- check_ntp:

  - now roughly feature-complete.
  - various bugfixes, esp. offset calculation.
  - enhanced the asynchronous offset polling to set requests that
    haven't recieved a response in >= 1 second to stale and retransmit them,
    which results in much better performance on unreliable networks.
  - we only spend timeout/2 seconds polling offsets, and if we don't get
    everything by that point we work with what we have and set status to
    warning/critical depending on how much data we have.
  - set the same defaults as the perl script.
- commit changes to configure.in to support automatic building of check_apt
  (if apt-get is installed and regex libraries available) and check_ntp
  (unconditionally), now defaulting to check_ntp.c instead of the perl script.
  if this is an issue we can back out the commit of course.  an eye
  should be kept on check_ntp building and running correctly in different
  environments, esp. 64-bit and big-endian platforms, and those with more
  "esoteric" API's (do any of the platforms not have poll()?).
- similar changes to Makefile.am's.
- common.h: add statement to include sys/poll.h
- runcmd.c: exit STATE_UNKNOWN if execve() fails.


git-svn-id: https://nagiosplug.svn.sourceforge.net/svnroot/nagiosplug/nagiosplug/trunk@1386 f882894a-f735-0410-b71e-b25c423dba1c

1 files changed, 144 insertions, 76 deletions

diff --git a/plugins/check_ntp.c b/plugins/check_ntp.c
index 149ca98..655dd4f 100644
--- a/plugins/check_ntp.c
+++ b/plugins/check_ntp.c
@@ -29,16 +29,15 @@ const char *email = "nagiosplug-devel@lists.sourceforge.net";
 #include "common.h"
 #include "netutils.h"
 #include "utils.h"
-#include <sys/poll.h>
 
 static char *server_address=NULL;
 static int verbose=0;
 static int zero_offset_bad=0;
-static double owarn=0;
-static double ocrit=0;
+static double owarn=60;
+static double ocrit=120;
 static short do_jitter=0;
-static double jwarn=0;
-static double jcrit=0;
+static double jwarn=5000;
+static double jcrit=10000;
 
 int process_arguments (int, char **);
 void print_help (void);
@@ -67,8 +66,11 @@ typedef struct {
 
 /* this structure holds data about results from querying offset from a peer */
 typedef struct {
-        int waiting;            /* we set to 1 to signal waiting for a response */  
+        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 */
 } ntp_server_results;
 
@@ -192,13 +194,12 @@ typedef struct {
 
 /* 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, rtdelay;
+        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));
-        rtdelay=NTP32asDOUBLE(m->rtdelay);
-        return (.5*((peer_tx-client_rx)+(peer_rx-client_tx)))-rtdelay;
+        return (.5*((peer_tx-client_rx)+(peer_rx-client_tx)));
 }
 
 /* print out a ntp packet in human readable/debuggable format */
@@ -279,14 +280,63 @@ void setup_request(ntp_message *p){
         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++){
+                /* 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){
+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, servers_readable=0, offsets_recvd=0;
+        int servers_completed=0, one_written=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;
@@ -337,28 +387,24 @@ double offset_request(const char *host){
                 ai_tmp = ai_tmp->ai_next;
         }
 
-        /* now do AVG_NUM checks to each host. */
-        while(servers_completed<num_hosts){
-
-                /* write to any servers that are free and have done < AVG_NUM reqs */
-                /* XXX we need some kind of ability to retransmit lost packets.
-                 * XXX one way would be replace "waiting" with a timestamp and
-                 * XXX if the timestamp is old enough the request is re-transmitted.
-                 * XXX then a certain number of failures could mark a server as
-                 * XXX bad, which is what i imagine that ntpdate does though
-                 * XXX i can't confirm it (i think it still only sends a max
-                 * XXX of AVG_NUM requests, but what does it do if one fails
-                 * XXX but the others succeed? */
-                /* XXX also we need the ability to cut out failed/unresponsive
-                 * XXX servers.  currently after doing all other servers we
-                 * XXX still wait for them until the bitter end/timeout. */
+        /* 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 && servers[i].num_responses<AVG_NUM){
+                        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=1;
+                                servers[i].waiting=now_time;
                                 one_written=1;
                                 break;
                         }
@@ -373,17 +419,22 @@ double offset_request(const char *host){
 
