Module `osyspyrt.asn1evthndlr`

Define classes supporting event handling.

Classes

class Asn1BerMessageDumpHandler

This implementation of an Asn1TaggedEventHandler can be used to get a formatted dump of an ASN.1 BER-encoded message in a human readable format.

The dump is done into the strbuf attribute.

Ancestors

Asn1TaggedEventHandler

Class variables

var MAXBYTESPERLINE
var lengthStack
var offset
var strbuf

Methods

def contents(self, data)

This method is invoked after each contents field is parsed. It formats and prints the contents in a hex/ascii format.

Parameters

data : bytes: Byte array containing encoded contents bytes.

def end_element(self)

This method is invoked after parsing is complete on each tag/length/value (TLV) in the message.

def start_element(self, tag, length, tagLenBytes)

This method is invoked after each tag/length value is parsed in the message being dumped. It formats and prints the tag/length values.

Parameters

tag : Asn1BerTag: Parsed tag value
length : Asn1BerLength: Parsed length value
tagLenBytes : bytes: Byte array containing the encoded tag/length bytes

class Asn1TaggedEventHandler

This class defines methods that must be implemented to define a SAX-like tagged event handler.

A tagged event handler returns tags from within a BER or DER message. This type of handler can be used to generically parse a message without knowledge of the associated ASN.1 schema definition. It is used in conjunction with the Asn1BerDecodeBuffer 'parse' method.

Subclasses

Asn1BerMessageDumpHandler

Methods

def contents(self, data)

The contents callback method is invoked when the contents of a primitive data element are parsed.

Parameters

data : bytes: Byte array containing encoded contents bytes.

def end_element(self)

The endElement callback method is invoked when the end of a tagged element is parsed.

def start_element(self, tag, length, tagLenBytes)

The startElement callback method is invoked when the start of any tagged element is parsed.

Parameters

tag : Asn1BerTag: Parsed tag value
length : Asn1BerLength: Parsed length value
tagLenBytes : bytes: Byte array containing the encoded tag/length bytes