Merge changes from branches/dermoth_ntp_rework (check_ntp_peer/check_ntp_time)

 NEWS                     |   13 
 plugins/Makefile.am      |    8 
 plugins/check_ntp_peer.c |  628 ++++++++++++++++-------------------------------
 plugins/check_ntp_time.c |  323 ++----------------------
 plugins/t/check_ntp.t    |   92 +++++-



git-svn-id: https://nagiosplug.svn.sourceforge.net/svnroot/nagiosplug/nagiosplug/trunk@1846 f882894a-f735-0410-b71e-b25c423dba1c

1 files changed, 216 insertions, 412 deletions

diff --git a/plugins/check_ntp_peer.c b/plugins/check_ntp_peer.c
index 164d5190..1c4702c8 100644
--- a/plugins/check_ntp_peer.c
+++ b/plugins/check_ntp_peer.c
@@ -1,6 +1,6 @@
 /******************************************************************************
 *
-* Nagios check_ntp plugin
+* Nagios check_ntp_peer plugin
 *
 * License: GPL
 * Copyright (c) 2006 sean finney <seanius@seanius.net>
@@ -10,11 +10,16 @@
 *
 * Description:
 *
-* This file contains the check_ntp plugin
+* This file contains the check_ntp_peer plugin
 *
-*  This plugin to check ntp servers independant of any commandline
+*  This plugin checks an NTP server independent of any commandline
 *  programs or external libraries.
 *
+*  Use this plugin to check the health of an NTP server. It supports
+*  checking the offset with the sync peer, the jitter and stratum. This
+*  plugin will not check the clock offset between the local host and NTP
+*  server; please use check_ntp_time for that purpose.
+*
 *
 * License Information:
 *
@@ -36,7 +41,7 @@
  
 *****************************************************************************/
 
-const char *progname = "check_ntp";
+const char *progname = "check_ntp_peer";
 const char *revision = "$Revision$";
 const char *copyright = "2007";
 const char *email = "nagiosplug-devel@lists.sourceforge.net";
@@ -47,51 +52,28 @@ const char *email = "nagiosplug-devel@lists.sourceforge.net";
 
 static char *server_address=NULL;
 static int verbose=0;
+static int quiet=0;
 static short do_offset=0;
 static char *owarn="60";
 static char *ocrit="120";
+static short do_stratum=0;
+static char *swarn="-1:16";
+static char *scrit="-1:16";
 static short do_jitter=0;
-static char *jwarn="5000";
-static char *jcrit="10000";
+static char *jwarn="-1:5000";
+static char *jcrit="-1:10000";
+static int syncsource_found=0;
 
 int process_arguments (int, char **);
 thresholds *offset_thresholds = NULL;
 thresholds *jitter_thresholds = NULL;
+thresholds *stratum_thresholds = NULL;
 void print_help (void);
 void print_usage (void);
 
-/* number of times to perform each request to get a good average. */
-#define AVG_NUM 4
-
 /* max size of control message data */
 #define MAX_CM_SIZE 468
 
-/* this structure holds everything in an ntp request/response as per rfc1305 */
-typedef struct {
-	uint8_t flags;       /* byte with leapindicator,vers,mode. see macros */
-	uint8_t stratum;     /* clock stratum */
-	int8_t poll;         /* polling interval */
-	int8_t precision;    /* precision of the local clock */
-	int32_t rtdelay;     /* total rt delay, as a fixed point num. see macros */
-	uint32_t rtdisp;     /* like above, but for max err to primary src */
-	uint32_t refid;      /* ref clock identifier */
-	uint64_t refts;      /* reference timestamp.  local time local clock */
-	uint64_t origts;     /* time at which request departed client */
-	uint64_t rxts;       /* time at which request arrived at server */
-	uint64_t txts;       /* time at which request departed server */
-} ntp_message;
-
-/* this structure holds data about results from querying offset from a peer */
-typedef struct {
-	time_t waiting;         /* ts set when we started waiting for a response */ 
-	int num_responses;      /* number of successfully recieved responses */
-	uint8_t stratum;        /* copied verbatim from the ntp_message */
-	double rtdelay;         /* converted from the ntp_message */
-	double rtdisp;          /* converted from the ntp_message */
-	double offset[AVG_NUM]; /* offsets from each response */
-	uint8_t flags;       /* byte with leapindicator,vers,mode. see macros */
-} ntp_server_results;
-
 /* this structure holds everything in an ntp control message as per rfc1305 */
 typedef struct {
 	uint8_t flags;       /* byte with leapindicator,vers,mode. see macros */
@@ -147,57 +129,6 @@ typedef struct {
 #define PEER_INCLUDED 0x04
 #define PEER_SYNCSOURCE 0x06
 
