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 (ldisc->cfg->localecho == FORCE_ON || \
  16                  (ldisc->cfg->localecho == AUTO && \
  17                       (ldisc->back->ldisc(ldisc->backhandle, LD_ECHO) || \
  18                            term_ldisc(ldisc->term, LD_ECHO))))
  19 #define EDITING (ldisc->cfg->localedit == FORCE_ON || \
  20                  (ldisc->cfg->localedit == AUTO && \
  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->frontend, 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 if (in_utf(ldisc->term) && c >= 0xC0)
  36         return 1;                      /* UTF-8 introducer character
  37                                         * (FIXME: combining / wide chars) */
  38     else if (in_utf(ldisc->term) && c >= 0x80 && c < 0xC0)
  39         return 0;                      /* UTF-8 followup character */
  40     else
  41         return 4;                      /* <XY> hex representation */
  42 }
  43
  44 static void pwrite(Ldisc ldisc, unsigned char c)
  45 {
  46     if ((c >= 32 && c <= 126) ||
  47         (!in_utf(ldisc->term) && c >= 0xA0) ||
  48         (in_utf(ldisc->term) && c >= 0x80)) {
  49         c_write(ldisc, (char *)&c, 1);
  50     } else if (c < 128) {
  51         char cc[2];
  52         cc[1] = (c == 127 ? '?' : c + 0x40);
  53         cc[0] = '^';
  54         c_write(ldisc, cc, 2);
  55     } else {
  56         char cc[5];
  57         sprintf(cc, "<%02X>", c);
  58         c_write(ldisc, cc, 4);
  59     }
  60 }
  61
  62 static int char_start(Ldisc ldisc, unsigned char c)
  63 {
  64     if (in_utf(ldisc->term))
  65         return (c < 0x80 || c >= 0xC0);
  66     else
  67         return 1;
  68 }
  69
  70 static void bsb(Ldisc ldisc, int n)
  71 {
  72     while (n--)
  73         c_write(ldisc, "\010 \010", 3);
  74 }
  75
  76 #define CTRL(x) (x^'@')
  77 #define KCTRL(x) ((x^'@') | 0x100)
  78
  79 void *ldisc_create(Config *mycfg, Terminal *term,
  80                    Backend *back, void *backhandle,
  81                    void *frontend)
  82 {
  83     Ldisc ldisc = snew(struct ldisc_tag);
  84
  85     ldisc->buf = NULL;
  86     ldisc->buflen = 0;
  87     ldisc->bufsiz = 0;
  88     ldisc->quotenext = 0;
  89
  90     ldisc->cfg = mycfg;
  91     ldisc->back = back;
  92     ldisc->backhandle = backhandle;
  93     ldisc->term = term;
  94     ldisc->frontend = frontend;
  95
  96     /* Link ourselves into the backend and the terminal */
  97     if (term)
  98         term->ldisc = ldisc;
  99     if (back)
 100         back->provide_ldisc(backhandle, ldisc);
 101
 102     return ldisc;
 103 }
 104
 105 void ldisc_free(void *handle)
 106 {
 107     Ldisc ldisc = (Ldisc) handle;
 108
 109     if (ldisc->term)
 110         ldisc->term->ldisc = NULL;
 111     if (ldisc->back)
 112         ldisc->back->provide_ldisc(ldisc->backhandle, NULL);
 113     if (ldisc->buf)
 114         sfree(ldisc->buf);
 115     sfree(ldisc);
 116 }
 117
 118 void ldisc_send(void *handle, char *buf, int len, int interactive)
 119 {
 120     Ldisc ldisc = (Ldisc) handle;
 121     int keyflag = 0;
 122     /*
 123      * Called with len=0 when the options change. We must inform
 124      * the front end in case it needs to know.
 125      */
 126     if (len == 0) {
 127         ldisc_update(ldisc->frontend, ECHOING, EDITING);
 128         return;
 129     }
 130     /*
 131      * Notify the front end that something was pressed, in case
 132      * it's depending on finding out (e.g. keypress termination for
 133      * Close On Exit).
 134      */
 135     frontend_keypress(ldisc->frontend);
 136
 137     /*
 138      * Less than zero means null terminated special string.
 139      */
 140     if (len < 0) {
 141         len = strlen(buf);
 142         keyflag = KCTRL('@');
 143     }
 144     /*
 145      * Either perform local editing, or just send characters.
