l2tpns/l2tplac.c
2012-12-09 18:50:07 +01:00

623 lines
19 KiB
C

/*
* 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
* */
typedef struct
{
uint32_t tunnel_type;
uint32_t tunnel_medium_type;
in_addr_t tunnel_server_endpoint; /* IP remote LNS */
char tunnel_password[64]; /* l2tpsecret remote LNS */
char tunnel_assignment_id[256];
} tunnelrlnst;
// Max Radius Tunnels by remote LNS
#define MAXTAGTUNNEL 0x20
static tunnelrlnst ptunnelrlns[MAXTAGTUNNEL];
/*
* Possible configrlns states
* CONFRLNSFREE -> CONFRLNSSET -> CONFRLNSFREE
*/
enum
{
CONFRLNSFREE = 0, // Not in use
CONFRLNSSET, // Config Set
CONFRLNSSETBYRADIUS // Config Set
};
// struct remote lns
typedef struct
{
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
char tunnel_assignment_id[256];
}
configrlns;
configrlns *pconfigrlns = NULL;
// Init data structures
void lac_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 conf as free.
for (i = 1; i < MAXRLNSTUNNEL; i++)
pconfigrlns[i].state = CONFRLNSFREE; // mark it as not filled in.
config->highest_rlnsid = 0;
lac_reset_rad_tag_tunnel_ctxt();
}
// Reset Radius TAG tunnel context
void lac_reset_rad_tag_tunnel_ctxt()
{
memset(ptunnelrlns, 0, sizeof(ptunnelrlns[0]) * MAXTAGTUNNEL);
}
// Add tunnel_type radius TAG tunnel to context
void lac_set_rad_tag_tunnel_type(uint8_t tag, uint32_t tunnel_type)
{
if (tag < MAXTAGTUNNEL)
ptunnelrlns[tag].tunnel_type = tunnel_type;
}
// Add tunnel_medium_type Radius TAG tunnel to context
void lac_set_rad_tag_tunnel_medium_type(uint8_t tag, uint32_t tunnel_medium_type)
{
if (tag < MAXTAGTUNNEL)
ptunnelrlns[tag].tunnel_medium_type = tunnel_medium_type;
}
// Add tunnel_server_endpoint Radius TAG tunnel to context
void lac_set_rad_tag_tunnel_serv_endpt(uint8_t tag, char *tunnel_server_endpoint)
{
if (tag < MAXTAGTUNNEL)
{
ptunnelrlns[tag].tunnel_server_endpoint = ntohl(inet_addr(tunnel_server_endpoint));
}
}
// Add tunnel_password Radius TAG tunnel to context
void lac_set_rad_tag_tunnel_password(uint8_t tag, char *tunnel_password)
{
if ((tag < MAXTAGTUNNEL) && (strlen(tunnel_password) < 64))
{
strcpy(ptunnelrlns[tag].tunnel_password, tunnel_password);
}
}
// Add tunnel_assignment_id Radius TAG tunnel to context
void lac_set_rad_tag_tunnel_assignment_id(uint8_t tag, char *tunnel_assignment_id)
{
if ((tag < MAXTAGTUNNEL) && (strlen(tunnel_assignment_id) < 256))
{
strcpy(ptunnelrlns[tag].tunnel_assignment_id, tunnel_assignment_id);
}
}
// Select a tunnel_assignment_id
int lac_rad_select_assignment_id(sessionidt s, char *assignment_id)
{
int idtag;
int nbtagfound = 0;
int bufidtag[MAXTAGTUNNEL];
for (idtag = 0; idtag < MAXTAGTUNNEL; ++idtag)
{
if (ptunnelrlns[idtag].tunnel_type == 0)
continue;
else if (ptunnelrlns[idtag].tunnel_type != 3) // 3 == L2TP tunnel type
LOG(1, s, session[s].tunnel, "Error, Only L2TP tunnel type supported\n");
else if (ptunnelrlns[idtag].tunnel_medium_type != 1)
LOG(1, s, session[s].tunnel, "Error, Only IP tunnel medium type supported\n");
else if (ptunnelrlns[idtag].tunnel_server_endpoint == 0)
LOG(1, s, session[s].tunnel, "Error, Bad IP tunnel server endpoint \n");
else if (strlen(ptunnelrlns[idtag].tunnel_assignment_id) > 0)
{
bufidtag[nbtagfound] = idtag;
nbtagfound++;
}
}
if (nbtagfound > 0)
{
// random between 0 and nbtagfound-1
idtag = (rand() % nbtagfound);
if (idtag >= nbtagfound)
idtag = 0; //Sanity checks.