-/**
- ** a note about the 32-bit "fixed point" numbers:
- **
- they are divided into halves, each being a 16-bit int in network byte order:
- - the first 16 bits are an int on the left side of a decimal point.
- - the second 16 bits represent a fraction n/(2^16)
- likewise for the 64-bit "fixed point" numbers with everything doubled :) 
- **/
-
-/* macros to access the left/right 16 bits of a 32-bit ntp "fixed point"
-   number.  note that these can be used as lvalues too */
-#define L16(x) (((uint16_t*)&x)[0])
-#define R16(x) (((uint16_t*)&x)[1])
-/* macros to access the left/right 32 bits of a 64-bit ntp "fixed point"
-   number.  these too can be used as lvalues */
-#define L32(x) (((uint32_t*)&x)[0])
-#define R32(x) (((uint32_t*)&x)[1])
-
-/* ntp wants seconds since 1/1/00, epoch is 1/1/70.  this is the difference */
-#define EPOCHDIFF 0x83aa7e80UL
-
-/* extract a 32-bit ntp fixed point number into a double */
-#define NTP32asDOUBLE(x) (ntohs(L16(x)) + (double)ntohs(R16(x))/65536.0)
-
-/* likewise for a 64-bit ntp fp number */
-#define NTP64asDOUBLE(n) (double)(((uint64_t)n)?\
-                         (ntohl(L32(n))-EPOCHDIFF) + \
-                         (.00000001*(0.5+(double)(ntohl(R32(n))/42.94967296))):\
-                         0)
-
-/* convert a struct timeval to a double */
-#define TVasDOUBLE(x) (double)(x.tv_sec+(0.000001*x.tv_usec))
-
-/* convert an ntp 64-bit fp number to a struct timeval */
-#define NTP64toTV(n,t) \
-	do{ if(!n) t.tv_sec = t.tv_usec = 0; \
-	    else { \
-			t.tv_sec=ntohl(L32(n))-EPOCHDIFF; \
-			t.tv_usec=(int)(0.5+(double)(ntohl(R32(n))/4294.967296)); \
-		} \
-	}while(0)
-
-/* convert a struct timeval to an ntp 64-bit fp number */
-#define TVtoNTP64(t,n) \
-	do{ if(!t.tv_usec && !t.tv_sec) n=0x0UL; \
-		else { \
-			L32(n)=htonl(t.tv_sec + EPOCHDIFF); \
-			R32(n)=htonl((uint64_t)((4294.967296*t.tv_usec)+.5)); \
-		} \
-	} while(0)
-
 /* NTP control message header is 12 bytes, plus any data in the data
  * field, plus null padding to the nearest 32-bit boundary per rfc.
  */
@@ -210,42 +141,6 @@ typedef struct {
 		printf("%u.%u.%u.%u", (x>>24)&0xff, (x>>16)&0xff, (x>>8)&0xff, x&0xff);\
 	}while(0);
 
-/* calculate the offset of the local clock */
-static inline double calc_offset(const ntp_message *m, const struct timeval *t){
-	double client_tx, peer_rx, peer_tx, client_rx;
-	client_tx = NTP64asDOUBLE(m->origts);
-	peer_rx = NTP64asDOUBLE(m->rxts);
-	peer_tx = NTP64asDOUBLE(m->txts);
-	client_rx=TVasDOUBLE((*t));
-	return (.5*((peer_tx-client_rx)+(peer_rx-client_tx)));
-}
-
-/* print out a ntp packet in human readable/debuggable format */
-void print_ntp_message(const ntp_message *p){
-	struct timeval ref, orig, rx, tx;
-
-	NTP64toTV(p->refts,ref);
-	NTP64toTV(p->origts,orig);
-	NTP64toTV(p->rxts,rx);
-	NTP64toTV(p->txts,tx);
-
-	printf("packet contents:\n");
-	printf("\tflags: 0x%.2x\n", p->flags);
-	printf("\t  li=%d (0x%.2x)\n", LI(p->flags), p->flags&LI_MASK);
-	printf("\t  vn=%d (0x%.2x)\n", VN(p->flags), p->flags&VN_MASK);
-	printf("\t  mode=%d (0x%.2x)\n", MODE(p->flags), p->flags&MODE_MASK);
-	printf("\tstratum = %d\n", p->stratum);
-	printf("\tpoll = %g\n", pow(2, p->poll));
-	printf("\tprecision = %g\n", pow(2, p->precision));
-	printf("\trtdelay = %-.16g\n", NTP32asDOUBLE(p->rtdelay));
-	printf("\trtdisp = %-.16g\n", NTP32asDOUBLE(p->rtdisp));
-	printf("\trefid = %x\n", p->refid);
-	printf("\trefts = %-.16g\n", NTP64asDOUBLE(p->refts));
-	printf("\torigts = %-.16g\n", NTP64asDOUBLE(p->origts));
-	printf("\trxts = %-.16g\n", NTP64asDOUBLE(p->rxts));
-	printf("\ttxts = %-.16g\n", NTP64asDOUBLE(p->txts));
-}
-
 void print_ntp_control_message(const ntp_control_message *p){
 	int i=0, numpeers=0;
 	const ntp_assoc_status_pair *peer=NULL;
@@ -282,222 +177,25 @@ void print_ntp_control_message(const ntp_control_message *p){
 	}
 }
 
