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URI Module open Method OpenURI Module check_options Method scan_open_optional_arguments Method open_uri Method open_loop Method redirectable? Method open_http Method HTTPError Class initialize Method HTTPRedirect Class initialize Method Buffer Class initialize Method << Method io Method Meta Module init Method meta_setup_encoding Method meta_add_field2 Method meta_add_field Method last_modified Method content_type_parse Method content_type Method charset Method content_encoding Method OpenRead Module open Method read Method URI Module HTTP Class buffer_open Method FTP Class buffer_open Method

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	# frozen_string_literal: true
	require 'uri'
	require 'stringio'
	require 'time'

	module URI
	# Allows the opening of various resources including URIs.
	#
	# If the first argument responds to the 'open' method, 'open' is called on
	# it with the rest of the arguments.
	#
	# If the first argument is a string that begins with <code>(protocol)://</code>, it is parsed by
	# URI.parse. If the parsed object responds to the 'open' method,
	# 'open' is called on it with the rest of the arguments.
	#
	# Otherwise, Kernel#open is called.
	#
	# OpenURI::OpenRead#open provides URI::HTTP#open, URI::HTTPS#open and
	# URI::FTP#open, Kernel#open.
	#
	# We can accept URIs and strings that begin with http://, https:// and
	# ftp://. In these cases, the opened file object is extended by OpenURI::Meta.
	def self.open(name, *rest, &block)
	if name.respond_to?(:open)
	name.open(*rest, &block)
	elsif name.respond_to?(:to_str) &&
	%r{\A[A-Za-z][A-Za-z0-9+\-\.]*://} =~ name &&
	(uri = URI.parse(name)).respond_to?(:open)
	uri.open(*rest, &block)
	else
	super
	end
	end
	end

	# OpenURI is an easy-to-use wrapper for Net::HTTP, Net::HTTPS and Net::FTP.
	#
	# == Example
	#
	# It is possible to open an http, https or ftp URL as though it were a file:
	#
	# URI.open("http://www.ruby-lang.org/") {\|f\|
	# f.each_line {\|line\| p line}
	# }
	#
	# The opened file has several getter methods for its meta-information, as
	# follows, since it is extended by OpenURI::Meta.
	#
	# URI.open("http://www.ruby-lang.org/en") {\|f\|
	# f.each_line {\|line\| p line}
	# p f.base_uri # <URI::HTTP:0x40e6ef2 URL:http://www.ruby-lang.org/en/>
	# p f.content_type # "text/html"
	# p f.charset # "iso-8859-1"
	# p f.content_encoding # []
	# p f.last_modified # Thu Dec 05 02:45:02 UTC 2002
	# }
	#
	# Additional header fields can be specified by an optional hash argument.
	#
	# URI.open("http://www.ruby-lang.org/en/",
	# "User-Agent" => "Ruby/#{RUBY_VERSION}",
	# "From" => "foo@bar.invalid",
	# "Referer" => "http://www.ruby-lang.org/") {\|f\|
	# # ...
	# }
	#
	# The environment variables such as http_proxy, https_proxy and ftp_proxy
	# are in effect by default. Here we disable proxy:
	#
	# URI.open("http://www.ruby-lang.org/en/", :proxy => nil) {\|f\|
	# # ...
	# }
	#
	# See OpenURI::OpenRead.open and URI.open for more on available options.
	#
	# URI objects can be opened in a similar way.
	#
	# uri = URI.parse("http://www.ruby-lang.org/en/")
	# uri.open {\|f\|
	# # ...
	# }
	#
	# URI objects can be read directly. The returned string is also extended by
	# OpenURI::Meta.
	#
	# str = uri.read
	# p str.base_uri
	#
	# Author:: Tanaka Akira <akr@m17n.org>

	module OpenURI
	Options = {
	:proxy => true,
	:proxy_http_basic_authentication => true,
	:progress_proc => true,
	:content_length_proc => true,
	:http_basic_authentication => true,
	:read_timeout => true,
	:open_timeout => true,
	:ssl_ca_cert => nil,
	:ssl_verify_mode => nil,
	:ftp_active_mode => false,
	:redirect => true,
	:encoding => nil,
	}

