Handle IPv4-mapped IPv6 addresses

Some reverse proxy configurations pass REMOTE_ADDR
as a IPv4-mapped IPv6 address when listening on a
IPv6 socket. This patch converts such a mapped
address into a IPv4 address at all usages of
REMOTE_ADDR. It handles both, the ::ffff:192.0.2.128
format as well as the deprecated ::192.0.2.128 format.

nsupdate/api/views.py

@@ -22,6 +22,7 @@ from ..utils import log, ddns_client
 from ..main.models import Host
 from ..main.dnstools import (FQDN, update, delete, check_ip, put_ip_into_session,
                              SameIpError, DnsUpdateError, NameServerNotAvailable)
+from ..main.iptools import normalize_ip
 
 
 def Response(content):
@@ -44,7 +45,7 @@ def myip_view(request, logger=None):
     """
     # Note: keeping this as a function-based view, as it is frequently used -
     # maybe it is slightly more efficient than class-based.
-    ipaddr = request.META['REMOTE_ADDR']
+    ipaddr = normalize_ip(request.META['REMOTE_ADDR'])
     logger.debug("detected remote ip address: %s" % ipaddr)
     return Response(ipaddr)
 
@@ -64,7 +65,7 @@ class DetectIpView(View):
         # so the session cookie is not received here - thus we access it via
         # the sessionid:
         s = SessionStore(session_key=sessionid)
-        ipaddr = request.META['REMOTE_ADDR']
+        ipaddr = normalize_ip(request.META['REMOTE_ADDR'])
         # as this is NOT the session automatically established and
         # also saved by the framework, we need to use save=True here
         put_ip_into_session(s, ipaddr, save=True)
@@ -225,7 +226,7 @@ class NicUpdateView(View):
             return Response('badagent')
         ipaddr = request.GET.get('myip')
         if not ipaddr:  # None or ''
-            ipaddr = request.META.get('REMOTE_ADDR')
+            ipaddr = normalize_ip(request.META.get('REMOTE_ADDR'))
         secure = request.is_secure()
         if delete:
             return _delete(host, ipaddr, secure, logger=logger)
@@ -283,7 +284,7 @@ class AuthorizedNicUpdateView(View):
         # and logged-in usage - thus misbehaved user agents are no problem.
         ipaddr = request.GET.get('myip')
         if not ipaddr:  # None or empty string
-            ipaddr = request.META.get('REMOTE_ADDR')
+            ipaddr = normalize_ip(request.META.get('REMOTE_ADDR'))
         secure = request.is_secure()
         if delete:
             return _delete(host, ipaddr, secure, logger=logger)

nsupdate/context_processors.py

@@ -10,6 +10,7 @@ logger = logging.getLogger(__name__)
 import time
 
 from .main.dnstools import put_ip_into_session
+from .main.iptools import normalize_ip
 
 from django.conf import settings
 
@@ -36,7 +37,7 @@ def update_ips(request):
     s = request.session
     t_now = int(time.time())
     # update and keep fresh using info from the request we have anyway:
-    ipaddr = request.META['REMOTE_ADDR']
+    ipaddr = normalize_ip(request.META['REMOTE_ADDR'])
     put_ip_into_session(s, ipaddr, max_age=MAX_IP_AGE / 2)
     # remove stale data to not show outdated IPs (e.g. after losing IPv6 connectivity):
     for key in ['ipv4', 'ipv6', ]:

nsupdate/main/iptools.py

@@ -0,0 +1,17 @@
+"""
+Misc. IP tools: normalize, handle mapped addresses
+"""
+
+from netaddr import IPAddress
+
+def normalize_ip(ipaddr):
+    ipaddr = normalize_mapped_address(ipaddr)
+    return ipaddr
+
+def normalize_mapped_address(ipaddr):
+    ipaddr = IPAddress(ipaddr)
+
+    if ipaddr.is_ipv4_compat() or ipaddr.is_ipv4_mapped():
+        ipaddr = ipaddr.ipv4()
+
+    return str(ipaddr)

nsupdate/main/views.py

@@ -19,6 +19,7 @@ from django.core.exceptions import PermissionDenied
 from django.utils.timezone import now
 
 from . import dnstools
+from .iptools import normalize_ip
 
 from .forms import (CreateHostForm, EditHostForm, CreateRelatedHostForm, EditRelatedHostForm,
                     CreateDomainForm, EditDomainForm, CreateUpdaterHostConfigForm, EditUpdaterHostConfigForm)
@@ -210,7 +211,7 @@ class AddHostView(CreateView):
     def form_valid(self, form):
         self.object = form.save(commit=False)
         try:
-            dnstools.add(self.object.get_fqdn(), self.request.META['REMOTE_ADDR'])
+            dnstools.add(self.object.get_fqdn(), normalize_ip(self.request.META['REMOTE_ADDR']))
         except dnstools.Timeout:
             success, level, msg = False, messages.ERROR, 'Timeout - communicating to name server failed.'
         except dnstools.NameServerNotAvailable:
@@ -265,7 +266,7 @@ class HostView(UpdateView):
     def get_context_data(self, *args, **kwargs):
         context = super(HostView, self).get_context_data(*args, **kwargs)
         context['nav_overview'] = True
-        context['remote_addr'] = self.request.META['REMOTE_ADDR']
+        context['remote_addr'] = normalize_ip(self.request.META['REMOTE_ADDR'])
         return context