Re: How to get git-send-email use a proxy?

["Ævar Arnfjörð Bjarmason" <avarab@gmail.com>]

On Fri, Apr 08 2022, Shaoxuan Yuan wrote:

> On Fri, Apr 8, 2022 at 5:53 AM brian m. carlson
> <sandals@crustytoothpaste.net> wrote:
>>
>> On 2022-04-06 at 14:19:43, Shaoxuan Yuan wrote:
>> > Greetings, Git community,
>> >
>> > I'm using git-send-email with Git 2.35.1 under system
>> > 5.4.72-microsoft-standard-WSL2, x86_64 GNU/Linux.
>> >
>> > I am on a system-wide socks5 proxy. Although I set the global
>> > .gitconfig to use the socks5 proxy trying to send emails, the
>> > connection to the SMTP server seems does not go through the proxy at
>> > all.
>> >
>> > Other git commands do go through the globally set .gitconfig proxy,
>> > git-send-email seems to be an exception.
>>
>> I think you're referring to http.proxy.  That affects only HTTP, HTTPS,
>> and FTP (if we even still support that).  All of those protocols are
>> handled by libcurl, which includes native proxy support.  It doesn't
>> affect other protocols like SSH or SMTP.
>>
>> > So I'm wondering if there needs to be a code change in
>> > 'git-send-email.perl' to run the connection through a proxy, or I just
>> > need to tune the setting to accomplish this?
>>
>> git send-email is written in Perl and doesn't use libcurl, so it doesn't
>> have proxy support.  If there's a particular optional module we could
>> dynamically load to provide proxy support, that's an option we could
>> support if someone wanted to provide a patch.
>>
>> In the mean time, you could also try using some sort of tool, like
>> socat, to bind a local port tunnelling over the proxy to the destination
>> server and then use SMTP over that local port to connect.
>> --
>> brian m. carlson (he/him or they/them)
>> Toronto, Ontario, CA
>
> Thanks, it's pretty informative ;-)

If you want to add a "native" feature to git-send-email.perl (and
provide a patch) it looks from
https://stackoverflow.com/questions/3253360/using-socks5-proxy-with-netsmtp
that doing so isn't too hard.

I.e. Net::SMTP (which we use) just uses standard Perl modules to connect
to the network, and there's other existing modules to ferry any such
connection through a SOCKS proxy: https://metacpan.org/pod/Net::SOCKS &
https://metacpan.org/pod/IO::Socket::Socks (I'm not sure which of these
is a better choice).

So it seems like a rather easy 10-20 line patch (including docs and
boilerplate) where we'd just create our own Git::Net::SMTP class, and
that class in turn would be like Net::SMTP, except its @ISA would first
dispatch to a "new" in a class we own.

We could thus intercept the new() invocation it makes to the socket
class it's picking now, and direct it to a wrapper.

There's probably even an existing CPAN module for "given this class,
screw with its @ISA such that socks support is added", I just haven't
looked.