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
  14 typedef struct ldisc_tag {
  15     Terminal *term;
  16     Backend *back;
  17     void *backhandle;
  18     void *frontend;
  19
  20     char *buf;
  21     int buflen, bufsiz, quotenext;
  22 } *Ldisc;
  23
  24 #define ECHOING (cfg.localecho == LD_YES || \
  25                  (cfg.localecho == LD_BACKEND && \
  26                       (ldisc->back->ldisc(ldisc->backhandle, LD_ECHO) || \
  27                            term_ldisc(ldisc->term, LD_ECHO))))
  28 #define EDITING (cfg.localedit == LD_YES || \
  29                  (cfg.localedit == LD_BACKEND && \
  30                       (ldisc->back->ldisc(ldisc->backhandle, LD_EDIT) || \
  31                            term_ldisc(ldisc->term, LD_EDIT))))
  32
  33 static void c_write(Ldisc ldisc, char *buf, int len)
  34 {
  35     from_backend(ldisc->term, 0, buf, len);
  36 }
  37
  38 static int plen(Ldisc ldisc, unsigned char c)
  39 {
  40     if ((c >= 32 && c <= 126) || (c >= 160 && !in_utf(ldisc->term)))
  41         return 1;
  42     else if (c < 128)
  43         return 2;                      /* ^x for some x */
  44     else
  45         return 4;                      /* <XY> for hex XY */
  46 }
  47
  48 static void pwrite(Ldisc ldisc, unsigned char c)
  49 {
  50     if ((c >= 32 && c <= 126) || (c >= 160 && !in_utf(ldisc->term))) {
  51         c_write(ldisc, &c, 1);
  52     } else if (c < 128) {
  53         char cc[2];
  54         cc[1] = (c == 127 ? '?' : c + 0x40);
  55         cc[0] = '^';
  56         c_write(ldisc, cc, 2);
  57     } else {
  58         char cc[5];
  59         sprintf(cc, "<%02X>", c);
  60         c_write(ldisc, cc, 4);
  61     }
  62 }
  63
  64 static void bsb(Ldisc ldisc, int n)
  65 {
  66     while (n--)
  67         c_write(ldisc, "\010 \010", 3);
  68 }
  69
  70 #define CTRL(x) (x^'@')
  71 #define KCTRL(x) ((x^'@') | 0x100)
  72
  73 void *ldisc_create(Terminal *term,
  74                    Backend *back, void *backhandle,
  75                    void *frontend)
  76 {
  77     Ldisc ldisc = smalloc(sizeof(*ldisc));
  78
  79     ldisc->buf = NULL;
  80     ldisc->buflen = 0;
  81     ldisc->bufsiz = 0;
  82     ldisc->quotenext = 0;
  83
  84     ldisc->back = back;
  85     ldisc->backhandle = backhandle;
  86     ldisc->term = term;
  87     ldisc->frontend = frontend;
  88
  89     /* Link ourselves into the backend and the terminal */
  90     if (term)
  91         term->ldisc = ldisc;
  92     if (back)
  93         back->provide_ldisc(backhandle, ldisc);
  94
  95     return ldisc;
  96 }
  97
  98 void ldisc_send(void *handle, char *buf, int len, int interactive)
  99 {
 100     Ldisc ldisc = (Ldisc) handle;
 101     int keyflag = 0;
 102     /*
 103      * Called with len=0 when the options change. We must inform
 104      * the front end in case it needs to know.
 105      */
 106     if (len == 0) {
 107         ldisc_update(ldisc->frontend, ECHOING, EDITING);
 108         return;
 109     }
 110     /*
 111      * Notify the front end that something was pressed, in case
 112      * it's depending on finding out (e.g. keypress termination for
 113      * Close On Exit).
 114      */
 115     frontend_keypress(ldisc->frontend);
 116
 117     /*
 118      * Less than zero means null terminated special string.
 119      */
 120     if (len < 0) {
 121         len = strlen(buf);
 122         keyflag = KCTRL('@');
 123     }
 124     /*
 125      * Either perform local editing, or just send characters.
