git.distorted.org.uk Git - u/mdw/putty/blob - ldisc.c

   1 /*
   2  * ldisc.c: PuTTY line discipline. Sits between the input coming
   3  * from keypresses in the window, and the output channel leading to
   4  * the back end. Implements echo and/or local line editing,
   5  * depending on what's currently configured.
   6  */
   7
   8 #include <stdio.h>
   9 #include <ctype.h>
  10
  11 #include "putty.h"
  12 #include "terminal.h"
  13 #include "ldisc.h"
  14
  15 #define ECHOING (cfg.localecho == LD_YES || \
  16                  (cfg.localecho == LD_BACKEND && \
  17                       (ldisc->back->ldisc(ldisc->backhandle, LD_ECHO) || \
  18                            term_ldisc(ldisc->term, LD_ECHO))))
  19 #define EDITING (cfg.localedit == LD_YES || \
  20                  (cfg.localedit == LD_BACKEND && \
  21                       (ldisc->back->ldisc(ldisc->backhandle, LD_EDIT) || \
  22                            term_ldisc(ldisc->term, LD_EDIT))))
  23
  24 static void c_write(Ldisc ldisc, char *buf, int len)
  25 {
  26     from_backend(ldisc->term, 0, buf, len);
  27 }
  28
  29 static int plen(Ldisc ldisc, unsigned char c)
  30 {
  31     if ((c >= 32 && c <= 126) || (c >= 160 && !in_utf(ldisc->term)))
  32         return 1;
  33     else if (c < 128)
  34         return 2;                      /* ^x for some x */
  35     else
  36         return 4;                      /* <XY> for hex XY */
  37 }
  38
  39 static void pwrite(Ldisc ldisc, unsigned char c)
  40 {
  41     if ((c >= 32 && c <= 126) || (c >= 160 && !in_utf(ldisc->term))) {
  42         c_write(ldisc, &c, 1);
  43     } else if (c < 128) {
  44         char cc[2];
  45         cc[1] = (c == 127 ? '?' : c + 0x40);
  46         cc[0] = '^';
  47         c_write(ldisc, cc, 2);
  48     } else {
  49         char cc[5];
  50         sprintf(cc, "<%02X>", c);
  51         c_write(ldisc, cc, 4);
  52     }
  53 }
  54
  55 static void bsb(Ldisc ldisc, int n)
  56 {
  57     while (n--)
  58         c_write(ldisc, "\010 \010", 3);
  59 }
  60
  61 #define CTRL(x) (x^'@')
  62 #define KCTRL(x) ((x^'@') | 0x100)
  63
  64 void *ldisc_create(Terminal *term,
  65                    Backend *back, void *backhandle,
  66                    void *frontend)
  67 {
  68     Ldisc ldisc = smalloc(sizeof(*ldisc));
  69
  70     ldisc->buf = NULL;
  71     ldisc->buflen = 0;
  72     ldisc->bufsiz = 0;
  73     ldisc->quotenext = 0;
  74
  75     ldisc->back = back;
  76     ldisc->backhandle = backhandle;
  77     ldisc->term = term;
  78     ldisc->frontend = frontend;
  79
  80     /* Link ourselves into the backend and the terminal */
  81     if (term)
  82         term->ldisc = ldisc;
  83     if (back)
  84         back->provide_ldisc(backhandle, ldisc);
  85
  86     return ldisc;
  87 }
  88
  89 void ldisc_send(void *handle, char *buf, int len, int interactive)
  90 {
  91     Ldisc ldisc = (Ldisc) handle;
  92     int keyflag = 0;
  93     /*
  94      * Called with len=0 when the options change. We must inform
  95      * the front end in case it needs to know.
  96      */
  97     if (len == 0) {
  98         ldisc_update(ldisc->frontend, ECHOING, EDITING);
  99         return;
 100     }
 101     /*
 102      * Notify the front end that something was pressed, in case
 103      * it's depending on finding out (e.g. keypress termination for
 104      * Close On Exit).
 105      */
 106     frontend_keypress(ldisc->frontend);
 107
 108     /*
 109      * Less than zero means null terminated special string.
