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ber_printf

LBER_ENCODE(3)                                                  LBER_ENCODE(3)



NAME
       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

SYNOPSIS
       #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 long 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 implemen-
       tation of the Basic Encoding Rules of ASN.1.  The version of BER  these
       routines  support is the one defined for the LDAP protocol.  The encod-
       ing rules are the same as BER, except that only definite  form  lengths
       are used, and bitstrings and octet strings are always encoded in primi-
       tive form.  In addition, these lightweight BER routines  restrict  tags
       and  class  to fit in a single octet (this means the actual tag must be
       less than 31).  When a "tag" is specified in the descriptions below, it
       refers to the tag, class, and primitive or constructed bit in the first
       octet of the encoding.  This man page describes the  encoding  routines
       in the lber library.  See lber-decode(3) for details on the correspond-
       ing decoding routines.  Consult  lber-types(3)  for  information  about
       types, allocators, and deallocators.

       Normally,  the  only routines that need 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 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_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).  The sb structure contains the descriptor  and  a  BerElement
       used  for  input  buffering.   Only  the sb_sd field is relevant to the
       ber_flush() routine.

       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 mul-
       tiple  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().  It interprets and formats its argu-
       ments according to the format string fmt.  The format string  can  con-
       tain 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.

              {  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 enumberation 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 ele-
       ment.  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.

       The ber_first_element() routine is used to return the tag and length of
       the  first  element  in a set or sequence.  It also returns in cookie a
       magic cookie parameter that should be passed  to  subsequent  calls  to
       ber_next_element(), which returns similar information.

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-types(3) ldap-async(3) ldap-sync(3)
       ldap-parse(3)

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



OpenLDAP 2.0.27-Release           12 May 2000                   LBER_ENCODE(3)