From bc431fceb64396f190508c9aa829eec39a9329f3 Mon Sep 17 00:00:00 2001
From: Andrew Svetlov <andrew.svetlov@gmail.com>
Date: Sat, 29 Aug 2015 13:30:34 -0400
Subject: [PATCH 1/9] Add skip_auto_headers parameter

---
 aiohttp/client.py            | 11 +++++++++--
 aiohttp/client_reqrep.py     | 26 ++++++++++++++++++++++----
 aiohttp/protocol.py          |  5 -----
 tests/test_client_request.py | 20 ++++++++++++++++++++
 tests/test_http_protocol.py  | 16 ----------------
 5 files changed, 51 insertions(+), 27 deletions(-)

diff --git a/aiohttp/client.py b/aiohttp/client.py
index dc0a8b176c8..cd3d0b3b95a 100644
--- a/aiohttp/client.py
+++ b/aiohttp/client.py
@@ -32,7 +32,8 @@ class ClientSession:
     _connector = None
 
     def __init__(self, *, connector=None, loop=None, cookies=None,
-                 headers=None, auth=None, request_class=ClientRequest,
+                 headers=None, skip_auto_headers=None,
+                 auth=None, request_class=ClientRequest,
                  response_class=ClientResponse,
                  ws_response_class=ClientWebSocketResponse):
 
@@ -65,6 +66,10 @@ def __init__(self, *, connector=None, loop=None, cookies=None,
         else:
             headers = CIMultiDict()
         self._default_headers = headers
+        if skip_auto_headers is not None:
+            self._skip_auto_headers = frozenset(skip_auto_headers)
+        else:
+            self._skip_auto_headers = frozenset()
 
         self._request_class = request_class
         self._response_class = response_class
@@ -88,6 +93,7 @@ def request(self, method, url, *,
                 params=None,
                 data=None,
                 headers=None,
+                skip_auto_headers=None,
                 files=None,
                 auth=None,
                 allow_redirects=True,
@@ -121,7 +127,8 @@ def request(self, method, url, *,
 
         while True:
             req = self._request_class(
-                method, url, params=params, headers=headers, data=data,
+                method, url, params=params, headers=headers,
+                skip_auto_headers=skip_auto_headers, data=data,
                 cookies=self.cookies, files=files, encoding=encoding,
                 auth=auth, version=version, compress=compress, chunked=chunked,
                 expect100=expect100,
diff --git a/aiohttp/client_reqrep.py b/aiohttp/client_reqrep.py
index 9b235c62604..cafcbac341f 100644
--- a/aiohttp/client_reqrep.py
+++ b/aiohttp/client_reqrep.py
@@ -18,8 +18,10 @@
 from . import hdrs, helpers, streams
 from .log import client_logger
 from .streams import EOF_MARKER, FlowControlStreamReader
-from .multidict import CIMultiDictProxy, MultiDictProxy, MultiDict, CIMultiDict
+from .multidict import (CIMultiDictProxy, MultiDictProxy, MultiDict,
+                        CIMultiDict, upstr)
 from .multipart import MultipartWriter
+from .protocol import HttpMessage
 
 PY_341 = sys.version_info >= (3, 4, 1)
 
@@ -39,6 +41,8 @@ class ClientRequest:
         hdrs.ACCEPT_ENCODING: 'gzip, deflate',
     }
 
+    SERVER_SOFTWARE = HttpMessage.SERVER_SOFTWARE
+
     body = b''
     auth = None
     response = None
@@ -53,7 +57,8 @@ class ClientRequest:
     # Until writer has finished finalizer will not be called.
 
     def __init__(self, method, url, *,
-                 params=None, headers=None, data=None, cookies=None,
+                 params=None, headers=None, skip_auto_headers=None,
+                 data=None, cookies=None,
                  files=None, auth=None, encoding='utf-8',
                  version=aiohttp.HttpVersion11, compress=None,
                  chunked=None, expect100=False,
@@ -77,6 +82,7 @@ def __init__(self, method, url, *,
         self.update_host(url)
         self.update_path(params)
         self.update_headers(headers)
+        self.update_auto_headers(skip_auto_headers)
         self.update_cookies(cookies)
         self.update_content_encoding()
         self.update_auth(auth)
@@ -191,14 +197,26 @@ def update_headers(self, headers):
             for key, value in headers:
                 self.headers.add(key, value)
 
