From c69d02664924e11ffc5e6728638216a26b81c4ce Mon Sep 17 00:00:00 2001
From: "Jason A. Donenfeld" <Jason@zx2c4.com>
Date: Tue, 18 Jun 2019 16:08:28 +0200
Subject: [PATCH] tun: windows: never retry open on Windows 10

---
 go.mod                       |  6 +++---
 go.sum                       | 12 ++++++------
 tun/tun_windows.go           | 15 ++++++++++++---
 tun/wintun/wintun_windows.go |  2 +-
 4 files changed, 22 insertions(+), 13 deletions(-)

diff --git a/go.mod b/go.mod
index 64042c9..5c37b80 100644
--- a/go.mod
+++ b/go.mod
@@ -3,7 +3,7 @@ module golang.zx2c4.com/wireguard
 go 1.12
 
 require (
-	golang.org/x/crypto v0.0.0-20190513172903-22d7a77e9e5f
-	golang.org/x/net v0.0.0-20190522155817-f3200d17e092
-	golang.org/x/sys v0.0.0-20190606203320-7fc4e5ec1444
+	golang.org/x/crypto v0.0.0-20190617133340-57b3e21c3d56
+	golang.org/x/net v0.0.0-20190613194153-d28f0bde5980
+	golang.org/x/sys v0.0.0-20190618155005-516e3c20635f
 )
diff --git a/go.sum b/go.sum
index c645ad2..fbaac9a 100644
--- a/go.sum
+++ b/go.sum
@@ -1,11 +1,11 @@
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
-golang.org/x/crypto v0.0.0-20190513172903-22d7a77e9e5f h1:R423Cnkcp5JABoeemiGEPlt9tHXFfw5kvc0yqlxRPWo=
-golang.org/x/crypto v0.0.0-20190513172903-22d7a77e9e5f/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/crypto v0.0.0-20190617133340-57b3e21c3d56 h1:ZpKuNIejY8P0ExLOVyKhb0WsgG8UdvHXe6TWjY7eL6k=
+golang.org/x/crypto v0.0.0-20190617133340-57b3e21c3d56/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
-golang.org/x/net v0.0.0-20190522155817-f3200d17e092 h1:4QSRKanuywn15aTZvI/mIDEgPQpswuFndXpOj3rKEco=
-golang.org/x/net v0.0.0-20190522155817-f3200d17e092/go.mod h1:HSz+uSET+XFnRR8LxR5pz3Of3rY3CfYBVs4xY44aLks=
+golang.org/x/net v0.0.0-20190613194153-d28f0bde5980 h1:dfGZHvZk057jK2MCeWus/TowKpJ8y4AmooUzdBSR9GU=
+golang.org/x/net v0.0.0-20190613194153-d28f0bde5980/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20190606203320-7fc4e5ec1444 h1:/d2cWp6PSamH4jDPFLyO150psQdqvtoNX8Zjg3AQ31g=
-golang.org/x/sys v0.0.0-20190606203320-7fc4e5ec1444/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/sys v0.0.0-20190618155005-516e3c20635f h1:dHNZYIYdq2QuU6w73vZ/DzesPbVlZVYZTtTZmrnsbQ8=
+golang.org/x/sys v0.0.0-20190618155005-516e3c20635f/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
diff --git a/tun/tun_windows.go b/tun/tun_windows.go
index b88129d..05fc3df 100644
--- a/tun/tun_windows.go
+++ b/tun/tun_windows.go
@@ -55,6 +55,15 @@ func packetAlign(size uint32) uint32 {
 	return (size + (packetExchangeAlignment - 1)) &^ (packetExchangeAlignment - 1)
 }
 
+var shouldRetryOpen = windows.RtlGetVersion().MajorVersion < 10
+
+func maybeRetry(x int) int {
+	if shouldRetryOpen {
+		return x
+	}
+	return 0
+}
+
 //
 // CreateTUN creates a Wintun adapter with the given name. Should a Wintun
 // adapter with the same name exist, it is reused.
@@ -104,7 +113,7 @@ func CreateTUNWithRequestedGUID(ifname string, requestedGUID *windows.GUID) (Dev
 }
 
 func (tun *NativeTun) openTUN() error {
-	retries := retryTimeout * retryRate
+	retries := maybeRetry(retryTimeout * retryRate)
 	if tun.close {
 		return os.ErrClosed
 	}
@@ -238,7 +247,7 @@ func (tun *NativeTun) Read(buff []byte, offset int) (int, error) {
 	default:
 	}
 
-	retries := 1000
+	retries := maybeRetry(1000)
 	for {
 		if tun.rdBuff.offset+packetExchangeAlignment <= tun.rdBuff.avail {
 			// Get packet from the exchange buffer.
@@ -302,7 +311,7 @@ func (tun *NativeTun) Flush() error {
 		tun.wrBuff.packetNum = 0
 		tun.wrBuff.offset = 0
 	}()
-	retries := 1000
+	retries := maybeRetry(1000)
 
 	for {
 		// Get TUN data pipe.
diff --git a/tun/wintun/wintun_windows.go b/tun/wintun/wintun_windows.go
index 281ab37..b8aabf3 100644
--- a/tun/wintun/wintun_windows.go
+++ b/tun/wintun/wintun_windows.go
@@ -30,7 +30,7 @@ type Wintun struct {
 var deviceClassNetGUID = windows.GUID{Data1: 0x4d36e972, Data2: 0xe325, Data3: 0x11ce, Data4: [8]byte{0xbf, 0xc1, 0x08, 0x00, 0x2b, 0xe1, 0x03, 0x18}}
 
 const (
-	hardwareID = "Wintun"
+	hardwareID             = "Wintun"
 	waitForRegistryTimeout = time.Second * 10
 )