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Path: utzoo!utgpu!water!watmath!clyde!rutgers!husc6!bloom-beacon!wesommer
From: wesommer@bloom-beacon.UUCP
Newsgroups: comp.unix.wizards
Subject: Re: Sockets stuck in FIN_WAIT_2
Message-ID: <886@bloom-beacon.MIT.EDU>
Date: Wed, 10-Jun-87 23:18:56 EDT
Article-I.D.: bloom-be.886
Posted: Wed Jun 10 23:18:56 1987
Date-Received: Sat, 13-Jun-87 07:01:41 EDT
References: <1556@aw.sei.cmu.edu>
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: wesommer@athena.mit.edu (William Sommerfeld)
Organization: Massachusetts Institute of Technology
Lines: 149

In article <1556@aw.sei.cmu.edu> pdb@sei.cmu.edu (Patrick Barron) writes:
>If I shutdown sendmail on my Ultrix VAX and there is still a socket out there
>bound to the local smtp service in FIN_WAIT_2 (waiting for a FIN from the
>remote host), then I'll never be able to restart mail unless I reboot the
>machine.  Does anyone have a program, or the proper "adb -k" incantations,
>to force a stuck FIN_WAIT_2 socket into CLOSED state?

Our local network wizard, Jeff Schiller, wrote one once.  It works on
4.2 and 4.3 and Ultrix (several flavors); I'm posting it here because
its so short.  Just compile it with
	cc -O -o fixfin2 fixfin2.c 
and run it as root.  Please, no flames about the style or lack of
comments (the author will ignore the flames anyway).

					Bill Sommerfeld
					wesommer@athena.mit.edu
				
#! /bin/sh
# This is a shell archive, meaning:
# 1. Remove everything above the #! /bin/sh line.
# 2. Save the resulting text in a file.
# 3. Execute the file with /bin/sh (not csh) to create:
#	fixfin2.c
# This archive created: Wed Jun 10 23:05:01 1987
export PATH; PATH=/bin:/usr/bin:$PATH
echo shar: "extracting 'fixfin2.c'" '(3047 characters)'
if test -f 'fixfin2.c'
then
	echo shar: "will not over-write existing file 'fixfin2.c'"
else
sed 's/^	X//' << \SHAR_EOF > 'fixfin2.c'
	X#include <stdio.h>
	X#include <sys/types.h>
	X#include <sys/file.h>
	X#include <sys/param.h>
	X#include <sys/socket.h>
	X#include <sys/socketvar.h>
	X#include <sys/mbuf.h>
	X#include <sys/protosw.h>
	X#include <netinet/in.h>
	X#include <netinet/in_systm.h>
	X#include <net/route.h>
	X#include <netinet/in_pcb.h>
	X#include <netinet/ip.h>
	X#include <netinet/tcp.h>
	X#include <netinet/tcp_fsm.h>
	X#include <netinet/tcp_timer.h>
	X#include <netinet/tcp_var.h>
	X#include <nlist.h>
	Xextern   int errno;
	Xstruct inpcb inpcb;
	Xstruct tcpcb tcpcb;
	Xint kmem;
	Xstruct nlist nl[] = {
	X#define N_TCB 0
	X  { "_tcb" }, 
	X  "",
	X};
	Xmain ()
	X{
	X  register int err;
	X  register struct inpcb *next, *prev;
	X  register int stateoff;
	X  struct inpcb *tcbaddr;
	X  int testfirst;
	X  short fstate;
	X  stateoff = 0;
	X  nlist("/vmunix", nl);
	X  if (nl[0].n_type == 0) {
	X    fprintf(stderr, "/vmunix: no namelist\n");
	X    exit (1);
	X  }
	X  tcbaddr = (struct inpcb *) nl[N_TCB].n_value;
	X  kmem = open ("/dev/kmem", O_RDWR, 0644);
	X  check_error(kmem, "Opening /dev/kmem", errno);
	X  (void) lseek (kmem, (off_t)tcbaddr, 0);
	X  check_error((errno != 0) ? -1 : 0, "seeking for tcbaddr", errno);
	X  err = read (kmem, (caddr_t)&inpcb, sizeof (struct inpcb));
	X  check_error(err, "reading tcb", errno);
	X  if (inpcb.inp_next == (struct inpcb *)tcbaddr) exit (3);
	X  prev = tcbaddr;
	X  while (inpcb.inp_next != (struct inpcb *)tcbaddr) {
	X    next = inpcb.inp_next;
	X    (void) lseek (kmem, (off_t)next, 0);
	X    check_error((errno != 0) ? -1 : 0, "seeking for next inpcb", errno);
	X    err = read(kmem, (char *)&inpcb, sizeof(inpcb));
	X    check_error(err, "reading next inpcb", errno);
	X    if (inpcb.inp_prev != prev) {
	X      fprintf(stderr,"Bad sample after %x\n", prev);
	X      exit (4);
	X    }
	X    (void) lseek(kmem, (off_t)inpcb.inp_ppcb, 0);
	X    check_error((errno != 0) ? -1 : 0, "Seeking tcpcb", errno);
	X    err = read (kmem, (char *)&tcpcb, sizeof(tcpcb));
	X    check_error(err, "Reading tcpcb", errno);
	X    if (stateoff == 0) {
	X      stateoff = (int) &tcpcb.t_state - (int) &tcpcb;
	X    }
	X    if (tcpcb.t_state == TCPS_FIN_WAIT_2) {
	X      testfirst = 1;
	X    doitagain:
	X      (void) lseek (kmem, (off_t) ((int) inpcb.inp_ppcb + stateoff), 0);
	X      check_error ((errno != 0) ? -1 : 0, "seeking to tcp state variable", errno);
	X      if (testfirst) {
	X	err = read (kmem, (char *)&fstate, sizeof (short));
	X      } else {
	X/*	fprintf(stderr, "Would write %d, &tcpcb = %X, stateoff= %d\n",
	X		fstate, inpcb.inp_ppcb, stateoff); */
	X	err = write (kmem, (char *)&fstate, sizeof (short));
	X      }
	X      check_error (err, testfirst ? "reading tcp state variable" :
	X		   "Writing tcp state variable", errno);
	X      if (testfirst) {
	X	if (fstate != TCPS_FIN_WAIT_2) {
	X	  fprintf(stderr, "Connection changed state!\n");
	X	} else {
	X	  testfirst = 0;
	X	  fstate = 0;
	X	}
	X	goto doitagain;
	X      }
	X    }
	X    prev = next;
	X  }
	X  (void) close (kmem);
	X  exit (0);
	X}
	X
	Xcheck_error(err, msg, code)
	Xint err;
	Xchar *msg;
	Xint code;
	X{
	X  if (err < 0) {
	X    fprintf (stderr, "finfix2: Error: %s\n", msg);
	X    errno = code;
	X    perror("fixfin2");
	X    exit (1);
	X  }
	X  return;
	X}
SHAR_EOF
if test 3047 -ne "`wc -c < 'fixfin2.c'`"
then
	echo shar: "error transmitting 'fixfin2.c'" '(should have been 3047 characters)'
fi
fi
exit 0
#	End of shell archive