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1.\" $OpenBSD: ober_oid_cmp.3,v 1.7 2025/06/13 18:34:00 schwarze Exp $
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3.\" Copyright (c) 2007, 2012 Reyk Floeter <reyk@openbsd.org>
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17.Dd $Mdocdate: June 13 2025 $
18.Dt OBER_OID_CMP 3
19.Os
20.Sh NAME
21.Nm ober_oid_cmp ,
22.Nm ober_oid2ber ,
23.Nm ober_string2oid
24.Nd OID helper functions for the BER library
25.Sh SYNOPSIS
26.Lb libutil
27.In sys/types.h
28.In ber.h
29.Ft int
30.Fn "ober_oid_cmp" "struct ber_oid *a" "struct ber_oid *b"
31.Ft size_t
32.Fn "ober_oid2ber" "struct ber_oid *oid" "u_int8_t *buf" "size_t size"
33.Ft int
34.Fn "ober_string2oid" "const char *string" "struct ber_oid *oid"
35.Sh DESCRIPTION
36Object Identifiers are commonly used in ASN.1-based protocols.
37These functions provide an interface to parse OIDs.
38For internal representation of OIDs, the following structure
39.Vt struct ber_oid
40is being used:
41.Bd -literal
42#define BER_MIN_OID_LEN 2
43#define BER_MAX_OID_LEN 64
44
45struct ber_oid {
46 u_int32_t bo_id[BER_MAX_OID_LEN + 1];
47 size_t bo_n;
48};
49.Ed
50.Pp
51The
52.Fn ober_oid2ber
53and
54.Fn ober_string2oid
55functions may be used to convert from and to
56.Vt struct ber_oid .
57.Pp
58.Fn ober_oid_cmp
59may be used to compare two
60.Vt ber_oid
61structures.
62.Sh RETURN VALUES
63.Fn ober_oid2ber
64returns the number of bytes written or 0 on failure.
65.Pp
66.Fn ober_string2oid
67returns 0 on success or -1 on failure.
68.Pp
69.Fn ober_oid_cmp
70returns an integer greater than, equal to, or less than 0, according to whether
71the oid
72.Fa a
73is greater than, equal to, or less than the oid
74.Fa b .
75If the shortest length from
76.Fa a
77and
78.Fa b
79matches
80the weight of the integer is 2, else it is 1.
81.Sh SEE ALSO
82.Xr ober_add_string 3 ,
83.Xr ober_get_string 3 ,
84.Xr ober_read_elements 3 ,
85.Xr ober_set_header 3
86.Sh HISTORY
87These functions first appeared as internal functions in
88.Xr snmpd 8
89in
90.Ox 4.2
91and were moved to libutil in
92.Ox 6.6 .
93.Sh AUTHORS
94.An -nosplit
95The BER library was written by
96.An Claudio Jeker Aq Mt claudio@openbsd.org ,
97.An Marc Balmer Aq Mt marc@openbsd.org
98and
99.An Reyk Floeter Aq Mt reyk@openbsd.org .