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TUN inbound: Make udp_fullcone pure side effect free udp connection (#5526)

Browse Source 
https://github.com/XTLS/Xray-core/pull/5526#issue-3804306341

---------

Co-authored-by: RPRX <63339210+RPRX@users.noreply.github.com>
This commit is contained in:
Owersun
2026-01-12 16:34:09 +01:00
committed by GitHub
parent 0c09f4342b
commit 7726fbece0
3 changed files with 156 additions and 199 deletions
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80
proxy/tun/stack_gvisor.go
View File

@@ -9,6 +9,7 @@ import (
"gvisor.dev/gvisor/pkg/buffer"
"gvisor.dev/gvisor/pkg/tcpip"
"gvisor.dev/gvisor/pkg/tcpip/adapters/gonet"
"gvisor.dev/gvisor/pkg/tcpip/checksum"
"gvisor.dev/gvisor/pkg/tcpip/header"
"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
@@ -102,21 +103,7 @@ func (t *stackGVisor) Start() error {
ipStack.SetTransportProtocolHandler(tcp.ProtocolNumber, tcpForwarder.HandlePacket)
// Use custom UDP packet handler, instead of strict gVisor forwarder, for FullCone NAT support
udpForwarder := newUdpConnectionHandler(t.ctx, t.handler, func(p []byte) {
// extract network protocol from the packet
var networkProtocol tcpip.NetworkProtocolNumber
switch header.IPVersion(p) {
case header.IPv4Version:
networkProtocol = header.IPv4ProtocolNumber
case header.IPv6Version:
networkProtocol = header.IPv6ProtocolNumber
default:
// discard packet with unknown network version
return
}
ipStack.WriteRawPacket(defaultNIC, networkProtocol, buffer.MakeWithData(p))
})
udpForwarder := newUdpConnectionHandler(t.handler.HandleConnection, t.writeRawUDPPacket)
ipStack.SetTransportProtocolHandler(udp.ProtocolNumber, func(id stack.TransportEndpointID, pkt *stack.PacketBuffer) bool {
data := pkt.Data().AsRange().ToSlice()
if len(data) == 0 {
@@ -137,6 +124,69 @@ func (t *stackGVisor) Start() error {
return nil
}
func (t *stackGVisor) writeRawUDPPacket(payload []byte, src net.Destination, dst net.Destination) error {
udpLen := header.UDPMinimumSize + len(payload)
srcIP := tcpip.AddrFromSlice(src.Address.IP())
dstIP := tcpip.AddrFromSlice(dst.Address.IP())
// build packet with appropriate IP header size
isIPv4 := dst.Address.Family().IsIPv4()
ipHdrSize := header.IPv6MinimumSize
ipProtocol := header.IPv6ProtocolNumber
if isIPv4 {
ipHdrSize = header.IPv4MinimumSize
ipProtocol = header.IPv4ProtocolNumber
}
pkt := stack.NewPacketBuffer(stack.PacketBufferOptions{
ReserveHeaderBytes: ipHdrSize + header.UDPMinimumSize,
Payload: buffer.MakeWithData(payload),
})
defer pkt.DecRef()
// Build UDP header
udpHdr := header.UDP(pkt.TransportHeader().Push(header.UDPMinimumSize))
udpHdr.Encode(&header.UDPFields{
SrcPort: uint16(src.Port),
DstPort: uint16(dst.Port),
Length: uint16(udpLen),
})
// Calculate and set UDP checksum
xsum := header.PseudoHeaderChecksum(header.UDPProtocolNumber, srcIP, dstIP, uint16(udpLen))
udpHdr.SetChecksum(^udpHdr.CalculateChecksum(checksum.Checksum(payload, xsum)))
// Build IP header
if isIPv4 {
ipHdr := header.IPv4(pkt.NetworkHeader().Push(header.IPv4MinimumSize))
ipHdr.Encode(&header.IPv4Fields{
TotalLength: uint16(header.IPv4MinimumSize + udpLen),
TTL: 64,
Protocol: uint8(header.UDPProtocolNumber),
SrcAddr: srcIP,
DstAddr: dstIP,
})
ipHdr.SetChecksum(^ipHdr.CalculateChecksum())
} else {
ipHdr := header.IPv6(pkt.NetworkHeader().Push(header.IPv6MinimumSize))
ipHdr.Encode(&header.IPv6Fields{
PayloadLength: uint16(udpLen),
TransportProtocol: header.UDPProtocolNumber,
HopLimit: 64,
SrcAddr: srcIP,
DstAddr: dstIP,
})
}
// dispatch the packet
err := t.stack.WriteRawPacket(defaultNIC, ipProtocol, buffer.MakeWithView(pkt.ToView()))
if err != nil {
return errors.New("failed to write raw udp packet back to stack", err)
}
return nil
}
// Close is called by Handler to shut down the stack
func (t *stackGVisor) Close() error {
if t.stack == nil {