sd: add BLE pairing and bonding support

Makefile

@@ -23,6 +23,16 @@ smoketest-tinygo:
 	@md5sum test.hex
 	$(TINYGO) build -o test.hex -size=short -target=pca10040-s132v6       ./examples/nusserver
 	@md5sum test.hex
+	# Both pairing examples link in crypto/ecdh for LE Secure Connections,
+	# whose P-256 tables need more RAM than the nRF52832 has.
+	$(TINYGO) build -o test.hex -size=short -target=pca10056-s140v7       ./examples/pairing-justworks
+	@md5sum test.hex
+	$(TINYGO) build -o test.hex -size=short -target=microbit-v2-s113v7    ./examples/pairing-justworks
+	@md5sum test.hex
+	$(TINYGO) build -o test.hex -size=short -target=pca10056-s140v7       ./examples/pairing-passkey
+	@md5sum test.hex
+	$(TINYGO) build -o test.hex -size=short -target=microbit-v2-s113v7    ./examples/pairing-passkey
+	@md5sum test.hex
 	$(TINYGO) build -o test.hex -size=short -target=pca10040-s132v6       ./examples/scanner
 	@md5sum test.hex
 	$(TINYGO) build -o test.hex -size=short -target=pca10040-s132v6       ./examples/stop-advertisement

adapter_nrf528xx-full.go

@@ -24,6 +24,7 @@ func handleEvent() {
 		gapEvent := eventBuf.evt.unionfield_gap_evt()
 		switch id {
 		case C.BLE_GAP_EVT_CONNECTED:
+			secOnConnect()
 			connectEvent := gapEvent.params.unionfield_connected()
 			device := Device{
 				Address:          Address{makeMACAddress(connectEvent.peer_addr)},
@@ -50,8 +51,9 @@ func handleEvent() {
 			}
 		case C.BLE_GAP_EVT_DISCONNECTED:
 			if debug {
-				println("evt: disconnected")
+				println("evt: disconnected, reason", gapEvent.params.unionfield_disconnected().reason)
 			}
+			secOnDisconnect(gapEvent.conn_handle)
 			// Clean up state for this connection.
 			for i, cb := range gattcNotificationCallbacks {
 				if uint16(cb.connectionHandle) == currentConnection.handle.Reg {
@@ -148,6 +150,42 @@ func handleEvent() {
 					println("gap timeout: other")
 				}
 			}
+		case C.BLE_GAP_EVT_SEC_PARAMS_REQUEST:
+			if debug {
+				println("evt: gap security parameters request")
+			}
+			secOnSecParamsRequest(gapEvent.conn_handle)
+		case C.BLE_GAP_EVT_SEC_INFO_REQUEST:
+			if debug {
+				println("evt: gap security info request")
+			}
+			secOnSecInfoRequest(gapEvent.conn_handle, gapEvent.params.unionfield_sec_info_request())
+		case C.BLE_GAP_EVT_PASSKEY_DISPLAY:
+			if debug {
+				println("evt: gap passkey display")
+			}
+			secOnPasskeyDisplay(gapEvent.conn_handle, gapEvent.params.unionfield_passkey_display())
+		case C.BLE_GAP_EVT_AUTH_KEY_REQUEST:
+			if debug {
+				println("evt: gap auth key request")
+			}
+			secOnAuthKeyRequest(gapEvent.conn_handle)
+		case C.BLE_GAP_EVT_LESC_DHKEY_REQUEST:
+			if debug {
+				println("evt: gap lesc dhkey request")
+			}
+			secOnLESCDHKeyRequest(gapEvent.conn_handle)
+		case C.BLE_GAP_EVT_CONN_SEC_UPDATE:
+			if debug {
+				connSec := gapEvent.params.unionfield_conn_sec_update().conn_sec
+				println("evt: gap connection security update, mode", connSec.sec_mode.bitfield_sm(), "level", connSec.sec_mode.bitfield_lv())
+			}
+			secOnConnSecUpdate(gapEvent.conn_handle)
+		case C.BLE_GAP_EVT_AUTH_STATUS:
+			if debug {
+				println("evt: gap auth status:", gapEvent.params.unionfield_auth_status().auth_status)
+			}
+			secOnAuthStatus(gapEvent.conn_handle, gapEvent.params.unionfield_auth_status())
 		default:
 			if debug {
 				println("unknown GAP event:", id)
@@ -164,16 +202,19 @@ func handleEvent() {
 			if handler != nil {
 				handler.callback(Connection(gattsEvent.conn_handle), int(writeEvent.offset), data)
 			}
+			// The write may have changed a CCCD, which a bonded central
+			// expects to persist across reconnections.
+			secSaveSysAttrs(gattsEvent.conn_handle)
 		case C.BLE_GATTS_EVT_SYS_ATTR_MISSING:
 			// This event is generated when reading the Generic Attribute
 			// service. It appears to be necessary for bonded devices.
 			// From the docs:
 			// > If the pointer is NULL, the system attribute info is
 			// > initialized, assuming that the application does not have any
 			// > previously saved system attribute data for this device.
-			// Maybe we should look at the error, but as there's not really a
-			// way to handle it, ignore it.
-			C.sd_ble_gatts_sys_attr_set(gattsEvent.conn_handle, nil, 0, 0)
+			// If the connected central is bonded with us, its saved CCCD
+			// state is restored instead of being initialized.
+			secOnSysAttrMissing(gattsEvent.conn_handle)
 		case C.BLE_GATTS_EVT_EXCHANGE_MTU_REQUEST:
 			// This event is generated by some devices. While we could support
 			// larger MTUs, this default MTU is supported everywhere.