 110      */
 111     if (len < 0) {
 112         len = strlen(buf);
 113         keyflag = KCTRL('@');
 114     }
 115     /*
 116      * Either perform local editing, or just send characters.
 117      */
 118     if (EDITING) {
 119         while (len--) {
 120             int c;
 121             c = *buf++ + keyflag;
 122             if (!interactive && c == '\r')
 123                 c += KCTRL('@');
 124             switch (ldisc->quotenext ? ' ' : c) {
 125                 /*
 126                  * ^h/^?: delete one char and output one BSB
 127                  * ^w: delete, and output BSBs, to return to last
 128                  * space/nonspace boundary
 129                  * ^u: delete, and output BSBs, to return to BOL
 130                  * ^c: Do a ^u then send a telnet IP
 131                  * ^z: Do a ^u then send a telnet SUSP
 132                  * ^\: Do a ^u then send a telnet ABORT
 133                  * ^r: echo "^R\n" and redraw line
 134                  * ^v: quote next char
 135                  * ^d: if at BOL, end of file and close connection,
 136                  * else send line and reset to BOL
 137                  * ^m: send line-plus-\r\n and reset to BOL
 138                  */
 139               case KCTRL('H'):
 140               case KCTRL('?'):         /* backspace/delete */
 141                 if (ldisc->buflen > 0) {
 142                     if (ECHOING)
 143                         bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 144                     ldisc->buflen--;
 145                 }
 146                 break;
 147               case CTRL('W'):          /* delete word */
 148                 while (ldisc->buflen > 0) {
 149                     if (ECHOING)
 150                         bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 151                     ldisc->buflen--;
 152                     if (ldisc->buflen > 0 &&
 153                         isspace(ldisc->buf[ldisc->buflen - 1]) &&
 154                         !isspace(ldisc->buf[ldisc->buflen]))
 155                         break;
 156                 }
 157                 break;
 158               case CTRL('U'):          /* delete line */
 159               case CTRL('C'):          /* Send IP */
 160               case CTRL('\\'):         /* Quit */
 161               case CTRL('Z'):          /* Suspend */
 162                 while (ldisc->buflen > 0) {
 163                     if (ECHOING)
 164                         bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 165                     ldisc->buflen--;
 166                 }
 167                 ldisc->back->special(ldisc->backhandle, TS_EL);
 168                 /*
 169                  * We don't send IP, SUSP or ABORT if the user has
 170                  * configured telnet specials off! This breaks
 171                  * talkers otherwise.
 172                  */
 173                 if (!cfg.telnet_keyboard)
 174                     goto default_case;
 175                 if (c == CTRL('C'))
 176                     ldisc->back->special(ldisc->backhandle, TS_IP);
 177                 if (c == CTRL('Z'))
 178                     ldisc->back->special(ldisc->backhandle, TS_SUSP);
 179                 if (c == CTRL('\\'))
 180                     ldisc->back->special(ldisc->backhandle, TS_ABORT);
 181                 break;
 182               case CTRL('R'):          /* redraw line */
 183                 if (ECHOING) {
 184                     int i;
 185                     c_write(ldisc, "^R\r\n", 4);
 186                     for (i = 0; i < ldisc->buflen; i++)
 187                         pwrite(ldisc, ldisc->buf[i]);
 188                 }
 189                 break;
 190               case CTRL('V'):          /* quote next char */
 191                 ldisc->quotenext = TRUE;
 192                 break;
 193               case CTRL('D'):          /* logout or send */
 194                 if (ldisc->buflen == 0) {
 195                     ldisc->back->special(ldisc->backhandle, TS_EOF);
 196                 } else {
 197                     ldisc->back->send(ldisc->backhandle, ldisc->buf, ldisc->buflen);
 198                     ldisc->buflen = 0;
 199                 }
 200                 break;
 201                 /*
 202                  * This particularly hideous bit of code from RDB
 203                  * allows ordinary ^M^J to do the same thing as
 204                  * magic-^M when in Raw protocol. The line `case
 205                  * KCTRL('M'):' is _inside_ the if block. Thus:
 206                  *
 207                  *  - receiving regular ^M goes straight to the
 208                  *    default clause and inserts as a literal ^M.
 209                  *  - receiving regular ^J _not_ directly after a
 210                  *    literal ^M (or not in Raw protocol) fails the
 211                  *    if condition, leaps to the bottom of the if,
 212                  *    and falls through into the default clause
 213                  *    again.
 214                  *  - receiving regular ^J just after a literal ^M
 215                  *    in Raw protocol passes the if condition,
 216                  *    deletes the literal ^M, and falls through
 217                  *    into the magic-^M code
 218                  *  - receiving a magic-^M empties the line buffer,
 219                  *    signals end-of-line in one of the various
 220                  *    entertaining ways, and _doesn't_ fall out of
 221                  *    the bottom of the if and through to the
 222                  *    default clause because of the break.
 223                  */
 224               case CTRL('J'):
 225                 if (cfg.protocol == PROT_RAW &&
 226                     ldisc->buflen > 0 && ldisc->buf[ldisc->buflen - 1] == '\r') {
 227                     if (ECHOING)
 228                         bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 229                     ldisc->buflen--;
 230                     /* FALLTHROUGH */
 231               case KCTRL('M'):         /* send with newline */
 232                     if (ldisc->buflen > 0)
 233                         ldisc->back->send(ldisc->backhandle, ldisc->buf, ldisc->buflen);
 234                     if (cfg.protocol == PROT_RAW)
 235                         ldisc->back->send(ldisc->backhandle, "\r\n", 2);
 236                     else if (cfg.protocol == PROT_TELNET && cfg.telnet_newline)
 237                         ldisc->back->special(ldisc->backhandle, TS_EOL);
 238                     else
 239                         ldisc->back->send(ldisc->backhandle, "\r", 1);
 240                     if (ECHOING)
 241                         c_write(ldisc, "\r\n", 2);
 242                     ldisc->buflen = 0;
 243                     break;
 244                 }
 245                 /* FALLTHROUGH */
 246               default:                 /* get to this label from ^V handler */
 247                 default_case:
 248                 if (ldisc->buflen >= ldisc->bufsiz) {
 249                     ldisc->bufsiz = ldisc->buflen + 256;
 250                     ldisc->buf = srealloc(ldisc->buf, ldisc->bufsiz);
 251                 }
 252                 ldisc->buf[ldisc->buflen++] = c;
 253                 if (ECHOING)
 254                     pwrite(ldisc, (unsigned char) c);
 255                 ldisc->quotenext = FALSE;
 256                 break;
 257             }
 258         }
 259     } else {
 260         if (ldisc->buflen != 0) {
 261             ldisc->back->send(ldisc->backhandle, ldisc->buf, ldisc->buflen);
 262             while (ldisc->buflen > 0) {
 263                 bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 264                 ldisc->buflen--;
 265             }
 266         }
 267         if (len > 0) {
 268             if (ECHOING)
 269                 c_write(ldisc, buf, len);
 270             if (keyflag && cfg.protocol == PROT_TELNET && len == 1) {
 271                 switch (buf[0]) {
 272                   case CTRL('M'):
 273                     if (cfg.protocol == PROT_TELNET && cfg.telnet_newline)
 274                         ldisc->back->special(ldisc->backhandle, TS_EOL);
 275                     else
 276                         ldisc->back->send(ldisc->backhandle, "\r", 1);
 277                     break;
 278                   case CTRL('?'):
 279                   case CTRL('H'):
 280                     if (cfg.telnet_keyboard) {
 281                         ldisc->back->special(ldisc->backhandle, TS_EC);
 282                         break;
 283                     }
 284                   case CTRL('C'):
 285                     if (cfg.telnet_keyboard) {
 286                         ldisc->back->special(ldisc->backhandle, TS_IP);
 287                         break;
 288                     }
 289                   case CTRL('Z'):
 290                     if (cfg.telnet_keyboard) {
 291                         ldisc->back->special(ldisc->backhandle, TS_SUSP);
 292                         break;
 293                     }
 294
 295                   default:
 296                     ldisc->back->send(ldisc->backhandle, buf, len);
 297                     break;
 298                 }
 299             } else
 300                 ldisc->back->send(ldisc->backhandle, buf, len);
 301         }
 302     }
 303 }