root/luci/branches/luci-0.8/contrib/package/freifunk-watchdog/src/watchdog.c @ 4511

/*
 *   This program is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation; either version 2 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
 *
 *   Copyright (C) 2009 Jo-Philipp Wich <xm@subsignal.org>
 */

#include "watchdog.h"

/* Global watchdog fd, required by signal handler */
int wdfd = -1;

/* Watchdog shutdown helper */
static void shutdown_watchdog(int sig)
{
    static int wdelay = 3600;
    static const char wshutdown = WATCH_SHUTDOWN;

    if( wdfd > -1 )
    {
        syslog(LOG_INFO, "Stopping watchdog timer");
        write(wdfd, &wshutdown, 1);

        /* Older Kamikaze versions are compiled with
         * CONFIG_WATCHDOG_NOWAYOUT=y, this can be
         * harmful if we're in the middle of an upgrade.
         * Increase the watchdog timeout to 3600 seconds
         * here to avoid unplanned reboots. */
        ioctl(wdfd, WDIOC_SETTIMEOUT, &wdelay);

        close(wdfd);
        wdfd = -1;
    }

    exit(0);
}

/* Get BSSID of given interface */
static int iw_get_bssid(int iwfd, const char *ifname, char *bssid)
{
    struct iwreq iwrq;

    if( iw_ioctl(iwfd, ifname, SIOCGIWAP, &iwrq) >= 0 )
    {
        unsigned char *addr = (unsigned char *)iwrq.u.ap_addr.sa_data;

        sprintf(bssid, "%02X:%02X:%02X:%02X:%02X:%02X",
            addr[0], addr[1], addr[2], addr[3], addr[4], addr[5]);

        return 0;
    }

    return -1;
}

/* Get channel of given interface */
static int iw_get_channel(int iwfd, const char *ifname, int *channel)
{
    int i;
    char buffer[sizeof(struct iw_range)];
    double cur_freq, cmp_freq;
    struct iwreq iwrq;
    struct iw_range *range;

    memset(buffer, 0, sizeof(buffer));

    iwrq.u.data.pointer = (char *)buffer;
    iwrq.u.data.length = sizeof(buffer);
    iwrq.u.data.flags = 0;

    if( iw_ioctl(iwfd, ifname, SIOCGIWRANGE, &iwrq) < 0)
    {
        *channel = -1;
        return -1;
    }

    range = (struct iw_range *)buffer;

    if( iw_ioctl(iwfd, ifname, SIOCGIWFREQ, &iwrq) >= 0 )
    {
        cur_freq = ((double)iwrq.u.freq.m) * pow(10, iwrq.u.freq.e);
        if( cur_freq < 1000.00 )
        {
            *channel = (int)cur_freq;
            return 0;
        }

        for(i = 0; i < range->num_frequency; i++)
        {
            cmp_freq = ((double)range->freq[i].m) * pow(10, range->freq[i].e);
            if( cmp_freq == cur_freq )
            {
                *channel = (int)range->freq[i].i;
                return 0;
            }
        }
    }

    *channel = -1;
    return -1;
}

/* Get the (first) pid of given process name */
static int find_process(const char *name)
{
    int pid = -1;
    int file;
    char buffer[128];
    char cmpname[128];
    DIR *dir;
    struct dirent *entry;

    if( (dir = opendir("/proc")) != NULL )
    {
        snprintf(cmpname, sizeof(cmpname), "Name:\t%s\n", name);

        while( (entry = readdir(dir)) != NULL )
        {
            if( !strcmp(entry->d_name, "..") || !isdigit(*entry->d_name) )
                continue;

            sprintf(buffer, "/proc/%s/status", entry->d_name);
            if( (file = open(buffer, O_RDONLY)) > -1 )
            {
                read(file, buffer, sizeof(buffer));
                close(file);

                if( strstr(buffer, cmpname) == buffer )
                {
                    pid = atoi(entry->d_name);

