openldap/doc/man/man3/ldap_get_dn.3

.TH LDAP_GET_DN 3 "22 July 2001" "OpenLDAP LDVERSION"
.\" $OpenLDAP$
.\" Copyright 1998-2002 The OpenLDAP Foundation All Rights Reserved.
.\" Copying restrictions apply.  See COPYRIGHT/LICENSE.
.SH NAME
ldap_get_dn, ldap_explode_dn, ldap_explode_rdn, ldap_dn2ufn \- LDAP DN handling routines
.SH SYNOPSIS
.nf
.ft B
#include <ldap.h>
.LP
.ft B
char *ldap_get_dn( LDAP *ld, LDAPMessage *entry )
.LP
.ft B
char **ldap_explode_dn( const char *dn, int notypes )
.LP
.ft B
char **ldap_explode_rdn( const char *rdn, int notypes )
.LP
.ft B
char *ldap_dn2ufn( const char * dn )
.LP
.ft B
char *ldap_dn2dcedn( const char * dn )
.LP
.ft B
char *ldap_dcedn2dn( const char * dn )
.LP
.ft B
char *ldap_dn2ad_canonical( const char * dn )
.LP
.ft B
int ldap_str2dn( const char *str, LDAPDN **dn, unsigned flags )
.LP
.ft B
int ldap_dn2str( LDAPDN *dn, char **str, unsigned flags )
.SH 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".
.LP
The
.B ldap_get_dn()
routine takes an \fIentry\fP as returned by
.BR ldap_first_entry (3)
or
.BR 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 
.BR ldap_memfree (3).
.LP
The
.B ldap_explode_dn()
routine takes a DN as returned by
.B ldap_get_dn()
and breaks it up into its component parts.  Each part is known as a
Relative Distinguished Name, or RDN.
.B ldap_explode_dn()
returns a
NULL-terminated array, each component of which contains an RDN from the
DN.  The \fInotypes\fP 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.
The result can be freed by calling
.BR ldap_value_free (3).
.LP
Similarly, the
.B ldap_explode_rdn()
routine takes an RDN as returned by
.B ldap_explode_dn(dn,0)
and breaks it up into its "type=value" component parts (or just "value",
if the \fInotypes\fP parameter is set).  Note the value is not
unescaped.  The result can be freed by calling
.BR ldap_value_free (3).
.LP
.B ldap_dn2ufn()
is used to turn a DN as returned by
.BR 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
.BR ldap_memfree (3).
.LP
.B ldap_dn2dcedn()
is used to turn a DN as returned by
.BR 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.
.B ldap_dcedn2dn()
performs the opposite operation.
.B 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
.BR ldap_memfree (3).
.LP
.B ldap_str2dn()
parses a string representation of a distinguished name contained in
.B str
into its components,
which are stored in 
.B dn
as
.B ldap_ava 
structures, arranged in
.B LDAPAVA,
.B LDAPRDN,
and 
.B LDAPDN
terms, defined as:
.nf
.ft B

typedef struct ldap_ava {
    char *la_attr;
    struct berval *la_value;
    unsigned la_flags;
} LDAPAVA;

typedef LDAPAVA** LDAPRDN;
typedef LDAPRDN** LDAPDN;

.ft
.fi
The attribute types and the attribute values are not normalized.
The
.B la_flags
can be either
.B LDAP_AVA_STRING
or
.B 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
.B flags
parameter to
.B ldap_str2dn()
can be
.LP
.nf
	LDAP_DN_FORMAT_LDAPV3
	LDAP_DN_FORMAT_LDAPV2
	LDAP_DN_FORMAT_DCE

.fi
which defines what DN syntax is expected (according to RFC 2253, 
RFC 1779 and DCE, respectively).
The format can be \fIOR\fPed to the flags
.LP
.nf
	LDAP_DN_P_NO_SPACES
	LDAP_DN_P_NO_SPACE_AFTER_RDN
	...
	LDAP_DN_PEDANTIC

.fi
The latter is a shortcut for all the previous limitations.
.LP
.B 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).
.LP
.B LDAP_DN_P_NO_SPACE_AFTER_RDN
does not allow a single space after RDN separators.
.LP
.B ldap_dn2str()
performs the inverse operation, yielding in 
.B str
a string representation of 
.B dn.
It allows the same values for
.B flags 
as
.B ldap_str2dn(),
plus
.LP
.nf
	LDAP_DN_FORMAT_UFN
	LDAP_DN_FORMAT_AD_CANONICAL

.fi
for user-friendly naming (RFC 1781) and AD canonical.
.SH ERRORS
If an error occurs in
.BR ldap_get_dn() ,
NULL is returned and the
.B ld_errno
field in the \fIld\fP parameter is set to indicate the error.  See
.BR ldap_error (3)
for a description of possible error codes.
.BR ldap_explode_dn() ,
.BR ldap_explode_rdn() ,
.B ldap_dn2ufn(),
.B ldap_dn2dcedn(),
.B ldap_dcedn2dn(),
and
.B ldap_dn2ad_canonical()
will return NULL with
.BR errno (3)
set appropriately in case of trouble.
.SH NOTES
These routines dynamically allocate memory that the caller must free.
.SH SEE ALSO
.BR ldap(3),
.BR ldap_error(3),
.BR ldap_first_entry(3),
.BR ldap_memfree(3),
.BR ldap_value_free(3)
.SH ACKNOWLEDGEMENTS
.B	OpenLDAP
is developed and maintained by The OpenLDAP Project (http://www.openldap.org/).
.B	OpenLDAP
is derived from University of Michigan LDAP 3.3 Release.