Added option to exclude survived gadgets from fingerprint comparison. This is useful for comparing very large, very similar fingerprints.

Author: ThomasOldham

handlers/FingerprintHandlers.go

@@ -287,6 +287,7 @@ func StoredFingerprintSurvivalHandler(w http.ResponseWriter, r *http.Request) {
 func StoredFingerprintComparisonHandler(w http.ResponseWriter, r *http.Request) {
 	f1Name := mux.Vars(r)["fingerprint"]
 	f2Name := r.FormValue("second")
+	includeSurvived := r.FormValue("include-survived") != "false"
 
 	f1Bytes, err := ioutil.ReadFile(FingerprintsDirectory() + f1Name)
 	if err != nil {
@@ -316,7 +317,7 @@ func StoredFingerprintComparisonHandler(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	comparison := lib.CompareFingerprints(f1, f2)
+	comparison := lib.CompareFingerprints(f1, f2, includeSurvived)
 	b, err := json.MarshalIndent(comparison, "", indent)
 	if err != nil {
 		logErrors(err, nil)

lib/CompareFingerprints.go

@@ -4,6 +4,6 @@ import (
 	"github.com/polyverse/ropoly/lib/types"
 )
 
-func CompareFingerprints(f1 types.Fingerprint, f2 types.Fingerprint) types.FingerprintComparison {
-	return f1.CompareTo(f2)
+func CompareFingerprints(f1, f2 types.Fingerprint, includeSurvived bool) types.FingerprintComparison {
+	return f1.CompareTo(f2, includeSurvived)
 }

lib/types/types.go

@@ -115,7 +115,7 @@ func FingerprintFromGadgets(gadgetInstances []*GadgetInstance) (Fingerprint, err
 	return fingerprint, nil
 }
 
-func (f1 Fingerprint) CompareTo(f2 Fingerprint) FingerprintComparison {
+func (f1 Fingerprint) CompareTo(f2 Fingerprint, includeSurvived bool) FingerprintComparison {
 	ret := FingerprintComparison{
 		GadgetDisplacements:   map[Addr]map[GadgetId][]Offset{},
 		NewGadgets:            map[GadgetId][]Addr{},
@@ -124,16 +124,28 @@ func (f1 Fingerprint) CompareTo(f2 Fingerprint) FingerprintComparison {
 
 	for gadget, oldAddresses := range f1 {
 		newAddresses := f2[gadget]
-		for i := 0; i < len(oldAddresses); i++ {
-			oldAddress := oldAddresses[i]
-			offsets := make([]Offset, len(newAddresses))
-			survived := false
-			for j, newAddress := range newAddresses {
-				offset := Offset(newAddress) - Offset(oldAddress)
-				if offset == 0 {
-					survived = true
+		newAddressIndex := 0
+		survivedAddresses := map[Addr]bool{}
+		for _, oldAddress := range oldAddresses {
+			for newAddressIndex < len(newAddresses) && oldAddress > newAddresses[newAddressIndex] {
+				newAddressIndex++
+			}
+			if newAddressIndex < len(newAddresses) && oldAddress == newAddresses[newAddressIndex] {
+				survivedAddresses[oldAddress] = true
+			}
+		}
+		for _, oldAddress := range oldAddresses {
+			survived := survivedAddresses[oldAddress]
+			if (!includeSurvived) && survived {
+				continue
+			}
+			var offsets []Offset
+			for _, newAddress := range newAddresses {
+				if (!includeSurvived) && survivedAddresses[newAddress] {
+					continue
 				}
-				offsets[j] = offset
+				offset := Offset(newAddress) - Offset(oldAddress)
+				offsets = append(offsets, offset)
 				ret.GadgetsByOffset[offset]++
 			}
 			if survived {