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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;
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. 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
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.
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