strcpy(assignment_id, ptunnelrlns[bufidtag[idtag]].tunnel_assignment_id);
return 1;
}
// Error no tunnel_assignment_id found
return 0;
}
// Save the 'radius tag tunnels' context on global configuration
void lac_save_rad_tag_tunnels(sessionidt s)
{
confrlnsidt idrlns;
int idtag;
for (idtag = 0; idtag < MAXTAGTUNNEL; ++idtag)
{
if (ptunnelrlns[idtag].tunnel_type == 0)
continue;
else if (ptunnelrlns[idtag].tunnel_type != 3) // 3 == L2TP tunnel type
LOG(1, s, session[s].tunnel, "Error, Only L2TP tunnel type supported\n");
else if (ptunnelrlns[idtag].tunnel_medium_type != 1)
LOG(1, s, session[s].tunnel, "Error, Only IP tunnel medium type supported\n");
else if (ptunnelrlns[idtag].tunnel_server_endpoint == 0)
LOG(1, s, session[s].tunnel, "Error, Bad IP tunnel server endpoint \n");
else if (strlen(ptunnelrlns[idtag].tunnel_assignment_id) <= 0)
LOG(1, s, session[s].tunnel, "Error, No tunnel_assignment_id \n");
else if (ptunnelrlns[idtag].tunnel_server_endpoint == ntohl(config->bind_address))
LOG(0, s, session[s].tunnel, "Error, IP Remote LNS == IP local bind address (%s) !!!\n", fmtaddr(config->bind_address, 0));
else
{
for (idrlns = 1; idrlns < MAXRLNSTUNNEL; ++idrlns)
{
if (pconfigrlns[idrlns].state == CONFRLNSFREE)
{
pconfigrlns[idrlns].ip = ptunnelrlns[idtag].tunnel_server_endpoint;
pconfigrlns[idrlns].port = L2TPPORT; //Default L2TP poart
strcpy(pconfigrlns[idrlns].l2tp_secret, ptunnelrlns[idtag].tunnel_password);
strcpy(pconfigrlns[idrlns].tunnel_assignment_id, ptunnelrlns[idtag].tunnel_assignment_id);
config->highest_rlnsid = idrlns;
pconfigrlns[idrlns].state = CONFRLNSSETBYRADIUS;
break;
}
else if (pconfigrlns[idrlns].state == CONFRLNSSETBYRADIUS)
{
if ( (pconfigrlns[idrlns].ip == ptunnelrlns[idtag].tunnel_server_endpoint) &&
(strcmp(pconfigrlns[idrlns].tunnel_assignment_id, ptunnelrlns[idtag].tunnel_assignment_id) == 0) )
{
// l2tp_secret may be changed
strcpy(pconfigrlns[idrlns].l2tp_secret, ptunnelrlns[idtag].tunnel_password);
pconfigrlns[idrlns].port = L2TPPORT; //Default L2TP poart
if (config->highest_rlnsid < idrlns) config->highest_rlnsid = idrlns;
break;
}
}
}
if (idrlns >= MAXRLNSTUNNEL)
{
LOG(0, s, session[s].tunnel, "No more Remote LNS Conf Free\n");
return;
}
}
}
}
// Create Remote LNS a Tunnel or Session
static int lac_create_tunnelsession(tunnelidt t, sessionidt s, confrlnsidt i_conf, char * puser)
{
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_conf].ip;
tunnel[t].port = pconfigrlns[i_conf].port;
tunnel[t].window = 4; // default window
tunnel[t].isremotelns = i_conf;
STAT(tunnel_created);
random_data(pconfigrlns[i_conf].auth, sizeof(pconfigrlns[i_conf].auth));
LOG(2, 0, t, "Create New tunnel to REMOTE LNS %s for user %s\n", fmtaddr(htonl(tunnel[t].ip), 0), puser);
lac_send_SCCRQ(t, pconfigrlns[i_conf].auth, sizeof(pconfigrlns[i_conf].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;
session[s].ppp.phase = Establish;
LOG(2, 0, t, "Open New session to REMOTE LNS %s for user: %s\n", fmtaddr(htonl(tunnel[t].ip), 0), puser);
// 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;
strncpy(session[s].user, puser, sizeof(session[s].user) - 1);
strncpy(session[new_sess].user, puser, sizeof(session[new_sess].user) - 1);
