path: root/web/attachments/121773-check_icmp-bundled.diff

diff -urN ../plugins/plugins/check_icmp.c ./plugins/check_icmp.c
--- ../plugins/plugins/check_icmp.c	2005-02-01 15:31:11.000000000 +0100
+++ ./plugins/check_icmp.c	2005-02-18 15:57:08.000000000 +0100
@@ -1,5 +1,5 @@
 /*
- * $Id: check_icmp.c,v 1.5 2005/02/01 07:33:13 stanleyhopcroft Exp $
+ * $Id: check_icmp.c,v 1.12 2005/01/29 23:23:23 exon Exp $
  *
  * Author: Andreas Ericsson <ae@op5.se>
  *
@@ -14,6 +14,15 @@
  * redundant routes. The only remainders of fping is currently a few
  * function names.
  *
+ * Kudos to;
+ *   Joe Rhett
+ *   Wickus Botha
+ *   Aaron Carr
+ *   Harper Mann
+ *   Phil Costelloe
+ *   Carsten Schmitz
+ * for lending me system resources, testing and feedback
+ *
  */
 
 #include <sys/time.h>
@@ -84,7 +93,7 @@
 	char *msg;                   /* icmp error message, if any */
 	struct sockaddr_in saddr_in; /* the address of this host */
 	struct in_addr error_addr;   /* stores address of error replies */
-	unsigned long long time_waited; /* total time waited, in usecs */
+	unsigned long int time_waited; /* total time waited, in usecs */
 	unsigned int icmp_sent, icmp_recv, icmp_lost; /* counters */
 	unsigned char icmp_type, icmp_code; /* type and code from errors */
 	unsigned short flags;        /* control/status flags */
@@ -137,18 +146,19 @@
 #define IP_HDR_SIZE 20
 #define MAX_PING_DATA (MAX_IP_PKT_SIZE - IP_HDR_SIZE - ICMP_MINLEN)
 #define DEFAULT_PING_DATA_SIZE (MIN_PING_DATA_SIZE + 44)
+#define DEFAULT_TTL 64
 
-/* various target states */
-#define TSTATE_INACTIVE 0x01	/* don't ping this host anymore */
-#define TSTATE_WAITING 0x02		/* unanswered packets on the wire */
-#define TSTATE_ALIVE 0x04       /* target is alive (has answered something) */
-#define TSTATE_UNREACH 0x08
+#define MIN_PKT_INTERVAL   25000 /* min pkt_interval, microsecs */
+#define NOFORCE_WAIT 0
+#define FORCE_WAIT 1
 
 /** prototypes **/
-static void usage(unsigned char, char *);
+static void usage(unsigned char, char *, ...);
 static u_int get_timevar(const char *);
 static u_int get_timevaldiff(struct timeval *, struct timeval *);
-static int wait_for_reply(int, u_int);
+static int reap_replies(int, u_int, int);
+void u_sleep(u_int u_sec);
+static u_int wait_for_reply(int, u_int);
 static int recvfrom_wto(int, char *, unsigned int, struct sockaddr *, u_int *);
 static int send_icmp_ping(int, struct rta_host *);
 static int get_threshold(char *str, threshold *th);
@@ -162,6 +172,7 @@
 
 /** external **/
 extern int optind, opterr, optopt;
+/* extern int h_errno; */
 extern char *optarg;
 extern char **environ;
 
@@ -173,15 +184,15 @@
 static unsigned short icmp_pkt_size, icmp_data_size = DEFAULT_PING_DATA_SIZE;
 static unsigned int icmp_sent = 0, icmp_recv = 0, icmp_lost = 0;
 #define icmp_pkts_en_route (icmp_sent - (icmp_recv + icmp_lost))
-static unsigned short targets_down = 0, targets = 0, packets = 0;
+static unsigned int targets_down = 0, targets = 0, packets = 0;
 #define targets_alive (targets - targets_down)
 static unsigned int retry_interval, pkt_interval, target_interval;
 static int icmp_sock, tcp_sock, udp_sock, status = STATE_OK;
 static pid_t pid;
 static struct timezone tz;
 static struct timeval prog_start;
-static unsigned long long max_completion_time = 0;
-static unsigned char ttl = 0;	/* outgoing ttl */
+static unsigned long int max_completion_time = 0;
+static unsigned char ttl = 64;	/* outgoing ttl */
 static unsigned int warn_down = 1, crit_down = 1; /* host down threshold values */
 float pkt_backoff_factor = 1.5;
 float target_backoff_factor = 1.5;
@@ -210,7 +221,8 @@
 {
 	char *msg = "unreachable";
 
