phpman > perldoc > Convert::ASN1(3pm)

NAME
    Convert::ASN1 - ASN.1 Encode/Decode library

VERSION
    version 0.33

SYNOPSIS
      use Convert::ASN1;

      $asn = Convert::ASN1->new;
      $asn->prepare(q<

        [APPLICATION 7] SEQUENCE {
          int INTEGER,
          str OCTET STRING
        }

      >);

      $pdu = $asn->encode( int => 7, str => "string");

      $out = $asn->decode($pdu);
      print $out->{int}," ",$out->{str},"\n";

      use Convert::ASN1 qw(:io);

      $peer   = asn_recv($sock,$buffer,0);
      $nbytes = asn_read($fh, $buffer);
      $nbytes = asn_send($sock, $buffer, $peer);
      $nbytes = asn_send($sock, $buffer);
      $nbytes = asn_write($fh, $buffer);
      $buffer = asn_get($fh);
      $yes    = asn_ready($fh)

DESCRIPTION
    Convert::ASN1 encodes and decodes ASN.1 data structures using BER/DER rules.

METHODS
  new ( [OPTIONS] )
    Contructor, creates a new object.

    If given, OPTIONS are the same ones as for "configure ( OPTIONS )" below.

  error ()
    Returns the last error.

  configure ( OPTIONS )
    Configure options to control how Convert::ASN1 will perform various tasks. Options are passed as
    name-value pairs.

    encode
        Reference to a hash which contains various encode options.

    decode
        Reference to a hash which contains various decode options.

    encoding
        One of 'BER' or 'DER'. The default is 'BER'

    tagdefault
        One of 'EXPLICIT' or 'IMPLICIT'. Default tagging conventions are normally given in the ASN.1
        module definition (not supported by the parser). The ASN.1 spec states EXPLICIT tagging is
        the default, but this option has IMPLICIT tagging default for backward compatibility
        reasons.

    Encode options

    real
        Which encoding to use for real's. One of 'binary', 'nr1', 'nr2', 'nr3'

    time
        This controls how UTCTime and GeneralizedTime elements are encoded. The default is
        "withzone".

        utctime
            The value passed will be encoded without a zone, ie a UTC value.

        withzone
            The value will be encoded with a zone. By default it will be encoded using the local
            time offset. The offset may be set using the "timezone" configure option.

        raw The value passed should already be in the correct format and will be copied into the PDU
            as-is.

    timezone
        By default UTCTime and GeneralizedTime will be encoded using the local time offset from UTC.
        This will over-ride that. It is an offset from UTC in seconds. This option can be overridden
        by passing a reference to a list of two values as the time value. The list should contain
        the time value and the offset from UTC in seconds.

    bigint
        If during encoding an value greater than 32 bits is discovered and is not already a big
        integer object, then the value will first be converted into a big integer object. This
        option controls the big integer class into which the objects will be blessed. The default is
        to use Math::BigInt

    Decode options

    time
        This controls how a UTCTime or a GeneralizedTime element will be decoded. The default is
        "utctime".

        utctime
            The value returned will be a time value as returned by the "time" function.

        withzone
            The value returned will be a reference to an array of two values. The first is the same
            as with "utctime", the second is the timezone offset, in seconds, that was used in the
            encoding.

        raw The value returned will be the raw encoding as extracted from the PDU.

    bigint
        If during decoding any big integers are discovered (integers greater than 32 bits), they
        will be decoded into big integer objects. This option controls the big integer class into
        which the objects will be blessed. The default is to use Math::BigInt.

    null
        The value to decode ASN.1 NULL types into. If not set, it defaults to 1.

  prepare ( ASN )
    Compile the given ASN.1 description which can be passed as a string or as a filehandle. The
    syntax used is very close to ASN.1, but has a few differences. If the ASN describes only one
    macro then encode/decode can be called on this object. If ASN describes more than one ASN.1
    macro then "find" must be called. The method returns undef on error.

  prepare_file ( ASNPATH )
    Compile the ASN.1 description to be read from the specified pathname.

  find ( MACRO )
    Find a macro from a prepared ASN.1 description. Returns an object which can be used for
    encode/decode.

  encode ( VARIABLES )
    Encode a PDU. Top-level variable are passed as name-value pairs, or as a reference to a hash
    containing them. Returns the encoded PDU, or undef on error.

  decode ( PDU )
    Decode the PDU, returns a reference to a hash containing the values for the PDU. Returns undef
    if there was an error.

  registeroid ( OID, HANDLER )
    Register a handler for all ASN.1 elements that are "DEFINED BY" the given OID.