+    def update_auto_headers(self, skip_auto_headers):
+        used_headers = set(self.headers)
+        if skip_auto_headers is not None:
+            for i in skip_auto_headers:
+                if not isinstance(i, upstr):
+                    raise ValueError(
+                        'skip_auto_headers should be set of upstr')
+                used_headers.add(i)
+
         for hdr, val in self.DEFAULT_HEADERS.items():
-            if hdr not in self.headers:
+            if hdr not in used_headers:
                 self.headers[hdr] = val
 
         # add host
-        if hdrs.HOST not in self.headers:
+        if hdrs.HOST not in used_headers:
             self.headers[hdrs.HOST] = self.netloc
 
+        if hdrs.USER_AGENT not in used_headers:
+            self.headers[hdrs.USER_AGENT] = self.SERVER_SOFTWARE
+
     def update_cookies(self, cookies):
         """Update request cookies header."""
         if not cookies:
diff --git a/aiohttp/protocol.py b/aiohttp/protocol.py
index 6fc23d1c39b..c99eb09245f 100644
--- a/aiohttp/protocol.py
+++ b/aiohttp/protocol.py
@@ -857,8 +857,3 @@ def __init__(self, transport, method, path,
         self.path = path
         self.status_line = '{0} {1} HTTP/{2[0]}.{2[1]}\r\n'.format(
             method, path, http_version)
-
-    def _add_default_headers(self):
-        super()._add_default_headers()
-
-        self.headers.setdefault(hdrs.USER_AGENT, self.SERVER_SOFTWARE)
diff --git a/tests/test_client_request.py b/tests/test_client_request.py
index ca88def9701..70cc0cc0630 100644
--- a/tests/test_client_request.py
+++ b/tests/test_client_request.py
@@ -10,6 +10,7 @@
 
 import aiohttp
 from aiohttp.client_reqrep import ClientRequest, ClientResponse
+from aiohttp.multidict import upstr
 
 PY_341 = sys.version_info >= (3, 4, 1)
 
@@ -101,6 +102,25 @@ def test_host_header(self):
         self.assertEqual(req.headers['HOST'], 'example.com:99')
         self.loop.run_until_complete(req.close())
 
+    def test_default_headers_useragent(self):
+        req = ClientRequest('get', 'http://python.org/', loop=self.loop)
+
+        self.assertNotIn('SERVER', req.headers)
+        self.assertIn('USER-AGENT', req.headers)
+
+    def test_default_headers_useragent_custom(self):
+        req = ClientRequest('get', 'http://python.org/', loop=self.loop,
+                            headers={'user-agent': 'my custom agent'})
+
+        self.assertIn('USER-Agent', req.headers)
+        self.assertEqual('my custom agent', req.headers['User-Agent'])
+
+    def test_skip_default_useragent_header(self):
+        req = ClientRequest('get', 'http://python.org/', loop=self.loop,
+                            skip_auto_headers=(upstr('user-agent'),))
+
+        self.assertNotIn('User-Agent', req.headers)
+
     def test_headers(self):
         req = ClientRequest('get', 'http://python.org/',
                             headers={'Content-Type': 'text/plain'},
diff --git a/tests/test_http_protocol.py b/tests/test_http_protocol.py
index f472026a148..b8a01aadca3 100644
--- a/tests/test_http_protocol.py
+++ b/tests/test_http_protocol.py
@@ -172,22 +172,6 @@ def test_default_headers_server(self):
 
         self.assertIn('SERVER', msg.headers)
 
