DNS服務檢測

摘自openNMS,檢測DNS服務

import java.io.IOException;

import java.io.InterruptedIOException;

import java.lang.reflect.UndeclaredThrowableException;

import java.net.ConnectException;

import java.net.DatagramPacket;

import java.net.DatagramSocket;

import java.net.InetAddress;

import java.net.NoRouteToHostException;

import java.net.UnknownHostException;

public class TestDns {

public static void main(String[] args){

// get the parameters

int retry = 2;

int port = 53;

int timeout = 3000;

// Host to lookup?

String lookup = "www.google.com";

if (lookup == null || lookup.length() == 0) {

// Get hostname of local machine for future DNS lookups

try {

lookup = InetAddress.getLocalHost().getHostName();

} catch (UnknownHostException ukE) {

// Recast the exception as a Service Monitor Exception

ukE.fillInStackTrace();

throw new UndeclaredThrowableException(ukE);

}

// get the address and DNS address request

InetAddress ipv4Addr = null;

try {

ipv4Addr = InetAddress.getByName("165.87.13.129");

} catch (UnknownHostException e1) {

// TODO Auto-generated catch block

e1.printStackTrace();

}

DNSAddressRequest request = new DNSAddressRequest(lookup);

int serviceStatus = -1;

DatagramSocket socket = null;

long responseTime = -1;

try {

socket = new DatagramSocket();

socket.setSoTimeout(timeout); // will force the

// InterruptedIOException

for (int attempts = 0; attempts <= retry && serviceStatus != 1; attempts++) {

try {

// Send DNS request

byte[] data = request.buildRequest();

DatagramPacket outgoing = new DatagramPacket(data, data.length, ipv4Addr, port);

long sentTime = System.currentTimeMillis();

socket.send(outgoing);

// Get DNS Response

byte[] buffer = new byte[512];

DatagramPacket incoming = new DatagramPacket(buffer, buffer.length);

socket.receive(incoming);

responseTime = System.currentTimeMillis() - sentTime;

// Validate DNS Response

// IOException thrown if packet does not decode as expected.

request.verifyResponse(incoming.getData(), incoming.getLength());

System.out.println(incoming.getAddress());

System.out.println("poll: valid DNS request received, responseTime= " + responseTime + "ms");

serviceStatus = 1;

} catch (InterruptedIOException ex) {

// Ignore, no response received.

}

} catch (NoRouteToHostException e) {

e.fillInStackTrace();

System.out.println("No route to host exception for address: " + ipv4Addr);

} catch (ConnectException e) {

// Connection refused. Continue to retry.

e.fillInStackTrace();

System.out.println("Connection exception for address: " + ipv4Addr);

} catch (IOException ex) {

ex.fillInStackTrace();

System.out.println("IOException while polling address: " + ipv4Addr);

} finally {

if (socket != null)

socket.close();

}

// Store response time if available

if (serviceStatus == 1) {

System.out.println("response time="+responseTime);

}

DNSAddressRequest.java

// This file is part of the OpenNMS(R) Application.

// OpenNMS(R) is a derivative work, containing both original code, included code and modified

// code that was published under the GNU General Public License. Copyrights for modified

// and included code are below.

// OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc.

// This program is free software; you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation; either version 2 of the License, or

// (at your option) any later version.

// This program is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License

// along with this program; if not, write to the Free Software

// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

// For more information contact:

// OpenNMS Licensing <[email protected]>

// http://www.opennms.org/

// http://www.opennms.com/

import java.io.ByteArrayOutputStream;

import java.io.DataOutputStream;

import java.io.IOException;

import java.util.ArrayList;

import java.util.List;

import java.util.StringTokenizer;

/**

* <PRE>

* 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

* </PRE>

* @author <A HREF="mailto:[email protected]">Sowmya </A>

* @author <A HREF="http://www.opennms.org/">OpenNMS </A>

public class DNSAddressRequest {

/**

*

* Defines the class internet in the domain name system.

*

public final int CLASS_IN = 1; // internet

/**

*

* Defines the address type.

*

public final int TYPE_ADDR = 1; // address

/**

*

* The offset of the query bit in the header.

*

public final int SHIFT_QUERY = 15;

/**

*

* The offset of the opcode bits in the header.

