net/nylon hangs in read(2) under FreeBSD10

[Pavel Timofeev]

Turns out, it's just enough to do
# telnet proxy.xxx.ru 1080
and do nothing after that for hanging nylon in read(2).
Naive nylon's code?

2014-03-12 11:34 GMT+04:00 Pavel Timofeev <timp87 at gmail.com>:
> Hello!
> I used net/nylon (socks proxy server, born in openbsd) for some time
> under FreeBSD10.0-RELEASE amd64.
> I had no problems in testlab with that configuration.
> But now I have problems in production with that.
> Sometimes nylon starts to eat whole CPU.
>
> For example, I have proxy.xxx.ru (192.168.31.198) and client1.xxx.ru
> (192.168.2.6).
> Here is what I see every time.
> Let's say that hung nylon has pid 5323
>
> # truss -p 5323
> ......
> read(6,0x7fffffffdb13,1)                         ERR#35 'Resource
> temporarily unavailable'
> read(6,0x7fffffffdb13,1)                         ERR#35 'Resource
> temporarily unavailable'
> read(6,0x7fffffffdb13,1)                         ERR#35 'Resource
> temporarily unavailable'
> read(6,0x7fffffffdb13,1)                         ERR#35 'Resource
> temporarily unavailable'
> read(6,0x7fffffffdb13,1)                         ERR#35 'Resource
> temporarily unavailable'
> ^C
>
> Nylon tries to read from FD 6 (right?) and gets errno 35. Infinite loop.
>
>
> # lsof -p 5323
> COMMAND  PID USER   FD   TYPE             DEVICE SIZE/OFF    NODE NAME
> nylon   5323 root  cwd   VDIR               0,96     1024       2 /
> nylon   5323 root  rtd   VDIR               0,96     1024       2 /
> nylon   5323 root  txt   VREG               0,96    34840 1134069
> /usr/local/bin/nylon
> nylon   5323 root  txt   VREG               0,96   111696  240770
> /libexec/ld-elf.so.1
> nylon   5323 root  txt   VREG               0,96   306532 2970271
> /usr/local/lib/event2/libevent-2.0.so.6
> nylon   5323 root  txt   VREG               0,96  1567216  481549 /lib/libc.so.7
> nylon   5323 root  txt   VREG               0,96   105104  481569
> /lib/libthr.so.3
> nylon   5323 root    0u  VCHR               0,15      0t0      15 /dev/null
> nylon   5323 root    1u  VCHR               0,15      0t0      15 /dev/null
> nylon   5323 root    2u  VCHR               0,15      0t0      15 /dev/null
> nylon   5323 root    4u  IPv4 0xfffff800646b9c00      0t0     TCP
> proxy.xxx.ru:socks (LISTEN)
> nylon   5323 root    5u  unix 0xfffff8006494d000      0t0
> ->0xfffff800098862b8
> nylon   5323 root    6u  IPv4 0xfffff8011cd07400      0t0     TCP
> proxy.xxx.ru:socks->client1.xxx.ru:45737 (ESTABLISHED)
>
> Looks like that FD is last line in this output. It's tcp socket (right?).
>
>
> # sockstat | grep 5323
> root     nylon      5323  4  tcp4   192.168.31.198:1080   *:*
> root     nylon      5323  5  dgram  -> /var/run/logpriv
> root     nylon      5323  6  tcp4   192.168.31.198:1080   192.168.2.6:45737
>
> That pid has open socket with client1.xxx.ru (192.168.2.6).
>
> I looked to open sockets in client1.xxx.ru and didn't find suitable.
>
> And I can kill that hung pid only using "kill -9".
>
>
> It appears to be a problem here. But where? In nylon or even in FreeBSD?
> I'm not UNIX OS and programming professional and I don't know wheater
> OS has to return errno 35 for read of that dead(?) socket.
> Do I have to provide more info? Which one? I'm looking forward!
> It happens quite often now.