Eliminated send_delay global (file) variable.

[icmpmonitor] / icmpmonitor.c

diff --git a/icmpmonitor.c b/icmpmonitor.c
index e8e777b..f2bf43e 100644 (file)
--- a/icmpmonitor.c
+++ b/icmpmonitor.c
@@ -1,653 +1,449 @@
 /*
 /*

- * Monitor hosts using ICMP "echo" and notify when down.
- * 
+ * ICMPmonitor
+ *
+ * Monitors hosts using ICMP 'echo', executing a user-specified command
+ * whenever hosts change state between responsive and unresponsive.
+ *

  * © 2019 Aaron Taylor <ataylor at subgeniuskitty dot com>
  * © 1999 Vadim Zaliva <lord@crocodile.org>
  * © 1989 The Regents of the University of California & Mike Muuss
  * © 2019 Aaron Taylor <ataylor at subgeniuskitty dot com>
  * © 1999 Vadim Zaliva <lord@crocodile.org>
  * © 1989 The Regents of the University of California & Mike Muuss

- * See LICENSE.txt file for copyright and license details.
+ *
+ * See LICENSE file for copyright and license details.

  */
 
  */
 

-#include <sys/param.h>

 #include <stdio.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <stdlib.h>

-#include <syslog.h>
-#include <stdarg.h>
+#include <stdbool.h>

 #include <signal.h>
 #include <string.h>
 #include <sys/time.h>
 #include <sys/wait.h>
 #include <sys/socket.h>
 #include <sys/types.h>
 #include <signal.h>
 #include <string.h>
 #include <sys/time.h>
 #include <sys/wait.h>
 #include <sys/socket.h>
 #include <sys/types.h>

-#include <fcntl.h>
-#include <sys/fcntl.h>

 #include <unistd.h>
 #include <unistd.h>

-#include <sys/stat.h>

 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <netdb.h>
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <netdb.h>

-#include <netinet/in_systm.h>

 #include <netinet/ip.h>
 #include <netinet/ip_icmp.h>
 #include <netinet/ip.h>
 #include <netinet/ip_icmp.h>

-#include <stddef.h>

 #include <errno.h>
 #include <errno.h>

+#include <assert.h>

 
 

-#include "cfg.h"
+#include "iniparser/iniparser.h"

 
 

-/* return codes */
-#define RET_OK         0
-#define RET_NO_HOSTS   1
-#define RET_INIT_ERROR 2
-#define RET_BAD_CFG    3
-#define RET_BAD_OPT    4
+#define VERSION 2

 
 

-#define        MAXPACKET       (65536 - 60 - 8) /* max packet size     */
-#define        DEFDATALEN      (64 - 8)         /* default data length */
+#define MAXPACKETSIZE  (65536 - 60 - 8) /* TODO: What are the magic numbers? */
+#define DEFAULTDATALEN (64 - 8)         /* TODO: What are the magic numbers? */

 
 

-#define VERSION "ICMPmonitor v1.2 by lord@crocodile.org"
-#define MAX_LOG_MSG_SIZE 4096
+/* ICMP header contains: type, code, checksum, identifier and sequence number. */
+#define ICMP_ECHO_HEADER_BYTES  8
+#define ICMP_ECHO_DATA_BYTES    sizeof(struct timeval)
+#define ICMP_ECHO_PACKET_BYTES  ICMP_ECHO_HEADER_BYTES + ICMP_ECHO_DATA_BYTES

 
 

-# define icmphdr                       icmp
+/* Minimum time in seconds between pings. If this value is increased above the */
+/* `ping_interval` for a given host, some pings to that host may not be sent.  */
+#define TIMER_RESOLUTION        1

 
 

-/* typedefs */
-typedef struct monitor_host
-{
-    /* following are coming from cfg */
-    char  *name;
+/* Must be larger than the length of the longest configuration key (currently 'start_condition'). */
+#define MAXCONFKEYLEN 20
+
+/* One struct per host as listed in the config file. */
+struct monitor_host {
+    /* From the config file */
+    char * name;

     int    ping_interval;
     int    max_delay;
     int    ping_interval;
     int    max_delay;

-    char  *upcmd;
-    char  *downcmd;
-
-    /* following values are calculated */
-    int    socket;
-    struct timeval last_ping_received;
-    struct timeval last_ping_sent;
-    int    up;
-    int    down;
+    char * up_cmd;
+    char * down_cmd;
+
+    /* Calculated values */
+    int                socket;
+    struct timeval     last_ping_received;
+    struct timeval     last_ping_sent;
+    bool               host_up;

     struct sockaddr_in dest;
 
     struct sockaddr_in dest;
 

