[l2tpns.git] / l2tpns.c

// L2TP Network Server
// Adrian Kennard 2002
// Copyright (c) 2003, 2004 Optus Internet Engineering
// 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 1.11 2004/07/07 09:09:53 bodea Exp $";

#include <arpa/inet.h>
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/if_tun.h>
#define SYSLOG_NAMES
#include <syslog.h>
#include <malloc.h>
#include <math.h>
#include <net/route.h>
#include <sys/mman.h>
#include <netdb.h>
#include <netinet/in.h>
#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>
#define __USE_GNU
#include <string.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/wait.h>
#include <linux/if.h>
#include <stddef.h>
#include <time.h>
#include <dlfcn.h>
#include <unistd.h>
#include <sched.h>
#include <sys/sysinfo.h>
#include <libcli.h>

#include "md5.h"
#include "l2tpns.h"
#include "cluster.h"
#include "plugin.h"
#include "ll.h"
#include "constants.h"
#include "control.h"
#include "util.h"
#include "tbf.h"

// Globals
struct configt *config = NULL;  // all configuration
int tapfd = -1;                 // tap interface file handle
int udpfd = -1;                 // UDP file handle
int controlfd = -1;             // Control signal handle
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
time_t basetime = 0;            // base clock
char hostname[1000] = "";       // us.
u16 tapmac[3];                  // MAC of tap interface
int tapidx;                     // ifr_ifindex of tap device
u32 sessionid = 0;              // session id for radius accounting
int syslog_log = 0;             // are we logging to syslog
FILE *log_stream = NULL;
struct sockaddr_in snoop_addr = {0};
extern int cluster_sockfd;
u32 last_sid = 0;
int clifd = 0;
sessionidt *cli_session_kill = NULL;
tunnelidt *cli_tunnel_kill = NULL;
static void *ip_hash[256];
u32 udp_tx = 0, udp_rx = 0, udp_rx_pkt = 0;
u32 eth_tx = 0, eth_rx = 0, eth_rx_pkt = 0;
u32 ip_pool_size = 1;
time_t time_now = 0;
char time_now_string[64] = {0};
char main_quit = 0;
char *_program_name = NULL;
linked_list *loaded_plugins;
linked_list *plugins[MAX_PLUGIN_TYPES];

#ifdef BGP
#include "bgp.h"
struct bgp_peer *bgp_peers = 0;
struct bgp_route_list *bgp_routes = 0;
int bgp_configured = 0;
#endif /* BGP */

#define membersize(STRUCT, MEMBER) sizeof(((STRUCT *)0)->MEMBER)
#define CONFIG(NAME, MEMBER, TYPE) { NAME, offsetof(struct configt, MEMBER), membersize(struct configt, MEMBER), TYPE }

struct config_descriptt config_values[] = {
        CONFIG("debug", debug, INT),
        CONFIG("log_file", log_filename, STRING),
        CONFIG("l2tp_secret", l2tpsecret, STRING),
        CONFIG("primary_dns", default_dns1, IP),
        CONFIG("secondary_dns", default_dns2, IP),
        CONFIG("save_state", save_state, BOOL),
        CONFIG("primary_radius", radiusserver[0], IP),
        CONFIG("secondary_radius", radiusserver[1], IP),
        CONFIG("radius_accounting", radius_accounting, BOOL),
        CONFIG("radius_secret", radiussecret, STRING),
        CONFIG("bind_address", bind_address, IP),
        CONFIG("send_garp", send_garp, BOOL),
        CONFIG("throttle_speed", rl_rate, UNSIGNED_LONG),
        CONFIG("accounting_dir", accounting_dir, STRING),
        CONFIG("setuid", target_uid, INT),
        CONFIG("dump_speed", dump_speed, BOOL),
        CONFIG("cleanup_interval", cleanup_interval, INT),
        CONFIG("multi_read_count", multi_read_count, INT),
        CONFIG("scheduler_fifo", scheduler_fifo, BOOL),
        CONFIG("icmp_rate", icmp_rate, INT),
        CONFIG("cluster_address", cluster_address, IP),
        CONFIG("cluster_interface", cluster_interface, STRING),
        CONFIG("cluster_hb_interval", cluster_hb_interval, INT),
        CONFIG("cluster_hb_timeout", cluster_hb_timeout, INT),
#ifdef BGP
        CONFIG("as_number", as_number, SHORT),
        CONFIG("bgp_peer1", bgp_peer[0], STRING),
        CONFIG("bgp_peer1_as", bgp_peer_as[0], SHORT),
        CONFIG("bgp_peer2", bgp_peer[1], STRING),
        CONFIG("bgp_peer2_as", bgp_peer_as[1], SHORT),
#endif /* BGP */
        { NULL, 0, 0, 0 },
};

char *plugin_functions[] = {
        NULL,
        "plugin_pre_auth",
        "plugin_post_auth",
        "plugin_packet_rx",
        "plugin_packet_tx",
        "plugin_timer",
        "plugin_new_session",
        "plugin_kill_session",
        "plugin_control",
        "plugin_radius_response",
        "plugin_become_master",
        "plugin_new_session_master",
};

#define max_plugin_functions (sizeof(plugin_functions) / sizeof(char *))

tunnelt *tunnel = NULL;         // 1000 * 45 = 45000 = 45k
sessiont *session = NULL;       // 5000 * 213 = 1065000 = 1 Mb
sessioncountt *sess_count = NULL;
radiust *radius = NULL;
ippoolt *ip_address_pool = NULL;
controlt *controlfree = 0;
struct Tstats *_statistics = NULL;
#ifdef RINGBUFFER
struct Tringbuffer *ringbuffer = NULL;
#endif

void sigalrm_handler(int);
void sighup_handler(int);
void sigterm_handler(int);
void sigquit_handler(int);
void sigchild_handler(int);
void read_config_file();
void read_state();
void dump_state();
void tunnel_clean();
tunnelidt new_tunnel();
void update_config();

static void cache_ipmap(ipt ip, int s);
static void uncache_ipmap(ipt ip);

// return internal time (10ths since run)
clockt now(void)
{
        struct timeval t;
        gettimeofday(&t, 0);
        return (t.tv_sec - basetime) * 10 + t.tv_usec / 100000 + 1;
}

// work out a retry time based on try number
clockt backoff(u8 try)
{
        if (try > 5) try = 5;                  // max backoff
        return now() + 10 * (1 << try);
}

void _log(int level, ipt address, sessionidt s, tunnelidt t, const char *format, ...)
{
        static char message[65536] = {0};
        static char message2[65536] = {0};
        va_list ap;

#ifdef RINGBUFFER
        if (ringbuffer)
        {
                if (++ringbuffer->tail >= RINGBUFFER_SIZE)
                        ringbuffer->tail = 0;
                if (ringbuffer->tail == ringbuffer->head)
                        if (++ringbuffer->head >= RINGBUFFER_SIZE)
                                ringbuffer->head = 0;

                ringbuffer->buffer[ringbuffer->tail].level = level;
                ringbuffer->buffer[ringbuffer->tail].address = address;
                ringbuffer->buffer[ringbuffer->tail].session = s;
                ringbuffer->buffer[ringbuffer->tail].tunnel = t;
                va_start(ap, format);
                vsnprintf(ringbuffer->buffer[ringbuffer->tail].message, 4095, format, ap);
                va_end(ap);
        }
#endif

        if (config->debug < level) return;

        va_start(ap, format);
        if (log_stream)
        {
                vsnprintf(message2, 65535, format, ap);
                snprintf(message, 65535, "%s %02d/%02d %s", time_now_string, t, s, message2);
                fprintf(log_stream, "%s", message);
        }
        else if (syslog_log)
        {
                vsnprintf(message2, 65535, format, ap);
                snprintf(message, 65535, "%02d/%02d %s", t, s, message2);
                syslog(level + 2, message); // We don't need LOG_EMERG or LOG_ALERT
        }
        va_end(ap);
}

void _log_hex(int level, ipt address, sessionidt s, tunnelidt t, const char *title, const char *data, int maxsize)
{
        int i, j;
        const u8 *d = (const u8 *)data;

        if (config->debug < level) return;

        // No support for log_hex to syslog
        if (log_stream)
        {
                log(level, address, s, t, "%s (%d bytes):\n", title, maxsize);
                setvbuf(log_stream, NULL, _IOFBF, 16384);

                for (i = 0; i < maxsize; )
                {
                        fprintf(log_stream, "%4X: ", i);
                        for (j = i; j < maxsize && j < (i + 16); j++)
                        {
                                fprintf(log_stream, "%02X ", d[j]);
                                if (j == i + 7)
                                        fputs(": ", log_stream);
                        }

                        for (; j < i + 16; j++)
                        {
                                fputs("   ", log_stream);
                                if (j == i + 7)
                                        fputs(": ", log_stream);
                        }

                        fputs("  ", log_stream);
                        for (j = i; j < maxsize && j < (i + 16); j++)
                        {
                                if (d[j] >= 0x20 && d[j] < 0x7f && d[j] != 0x20)
                                        fputc(d[j], log_stream);
                                else
                                        fputc('.', log_stream);

                                if (j == i + 7)
                                        fputs("  ", log_stream);
                        }

                        i = j;
                        fputs("\n", log_stream);
                }

                fflush(log_stream);
                setbuf(log_stream, NULL);
        }
}


// Add a route
//
// This adds it to the routing table, advertises it
// via iBGP if enabled, and stuffs it into the
// 'sessionbyip' cache.
//
// 'ip' and 'mask' must be in _host_ order.
//
void routeset(sessionidt s, ipt ip, ipt mask, ipt gw, u8 add)
{
        struct rtentry r;
        int i;

        if (!mask) mask = 0xffffffff;

        ip &= mask;             // Force the ip to be the first one in the route.

        memset(&r, 0, sizeof(r));
        r.rt_dev = config->tapdevice;
        r.rt_dst.sa_family = AF_INET;
        *(u32 *) & (((struct sockaddr_in *) &r.rt_dst)->sin_addr.s_addr) = htonl(ip);
        r.rt_gateway.sa_family = AF_INET;
        *(u32 *) & (((struct sockaddr_in *) &r.rt_gateway)->sin_addr.s_addr) = htonl(gw);
        r.rt_genmask.sa_family = AF_INET;
        *(u32 *) & (((struct sockaddr_in *) &r.rt_genmask)->sin_addr.s_addr) = htonl(mask);
        r.rt_flags = (RTF_UP | RTF_STATIC);
        if (gw)
                r.rt_flags |= RTF_GATEWAY;
        else if (mask == 0xffffffff)
                r.rt_flags |= RTF_HOST;

        log(1, ip, 0, 0, "Route %s %u.%u.%u.%u/%u.%u.%u.%u %u.%u.%u.%u\n",
            add ? "add" : "del",
            ip   >> 24, ip   >> 16 & 0xff, ip   >> 8 & 0xff, ip   & 0xff,
            mask >> 24, mask >> 16 & 0xff, mask >> 8 & 0xff, mask & 0xff,
            gw   >> 24, gw   >> 16 & 0xff, gw   >> 8 & 0xff, gw   & 0xff);

        if (ioctl(ifrfd, add ? SIOCADDRT : SIOCDELRT, (void *) &r) < 0)
                log(0, 0, 0, 0, "routeset() error in ioctl: %s\n", strerror(errno));

#ifdef BGP
        if (add)
                bgp_add_route(htonl(ip), htonl(mask));
        else
                bgp_del_route(htonl(ip), htonl(mask));
#endif /* BGP */

                // Add/Remove the IPs to the 'sessionbyip' cache.
                // Note that we add the zero address in the case of 
                // a network route. Roll on CIDR.

                // Note that 's == 0' implies this is the address pool.
                // We still cache it here, because it will pre-fill
                // the malloc'ed tree.

        if (s)
        {
                if (!add)       // Are we deleting a route?
                        s = 0;  // Caching the session as '0' is the same as uncaching.

                for (i = ip; (i&mask) == (ip&mask) ; ++i)
                        cache_ipmap(i, s);
        }
}

// Set up TAP interface
void inittap(void)
{
        struct ifreq ifr;
        struct sockaddr_in sin = {0};
        memset(&ifr, 0, sizeof(ifr));
        ifr.ifr_flags = IFF_TUN;

        tapfd = open(TAPDEVICE, O_RDWR);
        if (tapfd < 0)
        {                          // fatal
                log(0, 0, 0, 0, "Can't open %s: %s\n", TAPDEVICE, strerror(errno));
                exit(1);
        }
        {
                int flags = fcntl(tapfd, F_GETFL, 0);
                fcntl(tapfd, F_SETFL, flags | O_NONBLOCK);
        }
        if (ioctl(tapfd, TUNSETIFF, (void *) &ifr) < 0)
        {
                log(0, 0, 0, 0, "Can't set tap interface: %s\n", strerror(errno));
                exit(1);
        }
        assert(strlen(ifr.ifr_name) < sizeof(config->tapdevice));
        strncpy(config->tapdevice, ifr.ifr_name, sizeof(config->tapdevice) - 1);
        ifrfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);

        sin.sin_family = AF_INET;
        sin.sin_addr.s_addr = config->bind_address ? config->bind_address : 0x01010101; // 1.1.1.1
        memcpy(&ifr.ifr_addr, &sin, sizeof(struct sockaddr));

        if (ioctl(ifrfd, SIOCSIFADDR, (void *) &ifr) < 0)
        {
                log(0, 0, 0, 0, "Error setting tun address: %s\n", strerror(errno));
                exit(1);
        }
        /* Bump up the qlen to deal with bursts from the network */
        ifr.ifr_qlen = 1000;
        if (ioctl(ifrfd, SIOCSIFTXQLEN, (void *) &ifr) < 0)
        {
                log(0, 0, 0, 0, "Error setting tun queue length: %s\n", strerror(errno));
                exit(1);
        }
        ifr.ifr_flags = IFF_UP;
        if (ioctl(ifrfd, SIOCSIFFLAGS, (void *) &ifr) < 0)
        {
                log(0, 0, 0, 0, "Error setting tun flags: %s\n", strerror(errno));
                exit(1);
        }
        if (ioctl(ifrfd, SIOCGIFHWADDR, (void *) &ifr) < 0)
        {
                log(0, 0, 0, 0, "Error setting tun hardware address: %s\n", strerror(errno));
                exit(1);
        }
        memcpy(&tapmac, 2 + (u8 *) & ifr.ifr_hwaddr, 6);
        if (ioctl(ifrfd, SIOCGIFINDEX, (void *) &ifr) < 0)
        {
                log(0, 0, 0, 0, "Error setting tun ifindex: %s\n", strerror(errno));
                exit(1);
        }
        tapidx = ifr.ifr_ifindex;
}

// set up UDP port
void initudp(void)
{
        int on = 1;
        struct sockaddr_in addr;

        // Tunnel
        memset(&addr, 0, sizeof(addr));
        addr.sin_family = AF_INET;
        addr.sin_port = htons(L2TPPORT);
        addr.sin_addr.s_addr = config->bind_address;
        udpfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
        setsockopt(udpfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
        {
                int flags = fcntl(udpfd, F_GETFL, 0);
                fcntl(udpfd, F_SETFL, flags | O_NONBLOCK);
        }
        if (bind(udpfd, (void *) &addr, sizeof(addr)) < 0)
        {
                log(0, 0, 0, 0, "Error in UDP bind: %s\n", strerror(errno));
                exit(1);
        }
        snoopfd = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
        snoop_addr.sin_family = AF_INET;