-    def test_default_headers_useragent(self):
-        msg = protocol.Request(self.transport, 'GET', '/')
-        msg._add_default_headers()
-
-        self.assertNotIn('SERVER', msg.headers)
-        self.assertIn('USER-AGENT', msg.headers)
-
-    def test_default_headers_useragent_custom(self):
-        msg = protocol.Request(self.transport, 'GET', '/')
-        msg.add_headers(('user-agent', 'my custom agent'))
-        msg._add_default_headers()
-
-        headers = [r for r, _ in msg.headers.items()
-                   if r.lower() == 'user-agent']
-        self.assertEqual(len(headers), 1)
-
     def test_default_headers_chunked(self):
         msg = protocol.Response(self.transport, 200)
         msg._add_default_headers()

From 0b17644a24dfc2febaf05ffaeddfe42dd102aee4 Mon Sep 17 00:00:00 2001
From: Andrew Svetlov <andrew.svetlov@gmail.com>
Date: Sat, 29 Aug 2015 15:23:56 -0400
Subject: [PATCH 2/9] Merge passed and default skip lists for client headers

---
 aiohttp/client.py            | 10 ++++++++--
 tests/test_client_session.py | 32 +++++++++++++++++++++++++++++---
 2 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/aiohttp/client.py b/aiohttp/client.py
index cd3d0b3b95a..20feea05c07 100644
--- a/aiohttp/client.py
+++ b/aiohttp/client.py
@@ -67,7 +67,8 @@ def __init__(self, *, connector=None, loop=None, cookies=None,
             headers = CIMultiDict()
         self._default_headers = headers
         if skip_auto_headers is not None:
-            self._skip_auto_headers = frozenset(skip_auto_headers)
+            self._skip_auto_headers = frozenset([upstr(i)
+                                                 for i in skip_auto_headers])
         else:
             self._skip_auto_headers = frozenset()
 
@@ -125,10 +126,15 @@ def request(self, method, url, *,
             raise ValueError("Can't combine `Authorization` header with "
                              "`auth` argument")
 
+        skip_headers = self._skip_auto_headers
+        if skip_auto_headers is not None:
+            for i in self.skip_auto_headers:
+                skip_headers.add(upstr(i))
+
         while True:
             req = self._request_class(
                 method, url, params=params, headers=headers,
-                skip_auto_headers=skip_auto_headers, data=data,
+                skip_auto_headers=skip_headers, data=data,
                 cookies=self.cookies, files=files, encoding=encoding,
                 auth=auth, version=version, compress=compress, chunked=chunked,
                 expect100=expect100,
diff --git a/tests/test_client_session.py b/tests/test_client_session.py
index 0ef2cfb84bf..7dbd4c70e7f 100644
--- a/tests/test_client_session.py
+++ b/tests/test_client_session.py
@@ -9,7 +9,7 @@
 
 import aiohttp
 from aiohttp.client import ClientSession
-from aiohttp.multidict import MultiDict, CIMultiDict, CIMultiDictProxy
+from aiohttp.multidict import MultiDict, CIMultiDict, CIMultiDictProxy, upstr
 from aiohttp.connector import BaseConnector, TCPConnector
 from aiohttp.client_reqrep import ClientRequest, ClientResponse
 from http.cookies import SimpleCookie
@@ -141,8 +141,8 @@ def test_merge_headers_with_list_of_tuples(self):
         ]))
         session.close()
 
-    def _make_one(self):
-        session = ClientSession(loop=self.loop)
+    def _make_one(self, **kwargs):
+        session = ClientSession(loop=self.loop, **kwargs)
         params = dict(
             headers={"Authorization": "Basic ..."},
             max_redirects=2,
@@ -375,6 +375,32 @@ def test_borrow_connector_loop(self):
         session = ClientSession(connector=conn)
         self.assertIs(session._loop, self.loop)
 
