not-dig

A Bad Clone of the dig Tool

This project implements a stub resolver client that is able to query either a recursive or authoritative DNS server.

What is supported?

1. Specifying the server to query
2. Specifying the port to send the query
3. Any domain name and any RRTYPE can be encoded into a query
4. The following RRTYPEs can be decoded: A, NS, CNAME, SOA, PTR, HINFO, MX, TXT, AFSDB, AAAA, SRV, NAPTR, CERT, DNAME
5. UDP retry

What isn't supported?

1. DNSSEC in no way shape or form
2. Many RRTYPEs
3. Any options on which flags to set, or how to display the data (dig has things like +short, +trace, +norecurse, etc.)
4. No TCP support
5. Does not decode DNS options / special additionals

Build

Run make to run the tests and compile not-dig. Either

$ make

or

$ make all

To run only the tests run $ make test

To remove the executables run $ make clean

Usage

Call the executable and optionally give it a port / server address, and provide the domain name and qtype.

$ not-dig -@198.51.44.1 frazao.ca. a
; <<>> Not DiG 0.0.1 <<>> frazao.ca. A
;; global options: +cmd
;; Got answer:
;; ->> HEADER <<- opcode: QUERY status: NOERROR id: 61417
;; flags: aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
frazao.ca.              IN              A

;; ANSWER SECTION:
frazao.ca.              30              IN              A               54.197.199.246

;; Query time: 11 msec
;; SERVER: 198.51.44.1#53
;; WHEN: Tue May 28 13:49:23 DST 2019
;; MSG SIZE  rcvd: 43

FAQs

How professional is this code base?

I decided to do this after reading through K&R C and doing some excercises. The quality of the C code is guaranteed to be poor.

Is this memory safe?

Almost certainly not, the number of segfaults and memory issues that I ran while developing this was staggering. I would be very surprised if there are not any remaining memory issues.

Why?

I wanted to practice my C programming and I wanted to learn more about socket networking.

TODO

1. Implement better command line options handling DONE
2. Implement additional RRTYPEs
3. Implement a recursive resolver server
4. Implement a recursive resolver cache
5. Implement an authoritative DNS server
6. Expand scope of test suite
7. Implement queries over TCP
8. Implement dns trace funtionality
9. Implement ability to specify DNS server by name instead of by IP
10. Implement better input validation (e.g., autocorrect domains without terminal dot)