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Convert::ASN1(3)                     User Contributed Perl Documentation                    Convert::ASN1(3)



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

SYNOPSYS
         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'

       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. asis.
               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 overriden 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 descripton 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 decribes 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 containg 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 restiction 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 namespce 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 },
         ]}

   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@pobox.com>, Report bugs via <bug-Convert-ASN1@rt.cpan.org>

COPYRIGHT
       Copyright (c) 2000-2005 Graham Barr <gbarr@pobox.com>. All rights reserved.  This program is free
       software; you can redistribute it and/or modify it under the same terms as Perl itself.



perl v5.12.5                                     2008-09-15                                 Convert::ASN1(3)