add support for icmp

tcpip/transport/icmp/endpoint.go

@@ -86,7 +86,7 @@ type endpoint struct {
 	route    stack.Route
 }
 
-func newEndpoint(stack *stack.Stack, netProto tcpip.NetworkProtocolNumber, transProto tcpip.TransportProtocolNumber, waiterQueue *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) {
+func newEndpoint(stack *stack.Stack, netProto tcpip.NetworkProtocolNumber, transProto tcpip.TransportProtocolNumber, waiterQueue *waiter.Queue) (*endpoint, *tcpip.Error) {
 	return &endpoint{
 		stack:         stack,
 		netProto:      netProto,
@@ -365,7 +365,7 @@ func (e *endpoint) send4(r *stack.Route, data buffer.View) *tcpip.Error {
 	data = data[header.ICMPv4EchoMinimumSize:]
 
 	// Linux performs these basic checks.
-	if icmpv4.Type() != header.ICMPv4Echo || icmpv4.Code() != 0 {
+	if (icmpv4.Type() != header.ICMPv4Echo && icmpv4.Type() != header.ICMPv4EchoReply) || icmpv4.Code() != 0 {
 		return tcpip.ErrInvalidEndpointState
 	}
 
@@ -659,7 +659,7 @@ func (e *endpoint) HandlePacket(r *stack.Route, id stack.TransportEndpointID, vv
 	switch e.netProto {
 	case header.IPv4ProtocolNumber:
 		h := header.ICMPv4(vv.First())
-		if h.Type() != header.ICMPv4EchoReply {
+		if h.Type() != header.ICMPv4EchoReply && h.Type() != header.ICMPv4Echo {
 			e.stack.Stats().DroppedPackets.Increment()
 			return
 		}

tcpip/transport/icmp/forwarder.go

@@ -0,0 +1,97 @@
+// Copyright 2019 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package icmp
+
+import (
+	"github.com/google/netstack/tcpip"
+	"github.com/google/netstack/tcpip/buffer"
+	"github.com/google/netstack/tcpip/stack"
+	"github.com/google/netstack/waiter"
+)
+
+// Forwarder is a session request forwarder, which allows clients to decide
+// what to do with a session request, for example: ignore it, or process it.
+//
+// The canonical way of using it is to pass the Forwarder.HandlePacket function
+// to stack.SetTransportProtocolHandler.
+type Forwarder struct {
+	handler func(*ForwarderRequest)
+
+	stack *stack.Stack
+}
+
+// NewForwarder allocates and initializes a new forwarder.
+func NewForwarder(s *stack.Stack, handler func(*ForwarderRequest)) *Forwarder {
+	return &Forwarder{
+		stack:   s,
+		handler: handler,
+	}
+}
+
+// HandlePacket handles all packets.
+//
+// This function is expected to be passed as an argument to the
+// stack.SetTransportProtocolHandler function.
+func (f *Forwarder) HandlePacket(r *stack.Route, id stack.TransportEndpointID, netHeader buffer.View, vv buffer.VectorisedView) bool {
+
+	f.handler(&ForwarderRequest{
+		stack: f.stack,
+		route: r,
+		id:    id,
+		vv:    vv,
+	})
+
+	return true
+}
+
+// ForwarderRequest represents a session request received by the forwarder and
+// passed to the client. Clients may optionally create an endpoint to represent
+// it via CreateEndpoint.
+type ForwarderRequest struct {
+	stack *stack.Stack
+	route *stack.Route
+	id    stack.TransportEndpointID
+	vv    buffer.VectorisedView
+}
+
+// ID returns the 4-tuple (src address, src port, dst address, dst port) that
+// represents the session request.
+func (r *ForwarderRequest) ID() stack.TransportEndpointID {
+	return r.id
+}
+
+// CreateEndpoint creates a connected UDP endpoint for the session request.
+func (r *ForwarderRequest) CreateEndpoint(queue *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) {
+	ep, _ := newEndpoint(r.stack, r.route.NetProto, ProtocolNumber4, queue)
+	if err := r.stack.RegisterTransportEndpoint(r.route.NICID(), []tcpip.NetworkProtocolNumber{r.route.NetProto}, ProtocolNumber4, r.id, ep, true); err != nil {
+		ep.Close()
+		return nil, err
+	}
+
+	ep.id = r.id
+	ep.route = r.route.Clone()
+	//	ep.dstPort = r.id.RemotePort
+	ep.regNICID = r.route.NICID()
+
+	ep.state = stateConnected
+
+	ep.rcvMu.Lock()
+	ep.rcvReady = true
+	ep.rcvMu.Unlock()
+
+	ep.HandlePacket(r.route, r.id, r.vv)
+
+	return ep, nil
+}