adapter_nrf528xx-peripheral.go

@@ -27,6 +27,7 @@ func handleEvent() {
 			if debug {
 				println("evt: connected in peripheral role")
 			}
+			secOnConnect()
 			currentConnection.handle.Reg = uint16(gapEvent.conn_handle)
 			connectEvent := gapEvent.params.unionfield_connected()
 			device := Device{
@@ -36,8 +37,9 @@ func handleEvent() {
 			DefaultAdapter.connectHandler(device, true)
 		case C.BLE_GAP_EVT_DISCONNECTED:
 			if debug {
-				println("evt: disconnected")
+				println("evt: disconnected, reason", gapEvent.params.unionfield_disconnected().reason)
 			}
+			secOnDisconnect(gapEvent.conn_handle)
 			currentConnection.handle.Reg = C.BLE_CONN_HANDLE_INVALID
 			// Auto-restart advertisement if needed.
 			if defaultAdvertisement.isAdvertising.Get() != 0 {
@@ -64,6 +66,42 @@ func handleEvent() {
 			C.sd_ble_gap_phy_update(gapEvent.conn_handle, &phyUpdateResponse)
 		case C.BLE_GAP_EVT_PHY_UPDATE:
 			// ignore confirmation of phy successfully updated
+		case C.BLE_GAP_EVT_SEC_PARAMS_REQUEST:
+			if debug {
+				println("evt: gap security parameters request")
+			}
+			secOnSecParamsRequest(gapEvent.conn_handle)
+		case C.BLE_GAP_EVT_SEC_INFO_REQUEST:
+			if debug {
+				println("evt: gap security info request")
+			}
+			secOnSecInfoRequest(gapEvent.conn_handle, gapEvent.params.unionfield_sec_info_request())
+		case C.BLE_GAP_EVT_PASSKEY_DISPLAY:
+			if debug {
+				println("evt: gap passkey display")
+			}
+			secOnPasskeyDisplay(gapEvent.conn_handle, gapEvent.params.unionfield_passkey_display())
+		case C.BLE_GAP_EVT_AUTH_KEY_REQUEST:
+			if debug {
+				println("evt: gap auth key request")
+			}
+			secOnAuthKeyRequest(gapEvent.conn_handle)
+		case C.BLE_GAP_EVT_LESC_DHKEY_REQUEST:
+			if debug {
+				println("evt: gap lesc dhkey request")
+			}
+			secOnLESCDHKeyRequest(gapEvent.conn_handle)
+		case C.BLE_GAP_EVT_CONN_SEC_UPDATE:
+			if debug {
+				connSec := gapEvent.params.unionfield_conn_sec_update().conn_sec
+				println("evt: gap connection security update, mode", connSec.sec_mode.bitfield_sm(), "level", connSec.sec_mode.bitfield_lv())
+			}
+			secOnConnSecUpdate(gapEvent.conn_handle)
+		case C.BLE_GAP_EVT_AUTH_STATUS:
+			if debug {
+				println("evt: gap auth status:", gapEvent.params.unionfield_auth_status().auth_status)
+			}
+			secOnAuthStatus(gapEvent.conn_handle, gapEvent.params.unionfield_auth_status())
 		default:
 			if debug {
 				println("unknown GAP event:", id)
@@ -80,16 +118,19 @@ func handleEvent() {
 			if handler != nil {
 				handler.callback(Connection(gattsEvent.conn_handle), int(writeEvent.offset), data)
 			}
+			// The write may have changed a CCCD, which a bonded central
+			// expects to persist across reconnections.
+			secSaveSysAttrs(gattsEvent.conn_handle)
 		case C.BLE_GATTS_EVT_SYS_ATTR_MISSING:
 			// This event is generated when reading the Generic Attribute
 			// service. It appears to be necessary for bonded devices.
 			// From the docs:
 			// > If the pointer is NULL, the system attribute info is
 			// > initialized, assuming that the application does not have any
 			// > previously saved system attribute data for this device.
-			// Maybe we should look at the error, but as there's not really a
-			// way to handle it, ignore it.
-			C.sd_ble_gatts_sys_attr_set(gattsEvent.conn_handle, nil, 0, 0)
+			// If the connected central is bonded with us, its saved CCCD
+			// state is restored instead of being initialized.
+			secOnSysAttrMissing(gattsEvent.conn_handle)
 		case C.BLE_GATTS_EVT_EXCHANGE_MTU_REQUEST:
 			// This event is generated by some devices. While we could support
 			// larger MTUs, this default MTU is supported everywhere.

