hunting for an MSS option to clamp. The previous code assumed that at least
one more byte of options (such as a TCPOPT_EOL) would follow the MSS
option; now, we allow the MSS option to end on the last byte of the
TCP header.
Packets have been observed "in the wild" with a TCP header length of
'6' (24 bytes.. 20 bytes fixed header, 4 bytes options) with a 4-byte
MSS option exactly filling the 4 bytes of options payload and no
following TCPOPT_EOL.
RFC793 is quite explicit that the EOL byte:
" .. need only be used if the end of the options would not
otherwise coincide with the end of the TCP header."
"In rare cases when there is no room for ip options ip_insertoptions()
can fail and corrupt a header length. Initialize len and check what
ip_insertoptions() returns."
This merge changes the device switch tables from static array to
dynamically generated by config(8).
- All device switches is defined as a constant structure in device drivers.
- The new grammer ``device-major'' is introduced to ``files''.
device-major <prefix> char <num> [block <num>] [<rules>]
- All device major numbers must be listed up in port dependent majors.<arch>
by using this grammer.
- Added the new naming convention.
The name of the device switch must be <prefix>_[bc]devsw for auto-generation
of device switch tables.
- The backward compatibility of loading block/character device
switch by LKM framework is broken. This is necessary to convert
from block/character device major to device name in runtime and vice versa.
- The restriction to assign device major by LKM is completely removed.
We don't need to reserve LKM entries for dynamic loading of device switch.
- In compile time, device major numbers list is packed into the kernel and
the LKM framework will refer it to assign device major number dynamically.
TCPCB .. the fields need to be converted back to net-order, because
the packet is checksummed after the TCPCB lookup happens.
From YAMAMOTO Takashi <yamt@mwd.biglobe.ne.jp>.
we can always keep 2 packets on the wire, no matter what SO_SNDBUF is,
and therefore ACKs will never be delayed unless we run out of data to
transmit. The problem is quite easy to tickle when the MTU of the
outgoing interface is larger than the socket buffer size (e.g. loopback).
Fix from Charles Hannum.
optimization made last year. should solve PR 17867 and 10195.
IP_HDRINCL behavior of raw ip socket is kept unchanged. we may want to
provide IP_HDRINCL variant that does not swap endian.
value of the TCP_NODELAY socket option from the listener to the
newly connected connection. Agrees with how Linux & FreeBSD behave,
and goes more with the spirit of accept(2) creating a socket with
the same properties as the listener.
Analysis by Kevin Lahey. Closes PR 17616 by myself.
* Keep pointers to the first and last mbufs of the last record in the
socket buffer.
* Use the sb_lastrecord pointer in the sbappend*() family of functions
to avoid traversing the packet chain to find the last record.
* Add a new sbappend_stream() function for stream protocols which
guarantee that there will never be more than one record in the
socket buffer. This function uses the sb_mbtail pointer to perform
the data insertion. Make TCP use sbappend_stream().
On a profiling run, this makes sbappend of a TCP transmission using
a 1M socket buffer go from 50% of the time to .02% of the time.
Thanks to Bill Sommerfeld and YAMAMOTO Takashi for their debugging
assistance!
1. size_t is 64 bits, so use a u_32_t for iplused
2. microtime() and friends expect a struct timeval,
passing the first of two unsigned longs will not cut it.
as necessary:
* Implement a new mbuf utility routine, m_copyup(), is is like
m_pullup(), except that it always prepends and copies, rather
than only doing so if the desired length is larger than m->m_len.
m_copyup() also allows an offset into the destination mbuf, which
allows space for packet headers, in the forwarding case.
* Add *_HDR_ALIGNED_P() macros for IP, IPv6, ICMP, and IGMP. These
macros expand to 1 if __NO_STRICT_ALIGNMENT is defined, so that
architectures which do not have strict alignment constraints don't
pay for the test or visit the new align-if-needed path.
* Use the new macros to check if a header needs to be aligned, or to
assert that it already is, as appropriate.
Note: This code is still somewhat experimental. However, the new
code path won't be visited if individual device drivers continue
to guarantee that packets are delivered to layer 3 already properly
aligned (which are rules that are already in use).
- the destination is IPv4 multicast or 255.255.255.255, and
- outgoing interface is specified via socket option
this simplifies operation of routed
(no longer reqiure 224.0.0.0/4 to be set up)
martti