fix(tmplexec): memory blowup in multiproto

pkg/tmplexec/generic/exec.go

@@ -1,13 +1,13 @@
 package generic
 
 import (
-	"strings"
 	"sync/atomic"
 
 	"github.com/projectdiscovery/gologger"
 	"github.com/projectdiscovery/nuclei/v3/pkg/output"
 	"github.com/projectdiscovery/nuclei/v3/pkg/protocols"
 	"github.com/projectdiscovery/nuclei/v3/pkg/scan"
+	"github.com/projectdiscovery/nuclei/v3/pkg/tmplexec/utils"
 	mapsutil "github.com/projectdiscovery/utils/maps"
 )
 
@@ -64,17 +64,9 @@ func (g *Generic) ExecuteWithResults(ctx *scan.ScanContext) error {
 				// ideally this should never happen since protocol exits on error and callback is not called
 				return
 			}
-			ID := req.GetID()
-			if ID != "" {
-				builder := &strings.Builder{}
-				for k, v := range event.InternalEvent {
-					builder.WriteString(ID)
-					builder.WriteString("_")
-					builder.WriteString(k)
-					_ = previous.Set(builder.String(), v)
-					builder.Reset()
-				}
-			}
+
+			utils.FillPreviousEvent(req.GetID(), event, previous)
+
 			if event.HasOperatorResult() {
 				g.results.CompareAndSwap(false, true)
 			}

pkg/tmplexec/multiproto/multi.go

@@ -2,14 +2,14 @@ package multiproto
 
 import (
 	"strconv"
-	"strings"
 	"sync/atomic"
 
 	"github.com/projectdiscovery/nuclei/v3/pkg/output"
 	"github.com/projectdiscovery/nuclei/v3/pkg/protocols"
 	"github.com/projectdiscovery/nuclei/v3/pkg/protocols/common/generators"
 	"github.com/projectdiscovery/nuclei/v3/pkg/scan"
 	"github.com/projectdiscovery/nuclei/v3/pkg/templates/types"
+	"github.com/projectdiscovery/nuclei/v3/pkg/tmplexec/utils"
 	mapsutil "github.com/projectdiscovery/utils/maps"
 	stringsutil "github.com/projectdiscovery/utils/strings"
 )
@@ -90,17 +90,7 @@ func (m *MultiProtocol) ExecuteWithResults(ctx *scan.ScanContext) error {
 				return
 			}
 
-			ID := req.GetID()
-			if ID != "" {
-				builder := &strings.Builder{}
-				for k, v := range event.InternalEvent {
-					builder.WriteString(ID)
-					builder.WriteString("_")
-					builder.WriteString(k)
-					_ = previous.Set(builder.String(), v)
-					builder.Reset()
-				}
-			}
+			utils.FillPreviousEvent(req.GetID(), event, previous)
 
 			// log event and generate result for the event
 			ctx.LogEvent(event)

pkg/tmplexec/utils/utils.go

@@ -0,0 +1,34 @@
+package utils
+
+import (
+	"strings"
+
+	"github.com/projectdiscovery/nuclei/v3/pkg/output"
+	mapsutil "github.com/projectdiscovery/utils/maps"
+)
+
+// FillPreviousEvent is a helper function to get the previous event from the event
+// without leading to duplicate prefixes
+func FillPreviousEvent(reqID string, event *output.InternalWrappedEvent, previous *mapsutil.SyncLockMap[string, any]) {
+	if reqID == "" {
+		return
+	}
+
+	for k, v := range event.InternalEvent {
+		if _, ok := previous.Get(k); ok {
+			continue
+		}
+
+		if strings.HasPrefix(k, reqID+"_") {
+			continue
+		}
+
+		var builder strings.Builder
+
+		builder.WriteString(reqID)
+		builder.WriteString("_")
+		builder.WriteString(k)
+
+		_ = previous.Set(builder.String(), v)
+	}
+}