-	if(debug > 1) printf("get_icmp_error_msg(%u, %u)\n", icmp_type, icmp_code);
+	if(debug > 3) printf("get_icmp_error_msg(%u, %u) called\n",
+						 icmp_type, icmp_code);
 	switch(icmp_type) {
 	case ICMP_UNREACH:
 		switch(icmp_code) {
@@ -269,7 +281,7 @@
 	unsigned char *ptr;
 
 	if(p->icmp_type == ICMP_ECHO && p->icmp_id == pid) {
-		/* echo request from us to us (pinging localhost) */
+		if(debug > 2) printf("echo request from us to us (pinging localhost)\n");
 		return 0;
 	}
 
@@ -286,9 +298,13 @@
 	 * TIMXCEED actually sends a proper icmp response we will have passed
 	 * too many hops to have a hope of reaching it later, in which case it
 	 * indicates overconfidence in the network, poor routing or both. */
+	if(debug > 2) printf("random ICMP response type: %u,  code: %u\n",
+						 p->icmp_type, p->icmp_code);
 	if(p->icmp_type != ICMP_UNREACH && p->icmp_type != ICMP_TIMXCEED &&
 	   p->icmp_type != ICMP_SOURCEQUENCH && p->icmp_type != ICMP_PARAMPROB)
 	{
+		if(debug > 1) printf("Unsafe to handle unknown type %u, returning\n",
+							 p->icmp_type);
 		return 0;
 	}
 
@@ -298,7 +314,7 @@
 	if(sent_icmp->icmp_type != ICMP_ECHO || sent_icmp->icmp_id != pid ||
 	   sent_icmp->icmp_seq >= targets)
 	{
-		if(debug) printf("Packet is no response to a packet we sent\n");
+		if(debug) printf("not a response to a packet we sent, or target failed to duplicate request\n");
 		return 0;
 	}
 
@@ -394,12 +410,12 @@
 	}
 	else if(!strcmp(progname, "check_host")) {
 		mode = MODE_HOSTCHECK;
-		pkt_interval = 1000000;
+		pkt_interval = 200000;
 		packets = 5;
 		crit.rta = warn.rta = 1000000;
 		crit.pl = warn.pl = 100;
 	}
-	else if(!strcmp(progname, "check_rta_multi")) {
+	else if(!strcmp(progname, "check_icmp_multi")) {
 		mode = MODE_ALL;
 		target_interval = 0;
 		pkt_interval = 50000;
@@ -408,6 +424,8 @@
 
 	/* parse the arguments */
 	for(i = 1; i < argc; i++) {
+		/* the leading '-' of the optstring makes non-argument options
+		 * return with arg 1, meaning it's */
 		while((arg = getopt(argc, argv, "vhVw:c:n:p:t:H:i:b:I:l:")) != EOF) {
 			switch(arg) {
 			case 'v':
@@ -436,7 +454,8 @@
 				timeout = strtoul(optarg, NULL, 0);
 				if(!timeout) timeout = 10;
 				break;
-			case 'H':
+			case 'H': case 1: /* 1 is default for non-option arguments */
+				/* printf("arg: %ld, optarg: %s\n", arg, optarg); */
 				add_target(optarg);
 				break;
 			case 'l':
@@ -460,11 +479,10 @@
 		add_target(*argv);
 		argv++;
 	}
-	if(!targets) {
-		errno = 0;
-		crash("No hosts to check");
-		exit(3);
-	}
+	if(!targets) usage('h', "No hosts to check");
+
+	if(getuid() && pkt_interval < MIN_PKT_INTERVAL)
+		pkt_interval = MIN_PKT_INTERVAL;
 