        // Control
        memset(&addr, 0, sizeof(addr));
        addr.sin_family = AF_INET;
        addr.sin_port = htons(1702);
        controlfd = socket(AF_INET, SOCK_DGRAM, 17);
        setsockopt(controlfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
        if (bind(controlfd, (void *) &addr, sizeof(addr)) < 0)
        {
                log(0, 0, 0, 0, "Error in control bind: %s\n", strerror(errno));
                exit(1);
        }
}

//
// Find session by IP, < 1 for not found
//
// Confusingly enough, this 'ip' must be
// in _network_ order. This being the common
// case when looking it up from IP packet headers.
//
// We actually use this cache for two things.
// #1. For used IP addresses, this maps to the
// session ID that it's used by.
// #2. For un-used IP addresses, this maps to the
// index into the pool table that contains that
// IP address.
//

int lookup_ipmap(ipt ip)
{
        u8 *a = (u8 *)&ip;
        char **d = (char **) ip_hash;
        int s;

        if (!(d = (char **) d[(size_t) *a++])) return 0;
        if (!(d = (char **) d[(size_t) *a++])) return 0;
        if (!(d = (char **) d[(size_t) *a++])) return 0;

        s = (ipt) d[(size_t) *a];
        return s;
}

sessionidt sessionbyip(ipt ip)
{
        int s = lookup_ipmap(ip);
        CSTAT(call_sessionbyip);

        if (s > 0 && s < MAXSESSION && session[s].tunnel)
                return s;
        return 0;
}

//
// Take an IP address in HOST byte order and
// add it to the sessionid by IP cache.
//
// (It's actually cached in network order)
//
static void cache_ipmap(ipt ip, int s)
{
        ipt nip = htonl(ip);            // MUST be in network order. I.e. MSB must in be ((char*)(&ip))[0]
        u8 *a = (u8 *) &nip;
        char **d = (char **) ip_hash;
        int i;

        for (i = 0; i < 3; i++)
        {
                if (!d[(size_t) a[i]])
                {
                        if (!(d[(size_t) a[i]] = calloc(256, sizeof (void *))))
                                return;
                }

                d = (char **) d[(size_t) a[i]];
        }

        d[(size_t) a[3]] = (char *)((int)s);

        if (s > 0)
                log(4, ip, s, session[s].tunnel, "Caching ip address %s\n", inet_toa(nip));
        else if (s == 0)
                log(4, ip, 0, 0, "Un-caching ip address %s\n", inet_toa(nip));
        // else a map to an ip pool index.
}

static void uncache_ipmap(ipt ip)
{
        cache_ipmap(ip, 0);     // Assign it to the NULL session.
}

//
// CLI list to dump current ipcache.
//
int cmd_show_ipcache(struct cli_def *cli, char *command, char **argv, int argc)
{
        char **d = (char **) ip_hash, **e, **f, **g;
        int i, j, k, l;
        int count = 0;

        if (CLI_HELP_REQUESTED)
                return CLI_HELP_NO_ARGS;

        cli_print(cli, "%7s %s", "Sess#", "IP Address");

        for (i = 0; i < 256; ++i) {
                if (!d[i]) continue;
                e = (char**) d[i];
                for (j = 0; j < 256; ++j) {
                        if (!e[j]) continue;
                        f = (char**) e[j];
                        for (k = 0; k < 256; ++k) {
                                if (!f[k]) continue;
                                g = (char**)f[k];
                                for (l = 0; l < 256; ++l) {
                                        if (!g[l]) continue;
                                        cli_print(cli, "%7d %d.%d.%d.%d",  (int) g[l], i, j, k, l);
                                        ++count;
                                }
                        }
                }
        }
        cli_print(cli, "%d entries in cache", count);
        return CLI_OK;
}


// Find session by username, 0 for not found
// walled garden users aren't authenticated, so the username is
// reasonably useless. Ignore them to avoid incorrect actions
//
// This is VERY inefficent. Don't call it often. :)
//
sessionidt sessionbyuser(char *username)
{
        int s;
        CSTAT(call_sessionbyuser);

        for (s = 1; s < MAXSESSION ; ++s) {
                if (session[s].walled_garden)
                        continue;               // Skip walled garden users.

                if (!strncmp(session[s].user, username, 128))
                        return s;

        }
        return 0;       // Not found.
}

void send_garp(ipt ip)
{
        int s;
        struct ifreq ifr;
        u8 mac[6];

        s = socket(PF_INET, SOCK_DGRAM, 0);
        if (s < 0)
        {
                log(0, 0, 0, 0, "Error creating socket for GARP: %s\n", strerror(errno));
                return;
        }
        memset(&ifr, 0, sizeof(ifr));
        strncpy(ifr.ifr_name, "eth0", sizeof(ifr.ifr_name) - 1);
        if (ioctl(s, SIOCGIFHWADDR, &ifr) < 0)
        {
                log(0, 0, 0, 0, "Error getting eth0 hardware address for GARP: %s\n", strerror(errno));
                close(s);
                return;
        }
        memcpy(mac, &ifr.ifr_hwaddr.sa_data, 6*sizeof(char));
        if (ioctl(s, SIOCGIFINDEX, &ifr) < 0)
        {
                log(0, 0, 0, 0, "Error getting eth0 interface index for GARP: %s\n", strerror(errno));
                close(s);
                return;
        }
        close(s);
        sendarp(ifr.ifr_ifindex, mac, ip);
}

// Find session by username, 0 for not found
sessiont *sessiontbysessionidt(sessionidt s)
{
        if (!s || s > MAXSESSION) return NULL;
        return &session[s];
}

sessionidt sessionidtbysessiont(sessiont *s)
{
        sessionidt val = s-session;
        if (s < session || val > MAXSESSION) return 0;
        return val;
}

// Handle ARP requests
void processarp(u8 * buf, int len)
{
        ipt ip;
        sessionidt s;

        CSTAT(call_processarp);
        STAT(arp_recv);

        if (len != 46)
        {
                log(0, 0, 0, 0, "Unexpected length ARP %d bytes\n", len);
                STAT(arp_errors);
                return;
        }
        if (*(u16 *) (buf + 16) != htons(PKTARP))
        {
                log(0, 0, 0, 0, "Unexpected ARP type %04X\n", ntohs(*(u16 *) (buf + 16)));
                STAT(arp_errors);
                return;
        }
        if (*(u16 *) (buf + 18) != htons(0x0001))
        {
                log(0, 0, 0, 0, "Unexpected ARP hard type %04X\n", ntohs(*(u16 *) (buf + 18)));
                STAT(arp_errors);
                return;
        }
        if (*(u16 *) (buf + 20) != htons(PKTIP))
        {
                log(0, 0, 0, 0, "Unexpected ARP prot type %04X\n", ntohs(*(u16 *) (buf + 20)));
                STAT(arp_errors);
                return;
        }
        if (buf[22] != 6)
        {
                log(0, 0, 0, 0, "Unexpected ARP hard len %d\n", buf[22]);
                STAT(arp_errors);
                return;
        }
        if (buf[23] != 4)
        {
                log(0, 0, 0, 0, "Unexpected ARP prot len %d\n", buf[23]);
                STAT(arp_errors);
                return;
        }
        if (*(u16 *) (buf + 24) != htons(0x0001))
        {
                log(0, 0, 0, 0, "Unexpected ARP op %04X\n", ntohs(*(u16 *) (buf + 24)));
                STAT(arp_errors);
                return;
        }
        ip = *(u32 *) (buf + 42);
        // look up session
        s = sessionbyip(ip);
        if (s)
        {
                log(3, ntohl(ip), s, session[s].tunnel, "ARP reply for %s\n", inet_toa(ip));
                memcpy(buf + 4, buf + 10, 6); // set destination as source
                *(u16 *) (buf + 10) = htons(tapmac[0]); // set source address
                *(u16 *) (buf + 12) = htons(tapmac[1]);
                *(u16 *) (buf + 14) = htons(tapmac[2]);
                *(u16 *) (buf + 24) = htons(0x0002); // ARP reply
                memcpy(buf + 26, buf + 10, 6); // sender ethernet
                memcpy(buf + 36, buf + 4, 6); // target ethernet
                *(u32 *) (buf + 42) = *(u32 *) (buf + 32); // target IP
                *(u32 *) (buf + 32) = ip; // sender IP
                write(tapfd, buf, len);
                STAT(arp_replies);
        }
        else
        {
                log(3, ntohl(ip), 0, 0, "ARP request for unknown IP %s\n", inet_toa(ip));
                STAT(arp_discarded);
        }
}

// actually send a control message for a specific tunnel
void tunnelsend(u8 * buf, u16 l, tunnelidt t)
{
        struct sockaddr_in addr;

        CSTAT(call_tunnelsend);

        if (!t)
        {
                static int backtrace_count = 0;
                log(0, 0, 0, t, "tunnelsend called with 0 as tunnel id\n");
                STAT(tunnel_tx_errors);
                log_backtrace(backtrace_count, 5)
                return;
        }

        if (!tunnel[t].ip)
        {
                static int backtrace_count = 0;
                log(1, 0, 0, t, "Error sending data out tunnel: no remote endpoint (tunnel not set up)\n");
                log_backtrace(backtrace_count, 5)
                STAT(tunnel_tx_errors);
                return;
        }
        memset(&addr, 0, sizeof(addr));
        addr.sin_family = AF_INET;
        *(u32 *) & addr.sin_addr = htonl(tunnel[t].ip);
        addr.sin_port = htons(tunnel[t].port);

        // sequence expected, if sequence in message
        if (*buf & 0x08) *(u16 *) (buf + ((*buf & 0x40) ? 10 : 8)) = htons(tunnel[t].nr);

        // If this is a control message, deal with retries
        if (*buf & 0x80)
        {
                tunnel[t].last = time_now; // control message sent
                tunnel[t].retry = backoff(tunnel[t].try); // when to resend
                if (tunnel[t].try > 1)
                {
                        STAT(tunnel_retries);
                        log(3, tunnel[t].ip, 0, t, "Control message resend try %d\n", tunnel[t].try);
                }
        }

        if (sendto(udpfd, buf, l, 0, (void *) &addr, sizeof(addr)) < 0)
        {
                log(0, tunnel[t].ip, ntohs((*(u16 *) (buf + 6))), t, "Error sending data out tunnel: %s (udpfd=%d, buf=%p, len=%d, dest=%s)\n",
                                strerror(errno), udpfd, buf, l, inet_ntoa(addr.sin_addr));
                STAT(tunnel_tx_errors);
                return;
        }

        log_hex(5, "Send Tunnel Data", buf, l);
        STAT(tunnel_tx_packets);
        INC_STAT(tunnel_tx_bytes, l);
}

//
// Tiny helper function to write data to
// the 'tun' device.
//
int tun_write(u8 * data, int size)
{
        return write(tapfd, data, size);
}

// process outgoing (to tunnel) IP
//
void processipout(u8 * buf, int len)
{
        sessionidt s;
        sessiont *sp;
        tunnelidt t;
        ipt ip;

        char * data = buf;      // Keep a copy of the originals.
        int size = len;

        u8 b[MAXETHER + 20];

        CSTAT(call_processipout);

        if (len < MIN_IP_SIZE)
        {
                log(1, 0, 0, 0, "Short IP, %d bytes\n", len);
                STAT(tunnel_tx_errors);
                return;
        }
        if (len >= MAXETHER)
        {
                log(1, 0, 0, 0, "Oversize IP packet %d bytes\n", len);
                STAT(tunnel_tx_errors);
                return;
        }

        // Skip the tun header
        buf += 4;
        len -= 4;

        // Got an IP header now
        if (*(u8 *)(buf) >> 4 != 4)
        {
                log(1, 0, 0, 0, "IP: Don't understand anything except IPv4\n");
                return;
        }

        ip = *(u32 *)(buf + 16);
        if (!(s = sessionbyip(ip)))
        {
                // 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.
                {
                        log(4, 0, 0, 0, "IP: Sending ICMP host unreachable to %s\n", inet_toa(*(u32 *)(buf + 12)));
                        host_unreachable(*(u32 *)(buf + 12), *(u16 *)(buf + 4), ip, buf, (len < 64) ? 64 : len);
                }
                return;
        }
        t = session[s].tunnel;
        sp = &session[s];

        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;
        }

        // 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);

        log(5, session[s].ip, s, t, "Ethernet -> Tunnel (%d bytes)\n", len);

        // Add on L2TP header
        {
                u8 *p = makeppp(b, sizeof(b), buf, len, t, s, PPPIP);
                if (!p) {
                        log(3, session[s].ip, s, t, "failed to send packet in processipout.\n");
                        return;
                }
                tunnelsend(b, len + (p-b), t); // send it...
        }

        sp->cout += len; // byte count
        sp->total_cout += len; // byte count
        sp->pout++;
        udp_tx += len;
        sess_count[s].cout += len;      // To send to master..
}

//
// Helper routine for the TBF filters.
// Used to send queued data in to the user!
//
void send_ipout(sessionidt s, u8 *buf, int len)
{
        sessiont *sp;
        tunnelidt t;
        ipt ip;

        u8 b[MAXETHER + 20];

        if (len < 0 || len > MAXETHER) {
                log(1,0,0,0, "Odd size IP packet: %d bytes\n", len);
                return;
        }

        // Skip the tun header
        buf += 4;
        len -= 4;

        ip = *(u32 *)(buf + 16);

        if (!session[s].ip)
                return;
        t = session[s].tunnel;
        sp = &session[s];

        log(5, session[s].ip, s, t, "Ethernet -> Tunnel (%d bytes)\n", len);

        // 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);

        // Add on L2TP header
        {
                u8 *p = makeppp(b, sizeof(b),  buf, len, t, s, PPPIP);
                if (!p) {
                        log(3, session[s].ip, s, t, "failed to send packet in send_ipout.\n");
                        return;
                }
                tunnelsend(b, len + (p-b), t); // send it...
        }
        sp->cout += len; // byte count
        sp->total_cout += len; // byte count
        sp->pout++;
        udp_tx += len;
        sess_count[s].cout += len;      // To send to master..
}

// add an AVP (16 bit)
void control16(controlt * c, u16 avp, u16 val, u8 m)
{
        u16 l = (m ? 0x8008 : 0x0008);
        *(u16 *) (c->buf + c->length + 0) = htons(l);
        *(u16 *) (c->buf + c->length + 2) = htons(0);
        *(u16 *) (c->buf + c->length + 4) = htons(avp);
        *(u16 *) (c->buf + c->length + 6) = htons(val);
        c->length += 8;
}

// add an AVP (32 bit)
void control32(controlt * c, u16 avp, u32 val, u8 m)
{
        u16 l = (m ? 0x800A : 0x000A);
        *(u16 *) (c->buf + c->length + 0) = htons(l);
        *(u16 *) (c->buf + c->length + 2) = htons(0);
        *(u16 *) (c->buf + c->length + 4) = htons(avp);
        *(u32 *) (c->buf + c->length + 6) = htonl(val);
        c->length += 10;
}