-void setup_request(ntp_message *p){
-	struct timeval t;
-
-	memset(p, 0, sizeof(ntp_message));
-	LI_SET(p->flags, LI_ALARM);
-	VN_SET(p->flags, 4);
-	MODE_SET(p->flags, MODE_CLIENT);
-	p->poll=4;
-	p->precision=(int8_t)0xfa;
-	L16(p->rtdelay)=htons(1);
-	L16(p->rtdisp)=htons(1);
-
-	gettimeofday(&t, NULL);
-	TVtoNTP64(t,p->txts);
-}
-
-/* select the "best" server from a list of servers, and return its index.
- * this is done by filtering servers based on stratum, dispersion, and
- * finally round-trip delay. */
-int best_offset_server(const ntp_server_results *slist, int nservers){
-	int i=0, j=0, cserver=0, candidates[5], csize=0;
-
-	/* for each server */
-	for(cserver=0; cserver<nservers; cserver++){
-		/* sort out servers with error flags */
-		if ( LI(slist[cserver].flags) != LI_NOWARNING ){
-			if (verbose) printf("discarding peer id %d: flags=%d\n", cserver, LI(slist[cserver].flags));
-			break;
-		}
-
-		/* compare it to each of the servers already in the candidate list */
-		for(i=0; i<csize; i++){
-			/* does it have an equal or better stratum? */
-			if(slist[cserver].stratum <= slist[i].stratum){
-				/* does it have an equal or better dispersion? */
-				if(slist[cserver].rtdisp <= slist[i].rtdisp){
-					/* does it have a better rtdelay? */
-					if(slist[cserver].rtdelay < slist[i].rtdelay){
-						break;
-					}
-				}
-			}
-		}
-
-		/* if we haven't reached the current list's end, move everyone
-		 * over one to the right, and insert the new candidate */
-		if(i<csize){
-			for(j=5; j>i; j--){
-				candidates[j]=candidates[j-1];
-			}
-		}
-		/* regardless, if they should be on the list... */
-		if(i<5) {
-			candidates[i]=cserver;
-			if(csize<5) csize++;
-		/* otherwise discard the server */
-		} else {
-			DBG(printf("discarding peer id %d\n", cserver));
-		}
-	}
-
-	if(csize>0) {
-		DBG(printf("best server selected: peer %d\n", candidates[0]));
-		return candidates[0];
-	} else {
-		DBG(printf("no peers meeting synchronization criteria :(\n"));
-		return -1;
-	}
-}
-
-/* do everything we need to get the total average offset
- * - we use a certain amount of parallelization with poll() to ensure
- *   we don't waste time sitting around waiting for single packets. 
- * - we also "manually" handle resolving host names and connecting, because
- *   we have to do it in a way that our lazy macros don't handle currently :( */
-double offset_request(const char *host, int *status){
-	int i=0, j=0, ga_result=0, num_hosts=0, *socklist=NULL, respnum=0;
-	int servers_completed=0, one_written=0, one_read=0, servers_readable=0, best_index=-1;
-	time_t now_time=0, start_ts=0;
-	ntp_message *req=NULL;
-	double avg_offset=0.;
-	struct timeval recv_time;
-	struct addrinfo *ai=NULL, *ai_tmp=NULL, hints;
-	struct pollfd *ufds=NULL;
-	ntp_server_results *servers=NULL;
-
-	/* setup hints to only return results from getaddrinfo that we'd like */
-	memset(&hints, 0, sizeof(struct addrinfo));
-	hints.ai_family = address_family;
-	hints.ai_protocol = IPPROTO_UDP;
-	hints.ai_socktype = SOCK_DGRAM;
-
-	/* fill in ai with the list of hosts resolved by the host name */
-	ga_result = getaddrinfo(host, "123", &hints, &ai);
-	if(ga_result!=0){
-		die(STATE_UNKNOWN, "error getting address for %s: %s\n",
-		    host, gai_strerror(ga_result));
-	}
-
-	/* count the number of returned hosts, and allocate stuff accordingly */
-	for(ai_tmp=ai; ai_tmp!=NULL; ai_tmp=ai_tmp->ai_next){ num_hosts++; }
-	req=(ntp_message*)malloc(sizeof(ntp_message)*num_hosts);
-	if(req==NULL) die(STATE_UNKNOWN, "can not allocate ntp message array");
-	socklist=(int*)malloc(sizeof(int)*num_hosts);
-	if(socklist==NULL) die(STATE_UNKNOWN, "can not allocate socket array");
-	ufds=(struct pollfd*)malloc(sizeof(struct pollfd)*num_hosts);
-	if(ufds==NULL) die(STATE_UNKNOWN, "can not allocate socket array");
-	servers=(ntp_server_results*)malloc(sizeof(ntp_server_results)*num_hosts);
-	if(servers==NULL) die(STATE_UNKNOWN, "can not allocate server array");
-	memset(servers, 0, sizeof(ntp_server_results)*num_hosts);
-
-	/* setup each socket for writing, and the corresponding struct pollfd */
-	ai_tmp=ai;
-	for(i=0;ai_tmp;i++){
-		socklist[i]=socket(ai_tmp->ai_family, SOCK_DGRAM, IPPROTO_UDP);
-		if(socklist[i] == -1) {
-			perror(NULL);
-			die(STATE_UNKNOWN, "can not create new socket");
-		}
-		if(connect(socklist[i], ai_tmp->ai_addr, ai_tmp->ai_addrlen)){
-			die(STATE_UNKNOWN, "can't create socket connection");
-		} else {
-			ufds[i].fd=socklist[i];
-			ufds[i].events=POLLIN;
-			ufds[i].revents=0;
-		}
-		ai_tmp = ai_tmp->ai_next;
-	}
-
-	/* now do AVG_NUM checks to each host.  we stop before timeout/2 seconds
-	 * have passed in order to ensure post-processing and jitter time. */
-	now_time=start_ts=time(NULL);
-	while(servers_completed<num_hosts && now_time-start_ts <= socket_timeout/2){
-		/* loop through each server and find each one which hasn't
-		 * been touched in the past second or so and is still lacking
-		 * some responses.  for each of these servers, send a new request,
-		 * and update the "waiting" timestamp with the current time. */
-		one_written=0;
-		now_time=time(NULL);
-
-		for(i=0; i<num_hosts; i++){
-			if(servers[i].waiting<now_time && servers[i].num_responses<AVG_NUM){
-				if(verbose && servers[i].waiting != 0) printf("re-");
-				if(verbose) printf("sending request to peer %d\n", i);
-				setup_request(&req[i]);
-				write(socklist[i], &req[i], sizeof(ntp_message));
-				servers[i].waiting=now_time;
-				one_written=1;
-				break;
-			}
-		}
-
-		/* quickly poll for any sockets with pending data */
-		servers_readable=poll(ufds, num_hosts, 100);
-		if(servers_readable==-1){
-			perror("polling ntp sockets");
-			die(STATE_UNKNOWN, "communication errors");
-		}
-
-		/* read from any sockets with pending data */
-		for(i=0; servers_readable && i<num_hosts; i++){
-			if(ufds[i].revents&POLLIN && servers[i].num_responses < AVG_NUM){
-				if(verbose) {
-					printf("response from peer %d: ", i);
-				}
+char *extract_value(const char *varlist, const char *name){
+	char *tmpvarlist=NULL, *tmpkey=NULL, *value=NULL;
+	int last=0;
 
