RFC 4515 - Lightweight Directory Access Protocol (LDAP): String Representation of Search Filters.
The ldap.filter module defines the following functions:
This function escapes characters in assertion_value which are special in LDAP filters. You should use this function when building LDAP filter strings from arbitrary input. escape_mode means: If 0 only special chars mentioned in RFC 4515 are escaped. If 1 all NON-ASCII chars are escaped. If 2 all chars are escaped.