lwip_pppol2tp.c

00001 /**
00002  * @file
00003  * Network Point to Point Protocol over Layer 2 Tunneling Protocol program file.
00004  *
00005  */
00006 
00007 /*
00008  * Redistribution and use in source and binary forms, with or without modification,
00009  * are permitted provided that the following conditions are met:
00010  *
00011  * 1. Redistributions of source code must retain the above copyright notice,
00012  *    this list of conditions and the following disclaimer.
00013  * 2. Redistributions in binary form must reproduce the above copyright notice,
00014  *    this list of conditions and the following disclaimer in the documentation
00015  *    and/or other materials provided with the distribution.
00016  * 3. The name of the author may not be used to endorse or promote products
00017  *    derived from this software without specific prior written permission.
00018  *
00019  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
00020  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
00021  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
00022  * SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
00023  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
00024  * OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
00025  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
00026  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
00027  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
00028  * OF SUCH DAMAGE.
00029  *
00030  * This file is part of the lwIP TCP/IP stack.
00031  *
00032  */
00033 
00034 /*
00035  * L2TP Support status:
00036  *
00037  * Supported:
00038  * - L2TPv2 (PPP over L2TP, a.k.a. UDP tunnels)
00039  * - LAC
00040  *
00041  * Not supported:
00042  * - LNS (require PPP server support)
00043  * - L2TPv3 ethernet pseudowires
00044  * - L2TPv3 VLAN pseudowire
00045  * - L2TPv3 PPP pseudowires
00046  * - L2TPv3 IP encapsulation
00047  * - L2TPv3 IP pseudowire
00048  * - L2TP tunnel switching - http://tools.ietf.org/html/draft-ietf-l2tpext-tunnel-switching-08
00049  * - Multiple tunnels per UDP socket, as well as multiple sessions per tunnel
00050  * - Hidden AVPs
00051  */
00052 
00053 #include "netif/ppp/ppp_opts.h"
00054 #if PPP_SUPPORT && PPPOL2TP_SUPPORT /* don't build if not configured for use in lwipopts.h */
00055 
00056 #include "lwip/err.h"
00057 #include "lwip/memp.h"
00058 #include "lwip/netif.h"
00059 #include "lwip/udp.h"
00060 #include "lwip/snmp.h"
00061 
00062 #include "netif/ppp/ppp_impl.h"
00063 #include "netif/ppp/lcp.h"
00064 #include "netif/ppp/ipcp.h"
00065 #include "netif/ppp/pppol2tp.h"
00066 #include "netif/ppp/pppcrypt.h"
00067 #include "netif/ppp/magic.h"
00068 
00069 /* Memory pool */
00070 LWIP_MEMPOOL_DECLARE(PPPOL2TP_PCB, MEMP_NUM_PPPOL2TP_INTERFACES, sizeof(pppol2tp_pcb), "PPPOL2TP_PCB")
00071 
00072 /* callbacks called from PPP core */
00073 static err_t pppol2tp_write(ppp_pcb *ppp, void *ctx, struct pbuf *p);
00074 static err_t pppol2tp_netif_output(ppp_pcb *ppp, void *ctx, struct pbuf *p, u_short protocol);
00075 static err_t pppol2tp_destroy(ppp_pcb *ppp, void *ctx);    /* Destroy a L2TP control block */
00076 static void pppol2tp_connect(ppp_pcb *ppp, void *ctx);    /* Be a LAC, connect to a LNS. */
00077 static void pppol2tp_disconnect(ppp_pcb *ppp, void *ctx);  /* Disconnect */
00078 
00079  /* Prototypes for procedures local to this file. */
00080 static void pppol2tp_input(void *arg, struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *addr, u16_t port);
00081 static void pppol2tp_dispatch_control_packet(pppol2tp_pcb *l2tp, u16_t port, struct pbuf *p, u16_t ns, u16_t nr);
00082 static void pppol2tp_timeout(void *arg);
00083 static void pppol2tp_abort_connect(pppol2tp_pcb *l2tp);
00084 static err_t pppol2tp_send_sccrq(pppol2tp_pcb *l2tp);
00085 static err_t pppol2tp_send_scccn(pppol2tp_pcb *l2tp, u16_t ns);
00086 static err_t pppol2tp_send_icrq(pppol2tp_pcb *l2tp, u16_t ns);
00087 static err_t pppol2tp_send_iccn(pppol2tp_pcb *l2tp, u16_t ns);
00088 static err_t pppol2tp_send_zlb(pppol2tp_pcb *l2tp, u16_t ns);
00089 static err_t pppol2tp_send_stopccn(pppol2tp_pcb *l2tp, u16_t ns);
00090 static err_t pppol2tp_xmit(pppol2tp_pcb *l2tp, struct pbuf *pb);
00091 static err_t pppol2tp_udp_send(pppol2tp_pcb *l2tp, struct pbuf *pb);
00092 
00093 /* Callbacks structure for PPP core */
00094 static const struct link_callbacks pppol2tp_callbacks = {
00095   pppol2tp_connect,
00096 #if PPP_SERVER
00097   NULL,
00098 #endif /* PPP_SERVER */
00099   pppol2tp_disconnect,
00100   pppol2tp_destroy,
00101   pppol2tp_write,
00102   pppol2tp_netif_output,
00103   NULL,
00104   NULL
00105 };
00106 
00107 
00108 /* Create a new L2TP session. */
00109 ppp_pcb *pppol2tp_create(struct netif *pppif,
00110        struct netif *netif, const ip_addr_t *ipaddr, u16_t port,
00111        const u8_t *secret, u8_t secret_len,
00112        ppp_link_status_cb_fn link_status_cb, void *ctx_cb) {
00113   ppp_pcb *ppp;
00114   pppol2tp_pcb *l2tp;
00115   struct udp_pcb *udp;
00116 #if !PPPOL2TP_AUTH_SUPPORT
00117   LWIP_UNUSED_ARG(secret);
00118   LWIP_UNUSED_ARG(secret_len);
00119 #endif /* !PPPOL2TP_AUTH_SUPPORT */
00120 
00121   if (ipaddr == NULL) {
00122     goto ipaddr_check_failed;
00123   }
00124 
00125   l2tp = (pppol2tp_pcb *)LWIP_MEMPOOL_ALLOC(PPPOL2TP_PCB);
00126   if (l2tp == NULL) {
00127     goto memp_malloc_l2tp_failed;
00128   }
00129 
00130   udp = udp_new_ip_type(IP_GET_TYPE(ipaddr));
00131   if (udp == NULL) {
00132     goto udp_new_failed;
00133   }
00134   udp_recv(udp, pppol2tp_input, l2tp);
00135 
00136   ppp = ppp_new(pppif, &pppol2tp_callbacks, l2tp, link_status_cb, ctx_cb);
00137   if (ppp == NULL) {
00138     goto ppp_new_failed;
00139   }
00140 
00141   memset(l2tp, 0, sizeof(pppol2tp_pcb));
00142   l2tp->phase = PPPOL2TP_STATE_INITIAL;
