Wrong type for field ifindex in struct iface

[rene-d]

In Linux kernel, the ifindex is stored into a int variable (aka. 4 bytes). And can take values greater than 65535 (I don't know since which version...).

The ifindex field in the structure iface (ifvc.h) is a u_short, and big indices cannot fit. It occurs especially on servers running tests that create/destroy bridges and virtual interfaces.

smcroute exits with "Failed adding VIF for iface ..." message : it tries to set an option on a inexistant interface (2000 instead of 67536 for example).

[rene-d]

Nota: I haven't tried to change the type and recompile...

[troglobit]

The most obvious fix, as mentioned in #71, is to simply change from u_short to int. However, I just noticed we use if_nametoindex(3), which returns an unsigned int ... the kernel itself seems to use int for every relevant internal struct, so I propose changing to int.

[troglobit]

I've looked into this a bit further now and I don't see any other code, than the struct iface ifindex, that need to be changed.

I'm pushing a fix for that now, which will cause GitHub to automatically close this issue. Please, if you can @rene-d, test the fix. If it doesn't work we'll reopen this issue again. Thanks!

[rene-d]

Ok thanks! I will test tomorrow.

[rene-d]

Yes! the fix (type changed from u_short to int) solves the problem of interface indices greater than 2^16.

The test passes with ifindex below and above 65536. Without this fix, it passes with ifindex<65536 and fails otherwise.

[troglobit]

@rene-d Awesome, thank you for getting back on this! 🎉 😃

[rene-d]

Thank you for having dealt with my issue so fast ;-)

I have look for ifindex in the Linux kernel: sometimes it's typed u32, sometimes int. In net/core/dev.c line ~8034 in function dev_new_index(), ifindex is a strictly positive int (aka between 1 and 2^31-1).