禁止Ruby open-uri重定向

Question

我有一个简单的html解析器(用于学习目的)，我一直在开发它。

require 'open-uri'
puts "Enter URL to parse HTML: "
url = gets.chomp
puts "Enter tag to parse from: "
tag = gets.chomp
response = open(url).read
title1 = response.index(tag)
title2 = response.index(tag.insert(1,'/')) -1
result = response[(title1 + tag.length - 1)..title2]
print result 

当我输入http://twitter.com时，我得到这个错误消息：

ERROR: `open_loop': redirection forbidden: http://twitter.com -> https://twitter.com/ (RuntimeError)
from /usr/local/rvm/rubies/ruby-2.1.4/lib/ruby/2.1.0/open-uri.rb:149:in `open_uri'
from /usr/local/rvm/rubies/ruby-2.1.4/lib/ruby/2.1.0/open-uri.rb:704:in `open'
from /usr/local/rvm/rubies/ruby-2.1.4/lib/ruby/2.1.0/open-uri.rb:34:in `open'
from /home/ubuntu/workspace/htmlparse.rb:6:in `<main>' 

有什么建议或帮助吗？我是Ruby的新手，我知道其他的html解析模块，但我这样做是为了学习Ruby的基础知识。谢谢。

Answer 1

看一看open_uri_redirections的精华。

它为Ruby打了补丁，允许从OpenURI到HTTPS或相反方向的重定向。

Answer 2

您也可以捕获异常，然后使用'https‘url重试。

url = "http://classic.ona.io/api/v1/files/3538545?filename=gringgo/attachments/1485229166168.jpg"

uri = URI.parse(url)
tries = 3

begin
  uri.open(redirect: false)
rescue OpenURI::HTTPRedirect => redirect
  uri = redirect.uri # assigned from the "Location" response header
  retry if (tries -= 1) > 0
  raise
end

来源：https://twin.github.io/improving-open-uri/

Answer 3

Ruby2.4修复了open-uri中的升级重定向(从http -> https)，所以现在：

RUBY_VERSION
=> "2.4.2"

require 'open-uri'
=> true

open('http://twitter.com')
=> #<Tempfile:/tmp/open-uri20170926-24254-1kflwxq>

来源：http://blog.bigbinary.com/2017/03/02/open-uri-in-ruby-2-4-allows-http-to-https-redirection.html