00143   l2tp->ppp = ppp;
00144   l2tp->udp = udp;
00145   l2tp->netif = netif;
00146   ip_addr_copy(l2tp->remote_ip, *ipaddr);
00147   l2tp->remote_port = port;
00148 #if PPPOL2TP_AUTH_SUPPORT
00149   l2tp->secret = secret;
00150   l2tp->secret_len = secret_len;
00151 #endif /* PPPOL2TP_AUTH_SUPPORT */
00152 
00153   return ppp;
00154 
00155 ppp_new_failed:
00156   udp_remove(udp);
00157 udp_new_failed:
00158   LWIP_MEMPOOL_FREE(PPPOL2TP_PCB, l2tp);
00159 memp_malloc_l2tp_failed:
00160 ipaddr_check_failed:
00161   return NULL;
00162 }
00163 
00164 /* Called by PPP core */
00165 static err_t pppol2tp_write(ppp_pcb *ppp, void *ctx, struct pbuf *p) {
00166   pppol2tp_pcb *l2tp = (pppol2tp_pcb *)ctx;
00167   struct pbuf *ph; /* UDP + L2TP header */
00168   err_t ret;
00169 #if MIB2_STATS
00170   u16_t tot_len;
00171 #else /* MIB2_STATS */
00172   LWIP_UNUSED_ARG(ppp);
00173 #endif /* MIB2_STATS */
00174 
00175   ph = pbuf_alloc(PBUF_TRANSPORT, (u16_t)(PPPOL2TP_OUTPUT_DATA_HEADER_LEN), PBUF_RAM);
00176   if(!ph) {
00177     LINK_STATS_INC(link.memerr);
00178     LINK_STATS_INC(link.proterr);
00179     MIB2_STATS_NETIF_INC(ppp->netif, ifoutdiscards);
00180     pbuf_free(p);
00181     return ERR_MEM;
00182   }
00183 
00184   pbuf_header(ph, -(s16_t)PPPOL2TP_OUTPUT_DATA_HEADER_LEN); /* hide L2TP header */
00185   pbuf_cat(ph, p);
00186 #if MIB2_STATS
00187   tot_len = ph->tot_len;
00188 #endif /* MIB2_STATS */
00189 
00190   ret = pppol2tp_xmit(l2tp, ph);
00191   if (ret != ERR_OK) {
00192     LINK_STATS_INC(link.err);
00193     MIB2_STATS_NETIF_INC(ppp->netif, ifoutdiscards);
00194     return ret;
00195   }
00196 
00197   MIB2_STATS_NETIF_ADD(ppp->netif, ifoutoctets, (u16_t)tot_len);
00198   MIB2_STATS_NETIF_INC(ppp->netif, ifoutucastpkts);
00199   LINK_STATS_INC(link.xmit);
00200   return ERR_OK;
00201 }
00202 
00203 /* Called by PPP core */
00204 static err_t pppol2tp_netif_output(ppp_pcb *ppp, void *ctx, struct pbuf *p, u_short protocol) {
00205   pppol2tp_pcb *l2tp = (pppol2tp_pcb *)ctx;
00206   struct pbuf *pb;
00207   u8_t *pl;
00208   err_t err;
00209 #if MIB2_STATS
00210   u16_t tot_len;
00211 #else /* MIB2_STATS */
00212   LWIP_UNUSED_ARG(ppp);
00213 #endif /* MIB2_STATS */
00214 
00215   /* @todo: try to use pbuf_header() here! */
00216   pb = pbuf_alloc(PBUF_TRANSPORT, PPPOL2TP_OUTPUT_DATA_HEADER_LEN + sizeof(protocol), PBUF_RAM);
00217   if(!pb) {
00218     LINK_STATS_INC(link.memerr);
00219     LINK_STATS_INC(link.proterr);
00220     MIB2_STATS_NETIF_INC(ppp->netif, ifoutdiscards);
00221     return ERR_MEM;
00222   }
00223 
00224   pbuf_header(pb, -(s16_t)PPPOL2TP_OUTPUT_DATA_HEADER_LEN);
00225 
00226   pl = (u8_t*)pb->payload;
00227   PUTSHORT(protocol, pl);
00228 
00229   pbuf_chain(pb, p);
00230 #if MIB2_STATS
00231   tot_len = pb->tot_len;
00232 #endif /* MIB2_STATS */
00233 
00234   if( (err = pppol2tp_xmit(l2tp, pb)) != ERR_OK) {
00235     LINK_STATS_INC(link.err);
00236     MIB2_STATS_NETIF_INC(ppp->netif, ifoutdiscards);
00237     return err;
00238   }
00239 
00240   MIB2_STATS_NETIF_ADD(ppp->netif, ifoutoctets, tot_len);
00241   MIB2_STATS_NETIF_INC(ppp->netif, ifoutucastpkts);
00242   LINK_STATS_INC(link.xmit);
00243   return ERR_OK;
00244 }
00245 
00246 /* Destroy a L2TP control block */
00247 static err_t pppol2tp_destroy(ppp_pcb *ppp, void *ctx) {
00248   pppol2tp_pcb *l2tp = (pppol2tp_pcb *)ctx;
00249   LWIP_UNUSED_ARG(ppp);
00250 
00251   sys_untimeout(pppol2tp_timeout, l2tp);
00252   udp_remove(l2tp->udp);
00253   LWIP_MEMPOOL_FREE(PPPOL2TP_PCB, l2tp);
00254   return ERR_OK;
00255 }
00256 
00257 /* Be a LAC, connect to a LNS. */
00258 static void pppol2tp_connect(ppp_pcb *ppp, void *ctx) {
00259   err_t err;
00260   pppol2tp_pcb *l2tp = (pppol2tp_pcb *)ctx;
00261   lcp_options *lcp_wo;
00262   lcp_options *lcp_ao;
00263 #if PPP_IPV4_SUPPORT && VJ_SUPPORT
00264   ipcp_options *ipcp_wo;
00265   ipcp_options *ipcp_ao;
00266 #endif /* PPP_IPV4_SUPPORT && VJ_SUPPORT */
00267 
00268   l2tp->tunnel_port = l2tp->remote_port;
00269   l2tp->our_ns = 0;
00270   l2tp->peer_nr = 0;
00271   l2tp->peer_ns = 0;
00272   l2tp->source_tunnel_id = 0;
00273   l2tp->remote_tunnel_id = 0;
00274   l2tp->source_session_id = 0;
00275   l2tp->remote_session_id = 0;
00276   /* l2tp->*_retried are cleared when used */
00277 
00278   lcp_wo = &ppp->lcp_wantoptions;
00279   lcp_wo->mru = PPPOL2TP_DEFMRU;
00280   lcp_wo->neg_asyncmap = 0;
00281   lcp_wo->neg_pcompression = 0;
00282   lcp_wo->neg_accompression = 0;
00283   lcp_wo->passive = 0;
00284   lcp_wo->silent = 0;
00285 
00286   lcp_ao = &ppp->lcp_allowoptions;
00287   lcp_ao->mru = PPPOL2TP_DEFMRU;
00288   lcp_ao->neg_asyncmap = 0;
00289   lcp_ao->neg_pcompression = 0;
00290   lcp_ao->neg_accompression = 0;
00291 
00292 #if PPP_IPV4_SUPPORT && VJ_SUPPORT
00293   ipcp_wo = &ppp->ipcp_wantoptions;
00294   ipcp_wo->neg_vj = 0;
00295   ipcp_wo->old_vj = 0;
00296 
00297   ipcp_ao = &ppp->ipcp_allowoptions;
00298   ipcp_ao->neg_vj = 0;
00299   ipcp_ao->old_vj = 0;
00300 #endif /* PPP_IPV4_SUPPORT && VJ_SUPPORT */
00301 
00302   /* Listen to a random source port, we need to do that instead of using udp_connect()
00303    * because the L2TP LNS might answer with its own random source port (!= 1701)
00304    */
00305 #if LWIP_IPV6
00306   if (IP_IS_V6_VAL(l2tp->udp->local_ip)) {
00307     udp_bind(l2tp->udp, IP6_ADDR_ANY, 0);
00308   } else
00309 #endif /* LWIP_IPV6 */
00310   udp_bind(l2tp->udp, IP_ADDR_ANY, 0);
00311 
00312 #if PPPOL2TP_AUTH_SUPPORT
00313   /* Generate random vector */
00314   if (l2tp->secret != NULL) {
00315     magic_random_bytes(l2tp->secret_rv, sizeof(l2tp->secret_rv));
00316   }
00317 #endif /* PPPOL2TP_AUTH_SUPPORT */
00318 
00319   do {
00320     l2tp->remote_tunnel_id = magic();
00321   } while(l2tp->remote_tunnel_id == 0);
