Bug#283718: apt does not (always) honor the no_proxy environment variable

[Mario Lorenz <ml@vdazone.org>]

Package: apt
Version: 0.5.27

Despite previous assertions to the contrary
(see eg. #118780), the no_proxy environment variable is not
always properly honored.

In my particular case, I have a FTP URL of a local mirror
in sources.list, and a http://hostname:port style URL in
both ftp_proxy and http_proxy, and the hostname of the local mirror
in no_proxy.

Looking into the source, in methods/ftp.cc pretty early in main(),
ftp sees the http://-style proxy address, and hands over the
request to the http method, explicitly unsetting the no_proxy
environment variable along the way. http will then try to access 
the server via the proxy, in violation of the no_proxy setting.

IMHO the "check-for-no_proxy" logic needs to be moved to the
beginning of main(), so we can stay within ftp if it is determined
that ftp_proxy does not apply due to no_proxy restrictions.

apt.conf configuration not to use the proxy is also ignored, which,
albeit documented to work this way, could be argued to be wrong.
The proxy environment variables apply to several programs, hence
apt.conf is more specific and should supersede (or at least provide
the option to supersede) the environment variables.


-- 
Mario Lorenz                            Internet:    <ml@vdazone.org>
                                        Ham Radio:   DL5MLO@OK0PKL.#BOH.CZE.EU
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