96 lines
2.8 KiB
Go
96 lines
2.8 KiB
Go
// Copyright 2019 The gVisor Authors.
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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.dev/gvisor/pkg/tcpip"
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"gvisor.dev/gvisor/pkg/tcpip/stack"
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"gvisor.dev/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, pkt tcpip.PacketBuffer) 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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pkt: pkt,
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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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pkt tcpip.PacketBuffer
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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, ep.bindToDevice); 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.RegisterNICID = 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.pkt)
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return ep, nil
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}
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