// add an AVP (32 bit)
void controls(controlt * c, u16 avp, char *val, u8 m)
{
        u16 l = ((m ? 0x8000 : 0) + strlen(val) + 6);
        *(u16 *) (c->buf + c->length + 0) = htons(l);
        *(u16 *) (c->buf + c->length + 2) = htons(0);
        *(u16 *) (c->buf + c->length + 4) = htons(avp);
        memcpy(c->buf + c->length + 6, val, strlen(val));
        c->length += 6 + strlen(val);
}

// add a binary AVP
void controlb(controlt * c, u16 avp, char *val, unsigned int len, u8 m)
{
        u16 l = ((m ? 0x8000 : 0) + len + 6);
        *(u16 *) (c->buf + c->length + 0) = htons(l);
        *(u16 *) (c->buf + c->length + 2) = htons(0);
        *(u16 *) (c->buf + c->length + 4) = htons(avp);
        memcpy(c->buf + c->length + 6, val, len);
        c->length += 6 + len;
}

// new control connection
controlt *controlnew(u16 mtype)
{
        controlt *c;
        if (!controlfree)
                c = malloc(sizeof(controlt));
        else
        {
                c = controlfree;
                controlfree = c->next;
        }
        assert(c);
        c->next = 0;
        *(u16 *) (c->buf + 0) = htons(0xC802); // flags/ver
        c->length = 12;
        control16(c, 0, mtype, 1);
        return c;
}

// send zero block if nothing is waiting
// (ZLB send).
void controlnull(tunnelidt t)
{
        u8 buf[12];
        if (tunnel[t].controlc) // Messages queued; They will carry the ack.
                return;

        *(u16 *) (buf + 0) = htons(0xC802); // flags/ver
        *(u16 *) (buf + 2) = htons(12); // length
        *(u16 *) (buf + 4) = htons(tunnel[t].far); // tunnel
        *(u16 *) (buf + 6) = htons(0); // session
        *(u16 *) (buf + 8) = htons(tunnel[t].ns); // sequence
        *(u16 *) (buf + 10) = htons(tunnel[t].nr); // sequence
        tunnelsend(buf, 12, t);
}

// add a control message to a tunnel, and send if within window
void controladd(controlt * c, tunnelidt t, sessionidt s)
{
        *(u16 *) (c->buf + 2) = htons(c->length); // length
        *(u16 *) (c->buf + 4) = htons(tunnel[t].far); // tunnel
        *(u16 *) (c->buf + 6) = htons(s ? session[s].far : 0); // session
        *(u16 *) (c->buf + 8) = htons(tunnel[t].ns); // sequence
        tunnel[t].ns++;              // advance sequence
        // link in message in to queue
        if (tunnel[t].controlc)
                tunnel[t].controle->next = c;
        else
                tunnel[t].controls = c;
        tunnel[t].controle = c;
        tunnel[t].controlc++;
        // send now if space in window
        if (tunnel[t].controlc <= tunnel[t].window)
        {
                tunnel[t].try = 0;      // first send
                tunnelsend(c->buf, c->length, t);
        }
}

//
// Throttle or Unthrottle a session
//
// Throttle the data folling through a session
// to be no more than 'throttle' kbit/sec each way.
//
int throttle_session(sessionidt s, int throttle)
{
        if (!session[s].tunnel)
                return 0;       // No-one home.

        if (!*session[s].user)
                return 0; // User not logged in

        if (throttle) {
                if (session[s].tbf_in || session[s].tbf_out) {
                        if (throttle == session[s].throttle)
                                return 1;

                        // Currently throttled but the rate is changing.

                        free_tbf(session[s].tbf_in);
                        free_tbf(session[s].tbf_out);
                }

                session[s].tbf_in = new_tbf(s, throttle*1024/4, throttle*1024/8, send_ipin);
                session[s].tbf_out = new_tbf(s, throttle*1024/4, throttle*1024/8, send_ipout);

                if (throttle != session[s].throttle) {  // Changed. Flood to slaves.
                        session[s].throttle = throttle;
                        cluster_send_session(s);
                }

                return 1;
        }

        // else Unthrottling.

        if (!session[s].tbf_in && !session[s].tbf_out && !session[s].throttle)
                return 0;

        free_tbf(session[s].tbf_in);
        session[s].tbf_in = 0;

        free_tbf(session[s].tbf_out);
        session[s].tbf_out = 0;

        if (throttle != session[s].throttle) {  // Changed. Flood to slaves.
                session[s].throttle = throttle;
                cluster_send_session(s);
        }

        return 0;
}

// start tidy shutdown of session
void sessionshutdown(sessionidt s, char *reason)
{
        int dead = session[s].die;
        int walled_garden = session[s].walled_garden;


        CSTAT(call_sessionshutdown);

        if (!session[s].tunnel)
        {
                log(3, session[s].ip, s, session[s].tunnel, "Called sessionshutdown on a session with no tunnel.\n");
                return;                   // not a live session
        }

        if (!session[s].die)
                log(2, 0, s, session[s].tunnel, "Shutting down session %d: %s\n", s, reason);

        session[s].die = now() + 150; // Clean up in 15 seconds

        {
                struct param_kill_session data = { &tunnel[session[s].tunnel], &session[s] };
                run_plugins(PLUGIN_KILL_SESSION, &data);
        }

        // RADIUS Stop message
        if (session[s].opened && !walled_garden && !dead) {
                u16 r = session[s].radius;
                if (!r)
                {
                        if (!(r = radiusnew(s)))
                        {
                                log(1, 0, s, session[s].tunnel, "No free RADIUS sessions for Stop message\n");
                                STAT(radius_overflow);
                        }
                        else
                        {
                                int n;
                                for (n = 0; n < 15; n++)
                                        radius[r].auth[n] = rand();
                        }
                }
                if (r && radius[r].state != RADIUSSTOP)
                        radiussend(r, RADIUSSTOP); // stop, if not already trying
        }

        if (session[s].ip)
        {                          // IP allocated, clear and unroute
                int r;
                for (r = 0; r < MAXROUTE && session[s].route[r].ip; r++)
                {
                        routeset(s, session[s].route[r].ip, session[s].route[r].mask, session[s].ip, 0);
                        session[s].route[r].ip = 0;
                }

                if (session[s].ip_pool_index == -1) // static ip
                {
                        routeset(s, session[s].ip, 0, 0, 0);    // Delete route.
                        session[s].ip = 0;
                }
                else
                        free_ip_address(s);

                if (session[s].throttle)        // Unthrottle if throttled.
                        throttle_session(s, 0);
        }
        {                            // Send CDN
                controlt *c = controlnew(14); // sending CDN
                control16(c, 1, 3, 1);    // result code (admin reasons - TBA make error, general error, add message
                control16(c, 14, s, 1);   // assigned session (our end)
                controladd(c, session[s].tunnel, s); // send the message
        }
        cluster_send_session(s);
}

void sendipcp(tunnelidt t, sessionidt s)
{
        u8 buf[MAXCONTROL];
        u16 r = session[s].radius;
        u8 *q;

        CSTAT(call_sendipcp);

        if (!r)
                r = radiusnew(s);

        if (radius[r].state != RADIUSIPCP)
        {
                radius[r].state = RADIUSIPCP;
                radius[r].try = 0;
        }

        radius[r].retry = backoff(radius[r].try++);
        if (radius[r].try > 10)
        {
                radiusclear(r, s);      // Clear radius session.
                sessionshutdown(s, "No reply on IPCP");
                return;
        }

        q = makeppp(buf,sizeof(buf), 0, 0, t, s, PPPIPCP);
        if (!q) {
                log(3, session[s].ip, s, t, "failed to send packet in sendipcp.\n");
                return;
        }

        *q = ConfigReq;
        q[1] = r << RADIUS_SHIFT;                    // ID, dont care, we only send one type of request
        *(u16 *) (q + 2) = htons(10);
        q[4] = 3;
        q[5] = 6;
        *(u32 *) (q + 6) = config->bind_address; // send my IP
        tunnelsend(buf, 10 + (q - buf), t); // send it
        session[s].flags &= ~SF_IPCP_ACKED;     // Clear flag.
}

// kill a session now
void sessionkill(sessionidt s, char *reason)
{

        CSTAT(call_sessionkill);

        sessionshutdown(s, reason);  // close radius/routes, etc.
        if (session[s].radius)
                radiusclear(session[s].radius, 0); // cant send clean accounting data, session is killed

        log(2, 0, s, session[s].tunnel, "Kill session %d (%s): %s\n", s, session[s].user, reason);

        throttle_session(s, 0);         // Force session to be un-throttle. Free'ing TBF structures.

        memset(&session[s], 0, sizeof(session[s]));
        session[s].tunnel = T_FREE;     // Mark it as free.
        session[s].next = sessionfree;
        sessionfree = s;
        cluster_send_session(s);
}

// kill a tunnel now
void tunnelkill(tunnelidt t, char *reason)
{
        sessionidt s;
        controlt *c;

        CSTAT(call_tunnelkill);

        tunnel[t].state = TUNNELDIE;

        // free control messages
        while ((c = tunnel[t].controls))
        {
                controlt * n = c->next;
                tunnel[t].controls = n;
                tunnel[t].controlc--;
                c->next = controlfree;
                controlfree = c;
        }
        // kill sessions
        for (s = 1; s < MAXSESSION; s++)
                if (session[s].tunnel == t)
                        sessionkill(s, reason);

        // free tunnel
        tunnelclear(t);
        cluster_send_tunnel(t);
        log(1, 0, 0, t, "Kill tunnel %d: %s\n", t, reason);
        tunnel[t].die = 0;
        tunnel[t].state = TUNNELFREE;
}

// shut down a tunnel cleanly
void tunnelshutdown(tunnelidt t, char *reason)
{
        sessionidt s;

        CSTAT(call_tunnelshutdown);

        if (!tunnel[t].last || !tunnel[t].far || tunnel[t].state == TUNNELFREE)
        {
                // never set up, can immediately kill
                tunnelkill(t, reason);
                return;
        }
        log(1, 0, 0, t, "Shutting down tunnel %d (%s)\n", t, reason);

        // close session
        for (s = 1; s < MAXSESSION; s++)
                if (session[s].tunnel == t)
                        sessionkill(s, reason);

        tunnel[t].state = TUNNELDIE;
        tunnel[t].die = now() + 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
        }
}

// read and process packet on tunnel (UDP)
void processudp(u8 * buf, int len, struct sockaddr_in *addr)
{
        char *chapresponse = NULL;
        u16 l = len, t = 0, s = 0, ns = 0, nr = 0;
        u8 *p = buf + 2;


        CSTAT(call_processudp);

        udp_rx += len;
        udp_rx_pkt++;
        log_hex(5, "UDP Data", buf, len);
        STAT(tunnel_rx_packets);
        INC_STAT(tunnel_rx_bytes, len);
        if (len < 6)
        {
                log(1, ntohl(addr->sin_addr.s_addr), 0, 0, "Short UDP, %d bytes\n", len);
                STAT(tunnel_rx_errors);
                return;
        }
        if ((buf[1] & 0x0F) != 2)
        {
                log(1, ntohl(addr->sin_addr.s_addr), 0, 0, "Bad L2TP ver %d\n", (buf[1] & 0x0F) != 2);
                STAT(tunnel_rx_errors);
                return;
        }
        if (*buf & 0x40)
        {                          // length
                l = ntohs(*(u16 *) p);
                p += 2;
        }
        t = ntohs(*(u16 *) p);
        p += 2;
        s = ntohs(*(u16 *) p);
        p += 2;
        if (s >= MAXSESSION)
        {
                log(1, ntohl(addr->sin_addr.s_addr), s, t, "Received UDP packet with invalid session ID\n");
                STAT(tunnel_rx_errors);
                return;
        }
        if (t >= MAXTUNNEL)
        {
                log(1, ntohl(addr->sin_addr.s_addr), s, t, "Received UDP packet with invalid tunnel ID\n");
                STAT(tunnel_rx_errors);
                return;
        }
        if (*buf & 0x08)
        {                          // ns/nr
                ns = ntohs(*(u16 *) p);
                p += 2;
                nr = ntohs(*(u16 *) p);
                p += 2;
        }
        if (*buf & 0x02)
        {                          // offset
                u16 o = ntohs(*(u16 *) p);
                p += o + 2;
        }
        if ((p - buf) > l)
        {
                log(1, ntohl(addr->sin_addr.s_addr), s, t, "Bad length %d>%d\n", (p - buf), l);
                STAT(tunnel_rx_errors);
                return;
        }
        l -= (p - buf);
        if (*buf & 0x80)
        {                          // control
                u16 message = 0xFFFF; // message type
                u8 fatal = 0;
                u8 mandatorymessage = 0;
                u8 chap = 0;      // if CHAP being used
                u16 asession = 0;  // assigned session
                u32 amagic = 0;    // magic number
                u8 aflags = 0;    // flags from last LCF
                u16 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

                if (!config->cluster_iam_master) {
                        master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port);
                        return;
                }

                if ((*buf & 0xCA) != 0xC8)
                {
                        log(1, ntohl(addr->sin_addr.s_addr), s, t, "Bad control header %02X\n", *buf);
                        STAT(tunnel_rx_errors);
                        return;
                }
                log(3, ntohl(addr->sin_addr.s_addr), s, t, "Control message (%d bytes): (unacked %d) l-ns %d l-nr %d r-ns %d r-nr %d\n",
                                l, tunnel[t].controlc, tunnel[t].ns, tunnel[t].nr, ns, nr);
                // if no tunnel specified, assign one
                if (!t)
                {
                        int i;

                                //
                                // Is this a duplicate of the first packet? (SCCRQ)
                                //
                        for ( i = 1; i <= config->cluster_highest_tunnelid ; ++i) {
                                if (tunnel[t].state != TUNNELOPENING ||
                                        tunnel[t].ip != ntohl(*(ipt *) & addr->sin_addr) ||
                                        tunnel[t].port != ntohs(addr->sin_port) )
                                        continue;
                                t = i;
                                break;
                        }
                }

                if (!t) {
                        if (!(t = new_tunnel()))
                        {
                                log(1, ntohl(addr->sin_addr.s_addr), 0, 0, "No more tunnels\n");
                                STAT(tunnel_overflow);
                                return;
                        }
                        tunnelclear(t);
                        tunnel[t].ip = ntohl(*(ipt *) & addr->sin_addr);
                        tunnel[t].port = ntohs(addr->sin_port);
                        tunnel[t].window = 4; // default window
                        log(1, ntohl(addr->sin_addr.s_addr), 0, t, "   New tunnel from %u.%u.%u.%u/%u ID %d\n", tunnel[t].ip >> 24, tunnel[t].ip >> 16 & 255, tunnel[t].ip >> 8 & 255, tunnel[t].ip & 255, tunnel[t].port, t);
                        STAT(tunnel_created);
                }

                // This is used to time out old tunnels
                tunnel[t].lastrec = time_now;

                // check sequence of this message
                {
                        int skip = tunnel[t].window; // track how many in-window packets are still in queue
                                // some to clear maybe?
                        while (tunnel[t].controlc && (((tunnel[t].ns - tunnel[t].controlc) - nr) & 0x8000))
                        {
                                controlt *c = tunnel[t].controls;
                                tunnel[t].controls = c->next;
                                tunnel[t].controlc--;
                                c->next = controlfree;
                                controlfree = c;
                                skip--;
                                tunnel[t].try = 0; // we have progress
                        }

