ldb: added ldb_dn_minimise()

this removes any extraneous components from a DN. For an extended DN,
this means removing the string DN and all but the first extended
component.

This is needed as AD returns "invalid syntax" if you don't use
a minimal DN as the base DN for a search. A non-minimal DN also
doesn't ever match in a search expression.

Pair-Programmed-With: Andrew Bartlett <abartlet@samba.org>

2 files changed, 64 insertions, 0 deletions

diff --git a/source4/lib/ldb/common/ldb_dn.c b/source4/lib/ldb/common/ldb_dn.c
index 07594551ea..d5442e410e 100644
--- a/source4/lib/ldb/common/ldb_dn.c
+++ b/source4/lib/ldb/common/ldb_dn.c
@@ -2045,3 +2045,57 @@ int ldb_dn_update_components(struct ldb_dn *dn, const struct ldb_dn *ref_dn)
 
 	return LDB_SUCCESS;
 }
+
+/*
+  minimise a DN. The caller must pass in a validated DN.
+
+  If the DN has an extended component then only the first extended
+  component is kept, the DN string is stripped.
+
+  The existing dn is modified
+ */
+bool ldb_dn_minimise(struct ldb_dn *dn)
+{
+	int i;
+
+	if (!ldb_dn_validate(dn)) {
+		return false;
+	}
+	if (dn->ext_comp_num == 0) {
+		return true;
+	}
+
+	/* free components */
+	for (i = 0; i < dn->comp_num; i++) {
+		LDB_FREE(dn->components[i].name);
+		LDB_FREE(dn->components[i].value.data);
+		LDB_FREE(dn->components[i].cf_name);
+		LDB_FREE(dn->components[i].cf_value.data);
+	}
+	dn->comp_num = 0;
+	dn->valid_case = false;
+
+	LDB_FREE(dn->casefold);
+	LDB_FREE(dn->linearized);
+
+	/* note that we don't free dn->components as this there are
+	 * several places in ldb_dn.c that rely on it being non-NULL
+	 * for an exploded DN
+	 */
+
+	for (i = 1; i < dn->ext_comp_num; i++) {
+		LDB_FREE(dn->ext_components[i].name);
+		LDB_FREE(dn->ext_components[i].value.data);
+	}
+	dn->ext_comp_num = 1;
+
+	dn->ext_components = talloc_realloc(dn, dn->ext_components, struct ldb_dn_ext_component, 1);
+	if (dn->ext_components == NULL) {
+		ldb_dn_mark_invalid(dn);
+		return false;
+	}
+
+	LDB_FREE(dn->ext_linearized);
+
+	return true;
+}
diff --git a/source4/lib/ldb/include/ldb.h b/source4/lib/ldb/include/ldb.h
index e7f7ebba46..4b1a5fb708 100644
--- a/source4/lib/ldb/include/ldb.h
+++ b/source4/lib/ldb/include/ldb.h
@@ -2172,4 +2172,14 @@ const char *ldb_req_location(struct ldb_request *req);
 /* set the location marker on a request handle - used for debugging */
 #define LDB_REQ_SET_LOCATION(req) ldb_req_set_location(req, __location__)
 
+/*
+  minimise a DN. The caller must pass in a validated DN.
+
+  If the DN has an extended component then only the first extended
+  component is kept, the DN string is stripped.
+
+  The existing dn is modified
+ */
+bool ldb_dn_minimise(struct ldb_dn *dn);
+
 #endif