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1 office 1 /**
2 * @file
3 * Network Point to Point Protocol over Layer 2 Tunneling Protocol program file.
4 *
5 */
6  
7 /*
8 * Redistribution and use in source and binary forms, with or without modification,
9 * are permitted provided that the following conditions are met:
10 *
11 * 1. Redistributions of source code must retain the above copyright notice,
12 * this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright notice,
14 * this list of conditions and the following disclaimer in the documentation
15 * and/or other materials provided with the distribution.
16 * 3. The name of the author may not be used to endorse or promote products
17 * derived from this software without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
20 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
21 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
22 * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
23 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
24 * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
27 * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
28 * OF SUCH DAMAGE.
29 *
30 * This file is part of the lwIP TCP/IP stack.
31 *
32 */
33  
34 /*
35 * L2TP Support status:
36 *
37 * Supported:
38 * - L2TPv2 (PPP over L2TP, a.k.a. UDP tunnels)
39 * - LAC
40 *
41 * Not supported:
42 * - LNS (require PPP server support)
43 * - L2TPv3 ethernet pseudowires
44 * - L2TPv3 VLAN pseudowire
45 * - L2TPv3 PPP pseudowires
46 * - L2TPv3 IP encapsulation
47 * - L2TPv3 IP pseudowire
48 * - L2TP tunnel switching - http://tools.ietf.org/html/draft-ietf-l2tpext-tunnel-switching-08
49 * - Multiple tunnels per UDP socket, as well as multiple sessions per tunnel
50 * - Hidden AVPs
51 */
52  
53 #include "netif/ppp/ppp_opts.h"
54 #if PPP_SUPPORT && PPPOL2TP_SUPPORT /* don't build if not configured for use in lwipopts.h */
55  
56 #include "lwip/err.h"
57 #include "lwip/memp.h"
58 #include "lwip/netif.h"
59 #include "lwip/udp.h"
60 #include "lwip/snmp.h"
61  
62 #include "netif/ppp/ppp_impl.h"
63 #include "netif/ppp/lcp.h"
64 #include "netif/ppp/ipcp.h"
65 #include "netif/ppp/pppol2tp.h"
66 #include "netif/ppp/pppcrypt.h"
67 #include "netif/ppp/magic.h"
68  
69 /* Memory pool */
70 LWIP_MEMPOOL_DECLARE(PPPOL2TP_PCB, MEMP_NUM_PPPOL2TP_INTERFACES, sizeof(pppol2tp_pcb), "PPPOL2TP_PCB")
71  
72 /* callbacks called from PPP core */
73 static err_t pppol2tp_write(ppp_pcb *ppp, void *ctx, struct pbuf *p);
74 static err_t pppol2tp_netif_output(ppp_pcb *ppp, void *ctx, struct pbuf *p, u_short protocol);
75 static err_t pppol2tp_destroy(ppp_pcb *ppp, void *ctx); /* Destroy a L2TP control block */
76 static void pppol2tp_connect(ppp_pcb *ppp, void *ctx); /* Be a LAC, connect to a LNS. */
77 static void pppol2tp_disconnect(ppp_pcb *ppp, void *ctx); /* Disconnect */
78  
79 /* Prototypes for procedures local to this file. */
80 static void pppol2tp_input(void *arg, struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *addr, u16_t port);
81 static void pppol2tp_dispatch_control_packet(pppol2tp_pcb *l2tp, u16_t port, struct pbuf *p, u16_t ns, u16_t nr);
82 static void pppol2tp_timeout(void *arg);
83 static void pppol2tp_abort_connect(pppol2tp_pcb *l2tp);
84 static err_t pppol2tp_send_sccrq(pppol2tp_pcb *l2tp);
85 static err_t pppol2tp_send_scccn(pppol2tp_pcb *l2tp, u16_t ns);
86 static err_t pppol2tp_send_icrq(pppol2tp_pcb *l2tp, u16_t ns);
87 static err_t pppol2tp_send_iccn(pppol2tp_pcb *l2tp, u16_t ns);
88 static err_t pppol2tp_send_zlb(pppol2tp_pcb *l2tp, u16_t ns);
89 static err_t pppol2tp_send_stopccn(pppol2tp_pcb *l2tp, u16_t ns);
90 static err_t pppol2tp_xmit(pppol2tp_pcb *l2tp, struct pbuf *pb);
91 static err_t pppol2tp_udp_send(pppol2tp_pcb *l2tp, struct pbuf *pb);
92  
93 /* Callbacks structure for PPP core */
94 static const struct link_callbacks pppol2tp_callbacks = {
95 pppol2tp_connect,
96 #if PPP_SERVER
97 NULL,
98 #endif /* PPP_SERVER */
99 pppol2tp_disconnect,
100 pppol2tp_destroy,
101 pppol2tp_write,
102 pppol2tp_netif_output,
103 NULL,
104 NULL
105 };
106  
107  
108 /* Create a new L2TP session. */
109 ppp_pcb *pppol2tp_create(struct netif *pppif,
110 struct netif *netif, const ip_addr_t *ipaddr, u16_t port,
111 const u8_t *secret, u8_t secret_len,
112 ppp_link_status_cb_fn link_status_cb, void *ctx_cb) {
113 ppp_pcb *ppp;
114 pppol2tp_pcb *l2tp;
115 struct udp_pcb *udp;
116 #if !PPPOL2TP_AUTH_SUPPORT
117 LWIP_UNUSED_ARG(secret);
118 LWIP_UNUSED_ARG(secret_len);
119 #endif /* !PPPOL2TP_AUTH_SUPPORT */
120  
121 if (ipaddr == NULL) {
122 goto ipaddr_check_failed;
123 }
124  
125 l2tp = (pppol2tp_pcb *)LWIP_MEMPOOL_ALLOC(PPPOL2TP_PCB);
126 if (l2tp == NULL) {
127 goto memp_malloc_l2tp_failed;
128 }
129  
130 udp = udp_new_ip_type(IP_GET_TYPE(ipaddr));
131 if (udp == NULL) {
132 goto udp_new_failed;
133 }
134 udp_recv(udp, pppol2tp_input, l2tp);
135  
136 ppp = ppp_new(pppif, &pppol2tp_callbacks, l2tp, link_status_cb, ctx_cb);
137 if (ppp == NULL) {
138 goto ppp_new_failed;
139 }
140  
141 memset(l2tp, 0, sizeof(pppol2tp_pcb));
142 l2tp->phase = PPPOL2TP_STATE_INITIAL;
143 l2tp->ppp = ppp;
144 l2tp->udp = udp;
