Reconfigure dnspython to remove nameservers on inactive interfaces.

Closes #15; Workaround for rthalley/dnspython#1191

Author: jaraco

monkey.py

@@ -0,0 +1,83 @@
+import functools
+import logging
+import platform
+import subprocess
+import sys
+
+import dns.resolver
+
+
+def get_active_windows_dns_servers():
+    """
+    Uses PowerShell to get a set of DNS Server IPs from active IPv4 interfaces.
+    """
+    return set(map(get_dns, get_interface_indexes()))
+
+
+def non_empty_lines(lines):
+    return filter(None, (line.strip() for line in lines))
+
+
+def get_interface_indexes():
+    # Get InterfaceIndex of active, physical, IPv4-enabled adapters
+    ps_command_get_indexes = (
+        "Get-NetAdapter -OperationalStatus Up -AddressFamily IPv4 -Physical | "
+        "Select-Object -ExpandProperty InterfaceIndex"
+    )
+    result_indexes = subprocess.run(
+        ["powershell", "-Command", ps_command_get_indexes],
+        capture_output=True,
+        text=True,
+        check=True,
+        timeout=5,
+    )
+    return map(int, non_empty_lines(result_indexes.stdout).splitlines())
+
+
+def get_dns(index):
+    """
+    Process the index to get DNS servers for that interface.
+    """
+    index_int = int(index.strip())
+    ps_command_get_dns = (
+        f"Get-DnsClientServerAddress -InterfaceIndex {index_int} -AddressFamily IPv4 | "
+        "Select-Object -ExpandProperty ServerAddresses"
+    )
+    result_dns = subprocess.run(
+        ["powershell", "-Command", ps_command_get_dns],
+        capture_output=True,
+        text=True,
+        check=False,
+        timeout=5,  # check=False as it errors if no servers are set
+    )
+    # Add servers to the set (handles potential multiple servers per adapter)
+    if result_dns.returncode != 0:
+        return
+
+    return non_empty_lines(result_dns.stdout)
+
+
+def patch_dnspython_resolver_config():
+    """
+    Applies the monkeypatch to dns.resolver.Resolver._config_resolver
+    to filter nameservers based on active Windows interfaces.
+
+    Workaround for coherent-oss/coherent.deps#15.
+    """
+    if platform.system() != "Windows":
+        return
+
+    resolver = dns.resolver.get_default_resolver()
+
+    original_servers = resolver.nameservers
+
+    # Get DNS servers currently configured on *active* interfaces
+    active_servers_set = get_active_windows_dns_servers()
+
+    matching_servers = active_servers_set.intersection(original_servers)
+
+    if not matching_servers:
+        # Keep the original list if no active servers found
+        return
+
+    resolver.nameservers = matching_servers

pypi.py

@@ -71,6 +71,8 @@
 from retry_requests import retry
 from zipp.compat.overlay import zipfile
 
+from . import monkey
+
 session = retry(sessions.BaseUrlSession('https://pypi.python.org/pypi/'))
 session.mount('file://', FileAdapter())
 log = logging.getLogger(__name__)
@@ -96,6 +98,7 @@ def client(username=None):
 
     Defaults to an anonymous, read-only connection if no username is supplied.
     """
+    monkey.patch_dnspython_resolver_config()
     username = username or os.environ.get('DB_USER') or 'anonymous'
     cluster = os.environ.get('DB_CLUSTER') or 'cluster0.acvlhai.mongodb.net'
     password = (