-    unsigned int sentpackets ;
-    unsigned int recvdpackets;
-    
-    /* linked list */
-    struct monitor_host *next;
-} monitor_host_t;
-
-/* protos */
-static void logopen(void);
-static void logclose(void);
-static void log(int type, char *format, ...);
-static int  gethostaddr(const char *name);
-static void read_hosts(const char *cfg_file_name);
-static void init_hosts(void);
-static void get_response(void);
-static void pinger(int);
-static int  in_cksum(u_short *addr, int len);
-static void read_icmp_data(monitor_host_t *p);
-static void tvsub(struct timeval *out, struct timeval *in);
-static void done(int code);
-static void start_daemon(void);
-static int gcd(int x, int y);
-
-/* globals */
-
-static monitor_host_t **hosts      = NULL;
-static int             isDaemon    = 0; 
-static int             isVerbose   = 0;
-static int             keepBanging = 0;
-static unsigned short  ident;
-static int             send_delay  = 1;
-
-int main(int ac, char **av)
-{
-    extern char* optarg;
-    extern int   optind;
-    char         *cfgfile=NULL;
-    int          param;
-    
-    logopen();
-    log(LOG_INFO, VERSION " is starting.");
-
-    while((param = getopt(ac, av, "rvdf:")) != -1)
-       switch(param)
-        { 
-       case 'v':
-            isVerbose = 1;
-           break; 
-       case 'd':
-            isDaemon = 1;
-           break; 
-       case 'r':
-            keepBanging = 1;
-           break; 
-       case 'f':  
-           cfgfile=strdup(optarg);  
-           break;  
-       default: 
-           fprintf(stderr,"Usage: icmpmonitor [-d] [-v] [-r] [-f cfgfile]\n");
-            done(RET_BAD_OPT);
-       } 
-    
-    if(!cfgfile)
-    {
-        log(LOG_WARNING,"No cfg file specified. Assuming 'icmpmonitor.cfg'");
-       cfgfile="icmpmonitor.cfg";
-    }
+    /* Linked list */
+    struct monitor_host * next;
+};

 
 

-    read_hosts(cfgfile); /* we do this before becoming daemon,
-                            to be able process relative path */
+/* Globals */
+    /* Since the program is based around signals, a linked list of hosts is maintained here. */
+    static struct monitor_host * hosts          = NULL;
+    /* Set by command line flags. */
+    static bool                  verbose        = false;
+    static bool                  retry_down_cmd = false;

 
 

-    if(isDaemon)
-        start_daemon();
-    
-    init_hosts();
-    
-    ident=getpid() & 0xFFFF;
-    
-    (void)signal(SIGALRM, pinger);
-    alarm(send_delay); 
-
-    get_response();
-    
-    done(RET_OK);
+/*
+ * Generate an Internet Checksum per RFC 1071.
+ *
+ * This is not a general purpose implementation of RFC 1071.  Since we only
+ * send ICMP echo packets, we assume 'data' will contain a specific number of
+ * bytes.
+ */
+uint16_t
+checksum(uint16_t * data)
+{
+    uint32_t accumulator = 0;
+    for (size_t i = 0; i < ICMP_ECHO_PACKET_BYTES / 2; i++) {
+        accumulator += ntohs(data[i]);
+        if (accumulator > 0xffff) accumulator -= 0xffff;
+    }
+    return htons(~accumulator);

 }
 
 }
 

-

 /*
 /*

- * in_cksum --
- *     Checksum routine for Internet Protocol family headers (C Version)
+ * Calculate difference between two timeval structs to within one second.

  */
  */

-static int
-in_cksum(u_short *addr, int len)
+void
+timeval_diff(struct timeval * a, const struct timeval * b)

 {
 {

-    register int nleft = len;
-    register u_short *w = addr;
-    register int sum = 0;
-    u_short answer = 0;
-    
-    /*
-     * Our algorithm is simple, using a 32 bit accumulator (sum), we add
-     * sequential 16 bit words to it, and at the end, fold back all the
-     * carry bits from the top 16 bits into the lower 16 bits.
-     */
-    while (nleft > 1)  {
-        sum += *w++;
-        nleft -= 2;
-    }
-    
-    /* mop up an odd byte, if necessary */
-    if (nleft == 1) {
-        *(u_char *)(&answer) = *(u_char *)w ;
-        sum += answer;
-    }
-    
-    /* add back carry outs from top 16 bits to low 16 bits */
-    sum = (sum >> 16) + (sum & 0xffff);        /* add hi 16 to low 16 */
-    sum += (sum >> 16);                        /* add carry */
-    answer = ~sum;                     /* truncate to 16 bits */
-    return(answer);
+    assert(a->tv_sec >= b->tv_sec);
+    a->tv_sec -= b->tv_sec;

 }
 
 /*
 }
 
 /*

- * pinger --
- *     Compose and transmit an ICMP ECHO REQUEST packet.  The IP packet
- * will be added on by the kernel.  The ID field is our UNIX process ID,
- * and the sequence number is an ascending integer.  The first 8 bytes
+ * Compose and transmit an ICMP ECHO REQUEST packet. The IP packet
+ * will be added on by the kernel. The ID field is our UNIX process ID,
+ * and the sequence number is an ascending integer. The first 8 bytes

  * of the data portion are used to hold a UNIX "timeval" struct in VAX
  * byte-order, to compute the round-trip time.
  */
  * of the data portion are used to hold a UNIX "timeval" struct in VAX
  * byte-order, to compute the round-trip time.
  */

-static void pinger(int ignore)
+static void
+pinger(int ignore)

 {
 {

-    register struct icmphdr *icp;
-    register int             cc;
-    int                      i;
-    monitor_host_t           *p;
-    u_char outpack[MAXPACKET];
-
-    p=hosts[0];
-    while(p)
-    {
-        if(p->socket!=-1)
-        {
+    int i;
+    struct icmp * icp;
+    struct monitor_host * p = hosts;
+    unsigned char outpack[MAXPACKETSIZE]; /* Use char so this can be aliased later. */
+
+    while (p) {
+        if (p->socket != -1) {

             struct timeval now;
             struct timeval now;

-            
-            (void)gettimeofday(&now,(struct timezone *)NULL);
-            tvsub(&now, &p->last_ping_received);
-
-            if(now.tv_sec > (p->max_delay+p->ping_interval))
-            {            
-                p->up=0;
-                if((!p->down) || keepBanging)
-                {
-                   p->down = 1;
-                    
-                    if(isVerbose)
-                        log(LOG_INFO,"Host %s in down. Executing DOWN command",p->name);
-                    if(!fork())
-                    {
-                        system(p->downcmd);
-                        exit(0);
-                    } else
-                    {
+
+            gettimeofday(&now, (struct timezone *) NULL);
+            timeval_diff(&now, &p->last_ping_received);
+
+            if (now.tv_sec > (p->max_delay + p->ping_interval)) {
+                if ((p->host_up) || retry_down_cmd) {
+                    if (verbose) printf("INFO: Host %s stopped responding. Executing DOWN command.\n", p->name);
+                    p->host_up = false;
+                    if (!fork()) {
+                        system(p->down_cmd);
+                        exit(EXIT_SUCCESS);
+                    } else {

                         wait(NULL);
                     }
                 }
             }
                         wait(NULL);
                     }
                 }
             }

-            
-            (void)gettimeofday(&now,(struct timezone *)NULL);
-            tvsub(&now, &p->last_ping_sent);
-            
-            if(now.tv_sec > p->ping_interval)
-            {
-                /* Time to send ping */
-                
-                icp = (struct icmphdr *)outpack;
+
+            gettimeofday(&now, (struct timezone *) NULL);
+            timeval_diff(&now, &p->last_ping_sent);
+
+            if (now.tv_sec > p->ping_interval) { /* Time to send ping */
+                icp = (struct icmp *) outpack;

                 icp->icmp_type  = ICMP_ECHO;
                 icp->icmp_code  = 0;
                 icp->icmp_cksum = 0;
                 icp->icmp_seq   = p->socket;
                 icp->icmp_type  = ICMP_ECHO;
                 icp->icmp_code  = 0;
                 icp->icmp_cksum = 0;
                 icp->icmp_seq   = p->socket;