	def OpenURI.check_options(options) # :nodoc:
	options.each {\|k, v\|
	next unless Symbol === k
	unless Options.include? k
	raise ArgumentError, "unrecognized option: #{k}"
	end
	}
	end

	def OpenURI.scan_open_optional_arguments(*rest) # :nodoc:
	if !rest.empty? && (String === rest.first \|\| Integer === rest.first)
	mode = rest.shift
	if !rest.empty? && Integer === rest.first
	perm = rest.shift
	end
	end
	return mode, perm, rest
	end

	def OpenURI.open_uri(name, *rest) # :nodoc:
	uri = URI::Generic === name ? name : URI.parse(name)
	mode, _, rest = OpenURI.scan_open_optional_arguments(*rest)
	options = rest.shift if !rest.empty? && Hash === rest.first
	raise ArgumentError.new("extra arguments") if !rest.empty?
	options \|\|= {}
	OpenURI.check_options(options)

	if /\Arb?(?:\Z\|:([^:]+))/ =~ mode
	encoding, = $1,Encoding.find($1) if $1
	mode = nil
	end
	if options.has_key? :encoding
	if !encoding.nil?
	raise ArgumentError, "encoding specified twice"
	end
	encoding = Encoding.find(options[:encoding])
	end

	unless mode == nil \|\|
	mode == 'r' \|\| mode == 'rb' \|\|
	mode == File::RDONLY
	raise ArgumentError.new("invalid access mode #{mode} (#{uri.class} resource is read only.)")
	end

	io = open_loop(uri, options)
	io.set_encoding(encoding) if encoding
	if block_given?
	begin
	yield io
	ensure
	if io.respond_to? :close!
	io.close! # Tempfile
	else
	io.close if !io.closed?
	end
	end
	else
	io
	end
	end

	def OpenURI.open_loop(uri, options) # :nodoc:
	proxy_opts = []
	proxy_opts << :proxy_http_basic_authentication if options.include? :proxy_http_basic_authentication
	proxy_opts << :proxy if options.include? :proxy
	proxy_opts.compact!
	if 1 < proxy_opts.length
	raise ArgumentError, "multiple proxy options specified"
	end
	case proxy_opts.first
	when :proxy_http_basic_authentication
	opt_proxy, proxy_user, proxy_pass = options.fetch(:proxy_http_basic_authentication)
	proxy_user = proxy_user.to_str
	proxy_pass = proxy_pass.to_str
	if opt_proxy == true
	raise ArgumentError.new("Invalid authenticated proxy option: #{options[:proxy_http_basic_authentication].inspect}")
	end
	when :proxy
	opt_proxy = options.fetch(:proxy)
	proxy_user = nil
	proxy_pass = nil
	when nil
	opt_proxy = true
	proxy_user = nil
	proxy_pass = nil
	end
	case opt_proxy
	when true
	find_proxy = lambda {\|u\| pxy = u.find_proxy; pxy ? [pxy, nil, nil] : nil}
	when nil, false
	find_proxy = lambda {\|u\| nil}
	when String
	opt_proxy = URI.parse(opt_proxy)
	find_proxy = lambda {\|u\| [opt_proxy, proxy_user, proxy_pass]}
	when URI::Generic
	find_proxy = lambda {\|u\| [opt_proxy, proxy_user, proxy_pass]}
	else
	raise ArgumentError.new("Invalid proxy option: #{opt_proxy}")
	end