00322   /* save state, in case we fail to send SCCRQ */
00323   l2tp->sccrq_retried = 0;
00324   l2tp->phase = PPPOL2TP_STATE_SCCRQ_SENT;
00325   if ((err = pppol2tp_send_sccrq(l2tp)) != 0) {
00326     PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send SCCRQ, error=%d\n", err));
00327   }
00328   sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
00329 }
00330 
00331 /* Disconnect */
00332 static void pppol2tp_disconnect(ppp_pcb *ppp, void *ctx) {
00333   pppol2tp_pcb *l2tp = (pppol2tp_pcb *)ctx;
00334 
00335   l2tp->our_ns++;
00336   pppol2tp_send_stopccn(l2tp, l2tp->our_ns);
00337 
00338   /* stop any timer, disconnect can be called while initiating is in progress */
00339   sys_untimeout(pppol2tp_timeout, l2tp);
00340   l2tp->phase = PPPOL2TP_STATE_INITIAL;
00341   ppp_link_end(ppp); /* notify upper layers */
00342 }
00343 
00344 /* UDP Callback for incoming IPv4 L2TP frames */
00345 static void pppol2tp_input(void *arg, struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *addr, u16_t port) {
00346   pppol2tp_pcb *l2tp = (pppol2tp_pcb*)arg;
00347   u16_t hflags, hlen, len=0, tunnel_id=0, session_id=0, ns=0, nr=0, offset=0;
00348   u8_t *inp;
00349   LWIP_UNUSED_ARG(pcb);
00350 
00351   /* we can't unbound a UDP pcb, thus we can still receive UDP frames after the link is closed */
00352   if (l2tp->phase < PPPOL2TP_STATE_SCCRQ_SENT) {
00353     goto free_and_return;
00354   }
00355 
00356   if (!ip_addr_cmp(&l2tp->remote_ip, addr)) {
00357     goto free_and_return;
00358   }
00359 
00360   /* discard packet if port mismatch, but only if we received a SCCRP */
00361   if (l2tp->phase > PPPOL2TP_STATE_SCCRQ_SENT && l2tp->tunnel_port != port) {
00362     goto free_and_return;
00363   }
00364 
00365   /* printf("-----------\nL2TP INPUT, %d\n", p->len); */
00366 
00367   /* L2TP header */
00368   if (p->len < sizeof(hflags) + sizeof(tunnel_id) + sizeof(session_id) ) {
00369     goto packet_too_short;
00370   }
00371 
00372   inp = (u8_t*)p->payload;
00373   GETSHORT(hflags, inp);
00374 
00375   if (hflags & PPPOL2TP_HEADERFLAG_CONTROL) {
00376     /* check mandatory flags for a control packet */
00377     if ( (hflags & PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY) != PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY ) {
00378       PPPDEBUG(LOG_DEBUG, ("pppol2tp: mandatory header flags for control packet not set\n"));
00379       goto free_and_return;
00380     }
00381     /* check forbidden flags for a control packet */
00382     if (hflags & PPPOL2TP_HEADERFLAG_CONTROL_FORBIDDEN) {
00383       PPPDEBUG(LOG_DEBUG, ("pppol2tp: forbidden header flags for control packet found\n"));
00384       goto free_and_return;
00385     }
00386   } else {
00387     /* check mandatory flags for a data packet */
00388     if ( (hflags & PPPOL2TP_HEADERFLAG_DATA_MANDATORY) != PPPOL2TP_HEADERFLAG_DATA_MANDATORY) {
00389       PPPDEBUG(LOG_DEBUG, ("pppol2tp: mandatory header flags for data packet not set\n"));
00390       goto free_and_return;
00391     }
00392   }
00393 
00394   /* Expected header size  */
00395   hlen = sizeof(hflags) + sizeof(tunnel_id) + sizeof(session_id);
00396   if (hflags & PPPOL2TP_HEADERFLAG_LENGTH) {
00397     hlen += sizeof(len);
00398   }
00399   if (hflags & PPPOL2TP_HEADERFLAG_SEQUENCE) {
00400     hlen += sizeof(ns) + sizeof(nr);
00401   }
00402   if (hflags & PPPOL2TP_HEADERFLAG_OFFSET) {
00403     hlen += sizeof(offset);
00404   }
00405   if (p->len < hlen) {
00406     goto packet_too_short;
00407   }
00408 
00409   if (hflags & PPPOL2TP_HEADERFLAG_LENGTH) {
00410     GETSHORT(len, inp);
00411     if (p->len < len || len < hlen) {
00412       goto packet_too_short;
00413     }
00414   }
00415   GETSHORT(tunnel_id, inp);
00416   GETSHORT(session_id, inp);
00417   if (hflags & PPPOL2TP_HEADERFLAG_SEQUENCE) {
00418     GETSHORT(ns, inp);
00419     GETSHORT(nr, inp);
00420   }
00421   if (hflags & PPPOL2TP_HEADERFLAG_OFFSET) {
00422     GETSHORT(offset, inp)
00423     if (offset > 4096) { /* don't be fooled with large offset which might overflow hlen */
00424       PPPDEBUG(LOG_DEBUG, ("pppol2tp: strange packet received, offset=%d\n", offset));
00425       goto free_and_return;
00426     }
00427     hlen += offset;
00428     if (p->len < hlen) {
00429       goto packet_too_short;
00430     }
00431     INCPTR(offset, inp);
00432   }
00433 
00434   /* printf("HLEN = %d\n", hlen); */
00435 
00436   /* skip L2TP header */
00437   if (pbuf_header(p, -(s16_t)hlen) != 0) {
00438     goto free_and_return;
00439   }
00440 
00441   /* printf("LEN=%d, TUNNEL_ID=%d, SESSION_ID=%d, NS=%d, NR=%d, OFFSET=%d\n", len, tunnel_id, session_id, ns, nr, offset); */
00442   PPPDEBUG(LOG_DEBUG, ("pppol2tp: input packet, len=%"U16_F", tunnel=%"U16_F", session=%"U16_F", ns=%"U16_F", nr=%"U16_F"\n",
00443     len, tunnel_id, session_id, ns, nr));
00444 
00445   /* Control packet */
00446   if (hflags & PPPOL2TP_HEADERFLAG_CONTROL) {
00447     pppol2tp_dispatch_control_packet(l2tp, port, p, ns, nr);
00448     goto free_and_return;
00449   }
00450 
00451   /* Data packet */
00452   if(l2tp->phase != PPPOL2TP_STATE_DATA) {
00453     goto free_and_return;
00454   }
00455   if(tunnel_id != l2tp->remote_tunnel_id) {
00456      PPPDEBUG(LOG_DEBUG, ("pppol2tp: tunnel ID mismatch, assigned=%d, received=%d\n", l2tp->remote_tunnel_id, tunnel_id));
00457      goto free_and_return;
00458   }
00459   if(session_id != l2tp->remote_session_id) {
00460      PPPDEBUG(LOG_DEBUG, ("pppol2tp: session ID mismatch, assigned=%d, received=%d\n", l2tp->remote_session_id, session_id));
00461      goto free_and_return;
00462   }
00463   /*
00464    * skip address & flags if necessary
00465    *
00466    * RFC 2661 does not specify whether the PPP frame in the L2TP payload should
00467    * have a HDLC header or not. We handle both cases for compatibility.
