From ea932e4304c17eddb63dbfbd4aa6d1b83b58c0d3 Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Tue, 26 Oct 2021 18:51:52 +0200
Subject: manager: delay boottime updates and simplify

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
 main.go                | 10 ++++++++++
 manager/updatestate.go | 29 ++++++++++++++++++-----------
 2 files changed, 28 insertions(+), 11 deletions(-)

diff --git a/main.go b/main.go
index 3fad1a24..9a8a8607 100644
--- a/main.go
+++ b/main.go
@@ -6,15 +6,18 @@
 package main
 
 import (
+	"crypto/rand"
 	"debug/pe"
 	"errors"
 	"fmt"
 	"io"
 	"log"
+	unsafeRand "math/rand"
 	"os"
 	"strconv"
 	"strings"
 	"time"
+	"unsafe"
 
 	"golang.org/x/sys/windows"
 
@@ -150,12 +153,19 @@ func pipeFromHandleArgument(handleStr string) (*os.File, error) {
 	return os.NewFile(uintptr(handleInt), "pipe"), nil
 }
 
+func seedUnsafeRng() {
+	var seed int64
+	rand.Read(unsafe.Slice((*byte)(unsafe.Pointer(&seed)), unsafe.Sizeof(seed)))
+	unsafeRand.Seed(seed)
+}
+
 func main() {
 	if windows.SetDllDirectory("") != nil || windows.SetDefaultDllDirectories(windows.LOAD_LIBRARY_SEARCH_SYSTEM32) != nil {
 		panic("failed to restrict dll search path")
 	}
 
 	setLogFile()
+	seedUnsafeRng()
 	checkForWow64()
 
 	if len(os.Args) <= 1 {
diff --git a/manager/updatestate.go b/manager/updatestate.go
index 069e9b8a..5ea0f661 100644
--- a/manager/updatestate.go
+++ b/manager/updatestate.go
@@ -7,8 +7,10 @@ package manager
 
 import (
 	"log"
+	unsafeRand "math/rand"
 	"time"
 
+	"golang.zx2c4.com/wireguard/windows/services"
 	"golang.zx2c4.com/wireguard/windows/updater"
 	"golang.zx2c4.com/wireguard/windows/version"
 )
@@ -23,6 +25,10 @@ const (
 
 var updateState = UpdateStateUnknown
 
+func jitterSleep(min, max time.Duration) {
+	time.Sleep(min + time.Duration(unsafeRand.Int63n(int64(max-min+1))))
+}
+
 func checkForUpdates() {
 	if !version.IsRunningOfficialVersion() {
 		log.Println("Build is not official, so updates are disabled")
@@ -30,26 +36,27 @@ func checkForUpdates() {
 		IPCServerNotifyUpdateFound(updateState)
 		return
 	}
-
-	first := true
+	if services.StartedAtBoot() {
+		jitterSleep(time.Minute*2, time.Minute*5)
+	}
+	noError, didNotify := true, false
 	for {
 		update, err := updater.CheckForUpdate()
-		if err == nil && update != nil {
+		if err == nil && update != nil && !didNotify {
 			log.Println("An update is available")
 			updateState = UpdateStateFoundUpdate
 			IPCServerNotifyUpdateFound(updateState)
-			return
-		}
-		if err != nil {
+			didNotify = true
+		} else if err != nil && !didNotify {
 			log.Printf("Update checker: %v", err)
-			if first {
-				time.Sleep(time.Minute * 4)
-				first = false
+			if noError {
+				jitterSleep(time.Minute*4, time.Minute*6)
+				noError = false
 			} else {
-				time.Sleep(time.Minute * 25)
+				jitterSleep(time.Minute*25, time.Minute*30)
 			}
 		} else {
-			time.Sleep(time.Hour)
+			jitterSleep(time.Hour-time.Minute*3, time.Hour+time.Minute*3)
 		}
 	}
 }
-- 
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