                                // If the 'ns' just received is not the 'nr' we're
                                // expecting, just send an ack and drop it.
                                //
                                // if 'ns' is less, then we got a retransmitted packet.
                                // if 'ns' is greater than missed a packet. Either way
                                // we should ignore it.
                        if (ns != tunnel[t].nr)
                        {
                                // is this the sequence we were expecting?
                                log(1, ntohl(addr->sin_addr.s_addr), 0, t, "   Out of sequence tunnel %d, (%d is not the expected %d)\n", t, ns, tunnel[t].nr);
                                STAT(tunnel_rx_errors);

                                if (l)  // Is this not a ZLB?
                                        controlnull(t);
                                return;
                        }
                        // receiver advance (do here so quoted correctly in any sends below)
                        if (l) tunnel[t].nr = (ns + 1);
                        if (skip < 0) skip = 0;
                        if (skip < tunnel[t].controlc)
                        {
                                // some control packets can now be sent that were previous stuck out of window
                                int tosend = tunnel[t].window - skip;
                                controlt *c = tunnel[t].controls;
                                while (c && skip)
                                {
                                        c = c->next;
                                        skip--;
                                }
                                while (c && tosend)
                                {
                                        tunnel[t].try = 0; // first send
                                        tunnelsend(c->buf, c->length, t);
                                        c = c->next;
                                        tosend--;
                                }
                        }
                        if (!tunnel[t].controlc)
                                tunnel[t].retry = 0; // caught up
                }
                if (l)
                {                     // if not a null message
                        // process AVPs
                        while (l && !(fatal & 0x80))
                        {
                                u16 n = (ntohs(*(u16 *) p) & 0x3FF);
                                u8 *b = p;
                                u8 flags = *p;
                                u16 mtype;
                                p += n;       // next
                                if (l < n)
                                {
                                        log(1, ntohl(addr->sin_addr.s_addr), s, t, "Invalid length in AVP\n");
                                        STAT(tunnel_rx_errors);
                                        fatal = flags;
                                        return;
                                }
                                l -= n;
                                if (flags & 0x40)
                                {
                                        // handle hidden AVPs
                                        if (!*config->l2tpsecret)
                                        {
                                                log(1, ntohl(addr->sin_addr.s_addr), s, t, "Hidden AVP requested, but no L2TP secret.\n");
                                                fatal = flags;
                                                continue;
                                        }
                                        if (!session[s].random_vector_length)
                                        {
                                                log(1, ntohl(addr->sin_addr.s_addr), s, t, "Hidden AVP requested, but no random vector.\n");
                                                fatal = flags;
                                                continue;
                                        }
                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "Hidden AVP\n");
                                }
                                if (*b & 0x3C)
                                {
                                        log(1, ntohl(addr->sin_addr.s_addr), s, t, "Unrecognised AVP flags %02X\n", *b);
                                        fatal = flags;
                                        continue; // next
                                }
                                b += 2;
                                if (*(u16 *) (b))
                                {
                                        log(2, ntohl(addr->sin_addr.s_addr), s, t, "Unknown AVP vendor %d\n", ntohs(*(u16 *) (b)));
                                        fatal = flags;
                                        continue; // next
                                }
                                b += 2;
                                mtype = ntohs(*(u16 *) (b));
                                b += 2;
                                n -= 6;

                                log(4, ntohl(addr->sin_addr.s_addr), s, t, "   AVP %d (%s) len %d\n", mtype, avpnames[mtype], n);
                                switch (mtype)
                                {
                                case 0:     // message type
                                        message = ntohs(*(u16 *) b);
                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Message type = %d (%s)\n", *b,
                                                        l2tp_message_types[message]);
                                        mandatorymessage = flags;
                                        break;
                                case 1:     // result code
                                        {
                                                u16 rescode = ntohs(*(u16 *)(b));
                                                const char* resdesc = "(unknown)";
                                                if (message == 4) { /* StopCCN */
                                                        if (rescode <= MAX_STOPCCN_RESULT_CODE)
                                                                resdesc = stopccn_result_codes[rescode];
                                                } else if (message == 14) { /* CDN */
                                                        if (rescode <= MAX_CDN_RESULT_CODE)
                                                                resdesc = cdn_result_codes[rescode];
                                                }

                                                log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Result Code %d: %s\n",
                                                        rescode, resdesc);
                                                if (n >= 4) {
                                                        u16 errcode = ntohs(*(u16 *)(b + 2));
                                                        const char* errdesc = "(unknown)";
                                                        if (errcode <= MAX_ERROR_CODE)
                                                                errdesc = error_codes[errcode];
                                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Error Code %d: %s\n",
                                                                errcode, errdesc);
                                                }
                                                if (n > 4) {
                                                        /* %*s doesn't work?? */
                                                        char *buf = (char *)strndup(b+4, n-4);
                                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Error String: %s\n",
                                                                buf);
                                                        free(buf);
                                                }
                                                break;
                                        }
                                        break;
                                case 2:     // protocol version
                                        {
                                                version = ntohs(*(u16 *) (b));
                                                log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Protocol version = %d\n", version);
                                                if (version && version != 0x0100)
                                                {   // allow 0.0 and 1.0
                                                        log(1, ntohl(addr->sin_addr.s_addr), s, t, "   Bad protocol version %04X\n",
                                                                        version);
                                                        fatal = flags;
                                                        continue; // next
                                                }
                                        }
                                        break;
                                case 3:     // framing capabilities
//                                      log(4, ntohl(addr->sin_addr.s_addr), s, t, "Framing capabilities\n");
                                        break;
                                case 4:     // bearer capabilities
//                                      log(4, ntohl(addr->sin_addr.s_addr), s, t, "Bearer capabilities\n");
                                        break;
                                case 5:         // tie breaker
                                        // We never open tunnels, so we don't care about tie breakers
//                                      log(4, ntohl(addr->sin_addr.s_addr), s, t, "Tie breaker\n");
                                        continue;
                                case 6:     // firmware revision
//                                      log(4, ntohl(addr->sin_addr.s_addr), 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);
                                        log(4, ntohl(addr->sin_addr.s_addr), 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);
                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Vendor name = \"%s\"\n", tunnel[t].vendor);
                                        break;
                                case 9:     // assigned tunnel
                                        tunnel[t].far = ntohs(*(u16 *) (b));
                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Remote tunnel id = %d\n", tunnel[t].far);
                                        break;
                                case 10:    // rx window
                                        tunnel[t].window = ntohs(*(u16 *) (b));
                                        if (!tunnel[t].window)
                                                tunnel[t].window = 1; // window of 0 is silly
                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "   rx window = %d\n", tunnel[t].window);
                                        break;
                                case 11:        // Challenge
                                        {
                                                log(4, ntohl(addr->sin_addr.s_addr), s, t, "   LAC requested CHAP authentication for tunnel\n");
                                                build_chap_response(b, 2, n, &chapresponse);
                                        }
                                        break;
                                case 14:    // assigned session
                                        asession = session[s].far = ntohs(*(u16 *) (b));
                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "   assigned session = %d\n", asession);
                                        break;
                                case 15:    // call serial number
                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "   call serial number = %d\n", ntohl(*(u32 *)b));
                                        break;
                                case 18:    // bearer type
                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "   bearer type = %d\n", ntohl(*(u32 *)b));
                                        // TBA - for RADIUS
                                        break;
                                case 19:    // framing type
                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "   framing type = %d\n", ntohl(*(u32 *)b));
                                        // TBA
                                        break;
                                case 21:    // called number
                                        memset(called, 0, MAXTEL);
                                        memcpy(called, b, (n >= MAXTEL) ? (MAXTEL-1) : n);
                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Called <%s>\n", called);
                                        break;
                                case 22:    // calling number
                                        memset(calling, 0, MAXTEL);
                                        memcpy(calling, b, (n >= MAXTEL) ? (MAXTEL-1) : n);
                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Calling <%s>\n", calling);
                                        break;
                                case 24:    // tx connect speed
                                        if (n == 4)
                                        {
                                                session[s].tx_connect_speed = ntohl(*(u32 *)b);
                                        }
                                        else
                                        {
                                                // AS5300s send connect speed as a string
                                                char tmp[30] = {0};
                                                memcpy(tmp, b, (n >= 30) ? 30 : n);
                                                session[s].tx_connect_speed = atol(tmp);
                                        }
                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "   TX connect speed <%u>\n",
                                                        session[s].tx_connect_speed);
                                        break;
                                case 38:    // rx connect speed
                                        if (n == 4)
                                        {
                                                session[s].rx_connect_speed = ntohl(*(u32 *)b);
                                        }
                                        else
                                        {
                                                // AS5300s send connect speed as a string
                                                char tmp[30] = {0};
                                                memcpy(tmp, b, (n >= 30) ? 30 : n);
                                                session[s].rx_connect_speed = atol(tmp);
                                        }
                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "   RX connect speed <%u>\n",
                                                        session[s].rx_connect_speed);
                                        break;
                                case 25:    // Physical Channel ID
                                        {
                                                u32 tmp = ntohl(*(u32 *)b);
                                                log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Physical Channel ID <%X>\n", tmp);
                                                break;
                                        }
                                case 29:    // Proxy Authentication Type
                                        {
                                                u16 authtype = ntohs(*(u16 *)b);
                                                log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Proxy Auth Type %d (%s)\n",
                                                        authtype, authtypes[authtype]);
                                                requestchap = (authtype == 2);
                                                break;
                                        }
                                case 30:    // Proxy Authentication Name
                                        {
                                                char authname[64] = {0};
                                                memcpy(authname, b, (n > 63) ? 63 : n);
                                                log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Proxy Auth Name (%s)\n",
                                                        authname);
                                                break;
                                        }
                                case 31:    // Proxy Authentication Challenge
                                        {
                                                memcpy(radius[session[s].radius].auth, b, 16);
                                                log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Proxy Auth Challenge\n");
                                                break;
                                        }
                                case 32:    // Proxy Authentication ID
                                        {
                                                u16 authid = ntohs(*(u16 *)(b));
                                                log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Proxy Auth ID (%d)\n",
                                                        authid);
                                                if (session[s].radius)
                                                        radius[session[s].radius].id = authid;
                                                break;
                                        }
                                case 33:    // Proxy Authentication Response
                                        {
                                                char authresp[64] = {0};
                                                memcpy(authresp, b, (n > 63) ? 63 : n);
                                                log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Proxy Auth Response\n");
                                                break;
                                        }
                                case 27:    // last send lcp
                                        {        // find magic number
                                                u8 *p = b, *e = p + n;
                                                while (p < e && p[1])
                                                {
                                                        if (*p == 5 && p[1] == 6)
                                                                amagic = ntohl(*(u32 *) (p + 2));
                                                        else if (*p == 3 && p[1] == 5 && *(u16 *) (p + 2) == htons(PPPCHAP) && p[4] == 5)
                                                                chap = 1;
                                                        else if (*p == 7)
                                                                aflags |= SESSIONPFC;
                                                        else if (*p == 8)
                                                                aflags |= SESSIONACFC;
                                                        p += p[1];
                                                }

                                                {
                                                        char tmp[500] = {0};
                                                        tmp[0] = ConfigReq;
                                                        memcpy((tmp + 1), b, n);
                                                }
                                        }
                                        break;
                                case 28:    // last recv lcp confreq
                                        {
                                                char tmp[500] = {0};
                                                tmp[0] = ConfigReq;
                                                memcpy((tmp + 1), b, n);
                                                break;
                                        }
                                case 26:    // Initial Received LCP CONFREQ
                                        {
                                                char tmp[500] = {0};
                                                tmp[0] = ConfigReq;
                                                memcpy((tmp + 1), b, n);
                                        }
                                        break;
                                case 39:    // seq required - we control it as an LNS anyway...
                                        break;
                                case 36:    // Random Vector
                                        log(4, ntohl(addr->sin_addr.s_addr), s, t, "   Random Vector received. Enabled AVP Hiding.\n");
                                        memset(session[s].random_vector, 0, sizeof(session[s].random_vector));
                                        memcpy(session[s].random_vector, b, n);
                                        session[s].random_vector_length = n;
                                        break;
                                default:
                                        log(2, ntohl(addr->sin_addr.s_addr), s, t, "   Unknown AVP type %d\n", mtype);
                                        fatal = flags;
                                        continue; // next
                                }
                        }
                        // process message
                        if (fatal & 0x80)
                                tunnelshutdown(t, "Unknown Mandatory AVP");
                        else
                                switch (message)
                                {
                                case 1:       // SCCRQ - Start Control Connection Request
                                        {
                                                controlt *c = controlnew(2); // sending SCCRP
                                                control16(c, 2, version, 1); // protocol version
                                                control32(c, 3, 3, 1); // framing
                                                controls(c, 7, tunnel[t].hostname, 1); // host name (TBA)
                                                if (chapresponse) controlb(c, 13, chapresponse, 16, 1); // Challenge response
                                                control16(c, 9, t, 1); // assigned tunnel
                                                controladd(c, t, s); // send the resply
                                        }
                                        tunnel[t].state = TUNNELOPENING;
                                        break;
                                case 2:       // SCCRP
                                        tunnel[t].state = TUNNELOPEN;
                                        break;
                                case 3:       // SCCN
                                        tunnel[t].state = TUNNELOPEN;
                                        controlnull(t); // ack
                                        break;
                                case 4:       // StopCCN
                                        controlnull(t); // ack
                                        tunnelshutdown(t, "Stopped"); // Shut down cleanly
                                        tunnelkill(t, "Stopped"); // Immediately force everything dead
                                        break;
                                case 6:       // HELLO
                                        controlnull(t); // simply ACK
                                        break;
                                case 7:       // OCRQ
                                        // TBA
                                        break;
                                case 8:       // OCRO
                                        // TBA
                                        break;
                                case 9:       // OCCN
                                        // TBA
                                        break;
                                case 10:      // ICRQ
                                        if (!sessionfree)
                                        {
                                                STAT(session_overflow);
                                                tunnelshutdown(t, "No free sessions");
                                        }
                                        else
                                        {
                                                u16 r;
                                                controlt *c;

                                                s = sessionfree;
                                                sessionfree = session[s].next;
                                                memset(&session[s], 0, sizeof(session[s]));

                                                if (s > config->cluster_highest_sessionid)
                                                        config->cluster_highest_sessionid = s;

                                                // make a RADIUS session
                                                if (!(r = radiusnew(s)))
                                                {
                                                        log(1, ntohl(addr->sin_addr.s_addr), s, t, "No free RADIUS sessions for ICRQ\n");
                                                        sessionkill(s, "no free RADIUS sesions");
                                                        return;
                                                }

