Method: URI::Generic#find_proxy

Defined in:

lib/uri/generic.rb

#find_proxy ⇒ Object

returns a proxy URI. The proxy URI is obtained from environment variables such as http_proxy, ftp_proxy, no_proxy, etc. If there is no proper proxy, nil is returned.

Note that capitalized variables (HTTP_PROXY, FTP_PROXY, NO_PROXY, etc.) are examined too.

But http_proxy and HTTP_PROXY is treated specially under CGI environment. It’s because HTTP_PROXY may be set by Proxy: header. So HTTP_PROXY is not used. http_proxy is not used too if the variable is case insensitive. CGI_HTTP_PROXY can be used instead.

Raises:

• (BadURIError)

# File 'lib/uri/generic.rb', line 1613

def find_proxy
  raise BadURIError, "relative URI: #{self}" if self.relative?
  name = self.scheme.downcase + '_proxy'
  proxy_uri = nil
  if name == 'http_proxy' && ENV.include?('REQUEST_METHOD') # CGI?
    # HTTP_PROXY conflicts with *_proxy for proxy settings and
    # HTTP_* for header information in CGI.
    # So it should be careful to use it.
    pairs = ENV.reject {|k, v| /\Ahttp_proxy\z/i !~ k }
    case pairs.length
    when 0 # no proxy setting anyway.
      proxy_uri = nil
    when 1
      k, _ = pairs.shift
      if k == 'http_proxy' && ENV[k.upcase] == nil
        # http_proxy is safe to use because ENV is case sensitive.
        proxy_uri = ENV[name]
      else
        proxy_uri = nil
      end
    else # http_proxy is safe to use because ENV is case sensitive.
      proxy_uri = ENV.to_hash[name]
    end
    if !proxy_uri
      # Use CGI_HTTP_PROXY.  cf. libwww-perl.
      proxy_uri = ENV["CGI_#{name.upcase}"]
    end
  elsif name == 'http_proxy'
    unless proxy_uri = ENV[name]
      if proxy_uri = ENV[name.upcase]
        warn 'The environment variable HTTP_PROXY is discouraged.  Use http_proxy.'
      end
    end
  else
    proxy_uri = ENV[name] || ENV[name.upcase]
  end

  if proxy_uri.nil? || proxy_uri.empty?
    return nil
  end

  if self.hostname
    require 'socket'
    begin
      addr = IPSocket.getaddress(self.hostname)
      return nil if /\A127\.|\A::1\z/ =~ addr
    rescue SocketError
    end
  end

  name = 'no_proxy'
  if no_proxy = ENV[name] || ENV[name.upcase]
    no_proxy.scan(/([^:,]*)(?::(\d+))?/) {|host, port|
      if /(\A|\.)#{Regexp.quote host}\z/i =~ self.host &&
        (!port || self.port == port.to_i)
        return nil
      end
    }
  end
  URI.parse(proxy_uri)
end