*

public final int SHIFT_OPCODE = 11;

/**

*

* The offset of the authoritative bit in the header.

*

public final int SHIFT_AUTHORITATIVE = 10;

/**

*

* The offset of the truncated bit in the header.

*

public final int SHIFT_TRUNCATED = 9;

/**

*

* The offset of the recurse req bit in the header.

*

public final int SHIFT_RECURSE_PLEASE = 8;

/**

*

* The offset of the requrse avail bit in the header.

*

public final int SHIFT_RECURSE_AVAILABLE = 7;

/**

*

* The offset of the reserved bits in the header.

*

public final int SHIFT_RESERVED = 4;

/**

*

* The offset of the response code bits in the header.

*

public final int SHIFT_RESPONSE_CODE = 0;

/**

*

* The op code for a query in the header.

*

public final int OPCODE_QUERY = 0;

/**

*

* The host to request information from. This would be the nameserver if it

* supports DNS.

*

public String m_reqHost;

/**

*

* The id used to seralize the request. This allows the client (us) and the

* server (host) to match exchanges.

*

public int m_reqID;

/**

*

* True if the answer is authoratitve.

*

public boolean m_authoritative;

/**

*

* True if the message is truncated.

*

public boolean m_truncated;

/**

*

* True if the message is recursive.

public boolean m_recursive;

/**

*

* The list of answers.

*

public List m_answers;

/**

*

* The global id, used to get the request id.

*

private static int globalID = 1;

/**

*

* Decodes the integer to get the flags - refer header for more info on the

* flags.

*

private void decodeFlags(int flags) throws IOException {

// check the response flag

boolean isResponse = ((flags >> SHIFT_QUERY) & 1) != 0;

if (!isResponse)

throw new IOException("Response flag not set");

// check if error free

int code = (flags >> SHIFT_RESPONSE_CODE) & 15;

if (code != 0) {

if (code == 2) // Throw exception if error code indicates 'Server

// Failure'

throw new IOException(codeName(code) + " (" + code + ")");

}

// set the members of the instance.

m_authoritative = ((flags >> SHIFT_AUTHORITATIVE) & 1) != 0;

m_truncated = ((flags >> SHIFT_TRUNCATED) & 1) != 0;

m_recursive = ((flags >> SHIFT_RECURSE_AVAILABLE) & 1) != 0;

}

/**

*

* 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.

*

* @param host

* hostname for which address is to be constructed

public DNSAddressRequest(String host) {

// Split the host into its component

// parts.

StringTokenizer labels = new StringTokenizer(host, ".");

while (labels.hasMoreTokens()) {

// if any section is longer than

// 63 characters then it's illegal

if (labels.nextToken().length() > 63)

throw new IllegalArgumentException("Invalid hostname: " + host);

}

// The requested host

m_reqHost = host;

// Synchronize on the class, not

// the instance.

synchronized (getClass()) {

m_reqID = globalID % 65536;

globalID = m_reqID + 1; // prevents negative numbers.

}

m_answers = new ArrayList();

}

/**

*

* Builds the address request.

*

* @return A byte array containing the request.

public byte[] buildRequest() throws IOException {

ByteArrayOutputStream byteArrayOut = new ByteArrayOutputStream();

DataOutputStream dataOut = new DataOutputStream(byteArrayOut);

dataOut.writeShort(m_reqID);

dataOut.writeShort((0 << SHIFT_QUERY) | (OPCODE_QUERY << SHIFT_OPCODE) | (1 << SHIFT_RECURSE_PLEASE));

dataOut.writeShort(1); // # queries

dataOut.writeShort(0); // # answers

dataOut.writeShort(0); // # authorities

dataOut.writeShort(0); // # additional

StringTokenizer labels = new StringTokenizer(m_reqHost, ".");

while (labels.hasMoreTokens()) {

String label = labels.nextToken();

dataOut.writeByte(label.length());

dataOut.writeBytes(label);

}

dataOut.writeByte(0);

dataOut.writeShort(TYPE_ADDR);

dataOut.writeShort(CLASS_IN);

return byteArrayOut.toByteArray();

}

/**

*

* Extracts the response from the bytearray.

*

* @param data

* The byte array containing the response.

* @param length

* The length of the byte array.