                                                c = controlnew(11); // sending ICRP
                                                session[s].id = sessionid++;
                                                session[s].opened = time(NULL);
                                                session[s].tunnel = t;
                                                session[s].far = asession;
                                                session[s].last_packet = time_now;
                                                log(3, ntohl(addr->sin_addr.s_addr), s, t, "New session (%d/%d)\n", tunnel[t].far, session[s].far);
                                                control16(c, 14, s, 1); // assigned session
                                                controladd(c, t, s); // send the reply
                                                {
                                                        // Generate a random challenge
                                                        int n;
                                                        for (n = 0; n < 15; n++)
                                                                radius[r].auth[n] = rand();
                                                }
                                                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);
                                                STAT(session_created);
                                        }
                                        break;
                                case 11:      // ICRP
                                        // TBA
                                        break;
                                case 12:      // ICCN
                                        session[s].magic = amagic; // set magic number
                                        session[s].l2tp_flags = aflags; // set flags received
                                        log(3, ntohl(addr->sin_addr.s_addr), s, t, "Magic %X Flags %X\n", amagic, aflags);
                                        controlnull(t); // ack
                                        // In CHAP state, request PAP instead
                                        if (requestchap)
                                                initlcp(t, s);
                                        break;
                                case 14:      // CDN
                                        controlnull(t); // ack
                                        sessionshutdown(s, "Closed (Received CDN)");
                                        break;
                                case 0xFFFF:
                                        log(1, ntohl(addr->sin_addr.s_addr), s, t, "Missing message type\n");
                                        break;
                                default:
                                        STAT(tunnel_rx_errors);
                                        if (mandatorymessage & 0x80)
                                                tunnelshutdown(t, "Unknown message");
                                        else
                                                log(1, ntohl(addr->sin_addr.s_addr), s, t, "Unknown message type %d\n", message);
                                        break;
                                }
                        if (chapresponse) free(chapresponse);
                        cluster_send_tunnel(t);
                }
                else
                {
                        log(4, 0, s, t, "   Got a ZLB ack\n");
                }
        }
        else
        {                          // data
                u16 prot;

                log_hex(5, "Receive Tunnel Data", p, l);
                if (l > 2 && p[0] == 0xFF && p[1] == 0x03)
                {                     // HDLC address header, discard
                        p += 2;
                        l -= 2;
                }
                if (l < 2)
                {
                        log(1, ntohl(addr->sin_addr.s_addr), s, t, "Short ppp length %d\n", l);
                        STAT(tunnel_rx_errors);
                        return;
                }
                if (*p & 1)
                {
                        prot = *p++;
                        l--;
                }
                else
                {
                        prot = ntohs(*(u16 *) p);
                        p += 2;
                        l -= 2;
                }

                if (s && !session[s].tunnel)    // Is something wrong??
                {
                        if (!config->cluster_iam_master)
                        {
                                // Pass it off to the master to deal with..
                                master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port);
                                return;
                        }


                        log(1, ntohl(addr->sin_addr.s_addr), s, t, "UDP packet contains session %d "
                                        "but no session[%d].tunnel exists (LAC said"
                                        " tunnel = %d). Dropping packet.\n", s, s, t);
                        STAT(tunnel_rx_errors);
                        return;
                }

                if (session[s].die)
                {
                        log(3, ntohl(addr->sin_addr.s_addr), s, t, "Session %d is closing. Don't process PPP packets\n", s);
// I'm pretty sure this isn't right -- mo.
//                      return;              // closing session, PPP not processed
                }
                if (prot == PPPPAP)
                {
                        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; }
                        processpap(t, s, p, l);
                }
                else if (prot == PPPCHAP)
                {
                        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; }
                        processchap(t, s, p, l);
                }
                else if (prot == PPPLCP)
                {
                        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; }
                        processlcp(t, s, p, l);
                }
                else if (prot == PPPIPCP)
                {
                        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; }
                        processipcp(t, s, p, l);
                }
                else if (prot == PPPCCP)
                {
                        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; }
                        processccp(t, s, p, l);
                }
                else if (prot == PPPIP)
                {
                        if (!config->cluster_iam_master)
                        {
                                // We're a slave. Should we forward this packet to the master?

                                // Is this a walled garden session, or something that needs it's
                                // idle time updated??

                                // Maintain the idle timeouts on the master. If this would
                                // significantly reset the idletimeout, run it via the master
                                // to refresh the master's idle timer.
                                // Not sure this is ideal: It may re-order packets.

                                if (session[s].walled_garden || (session[s].last_packet + (ECHO_TIMEOUT/2)) < time_now)
                                {
                                        master_forward_packet(buf, len, addr->sin_addr.s_addr, addr->sin_port);
                                        session[s].last_packet = time_now;
                                        return;
                                }
                                // fall through to processipin.
                        } else
                                session[s].last_packet = time_now;
                        processipin(t, s, p, l);
                }
                else
                {
                        STAT(tunnel_rx_errors);
                        log(1, ntohl(addr->sin_addr.s_addr), s, t, "Unknown PPP protocol %04X\n", prot);
                }
        }
}

// read and process packet on tap
void processtap(u8 * buf, int len)
{
        log_hex(5, "Receive TAP Data", buf, len);
        STAT(tap_rx_packets);
        INC_STAT(tap_rx_bytes, len);

        CSTAT(call_processtap);

        eth_rx_pkt++;
        eth_rx += len;
        if (len < 22)
        {
                log(1, 0, 0, 0, "Short tap packet %d bytes\n", len);
                STAT(tap_rx_errors);
                return;
        }
        if (*(u16 *) (buf + 2) == htons(PKTARP)) // ARP
                processarp(buf, len);
        else if (*(u16 *) (buf + 2) == htons(PKTIP)) // IP
                processipout(buf, len);
        // Else discard.
}

//
// Maximum number of actions to complete.
// This is to avoid sending out too many packets
// at once.
#define MAX_ACTIONS 500

int regular_cleanups(void)
{
        static sessionidt s = 0;        // Next session to check for actions on.
        tunnelidt t;
        int count=0,i;
        u16 r;
        static clockt next_acct = 0;

        log(3, 0, 0, 0, "Begin regular cleanup\n");

        for (r = 1; r < MAXRADIUS; r++)
        {
                if (!radius[r].state)
                        continue;
                if (radius[r].retry)
                {
                        if (radius[r].retry <= TIME)
                                radiusretry(r);
                } else
                        radius[r].retry = backoff(radius[r].try+1);     // Is this really needed? --mo
        }
        for (t = 1; t <= config->cluster_highest_tunnelid; t++)
        {
                // check for expired tunnels
                if (tunnel[t].die && tunnel[t].die <= TIME)
                {
                        STAT(tunnel_timeout);
                        tunnelkill(t, "Expired");
                        continue;
                }
                // check for message resend
                if (tunnel[t].retry && tunnel[t].controlc)
                {
                        // resend pending messages as timeout on reply
                        if (tunnel[t].retry <= TIME)
                        {
                                controlt *c = tunnel[t].controls;
                                u8 w = tunnel[t].window;
                                tunnel[t].try++; // another try
                                if (tunnel[t].try > 5)
                                        tunnelkill(t, "Timeout on control message"); // game over
                                else
                                        while (c && w--)
                                        {
                                                tunnelsend(c->buf, c->length, t);
                                                c = c->next;
                                        }
                        }
                }
                // Send hello
                if (tunnel[t].state == TUNNELOPEN && tunnel[t].lastrec < TIME + 600)
                {
                        controlt *c = controlnew(6); // sending HELLO
                        controladd(c, t, 0); // send the message
                        log(3, tunnel[t].ip, 0, t, "Sending HELLO message\n");
                }
        }

        // Check for sessions that have been killed from the CLI
        if (cli_session_kill[0])
        {
                int i;
                for (i = 0; i < MAXSESSION && cli_session_kill[i]; i++)
                {
                        log(2, 0, cli_session_kill[i], 0, "Dropping session by CLI\n");
                        sessionshutdown(cli_session_kill[i], "Requested by administrator");
                        cli_session_kill[i] = 0;
                }
        }
        // Check for tunnels that have been killed from the CLI
        if (cli_tunnel_kill[0])
        {
                int i;
                for (i = 1; i < MAXTUNNEL && cli_tunnel_kill[i]; i++)
                {
                        log(2, 0, cli_tunnel_kill[i], 0, "Dropping tunnel by CLI\n");
                        tunnelshutdown(cli_tunnel_kill[i], "Requested by administrator");
                        cli_tunnel_kill[i] = 0;
                }
        }

        count = 0;
        for (i = 1; i <= config->cluster_highest_sessionid; i++)
        {

                s++;
                if (s > config->cluster_highest_sessionid)
                        s = 1;

                if (!session[s].tunnel) // Session isn't in use
                        continue;

                if (!session[s].die && session[s].ip && !(session[s].flags & SF_IPCP_ACKED) )
                {
                        // IPCP has not completed yet. Resend
                        log(3, session[s].ip, s, session[s].tunnel, "No ACK for initial IPCP ConfigReq... resending\n");
                        sendipcp(session[s].tunnel, s);
                }

                // check for expired sessions
                if (session[s].die && session[s].die <= TIME)
                {
                        sessionkill(s, "Expired");
                        if (++count >= MAX_ACTIONS) break;
                        continue;
                }

                // Drop sessions who have not responded within IDLE_TIMEOUT seconds
                if (session[s].last_packet && (time_now - session[s].last_packet >= IDLE_TIMEOUT))
                {
                        sessionkill(s, "No response to LCP ECHO requests");
                        STAT(session_timeout);
                        if (++count >= MAX_ACTIONS) break;
                        continue;
                }

                // No data in IDLE_TIMEOUT seconds, send LCP ECHO
                if (session[s].user[0] && (time_now - session[s].last_packet >= ECHO_TIMEOUT))
                {
                        u8 b[MAXCONTROL] = {0};

                        u8 *q = makeppp(b, sizeof(b), 0, 0, session[s].tunnel, s, PPPLCP);
                        if (!q) {
                                log(3, session[s].ip, s, t, "failed to send ECHO packet.\n");
                                continue;
                        }

                        *q = EchoReq;
                        *(u8 *)(q + 1) = (time_now % 255); // ID
                        *(u16 *)(q + 2) = htons(8); // Length
                        *(u32 *)(q + 4) = 0; // Magic Number (not supported)

                        log(4, session[s].ip, s, session[s].tunnel, "No data in %d seconds, sending LCP ECHO\n",
                                        (int)(time_now - session[s].last_packet));
                        tunnelsend(b, 24, session[s].tunnel); // send it
                        if (++count >= MAX_ACTIONS) break;
                        continue;
                }
        }
        if (config->accounting_dir && next_acct <= TIME)
        {
                // Dump accounting data
                next_acct = TIME + ACCT_TIME;
                dump_acct_info();
        }

        if (count >= MAX_ACTIONS)
                return 1;       // Didn't finish!

        log(3, 0, 0, 0, "End regular cleanup (%d actions), next in %d seconds\n", count, config->cleanup_interval);
        return 0;
}


//
// Are we in the middle of a tunnel update, or radius
// requests??
//
int still_busy(void)
{
        int i;
        static int last_talked = 0;
        for (i = config->cluster_highest_tunnelid ; i > 0 ; --i) {
                if (!tunnel[i].controlc)
                        continue;

                if (last_talked != TIME) {
                        log(2,0,0,0, "Tunnel %d still has un-acked control messages.\n", i);
                        last_talked = TIME;
                }
                return 1;
        }

        for (i = 1; i < MAXRADIUS; i++)
        {
                if (radius[i].state == RADIUSNULL)
                        continue;
                if (radius[i].state == RADIUSWAIT)
                        continue;

                if (last_talked != TIME) {
                        log(2,0,0,0, "Radius session %d is still busy (sid %d)\n", i, radius[i].session);
                        last_talked = TIME;
                }
                return 1;
        }

        return 0;
}

// main loop - gets packets on tap or udp and processes them
void mainloop(void)
{
        fd_set cr;
        int cn, i;
        u8 buf[65536];
        struct timeval to;
        clockt next_cluster_ping = 0;   // send initial ping immediately
        time_t next_clean = time_now + config->cleanup_interval;

        log(4, 0, 0, 0, "Beginning of main loop. udpfd=%d, tapfd=%d, cluster_sockfd=%d, controlfd=%d\n",
                        udpfd, tapfd, cluster_sockfd, controlfd);

        FD_ZERO(&cr);
        FD_SET(udpfd, &cr);
        FD_SET(tapfd, &cr);
        FD_SET(controlfd, &cr);
        FD_SET(clifd, &cr);
        if (cluster_sockfd) FD_SET(cluster_sockfd, &cr);
        cn = udpfd;
        if (cn < tapfd) cn = tapfd;
        if (cn < controlfd) cn = controlfd;
        if (cn < clifd) cn = clifd;
        if (cn < cluster_sockfd) cn = cluster_sockfd;
        for (i = 0; i < config->num_radfds; i++)
        {
                if (!radfds[i]) continue;
                FD_SET(radfds[i], &cr);
                if (radfds[i] > cn)
                        cn = radfds[i];
        }

        while (!main_quit || still_busy())
        {
                fd_set r;
                int n = cn;
#ifdef BGP
                fd_set w;
                int bgp_set[BGP_NUM_PEERS];
#endif /* BGP */

                if (config->reload_config)
                {
                        // Update the config state based on config settings
                        update_config();
                }

                memcpy(&r, &cr, sizeof(fd_set));
                to.tv_sec = 0;
                to.tv_usec = 100000; // 1/10th of a second.

#ifdef BGP
                FD_ZERO(&w);
                for (i = 0; i < BGP_NUM_PEERS; i++)
                {
                        bgp_set[i] = bgp_select_state(&bgp_peers[i]);
                        if (bgp_set[i] & 1)
                        {
                                FD_SET(bgp_peers[i].sock, &r);
                                if (bgp_peers[i].sock > n)
                                        n = bgp_peers[i].sock;
                        }

                        if (bgp_set[i] & 2)
                        {
                                FD_SET(bgp_peers[i].sock, &w);
                                if (bgp_peers[i].sock > n)
                                        n = bgp_peers[i].sock;
                        }
                }

                n = select(n + 1, &r, &w, 0, &to);
#else /* BGP */
                n = select(n + 1, &r, 0, 0, &to);
#endif /* BGP */

                TIME = now();
                if (n < 0)
                {
                        if (errno == EINTR)
                                continue;

                        log(0, 0, 0, 0, "Error returned from select(): %s\n", strerror(errno));
                        main_quit++;
                        break;
                }
                else if (n)
                {
                        struct sockaddr_in addr;
                        int alen = sizeof(addr);
                        if (FD_ISSET(udpfd, &r))
                        {
                                int c, n;
                                for (c = 0; c < config->multi_read_count; c++)
                                {
                                        if ((n = recvfrom(udpfd, buf, sizeof(buf), 0, (void *) &addr, &alen)) > 0)
                                                processudp(buf, n, &addr);
                                        else
                                                break;
                                }
                        }
                        if (FD_ISSET(tapfd, &r))
                        {
                                int c, n;
                                for (c = 0; c < config->multi_read_count; c++)
                                {
                                        if ((n = read(tapfd, buf, sizeof(buf))) > 0)
                                                processtap(buf, n);
                                        else
                                                break;
                                }
                        }
                        for (i = 0; i < config->num_radfds; i++)
                                if (FD_ISSET(radfds[i], &r))
                                        processrad(buf, recv(radfds[i], buf, sizeof(buf), 0), i);
                        if (FD_ISSET(cluster_sockfd, &r)) {
                                int size;
                                size = recvfrom(cluster_sockfd, buf, sizeof(buf), MSG_WAITALL, (void *) &addr, &alen);
                                processcluster(buf, size, addr.sin_addr.s_addr);
                        }
                        if (FD_ISSET(controlfd, &r))
                                processcontrol(buf, recvfrom(controlfd, buf, sizeof(buf), MSG_WAITALL, (void *) &addr, &alen), &addr);
                        if (FD_ISSET(clifd, &r))
                        {
                                struct sockaddr_in addr;
                                int sockfd;
                                int len = sizeof(addr);

