X-Git-Url: http://git.sameswireless.fr/l2tpns.git/blobdiff_plain/34fb6bc3d4b8980aa1e99326282b2ae528ef56e3..1eca21ec9caadb684fff8fd21e112e64ac3462ee:/l2tpns.c?ds=inline

diff --git a/l2tpns.c b/l2tpns.c
index 72e71b2..000e594 100644
--- a/l2tpns.c
+++ b/l2tpns.c
@@ -4,7 +4,7 @@
 // Copyright (c) 2002 FireBrick (Andrews & Arnold Ltd / Watchfront Ltd) - GPL licenced
 // vim: sw=8 ts=8
 
-char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.77 2005/01/10 07:45:03 bodea Exp $";
+char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.99 2005/05/07 13:12:25 bodea Exp $";
 
 #include <arpa/inet.h>
 #include <assert.h>
@@ -19,6 +19,7 @@ char const *cvs_id_l2tpns = "$Id: l2tpns.c,v 1.77 2005/01/10 07:45:03 bodea Exp
 #include <sys/mman.h>
 #include <netdb.h>
 #include <netinet/in.h>
+#include <netinet/ip6.h>
 #include <stdarg.h>
 #include <stdlib.h>
 #include <stdio.h>
@@ -62,19 +63,24 @@ int clifd = -1;			// Socket listening for CLI connections.
 int snoopfd = -1;		// UDP file handle for sending out intercept data
 int *radfds = NULL;		// RADIUS requests file handles
 int ifrfd = -1;			// File descriptor for routing, etc
+int ifr6fd = -1;		// File descriptor for IPv6 routing, etc
 static int rand_fd = -1;	// Random data source
 time_t basetime = 0;		// base clock
 char hostname[1000] = "";	// us.
-static uint32_t sessionid = 0;	// session id for radius accounting
+static int tunidx;		// ifr_ifindex of tun device
 static int syslog_log = 0;	// are we logging to syslog
-static FILE *log_stream = NULL;	// file handle for direct logging (i.e. direct into file, not via syslog).
+static FILE *log_stream = 0;	// file handle for direct logging (i.e. direct into file, not via syslog).
 extern int cluster_sockfd;	// Intra-cluster communications socket.
-uint32_t last_id = 0;		// Last used PPP SID. Can I kill this?? -- mo
+uint32_t last_id = 0;		// Unique ID for radius accounting
 
 struct cli_session_actions *cli_session_actions = NULL;	// Pending session changes requested by CLI
 struct cli_tunnel_actions *cli_tunnel_actions = NULL;	// Pending tunnel changes required by CLI
 
 static void *ip_hash[256];	// Mapping from IP address to session structures.
+struct ipv6radix {
+	int sess;
+	struct ipv6radix *branch;
+} ipv6_hash[256];		// Mapping from IPv6 address to session structures.
 
 // Traffic counters.
 static uint32_t udp_rx = 0, udp_rx_pkt = 0, udp_tx = 0;
@@ -99,12 +105,12 @@ config_descriptt config_values[] = {
 	CONFIG("l2tp_secret", l2tpsecret, STRING),
 	CONFIG("primary_dns", default_dns1, IPv4),
 	CONFIG("secondary_dns", default_dns2, IPv4),
-	CONFIG("save_state", save_state, BOOL),
 	CONFIG("primary_radius", radiusserver[0], IPv4),
 	CONFIG("secondary_radius", radiusserver[1], IPv4),
 	CONFIG("primary_radius_port", radiusport[0], SHORT),
 	CONFIG("secondary_radius_port", radiusport[1], SHORT),
 	CONFIG("radius_accounting", radius_accounting, BOOL),
+	CONFIG("radius_interim", radius_interim, INT),
 	CONFIG("radius_secret", radiussecret, STRING),
 	CONFIG("radius_authtypes", radius_authtypes_s, STRING),
 	CONFIG("bind_address", bind_address, IPv4),
@@ -125,6 +131,7 @@ config_descriptt config_values[] = {
 	CONFIG("cluster_interface", cluster_interface, STRING),
 	CONFIG("cluster_hb_interval", cluster_hb_interval, INT),
 	CONFIG("cluster_hb_timeout", cluster_hb_timeout, INT),
+	CONFIG("ipv6_prefix", ipv6_prefix, IPv6),
 	{ NULL, 0, 0, 0 },
 };
 
@@ -151,7 +158,7 @@ static sessionidt shut_acct_n = 0;
 
 tunnelt *tunnel = NULL;			// Array of tunnel structures.
 sessiont *session = NULL;		// Array of session structures.
-sessioncountt *sess_count = NULL;	// Array of partial per-session traffic counters.
+sessionlocalt *sess_local = NULL;	// Array of local per-session counters.
 radiust *radius = NULL;			// Array of radius structures.
 ippoolt *ip_address_pool = NULL;	// Array of dynamic IP addresses.
 ip_filtert *ip_filters = NULL;	// Array of named filters.
@@ -163,6 +170,7 @@ struct Tringbuffer *ringbuffer = NULL;
 
 static void cache_ipmap(in_addr_t ip, int s);
 static void uncache_ipmap(in_addr_t ip);
+static void cache_ipv6map(struct in6_addr ip, int prefixlen, int s);
 static void free_ip_address(sessionidt s);
 static void dump_acct_info(int all);
 static void sighup_handler(int sig);
@@ -170,8 +178,6 @@ static void sigalrm_handler(int sig);
 static void sigterm_handler(int sig);
 static void sigquit_handler(int sig);
 static void sigchild_handler(int sig);
-static void read_state(void);
-static void dump_state(void);
 static void build_chap_response(char *challenge, uint8_t id, uint16_t challenge_length, char **challenge_response);
 static void update_config(void);
 static void read_config_file(void);
@@ -181,7 +187,7 @@ static int remove_plugin(char *plugin_name);
 static void plugins_done(void);
 static void processcontrol(uint8_t *buf, int len, struct sockaddr_in *addr, int alen);
 static tunnelidt new_tunnel(void);
-static int unhide_avp(uint8_t *avp, tunnelidt t, sessionidt s, uint16_t length);
+static void unhide_value(uint8_t *value, size_t len, uint16_t type, uint8_t *vector, size_t vec_len);
 
 // return internal time (10ths since process startup)
 static clockt now(void)
@@ -421,11 +427,61 @@ static void routeset(sessionidt s, in_addr_t ip, in_addr_t mask, in_addr_t gw, i
 	}
 }
 
+void route6set(sessionidt s, struct in6_addr ip, int prefixlen, int add)
+{
+	struct in6_rtmsg rt;
+	char ipv6addr[INET6_ADDRSTRLEN];
+
+	if (ifr6fd < 0)
+	{
+		LOG(0, 0, 0, "Asked to set IPv6 route, but IPv6 not setup.\n");
+		return;
+	}
+
+	memset(&rt, 0, sizeof(rt));
+
+	memcpy(&rt.rtmsg_dst, &ip, sizeof(struct in6_addr));
+	rt.rtmsg_dst_len = prefixlen;
+	rt.rtmsg_metric = 1;
+	rt.rtmsg_flags = RTF_UP;
+	rt.rtmsg_ifindex = tunidx;
+
+	LOG(1, 0, 0, "Route %s %s/%d\n",
+	    add ? "add" : "del",
+	    inet_ntop(AF_INET6, &ip, ipv6addr, INET6_ADDRSTRLEN),
+	    prefixlen);
+
+	if (ioctl(ifr6fd, add ? SIOCADDRT : SIOCDELRT, (void *) &rt) < 0)
+		LOG(0, 0, 0, "route6set() error in ioctl: %s\n",
+				strerror(errno));
+
+	// FIXME: need to add BGP routing (RFC2858)
+
+	if (s)
+	{
+		if (!add)	// Are we deleting a route?
+			s = 0;	// Caching the session as '0' is the same as uncaching.
+
+		cache_ipv6map(ip, prefixlen, s);
+	}
+	
+	return;
+}
+
+// defined in linux/ipv6.h, but tricky to include from user-space
+// TODO: move routing to use netlink rather than ioctl
+struct in6_ifreq {
+	struct in6_addr ifr6_addr;
+	__u32 ifr6_prefixlen;
+	unsigned int ifr6_ifindex;
+};
+
 //
 // Set up TUN interface
 static void inittun(void)
 {
 	struct ifreq ifr;
+	struct in6_ifreq ifr6;
 	struct sockaddr_in sin = {0};
 	memset(&ifr, 0, sizeof(ifr));
 	ifr.ifr_flags = IFF_TUN;
@@ -471,6 +527,42 @@ static void inittun(void)
 		LOG(0, 0, 0, "Error setting tun flags: %s\n", strerror(errno));
 		exit(1);
 	}
+	if (ioctl(ifrfd, SIOCGIFINDEX, (void *) &ifr) < 0)
+	{
+		LOG(0, 0, 0, "Error getting tun ifindex: %s\n", strerror(errno));
+		exit(1);
+	}
+	tunidx = ifr.ifr_ifindex;
+
+	// Only setup IPv6 on the tun device if we have a configured prefix
+	if (config->ipv6_prefix.s6_addr[0] > 0) {
+		ifr6fd = socket(PF_INET6, SOCK_DGRAM, 0);
+
+		// Link local address is FE80::1
+		memset(&ifr6.ifr6_addr, 0, sizeof(ifr6.ifr6_addr));
+		ifr6.ifr6_addr.s6_addr[0] = 0xFE;
+		ifr6.ifr6_addr.s6_addr[1] = 0x80;
+		ifr6.ifr6_addr.s6_addr[15] = 1;
+		ifr6.ifr6_prefixlen = 64;
+		ifr6.ifr6_ifindex = ifr.ifr_ifindex;
+		if (ioctl(ifr6fd, SIOCSIFADDR, (void *) &ifr6) < 0)
+		{
+			LOG(0, 0, 0, "Error setting tun IPv6 link local address:"
+				" %s\n", strerror(errno));
+		}
+
+		// Global address is prefix::1
+		memset(&ifr6.ifr6_addr, 0, sizeof(ifr6.ifr6_addr));
+		ifr6.ifr6_addr = config->ipv6_prefix;
+		ifr6.ifr6_addr.s6_addr[15] = 1;
+		ifr6.ifr6_prefixlen = 64;
+		ifr6.ifr6_ifindex = ifr.ifr_ifindex;
+		if (ioctl(ifr6fd, SIOCSIFADDR, (void *) &ifr6) < 0)
+		{
+			LOG(0, 0, 0, "Error setting tun IPv6 global address: %s\n",
+				strerror(errno));
+		}
+	}
 }
 
