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wgengine/netstack: add support for incoming UDP connections

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Updates #504

Updates #707

Signed-off-by: Naman Sood <mail@nsood.in>
This commit is contained in:
Naman Sood 2021-03-08 13:22:35 -05:00
parent 43b30e463c
commit 7325b5a7ba
1 changed files with 67 additions and 9 deletions
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76
wgengine/netstack/netstack.go
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@ -18,6 +18,7 @@
"strconv"
"strings"
"sync"
"time"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/adapters/gonet"
@ -60,6 +61,7 @@ type Impl struct {
}
const nicID = 1
const mtu = 1500
// Create creates and populates a new Impl.
func Create(logf logger.Logf, tundev *tstun.TUN, e wgengine.Engine, mc *magicsock.Conn) (*Impl, error) {
@ -79,7 +81,6 @@ func Create(logf logger.Logf, tundev *tstun.TUN, e wgengine.Engine, mc *magicsoc
NetworkProtocols: []stack.NetworkProtocolFactory{ipv4.NewProtocol, ipv6.NewProtocol},
TransportProtocols: []stack.TransportProtocolFactory{tcp.NewProtocol, udp.NewProtocol, icmp.NewProtocol4, icmp.NewProtocol6},
})
const mtu = 1500
linkEP := channel.New(512, mtu, "")
if tcpipProblem := ipstack.CreateNIC(nicID, linkEP); tcpipProblem != nil {
return nil, fmt.Errorf("could not create netstack NIC: %v", tcpipProblem)
@ -390,18 +391,75 @@ func (ns *Impl) acceptUDP(r *udp.ForwarderRequest) {
ns.logf("Could not create endpoint, exiting")
return
}
localAddr, err := ep.GetLocalAddress()
if err != nil {
return
}
remoteAddr, err := ep.GetRemoteAddress()
if err != nil {
return
}
c := gonet.NewUDPConn(ns.ipstack, &wq, ep)
go echoUDP(c)
go ns.forwardUDP(c, &wq, localAddr, remoteAddr)
}
func echoUDP(c *gonet.UDPConn) {
buf := make([]byte, 1500)
for {
n, err := c.Read(buf)
func (ns *Impl) forwardUDP(client *gonet.UDPConn, wq *waiter.Queue, clientLocalAddr, clientRemoteAddr tcpip.FullAddress) {
port := clientLocalAddr.Port
ns.logf("[v2] netstack: forwarding incoming UDP connection on port %v", port)
backendLocalAddr := &net.UDPAddr{Port: int(clientRemoteAddr.Port)}
backendRemoteAddr := &net.UDPAddr{IP: net.ParseIP("127.0.0.1"), Port: int(port)}
backendConn, err := net.ListenUDP("udp4", backendLocalAddr)
if err != nil {
ns.logf("netstack: could not bind local port %v: %v, trying again with random port", clientRemoteAddr.Port, err)
backendConn, err = net.ListenUDP("udp4", nil)
if err != nil {
break
ns.logf("netstack: could not connect to local UDP server on port %v: %v", port, err)
return
}
c.Write(buf[:n])
}
c.Close()
ctx, cancel := context.WithCancel(context.Background())
timer := time.AfterFunc(2*time.Minute, func() {
ns.logf("netstack: forwarder UDP connection on port %v closed", port)
cancel()
client.Close()
backendConn.Close()
})
extend := func() {
timer.Reset(2 * time.Minute)
}
startPacketCopy(ctx, client, &net.UDPAddr{
IP: net.ParseIP(clientRemoteAddr.Addr.String()),
Port: int(clientRemoteAddr.Port),
}, backendConn, ns.logf, extend)
startPacketCopy(ctx, backendConn, backendRemoteAddr, client, ns.logf, extend)
}
func startPacketCopy(ctx context.Context, dst net.PacketConn, dstAddr net.Addr, src net.PacketConn, logf logger.Logf, extend func()) {
go func() {
pkt := make([]byte, mtu)
for {
select {
case <-ctx.Done():
return
default:
n, srcAddr, err := src.ReadFrom(pkt)
if err != nil {
if ctx.Err() == nil {
logf("read packet from %s failed: %v", srcAddr, err)
}
return
}
_, err = dst.WriteTo(pkt[:n], dstAddr)
if err != nil {
if ctx.Err() == nil {
logf("write packet to %s failed: %v", dstAddr, err)
}
return
}
logf("[v2] wrote UDP packet %s -> %s", srcAddr, dstAddr)
extend()
}
}
}()
}