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276 lines
8.3 KiB
Groff
276 lines
8.3 KiB
Groff
.TH LBER_ENCODE 3 "RELEASEDATE" "OpenLDAP LDVERSION"
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.\" $OpenLDAP$
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.\" Copyright 1998-2002 The OpenLDAP Foundation All Rights Reserved.
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.\" Copying restrictions apply. See COPYRIGHT/LICENSE.
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.SH NAME
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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
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.SH LIBRARY
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OpenLDAP LBER (liblber, -llber)
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.SH SYNOPSIS
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.B #include <lber.h>
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.LP
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.BI "BerElement *ber_alloc_t(int " options ");"
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.LP
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.BI "int ber_flush(Sockbuf *" sb ", BerElement *" ber ", int " freeit ");"
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.LP
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.BI "int ber_printf(BerElement *" ber ", const char *" fmt ", ...);"
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.LP
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.BI "int ber_put_int(BerElement *" ber ", ber_int_t " num ", ber_tag_t " tag ");"
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.LP
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.BI "int ber_put_enum(BerElement *" ber ", ber_int_t " num ", ber_tag_t " tag ");"
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.LP
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.BI "int ber_put_ostring(BerElement *" ber ", const char *" str ", ber_len_t " len ", ber_tag_t " tag ");"
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.LP
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.BI "int ber_put_string(BerElement *" ber ", const char *" str ", ber_tag_t " tag ");"
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.LP
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.BI "int ber_put_null(BerElement *" ber ", ber_tag_t " tag ");"
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.LP
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.BI "int ber_put_boolean(BerElement *" ber ", ber_int_t " bool ", ber_tag_t " tag ");"
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.LP
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.BI "int ber_put_bitstring(BerElement *" ber ", const char *" str ", ber_len_t " blen ", ber_tag_t " tag ");"
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.LP
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.BI "int ber_start_seq(BerElement *" ber ", ber_tag_t " tag ");"
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.LP
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.BI "int ber_start_set(BerElement *" ber ", ber_tag_t " tag ");"
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.LP
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.BI "int ber_put_seq(BerElement *" ber ");"
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.LP
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.BI "int ber_put_set(BerElement *" ber ");"
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.SH DESCRIPTION
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.LP
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These routines provide a subroutine interface to a simplified
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implementation of the Basic Encoding Rules of ASN.1. The version
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of BER these routines support is the one defined for the LDAP
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protocol. The encoding rules are the same as BER, except that
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only definite form lengths are used, and bitstrings and octet strings
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are always encoded in primitive form. This
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man page describes the encoding routines in the lber library. See
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.BR lber-decode (3)
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for details on the corresponding decoding routines. Consult
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.BR lber-types (3)
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for information about types, allocators, and deallocators.
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.LP
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Normally, the only routines that need to be called by an application
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are
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.BR ber_alloc_t ()
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to allocate a BER element for encoding,
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.BR ber_printf ()
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to do the actual encoding, and
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.BR ber_flush ()
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to actually write the element. The other routines are provided for those
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applications that need more control than
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.BR ber_printf ()
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provides. In
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general, these routines return the length of the element encoded, or
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LBER_ERROR if an error occurred.
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.LP
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The
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.BR ber_alloc_t ()
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routine is used to allocate a new BER element. It
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should be called with an argument of LBER_USE_DER.
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.LP
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The
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.BR ber_flush ()
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routine is used to actually write the element to a socket
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(or file) descriptor, once it has been fully encoded (using
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.BR ber_printf ()
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and friends). See
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.BR lber-sockbuf (3)
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for more details on the Sockbuf implementation of the \fIsb\fP parameter.
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If the \fIfreeit\fP parameter is non-zero, the supplied \fIber\fP will
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be freed after its contents have been flushed.
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.LP
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The
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.BR ber_printf ()
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routine is used to encode a BER element in much the same way that
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.BR sprintf (3)
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works. One important difference, though, is
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that some state information is kept with the \fIber\fP parameter so
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that multiple calls can be made to
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.BR ber_printf ()
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to append things to the end of the BER element.
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.BR Ber_printf ()
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writes to \fIber\fP, a pointer to a BerElement such as returned by
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.BR ber_alloc_t ().
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It interprets and
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formats its arguments according to the format string \fIfmt\fP.
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The format string can contain the following characters:
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.RS
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.LP
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.TP 3
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.B b
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Boolean. An ber_int_t parameter should be supplied. A boolean element
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is output.
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.TP
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.B e
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Enumeration. An ber_int_t parameter should be supplied. An
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enumeration element is output.
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.TP
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.B i
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Integer. An ber_int_t parameter should be supplied. An integer element
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is output.
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.TP
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.B B
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Bitstring. A char * pointer to the start of the bitstring is supplied,
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followed by the number of bits in the bitstring. A bitstring element
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is output.