-                icp->icmp_id    = ident;                       
-
-                if(isVerbose)
-                    log(LOG_INFO,"Sending ICMP packet to %s.",p->name);
-                
-                (void)gettimeofday((struct timeval *)&outpack[8],
-                                   (struct timezone *)NULL);
-                
-                cc = DEFDATALEN + 8;  /* skips ICMP portion */
-                
-                /* compute ICMP checksum here */
-                icp->icmp_cksum = in_cksum((u_short *)icp, cc);
-                
-                i = sendto(p->socket, (char *)outpack, cc, 0, (const struct sockaddr *)(&p->dest),
-                           sizeof(struct sockaddr));
-                
-                (void)gettimeofday(&p->last_ping_sent,
-                                   (struct timezone *)NULL);
-                
-                if(i<0 || i!=cc)
-                {
-                    if(i<0)
-                        log(LOG_WARNING,"Sending ICMP packet to %s failed.",p->name);
+                icp->icmp_id    = getpid() & 0xFFFF;
+
+                if (verbose) printf("INFO: Sending ICMP packet to %s.\n", p->name);
+
+                gettimeofday((struct timeval *) &outpack[8], (struct timezone *) NULL);
+
+                int cc = DEFAULTDATALEN + 8;  /* skips ICMP portion */
+
+                icp->icmp_cksum = checksum((uint16_t *) outpack);
+
+                i = sendto(p->socket, (char *) outpack, cc, 0, (const struct sockaddr *) (&p->dest), sizeof(struct sockaddr));
+
+                gettimeofday(&p->last_ping_sent, (struct timezone *) NULL);
+
+                if (i < 0 || i != cc) {
+                    if (i<0) fprintf(stderr, "WARN: Failed sending ICMP packet to %s.\n", p->name);

                 }
                 }

-                p->sentpackets++;

             }
         }
             }
         }

-        p=p->next;
-        
+        p = p->next;

     }
     }

-    
-    (void)signal(SIGALRM, pinger); /* restore handler */
-    alarm(send_delay);
+
+    signal(SIGALRM, pinger); /* restore handler */
+    alarm(TIMER_RESOLUTION);

 }
 
 }
 

-static void get_response(void)
+static void
+read_icmp_data(struct monitor_host * p)
+{
+    int cc, iphdrlen, delay;
+    socklen_t fromlen;
+    struct sockaddr_in from;
+    struct ip * ip;
+    struct icmp * icmp;
+    struct timeval tv;
+    unsigned char buf[MAXPACKETSIZE];
+
+    gettimeofday(&tv, (struct timezone *) NULL);
+
+    fromlen = sizeof(from);
+    if ((cc = recvfrom(p->socket, buf, sizeof(buf), 0, (struct sockaddr *)&from, &fromlen)) < 0) {
+        if (errno != EINTR) fprintf(stderr, "WARN: Error reading ICMP data from %s.\n", p->name);
+        return;
+    }
+
+    /* check IP header actual len */
+    ip       = (struct ip *) buf;
+    iphdrlen = ip->ip_hl << 2;
+    icmp     = (struct icmp *) (buf + iphdrlen);
+
+    if (cc < iphdrlen + ICMP_MINLEN) {
+        fprintf(stderr, "WARN: Received short packet from %s.\n", p->name);
+        return;
+    }
+
+    if (icmp->icmp_type == ICMP_ECHOREPLY && icmp->icmp_id == (getpid() & 0xFFFF) && icmp->icmp_seq == p->socket) {
+
+        memcpy(&p->last_ping_received, &tv, sizeof(tv));
+
+        timeval_diff(&tv, (struct timeval *) &icmp->icmp_data[0]);
+        delay = tv.tv_sec * 1000 + (tv.tv_usec / 1000);
+
+        if (verbose) printf("INFO: Got ICMP reply from %s.\n", p->name);
+        if (!p->host_up) {
+            if (verbose) printf("INFO: Host %s started responding. Executing UP command.\n", p->name);
+            p->host_up = true;
+            if (!fork()) {
+                system(p->up_cmd);
+                exit(EXIT_SUCCESS);
+            } else {
+                wait(NULL);
+            }
+        }
+    } else {
+        /* TODO: Do anything here? */
+    }
+}
+
+static void
+get_response(void)

 {
     fd_set rfds;
 {
     fd_set rfds;

-    int    retval;
-    monitor_host_t *p;
-    int    maxd=-1;
-    
-    while(1)
-    {
-        p=hosts[0];
+    int retval, maxd = -1;
+    struct monitor_host * p;
+
+    while (1) {
+        p = hosts;

         FD_ZERO(&rfds);
         FD_ZERO(&rfds);

-        while(p)
-        {
-            if(p->socket != -1)
-            {
-                if(p->socket > maxd)
-                    maxd=p->socket;
+        while (p) {
+            if (p->socket != -1) {
+                if (p->socket > maxd) maxd = p->socket;

                 FD_SET(p->socket, &rfds);
             }
                 FD_SET(p->socket, &rfds);
             }

-            p=p->next;
+            p = p->next;

