intial import

nameserver.go

@@ -0,0 +1,70 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"net"
+	"os/exec"
+	"strings"
+)
+
+func createQuery(data userData, addr net.IP, deleteRecord bool) string {
+	var query strings.Builder
+
+	query.WriteString(fmt.Sprintf("key %s\n", data.tsigkey))
+	query.WriteString(fmt.Sprintf("server %s\n", data.nameserver))
+	query.WriteString(fmt.Sprintf("zone %s\n", data.zonename))
+	if deleteRecord {
+		query.WriteString(fmt.Sprintf("update delete %s. A\n", data.hostname))
+	}
+	query.WriteString(fmt.Sprintf("update add %s. A %s\n", data.hostname,
+								  addr.String()))
+	query.WriteString("show\n")
+	query.WriteString("send\n")
+
+	return query.String()
+}
+
+func queryNameserver(query string) error {
+	var (
+		stdout bytes.Buffer
+		stderr bytes.Buffer
+	)
+
+	cmd := exec.Command("knsupdate", "-v")
+	cmd.Stdin = strings.NewReader(query)
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+	err := cmd.Run()
+	fmt.Printf(stdout.String())
+	fmt.Printf(stderr.String())
+
+	return err
+}
+
+func updateNameserver(data userData, addr net.IP) (bool, error) {
+	updateRecord := true
+	deleteRecord := true
+
+	addrs, err := net.LookupIP(data.hostname)
+	if err != nil {
+		deleteRecord = false
+	} else {
+		for _, ip := range addrs {
+			if ip.Equal(addr) {
+				updateRecord = false
+				break
+			}
+		}
+	}
+	if !updateRecord {
+		return false, nil
+	} else {
+		query := createQuery(data, addr, deleteRecord)
+		err = queryNameserver(query)
+		if err != nil {
+			return true, err
+		}
+		return true, nil
+	}
+}