-				read(ufds[i].fd, &req[i], sizeof(ntp_message));
-				gettimeofday(&recv_time, NULL);
-				DBG(print_ntp_message(&req[i]));
-				respnum=servers[i].num_responses++;
-				servers[i].offset[respnum]=calc_offset(&req[i], &recv_time);
-				if(verbose) {
-					printf("offset %.10g\n", servers[i].offset[respnum]);
-				}
-				servers[i].stratum=req[i].stratum;
-				servers[i].rtdisp=NTP32asDOUBLE(req[i].rtdisp);
-				servers[i].rtdelay=NTP32asDOUBLE(req[i].rtdelay);
-				servers[i].waiting=0;
-				servers[i].flags=req[i].flags;
-				servers_readable--;
-				one_read = 1;
-				if(servers[i].num_responses==AVG_NUM) servers_completed++;
-			}
-		}
-		/* lather, rinse, repeat. */
-	}
+	/* The following code require a non-empty varlist */
+	if(strlen(varlist) == 0)
+		return NULL;
 
-	if (one_read == 0) {
-		die(STATE_CRITICAL, "NTP CRITICAL: No response from NTP server\n");
-	}
+	tmpvarlist = strdup(varlist);
+	tmpkey = strtok(tmpvarlist, "=");
 
-	/* now, pick the best server from the list */
-	best_index=best_offset_server(servers, num_hosts);
-	if(best_index < 0){
-		*status=STATE_UNKNOWN;
-	} else {
-		/* finally, calculate the average offset */
-		for(i=0; i<servers[best_index].num_responses;i++){
-			avg_offset+=servers[best_index].offset[j];
+	do {
+		if(strstr(tmpkey, name) != NULL) {
+		value = strtok(NULL, ",");
+			last = 1;
 		}
-		avg_offset/=servers[best_index].num_responses;
-	}
+	} while (last == 0 && (tmpkey = strtok(NULL, "=")));
 
-	/* cleanup */
-	/* FIXME: Not closing the socket to avoid re-use of the local port
-	 * which can cause old NTP packets to be read instead of NTP control
-	 * pactets in jitter_request(). THERE MUST BE ANOTHER WAY...
-	 * for(j=0; j<num_hosts; j++){ close(socklist[j]); } */
-	free(socklist);
-	free(ufds);
-	free(servers);
-	free(req);
-	freeaddrinfo(ai);
-
-	if(verbose) printf("overall average offset: %.10g\n", avg_offset);
-	return avg_offset;
+	return value;
 }
 
 void
@@ -511,20 +209,36 @@ setup_control_request(ntp_control_message *p, uint8_t opcode, uint16_t seq){
 	/* Remaining fields are zero for requests */
 }
 
