official Berkeley fix for telnetd CR-NL mapping


Mike Karels (karels%okeeffe@berkeley.edu)
Wed, 16 Sep 87 21:04:00 PDT


In order to resolve certain compatibility problems when telnet sessions
are nested, 4.3BSD telnetd has been changed to translate <CR><NL> to '\r'
rather than 'n'. This circumvents problems when using a telnet client
that is incapable of sending <CR><NUL> to signify a carriage return,
then using telnet or tip to connect to a system that differentiates
between carriage return and line feed. (See previous discussions on
the tcp-ip mailing list.) This patch also fixes an error that mapped
<CR><NUL> to '\r' in binary mode. It is recommended that all 4.3BSD
sites change telnetd according to this patch.

                Mike

*** /nbsd/usr/src/etc/telnetd.c Mon May 12 22:21:51 1986
--- telnetd.c Wed Sep 2 23:22:30 1987
***************
*** 13,15 ****
  #ifndef lint
! static char sccsid[] = "@(#)telnetd.c 5.18 (Berkeley) 5/12/86";
  #endif not lint
--- 13,15 ----
  #ifndef lint
! static char sccsid[] = "@(#)telnetd.c 5.20 (Berkeley) 9/2/87";
  #endif not lint
***************
*** 573,575 ****
                        *nfrontp++ = c;
! if (c == '\r') {
                                if (pcc > 0 && ((*ptyip & 0377) == '\n')) {
--- 573,576 ----
                        *nfrontp++ = c;
! /* Don't do CR-NUL if we are in binary mode */
! if ((c == '\r') && (myopts[TELOPT_BINARY] == OPT_NO)) {
                                if (pcc > 0 && ((*ptyip & 0377) == '\n')) {
***************
*** 617,618 ****
--- 618,620 ----
                        state = TS_DATA;
+ /* Strip off \n or \0 after a \r */
                        if ((c == 0) || (c == '\n')) {
***************
*** 630,632 ****
                        /*
! * We map \r\n ==> \n, since \r\n says
                         * that we want to be in column 1 of the next
--- 632,638 ----
                        /*
! * We now map \r\n ==> \r for pragmatic reasons.
! * Many client implementations send \r\n when
! * the user hits the CarriageReturn key.
! *
! * We USED to map \r\n ==> \n, since \r\n says
                         * that we want to be in column 1 of the next
***************
*** 636,644 ****
                         */
! if ((myopts[TELOPT_BINARY] == OPT_NO) && c == '\r') {
! if ((ncc > 0) && ('\n' == *netip)) {
! netip++; ncc--;
! c = '\n';
! } else {
! state = TS_CR;
! }
                        }
--- 642,645 ----
                         */
! if ((c == '\r') && (hisopts[TELOPT_BINARY] == OPT_NO)) {
! state = TS_CR;
                        }



This archive was generated by hypermail 2.0b3 on Thu Mar 09 2000 - 14:39:15 GMT