use SO_REUSEADDR in accept loop

examples/app/app.nim

@@ -239,7 +239,7 @@ proc runApp(serverHostname: string, serverPort: Port, peerId: string,
                                                 srcPort)
     asyncCheck handleServerMessages(serverConn)
     let sock = await punchHole(punchdConn, serverConn, peerId, otherPeerId,
-                               "tcp-nutss")
+                               "tcp-syni")
     echo "connected!"
     await sock.send("ping")
     let msg = await sock.recv(4)

punchd.nim

@@ -48,6 +48,7 @@ proc acceptConnections(punchd: Punchd, ip: IpAddress, port: Port,
   else:
     assert(false, "can only accept TCP or UDP connections")
   let sock = newAsyncSocket(sockType = sockType, protocol = protocol)
+  sock.setSockOpt(OptReuseAddr, true)
   sock.bindAddr(port, $ip)
   sock.listen()
   while true: