  We develop a theory for the current-voltage characteristics of diffusive
superconductor-normal metal-superconductor Josephson junctions with resistive
interfaces and the distance between the electrodes smaller than the
superconducting coherence length. The theory allows for a quantitative
analytical and numerical analysis in the whole range of the interface
transparencies and asymmetry. We focus on the regime of large interface
resistance compared to the resistance of the normal region, when the
electron-hole dephasing in the normal region is significant and the finite
length of the junction plays a role. In the limit of strong asymmetry we find
pronounced current structures at the combination subharmonics of
$\Delta+\Delta_g$, where $\Delta_g$ is the proximity minigap in the normal
region, in addition to the subharmonics of the energy gap $2\Delta$ in the
electrodes. In the limit of rather transparent interfaces, our theory recovers
a known formula for the current in a short mesoscopic connector - a convolution
of the current through a single-channel point contact with the transparency
distribution for an asymmetric double-barrier potential.
