socket_getifidx - get interface number

       socket_getifidx returns the interface number for a symbolic network interface name (like "eth0" on Linux,
       for example).

       The interface number can be used as scope_id for IPv6 communications on link-local addresses.

       If something goes wrong, socket_getifidx returns -1, setting errno appropriately.

       socket_getifidx - get interface number

socket_getifname(3), socket_connect6(3)

                                                                                              socket_getifidx(3)

#include<libowfat/socket.h>

       int socket_getifidx(const char* ifname);