-/* XXX handle responses with the error bit set */
-double jitter_request(const char *host, int *status){
-	int conn=-1, i, npeers=0, num_candidates=0, syncsource_found=0;
-	int run=0, min_peer_sel=PEER_INCLUDED, num_selected=0, num_valid=0;
+/* This function does all the actual work; roughly here's what it does
+ * beside setting the offest, jitter and stratum passed as argument:
+ *  - offset can be negative, so if it cannot get the offset, offset_result
+ *    is set to UNKNOWN, otherwise OK.
+ *  - jitter and stratum are set to -1 if they cannot be retrieved so any
+ *    positive value means a success retrieving the value.
+ *  - status is set to WARNING if there's no sync.peer (otherwise OK) and is
+ *    the return value of the function.
+ *  status is pretty much useless as syncsource_found is a global variable
+ *  used later in main to check is the server was synchronized. It works
+ *  so I left it alone */
+int ntp_request(const char *host, double *offset, int *offset_result, double *jitter, int *stratum){
+	int conn=-1, i, npeers=0, num_candidates=0;
+	double tmp_offset = 0;
+	int min_peer_sel=PEER_INCLUDED;
 	int peers_size=0, peer_offset=0;
+	int status;
 	ntp_assoc_status_pair *peers=NULL;
 	ntp_control_message req;
-	const char *getvar = "jitter";
-	double rval = 0.0, jitter = -1.0;
-	char *startofvalue=NULL, *nptr=NULL;
+	const char *getvar = "stratum,offset,jitter";
+	char *data, *value, *nptr;
 	void *tmp;
 
+	status = STATE_OK;
+	*offset_result = STATE_UNKNOWN;
+	*jitter = *stratum = -1;
+
 	/* Long-winded explanation:
-	 * Getting the jitter requires a number of steps:
+	 * Getting the sync peer offset, jitter and stratum requires a number of
+	 * steps:
 	 * 1) Send a READSTAT request.
 	 * 2) Interpret the READSTAT reply
 	 *  a) The data section contains a list of peer identifiers (16 bits)
@@ -535,7 +249,8 @@ double jitter_request(const char *host, int *status){
 	 *     set a minimum of warning.
 	 * 3) Send a READVAR request for information on each peer identified
 	 *    in 2b greater than the minimum selection value.
-	 * 4) Extract the jitter value from the data[] (it's ASCII)
+	 * 4) Extract the offset, jitter and stratum value from the data[]
+	 *    (it's ASCII)
 	 */
 	my_udp_connect(server_address, 123, &conn);
 
@@ -564,7 +279,7 @@ double jitter_request(const char *host, int *status){
 	} while(req.op&REM_MORE);
 
 	/* first, let's find out if we have a sync source, or if there are
-	 * at least some candidates.  in the case of the latter we'll issue
+	 * at least some candidates. In the latter case we'll issue
 	 * a warning but go ahead with the check on them. */
 	for (i = 0; i < npeers; i++){
 		if (PEER_SEL(peers[i].status) >= PEER_INCLUDED){
@@ -578,21 +293,22 @@ double jitter_request(const char *host, int *status){
 	if(verbose) printf("%d candiate peers available\n", num_candidates);
 	if(verbose && syncsource_found) printf("synchronization source found\n");
 	if(! syncsource_found){
-		*status = STATE_UNKNOWN;
+		status = STATE_WARNING;
 		if(verbose) printf("warning: no synchronization source found\n");
 	}
 
 
-	for (run=0; run<AVG_NUM; run++){
-		if(verbose) printf("jitter run %d of %d\n", run+1, AVG_NUM);
-		for (i = 0; i < npeers; i++){
-			/* Only query this server if it is the current sync source */
-			if (PEER_SEL(peers[i].status) >= min_peer_sel){
-				num_selected++;
+	for (i = 0; i < npeers; i++){
+		/* Only query this server if it is the current sync source */
+		/* If there's no sync.peer, query all candidates and use the best one */
+		if (PEER_SEL(peers[i].status) >= min_peer_sel){
+			if(verbose) printf("Getting offset, jitter and stratum for peer %.2x\n", ntohs(peers[i].assoc));
+			asprintf(&data, "");
+			do{
 				setup_control_request(&req, OP_READVAR, 2);
 				req.assoc = peers[i].assoc;
-				/* By spec, putting the variable name "jitter"  in the request
-				 * should cause the server to provide _only_ the jitter value.
+				/* Putting the wanted variable names in the request
+				 * cause the server to provide _only_ the requested values.
 				 * thus reducing net traffic, guaranteeing us only a single
 				 * datagram in reply, and making intepretation much simpler
 				 */
@@ -605,48 +321,97 @@ double jitter_request(const char *host, int *status){
 				DBG(print_ntp_control_message(&req));
 
 				req.count = htons(MAX_CM_SIZE);
-				DBG(printf("recieving READVAR response...\n"));
+				DBG(printf("receiving READVAR response...\n"));
 				read(conn, &req, SIZEOF_NTPCM(req));
 				DBG(print_ntp_control_message(&req));
 
