fix for leftover data with interrupted persistent connections

Thanks to @pje for disclosure, initial patch, and input

Author: geemus

lib/excon/connection.rb

@@ -262,6 +262,11 @@ def request(params={}, &block)
 
       datum[:connection] = self
 
+      # cleanup data left behind on persistent connection after interrupt
+      if datum[:persistent] && !@persistent_socket_reusable
+        reset
+      end
+
       datum[:stack] = datum[:middlewares].map do |middleware|
         lambda {|stack| middleware.new(stack)}
       end.reverse.inject(self) do |middlewares, middleware|
@@ -270,7 +275,9 @@ def request(params={}, &block)
       datum = datum[:stack].request_call(datum)
 
       unless datum[:pipeline]
+        @persistent_socket_reusable = false
         datum = response(datum)
+        @persistent_socket_reusable = true
 
         if datum[:persistent]
           if key = datum[:response][:headers].keys.detect {|k| k.casecmp('Connection') == 0 }
@@ -344,6 +351,7 @@ def reset
       if old_socket = sockets.delete(@socket_key)
         old_socket.close rescue nil
       end
+      @persistent_socket_reusable = true
     end
 
     # Generate HTTP request verb methods

tests/connection_tests.rb

@@ -14,6 +14,29 @@
       connection.send(:socket) # creates/connects socket
       connection.data[:remote_ip]
     end
+
+    tests("persistent connections") do
+      connection = Excon.new('http://127.0.0.1:9292', persistent: true)
+
+      response_body = connection.request(path: '/foo', method: 'get').body
+      test("successful uninterrupted request") do
+        connection.request(path: '/foo', method: 'get').body == 'foo'
+      end
+
+      begin
+        # simulate an interrupted connection which leaves data behind
+        Timeout::timeout(0.0000000001) do
+          connection.request(path: '/foo', method: 'get')
+        end
+      rescue Timeout::Error
+        nil
+      end
+
+      test("resets connection after interrupt") do
+        response = connection.request(path: '/bar', method: 'get')
+        response.body == 'bar'
+      end
+    end
   end
 
   tests("inspect redaction") do

tests/rackups/basic.rb

@@ -32,6 +32,14 @@ class Basic < Sinatra::Base
     echo
   end
 
+  get('/foo') do
+    'foo'
+  end
+
+  get('/bar') do
+    'bar'
+  end
+
   private
 
   def echo