 // set up UDP port
@@ -537,17 +629,62 @@ static int lookup_ipmap(in_addr_t ip)
 	return (int) (intptr_t) d[(size_t) *a];
 }
 
+static int lookup_ipv6map(struct in6_addr ip)
+{
+	struct ipv6radix *curnode;
+	int i;
+	int s;
+	char ipv6addr[INET6_ADDRSTRLEN];
+
+	curnode = &ipv6_hash[ip.s6_addr[0]];
+	i = 1;
+	s = curnode->sess;
+
+	while (s == 0 && i < 15 && curnode->branch != NULL)
+	{
+		curnode = &curnode->branch[ip.s6_addr[i]];
+		s = curnode->sess;
+		i++;
+	}
+
+	LOG(4, s, session[s].tunnel, "Looking up address %s and got %d\n",
+    			inet_ntop(AF_INET6, &ip, ipv6addr,
+				INET6_ADDRSTRLEN),
+			s);
+
+	return s;
+}
+
 sessionidt sessionbyip(in_addr_t ip)
 {
 	int s = lookup_ipmap(ip);
 	CSTAT(sessionbyip);
 
-	if (s > 0 && s < MAXSESSION && session[s].tunnel)
+	if (s > 0 && s < MAXSESSION && session[s].opened)
 		return (sessionidt) s;
 
 	return 0;
 }
 
+sessionidt sessionbyipv6(struct in6_addr ip)
+{
+	int s;
+	CSTAT(sessionbyipv6);
+
+	if (!memcmp(&config->ipv6_prefix, &ip, 8) ||
+		(ip.s6_addr[0] == 0xFE && ip.s6_addr[1] == 0x80 &&
+		 (ip.s6_addr16[1] == ip.s6_addr16[2] == ip.s6_addr16[3] == 0))) {
+		s = lookup_ipmap(*(in_addr_t *) &ip.s6_addr[8]);
+	} else {
+		s = lookup_ipv6map(ip);
+	}
+
+	if (s > 0 && s < MAXSESSION && session[s].opened)
+		return s;
+
+	return 0;
+}
+
 //
 // Take an IP address in HOST byte order and
 // add it to the sessionid by IP cache.
@@ -587,6 +724,42 @@ static void uncache_ipmap(in_addr_t ip)
 	cache_ipmap(ip, 0);	// Assign it to the NULL session.
 }
 
+static void cache_ipv6map(struct in6_addr ip, int prefixlen, int s)
+{
+	int i;
+	int bytes;
+	struct ipv6radix *curnode;
+	char ipv6addr[INET6_ADDRSTRLEN];
+
+	curnode = &ipv6_hash[ip.s6_addr[0]];
+
+	bytes = prefixlen >> 3;
+	i = 1;
+	while (i < bytes) {
+		if (curnode->branch == NULL)
+		{
+			if (!(curnode->branch = calloc(256,
+					sizeof (struct ipv6radix))))
+				return;
+		}
+		curnode = &curnode->branch[ip.s6_addr[i]];
+		i++;
+	}
+
+	curnode->sess = s;
+
+	if (s > 0)
+		LOG(4, s, session[s].tunnel, "Caching ip address %s/%d\n",
+	    			inet_ntop(AF_INET6, &ip, ipv6addr, 
+					INET6_ADDRSTRLEN),
+				prefixlen);
+	else if (s == 0)
+		LOG(4, 0, 0, "Un-caching ip address %s/%d\n",
+	    			inet_ntop(AF_INET6, &ip, ipv6addr, 
+					INET6_ADDRSTRLEN),
+				prefixlen);
+}
+
 //
 // CLI list to dump current ipcache.
 //
@@ -642,8 +815,11 @@ sessionidt sessionbyuser(char *username)
 	int s;
 	CSTAT(sessionbyuser);
 
-	for (s = 1; s < MAXSESSION ; ++s)
+	for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
 	{
+		if (!session[s].opened)
+			continue;
+
 		if (session[s].walled_garden)
 			continue;		// Skip walled garden users.
 
@@ -685,17 +861,16 @@ void send_garp(in_addr_t ip)
 	sendarp(ifr.ifr_ifindex, mac, ip);
 }
 
-// Find session by username, 0 for not found
 static sessiont *sessiontbysessionidt(sessionidt s)
 {
-	if (!s || s > MAXSESSION) return NULL;
+	if (!s || s >= MAXSESSION) return NULL;
 	return &session[s];
 }
 
 static sessionidt sessionidtbysessiont(sessiont *s)
 {
 	sessionidt val = s-session;
-	if (s < session || val > MAXSESSION) return 0;
+	if (s < session || val >= MAXSESSION) return 0;
 	return val;
 }
 
@@ -832,7 +1007,7 @@ static void processipout(uint8_t * buf, int len)
 	// DoS prevention: enforce a maximum number of packets per 0.1s for a session
 	if (config->max_packets > 0)
 	{
-		if (sess_count[s].last_packet_out == TIME)
+		if (sess_local[s].last_packet_out == TIME)
 		{
 			int max = config->max_packets;
 
@@ -845,24 +1020,26 @@ static void processipout(uint8_t * buf, int len)
 			if (!config->cluster_iam_master && sp->throttle_out && sp->throttle_out < max)
 				max = sp->throttle_out;
 
-			if (++sess_count[s].packets_out > max)
+			if (++sess_local[s].packets_out > max)
 			{
-				sess_count[s].packets_dropped++;
+				sess_local[s].packets_dropped++;
 				return;
 			}
 		}
 		else
 		{
-			if (sess_count[s].packets_dropped)
+			if (sess_local[s].packets_dropped)
 			{
-				INC_STAT(tun_rx_dropped, sess_count[s].packets_dropped);
-				LOG(2, s, t, "Possible DoS attack on %s (%s); dropped %u packets.\n",
-					fmtaddr(ip, 0), sp->user, sess_count[s].packets_dropped);
+				INC_STAT(tun_rx_dropped, sess_local[s].packets_dropped);
+				LOG(3, s, t, "Dropped %u/%u packets to %s for %suser %s\n",
+					sess_local[s].packets_dropped, sess_local[s].packets_out,
+					fmtaddr(ip, 0), sp->throttle_out ? "throttled " : "",
+					sp->user);
 			}
 
-			sess_count[s].last_packet_out = TIME;
-			sess_count[s].packets_out = 1;
-			sess_count[s].packets_dropped = 0;
+			sess_local[s].last_packet_out = TIME;
+			sess_local[s].packets_out = 1;
+			sess_local[s].packets_dropped = 0;
 		}
 	}
 
