mirror of
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222 lines
8.1 KiB
Go
222 lines
8.1 KiB
Go
// The MIT License (MIT)
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//
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// Copyright (c) 2021 srs-bench(ossrs)
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy of
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// this software and associated documentation files (the "Software"), to deal in
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// the Software without restriction, including without limitation the rights to
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// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
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// the Software, and to permit persons to whom the Software is furnished to do so,
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// subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
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// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
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// COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
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// IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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package vnet
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import (
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"net"
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"sync"
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"time"
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"github.com/pion/transport/vnet"
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)
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// A UDP proxy between real server(net.UDPConn) and vnet.UDPConn.
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//
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// High level design:
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// ..............................................
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// : Virtual Network (vnet) :
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// : :
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// +-------+ * 1 +----+ +--------+ :
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// | :App |------------>|:Net|--o<-----|:Router | .............................
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// +-------+ +----+ | | : UDPProxy :
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// : | | +----+ +---------+ +---------+ +--------+
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// : | |--->o--|:Net|-->o-| vnet. |-->o-| net. |--->-| :Real |
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// : | | +----+ | UDPConn | | UDPConn | | Server |
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// : | | : +---------+ +---------+ +--------+
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// : | | ............................:
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// : +--------+ :
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// ...............................................
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//
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// The whole big picture:
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// ......................................
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// : Virtual Network (vnet) :
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// : :
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// +-------+ * 1 +----+ +--------+ :
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// | :App |------------>|:Net|--o<-----|:Router | .............................
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// +-------+ +----+ | | : UDPProxy :
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// +-----------+ * 1 +----+ | | +----+ +---------+ +---------+ +--------+
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// |:STUNServer|-------->|:Net|--o<-----| |--->o--|:Net|-->o-| vnet. |-->o-| net. |--->-| :Real |
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// +-----------+ +----+ | | +----+ | UDPConn | | UDPConn | | Server |
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// +-----------+ * 1 +----+ | | : +---------+ +---------+ +--------+
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// |:TURNServer|-------->|:Net|--o<-----| | ............................:
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// +-----------+ +----+ [1] | | :
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// : 1 | | 1 <<has>> :
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// : +---<>| |<>----+ [2] :
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// : | +--------+ | :
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// To form | *| v 0..1 :
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// a subnet tree | o [3] +-----+ :
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// : | ^ |:NAT | :
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// : | | +-----+ :
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// : +-------+ :
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// ......................................
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type UDPProxy struct {
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// The router bind to.
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router *vnet.Router
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// Each vnet source, bind to a real socket to server.
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// key is real server addr, which is net.Addr
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// value is *aUDPProxyWorker
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workers sync.Map
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// For each endpoint, we never know when to start and stop proxy,
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// so we stop the endpoint when timeout.
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timeout time.Duration
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// For utest, to mock the target real server.
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// Optional, use the address of received client packet.
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mockRealServerAddr *net.UDPAddr
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}
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// NewProxy create a proxy, the router for this proxy belongs/bind to. If need to proxy for
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// please create a new proxy for each router. For all addresses we proxy, we will create a
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// vnet.Net in this router and proxy all packets.
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func NewProxy(router *vnet.Router) (*UDPProxy, error) {
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v := &UDPProxy{router: router, timeout: 2 * time.Minute}
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return v, nil
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}
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// Close the proxy, stop all workers.
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func (v *UDPProxy) Close() error {
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// nolint:godox // TODO: FIXME: Do cleanup.
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return nil
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}
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// Proxy starts a worker for server, ignore if already started.
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func (v *UDPProxy) Proxy(client *vnet.Net, server *net.UDPAddr) error {
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// Note that even if the worker exists, it's also ok to create a same worker,
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// because the router will use the last one, and the real server will see a address
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// change event after we switch to the next worker.
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if _, ok := v.workers.Load(server.String()); ok {
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// nolint:godox // TODO: Need to restart the stopped worker?
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return nil
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}
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// Not exists, create a new one.
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worker := &aUDPProxyWorker{
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router: v.router, mockRealServerAddr: v.mockRealServerAddr,
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}
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v.workers.Store(server.String(), worker)
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return worker.Proxy(client, server)
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}
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// A proxy worker for a specified proxy server.
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type aUDPProxyWorker struct {
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router *vnet.Router
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mockRealServerAddr *net.UDPAddr
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// Each vnet source, bind to a real socket to server.
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// key is vnet client addr, which is net.Addr
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// value is *net.UDPConn
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endpoints sync.Map
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}
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func (v *aUDPProxyWorker) Proxy(client *vnet.Net, serverAddr *net.UDPAddr) error { // nolint:gocognit
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// Create vnet for real server by serverAddr.
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nw := vnet.NewNet(&vnet.NetConfig{
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StaticIP: serverAddr.IP.String(),
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})
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if err := v.router.AddNet(nw); err != nil {
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return err
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}
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// We must create a "same" vnet.UDPConn as the net.UDPConn,
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// which has the same ip:port, to copy packets between them.
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vnetSocket, err := nw.ListenUDP("udp4", serverAddr)
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if err != nil {
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return err
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}
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// Start a proxy goroutine.
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var findEndpointBy func(addr net.Addr) (*net.UDPConn, error)
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// nolint:godox // TODO: FIXME: Do cleanup.
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go func() {
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buf := make([]byte, 1500)
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for {
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n, addr, err := vnetSocket.ReadFrom(buf)
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if err != nil {
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return
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}
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if n <= 0 || addr == nil {
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continue // Drop packet
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}
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realSocket, err := findEndpointBy(addr)
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if err != nil {
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continue // Drop packet.
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}
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if _, err := realSocket.Write(buf[:n]); err != nil {
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return
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}
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}
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}()
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// Got new vnet client, start a new endpoint.
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findEndpointBy = func(addr net.Addr) (*net.UDPConn, error) {
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// Exists binding.
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if value, ok := v.endpoints.Load(addr.String()); ok {
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// Exists endpoint, reuse it.
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return value.(*net.UDPConn), nil
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}
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// The real server we proxy to, for utest to mock it.
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realAddr := serverAddr
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if v.mockRealServerAddr != nil {
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realAddr = v.mockRealServerAddr
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}
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// Got new vnet client, create new endpoint.
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realSocket, err := net.DialUDP("udp4", nil, realAddr)
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if err != nil {
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return nil, err
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}
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// Bind address.
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v.endpoints.Store(addr.String(), realSocket)
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// Got packet from real serverAddr, we should proxy it to vnet.
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// nolint:godox // TODO: FIXME: Do cleanup.
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go func(vnetClientAddr net.Addr) {
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buf := make([]byte, 1500)
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for {
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n, _, err := realSocket.ReadFrom(buf)
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if err != nil {
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return
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}
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if n <= 0 {
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continue // Drop packet
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}
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if _, err := vnetSocket.WriteTo(buf[:n], vnetClientAddr); err != nil {
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return
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}
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}
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}(addr)
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return realSocket, nil
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}
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return nil
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}
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