add middlewares, handlers and database models

internal/middleware/ratelimit.go

@@ -0,0 +1,151 @@
+package middleware
+
+import (
+	"log/slog"
+	"net/http"
+	"strings"
+	"sync"
+	"time"
+)
+
+// RateLimiter tracks request counts per IP address
+type RateLimiter struct {
+	mu       sync.RWMutex
+	requests map[string][]time.Time
+	limit    int           // Max requests allowed
+	window   time.Duration // Time window for rate limiting
+}
+
+// NewRateLimiter creates a new rate limiter
+func NewRateLimiter(limit int, window time.Duration) *RateLimiter {
+	rl := &RateLimiter{
+		requests: make(map[string][]time.Time),
+		limit:    limit,
+		window:   window,
+	}
+
+	// Start cleanup goroutine to prevent memory leak
+	go rl.cleanupLoop()
+
+	return rl
+}
+
+// Allow checks if request from IP should be allowed
+func (rl *RateLimiter) Allow(ip string) bool {
+	rl.mu.Lock()
+	defer rl.mu.Unlock()
+
+	now := time.Now()
+	cutoff := now.Add(-rl.window)
+
+	// Get requests for this IP
+	requests := rl.requests[ip]
+
+	// Remove old requests outside time window
+	validRequests := []time.Time{}
+	for _, reqTime := range requests {
+		if reqTime.After(cutoff) {
+			validRequests = append(validRequests, reqTime)
+		}
+	}
+
+	// Check if limit exceeded
+	if len(validRequests) >= rl.limit {
+		rl.requests[ip] = validRequests
+		return false
+	}
+
+	// Add current request
+	validRequests = append(validRequests, now)
+	rl.requests[ip] = validRequests
+
+	return true
+}
+
+// cleanupLoop periodically removes old entries to prevent memory leak
+func (rl *RateLimiter) cleanupLoop() {
+	ticker := time.NewTicker(5 * time.Minute)
+	defer ticker.Stop()
+
+	for range ticker.C {
+		rl.cleanup()
+	}
+}
+
+// cleanup removes IPs with no recent requests
+func (rl *RateLimiter) cleanup() {
+	rl.mu.Lock()
+	defer rl.mu.Unlock()
+
+	now := time.Now()
+	cutoff := now.Add(-rl.window * 2) // Keep data for 2x window
+
+	for ip, requests := range rl.requests {
+		// Check if all requests are old
+		allOld := true
+		for _, reqTime := range requests {
+			if reqTime.After(cutoff) {
+				allOld = false
+				break
+			}
+		}
+
+		// Remove IP if all requests are old
+		if allOld {
+			delete(rl.requests, ip)
+		}
+	}
+}
+
+// RateLimitAuth creates middleware for auth endpoints
+// Limits: 5 requests per 15 minutes per IP
+func RateLimitAuth() func(http.HandlerFunc) http.HandlerFunc {
+	limiter := NewRateLimiter(5, 15*time.Minute)
+
+	return func(next http.HandlerFunc) http.HandlerFunc {
+		return func(w http.ResponseWriter, r *http.Request) {
+			// Get real IP (handle proxies)
+			ip := getClientIP(r)
+
+			// Check rate limit
+			if !limiter.Allow(ip) {
+				slog.Warn("rate limit exceeded",
+					"ip", ip,
+					"path", r.URL.Path,
+				)
+				http.Error(w, "Too many requests. Please try again later.", http.StatusTooManyRequests)
+				return
+			}
+
+			next(w, r)
+		}
+	}
+}
+
+// getClientIP extracts real client IP from request
+func getClientIP(r *http.Request) string {
+	// Check X-Forwarded-For header (proxy/load balancer)
+	xff := r.Header.Get("X-Forwarded-For")
+	if xff != "" {
+		// Take first IP in list
+		ips := strings.Split(xff, ",")
+		if len(ips) > 0 {
+			return strings.TrimSpace(ips[0])
+		}
+	}
+
+	// Check X-Real-IP header
+	xri := r.Header.Get("X-Real-IP")
+	if xri != "" {
+		return strings.TrimSpace(xri)
+	}
+
+	// Fallback to RemoteAddr
+	ip := r.RemoteAddr
+	// Remove port if present
+	if idx := strings.LastIndex(ip, ":"); idx != -1 {
+		ip = ip[:idx]
+	}
+
+	return ip
+}