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OpenDarwin 7.2.1 - man page for lber-encode (opendarwin section 3)

LBER_ENCODE(3)			     Library Functions Manual			   LBER_ENCODE(3)

       ber_alloc_t,    ber_flush,   ber_printf,   ber_put_int,	 ber_put_enum,	 ber_put_ostring,
       ber_put_string,	 ber_put_null,	 ber_put_boolean,    ber_put_bitstring,    ber_start_seq,
       ber_start_set,  ber_put_seq,  ber_put_set  -  LBER simplified Basic Encoding Rules library
       routines for encoding

       OpenLDAP LBER (liblber, -llber)

       #include <lber.h>

       BerElement *ber_alloc_t(int options);

       int ber_flush(Sockbuf *sb, BerElement *ber, int freeit);

       int ber_printf(BerElement *ber, const char *fmt, ...);

       int ber_put_int(BerElement *ber, ber_int_t num, ber_tag_t tag);

       int ber_put_enum(BerElement *ber, ber_int_t num, ber_tag_t tag);

       int ber_put_ostring(BerElement *ber, const char *str, ber_len_t len, ber_tag_t tag);

       int ber_put_string(BerElement *ber, const char *str, ber_tag_t tag);

       int ber_put_null(BerElement *ber, ber_tag_t tag);

       int ber_put_boolean(BerElement *ber, ber_int_t bool, ber_tag_t tag);

       int ber_put_bitstring(BerElement *ber, const char *str, ber_len_t blen, ber_tag_t tag);

       int ber_start_seq(BerElement *ber, ber_tag_t tag);

       int ber_start_set(BerElement *ber, ber_tag_t tag);

       int ber_put_seq(BerElement *ber);

       int ber_put_set(BerElement *ber);

       These routines provide a subroutine interface to a simplified implementation of the  Basic
       Encoding Rules of ASN.1.  The version of BER these routines support is the one defined for
       the LDAP protocol.  The encoding rules are the same as BER, except that only definite form
       lengths	are  used, and bitstrings and octet strings are always encoded in primitive form.
       This man page describes the encoding routines in the lber library.  See lber-decode(3) for
       details	on  the  corresponding	decoding routines.  Consult lber-types(3) for information
       about types, allocators, and deallocators.

       Normally, the only routines that need to be called by an application are ber_alloc_t()  to
       allocate  a  BER  element  for  encoding,  ber_printf()	to  do	the  actual encoding, and
       ber_flush() to actually write the element.  The other  routines	are  provided  for  those
       applications  that  need  more control than ber_printf() provides.  In general, these rou-
       tines return the length of the element encoded, or -1 if an error occurred.

       The ber_alloc_t() routine is used to allocate a new BER element.  It should be called with
       an argument of LBER_USE_DER.

       The  ber_flush()  routine  is  used  to	actually  write the element to a socket (or file)
       descriptor, once it has been fully encoded (using ber_printf() and  friends).   See  lber-
       sockbuf(3)  for	more  details  on the Sockbuf implementation of the sb parameter.  If the
       freeit parameter is non-zero, the supplied ber will be freed after its contents have  been

       The  ber_printf()  routine  is  used  to  encode  a  BER element in much the same way that
       sprintf(3) works.  One important difference, though, is that  some  state  information  is
       kept  with  the ber parameter so that multiple calls can be made to ber_printf() to append
       things to the end of the BER element.  Ber_printf() writes to ber, a pointer to a  BerEle-
       ment such as returned by ber_alloc_t().	It interprets and formats its arguments according
       to the format string fmt.  The format string can contain the following characters:

	      b  Boolean.  An ber_int_t parameter should be supplied.  A boolean element is  out-

	      e  Enumeration.  An ber_int_t parameter should be supplied.  An enumeration element
		 is output.

	      i  Integer.  An ber_int_t parameter should be supplied.  An integer element is out-

	      B  Bitstring.  A char * pointer to the start of the bitstring is supplied, followed
		 by the number of bits in the bitstring.  A bitstring element is output.

	      n  Null.	No parameter is required.  A null element is output.

	      o  Octet string.	A char * is supplied,  followed  by  the  length  of  the  string
		 pointed to.  An octet string element is output.