+    @mock.patch("aiohttp.client.ClientSession.request")
+    def test_skip_auto_headers(self, patched):
+        session, params = self._make_one()
+        skip = [upstr('user-agent')]
+        self.run(session.get("http://example.com",
+                             skip_auto_headers=skip,
+                             **params))
+        params['skip_auto_headers'] = skip
+        self.assertTrue(patched.called, "`ClientSession.request` not called")
+        self.assertEqual(patched.call_args[1]['skip_auto_headers'], skip)
+        session.close()
+
+    @mock.patch("aiohttp.client.ClientSession.request")
+    def test_skip_auto_headers_default(self, patched):
+        skip = ['user-agent']
+        uskip = [upstr(i) for i in skip]
+        import ipdb;ipdb.set_trace()
+        session, params = self._make_one(skip_auto_headers=skip)
+        self.run(session.get("http://example.com",
+                             **params))
+        params['skip_auto_headers'] = skip
+        self.assertTrue(patched.called, "`ClientSession.request` not called")
+        print(patched.call_args)
+        self.assertEqual(patched.call_args[1]['skip_auto_headers'], uskip)
+        session.close()
+
 
 class TestCLientRequest(unittest.TestCase):
 

From b6bfb7afbe1b786ca396757c5a88c3822fc4057a Mon Sep 17 00:00:00 2001
From: Andrew Svetlov <andrew.svetlov@gmail.com>
Date: Sun, 30 Aug 2015 23:07:48 -0400
Subject: [PATCH 3/9] Write functional tests for skipping headers

---
 aiohttp/client.py                |  4 +-
 tests/test_client_functional2.py | 98 ++++++++++++++++++++++++++++++++
 tests/test_client_session.py     | 28 +--------
 3 files changed, 101 insertions(+), 29 deletions(-)
 create mode 100644 tests/test_client_functional2.py

diff --git a/aiohttp/client.py b/aiohttp/client.py
index 20feea05c07..d9525ecbfab 100644
--- a/aiohttp/client.py
+++ b/aiohttp/client.py
@@ -126,9 +126,9 @@ def request(self, method, url, *,
             raise ValueError("Can't combine `Authorization` header with "
                              "`auth` argument")
 
-        skip_headers = self._skip_auto_headers
+        skip_headers = set(self._skip_auto_headers)
         if skip_auto_headers is not None:
-            for i in self.skip_auto_headers:
+            for i in skip_auto_headers:
                 skip_headers.add(upstr(i))
 
         while True:
diff --git a/tests/test_client_functional2.py b/tests/test_client_functional2.py
new file mode 100644
index 00000000000..0b65d95be02
--- /dev/null
+++ b/tests/test_client_functional2.py
@@ -0,0 +1,98 @@
+import asyncio
+import socket
+import unittest
+
+import aiohttp
+from aiohttp import hdrs, log, web
+
+
+class TestClientFunctional2(unittest.TestCase):
+
+    def setUp(self):
+        self.handler = None
+        self.loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(None)
+        self.client = aiohttp.ClientSession(loop=self.loop)
+
+    def tearDown(self):
+        if self.handler:
+            self.loop.run_until_complete(self.handler.finish_connections())
+        self.client.close()
+        self.loop.stop()
+        self.loop.run_forever()
+        self.loop.close()
+
+    def find_unused_port(self):
+        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        s.bind(('127.0.0.1', 0))
+        port = s.getsockname()[1]
+        s.close()
+        return port
+
+    @asyncio.coroutine
+    def create_server(self):
+        app = web.Application(loop=self.loop)
+
+        port = self.find_unused_port()
+        self.handler = app.make_handler(
+            debug=True, keep_alive_on=False,
+            access_log=log.access_logger)
+        srv = yield from self.loop.create_server(
+            self.handler, '127.0.0.1', port)
+        url = "http://127.0.0.1:{}".format(port)
+        self.addCleanup(srv.close)
+        return app, srv, url
+
+    def test_auto_header_user_agent(self):
+        @asyncio.coroutine
+        def handler(request):
+            self.assertIn('aiohttp', request.headers['user-agent'])
+            return web.Response()
+
+        @asyncio.coroutine
+        def go():
+            app, srv, url = yield from self.create_server()
+            app.router.add_route('get', '/', handler)
+            resp = yield from self.client.get(url+'/')
+            self.assertEqual(200, resp.status)
+            yield from resp.release()
+
+        self.loop.run_until_complete(go())
+
+    def test_skip_auto_headers_user_agent(self):
+        @asyncio.coroutine
+        def handler(request):
+            self.assertNotIn(hdrs.USER_AGENT, request.headers)
+            return web.Response()
+
+        @asyncio.coroutine
+        def go():
+            app, srv, url = yield from self.create_server()
+            app.router.add_route('get', '/', handler)
+            resp = yield from self.client.get(url+'/',
+                                              skip_auto_headers=['user-agent'])
+            self.assertEqual(200, resp.status)
+            yield from resp.release()
+
+        self.loop.run_until_complete(go())
+
+    def test_skip_default_auto_headers_user_agent(self):
+        @asyncio.coroutine
+        def handler(request):
+            self.assertNotIn(hdrs.USER_AGENT, request.headers)
+            return web.Response()
+
+        @asyncio.coroutine
+        def go():
+            app, srv, url = yield from self.create_server()
+            app.router.add_route('get', '/', handler)
+
+            client = aiohttp.ClientSession(loop=self.loop,
+                                           skip_auto_headers=['user-agent'])
+            resp = yield from client.get(url+'/')
+            self.assertEqual(200, resp.status)
+            yield from resp.release()
+
+            client.close()
+
+        self.loop.run_until_complete(go())
diff --git a/tests/test_client_session.py b/tests/test_client_session.py
index 7dbd4c70e7f..6120da9b888 100644
--- a/tests/test_client_session.py
+++ b/tests/test_client_session.py
@@ -9,7 +9,7 @@
 