                 /* read from any sockets with pending data */
                 for(i=0; servers_readable && i<num_hosts; i++){
-                        if(ufds[i].revents&POLLIN){
+                        if(ufds[i].revents&POLLIN && servers[i].num_responses < AVG_NUM){
                                 if(verbose) {
                                         printf("response from peer %d: ", i);
                                 }
+
                                 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 %g\n", servers[i].offset[respnum]);
+                                        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_readable--;
                                 if(servers[i].num_responses==AVG_NUM) servers_completed++;
@@ -392,15 +443,17 @@ double offset_request(const char *host){
                 /* lather, rinse, repeat. */
         }
 
-        /* finally, calculate the average offset */
-        /* XXX still something about the "top 5" */
-        for(i=0;i<num_hosts;i++){
-                for(j=0;j<servers[i].num_responses;j++){
-                        offsets_recvd++;
-                        avg_offset+=servers[i].offset[j];
+        /* now, pick the best server from the list */
+        best_index=best_offset_server(servers, num_hosts);
+        if(best_index < 0){
+                *status=STATE_CRITICAL;
+        } else {
+                /* finally, calculate the average offset */
+                for(i=0; i<servers[best_index].num_responses;i++){
+                        avg_offset+=servers[best_index].offset[j];
                 }
+                avg_offset/=servers[best_index].num_responses;
         }
-        avg_offset/=offsets_recvd;
 
         /* cleanup */
         for(j=0; j<num_hosts; j++){ close(socklist[j]); }
@@ -410,7 +463,7 @@ double offset_request(const char *host){
         free(req);
         freeaddrinfo(ai);
 
-        if(verbose) printf("overall average offset: %g\n", avg_offset);
+        if(verbose) printf("overall average offset: %.10g\n", avg_offset);
         return avg_offset;
 }
 
@@ -426,10 +479,11 @@ setup_control_request(ntp_control_message *p, uint8_t opcode, uint16_t seq){
 }
 
 /* XXX handle responses with the error bit set */
-double jitter_request(const char *host){
+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;
-        ntp_assoc_status_pair *peers;
+        int peer_offset=0;
+        ntp_assoc_status_pair *peers=NULL;
         ntp_control_message req;
         double rval = 0.0, jitter = -1.0;
         char *startofvalue=NULL, *nptr=NULL;
@@ -449,27 +503,28 @@ double jitter_request(const char *host){
          * 4) Extract the jitter value from the data[] (it's ASCII)
          */
         my_udp_connect(server_address, 123, &conn);
-        setup_control_request(&req, OP_READSTAT, 1);
-
-        DBG(printf("sending READSTAT request"));
-        write(conn, &req, SIZEOF_NTPCM(req));
-        DBG(print_ntp_control_message(&req));
-        /* Attempt to read the largest size packet possible
-         * Is it possible for an NTP server to have more than 117 synchronization
-         * sources?  If so, we will receive a second datagram with additional
-         * peers listed, since 117 is the maximum number that can fit in a
-         * single NTP control datagram.  This code doesn't handle that case */
-        /* XXX check the REM_MORE bit */
-        req.count=htons(MAX_CM_SIZE);
-        DBG(printf("recieving READSTAT response"))
-        read(conn, &req, SIZEOF_NTPCM(req));
-        DBG(print_ntp_control_message(&req));
-        /* Each peer identifier is 4 bytes in the data section, which
-         * we represent as a ntp_assoc_status_pair datatype.
-         */
-        npeers=ntohs(req.count)/sizeof(ntp_assoc_status_pair);
-        peers=(ntp_assoc_status_pair*)malloc(sizeof(ntp_assoc_status_pair)*npeers);
-        memcpy((void*)peers, (void*)req.data, sizeof(ntp_assoc_status_pair)*npeers);
+
+        /* keep sending requests until the server stops setting the
+         * REM_MORE bit, though usually this is only 1 packet. */
+        do{
+                setup_control_request(&req, OP_READSTAT, 1);
+                DBG(printf("sending READSTAT request"));
+                write(conn, &req, SIZEOF_NTPCM(req));
+                DBG(print_ntp_control_message(&req));
+                /* Attempt to read the largest size packet possible */
+                req.count=htons(MAX_CM_SIZE);
+                DBG(printf("recieving READSTAT response"))
+                read(conn, &req, SIZEOF_NTPCM(req));
+                DBG(print_ntp_control_message(&req));
+                /* Each peer identifier is 4 bytes in the data section, which
+                 * we represent as a ntp_assoc_status_pair datatype.
+                 */
+                npeers+=(ntohs(req.count)/sizeof(ntp_assoc_status_pair));
+                peers=(ntp_assoc_status_pair*)realloc(peers, sizeof(ntp_assoc_status_pair)*npeers);
+                memcpy((void*)peers+peer_offset, (void*)req.data, sizeof(ntp_assoc_status_pair)*npeers);
+                peer_offset+=ntohs(req.count);
+        } 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
          * a warning but go ahead with the check on them. */
@@ -484,13 +539,15 @@ double jitter_request(const char *host){
         }
         if(verbose) printf("%d candiate peers available\n", num_candidates);
         if(verbose && syncsource_found) printf("synchronization source found\n");
-        /* XXX if ! syncsource_found set status to warning */
+        if(! syncsource_found) *status = STATE_WARNING;
+
 
