Diffusion FreeBSD src repository - subversion rS260508

Simplify inet alias handling code: if we're adding/removing alias which
rS260508
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Description

Simplify inet alias handling code: if we're adding/removing alias which
has the same prefix as some other alias on the same interface, use
newly-added rt_addrmsg() instead of hand-rolled in_addralias_rtmsg().

This eliminates the following rtsock messages:

Pinned RTM_ADD for prefix (for alias addition).
Pinned RTM_DELETE for prefix (for alias withdrawal).

Example (got 10.0.0.1/24 on vlan4, playing with 10.0.0.2/24):

before commit, addition:

got message of size 116 on Fri Jan 10 14:13:15 2014
RTM_NEWADDR: address being added to iface: len 116, metric 0, flags:
sockaddrs: <NETMASK,IFP,IFA,BRD>
 255.255.255.0 vlan4:8.0.27.c5.29.d4 10.0.0.2 10.0.0.255

got message of size 192 on Fri Jan 10 14:13:15 2014
RTM_ADD: Add Route: len 192, pid: 0, seq 0, errno 0, flags:<UP,PINNED>
locks:  inits:
sockaddrs: <DST,GATEWAY,NETMASK>
 10.0.0.0 10.0.0.2 (255) ffff ffff ff

after commit, addition:

got message of size 116 on Fri Jan 10 13:56:26 2014
RTM_NEWADDR: address being added to iface: len 116, metric 0, flags:
sockaddrs: <NETMASK,IFP,IFA,BRD>
 255.255.255.0 vlan4:8.0.27.c5.29.d4 14.0.0.2 14.0.0.255

before commit, wihdrawal:

got message of size 192 on Fri Jan 10 13:58:59 2014
RTM_DELETE: Delete Route: len 192, pid: 0, seq 0, errno 0, flags:<UP,PINNED>
locks:  inits:
sockaddrs: <DST,GATEWAY,NETMASK>
 10.0.0.0 10.0.0.2 (255) ffff ffff ff

got message of size 116 on Fri Jan 10 13:58:59 2014
RTM_DELADDR: address being removed from iface: len 116, metric 0, flags:
sockaddrs: <NETMASK,IFP,IFA,BRD>
 255.255.255.0 vlan4:8.0.27.c5.29.d4 10.0.0.2 10.0.0.255

adter commit, withdrawal:

got message of size 116 on Fri Jan 10 14:14:11 2014
RTM_DELADDR: address being removed from iface: len 116, metric 0, flags:
sockaddrs: <NETMASK,IFP,IFA,BRD>
 255.255.255.0 vlan4:8.0.27.c5.29.d4 10.0.0.2 10.0.0.255

Sending both RTM_ADD/RTM_DELETE messages to rtsock is completely wrong
(and requires some hacks to keep prefix in route table on RTM_DELETE).

I've tested this change with quagga (no change) and bird (*).

bird alias handling is already broken in *BSD sysdep code, so nothing
changes here, too.

I'm going to MFC this change if there will be no complains about behavior
change.

While here, fix some style(9) bugs introduced by r260488
(pointed by glebius and bde).

Sponsored by: Yandex LLC
MFC after: 4 weeks