From 3da5abab980359d6da4eab424ced3dc9b06f74c6 Mon Sep 17 00:00:00 2001 From: Ziver Koc Date: Thu, 11 Feb 2016 09:31:07 +0100 Subject: [PATCH] Updated comments from dns spec --- src/zutil/net/dns/DNSPacket.java | 208 ++++++++++++++++++++++--------- 1 file changed, 152 insertions(+), 56 deletions(-) diff --git a/src/zutil/net/dns/DNSPacket.java b/src/zutil/net/dns/DNSPacket.java index 333f7c9..85ffdfc 100755 --- a/src/zutil/net/dns/DNSPacket.java +++ b/src/zutil/net/dns/DNSPacket.java @@ -29,13 +29,12 @@ import zutil.parser.binary.BinaryStruct.*; /** * Created by Ziver on 2016-02-09. + * Reference: http://tools.ietf.org/html/rfc1035 */ public class DNSPacket implements BinaryStruct { public static final int OPCODE_QUERY = 0; public static final int OPCODE_IQUERY = 1; public static final int OPCODE_STATUS = 2; - public static final int OPCODE_NOTIFY = 4; - public static final int OPCODE_UPDATE = 5; public static final int RCODE_NO_ERROR = 0; public static final int RCODE_FORMAT_ERROR = 1; @@ -43,11 +42,6 @@ public class DNSPacket implements BinaryStruct { public static final int RCODE_NAME_ERROR = 3; public static final int RCODE_NOT_IMPLEMENTED = 4; public static final int RCODE_REFUSED = 5; - public static final int RCODE_YX_DOMAIN = 6; // A name exists where it should not - public static final int RCODE_YX_RR_SET = 7; // A resource record set exists where it should not - public static final int RCODE_NX_RR_SET = 8; // A resource record set should exist but does not - public static final int RCODE_NOT_AUTH = 9; // Server is not authoritative for the zone - public static final int RCODE_NOT_ZONE = 10; // The name is not in the zone specified in the message @BinaryField(index=0, length=16) @@ -57,95 +51,197 @@ public class DNSPacket implements BinaryStruct { //@BinaryField(index=10, length=16) //int flags; /** - * Query/Response Flag. - * Differentiates between queries and responses. - * Set to 0 when the query is generated; changed to 1 when that - * query is changed to a response by a replying server. + * A one bit field that specifies whether this message is a + * query (0), or a response (1). */ @BinaryField(index=10, length=1) - boolean qr; + boolean flagQueryResponse; /** - * Operation Code. - * Specifies the type of query in the message. This field is - * copied unchanged in the response + * A four bit field that specifies kind of query in this message. + * 
+     * 0    a standard query (QUERY)
+     * 1    an inverse query (IQUERY)
+     * 2    a server status request (STATUS)
+     *
*/ @BinaryField(index=11, length=4) - int opcode; + int flagOperationCode; /** - * Authoritative Answer Flag - * This bit is set to true in a response to indicate that the server - * that created the response is authoritative for the zone in - * which the domain name specified in the Question section is located + * This bit is valid in responses, + * and specifies that the responding name server is an + * authority for the domain name in question section. */ @BinaryField(index=12, length=1) - boolean aa; + boolean flagAuthoritativeAnswer; /** - * Truncation Flag. - * When set to true, indicates that the message was truncated - * due to its length + * specifies that this message was truncated + * due to length greater than that permitted on the + * transmission channel. */ @BinaryField(index=13, length=1) - boolean tc; + boolean flagTruncation; /** - * Recursion Desired. - * When set in a query, requests that the server receiving the - * query attempt to answer the query recursively, if the server - * supports recursive resolution. The value of this bit is not - * changed in the response. + * this bit may be set in a query and + * is copied into the response. If RD is set, it directs + * the name server to pursue the query recursively. + * Recursive query support is optional. */ @BinaryField(index=14, length=1) - boolean rd; + boolean flagRecursionDesired; /** - * Recursion Available. - * Set to true to indicate whether the server creating the response - * supports recursive queries. + * this be is set or cleared in a + * response, and denotes whether recursive query support is + * available in the name server. */ @BinaryField(index=15, length=1) - boolean ra; - @BinaryField(index=16, length=3) - int reserved; + boolean flagRecursionAvailable; /** - * Response Code. + * Reserved for future use. Must be zero in all queries + * and responses. + */ + @BinaryField(index=16, length=3) + private int z; + /** + * this field is set as part of responses. + * The values have the following interpretation: + * 
+     * 0    No error condition
+     * 1    Format error - The name server was
+     *      unable to interpret the query.
