fix(security): phase 2 high-severity hardening

- Push heartbeat accepts Authorization: Bearer header (query string deprecated)
- Gotify alerts use X-Gotify-Key header instead of token in URL
- Per-IP rate limiting on all API endpoints (token-bucket)
- /metrics gated behind cluster secret (UPTOP_METRICS_PUBLIC=true to opt out)
- Config export redacts passwords/tokens by default (redact_secrets=false to override)
- Fix rewritePlaceholders for 100+ SQL parameters
- Fix AddSiteReturningID/AddAlertReturningID race with LastInsertId/RETURNING
- HTTP server timeouts: read 30s, write 60s, idle 120s

internal/server/ratelimit.go

@@ -0,0 +1,91 @@
+package server
+
+import (
+	"net"
+	"net/http"
+	"sync"
+	"time"
+)
+
+type visitor struct {
+	tokens   float64
+	lastSeen time.Time
+}
+
+type RateLimiter struct {
+	mu       sync.Mutex
+	visitors map[string]*visitor
+	rate     float64
+	burst    float64
+}
+
+func NewRateLimiter(requestsPerMinute int) *RateLimiter {
+	rl := &RateLimiter{
+		visitors: make(map[string]*visitor),
+		rate:     float64(requestsPerMinute) / 60.0,
+		burst:    float64(requestsPerMinute),
+	}
+	go rl.cleanup()
+	return rl
+}
+
+func (rl *RateLimiter) Allow(ip string) bool {
+	rl.mu.Lock()
+	defer rl.mu.Unlock()
+
+	v, exists := rl.visitors[ip]
+	now := time.Now()
+
+	if !exists {
+		rl.visitors[ip] = &visitor{tokens: rl.burst - 1, lastSeen: now}
+		return true
+	}
+
+	elapsed := now.Sub(v.lastSeen).Seconds()
+	v.tokens += elapsed * rl.rate
+	if v.tokens > rl.burst {
+		v.tokens = rl.burst
+	}
+	v.lastSeen = now
+
+	if v.tokens < 1 {
+		return false
+	}
+	v.tokens--
+	return true
+}
+
+func (rl *RateLimiter) cleanup() {
+	for {
+		time.Sleep(5 * time.Minute)
+		rl.mu.Lock()
+		cutoff := time.Now().Add(-10 * time.Minute)
+		for ip, v := range rl.visitors {
+			if v.lastSeen.Before(cutoff) {
+				delete(rl.visitors, ip)
+			}
+		}
+		rl.mu.Unlock()
+	}
+}
+
+func clientIP(r *http.Request) string {
+	if fwd := r.Header.Get("X-Forwarded-For"); fwd != "" {
+		return fwd
+	}
+	host, _, err := net.SplitHostPort(r.RemoteAddr)
+	if err != nil {
+		return r.RemoteAddr
+	}
+	return host
+}
+
+func RateLimit(limiter *RateLimiter, next http.HandlerFunc) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		if !limiter.Allow(clientIP(r)) {
+			http.Error(w, "Rate limit exceeded", http.StatusTooManyRequests)
+			return
+		}
+		next(w, r)
+	}
+}