-				if(req.op&REM_ERROR && strstr(getvar, "jitter")) {
-					if(verbose) printf("The 'jitter' command failed (old ntp server?)\nRestarting with 'dispersion'...\n");
-					getvar = "dispersion";
-					num_selected--;
+				if(!(req.op&REM_ERROR))
+					asprintf(&data, "%s%s", data, req.data);
+			} while(req.op&REM_MORE);
+
+			if(req.op&REM_ERROR) {
+				if(strstr(getvar, "jitter")) {
+					if(verbose) printf("The command failed. This is usually caused by servers refusing the 'jitter'\nvariable. Restarting with 'dispersion'...\n");
+					getvar = "stratum,offset,dispersion";
+					i--;
+					continue;
+				} else if(strlen(getvar)) {
+					if(verbose) printf("Server didn't like dispersion either; will retrieve everything\n");
+					getvar = "";
 					i--;
 					continue;
 				}
+			}
+
+			if(verbose > 1)
+				printf("Server responded: >>>%s<<<\n", data);
+
+			/* get the offset */
+			if(verbose)
+				printf("parsing offset from peer %.2x: ", ntohs(peers[i].assoc));
+
+			value = extract_value(data, "offset");
+			nptr=NULL;
+			/* Convert the value if we have one */
+			if(value != NULL)
+				tmp_offset = strtod(value, &nptr) / 1000;
+			/* If value is null or no conversion was performed */
+			if(value == NULL || value==nptr) {
+				if(verbose) printf("error: unable to read server offset response.\n");
+			} else {
+				if(verbose) printf("%.10g\n", tmp_offset);
+				if(*offset_result == STATE_UNKNOWN || fabs(tmp_offset) < fabs(*offset)) {
+					*offset = tmp_offset;
+					*offset_result = STATE_OK;
+				} else {
+					/* Skip this one; move to the next */
+					continue;
+				}
+			}
 
-				/* get to the float value */
+			if(do_jitter) {
+				/* get the jitter */
 				if(verbose) {
-					printf("parsing jitter from peer %.2x: ", ntohs(peers[i].assoc));
+					printf("parsing %s from peer %.2x: ", strstr(getvar, "dispersion") != NULL ? "dispersion" : "jitter", ntohs(peers[i].assoc));
 				}
-				startofvalue = strchr(req.data, '=');
-				if(startofvalue != NULL) {
-					startofvalue++;
-					jitter = strtod(startofvalue, &nptr);
+				value = extract_value(data, strstr(getvar, "dispersion") != NULL ? "dispersion" : "jitter");
+				nptr=NULL;
+				/* Convert the value if we have one */
+				if(value != NULL)
+					*jitter = strtod(value, &nptr);
+				/* If value is null or no conversion was performed */
+				if(value == NULL || value==nptr) {
+					if(verbose) printf("error: unable to read server jitter/dispersion response.\n");
+					*jitter = -1;
+				} else if(verbose) {
+					printf("%.10g\n", *jitter);
+				}
+			}
+
+			if(do_stratum) {
+				/* get the stratum */
+				if(verbose) {
+					printf("parsing stratum from peer %.2x: ", ntohs(peers[i].assoc));
 				}
-				if(startofvalue == NULL || startofvalue==nptr){
-					printf("warning: unable to read server jitter response.\n");
-					*status = STATE_UNKNOWN;
+				value = extract_value(data, "stratum");
+				nptr=NULL;
+				/* Convert the value if we have one */
+				if(value != NULL)
+					*stratum = strtol(value, &nptr, 10);
+				if(value == NULL || value==nptr) {
+					if(verbose) printf("error: unable to read server stratum response.\n");
+					*stratum = -1;
 				} else {
-					if(verbose) printf("%g\n", jitter);
-					num_valid++;
-					rval += jitter;
+					if(verbose) printf("%i\n", *stratum);
 				}
 			}
-		}
-		if(verbose){
-			printf("jitter parsed from %d/%d peers\n", num_valid, num_selected);
-		}
-	}
-
-	rval = num_valid ? rval / num_valid : -1.0;
+		} /* if (PEER_SEL(peers[i].status) >= min_peer_sel) */
+	} /* for (i = 0; i < npeers; i++) */
 
 	close(conn);
 	if(peers!=NULL) free(peers);
-	/* If we return -1.0, it means no synchronization source was found */
-	return rval;
+
+	return status;
 }
 
 int process_arguments(int argc, char **argv){
@@ -658,8 +423,11 @@ int process_arguments(int argc, char **argv){
 		{"verbose", no_argument, 0, 'v'},
 		{"use-ipv4", no_argument, 0, '4'},
 		{"use-ipv6", no_argument, 0, '6'},
+		{"quiet", no_argument, 0, 'q'},
 		{"warning", required_argument, 0, 'w'},
 		{"critical", required_argument, 0, 'c'},
+		{"swarn", required_argument, 0, 'W'},
+		{"scrit", required_argument, 0, 'C'},
 		{"jwarn", required_argument, 0, 'j'},
 		{"jcrit", required_argument, 0, 'k'},
 		{"timeout", required_argument, 0, 't'},
@@ -672,7 +440,7 @@ int process_arguments(int argc, char **argv){
 		usage ("\n");
 
 	while (1) {
-		c = getopt_long (argc, argv, "Vhv46w:c:j:k:t:H:", longopts, &option);
+		c = getopt_long (argc, argv, "Vhv46qw:c:W:C:j:k:t:H:", longopts, &option);
 		if (c == -1 || c == EOF || c == 1)
 			break;
 
