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l2tpns/l2tplac.c
fendo 4df24fd868 first version of the LAC functionality
2012-11-28 23:43:33 +01:00

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/*
* Add functionality "LAC" to l2tpns.
* Used to forward a ppp session to another "LNS".
*/
#include <errno.h>
#include <string.h>
#include "md5.h"
#include "l2tpns.h"
#include "util.h"
#include "l2tplac.h"
/* sequence diagram: Client <--> LAC <--> LNS1 <--> LNS2
*
* LCP Negotiation
* Client <-------------------> LAC
* Challenge (CHAP/PAP)
* Client <-------------------> LAC
* SCCRQ
* LAC --------------------> LNS1 (Tunnel Open)
* SCCRP
* LAC <-------------------- LNS1 (Tunnel Open)
* SCCCN
* LAC --------------------> LNS1 (Tunnel Open)
* ZLB
* LAC <-------------------- LNS1 (Tunnel Open)
* ICRQ
* LAC --------------------> LNS1 (Session Open)
* ICRP
* LAC <-------------------- LNS1 (Session Open)
* ICCN
* LAC --------------------> LNS1 (Session Open)
* ZLB
* LAC <-------------------- LNS1 (Session Open)
* LCP Negotiation
* Client <---------------------------------------------> LNS1
* Challenge (CHAP/PAP)
* Client <---------------------------------------------> LNS1
* SCCRQ
* LNS1 --------------------> LNS2 (Tunnel Open)
* SCCRP
* LNS1 <-------------------- LNS2 (Tunnel Open)
* SCCCN
* LNS1 --------------------> LNS2 (Tunnel Open)
* ZLB
* LNS1 <-------------------- LNS2 (Tunnel Open)
* ICRQ
* LNS1 --------------------> LNS2 (Session Open)
* ICRP
* LNS1 <-------------------- LNS2 (Session Open)
* ICCN
* LNS1 --------------------> LNS2 (Session Open)
* ZLB
* LNS1 <-------------------- LNS2 (Session Open)
* LCP Negotiation
* Client <------------------------------------------------------------------------> LNS2
* PAP/CHAP Authentification
* Client <------------------------------------------------------------------------> LNS2
* DATA (ppp)
* Client <------------------------------------------------------------------------> LNS2
* */
// Limits
#define MAXRLNSTUNNEL 101
typedef uint16_t confrlnsidt;
/*
* Possible configrlns states
* TUNNELFREE -> TUNNELOPEN -> TUNNELDIE -> TUNNELFREE
*/
enum
{
CONFRLNSFREE = 0, // Not in use
CONFRLNSSET // Config Set
};
// struct remote lns
typedef struct
{
tunnelidt tid; // near end tunnel ID
int state; // conf state (tunnelstate enum)
in_addr_t ip; // Ip for far end
uint16_t port; // port for far end
hasht auth; // request authenticator
char strmaskuser[MAXUSER];
char l2tp_secret[64]; // L2TP shared secret
}
configrlns;
configrlns *pconfigrlns = NULL; // Array of tunnel structures.
// Init data structures
void initremotelnsdata()
{
confrlnsidt i;
if ( !(pconfigrlns = shared_malloc(sizeof(pconfigrlns[0]) * MAXRLNSTUNNEL)) )
{
LOG(0, 0, 0, "Error doing malloc for tunnels lac: %s\n", strerror(errno));
exit(1);
}
memset(pconfigrlns, 0, sizeof(pconfigrlns[0]) * MAXRLNSTUNNEL);
// Mark all the tunnels as undefined (waiting to be filled in by a download).
for (i = 1; i < MAXRLNSTUNNEL; i++)
pconfigrlns[i].state = CONFRLNSFREE; // mark it as not filled in.
