Ruby - net/http - following redirects - ruby

Question

I've got a URL and I'm using HTTP GET to pass a query along to a page. What happens with the most recent flavor (in net/http) is that the script doesn't go beyond the 302 response. I've tried several different solutions; HTTPClient, net/http, Rest-Client, Patron...
I need a way to continue to the final page in order to validate an attribute tag on that pages html. The redirection is due to a mobile user agent hitting a page that redirects to a mobile view, hence the mobile user agent in the header. Here is my code as it is today:
require 'uri'
require 'net/http'
class Check_Get_Page
def more_http
url = URI.parse('my_url')
req, data = Net::HTTP::Get.new(url.path, {
'User-Agent' => 'Mozilla/5.0 (iPhone; U; CPU iPhone OS 4_3_2 like Mac OS X; en-us) AppleWebKit/533.17.9 (KHTML, like Gecko) Version/5.0.2 Mobile/8H7 Safari/6533.18.5'
})
res = Net::HTTP.start(url.host, url.port) {|http|
http.request(req)
}
cookie = res.response['set-cookie']
puts 'Body = ' + res.body
puts 'Message = ' + res.message
puts 'Code = ' + res.code
puts "Cookie \n" + cookie
end
end
m = Check_Get_Page.new
m.more_http
Any suggestions would be greatly appreciated!

Answer 1

To follow redirects, you can do something like this (taken from ruby-doc)
Following Redirection
require 'net/http'
require 'uri'
def fetch(uri_str, limit = 10)
# You should choose better exception.
raise ArgumentError, 'HTTP redirect too deep' if limit == 0
url = URI.parse(uri_str)
req = Net::HTTP::Get.new(url.path, { 'User-Agent' => 'Mozilla/5.0 (etc...)' })
response = Net::HTTP.start(url.host, url.port, use_ssl: true) { |http| http.request(req) }
case response
when Net::HTTPSuccess then response
when Net::HTTPRedirection then fetch(response['location'], limit - 1)
else
response.error!
end
end
print fetch('http://www.ruby-lang.org/')

Answer 2

Given a URL that redirects
url = 'http://httpbin.org/redirect-to?url=http%3A%2F%2Fhttpbin.org%2Fredirect-to%3Furl%3Dhttp%3A%2F%2Fexample.org'
A. Net::HTTP
begin
response = Net::HTTP.get_response(URI.parse(url))
url = response['location']
end while response.is_a?(Net::HTTPRedirection)
Make sure that you handle the case when there are too many redirects.
B. OpenURI
open(url).read
OpenURI::OpenRead#open follows redirects by default, but it doesn't limit the number of redirects.

Answer 3

I wrote another class for this based on examples given here, thank you very much everybody. I added cookies, parameters and exceptions and finally got what I need: https://gist.github.com/sekrett/7dd4177d6c87cf8265cd
require 'uri'
require 'net/http'
require 'openssl'
class UrlResolver
def self.resolve(uri_str, agent = 'curl/7.43.0', max_attempts = 10, timeout = 10)
attempts = 0
cookie = nil
until attempts >= max_attempts
attempts += 1
url = URI.parse(uri_str)
http = Net::HTTP.new(url.host, url.port)
http.open_timeout = timeout
http.read_timeout = timeout
path = url.path
path = '/' if path == ''
path += '?' + url.query unless url.query.nil?
params = { 'User-Agent' => agent, 'Accept' => '*/*' }
params['Cookie'] = cookie unless cookie.nil?
request = Net::HTTP::Get.new(path, params)
if url.instance_of?(URI::HTTPS)
http.use_ssl = true
http.verify_mode = OpenSSL::SSL::VERIFY_NONE
end
response = http.request(request)
case response
when Net::HTTPSuccess then
break
when Net::HTTPRedirection then
location = response['Location']
cookie = response['Set-Cookie']
new_uri = URI.parse(location)
uri_str = if new_uri.relative?
url + location
else
new_uri.to_s
end
else
raise 'Unexpected response: ' + response.inspect
end
end
raise 'Too many http redirects' if attempts == max_attempts
uri_str
# response.body
end
end
puts UrlResolver.resolve('http://www.ruby-lang.org')

Answer 4

The reference that worked for me is here: http://shadow-file.blogspot.co.uk/2009/03/handling-http-redirection-in-ruby.html
Compared to most examples (including the accepted answer here), it's more robust as it handles URLs which are just a domain (http://example.com - needs to add a /), handles SSL specifically, and also relative URLs.
Of course you would be better off using a library like RESTClient in most cases, but sometimes the low-level detail is necessary.

Answer 5

Maybe you can use curb-fu gem here https://github.com/gdi/curb-fu the only thing is some extra code to make it follow redirect. I've used the following before. Hope it helps.
require 'rubygems'
require 'curb-fu'
module CurbFu
class Request
module Base
def new_meth(url_params, query_params = {})
curb = old_meth url_params, query_params
curb.follow_location = true
curb
end
alias :old_meth :build
alias :build :new_meth
end
end
end
#this should follow the redirect because we instruct
#Curb.follow_location = true
print CurbFu.get('http://<your path>/').body

Answer 6

If you do not need to care about the details at each redirection, you can use the library Mechanize
require 'mechanize'
agent = Mechanize.new
begin
response = #agent.get(url)
rescue Mechanize::ResponseCodeError
// response codes other than 200, 301, or 302
rescue Timeout::Error
rescue Mechanize::RedirectLimitReachedError
rescue StandardError
end
It will return the destination page.
Or you can turn off redirection by this :
agent.redirect_ok = false
Or you can optionally change some settings at the request
agent.user_agent = "Mozilla/5.0 (Linux; Android 6.0; Nexus 5 Build/MRA58N) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.106 Mobile Safari/537.36"