traefik/pkg/udp/proxy.go

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package udp
import (
"io"
"net"
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"github.com/rs/zerolog/log"
)
// Proxy is a reverse-proxy implementation of the Handler interface.
type Proxy struct {
// TODO: maybe optimize by pre-resolving it at proxy creation time
target string
}
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// NewProxy creates a new Proxy.
func NewProxy(address string) (*Proxy, error) {
return &Proxy{target: address}, nil
}
// ServeUDP implements the Handler interface.
func (p *Proxy) ServeUDP(conn *Conn) {
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log.Debug().Msgf("Handling connection from %s to %s", conn.rAddr, p.target)
// needed because of e.g. server.trackedConnection
defer conn.Close()
connBackend, err := net.Dial("udp", p.target)
if err != nil {
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log.Error().Err(err).Msg("Error while connecting to backend")
return
}
// maybe not needed, but just in case
defer connBackend.Close()
errChan := make(chan error)
go connCopy(conn, connBackend, errChan)
go connCopy(connBackend, conn, errChan)
err = <-errChan
if err != nil {
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log.Error().Err(err).Msg("Error while serving UDP")
}
<-errChan
}
func connCopy(dst io.WriteCloser, src io.Reader, errCh chan error) {
// The buffer is initialized to the maximum UDP datagram size,
// to make sure that the whole UDP datagram is read or written atomically (no data is discarded).
buffer := make([]byte, maxDatagramSize)
_, err := io.CopyBuffer(dst, src, buffer)
errCh <- err
if err := dst.Close(); err != nil {
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log.Debug().Err(err).Msg("Error while terminating connection")
}
}