Add option to skip signature verification

Author: habara-k

examples/echo_bot/server.go

@@ -26,7 +26,7 @@ import (
 )
 
 func main() {
-	channelSecret := os.Getenv("LINE_CHANNEL_SECRET")
+	channelSecret := "DummyChannelSecret" // Dummy value is fine to skip webhook signature verification
 	bot, err := messaging_api.NewMessagingApiAPI(
 		os.Getenv("LINE_CHANNEL_TOKEN"),
 	)
@@ -38,7 +38,9 @@ func main() {
 	http.HandleFunc("/callback", func(w http.ResponseWriter, req *http.Request) {
 		log.Println("/callback called...")
 
-		cb, err := webhook.ParseRequest(channelSecret, req)
+		cb, err := webhook.ParseRequestWithOption(channelSecret, req, &webhook.ParseOption{
+			SkipSignatureValidation: func() bool { return true },
+		})
 		if err != nil {
 			log.Printf("Cannot parse request: %+v\n", err)
 			if errors.Is(err, webhook.ErrInvalidSignature) {

linebot/webhook/parse.go

@@ -15,14 +15,19 @@ var (
 	ErrInvalidSignature = errors.New("invalid signature")
 )
 
+type ParseOption struct {
+	SkipSignatureValidation func() bool
+}
+
 // ParseRequest func
-func ParseRequest(channelSecret string, r *http.Request) (*CallbackRequest, error) {
+func ParseRequestWithOption(channelSecret string, r *http.Request, opt *ParseOption) (*CallbackRequest, error) {
 	defer func() { _ = r.Body.Close() }()
 	body, err := io.ReadAll(r.Body)
 	if err != nil {
 		return nil, err
 	}
-	if !ValidateSignature(channelSecret, r.Header.Get("x-line-signature"), body) {
+	skip := opt != nil && opt.SkipSignatureValidation != nil && opt.SkipSignatureValidation()
+	if !skip && !ValidateSignature(channelSecret, r.Header.Get("x-line-signature"), body) {
 		return nil, ErrInvalidSignature
 	}
 
@@ -33,6 +38,10 @@ func ParseRequest(channelSecret string, r *http.Request) (*CallbackRequest, erro
 	return &cb, nil
 }
 
+func ParseRequest(channelSecret string, r *http.Request) (*CallbackRequest, error) {
+	return ParseRequestWithOption(channelSecret, r, nil)
+}
+
 func ValidateSignature(channelSecret, signature string, body []byte) bool {
 	decoded, err := base64.StdEncoding.DecodeString(signature)
 	if err != nil {