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Fix und Anpassungen für DNS und Gateway
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jbergner
2025-05-09 09:02:22 +02:00
parent b4e90b1e92
commit dd258426ca
1 changed files with 125 additions and 40 deletions
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165
main.go
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@@ -1,3 +1,21 @@
// A small Go web‑server that converts an IPv4 address into an IPv6 address
// inside a user‑defined /96 ULA prefix and outputs Windows 11‑ready fields.
//
// Environment variables (all optional):
//
// ULA_PREFIX – /96 prefix to embed into, default "fdcb:7de3:a12a:0::"
// FORM_DEFAULT_IP - legt das Form Placeholder IP Feld fest (default: 172.16.0.0)
// DNS1 – preferred DNS IPv6 address (default: <prefix with 1::53>)
// DNS2 – alternate DNS IPv6 address (default: <prefix with 1::54>)
//
// Build & run:
//
// export ULA_PREFIX="fde5:1234:abcd:0::"
// export DNS1="fde5:1234:abcd:1::53" # optional
// export DNS2="fde5:1234:abcd:1::54" # optional
// go run main.go
//
// Open http://localhost:8080 in a browser.
package main package main
import ( import (
@@ -11,29 +29,36 @@ import (
) )
const ( const (
listenAddr = ":8080" // TCP port for the web UI listenAddr = ":8080"
defaultPrefix = "fdcb:7de3:a12a:0::" // fallback when ULA_PREFIX is unset defaultPrefix = "fd09:cafe:affe:4010::" // fallback /96
prefixLen = 96 // fixed /96 mapping
defaultIP = "172.16.0.0" defaultIP = "172.16.0.0"
) )
var ( var (
ulaPrefix string // effective /96 prefix (always ending in "::") ulaPrefix string // effective /96 prefix (always ends with ::)
pageTemplate *template.Template // populated in init() dns1 string // preferred DNS
dns2 string // alternate DNS
pageIP string pageIP string
pageTemplate *template.Template // compiled HTML template
) )
// viewData feeds data into the HTML template. // viewData is passed into the template.
type viewData struct { type viewData struct {
IPv4 string IPv4 string
IPv6 string IPv6 string
Error string Gateway string
DNS1 string
DNS2 string
Error string
HaveResult bool
} }
func main() { func main() {
initPrefixAndTemplate() initConfigAndTemplate()
http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) { http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
renderPage(w, viewData{}) // empty form renderPage(w, viewData{})
}) })
http.HandleFunc("/convert", func(w http.ResponseWriter, r *http.Request) { http.HandleFunc("/convert", func(w http.ResponseWriter, r *http.Request) {
@@ -47,28 +72,33 @@ func main() {
if err != nil { if err != nil {
data.Error = err.Error() data.Error = err.Error()
} else { } else {
data.HaveResult = true
data.IPv6 = ipv6 data.IPv6 = ipv6
data.Gateway = ulaPrefix + "1" // router IP = <prefix>::1
data.DNS1 = dns1
data.DNS2 = dns2
} }
renderPage(w, data) renderPage(w, data)
}) })
log.Printf("Server läuft auf http://localhost%s (Präfix: %s)", listenAddr, ulaPrefix) log.Printf("Server läuft auf http://localhost%s (Präfix %s, DNS1 %s, DNS2 %s)", listenAddr, ulaPrefix, dns1, dns2)
log.Fatal(http.ListenAndServe(listenAddr, nil)) log.Fatal(http.ListenAndServe(listenAddr, nil))
} }
// initPrefixAndTemplate reads the environment variable and prepares the HTML template. // initConfigAndTemplate reads env vars and prepares HTML template.
func initPrefixAndTemplate() { func initConfigAndTemplate() {
// ---- ULA prefix -------------------------------------------------------
ulaPrefix = os.Getenv("ULA_PREFIX") ulaPrefix = os.Getenv("ULA_PREFIX")
if ulaPrefix == "" { if ulaPrefix == "" {
ulaPrefix = defaultPrefix ulaPrefix = defaultPrefix
} }
pageIP = os.Getenv("IPv4") pageIP = os.Getenv("FORM_DEFAULT_IP")
if pageIP == "" { if pageIP == "" {
pageIP = defaultIP pageIP = defaultIP
} }
// Ensure the prefix ends with exactly two colons (::) so that we can append hex words. // ensure trailing :: so we can simply append hex words
if !strings.HasSuffix(ulaPrefix, "::") { if !strings.HasSuffix(ulaPrefix, "::") {
if strings.HasSuffix(ulaPrefix, ":") { if strings.HasSuffix(ulaPrefix, ":") {
ulaPrefix += ":" ulaPrefix += ":"
@@ -77,47 +107,102 @@ func initPrefixAndTemplate() {
} }
} }
// ---- DNS addresses ----------------------------------------------------
dns1 = os.Getenv("DNS1")
dns2 = os.Getenv("DNS2")
// default DNS: change subnet 0 → 1 and append ::53 / ::54
if dns1 == "" {
dns1 = strings.Replace(ulaPrefix, "::", "::53", 1)
