BadVPN – Rev 1
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/**
* @file
* Network Point to Point Protocol over Layer 2 Tunneling Protocol program file.
*
*/
/*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
* SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT
* OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
* OF SUCH DAMAGE.
*
* This file is part of the lwIP TCP/IP stack.
*
*/
/*
* L2TP Support status:
*
* Supported:
* - L2TPv2 (PPP over L2TP, a.k.a. UDP tunnels)
* - LAC
*
* Not supported:
* - LNS (require PPP server support)
* - L2TPv3 ethernet pseudowires
* - L2TPv3 VLAN pseudowire
* - L2TPv3 PPP pseudowires
* - L2TPv3 IP encapsulation
* - L2TPv3 IP pseudowire
* - L2TP tunnel switching - http://tools.ietf.org/html/draft-ietf-l2tpext-tunnel-switching-08
* - Multiple tunnels per UDP socket, as well as multiple sessions per tunnel
* - Hidden AVPs
*/
#include "netif/ppp/ppp_opts.h"
#if PPP_SUPPORT && PPPOL2TP_SUPPORT /* don't build if not configured for use in lwipopts.h */
#include "lwip/err.h"
#include "lwip/memp.h"
#include "lwip/netif.h"
#include "lwip/udp.h"
#include "lwip/snmp.h"
#include "netif/ppp/ppp_impl.h"
#include "netif/ppp/lcp.h"
#include "netif/ppp/ipcp.h"
#include "netif/ppp/pppol2tp.h"
#include "netif/ppp/pppcrypt.h"
#include "netif/ppp/magic.h"
/* Memory pool */
LWIP_MEMPOOL_DECLARE(PPPOL2TP_PCB, MEMP_NUM_PPPOL2TP_INTERFACES, sizeof(pppol2tp_pcb), "PPPOL2TP_PCB")
/* callbacks called from PPP core */
static err_t pppol2tp_write(ppp_pcb *ppp, void *ctx, struct pbuf *p);
static err_t pppol2tp_netif_output(ppp_pcb *ppp, void *ctx, struct pbuf *p, u_short protocol);
static err_t pppol2tp_destroy(ppp_pcb *ppp, void *ctx); /* Destroy a L2TP control block */
static void pppol2tp_connect(ppp_pcb *ppp, void *ctx); /* Be a LAC, connect to a LNS. */
static void pppol2tp_disconnect(ppp_pcb *ppp, void *ctx); /* Disconnect */
/* Prototypes for procedures local to this file. */
static void pppol2tp_input(void *arg, struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *addr, u16_t port);
static void pppol2tp_dispatch_control_packet(pppol2tp_pcb *l2tp, u16_t port, struct pbuf *p, u16_t ns, u16_t nr);
static void pppol2tp_timeout(void *arg);
static void pppol2tp_abort_connect(pppol2tp_pcb *l2tp);
static err_t pppol2tp_send_sccrq(pppol2tp_pcb *l2tp);
static err_t pppol2tp_send_scccn(pppol2tp_pcb *l2tp, u16_t ns);
static err_t pppol2tp_send_icrq(pppol2tp_pcb *l2tp, u16_t ns);
static err_t pppol2tp_send_iccn(pppol2tp_pcb *l2tp, u16_t ns);
static err_t pppol2tp_send_zlb(pppol2tp_pcb *l2tp, u16_t ns);
static err_t pppol2tp_send_stopccn(pppol2tp_pcb *l2tp, u16_t ns);
static err_t pppol2tp_xmit(pppol2tp_pcb *l2tp, struct pbuf *pb);
static err_t pppol2tp_udp_send(pppol2tp_pcb *l2tp, struct pbuf *pb);
/* Callbacks structure for PPP core */
static const struct link_callbacks pppol2tp_callbacks = {
pppol2tp_connect,
#if PPP_SERVER
NULL,
#endif /* PPP_SERVER */
pppol2tp_disconnect,
pppol2tp_destroy,
pppol2tp_write,
pppol2tp_netif_output,
NULL,
NULL
};
/* Create a new L2TP session. */
ppp_pcb *pppol2tp_create(struct netif *pppif,
struct netif *netif, const ip_addr_t *ipaddr, u16_t port,
const u8_t *secret, u8_t secret_len,
ppp_link_status_cb_fn link_status_cb, void *ctx_cb) {
ppp_pcb *ppp;
pppol2tp_pcb *l2tp;
struct udp_pcb *udp;
#if !PPPOL2TP_AUTH_SUPPORT
LWIP_UNUSED_ARG(secret);
LWIP_UNUSED_ARG(secret_len);
#endif /* !PPPOL2TP_AUTH_SUPPORT */
if (ipaddr == NULL) {
goto ipaddr_check_failed;
}
l2tp = (pppol2tp_pcb *)LWIP_MEMPOOL_ALLOC(PPPOL2TP_PCB);
if (l2tp == NULL) {
goto memp_malloc_l2tp_failed;
}
udp = udp_new_ip_type(IP_GET_TYPE(ipaddr));
if (udp == NULL) {
goto udp_new_failed;
}
udp_recv(udp, pppol2tp_input, l2tp);
ppp = ppp_new(pppif, &pppol2tp_callbacks, l2tp, link_status_cb, ctx_cb);
if (ppp == NULL) {
goto ppp_new_failed;
}
memset(l2tp, 0, sizeof(pppol2tp_pcb));
l2tp->phase = PPPOL2TP_STATE_INITIAL;
l2tp->ppp = ppp;
l2tp->udp = udp;
l2tp->netif = netif;
