87 lines
1.9 KiB
Go
87 lines
1.9 KiB
Go
package portmapper
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import (
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"fmt"
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"io"
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"net"
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"github.com/ishidawataru/sctp"
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)
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type userlandProxy interface {
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Start() error
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Stop() error
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}
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// ipVersion refers to IP version - v4 or v6
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type ipVersion string
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const (
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// IPv4 is version 4
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ipv4 ipVersion = "4"
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// IPv4 is version 6
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ipv6 ipVersion = "6"
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)
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// dummyProxy just listen on some port, it is needed to prevent accidental
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// port allocations on bound port, because without userland proxy we using
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// iptables rules and not net.Listen
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type dummyProxy struct {
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listener io.Closer
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addr net.Addr
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ipVersion ipVersion
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}
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func newDummyProxy(proto string, hostIP net.IP, hostPort int) (userlandProxy, error) {
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// detect version of hostIP to bind only to correct version
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version := ipv4
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if hostIP.To4() == nil {
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version = ipv6
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}
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switch proto {
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case "tcp":
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addr := &net.TCPAddr{IP: hostIP, Port: hostPort}
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return &dummyProxy{addr: addr, ipVersion: version}, nil
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case "udp":
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addr := &net.UDPAddr{IP: hostIP, Port: hostPort}
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return &dummyProxy{addr: addr, ipVersion: version}, nil
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case "sctp":
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addr := &sctp.SCTPAddr{IPAddrs: []net.IPAddr{{IP: hostIP}}, Port: hostPort}
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return &dummyProxy{addr: addr, ipVersion: version}, nil
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default:
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return nil, fmt.Errorf("Unknown addr type: %s", proto)
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}
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}
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func (p *dummyProxy) Start() error {
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switch addr := p.addr.(type) {
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case *net.TCPAddr:
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l, err := net.ListenTCP("tcp"+string(p.ipVersion), addr)
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if err != nil {
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return err
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}
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p.listener = l
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case *net.UDPAddr:
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l, err := net.ListenUDP("udp"+string(p.ipVersion), addr)
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if err != nil {
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return err
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}
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p.listener = l
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case *sctp.SCTPAddr:
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l, err := sctp.ListenSCTP("sctp"+string(p.ipVersion), addr)
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if err != nil {
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return err
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}
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p.listener = l
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default:
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return fmt.Errorf("Unknown addr type: %T", p.addr)
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}
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return nil
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}
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func (p *dummyProxy) Stop() error {
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if p.listener != nil {
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return p.listener.Close()
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}
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return nil
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}
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