Add per-IP connection limit to prevent resource exhaustion (v0.52.10)

- Add ORLY_MAX_CONN_PER_IP config option (default 25, hard limit 40)
- Track connections per IP in Server struct
- Reject new connections with HTTP 429 when limit exceeded
- Properly decrement count when connections close

This prevents a single IP from opening unlimited connections and
exhausting server memory/goroutines.

Files modified:
- app/config/config.go: Add MaxConnectionsPerIP config
- app/server.go: Add connPerIP tracking map
- app/main.go: Initialize connPerIP map
- app/handle-websocket.go: Implement per-IP limit check
- pkg/version/version: Bump to v0.52.10

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/config/config.go

@@ -146,6 +146,7 @@ type C struct {
 
 	// Connection concurrency control
 	MaxHandlersPerConnection int `env:"ORLY_MAX_HANDLERS_PER_CONN" default:"100" usage:"max concurrent message handlers per WebSocket connection (limits goroutine growth under load)"`
+	MaxConnectionsPerIP      int `env:"ORLY_MAX_CONN_PER_IP" default:"25" usage:"max WebSocket connections per IP address (prevents resource exhaustion, hard limit 40)"`
 
 	// Adaptive rate limiting (PID-controlled)
 	RateLimitEnabled            bool    `env:"ORLY_RATE_LIMIT_ENABLED" default:"true" usage:"enable adaptive PID-controlled rate limiting for database operations"`

app/handle-websocket.go

@@ -56,6 +56,42 @@ func (s *Server) HandleWebsocket(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 whitelist:
+	// Extract IP from remote (strip port)
+	ip := remote
+	if idx := strings.LastIndex(remote, ":"); idx != -1 {
+		ip = remote[:idx]
+	}
+
+	// Check per-IP connection limit (hard limit 40, default 25)
+	maxConnPerIP := s.Config.MaxConnectionsPerIP
+	if maxConnPerIP <= 0 {
+		maxConnPerIP = 25
+	}
+	if maxConnPerIP > 40 {
+		maxConnPerIP = 40 // Hard limit
+	}
+
+	s.connPerIPMu.Lock()
+	currentConns := s.connPerIP[ip]
+	if currentConns >= maxConnPerIP {
+		s.connPerIPMu.Unlock()
+		log.W.F("connection limit exceeded for IP %s: %d/%d connections", ip, currentConns, maxConnPerIP)
+		http.Error(w, "too many connections from your IP", http.StatusTooManyRequests)
+		return
+	}
+	s.connPerIP[ip]++
+	s.connPerIPMu.Unlock()
+
+	// Decrement connection count when this function returns
+	defer func() {
+		s.connPerIPMu.Lock()
+		s.connPerIP[ip]--
+		if s.connPerIP[ip] <= 0 {
+			delete(s.connPerIP, ip)
+		}
+		s.connPerIPMu.Unlock()
+	}()
+
 	// Create an independent context for this connection
 	// This context will be cancelled when the connection closes or server shuts down
 	ctx, cancel := context.WithCancel(s.Ctx)

app/main.go

@@ -87,6 +87,7 @@ func Run(
 		rateLimiter: limiter,
 		cfg:         cfg,
 		db:          db,
+		connPerIP:   make(map[string]int),
 	}
 
 	// Initialize branding/white-label manager if enabled

app/server.go

@@ -57,6 +57,10 @@ type Server struct {
 	// optional reverse proxy for dev web server
 	devProxy *httputil.ReverseProxy
 
+	// Per-IP connection tracking to prevent resource exhaustion
+	connPerIPMu sync.RWMutex
+	connPerIP   map[string]int
+
 	// Challenge storage for HTTP UI authentication
 	challengeMutex sync.RWMutex
 	challenges     map[string][]byte

pkg/version/version

@@ -1 +1 @@
-v0.52.9
+v0.52.10