cvs commit: src/sys/netinet tcp_subr.c tcp_var.h
silby at FreeBSD.org
Mon Apr 19 23:33:40 PDT 2004
silby 2004/04/19 23:33:39 PDT
FreeBSD src repository
sys/netinet tcp_subr.c tcp_var.h
Enhance our RFC1948 implementation to perform better in some pathlogical
TIME_WAIT recycling cases I was able to generate with http testing tools.
In short, as the old algorithm relied on ticks to create the time offset
component of an ISN, two connections with the exact same host, port pair
that were generated between timer ticks would have the exact same sequence
number. As a result, the second connection would fail to pass the TIME_WAIT
check on the server side, and the SYN would never be acknowledged.
I've "fixed" this by adding random positive increments to the time component
between clock ticks so that ISNs will *always* be increasing, no matter how
quickly the port is recycled.
Except in such contrived benchmarking situations, this problem should never
come up in normal usage... until networks get faster.
No MFC planned, 4.x is missing other optimizations that are needed to even
create the situation in which such quick port recycling will occur.
Revision Changes Path
1.188 +53 -2 src/sys/netinet/tcp_subr.c
1.103 +1 -0 src/sys/netinet/tcp_var.h
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