2 * Copyright (c) 2001-2002 Packet Design, LLC.
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:
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19 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, PACKET DESIGN MAKES NO
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25 * OF THE USE OF THIS SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY,
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34 * THE USE OF THIS SOFTWARE, EVEN IF PACKET DESIGN IS ADVISED OF
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37 * Author: Archie Cobbs <archie@freebsd.org>
39 * $FreeBSD: src/sys/netgraph/ng_l2tp.c,v 1.25 2008/03/16 21:33:12 mav Exp $
43 * L2TP netgraph node type.
45 * This node type implements the lower layer of the
46 * L2TP protocol as specified in RFC 2661.
49 #include <sys/param.h>
50 #include <sys/systm.h>
51 #include <sys/kernel.h>
55 #include <sys/malloc.h>
56 #include <sys/errno.h>
57 #include <sys/libkern.h>
59 #include <netgraph7/ng_message.h>
60 #include <netgraph7/netgraph.h>
61 #include <netgraph7/ng_parse.h>
64 #ifdef NG_SEPARATE_MALLOC
65 MALLOC_DEFINE(M_NETGRAPH_L2TP
, "netgraph_l2tp", "netgraph l2tp node");
67 #define M_NETGRAPH_L2TP M_NETGRAPH
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 */
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 */
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 */
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 */
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 # */
100 /* Compare sequence numbers using circular math */
101 #define L2TP_SEQ_DIFF(x, y) ((int)((int16_t)(x) - (int16_t)(y)))
103 #define SESSHASHSIZE 0x0020
104 #define SESSHASH(x) (((x) ^ ((x) >> 8)) & (SESSHASHSIZE - 1))
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
;
115 typedef struct ng_l2tp_hook_private
*hookpriv_p
;
118 * Sequence number state
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)
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 */
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
];
160 typedef struct ng_l2tp_private
*priv_p
;
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
;
172 /* Internal functions */
173 static int ng_l2tp_xmit_ctrl(priv_p priv
, struct mbuf
*m
, u_int16_t ns
);
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
);
188 static hookpriv_p
ng_l2tp_find_session(priv_p privp
, u_int16_t sid
);
189 static ng_fn_eachhook ng_l2tp_reset_session
;
192 static void ng_l2tp_seq_check(struct l2tp_seq
*seq
);
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
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
,
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
,
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
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
235 /* List of commands and how to convert arguments to/from ASCII */
236 static const struct ng_cmdlist ng_l2tp_cmdlist
[] = {
241 &ng_l2tp_config_type
,
253 NGM_L2TP_SET_SESS_CONFIG
,
255 &ng_l2tp_sess_config_type
,
260 NGM_L2TP_GET_SESS_CONFIG
,
262 &ng_parse_hint16_type
,
263 &ng_l2tp_sess_config_type
281 NGM_L2TP_GETCLR_STATS
,
288 NGM_L2TP_GET_SESSION_STATS
,
290 &ng_parse_int16_type
,
291 &ng_l2tp_session_stats_type
295 NGM_L2TP_CLR_SESSION_STATS
,
297 &ng_parse_int16_type
,
302 NGM_L2TP_GETCLR_SESSION_STATS
,
304 &ng_parse_int16_type
,
305 &ng_l2tp_session_stats_type
309 NGM_L2TP_ACK_FAILURE
,
318 &ng_l2tp_seq_config_type
,
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
,
336 NETGRAPH_INIT(l2tp
, &ng_l2tp_typestruct
);
338 /* Sequence number state sanity checking */
340 #define L2TP_SEQ_CHECK(seq) ng_l2tp_seq_check(seq)
342 #define L2TP_SEQ_CHECK(x) do { } while (0)
345 /* Whether to use m_copypacket() or m_dup() */
346 #define L2TP_COPY_MBUF m_copypacket
348 #define ERROUT(x) do { error = (x); goto done; } while (0)
350 /************************************************************************
352 ************************************************************************/
355 * Node type constructor
358 ng_l2tp_constructor(node_p node
)
363 /* Allocate private structure */
364 priv
= kmalloc(sizeof(*priv
), M_NETGRAPH_L2TP
,
365 M_WAITOK
| M_NULLOK
| M_ZERO
);
368 NG_NODE_SET_PRIVATE(node
, priv
);
371 /* Apply a semi-reasonable default configuration */
372 priv
->conf
.peer_win
= 1;
373 priv
->conf
.rexmit_max
= L2TP_MAX_REXMIT
;
374 priv
->conf
.rexmit_max_to
= L2TP_MAX_REXMIT_TO
;
376 /* Initialize sequence number state */
377 ng_l2tp_seq_init(priv
);
379 for (i
= 0; i
< SESSHASHSIZE
; i
++)
380 LIST_INIT(&priv
->sesshash
[i
]);
387 * Give our OK for a hook to be added.
