commit 3661e3e2bc0bfbf5796af625aec5a1f0181b8f1b
parent 9d8c7f0f1f80085e2faaa65e1cad30847575fb11
Author: Iván Ávalos <avalos@disroot.org>
Date: Tue, 18 Aug 2026 16:23:58 +0200
[common] keep the NFC payload alive across service restarts
It was handed to the service by broadcast right after startService(), so it was
dropped whenever the service was not up yet, and lost again every time the
system restarted the sticky service. Hold it per process instead.
Diffstat:
1 file changed, 29 insertions(+), 93 deletions(-)
diff --git a/taler-kotlin-android/src/main/java/net/taler/lib/android/TalerNfcService.kt b/taler-kotlin-android/src/main/java/net/taler/lib/android/TalerNfcService.kt
@@ -17,11 +17,9 @@
package net.taler.lib.android
import android.app.Activity
-import android.content.BroadcastReceiver
import android.content.ComponentName
import android.content.Context
import android.content.Intent
-import android.content.IntentFilter
import android.nfc.NdefMessage
import android.nfc.NdefRecord
import android.nfc.NfcAdapter.getDefaultAdapter
@@ -29,51 +27,12 @@ import android.nfc.cardemulation.CardEmulation
import android.nfc.cardemulation.HostApduService
import android.os.Bundle
import android.util.Log
-import androidx.core.content.ContextCompat
-import androidx.core.content.IntentCompat
import java.math.BigInteger
+import java.util.concurrent.atomic.AtomicReference
class TalerNfcService : HostApduService() {
- private var ndefMessage: NdefMessage? = null
-
- private val ndefUriBytes: ByteArray?
- get() = ndefMessage?.toByteArray()
-
- private val ndefUriLen: ByteArray?
- get() = ndefUriBytes?.size?.toLong()?.let { size ->
- fillByteArrayToFixedDimension(
- BigInteger.valueOf(size).toByteArray(),
- 2
- )
- }
-
private var readCapabilityContainerCheck = false
- private val broadcastReceiver = object: BroadcastReceiver() {
- override fun onReceive(context: Context?, intent: Intent?) {
- when (intent?.action) {
- SET_URI_INTENT -> intent.getStringExtra("uri")?.let { uri ->
- Log.d(TAG, "onReceive(SET_URI_INTENT) | URI: $uri")
- ndefMessage = NdefMessage(createUriRecord(uri))
- }
-
- SET_NDEF_INTENT -> IntentCompat.getParcelableExtra(
- intent,
- "ndef",
- NdefMessage::class.java,
- )?.let { ndef ->
- Log.d(TAG, "onReceive(SET_NDEF_INTENT) | NDEF: $ndef")
- ndefMessage = ndef
- }
-
- CLEAR_NDEF_INTENT -> {
- Log.d(TAG, "onReceive(CLEAR_NDEF_INTENT)")
- ndefMessage = null
- }
- }
- }
- }
-
override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int {
return START_STICKY
}
@@ -90,12 +49,19 @@ class TalerNfcService : HostApduService() {
return A_ERROR
}
- val message = ndefMessage
+ val message = ndefMessage.get()
if (message == null) {
Log.d(TAG, "processCommandApi() no data to write")
return A_ERROR
}
+ // snapshot: the payload can be replaced between APDUs of one exchange
+ val ndefBytes = message.toByteArray()
+ val ndefLen = fillByteArrayToFixedDimension(
+ BigInteger.valueOf(ndefBytes.size.toLong()).toByteArray(),
+ 2,
+ )
+
//
// The following flow is based on Appendix E "Example of Mapping Version 2.0 Command Flow"
// in the NFC Forum specification
@@ -138,9 +104,9 @@ class TalerNfcService : HostApduService() {
if (NDEF_READ_BINARY_NLEN.contentEquals(commandApdu)) {
// Build our response
- val response = ByteArray(ndefUriLen!!.size + A_OKAY.size)
- System.arraycopy(ndefUriLen!!, 0, response, 0, ndefUriLen!!.size)
- System.arraycopy(A_OKAY, 0, response, ndefUriLen!!.size, A_OKAY.size)
+ val response = ByteArray(ndefLen.size + A_OKAY.size)
+ System.arraycopy(ndefLen, 0, response, 0, ndefLen.size)
