Detection of interface type

Olsrd will try to register what interfaces are WLAN interfaces to be able to use different HELLO intervals on wireless and wired interfaces. Since mobility is assumed to be low on wired links, one can reduce control-traffic overhead by using a larger HELLO interval on wired interfaces. These intervals can be set in the configuration file.

To detect if an interface is to be registered as wireless, a request for WLAN information ioctl, SIOCGIWNAME, is issued to the driver. If it returns information other than NULL, the interface is set to be wireless. This, however, does not work as desired when using hardware such as Ethernet-to-WLAN bridges.

When olsrd selects the interface to use in a route, interfaces will be prioritized based on a metric set in the configuration process. As of now this metric is set to 1 if the interface is detected to be a WLAN interface, and 0 if not. This means that if a node has two symmetric links to a neighbor node, one over a WLAN interface and one over an Ethernet interface, then the Ethernet interface will be chosen when setting up the route.