ip_addr_copy(l2tp->remote_ip, *ipaddr);
l2tp->remote_port = port;
#if PPPOL2TP_AUTH_SUPPORT
l2tp->secret = secret;
l2tp->secret_len = secret_len;
#endif /* PPPOL2TP_AUTH_SUPPORT */
return ppp;
ppp_new_failed:
udp_remove(udp);
udp_new_failed:
LWIP_MEMPOOL_FREE(PPPOL2TP_PCB, l2tp);
memp_malloc_l2tp_failed:
ipaddr_check_failed:
return NULL;
}
/* Called by PPP core */
static err_t pppol2tp_write(ppp_pcb *ppp, void *ctx, struct pbuf *p) {
pppol2tp_pcb *l2tp = (pppol2tp_pcb *)ctx;
struct pbuf *ph; /* UDP + L2TP header */
err_t ret;
#if MIB2_STATS
u16_t tot_len;
#else /* MIB2_STATS */
LWIP_UNUSED_ARG(ppp);
#endif /* MIB2_STATS */
ph = pbuf_alloc(PBUF_TRANSPORT, (u16_t)(PPPOL2TP_OUTPUT_DATA_HEADER_LEN), PBUF_RAM);
if(!ph) {
LINK_STATS_INC(link.memerr);
LINK_STATS_INC(link.proterr);
MIB2_STATS_NETIF_INC(ppp->netif, ifoutdiscards);
pbuf_free(p);
return ERR_MEM;
}
pbuf_remove_header(ph, PPPOL2TP_OUTPUT_DATA_HEADER_LEN); /* hide L2TP header */
pbuf_cat(ph, p);
#if MIB2_STATS
tot_len = ph->tot_len;
#endif /* MIB2_STATS */
ret = pppol2tp_xmit(l2tp, ph);
if (ret != ERR_OK) {
LINK_STATS_INC(link.err);
MIB2_STATS_NETIF_INC(ppp->netif, ifoutdiscards);
return ret;
}
MIB2_STATS_NETIF_ADD(ppp->netif, ifoutoctets, (u16_t)tot_len);
MIB2_STATS_NETIF_INC(ppp->netif, ifoutucastpkts);
LINK_STATS_INC(link.xmit);
return ERR_OK;
}
/* Called by PPP core */
static err_t pppol2tp_netif_output(ppp_pcb *ppp, void *ctx, struct pbuf *p, u_short protocol) {
pppol2tp_pcb *l2tp = (pppol2tp_pcb *)ctx;
struct pbuf *pb;
u8_t *pl;
err_t err;
#if MIB2_STATS
u16_t tot_len;
#else /* MIB2_STATS */
LWIP_UNUSED_ARG(ppp);
#endif /* MIB2_STATS */
/* @todo: try to use pbuf_header() here! */
pb = pbuf_alloc(PBUF_TRANSPORT, PPPOL2TP_OUTPUT_DATA_HEADER_LEN + sizeof(protocol), PBUF_RAM);
if(!pb) {
LINK_STATS_INC(link.memerr);
LINK_STATS_INC(link.proterr);
MIB2_STATS_NETIF_INC(ppp->netif, ifoutdiscards);
return ERR_MEM;
}
pbuf_remove_header(pb, PPPOL2TP_OUTPUT_DATA_HEADER_LEN);
pl = (u8_t*)pb->payload;
PUTSHORT(protocol, pl);
pbuf_chain(pb, p);
#if MIB2_STATS
tot_len = pb->tot_len;
#endif /* MIB2_STATS */
if( (err = pppol2tp_xmit(l2tp, pb)) != ERR_OK) {
LINK_STATS_INC(link.err);
MIB2_STATS_NETIF_INC(ppp->netif, ifoutdiscards);
return err;
}
MIB2_STATS_NETIF_ADD(ppp->netif, ifoutoctets, tot_len);
MIB2_STATS_NETIF_INC(ppp->netif, ifoutucastpkts);
LINK_STATS_INC(link.xmit);
return ERR_OK;
}
/* Destroy a L2TP control block */
static err_t pppol2tp_destroy(ppp_pcb *ppp, void *ctx) {
pppol2tp_pcb *l2tp = (pppol2tp_pcb *)ctx;
LWIP_UNUSED_ARG(ppp);
sys_untimeout(pppol2tp_timeout, l2tp);
udp_remove(l2tp->udp);
LWIP_MEMPOOL_FREE(PPPOL2TP_PCB, l2tp);
return ERR_OK;
}
/* Be a LAC, connect to a LNS. */
static void pppol2tp_connect(ppp_pcb *ppp, void *ctx) {
err_t err;
pppol2tp_pcb *l2tp = (pppol2tp_pcb *)ctx;
lcp_options *lcp_wo;
lcp_options *lcp_ao;
#if PPP_IPV4_SUPPORT && VJ_SUPPORT
ipcp_options *ipcp_wo;
ipcp_options *ipcp_ao;
#endif /* PPP_IPV4_SUPPORT && VJ_SUPPORT */
l2tp->tunnel_port = l2tp->remote_port;
l2tp->our_ns = 0;
l2tp->peer_nr = 0;
l2tp->peer_ns = 0;
l2tp->source_tunnel_id = 0;
l2tp->remote_tunnel_id = 0;
l2tp->source_session_id = 0;
l2tp->remote_session_id = 0;
/* l2tp->*_retried are cleared when used */
lcp_wo = &ppp->lcp_wantoptions;
lcp_wo->mru = PPPOL2TP_DEFMRU;
lcp_wo->neg_asyncmap = 0;
lcp_wo->neg_pcompression = 0;
lcp_wo->neg_accompression = 0;
lcp_wo->passive = 0;
lcp_wo->silent = 0;
lcp_ao = &ppp->lcp_allowoptions;
lcp_ao->mru = PPPOL2TP_DEFMRU;
lcp_ao->neg_asyncmap = 0;
lcp_ao->neg_pcompression = 0;
lcp_ao->neg_accompression = 0;
#if PPP_IPV4_SUPPORT && VJ_SUPPORT
ipcp_wo = &ppp->ipcp_wantoptions;
ipcp_wo->neg_vj = 0;
ipcp_wo->old_vj = 0;
ipcp_ao = &ppp->ipcp_allowoptions;
ipcp_ao->neg_vj = 0;
ipcp_ao->old_vj = 0;
#endif /* PPP_IPV4_SUPPORT && VJ_SUPPORT */
/* Listen to a random source port, we need to do that instead of using udp_connect()
* because the L2TP LNS might answer with its own random source port (!= 1701)
