refactor: Channel validity, and reconnection

* ApduInterfaces also need a concept of validity based on the underlying
  APDU channel. For example, OMAPI depends on SEService being still
  connected.
* We then rely on this validity to wait for reconnection; we do not need
  to manually remove all channels under a slot because the rest will be
  invalid anyway, and the next attempt at connection will lazily
  recreate the channel.
* We had to manage channels manually before during reconnect because
  `valid` may result in SIGSEGV's when the underlying APDU channel has
  become invalid. This is avoided by the validity concept added to APDU
  channels.

app-common/src/main/java/im/angry/openeuicc/core/DefaultEuiccChannelManager.kt

@@ -103,28 +103,35 @@ open class DefaultEuiccChannelManager(
             findAllEuiccChannelsByPhysicalSlot(physicalSlotId)
         }
 
+    override suspend fun findEuiccChannelByPort(physicalSlotId: Int, portId: Int): EuiccChannel? =
+        withContext(Dispatchers.IO) {
+            uiccCards.find { it.physicalSlotIndex == physicalSlotId }?.let { card ->
+                card.ports.find { it.portIndex == portId }?.let { tryOpenEuiccChannel(it) }
+            }
+        }
+
     override fun findEuiccChannelByPortBlocking(physicalSlotId: Int, portId: Int): EuiccChannel? =
         runBlocking {
-            withContext(Dispatchers.IO) {
-                uiccCards.find { it.physicalSlotIndex == physicalSlotId }?.let { card ->
-                    card.ports.find { it.portIndex == portId }?.let { tryOpenEuiccChannel(it) }
-                }
-            }
+            findEuiccChannelByPort(physicalSlotId, portId)
         }
 
-    override suspend fun tryReconnectSlot(physicalSlotId: Int, timeoutMillis: Long) {
-        invalidateByPhysicalSlot(physicalSlotId)
+    override suspend fun waitForReconnect(physicalSlotId: Int, portId: Int, timeoutMillis: Long) {
+        // If there is already a valid channel, we close it proactively
+        // Sometimes the current channel can linger on for a bit even after it should have become invalid
+        channels.find { it.slotId == physicalSlotId && it.portId == portId }?.apply {
+            if (valid) close()
+        }
 
         withTimeout(timeoutMillis) {
             while (true) {
                 try {
-                    findAllEuiccChannelsByPhysicalSlot(physicalSlotId)!!.forEach {
-                        check(it.valid) { "Invalid channel" }
-                    }
+                    // tryOpenEuiccChannel() will automatically dispose of invalid channels
+                    // and recreate when needed
+                    val channel = findEuiccChannelByPortBlocking(physicalSlotId, portId)!!
+                    check(channel.valid) { "Invalid channel" }
                     break
                 } catch (e: Exception) {
-                    Log.d(TAG, "Slot reconnect failure, retrying in 1000 ms")
-                    invalidateByPhysicalSlot(physicalSlotId)
+                    Log.d(TAG, "Slot $physicalSlotId port $portId reconnect failure, retrying in 1000 ms")
                 }
                 delay(1000)
             }
@@ -157,12 +164,4 @@ open class DefaultEuiccChannelManager(
         channels.clear()
         euiccChannelFactory.cleanup()
     }
-
-    private fun invalidateByPhysicalSlot(physicalSlotId: Int) {
-        val toRemove = channels.filter { it.valid && it.slotId == physicalSlotId }
-        for (channel in toRemove) {
-            channel.close()
-            channels.remove(channel)
-        }
-    }
 }

app-common/src/main/java/im/angry/openeuicc/core/EuiccChannelManager.kt

@@ -9,13 +9,11 @@ interface EuiccChannelManager {
     suspend fun enumerateEuiccChannels()
 
     /**
-     * Reconnect ALL EuiccChannels belonging to a physical slot
-     * Throws TimeoutCancellationException when timed out
-     * If this operation times out, none of the channels belonging to the slot will be
-     * guaranteed to be consistent. The caller should either call invalidate()
-     * and try again later, or the application should simply exit entirely.
+     * Wait for a slot + port to reconnect (i.e. become valid again)
+     * If the port is currently valid, this function will return immediately.
+     * On timeout, the caller can decide to either try again later, or alert the user with an error
      */
-    suspend fun tryReconnectSlot(physicalSlotId: Int, timeoutMillis: Long = 1000)
+    suspend fun waitForReconnect(physicalSlotId: Int, portId: Int, timeoutMillis: Long = 1000)
 
     /**
      * Returns the EuiccChannel corresponding to a **logical** slot
@@ -39,6 +37,7 @@ interface EuiccChannelManager {
     /**
      * Returns the EuiccChannel corresponding to a **physical** slot and a port ID
      */
+    suspend fun findEuiccChannelByPort(physicalSlotId: Int, portId: Int): EuiccChannel?
     fun findEuiccChannelByPortBlocking(physicalSlotId: Int, portId: Int): EuiccChannel?
 