* @exception IOException

* Thrown if there is an error while reading the recieved

* packet

public void receiveResponse(byte[] data, int length) throws IOException {

* Decode the input stream.

DNSInputStream dnsIn = new DNSInputStream(data, 0, length);

int id = dnsIn.readShort();

if (id != m_reqID)

throw new IOException("ID does not match request");

// read in the flags

int flags = dnsIn.readShort();

decodeFlags(flags);

int numQueries = dnsIn.readShort();

int numAnswers = dnsIn.readShort();

int numAuthorities = dnsIn.readShort();

int numAdditional = dnsIn.readShort();

while (numQueries-- > 0) {

// discard questions

String rname = dnsIn.readDomainName();

int rtype = dnsIn.readShort();

int rclass = dnsIn.readShort();

}

try {

while (numAnswers-- > 0)

m_answers.add(dnsIn.readRR());

// ignore the authorities and additional information

/**

* while (numAuthorities -- > 0) dnsIn.readRR (); while

* (numAdditional -- > 0) dnsIn.readRR ();

} catch (IOException ex) {

if (!m_truncated)

throw ex;

}

/**

*

* 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.

* @param data

* The byte array containing the response.

* @param length

* The length of the byte array.

* @exception IOException

* Thrown if there is an error while reading the recieved

* packet

public void verifyResponse(byte[] data, int length) throws IOException {

* Decode the input stream.

DNSInputStream dnsIn = new DNSInputStream(data, 0, length);

int id = dnsIn.readShort();

if (id != m_reqID)

throw new IOException("ID does not match request");

// read in the flags

int flags = dnsIn.readShort();

decodeFlags(flags);

}

/**

*

* Return an enumeration of the recieved answers.

*

* @return The list of received answers.

public List getAnswers() {

return m_answers;

}

/**

*

* The request id for this particular instance.

*

public int getRequestID() {

return m_reqID;

}

/**

*

* The hostname that will be request from the DNS box.

*

public String getHost() {

return m_reqHost;

}

/**

*

* Returns true if the answer is truncated.

*

public boolean isTruncated() {

return m_truncated;

}

/**

*

* Returns true if the answer is recursive.

*

public boolean isRecursive() {

return m_recursive;

}

/**

*

* Returns true if the answer is authoritative.

*

public boolean isAuthoritative() {

return m_authoritative;

}

/**

*

* Returns the code string for the error code recieved.

*

* @param code

* The error code.

* @return The error string corresponding to the error code

public static String codeName(int code) {

String[] codeNames = { "Format error", "Server failure", "Name not known", "Not implemented", "Refused" };

return ((code >= 1) && (code <= 5)) ? codeNames[code - 1] : "Unknown error";

}

DNSInputStream.java

// This file is part of the OpenNMS(R) Application.

// OpenNMS(R) is a derivative work, containing both original code, included code and modified

// code that was published under the GNU General Public License. Copyrights for modified

// and included code are below.

// OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc.

// This program is free software; you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation; either version 2 of the License, or

// (at your option) any later version.

// This program is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License

// along with this program; if not, write to the Free Software

// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

// For more information contact:

// OpenNMS Licensing <[email protected]>

// http://www.opennms.org/

// http://www.opennms.com/

import java.io.ByteArrayInputStream;

import java.io.EOFException;

import java.io.IOException;

/**

*

* DNSInputStrean extends a ByteArrayInputStream and has methods to decode the

* data of a DNS response to an address resquest.

*

* @author <A HREF="mailto:[email protected]">Sowmya </A>

* @author <A HREF="http://www.opennms.org">OpenNMS </A>

public class DNSInputStream extends ByteArrayInputStream {

/**

*

* Constructs a new input stream for decoding DNS records.

*

* @param data

* The array of data to pass to the base class.

public DNSInputStream(byte[] data) {

super(data);

}

/**

*

* Constructs a DNSInputStream object from the byte array.

*

* @param data

* byte array containing the response data

* @param off

* offset of the data in the byte array

* @param len

* length of the byte array

public DNSInputStream(byte[] data, int off, int len) {

super(data, off, len);

}

/**

*

* Read a byte off the input stream.

*

* @return The integer read.

