From f8d0960af260219ab7c10a797ac62ecad25b2974 Mon Sep 17 00:00:00 2001
From: Jean-Samuel Aubry-Guzzi <js.aubry@shopify.com>
Date: Mon, 8 Dec 2025 11:22:55 -0500
Subject: [PATCH] [ruby/resolv] Handle TCP Requester #recv_reply incomplete
 data

https://github.com/ruby/resolv/commit/9c640bdc4a
---
 lib/resolv.rb           |  7 +++--
 test/resolv/test_dns.rb | 61 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 65 insertions(+), 3 deletions(-)

diff --git a/lib/resolv.rb b/lib/resolv.rb
index e6153af2a9..fa7d4e2e47 100644
--- a/lib/resolv.rb
+++ b/lib/resolv.rb
@@ -721,7 +721,8 @@ class Resolv
           begin
             reply, from = recv_reply(select_result[0])
           rescue Errno::ECONNREFUSED, # GNU/Linux, FreeBSD
-                 Errno::ECONNRESET # Windows
+                 Errno::ECONNRESET, # Windows
+                 EOFError
             # No name server running on the server?
             # Don't wait anymore.
             raise ResolvTimeout
@@ -931,10 +932,10 @@ class Resolv
 
         def recv_reply(readable_socks)
           len_data = readable_socks[0].read(2)
-          raise Errno::ECONNRESET if len_data.nil?
+          raise EOFError if len_data.nil? || len_data.bytesize != 2
           len = len_data.unpack('n')[0]
           reply = @socks[0].read(len)
-          raise Errno::ECONNRESET if reply.nil?
+          raise EOFError if reply.nil? || reply.bytesize != len
           return reply, nil
         end
 
diff --git a/test/resolv/test_dns.rb b/test/resolv/test_dns.rb
index 1dda9bc627..7a01909eeb 100644
--- a/test/resolv/test_dns.rb
+++ b/test/resolv/test_dns.rb
@@ -881,4 +881,65 @@ class TestResolvDNS < Test::Unit::TestCase
       client_thread.join
     end
   end
+
+  def test_tcp_connection_closed_with_partial_length_prefix
+    with_tcp('127.0.0.1', 0) do |t|
+      _, server_port, _, server_address = t.addr
+
+      server_thread = Thread.new do
+        ct = t.accept
+        ct.recv(512)
+        ct.write "A" # 1 byte
+        ct.close
+      end
+
+      client_thread = Thread.new do
+        requester = Resolv::DNS::Requester::TCP.new(server_address, server_port)
+        begin
+          msg = Resolv::DNS::Message.new
+          msg.add_question('example.org', Resolv::DNS::Resource::IN::A)
+          sender = requester.sender(msg, msg)
+          assert_raise(Resolv::ResolvTimeout) do
+            requester.request(sender, 2)
+          end
+        ensure
+          requester.close
+        end
+      end
+
+      server_thread.join
+      client_thread.join
+    end
+  end
+
+  def test_tcp_connection_closed_with_partial_message_body
+    with_tcp('127.0.0.1', 0) do |t|
+      _, server_port, _, server_address = t.addr
+
+      server_thread = Thread.new do
+        ct = t.accept
+        ct.recv(512)
+        ct.write([10].pack('n')) # length 10
+        ct.write "12345" # 5 bytes (partial)
+        ct.close
+      end
+
+      client_thread = Thread.new do
+        requester = Resolv::DNS::Requester::TCP.new(server_address, server_port)
+        begin
+          msg = Resolv::DNS::Message.new
+          msg.add_question('example.org', Resolv::DNS::Resource::IN::A)
+          sender = requester.sender(msg, msg)
+          assert_raise(Resolv::ResolvTimeout) do
+            requester.request(sender, 2)
+          end
+        ensure
+          requester.close
+        end
+      end
+
+      server_thread.join
+      client_thread.join
+    end
+  end
 end