 	if(!sockets) {
 		if(icmp_sock == -1) {
@@ -486,10 +504,12 @@
 	if(!ttl) ttl = 64;
 
 	if(icmp_sock) {
+		errno = 0;
 		result = setsockopt(icmp_sock, SOL_IP, IP_TTL, &ttl, sizeof(ttl));
 		if(debug) {
-			if(result == -1) printf("setsockopt failed\n");
-			else printf("ttl set to %u\n", ttl);
+			printf("setsockopt(icmp_sock, SOL_IP, IP_TTL, %u) = %d (%s)\n",
+				   ttl, result, strerror(errno));
+			if(result != -1) printf("outgoing ttl set to %u\n", ttl);
 		}
 	}
 
@@ -505,7 +525,7 @@
 	signal(SIGHUP, finish);
 	signal(SIGTERM, finish);
 	signal(SIGALRM, finish);
-	if(debug) printf("Setting alarm timeout to %u seconds\n", timeout);
+	if(debug > 1) printf("Setting alarm timeout to %u seconds\n", timeout);
 	alarm(timeout);
 
 	/* make sure we don't wait any longer than necessary */
@@ -514,10 +534,9 @@
 		((targets * packets * pkt_interval) + (targets * target_interval)) +
 		(targets * packets * crit.rta) + crit.rta;
 
-	if(debug) {
+	if(debug > 1) {
 		printf("packets: %u, targets: %u\n"
-			   "target_interval: %0.3f, pkt_interval %0.3f\n"
-			   "crit.rta: %0.3f\n"
+			   "target_interval: %0.3f, pkt_interval %0.3f, crit.rta: %0.3f\n"
 			   "max_completion_time: %0.3f\n",
 			   packets, targets,
 			   (float)target_interval / 1000, (float)pkt_interval / 1000,
@@ -527,9 +546,9 @@
 
 	if(debug) {
 		if(max_completion_time > (u_int)timeout * 1000000) {
-			printf("max_completion_time: %llu  timeout: %u\n",
+			printf("max_completion_time: %lu  timeout: %u\n",
 				   max_completion_time, timeout);
-			printf("Timout must be at lest %llu\n",
+			printf("Timout must be at lest %lu\n",
 				   max_completion_time / 1000000 + 1);
 		}
 	}
@@ -579,24 +598,27 @@
 	u_int i, t, result;
 	u_int final_wait, time_passed;
 
-	/* this loop might actually violate the pkt_interval or target_interval
-	 * settings, but only if there aren't any packets on the wire which
-	 * indicates that the target can handle an increased packet rate */
-	for(i = 0; i < packets; i++) {
-		for(t = 0; t < targets; t++) {
+	/* send the packets */
+	for(t = 0; t < targets; t++) {
+		for(i = 0; i < packets; i++) {
+
 			/* don't send useless packets */
-			if(!targets_alive) finish(0);
 			if(table[t]->flags & FLAG_LOST_CAUSE) {
 				if(debug) printf("%s is a lost cause. not sending any more\n",
 								 table[t]->name);
 				continue;
 			}
-			
+
 			/* we're still in the game, so send next packet */
 			(void)send_icmp_ping(icmp_sock, table[t]);
-			result = wait_for_reply(icmp_sock, target_interval);
+
+			/* pause for a while so we don't flood the network */
+			result = reap_replies(icmp_sock, pkt_interval, FORCE_WAIT);
 		}
-		result = wait_for_reply(icmp_sock, pkt_interval * targets);
+
+		/* wait for all incoming packets from all hosts */
+		if(target_interval > pkt_interval)
+			result = reap_replies(icmp_sock, target_interval - pkt_interval, FORCE_WAIT);
 	}
 
 	if(icmp_pkts_en_route && targets_alive) {
@@ -604,7 +626,7 @@
 		final_wait = max_completion_time - time_passed;
 
