Option to limit peer count that a normal user can create (#457)

docs/documentation/configuration/overview.md

@@ -38,6 +38,7 @@ advanced:
   rule_prio_offset: 20000
   route_table_offset: 20000
   api_admin_only: true
+  limit_additional_user_peers: 0
 
 database:
   debug: false
@@ -215,6 +216,10 @@ Additional or more specialized configuration options for logging and interface c
 - **Default:** `true`
 - **Description:** If `true`, the public REST API is accessible only to admin users. The API docs live at [`/api/v1/doc.html`](../rest-api/api-doc.md).
 
+### `limit_additional_user_peers`
+- **Default:** `0`
+- **Description:** Limit additional peers a normal user can create. `0` means unlimited.
+
 ---
 
 ## Database

internal/app/wireguard/wireguard_peers.go

@@ -188,6 +188,30 @@ func (m Manager) CreatePeer(ctx context.Context, peer *domain.Peer) (*domain.Pee
 
 	sessionUser := domain.GetUserInfo(ctx)
 
+    // Enforce peer limit for non-admin users if LimitAdditionalUserPeers is set
+    if m.cfg.Core.SelfProvisioningAllowed && !sessionUser.IsAdmin && m.cfg.Advanced.LimitAdditionalUserPeers > 0 {
+        peers, err := m.db.GetUserPeers(ctx, peer.UserIdentifier)
+        if err != nil {
+            return nil, fmt.Errorf("failed to fetch peers for user %s: %w", peer.UserIdentifier, err)
+        }
+        // Count enabled peers (disabled IS NULL)
+        peerCount := 0
+        for _, p := range peers {
+            if !p.IsDisabled() {
+                peerCount++
+            }
+        }
+        totalAllowedPeers := 1 + m.cfg.Advanced.LimitAdditionalUserPeers // 1 default peer + x additional peers
+        if peerCount >= totalAllowedPeers {
+            slog.WarnContext(ctx, "peer creation blocked due to limit",
+                "user", peer.UserIdentifier,
+                "current_count", peerCount,
+                "allowed_count", totalAllowedPeers)
+            return nil, fmt.Errorf("peer limit reached (%d peers allowed): %w", totalAllowedPeers, domain.ErrNoPermission)
+        }
+    }
+
+
 	existingPeer, err := m.db.GetPeer(ctx, peer.Identifier)
 	if err != nil && !errors.Is(err, domain.ErrNotFound) {
 		return nil, fmt.Errorf("unable to load existing peer %s: %w", peer.Identifier, err)

internal/config/config.go

@@ -29,18 +29,19 @@ type Config struct {
 	} `yaml:"core"`
 
 	Advanced struct {
-		LogLevel            string        `yaml:"log_level"`
-		LogPretty           bool          `yaml:"log_pretty"`
-		LogJson             bool          `yaml:"log_json"`
-		StartListenPort     int           `yaml:"start_listen_port"`
-		StartCidrV4         string        `yaml:"start_cidr_v4"`
-		StartCidrV6         string        `yaml:"start_cidr_v6"`
-		UseIpV6             bool          `yaml:"use_ip_v6"`
-		ConfigStoragePath   string        `yaml:"config_storage_path"` // keep empty to disable config export to file
-		ExpiryCheckInterval time.Duration `yaml:"expiry_check_interval"`
-		RulePrioOffset      int           `yaml:"rule_prio_offset"`
-		RouteTableOffset    int           `yaml:"route_table_offset"`
-		ApiAdminOnly        bool          `yaml:"api_admin_only"` // if true, only admin users can access the API
+		LogLevel                 string        `yaml:"log_level"`
+		LogPretty                bool          `yaml:"log_pretty"`
+		LogJson                  bool          `yaml:"log_json"`
+		StartListenPort          int           `yaml:"start_listen_port"`
+		StartCidrV4              string        `yaml:"start_cidr_v4"`
+		StartCidrV6              string        `yaml:"start_cidr_v6"`
+		UseIpV6                  bool          `yaml:"use_ip_v6"`
+		ConfigStoragePath        string        `yaml:"config_storage_path"` // keep empty to disable config export to file
+		ExpiryCheckInterval      time.Duration `yaml:"expiry_check_interval"`
+		RulePrioOffset           int           `yaml:"rule_prio_offset"`
+		RouteTableOffset         int           `yaml:"route_table_offset"`
+		ApiAdminOnly             bool          `yaml:"api_admin_only"` // if true, only admin users can access the API
+		LimitAdditionalUserPeers int           `yaml:"limit_additional_user_peers"`
 	} `yaml:"advanced"`
 
 	Statistics struct {
@@ -76,6 +77,7 @@ func (c *Config) LogStartupValues() {
 		"reEnablePeerAfterUserEnable", c.Core.ReEnablePeerAfterUserEnable,
 		"deletePeerAfterUserDeleted", c.Core.DeletePeerAfterUserDeleted,
 		"selfProvisioningAllowed", c.Core.SelfProvisioningAllowed,
+		"limitAdditionalUserPeers", c.Advanced.LimitAdditionalUserPeers,
 		"importExisting", c.Core.ImportExisting,
 		"restoreState", c.Core.RestoreState,
 		"useIpV6", c.Advanced.UseIpV6,
@@ -137,6 +139,7 @@ func defaultConfig() *Config {
 	cfg.Advanced.RulePrioOffset = 20000
 	cfg.Advanced.RouteTableOffset = 20000
 	cfg.Advanced.ApiAdminOnly = true
+	cfg.Advanced.LimitAdditionalUserPeers = 0
 
 	cfg.Statistics.UsePingChecks = true
 	cfg.Statistics.PingCheckWorkers = 10