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37 * Author: Archie Cobbs <archie@freebsd.org>
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 <netgraph/ng_message.h>
60 #include <netgraph/netgraph.h>
61 #include <netgraph/ng_parse.h>
62 #include <netgraph/ng_l2tp.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)
346 #define memmove(d, s, l) bcopy(s, d, l)
348 /* Whether to use m_copypacket() or m_dup() */
349 #define L2TP_COPY_MBUF m_copypacket
351 #define ERROUT(x) do { error = (x); goto done; } while (0)
353 /************************************************************************
355 ************************************************************************/
358 * Node type constructor
361 ng_l2tp_constructor(node_p node)
366 /* Allocate private structure */
367 MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
370 NG_NODE_SET_PRIVATE(node, priv);
373 /* Apply a semi-reasonable default configuration */
374 priv->conf.peer_win = 1;
375 priv->conf.rexmit_max = L2TP_MAX_REXMIT;
376 priv->conf.rexmit_max_to = L2TP_MAX_REXMIT_TO;
378 /* Initialize sequence number state */
379 ng_l2tp_seq_init(priv);
381 for (i = 0; i < SESSHASHSIZE; i++)
382 LIST_INIT(&priv->sesshash[i]);
389 * Give our OK for a hook to be added.
392 ng_l2tp_newhook(node_p node, hook_p hook, const char *name)
394 const priv_p priv = NG_NODE_PRIVATE(node);
396 /* Check hook name */
397 if (strcmp(name, NG_L2TP_HOOK_CTRL) == 0) {
398 if (priv->ctrl != NULL)
401 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_ctrl);
402 } else if (strcmp(name, NG_L2TP_HOOK_LOWER) == 0) {
403 if (priv->lower != NULL)
406 NG_HOOK_SET_RCVDATA(hook, ng_l2tp_rcvdata_lower);
408 static const char hexdig[16] = "0123456789abcdef";
409 u_int16_t session_id;
416 /* Parse hook name to get session ID */
417 if (strncmp(name, NG_L2TP_HOOK_SESSION_P,
418 sizeof(NG_L2TP_HOOK_SESSION_P) - 1) != 0)
420 hex = name + sizeof(NG_L2TP_HOOK_SESSION_P) - 1;
421 for (session_id = i = 0; i < 4; i++) {
422 for (j = 0; j < 16 && hex[i] != hexdig[j]; j++);
425 session_id = (session_id << 4) | j;
430 /* Create hook private structure */
431 MALLOC(hpriv, hookpriv_p,
432 sizeof(*hpriv), M_NETGRAPH_L2TP, M_NOWAIT | M_ZERO);
435 hpriv->conf.session_id = htons(session_id);
436 hpriv->conf.control_dseq = L2TP_CONTROL_DSEQ;
437 hpriv->conf.enable_dseq = L2TP_ENABLE_DSEQ;
439 NG_HOOK_SET_PRIVATE(hook, hpriv);
440 hash = SESSHASH(hpriv->conf.session_id);
441 LIST_INSERT_HEAD(&priv->sesshash[hash], hpriv, sessions);
449 * Receive a control message.