 		if(debug) {
-			printf("time_passed: %u  final_wait: %u  max_completion_time: %llu\n",
+			printf("time_passed: %u  final_wait: %u  max_completion_time: %lu\n",
 				   time_passed, final_wait, max_completion_time);
 		}
 		if(time_passed > max_completion_time) {
@@ -616,8 +638,61 @@
 		 * haven't yet */
 		if(debug) printf("Waiting for %u micro-seconds (%0.3f msecs)\n",
 						 final_wait, (float)final_wait / 1000);
-		result = wait_for_reply(icmp_sock, final_wait);
+		result = reap_replies(icmp_sock, final_wait, NOFORCE_WAIT);
+	}
+}
+
+/*
+ * select() is posix, so we expect it to be around
+ */
+void
+u_sleep(u_int u_sec)
+{
+	int nfound;
+	struct timeval to;
+	fd_set readset, writeset;
+
+	if(debug > 3) printf("sleeping for %u microseconds\n", u_sec);
+	if(!u_sec) return;
+
+	to.tv_sec = u_sec / 1000000;
+	to.tv_usec = u_sec % 1000000;
+	FD_ZERO(&writeset);
+	FD_ZERO(&readset);
+	nfound = select(0, &readset, &writeset, NULL, &to);
+	if(nfound < 0)
+		crash("select() in u_sleep");
+
+	return;
+}								/* u_sleep() */
+
+static int
+reap_replies(int sock, u_int t, int wait_forced)
+{
+	/* wrap up if all targets are declared dead */
+	if(debug > 3) printf("reap_replies(%d, %u, %d) called\n", sock, t, wait_forced);
+
+	if(!targets_alive ||
+	   get_timevaldiff(&prog_start, NULL) >= max_completion_time)
+	{
+		finish(0);
+	}
+
+	/* listen til timeout while there are packets en route (rhymes!) ;) */
+	while(t && icmp_pkts_en_route) {
+		t = wait_for_reply(sock, t);
+
+		/* the dead won't sing to us */
+		if(!targets_alive) finish(0);
 	}
+
+	if(icmp_recv == (targets_alive * (int)packets)) finish(0);
+
+	if(!t || !wait_forced) return 0;
+
+	u_sleep(t);
+
+	return 0;
 }
 
 /* response structure:
@@ -625,126 +700,98 @@
  * icmp header : 28 bytes
  * icmp echo reply : the rest
  */
-static int
+static u_int
 wait_for_reply(int sock, u_int t)
 {
 	int n, hlen;
 	static char buf[4096];
 	struct sockaddr_in resp_addr;
 	struct ip *ip;
-	struct icmp *icp, *sent_icmp;
+	struct icmp *icp;
 	struct rta_host *host;
 	struct icmp_ping_data *data;
 	struct timeval wait_start, now;
-	u_int tdiff, i, per_pkt_wait;
-
-	/* if we can't listen or don't have anything to listen to, just return */
-	if(!t || !icmp_pkts_en_route) return 0;
+	u_int tdiff, timo = t;
 
 	gettimeofday(&wait_start, &tz);
 
-	i = t;
-	per_pkt_wait = t / icmp_pkts_en_route;
-	while(icmp_pkts_en_route && get_timevaldiff(&wait_start, NULL) < i) {
-		t = per_pkt_wait;
-
-		/* wrap up if all targets are declared dead */
-		if(!targets_alive ||
-		   get_timevaldiff(&prog_start, NULL) >= max_completion_time ||
-		   (mode == MODE_HOSTCHECK && targets_down))
-		{
-			finish(0);
-		}
+	n = recvfrom_wto(sock, buf, sizeof(buf), (struct sockaddr *)&resp_addr, &timo);
+	if(!n) {	/* timeout */
+		if(debug > 2) printf("recvfrom_wto() timed out during a %u usecs wait\n", t);
+		return 0; /* no time left, so return just that */
+	}
 