}
if dns2 == "" {
dns2 = strings.Replace(ulaPrefix, "::", "::54", 1)
}
// ---- HTML template ----------------------------------------------------
html := fmt.Sprintf(`<!DOCTYPE html> html := fmt.Sprintf(`<!DOCTYPE html>
<html lang="de"> <html lang="de">
<head> <head>
<meta charset="utf-8" /> <meta charset="utf-8" />
<title>IPv4 → IPv6‑Mapper</title> <title>IPv4 → IPv6‑Mapper</title>
<style> <style>
body { font-family: system-ui, sans-serif; margin: 2rem; } body{font-family:system-ui,sans-serif;margin:2rem;max-width:46rem}
form { display: flex; gap: .5rem; } form{display:flex;gap:.5rem;flex-wrap:wrap}
input[type=text] { flex: 1; padding: .4rem; font-size: 1rem; } input[type=text],input[readonly]{padding:.4rem;font-size:1rem;border:1px solid #ccc;border-radius:4px;flex:1}
button { padding: .5rem 1rem; font-size: 1rem; cursor: pointer; } button{padding:.5rem 1rem;font-size:1rem;cursor:pointer;border-radius:4px;border:1px solid #666;background:#eee}
#result { margin-top: 1.5rem; font-weight: bold; } button.copy{padding:.3rem .6rem;font-size:.9rem;margin-left:.3rem;background:#def}
.error { color: #b00; } #result{margin-top:1.5rem}
</style> .row{display:flex;align-items:center;margin-bottom:.4rem}
.row label{width:14rem}
</style>
<script>
async function copy(id){
const val=document.getElementById(id).value;
await navigator.clipboard.writeText(val);
const btn=document.getElementById(id+"Btn");
const old=btn.textContent;
btn.textContent="✔ kopiert";
setTimeout(()=>btn.textContent=old,1200);
}
</script>
</head> </head>
<body> <body>
<h1>IPv4 → IPv6-Mapper</h1> <h1>IPv4 → IPv6‑Mapper</h1>
<form action="/convert" method="post"> <form action="/convert" method="post">
<input type="text" name="ipv4" placeholder="%s" value="{{.IPv4}}" required /> <input type="text" name="ipv4" placeholder="%s" value="{{.IPv4}}" required />
<button type="submit">Umrechnen</button> <button type="submit">Umrechnen</button>
</form> </form>
{{if .IPv6}}
<div id="result">IPv6-Adresse: <code>{{.IPv6}}</code></div> {{if .HaveResult}}
{{end}} <div id="result">
{{if .Error}} <h2>Windows 11‑Eingaben</h2>
<div class="error">Fehler: {{.Error}}</div> <div class="row">
{{end}} <label for="ip">IP‑Adresse</label>
<p>Präfix: <code>%s</code> &nbsp; (/96‑Zuordnung)</p> <input readonly id="ip" value="{{.IPv6}}" />
<button type="button" class="copy" id="ipBtn" onclick="copy('ip')">Kopieren</button>
</div>
<div class="row">
<label for="pl">Subnetzpräfixlänge</label>
<input readonly id="pl" value="96" />
<button type="button" class="copy" id="plBtn" onclick="copy('pl')">Kopieren</button>
</div>
<div class="row">
<label for="gw">Gateway (Bleibt vorerst leer!)</label>
<input readonly id="gw" value="{{.Gateway}}" />
<button type="button" class="copy" id="gwBtn" onclick="copy('gw')">Kopieren</button>
</div>
<div class="row">
<label for="dns1">Bevorzugter DNS</label>
<input readonly id="dns1" value="{{.DNS1}}" />
<button type="button" class="copy" id="dns1Btn" onclick="copy('dns1')">Kopieren</button>
</div>
<div class="row">
<label for="dns2">Alternativer DNS</label>
<input readonly id="dns2" value="{{.DNS2}}" />
<button type="button" class="copy" id="dns2Btn" onclick="copy('dns2')">Kopieren</button>
</div>
</div>
{{end}}
{{if .Error}}
<p style="color:#b00">Fehler: {{.Error}}</p>
{{end}}
<p style="margin-top:1.5rem">Aktives Präfix: <code>%s</code> (/96)</p>
</body> </body>
</html>`, pageIP, ulaPrefix) </html>`, pageIP, ulaPrefix)
pageTemplate = template.Must(template.New("page").Parse(html)) pageTemplate = template.Must(template.New("page").Parse(html))
} }
// embedIPv4 converts a dotted IPv4 string into the chosen ULA /96 IPv6 address. // embedIPv4 converts a dotted IPv4 string into an IPv6 address within ulaPrefix/96.
func embedIPv4(ipv4 string) (string, error) { func embedIPv4(ipv4 string) (string, error) {
ip := net.ParseIP(ipv4).To4() ip := net.ParseIP(ipv4).To4()
if ip == nil { if ip == nil {
return "", fmt.Errorf("'%s' ist keine gültige IPv4-Adresse", ipv4) return "", fmt.Errorf("'%s' ist keine gültige IPv4-Adresse", ipv4)
} }
hi := uint16(ip[0])<<8 | uint16(ip[1]) // high 16 bits (octets 0–1) hi := uint16(ip[0])<<8 | uint16(ip[1])
lo := uint16(ip[2])<<8 | uint16(ip[3]) // low 16 bits (octets 2–3) lo := uint16(ip[2])<<8 | uint16(ip[3])
return fmt.Sprintf("%s%x:%x", ulaPrefix, hi, lo), nil return fmt.Sprintf("%s%x:%x", ulaPrefix, hi, lo), nil
} }