Change e-mail domain blocks to block IPs dynamically (#17635)

* Change e-mail domain blocks to block IPs dynamically

* Update app/workers/scheduler/email_domain_block_refresh_scheduler.rb

Co-authored-by: Yamagishi Kazutoshi <ykzts@desire.sh>

* Update app/workers/scheduler/email_domain_block_refresh_scheduler.rb

Co-authored-by: Yamagishi Kazutoshi <ykzts@desire.sh>

Co-authored-by: Yamagishi Kazutoshi <ykzts@desire.sh>

spec/validators/blacklisted_email_validator_spec.rb

@@ -4,7 +4,7 @@ require 'rails_helper'
 
 RSpec.describe BlacklistedEmailValidator, type: :validator do
   describe '#validate' do
-    let(:user)   { double(email: 'info@mail.com', errors: errors) }
+    let(:user)   { double(email: 'info@mail.com', sign_up_ip: '1.2.3.4', errors: errors) }
     let(:errors) { double(add: nil) }
 
     before do

spec/validators/email_mx_validator_spec.rb

@@ -4,24 +4,28 @@ require 'rails_helper'
 
 describe EmailMxValidator do
   describe '#validate' do
-    let(:user) { double(email: 'foo@example.com', errors: double(add: nil)) }
+    let(:user) { double(email: 'foo@example.com', sign_up_ip: '1.2.3.4', errors: double(add: nil)) }
 
-    it 'does not add errors if there are no DNS records for an e-mail domain that is explicitly allowed' do
-      old_whitelist = Rails.configuration.x.email_domains_whitelist
-      Rails.configuration.x.email_domains_whitelist = 'example.com'
+    context 'for an e-mail domain that is explicitly allowed' do
+      around do |block|
+        tmp = Rails.configuration.x.email_domains_whitelist
+        Rails.configuration.x.email_domains_whitelist = 'example.com'
+        block.call
+        Rails.configuration.x.email_domains_whitelist = tmp
+      end
 
-      resolver = double
+      it 'does not add errors if there are no DNS records' do
+        resolver = double
 
-      allow(resolver).to receive(:getresources).with('example.com', Resolv::DNS::Resource::IN::MX).and_return([])
-      allow(resolver).to receive(:getresources).with('example.com', Resolv::DNS::Resource::IN::A).and_return([])
-      allow(resolver).to receive(:getresources).with('example.com', Resolv::DNS::Resource::IN::AAAA).and_return([])
-      allow(resolver).to receive(:timeouts=).and_return(nil)
-      allow(Resolv::DNS).to receive(:open).and_yield(resolver)
+        allow(resolver).to receive(:getresources).with('example.com', Resolv::DNS::Resource::IN::MX).and_return([])
+        allow(resolver).to receive(:getresources).with('example.com', Resolv::DNS::Resource::IN::A).and_return([])
+        allow(resolver).to receive(:getresources).with('example.com', Resolv::DNS::Resource::IN::AAAA).and_return([])
+        allow(resolver).to receive(:timeouts=).and_return(nil)
+        allow(Resolv::DNS).to receive(:open).and_yield(resolver)
 
-      subject.validate(user)
-      expect(user.errors).to_not have_received(:add)
-
-      Rails.configuration.x.email_domains_whitelist = old_whitelist
+        subject.validate(user)
+        expect(user.errors).to_not have_received(:add)
+      end
     end
 
     it 'adds an error if there are no DNS records for the e-mail domain' do
@@ -37,7 +41,7 @@ describe EmailMxValidator do
       expect(user.errors).to have_received(:add)
     end
 
-    it 'adds an error if a MX record exists but does not lead to an IP' do
+    it 'adds an error if a MX record does not lead to an IP' do
       resolver = double
 
       allow(resolver).to receive(:getresources).with('example.com', Resolv::DNS::Resource::IN::MX).and_return([double(exchange: 'mail.example.com')])
@@ -53,7 +57,7 @@ describe EmailMxValidator do
     end
 
     it 'adds an error if the A record is blacklisted' do
-      EmailDomainBlock.create!(domain: '1.2.3.4')
+      EmailDomainBlock.create!(domain: 'alternate-example.com', ips: ['1.2.3.4'])
       resolver = double
 
       allow(resolver).to receive(:getresources).with('example.com', Resolv::DNS::Resource::IN::MX).and_return([])
@@ -67,7 +71,7 @@ describe EmailMxValidator do
     end
 
     it 'adds an error if the AAAA record is blacklisted' do
-      EmailDomainBlock.create!(domain: 'fd00::1')
+      EmailDomainBlock.create!(domain: 'alternate-example.com', ips: ['fd00::1'])
       resolver = double
 
       allow(resolver).to receive(:getresources).with('example.com', Resolv::DNS::Resource::IN::MX).and_return([])
@@ -80,8 +84,8 @@ describe EmailMxValidator do
       expect(user.errors).to have_received(:add)
     end
 
-    it 'adds an error if the MX record is blacklisted' do
-      EmailDomainBlock.create!(domain: '2.3.4.5')
+    it 'adds an error if the A record of the MX record is blacklisted' do
+      EmailDomainBlock.create!(domain: 'mail.other-domain.com', ips: ['2.3.4.5'])
       resolver = double
 
       allow(resolver).to receive(:getresources).with('example.com', Resolv::DNS::Resource::IN::MX).and_return([double(exchange: 'mail.example.com')])
@@ -96,8 +100,8 @@ describe EmailMxValidator do
       expect(user.errors).to have_received(:add)
     end
 
-    it 'adds an error if the MX IPv6 record is blacklisted' do
-      EmailDomainBlock.create!(domain: 'fd00::2')
+    it 'adds an error if the AAAA record of the MX record is blacklisted' do
+      EmailDomainBlock.create!(domain: 'mail.other-domain.com', ips: ['fd00::2'])
       resolver = double
 
       allow(resolver).to receive(:getresources).with('example.com', Resolv::DNS::Resource::IN::MX).and_return([double(exchange: 'mail.example.com')])
@@ -112,7 +116,7 @@ describe EmailMxValidator do
       expect(user.errors).to have_received(:add)
     end
 
-    it 'adds an error if the MX hostname is blacklisted' do
+    it 'adds an error if the MX record is blacklisted' do
       EmailDomainBlock.create!(domain: 'mail.example.com')
       resolver = double