390 ng_l2tp_newhook(node_p node
, hook_p hook
, const char *name
)
392 const priv_p priv
= NG_NODE_PRIVATE(node
);
394 /* Check hook name */
395 if (strcmp(name
, NG_L2TP_HOOK_CTRL
) == 0) {
396 if (priv
->ctrl
!= NULL
)
399 NG_HOOK_SET_RCVDATA(hook
, ng_l2tp_rcvdata_ctrl
);
400 } else if (strcmp(name
, NG_L2TP_HOOK_LOWER
) == 0) {
401 if (priv
->lower
!= NULL
)
404 NG_HOOK_SET_RCVDATA(hook
, ng_l2tp_rcvdata_lower
);
406 static const char hexdig
[16] = "0123456789abcdef";
407 u_int16_t session_id
;
414 /* Parse hook name to get session ID */
415 if (strncmp(name
, NG_L2TP_HOOK_SESSION_P
,
416 sizeof(NG_L2TP_HOOK_SESSION_P
) - 1) != 0)
418 hex
= name
+ sizeof(NG_L2TP_HOOK_SESSION_P
) - 1;
419 for (session_id
= i
= 0; i
< 4; i
++) {
420 for (j
= 0; j
< 16 && hex
[i
] != hexdig
[j
]; j
++);
423 session_id
= (session_id
<< 4) | j
;
428 /* Create hook private structure */
429 hpriv
= kmalloc(sizeof(*hpriv
), M_NETGRAPH_L2TP
,
430 M_WAITOK
| M_NULLOK
| M_ZERO
);
433 hpriv
->conf
.session_id
= htons(session_id
);
434 hpriv
->conf
.control_dseq
= L2TP_CONTROL_DSEQ
;
435 hpriv
->conf
.enable_dseq
= L2TP_ENABLE_DSEQ
;
437 NG_HOOK_SET_PRIVATE(hook
, hpriv
);
438 hash
= SESSHASH(hpriv
->conf
.session_id
);
439 LIST_INSERT_HEAD(&priv
->sesshash
[hash
], hpriv
, sessions
);
447 * Receive a control message.
450 ng_l2tp_rcvmsg(node_p node
, item_p item
, hook_p lasthook
)
452 const priv_p priv
= NG_NODE_PRIVATE(node
);
453 struct ng_mesg
*resp
= NULL
;
457 NGI_GET_MSG(item
, msg
);
458 switch (msg
->header
.typecookie
) {
459 case NGM_L2TP_COOKIE
:
460 switch (msg
->header
.cmd
) {
461 case NGM_L2TP_SET_CONFIG
:
463 struct ng_l2tp_config
*const conf
=
464 (struct ng_l2tp_config
*)msg
->data
;
466 /* Check for invalid or illegal config */
467 if (msg
->header
.arglen
!= sizeof(*conf
)) {
471 conf
->enabled
= !!conf
->enabled
;
472 conf
->match_id
= !!conf
->match_id
;
473 conf
->tunnel_id
= htons(conf
->tunnel_id
);
474 conf
->peer_id
= htons(conf
->peer_id
);
475 if (priv
->conf
.enabled
476 && ((priv
->conf
.tunnel_id
!= 0
477 && conf
->tunnel_id
!= priv
->conf
.tunnel_id
)
478 || ((priv
->conf
.peer_id
!= 0
479 && conf
->peer_id
!= priv
->conf
.peer_id
)))) {
484 /* Save calling node as failure target */
485 priv
->ftarget
= NGI_RETADDR(item
);
487 /* Adjust sequence number state */
488 if ((error
= ng_l2tp_seq_adjust(priv
, conf
)) != 0)
491 /* Update node's config */
495 case NGM_L2TP_GET_CONFIG
:
497 struct ng_l2tp_config
*conf
;
499 NG_MKRESPONSE(resp
, msg
, sizeof(*conf
), M_WAITOK
| M_NULLOK
);
504 conf
= (struct ng_l2tp_config
*)resp
->data
;
507 /* Put ID's in host order */
508 conf
->tunnel_id
= ntohs(conf
->tunnel_id
);
509 conf
->peer_id
= ntohs(conf
->peer_id
);
512 case NGM_L2TP_SET_SESS_CONFIG
:
514 struct ng_l2tp_sess_config
*const conf
=
515 (struct ng_l2tp_sess_config
*)msg
->data
;
518 /* Check for invalid or illegal config. */
519 if (msg
->header
.arglen
!= sizeof(*conf
)) {
524 /* Put ID's in network order */
525 conf
->session_id
= htons(conf
->session_id
);
526 conf
->peer_id
= htons(conf
->peer_id
);
528 /* Find matching hook */
529 hpriv
= ng_l2tp_find_session(priv
, conf
->session_id
);
535 /* Update hook's config */
539 case NGM_L2TP_GET_SESS_CONFIG
:
541 struct ng_l2tp_sess_config
*conf
;
542 u_int16_t session_id
;
546 if (msg
->header
.arglen
!= sizeof(session_id
)) {
550 memcpy(&session_id
, msg
->data
, 2);
551 session_id
= htons(session_id
);
553 /* Find matching hook */
554 hpriv
= ng_l2tp_find_session(priv
, session_id
);
561 NG_MKRESPONSE(resp
