Crate system_proxy

Expand description

Resolve system proxies.

Simple usage

The default() function returns the default proxy resolver of the operating system, wrapped with a env::EnvProxyResolver which looks at the standard $HTTP_PROXY and friends used by most command line utilities:

let proxy = system_proxy::default();
let client = reqwest::blocking::Client::builder()
    .user_agent(concat!(env!("CARGO_PKG_NAME"), "/", env!("CARGO_PKG_VERSION")))
    .proxy(reqwest::Proxy::custom(move |u| proxy.for_url(u)))
    .build()
    .unwrap();

let response = client.get("https://httpbin.org/status/200").send().unwrap();
println!("Status code: {}", response.status());

Proxy resolvers

A ProxyResolver provides the ProxyResolver::for_url() method which returns the HTTP proxy URL to use for the given URL, Or None if a direct connection should be used.

Advanced usage

This crate also offers direct access to the operating system proxy resolver, via exported modules such as unix. It also offers direct access to a resolver which uses the standard $HTTP_PROXY etc. environment variables, via env::EnvProxyResolver. The corresponding module also exposes the the components of the proxy resolver, namely access to the proxy variables as well as to $NO_PROXY rules, which allows for flexible composition of proxy rules.

Operating system support

In addition to environment variables this crate mainly exposes the default proxy resolver of the underlying operating system.

Linux and other Unix systems

Linux and other related Unix systems such as FreeBSD do not offer a standard system-wide HTTP proxy resolver. Most unix programs use the wide-spread $HTTP_PROXY etc. environment variables.

However these variables suffer from various drawbacks: Applications using these variables cannot dynamically react on changes to the network connection, e.g. disconnecting from a public Wifi and connecting to the company ethernet, each using a different proxy. Instead the application needs to restart to obtain new values for the proxy configuration, which often requires users to restart their entire session to get an updated proxy environment. These applications also lack support for more sophisticated proxy configuration schemes, namely auto-configuration URLs, which are widely used in enterprise environments.

For this reason Gnome at least offers a separate per-user proxy configuration which allows to change the proxy dynamically for all running applications, and adds support for auto-configuration URLs. Most Glib/Gio based applications use this infrastructure.

This crate binds to Gio and uses the Gio proxy resolver to make use of this Gnome-wide proxy configuration.