Use urllib3 native chunking ability (#6226)

* Fix #3844 
* Use urllib for chunked 

---------

Co-authored-by: James Pickering <james.pickering@xml-solutions.com>
Co-authored-by: Leon Verrall <LVerrall@slb.com>

requests/adapters.py

@@ -22,7 +22,6 @@
 from urllib3.exceptions import ReadTimeoutError, ResponseError
 from urllib3.exceptions import SSLError as _SSLError
 from urllib3.poolmanager import PoolManager, proxy_from_url
-from urllib3.response import HTTPResponse
 from urllib3.util import Timeout as TimeoutSauce
 from urllib3.util import parse_url
 from urllib3.util.retry import Retry
@@ -485,63 +484,19 @@ def send(
             timeout = TimeoutSauce(connect=timeout, read=timeout)
 
         try:
-            if not chunked:
-                resp = conn.urlopen(
-                    method=request.method,
-                    url=url,
-                    body=request.body,
-                    headers=request.headers,
-                    redirect=False,
-                    assert_same_host=False,
-                    preload_content=False,
-                    decode_content=False,
-                    retries=self.max_retries,
-                    timeout=timeout,
-                )
-
-            # Send the request.
-            else:
-                if hasattr(conn, "proxy_pool"):
-                    conn = conn.proxy_pool
-
-                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_host=skip_host,
-                    )
-
-                    for header, value in request.headers.items():
-                        low_conn.putheader(header, value)
-
-                    low_conn.endheaders()
-
-                    for i in request.body:
-                        low_conn.send(hex(len(i))[2:].encode("utf-8"))
-                        low_conn.send(b"\r\n")
-                        low_conn.send(i)
-                        low_conn.send(b"\r\n")
-                    low_conn.send(b"0\r\n\r\n")
-
-                    # Receive the response from the server
-                    r = low_conn.getresponse()
-
-                    resp = HTTPResponse.from_httplib(
-                        r,
-                        pool=conn,
-                        connection=low_conn,
-                        preload_content=False,
-                        decode_content=False,
-                    )
-                except Exception:
-                    # If we hit any problems here, clean up the connection.
-                    # Then, raise so that we can handle the actual exception.
-                    low_conn.close()
-                    raise
+            resp = conn.urlopen(
+                method=request.method,
+                url=url,
+                body=request.body,
+                headers=request.headers,
+                redirect=False,
+                assert_same_host=False,
+                preload_content=False,
+                decode_content=False,
+                retries=self.max_retries,
+                timeout=timeout,
+                chunked=chunked,
+            )
 
         except (ProtocolError, OSError) as err:
             raise ConnectionError(err, request=request)