bin/6676: natd doesn't respond to SIGTERM

[Luoqi Chen]

>Number: 6676
>Category: bin
>Synopsis: natd doesn't respond to signals when there is no traffic
>Confidential: no
>Severity: non-critical
>Priority: low
>Responsible: freebsd-bugs
>State: open
>Quarter:
>Keywords:
>Date-Required:
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Mon May 18 03:40:01 PDT 1998
>Last-Modified:
>Originator: Luoqi Chen
>Organization:
>Release: FreeBSD 3.0-CURRENT i386
>Environment:

3.0-current as of 5/16/98

>Description:

When all of the following conditions are true,
o same in & out divert port (default)
o alias_address is used instead of an interface name
o there is no ip divert traffic (e.g. ipfw divert rule is removed)
natd won't respond to SIGTERM. I have a natd shutdown script which
removes ipfw divert rule first, then terminate natd with kill -TERM.
I could reverse the order, kill natd first, then removes divert rule,
since natd has a 10 sec grace period before shutdown, but this is
nevertheless a bug.

The cause of the problem is that by default signal handlers are
installed with SA_RESTART flag set, under aforementioned conditions,
recvfrom() syscall in DoAliasing() will block forever.

>How-To-Repeat:

Start natd with alias_address option, e.g.
natd -alias_address ${public_ip_address}

Now in my shutdown script, I first removes ipfw divert rule, then
killall natd
natd won't go away.

>Fix:

Set SIGTERM interruptable. (There's similar problem with SIGHUP,
in this case, refresh of address is delayed and the first packet
after an address change might be mistranslated.)

Index: natd.c
===================================================================
RCS file: /fun/cvs/src/usr.sbin/natd/natd.c,v
retrieving revision 1.8
diff -u -r1.8 natd.c
--- natd.c 1997/12/27 19:31:11 1.8
+++ natd.c 1998/05/18 10:09:32
@@ -243,6 +243,8 @@
* Catch signals to manage shutdown and
* refresh of interface address.
*/
+ siginterrupt (SIGHUP, 1);
+ siginterrupt (SIGALRM, 1);
signal (SIGTERM, InitiateShutdown);
signal (SIGHUP, RefreshAddr);
/*

>Audit-Trail:
>Unformatted:

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