v3, 2 partshttp: few fixes for the proxy configuration handling

Hello,

this is few patches, which fixes regressions in the proxy handling.

Changes since v2:
 - fix grammar (thanks to Ævar)
 - add new patch which fixes the silent ignoring of proxy missconfiguration

Sergey Ryazanov (2):
  http: honor empty http.proxy option to bypass proxy
  http: fix the silent ignoring of proxy misconfiguraion

 http.c | 13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

Earlier, the whole http.proxy option string was passed to curl without any preprocessing so curl could complain about the invalid proxy configuration.

After the commit 372370f167 ("http: use credential API to handle proxy authentication", 2016-01-26), if the user specified an invalid HTTP proxy option in the configuration, then the option parsing is silently fails and NULL will be passed to curl as a proxy. This forces curl to fall back to detecting the proxy configuration from the environment, causing the http.proxy option ignoring.

Fix this issue by checking the proxy option parsing result. If parsing failed then print error message and die. Such behaviour allows user to quickly figure the proxy misconfiguration and correct it.

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
---

Changes since v2:
  - new patch

 http.c | 3 +++
 1 file changed, 3 insertions(+)

On Tue, Apr 11, 2017 at 08:17:50PM +0300, Sergey Ryazanov wrote:

s/is silently/silently/

Two minor grammos:

s/error/an error/; s/user/the user/;

In the earlier discussion you mentioned a warning, but I like this die() much better.

Both patches look very clean, and nicely explained. Thanks for working on this.

-Peff

On Tue, Apr 11, 2017 at 8:37 PM, Jeff King <peff@peff.net> wrote:

Thank you. Just sent a series with suggested grammar fixes as v4.

I actually meant "die" but by some reason I typed "warning" :-/

Peff, I would like to thank you and Ævar for your great help!

Curl distinguishes between an empty proxy address and a NULL proxy address. In the first case it completely disables proxy usage, but if the proxy address option is NULL then curl attempts to determine the proxy address from the http_proxy environment variable.

According to the documentation, if the http.proxy option is set to an empty string, git should bypass proxy and connect to the server directly:

    export http_proxy=http://network-proxy/
    cd ~/foobar-project
    git config remote.origin.proxy ""
    git fetch

Previously, proxy host was configured by one line:

    curl_easy_setopt(result, CURLOPT_PROXY, curl_http_proxy);

Commit 372370f167 ("http: use credential API to handle proxy authentication", 2016-01-26) parses the proxy option, then extracts the proxy host address and updates the curl configuration, making the previous call a noop:

    credential_from_url(&proxy_auth, curl_http_proxy);
    curl_easy_setopt(result, CURLOPT_PROXY, proxy_auth.host);

But if the proxy option is empty then the proxy host field becomes NULL. This forces curl to fall back to detecting the proxy configuration from the environment, causing the http.proxy option to not work anymore.

Fix this issue by explicitly handling http.proxy being set the empty string. This also makes the code a bit more clear and should help us avoid such regressions in the future.

Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
---

Changes since v1:
 - explicitly handle this case instead of mangling the common code

Changes since v2:
 - fix grammar (thanks to Ævar)

 http.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)