Fix und Anpassungen für DNS und Gateway

2025-05-09 09:02:22 +02:00
parent b4e90b1e92
commit dd258426ca
1 changed files with 125 additions and 40 deletions
--- a/main.go
+++ b/main.go
@@ -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

 import (
@@ -11,29 +29,36 @@ import (
 )

 const (
-	listenAddr    = ":8080"              // TCP port for the web UI
-	defaultPrefix = "fdcb:7de3:a12a:0::" // fallback when ULA_PREFIX is unset
+	listenAddr    = ":8080"
+	defaultPrefix = "fd09:cafe:affe:4010::" // fallback /96
+	prefixLen     = 96                      // fixed /96 mapping
 	defaultIP     = "172.16.0.0"
 )

 var (
-	ulaPrefix    string             // effective /96 prefix (always ending in "::")
-	pageTemplate *template.Template // populated in init()
+	ulaPrefix    string // effective /96 prefix (always ends with ::)
+	dns1         string // preferred DNS
+	dns2         string // alternate DNS
 	pageIP       string
+	pageTemplate *template.Template // compiled HTML template
 )

-// viewData feeds data into the HTML template.
+// viewData is passed into the template.
 type viewData struct {
 	IPv4       string
 	IPv6       string
+	Gateway    string
+	DNS1       string
+	DNS2       string
 	Error      string
+	HaveResult bool
 }

 func main() {
-	initPrefixAndTemplate()
+	initConfigAndTemplate()

 	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) {
@@ -47,28 +72,33 @@ func main() {
 		if err != nil {
 			data.Error = err.Error()
 		} else {
+			data.HaveResult = true
 			data.IPv6 = ipv6
+			data.Gateway = ulaPrefix + "1" // router IP = <prefix>::1
+			data.DNS1 = dns1
+			data.DNS2 = dns2
 		}
 		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))
 }

-// initPrefixAndTemplate reads the environment variable and prepares the HTML template.
-func initPrefixAndTemplate() {
+// initConfigAndTemplate reads env vars and prepares HTML template.
+func initConfigAndTemplate() {
+	// ---- ULA prefix -------------------------------------------------------
 	ulaPrefix = os.Getenv("ULA_PREFIX")
 	if ulaPrefix == "" {
 		ulaPrefix = defaultPrefix
 	}

-	pageIP = os.Getenv("IPv4")
+	pageIP = os.Getenv("FORM_DEFAULT_IP")
 	if pageIP == "" {
 		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, ":") {
 			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 lang="de">
 <head>
-<meta charset="utf-8" />
-<title>IPv4 → IPv6‑Mapper</title>
-<style>
- body { font-family: system-ui, sans-serif; margin: 2rem; }
- form { display: flex; gap: .5rem; }
- input[type=text] { flex: 1; padding: .4rem; font-size: 1rem; }
- button { padding: .5rem 1rem; font-size: 1rem; cursor: pointer; }
- #result { margin-top: 1.5rem; font-weight: bold; }
- .error { color: #b00; }
-</style>
+  <meta charset="utf-8" />
+  <title>IPv4 → IPv6‑Mapper</title>
+  <style>
+   body{font-family:system-ui,sans-serif;margin:2rem;max-width:46rem}
+   form{display:flex;gap:.5rem;flex-wrap:wrap}
+   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;border-radius:4px;border:1px solid #666;background:#eee}
+   button.copy{padding:.3rem .6rem;font-size:.9rem;margin-left:.3rem;background:#def}
+   #result{margin-top:1.5rem}
+   .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>
 <body>
- <h1>IPv4 → IPv6-Mapper</h1>
+  <h1>IPv4 → IPv6‑Mapper</h1>
  <form action="/convert" method="post">
    <input type="text" name="ipv4" placeholder="%s" value="{{.IPv4}}" required />
    <button type="submit">Umrechnen</button>
  </form>
- {{if .IPv6}}
-   <div id="result">IPv6-Adresse: <code>{{.IPv6}}</code></div>
+
+  {{if .HaveResult}}
+  <div id="result">
+    <h2>Windows 11‑Eingaben</h2>
+    <div class="row">
+      <label for="ip">IP‑Adresse</label>
+      <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}}
-   <div class="error">Fehler: {{.Error}}</div>
+    <p style="color:#b00">Fehler: {{.Error}}</p>
  {{end}}
- <p>Präfix: <code>%s</code> &nbsp; (/96‑Zuordnung)</p>
+
+  <p style="margin-top:1.5rem">Aktives Präfix: <code>%s</code> (/96)</p>
 </body>
 </html>`, pageIP, ulaPrefix)

 	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) {
 	ip := net.ParseIP(ipv4).To4()
 	if ip == nil {
 		return "", fmt.Errorf("'%s' ist keine gültige IPv4-Adresse", ipv4)
 	}
-	hi := uint16(ip[0])<<8 | uint16(ip[1]) // high 16 bits (octets 0–1)
-	lo := uint16(ip[2])<<8 | uint16(ip[3]) // low 16 bits  (octets 2–3)
+	hi := uint16(ip[0])<<8 | uint16(ip[1])
+	lo := uint16(ip[2])<<8 | uint16(ip[3])
 	return fmt.Sprintf("%s%x:%x", ulaPrefix, hi, lo), nil
 }