, msg
, sizeof(hpriv
->conf
), M_WAITOK
| M_NULLOK
);
566 conf
= (struct ng_l2tp_sess_config
*)resp
->data
;
569 /* Put ID's in host order */
570 conf
->session_id
= ntohs(conf
->session_id
);
571 conf
->peer_id
= ntohs(conf
->peer_id
);
574 case NGM_L2TP_GET_STATS
:
575 case NGM_L2TP_CLR_STATS
:
576 case NGM_L2TP_GETCLR_STATS
:
578 if (msg
->header
.cmd
!= NGM_L2TP_CLR_STATS
) {
579 NG_MKRESPONSE(resp
, msg
,
580 sizeof(priv
->stats
), M_WAITOK
| M_NULLOK
);
586 &priv
->stats
, sizeof(priv
->stats
));
588 if (msg
->header
.cmd
!= NGM_L2TP_GET_STATS
)
589 memset(&priv
->stats
, 0, sizeof(priv
->stats
));
592 case NGM_L2TP_GET_SESSION_STATS
:
593 case NGM_L2TP_CLR_SESSION_STATS
:
594 case NGM_L2TP_GETCLR_SESSION_STATS
:
599 /* Get session ID. */
600 if (msg
->header
.arglen
!= sizeof(session_id
)) {
604 bcopy(msg
->data
, &session_id
, sizeof(uint16_t));
605 session_id
= htons(session_id
);
607 /* Find matching hook. */
608 hpriv
= ng_l2tp_find_session(priv
, session_id
);
614 if (msg
->header
.cmd
!= NGM_L2TP_CLR_SESSION_STATS
) {
615 NG_MKRESPONSE(resp
, msg
,
616 sizeof(hpriv
->stats
), M_WAITOK
| M_NULLOK
);
621 bcopy(&hpriv
->stats
, resp
->data
,
622 sizeof(hpriv
->stats
));
624 if (msg
->header
.cmd
!= NGM_L2TP_GET_SESSION_STATS
)
625 bzero(&hpriv
->stats
, sizeof(hpriv
->stats
));
628 case NGM_L2TP_SET_SEQ
:
630 struct ng_l2tp_seq_config
*const conf
=
631 (struct ng_l2tp_seq_config
*)msg
->data
;
633 /* Check for invalid or illegal seq config. */
634 if (msg
->header
.arglen
!= sizeof(*conf
)) {
638 conf
->ns
= htons(conf
->ns
);
639 conf
->nr
= htons(conf
->nr
);
640 conf
->rack
= htons(conf
->rack
);
641 conf
->xack
= htons(conf
->xack
);
643 /* Set sequence numbers. */
644 error
= ng_l2tp_seq_set(priv
, conf
);
658 NG_RESPOND_MSG(error
, node
, item
, resp
);
667 ng_l2tp_shutdown(node_p node
)
669 const priv_p priv
= NG_NODE_PRIVATE(node
);
670 struct l2tp_seq
*const seq
= &priv
->seq
;
675 /* Reset sequence number state */
676 ng_l2tp_seq_reset(priv
);
678 /* Free private data if neither timer is running */
679 ng_uncallout(&seq
->rack_timer
, node
);
680 ng_uncallout(&seq
->xack_timer
, node
);
682 mtx_uninit(&seq
->mtx
);
684 kfree(priv
, M_NETGRAPH_L2TP
);
695 ng_l2tp_disconnect(hook_p hook
)
697 const node_p node
= NG_HOOK_NODE(hook
);
698 const priv_p priv
= NG_NODE_PRIVATE(node
);
700 /* Zero out hook pointer */
701 if (hook
== priv
->ctrl
)
703 else if (hook
== priv
->lower
)
706 const hookpriv_p hpriv
= NG_HOOK_PRIVATE(hook
);
707 LIST_REMOVE(hpriv
, sessions
);
708 kfree(hpriv
, M_NETGRAPH_L2TP
);
709 NG_HOOK_SET_PRIVATE(hook
, NULL
);
712 /* Go away if no longer connected to anything */
713 if (NG_NODE_NUMHOOKS(node
) == 0 && NG_NODE_IS_VALID(node
))
714 ng_rmnode_self(node
);
718 /*************************************************************************
720 *************************************************************************/
723 * Find the hook with a given session ID (in network order).
726 ng_l2tp_find_session(priv_p privp
, u_int16_t sid
)
728 uint16_t hash
= SESSHASH(sid
);
729 hookpriv_p hpriv
= NULL
;
731 LIST_FOREACH(hpriv
, &privp
->sesshash
[hash
], sessions
) {
732 if (hpriv
->conf
.session_id
== sid
)
740 * Reset a hook's session state.
743 ng_l2tp_reset_session(hook_p hook
, void *arg
)
745 const hookpriv_p hpriv
= NG_HOOK_PRIVATE(hook
);
748 hpriv
->conf
.control_dseq
= 0;
749 hpriv
->conf
.enable_dseq
= 0;
750 bzero(&hpriv
->conf
, sizeof(struct ng_l2tp_session_stats
));
758 * Handle an incoming frame from below.