 import aiohttp
 from aiohttp.client import ClientSession
-from aiohttp.multidict import MultiDict, CIMultiDict, CIMultiDictProxy, upstr
+from aiohttp.multidict import MultiDict, CIMultiDict, CIMultiDictProxy
 from aiohttp.connector import BaseConnector, TCPConnector
 from aiohttp.client_reqrep import ClientRequest, ClientResponse
 from http.cookies import SimpleCookie
@@ -375,32 +375,6 @@ def test_borrow_connector_loop(self):
         session = ClientSession(connector=conn)
         self.assertIs(session._loop, self.loop)
 
-    @mock.patch("aiohttp.client.ClientSession.request")
-    def test_skip_auto_headers(self, patched):
-        session, params = self._make_one()
-        skip = [upstr('user-agent')]
-        self.run(session.get("http://example.com",
-                             skip_auto_headers=skip,
-                             **params))
-        params['skip_auto_headers'] = skip
-        self.assertTrue(patched.called, "`ClientSession.request` not called")
-        self.assertEqual(patched.call_args[1]['skip_auto_headers'], skip)
-        session.close()
-
-    @mock.patch("aiohttp.client.ClientSession.request")
-    def test_skip_auto_headers_default(self, patched):
-        skip = ['user-agent']
-        uskip = [upstr(i) for i in skip]
-        import ipdb;ipdb.set_trace()
-        session, params = self._make_one(skip_auto_headers=skip)
-        self.run(session.get("http://example.com",
-                             **params))
-        params['skip_auto_headers'] = skip
-        self.assertTrue(patched.called, "`ClientSession.request` not called")
-        print(patched.call_args)
-        self.assertEqual(patched.call_args[1]['skip_auto_headers'], uskip)
-        session.close()
-
 
 class TestCLientRequest(unittest.TestCase):
 

From ce4150a7bd4a8a2441eb0ef368785fb72dbac688 Mon Sep 17 00:00:00 2001
From: Andrew Svetlov <andrew.svetlov@gmail.com>
Date: Mon, 31 Aug 2015 00:22:36 -0400
Subject: [PATCH 4/9] Add skip_auto_headers check for content-type

---
 aiohttp/client_reqrep.py         |  4 ++++
 tests/test_client_functional2.py | 18 ++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/aiohttp/client_reqrep.py b/aiohttp/client_reqrep.py
index cafcbac341f..0e5c7646295 100644
--- a/aiohttp/client_reqrep.py
+++ b/aiohttp/client_reqrep.py
@@ -209,6 +209,7 @@ def update_auto_headers(self, skip_auto_headers):
         for hdr, val in self.DEFAULT_HEADERS.items():
             if hdr not in used_headers:
                 self.headers[hdr] = val
+                used_headers.add(hdr)
 
