feat: lookup wildcard domain with random sub

Author: sunggun-yu

internal/dnslookup/dnslookup.go

@@ -1,16 +1,36 @@
 package dnslookup
 
 import (
+	"math/rand"
 	"net"
 	"strings"
 
 	"github.com/sunggun-yu/dnsq/internal/models"
 )
 
+// randomHostname generates a random hostname
+func randomHostname() string {
+	const charset = "abcdefghijklmnopqrstuvwxyz0123456789"
+	length := 8
+	// TODO: need to check length of hostname and see if it is over 255 long including the subdomain
+	b := make([]byte, length)
+	for i := range b {
+		b[i] = charset[rand.Intn(len(charset))]
+	}
+	return string(b)
+}
+
 // GetDNSRecords returns DNS records for a given hostname
 func GetDNSRecords(hostname string) []models.DNSRecord {
 	var records []models.DNSRecord
 	currentHost := hostname
+	isWildcard := false
+
+	if strings.HasPrefix(hostname, "*.") {
+		randomSubdomain := randomHostname()
+		currentHost = randomSubdomain + hostname[1:]
+		isWildcard = true
+	}
 
 	// CNAME lookup
 	cname, err := net.LookupCNAME(currentHost)
@@ -24,6 +44,12 @@ func GetDNSRecords(hostname string) []models.DNSRecord {
 
 	// A and AAAA lookup
 	ips, err := net.LookupIP(currentHost)
+
+	// if it is a wildcard, set the original hostname to the records
+	if isWildcard {
+		currentHost = hostname
+	}
+
 	if err == nil {
 		for _, ip := range ips {
 			if ipv4 := ip.To4(); ipv4 != nil {