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Convert::ASN1 - ASN.1 Encode/Decode library
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)
Convert::ASN1 encodes and decodes ASN.1 data structures using BER/DER rules.
Contructor, creates a new object.
Returns the last error.
Configure options to control how Convert::ASN1 will perform various tasks. Options are passed as name-value pairs.
Reference to a hash which contains various encode options.
Reference to a hash which contains various decode options.
One of 'BER' or 'DER'. The default is 'BER'
Encode options
Which encoding to use for real's. One of 'binary', 'nr1', 'nr2', 'nr3'
This controls how UTCTime and GeneralizedTime elements are encoded. The default
is withzone.
The value passed will be encoded without a zone, ie a UTC value.
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.
The value passed should already be in the correct format and will be copied into the PDU as-is.
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.
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
This controls how a UTCTime or a GeneralizedTime element will be decoded. The default
is utctime.
The value returned will be a time value as returned by the time function.
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.
The value returned will be the raw encoding as extracted from the PDU.
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.
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.
Compile the ASN.1 description to be read from the specified pathname.
Find a macro from a prepared ASN.1 description. Returns an object which can be used for encode/decode.
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 the PDU, returns a reference to a hash containg the values for the PDU. Returns undef if there was an error.
As well as providing an object interface for encoding/decoding PDUs Convert::ASN1 also provides the following functions.
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.
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.
Identical to calling send, see the perlfunc manpage
Identical to calling syswrite with 2 arguments, see the perlfunc manpage
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 works with asn_get. It will return true if asn_get has already
read enough data into the buffer to return a complete element.
All exported functions
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
asn_dump, asn_dumphex
asn_recv, asn_send, asn_read, asn_write, asn_get, asn_ready
asn_tag, asn_decode_tag, asn_encode_tag, asn_decode_length, asn_encode_length
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 },
]}
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 {...}.
XS implementation.
More documentation.
More tests.
Graham Barr <gbarr@pobox.com>, Report bugs via <bug-Convert-ASN1@rt.cpan.org>
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.