145 l2tp->netif = netif;
146 ip_addr_copy(l2tp->remote_ip, *ipaddr);
147 l2tp->remote_port = port;
148 #if PPPOL2TP_AUTH_SUPPORT
149 l2tp->secret = secret;
150 l2tp->secret_len = secret_len;
151 #endif /* PPPOL2TP_AUTH_SUPPORT */
152  
153 return ppp;
154  
155 ppp_new_failed:
156 udp_remove(udp);
157 udp_new_failed:
158 LWIP_MEMPOOL_FREE(PPPOL2TP_PCB, l2tp);
159 memp_malloc_l2tp_failed:
160 ipaddr_check_failed:
161 return NULL;
162 }
163  
164 /* Called by PPP core */
165 static err_t pppol2tp_write(ppp_pcb *ppp, void *ctx, struct pbuf *p) {
166 pppol2tp_pcb *l2tp = (pppol2tp_pcb *)ctx;
167 struct pbuf *ph; /* UDP + L2TP header */
168 err_t ret;
169 #if MIB2_STATS
170 u16_t tot_len;
171 #else /* MIB2_STATS */
172 LWIP_UNUSED_ARG(ppp);
173 #endif /* MIB2_STATS */
174  
175 ph = pbuf_alloc(PBUF_TRANSPORT, (u16_t)(PPPOL2TP_OUTPUT_DATA_HEADER_LEN), PBUF_RAM);
176 if(!ph) {
177 LINK_STATS_INC(link.memerr);
178 LINK_STATS_INC(link.proterr);
179 MIB2_STATS_NETIF_INC(ppp->netif, ifoutdiscards);
180 pbuf_free(p);
181 return ERR_MEM;
182 }
183  
184 pbuf_remove_header(ph, PPPOL2TP_OUTPUT_DATA_HEADER_LEN); /* hide L2TP header */
185 pbuf_cat(ph, p);
186 #if MIB2_STATS
187 tot_len = ph->tot_len;
188 #endif /* MIB2_STATS */
189  
190 ret = pppol2tp_xmit(l2tp, ph);
191 if (ret != ERR_OK) {
192 LINK_STATS_INC(link.err);
193 MIB2_STATS_NETIF_INC(ppp->netif, ifoutdiscards);
194 return ret;
195 }
196  
197 MIB2_STATS_NETIF_ADD(ppp->netif, ifoutoctets, (u16_t)tot_len);
198 MIB2_STATS_NETIF_INC(ppp->netif, ifoutucastpkts);
199 LINK_STATS_INC(link.xmit);
200 return ERR_OK;
201 }
202  
203 /* Called by PPP core */
204 static err_t pppol2tp_netif_output(ppp_pcb *ppp, void *ctx, struct pbuf *p, u_short protocol) {
205 pppol2tp_pcb *l2tp = (pppol2tp_pcb *)ctx;
206 struct pbuf *pb;
207 u8_t *pl;
208 err_t err;
209 #if MIB2_STATS
210 u16_t tot_len;
211 #else /* MIB2_STATS */
212 LWIP_UNUSED_ARG(ppp);
213 #endif /* MIB2_STATS */
214  
215 /* @todo: try to use pbuf_header() here! */
216 pb = pbuf_alloc(PBUF_TRANSPORT, PPPOL2TP_OUTPUT_DATA_HEADER_LEN + sizeof(protocol), PBUF_RAM);
217 if(!pb) {
218 LINK_STATS_INC(link.memerr);
219 LINK_STATS_INC(link.proterr);
220 MIB2_STATS_NETIF_INC(ppp->netif, ifoutdiscards);
221 return ERR_MEM;
222 }
223  
224 pbuf_remove_header(pb, PPPOL2TP_OUTPUT_DATA_HEADER_LEN);
225  
226 pl = (u8_t*)pb->payload;
227 PUTSHORT(protocol, pl);
228  
229 pbuf_chain(pb, p);
230 #if MIB2_STATS
231 tot_len = pb->tot_len;
232 #endif /* MIB2_STATS */
233  
234 if( (err = pppol2tp_xmit(l2tp, pb)) != ERR_OK) {
235 LINK_STATS_INC(link.err);
236 MIB2_STATS_NETIF_INC(ppp->netif, ifoutdiscards);
237 return err;
238 }
239  
240 MIB2_STATS_NETIF_ADD(ppp->netif, ifoutoctets, tot_len);
241 MIB2_STATS_NETIF_INC(ppp->netif, ifoutucastpkts);
242 LINK_STATS_INC(link.xmit);
243 return ERR_OK;
244 }
245  
246 /* Destroy a L2TP control block */
247 static err_t pppol2tp_destroy(ppp_pcb *ppp, void *ctx) {
248 pppol2tp_pcb *l2tp = (pppol2tp_pcb *)ctx;
249 LWIP_UNUSED_ARG(ppp);
250  
251 sys_untimeout(pppol2tp_timeout, l2tp);
252 udp_remove(l2tp->udp);
253 LWIP_MEMPOOL_FREE(PPPOL2TP_PCB, l2tp);
254 return ERR_OK;
255 }
256  
257 /* Be a LAC, connect to a LNS. */
258 static void pppol2tp_connect(ppp_pcb *ppp, void *ctx) {
259 err_t err;
260 pppol2tp_pcb *l2tp = (pppol2tp_pcb *)ctx;
261 lcp_options *lcp_wo;
262 lcp_options *lcp_ao;
263 #if PPP_IPV4_SUPPORT && VJ_SUPPORT
264 ipcp_options *ipcp_wo;
265 ipcp_options *ipcp_ao;
266 #endif /* PPP_IPV4_SUPPORT && VJ_SUPPORT */
267  
268 l2tp->tunnel_port = l2tp->remote_port;
269 l2tp->our_ns = 0;
270 l2tp->peer_nr = 0;
271 l2tp->peer_ns = 0;
272 l2tp->source_tunnel_id = 0;
273 l2tp->remote_tunnel_id = 0;
274 l2tp->source_session_id = 0;
275 l2tp->remote_session_id = 0;
276 /* l2tp->*_retried are cleared when used */
277  
278 lcp_wo = &ppp->lcp_wantoptions;
279 lcp_wo->mru = PPPOL2TP_DEFMRU;
280 lcp_wo->neg_asyncmap = 0;
281 lcp_wo->neg_pcompression = 0;
282 lcp_wo->neg_accompression = 0;
283 lcp_wo->passive = 0;
284 lcp_wo->silent = 0;
285  
286 lcp_ao = &ppp->lcp_allowoptions;
287 lcp_ao->mru = PPPOL2TP_DEFMRU;
288 lcp_ao->neg_asyncmap = 0;
289 lcp_ao->neg_pcompression = 0;
290 lcp_ao->neg_accompression = 0;
291  
292 #if PPP_IPV4_SUPPORT && VJ_SUPPORT
293 ipcp_wo = &ppp->ipcp_wantoptions;
294 ipcp_wo->neg_vj = 0;
295 ipcp_wo->old_vj = 0;
296  
297 ipcp_ao = &ppp->ipcp_allowoptions;
298 ipcp_ao->neg_vj = 0;
299 ipcp_ao->old_vj = 0;
300 #endif /* PPP_IPV4_SUPPORT && VJ_SUPPORT */
301  
302 /* Listen to a random source port, we need to do that instead of using udp_connect()
303 * because the L2TP LNS might answer with its own random source port (!= 1701)
304 */
305 #if LWIP_IPV6
306 if (IP_IS_V6_VAL(l2tp->udp->local_ip)) {
307 udp_bind(l2tp->udp, IP6_ADDR_ANY, 0);
308 } else
309 #endif /* LWIP_IPV6 */
310 udp_bind(l2tp->udp, IP_ADDR_ANY, 0);
311  
312 #if PPPOL2TP_AUTH_SUPPORT
313 /* Generate random vector */
314 if (l2tp->secret != NULL) {
315 magic_random_bytes(l2tp->secret_rv, sizeof(l2tp->secret_rv));
316 }
317 #endif /* PPPOL2TP_AUTH_SUPPORT */
318  
319 do {
320 l2tp->remote_tunnel_id = magic();
321 } while(l2tp->remote_tunnel_id == 0);
322 /* save state, in case we fail to send SCCRQ */
