Unix socket and interfaces

[mastergt]

What is the problem this feature will solve?

Im need to write DHCP server, based on NODEJS.(linux)
clients can send DHCP DISCOVER packet from a number of interfaces:
vlan1, vlan100, vxlan1001 ....
Current problem - i cant determine interface name, packet received from, to match network to lease IP address according to this interface. I receive rinfo:
rinfo: {'0.0.0.0','ipv4',67,300}

What is the feature you are proposing to solve the problem?

https://nodejs.org/api/dgram.html
Based on documentation - we have rinfo object:

Please add here another property:

looks like:
rinfo: {'0.0.0.0','ipv4',67,300,'vlan10'}

What alternatives have you considered?

Unfortunately, I couldn't find an acceptable solution and was forced to write DHCP server using PERL.

[bnoordhuis]

Unlikely to happen because looking that up per datagram would be prohibitively slow (requires a call to if_indextoname or ioctl(SIOCGIFNAME) - too much overhead.)

I guess node could add the interface index (not its name) from the sockaddr struct to rinfo and then give you a method to look up the corresponding name, but don't expect anyone to implement that for you, you'll have to write that yourself. Be prepared your pull request may end up getting rejected because it's deemed too niche or not portable enough.