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.TP
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.B n
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Null. No parameter is required. A null element is output.
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.TP
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.B o
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Octet string. A char * is supplied, followed by the length of the
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string pointed to. An octet string element is output.
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.TP
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.B O
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Octet string. A struct berval * is supplied.
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An octet string element is output.
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.TP
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.B s
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Octet string. A null-terminated string is supplied. An octet string
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element is output, not including the trailing NULL octet.
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.TP
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.B t
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Tag. A ber_tag_t specifying the tag to give the next element
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is provided. This works across calls.
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.TP
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.B v
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Several octet strings. A null-terminated array of char *'s is
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supplied. Note that a construct like '{v}' is required to get
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an actual SEQUENCE OF octet strings.
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.TP
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.B V
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Several octet strings. A null-terminated array of struct berval *'s
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is supplied. Note that a construct like '{V}' is required to get
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an actual SEQUENCE OF octet strings.
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.TP
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.B W
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Several octet strings. An array of struct berval's is supplied. The
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array is terminated by a struct berval with a NULL bv_val.
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Note that a construct like '{W}' is required to get
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an actual SEQUENCE OF octet strings.
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.TP
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.B {
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Begin sequence. No parameter is required.
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.TP
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.B }
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End sequence. No parameter is required.
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.TP
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.B [
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Begin set. No parameter is required.
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.TP
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.B ]
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End set. No parameter is required.
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.RE
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.LP
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The
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.BR ber_put_int ()
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routine writes the integer element \fInum\fP to the BER element \fIber\fP.
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.LP
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The
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.BR ber_put_enum ()
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routine writes the enumeration element \fInum\fP to the BER element \fIber\fP.
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.LP
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The
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.BR ber_put_boolean ()
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routine writes the boolean value given by \fIbool\fP to the BER element.
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.LP
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The
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.BR ber_put_bitstring ()
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routine writes \fIblen\fP bits starting
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at \fIstr\fP as a bitstring value to the given BER element. Note
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that \fIblen\fP is the length \fIin bits\fP of the bitstring.
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.LP
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The
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.BR ber_put_ostring ()
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routine writes \fIlen\fP bytes starting at
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\fIstr\fP to the BER element as an octet string.
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.LP
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The
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.BR ber_put_string ()
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routine writes the null-terminated string (minus
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the terminating '\0') to the BER element as an octet string.
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.LP
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The
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.BR ber_put_null ()
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routine writes a NULL element to the BER element.
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.LP
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The
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.BR ber_start_seq ()
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routine is used to start a sequence in the BER element. The
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.BR ber_start_set ()
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routine works similarly.
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The end of the sequence or set is marked by the nearest matching call to
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.BR ber_put_seq ()
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or
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.BR ber_put_set (),
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respectively.
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.SH EXAMPLES
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Assuming the following variable declarations, and that the variables
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have been assigned appropriately, an lber encoding of
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the following ASN.1 object:
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.LP
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.nf
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AlmostASearchRequest := SEQUENCE {
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baseObject DistinguishedName,
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scope ENUMERATED {
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baseObject (0),
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singleLevel (1),
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wholeSubtree (2)
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},
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derefAliases ENUMERATED {
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neverDerefaliases (0),
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derefInSearching (1),
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derefFindingBaseObj (2),
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alwaysDerefAliases (3)
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},
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sizelimit INTEGER (0 .. 65535),
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timelimit INTEGER (0 .. 65535),
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attrsOnly BOOLEAN,
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attributes SEQUENCE OF AttributeType
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}
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.fi
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.LP
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can be achieved like so:
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.LP
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.nf
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int rc;
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ber_int_t scope, ali, size, time, attrsonly;
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char *dn, **attrs;
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BerElement *ber;
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/* ... fill in values ... */
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ber = ber_alloc_t( LBER_USE_DER );
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if ( ber == NULL ) {
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/* error */
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}
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rc = ber_printf( ber, "{siiiib{v}}", dn, scope, ali,
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size, time, attrsonly, attrs );
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if( rc == LBER_ERROR ) {
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/* error */
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} else {
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/* success */
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}
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.fi
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.SH ERRORS
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If an error occurs during encoding, generally these routines return LBER_ERROR.
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.LP
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.SH NOTES
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.LP
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The return values for all of these functions are declared in the
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<lber.h> header file.
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.SH SEE ALSO
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.BR lber-decode (3),
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.BR lber-memory (3),
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.BR lber-sockbuf (3),
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.BR lber-types (3)
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.SH ACKNOWLEDGEMENTS
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.B OpenLDAP
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is developed and maintained by The OpenLDAP Project (http://www.openldap.org/).
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.B OpenLDAP
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is derived from University of Michigan LDAP 3.3 Release.
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