.\" $OpenBSD: ber_set_header.3,v 1.2 2019/05/21 12:30:07 rob Exp $
.\"
.\" Copyright (c) 2007, 2012 Reyk Floeter <reyk@openbsd.org>
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.Dd $Mdocdate: May 21 2019 $
.Dt BER_SET_HEADER 3
.Os
.Sh NAME
.Nm ber_set_header ,
.Nm ber_calc_len ,
.Nm ber_set_writecallback ,
.Nm ber_link_elements ,
.Nm ber_replace_elements ,
.Nm ber_unlink_elements ,
.Nm ber_free_element ,
.Nm ber_free_elements
.Nd change and destroy ASN.1 objects for BER encoding
.Sh SYNOPSIS
.In sys/types.h
.In ber.h
.Ft "void"
.Fn "ber_set_header" "struct ber_element *elm" "int class" "unsigned int type"
.Ft "size_t"
.Fn "ber_calc_len" "struct ber_element *root"
.Ft "void"
.Fo "ber_set_writecallback"
.Fa "void (*cb)(void *arg, sizeof_t offs)"
.Fc
.Ft "void"
.Fn "ber_link_elements" "struct ber_element *prev" "struct ber_element *elm"
.Ft "void"
.Fn "ber_replace_elements" "struct ber_element *prev" "struct ber_element *elm"
.Ft "struct ber_element *"
.Fn "ber_unlink_elements" "struct ber_element *prev"
.Ft "void"
.Fn "ber_free_element" "struct ber_element *root"
.Ft "void"
.Fn "ber_free_elements" "struct ber_element *root"
.Pp
.Fd #define BER_TYPE_BOOLEAN			1
.Fd #define BER_TYPE_INTEGER			2
.Fd #define BER_TYPE_BITSTRING		3
.Fd #define BER_TYPE_OCTETSTRING		4
.Fd #define BER_TYPE_NULL			5
.Fd #define BER_TYPE_OBJECT			6
.Fd #define BER_TYPE_ENUMERATED		10
.Fd #define BER_TYPE_SEQUENCE		16
.Fd #define BER_TYPE_SET			17
.Pp
.Fd #define BER_TYPE_CONSTRUCTED		0x20
.Pp
.Fd #define BER_CLASS_UNIVERSAL		0x0
.Fd #define BER_CLASS_UNIV			BER_CLASS_UNIVERSAL
.Fd #define BER_CLASS_APPLICATION		0x1
.Fd #define BER_CLASS_APP			BER_CLASS_APPLICATION
.Fd #define BER_CLASS_CONTEXT		0x2
.Fd #define BER_CLASS_PRIVATE		0x3
.Sh DESCRIPTION
.Fn ber_set_header
sets the
.Fa class
and
.Fa type
of
.Fa elm .
.Pp
.Fn ber_calc_len
determines the total length of
.Fa root .
.Pp
.Fn ber_set_writecallback
registers the
.Vt br_cb
callback function.
.Pp
.Fn ber_link_elements
links
.Fa prev
and
.Fa elm .
.Pp
.Fn ber_replace_elements
replaces
.Fa prev
with
.Fa new
and frees any dynamically allocated storage assocated with
.Fa prev .
.Pp
.Fn ber_unlink_elements
unlinks
.Fa prev .
.Pp
.Fn ber_free_element
and
.Fn ber_free_elements
free any dynamically allocated storage associated with
.Fa root .
.Sh RETURN VALUES
.Fn ber_calc_len
returns the total length of a fully populated
.Fa root
containing one or more
.Vt ber_element .
.Pp
.Fn ber_unlink_elements
returns a pointer to
.Vt ber_element .
.Sh SEE ALSO
.Xr ber_add_string 3 ,
.Xr ber_get_string 3 ,
.Xr ber_oid_cmp 3 ,
.Xr ber_read_elements 3
.Sh STANDARDS
ITU-T Recommendation X.690, also known as ISO/IEC 8825-1:
Information technology - ASN.1 encoding rules.
.Sh HISTORY
These functions first appeared as internal functions in
.Xr snmpd 8
in
.Ox 4.2
and were moved to libutil in
.Ox 6.6 .
.Sh AUTHORS
.An -nosplit
The BER library was written by
.An Claudio Jeker Aq Mt claudio@openbsd.org ,
.An Marc Balmer Aq Mt marc@openbsd.org
and
.An Reyk Floeter Aq Mt reyk@openbsd.org .