Re: `url-retrieve' for https behind proxy: 400 bad request

[<tomas@tuxteam.de>]

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On Tue, Nov 08, 2016 at 09:18:07AM +0300, Andrew Savonichev wrote:
> Hi,
> 
> I use GNU/Emacs behind the http proxy with no user authorization, and
> seems `url-retrieve' does not work correctly with the proxy-server -
> error "400 Bad Request" for any https url.
> 
> Environment variables (http_proxy and https_proxy) are correctly set
> and other tools except the emacs work fine: tried curl and wget.
> 
> I've compared url-retrieve and curl requests to the proxy-server
> and there is a difference:
> curl does CONNECT followed by GET, while url-retrieve use a direct
> GET request.
> 
> curl (works fine):
>   CONNECT www.google.com:443 HTTP/1.1
>   Host: www.google.com:443
>   User-Agent: curl/7.29.0
>   Proxy-Connection: Keep-Alive
> 
>   GET / HTTP/1.1
>   User-Agent: curl/7.29.0
>   Host: www.google.com
>   Accept: */*
> 
> url-retrieve (error 400):
>   GET https://www.google.com/ HTTP/1.1
>   MIME-Version: 1.0
>   Extension: Security/Digest Security/SSL
>   Host: www.google.com
>   Accept-encoding: gzip
>   Accept: */*
>   User-Agent: URL/Emacs

Yeah. This is the usual dance for https over proxy (if the proxy allows
it). Basically, CONNECT tells the proxy to just pass the https stream
along, untouched.

> I've tried it with the GNU/Emacs 25.1 and 24.3.1 releases (with -Q
> command line option).

Seems url-retrieve hasn't implemented *that* wart yet. Consider
reporting a bug (Disclaimer: I haven't tested with latest Emacs).

> Is it a bug? Any ideas  would be appreciated.

I think so (but see disclaimer above). Or perhaps a missing feature.

Regards
- -- tomás
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