fix: an answer whose client went away ends quietly, and a shell whose client left before it opened is stopped.

debian-package/src/usr/lib/vpn-router/vpnrouter_web/sites.py

@@ -112,15 +112,19 @@ def site_files(handler, name, relative, query, payload, send_body):
                 return 404, {'error': f'{relative} does not exist'}
             with open(target, 'rb') as handle:
                 size = os.fstat(handle.fileno()).st_size
-                handler.send_response(200)
-                handler.send_header('Content-Type', mimetypes.guess_type(target.name)[0] or 'application/octet-stream')
-                handler.send_header('Content-Length', str(size))
-                handler.send_header('Content-Disposition',
-                                    f"attachment; filename*=UTF-8''{urllib.parse.quote(target.name)}")
-                handler.send_header('Cache-Control', 'no-store')
-                handler.end_headers()
-                if send_body:
-                    shutil.copyfileobj(handle, handler.wfile, vpnrouter_sites.CHUNK)
+                try:
+                    handler.send_response(200)
+                    handler.send_header('Content-Type', mimetypes.guess_type(target.name)[0] or 'application/octet-stream')
+                    handler.send_header('Content-Length', str(size))
+                    handler.send_header('Content-Disposition',
+                                        f"attachment; filename*=UTF-8''{urllib.parse.quote(target.name)}")
+                    handler.send_header('Cache-Control', 'no-store')
+                    handler.end_headers()
+                    if send_body:
+                        shutil.copyfileobj(handle, handler.wfile, vpnrouter_sites.CHUNK)
+                except ConnectionError:
+                    # The client went away before the file was sent.
+                    handler.close_connection = True
             return None
         if handler.command == 'PUT':
             length = handler.headers.get('Content-Length')