kex_buf2prop
if ((r = kex_buf2prop(kex->my, NULL, &prop)) != 0)
if ((r = kex_buf2prop(kex->my, NULL, &my)) != 0)
if ((r = kex_buf2prop(kex->peer, &first_kex_follows, &peer)) != 0)
int kex_buf2prop(struct sshbuf *, int *, char ***);
if ((r = kex_buf2prop(ssh->kex->my, NULL, &proposal)) != 0)