                                if ((sockfd = accept(clifd, (struct sockaddr *)&addr, &len)) <= 0)
                                {
                                        log(0, 0, 0, 0, "accept error: %s\n", strerror(errno));
                                        continue;
                                }
                                else
                                {
                                        cli_do(sockfd);
                                        close(sockfd);
                                }
                        }
                }

                        // Runs on every machine (master and slaves).
                if (cluster_sockfd && next_cluster_ping <= TIME)
                {
                        // Check to see which of the cluster is still alive..
                        cluster_send_ping(basetime);
                        cluster_check_master();
                        cluster_heartbeat();            // Only does anything if we're a master.
                        master_update_counts();         // If we're a slave, send our byte counters to our master.
                        if (config->cluster_iam_master && !config->cluster_iam_uptodate)
                                next_cluster_ping = TIME + 1; // out-of-date slaves, do fast updates
                        else
                                next_cluster_ping = TIME + config->cluster_hb_interval;
                }

                        // Run token bucket filtering queue..
                        // Only run it every 1/10th of a second.
                        // Runs on all machines both master and slave.
                {
                        static clockt last_run = 0;
                        if (last_run != TIME) {
                                last_run = TIME;
                                tbf_run_timer();
                        }
                }

                /* Handle timeouts. Make sure that this gets run anyway, even if there was
                 * something to read, else under load this will never actually run....
                 *
                 */
                if (config->cluster_iam_master && next_clean <= time_now) {
                        if (regular_cleanups()) { // Did it finish?
                                next_clean = time_now + 1 ;     // Didn't finish. Check quickly.
                        } else {
                                next_clean = time_now + config->cleanup_interval; // Did. Move to next interval.
                        }
                }

#ifdef BGP
                for (i = 0; i < BGP_NUM_PEERS; i++)
                {
                        bgp_process(&bgp_peers[i],
                                bgp_set[i] ? FD_ISSET(bgp_peers[i].sock, &r) : 0,
                                bgp_set[i] ? FD_ISSET(bgp_peers[i].sock, &w) : 0);
                }
#endif /* BGP */
        }

                // Are we the master and shutting down??
        if (config->cluster_iam_master)
                cluster_heartbeat(); // Flush any queued changes..

                // Ok. Notify everyone we're shutting down. If we're
                // the master, this will force an election.
        cluster_send_ping(0);

        //
        // Important!!! We MUST not process any packets past this point!
}

// Init data structures
void initdata(void)
{
        int i;

        _statistics = mmap(NULL, sizeof(struct Tstats), PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, 0, 0);
        if (_statistics == MAP_FAILED)
        {
                log(0, 0, 0, 0, "Error doing mmap for _statistics: %s\n", strerror(errno));
                exit(1);
        }
        config = mmap(NULL, sizeof(struct configt), PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, 0, 0);
        if (config == MAP_FAILED)
        {
                log(0, 0, 0, 0, "Error doing mmap for configuration: %s\n", strerror(errno));
                exit(1);
        }
        memset(config, 0, sizeof(struct configt));
        time(&config->start_time);
        strncpy(config->config_file, CONFIGFILE, sizeof(config->config_file) - 1);
        tunnel = mmap(NULL, sizeof(tunnelt) * MAXTUNNEL, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, 0, 0);
        if (tunnel == MAP_FAILED)
        {
                log(0, 0, 0, 0, "Error doing mmap for tunnels: %s\n", strerror(errno));
                exit(1);
        }
        session = mmap(NULL, sizeof(sessiont) * MAXSESSION, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, 0, 0);
        if (session == MAP_FAILED)
        {
                log(0, 0, 0, 0, "Error doing mmap for sessions: %s\n", strerror(errno));
                exit(1);
        }

        sess_count = mmap(NULL, sizeof(sessioncountt) * MAXSESSION, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, 0, 0);
        if (sess_count == MAP_FAILED)
        {
                log(0, 0, 0, 0, "Error doing mmap for sessions_count: %s\n", strerror(errno));
                exit(1);
        }

        radius = mmap(NULL, sizeof(radiust) * MAXRADIUS, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, 0, 0);
        if (radius == MAP_FAILED)
        {
                log(0, 0, 0, 0, "Error doing mmap for radius: %s\n", strerror(errno));
                exit(1);
        }
        ip_address_pool = mmap(NULL, sizeof(ippoolt) * MAXIPPOOL, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, 0, 0);
        if (ip_address_pool == MAP_FAILED)
        {
                log(0, 0, 0, 0, "Error doing mmap for ip_address_pool: %s\n", strerror(errno));
                exit(1);
        }
#ifdef RINGBUFFER
        ringbuffer = mmap(NULL, sizeof(struct Tringbuffer), PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, 0, 0);
        if (ringbuffer == MAP_FAILED)
        {
                log(0, 0, 0, 0, "Error doing mmap for ringbuffer: %s\n", strerror(errno));
                exit(1);
        }
        memset(ringbuffer, 0, sizeof(struct Tringbuffer));
#endif

        cli_session_kill = mmap(NULL, sizeof(sessionidt) * MAXSESSION, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, 0, 0);
        if (cli_session_kill == MAP_FAILED)
        {
                log(0, 0, 0, 0, "Error doing mmap for cli session kill: %s\n", strerror(errno));
                exit(1);
        }
        memset(cli_session_kill, 0, sizeof(sessionidt) * MAXSESSION);
        cli_tunnel_kill = mmap(NULL, sizeof(tunnelidt) * MAXSESSION, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, 0, 0);
        if (cli_tunnel_kill == MAP_FAILED)
        {
                log(0, 0, 0, 0, "Error doing mmap for cli tunnel kill: %s\n", strerror(errno));
                exit(1);
        }
        memset(cli_tunnel_kill, 0, sizeof(tunnelidt) * MAXSESSION);

        memset(tunnel, 0, sizeof(tunnelt) * MAXTUNNEL);
        memset(session, 0, sizeof(sessiont) * MAXSESSION);
        memset(radius, 0, sizeof(radiust) * MAXRADIUS);
        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++) {
                session[i].next = i + 1;
                session[i].tunnel = T_UNDEF;    // mark it as not filled in.
        }
        session[MAXSESSION - 1].next = 0;
        sessionfree = 1;

                // Mark all the tunnels as undefined (waiting to be filled in by a download).
        for (i = 1; i < MAXTUNNEL- 1; i++) {
                tunnel[i].state = TUNNELUNDEF;  // mark it as not filled in.
        }

        if (!*hostname)
        {
                char *p;
                // Grab my hostname unless it's been specified
                gethostname(hostname, sizeof(hostname));
                if ((p = strchr(hostname, '.'))) *p = 0;
        }
        _statistics->start_time = _statistics->last_reset = time(NULL);

#ifdef BGP
        bgp_peers = mmap(NULL, sizeof(struct bgp_peer) * BGP_NUM_PEERS, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, 0, 0);
        if (bgp_peers == MAP_FAILED)
        {
                log(0, 0, 0, 0, "Error doing mmap for bgp: %s\n", strerror(errno));
                exit(1);
        }
#endif /* BGP */
}

void initiptables(void)
{
        /* Flush the tables here so that we have a clean slate */

// Not needed. 'nat' is setup by garden.c
// mangle isn't used (as throttling is done by tbf inhouse).
}

int assign_ip_address(sessionidt s)
{
        u32 i;
        int best = -1;
        time_t best_time = time_now;
        char *u = session[s].user;
        char reuse = 0;


        CSTAT(call_assign_ip_address);

        for (i = 1; i < ip_pool_size; i++)
        {
                if (!ip_address_pool[i].address || ip_address_pool[i].assigned)
                        continue;

                if (!session[s].walled_garden && ip_address_pool[i].user[0] && !strcmp(u, ip_address_pool[i].user))
                {
                        best = i;
                        reuse = 1;
                        break;
                }

                if (ip_address_pool[i].last < best_time)
                {
                        best = i;
                        if (!(best_time = ip_address_pool[i].last))
                                break; // never used, grab this one
                }
        }

        if (best < 0)
        {
                log(0, 0, s, session[s].tunnel, "assign_ip_address(): out of addresses\n");
                return 0;
        }

        session[s].ip = ip_address_pool[best].address;
        session[s].ip_pool_index = best;
        ip_address_pool[best].assigned = 1;
        ip_address_pool[best].last = time_now;
        ip_address_pool[best].session = s;
        if (session[s].walled_garden)
                /* Don't track addresses of users in walled garden (note: this
                   means that their address isn't "sticky" even if they get
                   un-gardened). */
                ip_address_pool[best].user[0] = 0;
        else
                strncpy(ip_address_pool[best].user, u, sizeof(ip_address_pool[best].user) - 1);

        STAT(ip_allocated);
        log(4, ip_address_pool[best].address, s, session[s].tunnel,
                "assign_ip_address(): %s ip address %d from pool\n", reuse ? "Reusing" : "Allocating", best);

        return 1;
}

void free_ip_address(sessionidt s)
{
        int i = session[s].ip_pool_index;

        if (!session[s].ip)
                return; // what the?

        if (i < 0)      // Is this actually part of the ip pool?
                i = 0;

        STAT(ip_freed);
        cache_ipmap(session[s].ip, -i); // Change the mapping to point back to the ip pool index.
        session[s].ip = 0;
        ip_address_pool[i].assigned = 0;
        ip_address_pool[i].session = 0;
        ip_address_pool[i].last = time_now;


        CSTAT(call_free_ip_address);

}

//
// Fsck the address pool against the session table.
// Normally only called when we become a master.
//
// This isn't perfect: We aren't keep tracking of which
// users used to have an IP address.
//
void rebuild_address_pool(void)
{
        int i;

                //
                // Zero the IP pool allocation, and build
                // a map from IP address to pool index.
        for (i = 1; i < MAXIPPOOL; ++i) {
                ip_address_pool[i].assigned = 0;
                ip_address_pool[i].session = 0;
                if (!ip_address_pool[i].address)
                        continue;

                cache_ipmap(ip_address_pool[i].address, -i);    // Map pool IP to pool index.
        }

        for (i = 0; i < MAXSESSION; ++i) {
                int ipid;
                if (!session[i].ip || !session[i].tunnel)
                        continue;
                ipid = - lookup_ipmap(htonl(session[i].ip));

                if (session[i].ip_pool_index < 0) {     // Not allocated out of the pool.
                        if (ipid < 1)                   // Not found in the pool either? good.
                                continue;

                        log(0, 0, i, 0, "Session %d has an IP address (%s) that was marked static, but is in the pool (%d)!\n",
                                i, inet_toa(session[i].ip), ipid);

                        // Fall through and process it as part of the pool.
                }


                if (ipid > MAXIPPOOL || ipid < 0) {
                        log(0, 0, i, 0, "Session %d has a pool IP that's not found in the pool! (%d)\n", i, ipid);
                        ipid = -1;
                        session[i].ip_pool_index = ipid;
                        continue;
                }

                ip_address_pool[ipid].assigned = 1;
                ip_address_pool[ipid].session = i;
                ip_address_pool[ipid].last = time_now;
                strncpy(ip_address_pool[ipid].user, session[i].user, sizeof(ip_address_pool[ipid].user) - 1);
                session[i].ip_pool_index = ipid;
                cache_ipmap(session[i].ip, i);  // Fix the ip map.
        }
}

//
// Fix the address pool to match a changed session.
// (usually when the master sends us an update).
void fix_address_pool(int sid)
{
        int ipid;

        ipid = session[sid].ip_pool_index;

        if (ipid > ip_pool_size)
                return;         // Ignore it. rebuild_address_pool will fix it up.

        if (ip_address_pool[ipid].address != session[sid].ip)
                return;         // Just ignore it. rebuild_address_pool will take care of it.

        ip_address_pool[ipid].assigned = 1;
        ip_address_pool[ipid].session = sid;
        ip_address_pool[ipid].last = time_now;
        strncpy(ip_address_pool[ipid].user, session[sid].user, sizeof(ip_address_pool[ipid].user) - 1);
}

//
// Add a block of addresses to the IP pool to hand out.
//
void add_to_ip_pool(u32 addr, u32 mask)
{
        int i;
        if (mask == 0)
                mask = 0xffffffff;      // Host route only.

        addr &= mask;

        if (ip_pool_size >= MAXIPPOOL)  // Pool is full!
                return ;

        for (i = addr ;(i & mask) == addr; ++i)
        {
                if ((i & 0xff) == 0 || (i&0xff) == 255)
                        continue;       // Skip 0 and broadcast addresses.

                ip_address_pool[ip_pool_size].address = i;
                ip_address_pool[ip_pool_size].assigned = 0;
                ++ip_pool_size;
                if (ip_pool_size >= MAXIPPOOL)
                {
                        log(0,0,0,0, "Overflowed IP pool adding %s\n", inet_toa(htonl(addr)) );
                        return;
                }
        }
}

// Initialize the IP address pool
void initippool()
{
        FILE *f;
        char *p;
        char buf[4096];
        memset(ip_address_pool, 0, sizeof(ip_address_pool));

        if (!(f = fopen(IPPOOLFILE, "r")))
        {
                log(0, 0, 0, 0, "Can't load pool file " IPPOOLFILE ": %s\n", strerror(errno));
                exit(1);
        }

        while (ip_pool_size < MAXIPPOOL && fgets(buf, 4096, f))
        {
                char *pool = buf;
                buf[4095] = 0;  // Force it to be zero terminated/

                if (*buf == '#' || *buf == '\n')
                        continue; // Skip comments / blank lines
                if ((p = (char *)strrchr(buf, '\n'))) *p = 0;
                if ((p = (char *)strchr(buf, ':')))
                {
                        ipt src;
                        *p = '\0';
                        src = inet_addr(buf);
                        if (src == INADDR_NONE)
                        {
                                log(0, 0, 0, 0, "Invalid address pool IP %s\n", buf);
                                exit(1);
                        }
                        // This entry is for a specific IP only
                        if (src != config->bind_address)
                                continue;
                        *p = ':';
                        pool = p+1;
                }
                if ((p = (char *)strchr(pool, '/')))
                {
                        // It's a range
                        int numbits = 0;
                        u32 start = 0, mask = 0;

                        log(2, 0, 0, 0, "Adding IP address range %s\n", buf);
                        *p++ = 0;
                        if (!*p || !(numbits = atoi(p)))
                        {
                                log(0, 0, 0, 0, "Invalid pool range %s\n", buf);
                                continue;
                        }
                        start = ntohl(inet_addr(pool));
                        mask = (u32)(pow(2, numbits) - 1) << (32 - numbits);

                        // Add a static route for this pool
                        log(5, 0, 0, 0, "Adding route for address pool %s/%u\n", inet_toa(htonl(start)), 32 + mask);
                        routeset(0, start, mask, 0, 1);

