ipaserver/dcerpc.py: make PDC discovery more robust

Certain operations against AD domain controller can only be done if its
FSMO role is primary domain controller. We need to use writable DC and
PDC when creating trust and updating name suffix routing information.

https://fedorahosted.org/freeipa/ticket/4479

Reviewed-By: Sumit Bose <sbose@redhat.com>

1 files changed, 16 insertions, 5 deletions

diff --git a/ipaserver/dcerpc.py b/ipaserver/dcerpc.py
index 599326719..495c380b0 100644
--- a/ipaserver/dcerpc.py
+++ b/ipaserver/dcerpc.py
@@ -707,16 +707,19 @@ class TrustDomainInstance(object):
         binding_template=lambda x,y,z: u'%s:%s[%s]' % (x, y, z)
         return [binding_template(t, remote_host, o) for t in transports for o in options]
 
-    def retrieve_anonymously(self, remote_host, discover_srv=False):
+    def retrieve_anonymously(self, remote_host, discover_srv=False, search_pdc=False):
         """
         When retrieving DC information anonymously, we can't get SID of the domain
         """
         netrc = net.Net(creds=self.creds, lp=self.parm)
+        flags = nbt.NBT_SERVER_LDAP | nbt.NBT_SERVER_DS | nbt.NBT_SERVER_WRITABLE
+        if search_pdc:
+            flags = flags | nbt.NBT_SERVER_PDC
         try:
             if discover_srv:
-                result = netrc.finddc(domain=remote_host, flags=nbt.NBT_SERVER_LDAP | nbt.NBT_SERVER_DS)
+                result = netrc.finddc(domain=remote_host, flags=flags)
             else:
-                result = netrc.finddc(address=remote_host, flags=nbt.NBT_SERVER_LDAP | nbt.NBT_SERVER_DS)
+                result = netrc.finddc(address=remote_host, flags=flags)
         except RuntimeError, e:
             raise assess_dcerpc_exception(message=str(e))
 
@@ -727,6 +730,7 @@ class TrustDomainInstance(object):
         self.info['dns_forest'] = unicode(result.forest)
         self.info['guid'] = unicode(result.domain_uuid)
         self.info['dc'] = unicode(result.pdc_dns_name)
+        self.info['is_pdc'] = (result.server_type & nbt.NBT_SERVER_PDC) != 0
 
         # Netlogon response doesn't contain SID of the domain.
         # We need to do rootDSE search with LDAP_SERVER_EXTENDED_DN_OID control to reveal the SID
@@ -775,6 +779,13 @@ class TrustDomainInstance(object):
         self.info['sid'] = unicode(result.sid)
         self.info['dc'] = remote_host
 
+        try:
+            result = self._pipe.QueryInfoPolicy2(self._policy_handle, lsa.LSA_POLICY_INFO_ROLE)
+        except RuntimeError, (num, message):
+            raise assess_dcerpc_exception(num=num, message=message)
+
+        self.info['is_pdc'] = (result.role == lsa.LSA_ROLE_PRIMARY)
+
     def generate_auth(self, trustdom_secret):
         def arcfour_encrypt(key, data):
             c = RC4.RC4(key)
@@ -1070,9 +1081,9 @@ class TrustDomainJoins(object):
         rd.creds.set_anonymous()
         rd.creds.set_workstation(self.local_domain.hostname)
         if realm_server is None:
-            rd.retrieve_anonymously(realm, discover_srv=True)
+            rd.retrieve_anonymously(realm, discover_srv=True, search_pdc=True)
         else:
-            rd.retrieve_anonymously(realm_server, discover_srv=False)
+            rd.retrieve_anonymously(realm_server, discover_srv=False, search_pdc=True)
         rd.read_only = True
         if realm_admin and realm_passwd:
             if 'name' in rd.info: