MFC r287294:
Use 5 times RTO.Max as the default for the shutdown guard timer
as required by RFC 4960. The sysctl variable can be used to
overwrite this.

MFC r270673:
Announce SCTP support in the kern.features sysctl variables.

MFC r270859:
Enable SCTP support. It runs perfectly fine on a Wandboard quad.

MFC r271204 with manual intervention:
Fix the handling of sysctl variables when used with VIMAGE.
While there do some cleanup of the code.

MFC r271209:
Fix a leak of an address, if the address is scheduled for removal
and the stack is torn down.
Thanks to Peter Bostroem and Jiayang Liu from Google for reporting the
issue.

MFC r271219:
Use SYSCTL_PROC instead of SYSCTL_VNET_PROC.
Suggested by: glebius@

MFC r271221:
Use union sctp_sockstore instead of struct sockaddr_storage. This
eliminates some warnings when building in userland.
Thanks to Patrick Laimbock for reporting this issue.
Remove also some unnecessary casts.
There should be no functional change.

MFC r271228:
Address another warnings reported by Patrick Laimbock when compiling
in userspace. While there, improve consistency.

MFC r271230:
Address warnings generated by the clang analyzer.

Approved by: re (kib)

MFC r269858:

Add support for the SCTP_AUTH_SUPPORTED and SCTP_ASCONF_SUPPORTED
socket options. Add also a sysctl to control the support of ASCONF.

MFC r269527:

Add support for the SCTP_RECONFIG_SUPPORTED and the corresponding
sysctl controlling the negotiation of the RE-CONFIG extension.

MFC r269481:

Add support for the SCTP_PKTDROP_SUPPORTED socket option and
the corresponding sysctl variable.
The default is off, since the specification is not an RFC yet.

MFC r269475:

Add SCTP socket option SCTP_NRSACK_SUPPORTED to control the
NRSACK extension. The default will still be off, since it
it not an RFC (yet).
Changing the sysctl name will be in a separate commit.

MFC r269448:

Add support for the SCTP_PR_SUPPORTED socket option as specified in
http://tools.ietf.org/html/draft-ietf-tsvwg-sctp-prpolicies
Add also a sysctl controlling the default of the end-points.

MFC r269396:

Remove the asconf_auth_nochk sysctl. This was off by default and only
existed to be able to test with non-compliant peers a long time ago.

MFC r263921:

Use SCTP_OVER_UDP_TUNNELING_PORT more consistently.

MFC r263237:

* Provide information in error causes in ASCII instead of
proprietary binary format.
* Add support for a diagnostic information error cause.
The code is sysctlable and the default is 0, which
means it is not sent.

This is joint work with rrs@.

MFC r270673:
Announce SCTP support in the kern.features sysctl variables.

MFC r270859:
Enable SCTP support. It runs perfectly fine on a Wandboard quad.

MFC r271204 with manual intervention:
Fix the handling of sysctl variables when used with VIMAGE.
While there do some cleanup of the code.

MFC r271209:
Fix a leak of an address, if the address is scheduled for removal
and the stack is torn down.
Thanks to Peter Bostroem and Jiayang Liu from Google for reporting the
issue.

MFC r271219:
Use SYSCTL_PROC instead of SYSCTL_VNET_PROC.
Suggested by: glebius@

MFC r271221:
Use union sctp_sockstore instead of struct sockaddr_storage. This
eliminates some warnings when building in userland.
Thanks to Patrick Laimbock for reporting this issue.
Remove also some unnecessary casts.
There should be no functional change.

MFC r271228:
Address another warnings reported by Patrick Laimbock when compiling
in userspace. While there, improve consistency.

MFC r271230:
Address warnings generated by the clang analyzer.

Approved by: re (kib)

MFC r269858:

Add support for the SCTP_AUTH_SUPPORTED and SCTP_ASCONF_SUPPORTED
socket options. Add also a sysctl to control the support of ASCONF.

MFC r269527:

Add support for the SCTP_RECONFIG_SUPPORTED and the corresponding
sysctl controlling the negotiation of the RE-CONFIG extension.

MFC r269481:

Add support for the SCTP_PKTDROP_SUPPORTED socket option and
the corresponding sysctl variable.
The default is off, since the specification is not an RFC yet.

MFC r269475:

Add SCTP socket option SCTP_NRSACK_SUPPORTED to control the
NRSACK extension. The default will still be off, since it
it not an RFC (yet).
Changing the sysctl name will be in a separate commit.

MFC r269448:

Add support for the SCTP_PR_SUPPORTED socket option as specified in
http://tools.ietf.org/html/draft-ietf-tsvwg-sctp-prpolicies
Add also a sysctl controlling the default of the end-points.

MFC r269396:

Remove the asconf_auth_nochk sysctl. This was off by default and only
existed to be able to test with non-compliant peers a long time ago.

MFC r263921:

Use SCTP_OVER_UDP_TUNNELING_PORT more consistently.

MFC r263237:

* Provide information in error causes in ASCII instead of
proprietary binary format.
* Add support for a diagnostic information error cause.
The code is sysctlable and the default is 0, which
means it is not sent.

This is joint work with rrs@.