+ System.arraycopy(A_OKAY, 0, response, ndefLen.size, A_OKAY.size)
Log.d(TAG, "NDEF_READ_BINARY_NLEN triggered. Our Response: " + response.toHex())
@@ -152,15 +118,9 @@ class TalerNfcService : HostApduService() {
val offset = commandApdu.sliceArray(2..3).toHex().toInt(16)
val length = commandApdu.sliceArray(4..4).toHex().toInt(16)
- val fullResponse = ByteArray(ndefUriLen!!.size + ndefUriBytes!!.size)
- System.arraycopy(ndefUriLen!!, 0, fullResponse, 0, ndefUriLen!!.size)
- System.arraycopy(
- ndefUriBytes!!,
- 0,
- fullResponse,
- ndefUriLen!!.size,
- ndefUriBytes!!.size,
- )
+ val fullResponse = ByteArray(ndefLen.size + ndefBytes.size)
+ System.arraycopy(ndefLen, 0, fullResponse, 0, ndefLen.size)
+ System.arraycopy(ndefBytes, 0, fullResponse, ndefLen.size, ndefBytes.size)
Log.d(TAG, "NDEF_READ_BINARY triggered. Full data: " + fullResponse.toHex())
Log.d(TAG, "READ_BINARY - OFFSET: $offset - LEN: $length")
@@ -205,8 +165,6 @@ class TalerNfcService : HostApduService() {
return result.toString()
}
- private fun createUriRecord(uri: String) = NdefRecord.createUri(uri)
-
private fun fillByteArrayToFixedDimension(array: ByteArray, fixedSize: Int): ByteArray {
if (array.size == fixedSize) {
return array
@@ -219,33 +177,16 @@ class TalerNfcService : HostApduService() {
return fillByteArrayToFixedDimension(filledArray, fixedSize)
}
- override fun onCreate() {
- super.onCreate()
- Log.d(TAG, "onCreate() service running")
- val intentFilter = IntentFilter()
- intentFilter.addAction(SET_URI_INTENT)
- intentFilter.addAction(SET_NDEF_INTENT)
- intentFilter.addAction(CLEAR_NDEF_INTENT)
- ContextCompat.registerReceiver(
- this@TalerNfcService,
- broadcastReceiver,
- intentFilter,
- ContextCompat.RECEIVER_NOT_EXPORTED,
- )
- }
-
- override fun onDestroy() {
- super.onDestroy()
- Log.d(TAG, "onDestroy() NFC service")
- unregisterReceiver(broadcastReceiver)
- ndefMessage = null
- }
-
companion object {
private const val TAG = "taler-wallet-hce"
- const val SET_URI_INTENT = "taler-wallet-set-url"
- const val SET_NDEF_INTENT = "taler-wallet-set-ndef"
- const val CLEAR_NDEF_INTENT = "taler-wallet-clear-ndef"
+ /**
+ * The payload to serve, held per process rather than per service instance.
+ * The service is created asynchronously and can be restarted by the system at
+ * any time, so anything stored on the instance is lost or set too late.
+ */
+ private val ndefMessage = AtomicReference<NdefMessage?>(null)
+
+ private fun createUriRecord(uri: String) = NdefRecord.createUri(uri)
private val APDU_SELECT = byteArrayOf(
0x00.toByte(), // CLA - Class - Class of instruction
@@ -367,25 +308,20 @@ class TalerNfcService : HostApduService() {
fun setUri(activity: Activity, uri: String) {
if (!hasNfc(activity)) return
- val intent = Intent(SET_URI_INTENT)
- intent.setPackage(activity.packageName)
- intent.putExtra("uri", uri)
- activity.sendBroadcast(intent)
+ Log.d(TAG, "setUri() | URI: $uri")
+ ndefMessage.set(NdefMessage(createUriRecord(uri)))
}
fun setNdefPayload(activity: Activity, ndef: NdefMessage) {
if (!hasNfc(activity)) return
- val intent = Intent(SET_NDEF_INTENT)
- intent.setPackage(activity.packageName)
- intent.putExtra("ndef", ndef)
- activity.sendBroadcast(intent)
+ Log.d(TAG, "setNdefPayload() | NDEF: $ndef")
+ ndefMessage.set(ndef)
}
fun clearNdefPayload(activity: Activity) {
if (!hasNfc(activity)) return
- val intent = Intent(CLEAR_NDEF_INTENT)
- intent.setPackage(activity.packageName)
- activity.sendBroadcast(intent)
+ Log.d(TAG, "clearNdefPayload()")
+ ndefMessage.set(null)
}
}
}
\ No newline at end of file
