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require 'net/dns/resolver'
# Custom Domain
#
# Require net-dns gem
#
# A Rack middleware to to resolve the custom domain to original subdomain
# for your multi telent application.
#
# It's all transperant to your application, it performs cname lookup and
# overwrite HTTP_HOST if needed
#
# www.example.org => example.myapp.com
#
# Credit: Inspired by http://codetunes.com/2009/04/17/dynamic-cookie-domains-with-racks-middleware/
class CustomDomain
@@cache = {}
def initialize(app, default_domain)
@app = app
@default_domain = default_domain
end
def call(env)
host, port = env["HTTP_HOST"].split(':')
# modify Environment variable HTTP_HOST if custom domain is found
if custom_domain?(host)
domain = cname_lookup(host)
env['HTTP_X_FORWARDED_HOST'] = [host, domain].join(', ')
logger.info("CustomDomain: mapped #{host} => #{domain}")
end
@app.call(env)
end
def custom_domain?(host)
host !~ /#{@default_domain.sub(/^\./, '')}/i
end
def cname_lookup(host)
unless @@cache[host]
Net::DNS::Resolver.new.query(host).each_cname do |cname|
@@cache[host] = cname if cname.include?(@default_domain)
end
end
@@cache[host]
end
private
def logger
RAILS_DEFAULT_LOGGER || Logger.new(STDOUT)
end
end
@madsheep
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madsheep commented Apr 22, 2010

I wonder if there is any way of handling redirects after using this middleware? Once you tricked rails to think they are on 'example.myapp.com' redtiect_to method will always redirect user from example.com to example.myapp.com once you use it.

@speedmax
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speedmax commented Jun 26, 2013

3 years later.. :)

you have to handle all the URL helper and redirection yourself.. redirect_to(:host => domain)

@speedmax
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speedmax commented Aug 16, 2014

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