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ucat.go
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ucat.go
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package main
import (
"flag"
"fmt"
"io"
"log"
"net"
"os"
"os/signal"
"github.com/anacrolix/envpprof"
"github.com/anacrolix/utp"
)
func main() {
defer envpprof.Stop()
listen := flag.Bool("l", false, "listen")
port := flag.Int("p", 0, "port to listen on")
flag.Parse()
var (
conn net.Conn
err error
)
if *listen {
s, err := utp.NewSocket("udp", fmt.Sprintf(":%d", *port))
if err != nil {
log.Fatal(err)
}
defer s.Close()
conn, err = s.Accept()
if err != nil {
log.Fatal(err)
}
} else {
conn, err = utp.Dial(net.JoinHostPort(flag.Arg(0), flag.Arg(1)))
if err != nil {
log.Fatal(err)
}
}
defer conn.Close()
go func() {
sig := make(chan os.Signal, 1)
signal.Notify(sig, os.Interrupt)
<-sig
conn.Close()
}()
writerDone := make(chan struct{})
readerDone := make(chan struct{})
go func() {
defer close(writerDone)
written, err := io.Copy(conn, os.Stdin)
if err != nil {
conn.Close()
log.Fatalf("error after writing %d bytes: %s", written, err)
}
log.Printf("wrote %d bytes", written)
conn.Close()
}()
go func() {
defer close(readerDone)
n, err := io.Copy(os.Stdout, conn)
if err != nil {
log.Fatal(err)
}
log.Printf("received %d bytes", n)
}()
// Technically we should wait until both reading and writing are done. But
// ucat-style binaries terminate abrubtly when read or write is completed,
// and no state remains to clean-up the peer neatly.
select {
case <-writerDone:
case <-readerDone:
}
}