Support for receiving outbound packets in AF_PACKET.

Updates #173

PiperOrigin-RevId: 322665518

2 files changed, 64 insertions, 0 deletions

diff --git a/pkg/tcpip/link/packetsocket/BUILD b/pkg/tcpip/link/packetsocket/BUILD
new file mode 100644
index 000000000..6fff160ce
--- /dev/null
+++ b/pkg/tcpip/link/packetsocket/BUILD
@@ -0,0 +1,14 @@
+load("//tools:defs.bzl", "go_library")
+
+package(licenses = ["notice"])
+
+go_library(
+    name = "packetsocket",
+    srcs = ["endpoint.go"],
+    visibility = ["//visibility:public"],
+    deps = [
+        "//pkg/tcpip",
+        "//pkg/tcpip/link/nested",
+        "//pkg/tcpip/stack",
+    ],
+)
diff --git a/pkg/tcpip/link/packetsocket/endpoint.go b/pkg/tcpip/link/packetsocket/endpoint.go
new file mode 100644
index 000000000..3922c2a04
--- /dev/null
+++ b/pkg/tcpip/link/packetsocket/endpoint.go
@@ -0,0 +1,50 @@
+// Copyright 2020 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 packetsocket provides a link layer endpoint that provides the ability
+// to loop outbound packets to any AF_PACKET sockets that may be interested in
+// the outgoing packet.
+package packetsocket
+
+import (
+	"gvisor.dev/gvisor/pkg/tcpip"
+	"gvisor.dev/gvisor/pkg/tcpip/link/nested"
+	"gvisor.dev/gvisor/pkg/tcpip/stack"
+)
+
+type endpoint struct {
+	nested.Endpoint
+}
+
+// New creates a new packetsocket LinkEndpoint.
+func New(lower stack.LinkEndpoint) stack.LinkEndpoint {
+	e := &endpoint{}
+	e.Endpoint.Init(lower, e)
+	return e
+}
+
+// WritePacket implements stack.LinkEndpoint.WritePacket.
+func (e *endpoint) WritePacket(r *stack.Route, gso *stack.GSO, protocol tcpip.NetworkProtocolNumber, pkt *stack.PacketBuffer) *tcpip.Error {
+	e.Endpoint.DeliverOutboundPacket(r.RemoteLinkAddress, r.LocalLinkAddress, protocol, pkt)
+	return e.Endpoint.WritePacket(r, gso, protocol, pkt)
+}
+
+// WritePackets implements stack.LinkEndpoint.WritePackets.
+func (e *endpoint) WritePackets(r *stack.Route, gso *stack.GSO, pkts stack.PacketBufferList, proto tcpip.NetworkProtocolNumber) (int, *tcpip.Error) {
+	for pkt := pkts.Front(); pkt != nil; pkt = pkt.Next() {
+		e.Endpoint.DeliverOutboundPacket(pkt.EgressRoute.RemoteLinkAddress, pkt.EgressRoute.LocalLinkAddress, pkt.NetworkProtocolNumber, pkt)
+	}
+
+	return e.Endpoint.WritePackets(r, gso, pkts, proto)
+}