DNSAddressRequest (OpenNMS 2021.1.1 API)

java.lang.Object
- org.opennms.netmgt.provision.support.dns.DNSAddressRequest

public class DNSAddressRequest
extends Object


 The DNSAddressRequest holds a DNS request to lookup the IP address of a host -
 provides for transmitting and receiving the response for this lookup.

 NOTES: A DNS request and response has the following fileds header questions
 answers authorities additional information

 The header has the following format: id - unique id sent by the client and
 returned by the server in its response 16 bits of flags -
 Query(0)/response(1) flag opcode - that has type of query AA - set if the
 response is an authoritative answer TC - set if response is truncated RD -
 set if recursion is desired RA - set if recursion is available Z - reserved
 bits RCODE - response code

 This class checks only for the received response to have the answer(which
 will hold the IP address) - ignores the authorities and additional info

Author:: Sowmya

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`CLASS_IN` Defines the class internet in the domain name system.
`List<DNSAddressRR>`	`m_answers` The list of answers.
`boolean`	`m_authoritative` True if the answer is authoratitve.
`boolean`	`m_recursive` True if the message is recursive.
`String`	`m_reqHost` The host to request information from.
`int`	`m_reqID` The id used to seralize the request.
`boolean`	`m_truncated` True if the message is truncated.
`static int`	`OPCODE_QUERY` The op code for a query in the header.
`static int`	`SHIFT_AUTHORITATIVE` The offset of the authoritative bit in the header.
`static int`	`SHIFT_OPCODE` The offset of the opcode bits in the header.
`static int`	`SHIFT_QUERY` The offset of the query bit in the header.
`static int`	`SHIFT_RECURSE_AVAILABLE` The offset of the requrse avail bit in the header.
`static int`	`SHIFT_RECURSE_PLEASE` The offset of the recurse req bit in the header.
`static int`	`SHIFT_RESERVED` The offset of the reserved bits in the header.
`static int`	`SHIFT_RESPONSE_CODE` The offset of the response code bits in the header.
`static int`	`SHIFT_TRUNCATED` The offset of the truncated bit in the header.
`static int`	`TYPE_ADDR` Defines the address type.

Constructor Summary

Constructors
Constructor and Description

DNSAddressRequest(String host)
Constructs a DNSAddressRequest for ths hostname passed.

Constructors
Constructor and Description
`DNSAddressRequest(String host)` Constructs a DNSAddressRequest for ths hostname passed.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`byte[]`	`buildRequest()` Builds the address request.
`static String`	`codeName(int code)` Returns the code string for the error code recieved.
`List<DNSAddressRR>`	`getAnswers()` Return an enumeration of the recieved answers.
`String`	`getHost()` The hostname that will be request from the DNS box.
`int`	`getRequestID()` The request id for this particular instance.
`boolean`	`isAuthoritative()` Returns true if the answer is authoritative.
`boolean`	`isRecursive()` Returns true if the answer is recursive.
`boolean`	`isTruncated()` Returns true if the answer is truncated.
`void`	`receiveResponse(byte[] data, int length)` Extracts the response from the bytearray.
`void`	`verifyResponse(byte[] data, int length)` This method only goes so far as to decode the flags in the response byte array to verify that a DNS server sent the response.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - CLASS_IN
```
public static final int CLASS_IN
```
    Defines the class internet in the domain name system.
    
    See Also:
    
    Constant Field Values
  - TYPE_ADDR
```
public static final int TYPE_ADDR
```
    Defines the address type.
    
    See Also:
    
    Constant Field Values
  - SHIFT_QUERY
```
public static final int SHIFT_QUERY
```
    The offset of the query bit in the header.
    
    See Also:
    
    Constant Field Values
  - SHIFT_OPCODE
```
public static final int SHIFT_OPCODE
```
    The offset of the opcode bits in the header.
    
    See Also:
    
    Constant Field Values
  - SHIFT_AUTHORITATIVE
```
public static final int SHIFT_AUTHORITATIVE
```
    The offset of the authoritative bit in the header.
    
    See Also:
    
    Constant Field Values
  - SHIFT_TRUNCATED
```
public static final int SHIFT_TRUNCATED
```
    The offset of the truncated bit in the header.
    
    See Also:
    
    Constant Field Values
  - SHIFT_RECURSE_PLEASE
```
public static final int SHIFT_RECURSE_PLEASE
```
    The offset of the recurse req bit in the header.
    
