method

find_proxy

Ruby latest stable (v2_5_5) - 0 notes - Class: URI::Generic

find_proxy(env=ENV) public

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.

If the optional parameter, env, is specified, it is used instead of ENV.

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.

Show source

# File lib/uri/generic.rb, line 1490
    def find_proxy(env=ENV)
      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/ !~ 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.', uplevel: 1
          end
        end
      else
        proxy_uri = env[name] || env[name.upcase]
      end

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

      if self.hostname
        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]
        return nil unless URI::Generic.use_proxy?(self.hostname, addr, self.port, no_proxy)
      end
      URI.parse(proxy_uri)
    end

find_proxy

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