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