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// Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org)
package org.xbill.DNS;
import java.net.*;
import java.util.regex.*;
/**
* The Client Subnet EDNS Option, defined in
* http://tools.ietf.org/html/draft-vandergaast-edns-client-subnet-00
* ("Client subnet in DNS requests").
*
* The option is used to convey information about the IP address of the
* originating client, so that an authoritative server can make decisions
* based on this address, rather than the address of the intermediate
* caching name server.
*
* The option is transmitted as part of an OPTRecord in the additional section
* of a DNS message, as defined by RFC 2671 (EDNS0).
*
* An option code has not been assigned by IANA; the value 20730 (used here) is
* also used by several other implementations.
*
* The wire format of the option contains a 2-byte length field (1 for IPv4, 2
* for IPv6), a 1-byte source netmask, a 1-byte scope netmask, and an address
* truncated to the source netmask length (where the final octet is padded with
* bits set to 0)
*
*
* @see OPTRecord
*
* @author Brian Wellington
* @author Ming Zhou <mizhou@bnivideo.com>, Beaumaris Networks
*/
public class ClientSubnetOption extends EDNSOption {
private static final long serialVersionUID = -3868158449890266347L;
private int family;
private int sourceNetmask;
private int scopeNetmask;
private InetAddress address;
ClientSubnetOption() {
super(EDNSOption.Code.CLIENT_SUBNET);
}
private static int
checkMaskLength(String field, int family, int val) {
int max = Address.addressLength(family) * 8;
if (val < 0 || val > max)
throw new IllegalArgumentException("\"" + field + "\" " + val +
" must be in the range " +
"[0.." + max + "]");
return val;
}
/**
* Construct a Client Subnet option. Note that the number of significant bits in
* the address must not be greater than the supplied source netmask.
* XXX something about Java's mapped addresses
* @param sourceNetmask The length of the netmask pertaining to the query.
* In replies, it mirrors the same value as in the requests.
* @param scopeNetmask The length of the netmask pertaining to the reply.
* In requests, it MUST be set to 0. In responses, this may or may not match
* the source netmask.
* @param address The address of the client.
*/
public
ClientSubnetOption(int sourceNetmask, int scopeNetmask, InetAddress address) {
super(EDNSOption.Code.CLIENT_SUBNET);
this.family = Address.familyOf(address);
this.sourceNetmask = checkMaskLength("source netmask", this.family,
sourceNetmask);
this.scopeNetmask = checkMaskLength("scope netmask", this.family,
scopeNetmask);
this.address = Address.truncate(address, sourceNetmask);
if (!address.equals(this.address))
throw new IllegalArgumentException("source netmask is not " +
"valid for address");
}
/**
* Construct a Client Subnet option with scope netmask set to 0.
* @param sourceNetmask The length of the netmask pertaining to the query.
* In replies, it mirrors the same value as in the requests.
* @param address The address of the client.
* @see ClientSubnetOption
*/
public
ClientSubnetOption(int sourceNetmask, InetAddress address) {
this(sourceNetmask, 0, address);
}
/**
* Returns the family of the network address. This will be either IPv4 (1)
* or IPv6 (2).
*/
public int
getFamily() {
return family;
}
/** Returns the source netmask. */
public int
getSourceNetmask() {
return sourceNetmask;
}
/** Returns the scope netmask. */
public int
getScopeNetmask() {
return scopeNetmask;
}
/** Returns the IP address of the client. */
public InetAddress
getAddress() {
return address;
}
void
optionFromWire(DNSInput in) throws WireParseException {
family = in.readU16();
if (family != Address.IPv4 && family != Address.IPv6)
throw new WireParseException("unknown address family");
sourceNetmask = in.readU8();
if (sourceNetmask > Address.addressLength(family) * 8)
throw new WireParseException("invalid source netmask");
scopeNetmask = in.readU8();
if (scopeNetmask > Address.addressLength(family) * 8)
throw new WireParseException("invalid scope netmask");
// Read the truncated address
byte [] addr = in.readByteArray();
if (addr.length != (sourceNetmask + 7) / 8)
throw new WireParseException("invalid address");
// Convert it to a full length address.
byte [] fulladdr = new byte[Address.addressLength(family)];
System.arraycopy(addr, 0, fulladdr, 0, addr.length);
try {
address = InetAddress.getByAddress(fulladdr);
} catch (UnknownHostException e) {
throw new WireParseException("invalid address", e);
}
InetAddress tmp = Address.truncate(address, sourceNetmask);
if (!tmp.equals(address))
throw new WireParseException("invalid padding");
}
void
optionToWire(DNSOutput out) {
out.writeU16(family);
out.writeU8(sourceNetmask);
out.writeU8(scopeNetmask);
out.writeByteArray(address.getAddress(), 0, (sourceNetmask + 7) / 8);
}
String
optionToString() {
StringBuffer sb = new StringBuffer();
sb.append(address.getHostAddress());
sb.append("/");
sb.append(sourceNetmask);
sb.append(", scope netmask ");
sb.append(scopeNetmask);
return sb.toString();
}
}
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