5 files changed, 49 insertions, 7 deletions
diff --git a/pkg/tcpip/stack/nic.go b/pkg/tcpip/stack/nic.go
index abf73fe33..071221d5a 100644
--- a/pkg/tcpip/stack/nic.go
+++ b/pkg/tcpip/stack/nic.go
@@ -763,7 +763,7 @@ func (n *NIC) RemoveAddressRange(subnet tcpip.Subnet) {
 	n.mu.Unlock()
 }
 
-// Subnets returns the Subnets associated with this NIC.
+// AddressRanges returns the Subnets associated with this NIC.
 func (n *NIC) AddressRanges() []tcpip.Subnet {
 	n.mu.RLock()
 	defer n.mu.RUnlock()
diff --git a/pkg/tcpip/stack/stack.go b/pkg/tcpip/stack/stack.go
index f8d89248e..386eb6eec 100644
--- a/pkg/tcpip/stack/stack.go
+++ b/pkg/tcpip/stack/stack.go
@@ -912,7 +912,7 @@ func (s *Stack) CheckNIC(id tcpip.NICID) bool {
 	return false
 }
 
-// NICSubnets returns a map of NICIDs to their associated subnets.
+// NICAddressRanges returns a map of NICIDs to their associated subnets.
 func (s *Stack) NICAddressRanges() map[tcpip.NICID][]tcpip.Subnet {
 	s.mu.RLock()
 	defer s.mu.RUnlock()
diff --git a/pkg/tcpip/tcpip.go b/pkg/tcpip/tcpip.go
index 4a090ac86..b7813cbc0 100644
--- a/pkg/tcpip/tcpip.go
+++ b/pkg/tcpip/tcpip.go
@@ -322,7 +322,7 @@ type ControlMessages struct {
 	HasTOS bool
 
 	// TOS is the IPv4 type of service of the associated packet.
-	TOS int8
+	TOS uint8
 
 	// HasTClass indicates whether Tclass is valid/set.
 	HasTClass bool
@@ -500,9 +500,13 @@ type WriteOptions struct {
 type SockOptBool int
 
 const (
+	// ReceiveTOSOption is used by SetSockOpt/GetSockOpt to specify if the TOS
+	// ancillary message is passed with incoming packets.
+	ReceiveTOSOption SockOptBool = iota
+
 	// V6OnlyOption is used by {G,S}etSockOptBool to specify whether an IPv6
 	// socket is to be restricted to sending and receiving IPv6 packets only.
-	V6OnlyOption SockOptBool = iota
+	V6OnlyOption
 )
 
 // SockOptInt represents socket options which values have the int type.
diff --git a/pkg/tcpip/transport/udp/endpoint.go b/pkg/tcpip/transport/udp/endpoint.go
index 13446f5d9..c9cbed8f4 100644
--- a/pkg/tcpip/transport/udp/endpoint.go
+++ b/pkg/tcpip/transport/udp/endpoint.go
@@ -31,6 +31,7 @@ type udpPacket struct {
 	senderAddress tcpip.FullAddress
 	data          buffer.VectorisedView `state:".(buffer.VectorisedView)"`
 	timestamp     int64
+	tos           uint8
 }
 
 // EndpointState represents the state of a UDP endpoint.
@@ -113,6 +114,10 @@ type endpoint struct {
 	// applied while sending packets. Defaults to 0 as on Linux.
 	sendTOS uint8
 
+	// receiveTOS determines if the incoming IPv4 TOS header field is passed
+	// as ancillary data to ControlMessages on Read.
+	receiveTOS bool
+
 	// shutdownFlags represent the current shutdown state of the endpoint.
 	shutdownFlags tcpip.ShutdownFlags
 
@@ -243,7 +248,18 @@ func (e *endpoint) Read(addr *tcpip.FullAddress) (buffer.View, tcpip.ControlMess
 		*addr = p.senderAddress
 	}
 
-	return p.data.ToView(), tcpip.ControlMessages{HasTimestamp: true, Timestamp: p.timestamp}, nil
+	cm := tcpip.ControlMessages{
+		HasTimestamp: true,
+		Timestamp:    p.timestamp,
+	}
+	e.mu.RLock()
+	receiveTOS := e.receiveTOS
+	e.mu.RUnlock()
+	if receiveTOS {
+		cm.HasTOS = true
+		cm.TOS = p.tos
+	}
+	return p.data.ToView(), cm, nil
 }
 