*/
#if LWIP_IPV6
if (IP_IS_V6_VAL(l2tp->udp->local_ip)) {
udp_bind(l2tp->udp, IP6_ADDR_ANY, 0);
} else
#endif /* LWIP_IPV6 */
udp_bind(l2tp->udp, IP_ADDR_ANY, 0);
#if PPPOL2TP_AUTH_SUPPORT
/* Generate random vector */
if (l2tp->secret != NULL) {
magic_random_bytes(l2tp->secret_rv, sizeof(l2tp->secret_rv));
}
#endif /* PPPOL2TP_AUTH_SUPPORT */
do {
l2tp->remote_tunnel_id = magic();
} while(l2tp->remote_tunnel_id == 0);
/* save state, in case we fail to send SCCRQ */
l2tp->sccrq_retried = 0;
l2tp->phase = PPPOL2TP_STATE_SCCRQ_SENT;
if ((err = pppol2tp_send_sccrq(l2tp)) != 0) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send SCCRQ, error=%d\n", err));
}
sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
}
/* Disconnect */
static void pppol2tp_disconnect(ppp_pcb *ppp, void *ctx) {
pppol2tp_pcb *l2tp = (pppol2tp_pcb *)ctx;
l2tp->our_ns++;
pppol2tp_send_stopccn(l2tp, l2tp->our_ns);
/* stop any timer, disconnect can be called while initiating is in progress */
sys_untimeout(pppol2tp_timeout, l2tp);
l2tp->phase = PPPOL2TP_STATE_INITIAL;
ppp_link_end(ppp); /* notify upper layers */
}
/* UDP Callback for incoming IPv4 L2TP frames */
static void pppol2tp_input(void *arg, struct udp_pcb *pcb, struct pbuf *p, const ip_addr_t *addr, u16_t port) {
pppol2tp_pcb *l2tp = (pppol2tp_pcb*)arg;
u16_t hflags, hlen, len=0, tunnel_id=0, session_id=0, ns=0, nr=0, offset=0;
u8_t *inp;
LWIP_UNUSED_ARG(pcb);
/* we can't unbound a UDP pcb, thus we can still receive UDP frames after the link is closed */
if (l2tp->phase < PPPOL2TP_STATE_SCCRQ_SENT) {
goto free_and_return;
}
if (!ip_addr_cmp(&l2tp->remote_ip, addr)) {
goto free_and_return;
}
/* discard packet if port mismatch, but only if we received a SCCRP */
if (l2tp->phase > PPPOL2TP_STATE_SCCRQ_SENT && l2tp->tunnel_port != port) {
goto free_and_return;
}
/* printf("-----------\nL2TP INPUT, %d\n", p->len); */
/* L2TP header */
if (p->len < sizeof(hflags) + sizeof(tunnel_id) + sizeof(session_id) ) {
goto packet_too_short;
}
inp = (u8_t*)p->payload;
GETSHORT(hflags, inp);
if (hflags & PPPOL2TP_HEADERFLAG_CONTROL) {
/* check mandatory flags for a control packet */
if ( (hflags & PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY) != PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY ) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: mandatory header flags for control packet not set\n"));
goto free_and_return;
}
/* check forbidden flags for a control packet */
if (hflags & PPPOL2TP_HEADERFLAG_CONTROL_FORBIDDEN) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: forbidden header flags for control packet found\n"));
goto free_and_return;
}
} else {
/* check mandatory flags for a data packet */
if ( (hflags & PPPOL2TP_HEADERFLAG_DATA_MANDATORY) != PPPOL2TP_HEADERFLAG_DATA_MANDATORY) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: mandatory header flags for data packet not set\n"));
goto free_and_return;
}
}
/* Expected header size */
hlen = sizeof(hflags) + sizeof(tunnel_id) + sizeof(session_id);
if (hflags & PPPOL2TP_HEADERFLAG_LENGTH) {
hlen += sizeof(len);
}
if (hflags & PPPOL2TP_HEADERFLAG_SEQUENCE) {
hlen += sizeof(ns) + sizeof(nr);
}
if (hflags & PPPOL2TP_HEADERFLAG_OFFSET) {
hlen += sizeof(offset);
}
if (p->len < hlen) {
goto packet_too_short;
}
if (hflags & PPPOL2TP_HEADERFLAG_LENGTH) {
GETSHORT(len, inp);
if (p->len < len || len < hlen) {
goto packet_too_short;
}
}
GETSHORT(tunnel_id, inp);
GETSHORT(session_id, inp);
if (hflags & PPPOL2TP_HEADERFLAG_SEQUENCE) {
GETSHORT(ns, inp);
GETSHORT(nr, inp);
}
if (hflags & PPPOL2TP_HEADERFLAG_OFFSET) {
GETSHORT(offset, inp)
if (offset > 4096) { /* don't be fooled with large offset which might overflow hlen */
PPPDEBUG(LOG_DEBUG, ("pppol2tp: strange packet received, offset=%d\n", offset));
goto free_and_return;
}
hlen += offset;
if (p->len < hlen) {
goto packet_too_short;
}
INCPTR(offset, inp);
}
/* printf("HLEN = %d\n", hlen); */
/* skip L2TP header */
if (pbuf_remove_header(p, hlen) != 0) {
