Send only one Host header in chunked request

AUTHORS.rst

@@ -191,3 +191,4 @@ Patches and Suggestions
 - "Dull Bananas" <[email protected]> (`@dullbananas <https://github.com/dullbananas>`_)
 - Alessio Izzo (`@aless10 <https://github.com/aless10>`_)
 - Sylvain Marié (`@smarie <https://github.com/smarie>`_)
+- Hod Bin Noon (`@hodbn <https://github.com/hodbn>`_)

requests/adapters.py

@@ -458,9 +458,11 @@ def send(self, request, stream=False, timeout=None, verify=True, cert=None, prox
                 low_conn = conn._get_conn(timeout=DEFAULT_POOL_TIMEOUT)
 
                 try:
+                    skip_host = 'Host' in request.headers
                     low_conn.putrequest(request.method,
                                         url,
-                                        skip_accept_encoding=True)
+                                        skip_accept_encoding=True,
+                                        skip_host=skip_host)
 
                     for header, value in request.headers.items():
                         low_conn.putheader(header, value)

tests/test_lowlevel.py

@@ -9,6 +9,18 @@
 from .utils import override_environ
 
 
+def echo_response_handler(sock):
+    """Simple handler that will take request and echo it back to requester."""
+    request_content = consume_socket_content(sock, timeout=0.5)
+
+    text_200 = (
+        b'HTTP/1.1 200 OK\r\n'
+        b'Content-Length: %d\r\n\r\n'
+        b'%s'
+    ) % (len(request_content), request_content)
+    sock.send(text_200)
+
+
 def test_chunked_upload():
     """can safely send generators"""
     close_server = threading.Event()
@@ -46,6 +58,42 @@ def incomplete_chunked_response_handler(sock):
         close_server.set()  # release server block
 
 
+def test_chunked_upload_uses_only_specified_host_header():
+    """Ensure we use only the specified Host header for chunked requests."""
+    close_server = threading.Event()
+    server = Server(echo_response_handler, wait_to_close_event=close_server)
+
+    data = iter([b'a', b'b', b'c'])
+    custom_host = 'sample-host'
+
+    with server as (host, port):
+        url = 'http://{}:{}/'.format(host, port)
+        r = requests.post(url, data=data, headers={'Host': custom_host}, stream=True)
+        close_server.set()  # release server block
+
+    expected_header = b'Host: %s\r\n' % custom_host.encode('utf-8')
+    assert expected_header in r.content
+    assert r.content.count(b'Host: ') == 1
+
+
+def test_chunked_upload_doesnt_skip_host_header():
+    """Ensure we don't omit all Host headers with chunked requests."""
+    close_server = threading.Event()
+    server = Server(echo_response_handler, wait_to_close_event=close_server)
+
+    data = iter([b'a', b'b', b'c'])
+
+    with server as (host, port):
+        expected_host = '{}:{}'.format(host, port)
+        url = 'http://{}:{}/'.format(host, port)
+        r = requests.post(url, data=data, stream=True)
+        close_server.set()  # release server block
+
+    expected_header = b'Host: %s\r\n' % expected_host.encode('utf-8')
+    assert expected_header in r.content
+    assert r.content.count(b'Host: ') == 1
+
+
 def test_conflicting_content_lengths():
     """Ensure we correctly throw an InvalidHeader error if multiple
     conflicting Content-Length headers are returned.