Re: [Edbrowse-dev] A couple of feature requests

[Chris Brannon <chris@the-brannons.com>]

Karl Dahlke <eklhad@comcast.net> writes:

> Can you specify proxy exceptions within curl?

Nope.
This will be a fun can of worms.
In corporate settings, the proxy you use may depends on the
URL you're trying to fetch.
See http://en.wikipedia.org/wiki/Proxy_auto-config
It's going to be more complicated than just supporting exceptions.
Here's a long quote from that article:

<quote>
Computer {operating systems} (e.g., {Microsoft Windows}
{Mac OS X}
{Linux}) require a number of settings to communicate over the
{Internet}. These settings are typically obtained from an {Internet
Service Provider} (ISP). Either anonymous (proxy to use a {proxy
server}) or real settings may be used to establish a network connection.

The PAC File{edit}

The Proxy auto-config file format was originally designed by {Netscape}
in 1996 for the {Netscape Navigator 2.0}^{[1]} and is a
{text file} that defines at least one JavaScript function,
FindProxyForURL(url, host), with two arguments:
url is the URL of the object and host is the host-name derived from that URL.
By convention, the PAC file is normally named proxy.pac.
The {WPAD standard} uses wpad.dat.

To use it, a PAC file is published to a {HTTP server},
and client user agents are instructed to use it,
either by entering the URL in the proxy connection settings of the browser or
through the use of the WPAD protocol.

A very simple example of a PAC file is:

function FindProxyForURL(url, host)
{
	return "PROXY proxy.example.com:8080; DIRECT";
}


This function instructs the browser to retrieve all pages through the proxy on
{port} 8080 of the server proxy.example.com.
Should this proxy fail to respond, the browser contacts the Web-site directly,
without using a proxy. The latter may fail if {firewalls},
or other intermediary network devices,
reject requests from sources other than the proxy;
a common configuration in corporate networks.

A more complicated example demonstrates some available JavaScript functions to
be used in the FindProxyForURL function:

function FindProxyForURL(url, host) {
	// our local URLs from the domains below example.com don't need a proxy:
	if (shExpMatch(host, "*.example.com"))
	{
		return "DIRECT";
	}

	// URLs within this network are accessed through
	// port 8080 on fastproxy.example.com:
	if (isInNet(host, "10.0.0.0", "255.255.248.0"))
	{
		return "PROXY fastproxy.example.com:8080";
	}

	// All other requests go through port 8080 of proxy.example.com.
	// should that fail to respond, go directly to the WWW:
	return "PROXY proxy.example.com:8080; DIRECT";
}
</quote>

Yeah, I had to deal with this stuff when I worked for $big_company.  For
all intents and purposes, edbrowse was completely unusable on that
network.

-- Chris