From: Josh Bleecher Snyder Date: Tue, 15 Dec 2020 02:30:13 +0000 (-0800) Subject: device: simplify copying counter to nonce X-Git-Tag: 0.0.20210212~127 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=41cd68416c8f35e80523fb3102b6a9c9982446c4;p=thirdparty%2Fwireguard-go.git device: simplify copying counter to nonce Since we already have it packed into a uint64 in a known byte order, write it back out again the same byte order instead of copying byte by byte. This should also generate more efficient code, because the compiler can do a single uint64 write, instead of eight bounds checks and eight byte writes. Due to a missed optimization, it actually generates a mishmash of smaller writes: 1 byte, 4 bytes, 2 bytes, 1 byte. This is https://golang.org/issue/41663. The code is still better than before, and will get better yet once that compiler bug gets fixed. Signed-off-by: Josh Bleecher Snyder --- diff --git a/device/receive.go b/device/receive.go index 839b735..852bd89 100644 --- a/device/receive.go +++ b/device/receive.go @@ -268,22 +268,12 @@ func (device *Device) RoutineDecryption() { counter := elem.packet[MessageTransportOffsetCounter:MessageTransportOffsetContent] content := elem.packet[MessageTransportOffsetContent:] - // expand nonce - - nonce[0x4] = counter[0x0] - nonce[0x5] = counter[0x1] - nonce[0x6] = counter[0x2] - nonce[0x7] = counter[0x3] - - nonce[0x8] = counter[0x4] - nonce[0x9] = counter[0x5] - nonce[0xa] = counter[0x6] - nonce[0xb] = counter[0x7] - // decrypt and release to consumer var err error elem.counter = binary.LittleEndian.Uint64(counter) + // copy counter to nonce + binary.LittleEndian.PutUint64(nonce[0x4:0xc], elem.counter) elem.packet, err = elem.keypair.receive.Open( content[:0], nonce[:],