STAT(session_created);
}
else
{
lac_tunnelshutdown(t, "Shutting down", 6, 0, 0);
}
}
else
{
/** TODO **/
LOG(1, 0, t, "(REMOTE LNS) tunnel is not open\n");
}
return 1;
}
// Check if session must be forwarded to another LNS
// return 1 if the session must be forwarded (and Creating a tunnel/session has been started)
// else 0.
// Note: check from the configuration read on the startup-config (see setforward)
int lac_conf_forwardtoremotelns(sessionidt s, char * puser)
{
tunnelidt t, j;
confrlnsidt i;
for (i = 1; i <= config->highest_rlnsid ; ++i)
{
if ( (pconfigrlns[i].state == CONFRLNSSET) && (NULL != strstr(puser, pconfigrlns[i].strmaskuser)) )
{
t = 0;
for (j = 0; j <= config->cluster_highest_tunnelid ; ++j)
{
if ((tunnel[j].isremotelns) &&
(tunnel[j].ip == pconfigrlns[i].ip) &&
(tunnel[j].port == pconfigrlns[i].port) &&
(tunnel[j].state != TUNNELDIE))
{
t = j;
if (tunnel[t].isremotelns != i)
{
if ( (tunnel[t].state == TUNNELOPEN) || (tunnel[t].state == TUNNELOPENING) )
{
LOG(1, 0, t, "Tunnel Remote LNS ID inconsistency (IP RLNS:%s)\n",
fmtaddr(htonl(pconfigrlns[i].ip), 0));
tunnel[t].isremotelns = i;
}
else t = 0;
}
break;
}
}
return lac_create_tunnelsession(t, s, i, puser);
}
}
return 0;
}
// return 1 if the session must be forwarded (and Creating a tunnel/session has been started)
// else 0.
// Note: Started from a radius response
int lac_rad_forwardtoremotelns(sessionidt s, char *assignment_id, char * puser)
{
tunnelidt t, j;
confrlnsidt i;
for (i = 1; i <= config->highest_rlnsid ; ++i)
{
if ((pconfigrlns[i].state == CONFRLNSSETBYRADIUS) &&
(strcmp(pconfigrlns[i].tunnel_assignment_id, assignment_id) == 0))
{
t = 0;
for (j = 1; j <= config->cluster_highest_tunnelid ; ++j)
{
if ((tunnel[j].isremotelns == i) &&
(tunnel[j].ip == pconfigrlns[i].ip) &&
(tunnel[j].port == pconfigrlns[i].port) &&
(tunnel[j].state != TUNNELDIE))
{
if ( (tunnel[j].state == TUNNELOPEN) ||
(tunnel[j].state == TUNNELOPENING) )
{
t = j;
LOG(3, 0, t, "Tunnel Remote LNS already open(ing) (RLNS IP:%s)\n", fmtaddr(htonl(pconfigrlns[i].ip), 0));
break;
}
}
}
return lac_create_tunnelsession(t, s, i, puser);
}
}
return 0;
}
// Calcul the remote LNS auth
void lac_calc_rlns_auth(tunnelidt t, uint8_t id, uint8_t *out)
{
MD5_CTX ctx;
confrlnsidt idrlns;
idrlns = tunnel[t].isremotelns;
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 LAC or Remote LNS
int lac_session_forward(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 ((!tunnel[t].isremotelns) && (!tunnel[session[sess].tunnel].isremotelns))
{
LOG(0, sess, session[sess].tunnel, "Link Tunnel Session (%u) broken\n", s);
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;
// Update STAT IN
increment_counter(&session[sess].cin, &session[sess].cin_wrap, len);
session[sess].cin_delta += len;
session[sess].pin++;
sess_local[sess].cin += len;
sess_local[sess].pin++;
session[s].last_data = time_now;
// Update STAT OUT
increment_counter(&session[s].cout, &session[s].cout_wrap, len); // byte count
session[s].cout_delta += len;
session[s].pout++;
sess_local[s].cout += len;
sess_local[s].pout++;
}
else
session[sess].last_packet = time_now;
tunnelsend(buf, len, t); // send it...
