A complete rationale and discussion is given in this message
and the resulting discussion:
http://docs.freebsd.org/cgi/mid.cgi?4177C8AD.6060706
Note that this commit removes only the functional part of T/TCP
from the tcp_* related functions in the kernel. Other features
introduced with RFC1644 are left intact (socket layer changes,
sendmsg(2) on connection oriented protocols) and are meant to
be reused by a simpler and less intrusive reimplemention of the
previous T/TCP functionality.
Discussed on: -arch
originated on RELENG_4 and was ported to -CURRENT.
The scoreboarding code was obtained from OpenBSD, and many
of the remaining changes were inspired by OpenBSD, but not
taken directly from there.
You can enable/disable sack using net.inet.tcp.do_sack. You can
also limit the number of sack holes that all senders can have in
the scoreboard with net.inet.tcp.sackhole_limit.
Reviewed by: gnn
Obtained from: Yahoo! (Mohan Srinivasan, Jayanth Vijayaraghavan)
lastest rev of the spec. Use an explicit flag for Fast Recovery. [1]
Fix bug with exiting Fast Recovery on a retransmit timeout
diagnosed by Lu Guohan. [2]
Reviewed by: Thomas Henderson <thomas.r.henderson@boeing.com>
Reported and tested by: Lu Guohan <lguohan00@mails.tsinghua.edu.cn> [2]
Approved by: Thomas Henderson <thomas.r.henderson@boeing.com>,
Sally Floyd <floyd@acm.org> [1]
In order to ensure security and functionality, RFC 1948 style
initial sequence number generation has been implemented. Barring
any major crypographic breakthroughs, this algorithm should be
unbreakable. In addition, the problems with TIME_WAIT recycling
which affect our currently used algorithm are not present.
Reviewed by: jesper
generation scheme. Users may now select between the currently used
OpenBSD algorithm and the older random positive increment method.
While the OpenBSD algorithm is more secure, it also breaks TIME_WAIT
handling; this is causing trouble for an increasing number of folks.
To switch between generation schemes, one sets the sysctl
net.inet.tcp.tcp_seq_genscheme. 0 = random positive increments,
1 = the OpenBSD algorithm. 1 is still the default.
Once a secure _and_ compatible algorithm is implemented, this sysctl
will be removed.
Reviewed by: jlemon
Tested by: numerous subscribers of -net
is an application space macro and the applications are supposed to be free
to use it as they please (but cannot). This is consistant with the other
BSD's who made this change quite some time ago. More commits to come.
- eliminate the fast/slow timeout lists for TCP and instead use a
callout entry for each timer.
- increase the TCP timer granularity to HZ
- implement "bad retransmit" recovery, as presented in
"On Estimating End-to-End Network Path Properties", by Allman and Paxson.
Submitted by: jlemon, wollmann
This will make a number of things easier in the future, as well as (finally!)
avoiding the Id-smashing problem which has plagued developers for so long.
Boy, I'm glad we're not using sup anymore. This update would have been
insane otherwise.
