Always check the checksum on incoming packets that have them,
redefining udpcksum to control only generation of checksums

ioctl cmd arg is u_long

copyright typo

lint

put back missing code (from karels@bsdi.com)

4.4BSD snapshot (revision 8.1); add 1993 to copyright

prototype everything

change multicast code so that either SO_REUSEPORT or SO_REUSEADDR
indicates that additional sockets with the same port may be present

prototype icmp_error and fix incorrect call sites

use proper macro to pick out message data (from Andrew Cherenson)

add support for getting udp checksum

replace udp_ttl with sysctl setable ip_defttl

Mostly changes recommended by jch for variable subnets & multiple
IP addresses per physical interface. May require further work.

ip mcast bug fix from mccanne@ee.lbl.gov

(By Sklower) checkpoint the current state of Cherenson's work.

make kernel includes standard

multicast bugfix from arc@sgi.com

multicast changes from lbl

gcc lint

for now, redundantly include errno.h to share source with sys.oldvm

avoid waiting in udp_output

rm user.h; errno.h is in param.h

fix udp_saveopt to copy data to the right place.

fix spl's in udp_usrreq (only as needed, always splx), clear last pcb cache
when detaching

need to change iphlen earlier; icmp_error needs original ip_len; cleanups