goto free_and_return;
}
/* printf("LEN=%d, TUNNEL_ID=%d, SESSION_ID=%d, NS=%d, NR=%d, OFFSET=%d\n", len, tunnel_id, session_id, ns, nr, offset); */
PPPDEBUG(LOG_DEBUG, ("pppol2tp: input packet, len=%"U16_F", tunnel=%"U16_F", session=%"U16_F", ns=%"U16_F", nr=%"U16_F"\n",
len, tunnel_id, session_id, ns, nr));
/* Control packet */
if (hflags & PPPOL2TP_HEADERFLAG_CONTROL) {
pppol2tp_dispatch_control_packet(l2tp, port, p, ns, nr);
goto free_and_return;
}
/* Data packet */
if(l2tp->phase != PPPOL2TP_STATE_DATA) {
goto free_and_return;
}
if(tunnel_id != l2tp->remote_tunnel_id) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: tunnel ID mismatch, assigned=%d, received=%d\n", l2tp->remote_tunnel_id, tunnel_id));
goto free_and_return;
}
if(session_id != l2tp->remote_session_id) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: session ID mismatch, assigned=%d, received=%d\n", l2tp->remote_session_id, session_id));
goto free_and_return;
}
/*
* skip address & flags if necessary
*
* RFC 2661 does not specify whether the PPP frame in the L2TP payload should
* have a HDLC header or not. We handle both cases for compatibility.
*/
if (p->len >= 2) {
GETSHORT(hflags, inp);
if (hflags == 0xff03) {
pbuf_remove_header(p, 2);
}
}
/* Dispatch the packet thereby consuming it. */
ppp_input(l2tp->ppp, p);
return;
packet_too_short:
PPPDEBUG(LOG_DEBUG, ("pppol2tp: packet too short: %d\n", p->len));
free_and_return:
pbuf_free(p);
}
/* L2TP Control packet entry point */
static void pppol2tp_dispatch_control_packet(pppol2tp_pcb *l2tp, u16_t port, struct pbuf *p, u16_t ns, u16_t nr) {
u8_t *inp;
u16_t avplen, avpflags, vendorid, attributetype, messagetype=0;
err_t err;
#if PPPOL2TP_AUTH_SUPPORT
lwip_md5_context md5_ctx;
u8_t md5_hash[16];
u8_t challenge_id = 0;
#endif /* PPPOL2TP_AUTH_SUPPORT */
l2tp->peer_nr = nr;
l2tp->peer_ns = ns;
/* printf("L2TP CTRL INPUT, ns=%d, nr=%d, len=%d\n", ns, nr, p->len); */
/* Handle the special case of the ICCN acknowledge */
if (l2tp->phase == PPPOL2TP_STATE_ICCN_SENT && l2tp->peer_nr > l2tp->our_ns) {
l2tp->phase = PPPOL2TP_STATE_DATA;
}
/* ZLB packets */
if (p->tot_len == 0) {
return;
}
p = pbuf_coalesce(p, PBUF_RAW);
inp = (u8_t*)p->payload;
/* Decode AVPs */
while (p->len > 0) {
if (p->len < sizeof(avpflags) + sizeof(vendorid) + sizeof(attributetype) ) {
goto packet_too_short;
}
GETSHORT(avpflags, inp);
avplen = avpflags & PPPOL2TP_AVPHEADERFLAG_LENGTHMASK;
/* printf("AVPLEN = %d\n", avplen); */
if (p->len < avplen || avplen < sizeof(avpflags) + sizeof(vendorid) + sizeof(attributetype)) {
goto packet_too_short;
}
GETSHORT(vendorid, inp);
GETSHORT(attributetype, inp);
avplen -= sizeof(avpflags) + sizeof(vendorid) + sizeof(attributetype);
/* Message type must be the first AVP */
if (messagetype == 0) {
if (attributetype != 0 || vendorid != 0 || avplen != sizeof(messagetype) ) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: message type must be the first AVP\n"));
return;
}
GETSHORT(messagetype, inp);
/* printf("Message type = %d\n", messagetype); */
switch(messagetype) {
/* Start Control Connection Reply */
case PPPOL2TP_MESSAGETYPE_SCCRP:
/* Only accept SCCRP packet if we sent a SCCRQ */
if (l2tp->phase != PPPOL2TP_STATE_SCCRQ_SENT) {
goto send_zlb;
}
break;
/* Incoming Call Reply */
case PPPOL2TP_MESSAGETYPE_ICRP:
/* Only accept ICRP packet if we sent a IRCQ */
if (l2tp->phase != PPPOL2TP_STATE_ICRQ_SENT) {
goto send_zlb;
}
break;
/* Stop Control Connection Notification */
case PPPOL2TP_MESSAGETYPE_STOPCCN:
pppol2tp_send_zlb(l2tp, l2tp->our_ns); /* Ack the StopCCN before we switch to down state */
if (l2tp->phase < PPPOL2TP_STATE_DATA) {
pppol2tp_abort_connect(l2tp);
} else if (l2tp->phase == PPPOL2TP_STATE_DATA) {
/* Don't disconnect here, we let the LCP Echo/Reply find the fact
* that PPP session is down. Asking the PPP stack to end the session
* require strict checking about the PPP phase to prevent endless
* disconnection loops.
