Replace SSRF resolver with Addrinfo.getaddrinfo to include alternative localhost versions

lib/gitlab/url_blocker.rb

@@ -22,10 +22,12 @@ module Gitlab
           return true if blocked_user_or_hostname?(uri.user)
           return true if blocked_user_or_hostname?(uri.hostname)
 
-          server_ips = Resolv.getaddresses(uri.hostname)
+          server_ips = Addrinfo.getaddrinfo(uri.hostname, 80, nil, :STREAM).map(&:ip_address)
           return true if (blocked_ips & server_ips).any?
         rescue Addressable::URI::InvalidURIError
           return true
+        rescue SocketError
+          return false
         end
 
         false

spec/lib/gitlab/url_blocker_spec.rb

@@ -20,6 +20,22 @@ describe Gitlab::UrlBlocker do
       expect(described_class.blocked_url?('https://gitlab.com:25/foo/foo.git')).to be true
     end
 
+    it 'returns true for alternative version of 127.0.0.1 (0177.1)' do
+      expect(described_class.blocked_url?('https://0177.1:65535/foo/foo.git')).to be true
+    end
+
+    it 'returns true for alternative version of 127.0.0.1 (0x7f.1)' do
+      expect(described_class.blocked_url?('https://0x7f.1:65535/foo/foo.git')).to be true
+    end
+
+    it 'returns true for alternative version of 127.0.0.1 (2130706433)' do
+      expect(described_class.blocked_url?('https://2130706433:65535/foo/foo.git')).to be true
+    end
+
+    it 'returns true for alternative version of 127.0.0.1 (127.000.000.001)' do
+      expect(described_class.blocked_url?('https://127.000.000.001:65535/foo/foo.git')).to be true
+    end
+
     it 'returns true for a non-alphanumeric hostname' do
       stub_resolv