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.

1 files changed, 1 insertions, 0 deletions

diff --git a/sys/netinet/tcp_var.h b/sys/netinet/tcp_var.h
index ed3dec2..c85fecc 100644
--- a/sys/netinet/tcp_var.h
+++ b/sys/netinet/tcp_var.h
@@ -518,6 +518,7 @@ struct tcpcb *
 void	 tcp_drain(void);
 void	 tcp_fasttimo(void);
 void	 tcp_init(void);
+void	 tcp_fini(void *);
 void	 tcp_reass_init(void);
 void	 tcp_input(struct mbuf *, int);
 u_long	 tcp_maxmtu(struct in_conninfo *);