fix: preserve authenticated HLS session redirects

app.py

@@ -595,7 +595,18 @@ class Handler(BaseHTTPRequestHandler):
             r = conn.getresponse()
             if r.status >= 400:
                 raise Problem('暂时没有可播放画面，请确认设备网络、账号、码流路径和录像时间', 503)
+            location = None
+            if 300 <= r.status < 400:
+                # MediaMTX starts an HLS session with a relative redirect. The
+                # browser must keep that session query on subsequent playlists.
+                target = url.urlsplit(url.urljoin(path, r.getheader('Location', '')))
+                if (port != HLS_PORT or target.scheme or target.netloc
+                        or not re.fullmatch(r'/cam_[a-f0-9]{16}_(main|sub)/[a-zA-Z0-9_.-]+', target.path)):
+                    raise Problem('视频服务返回了无效的播放跳转', 502)
+                location = '/media/live' + target.path + ('?' + target.query if target.query else '')
             self.send_response(r.status)
+            if location:
+                self.send_header('Location', location)
             for k in ('Content-Type', 'Content-Length', 'Content-Range', 'Accept-Ranges'):
                 if r.getheader(k):
                     self.send_header(k, r.getheader(k))