tcpip/transport/udp: add Forwarder type
Add a UDP forwarder for intercepting and forwarding UDP sessions. Change-Id: I2d83c900c1931adfc59a532dd4f6b33a0db406c9 PiperOrigin-RevId: 244293576
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@ -222,6 +222,62 @@ func TestCloseReaderWithForwarder(t *testing.T) {
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sender.close()
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}
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func TestUDPForwarder(t *testing.T) {
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s, terr := newLoopbackStack()
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if terr != nil {
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t.Fatalf("newLoopbackStack() = %v", terr)
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}
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ip1 := tcpip.Address(net.IPv4(169, 254, 10, 1).To4())
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addr1 := tcpip.FullAddress{NICID, ip1, 11211}
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s.AddAddress(NICID, ipv4.ProtocolNumber, ip1)
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ip2 := tcpip.Address(net.IPv4(169, 254, 10, 2).To4())
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addr2 := tcpip.FullAddress{NICID, ip2, 11311}
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s.AddAddress(NICID, ipv4.ProtocolNumber, ip2)
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done := make(chan struct{})
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fwd := udp.NewForwarder(s, func(r *udp.ForwarderRequest) {
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defer close(done)
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var wq waiter.Queue
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ep, err := r.CreateEndpoint(&wq)
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if err != nil {
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t.Fatalf("r.CreateEndpoint() = %v", err)
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}
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defer ep.Close()
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c := NewConn(&wq, ep)
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buf := make([]byte, 256)
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n, e := c.Read(buf)
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if e != nil {
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t.Errorf("c.Read() = %v", e)
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}
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if _, e := c.Write(buf[:n]); e != nil {
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t.Errorf("c.Write() = %v", e)
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}
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})
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s.SetTransportProtocolHandler(udp.ProtocolNumber, fwd.HandlePacket)
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c2, err := NewPacketConn(s, addr2, ipv4.ProtocolNumber)
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if err != nil {
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t.Fatal("NewPacketConn(port 5):", err)
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}
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sent := "abc123"
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sendAddr := fullToUDPAddr(addr1)
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if n, err := c2.WriteTo([]byte(sent), sendAddr); err != nil || n != len(sent) {
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t.Errorf("c1.WriteTo(%q, %v) = %d, %v, want = %d, %v", sent, sendAddr, n, err, len(sent), nil)
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}
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buf := make([]byte, 256)
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n, recvAddr, err := c2.ReadFrom(buf)
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if err != nil || recvAddr.String() != sendAddr.String() {
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t.Errorf("c1.ReadFrom() = %d, %v, %v, want = %d, %v, %v", n, recvAddr, err, len(sent), sendAddr, nil)
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}
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}
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// TestDeadlineChange tests that changing the deadline affects currently blocked reads.
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func TestDeadlineChange(t *testing.T) {
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s, err := newLoopbackStack()
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@ -20,6 +20,7 @@ go_library(
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srcs = [
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"endpoint.go",
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"endpoint_state.go",
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"forwarder.go",
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"protocol.go",
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"udp_packet_list.go",
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],
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@ -0,0 +1,96 @@
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// Copyright 2019 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package udp
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import (
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"gvisor.googlesource.com/gvisor/pkg/tcpip"
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"gvisor.googlesource.com/gvisor/pkg/tcpip/buffer"
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"gvisor.googlesource.com/gvisor/pkg/tcpip/stack"
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"gvisor.googlesource.com/gvisor/pkg/waiter"
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)
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// Forwarder is a session request forwarder, which allows clients to decide
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// what to do with a session request, for example: ignore it, or process it.
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//
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// The canonical way of using it is to pass the Forwarder.HandlePacket function
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// to stack.SetTransportProtocolHandler.
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type Forwarder struct {
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handler func(*ForwarderRequest)
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stack *stack.Stack
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}
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// NewForwarder allocates and initializes a new forwarder.
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func NewForwarder(s *stack.Stack, handler func(*ForwarderRequest)) *Forwarder {
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return &Forwarder{
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stack: s,
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handler: handler,
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}
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}
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// HandlePacket handles all packets.
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//
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// This function is expected to be passed as an argument to the
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// stack.SetTransportProtocolHandler function.
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func (f *Forwarder) HandlePacket(r *stack.Route, id stack.TransportEndpointID, netHeader buffer.View, vv buffer.VectorisedView) bool {
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f.handler(&ForwarderRequest{
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stack: f.stack,
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route: r,
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id: id,
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vv: vv,
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})
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return true
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}
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// ForwarderRequest represents a session request received by the forwarder and
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// passed to the client. Clients may optionally create an endpoint to represent
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// it via CreateEndpoint.
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type ForwarderRequest struct {
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stack *stack.Stack
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route *stack.Route
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id stack.TransportEndpointID
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vv buffer.VectorisedView
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}
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// ID returns the 4-tuple (src address, src port, dst address, dst port) that
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// represents the session request.
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func (r *ForwarderRequest) ID() stack.TransportEndpointID {
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return r.id
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}
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// CreateEndpoint creates a connected UDP endpoint for the session request.
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func (r *ForwarderRequest) CreateEndpoint(queue *waiter.Queue) (tcpip.Endpoint, *tcpip.Error) {
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ep := newEndpoint(r.stack, r.route.NetProto, queue)
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if err := r.stack.RegisterTransportEndpoint(r.route.NICID(), []tcpip.NetworkProtocolNumber{r.route.NetProto}, ProtocolNumber, r.id, ep, ep.reusePort); err != nil {
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ep.Close()
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return nil, err
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}
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ep.id = r.id
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ep.route = r.route.Clone()
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ep.dstPort = r.id.RemotePort
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ep.regNICID = r.route.NICID()
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ep.state = stateConnected
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ep.rcvMu.Lock()
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ep.rcvReady = true
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ep.rcvMu.Unlock()
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ep.HandlePacket(r.route, r.id, r.vv)
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return ep, nil
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}
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