* @exception java.io.IOException

* Thrown if the end-of-file is encountered trying to read

* the next byte.

public int readByte() throws IOException {

int rc = read();

if (rc == -1)

throw new EOFException("end of buffer on read");

return rc;

}

/**

*

* Read a 'short' off the input stream.

*

* @return The short from the input stream.

* @exception java.io.IOException

* Thrown if the end-of-file is encountered trying to read

* the next short.

public int readShort() throws IOException {

return (readByte() << 8 | readByte());

}

/**

*

* Read an 'int' off the input stream.

*

* @return The int from the input stream.

* @exception java.io.IOException

* Thrown if there is an error while read.

public long readInt() throws IOException {

long rc = 0;

for (int i = 0; i < 4; i++)

rc = (rc << 8) | readByte();

return rc;

}

/**

*

* Read a 'string' off the input stream.

*

* @return the string from the input stream

* @exception java.io.IOException

* Thrown if there is an error while read

public String readString() throws IOException {

int len = readByte();

if (len == 0) {

return "";

}

byte[] buffer = new byte[len];

int rc = read(buffer);

if (rc == -1 || rc != len)

throw new EOFException("end of file while reading array");

return new String(buffer);

}

/**

*

* The readDomainName method is used to read an entire domain name from the

* stream. The string returned will be the concatentation of several

* substrings, each substring in the record is separated by a '.'(dot). For

* more information see the RFC for the distributed name service.

*

* @return The domain name string.

* @exception java.io.IOException

* Thrown if an error occurs decoding the string from the

* stream.

public String readDomainName() throws IOException {

// Check to make sure that we are not going

// to index the array and generate an bounds

// exception.

if (pos >= count)

throw new EOFException("EOF reading domain name");

// check the length byte. If the upper two bits are

// not set then it is a normal string and can be

// decoded using the readString() method.

if ((buf[pos] & 0xc0) == 0) {

String label = readString();

if (label.length() > 0) {

// get the next component(s) of the

// domain name. This is a recursive call.

// If the length is not equal to null then

// append the tail and return the new domain

// name.

String tail = readDomainName();

if (tail.length() > 0)

label = label + '.' + tail;

}

return label;

}

// If this point in the code is reached then

// compression is being used!

// If the upper two bits were set then this is a special

// encoding that points us to somewhere else in the record!

// We have to read that part of the record and to get the

// next element in the stream.

// Throw an I/O exception if the compression offset is

// malformed.

if ((buf[pos] & 0xc0) != 0xc0)

throw new IOException("Invalid domain name compression offset");

// read the short that is the pointer to the other

// part of the stream. Note buf is a protected buffer.

int offset = readShort() & 0x3fff;

DNSInputStream dnsIn = new DNSInputStream(buf, offset, buf.length - offset);

return dnsIn.readDomainName();

}

/**

*

* Reads the resource record from the input stream.

*

* @return The DNSAddressRR that is in response to the address request.

* @exception java.io.IOException

* Thrown if data does not decode to a DNSAddressRRl.

public DNSAddressRR readRR() throws IOException {

String rrName = readDomainName();

int rrType = readShort();

int rrClass = readShort();

long rrTTL = readInt();

int rrDataLen = readShort();

// Convert the length of data in this byte array input stream

// into a "substream" of data. The only way this could get

// complicated is if there are multiple threads using this

// stream. If that is the case then synchronization code

// should be used to wrap the next two lines -- Weave

DNSInputStream rrDNSIn = new DNSInputStream(buf, pos, rrDataLen);

pos += rrDataLen;

try {

// Create the route record and return it to

// the caller.

DNSAddressRR rr = new DNSAddressRR(rrName, rrType, rrClass, rrTTL, rrDNSIn);

return rr;

} catch (Exception ex) {

throw new IOException("Unknown DNSAddressRR (type " + " (" + rrType + "))" + " Originating Exception: " + ex.getMessage());

}

DNSAddressRR.java

// This file is part of the OpenNMS(R) Application.

// OpenNMS(R) is a derivative work, containing both original code, included code and modified

// code that was published under the GNU General Public License. Copyrights for modified

// and included code are below.

// OpenNMS(R) is a registered trademark of The OpenNMS Group, Inc.

// This program is free software; you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation; either version 2 of the License, or

// (at your option) any later version.

