jbergner
1ffea42f26
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348 lines
12 KiB
Go
348 lines
12 KiB
Go
// A Go web‑server that converts IPv4 addresses into IPv6 addresses
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// inside a user‑defined /96 ULA prefix and outputs Windows 11‑ready fields.
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//
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// Features
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// --------
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// 1. Single conversion page (http://localhost:8080/) – converts one IPv4.
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// 2. Range conversion page (http://localhost:8080/range) – converts a span of IPv4s into a table.
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//
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// Environment variables (all optional):
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//
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// ULA_PREFIX – /96 prefix to embed into, default "fd09:cafe:affe:4010::"
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// DNS1 – preferred DNS IPv6 address (default: <prefix>::53)
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// DNS2 – alternate DNS IPv6 address (default: <prefix>::54)
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// FORM_DEFAULT_IP – placeholder for the single‑convert page, default 172.16.0.0
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// RANGE_LIMIT – max number of addresses allowed in /range (default 1024)
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//
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// Build & run:
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//
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// go run main.go
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package main
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import (
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"fmt"
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"html/template"
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"log"
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"net"
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"net/http"
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"os"
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"strconv"
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"strings"
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)
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// ---------------------------------------------------------------------------
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// Configuration constants & globals
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// ---------------------------------------------------------------------------
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const (
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listenAddr = ":8080"
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defaultPrefix = "fd09:cafe:affe:4010::" // fallback /96
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defaultIP = "172.16.0.0"
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defaultLimit = 1024 // max. rows for range conversion
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)
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var (
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ulaPrefix string
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dns1, dns2 string
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pageIP string
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rangeLimit int
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singleTemplate *template.Template
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rangeTemplate *template.Template
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dhcpServer string
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dhcpScope string
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)
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// ---------------------------------------------------------------------------
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// Template data structures
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// ---------------------------------------------------------------------------
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type singleData struct {
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IPv4, IPv6, Gateway, DNS1, DNS2, Error string
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HaveResult bool
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}
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type addrPair struct{ Name, IPv4, IPv6 string }
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type rangeData struct {
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Start, End string
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DhcpServer, DhcpScope string
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Rows []addrPair
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Error string
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HaveResult bool
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}
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// ---------------------------------------------------------------------------
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// main – HTTP routing
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// ---------------------------------------------------------------------------
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func main() {
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initConfigAndTemplates()
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http.HandleFunc("/", handleSingle)
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http.HandleFunc("/convert", handleSingleConvert)
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http.HandleFunc("/range", handleRange)
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log.Printf("Server läuft auf http://localhost%s (Präfix %s, DNS1 %s, DNS2 %s, Limit %d)", listenAddr, ulaPrefix, dns1, dns2, rangeLimit)
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log.Fatal(http.ListenAndServe(listenAddr, nil))
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}
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// ---------------------------------------------------------------------------
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// Handlers – single conversion
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// ---------------------------------------------------------------------------
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func handleSingle(w http.ResponseWriter, r *http.Request) {
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renderSingle(w, singleData{})
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}
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func handleSingleConvert(w http.ResponseWriter, r *http.Request) {
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if err := r.ParseForm(); err != nil {
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renderSingle(w, singleData{Error: "Ungültiges Formular"})
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return
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}
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ipv4Str := r.FormValue("ipv4")
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ipv6, err := embedIPv4(ipv4Str)
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d := singleData{IPv4: ipv4Str}
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if err != nil {
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d.Error = err.Error()
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} else {
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d.HaveResult = true
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d.IPv6 = ipv6
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d.Gateway = ulaPrefix + "1"
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d.DNS1, d.DNS2 = dns1, dns2
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}
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renderSingle(w, d)
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}
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// ---------------------------------------------------------------------------
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// Handlers – range conversion
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// ---------------------------------------------------------------------------
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func handleRange(w http.ResponseWriter, r *http.Request) {
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switch r.Method {
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case http.MethodGet:
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renderRange(w, rangeData{})
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return
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case http.MethodPost:
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if err := r.ParseForm(); err != nil {
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renderRange(w, rangeData{Error: "Ungültiges Formular"})
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return
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}
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startStr := r.FormValue("start")
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endStr := r.FormValue("end")
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rows, err := convertRange(startStr, endStr)
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d := rangeData{Start: startStr, End: endStr, DhcpServer: dhcpServer, DhcpScope: dhcpScope}
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if err != nil {
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d.Error = err.Error()
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} else {
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d.HaveResult = true
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for a, b := range rows {
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fmt.Println(a, b)
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octets := strings.Split(b.IPv4, ".")
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if len(octets) != 4 {
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fmt.Println("Ungültige IP-Adresse!")