-		/* reap responses until we hit a timeout */
-		n = recvfrom_wto(sock, buf, sizeof(buf),
-						 (struct sockaddr *)&resp_addr, &t);
-		if(!n) {
-			if(debug > 1) {
-				printf("recvfrom_wto() timed out during a %u usecs wait\n",
-					   per_pkt_wait);
-			}
-			continue;	/* timeout for this one, so keep trying */
-		}
-		if(n < 0) {
-			if(debug) printf("recvfrom_wto() returned errors\n");
-			return n;
-		}
+	gettimeofday(&now, &tz);
+	tdiff = get_timevaldiff(&wait_start, &now);
+	/* make sure we can return time left */
+	if(t > tdiff) t -= tdiff;
+	else t = 0;
 
-		ip = (struct ip *)buf;
-		if(debug > 1) printf("received %u bytes from %s\n",
+	ip = (struct ip *)buf;
+	if(debug > 1) printf("received %u bytes from %s\n",
 						 ntohs(ip->ip_len), inet_ntoa(resp_addr.sin_addr));
 
-/* obsolete. alpha on tru64 provides the necessary defines, but isn't broken */
+/* obsolete, or at least not globally applicable */
 /* #if defined( __alpha__ ) && __STDC__ && !defined( __GLIBC__ ) */
 		/* alpha headers are decidedly broken. Using an ansi compiler,
 		 * they provide ip_vhl instead of ip_hl and ip_v, so we mask
 		 * off the bottom 4 bits */
 /* 		hlen = (ip->ip_vhl & 0x0f) << 2; */
 /* #else */
-		hlen = ip->ip_hl << 2;
+	hlen = ip->ip_hl << 2;
 /* #endif */
 
-		if(n < (hlen + ICMP_MINLEN)) {
-			crash("received packet too short for ICMP (%d bytes, expected %d) from %s\n",
-				  n, hlen + icmp_pkt_size, inet_ntoa(resp_addr.sin_addr));
-		}
-		/* else if(debug) { */
-		/* 	printf("ip header size: %u, packet size: %u (expected %u, %u)\n", */
-		/* 		   hlen, ntohs(ip->ip_len) - hlen, */
-		/* 		   sizeof(struct ip), icmp_pkt_size); */
-		/* } */
-
-		/* check the response */
-		icp = (struct icmp *)(buf + hlen);
-		sent_icmp = (struct icmp *)(buf + hlen + ICMP_MINLEN);
-		/* printf("buf: %p, icp: %p, distance: %u (expected %u)\n", */
-		/* 	   buf, icp, */
-		/* 	   (u_int)icp - (u_int)buf, hlen); */
-		/* printf("buf: %p, sent_icmp: %p, distance: %u (expected %u)\n", */
-		/* 	   buf, sent_icmp, */
-		/* 	   (u_int)sent_icmp - (u_int)buf, hlen + ICMP_MINLEN); */
-
-		if(icp->icmp_id != pid) {
-			handle_random_icmp(icp, &resp_addr);
-			continue;
-		}
-
-		if(icp->icmp_type != ICMP_ECHOREPLY || icp->icmp_seq >= targets) {
-			if(debug > 2) printf("not a proper ICMP_ECHOREPLY\n");
-			handle_random_icmp(icp, &resp_addr);
-			continue;
-		}
-
-		/* this is indeed a valid response */
-		data = (struct icmp_ping_data *)(icp->icmp_data);
-
-		host = table[icp->icmp_seq];
-		gettimeofday(&now, &tz);
-		tdiff = get_timevaldiff(&data->stime, &now);
+	if(n < (hlen + ICMP_MINLEN)) {
+		crash("received packet too short for ICMP (%d bytes, expected %d) from %s\n",
+			  n, hlen + icmp_pkt_size, inet_ntoa(resp_addr.sin_addr));
+	}
+	else if(debug > 2) {
+		printf("ip header size: %u, packet size: %u (expected %u, %u)\n",
+			   hlen, ntohs(ip->ip_len) - hlen,
+			   sizeof(struct ip), (u_int)icmp_pkt_size);
+	}
 
-		host->time_waited += tdiff;
-		host->icmp_recv++;
-		icmp_recv++;
+	/* check the response */
+	icp = (struct icmp *)(buf + hlen);
 