         }
 
         retval = select(maxd+1, &rfds, NULL, NULL, NULL);
         }
 
         retval = select(maxd+1, &rfds, NULL, NULL, NULL);

-        if(retval<0)
-        {
-            /* we get her in case we are interrupted by signal.
-               it's ok. */
-        }
-        else
-        {
-            if(retval>0)
-            {
-                /* log(LOG_DEBUG,"ICMP data is available now."); */
-                p=hosts[0];
-                while(p)
-                {
-                    if(p->socket!=-1 && FD_ISSET(p->socket, &rfds))
-                    {
-                        /* Read data */
-                        read_icmp_data(p);
-                    }
-                    p=p->next;
+        if (retval < 0) {
+            /* Intentionally empty. We arrive here when interrupted by a signal. No action should be taken. */
+        } else {
+            if (retval > 0) {
+                p = hosts;
+                while (p) {
+                    if (p->socket!=-1 && FD_ISSET(p->socket, &rfds)) read_icmp_data(p);
+                    p = p->next;

                 }
                 }

-            } else
-            {
-                log(LOG_DEBUG,"select returns 0."); /* TODO */
+            } else {
+                /* TODO: How to handle this error? */

             }
         }
     }
 }
 
             }
         }
     }
 }
 

-static void read_icmp_data(monitor_host_t *p)
+static void
+parse_config(const char * conf_file)

 {
 {

-    socklen_t fromlen       ;
-    struct sockaddr_in from ;
-    int cc                  ;
-    struct ip   *ip         ;
-    struct icmp *icmp       ;
-    int    iphdrlen         ;
-    int    delay            ;
-    struct timeval tv       ;
-    unsigned char buf[MAXPACKET]; /* read buffer */
-
-    (void)gettimeofday(&tv, (struct timezone *)NULL);
-    
-    fromlen = sizeof(from);
-    if((cc = recvfrom(p->socket, buf, sizeof(buf), 0,
-                      (struct sockaddr *)&from, &fromlen)) < 0)
-    {
-        if(errno != EINTR)
-            log(LOG_WARNING,"Error reading ICMP data from %s.",p->name);
-        return;
-    } 
-
-    /* log(LOG_DEBUG,"Got %d bytes of ICMP data from %s.",cc, p->name); */
-
-    /* check IP header actual len */ 
-    ip       = (struct ip *)buf               ; 
-    iphdrlen = ip->ip_hl<<2                   ; 
-    icmp     = (struct icmp *) (buf+iphdrlen) ;
-    
-    if(cc < iphdrlen+ICMP_MINLEN)
-    {
-        log(LOG_WARNING,"Received short packet from %s.",p->name);
-        return;
+    dictionary * conf = iniparser_load(conf_file);
+    if (conf == NULL) {
+        fprintf(stderr, "ERROR: Unable to parse configuration file %s.\n", conf_file);
+        exit(EXIT_FAILURE);

     }
     }

-    
-    if(icmp->icmp_type == ICMP_ECHOREPLY &&
-       icmp->icmp_id   == ident          &&
-       icmp->icmp_seq  == p->socket)
-    {
-        p->recvdpackets++;

 
 

