# lber-encode

## NAME



           ber_alloc_t, ber_flush, ber_flush2, 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 - OpenLDAP LBER simplified Basic Encoding
           Rules library routines for encoding
    


## LIBRARY



           OpenLDAP LBER (liblber, -llber)
    


## SYNOPSIS



           **#include <lber.h>**
    
           **BerElement *ber_alloc_t(int** _options_**);**
    
           **int ber_flush(Sockbuf ***_sb_**, BerElement ***_ber_**, int** _freeit_**);**
    
           **int ber_flush2(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_**);**
    


## DESCRIPTION



           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_flush2**()
           to actually write the element.  The other routines are provided
           for those applications that need more control than **ber_printf**()
           provides.  In general, these routines 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_flush2**() 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.  If
           _LBER_FLUSH_FREE_ON_SUCCESS_ is used, the _ber_ is only freed when
           successfully flushed, otherwise it is left intact; if
           _LBER_FLUSH_FREE_ON_ERROR_ is used, the _ber_ is only freed when an
           error occurs, otherwise it is left intact; if
           _LBER_FLUSH_FREE_ALWAYS_ is used, the _ber_ is freed anyway.  This
           function differs from the original ber_flush(3) function, whose
           behavior corresponds to that indicated for
           _LBER_FLUSH_FREE_ON_SUCCESS_.  Note that in the future, the behavior
           of ber_flush(3) with _freeit_ non-zero might change into that of
           ber_flush2(3) with _freeit_ set to _LBER_FLUSH_FREE_ALWAYS_.
    
           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 BerElement 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 output.
    
                  **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 output.
    
                  **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 output.
    
                  **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 strings.
    
                  **V** Several octet strings.  A null-terminated array of
                     struct berval *'s is supplied.  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.
    


## EXAMPLES



           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 */
                 }
    


## ERRORS



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


## NOTES



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


## ACKNOWLEDGEMENTS



           **OpenLDAP Software** is developed and maintained by The OpenLDAP
           Project <http://www.openldap.org/>.  **OpenLDAP Software** is derived
           from the University of Michigan LDAP 3.3 Release.
    


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