*/
}
return;
default:
break;
}
goto nextavp;
}
/* Skip proprietary L2TP extensions */
if (vendorid != 0) {
goto skipavp;
}
switch (messagetype) {
/* Start Control Connection Reply */
case PPPOL2TP_MESSAGETYPE_SCCRP:
switch (attributetype) {
case PPPOL2TP_AVPTYPE_TUNNELID:
if (avplen != sizeof(l2tp->source_tunnel_id) ) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: AVP Assign tunnel ID length check failed\n"));
return;
}
GETSHORT(l2tp->source_tunnel_id, inp);
PPPDEBUG(LOG_DEBUG, ("pppol2tp: Assigned tunnel ID %"U16_F"\n", l2tp->source_tunnel_id));
goto nextavp;
#if PPPOL2TP_AUTH_SUPPORT
case PPPOL2TP_AVPTYPE_CHALLENGE:
if (avplen == 0) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: Challenge length check failed\n"));
return;
}
if (l2tp->secret == NULL) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: Received challenge from peer and no secret key available\n"));
pppol2tp_abort_connect(l2tp);
return;
}
/* Generate hash of ID, secret, challenge */
lwip_md5_init(&md5_ctx);
lwip_md5_starts(&md5_ctx);
challenge_id = PPPOL2TP_MESSAGETYPE_SCCCN;
lwip_md5_update(&md5_ctx, &challenge_id, 1);
lwip_md5_update(&md5_ctx, l2tp->secret, l2tp->secret_len);
lwip_md5_update(&md5_ctx, inp, avplen);
lwip_md5_finish(&md5_ctx, l2tp->challenge_hash);
lwip_md5_free(&md5_ctx);
l2tp->send_challenge = 1;
goto skipavp;
case PPPOL2TP_AVPTYPE_CHALLENGERESPONSE:
if (avplen != PPPOL2TP_AVPTYPE_CHALLENGERESPONSE_SIZE) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: AVP Challenge Response length check failed\n"));
return;
}
/* Generate hash of ID, secret, challenge */
lwip_md5_init(&md5_ctx);
lwip_md5_starts(&md5_ctx);
challenge_id = PPPOL2TP_MESSAGETYPE_SCCRP;
lwip_md5_update(&md5_ctx, &challenge_id, 1);
lwip_md5_update(&md5_ctx, l2tp->secret, l2tp->secret_len);
lwip_md5_update(&md5_ctx, l2tp->secret_rv, sizeof(l2tp->secret_rv));
lwip_md5_finish(&md5_ctx, md5_hash);
lwip_md5_free(&md5_ctx);
if ( memcmp(inp, md5_hash, sizeof(md5_hash)) ) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: Received challenge response from peer and secret key do not match\n"));
pppol2tp_abort_connect(l2tp);
return;
}
goto skipavp;
#endif /* PPPOL2TP_AUTH_SUPPORT */
default:
break;
}
break;
/* Incoming Call Reply */
case PPPOL2TP_MESSAGETYPE_ICRP:
switch (attributetype) {
case PPPOL2TP_AVPTYPE_SESSIONID:
if (avplen != sizeof(l2tp->source_session_id) ) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: AVP Assign session ID length check failed\n"));
return;
}
GETSHORT(l2tp->source_session_id, inp);
PPPDEBUG(LOG_DEBUG, ("pppol2tp: Assigned session ID %"U16_F"\n", l2tp->source_session_id));
goto nextavp;
default:
break;
}
break;
default:
break;
}
skipavp:
INCPTR(avplen, inp);
nextavp:
/* printf("AVP Found, vendor=%d, attribute=%d, len=%d\n", vendorid, attributetype, avplen); */
/* next AVP */
if (pbuf_remove_header(p, avplen + sizeof(avpflags) + sizeof(vendorid) + sizeof(attributetype)) != 0) {
return;
}
}
switch(messagetype) {
/* Start Control Connection Reply */
case PPPOL2TP_MESSAGETYPE_SCCRP:
do {
l2tp->remote_session_id = magic();
} while(l2tp->remote_session_id == 0);
l2tp->tunnel_port = port; /* LNS server might have chosen its own local port */
l2tp->icrq_retried = 0;
l2tp->phase = PPPOL2TP_STATE_ICRQ_SENT;
l2tp->our_ns++;
if ((err = pppol2tp_send_scccn(l2tp, l2tp->our_ns)) != 0) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send SCCCN, error=%d\n", err));
LWIP_UNUSED_ARG(err); /* if PPPDEBUG is disabled */
}
l2tp->our_ns++;
if ((err = pppol2tp_send_icrq(l2tp, l2tp->our_ns)) != 0) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send ICRQ, error=%d\n", err));
LWIP_UNUSED_ARG(err); /* if PPPDEBUG is disabled */
}
sys_untimeout(pppol2tp_timeout, l2tp);
sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
break;
/* Incoming Call Reply */
case PPPOL2TP_MESSAGETYPE_ICRP:
l2tp->iccn_retried = 0;
l2tp->phase = PPPOL2TP_STATE_ICCN_SENT;
l2tp->our_ns++;
ppp_start(l2tp->ppp); /* notify upper layers */
if ((err = pppol2tp_send_iccn(l2tp, l2tp->our_ns)) != 0) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send ICCN, error=%d\n", err));
LWIP_UNUSED_ARG(err); /* if PPPDEBUG is disabled */
}
sys_untimeout(pppol2tp_timeout, l2tp);
sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
break;
/* Unhandled packet, send ZLB ACK */
default:
goto send_zlb;
}
return;
send_zlb:
pppol2tp_send_zlb(l2tp, l2tp->our_ns);
return;
packet_too_short:
PPPDEBUG(LOG_DEBUG, ("pppol2tp: packet too short: %d\n", p->len));
}
/* L2TP Timeout handler */
static void pppol2tp_timeout(void *arg) {