@@ -903,7 +1080,116 @@ static void processipout(uint8_t * buf, int len)
 	sp->total_cout += len; // byte count
 	sp->pout++;
 	udp_tx += len;
-	sess_count[s].cout += len;	// To send to master..
+	sess_local[s].cout += len;	// To send to master..
+}
+
+// process outgoing (to tunnel) IPv6
+//
+static void processipv6out(uint8_t * buf, int len)
+{
+	sessionidt s;
+	sessiont *sp;
+	tunnelidt t;
+	in_addr_t ip;
+	struct in6_addr ip6;
+
+	char *data = buf;	// Keep a copy of the originals.
+	int size = len;
+
+	uint8_t b[MAXETHER + 20];
+
+	CSTAT(processipv6out);
+
+	if (len < MIN_IP_SIZE)
+	{
+		LOG(1, 0, 0, "Short IPv6, %d bytes\n", len);
+		STAT(tunnel_tx_errors);
+		return;
+	}
+	if (len >= MAXETHER)
+	{
+		LOG(1, 0, 0, "Oversize IPv6 packet %d bytes\n", len);
+		STAT(tunnel_tx_errors);
+		return;
+	}
+
+	// Skip the tun header
+	buf += 4;
+	len -= 4;
+
+	// Got an IP header now
+	if (*(uint8_t *)(buf) >> 4 != 6)
+	{
+		LOG(1, 0, 0, "IP: Don't understand anything except IPv6\n");
+		return;
+	}
+
+	ip6 = *(struct in6_addr *)(buf+24);
+	s = sessionbyipv6(ip6);
+
+	if (s == 0)
+	{
+		ip = *(uint32_t *)(buf + 32);
+		s = sessionbyip(ip);
+	}
+	
+	if (s == 0)
+	{
+		// Is this a packet for a session that doesn't exist?
+		static int rate = 0;	// Number of ICMP packets we've sent this second.
+		static int last = 0;	// Last time we reset the ICMP packet counter 'rate'.
+
+		if (last != time_now)
+		{
+			last = time_now;
+			rate = 0;
+		}
+
+		if (rate++ < config->icmp_rate) // Only send a max of icmp_rate per second.
+		{
+			// FIXME: Should send icmp6 host unreachable
+		}
+		return;
+	}
+	t = session[s].tunnel;
+	sp = &session[s];
+
+	// FIXME: add DoS prevention/filters?
+
+	if (sp->tbf_out)
+	{
+		// Are we throttling this session?
+		if (config->cluster_iam_master)
+			tbf_queue_packet(sp->tbf_out, data, size);
+		else
+			master_throttle_packet(sp->tbf_out, data, size);
+		return;
+	}
+	else if (sp->walled_garden && !config->cluster_iam_master)
+	{
+		// We are walled-gardening this
+		master_garden_packet(s, data, size);
+		return;
+	}
+
+	LOG(5, s, t, "Ethernet -> Tunnel (%d bytes)\n", len);
+
+	// Add on L2TP header
+	{
+		uint8_t *p = makeppp(b, sizeof(b), buf, len, t, s, PPPIPV6);
+		if (!p) return;
+		tunnelsend(b, len + (p-b), t); // send it...
+	}
+
+	// Snooping this session, send it to intercept box
+	if (sp->snoop_ip && sp->snoop_port)
+		snoop_send_packet(buf, len, sp->snoop_ip, sp->snoop_port);
+
+	sp->cout += len; // byte count
+	sp->total_cout += len; // byte count
+	sp->pout++;
+	udp_tx += len;
+	sess_local[s].cout += len;	// To send to master..
 }
 
 //
@@ -953,7 +1239,7 @@ static void send_ipout(sessionidt s, uint8_t *buf, int len)
 	sp->total_cout += len; // byte count
 	sp->pout++;
 	udp_tx += len;
-	sess_count[s].cout += len;	// To send to master..
+	sess_local[s].cout += len;	// To send to master..
 }
 
 // add an AVP (16 bit)
@@ -978,7 +1264,7 @@ static void control32(controlt * c, uint16_t avp, uint32_t val, uint8_t m)
 	c->length += 10;
 }
 
-// add an AVP (32 bit)
+// add an AVP (string)
 static void controls(controlt * c, uint16_t avp, char *val, uint8_t m)
 {
 	uint16_t l = ((m ? 0x8000 : 0) + strlen(val) + 6);
@@ -1073,7 +1359,7 @@ static void controladd(controlt * c, tunnelidt t, sessionidt s)
 //
 void throttle_session(sessionidt s, int rate_in, int rate_out)
 {
-	if (!session[s].tunnel)
+	if (!session[s].opened)
 		return; // No-one home.
 
 	if (!*session[s].user)
@@ -1109,9 +1395,9 @@ void throttle_session(sessionidt s, int rate_in, int rate_out)
 }
 
 // add/remove filters from session (-1 = no change)
-void filter_session(sessionidt s, int filter_in, int filter_out)
+static void filter_session(sessionidt s, int filter_in, int filter_out)
 {
-	if (!session[s].tunnel)
+	if (!session[s].opened)
 		return; // No-one home.
 
 	if (!*session[s].user)
@@ -1147,16 +1433,16 @@ void filter_session(sessionidt s, int filter_in, int filter_out)
 }
 
 // start tidy shutdown of session
-void sessionshutdown(sessionidt s, char *reason)
+void sessionshutdown(sessionidt s, char *reason, int result, int error)
 {
 	int walled_garden = session[s].walled_garden;
 
 
 	CSTAT(sessionshutdown);
 
-	if (!session[s].tunnel)
+	if (!session[s].opened)
 	{
-		LOG(3, s, session[s].tunnel, "Called sessionshutdown on a session with no tunnel.\n");
+		LOG(3, s, session[s].tunnel, "Called sessionshutdown on an unopened session.\n");
 		return;                   // not a live session
 	}
 
@@ -1167,25 +1453,21 @@ void sessionshutdown(sessionidt s, char *reason)
 		run_plugins(PLUGIN_KILL_SESSION, &data);
 	}
 
-	if (session[s].opened && !walled_garden && !session[s].die)
+	if (session[s].ip && !walled_garden && !session[s].die)
 	{
 		// RADIUS Stop message
-		uint16_t r = session[s].radius;
+		uint16_t r = sess_local[s].radius;
 		if (!r)
+			r = radiusnew(s);
+
+		if (r)
 		{
-			if (!(r = radiusnew(s)))
-			{
-				LOG(1, s, session[s].tunnel, "No free RADIUS sessions for Stop message\n");
-				STAT(radius_overflow);
-			}
-			else
-			{
-				random_data(radius[r].auth, sizeof(radius[r].auth));
-			}
+			// stop, if not already trying
+			if (radius[r].state != RADIUSSTOP)
+				radiussend(r, RADIUSSTOP);
 		}
-
-		if (r && radius[r].state != RADIUSSTOP)
-			radiussend(r, RADIUSSTOP); // stop, if not already trying
+		else
+			LOG(1, s, session[s].tunnel, "No free RADIUS sessions for Stop message\n");
 
 	    	// Save counters to dump to accounting file
 		if (*config->accounting_dir && shut_acct_n < sizeof(shut_acct) / sizeof(*shut_acct))
@@ -1213,20 +1495,34 @@ void sessionshutdown(sessionidt s, char *reason)
 		}
 		else
 			free_ip_address(s);
+
+		// unroute IPv6, if setup
+		if (session[s].flags & SF_IPV6_ROUTED)
+			route6set(s, session[s].ipv6route, session[s].ipv6prefixlen, 0);
 	}
 
 	if (session[s].throttle_in || session[s].throttle_out) // Unthrottle if throttled.
 		throttle_session(s, 0, 0);
 
+	if (result)
 	{                            // Send CDN
 		controlt *c = controlnew(14); // sending CDN
-		control16(c, 1, 3, 1);    // result code (admin reasons - TBA make error, general error, add message
+		if (error)
+		{
+			char buf[4];
+			*(uint16_t *) buf     = htons(result);
+			*(uint16_t *) (buf+2) = htons(error);
+			controlb(c, 1, buf, 4, 1);
+		}
+		else
+			control16(c, 1, result, 1);
+
 		control16(c, 14, s, 1);   // assigned session (our end)
 		controladd(c, session[s].tunnel, s); // send the message
 	}
 
 	if (!session[s].die)
-		session[s].die = now() + 150; // Clean up in 15 seconds
+		session[s].die = TIME + 150; // Clean up in 15 seconds
 
 	// update filter refcounts
 	if (session[s].filter_in) ip_filters[session[s].filter_in - 1].used--;
@@ -1238,7 +1534,7 @@ void sessionshutdown(sessionidt s, char *reason)
 void sendipcp(tunnelidt t, sessionidt s)
 {
 	uint8_t buf[MAXCONTROL];
-	uint16_t r = session[s].radius;
+	uint16_t r = sess_local[s].radius;
 	uint8_t *q;
 
 	CSTAT(sendipcp);
@@ -1246,6 +1542,12 @@ void sendipcp(tunnelidt t, sessionidt s)
 	if (!r)
 		r = radiusnew(s);
 
+	if (!r)
+	{
+		sessionshutdown(s, "No free RADIUS sessions for IPCP", 3, 0);
+		return;
+	}
+
 	if (radius[r].state != RADIUSIPCP)
 	{
 		radius[r].state = RADIUSIPCP;
@@ -1256,7 +1558,7 @@ void sendipcp(tunnelidt t, sessionidt s)
 	if (radius[r].try > 10)
 	{
 		radiusclear(r, s);	// Clear radius session.
-		sessionshutdown(s, "No reply on IPCP");
+		sessionshutdown(s, "No reply to IPCP.", 3, 0);
 		return;
 	}
 
@@ -1274,26 +1576,65 @@ void sendipcp(tunnelidt t, sessionidt s)
 
 	tunnelsend(buf, 10 + (q - buf), t); // send it
 	session[s].flags &= ~SF_IPCP_ACKED;	// Clear flag.
+
+	// If we have an IPv6 prefix length configured, assume we should
+	// try to negotiate an IPv6 session as well. Unless we've had a
+	// (N)ACK for IPV6CP.
+	if (config->ipv6_prefix.s6_addr[0] > 0 && 
+			!(session[s].flags & SF_IPV6CP_ACKED) &&
+			!(session[s].flags & SF_IPV6_NACKED))
+	{
+		q = makeppp(buf,sizeof(buf), 0, 0, t, s, PPPIPV6CP);
+		if (!q) return;
+
+		*q = ConfigReq;
+		q[1] = r << RADIUS_SHIFT;		// ID, don't care, we
+							// only send one type
+							// of request
+		*(uint16_t *) (q + 2) = htons(14);
+		q[4] = 1;
+		q[5] = 10;
+		*(uint32_t *) (q + 6) = 0;		// We'll be prefix::1
+		*(uint32_t *) (q + 10) = 0;
+		q[13] = 1;
+
+		tunnelsend(buf, 14 + (q - buf), t);	// send it
+	}
+}
+
+static void sessionclear(sessionidt s)
+{
+	memset(&session[s], 0, sizeof(session[s]));
+	memset(&sess_local[s], 0, sizeof(sess_local[s]));
+	memset(&cli_session_actions[s], 0, sizeof(cli_session_actions[s]));
+
+	session[s].tunnel = T_FREE;	// Mark it as free.
+	session[s].next = sessionfree;
+	sessionfree = s;
 }
 
