Node registration fails when host has tunnel/virtual interfaces with non-MAC port_id #496

When running nmos-cpp Node in Docker (host networking), registration with the Registry fails with 400 Bad Request due to IS-04 schema validation failure. The node resource includes a tunnel interface (tunl0) whose port_id is 4 octets instead of the required 6-octet MAC.

• nmos-cpp Node and Registry in separate Docker containers
• Host networking / multiple host_addresses (physical NIC + Docker bridge IPs)
• Linux host with interfaces such as enP7s7, docker0, br-*, tunl0

Registry log

warning: JSON error: schema validation failed at root - no subschema has succeeded ...
{"type":"node","data":{...,"interfaces":[
  {"name":"enP7s7","port_id":"4c-bb-47-81-1f-e8",...},
  {"name":"docker0","port_id":"be-e8-aa-9a-16-c2",...},
  {"name":"br-47379b15f1c5","port_id":"d2-38-b9-d4-7e-80",...},
  {"name":"tunl0","port_id":"00-00-00-00",...}
]}}

Node log

Registration creation error: 400 Bad Request

Discovery and the POST to the Registration API succeed; only schema validation fails.

Root cause

On Linux, host_utils.cpp reads link-layer addresses from AF_PACKET and formats sll_halen bytes as-is. Tunnel interfaces like tunl0 report sll_halen == 4, producing "00-00-00-00".

IS-04 requires port_id to match ^([0-9a-f]{2}-){5}([0-9a-f]{2})$ (6 octets).

make_node_interfaces_port_id() in node_interfaces.cpp falls back to "00-00-00-00-00-00" only when port_id is empty — not when it is non-empty but invalid:

return value::string(!port_id.empty() ? port_id : U("00-00-00-00-00-00"));

Workaround

Restrict host_addresses to the single IP clients should use (e.g. the physical NIC), so tunnel interfaces are excluded:

"host_address": "192.168.6.54",
"host_addresses": ["192.168.6.54"]

Suggested fix

When physical_address is not a valid 6-octet MAC, either:

• normalize to "00-00-00-00-00-00" (already used for missing addresses), or
• exclude the interface from the node resource

This would make container/virtualised deployments more robust without requiring users to know which kernel-reported interfaces have non-MAC link addresses.