_L2TP_CLR_STATS: 545 case NGM_L2TP_GETCLR_STATS: 546 { 547 if (msg->header.cmd != NGM_L2TP_CLR_STATS) { 548 NG_MKRESPONSE(resp, msg, 549 sizeof(priv->stats), M_NOWAIT); 550 if (resp == NULL) { 551 error = ENOMEM; 552 break; 553 } 554 memcpy(resp->data, 555 &priv->stats, sizeof(priv->stats)); 556 } 557 if (msg->header.cmd != NGM_L2TP_GET_STATS) 558 memset(&priv->stats, 0, sizeof(priv->stats)); 559 break; 560 } 561 default: 562 error = EINVAL; 563 break; 564 } 565 break; 566 default: 567 error = EINVAL; 568 break; 569 } 570 if (rptr) 571 *rptr = resp; 572 else if (resp) 573 FREE(resp, M_NETGRAPH); 574 FREE(msg, M_NETGRAPH); 575 return (error); 576 } 577 578 /* 579 * Receive incoming data on a hook. 580 */ 581 static int 582 ng_l2tp_rcvdata(hook_p hook, struct mbuf *m, meta_p meta) 583 { 584 const node_p node = NG_HOOK_NODE(hook); 585 const priv_p priv = NG_NODE_PRIVATE(node); 586 int error; 587 588 /* Sanity check */ 589 L2TP_SEQ_CHECK(&priv->seq); 590 591 /* If not configured, reject */ 592 if (!priv->conf.enabled) { 593 NG_FREE_DATA(m, meta); 594 return (ENXIO); 595 } 596 597 /* Handle incoming frame from below */ 598 if (hook == priv->lower) { 599 error = ng_l2tp_recv_lower(node, m, meta); 600 goto done; 601 } 602 603 /* Handle outgoing control frame */ 604 if (hook == priv->ctrl) { 605 error = ng_l2tp_recv_ctrl(node, m, meta); 606 goto done; 607 } 608 609 /* Handle outgoing data frame */ 610 error = ng_l2tp_recv_data(node, m, meta, NG_HOOK_PRIVATE(hook)); 611 612 done: 613 /* Done */ 614 L2TP_SEQ_CHECK(&priv->seq); 615 return (error); 616 } 617 618 /* 619 * Destroy node 620 */ 621 static int 622 ng_l2tp_shutdown(node_p node) 623 { 624 const priv_p priv = NG_NODE_PRIVATE(node); 625 struct l2tp_seq *const seq = &priv->seq; 626 627 /* Sanity check */ 628 L2TP_SEQ_CHECK(seq); 629 630 /* Reset sequence number state */ 631 node->flags |= NG_INVALID; 632 ng_l2tp_seq_reset(priv); 633 ng_cutlinks(node); 634 ng_unname(node); 635 636 /* Free private data if neither timer is running */ 637 if (!seq->rack_timer_running && !seq->xack_timer_running) { 638 if (priv->ftarget != NULL) 639 FREE(priv->ftarget, M_NETGRAPH_L2TP); 640 FREE(priv, M_NETGRAPH_L2TP); 641 NG_NODE_SET_PRIVATE(node, NULL); 642 } 643 644 /* Unref node */ 645 NG_NODE_UNREF(node); 646 return (0); 647 } 648 649 /* 650 * Hook disconnection 651 */ 652 static int 653 ng_l2tp_disconnect(hook_p hook) 654 { 655 const node_p node = NG_HOOK_NODE(hook); 656 const priv_p priv = NG_NODE_PRIVATE(node); 657 658 /* Zero out hook pointer */ 659 if (hook == priv->ctrl) 660 priv->ctrl = NULL; 661 else if (hook == priv->lower) 662 priv->lower = NULL; 663 else { 664 FREE(NG_HOOK_PRIVATE(hook), M_NETGRAPH_L2TP); 665 NG_HOOK_SET_PRIVATE(hook, NULL); 666 } 667 668 /* Go away if no longer connected to anything */ 669 if (node->numhooks == 0) 670 ng_rmnode(node); 671 return (0); 672 } 673 674 /************************************************************************* 675 INTERNAL FUNCTIONS 676 *************************************************************************/ 677 678 /* 679 * Handle an incoming frame from below. 