Bug: if hostname cannot be resolved, then change external links to ip-address

[markbaaijens]

External links to LMS, Transmission en SyncThing are hard-coded pointing to hostname rpms, (local) DNS will take care to resolve them to a real ip-address. But sometimes, the local DNS denies resolving hostnames. Thus, the external links must point to a ip-address, which is the address of the Pi it self to be functional.

Steps to reproduce

• on a network where hostname cannot be resolved to an ip-address
• click on LogitechMediaServer on front-end/Home-page
• see that rpms tries to open http://rpms:9002, but will fail obviously

Notes

Find out a way to reproduce this in a network with proper/working (local) DNS. But is there a way? From the host it self, try ping (hostname). This probably always returns a valid result b/c the host it self will resolve the name to an ip-address.

If there is really no way to determine that DNS is not working correctly, always transform the external links to ip-address without prior testing.

Detect if local DNS is working

nslookup rpms | grep "SERVFAIL

Tasks

• implement in existing function logic/GetHostName:
  • if hostname cannot be resolved => ip-address

Related to https://github.com/markbaaijens/rpmusicserver/issues/120

[markbaaijens]

Some research to be done (on the host (rpms) it self in the problematic network):

• login by ssh on rpms
• retrieve the ip-address of the host:
  • hostname -I | awk '{print $1}'
• nmap rpms
• nmap [ip-address]
• nslookup rpms
• nslookup [ip-address]

[markbaaijens]

Apparantly, the code does not work. When executed nslookup rpms | grep "SERVFAIL on a site with failing local DNS, the respons is what is expected. But the built in code in logic.py, does not return the wanted effect, it is not clear why. What is needed here is debugging on site.