 // kill a session now
-static void sessionkill(sessionidt s, char *reason)
+void sessionkill(sessionidt s, char *reason)
 {
 
 	CSTAT(sessionkill);
 
-	session[s].die = now();
-	sessionshutdown(s, reason);  // close radius/routes, etc.
-	if (session[s].radius)
-		radiusclear(session[s].radius, s); // cant send clean accounting data, session is killed
+	if (!session[s].opened) // not alive
+		return;
 
-	LOG(2, s, session[s].tunnel, "Kill session %d (%s): %s\n", s, session[s].user, reason);
+	if (session[s].next)
+	{
+		LOG(0, s, session[s].tunnel, "Tried to kill a session with next pointer set (%d)\n", session[s].next);
+		return;
+	}
 
-	memset(&session[s], 0, sizeof(session[s]));
-	session[s].tunnel = T_FREE;	// Mark it as free.
-	session[s].next = sessionfree;
-	sessionfree = s;
-	cli_session_actions[s].action = 0;
+	session[s].die = TIME;
+	sessionshutdown(s, reason, 3, 0);  // close radius/routes, etc.
+	if (sess_local[s].radius)
+		radiusclear(sess_local[s].radius, s); // cant send clean accounting data, session is killed
+
+	LOG(2, s, session[s].tunnel, "Kill session %d (%s): %s\n", s, session[s].user, reason);
+	sessionclear(s);
 	cluster_send_session(s);
 }
 
@@ -1324,19 +1665,19 @@ static void tunnelkill(tunnelidt t, char *reason)
 		controlfree = c;
 	}
 	// kill sessions
-	for (s = 1; s < MAXSESSION; s++)
+	for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
 		if (session[s].tunnel == t)
 			sessionkill(s, reason);
 
 	// free tunnel
 	tunnelclear(t);
 	LOG(1, 0, t, "Kill tunnel %d: %s\n", t, reason);
-	cli_tunnel_actions[s].action = 0;
+	cli_tunnel_actions[t].action = 0;
 	cluster_send_tunnel(t);
 }
 
 // shut down a tunnel cleanly
-static void tunnelshutdown(tunnelidt t, char *reason)
+static void tunnelshutdown(tunnelidt t, char *reason, int result, int error, char *msg)
 {
 	sessionidt s;
 
@@ -1351,19 +1692,40 @@ static void tunnelshutdown(tunnelidt t, char *reason)
 	LOG(1, 0, t, "Shutting down tunnel %d (%s)\n", t, reason);
 
 	// close session
-	for (s = 1; s < MAXSESSION; s++)
+	for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
 		if (session[s].tunnel == t)
-			sessionshutdown(s, reason);
+			sessionshutdown(s, reason, 3, 0);
 
 	tunnel[t].state = TUNNELDIE;
-	tunnel[t].die = now() + 700; // Clean up in 70 seconds
+	tunnel[t].die = TIME + 700; // Clean up in 70 seconds
 	cluster_send_tunnel(t);
 	// TBA - should we wait for sessions to stop?
-	{                            // Send StopCCN
-		controlt *c = controlnew(4); // sending StopCCN
-		control16(c, 1, 1, 1);    // result code (admin reasons - TBA make error, general error, add message)
-		control16(c, 9, t, 1);    // assigned tunnel (our end)
-		controladd(c, t, 0);      // send the message
+	if (result) 
+	{
+		controlt *c = controlnew(4);	// sending StopCCN
+		if (error)
+		{
+			char buf[64];
+			int l = 4;
+			*(uint16_t *) buf     = htons(result);
+			*(uint16_t *) (buf+2) = htons(error);
+			if (msg)
+			{
+				int m = strlen(msg);
+				if (m + 4 > sizeof(buf))
+				    m = sizeof(buf) - 4;
+
+				memcpy(buf+4, msg, m);
+				l += m;
+			}
+
+			controlb(c, 1, buf, l, 1);
+		}
+		else
+			control16(c, 1, result, 1);
+
+		control16(c, 9, t, 1);		// assigned tunnel (our end)
+		controladd(c, t, 0);		// send the message
 	}
 }
 
@@ -1438,13 +1800,12 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 	{                          // control
 		uint16_t message = 0xFFFF;	// message type
 		uint8_t fatal = 0;
-		uint8_t mandatorymessage = 0;
-		uint8_t chap = 0;		// if CHAP being used
+		uint8_t mandatory = 0;
+		uint8_t authtype = 0;		// proxy auth type
 		uint16_t asession = 0;		// assigned session
 		uint32_t amagic = 0;		// magic number
 		uint8_t aflags = 0;		// flags from last LCF
 		uint16_t version = 0x0100;	// protocol version (we handle 0.0 as well and send that back just in case)
-		int requestchap = 0;		// do we request PAP instead of original CHAP request?
 		char called[MAXTEL] = "";	// called number
 		char calling[MAXTEL] = "";	// calling number
 
@@ -1454,7 +1815,10 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 			return;
 		}
 
-		if ((*buf & 0xCA) != 0xC8)
+		// control messages must have bits 0x80|0x40|0x08
+		// (type, length and sequence) set, and bits 0x02|0x01
+		// (offset and priority) clear
+		if ((*buf & 0xCB) != 0xC8)
 		{
 			LOG(1, s, t, "Bad control header %02X\n", *buf);
 			STAT(tunnel_rx_errors);
@@ -1564,71 +1928,111 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 		}
 		if (l)
 		{                     // if not a null message
+			int result = 0;
+			int error = 0;
+			char *msg = 0;
+
 			// process AVPs
-			while (l && !(fatal & 0x80))
+			while (l && !(fatal & 0x80)) // 0x80 = mandatory AVP
 			{
 				uint16_t n = (ntohs(*(uint16_t *) p) & 0x3FF);
 				uint8_t *b = p;
 				uint8_t flags = *p;
 				uint16_t mtype;
-				p += n;       // next
-				if (l < n)
+				if (n > l)
 				{
 					LOG(1, s, t, "Invalid length in AVP\n");
 					STAT(tunnel_rx_errors);
-					fatal = flags;
 					return;
 				}
+				p += n;       // next
 				l -= n;
+				if (flags & 0x3C) // reserved bits, should be clear
+				{
+					LOG(1, s, t, "Unrecognised AVP flags %02X\n", *b);
+					fatal = flags;
+					result = 2; // general error
+					error = 3; // reserved field non-zero
+					msg = 0;
+					continue; // next
+				}
+				b += 2;
+				if (*(uint16_t *) (b))
+				{
+					LOG(2, s, t, "Unknown AVP vendor %d\n", ntohs(*(uint16_t *) (b)));
+					fatal = flags;
+					result = 2; // general error
+					error = 6; // generic vendor-specific error
+					msg = "unsupported vendor-specific";
+					continue; // next
+				}
+				b += 2;
+				mtype = ntohs(*(uint16_t *) (b));
+				b += 2;
+				n -= 6;
+
 				if (flags & 0x40)
 				{
+					uint16_t orig_len;
+
 					// handle hidden AVPs
 					if (!*config->l2tpsecret)
 					{
 						LOG(1, s, t, "Hidden AVP requested, but no L2TP secret.\n");
 						fatal = flags;
+						result = 2; // general error
+						error = 6; // generic vendor-specific error
+						msg = "secret not specified";
 						continue;
 					}
 					if (!session[s].random_vector_length)
 					{
 						LOG(1, s, t, "Hidden AVP requested, but no random vector.\n");
 						fatal = flags;
+						result = 2; // general error
+						error = 6; // generic
+						msg = "no random vector";
+						continue;
+					}
+					if (n < 8)
+					{
+						LOG(2, s, t, "Short hidden AVP.\n");
+						fatal = flags;
+						result = 2; // general error
+						error = 2; // length is wrong
+						msg = 0;
 						continue;
 					}
+
 					LOG(4, s, t, "Hidden AVP\n");
+
 					// Unhide the AVP
-					n = unhide_avp(b, t, s, n);
-					if (n == 0)
+					unhide_value(b, n, mtype, session[s].random_vector, session[s].random_vector_length);
+
+					orig_len = ntohs(*(uint16_t *) b);
+					if (orig_len > n + 2)
 					{
+						LOG(1, s, t, "Original length %d too long in hidden AVP of length %d; wrong secret?\n",
+						    orig_len, n);
+
 						fatal = flags;
+						result = 2; // general error
+						error = 2; // length is wrong
+						msg = 0;
 						continue;
 					}
+
+					b += 2;
+					n = orig_len;
 				}
-				if (*b & 0x3C)
-				{
-					LOG(1, s, t, "Unrecognised AVP flags %02X\n", *b);
-					fatal = flags;
-					continue; // next
-				}
-				b += 2;
-				if (*(uint16_t *) (b))
-				{
-					LOG(2, s, t, "Unknown AVP vendor %d\n", ntohs(*(uint16_t *) (b)));
-					fatal = flags;
-					continue; // next
-				}
-				b += 2;
-				mtype = ntohs(*(uint16_t *) (b));
-				b += 2;
-				n -= 6;
 
