com.voytechs.jnetstream.codec
Interface Header

All Superinterfaces:

Identity

All Known Implementing Classes:

HeaderImpl, TCP

public interface Header
extends Identity

A header class that was decoded from a captured packet. Each packet contains a number of headers which in tern contain a number of fields.

The header does not contain any data from the capture file or stream. All data is contained within fields. You can query how many fields this header has using the getFieldCount() method and retrieve using the getField(int) or getField(String) method calls.

The header also contains a number of properties. Some properties are LOCAL and others are PERMANENT. Local properties are unrelated instances of some property and PERMANENT proporties are shared as a single instance between headers of the same type. That is a IPv4 headers will share a single instance of all PERMANENT properties defined for IPv4. They will each have a unique instance of LOCAL property though. Properties are stored as jnetstream.primitive.Primitive objects. To get actual data from the primitive object use method call chain form getProperty(String).getValue()

Headers do not contain other headers, only fields can contain other fields. Use the toString() method to printout very verbose output for the header. Each field is printed on separate line. This may produce large amount of output for a large header. I.e. X11 headers commonly produce more than 64Kbytes of text output this way.

To get less verbose output retrive the SUMMARY property for the header. The summary property contains a 1 line summary of the entire header. Below is an example of how to retrieve such a property.

 .... skipped try statement ....
 Decoder decoder = new Decoder("captureFile.pcap");
 Packet packet = decoder.nextPacket();
 Header header = packet.getHeader("IPv4");
 String summary = header.getProperty(Header.SUMMARY).getValue();
 .... skipped catch statements ....
 

Example:

 import com.voytechs.jnetstream.codec.Packet;
 import com.voytechs.jnetstream.codec.Header;
 import com.voytechs.jnetstream.codec.Field;
 import com.voytechs.jnetstream.codec.Decoder;
 import com.voytechs.jnetstream.io.StreamFormatException;
 import com.voytechs.jnetstream.npl.SyntaxError;
 import java.io.IOException;

 public class Tutorial1 {
     public static void main(String[] args) {
       try {
           Decoder decoder = new Decoder("myCaptureFile.pcap");
           Packet packet = null;
           Header header = null;
           Field field = null;
           
           while ( (packet = decoder.nextPacket()) != null) {
               header = packet.getHeader("IPv4");
           
               if (header != null) {
                   field = header.getField("hlen");
           
                   System.out.println("hlen=" + field.toString());
               } else {
                   System.out.println(packet.getProperty(Packet.SUMMARY));
               } 
           
           }
       } catch (StreamFormatException t) {
       } catch (IOException ie) {
       } catch (SyntaxError se) {
       }
     }
 }
 

Author:

Mark Bednarczyk

Field Summary

static java.lang.String	ABREVIATION Property contains abbreviation string for the header.
static java.lang.String	ACL Property contains defaul ACL for the header definition.
static java.lang.String	ADMINISTRATOR Property contains the username of the NetRepository administrator who maintains this header.
static java.lang.String	ANSI Property contains ANSI number.
static java.lang.String	AUTHOR Property contains the name of the author of the header.
static java.lang.String	COMMON Property contains common name for the header.
static java.lang.String	COMPANY Property contains the name of the company who owns the rights to the protocol and its headers.
static java.lang.String	COPYRIGHT Property contains copyright for the header defined.
static java.lang.String	CREATIONDATE Property contains the timestamp date of when the header definition was written.
static java.lang.String	CREATOR Property contains the name of the person who wrote the header definition and donated it to OpenSource.
static java.lang.String	DESCRIPTION Property contains full description of the header.
static java.lang.String	DOC Property contains DOC number.
static java.lang.String	HIDEHEADERLINE Property is a flag which indicates if the header output should be displayed or hidden.
static java.lang.String	HTTP Property contains URL HTTP address which contains more information about the header and the protocol.
static java.lang.String	IEEE Property contains IEEE number.
static java.lang.String	IETF Property contains IETF number.
static java.lang.String	IMTC Property contains IMTC number.
static java.lang.String	ITU Property contains ITU number.
static java.lang.String	NAME Property contains the name of this header.
static java.lang.String	OMG Property contains OMG number.
static java.lang.String	ORGANIZATION Property contains the name of the organization who owns the rights to the protocol and its headers if COMPANY is not appropriate.
static java.lang.String	OSILAYER Property contains OSI layer number.
static java.lang.String	RFC Property contains RFC number.
static java.lang.String	SHORTDESCRIPTION Property contains short single linde description for the header.
static java.lang.String	SHORTHEADER Property contains a summary line of the header.
static java.lang.String	STD Property contains RFC's STD number.
static java.lang.String	SUMMARY Property contains single line summary of most important header fields.
static java.lang.String	TRADEMARK Property contains trademark information for the header.
static java.lang.String	W3C Property contains W3C number.