adapter_sd.go

@@ -11,9 +11,8 @@ import (
 )
 
 // #include "ble.h"
-// #ifdef NRF51
-//   #include "nrf_soc.h"
-// #else
+// #include "nrf_soc.h"
+// #ifndef NRF51
 //   #include "nrf_nvic.h"
 // #endif
 import "C"
@@ -64,6 +63,18 @@ var DefaultAdapter = &Adapter{isDefault: true,
 
 var eventBufLen C.uint16_t
 
+// flashOpResult is set from the SWI2 interrupt handler when an asynchronous
+// sd_flash_write/sd_flash_page_erase command completes. It is a SoC event,
+// which is a separate event queue from the BLE events handled by
+// handleEvent, but delivered through the same interrupt (SD_EVT_IRQn is
+// SWI2_IRQn). 0 means no result yet, 1 success, 2 error. Consumed by bond
+// storage code where available.
+var flashOpResult volatile.Register8
+
+// Static because taking the address of a local variable for a C call would
+// heap-allocate, which is not allowed in interrupt context.
+var socEvtID C.uint32_t
+
 // Enable configures the BLE stack. It must be called before any
 // Bluetooth-related calls (unless otherwise indicated).
 func (a *Adapter) Enable() error {
@@ -88,6 +99,23 @@ func (a *Adapter) Enable() error {
 			}
 			handleEvent()
 		}
+
+		// Drain pending SoC events. Currently only flash operation
+		// completion is of interest, but any pending event must still be
+		// pulled out of the queue or the SoftDevice will stop delivering new
+		// ones.
+		for {
+			errCode := C.sd_evt_get(&socEvtID)
+			if errCode != 0 {
+				break
+			}
+			switch socEvtID {
+			case C.NRF_EVT_FLASH_OPERATION_SUCCESS:
+				flashOpResult.Set(1)
+			case C.NRF_EVT_FLASH_OPERATION_ERROR:
+				flashOpResult.Set(2)
+			}
+		}
 	})
 	intr.Enable()
 	intr.SetPriority(192)