2 files changed, 142 insertions, 0 deletions
diff --git a/pkg/tcpip/link/channel/channel.go b/pkg/tcpip/link/channel/channel.go
new file mode 100755
index 000000000..18adb2085
--- /dev/null
+++ b/pkg/tcpip/link/channel/channel.go
@@ -0,0 +1,138 @@
+// Copyright 2018 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 channel provides the implemention of channel-based data-link layer
+// endpoints. Such endpoints allow injection of inbound packets and store
+// outbound packets in a channel.
+package channel
+
+import (
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+)
+
+// PacketInfo holds all the information about an outbound packet.
+type PacketInfo struct {
+	Header  buffer.View
+	Payload buffer.View
+	Proto   tcpip.NetworkProtocolNumber
+	GSO     *stack.GSO
+}
+
+// Endpoint is link layer endpoint that stores outbound packets in a channel
+// and allows injection of inbound packets.
+type Endpoint struct {
+	dispatcher stack.NetworkDispatcher
+	mtu        uint32
+	linkAddr   tcpip.LinkAddress
+	GSO        bool
+
+	// C is where outbound packets are queued.
+	C chan PacketInfo
+}
+
+// New creates a new channel endpoint.
+func New(size int, mtu uint32, linkAddr tcpip.LinkAddress) *Endpoint {
+	return &Endpoint{
+		C:        make(chan PacketInfo, size),
+		mtu:      mtu,
+		linkAddr: linkAddr,
+	}
+}
+
+// Drain removes all outbound packets from the channel and counts them.
+func (e *Endpoint) Drain() int {
+	c := 0
+	for {
+		select {
+		case <-e.C:
+			c++
+		default:
+			return c
+		}
+	}
+}
+
+// Inject injects an inbound packet.
+func (e *Endpoint) Inject(protocol tcpip.NetworkProtocolNumber, vv buffer.VectorisedView) {
+	e.InjectLinkAddr(protocol, "", vv)
+}
+
+// InjectLinkAddr injects an inbound packet with a remote link address.
+func (e *Endpoint) InjectLinkAddr(protocol tcpip.NetworkProtocolNumber, remote tcpip.LinkAddress, vv buffer.VectorisedView) {
+	e.dispatcher.DeliverNetworkPacket(e, remote, "" /* local */, protocol, vv.Clone(nil))
+}
+
+// Attach saves the stack network-layer dispatcher for use later when packets
+// are injected.
+func (e *Endpoint) Attach(dispatcher stack.NetworkDispatcher) {
+	e.dispatcher = dispatcher
+}
+
+// IsAttached implements stack.LinkEndpoint.IsAttached.
+func (e *Endpoint) IsAttached() bool {
+	return e.dispatcher != nil
+}
+
+// MTU implements stack.LinkEndpoint.MTU. It returns the value initialized
+// during construction.
+func (e *Endpoint) MTU() uint32 {
+	return e.mtu
+}
+
+// Capabilities implements stack.LinkEndpoint.Capabilities.
+func (e *Endpoint) Capabilities() stack.LinkEndpointCapabilities {
+	caps := stack.LinkEndpointCapabilities(0)
+	if e.GSO {
+		caps |= stack.CapabilityGSO
+	}
+	return caps
+}
+
+// GSOMaxSize returns the maximum GSO packet size.
+func (*Endpoint) GSOMaxSize() uint32 {
+	return 1 << 15
+}
+
+// MaxHeaderLength returns the maximum size of the link layer header. Given it
+// doesn't have a header, it just returns 0.
+func (*Endpoint) MaxHeaderLength() uint16 {
+	return 0
+}
+
+// LinkAddress returns the link address of this endpoint.
+func (e *Endpoint) LinkAddress() tcpip.LinkAddress {
+	return e.linkAddr
+}
+
+// WritePacket stores outbound packets into the channel.
+func (e *Endpoint) WritePacket(_ *stack.Route, gso *stack.GSO, hdr buffer.Prependable, payload buffer.VectorisedView, protocol tcpip.NetworkProtocolNumber) *tcpip.Error {
+	p := PacketInfo{
+		Header:  hdr.View(),
+		Proto:   protocol,
+		Payload: payload.ToView(),
+		GSO:     gso,
+	}
+
+	select {
+	case e.C <- p:
+	default:
+	}
+
+	return nil
+}
+
+// Wait implements stack.LinkEndpoint.Wait.
+func (*Endpoint) Wait() {}
diff --git a/pkg/tcpip/link/channel/channel_state_autogen.go b/pkg/tcpip/link/channel/channel_state_autogen.go
new file mode 100755
index 000000000..19e9e5a2b
--- /dev/null
+++ b/pkg/tcpip/link/channel/channel_state_autogen.go
@@ -0,0 +1,4 @@
+// automatically generated by stateify.
+
+package channel
+