OPC UA application is not avaliable by hostname

[atimin]

Describe the bug

If I use @HOSTNAME@ for EndpointUrl the application starts ok, but it isn't available by this endpoint. I steel forced to use IP address.

To Reproduce
Steps to reproduce the behavior:

1. Generate an application with OpcUaProjectBuilder3
2. Replace 0.0.0.0 by @HOSTNAME@
3. Run the app
4. Try to connect with UAExpert

Expected behavior

The client must connect to the application by URL opc.tcp://hostname:port/

Logs
OpcUaServer.log
hostnametcp.pcapng.zip

Environment (please complete the following information):

• OS: Ubuntu-19.10
• Version 3.8.0

Additional context

In the logs one can see that the server binds a socket with IP 127.0.1.1 but UAExpert is looking for IP 127.0.0.1.

In docker-compose network the application binds the external IP:

2019-Nov-29 06:05:37.548068 INF [7f1c3d908700] secure channel endpoint open : Address=<172.30.1.3>, Port=<8889>
2019-Nov-29 06:05:37.548291 INF [7f1c3d908700] open opc ua endpoint : EndpointUrl=<opc.tcp://opcuaserver:8889>, ChannelCount=<0>, SessionCount=<0>

[atimin]

@huebl, why don't we bind IP 0.0.0.0 for the hostname?

[huebl]

The endpoint url must be a valid address (IP address or domain name), because it is used in certificate checking. The address 0.0.0.0 is not a valid address. In version 3 there is no certificate check.

The client use this address during the discovery process to established a connection to the opc ua server. This is not possible with the adress 0.0.0.0.

In version 4, the following behavior was implemented:

#115

That would also be a solution for version 3.

[atimin]

@huebl, I agree with you that 0.0.0.0 is not a valid IP for the endpoint. I mean not to use it for endpoint, but to bind the listening socket with 0.0.0.0 when the application has @hostname@ in EndpointURL. Actually, it is what you do in #115.

I can try to copy this solution into Release 3. Ok?

[huebl]

Yes, you can do that.