	uri_set = {}
	buf = nil
	while true
	redirect = catch(:open_uri_redirect) {
	buf = Buffer.new
	uri.buffer_open(buf, find_proxy.call(uri), options)
	nil
	}
	if redirect
	if redirect.relative?
	# Although it violates RFC2616, Location: field may have relative
	# URI. It is converted to absolute URI using uri as a base URI.
	redirect = uri + redirect
	end
	if !options.fetch(:redirect, true)
	raise HTTPRedirect.new(buf.io.status.join(' '), buf.io, redirect)
	end
	unless OpenURI.redirectable?(uri, redirect)
	raise "redirection forbidden: #{uri} -> #{redirect}"
	end
	if options.include? :http_basic_authentication
	# send authentication only for the URI directly specified.
	options = options.dup
	options.delete :http_basic_authentication
	end
	uri = redirect
	raise "HTTP redirection loop: #{uri}" if uri_set.include? uri.to_s
	uri_set[uri.to_s] = true
	else
	break
	end
	end
	io = buf.io
	io.base_uri = uri
	io
	end

	def OpenURI.redirectable?(uri1, uri2) # :nodoc:
	# This test is intended to forbid a redirection from http://... to
	# file:///etc/passwd, file:///dev/zero, etc. CVE-2011-1521
	# https to http redirect is also forbidden intentionally.
	# It avoids sending secure cookie or referer by non-secure HTTP protocol.
	# (RFC 2109 4.3.1, RFC 2965 3.3, RFC 2616 15.1.3)
	# However this is ad hoc. It should be extensible/configurable.
	uri1.scheme.downcase == uri2.scheme.downcase \|\|
	(/\A(?:http\|ftp)\z/i =~ uri1.scheme && /\A(?:https?\|ftp)\z/i =~ uri2.scheme)
	end

	def OpenURI.open_http(buf, target, proxy, options) # :nodoc:
	if proxy
	proxy_uri, proxy_user, proxy_pass = proxy
	raise "Non-HTTP proxy URI: #{proxy_uri}" if proxy_uri.class != URI::HTTP
	end

	if target.userinfo
	raise ArgumentError, "userinfo not supported. [RFC3986]"
	end

	header = {}
	options.each {\|k, v\| header[k] = v if String === k }

	require 'net/http'
	klass = Net::HTTP
	if URI::HTTP === target
	# HTTP or HTTPS
	if proxy
	unless proxy_user && proxy_pass
	proxy_user, proxy_pass = proxy_uri.userinfo.split(':') if proxy_uri.userinfo
	end
	if proxy_user && proxy_pass
	klass = Net::HTTP::Proxy(proxy_uri.hostname, proxy_uri.port, proxy_user, proxy_pass)
	else
	klass = Net::HTTP::Proxy(proxy_uri.hostname, proxy_uri.port)
	end
	end
	target_host = target.hostname
	target_port = target.port
	request_uri = target.request_uri
	else
	# FTP over HTTP proxy
	target_host = proxy_uri.hostname
	target_port = proxy_uri.port
	request_uri = target.to_s
	if proxy_user && proxy_pass
	header["Proxy-Authorization"] =
	'Basic ' + ["#{proxy_user}:#{proxy_pass}"].pack('m0')
	end
	end

	http = proxy ? klass.new(target_host, target_port) : klass.new(target_host, target_port, nil)
	if target.class == URI::HTTPS
	require 'net/https'
	http.use_ssl = true
	http.verify_mode = options[:ssl_verify_mode] \|\| OpenSSL::SSL::VERIFY_PEER
	store = OpenSSL::X509::Store.new
	if options[:ssl_ca_cert]
	Array(options[:ssl_ca_cert]).each do \|cert\|
	if File.directory? cert
	store.add_path cert
	else
	store.add_file cert
	end
	end
	else
	store.set_default_paths
	end
	http.cert_store = store
	end
	if options.include? :read_timeout
	http.read_timeout = options[:read_timeout]
	end
	if options.include? :open_timeout
	http.open_timeout = options[:open_timeout]
	end

