28
29 import java.util.Vector;
30 import javax.naming.*;
31
32
33 /**
34 * The ResourceRecords class represents the resource records in the
35 * four sections of a DNS message.
36 *
37 * The additional records section is currently ignored.
38 *
39 * @author Scott Seligman
40 */
41
42
43 class ResourceRecords {
44
45 // Four sections: question, answer, authority, additional.
46 // The question section is treated as being made up of (shortened)
47 // resource records, although this isn't technically how it's defined.
48 Vector question = new Vector();
49 Vector answer = new Vector();
50 Vector authority = new Vector();
51 Vector additional = new Vector();
52
53 /*
54 * True if these resource records are from a zone transfer. In
55 * that case only answer records are read (as per
56 * draft-ietf-dnsext-axfr-clarify-02.txt). Also, the rdata of
57 * those answer records is not decoded (for efficiency) except
58 * for SOA records.
59 */
60 boolean zoneXfer;
61
62 /*
63 * Returns a representation of the resource records in a DNS message.
64 * Does not modify or store a reference to the msg array.
65 */
66 ResourceRecords(byte[] msg, int msgLen, Header hdr, boolean zoneXfer)
67 throws NamingException {
68 if (zoneXfer) {
69 answer.ensureCapacity(8192); // an arbitrary "large" number
70 }
71 this.zoneXfer = zoneXfer;
72 add(msg, msgLen, hdr);
73 }
74
75 /*
76 * Returns the type field of the first answer record, or -1 if
77 * there are no answer records.
78 */
79 int getFirstAnsType() {
80 if (answer.size() == 0) {
81 return -1;
82 }
83 return ((ResourceRecord) answer.firstElement()).getType();
84 }
85
86 /*
87 * Returns the type field of the last answer record, or -1 if
88 * there are no answer records.
89 */
90 int getLastAnsType() {
91 if (answer.size() == 0) {
92 return -1;
93 }
94 return ((ResourceRecord) answer.lastElement()).getType();
95 }
96
97 /*
98 * Decodes the resource records in a DNS message and adds
99 * them to this object.
100 * Does not modify or store a reference to the msg array.
101 */
102 void add(byte[] msg, int msgLen, Header hdr) throws NamingException {
103
104 ResourceRecord rr;
105 int pos = Header.HEADER_SIZE; // current offset into msg
106
107 try {
108 for (int i = 0; i < hdr.numQuestions; i++) {
109 rr = new ResourceRecord(msg, msgLen, pos, true, false);
110 if (!zoneXfer) {
111 question.addElement(rr);
112 }
113 pos += rr.size();
114 }
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28
29 import java.util.Vector;
30 import javax.naming.*;
31
32
33 /**
34 * The ResourceRecords class represents the resource records in the
35 * four sections of a DNS message.
36 *
37 * The additional records section is currently ignored.
38 *
39 * @author Scott Seligman
40 */
41
42
43 class ResourceRecords {
44
45 // Four sections: question, answer, authority, additional.
46 // The question section is treated as being made up of (shortened)
47 // resource records, although this isn't technically how it's defined.
48 Vector<ResourceRecord> question = new Vector<>();
49 Vector<ResourceRecord> answer = new Vector<>();
50 Vector<ResourceRecord> authority = new Vector<>();
51 Vector<ResourceRecord> additional = new Vector<>();
52
53 /*
54 * True if these resource records are from a zone transfer. In
55 * that case only answer records are read (as per
56 * draft-ietf-dnsext-axfr-clarify-02.txt). Also, the rdata of
57 * those answer records is not decoded (for efficiency) except
58 * for SOA records.
59 */
60 boolean zoneXfer;
61
62 /*
63 * Returns a representation of the resource records in a DNS message.
64 * Does not modify or store a reference to the msg array.
65 */
66 ResourceRecords(byte[] msg, int msgLen, Header hdr, boolean zoneXfer)
67 throws NamingException {
68 if (zoneXfer) {
69 answer.ensureCapacity(8192); // an arbitrary "large" number
70 }
71 this.zoneXfer = zoneXfer;
72 add(msg, msgLen, hdr);
73 }
74
75 /*
76 * Returns the type field of the first answer record, or -1 if
77 * there are no answer records.
78 */
79 int getFirstAnsType() {
80 if (answer.size() == 0) {
81 return -1;
82 }
83 return answer.firstElement().getType();
84 }
85
86 /*
87 * Returns the type field of the last answer record, or -1 if
88 * there are no answer records.
89 */
90 int getLastAnsType() {
91 if (answer.size() == 0) {
92 return -1;
93 }
94 return answer.lastElement().getType();
95 }
96
97 /*
98 * Decodes the resource records in a DNS message and adds
99 * them to this object.
100 * Does not modify or store a reference to the msg array.
101 */
102 void add(byte[] msg, int msgLen, Header hdr) throws NamingException {
103
104 ResourceRecord rr;
105 int pos = Header.HEADER_SIZE; // current offset into msg
106
107 try {
108 for (int i = 0; i < hdr.numQuestions; i++) {
109 rr = new ResourceRecord(msg, msgLen, pos, true, false);
110 if (!zoneXfer) {
111 question.addElement(rr);
112 }
113 pos += rr.size();
114 }
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