init

component/control/udp.go

@@ -0,0 +1,145 @@
+/*
+ * SPDX-License-Identifier: AGPL-3.0-only
+ * Copyright (c) since 2022, mzz2017 (mzz@tuta.io). All rights reserved.
+ */
+
+package control
+
+import (
+	"encoding/binary"
+	"fmt"
+	"foo/common/consts"
+	"foo/pkg/pool"
+	"golang.org/x/net/dns/dnsmessage"
+	"net"
+	"net/netip"
+	"time"
+)
+
+const (
+	DefaultNatTimeout = 3 * time.Minute
+	DnsNatTimeout     = 17 * time.Second // RFC 5452
+)
+
+func ChooseNatTimeout(data []byte) (dmsg *dnsmessage.Message, timeout time.Duration) {
+	var dnsmsg dnsmessage.Message
+	if err := dnsmsg.Unpack(data); err == nil {
+		//log.Printf("DEBUG: lookup %v", dnsmsg.Questions[0].Name)
+		return &dnsmsg, DnsNatTimeout
+	}
+	return nil, DefaultNatTimeout
+}
+
+type AddrHdr struct {
+	Dest     netip.AddrPort
+	Outbound uint8
+}
+
+func ParseAddrHdr(data []byte) (hdr *AddrHdr, dataOffset int, err error) {
+	ipSize := 16
+	dataOffset = consts.AddrHdrSize
+	if len(data) < dataOffset {
+		return nil, 0, fmt.Errorf("data is too short to parse AddrHdr")
+	}
+	destAddr, _ := netip.AddrFromSlice(data[:ipSize])
+	port := binary.BigEndian.Uint16(data[ipSize:])
+	outbound := data[ipSize+2]
+	return &AddrHdr{
+		Dest:     netip.AddrPortFrom(destAddr, port),
+		Outbound: outbound,
+	}, dataOffset, nil
+}
+
+func (hdr *AddrHdr) ToBytesFromPool() []byte {
+	ipSize := 16
+	buf := pool.GetZero(consts.AddrHdrSize) // byte align to a multiple of 4
+	ip := hdr.Dest.Addr().As16()
+	copy(buf, ip[:])
+	binary.BigEndian.PutUint16(buf[ipSize:], hdr.Dest.Port())
+	buf[ipSize+2] = hdr.Outbound
+	return buf
+}
+
+func sendPktWithHdr(data []byte, from netip.AddrPort, lConn *net.UDPConn, to netip.AddrPort) error {
+	hdr := AddrHdr{
+		Dest:     from,
+		Outbound: 0, // Do not care.
+	}
+	bHdr := hdr.ToBytesFromPool()
+	defer pool.Put(bHdr)
+	buf := pool.Get(len(bHdr) + len(data))
+	defer pool.Put(buf)
+	copy(buf, bHdr)
+	copy(buf[len(bHdr):], data)
+	//log.Println("from", from, "to", to)
+	_, err := lConn.WriteToUDPAddrPort(buf, to)
+	return err
+}
+
+func (c *ControlPlane) RelayToUDP(lConn *net.UDPConn, to netip.AddrPort, isDNS bool) UdpHandler {
+	return func(data []byte, from netip.AddrPort) (err error) {
+		if isDNS {
+			data, err = c.DnsRespHandler(data)
+			if err != nil {
+				c.log.Warnf("DnsRespHandler: %v", err)
+			}
+		}
+		return sendPktWithHdr(data, from, lConn, to)
+	}
+}
+
+func (c *ControlPlane) handlePkt(data []byte, lConn *net.UDPConn, lAddrPort netip.AddrPort, addrHdr *AddrHdr) (err error) {
+	switch consts.OutboundIndex(addrHdr.Outbound) {
+	case consts.OutboundDirect:
+	case consts.OutboundControlPlaneRoute:
+		// FIXME: check and re-route.
+		addrHdr.Outbound = uint8(consts.OutboundDirect)
+
+		c.log.Debugf("outbound: %v => %v",
+			consts.OutboundControlPlaneRoute.String(),
+			consts.OutboundIndex(addrHdr.Outbound).String(),
+		)
+	default:
+	}
+	outbound := c.outbounds[addrHdr.Outbound]
+	dnsMessage, natTimeout := ChooseNatTimeout(data)
+	// We should cache DNS records and set record TTL to 0, in order to monitor the dns req and resp in real time.
+	isDns := dnsMessage != nil
+	if isDns {
+		if resp := c.LookupDnsRespCache(dnsMessage); resp != nil {
+			if err = sendPktWithHdr(resp, addrHdr.Dest, lConn, lAddrPort); err != nil {
+				return fmt.Errorf("failed to write cached DNS resp: %w", err)
+			}
+			q := dnsMessage.Questions[0]
+			c.log.Debugf("UDP(DNS) %v <-[%v]-> Cache: %v %v",
+				lAddrPort.String(), outbound.Name, q.Name, q.Type,
+			)
+			return nil
+		} else {
+			q := dnsMessage.Questions[0]
+			c.log.Debugf("UDP(DNS) %v <-[%v]-> %v: %v %v",
+				lAddrPort.String(), outbound.Name, addrHdr.Dest.String(), q.Name, q.Type,
+			)
+		}
+	} else {
+		// TODO: Set-up ip to domain mapping and show domain if possible.
+		c.log.Infof("UDP %v <-[%v]-> %v",
+			lAddrPort.String(), outbound.Name, addrHdr.Dest.String(),
+		)
+	}
+	ue, err := DefaultUdpEndpointPool.GetOrCreate(lAddrPort, &UdpEndpointOptions{
+		Handler:    c.RelayToUDP(lConn, lAddrPort, isDns),
+		NatTimeout: natTimeout,
+		Dialer:     outbound,
+		Target:     addrHdr.Dest,
+	})
+	if err != nil {
+		return fmt.Errorf("failed to GetOrCreate: %w", err)
+	}
+	//log.Printf("WriteToUDPAddrPort->%v", dest)
+	_, err = ue.WriteToUDPAddrPort(data, addrHdr.Dest)
+	if err != nil {
+		return fmt.Errorf("failed to write UDP packet req: %w", err)
+	}
+	return nil
+}