452 ng_l2tp_rcvmsg(node_p node, item_p item, hook_p lasthook)
454 const priv_p priv = NG_NODE_PRIVATE(node);
455 struct ng_mesg *resp = NULL;
459 NGI_GET_MSG(item, msg);
460 switch (msg->header.typecookie) {
461 case NGM_L2TP_COOKIE:
462 switch (msg->header.cmd) {
463 case NGM_L2TP_SET_CONFIG:
465 struct ng_l2tp_config *const conf =
466 (struct ng_l2tp_config *)msg->data;
468 /* Check for invalid or illegal config */
469 if (msg->header.arglen != sizeof(*conf)) {
473 conf->enabled = !!conf->enabled;
474 conf->match_id = !!conf->match_id;
475 conf->tunnel_id = htons(conf->tunnel_id);
476 conf->peer_id = htons(conf->peer_id);
477 if (priv->conf.enabled
478 && ((priv->conf.tunnel_id != 0
479 && conf->tunnel_id != priv->conf.tunnel_id)
480 || ((priv->conf.peer_id != 0
481 && conf->peer_id != priv->conf.peer_id)))) {
486 /* Save calling node as failure target */
487 priv->ftarget = NGI_RETADDR(item);
489 /* Adjust sequence number state */
490 if ((error = ng_l2tp_seq_adjust(priv, conf)) != 0)
493 /* Update node's config */
497 case NGM_L2TP_GET_CONFIG:
499 struct ng_l2tp_config *conf;
501 NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT);
506 conf = (struct ng_l2tp_config *)resp->data;
509 /* Put ID's in host order */
510 conf->tunnel_id = ntohs(conf->tunnel_id);
511 conf->peer_id = ntohs(conf->peer_id);
514 case NGM_L2TP_SET_SESS_CONFIG:
516 struct ng_l2tp_sess_config *const conf =
517 (struct ng_l2tp_sess_config *)msg->data;
520 /* Check for invalid or illegal config. */
521 if (msg->header.arglen != sizeof(*conf)) {
526 /* Put ID's in network order */
527 conf->session_id = htons(conf->session_id);
528 conf->peer_id = htons(conf->peer_id);
530 /* Find matching hook */
531 hpriv = ng_l2tp_find_session(priv, conf->session_id);
537 /* Update hook's config */
541 case NGM_L2TP_GET_SESS_CONFIG:
543 struct ng_l2tp_sess_config *conf;
544 u_int16_t session_id;
548 if (msg->header.arglen != sizeof(session_id)) {
552 memcpy(&session_id, msg->data, 2);
553 session_id = htons(session_id);
555 /* Find matching hook */
556 hpriv = ng_l2tp_find_session(priv, session_id);
563 NG_MKRESPONSE(resp, msg, sizeof(hpriv->conf), M_NOWAIT);
568 conf = (struct ng_l2tp_sess_config *)resp->data;
571 /* Put ID's in host order */
572 conf->session_id = ntohs(conf->session_id);
573 conf->peer_id = ntohs(conf->peer_id);
576 case NGM_L2TP_GET_STATS:
577 case NGM_L2TP_CLR_STATS:
578 case NGM_L2TP_GETCLR_STATS:
580 if (msg->header.cmd != NGM_L2TP_CLR_STATS) {
581 NG_MKRESPONSE(resp, msg,
582 sizeof(priv->stats), M_NOWAIT);
588 &priv->stats, sizeof(priv->stats));
590 if (msg->header.cmd != NGM_L2TP_GET_STATS)
591 memset(&priv->stats, 0, sizeof(priv->stats));
594 case NGM_L2TP_GET_SESSION_STATS:
595 case NGM_L2TP_CLR_SESSION_STATS:
596 case NGM_L2TP_GETCLR_SESSION_STATS:
601 /* Get session ID. */
602 if (msg->header.arglen != sizeof(session_id)) {
606 bcopy(msg->data, &session_id, sizeof(uint16_t));
607 session_id = htons(session_id);
609 /* Find matching hook. */
610 hpriv = ng_l2tp_find_session(priv, session_id);
616 if (msg->header.cmd != NGM_L2TP_CLR_SESSION_STATS) {
617 NG_MKRESPONSE(resp, msg,
618 sizeof(hpriv->stats), M_NOWAIT);
623 bcopy(&hpriv->stats, resp->data,
624 sizeof(hpriv->stats));
626 if (msg->header.cmd != NGM_L2TP_GET_SESSION_STATS)
627 bzero(&hpriv->stats, sizeof(hpriv->stats));
630 case NGM_L2TP_SET_SEQ:
632 struct ng_l2tp_seq_config *const conf =
633 (struct ng_l2tp_seq_config *)msg->data;
635 /* Check for invalid or illegal seq config. */
636 if (msg->header.arglen != sizeof(*conf)) {
640 conf->ns = htons(conf->ns);
641 conf->nr = htons(conf->nr);
642 conf->rack = htons(conf->rack);
643 conf->xack = htons(conf->xack);
645 /* Set sequence numbers. */
646 error = ng_l2tp_seq_set(priv, conf);
660 NG_RESPOND_MSG(error, node, item, resp);
669 ng_l2tp_shutdown(node_p node)
671 const priv_p priv = NG_NODE_PRIVATE(node);
672 struct l2tp_seq *const seq = &priv->seq;
677 /* Reset sequence number state */
678 ng_l2tp_seq_reset(priv);
680 /* Free private data if neither timer is running */
681 ng_uncallout(&seq->rack_timer, node);
682 ng_uncallout(&seq->xack_timer, node);
684 mtx_destroy(&seq->mtx);
686 FREE(priv, M_NETGRAPH_L2TP);
697 ng_l2tp_disconnect(hook_p hook)
699 const node_p node = NG_HOOK_NODE(hook);
700 const priv_p priv = NG_NODE_PRIVATE(node);
702 /* Zero out hook pointer */
703 if (hook == priv->ctrl)
705 else if (hook == priv->lower)
708 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
709 LIST_REMOVE(hpriv, sessions);
710 FREE(hpriv, M_NETGRAPH_L2TP);
711 NG_HOOK_SET_PRIVATE(hook, NULL);
714 /* Go away if no longer connected to anything */
715 if (NG_NODE_NUMHOOKS(node) == 0 && NG_NODE_IS_VALID(node))
716 ng_rmnode_self(node);
720 /*************************************************************************
722 *************************************************************************/
725 * Find the hook with a given session ID (in network order).
