panic in EvaluateThreshold because of unvalidated ParseRangeString return value

[Tommi2Day]

ParseRangeString may return NIL on errors, but in EvaluateThreshold this is not checked will lead to a panic

runtime error: invalid memory address or nil pointer dereference goroutine 36 [running]: runtime/debug.Stack() C:/Users/user/go-sdk/go1.21.3/src/runtime/debug/stack.go:24 +0x6b github.com/atc0005/go-nagios.(*Plugin).ReturnCheckResults(0xc0000c40e0) C:/local/progs/go-proj/src/check_hm/vendor/github.com/atc0005/go-nagios/nagios.go:283 +0x305 panic({0x1af6600?, 0x216afd0?}) C:/Users/user/go-sdk/go1.21.3/src/runtime/panic.go:920 +0x290 github.com/atc0005/go-nagios.(*Plugin).EvaluateThreshold(0xc0000c40e0, {0xc0001f16c0, 0x1, 0x1}) C:/local/progs/go-proj/src/check_hm/vendor/github.com/atc0005/go-nagios/range.go:153 +0xed
First

go-nagios/range.go

Lines 151 to 153 in 7a6e921

	CriticalThresholdObject := ParseRangeString(perfData[i].Crit)
	if CriticalThresholdObject.CheckRange(perfData[i].Value) {

may panic here if CritcalThreshold object is nil

second:

go-nagios/range.go

Lines 160 to 164 in 7a6e921

	warningThresholdObject := ParseRangeString(perfData[i].Warn)
	if warningThresholdObject.CheckRange(perfData[i].Value) {
	p.ExitStatusCode = StateWARNINGExitCode
	return nil

may panic here if warningThreshold object is nil

[atc0005]

@Tommi2Day,

Thank you for this report. I appreciate the specifics you have provided.

@infraweavers,

Any interest in taking a look at this? If you use a modified version of the code contributed in GH-178 is it publicly available?

I figured it was best to touch base with you to see if this was already resolved in a private branch before digging into it.

Thanks.