761 ng_l2tp_rcvdata_lower(hook_p h
, item_p item
)
763 static const u_int16_t req_bits
[2][2] = {
764 { L2TP_DATA_0BITS
, L2TP_DATA_1BITS
},
765 { L2TP_CTRL_0BITS
, L2TP_CTRL_1BITS
},
767 const node_p node
= NG_HOOK_NODE(h
);
768 const priv_p priv
= NG_NODE_PRIVATE(node
);
769 hookpriv_p hpriv
= NULL
;
781 L2TP_SEQ_CHECK(&priv
->seq
);
783 /* If not configured, reject */
784 if (!priv
->conf
.enabled
) {
792 /* Remember full packet length; needed for per session accounting. */
793 plen
= m
->m_pkthdr
.len
;
796 priv
->stats
.recvPackets
++;
797 priv
->stats
.recvOctets
+= plen
;
799 /* Get initial header */
800 if (m
->m_pkthdr
.len
< 6) {
801 priv
->stats
.recvRunts
++;
806 if (m
->m_len
< 2 && (m
= m_pullup(m
, 2)) == NULL
) {
807 priv
->stats
.memoryFailures
++;
811 hdr
= ntohs(*mtod(m
, u_int16_t
*));
814 /* Check required header bits and minimum length */
815 is_ctrl
= (hdr
& L2TP_HDR_CTRL
) != 0;
816 if ((hdr
& req_bits
[is_ctrl
][0]) != 0
817 || (~hdr
& req_bits
[is_ctrl
][1]) != 0) {
818 priv
->stats
.recvInvalid
++;
823 if (m
->m_pkthdr
.len
< 4 /* tunnel, session id */
824 + (2 * ((hdr
& L2TP_HDR_LEN
) != 0)) /* length field */
825 + (4 * ((hdr
& L2TP_HDR_SEQ
) != 0)) /* seq # fields */
826 + (2 * ((hdr
& L2TP_HDR_OFF
) != 0))) { /* offset field */
827 priv
->stats
.recvRunts
++;
833 /* Get and validate length field if present */
834 if ((hdr
& L2TP_HDR_LEN
) != 0) {
835 if (m
->m_len
< 2 && (m
= m_pullup(m
, 2)) == NULL
) {
836 priv
->stats
.memoryFailures
++;
840 len
= (u_int16_t
)ntohs(*mtod(m
, u_int16_t
*)) - 4;
842 if (len
< 0 || len
> m
->m_pkthdr
.len
) {
843 priv
->stats
.recvInvalid
++;
848 if (len
< m
->m_pkthdr
.len
) /* trim extra bytes */
849 m_adj(m
, -(m
->m_pkthdr
.len
- len
));
852 /* Get tunnel ID and session ID */
853 if (m
->m_len
< 4 && (m
= m_pullup(m
, 4)) == NULL
) {
854 priv
->stats
.memoryFailures
++;
858 memcpy(ids
, mtod(m
, u_int16_t
*), 4);
861 /* Check tunnel ID */
862 if (ids
[0] != priv
->conf
.tunnel_id
863 && (priv
->conf
.match_id
|| ids
[0] != 0)) {
864 priv
->stats
.recvWrongTunnel
++;
867 ERROUT(EADDRNOTAVAIL
);
870 /* Check session ID (for data packets only) */
871 if ((hdr
& L2TP_HDR_CTRL
) == 0) {
872 hpriv
= ng_l2tp_find_session(priv
, ids
[1]);
874 priv
->stats
.recvUnknownSID
++;
882 /* Get Ns, Nr fields if present */
883 if ((hdr
& L2TP_HDR_SEQ
) != 0) {
884 if (m
->m_len
< 4 && (m
= m_pullup(m
, 4)) == NULL
) {
885 priv
->stats
.memoryFailures
++;
889 memcpy(&ns
, &mtod(m
, u_int16_t
*)[0], 2);
891 memcpy(&nr
, &mtod(m
, u_int16_t
*)[1], 2);
895 nr
= 0; /* avoid gcc complaint */
896 ns
= 0; /* avoid gcc complaint */
899 /* Strip offset padding if present */
900 if ((hdr
& L2TP_HDR_OFF
) != 0) {
903 /* Get length of offset padding */
904 if (m
->m_len
< 2 && (m
= m_pullup(m
, 2)) == NULL
) {
905 priv
->stats
.memoryFailures
++;
909 memcpy(&offset
, mtod(m
, u_int16_t
*), 2);
910 offset
= ntohs(offset
);
912 /* Trim offset padding */
913 if ((2+offset
) > m
->m_pkthdr
.len
) {
914 priv
->stats
.recvInvalid
++;
922 /* Handle control packets */
923 if ((hdr
& L2TP_HDR_CTRL
) != 0) {
924 struct l2tp_seq
*const seq
= &priv
->seq
;
926 /* Handle receive ack sequence number Nr */
927 ng_l2tp_seq_recv_nr(priv
, nr
);
929 /* Discard ZLB packets */
930 if (m
->m_pkthdr
.len
== 0) {
931 priv
->stats
.recvZLBs
++;
939 * If not what we expect or we are busy, drop packet and
940 * send an immediate ZLB ack.
942 if (ns
!= seq
->nr
|| seq
->inproc
) {
943 if (L2TP_SEQ_DIFF(ns
, seq
->nr
) <= 0)
944 priv
->stats
.recvDuplicates
++;
946 priv
->stats
.recvOutOfOrder
++;
947 mtx_unlock(&seq
->mtx
);
948 ng_l2tp_xmit_ctrl(priv
, NULL
, seq
->ns
);
954 * Until we deliver this packet we can't receive next one as
955 * we have no information for sending ack.