    See Also:
    
    Constant Field Values
  - SHIFT_RECURSE_AVAILABLE
```
public static final int SHIFT_RECURSE_AVAILABLE
```
    The offset of the requrse avail bit in the header.
    
    See Also:
    
    Constant Field Values
  - SHIFT_RESERVED
```
public static final int SHIFT_RESERVED
```
    The offset of the reserved bits in the header.
    
    See Also:
    
    Constant Field Values
  - SHIFT_RESPONSE_CODE
```
public static final int SHIFT_RESPONSE_CODE
```
    The offset of the response code bits in the header.
    
    See Also:
    
    Constant Field Values
  - OPCODE_QUERY
```
public static final int OPCODE_QUERY
```
    The op code for a query in the header.
    
    See Also:
    
    Constant Field Values
  - m_reqHost
```
public String m_reqHost
```
    The host to request information from. This would be the nameserver if it supports DNS.
  - m_reqID
```
public int m_reqID
```
    The id used to seralize the request. This allows the client (us) and the server (host) to match exchanges.
  - m_authoritative
```
public boolean m_authoritative
```
    True if the answer is authoratitve.
  - m_truncated
```
public boolean m_truncated
```
    True if the message is truncated.
  - m_recursive
```
public boolean m_recursive
```
    True if the message is recursive.
  - m_answers
```
public List<DNSAddressRR> m_answers
```
    The list of answers.
- Constructor Detail
  - DNSAddressRequest
```
public DNSAddressRequest(String host)
```
    Constructs a DNSAddressRequest for ths hostname passed. The host string that is passed to the address string should be a hostname in "x.y.z" where x, y, and z are strings. This is not suppose to be a dotted decimal address.
    
    Parameters:
    
    host - hostname for which address is to be constructed
- Method Detail
  - buildRequest
```
public byte[] buildRequest()
                    throws IOException
```
    Builds the address request.
    
    Returns:
    
    A byte array containing the request.
    
    Throws:
    
    IOException - if any.
  - receiveResponse
```
public void receiveResponse(byte[] data,
                            int length)
                     throws IOException
```
    Extracts the response from the bytearray.
    
    Parameters:
    
    data - The byte array containing the response.
    
    length - The length of the byte array.
    
    Throws:
    
    IOException - Thrown if there is an error while reading the recieved packet
    
    IOException - if any.
  - verifyResponse
```
public void verifyResponse(byte[] data,
                           int length)
                    throws IOException
```
    This method only goes so far as to decode the flags in the response byte array to verify that a DNS server sent the response.
    
    NOTE: This is really a hack to get around the fact that the receiveResponse() method is not robust enough to handle all possible DNS server responses.
    
    Parameters:
    
    data - The byte array containing the response.
    
    length - The length of the byte array.
    
    Throws:
    
    IOException - Thrown if there is an error while reading the recieved packet
    
    IOException - if any.
  - getAnswers
```
public List<DNSAddressRR> getAnswers()
```
    Return an enumeration of the recieved answers.
    
    Returns:
    
    The list of received answers.
  - getRequestID
```
public int getRequestID()
```
    The request id for this particular instance.
    
    Returns:
    
    a int.
  - getHost
```
public String getHost()
```
    The hostname that will be request from the DNS box.
    
    Returns:
    
    a String object.
  - isTruncated
```
public boolean isTruncated()
```
    Returns true if the answer is truncated.
    
    Returns:
    
    a boolean.
  - isRecursive
```
public boolean isRecursive()
```
    Returns true if the answer is recursive.
    
    Returns:
    
    a boolean.
  - isAuthoritative
```
public boolean isAuthoritative()
```
    Returns true if the answer is authoritative.
    
    Returns:
    
    a boolean.
  - codeName
```
public static String codeName(int code)
```
    Returns the code string for the error code recieved.
    
    Parameters:
    
    code - The error code.
    
    Returns:
    
    The error string corresponding to the error code

Class DNSAddressRequest

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

CLASS_IN

TYPE_ADDR

SHIFT_QUERY

SHIFT_OPCODE

SHIFT_AUTHORITATIVE

SHIFT_TRUNCATED

SHIFT_RECURSE_PLEASE

SHIFT_RECURSE_AVAILABLE

SHIFT_RESERVED

SHIFT_RESPONSE_CODE

OPCODE_QUERY

m_reqHost

m_reqID

m_authoritative

m_truncated

m_recursive

m_answers

Constructor Detail

DNSAddressRequest

Method Detail

buildRequest

receiveResponse

verifyResponse

getAnswers

getRequestID

getHost

isTruncated

isRecursive

isAuthoritative

codeName