(default 1) disables PMTUD globally. Although PMTUD can be disabled in
the standard case by locking the MTU on a static route (including the
default route), this method doesn't work in the face of dynamic routing
protocols like gated.
flag means that there is more data to be put into the socket buffer.
Use it in TCP to reduce the interaction between mbuf sizes and the
Nagle algorithm.
Based on: "Justin C. Walker" <justin@apple.com>'s description of Apple's
fix for this problem.
`len = min(so->so_snd.sb_cc, win) - off;'. min() has type u_int
and `off' has type int, so when min() is 0 and `off' is 1, the RHS
overflows to 0U - 1 = UINT_MAX. `len' has type long, so when
sizeof(long) == sizeof(int), the LHS normally overflows to to the
correct value of -1, but when sizeof(long) > sizeof(int), the LHS
is UINT_MAX.
Fixed some u_long's that should have been fixed-sized types.
of the TCP payload. See RFC1122 section 4.2.2.6 . This allows
Path MTU discovery to be used along with IP options.
PR: problem discovered by Kevin Lahey <kml@nas.nasa.gov>
represent in the TCP header. The old code did effectively:
win = min(win, MAX_ALLOWED);
win = max(win, what_i_think_i_advertised_last_time);
so if what_i_think_i_advertised_last_time is bigger than can be
represented in the header (e.g. large buffers and no window scaling)
then we stuff a too-big number into a short. This fix reverses the
order of the comparisons.
PR: kern/4712
cache lines. Removed the struct ip proto since only a couple of chars
were actually being used in it. Changed the order of compares in the
PCB hash lookup to take advantage of partial cache line fills (on PPro).
Discussed-with: wollman
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.
gcc only inlines memcpy()'s whose count is constant and didn't inline
these. I want memcpy() in the kernel go away so that it's obvious that
it doesn't need to be optimized. Now it is only used for one struct
copy in si.c.
1) Set the persist timer to help time-out connections in the CLOSING state.
2) Honor the keep-alive timer in the CLOSING state.
This fixes problems with connections getting "stuck" due to incompletion
of the final connection shutdown which can be a BIG problem on busy WWW
servers.
have to decide whether to send a CC or CCnew option in our SYN segment
depending on the contents of our TAO cache. This decision has to be
made once when the connection starts. The earlier code delayed this
decision until the segment was assembled in tcp_output() and
retransmitted SYN segments could have different CC options.
Reviewed by: Richard Stevens, davidg, wollman
a few new wrinkles for MTU discovery which tcp_output() had better
be prepared to handle. ip_output() is also modified to do something
helpful in this case, since it has already calculated the information
we need.
and gated on `options MTUDISC' in the source. It is also practically
untested becausse (sniff!) I don't have easy access to a network with
an MTU of less than an Ethernet. If you have a small MTU network,
please try it and tell me if it works!
to be sent, just clean up and return ENOBUFS rather than silently
proceeding without sending any of the data. This makes it consistent
with the `#ifdef notyet' case immediately above.
Reviewed by: Andras Olah <olah@freebsd.org>
Obtained from: Lite-2
Bob Braden <braden@isi.edu>.
NB: This has not had David's TCP ACK hack re-integrated. It is not clear
what the correct solution to this problem is, if any. If a better solution
doesn't pop up in response to this message, I'll put David's code back in
(or he's welcome to do so himself).