680 */ 681 static int 682 ng_l2tp_recv_lower(node_p node, struct mbuf *m, meta_p meta) 683 { 684 static const u_int16_t req_bits[2][2] = { 685 { L2TP_DATA_0BITS, L2TP_DATA_1BITS }, 686 { L2TP_CTRL_0BITS, L2TP_CTRL_1BITS }, 687 }; 688 const priv_p priv = NG_NODE_PRIVATE(node); 689 hookpriv_p hpriv = NULL; 690 hook_p hook = NULL; 691 u_int16_t ids[2]; 692 u_int16_t hdr; 693 u_int16_t ns; 694 u_int16_t nr; 695 int is_ctrl; 696 int error; 697 int len; 698 699 /* Update stats */ 700 priv->stats.recvPackets++; 701 priv->stats.recvOctets += m->m_pkthdr.len; 702 703 /* Get initial header */ 704 if (m->m_pkthdr.len < 6) { 705 priv->stats.recvRunts++; 706 NG_FREE_DATA(m, meta); 707 return (EINVAL); 708 } 709 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) { 710 priv->stats.memoryFailures++; 711 NG_FREE_META(meta); 712 return (EINVAL); 713 } 714 hdr = ntohs(*mtod(m, u_int16_t *)); 715 m_adj(m, 2); 716 717 /* Check required header bits and minimum length */ 718 is_ctrl = (hdr & L2TP_HDR_CTRL) != 0; 719 if ((hdr & req_bits[is_ctrl][0]) != 0 720 || (~hdr & req_bits[is_ctrl][1]) != 0) { 721 priv->stats.recvInvalid++; 722 NG_FREE_DATA(m, meta); 723 return (EINVAL); 724 } 725 if (m->m_pkthdr.len < 4 /* tunnel, session id */ 726 + (2 * ((hdr & L2TP_HDR_LEN) != 0)) /* length field */ 727 + (4 * ((hdr & L2TP_HDR_SEQ) != 0)) /* seq # fields */ 728 + (2 * ((hdr & L2TP_HDR_OFF) != 0))) { /* offset field */ 729 priv->stats.recvRunts++; 730 NG_FREE_DATA(m, meta); 731 return (EINVAL); 732 } 733 734 /* Get and validate length field if present */ 735 if ((hdr & L2TP_HDR_LEN) != 0) { 736 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) { 737 priv->stats.memoryFailures++; 738 NG_FREE_META(meta); 739 return (EINVAL); 740 } 741 len = (u_int16_t)ntohs(*mtod(m, u_int16_t *)) - 4; 742 m_adj(m, 2); 743 if (len < 0 || len > m->m_pkthdr.len) { 744 priv->stats.recvInvalid++; 745 NG_FREE_DATA(m, meta); 746 return (EINVAL); 747 } 748 if (len < m->m_pkthdr.len) /* trim extra bytes */ 749 m_adj(m, -(m->m_pkthdr.len - len)); 750 } 751 752 /* Get tunnel ID and session ID */ 753 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) { 754 priv->stats.memoryFailures++; 755 NG_FREE_META(meta); 756 return (EINVAL); 757 } 758 memcpy(ids, mtod(m, u_int16_t *), 4); 759 m_adj(m, 4); 760 761 /* Check tunnel ID */ 762 if (ids[0] != priv->conf.tunnel_id 763 && (priv->conf.match_id || ids[0] != 0)) { 764 priv->stats.recvWrongTunnel++; 765 NG_FREE_DATA(m, meta); 766 return (EADDRNOTAVAIL); 767 } 768 769 /* Check session ID (for data packets only) */ 770 if ((hdr & L2TP_HDR_CTRL) == 0) { 771 LIST_FOREACH(hook, &node->hooks, hooks) { 772 if ((hpriv = NG_HOOK_PRIVATE(hook)) == NULL) 773 continue; 774 if (hpriv->conf.session_id == ids[1]) 775 break; 776 } 777 if (hook == NULL) { 778 priv->stats.recvUnknownSID++; 779 NG_FREE_DATA(m, meta); 780 return (ENOTCONN); 781 } 782 hpriv = NG_HOOK_PRIVATE(hook); 783 } 784 785 /* Get Ns, Nr fields if present */ 786 if ((hdr & L2TP_HDR_SEQ) != 0) { 787 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) { 788 priv->stats.memoryFailures++; 789 NG_FREE_META(meta); 790 return (EINVAL); 791 } 792 memcpy(&ns, &mtod(m, u_int16_t *)[0], 2); 793 ns = ntohs(ns); 794 memcpy(&nr, &mtod(m, u_int16_t *)[1], 2); 795 nr = ntohs(nr); 796 m_adj(m, 4); 797 } 798 799 /* Strip offset padding if present */ 800 if ((hdr & L2TP_HDR_OFF) != 0) { 801 u_int16_t offset; 802 803 /* Get length of offset padding */ 804 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) { 805 priv->stats.memoryFailures++; 806 NG_FREE_META(meta); 807 return (EINVAL); 808 } 809 memcpy(&offset, mtod(m, u_int16_t *), 2); 810 offset = ntohs(offset); 811 812 /* Trim offset padding */ 813 if ((2+offset) > m->m_pkthdr.len) { 814 priv->stats.recvInvalid++; 815 NG_FREE_DATA(m, meta); 816 return (EINVAL); 817 } 818 m_adj(m, 2+offset); 819 } 820 821 /* Handle control packets */ 822 if ((hdr & L2TP_HDR_CTRL) != 0) { 823 824 /* Handle receive ack sequence number Nr */ 825 ng_l2tp_seq_recv_nr(priv, nr); 826 827 /* Discard ZLB packets */ 828 if (m->m_pkthdr.len == 0) { 829 priv->stats.recvZLBs++; 830 NG_FREE_DATA(m, meta); 831 return (0); 832 } 833 834 /* 835 * Prepend session ID to packet here: we don't want to accept 836 * the send sequence number Ns if we have to drop the packet 837 * later because of a memory error, because then the upper 838 * layer would never get the packet. 839 */ 840 M_PREPEND(m, 2, M_DONTWAIT); 841 if (m == NULL) { 842 priv->stats.memoryFailures++; 843 NG_FREE_META(meta); 844 return (ENOBUFS); 845 } 846 memcpy(mtod(m, u_int16_t *), &ids[1], 2); 847 848 /* Now handle send sequence number */ 849 if (ng_l2tp_seq_recv_ns(priv, ns) == -1) { 850 NG_FREE_DATA(m, meta); 851 return (0); 852 } 853 854 /* Deliver packet to upper layers */ 855 NG_SEND_DATA(error, priv->ctrl, m, meta); 856 return (error); 857 } 858 859 /* Follow peer's lead in data sequencing, if configured to do so */ 860 if (!hpriv->conf.control_dseq) 861 hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0); 862 863 /* Handle data sequence numbers if present and enabled */ 864 if ((hdr & L2TP_HDR_SEQ) != 0) { 865 if (hpriv->conf.enable_dseq 866 && L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) { 867 NG_FREE_DATA(m, meta); /* duplicate or out of order */ 868 priv->stats.recvDataDrops++; 869 return (0); 870 } 871 hpriv->nr = ns + 1; 872 } 873 874 /* Drop empty data packets */ 875 if (m->m_pkthdr.len == 0) { 876 NG_FREE_DATA(m, meta); 877 return (0); 878 } 879 880 /* Deliver data */ 881 NG_SEND_DATA(error, hook, m, meta); 882 return (error); 883 } 884 885 /* 886 * Handle an outgoing control frame. 887 */ 888 static int 889 ng_l2tp_recv_ctrl(node_p node, struct mbuf *m, meta_p meta) 890 { 891 const priv_p priv = NG_NODE_PRIVATE(node); 892 struct l2tp_seq *const seq = &priv->seq; 893 int i; 894 895 /* Discard meta XXX should queue meta's along with packet */ 896 NG_FREE_META(meta); 897 898 /* Packet should have session ID prepended */ 899 if (m->m_pkthdr.len < 2) { 900 priv->stats.xmitInvalid++; 901 m_freem(m); 902 return (EINVAL); 903 } 904 905 /* Check max length */ 906 if (m->m_pkthdr.len >= 0x10000 - 14) { 907 priv->stats.xmitTooBig++; 908 m_freem(m); 909 return (EOVERFLOW); 910 } 911 912 /* Find next empty slot in transmit queue */ 913 for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++); 