PYTHON-1350 - Work around getsockopt issue on NetBSD

NetBSD doesn't support testing TCP_KEEPIDLE and friends,
only setting them.

doc/changelog.rst

@@ -1,6 +1,21 @@
 Changelog
 =========
 
+Changes in Version 3.5.1
+------------------------
+
+Version 3.5.1 fixes bugs reported since the release of 3.5.0:
+
+- Work around socket.getsockopt issue with NetBSD.
+
+Issues Resolved
+...............
+
+See the `PyMongo 3.5.1 release notes in JIRA`_ for the list of resolved issues
+in this release.
+
+.. _PyMongo 3.5.1 release notes in JIRA: https://jira.mongodb.org/projects/PYTHON/versions/18721
+
 Changes in Version 3.5
 ----------------------
 

pymongo/pool.py

@@ -150,9 +150,15 @@ else:
     def _set_tcp_option(sock, tcp_option, max_value):
         if hasattr(socket, tcp_option):
             sockopt = getattr(socket, tcp_option)
-            default = sock.getsockopt(socket.SOL_TCP, sockopt)
-            if default > max_value:
-                sock.setsockopt(socket.SOL_TCP, sockopt, max_value)
+            try:
+                # PYTHON-1350 - NetBSD doesn't implement getsockopt for
+                # TCP_KEEPIDLE and friends. Don't attempt to set the
+                # values there.
+                default = sock.getsockopt(socket.IPPROTO_TCP, sockopt)
+                if default > max_value:
+                    sock.setsockopt(socket.IPPROTO_TCP, sockopt, max_value)
+            except socket.error:
+                pass
 
     def _set_keepalive_times(sock):
         _set_tcp_option(sock, 'TCP_KEEPIDLE', _MAX_TCP_KEEPIDLE)