Responses to unicast queries not received

[queequac]

Hi, I am currently playing arround with the library to check whether I can use it in production.
Doing so I realized that I do not receive responses for SendUnicastQuery.

var mdns = new MulticastService();
mdns.UseIpv6 = false;
mdns.NetworkInterfaceDiscovered += (s, arg) =>
{
    var query = new Message();
    var question = new Question() { Name = "_googlecast._tcp.local.", Type = DnsType.PTR, Class = DnsClass.ANY };
    query.Questions.Add(question);
    //mdns.SendUnicastQuery("_googlecast._tcp.local.", DnsClass.ANY, DnsType.PTR); // Even though response is on "wire", it never triggers AnswerReceived
    mdns.SendQuery(query); // Works, all responses arrive at the multicast address
};
mdns.AnswerReceived += (s, arg) =>
{
    Debug.WriteLine(arg.Message.ToString());
};
mdns.Start();

I am using Wireshark and I can see queries being sent and also getting responses in both cases on the wire.

Using above code, SendQuery will result in AnswerReceived events (arriving at the multicast address 224.0.0.251), while uncommented SendUnicastQuery will not (even though I can see a response being sent from the device directly to my IP address).

I tried with UWP as well as .NET Framework 4.7.

And idea?

Best, Roland

[queequac]

With the additional line in the PR it works and I can successfully receive answers for those unicast queries on my local endpoint.

Since receivers are a superset of senders in this case, it might be sufficent to dispose that list only.

[queequac]

Slightly off-topic, but I am nosy.

What is the following line good for?

net-mdns/src/MulticastService.cs

Line 36 in b9f2f81

static readonly IPNetwork[] LinkLocalNetworks = new[] { IPNetwork.Parse("169.254.0.0/16"), IPNetwork.Parse("fe80::/10") };

I have looked through your dependencies, and this line is the only reason for the IPNetwork2 package.
Interestingly enough, there is not a single reference to LinkLocalNetworks in the entire solution.

[Raj123456788]

Hello, can you provide a working example for sending query?
mdns.NetworkInterfaceDiscovered += (s, arg) =>
{
var query = new Message();
var question = new Question() { Name = "_googlecast._tcp.local.", Type = DnsType.PTR, Class = DnsClass.ANY };
query.Questions.Add(question);
//mdns.SendUnicastQuery("_googlecast._tcp.local.", DnsClass.ANY, DnsType.PTR); // Even though response is on "wire", it never triggers AnswerReceived
mdns.SendQuery(query); // Works, all responses arrive at the multicast address
};

[queequac]

@Raj123456788 Sorry, I do not understand your request. The code shown in my first comment and which you partly copied is already a working sample for multicast. For unicast you have to comment out the last line and re-enable the line above (SendUnicastQuery). But this does only receive messages when taking over PR #92

[Raj123456788]

@queequac : thanks. Will try that. I have another question: I need to get a list of all services published on a n/w before I start my service(want to avoid publishing a service that is already published).
Problem: I receive the answer to query pretty late by the time I have already sent my publish request. I was trying to find a full proof way to do this. Let me know if you have any suggestions!

[queequac]

Hi @Raj123456788 , could you please stop spamming this thread, since your questions are totally unrelated to the issue? I don't want @richardschneider to close it just because of noise here.

btw, you will find answer to all your questions on the starting page anyway. Your last questions seems to be solvable via ResolveAsync and a cancelation token expiring in maybe 2seconds.

[Raj123456788]

@queequac : My apologies. I will create another issue henceforth. Thanks for the answer.

[Raj123456788]

@queequac: Did you ever get an answer for unicast queries response?

[queequac]

@Raj123456788 Sure, see my PR above... the code changes make it work with unicast queries.
I simply closed the corresponding pull request, since this repo is obviously no longer maintained and noone cares for the PR anyway.

[Raj123456788]

Hi @queequac : If you have any idea can you please answer my question #108
Thanks!

[Jeekate]

I met the same issue contacting to my esp8266, thanks for your PR!!