Provided by: libsnmp-session-perl_1.16-1_all
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").