fix: refactoring previous fix in attempt to address ongoing issues

See #211 and #215

lib/handler.go

@@ -2,7 +2,6 @@ package lib
 
 import (
 	"net/http"
-	"net/url"
 	"os"
 	"strings"
 
@@ -116,21 +115,16 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		zap.L().Info("user authorized", zap.String("username", username), zap.String("remote_address", remoteAddr))
 	}
 
-	// Cleanup destination header if it's present by stripping out the prefix
-	// and only keeping the path.
-	if destination := r.Header.Get("Destination"); destination != "" {
-		u, err := url.Parse(destination)
-		if err == nil {
-			destination = strings.TrimPrefix(u.Path, user.Prefix)
-			if !strings.HasPrefix(destination, "/") {
-				destination = "/" + destination
-			}
-			r.Header.Set("Destination", destination)
-		}
+	// Convert the HTTP request into an internal request type
+	req, err := newRequest(r, h.user.Prefix)
+	if err != nil {
+		zap.L().Info("invalid request path or destination", zap.Error(err))
+		http.Error(w, "Invalid request path or destination", http.StatusBadRequest)
+		return
 	}
 
 	// Checks for user permissions relatively to this PATH.
-	allowed := user.Allowed(r, func(filename string) bool {
+	allowed := user.Allowed(req, func(filename string) bool {
 		_, err := user.FileSystem.Stat(r.Context(), filename)
 		return !os.IsNotExist(err)
 	})