728 ng_l2tp_find_session(priv_p privp, u_int16_t sid)
730 uint16_t hash = SESSHASH(sid);
731 hookpriv_p hpriv = NULL;
733 LIST_FOREACH(hpriv, &privp->sesshash[hash], sessions) {
734 if (hpriv->conf.session_id == sid)
742 * Reset a hook's session state.
745 ng_l2tp_reset_session(hook_p hook, void *arg)
747 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
750 hpriv->conf.control_dseq = 0;
751 hpriv->conf.enable_dseq = 0;
752 bzero(&hpriv->conf, sizeof(struct ng_l2tp_session_stats));
760 * Handle an incoming frame from below.
763 ng_l2tp_rcvdata_lower(hook_p h, item_p item)
765 static const u_int16_t req_bits[2][2] = {
766 { L2TP_DATA_0BITS, L2TP_DATA_1BITS },
767 { L2TP_CTRL_0BITS, L2TP_CTRL_1BITS },
769 const node_p node = NG_HOOK_NODE(h);
770 const priv_p priv = NG_NODE_PRIVATE(node);
771 hookpriv_p hpriv = NULL;
783 L2TP_SEQ_CHECK(&priv->seq);
785 /* If not configured, reject */
786 if (!priv->conf.enabled) {
794 /* Remember full packet length; needed for per session accounting. */
795 plen = m->m_pkthdr.len;
798 priv->stats.recvPackets++;
799 priv->stats.recvOctets += plen;
801 /* Get initial header */
802 if (m->m_pkthdr.len < 6) {
803 priv->stats.recvRunts++;
808 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
809 priv->stats.memoryFailures++;
813 hdr = ntohs(*mtod(m, u_int16_t *));
816 /* Check required header bits and minimum length */
817 is_ctrl = (hdr & L2TP_HDR_CTRL) != 0;
818 if ((hdr & req_bits[is_ctrl][0]) != 0
819 || (~hdr & req_bits[is_ctrl][1]) != 0) {
820 priv->stats.recvInvalid++;
825 if (m->m_pkthdr.len < 4 /* tunnel, session id */
826 + (2 * ((hdr & L2TP_HDR_LEN) != 0)) /* length field */
827 + (4 * ((hdr & L2TP_HDR_SEQ) != 0)) /* seq # fields */
828 + (2 * ((hdr & L2TP_HDR_OFF) != 0))) { /* offset field */
829 priv->stats.recvRunts++;
835 /* Get and validate length field if present */
836 if ((hdr & L2TP_HDR_LEN) != 0) {
837 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
838 priv->stats.memoryFailures++;
842 len = (u_int16_t)ntohs(*mtod(m, u_int16_t *)) - 4;
844 if (len < 0 || len > m->m_pkthdr.len) {
845 priv->stats.recvInvalid++;
850 if (len < m->m_pkthdr.len) /* trim extra bytes */
851 m_adj(m, -(m->m_pkthdr.len - len));
854 /* Get tunnel ID and session ID */
855 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
856 priv->stats.memoryFailures++;
860 memcpy(ids, mtod(m, u_int16_t *), 4);
863 /* Check tunnel ID */
864 if (ids[0] != priv->conf.tunnel_id
865 && (priv->conf.match_id || ids[0] != 0)) {
866 priv->stats.recvWrongTunnel++;
869 ERROUT(EADDRNOTAVAIL);
872 /* Check session ID (for data packets only) */
873 if ((hdr & L2TP_HDR_CTRL) == 0) {
874 hpriv = ng_l2tp_find_session(priv, ids[1]);
876 priv->stats.recvUnknownSID++;