         # add host
         if hdrs.HOST not in used_headers:
@@ -217,6 +218,8 @@ def update_auto_headers(self, skip_auto_headers):
         if hdrs.USER_AGENT not in used_headers:
             self.headers[hdrs.USER_AGENT] = self.SERVER_SOFTWARE
 
+        self.skip_auto_headers = used_headers
+
     def update_cookies(self, cookies):
         """Update request cookies header."""
         if not cookies:
@@ -463,6 +466,7 @@ def send(self, writer, reader):
 
         # set default content-type
         if (self.method in self.POST_METHODS and
+                hdrs.CONTENT_TYPE not in self.skip_auto_headers and
                 hdrs.CONTENT_TYPE not in self.headers):
             self.headers[hdrs.CONTENT_TYPE] = 'application/octet-stream'
 
diff --git a/tests/test_client_functional2.py b/tests/test_client_functional2.py
index 0b65d95be02..b2c53e2cb58 100644
--- a/tests/test_client_functional2.py
+++ b/tests/test_client_functional2.py
@@ -96,3 +96,21 @@ def go():
             client.close()
 
         self.loop.run_until_complete(go())
+
+    def test_skip_auto_headers_content_type(self):
+        @asyncio.coroutine
+        def handler(request):
+            self.assertNotIn(hdrs.CONTENT_TYPE, request.headers)
+            return web.Response()
+
+        @asyncio.coroutine
+        def go():
+            app, srv, url = yield from self.create_server()
+            app.router.add_route('get', '/', handler)
+            resp = yield from self.client.get(
+                url+'/',
+                skip_auto_headers=['content-type'])
+            self.assertEqual(200, resp.status)
+            yield from resp.release()
+
+        self.loop.run_until_complete(go())

From 82efc7cd44a8fe8d59bc218b715837178eab3433 Mon Sep 17 00:00:00 2001
From: Andrew Svetlov <andrew.svetlov@gmail.com>
Date: Tue, 1 Sep 2015 22:55:18 -0400
Subject: [PATCH 5/9] Fix pep8

---
 tests/test_client_session.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/test_client_session.py b/tests/test_client_session.py
index 56aba46bb08..2f01d6d9076 100644
--- a/tests/test_client_session.py
+++ b/tests/test_client_session.py
@@ -398,6 +398,7 @@ def test_custom_req_rep(self):
         @asyncio.coroutine
         def go():
             conn = None
+
             class CustomResponse(ClientResponse):
                 @asyncio.coroutine
                 def start(self, connection, read_until_eof=False):

From b2fa1d02b289a2464d1eee7bf28b802ea0f62799 Mon Sep 17 00:00:00 2001
From: Andrew Svetlov <andrew.svetlov@gmail.com>
Date: Tue, 1 Sep 2015 23:48:53 -0400
Subject: [PATCH 6/9] Cleanup code

---
 aiohttp/client_reqrep.py     | 18 +++++-------------
 tests/test_client_request.py |  2 +-
 tests/test_client_session.py | 13 +++++++++++++
 3 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/aiohttp/client_reqrep.py b/aiohttp/client_reqrep.py
index b41601b8c20..5e7a18d891e 100644
--- a/aiohttp/client_reqrep.py
+++ b/aiohttp/client_reqrep.py
@@ -19,7 +19,7 @@
 from .log import client_logger
 from .streams import EOF_MARKER, FlowControlStreamReader
 from .multidict import (CIMultiDictProxy, MultiDictProxy, MultiDict,
-                        CIMultiDict, upstr)
+                        CIMultiDict)
 from .multipart import MultipartWriter
 from .protocol import HttpMessage
 
@@ -57,7 +57,7 @@ class ClientRequest:
     # Until writer has finished finalizer will not be called.
 
