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Date:      Fri, 14 Apr 2000 12:17:59 +0300
From:      Ruslan Ermilov <ru@FreeBSD.org>
To:        brian@pocketscience.com, brian@FreeBSD.org, cmott@scientech.com, net@FreeBSD.org
Cc:        freebsd-gnats-submit@FreeBSD.org
Subject:   Re: bin/17963: NATD appears to memory leak when a connection fails from the internal network to the external network.
Message-ID:  <20000414121759.A37837@relay.ucb.crimea.ua>
In-Reply-To: <200004130218.TAA12378@freefall.freebsd.org>; from brian@pocketscience.com on Wed, Apr 12, 2000 at 07:18:39PM -0700
References:  <200004130218.TAA12378@freefall.freebsd.org>
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On Wed, Apr 12, 2000 at 07:18:39PM -0700, brian@pocketscience.com wrote:
> 
[...]
> from an internal machine, make several network connections that get 
> dropped on the remote end (not denied, but connection timeouts)
> 
Please try the following patch.  It is for RELENG_3 (latest) sources.
Extract patch to the currrent directory, then follow instructions:

# mv ./p /tmp
# cd /usr/src/lib/libalias
# patch </tmp/p
# make clean all install		# build/install new library
# cd /usr/src/sbin/natd
# make clean all install		# build/install natd with new library


BACKGROUND

The problem was that the TCP link's timeout was set to TCP_EXPIRE_CONNECTED
(86400 secs) right after the first SYN from the client (or from the server
for incoming connections).  With this change, this huge timeout value will
only be applied to ESTABLISHED connections, i.e. only after SYN was seen
from both client and server side.  TCP links corresponding to failed TCP
connections (those which never receive neither SYN-ACK nor RST from server),
will be dropped after TCP_EXPIRE_INITIAL (300 seconds) timeout.


Cheers,
-- 
Ruslan Ermilov		Sysadmin and DBA of the
ru@ucb.crimea.ua	United Commercial Bank,
ru@FreeBSD.org		FreeBSD committer,
+380.652.247.647	Simferopol, Ukraine

http://www.FreeBSD.org	The Power To Serve
http://www.oracle.com	Enabling The Information Age

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Index: alias_db.c
===================================================================
RCS file: /usr/FreeBSD-CVS/src/lib/libalias/alias_db.c,v
retrieving revision 1.10.2.5
diff -u -p -r1.10.2.5 alias_db.c
--- alias_db.c	1999/12/21 00:04:09	1.10.2.5
+++ alias_db.c	2000/04/14 08:34:44
@@ -1538,22 +1538,19 @@ SetStateIn(struct alias_link *link, int 
     /* TCP input state */
     switch (state) {
     case ALIAS_TCP_STATE_DISCONNECTED:
-        if (link->data.tcp->state.out != ALIAS_TCP_STATE_CONNECTED) {
+        if (link->data.tcp->state.out != ALIAS_TCP_STATE_CONNECTED)
             link->expire_time = TCP_EXPIRE_DEAD;
-        } else {
+        else
             link->expire_time = TCP_EXPIRE_SINGLEDEAD;
-        }
-        link->data.tcp->state.in = state;
         break;
     case ALIAS_TCP_STATE_CONNECTED:
-        link->expire_time = TCP_EXPIRE_CONNECTED;
-        /*FALLTHROUGH*/
-    case ALIAS_TCP_STATE_NOT_CONNECTED:
-        link->data.tcp->state.in = state;
+        if (link->data.tcp->state.out == ALIAS_TCP_STATE_CONNECTED)
+            link->expire_time = TCP_EXPIRE_CONNECTED;
         break;
     default:
         abort();
     }
+    link->data.tcp->state.in = state;
 }
 
 
@@ -1563,22 +1560,19 @@ SetStateOut(struct alias_link *link, int
     /* TCP output state */
     switch (state) {
     case ALIAS_TCP_STATE_DISCONNECTED:
-        if (link->data.tcp->state.in != ALIAS_TCP_STATE_CONNECTED) {
+        if (link->data.tcp->state.in != ALIAS_TCP_STATE_CONNECTED)
             link->expire_time = TCP_EXPIRE_DEAD;
-        } else {
+        else
             link->expire_time = TCP_EXPIRE_SINGLEDEAD;
-        }
-        link->data.tcp->state.out = state;
         break;
     case ALIAS_TCP_STATE_CONNECTED:
-        link->expire_time = TCP_EXPIRE_CONNECTED;
-        /*FALLTHROUGH*/
-    case ALIAS_TCP_STATE_NOT_CONNECTED:
-        link->data.tcp->state.out = state;
+        if (link->data.tcp->state.in == ALIAS_TCP_STATE_CONNECTED)
+            link->expire_time = TCP_EXPIRE_CONNECTED;
         break;
     default:
         abort();
     }
+    link->data.tcp->state.out = state;
 }
 
 

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