+	if(icp->icmp_id != pid || icp->icmp_type != ICMP_ECHOREPLY || icp->icmp_seq >= targets) {
 		if(debug) {
-			printf("%0.3f ms rtt from %s, outgoing ttl: %u, incoming ttl: %u\n",
-				   (float)tdiff / 1000, inet_ntoa(resp_addr.sin_addr),
-				   ttl, ip->ip_ttl);
-		}
+			printf("inbound packet is:\n");
+			if(icp->icmp_id != pid) printf("\tnot marked by me\n");
+			if(icp->icmp_type != ICMP_ECHOREPLY) printf("\tnot an echo reply\n");
+			if(icp->icmp_seq >= targets) printf("\ttagged with a too high seq number\n");
+		}
+		handle_random_icmp(icp, &resp_addr);
+		return t;
+	}
+	if(debug > 2) puts("inbound packet is a valid ICMP_ECHOREPLY to a packet we sent");
+
+	/* this is indeed a valid response */
+	data = (struct icmp_ping_data *)(icp->icmp_data);
+	host = table[icp->icmp_seq];
+	tdiff = get_timevaldiff(&data->stime, &now);
+
+	host->time_waited += tdiff;
+	host->icmp_recv++;
+	icmp_recv++;
 
-		/* if we're in hostcheck mode, exit with limited printouts */
-		if(mode == MODE_HOSTCHECK) {
-			printf("OK - %s responds to ICMP. Packet %u, rta %0.3fms|"
-				   "pkt=%u;;0;%u rta=%0.3f;%0.3f;%0.3f;;\n",
-				   host->name, icmp_recv, (float)tdiff / 1000,
-				   icmp_recv, packets, (float)tdiff / 1000,
-				   (float)warn.rta / 1000, (float)crit.rta / 1000);
-			exit(STATE_OK);
-		}
+	if(debug) {
+		printf("%0.3f ms rtt from %s, outgoing ttl: %u, incoming ttl: %u\n",
+			   (float)tdiff / 1000, inet_ntoa(resp_addr.sin_addr),
+			   ttl, ip->ip_ttl);
+	}
+
+	/* if we're in hostcheck mode, exit with limited printouts */
+	if(mode == MODE_HOSTCHECK) {
+		printf("OK - %s responds to ICMP. Packet %u, rta %0.3fms|"
+			   "pkt=%u;;0;%u rta=%0.3f;%0.3f;%0.3f;;\n",
+			   host->name, icmp_recv, (float)tdiff / 1000,
+			   icmp_recv, packets, (float)tdiff / 1000,
+			   (float)warn.rta / 1000, (float)crit.rta / 1000);
+		exit(STATE_OK);
 	}
 
-	return 0;
+	return t;
 }
 
 /* the ping functions */
@@ -776,8 +823,6 @@
 	}
 	memset(buf, 0, icmp_pkt_size + sizeof(struct ip));
 
-	if((gettimeofday(&tv, &tz)) == -1) return -1;
-
 	icp = (struct icmp *)buf;
 	icp->icmp_type = ICMP_ECHO;
 	icp->icmp_code = 0;
@@ -785,7 +830,9 @@
 	icp->icmp_id = pid;
 	icp->icmp_seq = host->id;
 	data = (struct icmp_ping_data *)icp->icmp_data;
-	data->ping_id = 10; /* host->icmp.icmp_sent; */
+	data->ping_id = host->icmp_sent;
+
+	if((gettimeofday(&tv, &tz)) == -1) return -1;
 	memcpy(&data->stime, &tv, sizeof(struct timeval));
 	icp->icmp_cksum = icmp_checksum((u_short *)icp, icmp_pkt_size);
 
@@ -798,6 +845,7 @@
 		return -1;
 	}
 
+	/* increment the counters */
 	icmp_sent++;
 	host->icmp_sent++;
 
@@ -809,7 +857,7 @@
 			 u_int *timo)
 {
 	u_int slen;
-	int n;
+	int n, result;
 	struct timeval to, then, now;
 	fd_set rd, wr;
 
@@ -835,7 +883,10 @@
 
 	slen = sizeof(struct sockaddr);
 