884 /* Get Ns, Nr fields if present */
885 if ((hdr & L2TP_HDR_SEQ) != 0) {
886 if (m->m_len < 4 && (m = m_pullup(m, 4)) == NULL) {
887 priv->stats.memoryFailures++;
891 memcpy(&ns, &mtod(m, u_int16_t *)[0], 2);
893 memcpy(&nr, &mtod(m, u_int16_t *)[1], 2);
898 /* Strip offset padding if present */
899 if ((hdr & L2TP_HDR_OFF) != 0) {
902 /* Get length of offset padding */
903 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
904 priv->stats.memoryFailures++;
908 memcpy(&offset, mtod(m, u_int16_t *), 2);
909 offset = ntohs(offset);
911 /* Trim offset padding */
912 if ((2+offset) > m->m_pkthdr.len) {
913 priv->stats.recvInvalid++;
921 /* Handle control packets */
922 if ((hdr & L2TP_HDR_CTRL) != 0) {
923 struct l2tp_seq *const seq = &priv->seq;
925 /* Handle receive ack sequence number Nr */
926 ng_l2tp_seq_recv_nr(priv, nr);
928 /* Discard ZLB packets */
929 if (m->m_pkthdr.len == 0) {
930 priv->stats.recvZLBs++;
938 * If not what we expect or we are busy, drop packet and
939 * send an immediate ZLB ack.
941 if (ns != seq->nr || seq->inproc) {
942 if (L2TP_SEQ_DIFF(ns, seq->nr) <= 0)
943 priv->stats.recvDuplicates++;
945 priv->stats.recvOutOfOrder++;
946 mtx_unlock(&seq->mtx);
947 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
953 * Until we deliver this packet we can't receive next one as
954 * we have no information for sending ack.
957 mtx_unlock(&seq->mtx);
959 /* Prepend session ID to packet. */
960 M_PREPEND(m, 2, M_DONTWAIT);
963 priv->stats.memoryFailures++;
967 memcpy(mtod(m, u_int16_t *), &ids[1], 2);
969 /* Deliver packet to upper layers */
970 NG_FWD_NEW_DATA(error, item, priv->ctrl, m);
973 /* Ready to process next packet. */
976 /* If packet was successfully delivered send ack. */
978 /* Update recv sequence number */
980 /* Start receive ack timer, if not already running */
981 if (!callout_active(&seq->xack_timer)) {
982 ng_callout(&seq->xack_timer, priv->node, NULL,
983 L2TP_DELAYED_ACK, ng_l2tp_seq_xack_timeout,
987 mtx_unlock(&seq->mtx);
992 /* Per session packet, account it. */
993 hpriv->stats.recvPackets++;
994 hpriv->stats.recvOctets += plen;
996 /* Follow peer's lead in data sequencing, if configured to do so */
997 if (!hpriv->conf.control_dseq)
998 hpriv->conf.enable_dseq = ((hdr & L2TP_HDR_SEQ) != 0);
1000 /* Handle data sequence numbers if present and enabled */
1001 if ((hdr & L2TP_HDR_SEQ) != 0) {
1002 if (hpriv->conf.enable_dseq
1003 && L2TP_SEQ_DIFF(ns, hpriv->nr) < 0) {
1004 NG_FREE_ITEM(item); /* duplicate or out of order */
1006 priv->stats.recvDataDrops++;
1012 /* Drop empty data packets */
1013 if (m->m_pkthdr.len == 0) {
1020 NG_FWD_NEW_DATA(error, item, hook, m);
1023 L2TP_SEQ_CHECK(&priv->seq);
1028 * Handle an outgoing control frame.
