new: added dns CHAOS banner grabber to syn.scan

modules/syn_scan/banner_grabbing.go

@@ -29,6 +29,8 @@ func (mod *SynScanner) bannerGrabber(arg async.Job) {
 	fn := tcpGrabber
 	if port == 80 || port == 443 || sport[0] == '8' {
 		fn = httpGrabber
+	} else if port == 53 || port == 5353 {
+		fn = dnsGrabber
 	}
 
 	mod.Debug("grabbing banner for %s:%d", ip, port)

modules/syn_scan/dns_grabber.go

@@ -0,0 +1,34 @@
+package syn_scan
+
+import (
+	"fmt"
+	"regexp"
+
+	"github.com/miekg/dns"
+)
+
+var chaosParser = regexp.MustCompile(`.*"([^"]+)".*`)
+
+func grabChaos(addr string, q string) string {
+	c := new(dns.Client)
+	m := new(dns.Msg)
+	m.Question = make([]dns.Question, 1)
+	m.Question[0] = dns.Question{q, dns.TypeTXT, dns.ClassCHAOS}
+	if in, _, _ := c.Exchange(m, addr); in != nil && len(in.Answer) > 0 {
+		s := in.Answer[0].String()
+		if match := chaosParser.FindStringSubmatch(s); len(match) > 0 {
+			return match[1]
+		}
+	}
+	return ""
+}
+
+func dnsGrabber(mod *SynScanner, ip string, port int) string {
+	addr := fmt.Sprintf("%s:%d", ip, port)
+	if v := grabChaos(addr, "version.bind."); v != "" {
+		return v
+	} else if v := grabChaos(addr, "hostname.bind."); v != "" {
+		return v
+	}
+	return ""
+}