958 mtx_unlock(&seq
->mtx
);
960 /* Prepend session ID to packet. */
961 M_PREPEND(m
, 2, M_NOWAIT
);
964 priv
->stats
.memoryFailures
++;
968 memcpy(mtod(m
, u_int16_t
*), &ids
[1], 2);
970 /* Deliver packet to upper layers */
971 NG_FWD_NEW_DATA(error
, item
, priv
->ctrl
, m
);
974 /* Ready to process next packet. */
977 /* If packet was successfully delivered send ack. */
979 /* Update recv sequence number */
981 /* Start receive ack timer, if not already running */
982 if (!callout_active(&seq
->xack_timer
)) {
983 ng_callout(&seq
->xack_timer
, priv
->node
, NULL
,
984 L2TP_DELAYED_ACK
, ng_l2tp_seq_xack_timeout
,
988 mtx_unlock(&seq
->mtx
);
993 /* Per session packet, account it. */
994 hpriv
->stats
.recvPackets
++;
995 hpriv
->stats
.recvOctets
+= plen
;
997 /* Follow peer's lead in data sequencing, if configured to do so */
998 if (!hpriv
->conf
.control_dseq
)
999 hpriv
->conf
.enable_dseq
= ((hdr
& L2TP_HDR_SEQ
) != 0);
1001 /* Handle data sequence numbers if present and enabled */
1002 if ((hdr
& L2TP_HDR_SEQ
) != 0) {
1003 if (hpriv
->conf
.enable_dseq
1004 && L2TP_SEQ_DIFF(ns
, hpriv
->nr
) < 0) {
1005 NG_FREE_ITEM(item
); /* duplicate or out of order */
1007 priv
->stats
.recvDataDrops
++;
1013 /* Drop empty data packets */
1014 if (m
->m_pkthdr
.len
== 0) {
1021 NG_FWD_NEW_DATA(error
, item
, hook
, m
);
1024 L2TP_SEQ_CHECK(&priv
->seq
);
1029 * Handle an outgoing control frame.
1032 ng_l2tp_rcvdata_ctrl(hook_p hook
, item_p item
)
1034 const node_p node
= NG_HOOK_NODE(hook
);
1035 const priv_p priv
= NG_NODE_PRIVATE(node
);
1036 struct l2tp_seq
*const seq
= &priv
->seq
;
1043 L2TP_SEQ_CHECK(&priv
->seq
);
1045 /* If not configured, reject */
1046 if (!priv
->conf
.enabled
) {
1051 /* Grab mbuf and discard other stuff XXX */
1055 /* Packet should have session ID prepended */
1056 if (m
->m_pkthdr
.len
< 2) {
1057 priv
->stats
.xmitInvalid
++;
1062 /* Check max length */
1063 if (m
->m_pkthdr
.len
>= 0x10000 - 14) {
1064 priv
->stats
.xmitTooBig
++;
1069 mtx_lock(&seq
->mtx
);
1071 /* Find next empty slot in transmit queue */
1072 for (i
= 0; i
< L2TP_MAX_XWIN
&& seq
->xwin
[i
] != NULL
; i
++);
1073 if (i
== L2TP_MAX_XWIN
) {
1074 mtx_unlock(&seq
->mtx
);
1075 priv
->stats
.xmitDrops
++;
1081 /* If peer's receive window is already full, nothing else to do */
1082 if (i
>= seq
->cwnd
) {
1083 mtx_unlock(&seq
->mtx
);
1087 /* Start retransmit timer if not already running */
1088 if (!callout_active(&seq
->rack_timer
))
1089 ng_callout(&seq
->rack_timer
, node
, NULL
,
1090 hz
, ng_l2tp_seq_rack_timeout
, NULL
, 0);
1094 mtx_unlock(&seq
->mtx
);
1097 if ((m
= L2TP_COPY_MBUF(m
, M_NOWAIT
)) == NULL
) {
1098 priv
->stats
.memoryFailures
++;
1102 /* Send packet and increment xmit sequence number */
1103 error
= ng_l2tp_xmit_ctrl(priv
, m
, ns
);
1106 L2TP_SEQ_CHECK(&priv
->seq
);
1111 * Handle an outgoing data frame.
1114 ng_l2tp_rcvdata(hook_p hook
, item_p item
)
1116 const priv_p priv
= NG_NODE_PRIVATE(NG_HOOK_NODE(hook
));
1117 const hookpriv_p hpriv
= NG_HOOK_PRIVATE(hook
);
1124 L2TP_SEQ_CHECK(&priv
->seq
);
1126 /* If not configured, reject */
1127 if (!priv
->conf
.enabled
) {
1135 /* Check max length */
1136 if (m
->m_pkthdr
.len
>= 0x10000 - 12) {
1137 priv
->stats
.xmitDataTooBig
++;
1143 /* Prepend L2TP header */
1145 + (2 * (hpriv
->conf
.include_length
!= 0))
1146 + (4 * (hpriv
->conf
.enable_dseq
!= 0)),
1149 priv
->stats
.memoryFailures
++;
1153 hdr
= L2TP_DATA_HDR
;
1154 if (hpriv
->conf
.include_length
) {
1155 hdr
|= L2TP_HDR_LEN
;
1156 mtod(m
, u_int16_t
*)[i
++] = htons(m
->m_pkthdr
.len
);
1158 mtod(m
, u_int16_t
*)[i
++] = priv
->conf
.peer_id
;
1159 mtod(m
, u_int16_t
*)[i
++] = hpriv
->conf
.peer_id
;
1160 if (hpriv
->conf
.enable_dseq
) {
1161 hdr
|= L2TP_HDR_SEQ
;
1162 mtod(m
, u_int16_t
*)[i
++] = htons(hpriv
->ns
);
1163 mtod(m
, u_int16_t
*)[i
++] = htons(hpriv
->nr
);
1166 mtod(m
, u_int16_t
*)[0] = htons(hdr
);
1168 /* Update per session stats. */
1169 hpriv
->stats
.xmitPackets
++;
1170 hpriv
->stats
.xmitOctets
+= m
->m_pkthdr
.len
;
1172 /* And the global one. */
1173 priv
->stats
.xmitPackets
++;
1174 priv
->stats
.xmitOctets
+= m
->m_pkthdr
.len
;
1177 NG_FWD_NEW_DATA(error
, item
, priv
->lower
, m
);
1180 L2TP_SEQ_CHECK(&priv
->seq
);
1185 * Send a message to our controlling node that we've failed.
