Issue with iwd 1.3 + systemd-resolved + iwd's built-in network configuration not adding DNS servers

Issue with iwd 1.3 + systemd-resolved + iwd's built-in network configuration not adding DNS servers

[caljorden]

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Hello everyone,

I have hit an issue with iwd 1.3 on Arch Linux (also reported in arch bug tracker https://bugs.archlinux.org/task/64855) where with a minimal iwd configuration using the built-in network configuration and systemd-resolved for DNS, iwd 1.3 does not properly add the DNS servers to systemd-resolved.

I saw this first on my laptop, which I temporarily worked around by simply disabling the internal network configuration and manually running dhclient.  But, once I updated Arch on my workstation, and hit the same issue, I thought I should report it.  I opened the bug in Arch's bug system, not knowing (and still not entirely sure) if the issue is specific to Arch Linux or not.

I found that by reverting the commit 930528e35, and removing one call to the added function that had been added after this patch was applied, the problem went away.

I am not sure if this is some bad interaction between iwd and systemd-resolved in Arch, or some wider issue.  I have hit this issue on my home network using WPA2-PSK, as well as my work network (WPA2 Enterprise), so I do not think this is related to the network type of the connection.  My iwd/main.conf file looks like this:

---------------
[General]
EnableNetworkConfiguration=true

[Network]
NameResolvingService=systemd
---------------

Thank you,

Caleb Jorden

Re: Issue with iwd 1.3 + systemd-resolved + iwd's built-in network configuration not adding DNS servers

[carbonchauvinist]

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I've run into this issue as well with 1.3. I'm using iwd + systemd-resolved (using iwd to manage the network, i.e. no systemd-networkd at play here).

From what I can tell it's due to the fact that commit 930528e35 appends domain names as routing-only domains (i.e. prepends with "~"). I have "lan" as the domain value in my router and this is in turn added as "~lan" when viewing the output with resolvectl status. This changes the way  systemd-resolved sets the "DefaultRoute" value and causes it to be false instead of true.

Currently I can either manually, and non-permanently, set the DefaultRoute to true on the link in order to get name resolution (i.e.: `# resolvectl default-route wlan0 1`) or I can remove the domain designation from my router/dhcp server.

I wonder if the goal was to add the domains as routing-only domains instead of search-domains? (https://www.freedesktop.org/software/systemd/man/systemd.network.html#Domains=)

Because I'm not using systemd-networkd I don't know/see a way to override the DefaultRoute value permanently, though I obviously could be missing something.

Re: Issue with iwd 1.3 + systemd-resolved + iwd's built-in network configuration not adding DNS servers

[carbonchauvinist]

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> I wonder if the goal was to add the domains as routing-only domains instead of
> search-domains?
> (https://www.freedesktop.org/software/systemd/man/systemd.network.html#Domains=)

Typo here, I was wondering if the goal was to add the domain as search-domains instead of routing-only-domains.

Re: Issue with iwd 1.3 + systemd-resolved + iwd's built-in network configuration not adding DNS servers

[Denis Kenzior]

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Hi Caleb,

On 12/16/19 1:48 AM, caljorden(a)hotmail.com wrote:
> Hello everyone,
> 

<snip>

> 
> I found that by reverting the commit 930528e35, and removing one call to the added function that had been added after this patch was applied, the problem went away.

Can you try the attached patch on top of pristine 1.3 and tell me if it 
fixes your issue?

Regards,
-Denis

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From 6b5af799118a48461c5b0d58d74bed80e5a8abff Mon Sep 17 00:00:00 2001
From: Denis Kenzior <denkenz@gmail.com>
Date: Mon, 16 Dec 2019 16:15:35 -0600
Subject: [PATCH] resolve: Don't try to set routing domains

The intent was to treat all domains as search domains.
---
 src/resolve.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/resolve.c b/src/resolve.c
index 1d9bbe0ad659..32bc52bad577 100644
--- a/src/resolve.c
+++ b/src/resolve.c
@@ -221,7 +221,7 @@ static void resolve_systemd_add_domain_name(uint32_t ifindex,
 	if (!message)
 		return;
 
-	routing_domain = true;
+	routing_domain = false;
 
 	l_dbus_message_set_arguments(message, "ia(sb)", ifindex,
 						1, domain_name, routing_domain);
-- 
2.21.0

Re: Issue with iwd 1.3 + systemd-resolved + iwd's built-in network configuration not adding DNS servers

[carbonchauvinist]

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Thanks Denis.

I can confirm the patch fixes the reported issue for me. iwd now adds the domain as a search domain (without the prepended tilde) which keeps the DefaultRoute value true and means I am able to perform lookups as expected. Thank you.

Re: Issue with iwd 1.3 + systemd-resolved + iwd's built-in network configuration not adding DNS servers

[caljorden]

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Hi Denis,

Thanks for sending that patch out.  I can confirm that this fixes the problem when applied to the pristine 1.3 code.

Is this critical enough to release a 1.4 update, or perhaps a 1.3.1?

Thanks again!

- Caleb

Re: Issue with iwd 1.3 + systemd-resolved + iwd's built-in network configuration not adding DNS servers

[Denis Kenzior]

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Hi Caleb,

On 12/16/19 11:07 PM, caljorden(a)hotmail.com wrote:
> Hi Denis,
> 
> Thanks for sending that patch out.  I can confirm that this fixes the problem when applied to the pristine 1.3 code.

Thanks for testing!  I've pushed out this fix upstream as 295e42f87a8f 
("resolve: Don't try to set routing domains")

> 
> Is this critical enough to release a 1.4 update, or perhaps a 1.3.1?

Indeed.  We're investigating a different issue (with PEAP + MSCHAPv2) 
reported against 1.3.  Once we have that resolved we will try to get a 
1.4 out very soon.

Regards,
-Denis

Regards,
-Denis