Security Fix: clean paths correctly to avoid circumvention of BlacklistedPaths

server/utils/utils.go

@@ -1,6 +1,8 @@
 package utils
 
 import (
+	"net/url"
+	"path"
 	"strings"
 )
 
@@ -11,3 +13,15 @@ func TrimHostPort(host string) string {
 	}
 	return host
 }
+
+func CleanPath(uriPath string) string {
+	unescapedPath, _ := url.PathUnescape(uriPath)
+	cleanedPath := path.Join("/", unescapedPath)
+
+	// If the path refers to a directory, add a trailing slash.
+	if !strings.HasSuffix(cleanedPath, "/") && (strings.HasSuffix(unescapedPath, "/") || strings.HasSuffix(unescapedPath, "/.") || strings.HasSuffix(unescapedPath, "/..")) {
+		cleanedPath += "/"
+	}
+
+	return cleanedPath
+}