1188 ng_l2tp_seq_failure(priv_p priv
)
1190 struct ng_mesg
*msg
;
1193 NG_MKMESSAGE(msg
, NGM_L2TP_COOKIE
, NGM_L2TP_ACK_FAILURE
, 0, M_WAITOK
| M_NULLOK
);
1196 NG_SEND_MSG_ID(error
, priv
->node
, msg
, priv
->ftarget
, 0);
1199 /************************************************************************
1200 SEQUENCE NUMBER HANDLING
1201 ************************************************************************/
1204 * Initialize sequence number state.
1207 ng_l2tp_seq_init(priv_p priv
)
1209 struct l2tp_seq
*const seq
= &priv
->seq
;
1211 KASSERT(priv
->conf
.peer_win
>= 1,
1212 ("%s: peer_win is zero", __func__
));
1213 memset(seq
, 0, sizeof(*seq
));
1215 seq
->wmax
= priv
->conf
.peer_win
;
1216 if (seq
->wmax
> L2TP_MAX_XWIN
)
1217 seq
->wmax
= L2TP_MAX_XWIN
;
1218 seq
->ssth
= seq
->wmax
;
1219 ng_callout_init(&seq
->rack_timer
);
1220 ng_callout_init(&seq
->xack_timer
);
1221 mtx_init(&seq
->mtx
, "ng_l2tp");
1222 L2TP_SEQ_CHECK(seq
);
1226 * Set sequence number state as given from user.
1229 ng_l2tp_seq_set(priv_p priv
, const struct ng_l2tp_seq_config
*conf
)
1231 struct l2tp_seq
*const seq
= &priv
->seq
;
1233 /* If node is enabled, deny update to sequence numbers. */
1234 if (priv
->conf
.enabled
)
1237 /* We only can handle the simple cases. */
1238 if (conf
->xack
!= conf
->nr
|| conf
->ns
!= conf
->rack
)
1241 /* Set ns,nr,rack,xack parameters. */
1244 seq
->rack
= conf
->rack
;
1245 seq
->xack
= conf
->xack
;
1251 * Adjust sequence number state accordingly after reconfiguration.
1254 ng_l2tp_seq_adjust(priv_p priv
, const struct ng_l2tp_config
*conf
)
1256 struct l2tp_seq
*const seq
= &priv
->seq
;
1259 /* If disabling node, reset state sequence number */
1260 if (!conf
->enabled
) {
1261 ng_l2tp_seq_reset(priv
);
1265 /* Adjust peer's max recv window; it can only increase */
1266 new_wmax
= conf
->peer_win
;
1267 if (new_wmax
> L2TP_MAX_XWIN
)
1268 new_wmax
= L2TP_MAX_XWIN
;
1271 if (new_wmax
< seq
->wmax
)
1273 seq
->wmax
= new_wmax
;
1280 * Reset sequence number state.
1283 ng_l2tp_seq_reset(priv_p priv
)
1285 struct l2tp_seq
*const seq
= &priv
->seq
;
1290 L2TP_SEQ_CHECK(seq
);
1293 ng_uncallout(&seq
->rack_timer
, priv
->node
);
1294 ng_uncallout(&seq
->xack_timer
, priv
->node
);
1296 /* Free retransmit queue */
1297 for (i
= 0; i
< L2TP_MAX_XWIN
; i
++) {
1298 if (seq
->xwin
[i
] == NULL
)
1300 m_freem(seq
->xwin
[i
]);
1303 /* Reset session hooks' sequence number states */
1304 NG_NODE_FOREACH_HOOK(priv
->node
, ng_l2tp_reset_session
, NULL
, hook
);
1306 /* Reset node's sequence number state */
1311 seq
->wmax
= L2TP_MAX_XWIN
;
1313 seq
->ssth
= seq
->wmax
;
1316 bzero(seq
->xwin
, sizeof(seq
->xwin
));
1319 L2TP_SEQ_CHECK(seq
);
1323 * Handle receipt of an acknowledgement value (Nr) from peer.