914 if (i == L2TP_MAX_XWIN) { 915 priv->stats.xmitDrops++; 916 m_freem(m); 917 return (ENOBUFS); 918 } 919 seq->xwin[i] = m; 920 921 /* Sanity check receive ack timer state */ 922 KASSERT((i == 0) ^ seq->rack_timer_running, 923 ("%s: xwin %d full but rack timer %srunning", 924 __FUNCTION__, i, seq->rack_timer_running ? "" : "not ")); 925 926 /* If peer's receive window is already full, nothing else to do */ 927 if (i >= seq->cwnd) 928 return (0); 929 930 /* Start retransmit timer if not already running */ 931 if (!seq->rack_timer_running) { 932 callout_reset(&seq->rack_timer, 933 hz, ng_l2tp_seq_rack_timeout, node); 934 seq->rack_timer_running = 1; 935 NG_NODE_REF(node); 936 } 937 938 /* Copy packet */ 939 if ((m = L2TP_COPY_MBUF(seq->xwin[i], M_NOWAIT)) == NULL) { 940 priv->stats.memoryFailures++; 941 return (ENOBUFS); 942 } 943 944 /* Send packet and increment xmit sequence number */ 945 return (ng_l2tp_xmit_ctrl(priv, m, seq->ns++)); 946 } 947 948 /* 949 * Handle an outgoing data frame. 950 */ 951 static int 952 ng_l2tp_recv_data(node_p node, struct mbuf *m, meta_p meta, hookpriv_p hpriv) 953 { 954 const priv_p priv = NG_NODE_PRIVATE(node); 955 u_int16_t hdr; 956 int error; 957 int i = 1; 958 959 /* Check max length */ 960 if (m->m_pkthdr.len >= 0x10000 - 12) { 961 priv->stats.xmitDataTooBig++; 962 NG_FREE_META(meta); 963 m_freem(m); 964 return (EOVERFLOW); 965 } 966 967 /* Prepend L2TP header */ 968 M_PREPEND(m, 6 969 + (2 * (hpriv->conf.include_length != 0)) 970 + (4 * (hpriv->conf.enable_dseq != 0)), 971 M_DONTWAIT); 972 if (m == NULL) { 973 priv->stats.memoryFailures++; 974 NG_FREE_META(meta); 975 return (ENOBUFS); 976 } 977 hdr = L2TP_DATA_HDR; 978 if (hpriv->conf.include_length) { 979 hdr |= L2TP_HDR_LEN; 980 mtod(m, u_int16_t *)[i++] = htons(m->m_pkthdr.len); 981 } 982 mtod(m, u_int16_t *)[i++] = priv->conf.peer_id; 983 mtod(m, u_int16_t *)[i++] = hpriv->conf.peer_id; 984 if (hpriv->conf.enable_dseq) { 985 hdr |= L2TP_HDR_SEQ; 986 mtod(m, u_int16_t *)[i++] = htons(hpriv->ns); 987 mtod(m, u_int16_t *)[i++] = htons(hpriv->nr); 988 hpriv->ns++; 989 } 990 mtod(m, u_int16_t *)[0] = htons(hdr); 991 992 /* Send packet */ 993 NG_SEND_DATA(error, priv->lower, m, meta); 994 return (error); 995 } 996 997 /* 998 * Send a message to our controlling node that we've failed. 999 */ 1000 static void 1001 ng_l2tp_seq_failure(priv_p priv) 1002 { 1003 struct ng_mesg *msg; 1004 1005 NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_NOWAIT); 1006 if (msg == NULL) 1007 return; 1008 (void)ng_send_msg(priv->node, msg, priv->ftarget, NULL); 1009 } 1010 1011 /************************************************************************ 1012 SEQUENCE NUMBER HANDLING 1013 ************************************************************************/ 1014 1015 /* 1016 * Initialize sequence number state. 