diff --git a/lib/evil-proxy/agentproxy.rb b/lib/evil-proxy/agentproxy.rb
index 2652194..fe1369c 100644
--- a/lib/evil-proxy/agentproxy.rb
+++ b/lib/evil-proxy/agentproxy.rb
@@ -13,38 +13,57 @@ def fire key, *args
     @mitm_server.fire key, *args, self
   end
 
-  def perform_proxy_request(req, res)
+  def perform_proxy_request(req, res, req_class, body_stream = nil)
     uri = req.request_uri
     path = uri.path.dup
     path << "?" << uri.query if uri.query
-    header = Hash.new
-    choose_header(req, header)
-    response = nil
+    header = setup_proxy_header(req, res)
+    upstream = setup_upstream_proxy_authentication(req, res, header)
 
-    http = Net::HTTP.new(uri.host, uri.port)
+    body_tmp = []
+    http = Net::HTTP.new(uri.host, uri.port, upstream.host, upstream.port)
     http.use_ssl = true
     http.verify_mode = OpenSSL::SSL::VERIFY_NONE
-    http.start do
-      if @config[:ProxyTimeout]
-        ##################################   these issues are
-        http.open_timeout = 30   # secs  #   necessary (maybe because
-        http.read_timeout = 60   # secs  #   Ruby's bug, but why?)
-        ##################################
-      end
+    req_fib = Fiber.new do
+      http.start do
+        if @config[:ProxyTimeout]
+          ##################################   these issues are
+          http.open_timeout = 30   # secs  #   necessary (maybe because
+          http.read_timeout = 60   # secs  #   Ruby's bug, but why?)
+          ##################################
+        end
+        if body_stream && req['transfer-encoding'] =~ /\bchunked\b/i
+          header['Transfer-Encoding'] = 'chunked'
+        end
+        http_req = req_class.new(path, header)
+        http_req.body_stream = body_stream if body_stream
+        http.request(http_req) do |response|
+          # Persistent connection requirements are mysterious for me.
+          # So I will close the connection in every response.
+          res['proxy-connection'] = "close"
+          res['connection'] = "close"
 
-      response = yield(http, path, header)
+          # stream Net::HTTP::HTTPResponse to WEBrick::HTTPResponse
+          res.status = response.code.to_i
+          res.chunked = response.chunked?
+          choose_header(response, res)
+          set_cookie(response, res)
+          set_via(res)
+          response.read_body do |buf|
+            body_tmp << buf
+            Fiber.yield # wait for res.body Proc#call
+          end
+        end # http.request
+      end
+    end
+    req_fib.resume # read HTTP response headers and first chunk of the body
+    res.body = ->(socket) do
+      while buf = body_tmp.shift
+        socket.write(buf)
+        buf.clear
+        req_fib.resume # continue response.read_body
+      end
     end
-
-    # Persistent connection requirements are mysterious for me.
-    # So I will close the connection in every response.
-    res['proxy-connection'] = "close"
-    res['connection'] = "close"
-
-    # Convert Net::HTTP::HTTPResponse to WEBrick::HTTPResponse
-    res.status = response.code.to_i
-    choose_header(response, res)
-    set_cookie(response, res)
-    res.body = response.body
   end
 
   def service req, res
diff --git a/lib/evil-proxy/httpproxy.rb b/lib/evil-proxy/httpproxy.rb
index b099907..fe18e4a 100644
--- a/lib/evil-proxy/httpproxy.rb
+++ b/lib/evil-proxy/httpproxy.rb
@@ -69,25 +69,25 @@ def self.define_callback_methods callback
   end
 
   def do_PUT(req, res)
-    perform_proxy_request(req, res) do |http, path, header|
+    perform_proxy_request(req, res, req.class) do |http, path, header|
       http.put(path, req.body || '', header)
     end
   end
 
   def do_DELETE(req, res)
-    perform_proxy_request(req, res) do |http, path, header|
+    perform_proxy_request(req, res, req.class) do |http, path, header|
       http.delete(path, header)
     end
   end
 
   def do_PATCH(req, res)
-    perform_proxy_request(req, res) do |http, path, header|
+    perform_proxy_request(req, res, req.class) do |http, path, header|
       http.patch(path, req.body || '', header)
     end
   end
 
   def do_OPTIONS(req, res)
-    perform_proxy_request(req, res) do |http, path, header|
+    perform_proxy_request(req, res, req.class) do |http, path, header|
       http.options(path, header)
     end
   end