server: add client registry with dashboard support (#5115)

server/client_registry.go

@@ -0,0 +1,146 @@
+package server
+
+import (
+	"fmt"
+	"maps"
+	"sync"
+	"time"
+)
+
+// ClientInfo captures metadata about a connected frpc instance.
+type ClientInfo struct {
+	Key              string
+	User             string
+	ClientID         string
+	RunID            string
+	Hostname         string
+	Metas            map[string]string
+	FirstConnectedAt time.Time
+	LastConnectedAt  time.Time
+	DisconnectedAt   time.Time
+	Online           bool
+}
+
+// ClientRegistry keeps track of active clients keyed by "{user}.{clientID}" (or runID if clientID is empty).
+// Entries without an explicit clientID are removed on disconnect to avoid stale offline records.
+type ClientRegistry struct {
+	mu       sync.RWMutex
+	clients  map[string]*ClientInfo
+	runIndex map[string]string
+}
+
+func NewClientRegistry() *ClientRegistry {
+	return &ClientRegistry{
+		clients:  make(map[string]*ClientInfo),
+		runIndex: make(map[string]string),
+	}
+}
+
+// Register stores/updates metadata for a client and returns the registry key plus whether it conflicts with an online client.
+func (cr *ClientRegistry) Register(user, clientID, runID, hostname string, metas map[string]string) (key string, conflict bool) {
+	if runID == "" {
+		return "", false
+	}
+
+	effectiveID := clientID
+	if effectiveID == "" {
+		effectiveID = runID
+	}
+	key = cr.composeClientKey(user, effectiveID)
+	enforceUnique := clientID != ""
+
+	now := time.Now()
+	cr.mu.Lock()
+	defer cr.mu.Unlock()
+
+	info, exists := cr.clients[key]
+	if enforceUnique && exists && info.Online && info.RunID != "" && info.RunID != runID {
+		return key, true
+	}
+
+	if !exists {
+		info = &ClientInfo{
+			Key:              key,
+			User:             user,
+			ClientID:         clientID,
+			FirstConnectedAt: now,
+		}
+		cr.clients[key] = info
+	} else if info.RunID != "" {
+		delete(cr.runIndex, info.RunID)
+	}
+
+	info.RunID = runID
+	info.Hostname = hostname
+	info.Metas = metas
+	if info.FirstConnectedAt.IsZero() {
+		info.FirstConnectedAt = now
+	}
+	info.LastConnectedAt = now
+	info.DisconnectedAt = time.Time{}
+	info.Online = true
+
+	cr.runIndex[runID] = key
+	return key, false
+}
+
+// MarkOfflineByRunID marks the client as offline when the corresponding control disconnects.
+func (cr *ClientRegistry) MarkOfflineByRunID(runID string) {
+	cr.mu.Lock()
+	defer cr.mu.Unlock()
+
+	key, ok := cr.runIndex[runID]
+	if !ok {
+		return
+	}
+	if info, ok := cr.clients[key]; ok && info.RunID == runID {
+		if info.ClientID == "" {
+			delete(cr.clients, key)
+		} else {
+			info.RunID = ""
+			info.Online = false
+			now := time.Now()
+			info.DisconnectedAt = now
+		}
+	}
+	delete(cr.runIndex, runID)
+}
+
+// List returns a snapshot of all known clients.
+func (cr *ClientRegistry) List() []ClientInfo {
+	cr.mu.RLock()
+	defer cr.mu.RUnlock()
+
+	result := make([]ClientInfo, 0, len(cr.clients))
+	for _, info := range cr.clients {
+		cp := *info
+		cp.Metas = maps.Clone(info.Metas)
+		result = append(result, cp)
+	}
+	return result
+}
+
+// GetByKey retrieves a client by its composite key ({user}.{clientID} or runID fallback).
+func (cr *ClientRegistry) GetByKey(key string) (ClientInfo, bool) {
+	cr.mu.RLock()
+	defer cr.mu.RUnlock()
+
+	info, ok := cr.clients[key]
+	if !ok {
+		return ClientInfo{}, false
+	}
+	cp := *info
+	cp.Metas = maps.Clone(info.Metas)
+	return cp, true
+}
+
+func (cr *ClientRegistry) composeClientKey(user, id string) string {
+	switch {
+	case user == "":
+		return id
+	case id == "":
+		return user
+	default:
+		return fmt.Sprintf("%s.%s", user, id)
+	}
+}