 				LOG(4, s, t, "   AVP %d (%s) len %d\n", mtype, avp_name(mtype), n);
 				switch (mtype)
 				{
 				case 0:     // message type
 					message = ntohs(*(uint16_t *) b);
+					mandatory = flags & 0x80;
 					LOG(4, s, t, "   Message type = %d (%s)\n", *b, l2tp_message_type(message));
-					mandatorymessage = flags;
 					break;
 				case 1:     // result code
 					{
@@ -1663,6 +2067,9 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 						{   // allow 0.0 and 1.0
 							LOG(1, s, t, "   Bad protocol version %04X\n", version);
 							fatal = flags;
+							result = 5; // unspported protocol version
+							error = 0x0100; // supported version
+							msg = 0;
 							continue; // next
 						}
 					}
@@ -1681,14 +2088,14 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 //					LOG(4, s, t, "Firmware revision\n");
 					break;
 				case 7:     // host name
-					memset(tunnel[t].hostname, 0, 128);
-					memcpy(tunnel[t].hostname, b, (n >= 127) ? 127 : n);
+					memset(tunnel[t].hostname, 0, sizeof(tunnel[t].hostname));
+					memcpy(tunnel[t].hostname, b, (n < sizeof(tunnel[t].hostname)) ? n : sizeof(tunnel[t].hostname) - 1);
 					LOG(4, s, t, "   Tunnel hostname = \"%s\"\n", tunnel[t].hostname);
 					// TBA - to send to RADIUS
 					break;
 				case 8:     // vendor name
 					memset(tunnel[t].vendor, 0, sizeof(tunnel[t].vendor));
-					memcpy(tunnel[t].vendor, b, (n >= sizeof(tunnel[t].vendor) - 1) ? sizeof(tunnel[t].vendor) - 1 : n);
+					memcpy(tunnel[t].vendor, b, (n < sizeof(tunnel[t].vendor)) ? n : sizeof(tunnel[t].vendor) - 1);
 					LOG(4, s, t, "   Vendor name = \"%s\"\n", tunnel[t].vendor);
 					break;
 				case 9:     // assigned tunnel
@@ -1728,13 +2135,13 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 					// TBA
 					break;
 				case 21:    // called number
-					memset(called, 0, MAXTEL);
-					memcpy(called, b, (n >= MAXTEL) ? (MAXTEL-1) : n);
+					memset(called, 0, sizeof(called));
+					memcpy(called, b, (n < sizeof(called)) ? n : sizeof(called) - 1);
 					LOG(4, s, t, "   Called <%s>\n", called);
 					break;
 				case 22:    // calling number
-					memset(calling, 0, MAXTEL);
-					memcpy(calling, b, (n >= MAXTEL) ? (MAXTEL-1) : n);
+					memset(calling, 0, sizeof(calling));
+					memcpy(calling, b, (n < sizeof(calling)) ? n : sizeof(calling) - 1);
 					LOG(4, s, t, "   Calling <%s>\n", calling);
 					break;
 				case 23:    // subtype
@@ -1747,8 +2154,9 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 					else
 					{
 						// AS5300s send connect speed as a string
-						char tmp[30] = {0};
-						memcpy(tmp, b, (n >= 30) ? 30 : n);
+						char tmp[30];
+						memset(tmp, 0, sizeof(tmp));
+						memcpy(tmp, b, (n < sizeof(tmp)) ? n : sizeof(tmp) - 1);
 						session[s].tx_connect_speed = atol(tmp);
 					}
 					LOG(4, s, t, "   TX connect speed <%u>\n", session[s].tx_connect_speed);
@@ -1761,8 +2169,9 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 					else
 					{
 						// AS5300s send connect speed as a string
-						char tmp[30] = {0};
-						memcpy(tmp, b, (n >= 30) ? 30 : n);
+						char tmp[30];
+						memset(tmp, 0, sizeof(tmp));
+						memcpy(tmp, b, (n < sizeof(tmp)) ? n : sizeof(tmp) - 1);
 						session[s].rx_connect_speed = atol(tmp);
 					}
 					LOG(4, s, t, "   RX connect speed <%u>\n", session[s].rx_connect_speed);
@@ -1777,47 +2186,51 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 					{
 						uint16_t atype = ntohs(*(uint16_t *)b);
 						LOG(4, s, t, "   Proxy Auth Type %d (%s)\n", atype, auth_type(atype));
-						requestchap = (atype == 2);
+						if (atype == 2)
+							authtype = AUTHCHAP;
+						else if (atype == 3)
+							authtype = AUTHPAP;
+
 						break;
 					}
 				case 30:    // Proxy Authentication Name
 					{
-						char authname[64] = {0};
-						memcpy(authname, b, (n > 63) ? 63 : n);
+						char authname[64];
+						memset(authname, 0, sizeof(authname));
+						memcpy(authname, b, (n < sizeof(authname)) ? n : sizeof(authname) - 1);
 						LOG(4, s, t, "   Proxy Auth Name (%s)\n",
 							authname);
 						break;
 					}
 				case 31:    // Proxy Authentication Challenge
 					{
-						memcpy(radius[session[s].radius].auth, b, 16);
 						LOG(4, s, t, "   Proxy Auth Challenge\n");
+						if (sess_local[s].radius)
+							memcpy(radius[sess_local[s].radius].auth, b, 16);
 						break;
 					}
 				case 32:    // Proxy Authentication ID
 					{
 						uint16_t authid = ntohs(*(uint16_t *)(b));
 						LOG(4, s, t, "   Proxy Auth ID (%d)\n", authid);
-						if (session[s].radius)
-							radius[session[s].radius].id = authid;
+						if (sess_local[s].radius)
+							radius[sess_local[s].radius].id = authid;
 						break;
 					}
 				case 33:    // Proxy Authentication Response
-					{
-						char authresp[64] = {0};
-						memcpy(authresp, b, (n > 63) ? 63 : n);
-						LOG(4, s, t, "   Proxy Auth Response\n");
-						break;
-					}
-				case 27:    // last send lcp
+					LOG(4, s, t, "   Proxy Auth Response\n");
+					break;
+				case 27:    // last sent lcp
 					{        // find magic number
 						uint8_t *p = b, *e = p + n;
 						while (p + 1 < e && p[1] && p + p[1] <= e)
 						{
 							if (*p == 5 && p[1] == 6) // Magic-Number
 								amagic = ntohl(*(uint32_t *) (p + 2));
-							else if (*p == 3 && p[1] == 5 && *(uint16_t *) (p + 2) == htons(PPPCHAP) && p[4] == 5) // Authentication-Protocol
-								chap = 1;
+							else if (*p == 3 && p[1] == 4 && *(uint16_t *) (p + 2) == htons(PPPPAP)) // Authentication-Protocol (PAP)
+								authtype = AUTHPAP;
+							else if (*p == 3 && p[1] == 5 && *(uint16_t *) (p + 2) == htons(PPPCHAP) && p[4] == 5) // Authentication-Protocol (CHAP)
+								authtype = AUTHCHAP;
 							else if (*p == 7) // Protocol-Field-Compression
 								aflags |= SESSIONPFC;
 							else if (*p == 8) // Address-and-Control-Field-Compression
@@ -1839,14 +2252,20 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 					session[s].random_vector_length = n;
 					break;
 				default:
-					LOG(2, s, t, "   Unknown AVP type %d\n", mtype);
-					fatal = flags;
-					continue; // next
+					{
+						static char e[] = "unknown AVP 0xXXXX";
+						LOG(2, s, t, "   Unknown AVP type %d\n", mtype);
+						fatal = flags;
+						result = 2; // general error
+						error = 8; // unknown mandatory AVP
+						sprintf((msg = e) + 14, "%04x", mtype);
+						continue; // next
+					}
 				}
 			}
 			// process message
 			if (fatal & 0x80)
-				tunnelshutdown(t, "Unknown Mandatory AVP");
+				tunnelshutdown(t, "Invalid mandatory AVP", result, error, msg);
 			else
 				switch (message)
 				{
@@ -1871,8 +2290,7 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 					break;
 				case 4:       // StopCCN
 					controlnull(t); // ack
-					tunnelshutdown(t, "Stopped"); // Shut down cleanly
-					tunnelkill(t, "Stopped"); // Immediately force everything dead
+					tunnelshutdown(t, "Stopped", 0, 0, 0); // Shut down cleanly
 					break;
 				case 6:       // HELLO
 					controlnull(t); // simply ACK
@@ -1890,7 +2308,8 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 					if (!sessionfree)
 					{
 						STAT(session_overflow);
-						tunnelshutdown(t, "No free sessions");
+						LOG(1, 0, t, "No free sessions\n");
+						return;
 					}
 					else
 					{
@@ -1908,13 +2327,12 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 						if (!(r = radiusnew(s)))
 						{
 							LOG(1, s, t, "No free RADIUS sessions for ICRQ\n");
-							sessionkill(s, "no free RADIUS sesions");
+							sessionclear(s);
 							return;
 						}
 
 						c = controlnew(11); // sending ICRP
-						session[s].id = sessionid++;
-						session[s].opened = time(NULL);
+						session[s].opened = time_now;
 						session[s].tunnel = t;
 						session[s].far = asession;
 						session[s].last_packet = time_now;
@@ -1922,8 +2340,6 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 						control16(c, 14, s, 1); // assigned session
 						controladd(c, t, s); // send the reply
 
