Second mdns instance cannot be started

[BbIKTOP]

Second mdns instance cannot be created becuase listening sockel listen on inaddr_any (0)
To be able to create second instance you'd probably need to replace
lib/ESP8266mDNS/src/LEAmDNS_Helpers.cpp

if (m_pUDPContext->listen(IP4_ADDR_ANY, DNS_MQUERY_PORT))
to something like

if (m_pUDPContext->listen(ip_2_ip4(&m_netif->ip_addr), DNS_MQUERY_PORT))
To prevent err -8 ERR_USE on second instance

[d-a-v]

@BbIKTOP Thanks for the hint !
Did you modify your sources and checked if you can have both instances running with such fix ?

[BbIKTOP]

@d-a-v yes, sure, I changed this single line and now i have 2 instances running. Also i connected 2 computers, one to the esp ap and another one to the same wifi that esp sta connected to, and observe esp mdns via dns-sd and tcpdump on both computers

[lorol]

Hi @BbIKTOP there is a little side effect, probably only for me :) . I use a 2nd interface (an extra WiFI adapter) to get all OTA ports populated to Arduino IDE Win10. The LAN (current iface) has troubles (because I use WoL, I guess) so now the ESPs cannot find their way. Just FYI.

[BbIKTOP]

@lorol Sorry, could you explain further? I can't see how is it related - I mean, what is the influence to the OTA, when mDNS listens on it's interface only? And what exact troubles do you have?

[lorol]

@BbIKTOP it is my particular problem of having 2x network adapters (2x IPs) on same subnet - on the PC I run ArduinoIDE from. I guess, your implementation is fully correct it just doesn't work for me and I will hold on it. My problem is in PC setup somewhere that makes original LAN adapter inconsistently "seeing" the ESPs on my network. I just plugged an extra WiFi USB stick (no time to fix why the LAN adapter have issues) and all was OK until this change.
Anyway ... again this is another problem but before it worked now it doesn't. That's all.

You can disregard it, no problem. Hope no one else will have weird needs :)

Just from curiosity, why the original code several years was exposing IP4_ADDR_ANY - any reason (other than your testing convenience) to be not limited to &m_netif->ip_addr?

[BbIKTOP]

Didn’t get it but ok. I suppose, nobody tried to use it on both interfaces simultaneously, i mean on sta and ap. I. e. nobody tried to run 2 instances yet. Have no another versions

[lorol]

Hi @BbIKTOP FYI, you may be interested to follow these:
#7262
#7266