• Fill in the correct rtm_index for RTM_ADD and RTM_CHANGE messages.

• Allow RTM_CHANGE to change a number of route flags as specified by RTF_FMASK.

• The unused rtm_use field in struct rt_msghdr is redesignated as rtm_fmask field to communicate route flag changes in RTM_CHANGE messages from userland. The use count of a route was moved to rtm_rmx a long time ago. For source code compatibility reasons a define of rtm_use to rtm_fmask is provided.

These changes faciliate running of multiple cooperating routing
daemons at the same time without causing undesired interference.
Open[BGP|OSPF]D make use of these features to have IGP routes
override EGP ones.

Obtained from: OpenBSD (claudio@)
MFC after: 3 days