Fields inherited from interface com.voytechs.jnetstream.codec.Identity

SHORT_NAME

Method Summary

Field	getField(int index) Returns the requested field by index.
Field	getField(java.lang.String name) Returns the requested field by name.
int	getFieldCount() Returns the number of fields within this header.
Header	getHeader(int index) Returns the indexed header from the packet.
Header	getHeader(java.lang.String name) Returns the named header from the packet.
int	getHeaderCount() Returns the number of headers in this packet.
int	getHeaderLength() Get the length of the header in bytes.
java.lang.Object	getValue(int index) Conveniece method to retrieve a value of a field directly.
java.lang.Object	getValue(java.lang.String name) Conveniece method to retrieve a value of a field or propert directly.
boolean	hasHeader(java.lang.String name) Checks to if the specified header exists in the packet.

Methods inherited from interface com.voytechs.jnetstream.codec.Identity

getName, getProperty

Field Detail

NAME

static final java.lang.String NAME

Property contains the name of this header. This is a PERMENENT String property. Returns the name assigned to the header.

See Also:

Constant Field Values

SUMMARY

static final java.lang.String SUMMARY

Property contains single line summary of most important header fields. This is a LOCAL String property. Header definition creates the SUMMARY property using what are the most import fields of the header.

See Also:

Constant Field Values

COMMON

static final java.lang.String COMMON

Property contains common name for the header. This is a PERMANENT String property. Common name given to the protocol. Normally overrides what is output to the user, if the NAME property is too akward.

See Also:

Constant Field Values

RFC

static final java.lang.String RFC

Property contains RFC number. This is a PERMANENT Integer property.

See Also:

Constant Field Values

STD

static final java.lang.String STD

Property contains RFC's STD number. This is a PERMANENT Integer property.

See Also:

Constant Field Values

IEEE

static final java.lang.String IEEE

Property contains IEEE number. This is a PERMANENT String property.

See Also:

Constant Field Values

IMTC

static final java.lang.String IMTC

Property contains IMTC number. This is a PERMANENT String property.

See Also:

Constant Field Values

ITU

static final java.lang.String ITU

Property contains ITU number. This is a PERMANENT String property.

See Also:

Constant Field Values

OMG

static final java.lang.String OMG

Property contains OMG number. This is a PERMANENT String property.

See Also:

Constant Field Values

W3C

static final java.lang.String W3C

Property contains W3C number. This is a PERMANENT String property.

See Also:

Constant Field Values

IETF

static final java.lang.String IETF

Property contains IETF number. This is a PERMANENT String property.

See Also:

Constant Field Values

ANSI

static final java.lang.String ANSI

Property contains ANSI number. This is a PERMANENT String property.

See Also:

Constant Field Values

DOC

static final java.lang.String DOC

Property contains DOC number. This is a PERMANENT String property.

See Also:

Constant Field Values

OSILAYER

static final java.lang.String OSILAYER

Property contains OSI layer number. This is a PERMANENT Integer property. OSI layer determines the header type according to OSI layer table:

1. Physical
2. Data Link
3. Network
4. Transport
5. Session
6. Representation
7. Application

See Also:

Constant Field Values

DESCRIPTION

static final java.lang.String DESCRIPTION

Property contains full description of the header. This is a PERMANENT String property. This description is used by applications to display help information about the header.

See Also:

Constant Field Values

SHORTHEADER

static final java.lang.String SHORTHEADER

Property contains a summary line of the header. This is a LOCAL String property. Short header is slightly different from SUMMARY property in that it is used to display at top of header titles.

See Also:

Constant Field Values

COMPANY

static final java.lang.String COMPANY

Property contains the name of the company who owns the rights to the protocol and its headers. This is a PERMANENT String property.

See Also:

Constant Field Values

ORGANIZATION

static final java.lang.String ORGANIZATION

Property contains the name of the organization who owns the rights to the protocol and its headers if COMPANY is not appropriate. This is a PERMANENT String property.

