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udp_proxy.go
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/
udp_proxy.go
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package net
import (
"net"
"github.com/carvel-dev/kwt/pkg/kwt/net/dstconn"
"github.com/miekg/dns"
)
// https://github.com/LiamHaworth/go-tproxy/blob/master/tproxy_udp.go
type UDPProxy struct {
dstConnFactory dstconn.Factory
conn *net.UDPConn
logTag string
logger Logger
}
func NewUDPProxy(
dstConnFactory dstconn.Factory,
logger Logger,
) *UDPProxy {
return &UDPProxy{
dstConnFactory: dstConnFactory,
logTag: "UDPProxy",
logger: logger,
}
}
func (c *UDPProxy) Serve(startedCh chan struct{}) error {
var err error
addr, err := net.ResolveUDPAddr("udp", "localhost:0")
if err != nil {
return err
}
c.conn, err = net.ListenUDP("udp", addr)
if err != nil {
return err
}
defer c.conn.Close()
startedCh <- struct{}{}
c.logger.Info(c.logTag, "Started proxy on %s", c.conn.LocalAddr())
for {
var b []byte
_, sess, err := dns.ReadFromSessionUDP(c.conn, b)
if err != nil {
c.logger.Error(c.logTag, "Receiving UDP", err)
} else {
go c.serveSess(sess)
}
}
}
func (c *UDPProxy) Addr() net.Addr { return c.conn.LocalAddr() }
func (c *UDPProxy) Shutdown() error {
return nil
}
func (c *UDPProxy) serveSess(sess *dns.SessionUDP) {
c.logger.Info(c.logTag, "Started %s", sess.RemoteAddr())
}