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