                        add_to_ip_pool(start, mask);
                }
                else
                {
                        // It's a single ip address
                        add_to_ip_pool(inet_addr(pool), 0);
                }
        }
        fclose(f);
        log(1, 0, 0, 0, "IP address pool is %d addresses\n", ip_pool_size - 1);
}

void snoop_send_packet(char *packet, u16 size, ipt destination, u16 port)
{
        if (!destination || !port || snoopfd <= 0 || size <= 0 || !packet)
                return;

        snoop_addr.sin_addr.s_addr = destination;
        snoop_addr.sin_port = ntohs(port);

        log(5, 0, 0, 0, "Snooping packet at %p (%d bytes) to %s:%d\n",
                        packet, size, inet_toa(snoop_addr.sin_addr.s_addr), htons(snoop_addr.sin_port));
        if (sendto(snoopfd, packet, size, MSG_DONTWAIT | MSG_NOSIGNAL, (void *) &snoop_addr, sizeof(snoop_addr)) < 0)
                log(0, 0, 0, 0, "Error sending intercept packet: %s\n", strerror(errno));
        STAT(packets_snooped);
}

void dump_acct_info()
{
    char filename[1024];
    char timestr[64];
    time_t t = time(NULL);
    int i;
    FILE *f = NULL;


    CSTAT(call_dump_acct_info);

    strftime(timestr, 64, "%Y%m%d%H%M%S", localtime(&t));
    snprintf(filename, 1024, "%s/%s", config->accounting_dir, timestr);

    for (i = 0; i < MAXSESSION; i++)
    {
        if (!session[i].opened || !session[i].ip || !session[i].cin || !session[i].cout || !*session[i].user || session[i].walled_garden)
                continue;
        if (!f)
        {
            time_t now = time(NULL);
            if (!(f = fopen(filename, "w")))
            {
                    log(0, 0, 0, 0, "Can't write accounting info to %s: %s\n", filename, strerror(errno));
                    return;
            }
            log(3, 0, 0, 0, "Dumping accounting information to %s\n", filename);
            fprintf(f, "# dslwatch.pl dump file V1.01\n"
                "# host: %s\n"
                "# time: %ld\n"
                "# uptime: %ld\n"
                "# format: username ip qos uptxoctets downrxoctets\n",
                    hostname,
                    now,
                    now - basetime);
        }

        log(4, 0, 0, 0, "Dumping accounting information for %s\n", session[i].user);
        fprintf(f, "%s %s %d %u %u\n",
            session[i].user,                            // username
            inet_toa(htonl(session[i].ip)),             // ip
            (session[i].throttle) ? 2 : 1,              // qos
            (u32)session[i].cin,                // uptxoctets
            (u32)session[i].cout);              // downrxoctets

        session[i].pin = session[i].cin = 0;
        session[i].pout = session[i].cout = 0;
    }

    if (f) fclose(f);
}

// Main program
int main(int argc, char *argv[])
{
        int o;

        _program_name = strdup(argv[0]);

        time(&basetime);             // start clock

        // scan args
        while ((o = getopt(argc, argv, "vc:h:a:")) >= 0)
        {
                switch (o)
                {
                        case 'd':
                                // Double fork to detach from terminal
                                if (fork()) exit(0);
                                if (fork()) exit(0);
                                break;
                        case 'v':
                                config->debug++;
                                break;
                        case 'h':
                                snprintf(hostname, sizeof(hostname), "%s", optarg);
                                break;
                        case '?':
                        default:
                                printf("Args are:\n"
                                       "\t-d\tDetach from terminal\n"
                                       "\t-c <file>\tConfig file\n"
                                       "\t-h <hostname>\tForce hostname\n"
                                       "\t-a <address>\tUse specific address\n"
                                       "\t-v\t\tDebug\n");

                                return (0);
                                break;
                }
        }

        // Start the timer routine off
        time(&time_now);
        strftime(time_now_string, 64, "%Y-%m-%d %H:%M:%S", localtime(&time_now));
        signal(SIGALRM, sigalrm_handler);
        siginterrupt(SIGALRM, 0);

        initiptables();
        initplugins();
        initdata();
        init_tbf();
        init_cli(hostname);
        read_config_file();

        log(0, 0, 0, 0, "L2TPNS version " VERSION "\n");
        log(0, 0, 0, 0, "Copyright (c) 2003, 2004 Optus Internet Engineering\n");
        log(0, 0, 0, 0, "Copyright (c) 2002 FireBrick (Andrews & Arnold Ltd / Watchfront Ltd) - GPL licenced\n");
        {
                struct rlimit rlim;
                rlim.rlim_cur = RLIM_INFINITY;
                rlim.rlim_max = RLIM_INFINITY;
                // Remove the maximum core size
                if (setrlimit(RLIMIT_CORE, &rlim) < 0)
                        log(0, 0, 0, 0, "Can't set ulimit: %s\n", strerror(errno));
                // Make core dumps go to /tmp
                chdir("/tmp");
        }

        if (config->scheduler_fifo)
        {
                int ret;
                struct sched_param params = {0};
                params.sched_priority = 1;

                if (get_nprocs() < 2)
                {
                        log(0, 0, 0, 0, "Not using FIFO scheduler, there is only 1 processor in the system.\n");
                        config->scheduler_fifo = 0;
                }
                else
                {
                        if ((ret = sched_setscheduler(0, SCHED_FIFO, &params)) == 0)
                        {
                                log(1, 0, 0, 0, "Using FIFO scheduler. Say goodbye to any other processes running\n");
                        }
                        else
                        {
                                log(0, 0, 0, 0, "Error setting scheduler to FIFO: %s\n", strerror(errno));
                                config->scheduler_fifo = 0;
                        }
                }
        }

        /* Set up the cluster communications port. */
        if (cluster_init(config->bind_address) < 0)
                exit(1);

#ifdef BGP
        signal(SIGPIPE, SIG_IGN);
        bgp_setup(config->as_number);
        bgp_add_route(config->bind_address, 0xffffffff);
        if (*config->bgp_peer[0])
                bgp_start(&bgp_peers[0], config->bgp_peer[0],
                    config->bgp_peer_as[0], 0); /* 0 = routing disabled */

        if (*config->bgp_peer[1])
                bgp_start(&bgp_peers[1], config->bgp_peer[1],
                    config->bgp_peer_as[1], 0);
#endif /* BGP */

        inittap();
        log(1, 0, 0, 0, "Set up on interface %s\n", config->tapdevice);

        initudp();
        initrad();
        initippool();

        read_state();

        signal(SIGHUP, sighup_handler);
        signal(SIGTERM, sigterm_handler);
        signal(SIGINT, sigterm_handler);
        signal(SIGQUIT, sigquit_handler);
        signal(SIGCHLD, sigchild_handler);

        alarm(1);

        // Drop privileges here
        if (config->target_uid > 0 && geteuid() == 0)
                setuid(config->target_uid);

        mainloop();

#ifdef BGP
        /* try to shut BGP down cleanly; with luck the sockets will be
           writable since we're out of the select */
        {
                int i;
                for (i = 0; i < BGP_NUM_PEERS; i++)
                        if (bgp_peers[i].state == Established)
                                bgp_stop(&bgp_peers[i]);
        }
#endif /* BGP */

        /* remove plugins (so cleanup code gets run) */
        plugins_done();

        /* kill CLI children */
        signal(SIGTERM, SIG_IGN);
        kill(0, SIGTERM);
        return 0;
}

void sighup_handler(int junk)
{
        if (log_stream && log_stream != stderr)
        {
                fclose(log_stream);
                log_stream = NULL;
        }

        read_config_file();
}

void sigalrm_handler(int junk)
{
        // Log current traffic stats

        snprintf(config->bandwidth, sizeof(config->bandwidth),
                "UDP-ETH:%1.0f/%1.0f  ETH-UDP:%1.0f/%1.0f  TOTAL:%0.1f   IN:%u OUT:%u",
                (udp_rx / 1024.0 / 1024.0 * 8),
                (eth_tx / 1024.0 / 1024.0 * 8),
                (eth_rx / 1024.0 / 1024.0 * 8),
                (udp_tx / 1024.0 / 1024.0 * 8),
                ((udp_tx + udp_rx + eth_tx + eth_rx) / 1024.0 / 1024.0 * 8),
                udp_rx_pkt, eth_rx_pkt);

        udp_tx = udp_rx = 0;
        udp_rx_pkt = eth_rx_pkt = 0;
        eth_tx = eth_rx = 0;

        if (config->dump_speed)
                printf("%s\n", config->bandwidth);

        // Update the internal time counter
        time(&time_now);
        strftime(time_now_string, 64, "%Y-%m-%d %H:%M:%S", localtime(&time_now));
        alarm(1);

        {
                // Run timer hooks
                struct param_timer p = { time_now };
                run_plugins(PLUGIN_TIMER, &p);
        }

}

void sigterm_handler(int junk)
{
        log(1, 0, 0, 0, "Shutting down cleanly\n");
        if (config->save_state)
                dump_state();

        main_quit++;
}

void sigquit_handler(int junk)
{
        int i;

        log(1, 0, 0, 0, "Shutting down without saving sessions\n");
        for (i = 1; i < MAXSESSION; i++)
        {
                if (session[i].opened)
                        sessionkill(i, "L2TPNS Closing");
        }
        for (i = 1; i < MAXTUNNEL; i++)
        {
                if (tunnel[i].ip || tunnel[i].state)
                        tunnelshutdown(i, "L2TPNS Closing");
        }

        main_quit++;
}

void sigchild_handler(int signal)
{
        while (waitpid(-1, NULL, WNOHANG) > 0)
            ;
}

void read_state()
{
    struct stat sb;
    int i;
    ippoolt itmp;
    FILE *f;
    char magic[sizeof(DUMP_MAGIC)-1];
    u32 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, 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, 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, 0, "Bad state file magic\n");
        exit(1);
    }

    log(1, 0, 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, 0, "Error/mismatch reading ip pool header from state file\n");
        exit(1);
    }

    if (buf[0] > ip_pool_size)
    {
        log(0, 0, 0, 0, "ip pool has shrunk!  state = %d, current = %d\n", buf[0], ip_pool_size);
        exit(1);
    }

    log(2, 0, 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, 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, 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, 0, "Error/mismatch reading tunnel header from state file\n");
        exit(1);
    }

    log(2, 0, 0, 0, "Loading %u tunnels\n", MAXTUNNEL);
    if (fread(tunnel, sizeof(tunnelt), MAXTUNNEL, f) != MAXTUNNEL)
    {
        log(0, 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, 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, 0, "Error/mismatch reading session header from state file\n");
        exit(1);
    }

    log(2, 0, 0, 0, "Loading %u sessions\n", MAXSESSION);
    if (fread(session, sizeof(sessiont), MAXSESSION, f) != MAXSESSION)
    {
        log(0, 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, 0, 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, 0, "Loaded saved state information\n");
}

void dump_state()
{
    FILE *f;
    u32 buf[2];

    if (!config->save_state)
        return;

    do {
        if (!(f = fopen(STATEFILE, "w")))
            break;

        log(1, 0, 0, 0, "Dumping state information\n");

        if (fwrite(DUMP_MAGIC, sizeof(DUMP_MAGIC)-1, 1, f) != 1) break;

        log(2, 0, 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, 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, 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, 0, "Can't write state information: %s\n", strerror(errno));
    unlink(STATEFILE);
}

void build_chap_response(char *challenge, u8 id, u16 challenge_length, char **challenge_response)
{
        MD5_CTX ctx;
        *challenge_response = NULL;

        if (!*config->l2tpsecret)
        {
                log(0, 0, 0, 0, "LNS requested CHAP authentication, but no l2tp secret is defined\n");
                return;
        }

        log(4, 0, 0, 0, "   Building challenge response for CHAP request\n");

        *challenge_response = (char *)calloc(17, 1);

        MD5Init(&ctx);
        MD5Update(&ctx, &id, 1);
        MD5Update(&ctx, config->l2tpsecret, strlen(config->l2tpsecret));
        MD5Update(&ctx, challenge, challenge_length);
        MD5Final(*challenge_response, &ctx);

        return;
}

static int facility_value(char *name)
{
    int i;
    for (i = 0; facilitynames[i].c_name; i++)
    {
        if (strcmp(facilitynames[i].c_name, name) == 0)
            return facilitynames[i].c_val;
    }
    return 0;
}

void update_config()
{
        int i;
        static int timeout = 0;
        static int interval = 0;

        // Update logging
        closelog();
        syslog_log = 0;
        if (log_stream)
        {
                fclose(log_stream);
                log_stream = NULL;
        }
        if (*config->log_filename)
        {
                if (strstr(config->log_filename, "syslog:") == config->log_filename)
                {
                        char *p = config->log_filename + 7;
                        if (*p)
                        {
                                openlog("l2tpns", LOG_PID, facility_value(p));
                                syslog_log = 1;
                        }
                }
                else if (strchr(config->log_filename, '/') == config->log_filename)
                {
                        if ((log_stream = fopen((char *)(config->log_filename), "a")))
                        {
                                fseek(log_stream, 0, SEEK_END);
                                setbuf(log_stream, NULL);
                        }
                        else
                        {
                                log_stream = stderr;
                                setbuf(log_stream, NULL);
                        }
                }
        }
        else
        {
                log_stream = stderr;
                setbuf(log_stream, NULL);
        }


        // Update radius
        config->numradiusservers = 0;
        for (i = 0; i < MAXRADSERVER; i++)
                if (config->radiusserver[i]) config->numradiusservers++;

        if (!config->numradiusservers)
        {
                log(0, 0, 0, 0, "No RADIUS servers defined!\n");
        }

        config->num_radfds = 2 << RADIUS_SHIFT;

        // Update plugins
        for (i = 0; i < MAXPLUGINS; i++)
        {
                if (strcmp(config->plugins[i], config->old_plugins[i]) == 0)
                        continue;
                if (*config->plugins[i])
                {
                        // Plugin added
                        add_plugin(config->plugins[i]);
                }
                else if (*config->old_plugins[i])
                {
                        // Plugin removed
                        remove_plugin(config->old_plugins[i]);
                }
        }
        memcpy(config->old_plugins, config->plugins, sizeof(config->plugins));
        if (!config->cleanup_interval) config->cleanup_interval = 10;
        if (!config->multi_read_count) config->multi_read_count = 10;
        if (!config->cluster_address) config->cluster_address = inet_addr(DEFAULT_MCAST_ADDR);
        if (!*config->cluster_interface)
                strncpy(config->cluster_interface, DEFAULT_MCAST_INTERFACE, sizeof(config->cluster_interface) - 1);

        if (!config->cluster_hb_interval)
                config->cluster_hb_interval = PING_INTERVAL;    // Heartbeat every 0.5 seconds.

        if (!config->cluster_hb_timeout)
                config->cluster_hb_timeout = HB_TIMEOUT;        // 10 missed heartbeat triggers an election.

        if (interval != config->cluster_hb_interval || timeout != config->cluster_hb_timeout)
        {
                // Paranoia:  cluster_check_master() treats 2 x interval + 1 sec as
                // late, ensure we're sufficiently larger than that
                int t = 4 * config->cluster_hb_interval + 11;

                if (config->cluster_hb_timeout < t)
                {
                        log(0,0,0,0, "Heartbeat timeout %d too low, adjusting to %d\n", config->cluster_hb_timeout, t);
                        config->cluster_hb_timeout = t;
                }