00468    */
00469   if (p->len >= 2) {
00470     GETSHORT(hflags, inp);
00471     if (hflags == 0xff03) {
00472       pbuf_header(p, -(s16_t)2);
00473     }
00474   }
00475   /* Dispatch the packet thereby consuming it. */
00476   ppp_input(l2tp->ppp, p);
00477   return;
00478 
00479 packet_too_short:
00480   PPPDEBUG(LOG_DEBUG, ("pppol2tp: packet too short: %d\n", p->len));
00481 free_and_return:
00482   pbuf_free(p);
00483 }
00484 
00485 /* L2TP Control packet entry point */
00486 static void pppol2tp_dispatch_control_packet(pppol2tp_pcb *l2tp, u16_t port, struct pbuf *p, u16_t ns, u16_t nr) {
00487   u8_t *inp;
00488   u16_t avplen, avpflags, vendorid, attributetype, messagetype=0;
00489   err_t err;
00490 #if PPPOL2TP_AUTH_SUPPORT
00491   lwip_md5_context md5_ctx;
00492   u8_t md5_hash[16];
00493   u8_t challenge_id = 0;
00494 #endif /* PPPOL2TP_AUTH_SUPPORT */
00495 
00496   l2tp->peer_nr = nr;
00497   l2tp->peer_ns = ns;
00498   /* printf("L2TP CTRL INPUT, ns=%d, nr=%d, len=%d\n", ns, nr, p->len); */
00499 
00500   /* Handle the special case of the ICCN acknowledge */
00501   if (l2tp->phase == PPPOL2TP_STATE_ICCN_SENT && l2tp->peer_nr > l2tp->our_ns) {
00502     l2tp->phase = PPPOL2TP_STATE_DATA;
00503   }
00504 
00505   /* ZLB packets */
00506   if (p->tot_len == 0) {
00507     return;
00508   }
00509 
00510   p = ppp_singlebuf(p);
00511   inp = (u8_t*)p->payload;
00512   /* Decode AVPs */
00513   while (p->len > 0) {
00514     if (p->len < sizeof(avpflags) + sizeof(vendorid) + sizeof(attributetype) ) {
00515       goto packet_too_short;
00516     }
00517     GETSHORT(avpflags, inp);
00518     avplen = avpflags & PPPOL2TP_AVPHEADERFLAG_LENGTHMASK;
00519     /* printf("AVPLEN = %d\n", avplen); */
00520     if (p->len < avplen || avplen < sizeof(avpflags) + sizeof(vendorid) + sizeof(attributetype)) {
00521       goto packet_too_short;
00522     }
00523     GETSHORT(vendorid, inp);
00524     GETSHORT(attributetype, inp);
00525     avplen -= sizeof(avpflags) + sizeof(vendorid) + sizeof(attributetype);
00526 
00527     /* Message type must be the first AVP */
00528     if (messagetype == 0) {
00529       if (attributetype != 0 || vendorid != 0 || avplen != sizeof(messagetype) ) {
00530         PPPDEBUG(LOG_DEBUG, ("pppol2tp: message type must be the first AVP\n"));
00531         return;
00532       }
00533       GETSHORT(messagetype, inp);
00534       /* printf("Message type = %d\n", messagetype); */
00535       switch(messagetype) {
00536         /* Start Control Connection Reply */
00537         case PPPOL2TP_MESSAGETYPE_SCCRP:
00538           /* Only accept SCCRP packet if we sent a SCCRQ */
00539           if (l2tp->phase != PPPOL2TP_STATE_SCCRQ_SENT) {
00540             goto send_zlb;
00541           }
00542           break;
00543         /* Incoming Call Reply */
00544         case PPPOL2TP_MESSAGETYPE_ICRP:
00545           /* Only accept ICRP packet if we sent a IRCQ */
00546           if (l2tp->phase != PPPOL2TP_STATE_ICRQ_SENT) {
00547             goto send_zlb;
00548           }
00549           break;
00550         /* Stop Control Connection Notification */
00551         case PPPOL2TP_MESSAGETYPE_STOPCCN:
00552           pppol2tp_send_zlb(l2tp, l2tp->our_ns); /* Ack the StopCCN before we switch to down state */
00553           if (l2tp->phase < PPPOL2TP_STATE_DATA) {
00554             pppol2tp_abort_connect(l2tp);
00555           } else if (l2tp->phase == PPPOL2TP_STATE_DATA) {
00556             /* Don't disconnect here, we let the LCP Echo/Reply find the fact
00557              * that PPP session is down. Asking the PPP stack to end the session
00558              * require strict checking about the PPP phase to prevent endless
00559              * disconnection loops.