-	return recvfrom(sock, buf, len, 0, saddr, &slen);
+	result = recvfrom(sock, buf, len, 0, saddr, &slen);
+	if(result < 0) crash("recvfrom in recvfrom_wto");
+
+	return result;
 }
 
 static void
@@ -849,7 +900,7 @@
 	{"OK", "WARNING", "CRITICAL", "UNKNOWN", "DEPENDENT"};
 
 	alarm(0);
-	if(debug > 1) printf("finish(%d) called\n", sig);
+	if(debug > 2) printf("finish(%d) called\n", sig);
 
 	if(icmp_sock != -1) close(icmp_sock);
 	if(udp_sock != -1) close(udp_sock);
@@ -1016,23 +1067,20 @@
 	struct hostent *he;
 	struct in_addr *in, ip;
 
-	/* don't resolve if we don't have to */
-	if((ip.s_addr = inet_addr(arg)) != INADDR_NONE) {
-		/* don't add all ip's if we were given a specific one */
-		return add_target_ip(arg, &ip);
-		/* he = gethostbyaddr((char *)in, sizeof(struct in_addr), AF_INET); */
-		/* if(!he) return add_target_ip(arg, in); */
-	}
-	else {
-		errno = 0;
+	/* don't resolve if we don't have to, don't add all ip's if we were
+	 * given a specific one, even if we're in hostcheck mode */
+	if(inet_aton(arg, &ip)) return add_target_ip(arg, &ip);
+
+	/* not an IP, so resolve */
+	errno = 0;
+	he = gethostbyname(arg);
+	if(!he && h_errno == TRY_AGAIN) {
+		u_sleep(500000);
 		he = gethostbyname(arg);
-		if(!he) {
-			errno = 0;
-			crash("Failed to resolve %s", arg);
-			return -1;
-		}
 	}
 
+	if(!he) usage(0, "Failed to resolve %s: %s", arg, hstrerror(h_errno));
+
 	/* possibly add all the IP's as targets */
 	for(i = 0; he->h_addr_list[i]; i++) {
 		in = (struct in_addr *)he->h_addr_list[i];
@@ -1040,7 +1088,7 @@
 
 		/* this is silly, but it works */
 		if(mode == MODE_HOSTCHECK || mode == MODE_ALL) {
-			printf("mode: %d\n", mode);
+			if(debug) printf("mode: %d\n", mode);
 			continue;
 		}
 		break;
@@ -1048,6 +1096,7 @@
 
 	return 0;
 }
+
 /*
  * u = micro
  * m = milli
@@ -1073,12 +1122,12 @@
 	if(len >= 2 && !isdigit((int)str[len - 2])) p = str[len - 2];
 	if(p && u == 's') u = p;
 	else if(!p) p = u;
-	if(debug > 2) printf("evaluating %s, u: %c, p: %c\n", str, u, p);
+	if(debug > 3) printf("evaluating %s, u: %c, p: %c\n", str, u, p);
 
 	if(u == 'u') factor = 1;            /* microseconds */
 	else if(u == 'm') factor = 1000;	/* milliseconds */
 	else if(u == 's') factor = 1000000;	/* seconds */
-	if(debug > 2) printf("factor is %u\n", factor);
+	if(debug > 3) printf("factor is %u\n", factor);
 
 	i = strtoul(str, &ptr, 0);
 	if(!ptr || *ptr != '.' || strlen(ptr) < 2 || factor == 1)
@@ -1149,51 +1198,58 @@
 
 /* make core plugin developers happy (silly, really) */
 static void
-usage(unsigned char arg, char *msg)
+usage(unsigned char arg, char *fmt, ...)
 {
-	if(msg) printf("%s: %s\n", progname, msg);
+	if(fmt) {
+		va_list ap;
+
+		printf("%s: ", progname);
+
+		va_start(ap, fmt);
+		vprintf(fmt, ap);
+		va_end(ap);
+		puts("\n");
+	}
 
 	if(arg == 'V') {
-		printf("$Id: check_icmp.c,v 1.5 2005/02/01 07:33:13 stanleyhopcroft Exp $\n");
+		printf("$Id: check_icmp.c,v 1.12 2005/01/29 23:23:23 exon Exp $\n");
 		exit(STATE_UNKNOWN);
 	}
 
 	printf("Usage: %s [options] [-H] host1 host2 hostn\n\n", progname);
 
