Honor arrayOffset() in ByteBuffer read/write

Author: JeremiahM37

native/com_wolfssl_WolfSSL.c

@@ -67,6 +67,7 @@ jmethodID g_bufferPositionMethodId = NULL;
 jmethodID g_bufferLimitMethodId = NULL;
 jmethodID g_bufferHasArrayMethodId = NULL;
 jmethodID g_bufferArrayMethodId = NULL;
+jmethodID g_bufferArrayOffsetMethodId = NULL;
 jmethodID g_bufferSetPositionMethodId = NULL;
 jmethodID g_verifyCallbackMethodId = NULL;
 
@@ -185,6 +186,12 @@ JNIEXPORT jint JNICALL JNI_OnLoad(JavaVM* vm, void* reserved)
         return JNI_ERR;
     }
 
+    g_bufferArrayOffsetMethodId = (*env)->GetMethodID(env, byteBufferClass,
+        "arrayOffset", "()I");
+    if (g_bufferArrayOffsetMethodId == NULL) {
+        return JNI_ERR;
+    }
+
     g_bufferSetPositionMethodId = (*env)->GetMethodID(env, byteBufferClass,
         "position", "(I)Ljava/nio/Buffer;");
     if (g_bufferSetPositionMethodId == NULL) {
@@ -236,6 +243,7 @@ JNIEXPORT void JNICALL JNI_OnUnload(JavaVM* vm, void* reserved)
     g_bufferLimitMethodId = NULL;
     g_bufferHasArrayMethodId = NULL;
     g_bufferArrayMethodId = NULL;
+    g_bufferArrayOffsetMethodId = NULL;
     g_bufferSetPositionMethodId = NULL;
     g_verifyCallbackMethodId = NULL;
 }

native/com_wolfssl_WolfSSLSession.c

@@ -1303,6 +1303,7 @@ JNIEXPORT jint JNICALL Java_com_wolfssl_WolfSSLSession_write__JLjava_nio_ByteBuf
     int ret = BAD_FUNC_ARG;
     int maxInputSz;
     int inSz = length;
+    int arrayOffset = 0;
     byte* data = NULL;
     WOLFSSL* ssl = (WOLFSSL*)(uintptr_t)sslPtr;
     jbyteArray bufArr = NULL;
@@ -1333,6 +1334,15 @@ JNIEXPORT jint JNICALL Java_com_wolfssl_WolfSSLSession_write__JLjava_nio_ByteBuf
                 return SSL_FAILURE;
             }
 
+            /* Honor arrayOffset() for sliced/duplicated array-backed
+             * ByteBuffers, where logical position 0 maps to backing
+             * array index arrayOffset() */
+            arrayOffset = (int)(*jenv)->CallIntMethod(jenv, buf,
+                g_bufferArrayOffsetMethodId);
+            if ((*jenv)->ExceptionCheck(jenv)) {
+                return SSL_FAILURE;
+            }
+
             /* Get array elements */
             data = (byte *)(*jenv)->GetByteArrayElements(jenv, bufArr, NULL);
             if (data == NULL) {
@@ -1356,8 +1366,8 @@ JNIEXPORT jint JNICALL Java_com_wolfssl_WolfSSLSession_write__JLjava_nio_ByteBuf
             }
         }
 
-        ret = SSLWriteNonblockingWithSelectPoll(ssl, data + position,
-            (int)inSz, (int)timeout);
+        ret = SSLWriteNonblockingWithSelectPoll(ssl,
+            data + arrayOffset + position, (int)inSz, (int)timeout);
 
         /* release memory if using array mode */
         if (hasArray) {
@@ -1530,6 +1540,7 @@ JNIEXPORT jint JNICALL Java_com_wolfssl_WolfSSLSession_read__JLjava_nio_ByteBuff
     int size = 0;
     int maxOutputSz;
     int outSz = length;
+    int arrayOffset = 0;
     byte* data = NULL;
     WOLFSSL* ssl = (WOLFSSL*)(uintptr_t)sslPtr;
     jbyteArray bufArr = NULL;
@@ -1560,6 +1571,15 @@ JNIEXPORT jint JNICALL Java_com_wolfssl_WolfSSLSession_read__JLjava_nio_ByteBuff
                 return SSL_FAILURE;
             }
 
+            /* Honor arrayOffset() for sliced/duplicated array-backed
+             * ByteBuffers, where logical position 0 maps to backing
+             * array index arrayOffset() */
+            arrayOffset = (int)(*jenv)->CallIntMethod(jenv, buf,
+                g_bufferArrayOffsetMethodId);
+            if ((*jenv)->ExceptionCheck(jenv)) {
+                return SSL_FAILURE;
+            }
+
             /* Get array elements */
             data = (byte *)(*jenv)->GetByteArrayElements(jenv, bufArr, NULL);
             if (data == NULL) {
@@ -1583,8 +1603,8 @@ JNIEXPORT jint JNICALL Java_com_wolfssl_WolfSSLSession_read__JLjava_nio_ByteBuff
             }
         }
 
-        size = SSLReadNonblockingWithSelectPoll(ssl, data + position,
-            outSz, (int)timeout);
+        size = SSLReadNonblockingWithSelectPoll(ssl,
+            data + arrayOffset + position, outSz, (int)timeout);
 
         /* Release array elements if using array-backed buffer.
          * Note: DirectByteBuffer doesn't need releasing data */

native/com_wolfssl_globals.h

@@ -42,6 +42,7 @@ extern jmethodID g_bufferPositionMethodId;         /* ByteBuffer.position() */
 extern jmethodID g_bufferLimitMethodId;            /* ByteBuffer.limit() */
 extern jmethodID g_bufferHasArrayMethodId;         /* ByteBuffer.hasArray() */
 extern jmethodID g_bufferArrayMethodId;            /* ByteBuffer.array() */
+extern jmethodID g_bufferArrayOffsetMethodId;      /* ByteBuffer.arrayOffset() */
 extern jmethodID g_bufferSetPositionMethodId;      /* ByteBuffer.position(int) */
 extern jmethodID g_verifyCallbackMethodId;         /* WolfSSLVerifyCallback.verifyCallback */