323 l2tp->sccrq_retried = 0;
324 l2tp->phase = PPPOL2TP_STATE_SCCRQ_SENT;
325 if ((err = pppol2tp_send_sccrq(l2tp)) != 0) {
326 PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send SCCRQ, error=%d\n", err));
327 }
328 sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
329 }
330  
331 /* Disconnect */
332 static void pppol2tp_disconnect(ppp_pcb *ppp, void *ctx) {
333 pppol2tp_pcb *l2tp = (pppol2tp_pcb *)ctx;
334  
335 l2tp->our_ns++;
336 pppol2tp_send_stopccn(l2tp, l2tp->our_ns);
337  
338 /* stop any timer, disconnect can be called while initiating is in progress */
339 sys_untimeout(pppol2tp_timeout, l2tp);
340 l2tp->phase = PPPOL2TP_STATE_INITIAL;
341 ppp_link_end(ppp); /* notify upper layers */
342 }
343  
344 /* UDP Callback for incoming IPv4 L2TP frames */
345 static void pppol2tp_input(void *arg, struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *addr, u16_t port) {
346 pppol2tp_pcb *l2tp = (pppol2tp_pcb*)arg;
347 u16_t hflags, hlen, len=0, tunnel_id=0, session_id=0, ns=0, nr=0, offset=0;
348 u8_t *inp;
349 LWIP_UNUSED_ARG(pcb);
350  
351 /* we can't unbound a UDP pcb, thus we can still receive UDP frames after the link is closed */
352 if (l2tp->phase < PPPOL2TP_STATE_SCCRQ_SENT) {
353 goto free_and_return;
354 }
355  
356 if (!ip_addr_cmp(&l2tp->remote_ip, addr)) {
357 goto free_and_return;
358 }
359  
360 /* discard packet if port mismatch, but only if we received a SCCRP */
361 if (l2tp->phase > PPPOL2TP_STATE_SCCRQ_SENT && l2tp->tunnel_port != port) {
362 goto free_and_return;
363 }
364  
365 /* printf("-----------\nL2TP INPUT, %d\n", p->len); */
366  
367 /* L2TP header */
368 if (p->len < sizeof(hflags) + sizeof(tunnel_id) + sizeof(session_id) ) {
369 goto packet_too_short;
370 }
371  
372 inp = (u8_t*)p->payload;
373 GETSHORT(hflags, inp);
374  
375 if (hflags & PPPOL2TP_HEADERFLAG_CONTROL) {
376 /* check mandatory flags for a control packet */
377 if ( (hflags & PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY) != PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY ) {
378 PPPDEBUG(LOG_DEBUG, ("pppol2tp: mandatory header flags for control packet not set\n"));
379 goto free_and_return;
380 }
381 /* check forbidden flags for a control packet */
382 if (hflags & PPPOL2TP_HEADERFLAG_CONTROL_FORBIDDEN) {
383 PPPDEBUG(LOG_DEBUG, ("pppol2tp: forbidden header flags for control packet found\n"));
384 goto free_and_return;
385 }
386 } else {
387 /* check mandatory flags for a data packet */
388 if ( (hflags & PPPOL2TP_HEADERFLAG_DATA_MANDATORY) != PPPOL2TP_HEADERFLAG_DATA_MANDATORY) {
389 PPPDEBUG(LOG_DEBUG, ("pppol2tp: mandatory header flags for data packet not set\n"));
390 goto free_and_return;
391 }
392 }
393  
394 /* Expected header size */
395 hlen = sizeof(hflags) + sizeof(tunnel_id) + sizeof(session_id);
396 if (hflags & PPPOL2TP_HEADERFLAG_LENGTH) {
397 hlen += sizeof(len);
398 }
399 if (hflags & PPPOL2TP_HEADERFLAG_SEQUENCE) {
400 hlen += sizeof(ns) + sizeof(nr);
401 }
402 if (hflags & PPPOL2TP_HEADERFLAG_OFFSET) {
403 hlen += sizeof(offset);
404 }
405 if (p->len < hlen) {
406 goto packet_too_short;
407 }
408  
409 if (hflags & PPPOL2TP_HEADERFLAG_LENGTH) {
410 GETSHORT(len, inp);
411 if (p->len < len || len < hlen) {
412 goto packet_too_short;
413 }
414 }
415 GETSHORT(tunnel_id, inp);
416 GETSHORT(session_id, inp);
417 if (hflags & PPPOL2TP_HEADERFLAG_SEQUENCE) {
418 GETSHORT(ns, inp);
419 GETSHORT(nr, inp);
420 }
421 if (hflags & PPPOL2TP_HEADERFLAG_OFFSET) {
422 GETSHORT(offset, inp)
423 if (offset > 4096) { /* don't be fooled with large offset which might overflow hlen */
424 PPPDEBUG(LOG_DEBUG, ("pppol2tp: strange packet received, offset=%d\n", offset));
425 goto free_and_return;
426 }
427 hlen += offset;
428 if (p->len < hlen) {
429 goto packet_too_short;
430 }
431 INCPTR(offset, inp);
432 }
433  
434 /* printf("HLEN = %d\n", hlen); */
435  
436 /* skip L2TP header */
437 if (pbuf_remove_header(p, hlen) != 0) {
438 goto free_and_return;
439 }
440  
441 /* printf("LEN=%d, TUNNEL_ID=%d, SESSION_ID=%d, NS=%d, NR=%d, OFFSET=%d\n", len, tunnel_id, session_id, ns, nr, offset); */
442 PPPDEBUG(LOG_DEBUG, ("pppol2tp: input packet, len=%"U16_F", tunnel=%"U16_F", session=%"U16_F", ns=%"U16_F", nr=%"U16_F"\n",
443 len, tunnel_id, session_id, ns, nr));
444  
445 /* Control packet */
446 if (hflags & PPPOL2TP_HEADERFLAG_CONTROL) {
447 pppol2tp_dispatch_control_packet(l2tp, port, p, ns, nr);
448 goto free_and_return;
449 }
450  
451 /* Data packet */
452 if(l2tp->phase != PPPOL2TP_STATE_DATA) {
453 goto free_and_return;
454 }
455 if(tunnel_id != l2tp->remote_tunnel_id) {
456 PPPDEBUG(LOG_DEBUG, ("pppol2tp: tunnel ID mismatch, assigned=%d, received=%d\n", l2tp->remote_tunnel_id, tunnel_id));
457 goto free_and_return;
458 }
459 if(session_id != l2tp->remote_session_id) {
460 PPPDEBUG(LOG_DEBUG, ("pppol2tp: session ID mismatch, assigned=%d, received=%d\n", l2tp->remote_session_id, session_id));
461 goto free_and_return;
462 }
463 /*
464 * skip address & flags if necessary
465 *
466 * RFC 2661 does not specify whether the PPP frame in the L2TP payload should
467 * have a HDLC header or not. We handle both cases for compatibility.