	      O  Octet	string.   A struct berval * is supplied.  An octet string element is out-

	      s  Octet string.	A null-terminated string is supplied.  An octet string element is
		 output, not including the trailing NULL octet.

	      t  Tag.  A ber_tag_t specifying the tag to give the next element is provided.  This
		 works across calls.

	      v  Several octet strings.  A null-terminated array of char *'s is  supplied.   Note
		 that  a  construct  like  '{v}'  is  required to get an actual SEQUENCE OF octet

	      V  Several octet strings.  A null-terminated array of struct  berval  *'s  is  sup-
		 plied.   Note	that a construct like '{V}' is required to get an actual SEQUENCE
		 OF octet strings.

	      W  Several octet strings.  An array of struct berval's is supplied.  The	array  is
		 terminated  by  a  struct berval with a NULL bv_val.  Note that a construct like
		 '{W}' is required to get an actual SEQUENCE OF octet strings.

	      {  Begin sequence.  No parameter is required.

	      }  End sequence.	No parameter is required.

	      [  Begin set.  No parameter is required.

	      ]  End set.  No parameter is required.

       The ber_put_int() routine writes the integer element num to the BER element ber.

       The ber_put_enum() routine writes the enumeration element num to the BER element ber.

       The ber_put_boolean() routine writes the boolean value given by bool to the BER element.

       The ber_put_bitstring() routine writes blen bits starting at str as a bitstring	value  to
       the given BER element.  Note that blen is the length in bits of the bitstring.

       The  ber_put_ostring()  routine	writes len bytes starting at str to the BER element as an
       octet string.

       The ber_put_string() routine writes the null-terminated string (minus the terminating ' ')
       to the BER element as an octet string.

       The ber_put_null() routine writes a NULL element to the BER element.

       The  ber_start_seq()  routine  is  used	to  start  a  sequence	in  the BER element.  The
       ber_start_set() routine works similarly.  The end of the sequence or set is marked by  the
       nearest matching call to ber_put_seq() or ber_put_set(), respectively.

       Assuming  the  following  variable declarations, and that the variables have been assigned
       appropriately, an lber encoding of the following ASN.1 object:

	     AlmostASearchRequest := SEQUENCE {
		 baseObject	 DistinguishedName,
		 scope		 ENUMERATED {
		     baseObject    (0),
		     singleLevel   (1),
		     wholeSubtree  (2)
		 derefAliases	 ENUMERATED {
		     neverDerefaliases	 (0),
		     derefInSearching	 (1),
		     derefFindingBaseObj (2),
		     alwaysDerefAliases  (3)
		 sizelimit	 INTEGER (0 .. 65535),
		 timelimit	 INTEGER (0 .. 65535),
		 attrsOnly	 BOOLEAN,
		 attributes	 SEQUENCE OF AttributeType

       can be achieved like so:

	     int rc;
	     ber_int_t	  scope, ali, size, time, attrsonly;
	     char   *dn, **attrs;
	     BerElement *ber;

	     /* ... fill in values ... */

	     ber = ber_alloc_t( LBER_USE_DER );

	     if ( ber == NULL ) {
		 /* error */

	     rc = ber_printf( ber, "{siiiib{v}}", dn, scope, ali,
		 size, time, attrsonly, attrs );

	     if( rc == -1 ) {
		     /* error */
	     } else {
		     /* success */

       If an error occurs during encoding, generally these routines return -1.

       The return values for all of these functions are declared in the <lber.h> header file.

       lber-decode(3), lber-memory(3), lber-sockbuf(3), lber-types(3)

       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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