Set Connection: closed when running without request queueing

lib/puma/server.rb

@@ -371,7 +371,6 @@ def process_client(client, buffer)
             close_socket = false
             return
           when true
-            return unless @queue_requests
             buffer.reset
 
             ThreadPool.clean_thread_locals if clean_thread_locals
@@ -612,10 +611,10 @@ def handle_request(req, lines)
         line_ending = LINE_END
         colon = COLON
 
-        http_11 = if env[HTTP_VERSION] == HTTP_11
+        http_11 = env[HTTP_VERSION] == HTTP_11
+        if http_11
           allow_chunked = true
           keep_alive = env.fetch(HTTP_CONNECTION, "").downcase != CLOSE
-          include_keepalive_header = false
 
           # An optimization. The most common response is 200, so we can
           # reply with the proper 200 status without having to compute
@@ -629,11 +628,9 @@ def handle_request(req, lines)
 
             no_body ||= status < 200 || STATUS_WITH_NO_ENTITY_BODY[status]
           end
-          true
         else
           allow_chunked = false
           keep_alive = env.fetch(HTTP_CONNECTION, "").downcase == KEEP_ALIVE
-          include_keepalive_header = keep_alive
 
           # Same optimization as above for HTTP/1.1
           #
@@ -645,9 +642,12 @@ def handle_request(req, lines)
 
             no_body ||= status < 200 || STATUS_WITH_NO_ENTITY_BODY[status]
           end
-          false
         end
 
+        # regardless of what the client wants, we always close the connection
+        # if running without request queueing
+        keep_alive &&= @queue_requests
+
         response_hijack = nil
 
         headers.each do |k, vs|
@@ -674,10 +674,15 @@ def handle_request(req, lines)
           end
         end
 
-        if include_keepalive_header
-          lines << CONNECTION_KEEP_ALIVE
-        elsif http_11 && !keep_alive
-          lines << CONNECTION_CLOSE
+        # HTTP/1.1 & 1.0 assume different defaults:
+        # - HTTP 1.0 assumes the connection will be closed if not specified
+        # - HTTP 1.1 assumes the connection will be kept alive if not specified.
+        # Only set the header if we're doing something which is not the default
+        # for this protocol version
+        if http_11
+          lines << CONNECTION_CLOSE if !keep_alive
+        else
+          lines << CONNECTION_KEEP_ALIVE if keep_alive
         end
 
         if no_body

test/test_puma_server.rb

@@ -1,4 +1,6 @@
 require_relative "helper"
+require "puma/events"
+require "net/http"
 
 class TestPumaServer < Minitest::Test
   parallelize_me!
@@ -880,4 +882,43 @@ def assert_does_not_allow_http_injection(app, opts = {})
       assert_does_not_allow_http_injection(app)
     end
   end
+
+  def test_http11_connection_header_queue
+    server_run app: ->(_) { [200, {}, [""]] }
+
+    sock = send_http "GET / HTTP/1.1\r\n\r\n"
+    assert_equal ["HTTP/1.1 200 OK", "Content-Length: 0"], header(sock)
+
+    sock << "GET / HTTP/1.1\r\nConnection: close\r\n\r\n"
+    assert_equal ["HTTP/1.1 200 OK", "Connection: close", "Content-Length: 0"], header(sock)
+
+    sock.close
+  end
+
+  def test_http10_connection_header_queue
+    server_run app: ->(_) { [200, {}, [""]] }
+
+    sock = send_http "GET / HTTP/1.0\r\nConnection: keep-alive\r\n\r\n"
+    assert_equal ["HTTP/1.0 200 OK", "Connection: Keep-Alive", "Content-Length: 0"], header(sock)
+
+    sock << "GET / HTTP/1.0\r\n\r\n"
+    assert_equal ["HTTP/1.0 200 OK", "Content-Length: 0"], header(sock)
+    sock.close
+  end
+
+  def test_http11_connection_header_no_queue
+    @server = Puma::Server.new @app, @events, queue_requests: false
+    server_run app: ->(_) { [200, {}, [""]] }
+    sock = send_http "GET / HTTP/1.1\r\n\r\n"
+    assert_equal ["HTTP/1.1 200 OK", "Connection: close", "Content-Length: 0"], header(sock)
+    sock.close
+  end
+
+  def test_http10_connection_header_no_queue
+    @server = Puma::Server.new @app, @events, queue_requests: false
+    server_run app: ->(_) { [200, {}, [""]] }
+    sock = send_http "GET / HTTP/1.0\r\n\r\n"
+    assert_equal ["HTTP/1.0 200 OK", "Content-Length: 0"], header(sock)
+    sock.close
+  end
 end