1031 ng_l2tp_rcvdata_ctrl(hook_p hook, item_p item)
1033 const node_p node = NG_HOOK_NODE(hook);
1034 const priv_p priv = NG_NODE_PRIVATE(node);
1035 struct l2tp_seq *const seq = &priv->seq;
1042 L2TP_SEQ_CHECK(&priv->seq);
1044 /* If not configured, reject */
1045 if (!priv->conf.enabled) {
1050 /* Grab mbuf and discard other stuff XXX */
1054 /* Packet should have session ID prepended */
1055 if (m->m_pkthdr.len < 2) {
1056 priv->stats.xmitInvalid++;
1061 /* Check max length */
1062 if (m->m_pkthdr.len >= 0x10000 - 14) {
1063 priv->stats.xmitTooBig++;
1068 mtx_lock(&seq->mtx);
1070 /* Find next empty slot in transmit queue */
1071 for (i = 0; i < L2TP_MAX_XWIN && seq->xwin[i] != NULL; i++);
1072 if (i == L2TP_MAX_XWIN) {
1073 mtx_unlock(&seq->mtx);
1074 priv->stats.xmitDrops++;
1080 /* If peer's receive window is already full, nothing else to do */
1081 if (i >= seq->cwnd) {
1082 mtx_unlock(&seq->mtx);
1086 /* Start retransmit timer if not already running */
1087 if (!callout_active(&seq->rack_timer))
1088 ng_callout(&seq->rack_timer, node, NULL,
1089 hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1093 mtx_unlock(&seq->mtx);
1096 if ((m = L2TP_COPY_MBUF(m, M_DONTWAIT)) == NULL) {
1097 priv->stats.memoryFailures++;
1101 /* Send packet and increment xmit sequence number */
1102 error = ng_l2tp_xmit_ctrl(priv, m, ns);
1105 L2TP_SEQ_CHECK(&priv->seq);
1110 * Handle an outgoing data frame.
1113 ng_l2tp_rcvdata(hook_p hook, item_p item)
1115 const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
1116 const hookpriv_p hpriv = NG_HOOK_PRIVATE(hook);
1123 L2TP_SEQ_CHECK(&priv->seq);
1125 /* If not configured, reject */
1126 if (!priv->conf.enabled) {
1134 /* Check max length */
1135 if (m->m_pkthdr.len >= 0x10000 - 12) {
1136 priv->stats.xmitDataTooBig++;
1142 /* Prepend L2TP header */
1144 + (2 * (hpriv->conf.include_length != 0))
1145 + (4 * (hpriv->conf.enable_dseq != 0)),
1148 priv->stats.memoryFailures++;
1152 hdr = L2TP_DATA_HDR;
1153 if (hpriv->conf.include_length) {
1154 hdr |= L2TP_HDR_LEN;
1155 mtod(m, u_int16_t *)[i++] = htons(m->m_pkthdr.len);
1157 mtod(m, u_int16_t *)[i++] = priv->conf.peer_id;
1158 mtod(m, u_int16_t *)[i++] = hpriv->conf.peer_id;
1159 if (hpriv->conf.enable_dseq) {
1160 hdr |= L2TP_HDR_SEQ;
1161 mtod(m, u_int16_t *)[i++] = htons(hpriv->ns);
1162 mtod(m, u_int16_t *)[i++] = htons(hpriv->nr);
1165 mtod(m, u_int16_t *)[0] = htons(hdr);
1167 /* Update per session stats. */
1168 hpriv->stats.xmitPackets++;
1169 hpriv->stats.xmitOctets += m->m_pkthdr.len;
1171 /* And the global one. */
1172 priv->stats.xmitPackets++;
1173 priv->stats.xmitOctets += m->m_pkthdr.len;
1176 NG_FWD_NEW_DATA(error, item, priv->lower, m);
1179 L2TP_SEQ_CHECK(&priv->seq);
1184 * Send a message to our controlling node that we've failed.
1187 ng_l2tp_seq_failure(priv_p priv)
1189 struct ng_mesg *msg;
1192 NG_MKMESSAGE(msg, NGM_L2TP_COOKIE, NGM_L2TP_ACK_FAILURE, 0, M_NOWAIT);
1195 NG_SEND_MSG_ID(error, priv->node, msg, priv->ftarget, 0);
1198 /************************************************************************
1199 SEQUENCE NUMBER HANDLING
1200 ************************************************************************/
1203 * Initialize sequence number state.
