Add configurability (and documentation) to environment model

README.md

@@ -84,6 +84,23 @@ socket << "GET / HTTP/1.1\r\nHost: www.google.com\r\n\r\n"
 socket.gets # => "HTTP/1.1 200 OK\r\n"
 ```
 
+### Environment - patching TCPSocket
+
+```ruby
+require 'proxifier/env'
+ENV['PROXY'] = 'http://10.0.0.44:8888' # How to find the proxy
+ENV['PROXY_FILTER_REGEX'] = '(10\..*|localhost)' # Do not use proxy for connections inside internal net or localhost
+ENV['PROXY_FILTER_LIST'] = '66.211.168.123,207.97.227.239'
+```
+
+Afterwards, any new TCPSocket connections will use the proxy, unless they're excluded either by the specific PROXY_FILTER_LIST or the PROXY_FILTER_REGEX.
+
+PROXY_FILTER_LIST specifies a comma separated list of hostnames or IP addresses (whichever the client code is going to use).
+
+PROXY_FILTER_REGEX is a regular expression, where if the connection hostname (or IP address) matches the regex, connections will be made directly and not through the proxy.
+
+Both PROXY_FILTER_LIST and PROXY_FILTER_REGEX are optional, but only one will be used.
+
 ## Supported Proxies
 
 <table>

lib/proxifier/env.rb

@@ -36,6 +36,12 @@ def initialize_with_proxy(host, port, options_or_local_host = {}, local_port = n
         options = options_if_local_host
       end
 
+      if ENV['PROXY_FILTER_REGEX'].present?
+        options[:no_proxy] = /\A#{ENV['PROXY_FILTER_REGEX']}\z/
+      elsif ENV['PROXY_FILTER_LIST'].present?
+        options[:no_proxy] = ENV['PROXY_FILTER_LIST']
+      end
+
       if options[:proxy] && (proxy = Proxifier::Proxy(options.delete(:proxy), options)) && proxy.proxify?(host)
         initialize_without_proxy(proxy.host, proxy.port, local_host, local_port)
         begin

lib/proxifier/proxy.rb

@@ -8,8 +8,12 @@ class << self
       def proxify?(host, no_proxy = nil)
         return true unless no_proxy
 
-        dont_proxy = no_proxy.split(",")
-        dont_proxy.none? { |h| host =~ /#{h}\Z/ }
+        if no_proxy.is_a?(Regexp)
+          (host =~ no_proxy).nil?
+        else
+          dont_proxy = no_proxy.split(",")
+          dont_proxy.none? { |h| host =~ /#{h}\Z/ }
+        end
       end
     end