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CentOS 7.0 - man page for convert::asn1 (centos section 3)

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

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

VERSION
       version 0.26

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'

       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 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 },
	 ]}

       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
       o   XS implementation.

       o   More documentation.

       o   More tests.

AUTHOR
       Graham Barr <gbarr@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@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.

perl v5.16.3				    2012-06-09				 Convert::ASN1(3)


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