From d5f0e3726041a36c97d09747d4a0190b2c345958 Mon Sep 17 00:00:00 2001
From: Matt Jankowski <matt@jankowski.online>
Date: Fri, 17 Apr 2026 04:09:37 -0400
Subject: [PATCH] Include hosts resolver in request socket DNS lookup (#38699)

---
 app/lib/request.rb            |  8 +++-----
 spec/lib/fasp/request_spec.rb | 16 +++++++++-------
 spec/lib/request_spec.rb      | 35 +++++++++++++++++++++--------------
 3 files changed, 33 insertions(+), 26 deletions(-)

diff --git a/app/lib/request.rb b/app/lib/request.rb
index 66d7ece70f..376a37638c 100644
--- a/app/lib/request.rb
+++ b/app/lib/request.rb
@@ -292,11 +292,9 @@ class Request
         begin
           addresses = [IPAddr.new(host)]
         rescue IPAddr::InvalidAddressError
-          Resolv::DNS.open do |dns|
-            dns.timeouts = 5
-            addresses = dns.getaddresses(host)
-            addresses = addresses.grep(Resolv::IPv6).take(2) + addresses.grep_v(Resolv::IPv6).take(2)
-          end
+          resolvers = [Resolv::Hosts.new, Resolv::DNS.new.tap { |dns| dns.timeouts = 5 }]
+          addresses = Resolv.new(resolvers).getaddresses(host)
+          addresses = addresses.grep(Resolv::IPv6::Regex).take(2) + addresses.grep_v(Resolv::IPv6::Regex).take(2)
         end
 
         socks = []
diff --git a/spec/lib/fasp/request_spec.rb b/spec/lib/fasp/request_spec.rb
index 6456057b5e..cdc20270cd 100644
--- a/spec/lib/fasp/request_spec.rb
+++ b/spec/lib/fasp/request_spec.rb
@@ -86,14 +86,16 @@ RSpec.describe Fasp::Request do
         WebMock.enable!
       end
 
+      let(:resolv_service) { instance_double(Resolv) }
+
+      before do
+        allow(Resolv).to receive(:new).and_return(resolv_service)
+        allow(resolv_service).to receive(:getaddresses).with('reqprov.example.com').and_return(%w(0.0.0.0 2001:db8::face))
+      end
+
       it 'raises Mastodon::ValidationError' do
-        resolver = instance_double(Resolv::DNS)
-
-        allow(resolver).to receive(:getaddresses).with('reqprov.example.com').and_return(%w(0.0.0.0 2001:db8::face))
-        allow(resolver).to receive(:timeouts=).and_return(nil)
-        allow(Resolv::DNS).to receive(:open).and_yield(resolver)
-
-        expect { subject.send(method, '/test_path') }.to raise_error(Mastodon::ValidationError)
+        expect { subject.send(method, '/test_path') }
+          .to raise_error(Mastodon::ValidationError)
       end
     end
   end
diff --git a/spec/lib/request_spec.rb b/spec/lib/request_spec.rb
index da61823455..228c8bbb67 100644
--- a/spec/lib/request_spec.rb
+++ b/spec/lib/request_spec.rb
@@ -66,15 +66,20 @@ RSpec.describe Request do
         expect(a_request(:get, 'http://example.com')).to have_been_made.once
       end
 
-      it 'executes a HTTP request when the first address is private' do
-        resolver = instance_double(Resolv::DNS)
+      context 'when first address is private' do
+        let(:resolv_service) { instance_double(Resolv) }
 
-        allow(resolver).to receive(:getaddresses).with('example.com').and_return(%w(0.0.0.0 2001:4860:4860::8844))
-        allow(resolver).to receive(:timeouts=).and_return(nil)
-        allow(Resolv::DNS).to receive(:open).and_yield(resolver)
+        before do
+          allow(Resolv).to receive(:new).and_return(resolv_service)
+          allow(resolv_service).to receive(:getaddresses).with('example.com').and_return(%w(0.0.0.0 2001:4860:4860::8844))
+        end
 
-        expect { |block| subject.perform(&block) }.to yield_control
-        expect(a_request(:get, 'http://example.com')).to have_been_made.once
+        it 'executes a HTTP request' do
+          expect { |block| subject.perform(&block) }
+            .to yield_control
+          expect(a_request(:get, 'http://example.com'))
+            .to have_been_made.once
+        end
       end
 
       it 'makes a request with expected headers, yields, and closes the underlying connection' do
@@ -123,14 +128,16 @@ RSpec.describe Request do
         WebMock.enable!
       end
 
+      let(:resolv_service) { instance_double(Resolv) }
+
+      before do
+        allow(Resolv).to receive(:new).with([be_a(Resolv::Hosts), be_a(Resolv::DNS)]).and_return(resolv_service)
+        allow(resolv_service).to receive(:getaddresses).with('example.com').and_return(%w(0.0.0.0 2001:db8::face))
+      end
+
       it 'raises Mastodon::ValidationError' do
-        resolver = instance_double(Resolv::DNS)
-
-        allow(resolver).to receive(:getaddresses).with('example.com').and_return(%w(0.0.0.0 2001:db8::face))
-        allow(resolver).to receive(:timeouts=).and_return(nil)
-        allow(Resolv::DNS).to receive(:open).and_yield(resolver)
-
-        expect { subject.perform }.to raise_error Mastodon::ValidationError
+        expect { subject.perform }
+          .to raise_error Mastodon::ValidationError
       end
     end