  Let $K$ be a non-discrete non-Archimedean local field with residue
characteristic $p$. Let $G$ be the group of $K$ rational points of a algebraic
connected reductive group defined over $K$. In this article we compute the
extensions between characters of affine pro-$p$ Iwahori--Hecke algebra
$\mathcal{H}^{\text{aff}}$ over an algebraically closed field $R$ of
characteristic $p$. In rank one case we deduce the relation between the blocks
and $L$-packets.
