how to retrieve resource records and other stuff

[Periya.Data <per...@gm...>]

Hi,
     I have a DNS packet and I want to retrieve the entries in the query
section, answer section, name server resource records and additional records
sections. I see several approaches in the DNS Message library. I have not
yet attempted to run this code. Currently building the templates carefully.


Here is what I am doing and would like to know if there are better/elegant
approaches:

// dns_msg.getQuestion() returns the first record in the Q section.

        Record[] dns_query_record_array =
dns_msg.getSectionArray(Section.QUESTION);

        // dns_query_record_array.length must be equal to qdcount
        if (dns_query_record_array.length == 0) {
            // do something.
        } else {
            // do something...maybe print to verify
            int i = 0;
            while(i < dns_query_record_array.length) {
                //
                Record dns_query_rec = dns_query_record_array[i];
                System.out.println("Resource Record: " +
dns_query_rec.rdataToString());

                if (dns_query_rec != null){
                    Name qname = dns_query_rec.getName();
                    String qname_s = qname.toString();
                    int qtype = dns_query_rec.getType();
                    int qclass = dns_query_rec.getDClass();
                }
                i++;
            }

        }

       // Will the above get me all the entries in the question section? Or
should I do something like below..?????

        /*
      Record queryRecord = dns_msg.getQuestion();
        for (int q=0; q < qdcount; q++){
            if (queryRecord != null){
                qname = queryRecord.getName();
                qname_s = qname.toString();
                qtype = queryRecord.getType();
                qclass = queryRecord.getDClass();
            } else {
                qname_s = "none";
            }
        }
    */

        // DNS Answers
        // Note: there will be ANCOUNT number of resource records. You have
to loop to
        // get all the entries of the answer section.

        char rdlength;
        char rdata;

        Record[] dns_answer_record_array =
dns_msg.getSectionArray(Section.ANSWER);
        if (dns_answer_record_array.length == 0) {
            // do something.
        } else {
            // do something...maybe print to verify
            int i = 0;
            while(i < dns_answer_record_array.length) {
                Record dns_answer_rec = dns_answer_record_array[i];
                System.out.println("Resource Record: " +
dns_answer_rec.rdataToString());

                int type = dns_answer_rec.getType();
                Name name = dns_answer_rec.getName();
                int rdata_class = dns_answer_rec.getDClass();
                long ttl = dns_answer_rec.getTTL();

                i++;
            }

        }


        // Name server resource records
        // Note: There will be NSCOUNT number of name server rr in the
authority
        // records section.

        Record[] dns_nameserver_rr_array =
dns_msg.getSectionArray(Section.AUTHORITY);
        if (dns_nameserver_rr_array.length == 0) {
            // do something.
        } else {
            // do something...maybe print to verify
            int i = 0;
            while(i < dns_nameserver_rr_array.length) {
                Record dns_nameserver_rr = dns_nameserver_rr_array[i];
                System.out.println("Authority Record: " +
dns_nameserver_rr.rdataToString());
                i++;
            }

        }


        // Additional records section
        // Note: There will be ARCOUNT number of resource records in the
additional
        // records section.

        Record[] dns_additional_record_array =
dns_msg.getSectionArray(Section.ADDITIONAL);
        if (dns_additional_record_array.length == 0) {
            // do something.
        } else {
            // do something...maybe print to verify
            int i = 0;
            while(i < dns_additional_record_array.length) {
                Record dns_additional_rec = dns_additional_record_array[i];
                System.out.println("Additional Record: " +
dns_additional_rec.rdataToString());
                i++;
            }

        }



I have seen the RRSet and it has a nice iterator also. But, I think, a
simple record array is enough for me.
If there is a nice example that shows how to parse a DNS packet completely,
it would be useful.

Suggestions on improvements are greatly appreciated.


Thanks,
PD