Add CBOR and agent initiated WebSocket connections (#51, #490, #646, #845, etc)

- Add version exchange between hub and agent.
- Introduce ConnectionManager for managing WebSocket and SSH connections.
- Implement fingerprint generation and storage in agent.
- Create expiry map package to store universal tokens.
- Update config.yml configuration to include tokens.
- Enhance system management with new methods for handling system states and alerts.
- Update front-end components to support token / fingerprint management features.
- Introduce utility functions for token generation and hub URL retrieval.

Co-authored-by: nhas <jordanatararimu@gmail.com>

beszel/internal/hub/expirymap/expirymap.go

@@ -0,0 +1,104 @@
+package expirymap
+
+import (
+	"reflect"
+	"time"
+
+	"github.com/pocketbase/pocketbase/tools/store"
+)
+
+type val[T any] struct {
+	value   T
+	expires time.Time
+}
+
+type ExpiryMap[T any] struct {
+	store           *store.Store[string, *val[T]]
+	cleanupInterval time.Duration
+}
+
+// New creates a new expiry map with custom cleanup interval
+func New[T any](cleanupInterval time.Duration) *ExpiryMap[T] {
+	m := &ExpiryMap[T]{
+		store:           store.New(map[string]*val[T]{}),
+		cleanupInterval: cleanupInterval,
+	}
+	m.startCleaner()
+	return m
+}
+
+// Set stores a value with the given TTL
+func (m *ExpiryMap[T]) Set(key string, value T, ttl time.Duration) {
+	m.store.Set(key, &val[T]{
+		value:   value,
+		expires: time.Now().Add(ttl),
+	})
+}
+
+// GetOk retrieves a value and checks if it exists and hasn't expired
+// Performs lazy cleanup of expired entries on access
+func (m *ExpiryMap[T]) GetOk(key string) (T, bool) {
+	value, ok := m.store.GetOk(key)
+	if !ok {
+		return *new(T), false
+	}
+
+	// Check if expired and perform lazy cleanup
+	if value.expires.Before(time.Now()) {
+		m.store.Remove(key)
+		return *new(T), false
+	}
+
+	return value.value, true
+}
+
+// GetByValue retrieves a value by value
+func (m *ExpiryMap[T]) GetByValue(val T) (key string, value T, ok bool) {
+	for key, v := range m.store.GetAll() {
+		if reflect.DeepEqual(v.value, val) {
+			// check if expired
+			if v.expires.Before(time.Now()) {
+				m.store.Remove(key)
+				break
+			}
+			return key, v.value, true
+		}
+	}
+	return "", *new(T), false
+}
+
+// Remove explicitly removes a key
+func (m *ExpiryMap[T]) Remove(key string) {
+	m.store.Remove(key)
+}
+
+// RemovebyValue removes a value by value
+func (m *ExpiryMap[T]) RemovebyValue(value T) (T, bool) {
+	for key, val := range m.store.GetAll() {
+		if reflect.DeepEqual(val.value, value) {
+			m.store.Remove(key)
+			return val.value, true
+		}
+	}
+	return *new(T), false
+}
+
+// startCleaner runs the background cleanup process
+func (m *ExpiryMap[T]) startCleaner() {
+	go func() {
+		tick := time.Tick(m.cleanupInterval)
+		for range tick {
+			m.cleanup()
+		}
+	}()
+}
+
+// cleanup removes all expired entries
+func (m *ExpiryMap[T]) cleanup() {
+	now := time.Now()
+	for key, val := range m.store.GetAll() {
+		if val.expires.Before(now) {
+			m.store.Remove(key)
+		}
+	}
+}