Mutualizing decryption of event

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/EventDecryptor.kt

@@ -24,10 +24,12 @@ import kotlinx.coroutines.withContext
 import org.matrix.android.sdk.api.MatrixCallback
 import org.matrix.android.sdk.api.MatrixCoroutineDispatchers
 import org.matrix.android.sdk.api.crypto.MXCRYPTO_ALGORITHM_OLM
+import org.matrix.android.sdk.api.extensions.tryOrNull
 import org.matrix.android.sdk.api.logger.LoggerTag
 import org.matrix.android.sdk.api.session.crypto.MXCryptoError
 import org.matrix.android.sdk.api.session.crypto.model.MXEventDecryptionResult
 import org.matrix.android.sdk.api.session.crypto.model.MXUsersDevicesMap
+import org.matrix.android.sdk.api.session.crypto.model.OlmDecryptionResult
 import org.matrix.android.sdk.api.session.events.model.Event
 import org.matrix.android.sdk.api.session.events.model.EventType
 import org.matrix.android.sdk.api.session.events.model.content.OlmEventContent
@@ -85,6 +87,27 @@ internal class EventDecryptor @Inject constructor(
         return internalDecryptEvent(event, timeline)
     }
 
+    /**
+     * Decrypt an event and save the result in the given event.
+     *
+     * @param event the raw event.
+     * @param timeline the id of the timeline where the event is decrypted. It is used to prevent replay attack.
+     */
+    suspend fun decryptEventAndSaveResult(event: Event, timeline: String) {
+        tryOrNull(message = "Unable to decrypt the event") {
+            decryptEvent(event, timeline)
+        }
+                ?.let { result ->
+                    event.mxDecryptionResult = OlmDecryptionResult(
+                            payload = result.clearEvent,
+                            senderKey = result.senderCurve25519Key,
+                            keysClaimed = result.claimedEd25519Key?.let { mapOf("ed25519" to it) },
+                            forwardingCurve25519KeyChain = result.forwardingCurve25519KeyChain,
+                            isSafe = result.isSafe
+                    )
+                }
+    }
+
     /**
      * Decrypt an event asynchronously.
      *

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/relation/poll/FetchPollResponseEventsTask.kt

@@ -17,8 +17,6 @@
 package org.matrix.android.sdk.internal.session.room.relation.poll
 
 import com.zhuinden.monarchy.Monarchy
-import org.matrix.android.sdk.api.extensions.tryOrNull
-import org.matrix.android.sdk.api.session.crypto.model.OlmDecryptionResult
 import org.matrix.android.sdk.api.session.events.model.Event
 import org.matrix.android.sdk.api.session.events.model.RelationType
 import org.matrix.android.sdk.api.session.events.model.isPollResponse
@@ -107,20 +105,8 @@ internal class DefaultFetchPollResponseEventsTask @Inject constructor(
     }
 
     private suspend fun decryptEventIfNeeded(event: Event): Event {
-        // TODO move into a reusable task
         if (event.isEncrypted()) {
-            tryOrNull(message = "Unable to decrypt the event") {
+            eventDecryptor.decryptEventAndSaveResult(event, timeline = "")
-                eventDecryptor.decryptEvent(event, "")
-            }
-                    ?.let { result ->
-                        event.mxDecryptionResult = OlmDecryptionResult(
-                                payload = result.clearEvent,
-                                senderKey = result.senderCurve25519Key,
-                                keysClaimed = result.claimedEd25519Key?.let { mapOf("ed25519" to it) },
-                                forwardingCurve25519KeyChain = result.forwardingCurve25519KeyChain,
-                                isSafe = result.isSafe
-                        )
-                    }
         }
 
         event.ageLocalTs = clock.epochMillis() - (event.unsignedData?.age ?: 0)

matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/session/room/timeline/GetEventTask.kt

@@ -48,18 +48,7 @@ internal class DefaultGetEventTask @Inject constructor(
 
         // Try to decrypt the Event
         if (event.isEncrypted()) {
-            tryOrNull(message = "Unable to decrypt the event") {
+            eventDecryptor.decryptEventAndSaveResult(event, timeline = "")
-                eventDecryptor.decryptEvent(event, "")
-            }
-                    ?.let { result ->
-                        event.mxDecryptionResult = OlmDecryptionResult(
-                                payload = result.clearEvent,
-                                senderKey = result.senderCurve25519Key,
-                                keysClaimed = result.claimedEd25519Key?.let { mapOf("ed25519" to it) },
-                                forwardingCurve25519KeyChain = result.forwardingCurve25519KeyChain,
-                                isSafe = result.isSafe
-                        )
-                    }
         }
 
         event.ageLocalTs = clock.epochMillis() - (event.unsignedData?.age ?: 0)