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>

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();