experimental IDNA-fication

vpn_slice/__main__.py

@@ -311,6 +311,11 @@ def do_post_connect(env, args):
     for ip, aliases in args.aliases.items():
         host_map.append((ip, aliases))
 
+    # convert any non-ASCII hostnames to internationalized hostnames
+    # (FIXME: is this really a sensible thing to do? Does anything besides
+    # web browsers actually understand these? OpenSSH certainly doesn't.)
+    host_map = [(ip, [providers.dns.encode_intl(n) for n in names]) for (ip, names) in host_map]
+
     # add them to /etc/hosts
     if host_map:
         providers.hosts.write_hosts(host_map, args.name)

vpn_slice/dnspython.py

@@ -70,3 +70,6 @@ def lookup_srv(self, query):
                 result.update((x.priority, x.weight, str(x.target).rstrip('.')) for x in a)
 
         return [r[2] for r in sorted(result)]
+
+    def encode_intl(self, name):
+        return from_text(name).to_text(True)

vpn_slice/provider.py

@@ -126,6 +126,15 @@ def lookup_srv(self, query):
         interpretation of these results.
         """
 
+    def encode_intl(self, hostname):
+        """Convert a potentially non-ASCII hostname to its
+        internationalized representation, for example
+        (following IDNA2003):
+        www.foobár.com -> www.xn--foobr-0qa.com"""
+        if hostname.isascii():
+            return hostname
+        raise NotImplementedError()
+
 class HostsProvider(metaclass=ABCMeta):
     @abstractmethod
     def write_hosts(self, host_map, name):