-	if(arg != 'h') exit(3);
+	if(arg != 'h') {
+		printf("%s -h  for details\n", progname);
+		exit(3);
+	}
 
 	printf("Where options are any combination of:\n"
-		   " * -H | --host        specify a target\n"
-		   " * -w | --warn        warning threshold (currently %0.3fms,%u%%)\n"
-		   " * -c | --crit        critical threshold (currently %0.3fms,%u%%)\n"
-		   " * -n | --packets     number of packets to send (currently %u)\n"
-		   " * -i | --interval    max packet interval (currently %0.3fms)\n"
-		   " * -I | --hostint     max target interval (currently %0.3fms)\n"
-		   " * -l | --ttl         TTL on outgoing packets (currently %u)\n"
-		   " * -t | --timeout     timeout value (seconds, currently  %u)\n"
-		   " * -b | --bytes       icmp packet size (currenly ignored)\n"
-		   "   -v | --verbose     verbosity++\n"
-		   "   -h | --help        this cruft\n",
+		   " * -H | --host      specify a target\n"
+		   " * -w | --warn      warning threshold (currently %0.3fms,%u%%)\n"
+		   " * -c | --crit      critical threshold (currently %0.3fms,%u%%)\n"
+		   " * -n | --packets   number of packets to send (currently %u)\n"
+		   " * -i | --interval  max packet interval (currently %0.3fms)\n"
+		   " * -I | --hostint   max target interval (currently %0.3fms)\n",
 		   (float)warn.rta / 1000, warn.pl, (float)crit.rta / 1000, crit.pl,
 		   packets,
-		   (float)pkt_interval / 1000, (float)target_interval / 1000,
+		   (float)pkt_interval / 1000, (float)target_interval / 1000);
+
+	printf(" * -l | --ttl       outgoing TTL (currently %u, not supported on all platforms)\n"
+		   " * -t | --timeout   timeout value (seconds, currently  %u)\n"
+		   " * -b | --bytes     icmp packet size (currenly ignored)\n"
+		   "   -v | --verbose   verbosity++ (4 is sort of max)\n"
+		   "   -h | --help      this cruft\n",
 		   ttl, timeout);
 
-	puts("\nThe -H switch is optional. Naming a host (or several) to check is not.\n\n"
-		 "Threshold format for -w and -c is 200.25,60% for 200.25 msec RTA and 60%\n"
-		 "packet loss.  The default values should work well for most users.\n"
+	puts("\nThreshold format for -w and -c is 200.25,60% for 200.25 msec RTA and 60%\n"
+		 "packet loss.  All threshold values match inclusively.\n"
 		 "You can specify different RTA factors using the standardized abbreviations\n"
-		 "us (microseconds), ms (milliseconds, default) or just plain s for seconds.\n\n"
-		 "Threshold format for -d is warn,crit.  12,14 means WARNING if >= 12 hops\n"
-		 "are spent and CRITICAL if >= 14 hops are spent.\n"
-		 "NOTE: Some systems decrease TTL when forming ICMP_ECHOREPLY, others do not.\n\n"
-		 "The -v switch can be specified several times for increased verbosity.\n\n"
-		 "Long options are currently unsupported.\n\n"
-		 "Options marked with * require an argument\n");
-
-	puts("The latest version of this plugin can be found at http://oss.op5.se/nagios\n"
-		 "or https://devel.op5.se/oss until the day it is included in the official\n"
-		 "plugin distribution.\n");
+		 "us (microseconds), ms (milliseconds, default) or just plain s for seconds.\n");
+	puts("Long options are currently unsupported.\n");
+	puts("Options marked with * require an argument\n");
+	puts("If this program is invoked as check_host (with a symlink, preferrably), it will exit with status\n"
+		 "OK upon the first properly received ICMP_ECHOREPLY, making it ideal\n"
+		 "for hostchecks (less network load and much, much faster on OK)\n");
 
 	exit(3);
 }