	resp = nil
	http.start {
	req = Net::HTTP::Get.new(request_uri, header)
	if options.include? :http_basic_authentication
	user, pass = options[:http_basic_authentication]
	req.basic_auth user, pass
	end
	http.request(req) {\|response\|
	resp = response
	if options[:content_length_proc] && Net::HTTPSuccess === resp
	if resp.key?('Content-Length')
	options[:content_length_proc].call(resp['Content-Length'].to_i)
	else
	options[:content_length_proc].call(nil)
	end
	end
	resp.read_body {\|str\|
	buf << str
	if options[:progress_proc] && Net::HTTPSuccess === resp
	options[:progress_proc].call(buf.size)
	end
	str.clear
	}
	}
	}
	io = buf.io
	io.rewind
	io.status = [resp.code, resp.message]
	resp.each_name {\|name\| buf.io.meta_add_field2 name, resp.get_fields(name) }
	case resp
	when Net::HTTPSuccess
	when Net::HTTPMovedPermanently, # 301
	Net::HTTPFound, # 302
	Net::HTTPSeeOther, # 303
	Net::HTTPTemporaryRedirect # 307
	begin
	loc_uri = URI.parse(resp['location'])
	rescue URI::InvalidURIError
	raise OpenURI::HTTPError.new(io.status.join(' ') + ' (Invalid Location URI)', io)
	end
	throw :open_uri_redirect, loc_uri
	else
	raise OpenURI::HTTPError.new(io.status.join(' '), io)
	end
	end

	class HTTPError < StandardError
	def initialize(message, io)
	super(message)
	@io = io
	end
	attr_reader :io
	end

	# Raised on redirection,
	# only occurs when +redirect+ option for HTTP is +false+.
	class HTTPRedirect < HTTPError
	def initialize(message, io, uri)
	super(message, io)
	@uri = uri
	end
	attr_reader :uri
	end

	class Buffer # :nodoc: all
	def initialize
	@io = StringIO.new
	@size = 0
	end
	attr_reader :size

	StringMax = 10240
	def <<(str)
	@io << str
	@size += str.length
	if StringIO === @io && StringMax < @size
	require 'tempfile'
	io = Tempfile.new('open-uri')
	io.binmode
	Meta.init io, @io if Meta === @io
	io << @io.string
	@io = io
	end
	end

	def io
	Meta.init @io unless Meta === @io
	@io
	end
	end

	# Mixin for holding meta-information.
	module Meta
	def Meta.init(obj, src=nil) # :nodoc:
	obj.extend Meta
	obj.instance_eval {
	@base_uri = nil
	@meta = {} # name to string. legacy.
	@metas = {} # name to array of strings.
	}
	if src
	obj.status = src.status
	obj.base_uri = src.base_uri
	src.metas.each {\|name, values\|
	obj.meta_add_field2(name, values)
	}
	end
	end

	# returns an Array that consists of status code and message.
	attr_accessor :status

	# returns a URI that is the base of relative URIs in the data.
	# It may differ from the URI supplied by a user due to redirection.
	attr_accessor :base_uri

	# returns a Hash that represents header fields.
	# The Hash keys are downcased for canonicalization.
	# The Hash values are a field body.
	# If there are multiple field with same field name,
	# the field values are concatenated with a comma.
	attr_reader :meta

	# returns a Hash that represents header fields.
	# The Hash keys are downcased for canonicalization.
	# The Hash value are an array of field values.
	attr_reader :metas

	def meta_setup_encoding # :nodoc:
	charset = self.charset
	enc = nil
	if charset
	begin
	enc = Encoding.find(charset)
	rescue ArgumentError
	end
	end
	enc = Encoding::ASCII_8BIT unless enc
	if self.respond_to? :force_encoding
	self.force_encoding(enc)
	elsif self.respond_to? :string
	self.string.force_encoding(enc)
	else # Tempfile
	self.set_encoding enc
	end
	end

	def meta_add_field2(name, values) # :nodoc:
	name = name.downcase
	@metas[name] = values
	@meta[name] = values.join(', ')
	meta_setup_encoding if name == 'content-type'
	end

	def meta_add_field(name, value) # :nodoc:
	meta_add_field2(name, [value])
	end

	# returns a Time that represents the Last-Modified field.
	def last_modified
	if vs = @metas['last-modified']
	v = vs.join(', ')
	Time.httpdate(v)
	else
	nil
	end
	end

