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From: hedrick@athos.rutgers.edu (Charles Hedrick)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Porting BSD telnetd to a Sun
Keywords: telnetd bsd 4.3 Sun SunOS
Message-ID: <May.28.17.54.40.1991.9637@athos.rutgers.edu>
Date: 28 May 91 21:54:41 GMT
References: <jpc.675443676@avdms8.msfc.nasa.gov>
Organization: Rutgers Univ., New Brunswick, N.J.
Lines: 33
To: jpc@avdms8.msfc.nasa.gov

We use the 4.4 telnetd on our Suns.  With either version, you'll want
to add some code to the section that opens the controlling pty.  Look
for

  for (i = 0; i < 16; i++) {
	line[sizeof("/dev/ptyp") - 1] = "0123456789abcdef"[i];
 	p = open(line, O_RDWR);
	if (p > 0)
		goto gotpty;
  }

Instead, you want something like the following.  (This is taken from
our 4.4 version of telnetd, so I haven't actually used it in the 4.3
one, but I think it should be OK.)  Note that this code is
SunOS-specific, and should work in 4.0.3c or later.  (It depends upon
an undocumented side-effect of TIOCGPGRP.)

  for (i = 0; i < 16; i++) {
	line[sizeof("/dev/ptyp") - 1] = "0123456789abcdef"[i];
	p = open(line, O_RDWR);
	if (p > 0) {
	  line[5] = 't';
	  chown(line, 0, 0);
	  chmod(line, 0600);
	  /* make sure the tty isn't in use */
	  if (ioctl(p, TIOCGPGRP, &dummy) == -1 &&
	      errno == EIO)
	    goto gotpty;
	  chmod(line, 0666);
	  close(p);
	  line[5] = 'p';
	}
  }