-						// Generate a random challenge
-						random_data(radius[r].auth, sizeof(radius[r].auth));
 						strncpy(radius[r].calling, calling, sizeof(radius[r].calling) - 1);
 						strncpy(session[s].called, called, sizeof(session[s].called) - 1);
 						strncpy(session[s].calling, calling, sizeof(session[s].calling) - 1);
@@ -1939,21 +2355,21 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 					session[s].l2tp_flags = aflags; // set flags received
 					LOG(3, s, t, "Magic %X Flags %X\n", amagic, aflags);
 					controlnull(t); // ack
-					// In CHAP state, request PAP instead
-					if (requestchap)
-						initlcp(t, s);
+					// proxy authentication type is not supported
+					if (authtype && !(config->radius_authtypes & authtype))
+						sendlcp(t, s, config->radius_authprefer);
 					break;
 				case 14:      // CDN
 					controlnull(t); // ack
-					sessionshutdown(s, "Closed (Received CDN)");
+					sessionshutdown(s, "Closed (Received CDN).", 0, 0);
 					break;
 				case 0xFFFF:
 					LOG(1, s, t, "Missing message type\n");
 					break;
 				default:
 					STAT(tunnel_rx_errors);
-					if (mandatorymessage & 0x80)
-						tunnelshutdown(t, "Unknown message");
+					if (mandatory)
+						tunnelshutdown(t, "Unknown message type", 2, 6, "unknown message type");
 					else
 						LOG(1, s, t, "Unknown message type %d\n", message);
 					break;
@@ -1994,7 +2410,7 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 			l -= 2;
 		}
 
-		if (s && !session[s].tunnel)	// Is something wrong??
+		if (s && !session[s].opened)	// Is something wrong??
 		{
 			if (!config->cluster_iam_master)
 			{
@@ -2004,9 +2420,7 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 			}
 
 
-			LOG(1, s, t, "UDP packet contains session %d but no session[%d].tunnel "
-				     "exists (LAC said tunnel = %d).  Dropping packet.\n", s, s, t);
-
+			LOG(1, s, t, "UDP packet contains session which is not opened.  Dropping packet.\n");
 			STAT(tunnel_rx_errors);
 			return;
 		}
@@ -2035,6 +2449,19 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 			if (!config->cluster_iam_master) { master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port); return; }
 			processipcp(t, s, p, l);
 		}
+		else if (prot == PPPIPV6CP)
+		{
+			if (config->ipv6_prefix.s6_addr[0] > 0)
+			{
+				session[s].last_packet = time_now;
+				if (!config->cluster_iam_master) { master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port); return; }
+				processipv6cp(t, s, p, l);
+			}
+			else
+			{
+				LOG(1, s, t, "IPv6 not configured; ignoring IPv6CP\n");
+			}
+		}
 		else if (prot == PPPCCP)
 		{
 			session[s].last_packet = time_now;
@@ -2058,6 +2485,28 @@ void processudp(uint8_t * buf, int len, struct sockaddr_in *addr)
 
 			processipin(t, s, p, l);
 		}
+		else if (prot == PPPIPV6)
+		{
+			if (!config->ipv6_prefix.s6_addr[0] > 0)
+			{
+				LOG(1, s, t, "IPv6 not configured; yet received IPv6 packet. Ignoring.\n");
+				return;
+			}
+			if (session[s].die)
+			{
+				LOG(4, s, t, "Session %d is closing.  Don't process PPP packets\n", s);
+				return;              // closing session, PPP not processed
+			}
+
+			session[s].last_packet = time_now;
+			if (session[s].walled_garden && !config->cluster_iam_master)
+			{
+				master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port);
+				return;
+			}
+
+			processipv6in(t, s, p, l);
+		}
 		else
 		{
 			STAT(tunnel_rx_errors);
@@ -2086,6 +2535,10 @@ static void processtun(uint8_t * buf, int len)
 
 	if (*(uint16_t *) (buf + 2) == htons(PKTIP)) // IPv4
 		processipout(buf, len);
+	else if (*(uint16_t *) (buf + 2) == htons(PKTIPV6) // IPV6
+	    && config->ipv6_prefix.s6_addr[0] > 0)
+		processipv6out(buf, len);
+
 	// Else discard.
 }
 
@@ -2161,7 +2614,7 @@ static int regular_cleanups(void)
 			if (a & CLI_TUN_KILL)
 			{
 				LOG(2, 0, t, "Dropping tunnel by CLI\n");
-				tunnelshutdown(t, "Requested by administrator");
+				tunnelshutdown(t, "Requested by administrator", 1, 0, 0);
 			}
 		}
 
@@ -2174,34 +2627,37 @@ static int regular_cleanups(void)
 		if (s > config->cluster_highest_sessionid)
 			s = 1;
 
-		if (!session[s].tunnel)	// Session isn't in use
+		if (!session[s].opened)	// Session isn't in use
 			continue;
 
-		if (!session[s].die && session[s].ip && !(session[s].flags & SF_IPCP_ACKED))
+		// check for expired sessions
+		if (session[s].die)
 		{
-			// IPCP has not completed yet. Resend
-			LOG(3, s, session[s].tunnel, "No ACK for initial IPCP ConfigReq... resending\n");
-			sendipcp(session[s].tunnel, s);
+			if (session[s].die <= TIME)
+			{
+				sessionkill(s, "Expired");
+				if (++count >= MAX_ACTIONS) break;
+			}
+			continue;
 		}
 
-		// check for expired sessions
-		if (session[s].die && session[s].die <= TIME)
+		if (session[s].ip && !(session[s].flags & SF_IPCP_ACKED))
 		{
-			sessionkill(s, "Expired");
-			if (++count >= MAX_ACTIONS) break;
-			continue;
+			// IPCP has not completed yet. Resend
+			LOG(3, s, session[s].tunnel, "No ACK for initial IPCP ConfigReq... resending\n");
+			sendipcp(session[s].tunnel, s);
 		}
 
 		// Drop sessions who have not responded within IDLE_TIMEOUT seconds
 		if (session[s].last_packet && (time_now - session[s].last_packet >= IDLE_TIMEOUT))
 		{
-			sessionshutdown(s, "No response to LCP ECHO requests");
+			sessionshutdown(s, "No response to LCP ECHO requests.", 3, 0);
 			STAT(session_timeout);
 			if (++count >= MAX_ACTIONS) break;
 			continue;
 		}
 
-		// No data in IDLE_TIMEOUT seconds, send LCP ECHO
+		// No data in ECHO_TIMEOUT seconds, send LCP ECHO
 		if (session[s].user[0] && (time_now - session[s].last_packet >= ECHO_TIMEOUT))
 		{
 			uint8_t b[MAXCONTROL] = {0};
@@ -2229,7 +2685,7 @@ static int regular_cleanups(void)
 			if (a & CLI_SESS_KILL)
 			{
 				LOG(2, s, session[s].tunnel, "Dropping session by CLI\n");
-				sessionshutdown(s, "Requested by administrator");
+				sessionshutdown(s, "Requested by administrator.", 3, 0);
 				a = 0; // dead, no need to check for other actions
 			}
 
@@ -2288,6 +2744,29 @@ static int regular_cleanups(void)
 
 			if (++count >= MAX_ACTIONS) break;
 		}
+
+		// RADIUS interim accounting
+		if (config->radius_accounting && config->radius_interim > 0
+		    && session[s].ip && !session[s].walled_garden
+		    && !sess_local[s].radius // RADIUS already in progress
+		    && time_now - sess_local[s].last_interim >= config->radius_interim)
+		{
+			if (!(r = radiusnew(s)))
+			{
+				LOG(1, s, session[s].tunnel, "No free RADIUS sessions for Interim message\n");
+				STAT(radius_overflow);
+				continue;
+			}
+
+			LOG(3, s, session[s].tunnel, "Sending RADIUS Interim for %s (%u)\n",
+				session[s].user, session[s].unique_id);
+
+			radiussend(r, RADIUSINTERIM);
+			sess_local[s].last_interim = time_now;
+
+			if (++count >= MAX_ACTIONS)
+				break;
+		}
 	}
 
 	if (*config->accounting_dir)
@@ -2700,16 +3179,12 @@ static void initdata(int optdebug, char *optconfig)
 {
 	int i;
 
-	if (!(_statistics = shared_malloc(sizeof(struct Tstats))))
-	{
-		LOG(0, 0, 0, "Error doing malloc for _statistics: %s\n", strerror(errno));
-		exit(1);
-	}
 	if (!(config = shared_malloc(sizeof(configt))))
 	{
-		LOG(0, 0, 0, "Error doing malloc for configuration: %s\n", strerror(errno));
+		fprintf(stderr, "Error doing malloc for configuration: %s\n", strerror(errno));
 		exit(1);
 	}
+
 	memset(config, 0, sizeof(configt));
 	time(&config->start_time);
 	strncpy(config->config_file, optconfig, strlen(optconfig));
@@ -2718,6 +3193,22 @@ static void initdata(int optdebug, char *optconfig)
 	config->rl_rate = 28; // 28kbps
 	strcpy(config->random_device, RANDOMDEVICE);
 