return 1;
}
// Add new Remote LNS from CLI
// return:
// 0 = Error
// 1 = New Remote LNS conf ADD
// 2 = Remote LNS Conf Updated
int lac_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;
return 1;
}
else if ((pconfigrlns[idrlns].state == CONFRLNSSET) && (strcmp(pconfigrlns[idrlns].strmaskuser, mask) == 0))
{
if ( (pconfigrlns[idrlns].ip != ntohl(inet_addr(IP_RemoteLNS))) ||
(pconfigrlns[idrlns].port != atoi(Port_RemoteLNS)) ||
(strcmp(pconfigrlns[idrlns].l2tp_secret, SecretRemoteLNS) != 0) )
{
memset(&pconfigrlns[idrlns], 0, sizeof(pconfigrlns[idrlns]));
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);
if (config->highest_rlnsid < idrlns) config->highest_rlnsid = idrlns;
pconfigrlns[idrlns].state = CONFRLNSSET;
// Conf Updated, the tunnel must be dropped
return 2;
}
return 1;
}
}
LOG(0, 0, 0, "No more Remote LNS Conf Free\n");
return 0;
}
// Cli Show remote LNS defined
int lac_cli_show_remotelns(confrlnsidt idrlns, char *strout)
{
if (idrlns > config->highest_rlnsid)
return 0;
if (idrlns == 0)
// Show Summary
sprintf(strout, "%15s %3s %-32s %-32s %11s %7s %10s",
"IP Remote LNS",
"TID",
"l2tp secret",
"assignment Id",
"File/Radius",
"State",
"Count Sess");
else
{
tunnelidt t, tfound = 0;
sessionidt s;
int countsess = 0;
char state[20];
strcpy(state, "Close");
for (t = 0; t <= config->cluster_highest_tunnelid ; ++t)
{
if ((tunnel[t].isremotelns == idrlns) &&
(tunnel[t].ip == pconfigrlns[idrlns].ip) &&
(tunnel[t].port == pconfigrlns[idrlns].port) &&
(tunnel[t].state != TUNNELDIE))
{
if (tunnel[t].state == TUNNELOPENING)
strcpy(state, "Opening");
else if (tunnel[t].state == TUNNELOPEN)
strcpy(state, "Open");
for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
if (session[s].tunnel == t)
countsess++;
tfound = t;
break;
}
}
sprintf(strout, "%15s %3u %-32s %-32s %11s %7s %10u",
fmtaddr(htonl(pconfigrlns[idrlns].ip), 0),
tfound,
pconfigrlns[idrlns].l2tp_secret,
pconfigrlns[idrlns].tunnel_assignment_id,
(pconfigrlns[idrlns].state == CONFRLNSSET?"File":(pconfigrlns[idrlns].state == CONFRLNSSETBYRADIUS?"Radius":"Free")),
state,
countsess);
}
return 1;
}