1017 */ 1018 static void 1019 ng_l2tp_seq_init(priv_p priv) 1020 { 1021 struct l2tp_seq *const seq = &priv->seq; 1022 1023 KASSERT(priv->conf.peer_win >= 1, 1024 ("%s: peer_win is zero", __FUNCTION__)); 1025 memset(seq, 0, sizeof(*seq)); 1026 seq->cwnd = 1; 1027 seq->wmax = priv->conf.peer_win; 1028 if (seq->wmax > L2TP_MAX_XWIN) 1029 seq->wmax = L2TP_MAX_XWIN; 1030 seq->ssth = seq->wmax; 1031 seq->max_rexmits = priv->conf.rexmit_max; 1032 seq->max_rexmit_to = priv->conf.rexmit_max_to; 1033 callout_init(&seq->rack_timer); 1034 callout_init(&seq->xack_timer); 1035 L2TP_SEQ_CHECK(seq); 1036 } 1037 1038 /* 1039 * Adjust sequence number state accordingly after reconfiguration. 1040 */ 1041 static int 1042 ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf) 1043 { 1044 struct l2tp_seq *const seq = &priv->seq; 1045 u_int16_t new_wmax; 1046 1047 /* If disabling node, reset state sequence number */ 1048 if (!conf->enabled) { 1049 ng_l2tp_seq_reset(priv); 1050 return (0); 1051 } 1052 1053 /* Adjust peer's max recv window; it can only increase */ 1054 new_wmax = conf->peer_win; 1055 if (new_wmax > L2TP_MAX_XWIN) 1056 new_wmax = L2TP_MAX_XWIN; 1057 if (new_wmax == 0) 1058 return (EINVAL); 1059 if (new_wmax < seq->wmax) 1060 return (EBUSY); 1061 seq->wmax = new_wmax; 1062 1063 /* Update retransmit parameters */ 1064 seq->max_rexmits = conf->rexmit_max; 1065 seq->max_rexmit_to = conf->rexmit_max_to; 1066 1067 /* Done */ 1068 return (0); 1069 } 1070 1071 /* 1072 * Reset sequence number state. 1073 */ 1074 static void 1075 ng_l2tp_seq_reset(priv_p priv) 1076 { 1077 struct l2tp_seq *const seq = &priv->seq; 1078 hookpriv_p hpriv = NULL; 1079 hook_p hook; 1080 int i; 1081 1082 /* Sanity check */ 1083 L2TP_SEQ_CHECK(seq); 1084 1085 /* Stop timers */ 1086 if (seq->rack_timer_running && callout_stop(&seq->rack_timer) == 1) { 1087 seq->rack_timer_running = 0; 1088 NG_NODE_UNREF(priv->node); 1089 } 1090 if (seq->xack_timer_running && callout_stop(&seq->xack_timer) == 1) { 1091 seq->xack_timer_running = 0; 1092 NG_NODE_UNREF(priv->node); 1093 } 1094 1095 /* Free retransmit queue */ 1096 for (i = 0; i < L2TP_MAX_XWIN; i++) { 1097 if (seq->xwin[i] == NULL) 1098 break; 1099 m_freem(seq->xwin[i]); 1100 } 1101 1102 /* Reset session hooks' sequence number states */ 1103 LIST_FOREACH(hook, &priv->node->hooks, hooks) { 1104 if ((hpriv = NG_HOOK_PRIVATE(hook)) == NULL) 1105 continue; 1106 hpriv->conf.control_dseq = 0; 1107 hpriv->conf.enable_dseq = 0; 1108 hpriv->nr = 0; 1109 hpriv->ns = 0; 1110 } 1111 1112 /* Reset node's sequence number state */ 1113 memset(seq, 0, sizeof(*seq)); 1114 seq->cwnd = 1; 1115 seq->wmax = L2TP_MAX_XWIN; 1116 seq->ssth = seq->wmax; 1117 1118 /* Done */ 1119 L2TP_SEQ_CHECK(seq); 1120 } 1121 1122 /* 1123 * Handle receipt of an acknowledgement value (Nr) from peer. 1124 */ 1125 static void 1126 ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr) 1127 { 1128 struct l2tp_seq *const seq = &priv->seq; 1129 struct mbuf *m; 1130 int nack; 1131 int i; 1132 1133 /* Verify peer's ACK is in range */ 1134 if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0) 1135 return; /* duplicate ack */ 1136 if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) { 1137 priv->stats.recvBadAcks++; /* ack for packet not sent */ 1138 return; 1139 } 1140 KASSERT(nack <= L2TP_MAX_XWIN, 1141 ("%s: nack=%d > %d", __FUNCTION__, nack, L2TP_MAX_XWIN)); 1142 1143 /* Update receive ack stats */ 1144 seq->rack = nr; 1145 seq->rexmits = 0; 1146 1147 /* Free acknowledged packets and shift up packets in the xmit queue */ 1148 for (i = 0; i < nack; i++) 1149 m_freem(seq->xwin[i]); 1150 memmove(seq->xwin, seq->xwin + nack, 1151 (L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin)); 1152 memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0, 1153 nack * sizeof(*seq->xwin)); 1154 1155 /* 1156 * Do slow-start/congestion avoidance windowing algorithm described 1157 * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each 1158 * ACK had arrived separately. 1159 */ 1160 if (seq->cwnd < seq->wmax) { 1161 1162 /* Handle slow start phase */ 1163 if (seq->cwnd < seq->ssth) { 1164 seq->cwnd += nack; 1165 nack = 0; 1166 if (seq->cwnd > seq->ssth) { /* into cg.av. phase */ 1167 nack = seq->cwnd - seq->ssth; 1168 seq->cwnd = seq->ssth; 1169 } 1170 } 1171 1172 /* Handle congestion avoidance phase */ 1173 if (seq->cwnd >= seq->ssth) { 1174 seq->acks += nack; 1175 while (seq->acks >= seq->cwnd) { 1176 seq->acks -= seq->cwnd; 1177 if (seq->cwnd < seq->wmax) 1178 seq->cwnd++; 1179 } 1180 } 1181 } 1182 1183 /* Stop xmit timer */ 1184 if (seq->rack_timer_running && callout_stop(&seq->rack_timer) == 1) { 1185 seq->rack_timer_running = 0; 1186 NG_NODE_UNREF(priv->node); 1187 } 1188 1189 /* If transmit queue is empty, we're done for now */ 1190 if (seq->xwin[0] == NULL) 1191 return; 1192 1193 /* Start restransmit timer again */ 1194 callout_reset(&seq->rack_timer, 1195 hz, ng_l2tp_seq_rack_timeout, priv->node); 1196 seq->rack_timer_running = 1; 1197 NG_NODE_REF(priv->node); 1198 1199 /* 1200 * Send more packets, trying to keep peer's receive window full. 1201 * If there is a memory error, pretend packet was sent, as it 1202 * will get retransmitted later anyway. 1203 */ 1204 while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd 1205 && seq->xwin[i] != NULL) { 1206 if ((m = L2TP_COPY_MBUF(seq->xwin[i], M_NOWAIT)) == NULL) 1207 priv->stats.memoryFailures++; 1208 else 1209 ng_l2tp_xmit_ctrl(priv, m, seq->ns); 1210 seq->ns++; 1211 } 1212 } 1213 1214 /* 1215 * Handle receipt of a sequence number value (Ns) from peer. 1216 * We make no attempt to re-order out of order packets. 1217 * 1218 * This function should only be called for non-ZLB packets. 1219 * 1220 * Returns: 1221 * 0 Accept packet 1222 * -1 Drop packet 1223 */ 1224 static int 1225 ng_l2tp_seq_recv_ns(priv_p priv, u_int16_t ns) 1226 { 1227 struct l2tp_seq *const seq = &priv->seq; 1228 1229 /* If not what we expect, drop packet and send an immediate ZLB ack */ 1230 if (ns != seq->nr) { 1231 if (L2TP_SEQ_DIFF(ns, seq->nr) < 0) 1232 priv->stats.recvDuplicates++; 1233 else 1234 priv->stats.recvOutOfOrder++; 1235 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns); 1236 return (-1); 1237 } 1238 1239 /* Update recv sequence number */ 1240 seq->nr++; 1241 1242 /* Start receive ack timer, if not already running */ 1243 if (!seq->xack_timer_running) { 1244 callout_reset(&seq->xack_timer, 1245 L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout, priv->node); 1246 seq->xack_timer_running = 1; 1247 NG_NODE_REF(priv->node); 1248 } 1249 1250 /* Accept packet */ 1251 return (0); 