1326 ng_l2tp_seq_recv_nr(priv_p priv
, u_int16_t nr
)
1328 struct l2tp_seq
*const seq
= &priv
->seq
;
1329 struct mbuf
*xwin
[L2TP_MAX_XWIN
]; /* partial local copy */
1334 mtx_lock(&seq
->mtx
);
1336 /* Verify peer's ACK is in range */
1337 if ((nack
= L2TP_SEQ_DIFF(nr
, seq
->rack
)) <= 0) {
1338 mtx_unlock(&seq
->mtx
);
1339 return; /* duplicate ack */
1341 if (L2TP_SEQ_DIFF(nr
, seq
->ns
) > 0) {
1342 mtx_unlock(&seq
->mtx
);
1343 priv
->stats
.recvBadAcks
++; /* ack for packet not sent */
1346 KASSERT(nack
<= L2TP_MAX_XWIN
,
1347 ("%s: nack=%d > %d", __func__
, nack
, L2TP_MAX_XWIN
));
1349 /* Update receive ack stats */
1353 /* Free acknowledged packets and shift up packets in the xmit queue */
1354 for (i
= 0; i
< nack
; i
++)
1355 m_freem(seq
->xwin
[i
]);
1356 memmove(seq
->xwin
, seq
->xwin
+ nack
,
1357 (L2TP_MAX_XWIN
- nack
) * sizeof(*seq
->xwin
));
1358 memset(seq
->xwin
+ (L2TP_MAX_XWIN
- nack
), 0,
1359 nack
* sizeof(*seq
->xwin
));
1362 * Do slow-start/congestion avoidance windowing algorithm described
1363 * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
1364 * ACK had arrived separately.
1366 if (seq
->cwnd
< seq
->wmax
) {
1368 /* Handle slow start phase */
1369 if (seq
->cwnd
< seq
->ssth
) {
1372 if (seq
->cwnd
> seq
->ssth
) { /* into cg.av. phase */
1373 nack
= seq
->cwnd
- seq
->ssth
;
1374 seq
->cwnd
= seq
->ssth
;
1378 /* Handle congestion avoidance phase */
1379 if (seq
->cwnd
>= seq
->ssth
) {
1381 while (seq
->acks
>= seq
->cwnd
) {
1382 seq
->acks
-= seq
->cwnd
;
1383 if (seq
->cwnd
< seq
->wmax
)
1389 /* Stop xmit timer */
1390 if (callout_active(&seq
->rack_timer
))
1391 ng_uncallout(&seq
->rack_timer
, priv
->node
);
1393 /* If transmit queue is empty, we're done for now */
1394 if (seq
->xwin
[0] == NULL
) {
1395 mtx_unlock(&seq
->mtx
);
1399 /* Start restransmit timer again */
1400 ng_callout(&seq
->rack_timer
, priv
->node
, NULL
,
1401 hz
, ng_l2tp_seq_rack_timeout
, NULL
, 0);
1404 * Send more packets, trying to keep peer's receive window full.
1405 * Make copy of everything we need before lock release.
1409 while ((i
= L2TP_SEQ_DIFF(seq
->ns
, seq
->rack
)) < seq
->cwnd
1410 && seq
->xwin
[i
] != NULL
) {
1411 xwin
[j
++] = seq
->xwin
[i
];
1415 mtx_unlock(&seq
->mtx
);
1419 * If there is a memory error, pretend packet was sent, as it
1420 * will get retransmitted later anyway.
1422 for (i
= 0; i
< j
; i
++) {
1424 if ((m
= L2TP_COPY_MBUF(xwin
[i
], M_NOWAIT
)) == NULL
)
1425 priv
->stats
.memoryFailures
++;
1427 ng_l2tp_xmit_ctrl(priv
, m
, ns
);
1433 * Handle an ack timeout. We have an outstanding ack that we
1434 * were hoping to piggy-back, but haven't, so send a ZLB.
1437 ng_l2tp_seq_xack_timeout(node_p node
, hook_p hook
, void *arg1
, int arg2
)
1439 const priv_p priv
= NG_NODE_PRIVATE(node
);
1440 struct l2tp_seq
*const seq
= &priv
->seq
;
1442 /* Make sure callout is still active before doing anything */
1443 if (callout_pending(&seq
->xack_timer
) ||
1444 (!callout_active(&seq
->xack_timer
)))
1448 L2TP_SEQ_CHECK(seq
);
1451 ng_l2tp_xmit_ctrl(priv
, NULL
, seq
->ns
);
1453 /* callout_deactivate() is not needed here
1454 as ng_uncallout() was called by ng_l2tp_xmit_ctrl() */
1457 L2TP_SEQ_CHECK(seq
);
1461 * Handle a transmit timeout. The peer has failed to respond
1462 * with an ack for our packet, so retransmit it.
