1 // Copyright (c) 1999-2004 Brian Wellington (bwelling@xbill.org)
2
3 package org.xbill.DNS;
4
5 import java.net.*;
6 import java.util.regex.*;
7
8 /**
9 * The Client Subnet EDNS Option, defined in
10 * http://tools.ietf.org/html/draft-vandergaast-edns-client-subnet-00
11 * ("Client subnet in DNS requests").
12 *
13 * The option is used to convey information about the IP address of the
14 * originating client, so that an authoritative server can make decisions
15 * based on this address, rather than the address of the intermediate
16 * caching name server.
17 *
18 * The option is transmitted as part of an OPTRecord in the additional section
19 * of a DNS message, as defined by RFC 2671 (EDNS0).
20 *
21 * An option code has not been assigned by IANA; the value 20730 (used here) is
22 * also used by several other implementations.
23 *
24 * The wire format of the option contains a 2-byte length field (1 for IPv4, 2
25 * for IPv6), a 1-byte source netmask, a 1-byte scope netmask, and an address
26 * truncated to the source netmask length (where the final octet is padded with
27 * bits set to 0)
28 *
29 *
30 * @see OPTRecord
31 *
32 * @author Brian Wellington
33 * @author Ming Zhou <mizhou@bnivideo.com>, Beaumaris Networks
34 */
35 public class ClientSubnetOption extends EDNSOption {
36
37 private static final long serialVersionUID = -3868158449890266347L;
38
39 private int family;
40 private int sourceNetmask;
41 private int scopeNetmask;
42 private InetAddress address;
43
ClientSubnetOption()44 ClientSubnetOption() {
45 super(EDNSOption.Code.CLIENT_SUBNET);
46 }
47
48 private static int
checkMaskLength(String field, int family, int val)49 checkMaskLength(String field, int family, int val) {
50 int max = Address.addressLength(family) * 8;
51 if (val < 0 || val > max)
52 throw new IllegalArgumentException("\"" + field + "\" " + val +
53 " must be in the range " +
54 "[0.." + max + "]");
55 return val;
56 }
57
58 /**
59 * Construct a Client Subnet option. Note that the number of significant bits in
60 * the address must not be greater than the supplied source netmask.
61 * XXX something about Java's mapped addresses
62 * @param sourceNetmask The length of the netmask pertaining to the query.
63 * In replies, it mirrors the same value as in the requests.
64 * @param scopeNetmask The length of the netmask pertaining to the reply.
65 * In requests, it MUST be set to 0. In responses, this may or may not match
66 * the source netmask.
67 * @param address The address of the client.
68 */
69 public
ClientSubnetOption(int sourceNetmask, int scopeNetmask, InetAddress address)70 ClientSubnetOption(int sourceNetmask, int scopeNetmask, InetAddress address) {
71 super(EDNSOption.Code.CLIENT_SUBNET);
72
73 this.family = Address.familyOf(address);
74 this.sourceNetmask = checkMaskLength("source netmask", this.family,
75 sourceNetmask);
76 this.scopeNetmask = checkMaskLength("scope netmask", this.family,
77 scopeNetmask);
78 this.address = Address.truncate(address, sourceNetmask);
79
80 if (!address.equals(this.address))
81 throw new IllegalArgumentException("source netmask is not " +
82 "valid for address");
83 }
84
85 /**
86 * Construct a Client Subnet option with scope netmask set to 0.
87 * @param sourceNetmask The length of the netmask pertaining to the query.
88 * In replies, it mirrors the same value as in the requests.
89 * @param address The address of the client.
90 * @see ClientSubnetOption
91 */
92 public
ClientSubnetOption(int sourceNetmask, InetAddress address)93 ClientSubnetOption(int sourceNetmask, InetAddress address) {
94 this(sourceNetmask, 0, address);
95 }
96
97 /**
98 * Returns the family of the network address. This will be either IPv4 (1)
99 * or IPv6 (2).
100 */
101 public int
getFamily()102 getFamily() {
103 return family;
104 }
105
106 /** Returns the source netmask. */
107 public int
getSourceNetmask()108 getSourceNetmask() {
109 return sourceNetmask;
110 }
111
112 /** Returns the scope netmask. */
113 public int
getScopeNetmask()114 getScopeNetmask() {
115 return scopeNetmask;
116 }
117
118 /** Returns the IP address of the client. */
119 public InetAddress
getAddress()120 getAddress() {
121 return address;
122 }
123
124 void
optionFromWire(DNSInput in)125 optionFromWire(DNSInput in) throws WireParseException {
126 family = in.readU16();
127 if (family != Address.IPv4 && family != Address.IPv6)
128 throw new WireParseException("unknown address family");
129 sourceNetmask = in.readU8();
130 if (sourceNetmask > Address.addressLength(family) * 8)
131 throw new WireParseException("invalid source netmask");
132 scopeNetmask = in.readU8();
133 if (scopeNetmask > Address.addressLength(family) * 8)
134 throw new WireParseException("invalid scope netmask");
135
136 // Read the truncated address
137 byte [] addr = in.readByteArray();
138 if (addr.length != (sourceNetmask + 7) / 8)
139 throw new WireParseException("invalid address");
140
141 // Convert it to a full length address.
142 byte [] fulladdr = new byte[Address.addressLength(family)];
143 System.arraycopy(addr, 0, fulladdr, 0, addr.length);
144
145 try {
146 address = InetAddress.getByAddress(fulladdr);
147 } catch (UnknownHostException e) {
148 throw new WireParseException("invalid address", e);
149 }
150
151 InetAddress tmp = Address.truncate(address, sourceNetmask);
152 if (!tmp.equals(address))
153 throw new WireParseException("invalid padding");
154 }
155
156 void
optionToWire(DNSOutput out)157 optionToWire(DNSOutput out) {
158 out.writeU16(family);
159 out.writeU8(sourceNetmask);
160 out.writeU8(scopeNetmask);
161 out.writeByteArray(address.getAddress(), 0, (sourceNetmask + 7) / 8);
162 }
163
164 String
optionToString()165 optionToString() {
166 StringBuffer sb = new StringBuffer();
167 sb.append(address.getHostAddress());
168 sb.append("/");
169 sb.append(sourceNetmask);
170 sb.append(", scope netmask ");
171 sb.append(scopeNetmask);
172 return sb.toString();
173 }
174
175 }
176