	# :stopdoc:
	RE_LWS = /[\r\n\t ]+/n
	RE_TOKEN = %r{[^\x00- ()<>@,;:\\"/\[\]?={}\x7f]+}n
	RE_QUOTED_STRING = %r{"(?:[\r\n\t !#-\[\]-~\x80-\xff]\|\\[\x00-\x7f])*"}n
	RE_PARAMETERS = %r{(?:;#{RE_LWS}?#{RE_TOKEN}#{RE_LWS}?=#{RE_LWS}?(?:#{RE_TOKEN}\|#{RE_QUOTED_STRING})#{RE_LWS}?)*}n
	# :startdoc:

	def content_type_parse # :nodoc:
	vs = @metas['content-type']
	# The last (?:;#{RE_LWS}?)? matches extra ";" which violates RFC2045.
	if vs && %r{\A#{RE_LWS}?(#{RE_TOKEN})#{RE_LWS}?/(#{RE_TOKEN})#{RE_LWS}?(#{RE_PARAMETERS})(?:;#{RE_LWS}?)?\z}no =~ vs.join(', ')
	type = $1.downcase
	subtype = $2.downcase
	parameters = []
	$3.scan(/;#{RE_LWS}?(#{RE_TOKEN})#{RE_LWS}?=#{RE_LWS}?(?:(#{RE_TOKEN})\|(#{RE_QUOTED_STRING}))/no) {\|att, val, qval\|
	if qval
	val = qval[1...-1].gsub(/[\r\n\t !#-\[\]-~\x80-\xff]+\|(\\[\x00-\x7f])/n) { $1 ? $1[1,1] : $& }
	end
	parameters << [att.downcase, val]
	}
	["#{type}/#{subtype}", *parameters]
	else
	nil
	end
	end

	# returns "type/subtype" which is MIME Content-Type.
	# It is downcased for canonicalization.
	# Content-Type parameters are stripped.
	def content_type
	type, *_ = content_type_parse
	type \|\| 'application/octet-stream'
	end

	# returns a charset parameter in Content-Type field.
	# It is downcased for canonicalization.
	#
	# If charset parameter is not given but a block is given,
	# the block is called and its result is returned.
	# It can be used to guess charset.
	#
	# If charset parameter and block is not given,
	# nil is returned except text type.
	# In that case, "utf-8" is returned as defined by RFC6838 4.2.1
	def charset
	type, *parameters = content_type_parse
	if pair = parameters.assoc('charset')
	pair.last.downcase
	elsif block_given?
	yield
	elsif type && %r{\Atext/} =~ type
	"utf-8" # RFC6838 4.2.1
	else
	nil
	end
	end

	# Returns a list of encodings in Content-Encoding field as an array of
	# strings.
	#
	# The encodings are downcased for canonicalization.
	def content_encoding
	vs = @metas['content-encoding']
	if vs && %r{\A#{RE_LWS}?#{RE_TOKEN}#{RE_LWS}?(?:,#{RE_LWS}?#{RE_TOKEN}#{RE_LWS}?)*}o =~ (v = vs.join(', '))
	v.scan(RE_TOKEN).map {\|content_coding\| content_coding.downcase}
	else
	[]
	end
	end
	end

