Initial commit: DDNS service with NIC V2 protocol support

Features:
- Token-based subdomain claiming
- NIC V2 (DynDNS2) protocol implementation
- Technitium DNS integration
- Rate limiting (10 req/min IP, 1 req/min token)
- Web UI for space claiming
- Docker/Docker Compose support
- Compatible with UniFi, pfSense, EdgeRouter

Module: git.dws.rip/DWS/dyn

internal/config/config.go

@@ -0,0 +1,83 @@
+package config
+
+import (
+	"os"
+	"strconv"
+	"strings"
+)
+
+type Config struct {
+	ServerPort         string
+	DatabasePath       string
+	TechnitiumURL      string
+	TechnitiumUsername string
+	TechnitiumPassword string
+	TechnitiumToken    string
+	BaseDomain         string
+	SpaceSubdomain     string
+	RateLimitPerIP     int
+	RateLimitPerToken  int
+	TrustedProxies     []string
+}
+
+func Load() *Config {
+	cfg := &Config{
+		ServerPort:         getEnv("SERVER_PORT", "8080"),
+		DatabasePath:       getEnv("DATABASE_PATH", "./dyn.db"),
+		TechnitiumURL:      getEnv("TECHNITIUM_URL", ""),
+		TechnitiumUsername: getEnv("TECHNITIUM_USERNAME", ""),
+		TechnitiumPassword: getEnv("TECHNITIUM_PASSWORD", ""),
+		TechnitiumToken:    getEnv("TECHNITIUM_TOKEN", ""),
+		BaseDomain:         getEnv("BASE_DOMAIN", "dws.rip"),
+		SpaceSubdomain:     getEnv("SPACE_SUBDOMAIN", "space"),
+		RateLimitPerIP:     getEnvAsInt("RATE_LIMIT_PER_IP", 10),
+		RateLimitPerToken:  getEnvAsInt("RATE_LIMIT_PER_TOKEN", 1),
+		TrustedProxies:     getEnvAsSlice("TRUSTED_PROXIES", []string{}),
+	}
+
+	return cfg
+}
+
+func (c *Config) Validate() []string {
+	var errors []string
+
+	if c.TechnitiumURL == "" {
+		errors = append(errors, "TECHNITIUM_URL is required")
+	}
+
+	if c.TechnitiumToken == "" && (c.TechnitiumUsername == "" || c.TechnitiumPassword == "") {
+		errors = append(errors, "Either TECHNITIUM_TOKEN or TECHNITIUM_USERNAME/PASSWORD must be provided")
+	}
+
+	return errors
+}
+
+func (c *Config) GetZone() string {
+	if c.SpaceSubdomain == "" {
+		return c.BaseDomain
+	}
+	return c.SpaceSubdomain + "." + c.BaseDomain
+}
+
+func getEnv(key, defaultValue string) string {
+	if value := os.Getenv(key); value != "" {
+		return value
+	}
+	return defaultValue
+}
+
+func getEnvAsInt(key string, defaultValue int) int {
+	if value := os.Getenv(key); value != "" {
+		if intVal, err := strconv.Atoi(value); err == nil {
+			return intVal
+		}
+	}
+	return defaultValue
+}
+
+func getEnvAsSlice(key string, defaultValue []string) []string {
+	if value := os.Getenv(key); value != "" {
+		return strings.Split(value, ",")
+	}
+	return defaultValue
+}