         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++;
                                 setup_control_request(&req, OP_READVAR, 2);
                                 req.assoc = peers[i].assoc;
                                 /* By spec, putting the variable name "jitter"  in the request
@@ -514,11 +571,12 @@ double jitter_request(const char *host){
                                         printf("parsing jitter from peer %.2x: ", peers[i].assoc);
                                 }
                                 startofvalue = strchr(req.data, '=') + 1;
-                                jitter = strtod(startofvalue, &nptr);
-                                num_selected++;
-                                if(jitter == 0 && startofvalue==nptr){
-                                        printf("warning: unable to parse server response.\n");
-                                        /* XXX errors value ... */
+                                if(startofvalue != NULL) {
+                                        jitter = strtod(startofvalue, &nptr);
+                                }
+                                if(startofvalue == NULL || startofvalue==nptr){
+                                        printf("warning: unable to read server jitter response.\n");
+                                        *status = STATE_WARNING;
                                 } else {
                                         if(verbose) printf("%g\n", jitter);
                                         num_valid++;
@@ -527,7 +585,7 @@ double jitter_request(const char *host){
                         }
                 }
                 if(verbose){
-                        printf("jitter parsed from %d/%d peers\n", num_selected, num_valid);
+                        printf("jitter parsed from %d/%d peers\n", num_valid, num_selected);
                 }
         }
 
@@ -637,9 +695,11 @@ int process_arguments(int argc, char **argv){
 }
 
 int main(int argc, char *argv[]){
-        int result = STATE_UNKNOWN;
+        int result, offset_result, jitter_result;
         double offset=0, jitter=0;
 
+        result=offset_result=jitter_result=STATE_UNKNOWN;
+
         if (process_arguments (argc, argv) == ERROR)
                 usage4 (_("Could not parse arguments"));
 
@@ -649,14 +709,15 @@ int main(int argc, char *argv[]){
         /* set socket timeout */
         alarm (socket_timeout);
 
-        offset = offset_request(server_address);
-        if(offset > ocrit){
+        offset = offset_request(server_address, &offset_result);
+        if(fabs(offset) > ocrit){
                 result = STATE_CRITICAL;
-        } else if(offset > owarn) {
+        } else if(fabs(offset) > owarn) {
                 result = STATE_WARNING;
         } else {
                 result = STATE_OK;
         }
+        result=max_state(result, offset_result);
 
         /* If not told to check the jitter, we don't even send packets.
          * jitter is checked using NTP control packets, which not all
@@ -664,7 +725,7 @@ int main(int argc, char *argv[]){
          * (for example) will result in an error
          */
         if(do_jitter){
-                jitter=jitter_request(server_address);
+                jitter=jitter_request(server_address, &jitter_result);
                 if(jitter > jcrit){
                         result = max_state(result, STATE_CRITICAL);
                 } else if(jitter > jwarn) {
@@ -675,6 +736,7 @@ int main(int argc, char *argv[]){
                         result = STATE_UNKNOWN;
                 }
         }
+        result=max_state(result, jitter_result);
 
         switch (result) {
                 case STATE_CRITICAL :
@@ -690,9 +752,15 @@ int main(int argc, char *argv[]){
                         printf("NTP UNKNOWN: ");
                         break;
         }
-
-        printf("Offset %g secs|offset=%g", offset, offset);
-        if (do_jitter) printf("|jitter=%f", jitter);
+        if(offset_result==STATE_CRITICAL){
+                printf("Offset unknown|offset=unknown");
+        } else {
+                if(offset_result==STATE_WARNING){
+                        printf("Unable to fully sample sync server. ");
+                }
+                printf("Offset %.10g secs|offset=%.10g", offset, offset);
+        }
+        if (do_jitter) printf(", jitter=%f", jitter);
         printf("\n");
 
         if(server_address!=NULL) free(server_address);