00560              */
00561           }
00562           return;
00563         default:
00564           break;
00565       }
00566       goto nextavp;
00567     }
00568 
00569     /* Skip proprietary L2TP extensions */
00570     if (vendorid != 0) {
00571       goto skipavp;
00572     }
00573 
00574     switch (messagetype) {
00575       /* Start Control Connection Reply */
00576       case PPPOL2TP_MESSAGETYPE_SCCRP:
00577        switch (attributetype) {
00578           case PPPOL2TP_AVPTYPE_TUNNELID:
00579             if (avplen != sizeof(l2tp->source_tunnel_id) ) {
00580                PPPDEBUG(LOG_DEBUG, ("pppol2tp: AVP Assign tunnel ID length check failed\n"));
00581                return;
00582             }
00583             GETSHORT(l2tp->source_tunnel_id, inp);
00584             PPPDEBUG(LOG_DEBUG, ("pppol2tp: Assigned tunnel ID %"U16_F"\n", l2tp->source_tunnel_id));
00585             goto nextavp;
00586 #if PPPOL2TP_AUTH_SUPPORT
00587           case PPPOL2TP_AVPTYPE_CHALLENGE:
00588             if (avplen == 0) {
00589                PPPDEBUG(LOG_DEBUG, ("pppol2tp: Challenge length check failed\n"));
00590                return;
00591             }
00592             if (l2tp->secret == NULL) {
00593               PPPDEBUG(LOG_DEBUG, ("pppol2tp: Received challenge from peer and no secret key available\n"));
00594               pppol2tp_abort_connect(l2tp);
00595               return;
00596             }
00597             /* Generate hash of ID, secret, challenge */
00598             lwip_md5_init(&md5_ctx);
00599             lwip_md5_starts(&md5_ctx);
00600             challenge_id = PPPOL2TP_MESSAGETYPE_SCCCN;
00601             lwip_md5_update(&md5_ctx, &challenge_id, 1);
00602             lwip_md5_update(&md5_ctx, l2tp->secret, l2tp->secret_len);
00603             lwip_md5_update(&md5_ctx, inp, avplen);
00604             lwip_md5_finish(&md5_ctx, l2tp->challenge_hash);
00605             lwip_md5_free(&md5_ctx);
00606             l2tp->send_challenge = 1;
00607             goto skipavp;
00608           case PPPOL2TP_AVPTYPE_CHALLENGERESPONSE:
00609             if (avplen != PPPOL2TP_AVPTYPE_CHALLENGERESPONSE_SIZE) {
00610                PPPDEBUG(LOG_DEBUG, ("pppol2tp: AVP Challenge Response length check failed\n"));
00611                return;
00612             }
00613             /* Generate hash of ID, secret, challenge */
00614             lwip_md5_init(&md5_ctx);
00615             lwip_md5_starts(&md5_ctx);
00616             challenge_id = PPPOL2TP_MESSAGETYPE_SCCRP;
00617             lwip_md5_update(&md5_ctx, &challenge_id, 1);
00618             lwip_md5_update(&md5_ctx, l2tp->secret, l2tp->secret_len);
00619             lwip_md5_update(&md5_ctx, l2tp->secret_rv, sizeof(l2tp->secret_rv));
00620             lwip_md5_finish(&md5_ctx, md5_hash);
00621             lwip_md5_free(&md5_ctx);
00622             if ( memcmp(inp, md5_hash, sizeof(md5_hash)) ) {
00623               PPPDEBUG(LOG_DEBUG, ("pppol2tp: Received challenge response from peer and secret key do not match\n"));
00624               pppol2tp_abort_connect(l2tp);
00625               return;
00626             }
00627             goto skipavp;
00628 #endif /* PPPOL2TP_AUTH_SUPPORT */
00629           default:
00630             break;
00631         }
00632         break;
00633       /* Incoming Call Reply */
00634       case PPPOL2TP_MESSAGETYPE_ICRP:
00635         switch (attributetype) {
00636          case PPPOL2TP_AVPTYPE_SESSIONID:
00637             if (avplen != sizeof(l2tp->source_session_id) ) {
00638                PPPDEBUG(LOG_DEBUG, ("pppol2tp: AVP Assign session ID length check failed\n"));
00639                return;
00640             }
00641             GETSHORT(l2tp->source_session_id, inp);
00642             PPPDEBUG(LOG_DEBUG, ("pppol2tp: Assigned session ID %"U16_F"\n", l2tp->source_session_id));
00643             goto nextavp;
00644           default:
00645             break;
00646         }
00647         break;
00648       default:
00649         break;
00650     }
00651 
00652 skipavp:
00653     INCPTR(avplen, inp);
00654 nextavp:
00655     /* printf("AVP Found, vendor=%d, attribute=%d, len=%d\n", vendorid, attributetype, avplen); */
00656     /* next AVP */
00657     if (pbuf_header(p, -(s16_t)(avplen + sizeof(avpflags) + sizeof(vendorid) + sizeof(attributetype)) ) != 0) {
00658       return;
00659     }
00660   }
00661 
00662   switch(messagetype) {
00663     /* Start Control Connection Reply */
00664     case PPPOL2TP_MESSAGETYPE_SCCRP:
00665       do {
00666         l2tp->remote_session_id = magic();
00667       } while(l2tp->remote_session_id == 0);
00668       l2tp->tunnel_port = port; /* LNS server might have chosen its own local port */
00669       l2tp->icrq_retried = 0;
00670       l2tp->phase = PPPOL2TP_STATE_ICRQ_SENT;
00671       l2tp->our_ns++;
00672       if ((err = pppol2tp_send_scccn(l2tp, l2tp->our_ns)) != 0) {
00673         PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send SCCCN, error=%d\n", err));
00674       }
00675       l2tp->our_ns++;
00676       if ((err = pppol2tp_send_icrq(l2tp, l2tp->our_ns)) != 0) {
00677         PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send ICRQ, error=%d\n", err));
00678       }
00679       sys_untimeout(pppol2tp_timeout, l2tp);
00680       sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
00681       break;
00682     /* Incoming Call Reply */
00683     case PPPOL2TP_MESSAGETYPE_ICRP:
00684       l2tp->iccn_retried = 0;
00685       l2tp->phase = PPPOL2TP_STATE_ICCN_SENT;
00686       l2tp->our_ns++;
00687       ppp_start(l2tp->ppp); /* notify upper layers */
00688       if ((err = pppol2tp_send_iccn(l2tp, l2tp->our_ns)) != 0) {
00689         PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send ICCN, error=%d\n", err));
00690       }
00691       sys_untimeout(pppol2tp_timeout, l2tp);
00692       sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
00693       break;
00694     /* Unhandled packet, send ZLB ACK */
00695     default:
00696       goto send_zlb;