+     * 2    Server failure - The name server was
+     *      unable to process this query due to a
+     *      problem with the name server.
+     * 3    Name Error - Meaningful only for
+     *      responses from an authoritative name
+     *      server, this code signifies that the
+     *      domain name referenced in the query does
+     *      not exist.
+     * 4    Not Implemented - The name server does
+     *      not support the requested kind of query.
+     * 5    Refused - The name server refuses to
+     *      perform the specified operation for
+     *      policy reasons.
+     *
*/ @BinaryField(index=17, length=4) - int rCode; - + int flagResponseCode; //////////////// COUNTS /** * Question Count. - * Specifies the number of questions in the - * Question section of the message. + * Specifying the number of entries in the question section. */ @BinaryField(index=20, length=16) - int qdCount; + int countQuestion; /** * Answer Record Count. - * Specifies the number of resource records - * in the Answer section of the message. + * specifying the number of resource records in + * the answer section. */ @BinaryField(index=21, length=16) - int anCount; + int countAnswerRecord; /** * Name Server (Authority Record) Count. - * Specifies the number of resource records in the - * Authority section of the message. + * Specifying the number of name server resource records + * in the authority records section. */ @BinaryField(index=22, length=16) - int nsCount; + int countNameServer; /** * Additional Record Count. - * Specifies the number of resource records in the - * Additional section of the message. + * Specifying the number of resource records in the + * additional records section */ @BinaryField(index=23, length=16) - int arCount; + int countAdditionalRecord; - //////////////// REQUEST DATA - // char data[?] - // char flag[2] => QTYPE=0x00_01 host address query - // QCLASS=0x00_01 internet query + /* + Question section format + 1 1 1 1 1 1 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + | | + / QNAME / + / / + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + | QTYPE | + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + | QCLASS | + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + + where: + + QNAME a domain name represented as a sequence of labels, where + each label consists of a length octet followed by that + number of octets. The domain name terminates with the + zero length octet for the null label of the root. Note + that this field may be an odd number of octets; no + padding is used. + + QTYPE a two octet code which specifies the type of the query. + The values for this field include all codes valid for a + TYPE field, together with some more general codes which + can match more than one type of RR. + + QCLASS a two octet code that specifies the class of the query. + For example, the QCLASS field is IN for the Internet. + */ + + /* + Resource record format + + The answer, authority, and additional sections all share the same + format: a variable number of resource records, where the number of + records is specified in the corresponding count field in the header. + Each resource record has the following format: + 1 1 1 1 1 1 + 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + | | + / / + / NAME / + | | + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + | TYPE | + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + | CLASS | + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + | TTL | + | | + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + | RDLENGTH | + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--| + / RDATA / + / / + +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+ + + where: + + NAME a domain name to which this resource record pertains. + + TYPE two octets containing one of the RR type codes. This + field specifies the meaning of the data in the RDATA + field. + + CLASS two octets which specify the class of the data in the + RDATA field. + + TTL a 32 bit unsigned integer that specifies the time + interval (in seconds) that the resource record may be + cached before it should be discarded. Zero values are + interpreted to mean that the RR can only be used for the + transaction in progress, and should not be cached. + + RDLENGTH an unsigned 16 bit integer that specifies the length in + octets of the RDATA field. + + RDATA a variable length string of octets that describes the + resource. The format of this information varies + according to the TYPE and CLASS of the resource record. + For example, the if the TYPE is A and the CLASS is IN, + the RDATA field is a 4 octet ARPA Internet address. + */ }