pppol2tp_pcb *l2tp = (pppol2tp_pcb*)arg;
err_t err;
u32_t retry_wait;
PPPDEBUG(LOG_DEBUG, ("pppol2tp: timeout\n"));
switch (l2tp->phase) {
case PPPOL2TP_STATE_SCCRQ_SENT:
/* backoff wait */
if (l2tp->sccrq_retried < 0xff) {
l2tp->sccrq_retried++;
}
if (!l2tp->ppp->settings.persist && l2tp->sccrq_retried >= PPPOL2TP_MAXSCCRQ) {
pppol2tp_abort_connect(l2tp);
return;
}
retry_wait = LWIP_MIN(PPPOL2TP_CONTROL_TIMEOUT * l2tp->sccrq_retried, PPPOL2TP_SLOW_RETRY);
PPPDEBUG(LOG_DEBUG, ("pppol2tp: sccrq_retried=%d\n", l2tp->sccrq_retried));
if ((err = pppol2tp_send_sccrq(l2tp)) != 0) {
l2tp->sccrq_retried--;
PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send SCCRQ, error=%d\n", err));
LWIP_UNUSED_ARG(err); /* if PPPDEBUG is disabled */
}
sys_timeout(retry_wait, pppol2tp_timeout, l2tp);
break;
case PPPOL2TP_STATE_ICRQ_SENT:
l2tp->icrq_retried++;
if (l2tp->icrq_retried >= PPPOL2TP_MAXICRQ) {
pppol2tp_abort_connect(l2tp);
return;
}
PPPDEBUG(LOG_DEBUG, ("pppol2tp: icrq_retried=%d\n", l2tp->icrq_retried));
if (l2tp->peer_nr <= l2tp->our_ns -1) { /* the SCCCN was not acknowledged */
if ((err = pppol2tp_send_scccn(l2tp, l2tp->our_ns -1)) != 0) {
l2tp->icrq_retried--;
PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send SCCCN, error=%d\n", err));
LWIP_UNUSED_ARG(err); /* if PPPDEBUG is disabled */
sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
break;
}
}
if ((err = pppol2tp_send_icrq(l2tp, l2tp->our_ns)) != 0) {
l2tp->icrq_retried--;
PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send ICRQ, error=%d\n", err));
LWIP_UNUSED_ARG(err); /* if PPPDEBUG is disabled */
}
sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
break;
case PPPOL2TP_STATE_ICCN_SENT:
l2tp->iccn_retried++;
if (l2tp->iccn_retried >= PPPOL2TP_MAXICCN) {
pppol2tp_abort_connect(l2tp);
return;
}
PPPDEBUG(LOG_DEBUG, ("pppol2tp: iccn_retried=%d\n", l2tp->iccn_retried));
if ((err = pppol2tp_send_iccn(l2tp, l2tp->our_ns)) != 0) {
l2tp->iccn_retried--;
PPPDEBUG(LOG_DEBUG, ("pppol2tp: failed to send ICCN, error=%d\n", err));
LWIP_UNUSED_ARG(err); /* if PPPDEBUG is disabled */
}
sys_timeout(PPPOL2TP_CONTROL_TIMEOUT, pppol2tp_timeout, l2tp);
break;
default:
return; /* all done, work in peace */
}
}
/* Connection attempt aborted */
static void pppol2tp_abort_connect(pppol2tp_pcb *l2tp) {
PPPDEBUG(LOG_DEBUG, ("pppol2tp: could not establish connection\n"));
l2tp->phase = PPPOL2TP_STATE_INITIAL;
ppp_link_failed(l2tp->ppp); /* notify upper layers */
}
/* Initiate a new tunnel */
static err_t pppol2tp_send_sccrq(pppol2tp_pcb *l2tp) {
struct pbuf *pb;
u8_t *p;
u16_t len;
/* calculate UDP packet length */
len = 12 +8 +8 +10 +10 +6+sizeof(PPPOL2TP_HOSTNAME)-1 +6+sizeof(PPPOL2TP_VENDORNAME)-1 +8 +8;
#if PPPOL2TP_AUTH_SUPPORT
if (l2tp->secret != NULL) {
len += 6 + sizeof(l2tp->secret_rv);
}
#endif /* PPPOL2TP_AUTH_SUPPORT */
/* allocate a buffer */
pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
if (pb == NULL) {
return ERR_MEM;
}
LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
p = (u8_t*)pb->payload;
/* fill in pkt */
/* L2TP control header */
PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
PUTSHORT(len, p); /* Length */
PUTSHORT(0, p); /* Tunnel Id */
PUTSHORT(0, p); /* Session Id */
PUTSHORT(0, p); /* NS Sequence number - to peer */
PUTSHORT(0, p); /* NR Sequence number - expected for peer */
/* AVP - Message type */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_MESSAGE, p); /* Attribute type: Message Type */
PUTSHORT(PPPOL2TP_MESSAGETYPE_SCCRQ, p); /* Attribute value: Message type: SCCRQ */
/* AVP - L2TP Version */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_VERSION, p); /* Attribute type: Version */
PUTSHORT(PPPOL2TP_VERSION, p); /* Attribute value: L2TP Version */
/* AVP - Framing capabilities */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 10, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_FRAMINGCAPABILITIES, p); /* Attribute type: Framing capabilities */
PUTLONG(PPPOL2TP_FRAMINGCAPABILITIES, p); /* Attribute value: Framing capabilities */
/* AVP - Bearer capabilities */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 10, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_BEARERCAPABILITIES, p); /* Attribute type: Bearer capabilities */
PUTLONG(PPPOL2TP_BEARERCAPABILITIES, p); /* Attribute value: Bearer capabilities */
/* AVP - Host name */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 6+sizeof(PPPOL2TP_HOSTNAME)-1, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_HOSTNAME, p); /* Attribute type: Hostname */