468 */
469 if (p->len >= 2) {
470 GETSHORT(hflags, inp);
471 if (hflags == 0xff03) {
472 pbuf_remove_header(p, 2);
473 }
474 }
475 /* Dispatch the packet thereby consuming it. */
476 ppp_input(l2tp->ppp, p);
477 return;
478  
479 packet_too_short:
480 PPPDEBUG(LOG_DEBUG, ("pppol2tp: packet too short: %d\n", p->len));
481 free_and_return:
482 pbuf_free(p);
483 }
484  
485 /* L2TP Control packet entry point */
486 static void pppol2tp_dispatch_control_packet(pppol2tp_pcb *l2tp, u16_t port, struct pbuf *p, u16_t ns, u16_t nr) {
487 u8_t *inp;
488 u16_t avplen, avpflags, vendorid, attributetype, messagetype=0;
489 err_t err;
490 #if PPPOL2TP_AUTH_SUPPORT
491 lwip_md5_context md5_ctx;
492 u8_t md5_hash[16];
493 u8_t challenge_id = 0;
494 #endif /* PPPOL2TP_AUTH_SUPPORT */
495  
496 l2tp->peer_nr = nr;
497 l2tp->peer_ns = ns;
498 /* printf("L2TP CTRL INPUT, ns=%d, nr=%d, len=%d\n", ns, nr, p->len); */
499  
500 /* Handle the special case of the ICCN acknowledge */
501 if (l2tp->phase == PPPOL2TP_STATE_ICCN_SENT && l2tp->peer_nr > l2tp->our_ns) {
502 l2tp->phase = PPPOL2TP_STATE_DATA;
503 }
504  
505 /* ZLB packets */
506 if (p->tot_len == 0) {
507 return;
508 }
509  
510 p = pbuf_coalesce(p, PBUF_RAW);
511 inp = (u8_t*)p->payload;
512 /* Decode AVPs */
513 while (p->len > 0) {
514 if (p->len < sizeof(avpflags) + sizeof(vendorid) + sizeof(attributetype) ) {
515 goto packet_too_short;
516 }
517 GETSHORT(avpflags, inp);
518 avplen = avpflags & PPPOL2TP_AVPHEADERFLAG_LENGTHMASK;
519 /* printf("AVPLEN = %d\n", avplen); */
520 if (p->len < avplen || avplen < sizeof(avpflags) + sizeof(vendorid) + sizeof(attributetype)) {
521 goto packet_too_short;
522 }
523 GETSHORT(vendorid, inp);
524 GETSHORT(attributetype, inp);
525 avplen -= sizeof(avpflags) + sizeof(vendorid) + sizeof(attributetype);
526  
527 /* Message type must be the first AVP */
528 if (messagetype == 0) {
529 if (attributetype != 0 || vendorid != 0 || avplen != sizeof(messagetype) ) {
530 PPPDEBUG(LOG_DEBUG, ("pppol2tp: message type must be the first AVP\n"));
531 return;
532 }
533 GETSHORT(messagetype, inp);
534 /* printf("Message type = %d\n", messagetype); */
535 switch(messagetype) {
536 /* Start Control Connection Reply */
537 case PPPOL2TP_MESSAGETYPE_SCCRP:
538 /* Only accept SCCRP packet if we sent a SCCRQ */
539 if (l2tp->phase != PPPOL2TP_STATE_SCCRQ_SENT) {
540 goto send_zlb;
541 }
542 break;
543 /* Incoming Call Reply */
544 case PPPOL2TP_MESSAGETYPE_ICRP:
545 /* Only accept ICRP packet if we sent a IRCQ */
546 if (l2tp->phase != PPPOL2TP_STATE_ICRQ_SENT) {
547 goto send_zlb;
548 }
549 break;
550 /* Stop Control Connection Notification */
551 case PPPOL2TP_MESSAGETYPE_STOPCCN:
552 pppol2tp_send_zlb(l2tp, l2tp->our_ns); /* Ack the StopCCN before we switch to down state */
553 if (l2tp->phase < PPPOL2TP_STATE_DATA) {
554 pppol2tp_abort_connect(l2tp);
555 } else if (l2tp->phase == PPPOL2TP_STATE_DATA) {
556 /* Don't disconnect here, we let the LCP Echo/Reply find the fact
557 * that PPP session is down. Asking the PPP stack to end the session
558 * require strict checking about the PPP phase to prevent endless
559 * disconnection loops.
