putty/ldisc.c

/*
 * ldisc.c: PuTTY line discipline. Sits between the input coming
 * from keypresses in the window, and the output channel leading to
 * the back end. Implements echo and/or local line editing,
 * depending on what's currently configured.
 */

#include <windows.h>
#include <stdio.h>
#include <ctype.h>

#include "putty.h"

#define ECHOING (cfg.localecho == LD_YES || \
                 (cfg.localecho == LD_BACKEND && \
                      (back->ldisc(LD_ECHO) || term_ldisc(LD_ECHO))))
#define EDITING (cfg.localedit == LD_YES || \
                 (cfg.localedit == LD_BACKEND && \
                      (back->ldisc(LD_EDIT) || term_ldisc(LD_EDIT))))

static void c_write (char *buf, int len) {
    from_backend(0, buf, len);
}

static char *term_buf = NULL;
static int term_buflen = 0, term_bufsiz = 0, term_quotenext = 0;

static int plen(unsigned char c) {
    if ((c >= 32 && c <= 126) ||
        (c >= 160))
        return 1;
    else if (c < 128)
        return 2;                      /* ^x for some x */
    else
        return 4;                      /* <XY> for hex XY */
}

static void pwrite(unsigned char c) {
    if ((c >= 32 && c <= 126) ||
        (c >= 160)) {
        c_write(&c, 1);
    } else if (c < 128) {
        char cc[2];
        cc[1] = (c == 127 ? '?' : c + 0x40);
        cc[0] = '^';
        c_write(cc, 2);
    } else {
        char cc[5];
        sprintf(cc, "<%02X>", c);
        c_write(cc, 4);
    }
}

static void bsb(int n) {
    while (n--)
	c_write("\010 \010", 3);
}

#define CTRL(x) (x^'@')

void ldisc_send(char *buf, int len) {
    /*
     * Called with len=0 when the options change. We must inform
     * the front end in case it needs to know.
     */
    if (len == 0) {
        void ldisc_update(int echo, int edit);
        ldisc_update(ECHOING, EDITING);
    }
    /*
     * Either perform local editing, or just send characters.
     */
    if (EDITING) {
        while (len--) {
            char c;
            c = *buf++;
            switch (term_quotenext ? ' ' : c) {
                /*
                 * ^h/^?: delete one char and output one BSB
                 * ^w: delete, and output BSBs, to return to last
                 * space/nonspace boundary
                 * ^u: delete, and output BSBs, to return to BOL
                 * ^c: Do a ^u then send a telnet IP
                 * ^z: Do a ^u then send a telnet SUSP
                 * ^\: Do a ^u then send a telnet ABORT
                 * ^r: echo "^R\n" and redraw line
                 * ^v: quote next char
                 * ^d: if at BOL, end of file and close connection,
                 * else send line and reset to BOL
                 * ^m: send line-plus-\r\n and reset to BOL
                 */
              case CTRL('H'): case CTRL('?'):      /* backspace/delete */
                if (term_buflen > 0) {
                    if (ECHOING)
                        bsb(plen(term_buf[term_buflen-1]));
                    term_buflen--;
                }
                break;
              case CTRL('W'):		       /* delete word */
                while (term_buflen > 0) {
                    if (ECHOING)
                        bsb(plen(term_buf[term_buflen-1]));
                    term_buflen--;
                    if (term_buflen > 0 &&
                        isspace(term_buf[term_buflen-1]) &&
                        !isspace(term_buf[term_buflen]))
                        break;
                }
                break;
              case CTRL('U'):	       /* delete line */
              case CTRL('C'):	       /* Send IP */
              case CTRL('\\'):	       /* Quit */
              case CTRL('Z'):	       /* Suspend */
                while (term_buflen > 0) {
                    if (ECHOING)
                        bsb(plen(term_buf[term_buflen-1]));
                    term_buflen--;
                }
                back->special (TS_EL);
                if( c == CTRL('C') )  back->special (TS_IP);
                if( c == CTRL('Z') )  back->special (TS_SUSP);
                if( c == CTRL('\\') ) back->special (TS_ABORT);
                break;
              case CTRL('R'):	       /* redraw line */
                if (ECHOING) {
                    int i;
                    c_write("^R\r\n", 4);
                    for (i = 0; i < term_buflen; i++)
                        pwrite(term_buf[i]);
                }
                break;
              case CTRL('V'):	       /* quote next char */
                term_quotenext = TRUE;
                break;
              case CTRL('D'):	       /* logout or send */
                if (term_buflen == 0) {
                    back->special (TS_EOF);
                } else {
                    back->send(term_buf, term_buflen);
                    term_buflen = 0;
                }
                break;
              case CTRL('M'):	       /* send with newline */
                if (term_buflen > 0)
                    back->send(term_buf, term_buflen);
                if (cfg.protocol == PROT_RAW)
                    back->send("\r\n", 2);
                else
                    back->send("\r", 1);
                if (ECHOING)
                    c_write("\r\n", 2);
                term_buflen = 0;
                break;
              default:                     /* get to this label from ^V handler */
                if (term_buflen >= term_bufsiz) {
                    term_bufsiz = term_buflen + 256;
                    term_buf = saferealloc(term_buf, term_bufsiz);
                }
                term_buf[term_buflen++] = c;
                if (ECHOING)
                    pwrite(c);
                term_quotenext = FALSE;
                break;
            }
        }
    } else {
        if( term_buflen != 0 )
        {
            back->send(term_buf, term_buflen);
            while (term_buflen > 0) {
                bsb(plen(term_buf[term_buflen-1]));
                term_buflen--;
            }
        }
        if (len > 0) {
            if (ECHOING)
                c_write(buf, len);
            back->send(buf, len);
        }
    }
}