1206 ng_l2tp_seq_init(priv_p priv)
1208 struct l2tp_seq *const seq = &priv->seq;
1210 KASSERT(priv->conf.peer_win >= 1,
1211 ("%s: peer_win is zero", __func__));
1212 memset(seq, 0, sizeof(*seq));
1214 seq->wmax = priv->conf.peer_win;
1215 if (seq->wmax > L2TP_MAX_XWIN)
1216 seq->wmax = L2TP_MAX_XWIN;
1217 seq->ssth = seq->wmax;
1218 ng_callout_init(&seq->rack_timer);
1219 ng_callout_init(&seq->xack_timer);
1220 mtx_init(&seq->mtx, "ng_l2tp", NULL, MTX_DEF);
1221 L2TP_SEQ_CHECK(seq);
1225 * Set sequence number state as given from user.
1228 ng_l2tp_seq_set(priv_p priv, const struct ng_l2tp_seq_config *conf)
1230 struct l2tp_seq *const seq = &priv->seq;
1232 /* If node is enabled, deny update to sequence numbers. */
1233 if (priv->conf.enabled)
1236 /* We only can handle the simple cases. */
1237 if (conf->xack != conf->nr || conf->ns != conf->rack)
1240 /* Set ns,nr,rack,xack parameters. */
1243 seq->rack = conf->rack;
1244 seq->xack = conf->xack;
1250 * Adjust sequence number state accordingly after reconfiguration.
1253 ng_l2tp_seq_adjust(priv_p priv, const struct ng_l2tp_config *conf)
1255 struct l2tp_seq *const seq = &priv->seq;
1258 /* If disabling node, reset state sequence number */
1259 if (!conf->enabled) {
1260 ng_l2tp_seq_reset(priv);
1264 /* Adjust peer's max recv window; it can only increase */
1265 new_wmax = conf->peer_win;
1266 if (new_wmax > L2TP_MAX_XWIN)
1267 new_wmax = L2TP_MAX_XWIN;
1270 if (new_wmax < seq->wmax)
1272 seq->wmax = new_wmax;
1279 * Reset sequence number state.
1282 ng_l2tp_seq_reset(priv_p priv)
1284 struct l2tp_seq *const seq = &priv->seq;
1289 L2TP_SEQ_CHECK(seq);
1292 ng_uncallout(&seq->rack_timer, priv->node);
1293 ng_uncallout(&seq->xack_timer, priv->node);
1295 /* Free retransmit queue */
1296 for (i = 0; i < L2TP_MAX_XWIN; i++) {
1297 if (seq->xwin[i] == NULL)
1299 m_freem(seq->xwin[i]);
1302 /* Reset session hooks' sequence number states */
1303 NG_NODE_FOREACH_HOOK(priv->node, ng_l2tp_reset_session, NULL, hook);
1305 /* Reset node's sequence number state */
1310 seq->wmax = L2TP_MAX_XWIN;
1312 seq->ssth = seq->wmax;
1315 bzero(seq->xwin, sizeof(seq->xwin));
1318 L2TP_SEQ_CHECK(seq);
1322 * Handle receipt of an acknowledgement value (Nr) from peer.
1325 ng_l2tp_seq_recv_nr(priv_p priv, u_int16_t nr)
1327 struct l2tp_seq *const seq = &priv->seq;
1328 struct mbuf *xwin[L2TP_MAX_XWIN]; /* partial local copy */
1333 mtx_lock(&seq->mtx);
1335 /* Verify peer's ACK is in range */
1336 if ((nack = L2TP_SEQ_DIFF(nr, seq->rack)) <= 0) {
1337 mtx_unlock(&seq->mtx);
1338 return; /* duplicate ack */
1340 if (L2TP_SEQ_DIFF(nr, seq->ns) > 0) {
1341 mtx_unlock(&seq->mtx);
1342 priv->stats.recvBadAcks++; /* ack for packet not sent */
1345 KASSERT(nack <= L2TP_MAX_XWIN,
1346 ("%s: nack=%d > %d", __func__, nack, L2TP_MAX_XWIN));
1348 /* Update receive ack stats */
1352 /* Free acknowledged packets and shift up packets in the xmit queue */
1353 for (i = 0; i < nack; i++)
1354 m_freem(seq->xwin[i]);
1355 memmove(seq->xwin, seq->xwin + nack,
1356 (L2TP_MAX_XWIN - nack) * sizeof(*seq->xwin));
1357 memset(seq->xwin + (L2TP_MAX_XWIN - nack), 0,
1358 nack * sizeof(*seq->xwin));
1361 * Do slow-start/congestion avoidance windowing algorithm described
1362 * in RFC 2661, Appendix A. Here we handle a multiple ACK as if each
1363 * ACK had arrived separately.
