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From: jsq@ut-sally.UUCP (John Quarterman)
Newsgroups: net.bugs.4bsd
Subject: TCP connections hanging forever in FIN_WAIT_2 state
Message-ID: <590@ut-sally.UUCP>
Date: Sat, 10-Dec-83 16:28:16 EST
Article-I.D.: ut-sally.590
Posted: Sat Dec 10 16:28:16 1983
Date-Received: Sun, 11-Dec-83 04:54:41 EST
Organization: U. Texas CS Dept., Austin, Texas
Lines: 49

>From jsq Sat Dec 10 15:25:09 1983
Date: Sat, 10 Dec 83 15:25:03 cst
>From: jsq (John Quarterman)
Posted-Date: Sat, 10 Dec 83 15:25:03 cst
Received-Date: Sat, 10 Dec 83 15:25:03 cst
Message-Id: <8312102125.AA00997@ut-sally.ARPA>
Received: by ut-sally.ARPA (4.12/3.14)
	id AA00997; Sat, 10 Dec 83 15:25:03 cst
Subject: TCP connections hanging forever in FIN_WAIT_2 state
Index: 	sys/netinet/tcp_input.c 4.2BSD
Apparently-To: 4bsd-bugs@Berkeley
Apparently-To: jsq
Status: R

Description:
	TCP connections with TOPS-20 systems occassionally hang in
	FIN_WAIT_2 state.  When this happens, the connection *never*
	closes and such hung connections accumulate.
Repeat-By:
	If you have frequent TCP connections with a TOPS-20 host,
	you will notice, using netstat, connections in FIN_WAIT_2 state
	accumulating.  If you have frequent TOPS-20 traffic, all your
	incoming network pty ports will eventually be eaten up.
Fix:
	Add the line marked with +, 533, to /sys/netinet/tcp_input.c.
	This kludge does not agree complete with the TCP spec,
	but it does solve the problem.

		/*
		 * In FIN_WAIT_1 STATE in addition to the processing
		 * for the ESTABLISHED state if our FIN is now acknowledged
		 * then enter FIN_WAIT_2.
		 */
		case TCPS_FIN_WAIT_1:
			if (ourfinisacked) {
				/*
				 * If we can't receive any more
				 * data, then closing user can proceed.
				 */
				if (so->so_state & SS_CANTRCVMORE)
					soisdisconnected(so);
				tp->t_state = TCPS_FIN_WAIT_2;
+				tp->t_timer[TCPT_2MSL] = 2 * TCPTV_MSL;
			}
			break;

-- 
John Quarterman, CS Dept., University of Texas, Austin, Texas
{ihnp4,seismo,ctvax}!ut-sally!jsq, jsq@ut-sally.{ARPA,UUCP}