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LBER_ENCODE(3)             Library Functions Manual             LBER_ENCODE(3)



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 <&lt;lber.h>&gt;

       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.

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

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



OpenLDAP 2.4.23                   2010/06/30                    LBER_ENCODE(3)