bpo-45328: Avoid failure in OSs without TCP_NODELAY support (GH-28646) (GH-28771)

Operating systems without support for TCP_NODELAY will raise an OSError
when trying to set the socket option, but the show can still go on.
(cherry picked from commit 0571b93)

Co-authored-by: rtobar <[email protected]>

Author: miss-islington

Lib/http/client.py

@@ -70,6 +70,7 @@
 
 import email.parser
 import email.message
+import errno
 import http
 import io
 import re
@@ -939,7 +940,12 @@ def connect(self):
         sys.audit("http.client.connect", self, self.host, self.port)
         self.sock = self._create_connection(
             (self.host,self.port), self.timeout, self.source_address)
-        self.sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
+        # Might fail in OSs that don't implement TCP_NODELAY
+        try:
+             self.sock.setsockopt(socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
+        except OSError as e:
+            if e.errno != errno.ENOPROTOOPT:
+                raise
 
         if self._tunnel_host:
             self._tunnel()

Misc/NEWS.d/next/Library/2021-09-30-08-22-44.bpo-45328.8Z-Q0B.rst

@@ -0,0 +1 @@
+Fixed :class:`http.client.HTTPConnection` to work properly in OSs that don't support the ``TCP_NODELAY`` socket option.