1365 if (seq->cwnd < seq->wmax) {
1367 /* Handle slow start phase */
1368 if (seq->cwnd < seq->ssth) {
1371 if (seq->cwnd > seq->ssth) { /* into cg.av. phase */
1372 nack = seq->cwnd - seq->ssth;
1373 seq->cwnd = seq->ssth;
1377 /* Handle congestion avoidance phase */
1378 if (seq->cwnd >= seq->ssth) {
1380 while (seq->acks >= seq->cwnd) {
1381 seq->acks -= seq->cwnd;
1382 if (seq->cwnd < seq->wmax)
1388 /* Stop xmit timer */
1389 if (callout_active(&seq->rack_timer))
1390 ng_uncallout(&seq->rack_timer, priv->node);
1392 /* If transmit queue is empty, we're done for now */
1393 if (seq->xwin[0] == NULL) {
1394 mtx_unlock(&seq->mtx);
1398 /* Start restransmit timer again */
1399 ng_callout(&seq->rack_timer, priv->node, NULL,
1400 hz, ng_l2tp_seq_rack_timeout, NULL, 0);
1403 * Send more packets, trying to keep peer's receive window full.
1404 * Make copy of everything we need before lock release.
1408 while ((i = L2TP_SEQ_DIFF(seq->ns, seq->rack)) < seq->cwnd
1409 && seq->xwin[i] != NULL) {
1410 xwin[j++] = seq->xwin[i];
1414 mtx_unlock(&seq->mtx);
1418 * If there is a memory error, pretend packet was sent, as it
1419 * will get retransmitted later anyway.
1421 for (i = 0; i < j; i++) {
1423 if ((m = L2TP_COPY_MBUF(xwin[i], M_DONTWAIT)) == NULL)
1424 priv->stats.memoryFailures++;
1426 ng_l2tp_xmit_ctrl(priv, m, ns);
1432 * Handle an ack timeout. We have an outstanding ack that we
1433 * were hoping to piggy-back, but haven't, so send a ZLB.
1436 ng_l2tp_seq_xack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1438 const priv_p priv = NG_NODE_PRIVATE(node);
1439 struct l2tp_seq *const seq = &priv->seq;
1441 /* Make sure callout is still active before doing anything */
1442 if (callout_pending(&seq->xack_timer) ||
1443 (!callout_active(&seq->xack_timer)))
1447 L2TP_SEQ_CHECK(seq);
1450 ng_l2tp_xmit_ctrl(priv, NULL, seq->ns);
1452 /* callout_deactivate() is not needed here
1453 as ng_uncallout() was called by ng_l2tp_xmit_ctrl() */
1456 L2TP_SEQ_CHECK(seq);
1460 * Handle a transmit timeout. The peer has failed to respond
1461 * with an ack for our packet, so retransmit it.
1464 ng_l2tp_seq_rack_timeout(node_p node, hook_p hook, void *arg1, int arg2)
1466 const priv_p priv = NG_NODE_PRIVATE(node);
1467 struct l2tp_seq *const seq = &priv->seq;
1471 /* Make sure callout is still active before doing anything */
1472 if (callout_pending(&seq->rack_timer) ||
1473 (!callout_active(&seq->rack_timer)))
1477 L2TP_SEQ_CHECK(seq);
1479 priv->stats.xmitRetransmits++;
1481 /* Have we reached the retransmit limit? If so, notify owner. */
1482 if (seq->rexmits++ >= priv->conf.rexmit_max)
1483 ng_l2tp_seq_failure(priv);
1485 /* Restart timer, this time with an increased delay */
1486 delay = (seq->rexmits > 12) ? (1 << 12) : (1 << seq->rexmits);
1487 if (delay > priv->conf.rexmit_max_to)
1488 delay = priv->conf.rexmit_max_to;
1489 ng_callout(&seq->rack_timer, node, NULL,
1490 hz * delay, ng_l2tp_seq_rack_timeout, NULL, 0);
1492 /* Do slow-start/congestion algorithm windowing algorithm */
1493 seq->ns = seq->rack;
1494 seq->ssth = (seq->cwnd + 1) / 2;
1498 /* Retransmit oldest unack'd packet */
1499 if ((m = L2TP_COPY_MBUF(seq->xwin[0], M_DONTWAIT)) == NULL)
1500 priv->stats.memoryFailures++;
1502 ng_l2tp_xmit_ctrl(priv, m, seq->ns++);
1504 /* callout_deactivate() is not needed here
1505 as ng_callout() is getting called each time */
1508 L2TP_SEQ_CHECK(seq);
1512 * Transmit a control stream packet, payload optional.
