How to retrieve package source from arbitrary repository

[Malte Forkel <malte.forkel@berlin.de>]

Hi,

In order to rebuild or patch a package, I sometimes have to download its
source from a repository which is not on my APT sources list. I'm
looking for a tool to make retrieving the source as easy as possible.

Until now, I have been using dget (from the devscripts package). With
the URI of a .dsc file as its argument, dget will download all source
files of a package (typically, .dsc, .diff.gz., and .orig.tar.gz).

In order to use dget, I have to determine the .dsc file's URI, either by
browsing the repository contents or by looking at the repository's
control files. This task I would like to automate.

Is there a tool that will determine the .dsc file's URI given the
repository's base URI, the distribution name, and the package name? I
guess it would have to download and parse the Source control files,
ideally caching them for later use.

Thanks in advance,
Malte