Update decryptMessage() API with the error message as an output parameter

java/android/OlmLibSdk/olm-sdk/src/androidTest/java/org/matrix/olm/OlmGroupSessionTest.java

@@ -151,8 +151,10 @@ public class OlmGroupSessionTest {
     @Test
     public void test10InboundDecryptMessage() {
         // test decrypted message
+        StringBuffer errorMsg = new StringBuffer();
         OlmInboundGroupSession.DecryptIndex index = new OlmInboundGroupSession.DecryptIndex();
-        mBobDecryptedMessage = mBobInboundGroupSession.decryptMessage(mAliceToBobMessage, index);
+
+        mBobDecryptedMessage = mBobInboundGroupSession.decryptMessage(mAliceToBobMessage, index, errorMsg);
         assertFalse(TextUtils.isEmpty(mBobDecryptedMessage));
         assertTrue(0==index.mIndex);
     }
@@ -437,11 +439,43 @@ public class OlmGroupSessionTest {
             assertTrue("Exception in test18TestBadCharacterCrashInDecrypt, Exception code=" + e.getExceptionCode(), false);
         }
 
+        StringBuffer errorMsg = new StringBuffer();
         OlmInboundGroupSession.DecryptIndex index = new OlmInboundGroupSession.DecryptIndex();
-        String decryptedMessage = bobInboundGroupSession.decryptMessage(msgToDecryptWithEmoji, index);
+
+        String decryptedMessage = bobInboundGroupSession.decryptMessage(msgToDecryptWithEmoji, index, errorMsg);
         assertNotNull(decryptedMessage);
         assertTrue(13==index.mIndex);
     }
 
+
+    /**
+     * Specific test to check an error message is returned by decryptMessage() API.<br>
+     * A corrupted encrypted message is passed, and a INVALID_BASE64 is
+     * espexted.
+    **/
+    @Test
+    public void test19TestErrorMessageReturnedInDecrypt() {
+        OlmInboundGroupSession bobInboundGroupSession=null;
+        final String EXPECTED_ERROR_MESSAGE= "INVALID_BASE64";
+        StringBuffer errorMsg = new StringBuffer();
+        OlmInboundGroupSession.DecryptIndex index = new OlmInboundGroupSession.DecryptIndex();
+
+        String sessionKeyRef    = "AgAAAAycZE6AekIctJWYxd2AWLOY15YmxZODm/WkgbpWkyycp6ytSp/R+wo84jRrzBNWmv6ySLTZ9R0EDOk9VI2eZyQ6Efdwyo1mAvrWvTkZl9yALPdkOIVHywyG65f1SNiLrnsln3hgsT1vUrISGyKtsljoUgQpr3JDPEhD0ilAi63QBjhnGCW252b+7nF+43rb6O6lwm93LaVwe2341Gdp6EkhTUvetALezEqDOtKN00wVqAbq0RQAnUJIowxHbMswg+FyoR1K1oCjnVEoF23O9xlAn5g1XtuBZP3moJlR2lwsBA";
+        String corruptedEncryptedMsg = "AwgANYTHINGf87ge45ge7gr*/rg5ganything4gr41rrgr4re55tanythingmcsXUkhDv0UePj922kgf+";
+
+        // valid INBOUND GROUP SESSION
+        try {
+            bobInboundGroupSession = new OlmInboundGroupSession(sessionKeyRef);
+        } catch (OlmException e) {
+            assertTrue("Exception in test19TestErrorMessageReturnedInDecrypt, Exception code=" + e.getExceptionCode(), false);
+        }
+
+        String decryptedMessage = bobInboundGroupSession.decryptMessage(corruptedEncryptedMsg, index, errorMsg);
+        assertTrue(0!=EXPECTED_ERROR_MESSAGE.length());
+        assertTrue(EXPECTED_ERROR_MESSAGE.equals(errorMsg.toString()));
+        assertTrue(null==decryptedMessage);
+        assertTrue(0==index.mIndex);
+    }
+
 }
 

java/android/OlmLibSdk/olm-sdk/src/main/java/org/matrix/olm/OlmInboundGroupSession.java

@@ -45,7 +45,7 @@ public class OlmInboundGroupSession extends CommonSerializeUtils implements Seri
     private transient long mNativeId;
 
     /**
-     * Wrapper class to be used in {@link #decryptMessage(String, DecryptIndex)}
+     * Wrapper class to be used in {@link #decryptMessage(String, DecryptIndex, StringBuffer)}
      */
     static public class DecryptIndex {
         /** decrypt index **/
@@ -142,16 +142,26 @@ public class OlmInboundGroupSession extends CommonSerializeUtils implements Seri
 
 
     /**
-     * Decrypt the message passed in parameter.
+     * Decrypt the message passed in parameter.<br>
+     * In case of error, null is returned and an error message description is provided in aErrorMsg.
      * @param aEncryptedMsg the message to be decrypted
      * @param aDecryptIndex_out decrypted message index
+     * @param aErrorMsg error message description
      * @return the decrypted message if operation succeed, null otherwise.
      */
-    public String decryptMessage(String aEncryptedMsg, DecryptIndex aDecryptIndex_out) {
+    public String decryptMessage(String aEncryptedMsg, DecryptIndex aDecryptIndex_out, StringBuffer aErrorMsg) {
-        String decryptedMessage = decryptMessageJni(aEncryptedMsg, aDecryptIndex_out, OlmManager.ENABLE_STRING_UTF8_SPECIFIC_CONVERSION);
+        String decryptedMessage = null;
+
+        // sanity check
+        if(null == aErrorMsg) {
+            Log.e(LOG_TAG,"## decryptMessage(): invalid parameter - aErrorMsg=null");
+        } else {
+            aErrorMsg.setLength(0);
+            decryptedMessage = decryptMessageJni(aEncryptedMsg, aDecryptIndex_out, aErrorMsg, OlmManager.ENABLE_STRING_UTF8_SPECIFIC_CONVERSION);
+        }
         return decryptedMessage;
     }
-    private native String decryptMessageJni(String aEncryptedMsg, DecryptIndex aDecryptIndex_out, boolean aIsUtf8ConversionRequired);
+    private native String decryptMessageJni(String aEncryptedMsg, DecryptIndex aDecryptIndex_out, StringBuffer aErrorMsg, boolean aIsUtf8ConversionRequired);
 
