snow/wireguard-go
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device: timers: use pre-seeded per-thread unlocked fastrandn for jitter

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Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Jason A. Donenfeld 2021-10-28 13:47:50 +02:00
parent 60683d7361
commit eb6302c7eb
1 changed files with 5 additions and 10 deletions
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15
device/timers.go
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@ -8,19 +8,14 @@
package device
import (
"crypto/rand"
unsafeRand "math/rand"
"sync"
"sync/atomic"
"time"
"unsafe"
_ "unsafe"
)
func init() {
var seed int64
rand.Read(unsafe.Slice((*byte)(unsafe.Pointer(&seed)), unsafe.Sizeof(seed)))
unsafeRand.Seed(seed)
}
//go:linkname fastrandn runtime.fastrandn
func fastrandn(n uint32) uint32
// A Timer manages time-based aspects of the WireGuard protocol.
// Timer roughly copies the interface of the Linux kernel's struct timer_list.
@ -152,7 +147,7 @@ func expiredPersistentKeepalive(peer *Peer) {
/* Should be called after an authenticated data packet is sent. */
func (peer *Peer) timersDataSent() {
if peer.timersActive() && !peer.timers.newHandshake.IsPending() {
peer.timers.newHandshake.Mod(KeepaliveTimeout + RekeyTimeout + time.Millisecond*time.Duration(unsafeRand.Int63n(RekeyTimeoutJitterMaxMs)))
peer.timers.newHandshake.Mod(KeepaliveTimeout + RekeyTimeout + time.Millisecond*time.Duration(fastrandn(RekeyTimeoutJitterMaxMs)))
}
}
@ -184,7 +179,7 @@ func (peer *Peer) timersAnyAuthenticatedPacketReceived() {
/* Should be called after a handshake initiation message is sent. */
func (peer *Peer) timersHandshakeInitiated() {
if peer.timersActive() {
peer.timers.retransmitHandshake.Mod(RekeyTimeout + time.Millisecond*time.Duration(unsafeRand.Int63n(RekeyTimeoutJitterMaxMs)))
peer.timers.retransmitHandshake.Mod(RekeyTimeout + time.Millisecond*time.Duration(fastrandn(RekeyTimeoutJitterMaxMs)))
}
}