BER(3pm) User Contributed Perl Documentation BER(3pm)
NAME
BER - Basic Encoding Rules (BER) of Abstract Syntax Notation One
(ASN.1)
SYNOPSIS
use BER;
$encoded = encode_sequence (encode_int (123), encode_string ("foo"));
($i, $s) = decode_by_template ($encoded, "%{%i%s");
# $i will now be 123, $s the string "foo".
DESCRIPTION
This is a simple library to encode and decode data using the Basic
Encoding Rules (BER) of Abstract Syntax Notation One (ASN.1). It does
not claim to be a complete implementation of the standard, but
implements enough of the BER standard to encode and decode SNMP
messages.
VARIABLES
$pretty_print_timeticks (default: 1)
If non-zero (the default), "pretty_print" will convert TimeTicks to
"human readable" strings containing days, hours, minutes and seconds.
If the variable is zero, "pretty_print" will simply return an unsigned
integer representing hundredths of seconds. If you prefer this, bind
$pretty_print_timeticks to zero.
$errmsg - error message from last failed operation.
When they encounter errors, the routines in this module will generally
return "undef") and leave an informative error message in $errmsg).
METHODS
encode_int_0() - encode the integer 0.
This is functionally identical to encode_int(0).
encode_int() - encode an integer using the generic "integer" type tag.
encode_uinteger32() - encode an integer using the SNMP UInteger32 tag.
encode_counter32() - encode an integer using the SNMP Counter32 tag.
encode_counter64() - encode an integer using the SNMP Counter64 tag.
encode_gauge32() - encode an integer using the SNMP Gauge32 tag.
encode_oid() - encode an object ID, passed as a list of sub-IDs.
$encoded = encode_oid (1,3,6,1,...);
encode_null() - encode a null object.
This is used e.g. in binding lists for variables that don't have a
value (yet)
encode_sequence()
encode_tagged_sequence()
$encoded = encode_sequence (encoded1, encoded2, ...);
$encoded = encode_tagged_sequence (tag, encoded1, encoded2, ...);
Take already encoded values, and extend them to an encoded sequence.
"encoded_sequence" uses the generic sequence tag, while with
"encode_tagged_sequence" you can specify your own tag.
encode_string() - encode a Perl string as an OCTET STRING.
encode_ip_address() - encode an IPv4 address.
This can either be passed as a four-octet sequence in network byte
order, or as a text string in dotted-quad notation, e.g. "192.0.2.234".
encode_timeticks() - encode an integer as a "TimeTicks" object.
The integer should count hundredths of a second since the epoch defined
by "sysUpTime.0".
pretty_print() - convert an encoded byte sequence into human-readable form.
This function can be extended by registering pretty-printing methods
for specific type codes. Most BER type codes used in SNMP already have
such methods pre-registered by default. See "register_pretty_printer"
for how new methods can be added.
hex_string() - convert OCTET STRING to hexadecimal notation.
hex_string_of_type() - convert octet string to hex, and check type against
given tag.
decode_by_template() - decode complex object according to a template.
($var1, ...) = decode_by_template ($pdu, $template, ...);
The template can contain various %X directives. Some directives
consume additional arguments following the template itself. Most
directives will cause values to be returned. The values are returned
as a sequence in the order of the directives that generated them.
%{ - decode sequence.
This doesn't assign any return value, just checks and skips the
tag/length fields of the sequence. By default, the tag should be
the generic sequence tag, but a tag can also be specified in the
directive. The directive can either specify the tag as a prefix,
e.g. "%99{" will require a sequence tag of 99, or if the directive
is given as "%*{", the tag will be taken from the next argument.
%s - decode string
%i - decode integer
%u - decode unsigned integer
%O - decode Object ID (OID)
%A - decode IPv4 address
%@ - assigns the remaining undecoded part of the PDU to the next return
value.
decode_sequence() - Split sequence into components.
($first, $rest) = decode_sequence ($pdu);
Checks whether the PDU has a sequence type tag and a plausible length
field. Splits the initial element off the list, and returns both this
and the remainder of the PDU.
register_pretty_printer() - register pretty-printing methods for typecodes.
This function takes a hashref that specifies functions to call when the
specified value type is being printed. It returns the number of
functions that were registered.
AUTHORS
Created by: Simon Leinen <simon.leinen@switch.ch>
Contributions and fixes by:
Andrzej Tobola <san@iem.pw.edu.pl>: Added long String decode
Tobias Oetiker <tobi@oetiker.ch>: Added 5 Byte Integer decode ...
Dave Rand <dlr@Bungi.com>: Added "SysUpTime" decode
Philippe Simonet <sip00@vg.swissptt.ch>: Support larger subids
Yufang HU <yhu@casc.com>: Support even larger subids
Mike Mitchell <Mike.Mitchell@sas.com>: New generalized "encode_int()"
Mike Diehn <mdiehn@mindspring.net>: "encode_ip_address()"
Rik Hoorelbeke <rik.hoorelbeke@pandora.be>: "encode_oid()" fix
Brett T Warden <wardenb@eluminant.com>: pretty "UInteger32"
Bert Driehuis <driehuis@playbeing.org>: Handle SNMPv2 exception codes
Jakob Ilves (/IlvJa) <jakob.ilves@oracle.com>: PDU decoding
Jan Kasprzak <kas@informatics.muni.cz>: Fix for PDU syntax check
Milen Pavlov <milen@batmbg.com>: Recognize variant length for ints
COPYRIGHT
Copyright (c) 1995-2009, Simon Leinen.
This program is free software; you can redistribute it under the
"Artistic License 2.0" included in this distribution (file "Artistic").
perl v5.36.0 2022-11-26 BER(3pm)
Generated by dwww version 1.15 on Thu Sep 4 17:16:08 CEST 2025.