	# Mixin for HTTP and FTP URIs.
	module OpenRead
	# OpenURI::OpenRead#open provides `open' for URI::HTTP and URI::FTP.
	#
	# OpenURI::OpenRead#open takes optional 3 arguments as:
	#
	# OpenURI::OpenRead#open([mode [, perm]] [, options]) [{\|io\| ... }]
	#
	# OpenURI::OpenRead#open returns an IO-like object if block is not given.
	# Otherwise it yields the IO object and return the value of the block.
	# The IO object is extended with OpenURI::Meta.
	#
	# +mode+ and +perm+ are the same as Kernel#open.
	#
	# However, +mode+ must be read mode because OpenURI::OpenRead#open doesn't
	# support write mode (yet).
	# Also +perm+ is ignored because it is meaningful only for file creation.
	#
	# +options+ must be a hash.
	#
	# Each option with a string key specifies an extra header field for HTTP.
	# I.e., it is ignored for FTP without HTTP proxy.
	#
	# The hash may include other options, where keys are symbols:
	#
	# [:proxy]
	# Synopsis:
	# :proxy => "http://proxy.foo.com:8000/"
	# :proxy => URI.parse("http://proxy.foo.com:8000/")
	# :proxy => true
	# :proxy => false
	# :proxy => nil
	#
	# If :proxy option is specified, the value should be String, URI,
	# boolean or nil.
	#
	# When String or URI is given, it is treated as proxy URI.
	#
	# When true is given or the option itself is not specified,
	# environment variable `scheme_proxy' is examined.
	# `scheme' is replaced by `http', `https' or `ftp'.
	#
	# When false or nil is given, the environment variables are ignored and
	# connection will be made to a server directly.
	#
	# [:proxy_http_basic_authentication]
	# Synopsis:
	# :proxy_http_basic_authentication =>
	# ["http://proxy.foo.com:8000/", "proxy-user", "proxy-password"]
	# :proxy_http_basic_authentication =>
	# [URI.parse("http://proxy.foo.com:8000/"),
	# "proxy-user", "proxy-password"]
	#
	# If :proxy option is specified, the value should be an Array with 3
	# elements. It should contain a proxy URI, a proxy user name and a proxy
	# password. The proxy URI should be a String, an URI or nil. The proxy
	# user name and password should be a String.
	#
	# If nil is given for the proxy URI, this option is just ignored.
	#
	# If :proxy and :proxy_http_basic_authentication is specified,
	# ArgumentError is raised.
	#
	# [:http_basic_authentication]
	# Synopsis:
	# :http_basic_authentication=>[user, password]
	#
	# If :http_basic_authentication is specified,
	# the value should be an array which contains 2 strings:
	# username and password.
	# It is used for HTTP Basic authentication defined by RFC 2617.
	#
	# [:content_length_proc]
	# Synopsis:
	# :content_length_proc => lambda {\|content_length\| ... }
	#
	# If :content_length_proc option is specified, the option value procedure
	# is called before actual transfer is started.
	# It takes one argument, which is expected content length in bytes.
	#
	# If two or more transfers are performed by HTTP redirection, the
	# procedure is called only once for the last transfer.
	#
	# When expected content length is unknown, the procedure is called with
	# nil. This happens when the HTTP response has no Content-Length header.
	#
	# [:progress_proc]
	# Synopsis:
	# :progress_proc => lambda {\|size\| ...}
	#
	# If :progress_proc option is specified, the proc is called with one
	# argument each time when `open' gets content fragment from network.
	# The argument +size+ is the accumulated transferred size in bytes.
	#
	# If two or more transfer is done by HTTP redirection, the procedure
	# is called only one for a last transfer.
	#
	# :progress_proc and :content_length_proc are intended to be used for
	# progress bar.
	# For example, it can be implemented as follows using Ruby/ProgressBar.
	#
	# pbar = nil
	# open("http://...",
	# :content_length_proc => lambda {\|t\|
	# if t && 0 < t
	# pbar = ProgressBar.new("...", t)
	# pbar.file_transfer_mode
	# end
	# },
	# :progress_proc => lambda {\|s\|
	# pbar.set s if pbar
	# }) {\|f\| ... }
	#
	# [:read_timeout]
	# Synopsis:
	# :read_timeout=>nil (no timeout)
	# :read_timeout=>10 (10 second)
	#
	# :read_timeout option specifies a timeout of read for http connections.
	#
	# [:open_timeout]
	# Synopsis:
	# :open_timeout=>nil (no timeout)
	# :open_timeout=>10 (10 second)
	#
	# :open_timeout option specifies a timeout of open for http connections.
	#
	# [:ssl_ca_cert]
	# Synopsis:
	# :ssl_ca_cert=>filename or an Array of filenames
	#
	# :ssl_ca_cert is used to specify CA certificate for SSL.
	# If it is given, default certificates are not used.
	#
	# [:ssl_verify_mode]
	# Synopsis:
	# :ssl_verify_mode=>mode
	#
	# :ssl_verify_mode is used to specify openssl verify mode.
	#
	# [:ftp_active_mode]
	# Synopsis:
	# :ftp_active_mode=>bool
	#
	# <tt>:ftp_active_mode => true</tt> is used to make ftp active mode.
	# Ruby 1.9 uses passive mode by default.
	# Note that the active mode is default in Ruby 1.8 or prior.
	#
	# [:redirect]
	# Synopsis:
	# :redirect=>bool
	#
	# +:redirect+ is true by default. <tt>:redirect => false</tt> is used to
	# disable all HTTP redirects.
	#
	# OpenURI::HTTPRedirect exception raised on redirection.
	# Using +true+ also means that redirections between http and ftp are
	# permitted.
	#
	def open(*rest, &block)
	OpenURI.open_uri(self, *rest, &block)
	end