00697   }
00698   return;
00699 
00700 send_zlb:
00701   pppol2tp_send_zlb(l2tp, l2tp->our_ns);
00702   return;
00703 packet_too_short:
00704   PPPDEBUG(LOG_DEBUG, ("pppol2tp: packet too short: %d\n", p->len));
00705 }
00706 
00707 /* L2TP Timeout handler */
00708 static void pppol2tp_timeout(void *arg) {
00709   pppol2tp_pcb *l2tp = (pppol2tp_pcb*)arg;
00710   err_t err;
00711   u32_t retry_wait;
00712 
00713   PPPDEBUG(LOG_DEBUG, ("pppol2tp: timeout\n"));
00714 
00715   switch (l2tp->phase) {
00716     case PPPOL2TP_STATE_SCCRQ_SENT:
00717       /* backoff wait */
00718       if (l2tp->sccrq_retried < 0xff) {
00719         l2tp->sccrq_retried++;
00720       }
00721       if (!l2tp->ppp->settings.persist && l2tp->sccrq_retried >= PPPOL2TP_MAXSCCRQ) {
00722         pppol2tp_abort_connect(l2tp);
00723         return;
00724       }
00725       retry_wait = LWIP_MIN(PPPOL2TP_CONTROL_TIMEOUT * l2tp->sccrq_retried, PPPOL2TP_SLOW_RETRY);
00726       PPPDEBUG(LOG_DEBUG, ("pppol2tp: sccrq_retried=%d\n", l2tp->sccrq_retried));
00727       if ((err = pppol2tp_send_sccrq(l2tp)) != 0) {
00728         l2tp->sccrq_retried--;
00729         PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send SCCRQ, error=%d\n", err));
00730       }
00731       sys_timeout(retry_wait, pppol2tp_timeout, l2tp);
00732       break;
00733 
00734     case PPPOL2TP_STATE_ICRQ_SENT:
00735       l2tp->icrq_retried++;
00736       if (l2tp->icrq_retried >= PPPOL2TP_MAXICRQ) {
00737         pppol2tp_abort_connect(l2tp);
00738         return;
00739       }
00740       PPPDEBUG(LOG_DEBUG, ("pppol2tp: icrq_retried=%d\n", l2tp->icrq_retried));
00741       if (l2tp->peer_nr <= l2tp->our_ns -1) { /* the SCCCN was not acknowledged */
00742         if ((err = pppol2tp_send_scccn(l2tp, l2tp->our_ns -1)) != 0) {
00743       l2tp->icrq_retried--;
00744       PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send SCCCN, error=%d\n", err));
00745       sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
00746       break;
00747     }
00748       }
00749       if ((err = pppol2tp_send_icrq(l2tp, l2tp->our_ns)) != 0) {
00750     l2tp->icrq_retried--;
00751     PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send ICRQ, error=%d\n", err));
00752       }
00753       sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
00754       break;
00755 
00756     case PPPOL2TP_STATE_ICCN_SENT:
00757       l2tp->iccn_retried++;
00758       if (l2tp->iccn_retried >= PPPOL2TP_MAXICCN) {
00759         pppol2tp_abort_connect(l2tp);
00760         return;
00761       }
00762       PPPDEBUG(LOG_DEBUG, ("pppol2tp: iccn_retried=%d\n", l2tp->iccn_retried));
00763       if ((err = pppol2tp_send_iccn(l2tp, l2tp->our_ns)) != 0) {
00764     l2tp->iccn_retried--;
00765     PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send ICCN, error=%d\n", err));
00766       }
00767       sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
00768       break;
00769 
00770     default:
00771       return;  /* all done, work in peace */
00772   }
00773 }
00774 
00775 /* Connection attempt aborted */
00776 static void pppol2tp_abort_connect(pppol2tp_pcb *l2tp) {
00777   PPPDEBUG(LOG_DEBUG, ("pppol2tp: could not establish connection\n"));
00778   l2tp->phase = PPPOL2TP_STATE_INITIAL;
00779   ppp_link_failed(l2tp->ppp); /* notify upper layers */
00780 }
00781 
00782 /* Initiate a new tunnel */
00783 static err_t pppol2tp_send_sccrq(pppol2tp_pcb *l2tp) {
00784   struct pbuf *pb;
00785   u8_t *p;
00786   u16_t len;
00787 
00788   /* calculate UDP packet length */
00789   len = 12 +8 +8 +10 +10 +6+sizeof(PPPOL2TP_HOSTNAME)-1 +6+sizeof(PPPOL2TP_VENDORNAME)-1 +8 +8;
00790 #if PPPOL2TP_AUTH_SUPPORT
00791   if (l2tp->secret != NULL) {
00792     len += 6 + sizeof(l2tp->secret_rv);
00793   }
00794 #endif /* PPPOL2TP_AUTH_SUPPORT */
00795 
00796   /* allocate a buffer */
00797   pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
00798   if (pb == NULL) {
00799     return ERR_MEM;
00800   }
00801   LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
00802 
00803   p = (u8_t*)pb->payload;
00804   /* fill in pkt */
00805   /* L2TP control header */
00806   PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
00807   PUTSHORT(len, p); /* Length */
00808   PUTSHORT(0, p); /* Tunnel Id */
00809   PUTSHORT(0, p); /* Session Id */
00810   PUTSHORT(0, p); /* NS Sequence number - to peer */
00811   PUTSHORT(0, p); /* NR Sequence number - expected for peer */
00812 
00813   /* AVP - Message type */
00814   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
00815   PUTSHORT(0, p); /* Vendor ID */
00816   PUTSHORT(PPPOL2TP_AVPTYPE_MESSAGE, p); /* Attribute type: Message Type */
00817   PUTSHORT(PPPOL2TP_MESSAGETYPE_SCCRQ, p); /* Attribute value: Message type: SCCRQ */
00818 
00819   /* AVP - L2TP Version */
00820   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
00821   PUTSHORT(0, p); /* Vendor ID */
00822   PUTSHORT(PPPOL2TP_AVPTYPE_VERSION, p); /* Attribute type: Version */
00823   PUTSHORT(PPPOL2TP_VERSION, p); /* Attribute value: L2TP Version */
00824 
00825   /* AVP - Framing capabilities */
00826   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 10, p); /* Mandatory flag + len field */
00827   PUTSHORT(0, p); /* Vendor ID */
00828   PUTSHORT(PPPOL2TP_AVPTYPE_FRAMINGCAPABILITIES, p); /* Attribute type: Framing capabilities */
00829   PUTLONG(PPPOL2TP_FRAMINGCAPABILITIES, p); /* Attribute value: Framing capabilities */
00830 
00831   /* AVP - Bearer capabilities */
00832   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 10, p); /* Mandatory flag + len field */
00833   PUTSHORT(0, p); /* Vendor ID */
00834   PUTSHORT(PPPOL2TP_AVPTYPE_BEARERCAPABILITIES, p); /* Attribute type: Bearer capabilities */
00835   PUTLONG(PPPOL2TP_BEARERCAPABILITIES, p); /* Attribute value: Bearer capabilities */
00836 
00837   /* AVP - Host name */
00838   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 6+sizeof(PPPOL2TP_HOSTNAME)-1, p); /* Mandatory flag + len field */
00839   PUTSHORT(0, p); /* Vendor ID */
