CHECK(ofpraw_decode_partial(&raw, &hello, sizeof hello), 0);
CHECK(raw, OFPRAW_OFPT_HELLO);
CHECK(ntohs(hello.length), sizeof hello);
CHECK(ofpraw_decode_partial(&raw, &hello, sizeof hello), 0);
CHECK(raw, OFPRAW_OFPT_HELLO);
CHECK(ntohs(hello.length), sizeof hello);