	# OpenURI::OpenRead#read([ options ]) reads a content referenced by self and
	# returns the content as string.
	# The string is extended with OpenURI::Meta.
	# The argument +options+ is same as OpenURI::OpenRead#open.
	def read(options={})
	self.open(options) {\|f\|
	str = f.read
	Meta.init str, f
	str
	}
	end
	end
	end

	module URI
	class HTTP
	def buffer_open(buf, proxy, options) # :nodoc:
	OpenURI.open_http(buf, self, proxy, options)
	end

	include OpenURI::OpenRead
	end

	class FTP
	def buffer_open(buf, proxy, options) # :nodoc:
	if proxy
	OpenURI.open_http(buf, self, proxy, options)
	return
	end

	begin
	require 'net/ftp'
	rescue LoadError
	abort "net/ftp is not found. You may need to `gem install net-ftp` to install net/ftp."
	end

	path = self.path
	path = path.sub(%r{\A/}, '%2F') # re-encode the beginning slash because uri library decodes it.
	directories = path.split(%r{/}, -1)
	directories.each {\|d\|
	d.gsub!(/%([0-9A-Fa-f][0-9A-Fa-f])/) { [$1].pack("H2") }
	}
	unless filename = directories.pop
	raise ArgumentError, "no filename: #{self.inspect}"
	end
	directories.each {\|d\|
	if /[\r\n]/ =~ d
	raise ArgumentError, "invalid directory: #{d.inspect}"
	end
	}
	if /[\r\n]/ =~ filename
	raise ArgumentError, "invalid filename: #{filename.inspect}"
	end
	typecode = self.typecode
	if typecode && /\A[aid]\z/ !~ typecode
	raise ArgumentError, "invalid typecode: #{typecode.inspect}"
	end

	# The access sequence is defined by RFC 1738
	ftp = Net::FTP.new
	ftp.connect(self.hostname, self.port)
	ftp.passive = !options[:ftp_active_mode]
	# todo: extract user/passwd from .netrc.
	user = 'anonymous'
	passwd = nil
	user, passwd = self.userinfo.split(/:/) if self.userinfo
	ftp.login(user, passwd)
	directories.each {\|cwd\|
	ftp.voidcmd("CWD #{cwd}")
	}
	if typecode
	# xxx: typecode D is not handled.
	ftp.voidcmd("TYPE #{typecode.upcase}")
	end
	if options[:content_length_proc]
	options[:content_length_proc].call(ftp.size(filename))
	end
	ftp.retrbinary("RETR #{filename}", 4096) { \|str\|
	buf << str
	options[:progress_proc].call(buf.size) if options[:progress_proc]
	}
	ftp.close
	buf.io.rewind
	end

	include OpenURI::OpenRead
	end
	end