cli_test.go

@@ -98,6 +98,15 @@ func TestQUIC(t *testing.T) {
 	assert.Nil(t, err)
 }
 
+func TestReverse(t *testing.T) {
+	app := prepareCLI()
+	args := os.Args[0:1]
+	args = append(args, "-x")
+	args = append(args, "8.8.8.8")
+	err := app.Run(args)
+	assert.Nil(t, err)
+}
+
 func FuzzCli(f *testing.F) {
 	testcases := []string{"git.froth.zone", "", "!12345", "google.com.edu.org.fr"}
 	for _, tc := range testcases {

query.go

@@ -48,6 +48,17 @@ func doQuery(c *cli.Context) error {
 		return err
 	}
 	msg := new(dns.Msg)
+
+	if Options.Reverse {
+		if dns.TypeToString[Options.Answers.Request] == "A" {
+			Options.Answers.Request = dns.StringToType["PTR"]
+		}
+		Options.Answers.Name, err = util.ReverseDNS(Options.Answers.Name, Options.Answers.Request)
+		if err != nil {
+			return err
+		}
+	}
+
 	// if the domain is not canonical, make it canonical
 	if !strings.HasSuffix(Options.Answers.Name, ".") {
 		Options.Answers.Name = fmt.Sprintf("%s.", Options.Answers.Name)

util/helpers.go

@@ -11,7 +11,8 @@ import (
 )
 
 // Given an IP or phone number, return a canonical string to be queried
-func ReverseDNS(address string, query string) (string, error) {
+func ReverseDNS(address string, querInt uint16) (string, error) {
+	query := dns.TypeToString[querInt]
 	if query == "PTR" {
 		return dns.ReverseAddr(address)
 	} else if query == "NAPTR" {

util/helpers_test.go

@@ -5,17 +5,23 @@ package util
 import (
 	"testing"
 
+	"github.com/miekg/dns"
 	"github.com/stretchr/testify/assert"
 )
 
+var (
+	PTR   = dns.StringToType["PTR"]
+	NAPTR = dns.StringToType["NAPTR"]
+)
+
 func TestIPv4(t *testing.T) {
-	act, err := ReverseDNS("8.8.4.4", "PTR")
+	act, err := ReverseDNS("8.8.4.4", PTR)
 	assert.Nil(t, err)
 	assert.Equal(t, act, "4.4.8.8.in-addr.arpa.", "IPv4 reverse")
 }
 
 func TestIPv6(t *testing.T) {
-	act, err := ReverseDNS("2606:4700:4700::1111", "PTR")
+	act, err := ReverseDNS("2606:4700:4700::1111", PTR)
 	assert.Nil(t, err)
 	assert.Equal(t, act, "1.1.1.1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.7.4.0.0.7.4.6.0.6.2.ip6.arpa.", "IPv6 reverse")
 }
@@ -31,13 +37,13 @@ func TestNAPTR(t *testing.T) {
 		{"17705551212", "2.1.2.1.5.5.5.0.7.7.1.e164.arpa."},
 	}
 	for _, test := range tests {
-		act, err := ReverseDNS(test.in, "NAPTR")
+		act, err := ReverseDNS(test.in, NAPTR)
 		assert.Nil(t, err)
 		assert.Equal(t, test.want, act)
 	}
 }
 
 func TestInvalid(t *testing.T) {
-	_, err := ReverseDNS("AAAAA", "A")
+	_, err := ReverseDNS("AAAAA", 1)
 	assert.NotNil(t, err)
 }