pandora: Add a OnPairing method to host interface

- Adds OnPairing method to receive a stream of pairing events.
- Reorganizes interface.

Test: m PandoraServer
Change-Id: I578542dca3f5e9cced0c6a53f1f693c62119a4da

android/pandora/server/proto/pandora/host.proto

@@ -18,8 +18,9 @@ service Host {
   // The GRPC server might take some time to be available after
   // this command.
   rpc Reset(google.protobuf.Empty) returns (google.protobuf.Empty);
-  // Remove pairing
-  rpc DeletePairing(DeletePairingRequest) returns (DeletePairingResponse);
+  // Read the local Bluetooth device address.
+  // This should return the same value as a Read BD_ADDR HCI command.
+  rpc ReadLocalAddress(google.protobuf.Empty) returns (ReadLocalAddressResponse);
   // Create an ACL BR/EDR connection to a peer.
   // This should send a CreateConnection on the HCI level.
   // If the two devices have not established a previous bond,
@@ -31,13 +32,25 @@ service Host {
   rpc WaitConnection(WaitConnectionRequest) returns (WaitConnectionResponse);
   // Disconnect an ACL BR/EDR connection. The Connection must not be reused afterwards.
   rpc Disconnect(DisconnectRequest) returns (DisconnectResponse);
-  // Read the local Bluetooth device address.
-  // This should return the same value as a Read BD_ADDR HCI command.
-  rpc ReadLocalAddress(google.protobuf.Empty) returns (ReadLocalAddressResponse);
-  // Create a LE connection
+  // Create a LE connection.
   rpc ConnectLE(ConnectLERequest) returns (ConnectLEResponse);
-  // Disconnect ongoing LE connection
+  // Disconnect ongoing LE connection.
   rpc DisconnectLE(DisconnectLERequest) returns (google.protobuf.Empty);
+  // Listen to pairing events.
+  // This is handled independently from connections for several reasons:
+  // - Pairing can be triggered at any time and multiple times during the
+  //   lifetime of a connection (this also explains why this is a stream).
+  // - In BR/EDR, the specification allows for a device to authenticate before
+  //   connecting when in security mode 3 (link level enforced security).
+  rpc OnPairing(stream PairingEventAnswer) returns (stream PairingEvent);
+  // Remove pairing.
+  rpc DeletePairing(DeletePairingRequest) returns (DeletePairingResponse);
+}
+
+// Response of the `ReadLocalAddress` method.
+message ReadLocalAddressResponse {
+  // Local Bluetooth Device Address as array of 6 bytes.
+  bytes address = 1;
 }
 
 // A Token representing an ACL connection.
@@ -93,15 +106,6 @@ message WaitConnectionResponse {
   }
 }
 
-// Request of the `DeletePairing` method.
-message DeletePairingRequest {
-  // Local Bluetooth Device Address as array of 6 bytes.
-  bytes address = 1;
-}
-
-// Response of the `DeletePairing` method.
-message DeletePairingResponse {}
-
 // Request of the `Disconnect` method.
 message DisconnectRequest {
   // Connection that should be disconnected.
@@ -111,12 +115,6 @@ message DisconnectRequest {
 // Response of the `Disconnect` method.
 message DisconnectResponse {}
 
-// Response of the `ReadLocalAddress` method.
-message ReadLocalAddressResponse {
-  // Local Bluetooth Device Address as array of 6 bytes.
-  bytes address = 1;
-}
-
 // Request of the `ConnectLE` method
 message ConnectLERequest {
   bytes address = 1;
@@ -133,3 +131,53 @@ message ConnectLEResponse {
 message DisconnectLERequest {
   Connection connection = 1;
 }
+
+message PairingEvent {
+  // Peer Bluetooth Device Address as array of 6 bytes.
+  bytes address = 1;
+  // Authentication method used for this pairing event
+  oneof method {
+    // "Just Works" Secure Simple Pairing association
+    // model. Confirmation is automatic.
+    google.protobuf.Empty just_works = 2;
+    // Numeric Comparison Secure Simple Pairing association
+    // model. Confirmation is required.
+    uint32 numeric_comparison = 3;
+    // Passkey Entry Secure Simple Pairing association model.
+    // Passkey is shown to the user.
+    // The peer device receives a Passkey Entry request.
+    bytes passkey_entry_notification = 4;
+    // Passkey Entry Secure Simple Pairing association model.
+    // Passkey is typed by the user.
+    google.protobuf.Empty passkey_entry_request = 5;
+    // Legacy PIN Pairing.
+    // A PIN Code is typed by the user.
+    google.protobuf.Empty pin_code = 6;
+  }
+}
+
+message PairingEventAnswer {
+  // Received pairing event.
+  PairingEvent event = 1;
+  // Answer when needed to the pairing event method.
+  oneof answer {
+    // Numeric Comparison confirmation.
+    // Used when pairing event method is `numeric_comparison`.
+    bool confirm = 2;
+    // Passkey typed by the user.
+    // Used when pairing event method is `passkey_entry_request`.
+    bytes passkey = 3;
+    // Pin typed by the user.
+    // Used when pairing event method is `pin_code`.
+    uint32 pin = 4;
+  };
+}
+
+// Request of the `DeletePairing` method.
+message DeletePairingRequest {
+  // Local Bluetooth Device Address as array of 6 bytes.
+  bytes address = 1;
+}
+
+// Response of the `DeletePairing` method.
+message DeletePairingResponse {}