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.
Encode options
This controls how UTCTime and GeneralizedTime elements are encoded. The default
is withzone.
timezone
configure option.
Decode options
This controls how a UTCTime or a GeneralizedTime element will be decoded. The default
is utctime.
time function.
utctime, the second is the timezone offset, in seconds, that was
used in the encoding.
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.
send, see perlfunc
syswrite with 2 arguments, see perlfunc
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.
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 {...}.
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.