NetworkManager signals global connectivity even when DNS is not yet ready

[Marcel Dopita <m rcel cz>]

Hello,

When trying to setup my desktop environment (Arch Linux & XFCE) I also 
enabled Pidgin (IM client) to launch in XFCE session. I noticed that 
Pidgin doesn't connect immediately after boot but it works either by 
manually forcing it to reconnect or waiting 30-45 seconds for next 
reconnect.

I started debugging the issue and found that Pidgin is starting 
connection attempts based on event from NetworkManager:

(00:09:44) network: Got StateChange from NetworkManager: 70.

I understand that 70 is state "NM_STATE_CONNECTED_GLOBAL" - the global 
network connectivity. I'm no C developer but I added some addition debug 
info to find out that it fails when calling function getaddrinfo() (and 
maybe some other) which returns -2 (meaning "NAME or SERVICE is 
unknown.")
When I put there quick and dirty calls to 'dig' (making A/SRV or any 
other requests), it just fails as well after few seconds with 
"connection timed out; no servers could be reached". However if I 
specify nameserver in the dig call (@x.x.y.y) it works just fine.
As my last test I tried to cat the /etc/resolv.conf file - and indeed, 
nameservers were not there yet.

$ cat /etc/resolv.conf
# Generated by NetworkManager
$ stat /etc/resolv.conf
   File: '/etc/resolv.conf'
   Size: 30             Blocks: 8          IO Block: 4096   regular file
 Device: 802h/2050d     Inode: 3285669     Links: 1
 Access: (0644/-rw-r--r--)  Uid: (    0/    root)   Gid: (    0/    
root)
 Access: 2014-06-04 00:09:42.243614494 +0200
 Modify: 2014-06-04 00:09:18.811462566 +0200
 Change: 2014-06-04 00:09:18.811462566 +0200

 *I rebooted system at 00:09:19

 Nameservers do appears after a short while (I did not test if it's 
couple of ms or s) and point to my router (192.168.1.1). I'm using DHCP, 
IPv4 (and also IPv6 but I enabled it just recently and doesn't seem to 
be the cause). I also switched between two routers and this probably 
isn't the cause.

 I use NetworkManager 0.9.8.10-1 on Arch Linux. My desktop pc is still 
quite fast (CPU i7 3770k, SSD, 32 GB RAM, UEFI) so could that be some 
bug influenced by this? That reminds me that I could attempt to 
duplicate on my way slower laptop.

 Is this something NetworkManager should take care of? Is there anything 
else I could try? (I will report it to the bug tracker if it's a bug.)

PS: I just see it in the log - "NetworkManager state is now 
CONNECTED_GLOBAL" is before "Writing DNS information".


Best regards,
Marcel


LOG:

čen 04 00:09:42 p8z77 NetworkManager[321]: <info> (eno1): DHCPv4 state 
changed preinit -> (null)
čen 04 00:09:43 p8z77 dhcpcd[462]: eno1: leased 192.168.1.100 for 86400 
seconds
čen 04 00:09:43 p8z77 dhcpcd[462]: eno1: adding route to 192.168.1.0/24
čen 04 00:09:43 p8z77 NetworkManager[321]: <info> (eno1): DHCPv4 state 
changed (null) -> bound
čen 04 00:09:43 p8z77 NetworkManager[321]: <info>   address 
192.168.1.100
čen 04 00:09:43 p8z77 NetworkManager[321]: <info>   prefix 24 
(255.255.255.0)
čen 04 00:09:43 p8z77 NetworkManager[321]: <info>   gateway 192.168.1.1
čen 04 00:09:43 p8z77 NetworkManager[321]: <info>   hostname 'p8z77'
čen 04 00:09:43 p8z77 NetworkManager[321]: <info>   nameserver 
'192.168.1.1'
čen 04 00:09:43 p8z77 NetworkManager[321]: <info> Activation (eno1) 
Stage 5 of 5 (IPv4 Configure Commit) scheduled...
čen 04 00:09:43 p8z77 NetworkManager[321]: <info> Activation (eno1) 
Stage 5 of 5 (IPv4 Commit) started...
čen 04 00:09:44 p8z77 dhcpcd[462]: eno1: removing route to 
192.168.1.0/24
čen 04 00:09:44 p8z77 NetworkManager[321]: <info> (eno1): device state 
change: ip-config -> secondaries (reason 'none') [70 90 0]
čen 04 00:09:44 p8z77 NetworkManager[321]: <info> Activation (eno1) 
Stage 5 of 5 (IPv4 Commit) complete.
čen 04 00:09:44 p8z77 NetworkManager[321]: <info> (eno1): device state 
change: secondaries -> activated (reason 'none') [90 100 0]
čen 04 00:09:44 p8z77 NetworkManager[321]: <info> NetworkManager state 
is now CONNECTED_GLOBAL
čen 04 00:09:44 p8z77 NetworkManager[321]: <info> Policy set 'Wired 
connection 1' (eno1) as default for IPv4 routing and DNS.
čen 04 00:09:44 p8z77 NetworkManager[321]: <info> Policy set 'Wired 
connection 1' (eno1) as default for IPv6 routing and DNS.
čen 04 00:09:44 p8z77 NetworkManager[321]: <info> Writing DNS 
information to /usr/bin/resolvconf