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perf(processors): Rate limit PE parsing #435

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perf(processors): Rate limit PE parsing #435

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11 changes: 11 additions & 0 deletions internal/etw/processors/processor.go
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Original file line number Diff line number Diff line change
Expand Up @@ -19,10 +19,12 @@
package processors

import (
"expvar"
libntfs "github.com/rabbitstack/fibratus/pkg/fs/ntfs"
"github.com/rabbitstack/fibratus/pkg/kevent"
"github.com/rabbitstack/fibratus/pkg/kevent/kparams"
"github.com/rabbitstack/fibratus/pkg/pe"
"golang.org/x/time/rate"
"os"
)

Expand Down Expand Up @@ -83,6 +85,10 @@ func (typ ProcessorType) String() string {
}
}

var lim = rate.NewLimiter(30, 40) // allow 30 parse ops per second or bursts of 40 ops

var parseImageFileCharacteristicsRateLimits = expvar.NewInt("processors.image.file.characteristics.rate.limits")

// parseImageFileCharacteristics parses the PE structure for the file path
// residing in the given event parameters. The preferred method for reading
// the PE metadata is by directly accessing the file.
Expand All @@ -92,6 +98,11 @@ func (typ ProcessorType) String() string {
// data. Most notably, parameters that indicate whether the file is a DLL,
// executable image, or a Windows driver.
func parseImageFileCharacteristics(e *kevent.Kevent) error {
if !lim.Allow() {
parseImageFileCharacteristicsRateLimits.Add(1)
return nil
}

var pefile *pe.PE
filename := e.GetParamAsString(kparams.FilePath)
f, err := os.Open(filename)
Expand Down