differentiate between limit types when LDAP search exceeds configured limits

When LDAP search fails on exceeded limits, we should raise an specific
exception for the type of limit raised (size, time, administrative) so that
the consumer can distinguish between e.g. searches returning too many entries
and those timing out.

https://fedorahosted.org/freeipa/ticket/5677

Reviewed-By: Petr Spacek <pspacek@redhat.com>

1 files changed, 50 insertions, 18 deletions

diff --git a/ipapython/ipaldap.py b/ipapython/ipaldap.py
index 2965ba4a5..405f1ee2f 100644
--- a/ipapython/ipaldap.py
+++ b/ipapython/ipaldap.py
@@ -60,6 +60,11 @@ AUTOBIND_AUTO = 1
 AUTOBIND_ENABLED = 2
 AUTOBIND_DISABLED = 3
 
+TRUNCATED_SIZE_LIMIT = object()
+TRUNCATED_TIME_LIMIT = object()
+TRUNCATED_ADMIN_LIMIT = object()
+
+
 def unicode_from_utf8(val):
     '''
     val is a UTF-8 encoded string, return a unicode object.
@@ -971,11 +976,11 @@ class LDAPClient(object):
         except ldap.OBJECT_CLASS_VIOLATION:
             raise errors.ObjectclassViolation(info=info)
         except ldap.ADMINLIMIT_EXCEEDED:
-            raise errors.LimitsExceeded()
+            raise errors.AdminLimitExceeded()
         except ldap.SIZELIMIT_EXCEEDED:
-            raise errors.LimitsExceeded()
+            raise errors.SizeLimitExceeded()
         except ldap.TIMELIMIT_EXCEEDED:
-            raise errors.LimitsExceeded()
+            raise errors.TimeLimitExceeded()
         except ldap.NOT_ALLOWED_ON_RDN:
             raise errors.NotAllowedOnRDN(attr=info)
         except ldap.FILTER_ERROR:
@@ -1003,6 +1008,20 @@ class LDAPClient(object):
                 'Unhandled LDAPError: %s: %s' % (type(e).__name__, str(e)))
             raise errors.DatabaseError(desc=desc, info=info)
 
+    @staticmethod
+    def handle_truncated_result(truncated):
+        if not truncated:
+            return
+
+        if truncated is TRUNCATED_ADMIN_LIMIT:
+            raise errors.AdminLimitExceeded()
+        elif truncated is TRUNCATED_SIZE_LIMIT:
+            raise errors.SizeLimitExceeded()
+        elif truncated is TRUNCATED_TIME_LIMIT:
+            raise errors.TimeLimitExceeded()
+        else:
+            raise errors.LimitsExceeded()
+
     @property
     def schema(self):
         """schema associated with this LDAP server"""
@@ -1249,7 +1268,7 @@ class LDAPClient(object):
         return self.combine_filters(flts, rules)
 
     def get_entries(self, base_dn, scope=ldap.SCOPE_SUBTREE, filter=None,
-                    attrs_list=None):
+                    attrs_list=None, **kwargs):
         """Return a list of matching entries.
 
         :raises: errors.LimitsExceeded if the list is truncated by the server
@@ -1260,13 +1279,21 @@ class LDAPClient(object):
         :param scope: search scope, see LDAP docs (default ldap2.SCOPE_SUBTREE)
         :param filter: LDAP filter to apply
         :param attrs_list: ist of attributes to return, all if None (default)
-
-        Use the find_entries method for more options.
+        :param kwargs: additional keyword arguments. See find_entries method
+        for their description.
         """
         entries, truncated = self.find_entries(
             base_dn=base_dn, scope=scope, filter=filter, attrs_list=attrs_list)
-        if truncated:
-            raise errors.LimitsExceeded()
+        try:
+            self.handle_truncated_result(truncated)
+        except errors.LimitsExceeded as e:
+            self.log.error(
+                "{} while getting entries (base DN: {}, filter: {})".format(
+                    e, base_dn, filter
+                )
+            )
+            raise
+
         return entries
 
     def find_entries(self, filter=None, attrs_list=None, base_dn=None,
@@ -1357,6 +1384,15 @@ class LDAPClient(object):
                                 break
                         else:
                             cookie = ''
+                except ldap.ADMINLIMIT_EXCEEDED:
+                    truncated = TRUNCATED_ADMIN_LIMIT
+                    break
+                except ldap.SIZELIMIT_EXCEEDED:
+                    truncated = TRUNCATED_SIZE_LIMIT
+                    break
+                except ldap.TIMELIMIT_EXCEEDED:
+                    truncated = TRUNCATED_TIME_LIMIT
+                    break
                 except ldap.LDAPError as e:
                     # If paged search is in progress, try to cancel it
                     if paged_search and cookie:
@@ -1402,15 +1438,13 @@ class LDAPClient(object):
 
         search_kw = {attr: value, 'objectClass': object_class}
         filter = self.make_filter(search_kw, rules=self.MATCH_ALL)
-        (entries, truncated) = self.find_entries(filter, attrs_list, base_dn)
+        entries = self.get_entries(
+            base_dn, filter=filter, attrs_list=attrs_list)
 
         if len(entries) > 1:
             raise errors.SingleMatchExpected(found=len(entries))
-        else:
-            if truncated:
-                raise errors.LimitsExceeded()
-            else:
-                return entries[0]
+
+        return entries[0]
 
     def get_entry(self, dn, attrs_list=None, time_limit=None,
                   size_limit=None):
@@ -1423,13 +1457,11 @@ class LDAPClient(object):
 
         assert isinstance(dn, DN)
 
-        (entries, truncated) = self.find_entries(
-            None, attrs_list, dn, self.SCOPE_BASE, time_limit=time_limit,
+        entries = self.get_entries(
+            dn, self.SCOPE_BASE, None, attrs_list, time_limit=time_limit,
             size_limit=size_limit
         )
 
-        if truncated:
-            raise errors.LimitsExceeded()
         return entries[0]
 
     def add_entry(self, entry):