telnetd improvements

telnetd improvements

[Vadim]

Hi -- i fixed the telnetd "line discipline" to make it more convinient
for those who telnet into a Plan 9 system (i.e. it simulates the
BSD-style kill/erase behaviour).  Diffs (from 2.0 source) are:

cpu% cd /sys/src/cmd/service
cpu% diff telnetd.c.old telnetd.c
273a274,276
> #define BACKSPACE() { ECHO('\b'); ECHO(' '); ECHO('\b'); }
> #define RUBOUT(c) { BACKSPACE(); if((c)<' ' || (c)==0177) BACKSPACE(); }
>
347,350d349
<               case 0x00:
<                       if(noproto)             /* telnet ignores nulls */
<                               *bp++ = c;
<                       continue;
357c356
<                       if(start < bp)
---
>                       if(start < bp) {
359,360c358,360
<                       if(opt[Echo].local)
<                               ECHO(c);
---
>                               if(opt[Echo].local)
>                                       RUBOUT(*bp);
>                       }
364,369c364,368
<                       bp = start;
<                       if(opt[Echo].local){
<                               ECHO('^');
<                               ECHO('U');
<                               ECHO('\r');
<                               ECHO('\n');
---
>                       if(opt[Echo].local) {
>                               while (bp > start) {
>                                       bp--;
>                                       RUBOUT(*bp);
>                               }
375,378c374
<                               while (--bp >= start && !alnum(*bp))
<                                       ECHO('\b');
<                               while (bp >= start && alnum(*bp)) {
<                                       ECHO('\b');
---
>                               while (bp > start && !alnum(bp[-1])) {
379a376
>                                       RUBOUT(*bp);
381c378,381
<                               bp++;
---
>                               while (bp > start && alnum(bp[-1])) {
>                                       bp--;
>                                       BACKSPACE();
>                               }
386a387,389
>                       ECHO('\r');
>                       ECHO('\n');
>                       bp = start;
388a392,396
>               case 0x00:
>                       if(!noproto)            /* telnet ignores nulls */
>                               break;
>                       /*FALL THRU*/
>
390,391c398,405
<                       if(opt[Echo].local)
<                               ECHO(c);
---
>                       if(opt[Echo].local) {
>                               if( c >= ' ' ) {
>                                       ECHO(c);
>                               } else {
>                                       ECHO('^');
>                                       ECHO(0x40|c);
>                               }
>                       }
cpu%

--vadim