Enhancement of "redirect" function, adding support for MacOS

Added the function of "MacOS" FreeBSD firewall traffic forwarding and resolving destination address
example:
"inbounds": [
{
"listen": "127.0.0.1",
"port": 1122,
"protocol": "dokodemo-door",
"tag": "dokodemo",
"settings": {
"network": "tcp",
"followRedirect": true,
"userLevel": 0
},
"streamSettings": {
"sockopt": {
"tproxy": "Redirect"
}
}
}
]

还原#1189 提交

transport/internet/udp/hub_darwin.go

@@ -0,0 +1,46 @@
+//go:build darwin
+// +build darwin
+
+package udp
+
+import (
+	"bytes"
+	"encoding/gob"
+	"io"
+
+	"github.com/xtls/xray-core/common/errors"
+	"github.com/xtls/xray-core/common/net"
+	"github.com/xtls/xray-core/transport/internet"
+)
+
+// RetrieveOriginalDest from stored laddr, caddr
+func RetrieveOriginalDest(oob []byte) net.Destination {
+	dec := gob.NewDecoder(bytes.NewBuffer(oob))
+	var la, ra net.UDPAddr
+	dec.Decode(&la)
+	dec.Decode(&ra)
+	ip, port, err := internet.OriginalDst(&la, &ra)
+	if err != nil {
+		return net.Destination{}
+	}
+	return net.UDPDestination(net.IPAddress(ip), net.Port(port))
+}
+
+// ReadUDPMsg stores laddr, caddr for later use
+func ReadUDPMsg(conn *net.UDPConn, payload []byte, oob []byte) (int, int, int, *net.UDPAddr, error) {
+	nBytes, addr, err := conn.ReadFromUDP(payload)
+	var buf bytes.Buffer
+	enc := gob.NewEncoder(&buf)
+	udpAddr, ok := conn.LocalAddr().(*net.UDPAddr)
+	if !ok {
+		return 0, 0, 0, nil, errors.New("invalid local address")
+	}
+	if addr == nil {
+		return 0, 0, 0, nil, errors.New("invalid remote address")
+	}
+	enc.Encode(udpAddr)
+	enc.Encode(addr)
+	var reader io.Reader = &buf
+	noob, _ := reader.Read(oob)
+	return nBytes, noob, 0, addr, err
+}

transport/internet/udp/hub_other.go

@@ -1,5 +1,5 @@
-//go:build !linux && !freebsd
-// +build !linux,!freebsd
+//go:build !linux && !freebsd && !darwin
+// +build !linux,!freebsd,!darwin
 
 package udp