@@ -688,6 +456,9 @@ int process_arguments(int argc, char **argv){
 		case 'v':
 			verbose++;
 			break;
+		case 'q':
+			quiet = 1;
+			break;
 		case 'w':
 			do_offset=1;
 			owarn = optarg;
@@ -696,6 +467,14 @@ int process_arguments(int argc, char **argv){
 			do_offset=1;
 			ocrit = optarg;
 			break;
+		case 'W':
+			do_stratum=1;
+			swarn = optarg;
+			break;
+		case 'C':
+			do_stratum=1;
+			scrit = optarg;
+			break;
 		case 'j':
 			do_jitter=1;
 			jwarn = optarg;
@@ -746,24 +525,31 @@ char *perfd_offset (double offset)
 
 char *perfd_jitter (double jitter)
 {
-	return fperfdata ("jitter", jitter, "s",
+	return fperfdata ("jitter", jitter, "",
 		do_jitter, jitter_thresholds->warning->end,
 		do_jitter, jitter_thresholds->critical->end,
 		TRUE, 0, FALSE, 0);
 }
 
+char *perfd_stratum (int stratum)
+{
+	return perfdata ("stratum", stratum, "",
+		do_stratum, (int)stratum_thresholds->warning->end,
+		do_stratum, (int)stratum_thresholds->critical->end,
+		TRUE, 0, TRUE, 16);
+}
+
 int main(int argc, char *argv[]){
-	int result, offset_result, jitter_result;
+	int result, offset_result, stratum;
 	double offset=0, jitter=0;
 	char *result_line, *perfdata_line;
 
-	result = offset_result = jitter_result = STATE_OK;
-
 	if (process_arguments (argc, argv) == ERROR)
 		usage4 (_("Could not parse arguments"));
 
 	set_thresholds(&offset_thresholds, owarn, ocrit);
 	set_thresholds(&jitter_thresholds, jwarn, jcrit);
+	set_thresholds(&stratum_thresholds, swarn, scrit);
 
 	/* initialize alarm signal handling */
 	signal (SIGALRM, socket_timeout_alarm_handler);
@@ -771,29 +557,24 @@ int main(int argc, char *argv[]){
 	/* set socket timeout */
 	alarm (socket_timeout);
 
-	offset = offset_request(server_address, &offset_result);
-	/* check_ntp used to always return CRITICAL if offset_result == STATE_UNKNOWN.
-	 * Now we'll only do that is the offset thresholds were set */
-	if (do_offset && offset_result == STATE_UNKNOWN) {
-		result = STATE_CRITICAL;
+	/* This returns either OK or WARNING (See comment preceeding ntp_request) */
+	result = ntp_request(server_address, &offset, &offset_result, &jitter, &stratum);
+
+	if(offset_result == STATE_UNKNOWN) {
+		/* if there's no sync peer (this overrides ntp_request output): */
+		result = (quiet == 1 ? STATE_UNKNOWN : STATE_CRITICAL);
 	} else {
-		result = get_status(fabs(offset), offset_thresholds);
+		/* Be quiet if there's no candidates either */
+		if (quiet == 1 && result == STATE_WARNING)
+			result = STATE_UNKNOWN;
+		result = max_state_alt(result, get_status(fabs(offset), offset_thresholds));
 	}
 
-	/* If not told to check the jitter, we don't even send packets.
-	 * jitter is checked using NTP control packets, which not all
-	 * servers recognize.  Trying to check the jitter on OpenNTPD
-	 * (for example) will result in an error
-	 */
-	if(do_jitter){
-		jitter=jitter_request(server_address, &jitter_result);
+	if(do_stratum)
+		result = max_state_alt(result, get_status(stratum, stratum_thresholds));
+
+	if(do_jitter)
 		result = max_state_alt(result, get_status(jitter, jitter_thresholds));
-		/* -1 indicates that we couldn't calculate the jitter
-		 * Only overrides STATE_OK from the offset */
-		if(jitter == -1.0 && result == STATE_OK)
-			result = STATE_UNKNOWN;
-	}
-	result = max_state_alt(result, jitter_result);
 
