[avahi] Receive mDNS annoucnements

[Jon Fitt]

I'm not able to get a record browser doing what I want. I have modified client-browse-services.c to make a record browser instead of a service browser. 
avahi_record_browser_new(client, AVAHI_IF_UNSPEC, AVAHI_PROTO_UNSPEC, "BRN30055C232008.local", AVAHI_DNS_CLASS_IN, AVAHI_DNS_TYPE_A, 0, browse_callback, client)

I know my printer BRN30055C232008.local is making DNS A announcements because I can see them in Wireshark. However I just get CACHE_EXHAUSTED then seg fault. I've tried different host names with and without the domain and sometimes that will get CACHE_EXHAUSTED, ALL_FOR_NOW instead of seg fault. I've also tried the hostnames with and without the domain of various Apple devices I know are making DNS A announcements.
I know that my printer is also making _http._tcp service announcements as "Brother DCP-8011DN". If I pass "Brother DCP-8011DN" as the host name then I get:CACHE_EXHAUSTEDDNS failure: NXDOMAIN
That's the closest I get to an outcome. It's worrying because I don't only want to get the DNS A records of hosts that also advertise services, I just want to grab (preferably all) DNS A records that the daemon has in memory.
Regards,
Jonathan 

     On Tuesday, 25 November 2014, 16:38, Michael Jones <avahi at jonesmz.com> wrote:
   

 


In the avahi-client C-API there is the concept of a Service Browser and a Record Browser. Service Browser sounds like what you are using now:

| AvahiServiceBrowser* avahi_service_browser_new | ( | AvahiClient *  | client, |
|  |  | AvahiIfIndex  | interface, |
|  |  | AvahiProtocol  | protocol, |
|  |  | const char *  | type, |
|  |  | const char *  | domain, |
|  |  | AvahiLookupFlags  | flags, |
|  |  | AvahiServiceBrowserCallback  | callback, |
|  |  | void *  | userdata  |
|  | ) |


The type being for example _http._tcp. Whereas a Record Browser looks like this:

| AvahiRecordBrowser* avahi_record_browser_new | ( | AvahiClient *  | client, |
|  |  | AvahiIfIndex  | interface, |
|  |  | AvahiProtocol  | protocol, |
|  |  | const char *  | name, |
|  |  | uint16_t  | clazz, |
|  |  | uint16_t  | type, |
|  |  | AvahiLookupFlags  | flags, |
|  |  | AvahiRecordBrowserCallback  | callback, |
|  |  | void *  | userdata  |
|  | ) |



Hi Jonathan,

    Yea, that looks familiar. As far as I remember, the qtzeroconf (either the original, or my fork) doesn't use the avahi_record_browser api.

    I'd be happy to collaborate with you on building support for that.

    Should be pretty straight forward. Mostly we'll just need to copy and modify the ServiceBrowser class, I think. 

--Mike

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