From b9db93d60492d7816fd6cc4201228ee35820a36d Mon Sep 17 00:00:00 2001
From: Mikael Magnusson <mikma@users.sourceforge.net>
Date: Sat, 23 Jan 2021 02:18:03 +0100
Subject: fix gre protocol number

---
 pkg/tcpip/header/gre.go                  | 5 +++++
 pkg/tcpip/header/parse/parse.go          | 2 +-
 pkg/tcpip/link/gre/gre.go                | 4 ++--
 pkg/tcpip/sample/tun_tcp_connect/main.go | 4 ++--
 pkg/tcpip/transport/gre/protocol.go      | 6 +++---
 5 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/pkg/tcpip/header/gre.go b/pkg/tcpip/header/gre.go
index 3d1cc97d9..65f5c1894 100644
--- a/pkg/tcpip/header/gre.go
+++ b/pkg/tcpip/header/gre.go
@@ -13,6 +13,11 @@ const (
 // GRE represents a GRE header stored in a byte array.
 type GRE []byte
 
+const (
+	// GREProtocolNumber is GRE's transport protocol number.
+	GREProtocolNumber tcpip.TransportProtocolNumber = 47
+)
+
 // SetLength sets the "length" field of the udp header.
 func (b GRE) SetProtocolType(protocol tcpip.NetworkProtocolNumber) {
 	binary.BigEndian.PutUint16(b[greProtocolType:], uint16(protocol))
diff --git a/pkg/tcpip/header/parse/parse.go b/pkg/tcpip/header/parse/parse.go
index 3e5336c04..de3a91227 100644
--- a/pkg/tcpip/header/parse/parse.go
+++ b/pkg/tcpip/header/parse/parse.go
@@ -176,6 +176,6 @@ func TCP(pkt *stack.PacketBuffer) bool {
 // Returns true if the header was successfully parsed.
 func GRE(pkt *stack.PacketBuffer) bool {
 	_, ok := pkt.TransportHeader().Consume(4)
-	pkt.TransportProtocolNumber = 47
+	pkt.TransportProtocolNumber = header.GREProtocolNumber
 	return ok
 }
diff --git a/pkg/tcpip/link/gre/gre.go b/pkg/tcpip/link/gre/gre.go
index cd05f39d7..04f8f8da7 100644
--- a/pkg/tcpip/link/gre/gre.go
+++ b/pkg/tcpip/link/gre/gre.go
@@ -7,6 +7,7 @@ import (
         "os"
 
 	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/link/channel"
 	"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/raw"
@@ -15,7 +16,6 @@ import (
 )
 
 var SIZE = 16
-var ProtocolNumber tcpip.TransportProtocolNumber = 47
 
 type Endpoint struct {
 	channel.Endpoint
@@ -41,7 +41,7 @@ func (e *Endpoint) Bind(s *stack.Stack, laddr tcpip.FullAddress) {
 
 	// Create TCP endpoint.
 	var wq waiter.Queue
-	ep, err := raw.NewEndpoint(s, ipv4.ProtocolNumber, ProtocolNumber, &wq)
+	ep, err := raw.NewEndpoint(s, ipv4.ProtocolNumber, header.GREProtocolNumber, &wq)
 	if err != nil {
 		log.Fatal(err)
 	}
diff --git a/pkg/tcpip/sample/tun_tcp_connect/main.go b/pkg/tcpip/sample/tun_tcp_connect/main.go
index f44237295..19276aca7 100644
--- a/pkg/tcpip/sample/tun_tcp_connect/main.go
+++ b/pkg/tcpip/sample/tun_tcp_connect/main.go
@@ -233,7 +233,7 @@ func main() {
 
 	// Create TCP endpoint.
 	var rawWq waiter.Queue
-	rawEp, tcperr := raw.NewEndpoint(s, ipv4.ProtocolNumber, 47, &rawWq)
+	rawEp, tcperr := raw.NewEndpoint(s, ipv4.ProtocolNumber, header.GREProtocolNumber, &rawWq)
 	if tcperr != nil {
 		log.Fatal(tcperr)
 	}
@@ -260,7 +260,7 @@ func main() {
                 Raddr: fraddr,
         }
         greFwd := gre.NewForwarder(s, greInfo.greHandler)
-        s.SetTransportProtocolHandler(47, greFwd.HandlePacket)
+        s.SetTransportProtocolHandler(header.GREProtocolNumber, greFwd.HandlePacket)
 
         go greInfo.greRead(chEP)
         //greEP.Bind(s, greIP)
diff --git a/pkg/tcpip/transport/gre/protocol.go b/pkg/tcpip/transport/gre/protocol.go
index c1a49d042..a2182cfe4 100644
--- a/pkg/tcpip/transport/gre/protocol.go
+++ b/pkg/tcpip/transport/gre/protocol.go
@@ -20,7 +20,7 @@ import (
 
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
-//	"gvisor.dev/gvisor/pkg/tcpip/header"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/header/parse"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 	"gvisor.dev/gvisor/pkg/tcpip/transport/raw"
@@ -29,7 +29,7 @@ import (
 
 const (
 	// ProtocolNumber is the gre protocol number.
-	ProtocolNumber = 47 //header.GREProtocolNumber
+	ProtocolNumber = header.GREProtocolNumber
 
 	// MinBufferSize is the smallest size of a receive or send buffer.
 	MinBufferSize = 4 << 10 // 4KiB bytes.
@@ -64,7 +64,7 @@ func (p *protocol) NewEndpoint(netProto tcpip.NetworkProtocolNumber, waiterQueue
 // NewRawEndpoint creates a new raw GRE endpoint. It implements
 // stack.TransportProtocol.NewRawEndpoint.
 func (p *protocol) NewRawEndpoint(netProto tcpip.NetworkProtocolNumber, waiterQueue *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) {
-	return raw.NewEndpoint(p.stack, netProto, /*header.GREProtocolNumber*/ 47, waiterQueue)
+	return raw.NewEndpoint(p.stack, netProto, ProtocolNumber, waiterQueue)
 }
 
 // MinimumPacketSize returns the minimum valid gre packet size.
-- 
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