fix(lib): scans didn't stop on ctx cancellation (#6310)

* fix(lib): scans didn't stop on ctx cancellation

Signed-off-by: Dwi Siswanto <git@dw1.io>

* Update lib/sdk_test.go

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

* fix(lib): wait resources to be released b4 return

Signed-off-by: Dwi Siswanto <git@dw1.io>

---------

Signed-off-by: Dwi Siswanto <git@dw1.io>
Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

lib/sdk.go

@@ -5,6 +5,7 @@ import (
 	"bytes"
 	"context"
 	"io"
+	"sync"
 
 	"github.com/projectdiscovery/nuclei/v3/pkg/authprovider"
 	"github.com/projectdiscovery/nuclei/v3/pkg/catalog"
@@ -64,6 +65,7 @@ type NucleiEngine struct {
 	templatesLoaded bool
 
 	// unexported core fields
+	ctx              context.Context
 	interactshClient *interactsh.Client
 	catalog          catalog.Catalog
 	rateLimiter      *ratelimit.Limiter
@@ -246,9 +248,9 @@ func (e *NucleiEngine) ExecuteCallbackWithCtx(ctx context.Context, callback ...f
 	}
 
 	filtered := []func(event *output.ResultEvent){}
-	for _, callback := range callback {
-		if callback != nil {
-			filtered = append(filtered, callback)
+	for _, cb := range callback {
+		if cb != nil {
+			filtered = append(filtered, cb)
 		}
 	}
 	e.resultCallbacks = append(e.resultCallbacks, filtered...)
@@ -258,15 +260,32 @@ func (e *NucleiEngine) ExecuteCallbackWithCtx(ctx context.Context, callback ...f
 		return ErrNoTemplatesAvailable
 	}
 
-	_ = e.engine.ExecuteScanWithOpts(ctx, templatesAndWorkflows, e.inputProvider, false)
-	defer e.engine.WorkPool().Wait()
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		_ = e.engine.ExecuteScanWithOpts(ctx, templatesAndWorkflows, e.inputProvider, false)
+	}()
+
+	// wait for context to be cancelled
+	select {
+	case <-ctx.Done():
+		<-wait(&wg) // wait for scan to finish
+		return ctx.Err()
+	case <-wait(&wg):
+		// scan finished
+	}
 	return nil
 }
 
 // ExecuteWithCallback is same as ExecuteCallbackWithCtx but with default context
 // Note this is deprecated and will be removed in future major release
 func (e *NucleiEngine) ExecuteWithCallback(callback ...func(event *output.ResultEvent)) error {
-	return e.ExecuteCallbackWithCtx(context.Background(), callback...)
+	ctx := context.Background()
+	if e.ctx != nil {
+		ctx = e.ctx
+	}
+	return e.ExecuteCallbackWithCtx(ctx, callback...)
 }
 
 // Options return nuclei Type Options
@@ -290,6 +309,7 @@ func NewNucleiEngineCtx(ctx context.Context, options ...NucleiSDKOptions) (*Nucl
 	e := &NucleiEngine{
 		opts: types.DefaultOptions(),
 		mode: singleInstance,
+		ctx:  ctx,
 	}
 	for _, option := range options {
 		if err := option(e); err != nil {
@@ -306,3 +326,13 @@ func NewNucleiEngineCtx(ctx context.Context, options ...NucleiSDKOptions) (*Nucl
 func NewNucleiEngine(options ...NucleiSDKOptions) (*NucleiEngine, error) {
 	return NewNucleiEngineCtx(context.Background(), options...)
 }
+
+// wait for a waitgroup to finish
+func wait(wg *sync.WaitGroup) <-chan struct{} {
+	ch := make(chan struct{})
+	go func() {
+		defer close(ch)
+		wg.Wait()
+	}()
+	return ch
+}

lib/sdk_test.go

@@ -0,0 +1,37 @@
+package nuclei_test
+
+import (
+	"context"
+	"log"
+	"testing"
+	"time"
+
+	nuclei "github.com/projectdiscovery/nuclei/v3/lib"
+	"github.com/stretchr/testify/require"
+)
+
+func TestContextCancelNucleiEngine(t *testing.T) {
+	// create nuclei engine with options
+	ctx, cancel := context.WithCancel(context.Background())
+	ne, err := nuclei.NewNucleiEngineCtx(ctx,
+		nuclei.WithTemplateFilters(nuclei.TemplateFilters{Tags: []string{"oast"}}),
+		nuclei.EnableStatsWithOpts(nuclei.StatsOptions{MetricServerPort: 0}),
+	)
+	require.NoError(t, err, "could not create nuclei engine")
+
+	go func() {
+		time.Sleep(time.Second * 2)
+		cancel()
+		log.Println("Test: context cancelled")
+	}()
+
+	// load targets and optionally probe non http/https targets
+	ne.LoadTargets([]string{"http://honey.scanme.sh"}, false)
+	// when callback is nil it nuclei will print JSON output to stdout
+	err = ne.ExecuteWithCallback(nil)
+	if err != nil {
+		// we expect a context cancellation error
+		require.ErrorIs(t, err, context.Canceled, "was expecting context cancellation error")
+	}
+	defer ne.Close()
+}