refactor structure

scanner.go

@@ -0,0 +1,50 @@
+package main
+
+import (
+	"crypto/tls"
+	"io"
+	"log/slog"
+	"net"
+	"strconv"
+	"time"
+)
+
+var TLSDictionary = map[uint16]string{
+	0x0301: "1.0",
+	0x0302: "1.1",
+	0x0303: "1.2",
+	0x0304: "1.3",
+}
+
+func ScanTLS(ip net.IP, out io.Writer) {
+	hostPort := net.JoinHostPort(ip.String(), strconv.Itoa(port))
+	conn, err := net.DialTimeout("tcp", hostPort, time.Duration(timeout)*time.Second)
+	if err != nil {
+		slog.Debug("Cannot dial", "target", hostPort)
+		return
+	}
+	defer conn.Close()
+	err = conn.SetDeadline(time.Now().Add(time.Duration(timeout) * time.Second))
+	if err != nil {
+		slog.Error("Error setting deadline", "err", err)
+		return
+	}
+	c := tls.Client(conn, &tls.Config{
+		InsecureSkipVerify: true,
+		NextProtos:         []string{"h2", "http/1.1"},
+	})
+	err = c.Handshake()
+	if err != nil {
+		slog.Debug("TLS handshake failed", "target", hostPort)
+		return
+	}
+	state := c.ConnectionState()
+	alpn := state.NegotiatedProtocol
+	log := slog.Debug
+	if state.Version == 0x0304 && alpn == "h2" {
+		log = slog.Info
+		_, _ = io.WriteString(out, ip.String()+"\n")
+	}
+	log("Connected to target", "host", ip.String(), "tls", TLSDictionary[state.Version],
+		"alpn", alpn, "cert", state.PeerCertificates[0].Subject)
+}