Add ipadm: Go-Tool zur Verwaltung statischer DHCP/DNS-Hosts

tools/ipadm/interactive.go

@@ -0,0 +1,92 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+)
+
+var stdinReader = bufio.NewReader(os.Stdin)
+
+// prompt shows label with a "[current]" hint, reads one line, and returns
+// current unchanged if the user just presses enter.
+func prompt(label, current string) string {
+	if current != "" {
+		fmt.Printf("%s [%s]: ", label, current)
+	} else {
+		fmt.Printf("%s: ", label)
+	}
+	line, _ := stdinReader.ReadString('\n')
+	line = strings.TrimSpace(line)
+	if line == "" {
+		return current
+	}
+	return line
+}
+
+// interactiveEdit implements the bare `ipadm <hostname>` form: add the host
+// if it doesn't exist yet, otherwise edit it in place. Returns the updated
+// host list, or an error if validation fails.
+func interactiveEdit(hosts []Host, name string, cfg netConfig) ([]Host, error) {
+	if err := validateHostname(name); err != nil {
+		return nil, err
+	}
+	idx := findHost(hosts, name)
+
+	var cur Host
+	if idx >= 0 {
+		cur = hosts[idx]
+		fmt.Printf("Bearbeite bestehenden Host %q (Enter = Wert behalten)\n", name)
+	} else {
+		cur = Host{Name: name}
+		fmt.Printf("Neuer Host %q (Enter bei MAC/Comment = leer lassen)\n", name)
+	}
+
+	for {
+		ip := prompt("IP-Adresse", cur.IP)
+		if err := validateIP(ip, cfg.lanCIDR, cfg.poolStart, cfg.poolEnd); err != nil {
+			fmt.Fprintln(os.Stderr, "Fehler:", err)
+			continue
+		}
+		cur.IP = ip
+		break
+	}
+
+	for {
+		mac := prompt("MAC-Adresse (optional, '-' zum Löschen)", macOrDash(cur.MAC))
+		if mac == "-" {
+			mac = ""
+		}
+		norm, err := normalizeMAC(mac)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, "Fehler:", err)
+			continue
+		}
+		cur.MAC = norm
+		break
+	}
+
+	cur.Comment = prompt("Kommentar", cur.Comment)
+
+	if other := findByIP(hosts, cur.IP, idx); other >= 0 {
+		return nil, fmt.Errorf("IP %s ist bereits Host %q zugewiesen", cur.IP, hosts[other].Name)
+	}
+	if other := findByMAC(hosts, cur.MAC, idx); other >= 0 {
+		return nil, fmt.Errorf("MAC %s ist bereits Host %q zugewiesen", cur.MAC, hosts[other].Name)
+	}
+
+	if idx >= 0 {
+		hosts[idx] = cur
+	} else {
+		hosts = append(hosts, cur)
+	}
+	return hosts, nil
+}
+
+func macOrDash(mac string) string {
+	if mac == "" {
+		return ""
+	}
+	return mac
+}