     /**

app-common/src/main/java/im/angry/openeuicc/core/OmapiApduInterface.kt

@@ -13,6 +13,9 @@ class OmapiApduInterface(
     private lateinit var session: Session
     private lateinit var lastChannel: Channel
 
+    override val valid: Boolean
+        get() = service.isConnected && (this::session.isInitialized && !session.isClosed)
+
     override fun connect() {
         session = service.getUiccReaderCompat(port.logicalSlotIndex + 1).openSession()
     }

app-common/src/main/java/im/angry/openeuicc/ui/EuiccManagementFragment.kt

@@ -146,7 +146,7 @@ open class EuiccManagementFragment : Fragment(), EuiccProfilesChangedListener,
                 }
 
                 try {
-                    euiccChannelManager.tryReconnectSlot(slotId, timeoutMillis = 30 * 1000)
+                    euiccChannelManager.waitForReconnect(slotId, portId, timeoutMillis = 30 * 1000)
                 } catch (e: TimeoutCancellationException) {
                     withContext(Dispatchers.Main) {
                         // Timed out waiting for SIM to come back online, we can no longer assume that the LPA is still valid

app/src/main/java/im/angry/openeuicc/core/TelephonyManagerApduInterface.kt

@@ -11,6 +11,11 @@ class TelephonyManagerApduInterface(
 ): ApduInterface {
     private var lastChannel: Int = -1
 
+    override val valid: Boolean
+        // TelephonyManager channels will never become truly "invalid",
+        // just that transactions might return errors or nonsense
+        get() = lastChannel != -1
+
     override fun connect() {
         // Do nothing
     }

libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/ApduInterface.kt

@@ -9,4 +9,11 @@ interface ApduInterface {
     fun logicalChannelOpen(aid: ByteArray): Int
     fun logicalChannelClose(handle: Int)
     fun transmit(tx: ByteArray): ByteArray
+
+    /**
+     * Is this APDU connection still valid?
+     * Note that even if this returns true, the underlying connection might be broken anyway;
+     * callers should further check with the LPA to fully determine the validity of a channel
+     */
+    val valid: Boolean
 }

libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/LocalProfileAssistant.kt

@@ -2,15 +2,6 @@ package net.typeblog.lpac_jni
 
 interface LocalProfileAssistant {
     val valid: Boolean
-        get() = try {
-            // If we can read both eID and profiles properly, we are likely looking at
-            // a valid LocalProfileAssistant
-            eID
-            profiles
-            true
-        } catch (e: Exception) {
-            false
-        }
     val profiles: List<LocalProfileInfo>
     val notifications: List<LocalProfileNotification>
     val eID: String

libs/lpac-jni/src/main/java/net/typeblog/lpac_jni/impl/LocalProfileAssistantImpl.kt

@@ -11,13 +11,14 @@ import net.typeblog.lpac_jni.LocalProfileNotification
 import net.typeblog.lpac_jni.ProfileDownloadCallback
 
 class LocalProfileAssistantImpl(
-    apduInterface: ApduInterface,
+    private val apduInterface: ApduInterface,
     httpInterface: HttpInterface
 ): LocalProfileAssistant {
     companion object {
         private const val TAG = "LocalProfileAssistantImpl"
     }
 
+    private var finalized = false
     private var contextHandle: Long = LpacJni.createContext(apduInterface, httpInterface)
     init {
         if (LpacJni.euiccInit(contextHandle) < 0) {
@@ -28,6 +29,17 @@ class LocalProfileAssistantImpl(
         httpInterface.usePublicKeyIds(pkids)
     }
 
+    override val valid: Boolean
+        get() = !finalized && apduInterface.valid && try {
+            // If we can read both eID and profiles properly, we are likely looking at
+            // a valid LocalProfileAssistant
+            eID
+            profiles
+            true
+        } catch (e: Exception) {
+            false
+        }
+
     override val profiles: List<LocalProfileInfo>
         get() = LpacJni.es10cGetProfilesInfo(contextHandle)!!.asList()
 
@@ -71,8 +83,12 @@ class LocalProfileAssistantImpl(
         return LpacJni.es10cSetNickname(contextHandle, iccid, nickname) == 0
     }
 
+    @Synchronized
     override fun close() {
-        LpacJni.euiccFini(contextHandle)
-        LpacJni.destroyContext(contextHandle)
+        if (!finalized) {
+            LpacJni.euiccFini(contextHandle)
+            LpacJni.destroyContext(contextHandle)
+            finalized = true
+        }
     }
 }