                // Push timing changes to the slaves immediately if we're the master
                if (config->cluster_iam_master)
                        cluster_heartbeat();

                interval = config->cluster_hb_interval;
                timeout = config->cluster_hb_timeout;
        }

        config->reload_config = 0;
}

void read_config_file()
{
        FILE *f;

        if (!config->config_file) return;
        if (!(f = fopen(config->config_file, "r"))) {
                fprintf(stderr, "Can't open config file %s: %s\n", config->config_file, strerror(errno));
                return;
        }

        log(3, 0, 0, 0, "Reading config file %s\n", config->config_file);
        cli_do_file(f);
        log(3, 0, 0, 0, "Done reading config file\n");
        fclose(f);
        update_config();
}

int sessionsetup(tunnelidt t, sessionidt s)
{
        // A session now exists, set it up
        ipt ip;
        char *user;
        sessionidt i;
        int r;

        CSTAT(call_sessionsetup);


        log(3, session[s].ip, s, t, "Doing session setup for session\n");

        if (!session[s].ip || session[s].ip == 0xFFFFFFFE)
        {
                assign_ip_address(s);
                if (session[s].ip)
                        log(3, 0, s, t, "   No IP allocated. Assigned %s from pool\n",
                                        inet_toa(htonl(session[s].ip)));
                else
                        log(0, 0, s, t, "   No IP allocated. The IP address pool is FULL!\n");
        }


        // Make sure this is right
        session[s].tunnel = t;

        // zap old sessions with same IP and/or username
        // Don't kill gardened sessions - doing so leads to a DoS
        // from someone who doesn't need to know the password
        {
                ip = session[s].ip;
                user = session[s].user;
                for (i = 1; i <= config->cluster_highest_sessionid; i++)
                {
                        if (i == s) continue;
                        if (ip == session[i].ip) sessionkill(i, "Duplicate IP address");
                        if (!session[s].walled_garden && !session[i].walled_garden && strcasecmp(user, session[i].user) == 0)
                                sessionkill(i, "Duplicate session for users");
                }
        }

                // Add the route for this session.
                //
                // Static IPs need to be routed. Anything else
                // is part of the IP address pool and is already routed,
                // it just needs to be added to the IP cache.
        if (session[s].ip_pool_index == -1) // static ip
                routeset(s, session[s].ip, 0, 0, 1);
        else
                cache_ipmap(session[s].ip, s);

        for (r = 0; r < MAXROUTE && session[s].route[r].ip; r++)
                routeset(s, session[s].route[r].ip, session[s].route[r].mask, session[s].ip, 1);

        if (!session[s].sid) {  // did this session just finish radius?
                log(3, session[s].ip, s, t, "Sending initial IPCP to client\n");
                sendipcp(t, s);
                session[s].sid = ++last_sid;
        }

        // Run the plugin's against this new session.
        {
                struct param_new_session data = { &tunnel[t], &session[s] };
                run_plugins(PLUGIN_NEW_SESSION, &data);
        }

        // Force throttling on or off (Actually : refresh the current throttling status)
        // This has the advantage of cleaning up after another throttled user who may have left
        // firewall rules lying around
        throttle_session(s, session[s].throttle);

        session[s].last_packet = time_now;

        {
                char *sessionip, *tunnelip;
                sessionip = strdup(inet_toa(htonl(session[s].ip)));
                tunnelip = strdup(inet_toa(htonl(tunnel[t].ip)));
                log(2, session[s].ip, s, t, "Login by %s at %s from %s (%s)\n",
                                session[s].user, sessionip, tunnelip, tunnel[t].hostname);
                if (sessionip) free(sessionip);
                if (tunnelip) free(tunnelip);
        }

        cluster_send_session(s);        // Mark it as dirty, and needing to the flooded to the cluster.

        return 1;       // RADIUS OK and IP allocated, done...
}

//
// This session just got dropped on us by the master or something.
// Make sure our tables up up to date...
//
int load_session(sessionidt s, sessiont *new)
{
        int i;

                // Sanity checks.
        if (new->ip_pool_index >= MAXIPPOOL ||
                new->tunnel >= MAXTUNNEL) {
                log(0,0,s,0, "Strange session update received!\n");
                        // FIXME! What to do here?
                return 0;
        }

                //
                // Ok. All sanity checks passed. Now we're committed to
                // loading the new session.
                //

        session[s].tunnel = new->tunnel; // For logging in cache_ipmap


        if (new->ip != session[s].ip)   // Changed ip. fix up hash tables.
        {
                if (session[s].ip)      // If there's an old one, remove it.
                {
                        // Remove any routes if the IP has changed
                        for (i = 0; i < MAXROUTE && session[s].route[i].ip; i++)
                        {
                                routeset(s, session[s].route[i].ip, session[s].route[i].mask, session[s].ip, 0);
                                session[s].route[i].ip = 0;
                        }

                        if (session[s].ip_pool_index == -1) // static IP
                                routeset(s, session[s].ip, 0, 0, 0);
                        else            // It's part of the IP pool, remove it manually.
                                uncache_ipmap(session[s].ip);
                }

                if (new->ip) {          // If there's a new one, add it.
                        if (new->ip_pool_index == -1)
                                routeset(s, new->ip, 0, 0, 1);
                        else
                                cache_ipmap(new->ip, s);
                }
        }

        // Update routed networks
        for (i = 0; i < MAXROUTE && (session[s].route[i].ip || new->route[i].ip); i++)
        {
                if (new->route[i].ip == session[s].route[i].ip &&
                    new->route[i].mask == session[s].route[i].mask)
                        continue;

                if (session[s].route[i].ip) // Remove the old one if it exists.
                        routeset(s, session[s].route[i].ip, session[s].route[i].mask, session[s].ip, 0);

                if (new->route[i].ip)   // Add the new one if it exists.
                        routeset(s, new->route[i].ip, new->route[i].mask, new->ip, 1);
        }

        if (new->tunnel && s > config->cluster_highest_sessionid)       // Maintain this in the slave. It's used
                                        // for walking the sessions to forward byte counts to the master.
                config->cluster_highest_sessionid = s;

        memcpy(&session[s], new, sizeof(session[s]));   // Copy over..

                // Do fixups into address pool.
        if (new->ip_pool_index != -1)
                fix_address_pool(s);

        return 1;
}

#ifdef RINGBUFFER
void ringbuffer_dump(FILE *stream)
{
        int i = ringbuffer->head;

        while (i != ringbuffer->tail)
        {
                if (*ringbuffer->buffer[i].message)
                        fprintf(stream, "%d-%s", ringbuffer->buffer[i].level, ringbuffer->buffer[i].message);
                if (++i == ringbuffer->tail) break;
                if (i == RINGBUFFER_SIZE) i = 0;
        }
}
#endif

void initplugins()
{
        int i;

        loaded_plugins = ll_init();
        // Initialize the plugins to nothing
        for (i = 0; i < MAX_PLUGIN_TYPES; i++)
                plugins[i] = ll_init();
}

static void *open_plugin(char *plugin_name, int load)
{
        char path[256] = "";

        snprintf(path, 256, PLUGINDIR "/%s.so", plugin_name);
        log(2, 0, 0, 0, "%soading plugin from %s\n", load ? "L" : "Un-l", path);
        return dlopen(path, RTLD_NOW);
}

void add_plugin(char *plugin_name)
{
        static struct pluginfuncs funcs = {
                _log,
                _log_hex,
                inet_toa,
                sessionbyuser,
                sessiontbysessionidt,
                sessionidtbysessiont,
                sessionkill,
                radiusnew,
                radiussend,
        };

        void *p = open_plugin(plugin_name, 1);
        int (*initfunc)(struct pluginfuncs *);
        int i;

        if (!p)
        {
                log(1, 0, 0, 0, "   Plugin load failed: %s\n", dlerror());
                return;
        }

        if (ll_contains(loaded_plugins, p))
        {
                dlclose(p);
                return;
        }

        {
                int *v = dlsym(p, "__plugin_api_version");
                if (!v || *v != PLUGIN_API_VERSION)
                {
                        log(1, 0, 0, 0, "   Plugin load failed: API version mismatch: %s\n", dlerror());
                        dlclose(p);
                        return;
                }
        }

        if ((initfunc = dlsym(p, "plugin_init")))
        {
                if (!initfunc(&funcs))
                {
                        log(1, 0, 0, 0, "   Plugin load failed: plugin_init() returned FALSE: %s\n", dlerror());
                        dlclose(p);
                        return;
                }
        }

        ll_push(loaded_plugins, p);

        for (i = 0; i < max_plugin_functions; i++)
        {
                void *x;
                if (plugin_functions[i] && (x = dlsym(p, plugin_functions[i])))
                {
                        log(3, 0, 0, 0, "   Supports function \"%s\"\n", plugin_functions[i]);
                        ll_push(plugins[i], x);
                }
        }

        log(2, 0, 0, 0, "   Loaded plugin %s\n", plugin_name);
}

static void run_plugin_done(void *plugin)
{
        int (*donefunc)(void) = dlsym(plugin, "plugin_done");

        if (donefunc)
                donefunc();
}

void remove_plugin(char *plugin_name)
{
        void *p = open_plugin(plugin_name, 0);
        int i;

        if (!p)
                return;

        for (i = 0; i < max_plugin_functions; i++)
        {
                void *x;
                if (plugin_functions[i] && (x = dlsym(p, plugin_functions[i])))
                        ll_delete(plugins[i], x);
        }

        if (ll_contains(loaded_plugins, p))
        {
                ll_delete(loaded_plugins, p);
                run_plugin_done(p);
        }

        dlclose(p);
        log(2, 0, 0, 0, "Removed plugin %s\n", plugin_name);
}

int run_plugins(int plugin_type, void *data)
{
        int (*func)(void *data);
        if (!plugins[plugin_type] || plugin_type > max_plugin_functions) return 1;

        ll_reset(plugins[plugin_type]);
        while ((func = ll_next(plugins[plugin_type])))
        {
                int rc;
                rc = func(data);
                if (rc == PLUGIN_RET_STOP) return 1;
                if (rc == PLUGIN_RET_ERROR) return 0;
        }
        return 1;
}

void plugins_done()
{
        void *p;

        ll_reset(loaded_plugins);
        while ((p = ll_next(loaded_plugins)))
                run_plugin_done(p);
}

void processcontrol(u8 * buf, int len, struct sockaddr_in *addr)
{
        char *resp;
        int l;
        struct param_control param = { buf, len, ntohl(addr->sin_addr.s_addr), ntohs(addr->sin_port), NULL, 0, 0 };


        if (log_stream && config->debug >= 4)
        {
                log(4, ntohl(addr->sin_addr.s_addr), 0, 0, "Received ");
                dump_packet(buf, log_stream);
        }

        resp = calloc(1400, 1);
        l = new_packet(PKT_RESP_ERROR, resp);
        *(int *)(resp + 6) = *(int *)(buf + 6);

        param.type = ntohs(*(short *)(buf + 2));
        param.id = ntohl(*(int *)(buf + 6));
        param.data_length = ntohs(*(short *)(buf + 4)) - 10;
        param.data = (param.data_length > 0) ? (char *)(buf + 10) : NULL;
        param.response = resp;
        param.response_length = l;

        run_plugins(PLUGIN_CONTROL, &param);

        if (param.send_response)
        {
                send_packet(controlfd, ntohl(addr->sin_addr.s_addr), ntohs(addr->sin_port), param.response, param.response_length);
                log(4, ntohl(addr->sin_addr.s_addr), 0, 0, "Sent Control packet response\n");
        }

        free(resp);
}

/*
 * HACK
 * Go through all of the tunnels and do some cleanups
 */
void tunnel_clean()
{
        int i;

        log(1, 0, 0, 0, "Cleaning tunnels array\n");

        for (i = 1; i < MAXTUNNEL; i++)
        {
                if (!tunnel[i].ip
                                || !*tunnel[i].hostname
                                || (tunnel[i].state == TUNNELDIE && tunnel[i].die >= time_now))
                {
                        tunnelclear(i);
                }
        }
}

void tunnelclear(tunnelidt t)
{
        if (!t) return;
        memset(&tunnel[t], 0, sizeof(tunnel[t]));
        tunnel[t].state = TUNNELFREE;
}

tunnelidt new_tunnel()
{
        tunnelidt i;
        for (i = 1; i < MAXTUNNEL; i++)
        {
                if (tunnel[i].state == TUNNELFREE)
                {
                        log(4, 0, 0, i, "Assigning tunnel ID %d\n", i);
                        if (i > config->cluster_highest_tunnelid)
                                config->cluster_highest_tunnelid = i;
                        return i;
                }
        }
        log(0, 0, 0, 0, "Can't find a free tunnel! There shouldn't be this many in use!\n");
        return 0;
}

//
// We're becoming the master. Do any required setup..
//
// This is principally telling all the plugins that we're
// now a master, and telling them about all the sessions
// that are active too..
//
void become_master(void)
{
        int s;
        run_plugins(PLUGIN_BECOME_MASTER, NULL);

        for (s = 1; s <= config->cluster_highest_sessionid ; ++s) {
                if (!session[s].tunnel) // Not an in-use session.
                        continue;

                run_plugins(PLUGIN_NEW_SESSION_MASTER, &session[s]);
        }
}



int cmd_show_hist_idle(struct cli_def *cli, char *command, char **argv, int argc)
{
        int s, i;
        int count = 0;
        int buckets[64];

        if (CLI_HELP_REQUESTED)
                return CLI_HELP_NO_ARGS;

        time(&time_now);
        for (i = 0; i < 64;++i) buckets[i] = 0;

        for (s = 1; s <= config->cluster_highest_sessionid ; ++s) {
                int idle;
                if (!session[s].tunnel)
                        continue;

                idle = time_now - session[s].last_packet;
                idle /= 5 ; // In multiples of 5 seconds.
                if (idle < 0)
                        idle = 0;
                if (idle > 63)
                        idle = 63;

                ++count;
                ++buckets[idle];
        }

        for (i = 0; i < 63; ++i) {
                cli_print(cli, "%3d seconds  : %7.2f%% (%6d)", i * 5, (double) buckets[i] * 100.0 / count , buckets[i]);
        }
        cli_print(cli, "lots of secs : %7.2f%% (%6d)", (double) buckets[63] * 100.0 / count , buckets[i]);
        cli_print(cli, "%d total sessions open.", count);
        return CLI_OK;
}

int cmd_show_hist_open(struct cli_def *cli, char *command, char **argv, int argc)
{
        int s, i;
        int count = 0;
        int buckets[64];

        if (CLI_HELP_REQUESTED)
                return CLI_HELP_NO_ARGS;

        time(&time_now);
        for (i = 0; i < 64;++i) buckets[i] = 0;

        for (s = 1; s <= config->cluster_highest_sessionid ; ++s) {
                int open = 0, d;
                if (!session[s].tunnel)
                        continue;

                d = time_now - session[s].opened;
                if (d < 0)
                        d = 0;
                while (d > 1 && open < 32) {
                        ++open;
                        d >>= 1; // half.
                }
                ++count;
                ++buckets[open];
        }

        s = 1;
        for (i = 0; i  < 30; ++i) {
                cli_print(cli, " < %8d seconds : %7.2f%% (%6d)", s, (double) buckets[i] * 100.0 / count , buckets[i]);
                s <<= 1;
        }
        cli_print(cli, "%d total sessions open.", count);
        return CLI_OK;
}