 	switch (result) {
 		case STATE_CRITICAL :
@@ -809,6 +590,9 @@ int main(int argc, char *argv[]){
 			asprintf(&result_line, "NTP UNKNOWN:");
 			break;
 	}
+	if(!syncsource_found)
+		asprintf(&result_line, "%s %s,", result_line, _("Server not synchronized"));
+
 	if(offset_result == STATE_UNKNOWN){
 		asprintf(&result_line, "%s %s", result_line, _("Offset unknown"));
 		asprintf(&perfdata_line, "");
@@ -818,7 +602,11 @@ int main(int argc, char *argv[]){
 	}
 	if (do_jitter) {
 		asprintf(&result_line, "%s, jitter=%f", result_line, jitter);
-		asprintf(&perfdata_line, "%s %s", perfdata_line,  perfd_jitter(jitter));
+		asprintf(&perfdata_line, "%s %s", perfdata_line, perfd_jitter(jitter));
+	}
+	if (do_stratum) {
+		asprintf(&result_line, "%s, stratum=%i", result_line, stratum);
+		asprintf(&perfdata_line, "%s %s", perfdata_line, perfd_stratum(stratum));
 	}
 	printf("%s|%s\n", result_line, perfdata_line);
 
@@ -833,18 +621,24 @@ void print_help(void){
 
 	printf ("Copyright (c) 2006 Sean Finney\n");
 	printf (COPYRIGHT, copyright, email);
-  
-  printf ("%s\n", _("This plugin checks the selected ntp server"));
 
-  printf ("\n\n");
-  
+	printf ("%s\n", _("This plugin checks the selected ntp server"));
+
+	printf ("\n\n");
+
 	print_usage();
 	printf (_(UT_HELP_VRSN));
 	printf (_(UT_HOST_PORT), 'p', "123");
+	printf (" %s\n", "-q, --quiet");
+	printf ("    %s\n", _("Returns UNKNOWN instead of CRITICAL or WARNING if server isn't synchronized"));
 	printf (" %s\n", "-w, --warning=THRESHOLD");
 	printf ("    %s\n", _("Offset to result in warning status (seconds)"));
 	printf (" %s\n", "-c, --critical=THRESHOLD");
 	printf ("    %s\n", _("Offset to result in critical status (seconds)"));
+	printf (" %s\n", "-W, --warning=THRESHOLD");
+	printf ("    %s\n", _("Warning threshold for stratum"));
+	printf (" %s\n", "-W, --critical=THRESHOLD");
+	printf ("    %s\n", _("Critical threshold for stratum"));
 	printf (" %s\n", "-j, --warning=THRESHOLD");
 	printf ("    %s\n", _("Warning threshold for jitter"));
 	printf (" %s\n", "-k, --critical=THRESHOLD");
@@ -854,17 +648,26 @@ void print_help(void){
 
 	printf("\n");
 	printf("%s\n", _("Notes:"));
+	printf(" %s\n", _("This plugin checks an NTP server independent of any commandline"));
+	printf(" %s\n\n", _("programs or external libraries."));
+	printf(" %s\n", _("Use this plugin to check the health of an NTP server. It supports"));
+	printf(" %s\n", _("checking the offset with the sync peer, the jitter and stratum. This"));
+	printf(" %s\n", _("plugin will not check the clock offset between the local host and NTP"));
+	printf(" %s\n\n", _("server; please use check_ntp_time for that purpose."));
+
 	printf(" %s\n", _("See:"));
 	printf(" %s\n", ("http://nagiosplug.sourceforge.net/developer-guidelines.html#THRESHOLDFORMAT"));
 	printf(" %s\n", _("for THRESHOLD format and examples."));
 
 	printf("\n");
 	printf("%s\n", _("Examples:"));
-	printf(" %s\n", _("Normal offset check:"));
-	printf("  %s\n", ("./check_ntp -H ntpserv -w 0.5 -c 1"));
+	printf(" %s\n", _("Normal NTP server check:"));
+	printf("  %s\n", ("./check_ntp_peer -H ntpserv -w 0.5 -c 1"));
 	printf(" %s\n", _("Check jitter too, avoiding critical notifications if jitter isn't available"));
 	printf(" %s\n", _("(See Notes above for more details on thresholds formats):"));
-	printf("  %s\n", ("./check_ntp -H ntpserv -w 0.5 -c 1 -j -1:100 -k -1:200"));
+	printf("  %s\n", ("./check_ntp_peer -H ntpserv -w 0.5 -c 1 -j -1:100 -k -1:200"));
+	printf(" %s\n", _("Check only stratum:"));
+	printf("  %s\n", ("./check_ntp_peer -H ntpserv -W 4 -C 6"));
 
 	printf (_(UT_SUPPORT));
 }
@@ -872,6 +675,7 @@ void print_help(void){
 void
 print_usage(void)
 {
-  printf (_("Usage:"));
-  printf(" %s -H <host> [-w <warn>] [-c <crit>] [-j <warn>] [-k <crit>] [-v verbose]\n", progname);
+	printf (_("Usage:"));
+	printf(" %s -H <host> [-w <warn>] [-c <crit>] [-W <warn>] [-C <crit>]\n", progname);
+	printf("       [-j <warn>] [-k <crit>] [-v verbose]\n");
 }