1252 } 1253 1254 /* 1255 * Handle an ack timeout. We have an outstanding ack that we 1256 * were hoping to piggy-back, but haven't, so send a ZLB. 1257 */ 1258 static void 1259 ng_l2tp_seq_xack_timeout(void *arg) 1260 { 1261 const node_p node = arg; 1262 const priv_p priv = NG_NODE_PRIVATE(node); 1263 struct l2tp_seq *const seq = &priv->seq; 1264 int s; 1265 1266 /* Check if node is going away */ 1267 s = splnet(); 1268 if (NG_NODE_NOT_VALID(node)) { 1269 seq->xack_timer_running = 0; 1270 if (!seq->rack_timer_running) { 1271 if (priv->ftarget != NULL) 1272 FREE(priv->ftarget, M_NETGRAPH_L2TP); 1273 FREE(priv, M_NETGRAPH_L2TP); 1274 NG_NODE_SET_PRIVATE(node, NULL); 1275 } 1276 NG_NODE_UNREF(node); 1277 splx(s); 1278 return; 1279 } 1280 1281 /* Sanity check */ 1282 L2TP_SEQ_CHECK(seq); 1283 1284 /* If ack is still outstanding, send a ZLB */ 1285 if (seq->xack != seq->nr) 1286 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns); 1287 1288 /* Done */ 1289 seq->xack_timer_running = 0; 1290 NG_NODE_UNREF(node); 1291 L2TP_SEQ_CHECK(seq); 1292 splx(s); 1293 } 1294 1295 /* 1296 * Handle a transmit timeout. The peer has failed to respond 1297 * with an ack for our packet, so retransmit it. 1298 */ 1299 static void 1300 ng_l2tp_seq_rack_timeout(void *arg) 1301 { 1302 const node_p node = arg; 1303 const priv_p priv = NG_NODE_PRIVATE(node); 1304 struct l2tp_seq *const seq = &priv->seq; 1305 struct mbuf *m; 1306 u_int delay; 1307 int s; 1308 1309 /* Check if node is going away */ 1310 s = splnet(); 1311 if (NG_NODE_NOT_VALID(node)) { 1312 seq->rack_timer_running = 0; 1313 if (!seq->xack_timer_running) { 1314 if (priv->ftarget != NULL) 1315 FREE(priv->ftarget, M_NETGRAPH_L2TP); 1316 FREE(priv, M_NETGRAPH_L2TP); 1317 NG_NODE_SET_PRIVATE(node, NULL); 1318 } 1319 NG_NODE_UNREF(node); 1320 splx(s); 1321 return; 1322 } 1323 1324 /* Sanity check */ 1325 L2TP_SEQ_CHECK(seq); 1326 1327 /* Make sure peer's ack is still outstanding before doing anything */ 1328 if (seq->rack == seq->ns) { 1329 seq->rack_timer_running = 0; 1330 NG_NODE_UNREF(node); 1331 goto done; 1332 } 1333 priv->stats.xmitRetransmits++; 1334 1335 /* Have we reached the retransmit limit? If so, notify owner. */ 1336 if (seq->rexmits++ >= seq->max_rexmits) 1337 ng_l2tp_seq_failure(priv); 1338 1339 /* Restart timer, this time with an increased delay */ 1340 delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits); 1341 if (delay > seq->max_rexmit_to) 1342 delay = seq->max_rexmit_to; 1343 callout_reset(&seq->rack_timer, 1344 hz * delay, ng_l2tp_seq_rack_timeout, node); 1345 1346 /* Do slow-start/congestion algorithm windowing algorithm */ 1347 seq->ssth = (seq->cwnd + 1) / 2; 1348 seq->cwnd = 1; 1349 seq->acks = 0; 1350 1351 /* Retransmit oldest unack'd packet */ 1352 if ((m = L2TP_COPY_MBUF(seq->xwin[0], M_NOWAIT)) == NULL) 1353 priv->stats.memoryFailures++; 1354 else 1355 ng_l2tp_xmit_ctrl(priv, m, seq->rack); 1356 1357 done: 1358 /* Done */ 1359 L2TP_SEQ_CHECK(seq); 1360 splx(s); 1361 } 1362 1363 /* 1364 * Transmit a control stream packet, payload optional. 1365 * The transmit sequence number is not incremented. 