     def __init__(self, method, url, *,
-                 params=None, headers=None, skip_auto_headers=None,
+                 params=None, headers=None, skip_auto_headers=frozenset(),
                  data=None, cookies=None,
                  files=None, auth=None, encoding='utf-8',
                  version=aiohttp.HttpVersion11, compress=None,
@@ -198,18 +198,12 @@ def update_headers(self, headers):
                 self.headers.add(key, value)
 
     def update_auto_headers(self, skip_auto_headers):
-        used_headers = set(self.headers)
-        if skip_auto_headers is not None:
-            for i in skip_auto_headers:
-                if not isinstance(i, upstr):
-                    raise ValueError(
-                        'skip_auto_headers should be set of upstr')
-                used_headers.add(i)
+        self.skip_auto_headers = skip_auto_headers
+        used_headers = set(self.headers) | skip_auto_headers
 
         for hdr, val in self.DEFAULT_HEADERS.items():
             if hdr not in used_headers:
-                self.headers[hdr] = val
-                used_headers.add(hdr)
+                self.headers.add(hdr, val)
 
         # add host
         if hdrs.HOST not in used_headers:
@@ -218,8 +212,6 @@ def update_auto_headers(self, skip_auto_headers):
         if hdrs.USER_AGENT not in used_headers:
             self.headers[hdrs.USER_AGENT] = self.SERVER_SOFTWARE
 
-        self.skip_auto_headers = used_headers
-
     def update_cookies(self, cookies):
         """Update request cookies header."""
         if not cookies:
diff --git a/tests/test_client_request.py b/tests/test_client_request.py
index c361a32b404..fa7469b3b6a 100644
--- a/tests/test_client_request.py
+++ b/tests/test_client_request.py
@@ -132,7 +132,7 @@ def test_default_headers_useragent_custom(self):
 
     def test_skip_default_useragent_header(self):
         req = ClientRequest('get', 'http://python.org/', loop=self.loop,
-                            skip_auto_headers=(upstr('user-agent'),))
+                            skip_auto_headers=set([upstr('user-agent')]))
 
         self.assertNotIn('User-Agent', req.headers)
 
diff --git a/tests/test_client_session.py b/tests/test_client_session.py
index 2f01d6d9076..4445ebe030f 100644
--- a/tests/test_client_session.py
+++ b/tests/test_client_session.py
@@ -76,6 +76,19 @@ def test_init_headers_MultiDict(self):
                          ("H3", "header3")]))
         session.close()
 
+    def test_init_headers_list_of_tuples_with_duplicates(self):
+        session = ClientSession(
+            headers=[("h1", "header11"),
+                     ("h2", "header21"),
+                     ("h1", "header12")],
+            loop=self.loop)
+        self.assertEqual(
+            session._default_headers,
+            CIMultiDict([("H1", "header11"),
+                         ("H2", "header21"),
+                         ("H1", "header12")]))
+        session.close()
+
     def test_init_cookies_with_simple_dict(self):
         session = ClientSession(
             cookies={

From 568adcffcb049707d98464c85f89c77b69ac35a6 Mon Sep 17 00:00:00 2001
From: Andrew Svetlov <andrew.svetlov@gmail.com>
Date: Tue, 1 Sep 2015 23:52:56 -0400
Subject: [PATCH 7/9] More tests

---
 tests/test_client_session.py | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/tests/test_client_session.py b/tests/test_client_session.py
index 4445ebe030f..72bedeb7898 100644
--- a/tests/test_client_session.py
+++ b/tests/test_client_session.py
@@ -155,6 +155,22 @@ def test_merge_headers_with_list_of_tuples(self):
         ]))
         session.close()
 
+    def test_merge_headers_with_list_of_tuples_duplicated_names(self):
+        session = ClientSession(
+            headers={
+                "h1": "header1",
+                "h2": "header2"
+            }, loop=self.loop)
+        headers = session._prepare_headers([("h1", "v1"),
+                                            ("h1", "v2")])
+        self.assertIsInstance(headers, CIMultiDict)
+        self.assertEqual(headers, CIMultiDict([
+            ("H2", "header2"),
+            ("H1", "v1"),
+            ("H1", "v2"),
+        ]))
+        session.close()
+
     def _make_one(self, **kwargs):
         session = ClientSession(loop=self.loop, **kwargs)
         params = dict(