-        memcpy(&p->last_ping_received, &tv, sizeof(tv));
-        
-        tvsub(&tv, (struct timeval *) &icmp->icmp_data[0]);
-        delay=tv.tv_sec*1000+(tv.tv_usec/1000);
-        
-        if(isVerbose)
-            log(LOG_INFO,"Got ICMP reply from %s in %d ms.",p->name,delay);
-       p->down=0;
-        if(!p->up)
-        {
-            p->up=1;
-            if(isVerbose)
-                log(LOG_INFO,"Host %s in now up. Executing UP command",p->name);
-            if(!fork())
-            {
-                system(p->upcmd);
-                exit(0);
-            } else
-            {
-                wait(NULL);
-            }
+    int host_count = iniparser_getnsec(conf);
+    if (host_count < 1 ) {
+        fprintf(stderr, "ERROR: Unable to determine number of hosts in configuration file.\n");
+        exit(EXIT_FAILURE);
+    }
+
+    struct monitor_host * host_list_end = NULL;
+    for (int i=0; i < host_count; i++) {
+        /* Allocate a reusable buffer large enough to hold the full 'section:key' string. */
+        int section_len = strlen(iniparser_getsecname(conf, i));
+        char * key_buf = malloc(section_len + 1 + MAXCONFKEYLEN + 1);
+        strcpy(key_buf, iniparser_getsecname(conf, i));
+        key_buf[section_len++] = ':';
+
+        struct monitor_host * cur_host = malloc(sizeof(struct monitor_host));
+
+        key_buf[section_len] = '\0';
+        strncat(key_buf, "host", MAXCONFKEYLEN);
+        cur_host->name = strdup(iniparser_getstring(conf, key_buf, NULL));
+
+        key_buf[section_len] = '\0';
+        strncat(key_buf, "interval", MAXCONFKEYLEN);
+        cur_host->ping_interval = iniparser_getint(conf, key_buf, -1);
+
+        key_buf[section_len] = '\0';
+        strncat(key_buf, "max_delay", MAXCONFKEYLEN);
+        cur_host->max_delay = iniparser_getint(conf, key_buf, -1);
+
+        key_buf[section_len] = '\0';
+        strncat(key_buf, "up_cmd", MAXCONFKEYLEN);
+        cur_host->up_cmd = strdup(iniparser_getstring(conf, key_buf, NULL));
+
+        key_buf[section_len] = '\0';
+        strncat(key_buf, "down_cmd", MAXCONFKEYLEN);
+        cur_host->down_cmd = strdup(iniparser_getstring(conf, key_buf, NULL));
+
+        key_buf[section_len] = '\0';
+        /* TODO: Parse for up/down/auto in start_condition. */
+        /* TODO: Do a host up/down check if necessary. */
+        cur_host->host_up = true;
+
+        /* TODO: Do I want to make any checks for start_condition? */
+        if (cur_host->name == NULL || cur_host->ping_interval == -1 || cur_host->max_delay == -1) {
+            fprintf(stderr, "ERROR: Problems parsing section %s.\n", iniparser_getsecname(conf, i));
+            exit(EXIT_FAILURE);
+        }
+
+        cur_host->socket = -1;
+        cur_host->next = NULL;
+        gettimeofday(&(cur_host->last_ping_received), (struct timezone *) NULL);
+
+        if (hosts == NULL) {
+            hosts = cur_host;
+            host_list_end = cur_host;
+        } else {
+            host_list_end->next = cur_host;
+            host_list_end = cur_host;

         }
         }

-    } else
-    {
-        /*
-          log(LOG_DEBUG,"ICMP packet of type %d from %s. Ident=%d",icmp->icmp_type,
-          p->name,
-          icmp->icmp_id
-          );
-        */
+
+        free(key_buf);

     }
     }

+    iniparser_freedict(conf);

 }
 
 }
 

-static void read_hosts(const char *cfg_file_name)
+static int
+get_host_addr(const char * name)

 {
 {

-    int    i,n=0;
-    struct Cfg *cfg;
-    
-    if((cfg=readcfg(cfg_file_name))==NULL)
-    {
-        log(LOG_ERR,"Error reading cfg. Exiting.");
-        done(RET_BAD_CFG);
-    }
-    
-    if(cfg->nelements)
-    {
-        hosts=malloc(sizeof(monitor_host_t *)*cfg->nelements);
-        for(i=0;i<cfg->nelements;i++)
-        {
-            if(cfg->dict[i]->nvalues<4)
-            {
-                log(LOG_ERR,"Not enough fields in record %d of cfg file. Got %d.",n, cfg->dict[i]->nvalues+1);
-                done(RET_BAD_CFG);
-            } else if(cfg->dict[i]->nvalues>5)
-            {
-                log(LOG_ERR,"Too many fields in record %d of cfg file. Got %d.",n, cfg->dict[i]->nvalues+1);
-                done(RET_BAD_CFG);
-            }
-            
-            hosts[n]=malloc(sizeof(monitor_host_t));
-            hosts[n]->name          = strdup(cfg->dict[i]->name);
-            hosts[n]->ping_interval = atoi  (cfg->dict[i]->value[0]);
-            hosts[n]->max_delay     = atoi  (cfg->dict[i]->value[1]);
-            hosts[n]->upcmd         = strdup(cfg->dict[i]->value[2]);
-            hosts[n]->downcmd       = strdup(cfg->dict[i]->value[3]);
-            
-           if(cfg->dict[i]->nvalues==4)
-           {
-               hosts[n]->down = 0;
-               hosts[n]->up   = 1;
-           } else if(strcmp(cfg->dict[i]->value[4], "up")==0)
-           {
-               hosts[n]->down = 0;
-               hosts[n]->up   = 1;
-           } else if(strcmp(cfg->dict[i]->value[4], "down")==0)
-           {
-               hosts[n]->down = 1;
-               hosts[n]->up   = 0;
-           } else if(strcmp(cfg->dict[i]->value[4], "auto")==0)
-           {
-               hosts[n]->down = 1;
-               hosts[n]->up   = 1;
-           } else if(strcmp(cfg->dict[i]->value[4], "none")==0)
-           {
-               hosts[n]->down = 0;
-               hosts[n]->up   = 0;
-           } else
-           {
-               log(LOG_ERR,"Illegal value %s in record %n for startup condition.", cfg->dict[i]->value[4], n);
-               done(RET_BAD_CFG);
-           }
-            hosts[n]->sentpackets   = 0;
-            hosts[n]->recvdpackets  = 0;
-
-            hosts[n]->socket           = -1;
-            hosts[n]->next             = nil;
-            if(n>0)
-                hosts[n-1]->next=hosts[n];
-            (void)gettimeofday(&(hosts[n]->last_ping_received), (struct timezone *)NULL);
-
-            n++;
-        } 
-    }
-
-    freecfg(cfg);
+    static int res;
+    struct hostent * host_ent;

