[feature] Use ETag for robots.txt to prevent mishaps (#3829)v0.18.1

* [feature] Use ETag for robots.txt to prevent mishaps

* check incoming if-none-match header

1 files changed, 20 insertions, 0 deletions

diff --git a/internal/api/robots/robots.go b/internal/api/robots/robots.go
index 98db4682d..b72a01ed6 100644
--- a/internal/api/robots/robots.go
+++ b/internal/api/robots/robots.go
@@ -49,9 +49,29 @@ func (m *Module) Route(attachHandler func(method string, path string, f ...gin.H
 }
 
 func (m *Module) robotsGETHandler(c *gin.Context) {
+	const ETag = "\"" + apiutil.RobotsTxtETag + "\""
+	c.Header("ETag", ETag)
+
+	if c.Request.Header.Get("If-None-Match") == ETag {
+		// Cached.
+		c.AbortWithStatus(http.StatusNotModified)
+		return
+	}
+
+	// Not cached, serve.
 	c.String(http.StatusOK, apiutil.RobotsTxt)
 }
 
 func (m *Module) robotsGETHandlerDisallowNodeInfo(c *gin.Context) {
+	const ETag = "\"" + apiutil.RobotsTxtDisallowNodeInfoETag + "\""
+	c.Header("ETag", ETag)
+
+	if c.Request.Header.Get("If-None-Match") == ETag {
+		// Cached.
+		c.AbortWithStatus(http.StatusNotModified)
+		return
+	}
+
+	// Not cached, serve.
 	c.String(http.StatusOK, apiutil.RobotsTxtDisallowNodeInfo)
 }