ipa-client assumes a single namingcontext

When LDAP server contains more that one suffixes, the ipa client
installation does not detect it as IPA server and fails to install.
Fix ipa server discovery so that it correctly searches all naming
contexts for the IPA one.

https://fedorahosted.org/freeipa/ticket/1868

ipa-client/ipaclient/ipadiscovery.py

@@ -24,7 +24,8 @@ import ipapython.dnsclient
 import tempfile
 import ldap
 from ldap import LDAPError
-from ipapython.ipautil import run, CalledProcessError, valid_ip
+from ipapython.ipautil import run, CalledProcessError, valid_ip, get_ipa_basedn, \
+                              realm_to_suffix
 
 
 NOT_FQDN = -1
@@ -176,9 +177,15 @@ class IPADiscovery:
             self.server = ldapret[1]
             self.realm = ldapret[2]
 
-        if ldapret[0] == NO_ACCESS_TO_LDAP and self.realm == None:
+        if ldapret[0] == NO_ACCESS_TO_LDAP and self.realm is None:
             # Assume realm is the same as domain.upper()
             self.realm = self.domain.upper()
+            logging.debug("Assuming realm is the same as domain: %s" % self.realm)
+
+        if ldapret[0] == NO_ACCESS_TO_LDAP and self.basedn is None:
+            # Generate suffix from realm
+            self.basedn = realm_to_suffix(self.realm)
+            logging.debug("Generate basedn from realm: %s" % self.basedn)
 
         return ldapret[0]
 
@@ -229,25 +236,14 @@ class IPADiscovery:
             lh.start_tls_s()
             lh.simple_bind_s("","")
 
-            logging.debug("Search rootdse")
-            lret = lh.search_s("", ldap.SCOPE_BASE, "(objectClass=*)")
-            for lattr in lret[0][1]:
-                if lattr.lower() == "namingcontexts":
-                    self.basedn = lret[0][1][lattr][0]
+            # get IPA base DN
+            logging.debug("Search LDAP server for IPA base DN")
+            basedn = get_ipa_basedn(lh)
 
-            logging.debug("Search for (info=*) in "+self.basedn+"(base)")
-            lret = lh.search_s(self.basedn, ldap.SCOPE_BASE, "(info=IPA*)")
-            if not lret:
+            if basedn is None:
                 return [NOT_IPA_SERVER]
-            logging.debug("Found: "+str(lret))
 
-            for lattr in lret[0][1]:
-                if lattr.lower() == "info":
-                    linfo = lret[0][1][lattr][0].lower()
-                    break
-
-            if not linfo or linfo.lower() != 'ipa v2.0':
-                return [NOT_IPA_SERVER]
+            self.basedn = basedn
 
             #search and return known realms
             logging.debug("Search for (objectClass=krbRealmContainer) in "+self.basedn+"(sub)")

ipapython/ipautil.py

@@ -22,6 +22,8 @@ PLUGINS_SHARE_DIR = "/usr/share/ipa/plugins"
 
 GEN_PWD_LEN = 12
 
+IPA_BASEDN_INFO = 'ipa v2.0'
+
 import string
 import tempfile
 import logging
@@ -33,6 +35,7 @@ import stat
 import shutil
 import urllib2
 import socket
+import ldap
 
 from ipapython import ipavalidate
 from types import *
@@ -1126,3 +1129,37 @@ def bind_port_responder(port, socket_stream=True, socket_timeout=None, responder
                 s.sendto(responder_data, addr)
     finally:
         s.close()
+
+def get_ipa_basedn(conn):
+    """
+    Get base DN of IPA suffix in given LDAP server.
+
+    None is returned if the suffix is not found
+
+    :param conn: Bound LDAP connection that will be used for searching
+    """
+    entries = conn.search_ext_s(
+        '', scope=ldap.SCOPE_BASE, attrlist=['namingcontexts']
+    )
+
+    contexts = entries[0][1]['namingcontexts']
+    for context in contexts:
+        logging.debug("Check if naming context '%s' is for IPA" % context)
+        try:
+            entry = conn.search_s(context, ldap.SCOPE_BASE, "(info=IPA*)")
+        except ldap.NO_SUCH_OBJECT:
+            logging.debug("LDAP server did not return info attribute to check for IPA version")
+            continue
+        if len(entry) == 0:
+            logging.debug("Info attribute with IPA server version not found")
+            continue
+        info = entry[0][1]['info'][0].lower()
+        if info != IPA_BASEDN_INFO:
+            logging.debug("Detected IPA server version (%s) did not match the client (%s)" \
+                % (info, IPA_BASEDN_INFO))
+            continue
+        logging.debug("Naming context '%s' is a valid IPA context" % context)
+        return context
+
+    return None
+