Re: [PATCH 9/9] hs20-client: Add 1 second sleep after IP is detected to allow external config to complete.

On 02/16/2020 06:33 AM, Jouni Malinen wrote:
> On Fri, Feb 07, 2020 at 01:10:17AM -0800, [email protected] wrote:
>> For instance, setting up VRFs and such might take a small bit of extra time.
>
> What is VRF and why would a user space tool on a station device need to
> know about that?

VRF is 'virtual router function', or something like that.  It is somewhat similar
in use to network name spaces and routing table rules.  It allows multiple wlans
to route to the same AP, for instance.

>
>> diff --git a/hs20/client/oma_dm_client.c b/hs20/client/oma_dm_client.c
>> @@ -1211,6 +1211,8 @@ int cmd_oma_dm_sim_prov(struct hs20_osu_client *ctx, const char *url)
>>   	if (wait_ip_addr(ctx->ifname, 15) < 0) {
>>   		wpa_printf(MSG_INFO, "Could not get IP address for WLAN - try connection anyway");
>>   	}
>> +	/* Give a bit more time in case external tools are still configuring things, like VRF. */
>> +	os_sleep(1, 0);
>>   	write_summary(ctx, "OMA-DM SIM provisioning");
>
> Wouldn't it make more sense to do whatever is needed within
> wait_ip_addr() instead of copy pasting this into every location where
> wait_ip_addr() is called? That said, I'm not convinced waiting one
> second is the thing that should happen here.
>
> What exactly are the cases where you have needed to wait longer after
> the IP address has been assigned? Maybe wait_ip_addr() (or
> wpa_supplicant before indicating STATUS command ip_address field) should
> wait for those exact things rather than adding a hardcoded wait for one
> second.

My testing tool uses a custom DHCP script and sets the IP address, route,
and DNS per interface.  Part of this also optionally sets up VRF or routing
table rules to allow many interfaces to talk to the same AP properly.

Since I want to have the OSU client use the DNS given out by the AP
(and not whatever eth0 management face is already using), then that is why
I want to have the separate file option to hold the DNS entry per wlan.

In testing, I saw cases where connectivity to the hs20 web servers timed
out some of the time.  I thought maybe it was a race in setting up the vrf, but in truth, I am
not sure that is the root cause.  Probably no one else needs this particular
behaviour, so you can drop that 1 sec sleep patch and probably that works fine
for everyone else.

Since normal frameworks are probably not going to auto-generate the DNS file
or set up fancy routing rules, it is probably not worth mucking with the wait-for-ip
logic.

Thanks,
Ben


-- 
Ben Greear <[email protected]>
Candela Technologies Inc  http://www.candelatech.com