From 99eb7896be17cc688f001886469fb109b0575cad Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Mon, 18 May 2020 14:32:31 -0600 Subject: device: rework padding calculation and don't shadow paddedSize Reported-by: Jayakumar S Signed-off-by: Jason A. Donenfeld --- device/send.go | 32 +++++++++++++++++--------------- 1 file changed, 17 insertions(+), 15 deletions(-) (limited to 'device/send.go') diff --git a/device/send.go b/device/send.go index 9be1233..c0bdba3 100644 --- a/device/send.go +++ b/device/send.go @@ -448,6 +448,21 @@ func (peer *Peer) RoutineNonce() { } } +func calculatePaddingSize(packetSize, mtu int) int { + lastUnit := packetSize + if mtu == 0 { + return ((lastUnit + PaddingMultiple - 1) & ^(PaddingMultiple - 1)) - lastUnit + } + if lastUnit > mtu { + lastUnit %= mtu + } + paddedSize := ((lastUnit + PaddingMultiple - 1) & ^(PaddingMultiple - 1)) + if paddedSize > mtu { + paddedSize = mtu + } + return paddedSize - lastUnit +} + /* Encrypts the elements in the queue * and marks them for sequential consumption (by releasing the mutex) * @@ -514,21 +529,8 @@ func (device *Device) RoutineEncryption() { // pad content to multiple of 16 - mtu := int(atomic.LoadInt32(&device.tun.mtu)) - var paddedSize int - if mtu == 0 { - paddedSize = (len(elem.packet) + PaddingMultiple - 1) & ^(PaddingMultiple - 1) - } else { - lastUnit := len(elem.packet) - if lastUnit > mtu { - lastUnit %= mtu - } - paddedSize := (lastUnit + PaddingMultiple - 1) & ^(PaddingMultiple - 1) - if paddedSize > mtu { - paddedSize = mtu - } - } - for i := len(elem.packet); i < paddedSize; i++ { + paddingSize := calculatePaddingSize(len(elem.packet), int(atomic.LoadInt32(&device.tun.mtu))) + for i := 0; i < paddingSize; i++ { elem.packet = append(elem.packet, 0) } -- cgit v1.2.3-59-g8ed1b