CVS commit: [netbsd-9] src/sys/net

["Martin Husemann" <martin%netbsd.org@localhost>]

Module Name:    src
Committed By:   martin
Date:           Thu Nov 14 15:34:35 UTC 2019

Modified Files:
        src/sys/net [netbsd-9]: if_loop.c

Log Message:
Pull up following revision(s) (requested by msaitoh in ticket #424):

        sys/net/if_loop.c: revision 1.108
        sys/net/if_loop.c: revision 1.109

 Fix IP broadcast + checksum offload problem.

 When a machine sends a IP broadcast packet to an Ethernet interface that the
checksum offload flags are set, the packet goes through ether_output() ->
looutput() and the offload flags is cleared without calculating the checksum.

And then, ip_input() calculate the packet's checksum because it's csum_flags is
zero. It regard as bad checksum and it's dropped because the packet's ifp
is s not lo0's. Fixes this bug by passing csum_flags as "calculated and good"
when IN_LOOPBACK_NEED_CHECKSUM() is false. Advised by ryo@.

 This problem was seen when "routed -s" was used and the machine's interface's
offload flags were set. bad checksum field of "netstat -s" was increased every
30 seconds.

 Fix comment.


To generate a diff of this commit:
cvs rdiff -u -r1.107 -r1.107.2.1 src/sys/net/if_loop.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.