hedrick@athos.rutgers.edu (Charles Hedrick) (12/22/87)
The 4.3 telnet and telnetd, as contrasted to the 4.2 versions,
implement a much larger subset of the whole telnet spec. However the
4.3 version still doesn't do telnet SYNC. This is the feature needed
to clear the output buffer on the local end when it is done on the
remote end. That is, the feature needed to make ^C and ^O stop output
within a reasonable amount of time. In order to make this work, we
have to run the pty in packet mode (as rlogind does). Other than
that, the patch is pretty easy. We have a number of changes to
telnetd, but it looks like these are the relevant ones. Note that
this is to the 4.3 telnetd. The 4.2 version doesn't have the neturg
mechanism, so this patch wouldn't work. Of course this telnetd won't
accomplish anything unless your telnet handles SYNC correctly. That
requires the 4.3 telnet (and a kernel that includes SO_OOBINLINE --
4.3 telnet tries to simulate it if it isn't defined, but the
simulation doesn't seem to work very well).
***************
*** 382,387 ****
--- 447,453 ----
ioctl(f, FIONBIO, &on);
ioctl(p, FIONBIO, &on);
+ ioctl(p, TIOCPKT, &on);
#if defined(SO_OOBINLINE)
setsockopt(net, SOL_SOCKET, SO_OOBINLINE, &on, sizeof on);
#endif /* defined(SO_OOBINLINE) */
***************
*** 553,559 ****
/*
* Something to read from the pty...
*/
! if (FD_ISSET(p, &ibits)) {
pcc = read(p, ptyibuf, BUFSIZ);
if (pcc < 0 && errno == EWOULDBLOCK)
pcc = 0;
--- 619,625 ----
/*
* Something to read from the pty...
*/
! if (FD_ISSET(p, &ibits) || FD_ISSET(p, &xbits)) {
pcc = read(p, ptyibuf, BUFSIZ);
if (pcc < 0 && errno == EWOULDBLOCK)
pcc = 0;
***************
*** 560,566 ****
else {
if (pcc <= 0)
break;
! ptyip = ptyibuf;
}
}
--- 626,640 ----
else {
if (pcc <= 0)
break;
! if (ptyibuf[0] & TIOCPKT_FLUSHWRITE) {
!
! netclear(); /* clear buffer back */
! *nfrontp++ = IAC;
! *nfrontp++ = DM;
! neturg = nfrontp-1; /* off by one XXX */
! }
! pcc--;
! ptyip = ptyibuf+1;
}
}