 126      */
 127     if (EDITING) {
 128         while (len--) {
 129             int c;
 130             c = *buf++ + keyflag;
 131             if (!interactive && c == '\r')
 132                 c += KCTRL('@');
 133             switch (ldisc->quotenext ? ' ' : c) {
 134                 /*
 135                  * ^h/^?: delete one char and output one BSB
 136                  * ^w: delete, and output BSBs, to return to last
 137                  * space/nonspace boundary
 138                  * ^u: delete, and output BSBs, to return to BOL
 139                  * ^c: Do a ^u then send a telnet IP
 140                  * ^z: Do a ^u then send a telnet SUSP
 141                  * ^\: Do a ^u then send a telnet ABORT
 142                  * ^r: echo "^R\n" and redraw line
 143                  * ^v: quote next char
 144                  * ^d: if at BOL, end of file and close connection,
 145                  * else send line and reset to BOL
 146                  * ^m: send line-plus-\r\n and reset to BOL
 147                  */
 148               case KCTRL('H'):
 149               case KCTRL('?'):         /* backspace/delete */
 150                 if (ldisc->buflen > 0) {
 151                     if (ECHOING)
 152                         bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 153                     ldisc->buflen--;
 154                 }
 155                 break;
 156               case CTRL('W'):          /* delete word */
 157                 while (ldisc->buflen > 0) {
 158                     if (ECHOING)
 159                         bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 160                     ldisc->buflen--;
 161                     if (ldisc->buflen > 0 &&
 162                         isspace(ldisc->buf[ldisc->buflen - 1]) &&
 163                         !isspace(ldisc->buf[ldisc->buflen]))
 164                         break;
 165                 }
 166                 break;
 167               case CTRL('U'):          /* delete line */
 168               case CTRL('C'):          /* Send IP */
 169               case CTRL('\\'):         /* Quit */
 170               case CTRL('Z'):          /* Suspend */
 171                 while (ldisc->buflen > 0) {
 172                     if (ECHOING)
 173                         bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 174                     ldisc->buflen--;
 175                 }
 176                 ldisc->back->special(ldisc->backhandle, TS_EL);
 177                 /*
 178                  * We don't send IP, SUSP or ABORT if the user has
 179                  * configured telnet specials off! This breaks
 180                  * talkers otherwise.
 181                  */
 182                 if (!cfg.telnet_keyboard)
 183                     goto default_case;
 184                 if (c == CTRL('C'))
 185                     ldisc->back->special(ldisc->backhandle, TS_IP);
 186                 if (c == CTRL('Z'))
 187                     ldisc->back->special(ldisc->backhandle, TS_SUSP);
 188                 if (c == CTRL('\\'))
 189                     ldisc->back->special(ldisc->backhandle, TS_ABORT);
 190                 break;
 191               case CTRL('R'):          /* redraw line */
 192                 if (ECHOING) {
 193                     int i;
 194                     c_write(ldisc, "^R\r\n", 4);
 195                     for (i = 0; i < ldisc->buflen; i++)
 196                         pwrite(ldisc, ldisc->buf[i]);
 197                 }
 198                 break;
 199               case CTRL('V'):          /* quote next char */
 200                 ldisc->quotenext = TRUE;
 201                 break;
 202               case CTRL('D'):          /* logout or send */
 203                 if (ldisc->buflen == 0) {
 204                     ldisc->back->special(ldisc->backhandle, TS_EOF);
 205                 } else {
 206                     ldisc->back->send(ldisc->backhandle, ldisc->buf, ldisc->buflen);
 207                     ldisc->buflen = 0;
 208                 }
 209                 break;
 210                 /*
 211                  * This particularly hideous bit of code from RDB
 212                  * allows ordinary ^M^J to do the same thing as
 213                  * magic-^M when in Raw protocol. The line `case
 214                  * KCTRL('M'):' is _inside_ the if block. Thus:
 215                  *
 216                  *  - receiving regular ^M goes straight to the
 217                  *    default clause and inserts as a literal ^M.