 146      */
 147     if (EDITING) {
 148         while (len--) {
 149             int c;
 150             c = (unsigned char)(*buf++) + keyflag;
 151             if (!interactive && c == '\r')
 152                 c += KCTRL('@');
 153             switch (ldisc->quotenext ? ' ' : c) {
 154                 /*
 155                  * ^h/^?: delete, and output BSBs, to return to
 156                  * last character boundary (in UTF-8 mode this may
 157                  * be more than one byte)
 158                  * ^w: delete, and output BSBs, to return to last
 159                  * space/nonspace boundary
 160                  * ^u: delete, and output BSBs, to return to BOL
 161                  * ^c: Do a ^u then send a telnet IP
 162                  * ^z: Do a ^u then send a telnet SUSP
 163                  * ^\: Do a ^u then send a telnet ABORT
 164                  * ^r: echo "^R\n" and redraw line
 165                  * ^v: quote next char
 166                  * ^d: if at BOL, end of file and close connection,
 167                  * else send line and reset to BOL
 168                  * ^m: send line-plus-\r\n and reset to BOL
 169                  */
 170               case KCTRL('H'):
 171               case KCTRL('?'):         /* backspace/delete */
 172                 if (ldisc->buflen > 0) {
 173                     do {
 174                         if (ECHOING)
 175                             bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 176                         ldisc->buflen--;
 177                     } while (!char_start(ldisc, ldisc->buf[ldisc->buflen]));
 178                 }
 179                 break;
 180               case CTRL('W'):          /* delete word */
 181                 while (ldisc->buflen > 0) {
 182                     if (ECHOING)
 183                         bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 184                     ldisc->buflen--;
 185                     if (ldisc->buflen > 0 &&
 186                         isspace((unsigned char)ldisc->buf[ldisc->buflen-1]) &&
 187                         !isspace((unsigned char)ldisc->buf[ldisc->buflen]))
 188                         break;
 189                 }
 190                 break;
 191               case CTRL('U'):          /* delete line */
 192               case CTRL('C'):          /* Send IP */
 193               case CTRL('\\'):         /* Quit */
 194               case CTRL('Z'):          /* Suspend */
 195                 while (ldisc->buflen > 0) {
 196                     if (ECHOING)
 197                         bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 198                     ldisc->buflen--;
 199                 }
 200                 ldisc->back->special(ldisc->backhandle, TS_EL);
 201                 /*
 202                  * We don't send IP, SUSP or ABORT if the user has
 203                  * configured telnet specials off! This breaks
 204                  * talkers otherwise.
 205                  */
 206                 if (!ldisc->cfg->telnet_keyboard)
 207                     goto default_case;
 208                 if (c == CTRL('C'))
 209                     ldisc->back->special(ldisc->backhandle, TS_IP);
 210                 if (c == CTRL('Z'))
 211                     ldisc->back->special(ldisc->backhandle, TS_SUSP);
 212                 if (c == CTRL('\\'))
 213                     ldisc->back->special(ldisc->backhandle, TS_ABORT);
 214                 break;
 215               case CTRL('R'):          /* redraw line */
 216                 if (ECHOING) {
 217                     int i;
 218                     c_write(ldisc, "^R\r\n", 4);
 219                     for (i = 0; i < ldisc->buflen; i++)
 220                         pwrite(ldisc, ldisc->buf[i]);
 221                 }
 222                 break;
 223               case CTRL('V'):          /* quote next char */
 224                 ldisc->quotenext = TRUE;
 225                 break;
 226               case CTRL('D'):          /* logout or send */
 227                 if (ldisc->buflen == 0) {
 228                     ldisc->back->special(ldisc->backhandle, TS_EOF);
 229                 } else {
 230                     ldisc->back->send(ldisc->backhandle, ldisc->buf, ldisc->buflen);
 231                     ldisc->buflen = 0;
 232                 }
 233                 break;
 234                 /*
 235                  * This particularly hideous bit of code from RDB
 236                  * allows ordinary ^M^J to do the same thing as
 237                  * magic-^M when in Raw protocol. The line `case
 238                  * KCTRL('M'):' is _inside_ the if block. Thus:
 239                  *
 240                  *  - receiving regular ^M goes straight to the
 241                  *    default clause and inserts as a literal ^M.
