output: allow user to ignore small ranges and shared networks

Some have configuration which combines small ranges such as one host, and
greater address ranges that are important to monitor.  Especially the one
host ranges tend to cause a lot of false-positive alarms, as they are
immediately 100% full when a machine requests an address.

Signed-off-by: Sami Kerola <kerolasa@iki.fi>

man/dhcpd-pools.1.in

@@ -159,6 +159,12 @@ is
 If critical percentage is not specified it defaults to
 .BR @ALARM_CRIT@ .
 .TP
+\fB\-\-minsize\fR=\fIsize\f
+Ignore ranges and shared networks that are smaller or equal to the
+defined size.  This option is meaningful only in context of alarming, and
+will intented to supress for example single host ranges.  By default this
+option is not in use.
+.TP
 \fB\-v\fR, \fB\-\-version\fR
 Print version information to standard output and exit successfully.
 .TP

src/dhcpd-pools.c

@@ -72,7 +72,8 @@ int main(int argc, char **argv)
 	struct range_t *tmp_ranges;
 	enum {
 		OPT_WARN = CHAR_MAX + 1,
-		OPT_CRIT
+		OPT_CRIT,
+		OPT_MINSIZE
 	};
 	int ret_val;
 
@@ -89,6 +90,7 @@ int main(int argc, char **argv)
 		{"help", no_argument, NULL, 'h'},
 		{"warning", required_argument, NULL, OPT_WARN},
 		{"critical", required_argument, NULL, OPT_CRIT},
+		{"minsize", required_argument, NULL, OPT_MINSIZE},
 		{NULL, 0, NULL, 0}
 	};
 
@@ -192,6 +194,10 @@ int main(int argc, char **argv)
 			config.critical =
 			    strtod_or_err(optarg, "illegal argument");
 			break;
+		case OPT_MINSIZE:
+			config.minsize =
+			    strtod_or_err(optarg, "illegal argument");
+			break;
 		case 'v':
 			/* Print version */
 			print_version();

src/dhcpd-pools.h

@@ -110,6 +110,7 @@ struct configuration_t {
 	bool backups_found;
 	double warning;
 	double critical;
+	double minsize;
 };
 /*! \struct shared_network_t
  * \brief Counters for an individual shared network.

src/other.c

@@ -314,7 +314,8 @@ This is ISC dhcpd pools usage analyzer.\n\
   -L, --limit=NR         output limit mask 77 - 00\n");
 	fprintf(out, "\
       --warning=PERC     set warning alarming limit\n\
-      --critical=PERC    set critical alarming limit\n");
+      --critical=PERC    set critical alarming limit\n\
+      --minsize=size     disable alarms for small ranges and shared-nets\n");
 	fprintf(out, "\
   -v, --version          version information\n\
   -h, --help             this screen\n\

src/output.c

@@ -1018,7 +1018,7 @@ int output_alarming(void)
 	struct shared_network_t *shared_p;
 	unsigned int i;
 	float perc;
-	int rw = 0, rc = 0, ro = 0, sw = 0, sc = 0, so = 0;
+	int rw = 0, rc = 0, ro = 0, ri = 0, sw = 0, sc = 0, so = 0, si = 0;
 	int ret_val, ret;
 
 	range_p = ranges;
@@ -1037,27 +1037,36 @@ int output_alarming(void)
 
 	if (config.output_limit[1] & BIT1) {
 		for (i = 0; i < num_ranges; i++) {
-			perc = (float)(100 * range_p->count) / range_size;
-			if (config.critical < perc)
-				rc++;
-			else if (config.warning < perc)
-				rw++;
-			else
-				ro++;
+			if (config.minsize < range_size) {
+				perc =
+				    (float)(100 * range_p->count) / range_size;
+				if (config.critical < perc)
+					rc++;
+				else if (config.warning < perc)
+					rw++;
+				else
+					ro++;
+			} else {
+				ri++;
+			}
 			range_p++;
 			range_size = get_range_size(range_p);
 		}
 	}
 	if (config.output_limit[1] & BIT2) {
 		for (i = 0; i < num_shared_networks; i++) {
-			perc = (float)(100 * shared_p->used) /
-			    shared_p->available;
-			if (config.critical < perc)
-				sc++;
-			else if (config.warning < perc)
-				sw++;
-			else
-				so++;
+			if (config.minsize < shared_p->available) {
+				perc = (float)(100 * shared_p->used) /
+				    shared_p->available;
+				if (config.critical < perc)
+					sc++;
+				else if (config.warning < perc)
+					sw++;
+				else
+					so++;
+			} else {
+				si++;
+			}
 			shared_p++;
 		}
 	}
@@ -1079,10 +1088,17 @@ int output_alarming(void)
 	if (config.output_limit[0] & BIT1) {
 		fprintf(outfile, "Ranges; crit: %d warn: %d ok: %d ", rc, rw,
 			ro);
+		if (ri != 0) {
+			fprintf(outfile, "ignored: %d ", ri);
+		}
+
 	}
 	if (config.output_limit[0] & BIT2) {
 		fprintf(outfile, "Shared nets; crit: %d warn: %d ok: %d", sc,
 			sw, so);
+		if (si != 0) {
+			fprintf(outfile, "ignored: %d ", si);
+		}
 	}
 	fprintf(outfile, "\n");
 	if (outfile == stdout) {