K 10
svn:author
V 3
hrs
K 8
svn:date
V 27
2020-02-27T19:49:59.552059Z
K 7
svn:log
V 812
Fix poor performance of ftp(1) due to small SO_SNDBUF and SO_RCVBUF.

ftp(1) from vendor/tnftp always tried the following for
every TCP connection:

1. Get the current buffer length of SO_SNDBUF and SO_RCVBUF
   by getsockopt(2).

2. Invoke setsockopt(2) to set them to the same values
   after checking if they are in a range between 8 KiB to 8 MiB.

This behavior broke dynamic buffer sizing enabled by
default (net.inet.tcp.{recv,send}buf_auto sysctls) and
led to a very poor transfer rate.  The fetch(1) utility
does not have this problem.

This change prevents SO_SNDBUF and SO_RCVBUF from configuring
when the buffer auto-sizing is enabled unless the buffer sizes are
explicitly specified.

PR:		240827
Spotted by:	Yuichiro NAITO
MFC after:	3 days
Differential Revision:	https://reviews.freebsd.org/D23732

END