// This program is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License

// along with this program; if not, write to the Free Software

// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

// For more information contact:

// OpenNMS Licensing <[email protected]>

// http://www.opennms.org/

// http://www.opennms.com/

import java.io.IOException;

import java.net.InetAddress;

import java.net.UnknownHostException;

/**

*

* Holds a DNS resource record which is a DNS response that gives the IP address

* of a particular hostname. A resource record typically has:

*

* <TABLE BORDER=0>

* <TH>

* <TD>Element</TD>

* <TD>Description</TD>

* </TH>

* <TR>

* <TD>Name</TD>

* <TD>Domain name that the resource record describes.</TD>

* </TR>

* <TR>

* <TD>Type</TD>

* <TD>Type of RR.</TD>

* </TR>

* <TR>

* <TD>Class</TD>

* <TD>RR Class.</TD>

* </TR>

* <TR>

* <TD>TTL</TD>

* <TD>Time-To-Live for the RR.</TD>

* </TR>

* <TR>

* <TD>RDLEN</TD>

* <TD>Length of the following data.</TD>

* </TR>

* <TR>

* <TD>Data</TD>

* <TD>Actual data of this RR.</TD>

* </TR>

* </TABLE>

* @author <A HREF="mailto:[email protected]">Sowmya </A>

* @author <A HREF="http://www.opennms.org/">OpenNMS </A>

public final class DNSAddressRR {

/**

*

* Name of this RR.

*

private String m_name;

/**

*

* Type of this RR.

*

private int m_type;

/**

*

* Class of this RR.

*

private int m_class;

/**

*

* Time to live for this RR.

*

private long m_TTL;

/**

*

* Time at which this RR was created.

*

private long m_created;

/**

*

* The IP Address for the Route Record.

*

private int[] ipAddress;

/**

*

* Returns the address in the dotted decimal format.

*

* @return The address in the dotted decimal format.

private String AddressToByteString() {

return ipAddress[0] + "." + ipAddress[1] + "." + ipAddress[2] + "." + ipAddress[3];

}

/**

*

* Constructs an new DNS Address Resource Record with the specified

* information.

*

* @param name

* name of the RR

* @param type

* type of the RR

* @param clas

* class of the RR

* @param ttl

* time for which this RR is valid

* @param dnsIn

* inputstream for this RR

* @exception java.io.IOException

* Thrown if an error occurs decoding data from the passed

* DNSInputStream.

public DNSAddressRR(String name, int type, int clas, long ttl, DNSInputStream dnsIn) throws IOException {

m_name = name;

m_type = type;

m_class = clas;

m_TTL = ttl;

m_created = System.currentTimeMillis();

// decode

ipAddress = new int[4];

for (int i = 0; i < 4; ++i) {

ipAddress[i] = dnsIn.readByte();

}

/**

*

* Returns the address from the address record as a byte array.

*

* @return The address as a byte array.

public byte[] getAddress() {

byte[] ip = new byte[4];

for (int j = 0; j < 4; j++)

ip[j] = (byte) (ipAddress[j]);

return ip;

}

/**

*

* the InetAddress of the address contained for the record.

*

* @return The InetAddress of the address

* @exception java.net.UnknownHostException

* Thrown if the InetAddress object cannot be constructed.

public InetAddress getInetAddress() throws UnknownHostException {

return InetAddress.getByName(AddressToByteString());

}

/**

*

* Converts the object to a textual string that describes the resource

* record.

*

* @return The string describing the object.

public String toString() {

return getRRName() + " Internet Address = " + AddressToByteString();

}

/**

*

* Returns the name of this RR.

*

* @return The name of this RR.

public String getRRName() {

return m_name;

}

/**

*

* Returns the type of this RR.

*

* @return The type of this RR.

public int getRRType() {

return m_type;

}

/**

*

* Returns the class of this RR.

*

* @return The class of this RR.

public int getRRClass() {

return m_class;

}

/**

*

* Returns the TTL of this RR.

*

* @return the TTL of this RR

public long getRRTTL() {

return m_TTL;

}

/**

*

* Returns true if still valid i.e. TTL has not expired.

*

* @return True if valid, false if not.

public boolean isValid() {

return m_TTL * 1000 > System.currentTimeMillis() - m_created;

}

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