Add bluetooth agent

Signed-off-by: Hadi <[email protected]>

internal/bluetooth/agent.go

@@ -0,0 +1,83 @@
+package bluetooth
+
+import (
+	"fmt"
+	"sync"
+
+	"github.com/godbus/dbus/v5"
+)
+
+const (
+	agentPath       = dbus.ObjectPath("/org/anotherhadi/settuings/agent")
+	agentCapability = "DisplayYesNo"
+)
+
+// agent implements the BlueZ org.bluez.Agent1 interface, auto-accepting
+// every pairing prompt. `bluetoothctl pair` run non-interactively never
+// registers an agent, so BlueZ has nobody to ask for PIN/passkey
+// confirmation and any device that isn't "Just Works" fails with
+// AuthenticationFailed. Registering this agent as the system default
+// fixes that even though pairing itself still happens in a separate
+// bluetoothctl process: BlueZ routes auth requests to whichever agent is
+// registered as default, not to whoever initiated the pairing.
+type agent struct{}
+
+func (agent) Release() *dbus.Error { return nil }
+
+func (agent) RequestPinCode(_ dbus.ObjectPath) (string, *dbus.Error) {
+	return "", dbus.NewError("org.bluez.Error.Rejected", nil)
+}
+
+func (agent) DisplayPinCode(_ dbus.ObjectPath, _ string) *dbus.Error { return nil }
+
+func (agent) RequestPasskey(_ dbus.ObjectPath) (uint32, *dbus.Error) {
+	return 0, dbus.NewError("org.bluez.Error.Rejected", nil)
+}
+
+func (agent) DisplayPasskey(_ dbus.ObjectPath, _ uint32, _ uint16) *dbus.Error { return nil }
+
+func (agent) RequestConfirmation(_ dbus.ObjectPath, _ uint32) *dbus.Error { return nil }
+
+func (agent) RequestAuthorization(_ dbus.ObjectPath) *dbus.Error { return nil }
+
+func (agent) AuthorizeService(_ dbus.ObjectPath, _ string) *dbus.Error { return nil }
+
+func (agent) Cancel() *dbus.Error { return nil }
+
+var (
+	agentOnce sync.Once
+	agentErr  error
+	// agentConn is kept alive for the process lifetime: BlueZ calls back
+	// into our agent over this connection while pairing is in progress.
+	agentConn *dbus.Conn
+)
+
+// ensureAgent registers this process as BlueZ's default pairing agent, once
+// per run. Call before any Pair.
+func ensureAgent() error {
+	agentOnce.Do(func() {
+		conn, err := dbus.ConnectSystemBus()
+		if err != nil {
+			agentErr = fmt.Errorf("connect to system bus: %w", err)
+			return
+		}
+
+		if err := conn.Export(agent{}, agentPath, "org.bluez.Agent1"); err != nil {
+			agentErr = fmt.Errorf("export agent: %w", err)
+			return
+		}
+
+		manager := conn.Object("org.bluez", dbus.ObjectPath("/org/bluez"))
+		if call := manager.Call("org.bluez.AgentManager1.RegisterAgent", 0, agentPath, agentCapability); call.Err != nil {
+			agentErr = fmt.Errorf("register agent: %w", call.Err)
+			return
+		}
+		if call := manager.Call("org.bluez.AgentManager1.RequestDefaultAgent", 0, agentPath); call.Err != nil {
+			agentErr = fmt.Errorf("request default agent: %w", call.Err)
+			return
+		}
+
+		agentConn = conn
+	})
+	return agentErr
+}

internal/bluetooth/device.go

@@ -185,10 +185,13 @@ func Scan(seconds int) error {
 	return err
 }
 
-// Pair initiates pairing with a device. Because non-interactive
-// bluetoothctl has no agent to answer PIN/confirmation prompts, this only
-// succeeds for "just works" devices (most mice, keyboards, headsets).
+// Pair initiates pairing with a device, first registering settuings as
+// BlueZ's default agent so devices that need PIN/passkey confirmation
+// (not just "just works" ones) can complete pairing.
 func Pair(address string) error {
+	if err := ensureAgent(); err != nil {
+		return err
+	}
 	_, err := run(actionTimeout, "pair", address)
 	return err
 }