WIP: check if reconstructed perfdata from regex matches is same as the original string

still wip, might fail in real deployments.

Add test for it, detects if textual data written at the end of a perfstring is discarded.

Author: Ahmet Oeztuerk

pkg/nagflux/collector/spoolfile/nagiosSpoolfileWorker.go

@@ -88,6 +88,7 @@ var (
 	//		Same as 6th capture group, but it is for the maximum value this time.
 	// '\s' matches any whitespace character, infinite times.
 	//	Idea: It seperates different perf data values as this must be matched new capture group can be captured
+	// Overall this script will detect a perfdata in Nagios syntax
 	regexPerformancelable = regexp.MustCompile(`([^=]+)=(U|[\d\.\,\-]+)([\pL\/\%]*);?([\d\.\,\-\:\~\@]*)?;?([\d\.\,\-\:\~\@]*)?;?([\d\.\,\-]*)?;?([\d\.\,\-]*)?;?\s*`)
 
 	// The perfdata part might have some alternative check at the end, recognize it by it being at the end and only containing letters, '_', '-'
@@ -254,8 +255,8 @@ func (w *NagiosSpoolfileWorker) PerformanceDataIterator(input map[string]string)
 
 	// anonymous closure, starts immediately after definition in another goroutine without blocking
 	go func() {
-		perdataString := input[dataType+"PERFDATA"]
-		cleaned := regexStripErrors.ReplaceAllString(perdataString, "")
+		perfdataString := input[dataType+"PERFDATA"]
+		perfdataStringErrorsRemoved := regexStripErrors.ReplaceAllString(perfdataString, "")
 
 		// Slices up the string into a form like this
 		// Each match is put into an array with their capture groups
@@ -269,14 +270,27 @@ func (w *NagiosSpoolfileWorker) PerformanceDataIterator(input map[string]string)
 				["pl=0%;80;100;0;100","pl","0","%","80","100","0","100"]
 			]
 		*/
-		perfdataStringMatches := regexPerformancelable.FindAllStringSubmatch(cleaned, -1)
+		perfdataStringMatches := regexPerformancelable.FindAllStringSubmatch(perfdataStringErrorsRemoved, -1)
 		currentCheckMultiLabel := ""
 
 		// try to find a check_multi prefix
 		if len(perfdataStringMatches) > 0 && len(perfdataStringMatches[0]) > 1 {
 			currentCheckMultiLabel = getCheckMultiRegexMatch(perfdataStringMatches[0][1])
 		}
 
+		// check if concataneting matches makes up the original string
+		matchesConcatenated := ""
+		for _, matchAndCaptureGroups := range perfdataStringMatches {
+			match := matchAndCaptureGroups[0]
+			matchesConcatenated += match
+		}
+
+		if len(matchesConcatenated) > 0 && strings.TrimSpace(matchesConcatenated) != strings.TrimSpace(perfdataString) {
+			log.Warnf("Perfdata matches: '%v' when concatanted come up to be: '%s', and original perfdata string is: '%s' . They are not equal after stripping whitespace from both", perfdataStringMatches, matchesConcatenated, perfdataString)
+			close(ch)
+			return
+		}
+
 		for _, perfdataStringMatch := range perfdataStringMatches {
 			// Allows to add tags and fields to spoolfileentries
 			tags := map[string]string{}

pkg/nagflux/collector/spoolfile/nagiosSpoolfileWorker_test.go

@@ -583,6 +583,28 @@ func TestPerformanceDataParser_LongMaxValue(t *testing.T) {
 	assert.Emptyf(t, collectedPerfData, "Item should not be taken into the performance data due to long length of maximum value, splittedPerformanceData: %v", splittedPerformanceData)
 }
 
+func TestPerformanceDataParser_GarbageStringAfterPerfdata(t *testing.T) {
+	t.Helper()
+
+	config.InitConfigFromString(configFileContent)
+
+	w := NewNagiosSpoolfileWorker(0, nil, nil, nil, 4096, collector.AllFilterable, PerfdataLabelMaxLengthDefault, PerfdataUOMMaxLengthDefault, PerfdataNumericValuesMaxLengthDefault, PerfdataThresholdsMaxLengthDefault)
+
+	// If you use underscores in the uom, it gets split out and only the first part is taken.
+	// UOM is deliberately written without underscores here
+	splittedPerformanceData := helper.StringToMap(
+		"DATATYPE::SERVICEPERFDATA	TIMET::1441791000	HOSTNAME::xxx	SERVICEDESC::range	SERVICEPERFDATA::passme=1 failme=1;1:2;3:4;5;6-hello-i-am-garbage-string-that-should-be-detected-as-i-am-not-whitespace	SERVICECHECKCOMMAND::check_dummy	SERVICESTATE::0	SERVICESTATETYPE::1",
+		"\t", "::")
+
+	//nolint:prealloc // do not know the size of the iterable
+	collectedPerfData := []PerformanceData{}
+	for singlePerfdata := range w.PerformanceDataIterator(splittedPerformanceData) {
+		collectedPerfData = append(collectedPerfData, *singlePerfdata)
+	}
+
+	assert.Emptyf(t, collectedPerfData, "Item should not be taken into the performance data due to long length of maximum value, splittedPerformanceData: %v", splittedPerformanceData)
+}
+
 func testPerformanceDataParser(t *testing.T, input string, expect []PerformanceData) {
 	t.Helper()