1465 ng_l2tp_seq_rack_timeout(node_p node
, hook_p hook
, void *arg1
, int arg2
)
1467 const priv_p priv
= NG_NODE_PRIVATE(node
);
1468 struct l2tp_seq
*const seq
= &priv
->seq
;
1472 /* Make sure callout is still active before doing anything */
1473 if (callout_pending(&seq
->rack_timer
) ||
1474 (!callout_active(&seq
->rack_timer
)))
1478 L2TP_SEQ_CHECK(seq
);
1480 priv
->stats
.xmitRetransmits
++;
1482 /* Have we reached the retransmit limit? If so, notify owner. */
1483 if (seq
->rexmits
++ >= priv
->conf
.rexmit_max
)
1484 ng_l2tp_seq_failure(priv
);
1486 /* Restart timer, this time with an increased delay */
1487 delay
= (seq
->rexmits
> 12) ? (1 << 12) : (1 << seq
->rexmits
);
1488 if (delay
> priv
->conf
.rexmit_max_to
)
1489 delay
= priv
->conf
.rexmit_max_to
;
1490 ng_callout(&seq
->rack_timer
, node
, NULL
,
1491 hz
* delay
, ng_l2tp_seq_rack_timeout
, NULL
, 0);
1493 /* Do slow-start/congestion algorithm windowing algorithm */
1494 seq
->ns
= seq
->rack
;
1495 seq
->ssth
= (seq
->cwnd
+ 1) / 2;
1499 /* Retransmit oldest unack'd packet */
1500 if ((m
= L2TP_COPY_MBUF(seq
->xwin
[0], M_NOWAIT
)) == NULL
)
1501 priv
->stats
.memoryFailures
++;
1503 ng_l2tp_xmit_ctrl(priv
, m
, seq
->ns
++);
1505 /* callout_deactivate() is not needed here
1506 as ng_callout() is getting called each time */
1509 L2TP_SEQ_CHECK(seq
);
1513 * Transmit a control stream packet, payload optional.
1514 * The transmit sequence number is not incremented.
1517 ng_l2tp_xmit_ctrl(priv_p priv
, struct mbuf
*m
, u_int16_t ns
)
1519 struct l2tp_seq
*const seq
= &priv
->seq
;
1520 u_int16_t session_id
= 0;
1523 mtx_lock(&seq
->mtx
);
1525 /* Stop ack timer: we're sending an ack with this packet.
1526 Doing this before to keep state predictable after error. */
1527 if (callout_active(&seq
->xack_timer
))
1528 ng_uncallout(&seq
->xack_timer
, priv
->node
);
1530 seq
->xack
= seq
->nr
;
1532 mtx_unlock(&seq
->mtx
);
1534 /* If no mbuf passed, send an empty packet (ZLB) */
1537 /* Create a new mbuf for ZLB packet */
1538 MGETHDR(m
, M_NOWAIT
, MT_DATA
);
1540 priv
->stats
.memoryFailures
++;
1543 m
->m_len
= m
->m_pkthdr
.len
= 12;
1544 m
->m_pkthdr
.rcvif
= NULL
;
1545 priv
->stats
.xmitZLBs
++;
1548 /* Strip off session ID */
1549 if (m
->m_len
< 2 && (m
= m_pullup(m
, 2)) == NULL
) {
1550 priv
->stats
.memoryFailures
++;
1553 memcpy(&session_id
, mtod(m
, u_int16_t
*), 2);
1556 /* Make room for L2TP header */
1557 M_PREPEND(m
, 12, M_NOWAIT
);
1559 priv
->stats
.memoryFailures
++;
1564 /* Fill in L2TP header */
1565 mtod(m
, u_int16_t
*)[0] = htons(L2TP_CTRL_HDR
);
1566 mtod(m
, u_int16_t
*)[1] = htons(m
->m_pkthdr
.len
);
1567 mtod(m
, u_int16_t
*)[2] = priv
->conf
.peer_id
;
1568 mtod(m
, u_int16_t
*)[3] = session_id
;
1569 mtod(m
, u_int16_t
*)[4] = htons(ns
);
1570 mtod(m
, u_int16_t
*)[5] = htons(seq
->nr
);
1572 /* Update sequence number info and stats */
1573 priv
->stats
.xmitPackets
++;
1574 priv
->stats
.xmitOctets
+= m
->m_pkthdr
.len
;
1577 NG_SEND_DATA_ONLY(error
, priv
->lower
, m
);
1583 * Sanity check sequence number state.
1586 ng_l2tp_seq_check(struct l2tp_seq
*seq
)
1588 int self_unack
, peer_unack
;
1591 #define CHECK(p) KASSERT((p), ("%s: not: %s", __func__, #p))
1593 mtx_lock(&seq
->mtx
);
1595 self_unack
= L2TP_SEQ_DIFF(seq
->nr
, seq
->xack
);
1596 peer_unack
= L2TP_SEQ_DIFF(seq
->ns
, seq
->rack
);
1597 CHECK(seq
->wmax
<= L2TP_MAX_XWIN
);
1598 CHECK(seq
->cwnd
>= 1);
1599 CHECK(seq
->cwnd
<= seq
->wmax
);
1600 CHECK(seq
->ssth
>= 1);
1601 CHECK(seq
->ssth
<= seq
->wmax
);
1602 if (seq
->cwnd
< seq
->ssth
)
1603 CHECK(seq
->acks
== 0);
1605 CHECK(seq
->acks
<= seq
->cwnd
);
1606 CHECK(self_unack
>= 0);
1607 CHECK(peer_unack
>= 0);
1608 CHECK(peer_unack
<= seq
->wmax
);
1609 CHECK((self_unack
== 0) ^ callout_active(&seq
->xack_timer
));
1610 CHECK((peer_unack
== 0) ^ callout_active(&seq
->rack_timer
));
1611 for (i
= 0; i
< peer_unack
; i
++)
1612 CHECK(seq
->xwin
[i
] != NULL
);
1613 for ( ; i
< seq
->cwnd
; i
++) /* verify peer's recv window full */
1614 CHECK(seq
->xwin
[i
] == NULL
);
1616 mtx_unlock(&seq
->mtx
);
1620 #endif /* INVARIANTS */