    HANDLER must be a Convert::ASN1 object, e.g. as returned by "find ( MACRO )".

  registertype ( NAME, OID, HANDLER )
    Register a handler for all ASN.1 elements named "NAME", that are "DEFINED BY" the given OID.

    HANDLER must be a Convert::ASN1 object, e.g. as returned by "find ( MACRO )".

EXPORTS
    As well as providing an object interface for encoding/decoding PDUs Convert::ASN1 also provides
    the following functions.

  IO Functions
    asn_recv ( SOCK, BUFFER, FLAGS )
        Will read a single element from the socket SOCK into BUFFER. FLAGS may be MSG_PEEK as
        exported by "Socket". Returns the address of the sender, or undef if there was an error.
        Some systems do not support the return of the peer address when the socket is a connected
        socket, in these cases the empty string will be returned. This is the same behaviour as the
        "recv" function in perl itself.

        It is recommended that if the socket is of type SOCK_DGRAM then "recv" be called directly
        instead of calling "asn_recv".

    asn_read ( FH, BUFFER, OFFSET )
    asn_read ( FH, BUFFER )
        Will read a single element from the filehandle FH into BUFFER. Returns the number of bytes
        read if a complete element was read, -1 if an incomplete element was read or undef if there
        was an error. If OFFSET is specified then it is assumed that BUFFER already contains an
        incomplete element and new data will be appended starting at OFFSET.

        If FH is a socket the asn_recv is used to read the element, so the same restriction applies
        if FH is a socket of type SOCK_DGRAM.

    asn_send ( SOCK, BUFFER, FLAGS, TO )
    asn_send ( SOCK, BUFFER, FLAGS )
        Identical to calling "send", see perlfunc

    asn_write ( FH, BUFFER )
        Identical to calling "syswrite" with 2 arguments, see perlfunc

    asn_get ( FH )
        "asn_get" provides buffered IO. Because it needs a buffer FH must be a GLOB or a reference
        to a GLOB. "asn_get" will use two entries in the hash element of the GLOB to use as its
        buffer:

          asn_buffer - input buffer
          asn_need   - number of bytes needed for the next element, if known

        Returns an element or undef if there was an error.

    asn_ready ( FH )
        "asn_ready" works with "asn_get". It will return true if "asn_get" has already read enough
        data into the buffer to return a complete element.

  Encode/Decode Functions
    asn_tag ( CLASS, VALUE )
        Given CLASS and a VALUE, calculate an integer which when encoded will become the tag.

    asn_decode_tag ( TAG )
        Decode the given ASN.1 encoded "TAG".

    asn_encode_tag ( TAG )
        Encode TAG value for encoding. We assume that the tag has been correctly generated with
        "asn_tag ( CLASS, VALUE )".

    asn_decode_length ( LEN )
        Decode the given ASN.1 decoded "LEN".

    asn_encode_length ( LEN )
        Encode the given "LEN" to its ASN.1 encoding.

  Constants
    ASN_BIT_STR
    ASN_BOOLEAN
    ASN_ENUMERATED
    ASN_GENERAL_TIME
    ASN_IA5_STR
    ASN_INTEGER
    ASN_NULL
    ASN_OBJECT_ID
    ASN_OCTET_STR
    ASN_PRINT_STR
    ASN_REAL
    ASN_SEQUENCE
    ASN_SET
    ASN_UTC_TIME
    ASN_APPLICATION
    ASN_CONTEXT
    ASN_PRIVATE
    ASN_UNIVERSAL
    ASN_PRIMITIVE
    ASN_CONSTRUCTOR
    ASN_LONG_LEN
    ASN_EXTENSION_ID
    ASN_BIT

