lber-encode(3) — Linux manual page


LBER_ENCODE(3)          Library Functions Manual          LBER_ENCODE(3)

NAME         top

       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         top

       OpenLDAP LBER (liblber, -llber)

SYNOPSIS         top

       #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

       int ber_put_null(BerElement *ber, ber_tag_t tag);

       int ber_put_boolean(BerElement *ber, ber_int_t bool, ber_tag_t

       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         top

       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

              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

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

       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         top

       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         top

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

NOTES         top

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

SEE ALSO         top

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


       OpenLDAP Software is developed and maintained by The OpenLDAP
       Project <>.  OpenLDAP Software is derived
       from the University of Michigan LDAP 3.3 Release.

COLOPHON         top

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OpenLDAP LDVERSION             RELEASEDATE                LBER_ENCODE(3)

Pages that refer to this page: lber-decode(3)lber-encode(3)lber-memory(3)lber-sockbuf(3)lber-types(3)ldap(3)slapo-valsort(5)