Package org.ldaptive.asn1

Class DERParser

java.lang.Object

org.ldaptive.asn1.DERParser

public class DERParser
extends Object

This class provides a SAX-like parsing facility for DER-encoded data where elements of interest in the parse tree may be registered to handlers via the registerHandler(org.ldaptive.asn1.DERPath, org.ldaptive.asn1.ParseHandler) methods. DERPath strings are used to map handlers to elements of interest.

See Also:

DERPath

Field Summary

Fields

Modifier and Type	Field	Description
private Map<DERPath,ParseHandler>	handlerMap	Handlers for DER paths.
protected Logger	logger	Logger for this class.
private static int	MAX_PATH_DEPTH	Maximum supported path depth.
private static int	MAX_PERMUTATIONS	Maximum number of tag permutations allowed.
private Queue<DERPath>	permutations	Permutations of the current path.

Constructor Summary

Constructors

Constructor	Description
DERParser()

Method Summary

Modifier and Type	Method	Description
private void	addTag(DERTag tag, int index)	Add the given tag at the specified index to all permutations of the current parser path and increases the number of permutations as necessary to satisfy the following relation:
void	parse(DERBuffer encoded)	Parse a DER-encoded data structure by calling registered handlers when points of interest are encountered in the parse tree.
private void	parseTag(DERTag tag, DERBuffer encoded)	Invokes the parse handler for the current path and advances to the next position in the encoded bytes.
private void	parseTags(DERBuffer encoded)	Reads the supplied DER encoded bytes and invokes handlers as configured paths are encountered.
int	readLength(DERBuffer encoded)	Reads the length of a DER-encoded value from the given byte buffer.
DERTag	readTag(DERBuffer encoded)	Reads a DER tag from a single byte at the current position of the given buffer.
void	registerHandler(DERPath path, ParseHandler handler)	Registers the supplied handler to fire when the supplied path is encountered.
private void	removeTag()	Removes the tag at the leaf position of all permutations of the current parser path, and reduces the number of permutations as necessary to satisfy the following relation:

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MAX_PATH_DEPTH

private static final int MAX_PATH_DEPTH

Maximum supported path depth.

See Also:

Constant Field Values

MAX_PERMUTATIONS

private static final int MAX_PERMUTATIONS

Maximum number of tag permutations allowed.

logger

protected final Logger logger

Logger for this class.

handlerMap

private final Map<DERPath,ParseHandler> handlerMap

Handlers for DER paths.

permutations

private final Queue<DERPath> permutations

Permutations of the current path.

Constructor Detail

DERParser

public DERParser()

Method Detail

registerHandler

public void registerHandler(DERPath path,
                            ParseHandler handler)

Registers the supplied handler to fire when the supplied path is encountered.

Parameters:

path - to register

handler - to associate with the path

parse

public void parse(DERBuffer encoded)

Parse a DER-encoded data structure by calling registered handlers when points of interest are encountered in the parse tree.

Parameters:

encoded - DER-encoded bytes.

readTag

public DERTag readTag(DERBuffer encoded)

Reads a DER tag from a single byte at the current position of the given buffer. The buffer position is naturally advanced one byte in this operation.

Parameters:

encoded - Buffer containing DER-encoded bytes positioned at tag.

Returns:

Tag or null if no universal tag or application-specific tag is known that matches the byte read in.

readLength

public int readLength(DERBuffer encoded)

Reads the length of a DER-encoded value from the given byte buffer. The buffer is expected to be positioned at the byte immediately following the tag byte, which is where the length byte(s) begin(s). Invocation of this method has two generally beneficial side effects:

1. Buffer is positioned at start of value bytes.
2. Buffer limit is set to the end of value bytes.

Parameters:

encoded - buffer containing DER-encoded bytes positioned at start of length byte(s).

Returns:

number of bytes occupied by tag value.

parseTags

private void parseTags(DERBuffer encoded)

Reads the supplied DER encoded bytes and invokes handlers as configured paths are encountered.

Parameters:

encoded - to parse

parseTag

private void parseTag(DERTag tag,
                      DERBuffer encoded)

Invokes the parse handler for the current path and advances to the next position in the encoded bytes.

Parameters:

tag - to inspect for internal tags

encoded - to parse

addTag

private void addTag(DERTag tag,
                    int index)

Add the given tag at the specified index to all permutations of the current parser path and increases the number of permutations as necessary to satisfy the following relation:

size = 2^n

where n is the path length.

Parameters:

tag - to add to path.

index - of tag relative to parent.

removeTag

private void removeTag()

Removes the tag at the leaf position of all permutations of the current parser path, and reduces the number of permutations as necessary to satisfy the following relation:

size = 2^n

where n is the path length.