Merge pull request #72 from josmo/allow-vpn-dns-for-domains

MacOS implementation of domain specific use of vpn dns

vpn_slice/__main__.py

@@ -42,14 +42,15 @@ def get_default_providers():
             prep = CheckTunDevProvider,
         )
     elif platform.startswith('darwin'):
-        from .mac import PsProvider, BSDRouteProvider
+        from .mac import PsProvider, BSDRouteProvider, MacSplitDNSProvider
         from .posix import PosixHostsFileProvider
         from .dnspython import DNSPythonProvider
         return dict(
             process = PsProvider,
             route = BSDRouteProvider,
             dns = DNSPythonProvider or DigProvider,
             hosts = PosixHostsFileProvider,
+            domain_vpn_dns = MacSplitDNSProvider,
         )
     elif platform.startswith('freebsd'):
         from .mac import BSDRouteProvider
@@ -134,6 +135,13 @@ def do_disconnect(env, args):
         except sp.CalledProcessError:
             print("WARNING: failed to deconfigure firewall for VPN interface (%s)" % env.tundev, file=stderr)
 
+    if args.vpn_domains is not None:
+        try:
+            providers.domain_vpn_dns.deconfigure_domain_vpn_dns(args.vpn_domains, env.dns)
+        except:
+            print("WARNING: failed to deconfigure domains vpn dns", file=stderr)
+
+
 def do_connect(env, args):
     global providers
     if args.banner and env.banner:
@@ -219,6 +227,14 @@ def do_connect(env, args):
         if args.verbose:
             print("Restored routes for %d excluded subnets." % len(exc_subnets), exc_subnets, file=stderr)
 
+    # Use vpn dns for provided domains
+    if args.vpn_domains is not None:
+        if 'domain_vpn_dns' not in providers:
+            print("WARNING: no split dns provider available; can't split dns", file=stderr)
+        else:
+            providers.domain_vpn_dns.configure_domain_vpn_dns(args.vpn_domains, env.dns)
+
+
 def do_post_connect(env, args):
     global providers
     # lookup named hosts for which we need routes and/or host_map entries
@@ -429,6 +445,7 @@ def parse_args_and_env(args=None, environ=os.environ):
     g.add_argument('-D','--dump', action='store_true', help='Dump environment variables passed by caller')
     g.add_argument('--no-fork', action='store_false', dest='fork', help="Don't fork and continue in background on connect")
     g.add_argument('--ppid', type=int, help='PID of calling process (normally autodetected, when using openconnect or vpnc)')
+    g.add_argument('--domains-vpn-dns', dest='vpn_domains', default=None, help="comma seperated domains to query with vpn dns")
     args = p.parse_args(args)
     env = parse_env(environ)
     return p, args, env
@@ -470,6 +487,9 @@ def finalize_args_and_env(args, env):
     if args.route_splits:
         args.subnets.extend(env.splitinc)
         args.exc_subnets.extend(env.splitexc)
+    if args.vpn_domains is not None:
+        args.vpn_domains = str.split(args.vpn_domains, ',')
+
 
 def main(args=None, environ=os.environ):
     global providers

vpn_slice/mac.py

@@ -4,7 +4,7 @@
 from ipaddress import ip_network, ip_interface
 
 from .posix import PosixProcessProvider
-from .provider import RouteProvider
+from .provider import RouteProvider, SplitDNSProvider
 from .util import get_executable
 
 
@@ -112,3 +112,22 @@ def add_address(self, device, address):
             # with BSD ifconfig. See example in default vpnc-script:
             #   https://gitlab.com/openconnect/vpnc-scripts/blob/https://gitlab.com/openconnect/vpnc-scripts/blob/921e8760/vpnc-script#L193
             self._ifconfig(device, 'inet', address.ip, address.ip, 'netmask', '255.255.255.255')
+
+
+class MacSplitDNSProvider(SplitDNSProvider):
+    def configure_domain_vpn_dns(self, domains, nameservers):
+        if not os.path.exists('/etc/resolver'):
+            os.makedirs('/etc/resolver')
+        for domain in domains:
+            resolver_file_name = "/etc/resolver/{0}".format(domain)
+            with open(resolver_file_name, "w") as resolver_file:
+                for nameserver in nameservers:
+                    resolver_file.write("nameserver {}\n".format(nameserver))
+
+    def deconfigure_domain_vpn_dns(self, domains, nameservers):
+        for domain in domains:
+            resolver_file_name = "/etc/resolver/{0}".format(domain)
+            if os.path.exists(resolver_file_name):
+                os.remove(resolver_file_name)
+        if not len(os.listdir('/etc/resolver')):
+            os.removedirs('/etc/resolver')

vpn_slice/provider.py

@@ -143,3 +143,18 @@ def prepare_tunnel(self):
         Base class behavior is to do nothing.
 
         """
+
+class SplitDNSProvider:
+    def configure_domain_vpn_dns(self, domains, nameservers):
+        """Configure domain vpn dns.
+
+        Base class behavior is to do nothing.
+
+        """
+
+    def deconfigure_domain_vpn_dns(self, domains, nameservers):
+        """Remove domain vpn dns.
+
+        Base class behavior is to do nothing.
+
+        """