 // prepareForWrite prepares the endpoint for sending data. In particular, it
@@ -458,6 +474,12 @@ func (e *endpoint) Peek([][]byte) (int64, tcpip.ControlMessages, *tcpip.Error) {
 // SetSockOptBool implements tcpip.Endpoint.SetSockOptBool.
 func (e *endpoint) SetSockOptBool(opt tcpip.SockOptBool, v bool) *tcpip.Error {
 	switch opt {
+	case tcpip.ReceiveTOSOption:
+		e.mu.Lock()
+		e.receiveTOS = v
+		e.mu.Unlock()
+		return nil
+
 	case tcpip.V6OnlyOption:
 		// We only recognize this option on v6 endpoints.
 		if e.NetProto != header.IPv6ProtocolNumber {
@@ -664,15 +686,21 @@ func (e *endpoint) SetSockOpt(opt interface{}) *tcpip.Error {
 // GetSockOptBool implements tcpip.Endpoint.GetSockOptBool.
 func (e *endpoint) GetSockOptBool(opt tcpip.SockOptBool) (bool, *tcpip.Error) {
 	switch opt {
+	case tcpip.ReceiveTOSOption:
+		e.mu.RLock()
+		v := e.receiveTOS
+		e.mu.RUnlock()
+		return v, nil
+
 	case tcpip.V6OnlyOption:
 		// We only recognize this option on v6 endpoints.
 		if e.NetProto != header.IPv6ProtocolNumber {
 			return false, tcpip.ErrUnknownProtocolOption
 		}
 
-		e.mu.Lock()
+		e.mu.RLock()
 		v := e.v6only
-		e.mu.Unlock()
+		e.mu.RUnlock()
 
 		return v, nil
 	}
@@ -1215,6 +1243,12 @@ func (e *endpoint) HandlePacket(r *stack.Route, id stack.TransportEndpointID, pk
 	e.rcvList.PushBack(packet)
 	e.rcvBufSize += pkt.Data.Size()
 
+	// Save any useful information from the network header to the packet.
+	switch r.NetProto {
+	case header.IPv4ProtocolNumber:
+		packet.tos, _ = header.IPv4(pkt.NetworkHeader).TOS()
+	}
+
 	packet.timestamp = e.stack.NowNanoseconds()
 
 	e.rcvMu.Unlock()
diff --git a/pkg/tcpip/transport/udp/udp_state_autogen.go b/pkg/tcpip/transport/udp/udp_state_autogen.go
index 5c4b43214..75b78fa01 100755
--- a/pkg/tcpip/transport/udp/udp_state_autogen.go
+++ b/pkg/tcpip/transport/udp/udp_state_autogen.go
@@ -15,6 +15,7 @@ func (x *udpPacket) save(m state.Map) {
 	m.Save("udpPacketEntry", &x.udpPacketEntry)
 	m.Save("senderAddress", &x.senderAddress)
 	m.Save("timestamp", &x.timestamp)
+	m.Save("tos", &x.tos)
 }
 
 func (x *udpPacket) afterLoad() {}
@@ -22,6 +23,7 @@ func (x *udpPacket) load(m state.Map) {
 	m.Load("udpPacketEntry", &x.udpPacketEntry)
 	m.Load("senderAddress", &x.senderAddress)
 	m.Load("timestamp", &x.timestamp)
+	m.Load("tos", &x.tos)
 	m.LoadValue("data", new(buffer.VectorisedView), func(y interface{}) { x.loadData(y.(buffer.VectorisedView)) })
 }
 
@@ -51,6 +53,7 @@ func (x *endpoint) save(m state.Map) {
 	m.Save("boundBindToDevice", &x.boundBindToDevice)
 	m.Save("boundPortFlags", &x.boundPortFlags)
 	m.Save("sendTOS", &x.sendTOS)
+	m.Save("receiveTOS", &x.receiveTOS)
 	m.Save("shutdownFlags", &x.shutdownFlags)
 	m.Save("multicastMemberships", &x.multicastMemberships)
 	m.Save("effectiveNetProtos", &x.effectiveNetProtos)
@@ -79,6 +82,7 @@ func (x *endpoint) load(m state.Map) {
 	m.Load("boundBindToDevice", &x.boundBindToDevice)
 	m.Load("boundPortFlags", &x.boundPortFlags)
 	m.Load("sendTOS", &x.sendTOS)
+	m.Load("receiveTOS", &x.receiveTOS)
 	m.Load("shutdownFlags", &x.shutdownFlags)
 	m.Load("multicastMemberships", &x.multicastMemberships)
 	m.Load("effectiveNetProtos", &x.effectiveNetProtos)