  Debug Functions
    asn_dump ( [FH,] BUFFER )
        Try to decode the given buffer as ASN.1 structure and dump it to the given file handle, or
        "STDERR" if the handle is not given.

    asn_hexdump ( FH, BUFFER )

EXPORT TAGS
    :all
        All exported functions

    :const
        ASN_BOOLEAN, ASN_INTEGER, ASN_BIT_STR, ASN_OCTET_STR, ASN_NULL, ASN_OBJECT_ID, ASN_REAL,
        ASN_ENUMERATED, ASN_SEQUENCE, ASN_SET, ASN_PRINT_STR, ASN_IA5_STR, ASN_UTC_TIME,
        ASN_GENERAL_TIME, ASN_UNIVERSAL, ASN_APPLICATION, ASN_CONTEXT, ASN_PRIVATE, ASN_PRIMITIVE,
        ASN_CONSTRUCTOR, ASN_LONG_LEN, ASN_EXTENSION_ID, ASN_BIT

    :debug
        asn_dump, asn_hexdump

    :io asn_recv, asn_send, asn_read, asn_write, asn_get, asn_ready

    :tag
        asn_tag, asn_decode_tag, asn_encode_tag, asn_decode_length, asn_encode_length

MAPPING ASN.1 TO PERL
    Every element in the ASN.1 definition has a name, in perl a hash is used with these names as an
    index and the element value as the hash value.

      # ASN.1
      int INTEGER,
      str OCTET STRING

      # Perl
      { int => 5, str => "text" }

    In the case of a SEQUENCE, SET or CHOICE then the value in the namespace will be a hash
    reference which will be the namespace for the elements with that element.

      # ASN.1
      int INTEGER,
      seq SEQUENCE {
        str OCTET STRING,
        bool BOOLEAN
      }

      # Perl
      { int => 5, seq => { str => "text", bool => 1}}

    If the element is a SEQUENCE OF, or SET OF, then the value in the namespace will be an array
    reference. The elements in the array will be of the type expected by the type following the OF.
    For example with "SEQUENCE OF STRING" the array would contain strings. With "SEQUENCE OF
    SEQUENCE { ... }" the array will contain hash references which will be used as namespaces

      # ASN.1
      int INTEGER,
      str SEQUENCE OF OCTET STRING

      # Perl
      { int => 5, str => [ "text1", "text2"]}

      # ASN.1
      int INTEGER,
      str SEQUENCE OF SEQUENCE {
        type OCTET STRING,
        value INTEGER
      }

      # Perl
      { int => 5, str => [
        { type => "abc", value => 4 },
        { type => "def", value => -1 },
      ]}

    Finally, if you wish to pre-parse ASN.1 and hold it to include inline in your PDU, you can
    coerce it into the ASN.1 spec by defining the value as ANY in the schema, and then pass the pre
    encoded value inline.

      # ASN.1
      int INTEGER,
      str OCTET STRING,
      pre ANY

      # Perl
      { int => 5, str => "text", pre=>"\x03\x03\x00\x0a\x05" }

    passes a pre-encoded BIT STRING instance as hex text. -But it could be a previous run of
    $obj->encode() from another run held in some variable.

  Exceptions
    There are some exceptions where Convert::ASN1 does not require an element to be named. These are
    SEQUENCE {...}, SET {...} and CHOICE. In each case if the element is not given a name then the
    elements inside the {...} will share the same namespace as the elements outside of the {...}.

TODO
    *   XS implementation.

    *   More documentation.

    *   More tests.

AUTHOR
    Graham Barr <gbarr AT cpan.org>

SUPPORT
    Report issues via github at https://github.com/gbarr/perl-Convert-ASN1/issues

    To contribute I encourage you to create a git fork of the repository at
    https://github.com/gbarr/perl-Convert-ASN1 do you work on a fresh branch created from master and
    submit a pull request

COPYRIGHT
    Copyright (c) 2000-2012 Graham Barr <gbarr AT cpan.org>. All rights reserved. This program is free
    software; you can redistribute it and/or modify it under the same terms as Perl itself.