+	log_stream = stderr;
+
+#ifdef RINGBUFFER
+	if (!(ringbuffer = shared_malloc(sizeof(struct Tringbuffer))))
+	{
+		LOG(0, 0, 0, "Error doing malloc for ringbuffer: %s\n", strerror(errno));
+		exit(1);
+	}
+	memset(ringbuffer, 0, sizeof(struct Tringbuffer));
+#endif
+
+	if (!(_statistics = shared_malloc(sizeof(struct Tstats))))
+	{
+		LOG(0, 0, 0, "Error doing malloc for _statistics: %s\n", strerror(errno));
+		exit(1);
+	}
 	if (!(tunnel = shared_malloc(sizeof(tunnelt) * MAXTUNNEL)))
 	{
 		LOG(0, 0, 0, "Error doing malloc for tunnels: %s\n", strerror(errno));
@@ -2729,9 +3220,9 @@ static void initdata(int optdebug, char *optconfig)
 		exit(1);
 	}
 
-	if (!(sess_count = shared_malloc(sizeof(sessioncountt) * MAXSESSION)))
+	if (!(sess_local = shared_malloc(sizeof(sessionlocalt) * MAXSESSION)))
 	{
-		LOG(0, 0, 0, "Error doing malloc for sessions_count: %s\n", strerror(errno));
+		LOG(0, 0, 0, "Error doing malloc for sess_local: %s\n", strerror(errno));
 		exit(1);
 	}
 
@@ -2754,15 +3245,6 @@ static void initdata(int optdebug, char *optconfig)
 	}
 	memset(ip_filters, 0, sizeof(ip_filtert) * MAXFILTER);
 
-#ifdef RINGBUFFER
-	if (!(ringbuffer = shared_malloc(sizeof(struct Tringbuffer))))
-	{
-		LOG(0, 0, 0, "Error doing malloc for ringbuffer: %s\n", strerror(errno));
-		exit(1);
-	}
-	memset(ringbuffer, 0, sizeof(struct Tringbuffer));
-#endif
-
 	if (!(cli_session_actions = shared_malloc(sizeof(struct cli_session_actions) * MAXSESSION)))
 	{
 		LOG(0, 0, 0, "Error doing malloc for cli session actions: %s\n", strerror(errno));
@@ -2783,7 +3265,7 @@ static void initdata(int optdebug, char *optconfig)
 	memset(ip_address_pool, 0, sizeof(ippoolt) * MAXIPPOOL);
 
 		// Put all the sessions on the free list marked as undefined.
-	for (i = 1; i < MAXSESSION - 1; i++)
+	for (i = 1; i < MAXSESSION; i++)
 	{
 		session[i].next = i + 1;
 		session[i].tunnel = T_UNDEF;	// mark it as not filled in.
@@ -2792,7 +3274,7 @@ static void initdata(int optdebug, char *optconfig)
 	sessionfree = 1;
 
 		// Mark all the tunnels as undefined (waiting to be filled in by a download).
-	for (i = 1; i < MAXTUNNEL- 1; i++)
+	for (i = 1; i < MAXTUNNEL; i++)
 		tunnel[i].state = TUNNELUNDEF;	// mark it as not filled in.
 
 	if (!*hostname)
@@ -2918,8 +3400,9 @@ void rebuild_address_pool(void)
 	for (i = 0; i < MAXSESSION; ++i)
 	{
 		int ipid;
-		if (!session[i].ip || !session[i].tunnel)
+		if (!(session[i].opened && session[i].ip))
 			continue;
+
 		ipid = - lookup_ipmap(htonl(session[i].ip));
 
 		if (session[i].ip_pool_index < 0)
@@ -3283,8 +3766,6 @@ int main(int argc, char *argv[])
 	initrad();
 	initippool();
 
-	read_state();
-
 	signal(SIGHUP, sighup_handler);
 	signal(SIGTERM, sigterm_handler);
 	signal(SIGINT, sigterm_handler);
@@ -3331,9 +3812,11 @@ int main(int argc, char *argv[])
 
 static void sighup_handler(int sig)
 {
-	if (log_stream && log_stream != stderr)
+	if (log_stream)
 	{
-		fclose(log_stream);
+		if (log_stream != stderr)
+			fclose(log_stream);
+
 		log_stream = NULL;
 	}
 
@@ -3376,9 +3859,6 @@ static void sigalrm_handler(int sig)
 static void sigterm_handler(int sig)
 {
 	LOG(1, 0, 0, "Shutting down cleanly\n");
-	if (config->save_state)
-		dump_state();
-
 	main_quit++;
 }
 
@@ -3398,7 +3878,7 @@ static void sigquit_handler(int sig)
 		for (i = 1; i < MAXTUNNEL; i++)
 		{
 			if (tunnel[i].ip || tunnel[i].state)
-				tunnelshutdown(i, "L2TPNS Closing");
+				tunnelshutdown(i, "L2TPNS Closing", 6, 0, 0);
 		}
 	}
 
@@ -3411,182 +3891,6 @@ static void sigchild_handler(int sig)
 	    ;
 }
 
-static void read_state()
-{
-	struct stat sb;
-	int i;
-	ippoolt itmp;
-	FILE *f;
-	char magic[sizeof(DUMP_MAGIC) - 1];
-	uint32_t buf[2];
-
-	if (!config->save_state)
-	{
-		unlink(STATEFILE);
-		return ;
-	}
-
-	if (stat(STATEFILE, &sb) < 0)
-	{
-		unlink(STATEFILE);
-		return ;
-	}
-
-	if (sb.st_mtime < (time(NULL) - 60))
-	{
-		LOG(0, 0, 0, "State file is too old to read, ignoring\n");
-		unlink(STATEFILE);
-		return ;
-	}
-
-	f = fopen(STATEFILE, "r");
-	unlink(STATEFILE);
-
-	if (!f)
-	{
-		LOG(0, 0, 0, "Can't read state file: %s\n", strerror(errno));
-		exit(1);
-	}
-
-	if (fread(magic, sizeof(magic), 1, f) != 1 || strncmp(magic, DUMP_MAGIC, sizeof(magic)))
-	{
-		LOG(0, 0, 0, "Bad state file magic\n");
-		exit(1);
-	}
-
-	LOG(1, 0, 0, "Reading state information\n");
-	if (fread(buf, sizeof(buf), 1, f) != 1 || buf[0] > MAXIPPOOL || buf[1] != sizeof(ippoolt))
-	{
-		LOG(0, 0, 0, "Error/mismatch reading ip pool header from state file\n");
-		exit(1);
-	}
-
-	if (buf[0] > ip_pool_size)
-	{
-		LOG(0, 0, 0, "ip pool has shrunk!  state = %d, current = %d\n", buf[0], ip_pool_size);
-		exit(1);
-	}
-
-	LOG(2, 0, 0, "Loading %u ip addresses\n", buf[0]);
-	for (i = 0; i < buf[0]; i++)
-	{
-		if (fread(&itmp, sizeof(itmp), 1, f) != 1)
-		{
-			LOG(0, 0, 0, "Error reading ip %d from state file: %s\n", i, strerror(errno));
-			exit(1);
-		}
-
-		if (itmp.address != ip_address_pool[i].address)
-		{
-			LOG(0, 0, 0, "Mismatched ip %d from state file: pool may only be extended\n", i);
-			exit(1);
-		}
-
-		memcpy(&ip_address_pool[i], &itmp, sizeof(itmp));
-	}
-
-	if (fread(buf, sizeof(buf), 1, f) != 1 || buf[0] != MAXTUNNEL || buf[1] != sizeof(tunnelt))
-	{
-		LOG(0, 0, 0, "Error/mismatch reading tunnel header from state file\n");
-		exit(1);
-	}
-
-	LOG(2, 0, 0, "Loading %u tunnels\n", MAXTUNNEL);
-	if (fread(tunnel, sizeof(tunnelt), MAXTUNNEL, f) != MAXTUNNEL)
-	{
-		LOG(0, 0, 0, "Error reading tunnel data from state file\n");
-		exit(1);
-	}
-
-	for (i = 0; i < MAXTUNNEL; i++)
-	{
-		tunnel[i].controlc = 0;
-		tunnel[i].controls = NULL;
-		tunnel[i].controle = NULL;
-		if (*tunnel[i].hostname)
-			LOG(3, 0, 0, "Created tunnel for %s\n", tunnel[i].hostname);
-	}
-
-	if (fread(buf, sizeof(buf), 1, f) != 1 || buf[0] != MAXSESSION || buf[1] != sizeof(sessiont))
-	{
-		LOG(0, 0, 0, "Error/mismatch reading session header from state file\n");
-		exit(1);
-	}
-
-	LOG(2, 0, 0, "Loading %u sessions\n", MAXSESSION);
-	if (fread(session, sizeof(sessiont), MAXSESSION, f) != MAXSESSION)
-	{
-		LOG(0, 0, 0, "Error reading session data from state file\n");
-		exit(1);
-	}
-
-	for (i = 0; i < MAXSESSION; i++)
-	{
-		session[i].tbf_in = 0;
-		session[i].tbf_out = 0;
-		if (session[i].opened)
-		{
-			LOG(2, i, 0, "Loaded active session for user %s\n", session[i].user);
-			if (session[i].ip)
-				sessionsetup(session[i].tunnel, i);
-		}
-	}
-
-	fclose(f);
-	LOG(0, 0, 0, "Loaded saved state information\n");
-}
-
-static void dump_state()
-{
-	FILE *f;
-	uint32_t buf[2];
-
-	if (!config->save_state)
-		return;
-
-	do
-	{
-		if (!(f = fopen(STATEFILE, "w")))
-			break;
-
-		LOG(1, 0, 0, "Dumping state information\n");
-
-		if (fwrite(DUMP_MAGIC, sizeof(DUMP_MAGIC) - 1, 1, f) != 1)
-			break;
-
-		LOG(2, 0, 0, "Dumping %u ip addresses\n", ip_pool_size);
-		buf[0] = ip_pool_size;
-		buf[1] = sizeof(ippoolt);
-		if (fwrite(buf, sizeof(buf), 1, f) != 1)
-			break;
-		if (fwrite(ip_address_pool, sizeof(ippoolt), ip_pool_size, f) != ip_pool_size)
-			break;
-
-		LOG(2, 0, 0, "Dumping %u tunnels\n", MAXTUNNEL);
-		buf[0] = MAXTUNNEL;
-		buf[1] = sizeof(tunnelt);
-		if (fwrite(buf, sizeof(buf), 1, f) != 1)
-			break;
-		if (fwrite(tunnel, sizeof(tunnelt), MAXTUNNEL, f) != MAXTUNNEL)
-			break;
-
-		LOG(2, 0, 0, "Dumping %u sessions\n", MAXSESSION);
-		buf[0] = MAXSESSION;
-		buf[1] = sizeof(sessiont);
-		if (fwrite(buf, sizeof(buf), 1, f) != 1)
-			break;
-		if (fwrite(session, sizeof(sessiont), MAXSESSION, f) != MAXSESSION)
-			break;
-
-		if (fclose(f) == 0)
-			return ; // OK
-	}
-	while (0);
-
-	LOG(0, 0, 0, "Can't write state information: %s\n", strerror(errno));
-	unlink(STATEFILE);
-}
-
 static void build_chap_response(char *challenge, uint8_t id, uint16_t challenge_length, char **challenge_response)
 {
 	MD5_CTX ctx;
@@ -3634,7 +3938,9 @@ static void update_config()
 	syslog_log = 0;
 	if (log_stream)
 	{
-		fclose(log_stream);
+		if (log_stream != stderr)
+			fclose(log_stream);
+
 		log_stream = NULL;
 	}
 
