> does anyone know why telnet has trouble with this?
>
> ; echo godaddy.com|telnet -nr /net.alt/tcp!whois.godaddy.com!43
> connected to /net.alt/tcp!whois.godaddy.com!43 on /net.alt/tcp/12
> ;
>
> from a similarly-connected linux machine, linux telnet returns a
> lengthy answer.
It's not telnet's fault. It's a TCP bug.
Here's a trace on Linux. Notice that godaddy's SYN|ACK packet (34822ms)
advertises a zero-length receive window, so Linux has to wait
until it gets an ACK to its ACK to open the window (34899ms)
before it sends (34900ms).
# /usr/local/plan9/bin/snoopy -f 'tcp(sd=43)' eth0
after optimize: ether(ip(tcp(sd = 43)))
034744 ms
ether(s=000feafc0dbe d=00095bdb3254 pr=0800 ln=74)
ip(s=192.168.0.99 d=68.178.211.43 id=9ca5 frag=4000 ttl= 64 pr=6 ln=60)
tcp(s=42805 d=43 seq=1897121382 ack=0 fl=S win=5840 ck=d993 opt4=(mss
1460) opt2=(4 ) opt10=(8 45155AC300000000) opt=NOOP opt3=(wscale 7))
034822 ms
ether(s=00095bdb3254 d=000feafc0dbe pr=0800 ln=60)
ip(s=68.178.211.43 d=192.168.0.99 id=9ca5 frag=0000 ttl= 31 pr=6 ln=40)
tcp(s=43 d=42805 seq=3642134677 ack=1897121383 fl=AS win=0 ck=8e61)
034822 ms
ether(s=000feafc0dbe d=00095bdb3254 pr=0800 ln=54)
ip(s=192.168.0.99 d=68.178.211.43 id=9ca6 frag=4000 ttl= 64 pr=6 ln=40)
tcp(s=42805 d=43 seq=1897121383 ack=3642134678 fl=A win=5840 ck=7792)
034899 ms
ether(s=00095bdb3254 d=000feafc0dbe pr=0800 ln=60)
ip(s=68.178.211.43 d=192.168.0.99 id=34a4 frag=0000 ttl=111 pr=6 ln=40)
tcp(s=43 d=42805 seq=3642134678 ack=1897121383 fl=A win=16384 ck=4e62)
034900 ms
ether(s=000feafc0dbe d=00095bdb3254 pr=0800 ln=66)
ip(s=192.168.0.99 d=68.178.211.43 id=9ca7 frag=4000 ttl= 64 pr=6 ln=52)
tcp(s=42805 d=43 seq=1897121383 ack=3642134678 fl=AP win=5840 ck=d90f)
dump(godaddy.com\n)
035195 ms
ether(s=00095bdb3254 d=000feafc0dbe pr=0800 ln=60)
ip(s=68.178.211.43 d=192.168.0.99 id=34d7 frag=0000 ttl=111 pr=6 ln=40)
tcp(s=43 d=42805 seq=3642134678 ack=1897121395 fl=A win=65523 ck=8e62)
035265 ms
ether(s=00095bdb3254 d=000feafc0dbe pr=0800 ln=1434)
ip(s=68.178.211.43 d=192.168.0.99 id=3504 frag=0000 ttl=111 pr=6
ln=1420)
tcp(s=43 d=42805 seq=3642134678 ack=1897121395 fl=A win=65523 ck=a8b6)
dump(The data contained in GoDaddy.co)
Plan 9 ignores the zero length window and sends a single byte (2456ms),
causing godaddy to hang up (2493ms).
cpu% snoopy -N 1500 -f 'tcp(sd=43)' /net/ether1
after optimize: ether(ip(tcp(sd = 43)))
002343 ms
ether(s=0004238ecb1a d=0007b3f12c00 pr=0800 ln=62)
ip(s=18.26.4.98 d=68.178.211.43 id=9330 frag=0000 ttl=255 pr=6 ln=48)
tcp(s=32619 d=43 seq=1578393267 ack=0 fl=S win=65535 ck=1767 opt4=(mss
1460) opt3=(wscale 3) opt=NOOP)
002418 ms
ether(s=0007b3f12c00 d=0004238ecb1a pr=0800 ln=64)
ip(s=68.178.211.43 d=18.26.4.98 id=9330 frag=0000 ttl=223 pr=6 ln=40)
tcp(s=43 d=32619 seq=2734158449 ack=1578393268 fl=AS win=0 ck=afb0)
002437 ms
ether(s=0004238ecb1a d=0007b3f12c00 pr=0800 ln=60)
ip(s=18.26.4.98 d=68.178.211.43 id=9339 frag=0000 ttl=255 pr=6 ln=40)
tcp(s=32619 d=43 seq=1578393268 ack=2734158450 fl=AP win=65535 ck=afa9)
002456 ms
ether(s=0004238ecb1a d=0007b3f12c00 pr=0800 ln=60)
ip(s=18.26.4.98 d=68.178.211.43 id=933a frag=0000 ttl=255 pr=6 ln=41)
tcp(s=32619 d=43 seq=1578393268 ack=2734158450 fl=A win=65535 ck=48b0)
dump(g)
002493 ms
ether(s=0007b3f12c00 d=0004238ecb1a pr=0800 ln=64)
ip(s=68.178.211.43 d=18.26.4.98 id=9339 frag=0000 ttl=223 pr=6 ln=40)
tcp(s=43 d=32619 seq=2734158450 ack=1578393268 fl=AR win=65535 ck=afad)
The source is in /sys/src/9/ip/tcp.c. Have fun.
Russ
