FIX: allows onebox to force GET hosts returning wrong headers on HEAD

lib/final_destination.rb

@@ -18,6 +18,7 @@ class FinalDestination
       end
 
     @opts = opts || {}
+    @force_get_hosts = @opts[:force_get_hosts] || []
     @opts[:max_redirects] ||= 5
     @opts[:lookup_ip] ||= lambda do |host|
       begin
@@ -29,6 +30,7 @@ class FinalDestination
     @ignored = [Discourse.base_url_no_prefix] + (@opts[:ignore_redirects] || [])
     @limit = @opts[:max_redirects]
     @status = :ready
+    @http_verb = @force_get_hosts.any? { |host| hostname_matches?(host) } ? :get : :head
     @cookie = nil
   end
 
@@ -79,7 +81,7 @@ class FinalDestination
 
     return nil unless validate_uri
     headers = request_headers
-    response = Excon.head(
+    response = Excon.public_send(@http_verb,
       @uri.to_s,
       read_timeout: FinalDestination.connection_timeout,
       headers: headers

lib/oneboxer.rb

@@ -21,6 +21,10 @@ module Oneboxer
     @ignore_redirects ||= ['http://www.dropbox.com', 'http://store.steampowered.com', Discourse.base_url]
   end
 
+  def self.force_get_hosts
+    @force_get_hosts ||= ['http://us.battle.net']
+  end
+
   def self.preview(url, options = nil)
     options ||= {}
     invalidate(url) if options[:invalidate_oneboxes]
@@ -147,7 +151,7 @@ module Oneboxer
 
     def self.onebox_raw(url)
       Rails.cache.fetch(onebox_cache_key(url), expires_in: 1.day) do
-        fd = FinalDestination.new(url, ignore_redirects: ignore_redirects)
+        fd = FinalDestination.new(url, ignore_redirects: ignore_redirects, force_get_hosts: force_get_hosts)
         uri = fd.resolve
         return blank_onebox if uri.blank? || SiteSetting.onebox_domains_blacklist.include?(uri.hostname)
         options = {

spec/components/final_destination_spec.rb

@@ -7,6 +7,8 @@ describe FinalDestination do
     {
       ignore_redirects: ['https://ignore-me.com'],
 
+      force_get_hosts: ['https://force.get.com'],
+
       # avoid IP lookups in test
       lookup_ip: lambda do |host|
         case host
@@ -17,6 +19,7 @@ describe FinalDestination do
         when 'private-host.com' then '192.168.10.1'
         when 'internal-ipv6.com' then '2001:abc:de:01:3:3d0:6a65:c2bf'
         when 'ignore-me.com' then '53.84.143.152'
+        when 'force.get.com' then '22.102.29.40'
         else
           as_ip = IPAddr.new(host) rescue nil
           raise "couldn't lookup #{host}" if as_ip.nil?
@@ -132,6 +135,31 @@ describe FinalDestination do
       end
     end
 
+    context "GET can be forced" do
+      before do
+        stub_request(:head, 'https://force.get.com/posts?page=4')
+        stub_request(:get, 'https://force.get.com/posts?page=4')
+        stub_request(:head, 'https://eviltrout.com/posts?page=2')
+        stub_request(:get, 'https://eviltrout.com/posts?page=2')
+      end
+
+      it "will do a GET when forced" do
+        final = FinalDestination.new('https://force.get.com/posts?page=4', opts)
+        expect(final.resolve.to_s).to eq('https://force.get.com/posts?page=4')
+        expect(final.status).to eq(:resolved)
+        expect(WebMock).to have_requested(:get, 'https://force.get.com/posts?page=4')
+        expect(WebMock).to_not have_requested(:head, 'https://force.get.com/posts?page=4')
+      end
+
+      it "will do a HEAD if not forced" do
+        final = FinalDestination.new('https://eviltrout.com/posts?page=2', opts)
+        expect(final.resolve.to_s).to eq('https://eviltrout.com/posts?page=2')
+        expect(final.status).to eq(:resolved)
+        expect(WebMock).to_not have_requested(:get, 'https://eviltrout.com/posts?page=2')
+        expect(WebMock).to have_requested(:head, 'https://eviltrout.com/posts?page=2')
+      end
+    end
+
     context "HEAD not supported" do
       before do
         stub_request(:get, 'https://eviltrout.com').to_return(