                    /* Skip myself ... */
                    if( pid == getpid() )
                        pid = -1;
                    else
                        break;
                }
            }
        }

        closedir(dir);
        return pid;
    }

    syslog(LOG_CRIT, "Unable to open /proc: %s",
        strerror(errno));

    return -1;
}

/* Get the 5 minute load average */
static double find_loadavg(void)
{
    int fd;
    char buffer[10];
    double load = 0.00;

    if( (fd = open("/proc/loadavg", O_RDONLY)) > -1 )
    {
        if( read(fd, buffer, sizeof(buffer)) == sizeof(buffer) )
            load = atof(&buffer[5]);

        close(fd);
    }

    return load;
}

/* Check if given uci file was updated */
static int check_uci_update(const char *config, time_t *mtime)
{
    struct stat s;
    char path[128];

    snprintf(path, sizeof(path), "/var/state/%s", config);
    if( stat(path, &s) > -1 )
    {
        if( (*mtime == 0) || (s.st_mtime > *mtime) )
        {
            *mtime = s.st_mtime;
            return 1;
        }

        return 0;
    }

    return -1;
}

/* Add tuple */
static void load_wifi_uci_add_iface(const char *section, struct uci_itr_ctx *itr)
{
    wifi_tuple_t *t;
    const char *ucitmp;
    int val = 0;

    if( (t = (wifi_tuple_t *)malloc(sizeof(wifi_tuple_t))) != NULL )
    {
        ucitmp = ucix_get_option(itr->ctx, "wireless", section, "ifname");
        if(ucitmp)
        {
            strncpy(t->ifname, ucitmp, sizeof(t->ifname));
            val++;
        }

        ucitmp = ucix_get_option(itr->ctx, "wireless", section, "bssid");
        if(ucitmp)
        {
            strncpy(t->bssid, ucitmp, sizeof(t->bssid));
            val++;
        }

        ucitmp = ucix_get_option(itr->ctx, "wireless", section, "device");
        if(ucitmp)
        {
            ucitmp = ucix_get_option(itr->ctx, "wireless", ucitmp, "channel");
            if(ucitmp)
            {
                t->channel = atoi(ucitmp);
                val++;
            }
        }

        if( val == 3 )
        {
            syslog(LOG_INFO, "Monitoring %s: bssid=%s channel=%d",
                t->ifname, t->bssid, t->channel);

            t->next = itr->list;
            itr->list = t;
        }
        else
        {
            free(t);
        }
    }
}

/* Load config */
static wifi_tuple_t * load_wifi_uci(wifi_tuple_t *ifs, time_t *modtime)
{
    struct uci_context *ctx;
    struct uci_itr_ctx itr;
    wifi_tuple_t *cur, *next;

    if( check_uci_update("wireless", modtime) )
    {
        syslog(LOG_INFO, "Config changed, reloading");

        if( (ctx = ucix_init("wireless")) != NULL )
        {
            if( ifs != NULL )
            {
                for(cur = ifs; cur; cur = next)
                {
                    next = cur->next;
                    free(cur);
                }
            }

            itr.list = NULL;
            itr.ctx = ctx;

            ucix_for_each_section_type(ctx, "wireless", "wifi-iface",
                (void *)load_wifi_uci_add_iface, &itr);

            return itr.list;
        }
    }

    return ifs;
}

/* Daemon implementation */
static int do_daemon(void)
{
    static int wdtrigger = 1;
    static int wdtimeout = INTERVAL * 2;
    static const char wdkeepalive = WATCH_KEEPALIVE;

    int iwfd;
    int channel;
    char bssid[18];
    struct sigaction sa;

    wifi_tuple_t *ifs = NULL, *curif;
    time_t modtime = 0;

    int restart_wifi = 0;
    int restart_cron = 0;
    int restart_sshd = 0;
    int loadavg_panic = 0;

    openlog(SYSLOG_IDENT, 0, LOG_DAEMON);
    //daemon(1, 1);

    if( (iwfd = socket(AF_INET, SOCK_DGRAM, 0)) == -1 )
    {
        syslog(LOG_ERR, "Can not open wireless control socket: %s",
            strerror(errno));

        return 1;
    }

    if( (wdfd = open(WATCH_DEVICE, O_WRONLY)) > -1 )
    {
        syslog(LOG_INFO, "Opened %s - polling every %i seconds",
            WATCH_DEVICE, INTERVAL);