@@ -3716,7 +4022,7 @@ static void update_config()
 		else if (!strncasecmp("pap", p, strlen(p)))
 			type = AUTHPAP;
 		else
-			LOG(0, 0, 0, "Invalid RADIUS authentication type \"%s\"", p);
+			LOG(0, 0, 0, "Invalid RADIUS authentication type \"%s\"\n", p);
 
 		config->radius_authtypes |= type;
 		if (!config->radius_authprefer)
@@ -3846,13 +4152,13 @@ int sessionsetup(tunnelidt t, sessionidt s)
 
 	LOG(3, s, t, "Doing session setup for session\n");
 
-	if (!session[s].ip || session[s].ip == 0xFFFFFFFE)
+	if (!session[s].ip)
 	{
 		assign_ip_address(s);
 		if (!session[s].ip)
 		{
 			LOG(0, s, t, "   No IP allocated.  The IP address pool is FULL!\n");
-			sessionshutdown(s, "No IP addresses available");
+			sessionshutdown(s, "No IP addresses available.", 2, 7);
 			return 0;
 		}
 		LOG(3, s, t, "   No IP allocated.  Assigned %s from pool\n",
@@ -3895,6 +4201,7 @@ int sessionsetup(tunnelidt t, sessionidt s)
 		// convered by a Framed-Route.  Anything else is part
 		// of the IP address pool and is already routed, it
 		// just needs to be added to the IP cache.
+		// IPv6 route setup is done in ppp.c, when IPV6CP is acked.
 		if (session[s].ip_pool_index == -1) // static ip
 		{
 			if (!routed) routeset(s, session[s].ip, 0, 0, 1);
@@ -4017,6 +4324,10 @@ int load_session(sessionidt s, sessiont *new)
 		}
 	}
 
+	// check v6 routing
+	if (new->flags & SF_IPV6_ROUTED && !(session[s].flags & SF_IPV6_ROUTED))
+		    route6set(s, new->ipv6route, new->ipv6prefixlen, 1);
+
 	// check filters
 	if (new->filter_in && (new->filter_in > MAXFILTER || !ip_filters[new->filter_in - 1].name[0]))
 	{
@@ -4444,7 +4755,7 @@ void become_master(void)
 	{
 		for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
 		{
-			if (!session[s].tunnel) // Not an in-use session.
+			if (!session[s].opened) // Not an in-use session.
 				continue;
 
 			run_plugins(PLUGIN_NEW_SESSION_MASTER, &session[s]);
@@ -4476,7 +4787,7 @@ int cmd_show_hist_idle(struct cli_def *cli, char *command, char **argv, int argc
 	for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
 	{
 		int idle;
-		if (!session[s].tunnel)
+		if (!session[s].opened)
 			continue;
 
 		idle = time_now - session[s].last_packet;
@@ -4514,7 +4825,7 @@ int cmd_show_hist_open(struct cli_def *cli, char *command, char **argv, int argc
 	for (s = 1; s <= config->cluster_highest_sessionid ; ++s)
 	{
 		int open = 0, d;
-		if (!session[s].tunnel)
+		if (!session[s].opened)
 			continue;
 
 		d = time_now - session[s].opened;
@@ -4541,75 +4852,45 @@ int cmd_show_hist_open(struct cli_def *cli, char *command, char **argv, int argc
 
 /* Unhide an avp.
  *
- * This unencodes the AVP using the L2TP CHAP secret and the
- * previously stored random vector. It replaces the hidden data with
- * the cleartext data and returns the length of the cleartext data
- * (including the AVP "header" of 6 bytes).
- *
- * Based on code from rp-l2tpd by Roaring Penguin Software Inc.
+ * This unencodes the AVP using the L2TP secret and the previously
+ * stored random vector.  It overwrites the hidden data with the
+ * unhidden AVP subformat.
  */
-static int unhide_avp(uint8_t *avp, tunnelidt t, sessionidt s, uint16_t length)
+static void unhide_value(uint8_t *value, size_t len, uint16_t type, uint8_t *vector, size_t vec_len)
 {
 	MD5_CTX ctx;
-	uint8_t *cursor;
 	uint8_t digest[16];
-	uint8_t working_vector[16];
-	uint16_t hidden_length;
-	uint8_t type[2];
-	size_t done, todo;
-	uint8_t *output;
-
-	// Find the AVP type.
-	type[0] = *(avp + 4);
-	type[1] = *(avp + 5);
-
-	// Line up with the hidden data
-	cursor = output = avp + 6;
+	uint8_t *last;
+	size_t d = 0;
 
 	// Compute initial pad
 	MD5Init(&ctx);
-	MD5Update(&ctx, type, 2);
+	MD5Update(&ctx, (uint8_t) (type >> 8) & 0xff, 1);
+	MD5Update(&ctx, (uint8_t)  type       & 0xff, 1);
 	MD5Update(&ctx, config->l2tpsecret, strlen(config->l2tpsecret));
-	MD5Update(&ctx, session[s].random_vector, session[s].random_vector_length);
+	MD5Update(&ctx, vector, vec_len);
 	MD5Final(digest, &ctx);
 
-	// Get hidden length
-	hidden_length = ((uint16_t) (digest[0] ^ cursor[0])) * 256 + (uint16_t) (digest[1] ^ cursor[1]);
-
-	// Keep these for later use
-	working_vector[0] = *cursor;
-	working_vector[1] = *(cursor + 1);
-	cursor += 2;
-
-	if (hidden_length > length - 8)
-	{
-		LOG(1, s, t, "Hidden length %d too long in AVP of length %d\n", (int) hidden_length, (int) length);
-		return 0;
-	}
+	// pointer to last decoded 16 octets
+	last = value;
 
-	/* Decrypt remainder */
-	done = 2;
-	todo = hidden_length;
-	while (todo)
+	while (len > 0)
 	{
-		working_vector[done] = *cursor;
-		*output = digest[done] ^ *cursor;
-		++output;
-		++cursor;
-		--todo;
-		++done;
-		if (done == 16 && todo)
+		// calculate a new pad based on the last decoded block
+		if (d >= sizeof(digest))
 		{
-			// Compute new digest
-			done = 0;
 			MD5Init(&ctx);
 			MD5Update(&ctx, config->l2tpsecret, strlen(config->l2tpsecret));
-			MD5Update(&ctx, &working_vector, 16);
+			MD5Update(&ctx, last, sizeof(digest));
 			MD5Final(digest, &ctx);
+
+			d = 0;
+			last = value;
 		}
-	}
 
-	return hidden_length + 6;
+		*value++ ^= digest[d++];
+		len--;
+	}
 }
 
 static int ip_filter_port(ip_filter_portt *p, uint16_t port)