1366 */ 1367 static int 1368 ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns) 1369 { 1370 struct l2tp_seq *const seq = &priv->seq; 1371 u_int16_t session_id = 0; 1372 meta_p meta = NULL; 1373 int error; 1374 1375 /* If no mbuf passed, send an empty packet (ZLB) */ 1376 if (m == NULL) { 1377 1378 /* Create a new mbuf for ZLB packet */ 1379 MGETHDR(m, M_DONTWAIT, MT_DATA); 1380 if (m == NULL) { 1381 priv->stats.memoryFailures++; 1382 return (ENOBUFS); 1383 } 1384 m->m_len = m->m_pkthdr.len = 12; 1385 m->m_pkthdr.rcvif = NULL; 1386 priv->stats.xmitZLBs++; 1387 } else { 1388 1389 /* Strip off session ID */ 1390 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) { 1391 priv->stats.memoryFailures++; 1392 return (ENOBUFS); 1393 } 1394 memcpy(&session_id, mtod(m, u_int16_t *), 2); 1395 m_adj(m, 2); 1396 1397 /* Make room for L2TP header */ 1398 M_PREPEND(m, 12, M_DONTWAIT); 1399 if (m == NULL) { 1400 priv->stats.memoryFailures++; 1401 return (ENOBUFS); 1402 } 1403 } 1404 1405 /* Fill in L2TP header */ 1406 mtod(m, u_int16_t *)[0] = htons(L2TP_CTRL_HDR); 1407 mtod(m, u_int16_t *)[1] = htons(m->m_pkthdr.len); 1408 mtod(m, u_int16_t *)[2] = priv->conf.peer_id; 1409 mtod(m, u_int16_t *)[3] = session_id; 1410 mtod(m, u_int16_t *)[4] = htons(ns); 1411 mtod(m, u_int16_t *)[5] = htons(seq->nr); 1412 1413 /* Update sequence number info and stats */ 1414 priv->stats.xmitPackets++; 1415 priv->stats.xmitOctets += m->m_pkthdr.len; 1416 1417 /* Stop ack timer: we're sending an ack with this packet */ 1418 if (seq->xack_timer_running && callout_stop(&seq->xack_timer) == 1) { 1419 seq->xack_timer_running = 0; 1420 NG_NODE_UNREF(priv->node); 1421 } 1422 seq->xack = seq->nr; 1423 1424 /* Send packet */ 1425 NG_SEND_DATA(error, priv->lower, m, meta); 1426 return (error); 1427 } 1428 1429 #ifdef INVARIANTS 1430 /* 1431 * Sanity check sequence number state. 1432 */ 1433 static void 1434 ng_l2tp_seq_check(struct l2tp_seq *seq) 1435 { 1436 const int self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack); 1437 const int peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack); 1438 int i; 1439 1440 #define CHECK(p) KASSERT((p), ("%s: not: %s", __FUNCTION__, #p)) 1441 1442 CHECK(seq->wmax <= L2TP_MAX_XWIN); 1443 CHECK(seq->cwnd >= 1); 1444 CHECK(seq->cwnd <= seq->wmax); 1445 CHECK(seq->ssth >= 1); 1446 CHECK(seq->ssth <= seq->wmax); 1447 if (seq->cwnd < seq->ssth) 1448 CHECK(seq->acks == 0); 1449 else 1450 CHECK(seq->acks <= seq->cwnd); 1451 CHECK(self_unack >= 0); 1452 CHECK(peer_unack >= 0); 1453 CHECK(peer_unack <= seq->wmax); 1454 CHECK((self_unack == 0) ^ seq->xack_timer_running); 1455 CHECK((peer_unack == 0) ^ seq->rack_timer_running); 1456 CHECK(seq->rack_timer_running || !callout_pending(&seq->rack_timer)); 1457 CHECK(seq->xack_timer_running || !callout_pending(&seq->xack_timer)); 1458 for (i = 0; i < peer_unack; i++) 1459 CHECK(seq->xwin[i] != NULL); 1460 for ( ; i < seq->cwnd; i++) /* verify peer's recv window full */ 1461 CHECK(seq->xwin[i] == NULL); 1462 1463 #undef CHECK 1464 } 1465 #endif /* INVARIANTS */ 1466 1467
Cache object: d5353e497ad6506781455b9f78d0e05e
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