MEMCPY(p, PPPOL2TP_HOSTNAME, sizeof(PPPOL2TP_HOSTNAME)-1); /* Attribute value: Hostname */
INCPTR(sizeof(PPPOL2TP_HOSTNAME)-1, p);
/* AVP - Vendor name */
PUTSHORT(6+sizeof(PPPOL2TP_VENDORNAME)-1, p); /* len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_VENDORNAME, p); /* Attribute type: Vendor name */
MEMCPY(p, PPPOL2TP_VENDORNAME, sizeof(PPPOL2TP_VENDORNAME)-1); /* Attribute value: Vendor name */
INCPTR(sizeof(PPPOL2TP_VENDORNAME)-1, p);
/* AVP - Assign tunnel ID */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_TUNNELID, p); /* Attribute type: Tunnel ID */
PUTSHORT(l2tp->remote_tunnel_id, p); /* Attribute value: Tunnel ID */
/* AVP - Receive window size */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_RECEIVEWINDOWSIZE, p); /* Attribute type: Receive window size */
PUTSHORT(PPPOL2TP_RECEIVEWINDOWSIZE, p); /* Attribute value: Receive window size */
#if PPPOL2TP_AUTH_SUPPORT
/* AVP - Challenge */
if (l2tp->secret != NULL) {
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 6 + sizeof(l2tp->secret_rv), p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_CHALLENGE, p); /* Attribute type: Challenge */
MEMCPY(p, l2tp->secret_rv, sizeof(l2tp->secret_rv)); /* Attribute value: Random vector */
INCPTR(sizeof(l2tp->secret_rv), p);
}
#endif /* PPPOL2TP_AUTH_SUPPORT */
return pppol2tp_udp_send(l2tp, pb);
}
/* Complete tunnel establishment */
static err_t pppol2tp_send_scccn(pppol2tp_pcb *l2tp, u16_t ns) {
struct pbuf *pb;
u8_t *p;
u16_t len;
/* calculate UDP packet length */
len = 12 +8;
#if PPPOL2TP_AUTH_SUPPORT
if (l2tp->send_challenge) {
len += 6 + sizeof(l2tp->challenge_hash);
}
#endif /* PPPOL2TP_AUTH_SUPPORT */
/* allocate a buffer */
pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
if (pb == NULL) {
return ERR_MEM;
}
LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
p = (u8_t*)pb->payload;
/* fill in pkt */
/* L2TP control header */
PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
PUTSHORT(len, p); /* Length */
PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
PUTSHORT(0, p); /* Session Id */
PUTSHORT(ns, p); /* NS Sequence number - to peer */
PUTSHORT(l2tp->peer_ns+1, p); /* NR Sequence number - expected for peer */
/* AVP - Message type */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_MESSAGE, p); /* Attribute type: Message Type */
PUTSHORT(PPPOL2TP_MESSAGETYPE_SCCCN, p); /* Attribute value: Message type: SCCCN */
#if PPPOL2TP_AUTH_SUPPORT
/* AVP - Challenge response */
if (l2tp->send_challenge) {
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 6 + sizeof(l2tp->challenge_hash), p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_CHALLENGERESPONSE, p); /* Attribute type: Challenge response */
MEMCPY(p, l2tp->challenge_hash, sizeof(l2tp->challenge_hash)); /* Attribute value: Computed challenge */
INCPTR(sizeof(l2tp->challenge_hash), p);
}
#endif /* PPPOL2TP_AUTH_SUPPORT */
return pppol2tp_udp_send(l2tp, pb);
}
/* Initiate a new session */
static err_t pppol2tp_send_icrq(pppol2tp_pcb *l2tp, u16_t ns) {
struct pbuf *pb;
u8_t *p;
u16_t len;
u32_t serialnumber;
/* calculate UDP packet length */
len = 12 +8 +8 +10;
/* allocate a buffer */
pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
if (pb == NULL) {
return ERR_MEM;
}
LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
p = (u8_t*)pb->payload;
/* fill in pkt */
/* L2TP control header */
PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
PUTSHORT(len, p); /* Length */
PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
PUTSHORT(0, p); /* Session Id */
PUTSHORT(ns, p); /* NS Sequence number - to peer */
PUTSHORT(l2tp->peer_ns+1, p); /* NR Sequence number - expected for peer */
/* AVP - Message type */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_MESSAGE, p); /* Attribute type: Message Type */
PUTSHORT(PPPOL2TP_MESSAGETYPE_ICRQ, p); /* Attribute value: Message type: ICRQ */
/* AVP - Assign session ID */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_SESSIONID, p); /* Attribute type: Session ID */
PUTSHORT(l2tp->remote_session_id, p); /* Attribute value: Session ID */
/* AVP - Call Serial Number */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 10, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_CALLSERIALNUMBER, p); /* Attribute type: Serial number */
serialnumber = magic();
PUTLONG(serialnumber, p); /* Attribute value: Serial number */
return pppol2tp_udp_send(l2tp, pb);
}
/* Complete tunnel establishment */
static err_t pppol2tp_send_iccn(pppol2tp_pcb *l2tp, u16_t ns) {
struct pbuf *pb;
u8_t *p;
