RFR(s): 8228580: DnsClient TCP socket timeout

[Florian Weimer]

* Pavel Rappo:

>> On 4 Sep 2019, at 18:38, Florian Weimer <fweimer at redhat.com> wrote:
>> 
>> <snip>
>> 
>> Maybe I'm mistaken, but I think this:
>> 
>> 692     Tcp(InetAddress server, int port, int timeout) throws IOException {
>> 693         sock = new Socket(server, port);
>> 694         sock.setTcpNoDelay(true);
>> 695         out = new java.io.BufferedOutputStream(sock.getOutputStream());
>> 696         in = new java.io.BufferedInputStream(sock.getInputStream());
>> 697         timeoutLeft = timeout;
>> 698     }
>> 
>> creates the TCP socket and connects it.  This is a potentially blocking
>> operation as well.  
>
> You are right, it definitely is a blocking operation. I missed it. I was focused on
>
>     712         sock.setSoTimeout(timeoutLeft);
>
> So I'd suggest we use explicit connect with timeout
>
>     java.net.Socket#connect(java.net.SocketAddress, int)
>
> Are you okay with that?

Sure.  You should use a larger timeout than the initial UDP timeout,
though.  Can you compute the maximum amount of time the UDP code would
wait for reply and use that?  Or is that the timeoutLeft value?

Thanks,
Florian