/*
* Monitor hosts using ICMP "echo" and notify when down.
- *
+ *
* © 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 file for copyright and license details.
*/
-#include <sys/param.h>
#include <stdio.h>
#include <stdlib.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 <fcntl.h>
-#include <sys/fcntl.h>
#include <unistd.h>
-#include <sys/stat.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 <stddef.h>
#include <errno.h>
#include "cfg.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 MAXPACKETSIZE (65536 - 60 - 8) /* TODO: What are the magic numbers? */
+#define DEFAULTDATALEN (64 - 8) /* TODO: What are the magic numbers? */
-#define MAXPACKET (65536 - 60 - 8) /* max packet size */
-#define DEFDATALEN (64 - 8) /* default data length */
-
-#define VERSION "ICMPmonitor v1.2 by lord@crocodile.org"
-
-# define icmphdr icmp
-
-/* typedefs */
-typedef struct monitor_host
-{
- /* following are coming from cfg */
- char *name;
+struct monitor_host {
+ /* From the config file */
+ char * name;
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 * upcmd;
+ char * downcmd;
+
+ /* Calculated values */
+ int socket;
+ struct timeval last_ping_received;
+ struct timeval last_ping_sent;
+ bool hostup;
struct sockaddr_in dest;
+ unsigned int sentpackets;
+ unsigned int recvdpackets;
- unsigned int sentpackets ;
- unsigned int recvdpackets;
-
/* linked list */
- struct monitor_host *next;
-} monitor_host_t;
-
-/* protos */
-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 int gcd(int x, int y);
+ struct monitor_host * next;
+};
/* globals */
-
-static monitor_host_t **hosts = NULL;
-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;
-
- while((param = getopt(ac, av, "rvf:")) != -1)
- switch(param)
- {
- case 'v':
- isVerbose = 1;
- break;
- case 'r':
- keepBanging = 1;
- break;
- case 'f':
- cfgfile=strdup(optarg);
- break;
- default:
- fprintf(stderr,"Usage: icmpmonitor [-v] [-r] [-f cfgfile]\n");
- done(RET_BAD_OPT);
- }
-
- if (!cfgfile) {
- fprintf(stderr, "ERROR: No config file specified.\n");
- exit(EXIT_FAILURE);
- }
-
- read_hosts(cfgfile);
-
- init_hosts();
-
- ident=getpid() & 0xFFFF;
-
- (void)signal(SIGALRM, pinger);
- alarm(send_delay);
-
- get_response();
-
- done(RET_OK);
-}
-
+static struct monitor_host ** hosts = NULL;
+static int isVerbose = 0;
+static int keepBanging = 0;
+static int send_delay = 1;
/*
- * in_cksum --
- * Checksum routine for Internet Protocol family headers (C Version)
+ * Checksum routine for Internet Protocol family headers
*/
static int
-in_cksum(u_short *addr, int len)
+in_cksum(unsigned short * addr, int len)
{
- register int nleft = len;
- register u_short *w = addr;
- register int sum = 0;
- u_short answer = 0;
-
+ int nleft = len;
+ unsigned short * w = addr;
+ int sum = 0;
+ unsigned 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) {
+ while (nleft > 1) {
sum += *w++;
nleft -= 2;
}
-
+
/* mop up an odd byte, if necessary */
if (nleft == 1) {
- *(u_char *)(&answer) = *(u_char *)w ;
+ *(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 */
+ sum = (sum >> 16) + (sum & 0xffff); /* add hi 16 to low 16 */
+ sum += (sum >> 16); /* add carry */
+ answer = ~sum; /* truncate to 16 bits */
return(answer);
}
/*
- * 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
+ * Subtracts two timeval structs.
+ * Ensure out >= in.
+ * Modifies out = out - in.
+ */
+static void
+tvsub(register struct timeval * out, register struct timeval * in)
+{
+ if ((out->tv_usec -= in->tv_usec) < 0) {
+ --out->tv_sec;
+ out->tv_usec += 1000000;
+ }
+ out->tv_sec -= in->tv_sec;
+}
+
+/*
+ * 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.
*/
-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 cc, i;
+ struct icmp * icp;
+ struct monitor_host * p;
+ u_char outpack[MAXPACKETSIZE];
+
+ p = hosts[0];
+ while (p) {
+ if (p->socket != -1) {
struct timeval now;
-
- (void)gettimeofday(&now,(struct timezone *)NULL);
+
+ 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) printf("INFO: Host %s is down. Executing DOWN command.\n", p->name);
- if(!fork())
- {
+ if (now.tv_sec > (p->max_delay + p->ping_interval)) {
+ if ((p->hostup) || keepBanging) {
+ if (isVerbose) printf("INFO: Host %s stopped responding. Executing DOWN command.\n", p->name);
+ p->hostup = false;
+ if (!fork()) {
system(p->downcmd);
- exit(0);
- } else
- {
+ exit(EXIT_SUCCESS);
+ } else {
wait(NULL);
}
}
}
-
- (void)gettimeofday(&now,(struct timezone *)NULL);
+
+ 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;
+
+ 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_id = ident;
+ icp->icmp_id = getpid() & 0xFFFF;
if (isVerbose) printf("INFO: Sending ICMP packet to %s.\n", 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)
- {
+
+ gettimeofday((struct timeval *) &outpack[8], (struct timezone *) NULL);
+
+ cc = DEFAULTDATALEN + 8; /* skips ICMP portion */
+
+ /* compute ICMP checksum */
+ icp->icmp_cksum = in_cksum((unsigned short *) icp, cc);
+
+ 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 */
+
+ signal(SIGALRM, pinger); /* restore handler */
alarm(send_delay);
}
-static void get_response(void)
+static void
+read_icmp_data(struct monitor_host * p)
{
- fd_set rfds;
- int retval;
- monitor_host_t *p;
- int maxd=-1;
-
- while(1)
- {
- p=hosts[0];
- FD_ZERO(&rfds);
- while(p)
- {
- if(p->socket != -1)
- {
- if(p->socket > maxd)
- maxd=p->socket;
- FD_SET(p->socket, &rfds);
- }
- p=p->next;
- }
+ int cc, iphdrlen, delay;
+ socklen_t fromlen;
+ struct sockaddr_in from;
+ struct ip * ip;
+ struct icmp * icmp;
+ struct timeval tv;
+ unsigned char buf[MAXPACKETSIZE];
- 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)
- {
- p=hosts[0];
- while(p)
- {
- if(p->socket!=-1 && FD_ISSET(p->socket, &rfds))
- {
- /* Read data */
- read_icmp_data(p);
- }
- p=p->next;
- }
- } else {
- /* TODO: How to handle this error? */
- }
- }
- }
-}
+ gettimeofday(&tv, (struct timezone *) NULL);
-static void read_icmp_data(monitor_host_t *p)
-{
- 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) 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);
- /* 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 == ident &&
- icmp->icmp_seq == p->socket)
- {
+
+ if (icmp->icmp_type == ICMP_ECHOREPLY && icmp->icmp_id == (getpid() & 0xFFFF) && 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) printf("INFO: Got ICMP reply from %s in %d ms.\n", p->name, delay);
- p->down=0;
- if(!p->up)
- {
- p->up=1;
- if (isVerbose) printf("INFO: Host %s is up. Executing UP command.\n", p->name);
- if(!fork())
- {
+ delay = tv.tv_sec * 1000 + (tv.tv_usec / 1000);
+
+ if (isVerbose) printf("INFO: Got ICMP reply from %s in %d ms.\n", p->name, delay);
+ if (!p->hostup) {
+ if (isVerbose) printf("INFO: Host %s started responding. Executing UP command.\n", p->name);
+ p->hostup = true;
+ if (!fork()) {
system(p->upcmd);
- exit(0);
- } else
- {
+ exit(EXIT_SUCCESS);
+ } else {
wait(NULL);
}
}
}
}
-static void read_hosts(const char *cfg_file_name)
+static void
+get_response(void)
+{
+ fd_set rfds;
+ int retval, maxd = -1;
+ struct monitor_host * p;
+
+ while (1) {
+ p = hosts[0];
+ FD_ZERO(&rfds);
+ while (p) {
+ if (p->socket != -1) {
+ if (p->socket > maxd) maxd=p->socket;
+ FD_SET(p->socket, &rfds);
+ }
+ p = p->next;
+ }
+
+ retval = select(maxd+1, &rfds, NULL, NULL, NULL);
+ if (retval < 0) {
+ /* Intentionally empty. We arrive here when interrupted by a signal. No action should be taken. */
+ } else {
+ if (retval > 0) {
+ p = hosts[0];
+ while (p) {
+ if (p->socket!=-1 && FD_ISSET(p->socket, &rfds)) read_icmp_data(p);
+ p = p->next;
+ }
+ } else {
+ /* TODO: How to handle this error? */
+ }
+ }
+ }
+}
+
+static void
