DNS Message Parser and Serializer

Small DNS query/response helpers built on top of github.com/miekg/dns.

This module focuses on:

• constructing DNS query messages with safe defaults;
• validating DNS responses against a query;
• extracting valid answers and common record types.

It does not aim to implement a full DNS parser/serializer. Instead, it wraps github.com/miekg/dns and provides reusable utility functions and algorithms.

Example

import (
	"log"

	"github.com/bassosimone/dnscodec"
	"github.com/miekg/dns"
)

// Serialize a DNS query for DNS-over-UDP
query := dnscodec.NewQuery("www.example.com", dns.TypeA)
msgQuery, err := query.NewMsg()
if err != nil {
	log.Fatal(err)
}
rawQuery, err := msgQuery.Pack()
if err != nil {
	log.Fatal(err)
}
_ = rawQuery // send using your transport

// Parse a DNS response for the above query
msgResponse := new(dns.Msg)
rawResponse := []byte{} // replace with raw response bytes
if err := msgResponse.Unpack(rawResponse); err != nil {
	log.Fatal(err)
}
resp, err := dnscodec.ParseResponse(msgQuery, msgResponse)
if err != nil {
	log.Fatal(err)
}

// Get all the matching A records in the response
aRecs, err := resp.RecordsA()
if err != nil {
	log.Fatal(err)
}

// Same as above but for AAAA
aaaaRecs, err := resp.RecordsAAAA()
if err != nil {
	log.Fatal(err)
}

// Same as above but for CNAME
cnameRecs, err := resp.RecordsCNAME()
if err != nil {
	log.Fatal(err)
}

See example_test.go for transport-specific query settings.

API Sketch

• NewQuery constructs a query with safe defaults (random ID, EDNS UDP size).
• ParseResponse validates and extracts meaningful RRs.
• Response.RecordsA, Response.RecordsAAAA, Response.RecordsCNAME return the records.

Installation

go get github.com/bassosimone/dnscodec

Development

go test ./...

License

SPDX-License-Identifier: GPL-3.0-or-later