Bug 1834: FTP file uploads are interrupting with TLS 1.3

https://winscp.net/tracker/1834

Source commit: ed1a795deeb85606fa2ebb3cb265a407b5abfbef

source/filezilla/AsyncSslSocketLayer.cpp

@@ -983,12 +983,12 @@ BOOL CAsyncSslSocketLayer::ShutDown(int nHow /*=sends*/)
     }
 
     int res = SSL_shutdown(m_ssl);
-    if (res != -1)
+    if (res == 0)
+    {
+      res = SSL_shutdown(m_ssl);
+    }
+    if (res >= 0)
     {
-      if (!res)
-      {
-        SSL_shutdown(m_ssl);
-      }
       if (ShutDownComplete())
         return ShutDownNext();
       else

source/filezilla/TransferSocket.cpp

@@ -785,8 +785,12 @@ void CTransferSocket::OnSend(int nErrorCode)
           CloseOnShutDownOrError(CSMODE_TRANSFERERROR);
           return;
         }
-        else if (!pos && numread < (currentBufferSize-m_bufferpos) && m_bufferpos != currentBufferSize)
+        else if (!pos && // all data in buffer were sent
+                 numread < (currentBufferSize-m_bufferpos) && // was read less then wanted (eof reached?)
+                 m_bufferpos != currentBufferSize) // and it's not because the buffer is full?
         {
+          // With TLS 1.3 we can get back
+          m_bufferpos = 0;
           CloseOnShutDownOrError(0);
           return;
         }