[WireGuard] [PATCH] persistent keepalive: start sending immediately

[William]

On Fri, Jul 08, 2016 at 02:34:12PM +0200, Jason A. Donenfeld wrote:
> Rather than only start sending the persistent keepalive packets when the
> device first sends data, this changes it to send the packets immediately
> on `ip link set up`. This makes things generally seem more stateless,
> since the administrator does not have to manually ping the endpoint.
> 
> Of course, if you have a lot of peers and all of them have persistent
> keepalive enabled, this could cause a lot of unwanted immediate traffic.
> On the other hand, if all of those peers are at some point going to be
> sending packets, this would happen anyway. I suppose the moral of the
> story is that persistent keepalive is a feature really just for clients
> behind NAT, not for servers, and it should be used sparingly, which is
> why we've set it off by default in the first place.
> ---
> 
> Hi list,
> 
> I haven't merged this yet, and I'm debating whether it's something we want.
> I'm open to all opinions here, so feed back would be most welcome.

Hi all,

just to have a trace here of what I pointed out on IRC:
In the case of making a peer accessible through a NAT "I don't want to
have to manually ping things from the client I'm trying to ssh to in the
first place".

> 
> Thanks,
> Jason
> 
> 
>  src/config.c | 5 ++++-
>  src/device.c | 2 ++
>  2 files changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/src/config.c b/src/config.c
> index 767d31a..910c31b 100644
> --- a/src/config.c
> +++ b/src/config.c
> @@ -106,8 +106,11 @@ static int set_peer(struct wireguard_device *wg, void __user *user_peer, size_t
>  	if (in_peer.persistent_keepalive_interval != (uint16_t)-1) {
>  		if (in_peer.persistent_keepalive_interval && (in_peer.persistent_keepalive_interval < 10 || in_peer.persistent_keepalive_interval > 3600))
>  			ret = -EINVAL;
> -		else
> +		else {
> +			if (!peer->persistent_keepalive_interval && in_peer.persistent_keepalive_interval && netdev_pub(wg)->flags & IFF_UP)
> +				socket_send_buffer_to_peer(peer, NULL, 0, 0);
>  			peer->persistent_keepalive_interval = in_peer.persistent_keepalive_interval;
> +		}
>  	}
>  
>  	if (netdev_pub(wg)->flags & IFF_UP)
> diff --git a/src/device.c b/src/device.c
> index 120f8c9..198368f 100644
> --- a/src/device.c
> +++ b/src/device.c
> @@ -40,6 +40,8 @@ static int open_peer(struct wireguard_peer *peer, void *data)
>  	socket_set_peer_dst(peer);
>  	timers_init_peer(peer);
>  	packet_send_queue(peer);
> +	if (peer->persistent_keepalive_interval)
> +		socket_send_buffer_to_peer(peer, NULL, 0, 0);
>  	return 0;
>  }
>  
> -- 
> 2.9.0
> 
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-- 
William