560 */
561 }
562 return;
563 default:
564 break;
565 }
566 goto nextavp;
567 }
568  
569 /* Skip proprietary L2TP extensions */
570 if (vendorid != 0) {
571 goto skipavp;
572 }
573  
574 switch (messagetype) {
575 /* Start Control Connection Reply */
576 case PPPOL2TP_MESSAGETYPE_SCCRP:
577 switch (attributetype) {
578 case PPPOL2TP_AVPTYPE_TUNNELID:
579 if (avplen != sizeof(l2tp->source_tunnel_id) ) {
580 PPPDEBUG(LOG_DEBUG, ("pppol2tp: AVP Assign tunnel ID length check failed\n"));
581 return;
582 }
583 GETSHORT(l2tp->source_tunnel_id, inp);
584 PPPDEBUG(LOG_DEBUG, ("pppol2tp: Assigned tunnel ID %"U16_F"\n", l2tp->source_tunnel_id));
585 goto nextavp;
586 #if PPPOL2TP_AUTH_SUPPORT
587 case PPPOL2TP_AVPTYPE_CHALLENGE:
588 if (avplen == 0) {
589 PPPDEBUG(LOG_DEBUG, ("pppol2tp: Challenge length check failed\n"));
590 return;
591 }
592 if (l2tp->secret == NULL) {
593 PPPDEBUG(LOG_DEBUG, ("pppol2tp: Received challenge from peer and no secret key available\n"));
594 pppol2tp_abort_connect(l2tp);
595 return;
596 }
597 /* Generate hash of ID, secret, challenge */
598 lwip_md5_init(&md5_ctx);
599 lwip_md5_starts(&md5_ctx);
600 challenge_id = PPPOL2TP_MESSAGETYPE_SCCCN;
601 lwip_md5_update(&md5_ctx, &challenge_id, 1);
602 lwip_md5_update(&md5_ctx, l2tp->secret, l2tp->secret_len);
603 lwip_md5_update(&md5_ctx, inp, avplen);
604 lwip_md5_finish(&md5_ctx, l2tp->challenge_hash);
605 lwip_md5_free(&md5_ctx);
606 l2tp->send_challenge = 1;
607 goto skipavp;
608 case PPPOL2TP_AVPTYPE_CHALLENGERESPONSE:
609 if (avplen != PPPOL2TP_AVPTYPE_CHALLENGERESPONSE_SIZE) {
610 PPPDEBUG(LOG_DEBUG, ("pppol2tp: AVP Challenge Response length check failed\n"));
611 return;
612 }
613 /* Generate hash of ID, secret, challenge */
614 lwip_md5_init(&md5_ctx);
615 lwip_md5_starts(&md5_ctx);
616 challenge_id = PPPOL2TP_MESSAGETYPE_SCCRP;
617 lwip_md5_update(&md5_ctx, &challenge_id, 1);
618 lwip_md5_update(&md5_ctx, l2tp->secret, l2tp->secret_len);
619 lwip_md5_update(&md5_ctx, l2tp->secret_rv, sizeof(l2tp->secret_rv));
620 lwip_md5_finish(&md5_ctx, md5_hash);
621 lwip_md5_free(&md5_ctx);
622 if ( memcmp(inp, md5_hash, sizeof(md5_hash)) ) {
623 PPPDEBUG(LOG_DEBUG, ("pppol2tp: Received challenge response from peer and secret key do not match\n"));
624 pppol2tp_abort_connect(l2tp);
625 return;
626 }
627 goto skipavp;
628 #endif /* PPPOL2TP_AUTH_SUPPORT */
629 default:
630 break;
631 }
632 break;
633 /* Incoming Call Reply */
634 case PPPOL2TP_MESSAGETYPE_ICRP:
635 switch (attributetype) {
636 case PPPOL2TP_AVPTYPE_SESSIONID:
637 if (avplen != sizeof(l2tp->source_session_id) ) {
638 PPPDEBUG(LOG_DEBUG, ("pppol2tp: AVP Assign session ID length check failed\n"));
639 return;
640 }
641 GETSHORT(l2tp->source_session_id, inp);
642 PPPDEBUG(LOG_DEBUG, ("pppol2tp: Assigned session ID %"U16_F"\n", l2tp->source_session_id));
643 goto nextavp;
644 default:
645 break;
646 }
647 break;
648 default:
649 break;
650 }
651  
652 skipavp:
653 INCPTR(avplen, inp);
654 nextavp:
655 /* printf("AVP Found, vendor=%d, attribute=%d, len=%d\n", vendorid, attributetype, avplen); */
656 /* next AVP */
657 if (pbuf_remove_header(p, avplen + sizeof(avpflags) + sizeof(vendorid) + sizeof(attributetype)) != 0) {
658 return;
659 }
660 }
661  
662 switch(messagetype) {
663 /* Start Control Connection Reply */
664 case PPPOL2TP_MESSAGETYPE_SCCRP:
665 do {
666 l2tp->remote_session_id = magic();
667 } while(l2tp->remote_session_id == 0);
668 l2tp->tunnel_port = port; /* LNS server might have chosen its own local port */
669 l2tp->icrq_retried = 0;
670 l2tp->phase = PPPOL2TP_STATE_ICRQ_SENT;
671 l2tp->our_ns++;
672 if ((err = pppol2tp_send_scccn(l2tp, l2tp->our_ns)) != 0) {
673 PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send SCCCN, error=%d\n", err));
674 LWIP_UNUSED_ARG(err); /* if PPPDEBUG is disabled */
675 }
676 l2tp->our_ns++;
677 if ((err = pppol2tp_send_icrq(l2tp, l2tp->our_ns)) != 0) {
678 PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send ICRQ, error=%d\n", err));
679 LWIP_UNUSED_ARG(err); /* if PPPDEBUG is disabled */
680 }
681 sys_untimeout(pppol2tp_timeout, l2tp);
682 sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
683 break;
684 /* Incoming Call Reply */
685 case PPPOL2TP_MESSAGETYPE_ICRP:
686 l2tp->iccn_retried = 0;
687 l2tp->phase = PPPOL2TP_STATE_ICCN_SENT;
688 l2tp->our_ns++;
689 ppp_start(l2tp->ppp); /* notify upper layers */
690 if ((err = pppol2tp_send_iccn(l2tp, l2tp->our_ns)) != 0) {
691 PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send ICCN, error=%d\n", err));
692 LWIP_UNUSED_ARG(err); /* if PPPDEBUG is disabled */
693 }
694 sys_untimeout(pppol2tp_timeout, l2tp);
695 sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
696 break;
697 /* Unhandled packet, send ZLB ACK */
698 default:
699 goto send_zlb;
700 }
701 return;
702  
703 send_zlb:
704 pppol2tp_send_zlb(l2tp, l2tp->our_ns);
705 return;
706 packet_too_short:
707 PPPDEBUG(LOG_DEBUG, ("pppol2tp: packet too short: %d\n", p->len));
708 }
709  
710 /* L2TP Timeout handler */
711 static void pppol2tp_timeout(void *arg) {
712 pppol2tp_pcb *l2tp = (pppol2tp_pcb*)arg;
713 err_t err;
714 u32_t retry_wait;
715  
716 PPPDEBUG(LOG_DEBUG, ("pppol2tp: timeout\n"));
717  
718 switch (l2tp->phase) {
719 case PPPOL2TP_STATE_SCCRQ_SENT:
720 /* backoff wait */
721 if (l2tp->sccrq_retried < 0xff) {
722 l2tp->sccrq_retried++;
723 }
724 if (!l2tp->ppp->settings.persist && l2tp->sccrq_retried >= PPPOL2TP_MAXSCCRQ) {
725 pppol2tp_abort_connect(l2tp);
726 return;
727 }
728 retry_wait = LWIP_MIN(PPPOL2TP_CONTROL_TIMEOUT * l2tp->sccrq_retried, PPPOL2TP_SLOW_RETRY);
729 PPPDEBUG(LOG_DEBUG, ("pppol2tp: sccrq_retried=%d\n", l2tp->sccrq_retried));
730 if ((err = pppol2tp_send_sccrq(l2tp)) != 0) {
731 l2tp->sccrq_retried--;
732 PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send SCCRQ, error=%d\n", err));
733 LWIP_UNUSED_ARG(err); /* if PPPDEBUG is disabled */
734 }
735 sys_timeout(retry_wait, pppol2tp_timeout, l2tp);
736 break;
737  
738 case PPPOL2TP_STATE_ICRQ_SENT:
739 l2tp->icrq_retried++;
740 if (l2tp->icrq_retried >= PPPOL2TP_MAXICRQ) {
741 pppol2tp_abort_connect(l2tp);
742 return;
743 }
744 PPPDEBUG(LOG_DEBUG, ("pppol2tp: icrq_retried=%d\n", l2tp->icrq_retried));
745 if (l2tp->peer_nr <= l2tp->our_ns -1) { /* the SCCCN was not acknowledged */
746 if ((err = pppol2tp_send_scccn(l2tp, l2tp->our_ns -1)) != 0) {
747 l2tp->icrq_retried--;
748 PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send SCCCN, error=%d\n", err));
749 LWIP_UNUSED_ARG(err); /* if PPPDEBUG is disabled */
750 sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
751 break;
752 }
753 }
754 if ((err = pppol2tp_send_icrq(l2tp, l2tp->our_ns)) != 0) {
755 l2tp->icrq_retried--;
756 PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send ICRQ, error=%d\n", err));
757 LWIP_UNUSED_ARG(err); /* if PPPDEBUG is disabled */
758 }
759 sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
760 break;
761  
762 case PPPOL2TP_STATE_ICCN_SENT:
763 l2tp->iccn_retried++;
764 if (l2tp->iccn_retried >= PPPOL2TP_MAXICCN) {
765 pppol2tp_abort_connect(l2tp);
766 return;
767 }
768 PPPDEBUG(LOG_DEBUG, ("pppol2tp: iccn_retried=%d\n", l2tp->iccn_retried));
769 if ((err = pppol2tp_send_iccn(l2tp, l2tp->our_ns)) != 0) {
770 l2tp->iccn_retried--;
771 PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send ICCN, error=%d\n", err));
772 LWIP_UNUSED_ARG(err); /* if PPPDEBUG is disabled */
773 }
774 sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
775 break;
776  
777 default:
778 return; /* all done, work in peace */
779 }
780 }
781  
782 /* Connection attempt aborted */
783 static void pppol2tp_abort_connect(pppol2tp_pcb *l2tp) {
784 PPPDEBUG(LOG_DEBUG, ("pppol2tp: could not establish connection\n"));
785 l2tp->phase = PPPOL2TP_STATE_INITIAL;
786 ppp_link_failed(l2tp->ppp); /* notify upper layers */
787 }
788  
789 /* Initiate a new tunnel */
790 static err_t pppol2tp_send_sccrq(pppol2tp_pcb *l2tp) {
791 struct pbuf *pb;
792 u8_t *p;
793 u16_t len;
794  
795 /* calculate UDP packet length */
796 len = 12 +8 +8 +10 +10 +6+sizeof(PPPOL2TP_HOSTNAME)-1 +6+sizeof(PPPOL2TP_VENDORNAME)-1 +8 +8;
797 #if PPPOL2TP_AUTH_SUPPORT
798 if (l2tp->secret != NULL) {
799 len += 6 + sizeof(l2tp->secret_rv);
800 }
801 #endif /* PPPOL2TP_AUTH_SUPPORT */
802  
803 /* allocate a buffer */
804 pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
805 if (pb == NULL) {
806 return ERR_MEM;
807 }
808 LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
809  
810 p = (u8_t*)pb->payload;
811 /* fill in pkt */
812 /* L2TP control header */
813 PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
814 PUTSHORT(len, p); /* Length */
815 PUTSHORT(0, p); /* Tunnel Id */
816 PUTSHORT(0, p); /* Session Id */
817 PUTSHORT(0, p); /* NS Sequence number - to peer */
818 PUTSHORT(0, p); /* NR Sequence number - expected for peer */
819  
820 /* AVP - Message type */
821 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
822 PUTSHORT(0, p); /* Vendor ID */
823 PUTSHORT(PPPOL2TP_AVPTYPE_MESSAGE, p); /* Attribute type: Message Type */
824 PUTSHORT(PPPOL2TP_MESSAGETYPE_SCCRQ, p); /* Attribute value: Message type: SCCRQ */
825  
826 /* AVP - L2TP Version */
827 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
828 PUTSHORT(0, p); /* Vendor ID */
829 PUTSHORT(PPPOL2TP_AVPTYPE_VERSION, p); /* Attribute type: Version */
830 PUTSHORT(PPPOL2TP_VERSION, p); /* Attribute value: L2TP Version */
831  
832 /* AVP - Framing capabilities */
833 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 10, p); /* Mandatory flag + len field */
834 PUTSHORT(0, p); /* Vendor ID */
835 PUTSHORT(PPPOL2TP_AVPTYPE_FRAMINGCAPABILITIES, p); /* Attribute type: Framing capabilities */
836 PUTLONG(PPPOL2TP_FRAMINGCAPABILITIES, p); /* Attribute value: Framing capabilities */
837  
838 /* AVP - Bearer capabilities */
839 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 10, p); /* Mandatory flag + len field */
840 PUTSHORT(0, p); /* Vendor ID */
841 PUTSHORT(PPPOL2TP_AVPTYPE_BEARERCAPABILITIES, p); /* Attribute type: Bearer capabilities */
842 PUTLONG(PPPOL2TP_BEARERCAPABILITIES, p); /* Attribute value: Bearer capabilities */
843  
844 /* AVP - Host name */
845 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 6+sizeof(PPPOL2TP_HOSTNAME)-1, p); /* Mandatory flag + len field */
846 PUTSHORT(0, p); /* Vendor ID */
847 PUTSHORT(PPPOL2TP_AVPTYPE_HOSTNAME, p); /* Attribute type: Hostname */
848 MEMCPY(p, PPPOL2TP_HOSTNAME, sizeof(PPPOL2TP_HOSTNAME)-1); /* Attribute value: Hostname */
849 INCPTR(sizeof(PPPOL2TP_HOSTNAME)-1, p);
850  
851 /* AVP - Vendor name */
852 PUTSHORT(6+sizeof(PPPOL2TP_VENDORNAME)-1, p); /* len field */
853 PUTSHORT(0, p); /* Vendor ID */
854 PUTSHORT(PPPOL2TP_AVPTYPE_VENDORNAME, p); /* Attribute type: Vendor name */
