sshbuf_poke
ASSERT_INT_EQ(sshbuf_poke(p1, 0, "hello!", 6), 0);
ASSERT_INT_EQ(sshbuf_poke(p1, 4, "hello!", 6), 0);
ASSERT_INT_EQ(sshbuf_poke(p1, 7, "hello!", 6),
ASSERT_INT_EQ(sshbuf_poke(p1, 10, "hello!", 6),
ASSERT_INT_EQ(sshbuf_poke(p1, 1000, "hello!", 6),
int sshbuf_poke(struct sshbuf *buf, size_t offset, void *v, size_t len);