LDAP_GET_DN(3) OpenLDAP 2.2.23 (2005/01/24) LDAP_GET_DN(3)
NAME
ldap_get_dn, ldap_explode_dn, ldap_explode_rdn, ldap_dn2ufn
- LDAP DN handling routines
LIBRARY
OpenLDAP LDAP (libldap, -lldap)
SYNOPSIS
#include <ldap.h>
char *ldap_get_dn( LDAP *ld, LDAPMessage *entry )
int ldap_str2dn( const char *str, LDAPDN **dn, unsigned flags )
int ldap_dn2str( LDAPDN *dn, char **str, unsigned flags )
char **ldap_explode_dn( const char *dn, int notypes )
char **ldap_explode_rdn( const char *rdn, int notypes )
char *ldap_dn2ufn( const char * dn )
char *ldap_dn2dcedn( const char * dn )
char *ldap_dcedn2dn( const char * dn )
char *ldap_dn2ad_canonical( const char * dn )
DESCRIPTION
These routines allow LDAP entry names (Distinguished Names,
or DNs) to be obtained, parsed, converted to a user-friendly
form, and tested. A DN has the form described in RFC 2253
"Lightweight Directory Access Protocol (v3): UTF-8 String
Representation of Distinguished Names".
The ldap_get_dn() routine takes an entry as returned by
ldap_first_entry(3) or ldap_next_entry(3) and returns a copy
of the entry's DN. Space for the DN will be obtained
dynamically and should be freed by the caller using
ldap_memfree(3).
ldap_str2dn() parses a string representation of a
distinguished name contained in str into its components,
which are stored in dn as ldap_ava structures, arranged in
LDAPAVA, LDAPRDN, and LDAPDN terms, defined as:
typedef struct ldap_ava {
char *la_attr;
struct berval *la_value;
unsigned la_flags;
} LDAPAVA;
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LDAP_GET_DN(3) OpenLDAP 2.2.23 (2005/01/24) LDAP_GET_DN(3)
typedef LDAPAVA** LDAPRDN;
typedef LDAPRDN** LDAPDN;
The attribute types and the attribute values are not
normalized. The la_flags can be either LDAP_AVA_STRING or
LDAP_AVA_BINARY, the latter meaning that the value is
BER/DER encoded and thus must be represented as, quoting
from RFC 2253, " ... an octothorpe character ('#' ASCII 35)
followed by the hexadecimal representation of each of the
bytes of the BER encoding of the X.500 AttributeValue." The
flags parameter to ldap_str2dn() can be
LDAP_DN_FORMAT_LDAPV3
LDAP_DN_FORMAT_LDAPV2
LDAP_DN_FORMAT_DCE
which defines what DN syntax is expected (according to RFC
2253, RFC 1779 and DCE, respectively). The format can be
ORed to the flags
LDAP_DN_P_NO_SPACES
LDAP_DN_P_NO_SPACE_AFTER_RDN
...
LDAP_DN_PEDANTIC
The latter is a shortcut for all the previous limitations.
LDAP_DN_P_NO_SPACES does not allow extra spaces in the dn;
the default is to silently eliminate spaces around AVA
separators ('='), RDN component separators ('+' for
LDAPv3/LDAPv2 or ',' for DCE) and RDN separators (','
LDAPv3/LDAPv2 or '/' for DCE).
LDAP_DN_P_NO_SPACE_AFTER_RDN does not allow a single space
after RDN separators.
ldap_dn2str() performs the inverse operation, yielding in
str a string representation of dn. It allows the same values
for flags as ldap_str2dn(), plus
LDAP_DN_FORMAT_UFN
LDAP_DN_FORMAT_AD_CANONICAL
for user-friendly naming (RFC 1781) and AD canonical.
The following routines are viewed as deprecated in favor of
ldap_str2dn() and ldap_dn2str(). They are provided to
support legacy applications.
The ldap_explode_dn() routine takes a DN as returned by
ldap_get_dn() and breaks it up into its component parts.
Each part is known as a Relative Distinguished Name, or RDN.
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LDAP_GET_DN(3) OpenLDAP 2.2.23 (2005/01/24) LDAP_GET_DN(3)ldap_explode_dn() returns a NULL-terminated array, each
component of which contains an RDN from the DN. The notypes
parameter is used to request that only the RDN values be
returned, not their types. For example, the DN "cn=Bob,
c=US" would return as either { "cn=Bob", "c=US", NULL } or {
"Bob", "US", NULL }, depending on whether notypes was 0 or
1, respectively. Assertion values in RDN strings may
included escaped characters. The result can be freed by
calling ldap_value_free(3).
Similarly, the ldap_explode_rdn() routine takes an RDN as
returned by ldap_explode_dn(dn,0) and breaks it up into its
"type=value" component parts (or just "value", if the
notypes parameter is set). Note the value is not unescaped.
The result can be freed by calling ldap_value_free(3).
ldap_dn2ufn() is used to turn a DN as returned by
ldap_get_dn(3) into a more user-friendly form, stripping off
all type names. See "Using the Directory to Achieve User
Friendly Naming" (RFC 1781) for more details on the UFN
format. Due to the ambigious nature of the format, it is
generally only used for display purposes. The space for the
UFN returned is obtained dynamically and the user is
responsible for freeing it via a call to ldap_memfree(3).
ldap_dn2dcedn() is used to turn a DN as returned by
ldap_get_dn(3) into a DCE-style DN, e.g. a string with
most-significant to least significant rdns separated by
slashes ('/'); rdn components are separated by commas (',').
Only printable chars (e.g. LDAPv2 printable string) are
allowed, at least in this implementation. ldap_dcedn2dn()
performs the opposite operation. ldap_dn2ad_canonical()
turns a DN into a AD canonical name, which is basically a
DCE dn with attribute types omitted. The trailing domain,
if present, is turned in a DNS-like domain. The space for
the returned value is obtained dynamically and the user is
responsible for freeing it via a call to ldap_memfree(3).
ERRORS
If an error occurs in ldap_get_dn(), NULL is returned and
the ld_errno field in the ld parameter is set to indicate
the error. See ldap_error(3) for a description of possible
error codes. ldap_explode_dn(), ldap_explode_rdn(),
ldap_dn2ufn(), ldap_dn2dcedn(), ldap_dcedn2dn(), and
ldap_dn2ad_canonical() will return NULL with errno(3) set
appropriately in case of trouble.
NOTES
These routines dynamically allocate memory that the caller
must free.
SEE ALSO
Page 3 (printed 5/15/05)
LDAP_GET_DN(3) OpenLDAP 2.2.23 (2005/01/24) LDAP_GET_DN(3)ldap(3), ldap_error(3), ldap_first_entry(3),
ldap_memfree(3), ldap_value_free(3)
ACKNOWLEDGEMENTS
OpenLDAP is developed and maintained by The OpenLDAP Project
(http://www.openldap.org/). OpenLDAP is derived from
University of Michigan LDAP 3.3 Release.
Page 4 (printed 5/15/05)