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return
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}
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O3 := ""
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O4 := ""
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if len(octets[2]) < 2 {
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O3 = "0" + octets[2]
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} else {
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O3 = octets[2]
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}
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if len(octets[3]) < 2 {
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O4 = "0" + octets[3]
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} else {
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O4 = octets[3]
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}
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N := "PC" + O3 + O4
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d.Rows = append(d.Rows, addrPair{IPv4: b.IPv4, IPv6: b.IPv6, Name: N})
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}
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}
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renderRange(w, d)
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default:
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http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
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}
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}
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// convertRange returns slice of addrPairs for every IPv4 in [start,end].
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func convertRange(start, end string) ([]addrPair, error) {
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sip := net.ParseIP(start).To4()
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eip := net.ParseIP(end).To4()
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if sip == nil || eip == nil {
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return nil, fmt.Errorf("start oder ende ist keine gültige ipv4-adresse")
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}
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su := ipToUint32(sip)
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eu := ipToUint32(eip)
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if su > eu {
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return nil, fmt.Errorf("start darf nicht größer als ende sein")
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}
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count := int(eu - su + 1)
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if count > rangeLimit {
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return nil, fmt.Errorf("bereich zu groß (%d > %d)", count, rangeLimit)
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}
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rows := make([]addrPair, 0, count)
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for cur := su; cur <= eu; cur++ {
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ipv4 := uint32ToIP(cur).String()
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ipv6, _ := embedIPv4(ipv4) // embedIPv4 kann hier nicht mehr fehlschlagen
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rows = append(rows, addrPair{IPv4: ipv4, IPv6: ipv6})
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}
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return rows, nil
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}
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// ---------------------------------------------------------------------------
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// Helper functions
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// ---------------------------------------------------------------------------
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func embedIPv4(ipv4 string) (string, error) {
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ip := net.ParseIP(ipv4).To4()
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if ip == nil {
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return "", fmt.Errorf("%s ist keine gültige IPv4-Adresse", ipv4)
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}
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hi := uint16(ip[0])<<8 | uint16(ip[1])
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lo := uint16(ip[2])<<8 | uint16(ip[3])
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return fmt.Sprintf("%s%x:%x", ulaPrefix, hi, lo), nil
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}
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func ipToUint32(ip net.IP) uint32 {
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return uint32(ip[0])<<24 | uint32(ip[1])<<16 | uint32(ip[2])<<8 | uint32(ip[3])
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}
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func uint32ToIP(u uint32) net.IP {
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return net.IPv4(byte(u>>24), byte(u>>16), byte(u>>8), byte(u))
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}
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// ---------------------------------------------------------------------------
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// Config & templates
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// ---------------------------------------------------------------------------
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func initConfigAndTemplates() {
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// ULA prefix ---------------------------------
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ulaPrefix = os.Getenv("ULA_PREFIX")
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if ulaPrefix == "" {
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ulaPrefix = defaultPrefix
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}
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if !strings.HasSuffix(ulaPrefix, "::") {
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if strings.HasSuffix(ulaPrefix, ":") {
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ulaPrefix += ":"
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} else {
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ulaPrefix += "::"
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}
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}
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// DNS defaults --------------------------------
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dns1 = os.Getenv("DNS1")
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dns2 = os.Getenv("DNS2")
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if dns1 == "" {
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dns1 = strings.Replace(ulaPrefix, "::", "::53", 1)
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}
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if dns2 == "" {
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dns2 = strings.Replace(ulaPrefix, "::", "::54", 1)
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}
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// Placeholder IP ------------------------------
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pageIP = os.Getenv("FORM_DEFAULT_IP")
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if pageIP == "" {
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pageIP = defaultIP
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}
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dhcpScope = os.Getenv("DHCP_SCOPE")
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dhcpServer = os.Getenv("DHCP_SERVER")
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// Range limit ---------------------------------
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if limStr := os.Getenv("RANGE_LIMIT"); limStr != "" {
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if v, err := strconv.Atoi(limStr); err == nil && v > 0 {
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rangeLimit = v
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} else {
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rangeLimit = defaultLimit
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}
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} else {
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rangeLimit = defaultLimit
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}
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// Templates -----------------------------------
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singleHTML := fmt.Sprintf(singlePageHTML, pageIP, ulaPrefix)
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rangeHTML := rangePageHTML
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singleTemplate = template.Must(template.New("single").Parse(singleHTML))
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rangeTemplate = template.Must(template.New("range").Parse(rangeHTML))
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fmt.Println(ulaPrefix, dns1, dns2, pageIP, dhcpServer, dhcpScope, rangeLimit)
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fmt.Println(singleHTML)
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fmt.Println(rangeHTML)
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}
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// ---------------------------------------------------------------------------
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// Template rendering helpers
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// ---------------------------------------------------------------------------
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func renderSingle(w http.ResponseWriter, d singleData) {
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w.Header().Set("Content-Type", "text/html; charset=utf-8")
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_ = singleTemplate.Execute(w, d)
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}
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func renderRange(w http.ResponseWriter, d rangeData) {
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w.Header().Set("Content-Type", "text/html; charset=utf-8")
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_ = rangeTemplate.Execute(w, d)
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}
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// ---------------------------------------------------------------------------
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// HTML templates as raw strings with %s placeholders (prefix, etc.)
