initial commit

utils/dns_utils.go

@@ -0,0 +1,31 @@
+// dns utils
+package utils
+
+import (
+	"github.com/miekg/dns"
+)
+
+// build the question section of a dns packet
+func QuestionMaker(domain string, qclass uint16, qtype uint16) *dns.Question {
+	return &dns.Question{Name: dns.Fqdn(domain), Qtype: qtype, Qclass: qclass}
+}
+
+// build a specific query message
+func QueryMaker(domain string, rd bool, qclass uint16, qtype uint16, edns bool) *dns.Msg {
+	msg := new(dns.Msg)
+	msg.Id = dns.Id()
+	msg.RecursionDesired = rd
+	msg.Question = make([]dns.Question, 1)
+	msg.Question[0] = *QuestionMaker(domain, qclass, qtype)
+	if edns {
+		msg = msg.SetEdns0(4096, false)
+	}
+	return msg
+}
+
+// query and receive the response
+func DNSQuery(addr string, domain string, rd bool, qclass uint16, qtype uint16, edns bool) (*dns.Msg, error) {
+	msg := QueryMaker(domain, rd, qclass, qtype, edns)
+	res, err := dns.Exchange(msg, addr)
+	return res, err
+}