855 MEMCPY(p, PPPOL2TP_VENDORNAME, sizeof(PPPOL2TP_VENDORNAME)-1); /* Attribute value: Vendor name */
856 INCPTR(sizeof(PPPOL2TP_VENDORNAME)-1, p);
857  
858 /* AVP - Assign tunnel ID */
859 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
860 PUTSHORT(0, p); /* Vendor ID */
861 PUTSHORT(PPPOL2TP_AVPTYPE_TUNNELID, p); /* Attribute type: Tunnel ID */
862 PUTSHORT(l2tp->remote_tunnel_id, p); /* Attribute value: Tunnel ID */
863  
864 /* AVP - Receive window size */
865 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
866 PUTSHORT(0, p); /* Vendor ID */
867 PUTSHORT(PPPOL2TP_AVPTYPE_RECEIVEWINDOWSIZE, p); /* Attribute type: Receive window size */
868 PUTSHORT(PPPOL2TP_RECEIVEWINDOWSIZE, p); /* Attribute value: Receive window size */
869  
870 #if PPPOL2TP_AUTH_SUPPORT
871 /* AVP - Challenge */
872 if (l2tp->secret != NULL) {
873 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 6 + sizeof(l2tp->secret_rv), p); /* Mandatory flag + len field */
874 PUTSHORT(0, p); /* Vendor ID */
875 PUTSHORT(PPPOL2TP_AVPTYPE_CHALLENGE, p); /* Attribute type: Challenge */
876 MEMCPY(p, l2tp->secret_rv, sizeof(l2tp->secret_rv)); /* Attribute value: Random vector */
877 INCPTR(sizeof(l2tp->secret_rv), p);
878 }
879 #endif /* PPPOL2TP_AUTH_SUPPORT */
880  
881 return pppol2tp_udp_send(l2tp, pb);
882 }
883  
884 /* Complete tunnel establishment */
885 static err_t pppol2tp_send_scccn(pppol2tp_pcb *l2tp, u16_t ns) {
886 struct pbuf *pb;
887 u8_t *p;
888 u16_t len;
889  
890 /* calculate UDP packet length */
891 len = 12 +8;
892 #if PPPOL2TP_AUTH_SUPPORT
893 if (l2tp->send_challenge) {
894 len += 6 + sizeof(l2tp->challenge_hash);
895 }
896 #endif /* PPPOL2TP_AUTH_SUPPORT */
897  
898 /* allocate a buffer */
899 pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
900 if (pb == NULL) {
901 return ERR_MEM;
902 }
903 LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
904  
905 p = (u8_t*)pb->payload;
906 /* fill in pkt */
907 /* L2TP control header */
908 PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
909 PUTSHORT(len, p); /* Length */
910 PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
911 PUTSHORT(0, p); /* Session Id */
912 PUTSHORT(ns, p); /* NS Sequence number - to peer */
913 PUTSHORT(l2tp->peer_ns+1, p); /* NR Sequence number - expected for peer */
914  
915 /* AVP - Message type */
916 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
917 PUTSHORT(0, p); /* Vendor ID */
918 PUTSHORT(PPPOL2TP_AVPTYPE_MESSAGE, p); /* Attribute type: Message Type */
919 PUTSHORT(PPPOL2TP_MESSAGETYPE_SCCCN, p); /* Attribute value: Message type: SCCCN */
920  
921 #if PPPOL2TP_AUTH_SUPPORT
922 /* AVP - Challenge response */
923 if (l2tp->send_challenge) {
924 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 6 + sizeof(l2tp->challenge_hash), p); /* Mandatory flag + len field */
925 PUTSHORT(0, p); /* Vendor ID */
926 PUTSHORT(PPPOL2TP_AVPTYPE_CHALLENGERESPONSE, p); /* Attribute type: Challenge response */
927 MEMCPY(p, l2tp->challenge_hash, sizeof(l2tp->challenge_hash)); /* Attribute value: Computed challenge */
928 INCPTR(sizeof(l2tp->challenge_hash), p);
929 }
930 #endif /* PPPOL2TP_AUTH_SUPPORT */
931  
932 return pppol2tp_udp_send(l2tp, pb);
933 }
934  
935 /* Initiate a new session */
936 static err_t pppol2tp_send_icrq(pppol2tp_pcb *l2tp, u16_t ns) {
937 struct pbuf *pb;
938 u8_t *p;
939 u16_t len;
940 u32_t serialnumber;
941  
942 /* calculate UDP packet length */
943 len = 12 +8 +8 +10;
944  
945 /* allocate a buffer */
946 pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
947 if (pb == NULL) {
948 return ERR_MEM;
949 }
950 LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
951  
952 p = (u8_t*)pb->payload;
953 /* fill in pkt */
954 /* L2TP control header */
955 PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
956 PUTSHORT(len, p); /* Length */
957 PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
958 PUTSHORT(0, p); /* Session Id */
959 PUTSHORT(ns, p); /* NS Sequence number - to peer */
960 PUTSHORT(l2tp->peer_ns+1, p); /* NR Sequence number - expected for peer */
961  
962 /* AVP - Message type */
963 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
964 PUTSHORT(0, p); /* Vendor ID */
965 PUTSHORT(PPPOL2TP_AVPTYPE_MESSAGE, p); /* Attribute type: Message Type */
966 PUTSHORT(PPPOL2TP_MESSAGETYPE_ICRQ, p); /* Attribute value: Message type: ICRQ */
967  
968 /* AVP - Assign session ID */
969 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
970 PUTSHORT(0, p); /* Vendor ID */
971 PUTSHORT(PPPOL2TP_AVPTYPE_SESSIONID, p); /* Attribute type: Session ID */
972 PUTSHORT(l2tp->remote_session_id, p); /* Attribute value: Session ID */
973  
974 /* AVP - Call Serial Number */
975 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 10, p); /* Mandatory flag + len field */
976 PUTSHORT(0, p); /* Vendor ID */
977 PUTSHORT(PPPOL2TP_AVPTYPE_CALLSERIALNUMBER, p); /* Attribute type: Serial number */
978 serialnumber = magic();
979 PUTLONG(serialnumber, p); /* Attribute value: Serial number */
980  
981 return pppol2tp_udp_send(l2tp, pb);
982 }
983  
984 /* Complete tunnel establishment */
985 static err_t pppol2tp_send_iccn(pppol2tp_pcb *l2tp, u16_t ns) {
986 struct pbuf *pb;
987 u8_t *p;
988 u16_t len;
989  
990 /* calculate UDP packet length */
991 len = 12 +8 +10 +10;
992  
993 /* allocate a buffer */
994 pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