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// ---------------------------------------------------------------------------
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var singlePageHTML = `<!DOCTYPE html>
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<html lang="de">
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<head>
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<meta charset="utf-8" />
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<title>IPv4 → IPv6-Mapper</title>
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<style>
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body{font-family:system-ui,sans-serif;margin:2rem}
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form{display:flex;gap:.5rem;flex-wrap:wrap;margin-bottom:1rem}
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input[type=text],input[readonly]{padding:.4rem;font-size:1rem;border:1px solid #ccc;border-radius:4px;flex:1}
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button{padding:.5rem 1rem;font-size:1rem;cursor:pointer;border-radius:4px;border:1px solid #666;background:#eee}
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button.copy{padding:.3rem .6rem;font-size:.9rem;margin-left:.3rem;background:#def}
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.row{display:flex;align-items:center;margin-bottom:.4rem}
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.row label{width:14rem}
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</style>
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<script>async function copy(id){const v=document.getElementById(id).value;await navigator.clipboard.writeText(v);const b=document.getElementById(id+'Btn');const o=b.textContent;b.textContent='✔';setTimeout(()=>b.textContent=o,1200);}</script>
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</head><body>
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<h1>IPv4 → IPv6 (einzeln)</h1>
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<form action="/convert" method="post">
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<input name="ipv4" type="text" placeholder="%s" value="{{.IPv4}}" required />
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<button>Umrechnen</button>
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<a href="/range" style="margin-left:1rem">» Bereich konvertieren</a>
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</form>
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{{if .HaveResult}}
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<div>
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<h2>Windows 11-Eingaben</h2>
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<div class="row"><label>IP-Adresse</label><input readonly id="ip" value="{{.IPv6}}"><button type="button" class="copy" id="ipBtn" onclick="copy('ip')">Copy</button></div>
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<div class="row"><label>Subnetzpräfix</label><input readonly id="pl" value="96"><button type="button" class="copy" id="plBtn" onclick="copy('pl')">Copy</button></div>
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<div class="row"><label>Gateway</label><input readonly id="gw" value="{{.Gateway}}"><button type="button" class="copy" id="gwBtn" onclick="copy('gw')">Copy</button></div>
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<div class="row"><label>DNS bevorzugt</label><input readonly id="dns1" value="{{.DNS1}}"><button type="button" class="copy" id="dns1Btn" onclick="copy('dns1')">Copy</button></div>
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<div class="row"><label>DNS alternativ</label><input readonly id="dns2" value="{{.DNS2}}"><button type="button" class="copy" id="dns2Btn" onclick="copy('dns2')">Copy</button></div>
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</div>
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{{end}}
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{{if .Error}}<p style="color:#b00">Fehler: {{.Error}}</p>{{end}}
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<p style="margin-top:1rem">Aktives Präfix: <code>%s</code> (/96)</p>
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</body></html>`
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var rangePageHTML = `<!DOCTYPE html>
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<html lang="de">
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<head>
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<meta charset="utf-8" />
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<title>IPv4-Range → IPv6</title>
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<style>
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body{font-family:system-ui,sans-serif;margin:2rem}
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table{border-collapse:collapse;width:100%}
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th,td{border:1px solid #ccc;padding:.4rem;text-align:left;font-family:monospace}
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form{display:flex;gap:.5rem;flex-wrap:wrap;margin-bottom:1rem}
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input[type=text]{padding:.4rem;font-size:1rem;border:1px solid #ccc;border-radius:4px;flex:1}
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button{padding:.5rem 1rem;font-size:1rem;cursor:pointer;border-radius:4px;border:1px solid #666;background:#eee}
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</style>
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</head><body>
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<h1>IPv4-Bereich → IPv6-Tabelle</h1>
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<form action="/range" method="post">
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<input name="start" type="text" placeholder="Start-IPv4" value="{{.Start}}" required />
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<input name="end" type="text" placeholder="End-IPv4" value="{{.End}}" required />
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<button>Konvertieren</button>
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<a href="/" style="margin-left:1rem">« Einzelkonverter</a>
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</form>
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{{if .HaveResult}}
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<table>
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<tr><th>IPv4</th><th>IPv6</th><th>DHCP-IPv4</th><th>DHCP-IPv6</th></tr>
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{{range .Rows}}<tr><td>{{.IPv4}}</td><td>{{.IPv6}}</td><td>netsh DHCP Server {{$.DhcpServer}} Scope {{$.DhcpScope}} Add reservedip {{.IPv4}} "{{.Name}}.stadt-hilden.de" "" "DHCP"</td><td>---</td></tr>{{end}}
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</table>
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{{end}}
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{{if .Error}}<p style="color:#b00">Fehler: {{.Error}}</p>{{end}}
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</body></html>`
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