From 3f82d25e009de5debeee92834c9488a8a9c09b4a Mon Sep 17 00:00:00 2001
From: Andrew Svetlov <andrew.svetlov@gmail.com>
Date: Thu, 3 Sep 2015 18:06:44 -0400
Subject: [PATCH 8/9] Document skip_auto_headers parameter

---
 docs/client_reference.rst | 36 ++++++++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/docs/client_reference.rst b/docs/client_reference.rst
index 26e3c505153..cac850ddeb3 100644
--- a/docs/client_reference.rst
+++ b/docs/client_reference.rst
@@ -41,7 +41,8 @@ The client session supports context manager protocol for self closing::
 
 
 .. class:: ClientSession(*, connector=None, loop=None, cookies=None,\
-                         headers=None, auth=None, request_class=ClientRequest,\
+                         headers=None, skip_auto_headers=None, \
+                         auth=None, request_class=ClientRequest,\
                          response_class=ClientResponse, \
                          ws_response_class=ClientWebSocketResponse)
 
@@ -61,8 +62,23 @@ The client session supports context manager protocol for self closing::
 
    :param dict cookies: Cookies to send with the request (optional)
 
-   :param dict headers: HTTP Headers to send with
-                        the request (optional)
+   :param headers: HTTP Headers to send with
+                   the request (optional).
+
+                   May be either *iterable of key-value pairs* or
+                   :class:`~collections.abc.Mapping`
+                   (e.g. :class:`dict`,
+                   :class:`~aiohttp.multidict.CIMultiDict`).
+
+   :param skip_auto_headers: set of headers for which autogeneration
+      should be skipped.
+
+      *aiohttp* autogenerates headers like ``User-Agent`` or
+      ``Content-Type`` if these headers are not explicitly
+      passed. Using ``skip_auto_headers`` parameter allows to skip
+      that generation.
+
+      Iterable of :class:`str` or :class:`~aiohttp.multidict.upstr` (optional)
 
    :param aiohttp.helpers.BasicAuth auth: BasicAuth named tuple that represents
                                           HTTP Basic Authorization (optional)
@@ -106,7 +122,8 @@ The client session supports context manager protocol for self closing::
 
 
    .. coroutinemethod:: request(method, url, *, params=None, data=None,\
-                                headers=None, auth=None, allow_redirects=True,\
+                                headers=None, skip_auto_headers=None, \
+                                auth=None, allow_redirects=True,\
                                 max_redirects=10, encoding='utf-8',\
                                 version=HttpVersion(major=1, minor=1),\
                                 compress=None, chunked=None, expect100=False,\
@@ -128,6 +145,17 @@ The client session supports context manager protocol for self closing::
       :param dict headers: HTTP Headers to send with
                            the request (optional)
 
+      :param skip_auto_headers: set of headers for which autogeneration
+         should be skipped.
+
+         *aiohttp* autogenerates headers like ``User-Agent`` or
+         ``Content-Type`` if these headers are not explicitly
+         passed. Using ``skip_auto_headers`` parameter allows to skip
+         that generation.
+
+         Iterable of :class:`str` or :class:`~aiohttp.multidict.upstr`
+         (optional)
+
       :param aiohttp.helpers.BasicAuth auth: BasicAuth named tuple that
                                              represents HTTP Basic Authorization
                                              (optional)

From 5c5743e2d15520a06ee014603dad2b22d4989542 Mon Sep 17 00:00:00 2001
From: Andrew Svetlov <andrew.svetlov@gmail.com>
Date: Thu, 3 Sep 2015 18:08:18 -0400
Subject: [PATCH 9/9] Update CHANGES

---
 CHANGES.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/CHANGES.txt b/CHANGES.txt
index 9ced23a2ee0..29caca832f5 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -20,3 +20,5 @@ CHANGES
   Using `force` parameter for the method is deprecated: use `.release()` instead.
 
 * Properly requote URL's path #480
+
+* add `skip_auto_headers` parameter for client API #486