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/middleware/ratelimit.go

@@ -0,0 +1,112 @@
+package middleware
+
+import (
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/gin-gonic/gin"
+)
+
+type RateLimiter struct {
+	ipLimits      map[string]*RateLimitEntry
+	tokenLimits   map[string]*RateLimitEntry
+	mu            sync.RWMutex
+	limitPerIP    int
+	limitPerToken int
+}
+
+type RateLimitEntry struct {
+	Count     int
+	ResetTime time.Time
+}
+
+func NewRateLimiter(perIP, perToken int) *RateLimiter {
+	return &RateLimiter{
+		ipLimits:      make(map[string]*RateLimitEntry),
+		tokenLimits:   make(map[string]*RateLimitEntry),
+		limitPerIP:    perIP,
+		limitPerToken: perToken,
+	}
+}
+
+func (rl *RateLimiter) RateLimitByIP() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		ip := c.ClientIP()
+
+		rl.mu.Lock()
+		entry, exists := rl.ipLimits[ip]
+		now := time.Now()
+
+		if !exists || now.After(entry.ResetTime) {
+			rl.ipLimits[ip] = &RateLimitEntry{
+				Count:     1,
+				ResetTime: now.Add(time.Minute),
+			}
+			rl.mu.Unlock()
+			c.Next()
+			return
+		}
+
+		if entry.Count >= rl.limitPerIP {
+			rl.mu.Unlock()
+			c.String(http.StatusTooManyRequests, "rate limit exceeded")
+			c.Abort()
+			return
+		}
+
+		entry.Count++
+		rl.mu.Unlock()
+		c.Next()
+	}
+}
+
+func (rl *RateLimiter) RateLimitByToken() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		token := extractToken(c)
+		if token == "" {
+			c.Next()
+			return
+		}
+
+		rl.mu.Lock()
+		entry, exists := rl.tokenLimits[token]
+		now := time.Now()
+
+		if !exists || now.After(entry.ResetTime) {
+			rl.tokenLimits[token] = &RateLimitEntry{
+				Count:     1,
+				ResetTime: now.Add(time.Minute),
+			}
+			rl.mu.Unlock()
+			c.Next()
+			return
+		}
+
+		if entry.Count >= rl.limitPerToken {
+			rl.mu.Unlock()
+			c.String(http.StatusTooManyRequests, "rate limit exceeded")
+			c.Abort()
+			return
+		}
+
+		entry.Count++
+		rl.mu.Unlock()
+		c.Next()
+	}
+}
+
+func extractToken(c *gin.Context) string {
+	auth := c.GetHeader("Authorization")
+	if auth == "" {
+		return ""
+	}
+
+	parts := strings.SplitN(auth, " ", 2)
+	if len(parts) != 2 || parts[0] != "Basic" {
+		return ""
+	}
+
+	return parts[1]
+}