        /* Install signal handler to halt watchdog on shutdown */
        sa.sa_handler = shutdown_watchdog;
        sa.sa_flags = SA_NOCLDWAIT | SA_RESTART;
        sigaction(SIGHUP,  &sa, NULL);
        sigaction(SIGINT,  &sa, NULL);
        sigaction(SIGPIPE, &sa, NULL);
        sigaction(SIGTERM, &sa, NULL);
        sigaction(SIGUSR1, &sa, NULL);
        sigaction(SIGUSR2, &sa, NULL);

        /* Set watchdog timeout to twice the interval */
        ioctl(wdfd, WDIOC_SETTIMEOUT, &wdtimeout);
    }

    while( 1 )
    {
        /* Check average load */
        if( find_loadavg() >= LOAD_TRESHOLD )
            loadavg_panic++;
        else
            loadavg_panic = 0;

        /* Check crond */
        if( find_process("crond") < 0 )
            restart_cron++;

        /* Check SSHd */
        if( find_process("dropbear") < 0 )
            restart_sshd++;

        /* Check wireless interfaces */
        ifs = load_wifi_uci(ifs, &modtime);
        for( curif = ifs; curif; curif = curif->next )
        {
            /* Get current channel and bssid */
            if( (iw_get_bssid(iwfd, curif->ifname, bssid) == 0) &&
                (iw_get_channel(iwfd, curif->ifname, &channel) == 0) )
            {
                /* Check BSSID */
                if( strcasecmp(bssid, curif->bssid) != 0 )
                {
                    syslog(LOG_WARNING, "BSSID mismatch on %s: current=%s wanted=%s",
                        curif->ifname, bssid, curif->bssid);

                    restart_wifi++;
                }

                /* Check channel */
                else if( channel != curif->channel )
                {
                    syslog(LOG_WARNING, "Channel mismatch on %s: current=%d wanted=%d",
                        curif->ifname, channel, curif->channel);

                    restart_wifi++;
                }
            }
            else
            {
                syslog(LOG_WARNING, "Requested interface %s not present", curif->ifname);
            }
        }


        /* Wifi restart required? */
        if( restart_wifi >= HYSTERESIS )
        {
            restart_wifi = 0;
            syslog(LOG_WARNING, "Channel or BSSID mismatch on wireless interface, restarting");
            EXEC(WIFI_ACTION);
        }

        /* Cron restart required? */
        if( restart_cron >= HYSTERESIS )
        {
            restart_cron = 0;
            syslog(LOG_WARNING, "The cron process died, restarting");
            EXEC(CRON_ACTION);
        }

        /* SSHd restart required? */
        if( restart_sshd >= HYSTERESIS )
        {
            restart_sshd = 0;
            syslog(LOG_WARNING, "The ssh process died, restarting");
            EXEC(SSHD_ACTION);
        }

        /* Is there a load problem? */
        if( loadavg_panic >= HYSTERESIS )
        {
            syslog(LOG_EMERG, "Critical system load level, triggering reset!");

            /* Try watchdog, fall back to reboot */
            if( wdfd > -1 )
                ioctl(wdfd, WDIOC_SETTIMEOUT, &wdtrigger);
            else
                EXEC(LOAD_ACTION);
        }

        /* Reset watchdog timer */
        if( wdfd > -1 )
            write(wdfd, &wdkeepalive, 1);

        sleep(INTERVAL);
    }

    shutdown_watchdog(0);
    closelog();

    return 0;
}


int main(int argc, char *argv[])
{
    /* Check if watchdog is running ... */
    if( (argc > 1) && (strcmp(argv[1], "running") == 0) )
    {
        return (find_process(BINARY) == -1);
    }

    /* Start daemon */
    return do_daemon();
}