Skip to content

Commit

Permalink
Supports writes and displays names
Browse files Browse the repository at this point in the history
  • Loading branch information
@tdcolvin
tdcolvin committed Nov 11, 2023
1 parent a243c87 commit 05f2bb6
Show file tree
Hide file tree
Showing 2 changed files with 88 additions and 7 deletions.
72 changes: 66 additions & 6 deletions app/src/main/java/com/tdcolvin/bleserver/BluetoothCTFServer.kt
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,13 +15,15 @@ import android.content.Context
import androidx.annotation.RequiresPermission
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.update
import kotlinx.coroutines.withContext
import java.util.UUID
import kotlin.coroutines.resume
import kotlin.coroutines.suspendCoroutine

const val CTF_SERVICE_UUID = "e2f5f000-b11f-4623-b6b1-7d5373925267"
const val CTF_CHARACTERISTIC_UUID = "8c380000-10bd-4fdb-ba21-1922d6cf860d"
const val CTF_SERVICE_UUID = "8c380000-10bd-4fdb-ba21-1922d6cf860d"
const val PASSWORD_CHARACTERISTIC_UUID = "8c380001-10bd-4fdb-ba21-1922d6cf860d"
const val NAME_CHARACTERISTIC_UUID = "8c380002-10bd-4fdb-ba21-1922d6cf860d"

//These fields are marked as API >= 31 in the Manifest class, so we can't use those without warning.
//So we create our own, which prevents over-suppression of the Linter
Expand All @@ -34,14 +36,19 @@ class BluetoothCTFServer(private val context: Context) {
?: throw Exception("This device doesn't support Bluetooth")

private val serviceUuid = UUID.fromString(CTF_SERVICE_UUID)
private val characteristicUuid = UUID.fromString(CTF_CHARACTERISTIC_UUID)
private val passwordCharUuid = UUID.fromString(PASSWORD_CHARACTERISTIC_UUID)
private val nameCharUuid = UUID.fromString(NAME_CHARACTERISTIC_UUID)

private var server: BluetoothGattServer? = null
private var ctfService: BluetoothGattService? = null

private var advertiseCallback: AdvertiseCallback? = null
private val isServerListening: MutableStateFlow<Boolean?> = MutableStateFlow(null)

private val preparedWrites = HashMap<Int, ByteArray>()

val namesReceived = MutableStateFlow(emptyList<String>())

@RequiresPermission(allOf = [PERMISSION_BLUETOOTH_CONNECT, PERMISSION_BLUETOOTH_ADVERTISE])
suspend fun startServer() = withContext(Dispatchers.IO) {
//If server already exists, we don't need to create one
Expand Down Expand Up @@ -133,17 +140,70 @@ class BluetoothCTFServer(private val context: Context) {
super.onCharacteristicReadRequest(device, requestId, offset, characteristic)
server?.sendResponse(device, requestId, BluetoothGatt.GATT_SUCCESS, offset, "HELLO".encodeToByteArray())
}

@RequiresPermission(PERMISSION_BLUETOOTH_CONNECT)
override fun onCharacteristicWriteRequest(
device: BluetoothDevice,
requestId: Int,
characteristic: BluetoothGattCharacteristic,
preparedWrite: Boolean,
responseNeeded: Boolean,
offset: Int,
value: ByteArray
) {
super.onCharacteristicWriteRequest(
device,
requestId,
characteristic,
preparedWrite,
responseNeeded,
offset,
value
)
super.onCharacteristicWriteRequest(device, requestId, characteristic, preparedWrite, responseNeeded, offset, value)

if(preparedWrite) {
val bytes = preparedWrites.getOrDefault(requestId, byteArrayOf())
preparedWrites[requestId] = bytes.plus(value)
}
else {
namesReceived.update { it.plus(String(value)) }
}

if(responseNeeded) {
server?.sendResponse(device, requestId, BluetoothGatt.GATT_SUCCESS, 0, byteArrayOf())
}
}

override fun onExecuteWrite(
device: BluetoothDevice?,
requestId: Int,
execute: Boolean
) {
super.onExecuteWrite(device, requestId, execute)
val bytes = preparedWrites.remove(requestId)
if (execute && bytes != null) {
namesReceived.update { it.plus(String(bytes)) }
}
}
})

val service = BluetoothGattService(serviceUuid, BluetoothGattService.SERVICE_TYPE_PRIMARY)

val characteristic = BluetoothGattCharacteristic(
characteristicUuid,
val passwordCharacteristic = BluetoothGattCharacteristic(
passwordCharUuid,
BluetoothGattCharacteristic.PROPERTY_READ,
BluetoothGattCharacteristic.PERMISSION_READ
)

service.addCharacteristic(characteristic)
val nameCharacteristic = BluetoothGattCharacteristic(
nameCharUuid,
BluetoothGattCharacteristic.PROPERTY_WRITE,
BluetoothGattCharacteristic.PERMISSION_WRITE
)

service.addCharacteristic(passwordCharacteristic)
service.addCharacteristic(nameCharacteristic)
server?.addService(service)
ctfService = service
}
Expand Down
23 changes: 22 additions & 1 deletion app/src/main/java/com/tdcolvin/bleserver/MainActivity.kt
View file
Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,8 @@ import androidx.activity.result.contract.ActivityResultContracts
import androidx.annotation.RequiresPermission
import androidx.compose.foundation.layout.Column
import androidx.compose.foundation.layout.fillMaxSize
import androidx.compose.foundation.lazy.LazyColumn
import androidx.compose.foundation.lazy.items
import androidx.compose.material3.Button
import androidx.compose.material3.MaterialTheme
import androidx.compose.material3.Surface
Expand Down Expand Up @@ -86,6 +88,7 @@ class MainActivity : ComponentActivity() {
onStartServer = { viewModel.startServer() },
onStopServer = { viewModel.stopServer() }
)
NamesReceived(names = uiState.namesReceived)
}
else {
val launcher = rememberLauncherForActivityResult(contract = ActivityResultContracts.RequestMultiplePermissions()) { granted ->
Expand Down Expand Up @@ -113,6 +116,15 @@ class MainActivity : ComponentActivity() {
}
}
}

@Composable
fun NamesReceived(names: List<String>) {
LazyColumn {
items(names) { name ->
Text(name)
}
}
}
}

class ServerViewModel(application: Application): AndroidViewModel(application) {
Expand All @@ -121,6 +133,14 @@ class ServerViewModel(application: Application): AndroidViewModel(application) {

private val server: BluetoothCTFServer = BluetoothCTFServer(application)

init {
viewModelScope.launch {
server.namesReceived.collect { names ->
_uiState.update { it.copy(namesReceived = names) }
}
}
}

@RequiresPermission(allOf = [PERMISSION_BLUETOOTH_ADVERTISE, PERMISSION_BLUETOOTH_CONNECT])
fun startServer() {
viewModelScope.launch {
Expand All @@ -138,5 +158,6 @@ class ServerViewModel(application: Application): AndroidViewModel(application) {
}

data class ServerUIState(
val serverRunning: Boolean = false
val serverRunning: Boolean = false,
val namesReceived: List<String> = emptyList()
)

0 comments on commit 05f2bb6

Please sign in to comment.