995 if (pb == NULL) {
996 return ERR_MEM;
997 }
998 LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
999  
1000 p = (u8_t*)pb->payload;
1001 /* fill in pkt */
1002 /* L2TP control header */
1003 PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
1004 PUTSHORT(len, p); /* Length */
1005 PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
1006 PUTSHORT(l2tp->source_session_id, p); /* Session Id */
1007 PUTSHORT(ns, p); /* NS Sequence number - to peer */
1008 PUTSHORT(l2tp->peer_ns+1, p); /* NR Sequence number - expected for peer */
1009  
1010 /* AVP - Message type */
1011 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
1012 PUTSHORT(0, p); /* Vendor ID */
1013 PUTSHORT(PPPOL2TP_AVPTYPE_MESSAGE, p); /* Attribute type: Message Type */
1014 PUTSHORT(PPPOL2TP_MESSAGETYPE_ICCN, p); /* Attribute value: Message type: ICCN */
1015  
1016 /* AVP - Framing type */
1017 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 10, p); /* Mandatory flag + len field */
1018 PUTSHORT(0, p); /* Vendor ID */
1019 PUTSHORT(PPPOL2TP_AVPTYPE_FRAMINGTYPE, p); /* Attribute type: Framing type */
1020 PUTLONG(PPPOL2TP_FRAMINGTYPE, p); /* Attribute value: Framing type */
1021  
1022 /* AVP - TX Connect speed */
1023 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 10, p); /* Mandatory flag + len field */
1024 PUTSHORT(0, p); /* Vendor ID */
1025 PUTSHORT(PPPOL2TP_AVPTYPE_TXCONNECTSPEED, p); /* Attribute type: TX Connect speed */
1026 PUTLONG(PPPOL2TP_TXCONNECTSPEED, p); /* Attribute value: TX Connect speed */
1027  
1028 return pppol2tp_udp_send(l2tp, pb);
1029 }
1030  
1031 /* Send a ZLB ACK packet */
1032 static err_t pppol2tp_send_zlb(pppol2tp_pcb *l2tp, u16_t ns) {
1033 struct pbuf *pb;
1034 u8_t *p;
1035 u16_t len;
1036  
1037 /* calculate UDP packet length */
1038 len = 12;
1039  
1040 /* allocate a buffer */
1041 pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
1042 if (pb == NULL) {
1043 return ERR_MEM;
1044 }
1045 LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
1046  
1047 p = (u8_t*)pb->payload;
1048 /* fill in pkt */
1049 /* L2TP control header */
1050 PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
1051 PUTSHORT(len, p); /* Length */
1052 PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
1053 PUTSHORT(0, p); /* Session Id */
1054 PUTSHORT(ns, p); /* NS Sequence number - to peer */
1055 PUTSHORT(l2tp->peer_ns+1, p); /* NR Sequence number - expected for peer */
1056  
1057 return pppol2tp_udp_send(l2tp, pb);
1058 }
1059  
1060 /* Send a StopCCN packet */
1061 static err_t pppol2tp_send_stopccn(pppol2tp_pcb *l2tp, u16_t ns) {
1062 struct pbuf *pb;
1063 u8_t *p;
1064 u16_t len;
1065  
1066 /* calculate UDP packet length */
1067 len = 12 +8 +8 +8;
1068  
1069 /* allocate a buffer */
1070 pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
1071 if (pb == NULL) {
1072 return ERR_MEM;
1073 }
1074 LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
1075  
1076 p = (u8_t*)pb->payload;
1077 /* fill in pkt */
1078 /* L2TP control header */
1079 PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
1080 PUTSHORT(len, p); /* Length */
1081 PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
1082 PUTSHORT(0, p); /* Session Id */
1083 PUTSHORT(ns, p); /* NS Sequence number - to peer */
1084 PUTSHORT(l2tp->peer_ns+1, p); /* NR Sequence number - expected for peer */
1085  
1086 /* AVP - Message type */
1087 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
1088 PUTSHORT(0, p); /* Vendor ID */
1089 PUTSHORT(PPPOL2TP_AVPTYPE_MESSAGE, p); /* Attribute type: Message Type */
1090 PUTSHORT(PPPOL2TP_MESSAGETYPE_STOPCCN, p); /* Attribute value: Message type: StopCCN */
1091  
1092 /* AVP - Assign tunnel ID */
1093 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
1094 PUTSHORT(0, p); /* Vendor ID */
1095 PUTSHORT(PPPOL2TP_AVPTYPE_TUNNELID, p); /* Attribute type: Tunnel ID */
1096 PUTSHORT(l2tp->remote_tunnel_id, p); /* Attribute value: Tunnel ID */
1097  
1098 /* AVP - Result code */
1099 PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
1100 PUTSHORT(0, p); /* Vendor ID */
1101 PUTSHORT(PPPOL2TP_AVPTYPE_RESULTCODE, p); /* Attribute type: Result code */
1102 PUTSHORT(PPPOL2TP_RESULTCODE, p); /* Attribute value: Result code */
1103  
1104 return pppol2tp_udp_send(l2tp, pb);
1105 }
1106  
1107 static err_t pppol2tp_xmit(pppol2tp_pcb *l2tp, struct pbuf *pb) {
1108 u8_t *p;
1109  
1110 /* make room for L2TP header - should not fail */
1111 if (pbuf_add_header(pb, PPPOL2TP_OUTPUT_DATA_HEADER_LEN) != 0) {
1112 /* bail out */
1113 PPPDEBUG(LOG_ERR, ("pppol2tp: pppol2tp_pcb: could not allocate room for L2TP header\n"));
1114 LINK_STATS_INC(link.lenerr);
1115 pbuf_free(pb);
1116 return ERR_BUF;
1117 }
1118  
1119 p = (u8_t*)pb->payload;
1120 PUTSHORT(PPPOL2TP_HEADERFLAG_DATA_MANDATORY, p);
1121 PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
1122 PUTSHORT(l2tp->source_session_id, p); /* Session Id */
1123  
1124 return pppol2tp_udp_send(l2tp, pb);
1125 }
1126  
1127 static err_t pppol2tp_udp_send(pppol2tp_pcb *l2tp, struct pbuf *pb) {
1128 err_t err;
1129 if (l2tp->netif) {
1130 err = udp_sendto_if(l2tp->udp, pb, &l2tp->remote_ip, l2tp->tunnel_port, l2tp->netif);
1131 } else {
1132 err = udp_sendto(l2tp->udp, pb, &l2tp->remote_ip, l2tp->tunnel_port);
1133 }
1134 pbuf_free(pb);
1135 return err;
1136 }
1137  
1138 #endif /* PPP_SUPPORT && PPPOL2TP_SUPPORT */