Merge pull request #163 from github/custom-domain-simplifaction

Custom domain simplifaction

lib/github-pages-health-check/domain.rb

@@ -91,7 +91,7 @@ class Domain < Checkable
         host uri nameservers dns_resolves? proxied? cloudflare_ip?
         fastly_ip? old_ip_address? a_record? aaaa_record? a_record_present? aaaa_record_present?
         cname_record? mx_records_present? valid_domain? apex_domain?
-        should_be_a_record? cname_to_github_user_domain?
+        should_be_a_record? cname_to_github_user_domain? cname_to_domain_to_pages?
         cname_to_pages_dot_github_dot_com? cname_to_fastly?
         pointed_to_github_pages_ip? non_github_pages_ip_present? pages_domain?
         served_by_pages? valid? reason valid_domain? https?
@@ -243,6 +243,16 @@ def cname_to_github_user_domain?
         cname? && !cname_to_pages_dot_github_dot_com? && cname.pages_domain?
       end
 
+      # Check if the CNAME points to a Domain that points to pages
+      # e.g. CNAME -> Domain -> Pages
+      def cname_to_domain_to_pages?
+        a_record_to_pages = dns.select { |d| d.type == Dnsruby::Types::A && d.name.to_s == host }.first
+
+        return false unless a_record_to_pages && cname? && !cname_to_pages_dot_github_dot_com? && @www_cname
+
+        CURRENT_IP_ADDRESSES.include?(a_record_to_pages.address.to_s.downcase)
+      end
+
       # Is the given domain a CNAME to pages.github.(io|com)
       # instead of being CNAME'd to the user's subdomain?
       #
@@ -304,6 +314,7 @@ def proxied?
         return true if cloudflare_ip?
         return false if pointed_to_github_pages_ip?
         return false if cname_to_github_user_domain?
+        return false if cname_to_domain_to_pages?
         return false if cname_to_pages_dot_github_dot_com?
         return false if cname_to_fastly? || fastly_ip?
 
@@ -399,9 +410,16 @@ def cname
         cnames = dns.take_while { |answer| answer.type == Dnsruby::Types::CNAME }
         return if cnames.empty?
 
+        www_cname(cnames.last)
         @cname ||= Domain.new(cnames.last.cname.to_s)
       end
 
+      # Check if we have a 'www.' CNAME that matches the domain
+      def www_cname(cname)
+        @www_cname ||= cname.name.to_s.start_with?("www.") &&
+          cname.name.to_s.end_with?(cname.domainname.to_s)
+      end
+
       def mx_records_present?
         return unless dns?
 
@@ -454,8 +472,7 @@ def https_eligible?
         return false if host.include?("_")
 
         # Must be a CNAME or point to our IPs.
-        # Only check the one domain if a CNAME. Don't check the parent domain.
-        return true if cname_to_github_user_domain?
+        return true if cname_to_github_user_domain? || cname_to_domain_to_pages?
 
         # Check CAA records for the full domain and its parent domain.
         pointed_to_github_pages_ip? && caa.lets_encrypt_allowed?

lib/github-pages-health-check/version.rb

@@ -2,6 +2,6 @@
 
 module GitHubPages
   module HealthCheck
-    VERSION = "1.18.2"
+    VERSION = "1.18.3"
   end
 end

spec/github_pages_health_check/domain_spec.rb

@@ -240,6 +240,100 @@
       end
     end
 
+    context "CNAME to Domain to Pages" do
+      let(:cname) { "www.fontawesome.it" }
+      let(:domain) { "fontawesome.it" }
+      let(:ip) { "185.199.108.153" }
+      before(:each) do
+        allow(subject).to receive(:dns) do
+          [
+            Dnsruby::RR.create("#{cname}. 1000 IN CNAME #{domain}"),
+            a_packet
+          ]
+        end
+      end
+
+      it "follows the CNAMEs all the way down" do
+        expect(subject.cname.host).to eq("fontawesome.it")
+      end
+
+      it "knows it's a Pages IP at the end" do
+        expect(subject).to be_a_cname_to_domain_to_pages
+      end
+    end
+
+    context "Random CNAME to Domain that goes to Pages" do
+      let(:cname) { "monalisa" }
+      let(:domain) { "fontawesome.it" }
+      let(:ip) { "185.199.108.153" }
+      before(:each) do
+        allow(subject).to receive(:dns) do
+          [
+            Dnsruby::RR.create("#{cname}. 1000 IN CNAME #{domain}"),
+            a_packet
+          ]
+        end
+      end
+
+      it "CNAME does not start with www and no match to host" do
+        expect(subject).to_not be_a_cname_to_domain_to_pages
+      end
+    end
+
+    context "CNAME with same host but no www" do
+      let(:cname) { "blog.fontawesome.it" }
+      let(:domain) { "fontawesome.it" }
+      let(:ip) { "185.199.108.153" }
+      before(:each) do
+        allow(subject).to receive(:dns) do
+          [
+            Dnsruby::RR.create("#{cname}. 1000 IN CNAME #{domain}"),
+            a_packet
+          ]
+        end
+      end
+
+      it "CNAME does not start with www and no match to host" do
+        expect(subject).to_not be_a_cname_to_domain_to_pages
+      end
+    end
+
+    context "CNAME starts with www but different host" do
+      let(:cname) { "www.fontawesome.it" }
+      let(:domain) { "awesomefont.it" }
+      let(:ip) { "185.199.108.153" }
+      before(:each) do
+        allow(subject).to receive(:dns) do
+          [
+            Dnsruby::RR.create("#{cname}. 1000 IN CNAME #{domain}"),
+            a_packet
+          ]
+        end
+      end
+
+      it "CNAME does not match to host" do
+        expect(subject).to_not be_a_cname_to_domain_to_pages
+      end
+    end
+
+    context "CNAME to Domain that doesn't go to Pages" do
+      let(:cname) { "www.fontawesome.it" }
+      let(:domain) { "fontawesome.it" }
+      let(:ip) { "127.0.0.1" }
+      before(:each) do
+        allow(subject).to receive(:dns) do
+          [
+            Dnsruby::RR.create("#{cname}. 1000 IN CNAME #{domain}"),
+            a_packet
+          ]
+        end
+      end
+
+      it "knows it's not a Pages IP at the end" do
+        expect(subject).to_not be_a_cname_to_domain_to_pages
+      end
+    end
+
     context "broken CNAMEs" do
       before do
         allow(subject).to receive(:dns) do