allow large HTTP body so long as resulting message is small

server/errors.go

@@ -117,6 +117,7 @@ var (
 	errHTTPBadRequestWebPushSubscriptionInvalid      = &errHTTP{40038, http.StatusBadRequest, "invalid request: web push payload malformed", "", nil}
 	errHTTPBadRequestWebPushEndpointUnknown          = &errHTTP{40039, http.StatusBadRequest, "invalid request: web push endpoint unknown", "", nil}
 	errHTTPBadRequestWebPushTopicCountTooHigh        = &errHTTP{40040, http.StatusBadRequest, "invalid request: too many web push topic subscriptions", "", nil}
+	errHTTPBadRequestTemplatedMessageTooLarge        = &errHTTP{40041, http.StatusBadRequest, "invalid request: message is too large after replacing template", "", nil}
 	errHTTPNotFound                                  = &errHTTP{40401, http.StatusNotFound, "page not found", "", nil}
 	errHTTPUnauthorized                              = &errHTTP{40101, http.StatusUnauthorized, "unauthorized", "https://ntfy.sh/docs/publish/#authentication", nil}
 	errHTTPForbidden                                 = &errHTTP{40301, http.StatusForbidden, "forbidden", "https://ntfy.sh/docs/publish/#authentication", nil}

server/server.go

@@ -1044,8 +1044,11 @@ func (s *Server) parsePublishParams(r *http.Request, m *message) (cache bool, fi
 //     Body must be attachment, because we passed a filename
 //  5. curl -T file.txt ntfy.sh/mytopic
 //     If file.txt is <= 4096 (message limit) and valid UTF-8, treat it as a message
-//  6. curl -T file.txt ntfy.sh/mytopic
-//     If file.txt is > message limit, treat it as an attachment
+//  6. curl -H "Template: yes" -T file.txt ntfy.sh/mytopic
+//     If file.txt is < 4096*2 (message limit*2) and a template is used, try parsing under the assumption
+//     that the message generated by the template will be less than 4096
+//  7. curl -T file.txt ntfy.sh/mytopic
+//     If file.txt is > message limit or template && file.txt > message limit*2, treat it as an attachment
 func (s *Server) handlePublishBody(r *http.Request, v *visitor, m *message, body *util.PeekedReadCloser, template bool, unifiedpush bool) error {
 	if m.Event == pollRequestEvent { // Case 1
 		return s.handleBodyDiscard(body)
@@ -1057,8 +1060,16 @@ func (s *Server) handlePublishBody(r *http.Request, v *visitor, m *message, body
 		return s.handleBodyAsAttachment(r, v, m, body) // Case 4
 	} else if !body.LimitReached && utf8.Valid(body.PeekedBytes) {
 		return s.handleBodyAsTextMessage(m, body, template) // Case 5
+	} else if template {
+		templateBody, err := util.Peek(body, s.config.MessageSizeLimit*2)
+		if err != nil {
+			return err
+		}
+		if !templateBody.LimitReached {
+			return s.handleBodyAsTextMessage(m, templateBody, template) // Case 6
+		}
 	}
-	return s.handleBodyAsAttachment(r, v, m, body) // Case 6
+	return s.handleBodyAsAttachment(r, v, m, body) // Case 7
 }
 
 func (s *Server) handleBodyDiscard(body *util.PeekedReadCloser) error {
@@ -1104,6 +1115,10 @@ func (s *Server) handleBodyAsTextMessage(m *message, body *util.PeekedReadCloser
 	if m.Attachment != nil && m.Attachment.Name != "" && m.Message == "" {
 		m.Message = fmt.Sprintf(defaultAttachmentMessage, m.Attachment.Name)
 	}
+	// Ensure message is less than message limit after templating
+	if len(m.Message) > s.config.MessageSizeLimit {
+		return errHTTPBadRequestTemplatedMessageTooLarge
+	}
 	return nil
 }
 

server/server_test.go

@@ -2754,6 +2754,35 @@ func TestServer_MessageTemplate_FancyGJSON(t *testing.T) {
 	require.Equal(t, `2 Severe Errors`, m.Title)
 }
 
+func TestServer_MessageTemplate_ExceedMessageSize_TemplatedMessageOK(t *testing.T) {
+	c := newTestConfig(t)
+	c.MessageSizeLimit = 25 // 25 < len(HTTP body) < 25*2 && len(m.Message) < 25
+	s := newTestServer(t, c)
+	response := request(t, s, "PUT", "/mytopic", `{"foo":"bar", "nested":{"title":"here"}}`, map[string]string{
+		"X-Message":  "${foo}",
+		"X-Title":    "${nested.title}",
+		"X-Template": "1",
+	})
+
+	require.Equal(t, 200, response.Code)
+	m := toMessage(t, response.Body.String())
+	require.Equal(t, "bar", m.Message)
+	require.Equal(t, "here", m.Title)
+}
+
+func TestServer_MessageTemplate_ExceedMessageSize_TemplatedMessageTooLong(t *testing.T) {
+	c := newTestConfig(t)
+	c.MessageSizeLimit = 21 // 21 < len(HTTP body) < 21*2 && !len(m.Message) < 21
+	s := newTestServer(t, c)
+	response := request(t, s, "PUT", "/mytopic", `{"foo":"This is a long message"}`, map[string]string{
+		"X-Message":  "${foo}",
+		"X-Template": "1",
+	})
+
+	require.Equal(t, 400, response.Code)
+	require.Equal(t, 40041, toHTTPError(t, response.Body.String()).Code)
+}
+
 func newTestConfig(t *testing.T) *Config {
 	conf := NewConfig()
 	conf.BaseURL = "http://127.0.0.1:12345"