 
     /**

java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_inbound_group_session.cpp

@@ -180,7 +180,7 @@ JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(sessionIdentifierJni)(JNIEn
 }
 
 
-JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject thiz, jstring aEncryptedMsg, jobject aDecryptIndex, jboolean aIsUtf8ConversionRequired)
+JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject thiz, jstring aEncryptedMsg, jobject aDecryptIndex, jobject aErrorMsg, jboolean aIsUtf8ConversionRequired)
 {
     jstring decryptedMsgRetValue = 0;
     OlmInboundGroupSession *sessionPtr = NULL;
@@ -190,6 +190,10 @@ JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *
     uint32_t messageIndex = 0;
     jclass indexObjJClass = 0;
     jfieldID indexMsgFieldId;
+    jclass errorMsgJClass = 0;
+    jmethodID errorMsgMethodId = 0;
+    jstring errorJstring = 0;
+    const char *errorMsgPtr = NULL;
 
     LOGD("## decryptMessageJni(): inbound group session IN");
 
@@ -205,6 +209,18 @@ JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *
     {
         LOGE(" ## decryptMessageJni(): failure - invalid index object");
     }
+    else if(0 == aErrorMsg)
+    {
+        LOGE(" ## decryptMessageJni(): failure - invalid error object");
+    }
+    else if(0 == (errorMsgJClass = env->GetObjectClass(aErrorMsg)))
+    {
+        LOGE(" ## decryptMessageJni(): failure - unable to get error class");
+    }
+    else if(0 == (errorMsgMethodId = env->GetMethodID(errorMsgJClass, "append", "(Ljava/lang/String;)Ljava/lang/StringBuffer;")))
+    {
+        LOGE(" ## decryptMessageJni(): failure - unable to get error method ID");
+    }
     else if(0 == (encryptedMsgPtr = env->GetStringUTFChars(aEncryptedMsg, 0)))
     {
         LOGE(" ## decryptMessageJni(): failure - encrypted message JNI allocation OOM");
@@ -238,7 +254,12 @@ JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *
                                                                                encryptedMsgLength);
             if(maxPlainTextLength == olm_error())
             {
-                LOGE(" ## decryptMessageJni(): failure - olm_group_decrypt_max_plaintext_length Msg=%s",(const char *)olm_inbound_group_session_last_error(sessionPtr));
+                errorMsgPtr = olm_inbound_group_session_last_error(sessionPtr);
+                LOGE(" ## decryptMessageJni(): failure - olm_group_decrypt_max_plaintext_length Msg=%s",errorMsgPtr);
+                if(0 != (errorJstring = env->NewStringUTF(errorMsgPtr)))
+                {
+                    env->CallObjectMethod(aErrorMsg, errorMsgMethodId, errorJstring);
+                }
             }
             else
             {
@@ -257,7 +278,13 @@ JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *
                                                            &messageIndex);
                 if(plaintextLength == olm_error())
                 {
-                    LOGE(" ## decryptMessageJni(): failure - olm_group_decrypt Msg=%s",(const char *)olm_inbound_group_session_last_error(sessionPtr));
+                    errorMsgPtr = olm_inbound_group_session_last_error(sessionPtr);
+                    LOGE(" ## decryptMessageJni(): failure - olm_group_decrypt Msg=%s",errorMsgPtr);
+
+                    if(0 != (errorJstring = env->NewStringUTF(errorMsgPtr)))
+                    {
+                        env->CallObjectMethod(aErrorMsg, errorMsgMethodId, errorJstring);
+                    }
                 }
                 else
                 {

java/android/OlmLibSdk/olm-sdk/src/main/jni/olm_inbound_group_session.h

@@ -33,7 +33,7 @@ JNIEXPORT jlong OLM_INBOUND_GROUP_SESSION_FUNC_DEF(createNewSessionJni)(JNIEnv *
 
 JNIEXPORT jint OLM_INBOUND_GROUP_SESSION_FUNC_DEF(initInboundGroupSessionWithSessionKeyJni)(JNIEnv *env, jobject thiz, jstring aSessionKey);
 JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(sessionIdentifierJni)(JNIEnv *env, jobject thiz);
-JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject thiz, jstring aEncryptedMsg, jobject aDecryptIndex, jboolean aIsUtf8ConversionRequired);
+JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(decryptMessageJni)(JNIEnv *env, jobject thiz, jstring aEncryptedMsg, jobject aDecryptIndex, jobject aErrorMsg, jboolean aIsUtf8ConversionRequired);
 
 // serialization
 JNIEXPORT jstring OLM_INBOUND_GROUP_SESSION_FUNC_DEF(serializeDataWithKeyJni)(JNIEnv *env, jobject thiz, jstring aKey, jobject aErrorMsg);