1513 * The transmit sequence number is not incremented.
1516 ng_l2tp_xmit_ctrl(priv_p priv, struct mbuf *m, u_int16_t ns)
1518 struct l2tp_seq *const seq = &priv->seq;
1519 u_int16_t session_id = 0;
1522 mtx_lock(&seq->mtx);
1524 /* Stop ack timer: we're sending an ack with this packet.
1525 Doing this before to keep state predictable after error. */
1526 if (callout_active(&seq->xack_timer))
1527 ng_uncallout(&seq->xack_timer, priv->node);
1529 seq->xack = seq->nr;
1531 mtx_unlock(&seq->mtx);
1533 /* If no mbuf passed, send an empty packet (ZLB) */
1536 /* Create a new mbuf for ZLB packet */
1537 MGETHDR(m, M_DONTWAIT, MT_DATA);
1539 priv->stats.memoryFailures++;
1542 m->m_len = m->m_pkthdr.len = 12;
1543 m->m_pkthdr.rcvif = NULL;
1544 priv->stats.xmitZLBs++;
1547 /* Strip off session ID */
1548 if (m->m_len < 2 && (m = m_pullup(m, 2)) == NULL) {
1549 priv->stats.memoryFailures++;
1552 memcpy(&session_id, mtod(m, u_int16_t *), 2);
1555 /* Make room for L2TP header */
1556 M_PREPEND(m, 12, M_DONTWAIT);
1558 priv->stats.memoryFailures++;
1563 /* Fill in L2TP header */
1564 mtod(m, u_int16_t *)[0] = htons(L2TP_CTRL_HDR);
1565 mtod(m, u_int16_t *)[1] = htons(m->m_pkthdr.len);
1566 mtod(m, u_int16_t *)[2] = priv->conf.peer_id;
1567 mtod(m, u_int16_t *)[3] = session_id;
1568 mtod(m, u_int16_t *)[4] = htons(ns);
1569 mtod(m, u_int16_t *)[5] = htons(seq->nr);
1571 /* Update sequence number info and stats */
1572 priv->stats.xmitPackets++;
1573 priv->stats.xmitOctets += m->m_pkthdr.len;
1576 NG_SEND_DATA_ONLY(error, priv->lower, m);
1582 * Sanity check sequence number state.
1585 ng_l2tp_seq_check(struct l2tp_seq *seq)
1587 int self_unack, peer_unack;
1590 #define CHECK(p) KASSERT((p), ("%s: not: %s", __func__, #p))
1592 mtx_lock(&seq->mtx);
1594 self_unack = L2TP_SEQ_DIFF(seq->nr, seq->xack);
1595 peer_unack = L2TP_SEQ_DIFF(seq->ns, seq->rack);
1596 CHECK(seq->wmax <= L2TP_MAX_XWIN);
1597 CHECK(seq->cwnd >= 1);
1598 CHECK(seq->cwnd <= seq->wmax);
1599 CHECK(seq->ssth >= 1);
1600 CHECK(seq->ssth <= seq->wmax);
1601 if (seq->cwnd < seq->ssth)
1602 CHECK(seq->acks == 0);
1604 CHECK(seq->acks <= seq->cwnd);
1605 CHECK(self_unack >= 0);
1606 CHECK(peer_unack >= 0);
1607 CHECK(peer_unack <= seq->wmax);
1608 CHECK((self_unack == 0) ^ callout_active(&seq->xack_timer));
1609 CHECK((peer_unack == 0) ^ callout_active(&seq->rack_timer));
1610 for (i = 0; i < peer_unack; i++)
1611 CHECK(seq->xwin[i] != NULL);
1612 for ( ; i < seq->cwnd; i++) /* verify peer's recv window full */
1613 CHECK(seq->xwin[i] == NULL);
1615 mtx_unlock(&seq->mtx);
1619 #endif /* INVARIANTS */