 
 

-    if(n<=0)
-    {
-        log(LOG_ERR,"No hosts defined in cfg file, exiting.");
-        done(RET_NO_HOSTS);
+    if ((res = inet_addr(name)) < 0) {
+        host_ent = gethostbyname(name);
+        if (!host_ent) return -1;
+        memcpy(&res, host_ent->h_addr, host_ent->h_length);

     }
     }

-    else
-        log(LOG_DEBUG,"%d host(s) found in cfg file,", n);
-    
+    return(res);

 }
 
 }
 

-static int gethostaddr(const char *name)
+static int
+gcd(int x, int y)

 {
 {

-    static  int  res;
-    struct hostent *he;
-    
-    if((res=inet_addr(name))<0)
-    {
-       he=gethostbyname(name);
-        if(!he)
-            return -1;
-       memcpy( &res , he->h_addr , he->h_length );
-    } 
-    return(res);
+    int remainder = x % y;
+    if (remainder == 0) return y;
+    return gcd(y, remainder);

 }
 
 }
 

-static void init_hosts(void)
+static void
+init_hosts(void)

 {
 {

-    monitor_host_t *p=hosts[0];
-    struct protoent   *proto;
-    int ok=0;
-
-    if((proto=getprotobyname("icmp"))==NULL)
-    {
-        log(LOG_ERR,"Unknown protocol: icmp. Exiting.");
-        done(RET_INIT_ERROR);
+    struct monitor_host * p = hosts;
+    struct protoent * proto;
+    int ok = 0;
+
+    if ((proto = getprotobyname("icmp")) == NULL) {
+        fprintf(stderr, "ERROR: Unknown protocol: icmp.\n");
+        exit(EXIT_FAILURE);

     }
     }

-    
-    while(p)
-    {
-        log(LOG_DEBUG,"resolving host %s", p->name);
-        
-        bzero(&p->dest,sizeof(p->dest));
-        p->dest.sin_family=AF_INET;
-        if((p->dest.sin_addr.s_addr=gethostaddr(p->name))<=0)
-        {
-            log(LOG_ERR,"Can't resolve host. Skipping client %s.",p->name);
+
+    while (p) {
+        bzero(&p->dest, sizeof(p->dest));
+        p->dest.sin_family = AF_INET;
+        if ((p->dest.sin_addr.s_addr = get_host_addr(p->name)) <= 0) {
+            fprintf(stderr, "WARN: Can't resolve host. Skipping client %s.\n", p->name);

             p->socket=-1;
             p->socket=-1;

-        } else
-        {
-            if((p->socket=socket(AF_INET,SOCK_RAW,proto->p_proto))<0)
-            {
-                log(LOG_ERR,"Can't create socket. Skipping client %s.",p->name);
+        } else {
+            if ((p->socket = socket(AF_INET,SOCK_RAW,proto->p_proto)) < 0) {
+                fprintf(stderr, "WARN: Can't create socket. Skipping client %s.\n", p->name);

                 p->socket=-1;
                 p->socket=-1;

-            } else
-            {
-                if(ok==0)
-                    send_delay = p->ping_interval;
-                else
-                    send_delay = gcd(send_delay, p->ping_interval);
+            } else {
+                //if (ok == 0) send_delay = p->ping_interval;
+                //else send_delay = gcd(send_delay, p->ping_interval);

                 ok++;
             }
         }
                 ok++;
             }
         }

-        p=p->next;
+        p = p->next;