See Also:

Constant Field Values

COPYRIGHT

static final java.lang.String COPYRIGHT

Property contains copyright for the header defined. Copyright notice will always be displayed to the user when the header is encountered. This is a PERMANENT String property.

See Also:

Constant Field Values

TRADEMARK

static final java.lang.String TRADEMARK

Property contains trademark information for the header. This is a PERMANENT String property.

See Also:

Constant Field Values

SHORTDESCRIPTION

static final java.lang.String SHORTDESCRIPTION

Property contains short single linde description for the header. This property is PERMANENT String property. Just like DESCRIPTION Property but shorter.

See Also:

Constant Field Values

ABREVIATION

static final java.lang.String ABREVIATION

Property contains abbreviation string for the header. This property is PERMANENT String property.

See Also:

Constant Field Values

HTTP

static final java.lang.String HTTP

Property contains URL HTTP address which contains more information about the header and the protocol. This is a PERMANENT String property.

See Also:

Constant Field Values

AUTHOR

static final java.lang.String AUTHOR

Property contains the name of the author of the header. This property is PERMANENT String property. Author is different from the creator of the definition for the protocol.

See Also:

Constant Field Values

CREATOR

static final java.lang.String CREATOR

Property contains the name of the person who wrote the header definition and donated it to OpenSource. This property is PERMANENT String property.

See Also:

Constant Field Values

ADMINISTRATOR

static final java.lang.String ADMINISTRATOR

Property contains the username of the NetRepository administrator who maintains this header. This is a PERMANENT String property. NetRepository is an online database of protocols which are user accessible. This property contains the username of the protocol who maintains the definition of this header.

See Also:

Constant Field Values

CREATIONDATE

static final java.lang.String CREATIONDATE

Property contains the timestamp date of when the header definition was written. This is a PERMANENT String property.

See Also:

Constant Field Values

ACL

static final java.lang.String ACL

Property contains defaul ACL for the header definition. This is a PERMANENT String property. ACL is used to determine how the header definition may be used or not used.

See Also:

Constant Field Values

HIDEHEADERLINE

static final java.lang.String HIDEHEADERLINE

Property is a flag which indicates if the header output should be displayed or hidden. This is a LOCAL or PERMANENT Integer property.

See Also:

Constant Field Values

Method Detail

getField

Field getField(java.lang.String name)

Returns the requested field by name. If the field with requested name is not found, null is returned.

Returns:

The requested field or null if not found.

getField

Field getField(int index)

Returns the requested field by index. If the index is out of range then null is returned.

Returns:

The requested field or null if index out of range.

getFieldCount

int getFieldCount()

Returns the number of fields within this header. The count does not count any subfields of fields, only its direct children fields.

Returns:

Number of direct children contained within this field.

getValue

java.lang.Object getValue(java.lang.String name)

Conveniece method to retrieve a value of a field or propert directly.

Parameters:

name - Field or property name to retrieve the value from.

Returns:

Opaque value of the field or property.

Since:

JNetStream 0.2.2

getValue

java.lang.Object getValue(int index)

Conveniece method to retrieve a value of a field directly.

Parameters:

index - Index of the field within the header to retrieve the value from.

Returns:

Opaque value of the field.

Since:

JNetStream 0.2.2

getHeaderLength

int getHeaderLength()

Get the length of the header in bytes.

Returns:

length of the header in bytes.

getHeaderCount

int getHeaderCount()

Returns the number of headers in this packet.

Packet is made up of a number of headers that the decoder was able to decode from the capture file or stream.

Returns:

Number of headers found in this packet.

hasHeader

boolean hasHeader(java.lang.String name)

Checks to if the specified header exists in the packet. You can also check for the "Data" header using this method, although there is a convience method hasDataHeader()

Parameters:

name - name of the header to check for.

Returns:

true if header exists in the packet, otherwise false.

getHeader

Header getHeader(java.lang.String name)

Returns the named header from the packet. If the header with the given name is not found, null is returned.

Packet is made up of a number of headers that the decoder was able to decode from the capture file or stream. To find out how many headers use the getHeaderCount() method call.

Returns:

The header if found, otherwise nul..

getHeader

Header getHeader(int index)

Returns the indexed header from the packet. If index is out of range then null is returned.

Packet is made up of a number of headers that the decoder was able to decode from the capture file or stream. To find out how many headers use the getHeaderCount() method call.

Returns:

The header found at this header index within the packet. Header are added and stored within the packet in the order they were decoded. null is returned if index is out of range.