diff options
Diffstat (limited to 'src/de/measite/minidns/DNSMessage.java')
| -rw-r--r-- | src/de/measite/minidns/DNSMessage.java | 507 |
1 files changed, 507 insertions, 0 deletions
diff --git a/src/de/measite/minidns/DNSMessage.java b/src/de/measite/minidns/DNSMessage.java new file mode 100644 index 00000000..14c8f04b --- /dev/null +++ b/src/de/measite/minidns/DNSMessage.java @@ -0,0 +1,507 @@ +package de.measite.minidns; + +import java.io.ByteArrayInputStream; +import java.io.ByteArrayOutputStream; +import java.io.DataInputStream; +import java.io.DataOutputStream; +import java.io.IOException; +import java.util.Arrays; + +/** + * A DNS message as defined by rfc1035. The message consists of a header and + * 4 sections: question, answer, nameserver and addition resource record + * section. + * A message can either be parsed ({@see #parse(byte[])}) or serialized + * ({@see #toArray()}). + */ +public class DNSMessage { + + /** + * Possible DNS reply codes. + */ + public static enum RESPONSE_CODE { + NO_ERROR(0), FORMAT_ERR(1), SERVER_FAIL(2), NX_DOMAIN(3), + NO_IMP(4), REFUSED(5), YXDOMAIN(6), YXRRSET(7), + NXRRSET(8), NOT_AUTH(9),NOT_ZONE(10); + + /** + * Reverse lookup table for response codes. + */ + private final static RESPONSE_CODE INVERSE_LUT[] = new RESPONSE_CODE[]{ + NO_ERROR, FORMAT_ERR, SERVER_FAIL, NX_DOMAIN, NO_IMP, + REFUSED, YXDOMAIN, YXRRSET, NXRRSET, NOT_AUTH, NOT_ZONE, + null, null, null, null, null + }; + + /** + * The response code value. + */ + private final byte value; + + /** + * Create a new response code. + * @param value The response code value. + */ + private RESPONSE_CODE(int value) { + this.value = (byte)value; + } + + /** + * Retrieve the byte value of the response code. + * @return + */ + public byte getValue() { + return (byte) value; + } + + /** + * Retrieve the response code for a byte value. + * @param value The byte value. + * @return The symbolic response code or null. + * @throws IllegalArgumentException if the value is not in the range of + * 0..15. + */ + public static RESPONSE_CODE getResponseCode(int value) { + if (value < 0 || value > 15) { + throw new IllegalArgumentException(); + } + return INVERSE_LUT[value]; + } + + }; + + /** + * Symbolic DNS Opcode values. + */ + public static enum OPCODE { + QUERY(0), + INVERSE_QUERY(1), + STATUS(2), + NOTIFY(4), + UPDATE(5); + + /** + * Lookup table for for obcode reolution. + */ + private final static OPCODE INVERSE_LUT[] = new OPCODE[]{ + QUERY, INVERSE_QUERY, STATUS, null, NOTIFY, UPDATE, null, + null, null, null, null, null, null, null, null + }; + + /** + * The value of this opcode. + */ + private final byte value; + + /** + * Create a new opcode for a given byte value. + * @param value The byte value of the opcode. + */ + private OPCODE(int value) { + this.value = (byte)value; + } + + /** + * Retrieve the byte value of this opcode. + * @return The byte value of this opcode. + */ + public byte getValue() { + return value; + } + + /** + * Retrieve the symbolic name of an opcode byte. + * @param value The byte value of the opcode. + * @return The symbolic opcode or null. + * @throws IllegalArgumentException If the byte value is not in the + * range 0..15. + */ + public static OPCODE getOpcode(int value) { + if (value < 0 || value > 15) { + throw new IllegalArgumentException(); + } + return INVERSE_LUT[value]; + } + + }; + + /** + * The DNS message id. + */ + protected int id; + + /** + * The DNS message opcode. + */ + protected OPCODE opcode; + + /** + * The response code of this dns message. + */ + protected RESPONSE_CODE responseCode; + + /** + * True if this is a query. + */ + protected boolean query; + + /** + * True if this is a authorative response. + */ + protected boolean authoritativeAnswer; + + /** + * True on truncate, tcp should be used. + */ + protected boolean truncated; + + /** + * True if the server should recurse. + */ + protected boolean recursionDesired; + + /** + * True if recursion is possible. + */ + protected boolean recursionAvailable; + + /** + * True if the server regarded the response as authentic. + */ + protected boolean authenticData; + + /** + * True if the server should