queue_reply
ret = queue_reply(&staging_q, &hdr, sizeof(hdr));
ret = queue_reply(&staging_q, path, path_len);
ret = queue_reply(&staging_q, token_caller, tok_len);
rc = queue_reply(&staging_q, &req->msg, sizeof(req->msg));
rc = queue_reply(&staging_q, req->body, req->msg.len);
rc = queue_reply(&u->read_buffers, &msg, sizeof(msg.hdr) + msg.hdr.len);