00840   PUTSHORT(PPPOL2TP_AVPTYPE_HOSTNAME, p); /* Attribute type: Hostname */
00841   MEMCPY(p, PPPOL2TP_HOSTNAME, sizeof(PPPOL2TP_HOSTNAME)-1); /* Attribute value: Hostname */
00842   INCPTR(sizeof(PPPOL2TP_HOSTNAME)-1, p);
00843 
00844   /* AVP - Vendor name */
00845   PUTSHORT(6+sizeof(PPPOL2TP_VENDORNAME)-1, p); /* len field */
00846   PUTSHORT(0, p); /* Vendor ID */
00847   PUTSHORT(PPPOL2TP_AVPTYPE_VENDORNAME, p); /* Attribute type: Vendor name */
00848   MEMCPY(p, PPPOL2TP_VENDORNAME, sizeof(PPPOL2TP_VENDORNAME)-1); /* Attribute value: Vendor name */
00849   INCPTR(sizeof(PPPOL2TP_VENDORNAME)-1, p);
00850 
00851   /* AVP - Assign tunnel ID */
00852   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
00853   PUTSHORT(0, p); /* Vendor ID */
00854   PUTSHORT(PPPOL2TP_AVPTYPE_TUNNELID, p); /* Attribute type: Tunnel ID */
00855   PUTSHORT(l2tp->remote_tunnel_id, p); /* Attribute value: Tunnel ID */
00856 
00857   /* AVP - Receive window size */
00858   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
00859   PUTSHORT(0, p); /* Vendor ID */
00860   PUTSHORT(PPPOL2TP_AVPTYPE_RECEIVEWINDOWSIZE, p); /* Attribute type: Receive window size */
00861   PUTSHORT(PPPOL2TP_RECEIVEWINDOWSIZE, p); /* Attribute value: Receive window size */
00862 
00863 #if PPPOL2TP_AUTH_SUPPORT
00864   /* AVP - Challenge */
00865   if (l2tp->secret != NULL) {
00866     PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 6 + sizeof(l2tp->secret_rv), p); /* Mandatory flag + len field */
00867     PUTSHORT(0, p); /* Vendor ID */
00868     PUTSHORT(PPPOL2TP_AVPTYPE_CHALLENGE, p); /* Attribute type: Challenge */
00869     MEMCPY(p, l2tp->secret_rv, sizeof(l2tp->secret_rv)); /* Attribute value: Random vector */
00870     INCPTR(sizeof(l2tp->secret_rv), p);
00871   }
00872 #endif /* PPPOL2TP_AUTH_SUPPORT */
00873 
00874   return pppol2tp_udp_send(l2tp, pb);
00875 }
00876 
00877 /* Complete tunnel establishment */
00878 static err_t pppol2tp_send_scccn(pppol2tp_pcb *l2tp, u16_t ns) {
00879   struct pbuf *pb;
00880   u8_t *p;
00881   u16_t len;
00882 
00883   /* calculate UDP packet length */
00884   len = 12 +8;
00885 #if PPPOL2TP_AUTH_SUPPORT
00886   if (l2tp->send_challenge) {
00887     len += 6 + sizeof(l2tp->challenge_hash);
00888   }
00889 #endif /* PPPOL2TP_AUTH_SUPPORT */
00890 
00891   /* allocate a buffer */
00892   pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
00893   if (pb == NULL) {
00894     return ERR_MEM;
00895   }
00896   LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
00897 
00898   p = (u8_t*)pb->payload;
00899   /* fill in pkt */
00900   /* L2TP control header */
00901   PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
00902   PUTSHORT(len, p); /* Length */
00903   PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
00904   PUTSHORT(0, p); /* Session Id */
00905   PUTSHORT(ns, p); /* NS Sequence number - to peer */
00906   PUTSHORT(l2tp->peer_ns+1, p); /* NR Sequence number - expected for peer */
00907 
00908   /* AVP - Message type */
00909   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
00910   PUTSHORT(0, p); /* Vendor ID */
00911   PUTSHORT(PPPOL2TP_AVPTYPE_MESSAGE, p); /* Attribute type: Message Type */
00912   PUTSHORT(PPPOL2TP_MESSAGETYPE_SCCCN, p); /* Attribute value: Message type: SCCCN */
00913 
00914 #if PPPOL2TP_AUTH_SUPPORT
00915   /* AVP - Challenge response */
00916   if (l2tp->send_challenge) {
00917     PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 6 + sizeof(l2tp->challenge_hash), p); /* Mandatory flag + len field */
00918     PUTSHORT(0, p); /* Vendor ID */
00919     PUTSHORT(PPPOL2TP_AVPTYPE_CHALLENGERESPONSE, p); /* Attribute type: Challenge response */
00920     MEMCPY(p, l2tp->challenge_hash, sizeof(l2tp->challenge_hash)); /* Attribute value: Computed challenge */
00921     INCPTR(sizeof(l2tp->challenge_hash), p);
00922   }
00923 #endif /* PPPOL2TP_AUTH_SUPPORT */
00924 
00925   return pppol2tp_udp_send(l2tp, pb);
00926 }
00927 
00928 /* Initiate a new session */
00929 static err_t pppol2tp_send_icrq(pppol2tp_pcb *l2tp, u16_t ns) {
00930   struct pbuf *pb;
00931   u8_t *p;
00932   u16_t len;
00933   u32_t serialnumber;
00934 
00935   /* calculate UDP packet length */
00936   len = 12 +8 +8 +10;
00937 
00938   /* allocate a buffer */
00939   pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
00940   if (pb == NULL) {
00941     return ERR_MEM;
00942   }
00943   LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
00944 
00945   p = (u8_t*)pb->payload;
00946   /* fill in pkt */
00947   /* L2TP control header */
00948   PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
00949   PUTSHORT(len, p); /* Length */
00950   PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
00951   PUTSHORT(0, p); /* Session Id */
00952   PUTSHORT(ns, p); /* NS Sequence number - to peer */
00953   PUTSHORT(l2tp->peer_ns+1, p); /* NR Sequence number - expected for peer */
00954 
00955   /* AVP - Message type */
00956   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
00957   PUTSHORT(0, p); /* Vendor ID */
00958   PUTSHORT(PPPOL2TP_AVPTYPE_MESSAGE, p); /* Attribute type: Message Type */
00959   PUTSHORT(PPPOL2TP_MESSAGETYPE_ICRQ, p); /* Attribute value: Message type: ICRQ */
00960 
00961   /* AVP - Assign session ID */
00962   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
00963   PUTSHORT(0, p); /* Vendor ID */
00964   PUTSHORT(PPPOL2TP_AVPTYPE_SESSIONID, p); /* Attribute type: Session ID */
00965   PUTSHORT(l2tp->remote_session_id, p); /* Attribute value: Session ID */
00966 
00967   /* AVP - Call Serial Number */
00968   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 10, p); /* Mandatory flag + len field */
00969   PUTSHORT(0, p); /* Vendor ID */
00970   PUTSHORT(PPPOL2TP_AVPTYPE_CALLSERIALNUMBER, p); /* Attribute type: Serial number */
00971   serialnumber = magic();
00972   PUTLONG(serialnumber, p); /* Attribute value: Serial number */
00973 
00974   return pppol2tp_udp_send(l2tp, pb);
00975 }
00976 
00977 /* Complete tunnel establishment */