 242                  *  - receiving regular ^J _not_ directly after a
 243                  *    literal ^M (or not in Raw protocol) fails the
 244                  *    if condition, leaps to the bottom of the if,
 245                  *    and falls through into the default clause
 246                  *    again.
 247                  *  - receiving regular ^J just after a literal ^M
 248                  *    in Raw protocol passes the if condition,
 249                  *    deletes the literal ^M, and falls through
 250                  *    into the magic-^M code
 251                  *  - receiving a magic-^M empties the line buffer,
 252                  *    signals end-of-line in one of the various
 253                  *    entertaining ways, and _doesn't_ fall out of
 254                  *    the bottom of the if and through to the
 255                  *    default clause because of the break.
 256                  */
 257               case CTRL('J'):
 258                 if (ldisc->cfg->protocol == PROT_RAW &&
 259                     ldisc->buflen > 0 && ldisc->buf[ldisc->buflen - 1] == '\r') {
 260                     if (ECHOING)
 261                         bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 262                     ldisc->buflen--;
 263                     /* FALLTHROUGH */
 264               case KCTRL('M'):         /* send with newline */
 265                     if (ldisc->buflen > 0)
 266                         ldisc->back->send(ldisc->backhandle, ldisc->buf, ldisc->buflen);
 267                     if (ldisc->cfg->protocol == PROT_RAW)
 268                         ldisc->back->send(ldisc->backhandle, "\r\n", 2);
 269                     else if (ldisc->cfg->protocol == PROT_TELNET && ldisc->cfg->telnet_newline)
 270                         ldisc->back->special(ldisc->backhandle, TS_EOL);
 271                     else
 272                         ldisc->back->send(ldisc->backhandle, "\r", 1);
 273                     if (ECHOING)
 274                         c_write(ldisc, "\r\n", 2);
 275                     ldisc->buflen = 0;
 276                     break;
 277                 }
 278                 /* FALLTHROUGH */
 279               default:                 /* get to this label from ^V handler */
 280                 default_case:
 281                 if (ldisc->buflen >= ldisc->bufsiz) {
 282                     ldisc->bufsiz = ldisc->buflen + 256;
 283                     ldisc->buf = sresize(ldisc->buf, ldisc->bufsiz, char);
 284                 }
 285                 ldisc->buf[ldisc->buflen++] = c;
 286                 if (ECHOING)
 287                     pwrite(ldisc, (unsigned char) c);
 288                 ldisc->quotenext = FALSE;
 289                 break;
 290             }
 291         }
 292     } else {
 293         if (ldisc->buflen != 0) {
 294             ldisc->back->send(ldisc->backhandle, ldisc->buf, ldisc->buflen);
 295             while (ldisc->buflen > 0) {
 296                 bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 297                 ldisc->buflen--;
 298             }
 299         }
 300         if (len > 0) {
 301             if (ECHOING)
 302                 c_write(ldisc, buf, len);
 303             if (keyflag && ldisc->cfg->protocol == PROT_TELNET && len == 1) {
 304                 switch (buf[0]) {
 305                   case CTRL('M'):
 306                     if (ldisc->cfg->protocol == PROT_TELNET && ldisc->cfg->telnet_newline)
 307                         ldisc->back->special(ldisc->backhandle, TS_EOL);
 308                     else
 309                         ldisc->back->send(ldisc->backhandle, "\r", 1);
 310                     break;
 311                   case CTRL('?'):
 312                   case CTRL('H'):
 313                     if (ldisc->cfg->telnet_keyboard) {
 314                         ldisc->back->special(ldisc->backhandle, TS_EC);
 315                         break;
 316                     }
 317                   case CTRL('C'):
 318                     if (ldisc->cfg->telnet_keyboard) {
 319                         ldisc->back->special(ldisc->backhandle, TS_IP);
 320                         break;
 321                     }
 322                   case CTRL('Z'):
 323                     if (ldisc->cfg->telnet_keyboard) {
 324                         ldisc->back->special(ldisc->backhandle, TS_SUSP);
 325                         break;
 326                     }
 327
 328                   default:
 329                     ldisc->back->send(ldisc->backhandle, buf, len);
 330                     break;
 331                 }
 332             } else
 333                 ldisc->back->send(ldisc->backhandle, buf, len);
 334         }
 335     }
 336 }