Subject: bug#20402: guix cannot download via an http proxy

From: Joshua Randall <[email-masked]>
Date: Tue, 21 Apr 2015 23:56:02 +0100

Package: guix
Version: 0.8.1

I am attempting to use guix from within a network that does not allow
outbound http connections except via an http proxy. I am using Guile
v2.0.11, which supports http proxies, so my expectation would be that since
I have http_proxy and https_proxy environment variables set, guix would use
the specified proxy for outbound http connections, but instead it appears
to ignore the proxy settings and attempts to contact the http server
directly, which results in a timeout.

For example, when doing a `guix pull` I got the following:
$ guix pull
starting download of `/tmp/guix-file.l1zwZ7' from `
http://git.savannah.gnu.org/cgit/guix.git/snapshot/guix-master.tar.gz'...
ERROR: In procedure connect: Connection timed out
failed to download "/tmp/guix-file.l1zwZ7" from "
http://git.savannah.gnu.org/cgit/guix.git/snapshot/guix-master.tar.gz"
guix pull: error: failed to download up-to-date source, exiting

It appears that Guile has had support for http proxies in the web client
package since v2.0.10, and although guix is using the http-get method from
Guile, it isn't using the open-socket-for-uri method, which is the one that
implements making a proxy connection. Instead, guix seems to have copied
and modified the code from an older version of open-socket-for-uri
into open-connection-for-uri
(
http://git.savannah.gnu.org/cgit/guix.git/tree/guix/build/download.scm?id=v0.8.1#n153)
and uses that instead. I suspect what has happened is that the Guile
version of open-socket-for-uri has added proxy support since the code was
copied into open-connection-for-uri. One fix would be to port over the
changes to open-socket-for-uri that were made in Guile 2.0.10.

However, it appears from the code comment that that the reason
open-connection-for-uri copies the functionality of open-socket-for-uri is
to avoid NSS lookups for symbolic port arguments, and it looks to me that
since version 2.0.7 of Guile, its open-socket-for-uri can be convinced not
to do NSS lookups as long as (uri-port uri) is not #f (see
http://git.savannah.gnu.org/cgit/guile.git/tree/module/web/client.scm?id=v2.0.7#n53
).

Rather than porting the new code from Guile's open-socket-for-uri, it might
make more sense to just call open-socket-for-uri with a uri that always has
a port (i.e. implement the same hard-coding for http and https in the
http-fetch function to make sure that uri has the default port set - I
notice for some reason Guile's string->uri parser does not set the port for
http and https even though it has the default ports for both set in the
code. I suppose one could use the existing post-2.0.7? test to keep calling
open-connection-for-uri for backwards compatibility with old versions of
Guile (which in any case don't have proxy support, so for my use case it
doesn't matter).

I can try to put together a patch that implements this fix, although I
haven't written scheme in quite a while, so someone else may be better
suited for it.

Cheers,

Josh.