     }
 
     }
 

-    if(!ok)
-    {
-        log(LOG_ERR,"No hosts left to process, exiting.");
-        done(RET_NO_HOSTS);
+    if (!ok) {
+        fprintf(stderr, "ERROR: No hosts left to process.\n");
+        exit(EXIT_FAILURE);

     }
 }
 
     }
 }
 

-/*
- * tvsub --
- *     Subtract 2 timeval structs:  out = out - in.  Out is assumed to
- * be >= in.
- */
-static void
-tvsub(register struct timeval *out, register struct timeval *in)
+void
+print_usage(char ** argv)

 {
 {

-       if ((out->tv_usec -= in->tv_usec) < 0) {
-               --out->tv_sec;
-               out->tv_usec += 1000000;
-       }
-       out->tv_sec -= in->tv_sec;
+    printf( "ICMPmonitor v%d (www.subgeniuskitty.com)\n"
+            "Usage: %s [-h] [-v] [-r] -f <file>\n"
+            "  -v         Verbose mode. Prints message for each packet sent and received.\n"
+            "  -r         Repeat down_cmd every time a host fails to respond to a packet.\n"
+            "             Note: Default behavior executes down_cmd only once, resetting once the host is back up.\n"
+            "  -h         Help (prints this message)\n"
+            "  -f <file>  Specify a configuration file.\n"
+            , VERSION, argv[0]);

 }
 
 }
 

-void done(int code)
+void
+parse_params(int argc, char ** argv)

 {
 {

-    logclose();
-    exit(code);
-}
-
-void start_daemon(void)
-{
-    if(fork())
-       exit(0);
-    
-    chdir("/");
-    umask(0);
-    (void) close(0);
-    (void) close(1);
-    (void) close(2);
-    (void) open("/", O_RDONLY);
-    (void) dup2(0, 1);
-    (void) dup2(0, 2);
-    setsid();
+    int param;
+    while ((param = getopt(argc, argv, "hrvf:")) != -1) {
+        switch(param) {
+            case 'v':
+                verbose = true;
+                break;
+            case 'r':
+                retry_down_cmd = true;
+                break;
+            case 'f':
+                parse_config(optarg);
+                break;
+            case 'h':
+            default:
+                print_usage(argv);
+                exit(EXIT_FAILURE);
+                break;
+        }
+    }
+    if (hosts == NULL) {
+        fprintf(stderr, "ERROR: Unable to parse a config file.\n");
+        exit(EXIT_FAILURE);
+    }

 }
 
 }
 

-static void logopen(void)
+int
+main(int argc, char ** argv)

 {
 {

-    if(isDaemon)
-        openlog("icmpmonitor", LOG_PID| LOG_CONS|LOG_NOWAIT, LOG_USER);
-}
+    parse_params(argc, argv);

 
 

-static void logclose(void)
-{
-    if(isDaemon)
-        closelog();
-}
+    init_hosts();

 
 

-/**
- * This function should be used as central logging facility.
- * 'type' argument should be one of following:
- *
- *  LOG_EMERG  system is unusable 
- *  LOG_ALERT  action must be taken immediately 
- *  LOG_CRIT   critical conditions 
- *  LOG_ERR    error conditions 
- *  LOG_WARNING        warning conditions 
- *  LOG_NOTICE normal but significant condition 
- *  LOG_INFO   informational 
- *  LOG_DEBUG  debug-level messages 
- */
-static void log(int type, char *format, ...)
-{
-    va_list ap;
+    signal(SIGALRM, pinger);
+    alarm(TIMER_RESOLUTION);

 
 

-#ifndef DEBUG
-    if(type==LOG_DEBUG)
-        return;
-#endif
-    
-    va_start(ap, format);
-
-    if(isDaemon)
-    {
-        char buffer[MAX_LOG_MSG_SIZE];
-            
-        (void)vsnprintf(buffer, MAX_LOG_MSG_SIZE, format, ap);
-        syslog(type,buffer);
-    } else
-    {
-        (void)  fprintf(stderr, "icmpmonitor[%d]:", (int)getpid());
-        (void) vfprintf(stderr, format, ap);
-        (void)  fprintf(stderr, "\n");
-    }
-    va_end(ap);
-}
+    get_response();

 
 

-static int gcd(int x, int y)
-{
-    while(x!=y)
-    {
-        if(x<y)
-            y-=x;
-        else 
-            x-=y;
-    }
-    return x;
+    exit(EXIT_SUCCESS);

 }
 }