Add support for IPv6 remote hosts.

Supported sshuttle commands for IPv6:

./sshuttle -r "IPv6:addr" 0.0.0.0/0 -vv
./sshuttle -r "[IPv6:addr]" 0.0.0.0/0 -vv
./sshuttle -r "[IPv6:addr]:22" 0.0.0.0/0 -vv

Technically "invalid" address/port formats, but they can still be parsed because they’re unambiguous, so these also work:

./sshuttle -r "IPv6:addr]" 0.0.0.0/0 -vv
./sshuttle -r "IPv6:addr]:" 0.0.0.0/0 -vv
./sshuttle -r "IPv6:addr]:22" 0.0.0.0/0 -vv
./sshuttle -r "[IPv6:addr" 0.0.0.0/0 -vv

(If you have a Mac with Back To My Mac, use dns-sd to discover the remote host's IPv6 address:
dns-sd -G v4v6 <machine name>.<member name>.members.mac.com )

ssh.py

@@ -23,15 +23,33 @@ def empackage(z, filename):
 
 def connect(ssh_cmd, rhostport, python):
     main_exe = sys.argv[0]
+    portl = []
+
+    rhostIsIPv6 = False
+    if rhostport.count(':') > 1:
+        rhostIsIPv6 = True
+        if rhostport.count(']') or rhostport.count('['):
+            result = rhostport.split(']')
+            rhost = result[0].strip('[')
+            if len(result) > 1:
+                result[1] = result[1].strip(':')
+                if result[1] is not '':
+                    portl = ['-p', str(int(result[1]))]
+        else: # can't disambiguate IPv6 colons and a port number. pass the hostname through.
+            rhost = rhostport
+    else: # IPv4
         l = (rhostport or '').split(':', 1)
         rhost = l[0]
-    portl = []
         if len(l) > 1:
             portl = ['-p', str(int(l[1]))]
 
     if rhost == '-':
         rhost = None
 
+    ipv6flag = []
+    if rhostIsIPv6:
+        ipv6flag = ['-6']
+
     z = zlib.compressobj(1)
     content = readfile('assembler.py')
     content2 = (empackage(z, 'helpers.py') +
@@ -59,6 +77,7 @@ def connect(ssh_cmd, rhostport, python):
             sshl = ['ssh']
         argv = (sshl + 
                 portl + 
+                ipv6flag + 
                 [rhost, '--', "'%s' -c '%s'" % (python, pyscript)])
     (s1,s2) = socket.socketpair()
     def setup():