 218                  *  - receiving regular ^J _not_ directly after a
 219                  *    literal ^M (or not in Raw protocol) fails the
 220                  *    if condition, leaps to the bottom of the if,
 221                  *    and falls through into the default clause
 222                  *    again.
 223                  *  - receiving regular ^J just after a literal ^M
 224                  *    in Raw protocol passes the if condition,
 225                  *    deletes the literal ^M, and falls through
 226                  *    into the magic-^M code
 227                  *  - receiving a magic-^M empties the line buffer,
 228                  *    signals end-of-line in one of the various
 229                  *    entertaining ways, and _doesn't_ fall out of
 230                  *    the bottom of the if and through to the
 231                  *    default clause because of the break.
 232                  */
 233               case CTRL('J'):
 234                 if (cfg.protocol == PROT_RAW &&
 235                     ldisc->buflen > 0 && ldisc->buf[ldisc->buflen - 1] == '\r') {
 236                     if (ECHOING)
 237                         bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 238                     ldisc->buflen--;
 239                     /* FALLTHROUGH */
 240               case KCTRL('M'):         /* send with newline */
 241                     if (ldisc->buflen > 0)
 242                         ldisc->back->send(ldisc->backhandle, ldisc->buf, ldisc->buflen);
 243                     if (cfg.protocol == PROT_RAW)
 244                         ldisc->back->send(ldisc->backhandle, "\r\n", 2);
 245                     else if (cfg.protocol == PROT_TELNET && cfg.telnet_newline)
 246                         ldisc->back->special(ldisc->backhandle, TS_EOL);
 247                     else
 248                         ldisc->back->send(ldisc->backhandle, "\r", 1);
 249                     if (ECHOING)
 250                         c_write(ldisc, "\r\n", 2);
 251                     ldisc->buflen = 0;
 252                     break;
 253                 }
 254                 /* FALLTHROUGH */
 255               default:                 /* get to this label from ^V handler */
 256                 default_case:
 257                 if (ldisc->buflen >= ldisc->bufsiz) {
 258                     ldisc->bufsiz = ldisc->buflen + 256;
 259                     ldisc->buf = srealloc(ldisc->buf, ldisc->bufsiz);
 260                 }
 261                 ldisc->buf[ldisc->buflen++] = c;
 262                 if (ECHOING)
 263                     pwrite(ldisc, (unsigned char) c);
 264                 ldisc->quotenext = FALSE;
 265                 break;
 266             }
 267         }
 268     } else {
 269         if (ldisc->buflen != 0) {
 270             ldisc->back->send(ldisc->backhandle, ldisc->buf, ldisc->buflen);
 271             while (ldisc->buflen > 0) {
 272                 bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
 273                 ldisc->buflen--;
 274             }
 275         }
 276         if (len > 0) {
 277             if (ECHOING)
 278                 c_write(ldisc, buf, len);
 279             if (keyflag && cfg.protocol == PROT_TELNET && len == 1) {
 280                 switch (buf[0]) {
 281                   case CTRL('M'):
 282                     if (cfg.protocol == PROT_TELNET && cfg.telnet_newline)
 283                         ldisc->back->special(ldisc->backhandle, TS_EOL);
 284                     else
 285                         ldisc->back->send(ldisc->backhandle, "\r", 1);
 286                     break;
 287                   case CTRL('?'):
 288                   case CTRL('H'):
 289                     if (cfg.telnet_keyboard) {
 290                         ldisc->back->special(ldisc->backhandle, TS_EC);
 291                         break;
 292                     }
 293                   case CTRL('C'):
 294                     if (cfg.telnet_keyboard) {
 295                         ldisc->back->special(ldisc->backhandle, TS_IP);
 296                         break;
 297                     }
 298                   case CTRL('Z'):
 299                     if (cfg.telnet_keyboard) {
 300                         ldisc->back->special(ldisc->backhandle, TS_SUSP);
 301                         break;
 302                     }
 303
 304                   default:
 305                     ldisc->back->send(ldisc->backhandle, buf, len);
 306                     break;
 307                 }
 308             } else
 309                 ldisc->back->send(ldisc->backhandle, buf, len);
 310         }
 311     }
 312 }