config->highest_rlnsid = 0;
}
// Check if must be forwarded to another LNS
int forwardtolns(sessionidt s, char * puser)
{
tunnelidt t;
confrlnsidt i;
for (i = 1; i <= config->highest_rlnsid ; ++i)
{
if ( NULL != strstr(puser, pconfigrlns[i].strmaskuser))
{
t = pconfigrlns[i].tid;
if ((t != 0) && (tunnel[t].ip != pconfigrlns[i].ip))
{
pconfigrlns[i].tid = t = 0;
LOG(1, 0, t, "Tunnel ID inconsistency\n");
}
if (t == 0)
{
if (main_quit == QUIT_SHUTDOWN) return 0;
// Start Open Tunnel
if (!(t = lac_new_tunnel()))
{
LOG(1, 0, 0, "No more tunnels\n");
STAT(tunnel_overflow);
return 0;
}
lac_tunnelclear(t);
tunnel[t].ip = pconfigrlns[i].ip;
tunnel[t].port = pconfigrlns[i].port;
tunnel[t].window = 4; // default window
STAT(tunnel_created);
LOG(1, 0, t, "New (REMOTE LNS) tunnel to %s:%u ID %u\n", fmtaddr(htonl(tunnel[t].ip), 0), tunnel[t].port, t);
random_data(pconfigrlns[i].auth, sizeof(pconfigrlns[i].auth));
pconfigrlns[i].tid = t;
lac_send_SCCRQ(t, pconfigrlns[i].auth, sizeof(pconfigrlns[i].auth));
}
else if (tunnel[t].state == TUNNELOPEN)
{
if (main_quit != QUIT_SHUTDOWN)
{
/**********************/
/** Open New session **/
/**********************/
sessionidt new_sess = sessionfree;
sessionfree = session[new_sess].next;
memset(&session[new_sess], 0, sizeof(session[new_sess]));
if (new_sess > config->cluster_highest_sessionid)
config->cluster_highest_sessionid = new_sess;
session[new_sess].opened = time_now;
session[new_sess].tunnel = t;
session[new_sess].last_packet = session[s].last_data = time_now;
session[new_sess].ppp.phase = Establish;
session[new_sess].ppp.lcp = Starting;
// Sent ICRQ Incoming-call-request
lac_send_ICRQ(t, new_sess);
// Set session to forward to another LNS
session[s].forwardtosession = new_sess;
session[new_sess].forwardtosession = s;
STAT(session_created);
}
else
{
lac_tunnelshutdown(t, "Shutting down", 6, 0, 0);
pconfigrlns[i].tid = 0;
}
}
else
{
/** TODO **/
LOG(1, 0, t, "(REMOTE LNS) tunnel is not open\n");
}
return 1;
}
}
return 0;
}
static tunnelidt getidrlns(tunnelidt t)
{
confrlnsidt idrlns;
for (idrlns = 1; idrlns <= config->highest_rlnsid ; ++idrlns)
{
if (pconfigrlns[idrlns].tid == t) return idrlns;
}
return 0;
}
int istunneltolns(tunnelidt t)
{
confrlnsidt idrlns;
for (idrlns = 1; idrlns <= config->highest_rlnsid ; ++idrlns)
{
if (pconfigrlns[idrlns].tid == t) return 1;
}
return 0;
}
void calc_lac_auth(tunnelidt t, uint8_t id, uint8_t *out)
{
MD5_CTX ctx;
confrlnsidt idrlns;
idrlns = getidrlns(t);
MD5_Init(&ctx);
MD5_Update(&ctx, &id, 1);
MD5_Update(&ctx, pconfigrlns[idrlns].l2tp_secret, strlen(pconfigrlns[idrlns].l2tp_secret));
MD5_Update(&ctx, pconfigrlns[idrlns].auth, 16);
MD5_Final(out, &ctx);
}
// Forward session to external LNS
int session_forward_tolns(uint8_t *buf, int len, sessionidt sess, uint16_t proto)
{
uint16_t t = 0, s = 0;
uint8_t *p = buf + 2; // First word L2TP options
s = session[sess].forwardtosession;
if (session[s].forwardtosession != sess)
{
LOG(0, sess, session[sess].tunnel, "Link Session (%u) broken\n", s);
return 0;
}
t = session[s].tunnel;
if (t >= MAXTUNNEL)
{
LOG(1, s, t, "Session with invalid tunnel ID\n");
return 0;
}
if (*buf & 0x40)
{ // length
p += 2;
}
*(uint16_t *) p = htons(tunnel[t].far); // tunnel
p += 2;
*(uint16_t *) p = htons(session[s].far); // session
p += 2;
if (*buf & 0x08)
{ // ns/nr
*(uint16_t *) p = htons(tunnel[t].ns); // sequence
p += 2;
*(uint16_t *) p = htons(tunnel[t].nr); // sequence
p += 2;
}
if ((proto == PPPIP) || (proto == PPPMP) ||(proto == PPPIPV6 && config->ipv6_prefix.s6_addr[0]))
{
session[sess].last_packet = session[sess].last_data = time_now;
}
else
session[sess].last_packet = time_now;
tunnelsend(buf, len, t); // send it...
return 1;
}
int addremotelns(char *mask, char *IP_RemoteLNS, char *Port_RemoteLNS, char *SecretRemoteLNS)
{
confrlnsidt idrlns;
for (idrlns = 1; idrlns < MAXRLNSTUNNEL; ++idrlns)
{
if (pconfigrlns[idrlns].state == CONFRLNSFREE)
{
snprintf((char *) pconfigrlns[idrlns].strmaskuser, sizeof(pconfigrlns[idrlns].strmaskuser), "%s", mask);
pconfigrlns[idrlns].ip = ntohl(inet_addr(IP_RemoteLNS));
pconfigrlns[idrlns].port = atoi(Port_RemoteLNS);
snprintf((char *) pconfigrlns[idrlns].l2tp_secret, sizeof(pconfigrlns[idrlns].l2tp_secret), "%s", SecretRemoteLNS);
config->highest_rlnsid = idrlns;
pconfigrlns[idrlns].state = CONFRLNSSET;
LOG(1, 0, 0, "New Remote LNS conf (count %u) mask:%s IP:%s Port:%u l2tpsecret:*****\n", idrlns,
pconfigrlns[idrlns].strmaskuser, fmtaddr(htonl(pconfigrlns[idrlns].ip), 0),
pconfigrlns[idrlns].port);
return 1;
}
}
LOG(0, 0, 0, "No more Remote LNS Conf Free\n");
return 0;
}
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