u16_t len;
/* calculate UDP packet length */
len = 12 +8 +10 +10;
/* allocate a buffer */
pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
if (pb == NULL) {
return ERR_MEM;
}
LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
p = (u8_t*)pb->payload;
/* fill in pkt */
/* L2TP control header */
PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
PUTSHORT(len, p); /* Length */
PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
PUTSHORT(l2tp->source_session_id, p); /* Session Id */
PUTSHORT(ns, p); /* NS Sequence number - to peer */
PUTSHORT(l2tp->peer_ns+1, p); /* NR Sequence number - expected for peer */
/* AVP - Message type */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_MESSAGE, p); /* Attribute type: Message Type */
PUTSHORT(PPPOL2TP_MESSAGETYPE_ICCN, p); /* Attribute value: Message type: ICCN */
/* AVP - Framing type */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 10, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_FRAMINGTYPE, p); /* Attribute type: Framing type */
PUTLONG(PPPOL2TP_FRAMINGTYPE, p); /* Attribute value: Framing type */
/* AVP - TX Connect speed */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 10, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_TXCONNECTSPEED, p); /* Attribute type: TX Connect speed */
PUTLONG(PPPOL2TP_TXCONNECTSPEED, p); /* Attribute value: TX Connect speed */
return pppol2tp_udp_send(l2tp, pb);
}
/* Send a ZLB ACK packet */
static err_t pppol2tp_send_zlb(pppol2tp_pcb *l2tp, u16_t ns) {
struct pbuf *pb;
u8_t *p;
u16_t len;
/* calculate UDP packet length */
len = 12;
/* allocate a buffer */
pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
if (pb == NULL) {
return ERR_MEM;
}
LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
p = (u8_t*)pb->payload;
/* fill in pkt */
/* L2TP control header */
PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
PUTSHORT(len, p); /* Length */
PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
PUTSHORT(0, p); /* Session Id */
PUTSHORT(ns, p); /* NS Sequence number - to peer */
PUTSHORT(l2tp->peer_ns+1, p); /* NR Sequence number - expected for peer */
return pppol2tp_udp_send(l2tp, pb);
}
/* Send a StopCCN packet */
static err_t pppol2tp_send_stopccn(pppol2tp_pcb *l2tp, u16_t ns) {
struct pbuf *pb;
u8_t *p;
u16_t len;
/* calculate UDP packet length */
len = 12 +8 +8 +8;
/* allocate a buffer */
pb = pbuf_alloc(PBUF_TRANSPORT, len, PBUF_RAM);
if (pb == NULL) {
return ERR_MEM;
}
LWIP_ASSERT("pb->tot_len == pb->len", pb->tot_len == pb->len);
p = (u8_t*)pb->payload;
/* fill in pkt */
/* L2TP control header */
PUTSHORT(PPPOL2TP_HEADERFLAG_CONTROL_MANDATORY, p);
PUTSHORT(len, p); /* Length */
PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
PUTSHORT(0, p); /* Session Id */
PUTSHORT(ns, p); /* NS Sequence number - to peer */
PUTSHORT(l2tp->peer_ns+1, p); /* NR Sequence number - expected for peer */
/* AVP - Message type */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_MESSAGE, p); /* Attribute type: Message Type */
PUTSHORT(PPPOL2TP_MESSAGETYPE_STOPCCN, p); /* Attribute value: Message type: StopCCN */
/* AVP - Assign tunnel ID */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_TUNNELID, p); /* Attribute type: Tunnel ID */
PUTSHORT(l2tp->remote_tunnel_id, p); /* Attribute value: Tunnel ID */
/* AVP - Result code */
PUTSHORT(PPPOL2TP_AVPHEADERFLAG_MANDATORY + 8, p); /* Mandatory flag + len field */
PUTSHORT(0, p); /* Vendor ID */
PUTSHORT(PPPOL2TP_AVPTYPE_RESULTCODE, p); /* Attribute type: Result code */
PUTSHORT(PPPOL2TP_RESULTCODE, p); /* Attribute value: Result code */
return pppol2tp_udp_send(l2tp, pb);
}
static err_t pppol2tp_xmit(pppol2tp_pcb *l2tp, struct pbuf *pb) {
u8_t *p;
/* make room for L2TP header - should not fail */
if (pbuf_add_header(pb, PPPOL2TP_OUTPUT_DATA_HEADER_LEN) != 0) {
/* bail out */
PPPDEBUG(LOG_ERR, ("pppol2tp: pppol2tp_pcb: could not allocate room for L2TP header\n"));
LINK_STATS_INC(link.lenerr);
pbuf_free(pb);
return ERR_BUF;
}
p = (u8_t*)pb->payload;
PUTSHORT(PPPOL2TP_HEADERFLAG_DATA_MANDATORY, p);
PUTSHORT(l2tp->source_tunnel_id, p); /* Tunnel Id */
PUTSHORT(l2tp->source_session_id, p); /* Session Id */
return pppol2tp_udp_send(l2tp, pb);
}
static err_t pppol2tp_udp_send(pppol2tp_pcb *l2tp, struct pbuf *pb) {
err_t err;
if (l2tp->netif) {
err = udp_sendto_if(l2tp->udp, pb, &l2tp->remote_ip, l2tp->tunnel_port, l2tp->netif);
} else {
err = udp_sendto(l2tp->udp, pb, &l2tp->remote_ip, l2tp->tunnel_port);
}
pbuf_free(pb);
return err;
}
#endif /* PPP_SUPPORT && PPPOL2TP_SUPPORT */