not check the replies. + */ + protected boolean checkDisabled; + + /** + * The question section content. + */ + protected Question questions[]; + + /** + * The answers section content. + */ + protected Record answers[]; + + /** + * The nameserver records. + */ + protected Record nameserverRecords[]; + + /** + * Additional resousrce records. + */ + protected Record additionalResourceRecords[]; + + /** + * Retrieve the current DNS message id. + * @return The current DNS message id. + */ + public int getId() { + return id; + } + + /** + * Set the current DNS message id. + * @param id The new DNS message id. + */ + public void setId(int id) { + this.id = id & 0xffff; + } + + /** + * Retrieve the query type (true or false; + * @return True if this DNS message is a query. + */ + public boolean isQuery() { + return query; + } + + /** + * Set the query status of this message. + * @param query The new query status. + */ + public void setQuery(boolean query) { + this.query = query; + } + + /** + * True if the DNS message is an authoritative answer. + * @return True if this an authoritative DNS message. + */ + public boolean isAuthoritativeAnswer() { + return authoritativeAnswer; + } + + /** + * Set the authoritative answer flag. + * @param authoritativeAnswer Tge new authoritative answer value. + */ + public void setAuthoritativeAnswer(boolean authoritativeAnswer) { + this.authoritativeAnswer = authoritativeAnswer; + } + + /** + * Retrieve the truncation status of this message. True means that the + * client should try a tcp lookup. + * @return True if this message was truncated. + */ + public boolean isTruncated() { + return truncated; + } + + /** + * Set the truncation bit on this DNS message. + * @param truncated The new truncated bit status. + */ + public void setTruncated(boolean truncated) { + this.truncated = truncated; + } + + /** + * Check if this message preferes recursion. + * @return True if recursion is desired. + */ + public boolean isRecursionDesired() { + return recursionDesired; + } + + /** + * Set the recursion desired flag on this message. + * @param recursionDesired The new recusrion setting. + */ + public void setRecursionDesired(boolean recursionDesired) { + this.recursionDesired = recursionDesired; + } + + /** + * Retrieve the recursion available flag of this DNS message. + * @return The recursion available flag of this message. + */ + public boolean isRecursionAvailable() { + return recursionAvailable; + } + + /** + * Set the recursion available flog from this DNS message. + * @param recursionAvailable The new recursion available status. + */ + public void setRecursionAvailable(boolean recursionAvailable) { + this.recursionAvailable = recursionAvailable; + } + + /** + * Retrieve the authentic data flag of this message. + * @return The authentic data flag. + */ + public boolean isAuthenticData() { + return authenticData; + } + + /** + * Set the authentic data flag on this DNS message. + * @param authenticData The new authentic data flag value. + */ + public void setAuthenticData(boolean authenticData) { + this.authenticData = authenticData; + } + + /** + * Check if checks are disabled. + * @return The status of the CheckDisabled flag. + */ + public boolean isCheckDisabled() { + return checkDisabled; + } + + /** + * Change the check status of this packet. + * @param checkDisabled + */ + public void setCheckDisabled(boolean checkDisabled) { + this.checkDisabled = checkDisabled; + } + + /** + * Generate a binary dns packet out of this message. + * @return byte[] the binary representation. + * @throws IOException Should never happen. + */ + public byte[] toArray() throws IOException { + ByteArrayOutputStream baos = new ByteArrayOutputStream(512); + DataOutputStream dos = new DataOutputStream(baos); + int header = 0; + if (query) { + header += 1 << 15; + } + if (opcode != null) { + header += opcode.getValue() << 11; + } + if (authoritativeAnswer) { + header += 1 << 10; + } + if (truncated) { + header += 1 << 9; + } + if (recursionDesired) { + header += 1 << 8; + } + if (recursionAvailable) { + header += 1 << 7; + } + if (authenticData) { + header += 1 << 5; + } + if (checkDisabled) { + header += 1 << 4; + } + if (responseCode != null) { + header += responseCode.getValue(); + } + dos.writeShort((short)id); + dos.writeShort((short)header); + if (questions == null) { + dos.writeShort(0); + } else { + dos.writeShort((short)questions.length); + } + if (answers == null) { + dos.writeShort(0); + } else { + dos.writeShort((short)answers.length); + } + if (nameserverRecords == null) { + dos.writeShort(0); + } else { + dos.writeShort((short)nameserverRecords.length); + } + if (additionalResourceRecords == null) { + dos.writeShort(0); + } else { + dos.writeShort((short)additionalResourceRecords.length); + } + for (Question question: questions) { + dos.write(question.toByteArray()); + } + dos.flush(); + return baos.toByteArray(); + } + + /** + * Build a DNS Message based on a binary DNS message. + * @param data The DNS message data. + * @return Parsed DNSMessage message. + * @throws IOException On read errors. + */ + public static DNSMessage parse(byte data[]) throws IOException { + ByteArrayInputStream bis = new ByteArrayInputStream(data); + DataInputStream dis = new DataInputStream(bis); + DNSMessage message = new DNSMessage(); + message.id = dis.readUnsignedShort(); + int header = dis.readUnsignedShort(); + message.query = ((header >> 15) & 1) == 0; + message.opcode = OPCODE.getOpcode((header >> 11) & 0xf); + message.authoritativeAnswer = ((header >> 10) & 1) == 1; + message.truncated = ((header >> 9) & 1) == 1; + message.recursionDesired = ((header >> 8) & 1) == 1; + message.recursionAvailable = ((header >> 7) & 1) == 1; + message.authenticData = ((header >> 5) & 1) == 1; + message.checkDisabled = ((header >> 4) & 1) == 1; + message.responseCode = RESPONSE_CODE.getResponseCode(header & 0xf); + int questionCount = dis.readUnsignedShort(); + int answerCount = dis.readUnsignedShort(); + int nameserverCount = dis.readUnsignedShort(); + int additionalResourceRecordCount = dis.readUnsignedShort(); + message.questions = new Question[questionCount]; + while (questionCount-- > 0) { + Question q = new Question(); + q.parse(dis, data); + message.questions[questionCount] = q; + } + message.answers = new Record[answerCount]; + while (answerCount-- > 0) { + Record rr = new Record(); + rr.parse(dis, data); + message.answers[answerCount] = rr; + } + message.nameserverRecords = new Record[nameserverCount]; + while (nameserverCount-- > 0) { + Record rr = new Record(); + rr.parse(dis, data); + message.nameserverRecords[nameserverCount] = rr; + } + message.additionalResourceRecords = + new Record[additionalResourceRecordCount]; + while (additionalResourceRecordCount-- > 0) { + Record rr = new Record(); + rr.parse(dis, data); + message.additionalResourceRecords[additionalResourceRecordCount] = + rr; + } + return message; + } + + /** + * Set the question part of this message. + * @param questions The questions. + */ + public void setQuestions(Question ... questions) { + this.questions = questions; + } + + /** + * Retrieve the opcode of this message. + * @return The opcode of this message. + */ + public OPCODE getOpcode() { + return opcode; + } + + /** + * Retrieve the response code of this message. + * @return The response code. + */ + public RESPONSE_CODE getResponseCode() { + return responseCode; + } + + /** + * Retrieve the question section of this message. + * @return The DNS question section. + */ + public Question[] getQuestions() { + return questions; + } + + /** + * Retrieve the answer records of this DNS message. + * @return The answer section of this DNS message. + */ + public Record[] getAnswers() { + return answers; + } + + /** + * Retrieve the nameserver records of this DNS message. + * @return The nameserver section of this DNS message. + */ + public Record[] getNameserverRecords() { + return nameserverRecords; + } + + /** + * Retrieve the additional resource records attached to this DNS message. + * @return The additional resource record section of this DNS message. + */ + public Record[] getAdditionalResourceRecords() { + return additionalResourceRecords; + } + + public String toString() { + return "-- DNSMessage " + id + " --\n" + + Arrays.toString(answers); + } + +} |