+read_hosts(const char * cfg_file_name)
{
- int i,n=0;
- struct Cfg *cfg;
-
+ int i, n = 0;
+ struct Cfg * cfg;
+
if ((cfg = readcfg(cfg_file_name)) == NULL) {
fprintf(stderr, "ERROR: Failed to read config.\n");
exit(EXIT_FAILURE);
}
-
+
if (cfg->nelements) {
- hosts = malloc(sizeof(monitor_host_t *) * cfg->nelements);
- for (i=0; i<cfg->nelements; i++) {
+ hosts = malloc(sizeof(struct monitor_host *) * cfg->nelements);
+ for (i = 0; i < cfg->nelements; i++) {
if (cfg->dict[i]->nvalues < 4) {
fprintf(stderr, "ERROR: Not enough fields in record %d of cfg file. Got %d.\n", n, cfg->dict[i]->nvalues+1);
exit(EXIT_FAILURE);
fprintf(stderr, "ERROR: Too many fields in record %d of cfg file. Got %d.\n", n, cfg->dict[i]->nvalues+1);
exit(EXIT_FAILURE);
}
-
- hosts[n] = malloc(sizeof(monitor_host_t));
+
+ hosts[n] = malloc(sizeof(struct monitor_host));
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 {
- fprintf(stderr, "ERROR: Illegal value %s in record %n for startup condition.\n", cfg->dict[i]->value[4], n);
- exit(EXIT_FAILURE);
- }
+
+ if (cfg->dict[i]->nvalues == 4) {
+ hosts[n]->hostup = true;
+ } else if (strcmp(cfg->dict[i]->value[4], "up") == 0) {
+ hosts[n]->hostup = true;
+ } else if (strcmp(cfg->dict[i]->value[4], "down") == 0) {
+ hosts[n]->hostup = false;
+ } else if (strcmp(cfg->dict[i]->value[4], "auto") == 0) {
+ /* TODO: Send a ping and set initial state accordingly. */
+ } else {
+ fprintf(stderr, "ERROR: Illegal value %s in record %d for startup condition.\n", cfg->dict[i]->value[4], n);
+ exit(EXIT_FAILURE);
+ }
hosts[n]->sentpackets = 0;
hosts[n]->recvdpackets = 0;
gettimeofday(&(hosts[n]->last_ping_received), (struct timezone *)NULL);
n++;
- }
+ }
}
freecfg(cfg);
}
}
-static int gethostaddr(const char *name)
+static int
+gethostaddr(const char * name)
{
- 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 );
- }
+ 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);
}
-static void init_hosts(void)
+static int
+gcd(int x, int y)
+{
+ int remainder = x % y;
+ if (remainder == 0) return y;
+ return gcd(y, remainder);
+}
+
+static void
+init_hosts(void)
{
- monitor_host_t *p=hosts[0];
- struct protoent *proto;
- int ok=0;
+ struct monitor_host * p = hosts[0];
+ struct protoent * proto;
+ int ok = 0;
if ((proto = getprotobyname("icmp")) == NULL) {
fprintf(stderr, "ERROR: Unknown protocol: icmp.\n");
exit(EXIT_FAILURE);
}
-
- while(p) {
- bzero(&p->dest,sizeof(p->dest));
- p->dest.sin_family=AF_INET;
- if((p->dest.sin_addr.s_addr=gethostaddr(p->name))<=0)
- {
+
+ while (p) {
+ bzero(&p->dest, sizeof(p->dest));
+ p->dest.sin_family = AF_INET;
+ if ((p->dest.sin_addr.s_addr = gethostaddr(p->name)) <= 0) {
fprintf(stderr, "WARN: Can't resolve host. Skipping client %s.\n", p->name);
p->socket=-1;
- } else
- {
- if((p->socket=socket(AF_INET,SOCK_RAW,proto->p_proto))<0)
- {
+ } 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;
- } 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++;
}
}
- p=p->next;
+ p = p->next;
}
- if(!ok)
- {
+ 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)
+int
+main(int argc, char ** argv)
{
- if ((out->tv_usec -= in->tv_usec) < 0) {
- --out->tv_sec;
- out->tv_usec += 1000000;
- }
- out->tv_sec -= in->tv_sec;
-}
+ extern char * optarg;
+ extern int optind;
+ char * cfgfile = NULL;
+ int param;
+
+ while ((param = getopt(argc, argv, "rvf:")) != -1) {
+ switch(param) {
+ case 'v':
+ isVerbose = 1;
+ break;
+ case 'r':
+ keepBanging = 1;
+ break;
+ case 'f':
+ cfgfile=strdup(optarg);
+ break;
+ default:
+ fprintf(stderr,"Usage: icmpmonitor [-v] [-r] [-f cfgfile]\n");
+ exit(EXIT_FAILURE);
+ }
+ }
-void done(int code)
-{
- exit(code);
-}
+ if (!cfgfile) {
+ fprintf(stderr, "ERROR: No config file specified.\n");
+ exit(EXIT_FAILURE);
+ }
-static int gcd(int x, int y)
-{
- int remainder = x % y;
- if (remainder == 0) return y;
- return gcd(y, remainder);
+ read_hosts(cfgfile);
+
+ init_hosts();
+
+ signal(SIGALRM, pinger);
+ alarm(send_delay);
+
+ get_response();
+
+ exit(EXIT_SUCCESS);
}