00978 static err_t pppol2tp_send_iccn(pppol2tp_pcb *l2tp, u16_t ns) {
00979   struct pbuf *pb;
00980   u8_t *p;
00981   u16_t len;
00982 
00983   /* calculate UDP packet length */
00984   len = 12 +8 +10 +10;
00985 
00986   /* allocate a buffer */
00987   pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
00988   if (pb == NULL) {
00989     return ERR_MEM;
00990   }
00991   LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
00992 
00993   p = (u8_t*)pb->payload;
00994   /* fill in pkt */
00995   /* L2TP control header */
00996   PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
00997   PUTSHORT(len, p); /* Length */
00998   PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
00999   PUTSHORT(l2tp->source_session_id, p); /* Session Id */
01000   PUTSHORT(ns, p); /* NS Sequence number - to peer */
01001   PUTSHORT(l2tp->peer_ns+1, p); /* NR Sequence number - expected for peer */
01002 
01003   /* AVP - Message type */
01004   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
01005   PUTSHORT(0, p); /* Vendor ID */
01006   PUTSHORT(PPPOL2TP_AVPTYPE_MESSAGE, p); /* Attribute type: Message Type */
01007   PUTSHORT(PPPOL2TP_MESSAGETYPE_ICCN, p); /* Attribute value: Message type: ICCN */
01008 
01009   /* AVP - Framing type */
01010   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 10, p); /* Mandatory flag + len field */
01011   PUTSHORT(0, p); /* Vendor ID */
01012   PUTSHORT(PPPOL2TP_AVPTYPE_FRAMINGTYPE, p); /* Attribute type: Framing type */
01013   PUTLONG(PPPOL2TP_FRAMINGTYPE, p); /* Attribute value: Framing type */
01014 
01015   /* AVP - TX Connect speed */
01016   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 10, p); /* Mandatory flag + len field */
01017   PUTSHORT(0, p); /* Vendor ID */
01018   PUTSHORT(PPPOL2TP_AVPTYPE_TXCONNECTSPEED, p); /* Attribute type: TX Connect speed */
01019   PUTLONG(PPPOL2TP_TXCONNECTSPEED, p); /* Attribute value: TX Connect speed */
01020 
01021   return pppol2tp_udp_send(l2tp, pb);
01022 }
01023 
01024 /* Send a ZLB ACK packet */
01025 static err_t pppol2tp_send_zlb(pppol2tp_pcb *l2tp, u16_t ns) {
01026   struct pbuf *pb;
01027   u8_t *p;
01028   u16_t len;
01029 
01030   /* calculate UDP packet length */
01031   len = 12;
01032 
01033   /* allocate a buffer */
01034   pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
01035   if (pb == NULL) {
01036     return ERR_MEM;
01037   }
01038   LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
01039 
01040   p = (u8_t*)pb->payload;
01041   /* fill in pkt */
01042   /* L2TP control header */
01043   PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
01044   PUTSHORT(len, p); /* Length */
01045   PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
01046   PUTSHORT(0, p); /* Session Id */
01047   PUTSHORT(ns, p); /* NS Sequence number - to peer */
01048   PUTSHORT(l2tp->peer_ns+1, p); /* NR Sequence number - expected for peer */
01049 
01050   return pppol2tp_udp_send(l2tp, pb);
01051 }
01052 
01053 /* Send a StopCCN packet */
01054 static err_t pppol2tp_send_stopccn(pppol2tp_pcb *l2tp, u16_t ns) {
01055   struct pbuf *pb;
01056   u8_t *p;
01057   u16_t len;
01058 
01059   /* calculate UDP packet length */
01060   len = 12 +8 +8 +8;
01061 
01062   /* allocate a buffer */
01063   pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
01064   if (pb == NULL) {
01065     return ERR_MEM;
01066   }
01067   LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
01068 
01069   p = (u8_t*)pb->payload;
01070   /* fill in pkt */
01071   /* L2TP control header */
01072   PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
01073   PUTSHORT(len, p); /* Length */
01074   PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
01075   PUTSHORT(0, p); /* Session Id */
01076   PUTSHORT(ns, p); /* NS Sequence number - to peer */
01077   PUTSHORT(l2tp->peer_ns+1, p); /* NR Sequence number - expected for peer */
01078 
01079   /* AVP - Message type */
01080   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
01081   PUTSHORT(0, p); /* Vendor ID */
01082   PUTSHORT(PPPOL2TP_AVPTYPE_MESSAGE, p); /* Attribute type: Message Type */
01083   PUTSHORT(PPPOL2TP_MESSAGETYPE_STOPCCN, p); /* Attribute value: Message type: StopCCN */
01084 
01085   /* AVP - Assign tunnel ID */
01086   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
01087   PUTSHORT(0, p); /* Vendor ID */
01088   PUTSHORT(PPPOL2TP_AVPTYPE_TUNNELID, p); /* Attribute type: Tunnel ID */
01089   PUTSHORT(l2tp->remote_tunnel_id, p); /* Attribute value: Tunnel ID */
01090 
01091   /* AVP - Result code */
01092   PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
01093   PUTSHORT(0, p); /* Vendor ID */
01094   PUTSHORT(PPPOL2TP_AVPTYPE_RESULTCODE, p); /* Attribute type: Result code */
01095   PUTSHORT(PPPOL2TP_RESULTCODE, p); /* Attribute value: Result code */
01096 
01097   return pppol2tp_udp_send(l2tp, pb);
01098 }
01099 
01100 static err_t pppol2tp_xmit(pppol2tp_pcb *l2tp, struct pbuf *pb) {
01101   u8_t *p;
01102 
01103   /* make room for L2TP header - should not fail */
01104   if (pbuf_header(pb, (s16_t)PPPOL2TP_OUTPUT_DATA_HEADER_LEN) != 0) {
01105     /* bail out */
01106     PPPDEBUG(LOG_ERR, ("pppol2tp: pppol2tp_pcb: could not allocate room for L2TP header\n"));
01107     LINK_STATS_INC(link.lenerr);
01108     pbuf_free(pb);
01109     return ERR_BUF;
01110   }
01111 
01112   p = (u8_t*)pb->payload;
01113   PUTSHORT(PPPOL2TP_HEADERFLAG_DATA_MANDATORY, p);
01114   PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
01115   PUTSHORT(l2tp->source_session_id, p); /* Session Id */
01116 
01117   return pppol2tp_udp_send(l2tp, pb);
01118 }
01119 
01120 static err_t pppol2tp_udp_send(pppol2tp_pcb *l2tp, struct pbuf *pb) {
01121   err_t err;
01122   if (l2tp->netif) {
01123     err = udp_sendto_if(l2tp->udp, pb, &l2tp->remote_ip, l2tp->tunnel_port, l2tp->netif);
01124   } else {
01125     err = udp_sendto(l2tp->udp, pb, &l2tp->remote_ip, l2tp->tunnel_port);
01126   }
01127   pbuf_free(pb);
01128   return err;
01129 }
01130 
01131 #endif /* PPP_SUPPORT && PPPOL2TP_SUPPORT */