QUIC: asynchronous shutdown. Previously, when cleaning up a QUIC stream in shutdown mode, ngx_quic_shutdown_quic() was called, which could close the QUIC connection right away. This could be a problem if the connection was referenced up the stack. For example, this could happen in ngx_quic_init_streams(), ngx_quic_close_streams(), ngx_quic_create_client_stream() etc. With a typical HTTP/3 client the issue is unlikely because of HTTP/3 uni streams which need a posted event to close. In this case QUIC connection cannot be closed right away. Now QUIC connection read event is posted and it will shut down the connection asynchronously.

scgi_param  REQUEST_METHOD     $request_method;
scgi_param  REQUEST_URI        $request_uri;
scgi_param  QUERY_STRING       $query_string;
scgi_param  CONTENT_TYPE       $content_type;

scgi_param  DOCUMENT_URI       $document_uri;
scgi_param  DOCUMENT_ROOT      $document_root;
scgi_param  SCGI               1;
scgi_param  SERVER_PROTOCOL    $server_protocol;
scgi_param  REQUEST_SCHEME     $scheme;
scgi_param  HTTPS              $https if_not_empty;

scgi_param  REMOTE_ADDR        $remote_addr;
scgi_param  REMOTE_PORT        $remote_port;
scgi_param  SERVER_PORT        $server_port;
scgi_param  SERVER_NAME        $server_name;