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putty-source/ldisc.c
Simon Tatham 6aa1dcb1ca Remove assertion that len != 0 in ldisc_send. 
A user reported another situation in which that assertion can fail: if
you paste text into the terminal that consists 100% of characters not
available in the CONF_line_codepage character set, then the
translation step generates the empty string as output, and that gets
passed to ldisc_send by term_paste without checking.

Previous bugs of this kind (see commits 4634cd47f7 and 43a63019f5)
were fixed by adding a check before calling ldisc_send. But in commit
4634cd47f7 I said that probably at some point the right fix would be
to remove the assertion in ldisc_send itself, so that passing len==0
becomes legal. (The assertion was there in the first place to catch
cases where len==0 was used with its obsolete special meaning of
signalling 'please update your status'.)

Well, I think it's finally time. The assertion is removed: it's now
legal again to call ldisc_send with an empty buffer, and its meaning
is no longer the archaic special thing, but the trivial one of sending
zero characters through the line discipline.

(cherry picked from commit cd3e917fd0)
2020-06-14 15:49:36 +01:00

344 lines
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/*
* 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 <stdio.h>
#include <ctype.h>
#include <assert.h>
#include "putty.h"
#include "terminal.h"
#include "ldisc.h"
#define ECHOING (ldisc->localecho == FORCE_ON || \
(ldisc->localecho == AUTO && \
(backend_ldisc_option_state(ldisc->backend, LD_ECHO))))
#define EDITING (ldisc->localedit == FORCE_ON || \
(ldisc->localedit == AUTO && \
(backend_ldisc_option_state(ldisc->backend, LD_EDIT))))
static void c_write(Ldisc *ldisc, const void *buf, int len)
{
seat_stdout(ldisc->seat, buf, len);
}
static int plen(Ldisc *ldisc, unsigned char c)
{
if ((c >= 32 && c <= 126) || (c >= 160 && !in_utf(ldisc->term)))
return 1;
else if (c < 128)
return 2; /* ^x for some x */
else if (in_utf(ldisc->term) && c >= 0xC0)
return 1; /* UTF-8 introducer character
* (FIXME: combining / wide chars) */
else if (in_utf(ldisc->term) && c >= 0x80 && c < 0xC0)
return 0; /* UTF-8 followup character */
else
return 4; /* <XY> hex representation */
}
static void pwrite(Ldisc *ldisc, unsigned char c)
{
if ((c >= 32 && c <= 126) ||
(!in_utf(ldisc->term) && c >= 0xA0) ||
(in_utf(ldisc->term) && c >= 0x80)) {
c_write(ldisc, &c, 1);
} else if (c < 128) {
char cc[2];
cc[1] = (c == 127 ? '?' : c + 0x40);
cc[0] = '^';
c_write(ldisc, cc, 2);
} else {
char cc[5];
sprintf(cc, "<%02X>", c);
c_write(ldisc, cc, 4);
}
}
static bool char_start(Ldisc *ldisc, unsigned char c)
{
if (in_utf(ldisc->term))
return (c < 0x80 || c >= 0xC0);
else
return true;
}
static void bsb(Ldisc *ldisc, int n)
{
while (n--)
c_write(ldisc, "\010 \010", 3);
}
#define CTRL(x) (x^'@')
#define KCTRL(x) ((x^'@') | 0x100)
Ldisc *ldisc_create(Conf *conf, Terminal *term, Backend *backend, Seat *seat)
{
Ldisc *ldisc = snew(Ldisc);
ldisc->buf = NULL;
ldisc->buflen = 0;
ldisc->bufsiz = 0;
ldisc->quotenext = false;
ldisc->backend = backend;
ldisc->term = term;
ldisc->seat = seat;
ldisc_configure(ldisc, conf);
/* Link ourselves into the backend and the terminal */
if (term)
term->ldisc = ldisc;
if (backend)
backend_provide_ldisc(backend, ldisc);
return ldisc;
}
void ldisc_configure(Ldisc *ldisc, Conf *conf)
{
ldisc->telnet_keyboard = conf_get_bool(conf, CONF_telnet_keyboard);
ldisc->telnet_newline = conf_get_bool(conf, CONF_telnet_newline);
ldisc->protocol = conf_get_int(conf, CONF_protocol);
ldisc->localecho = conf_get_int(conf, CONF_localecho);
ldisc->localedit = conf_get_int(conf, CONF_localedit);
}
void ldisc_free(Ldisc *ldisc)
{
if (ldisc->term)
ldisc->term->ldisc = NULL;
if (ldisc->backend)
backend_provide_ldisc(ldisc->backend, NULL);
if (ldisc->buf)
sfree(ldisc->buf);
sfree(ldisc);
}
void ldisc_echoedit_update(Ldisc *ldisc)
{
seat_echoedit_update(ldisc->seat, ECHOING, EDITING);
}
void ldisc_send(Ldisc *ldisc, const void *vbuf, int len, bool interactive)
{
const char *buf = (const char *)vbuf;
int keyflag = 0;
assert(ldisc->term);
if (interactive) {
/*
* Interrupt a paste from the clipboard, if one was in
* progress when the user pressed a key. This is easier than
* buffering the current piece of data and saving it until the
* terminal has finished pasting, and has the potential side
* benefit of permitting a user to cancel an accidental huge
* paste.
*/
term_nopaste(ldisc->term);
}
/*
* Less than zero means null terminated special string.
*/
if (len < 0) {
len = strlen(buf);
keyflag = KCTRL('@');
}
/*
* Either perform local editing, or just send characters.
*/
if (EDITING) {
while (len--) {
int c;
c = (unsigned char)(*buf++) + keyflag;
if (!interactive && c == '\r')
c += KCTRL('@');
switch (ldisc->quotenext ? ' ' : c) {
/*
* ^h/^?: delete, and output BSBs, to return to
* last character boundary (in UTF-8 mode this may
* be more than one byte)
* ^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 KCTRL('H'):
case KCTRL('?'): /* backspace/delete */
if (ldisc->buflen > 0) {
do {
if (ECHOING)
bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
ldisc->buflen--;
} while (!char_start(ldisc, ldisc->buf[ldisc->buflen]));
}
break;
case CTRL('W'): /* delete word */
while (ldisc->buflen > 0) {
if (ECHOING)
bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
ldisc->buflen--;
if (ldisc->buflen > 0 &&
isspace((unsigned char)ldisc->buf[ldisc->buflen-1]) &&
!isspace((unsigned char)ldisc->buf[ldisc->buflen]))
break;
}
break;
case CTRL('U'): /* delete line */
case CTRL('C'): /* Send IP */
case CTRL('\\'): /* Quit */
case CTRL('Z'): /* Suspend */
while (ldisc->buflen > 0) {
if (ECHOING)
bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
ldisc->buflen--;
}
backend_special(ldisc->backend, SS_EL, 0);
/*
* We don't send IP, SUSP or ABORT if the user has
* configured telnet specials off! This breaks
* talkers otherwise.
*/
if (!ldisc->telnet_keyboard)
goto default_case;
if (c == CTRL('C'))
backend_special(ldisc->backend, SS_IP, 0);
if (c == CTRL('Z'))
backend_special(ldisc->backend, SS_SUSP, 0);
if (c == CTRL('\\'))
backend_special(ldisc->backend, SS_ABORT, 0);
break;
case CTRL('R'): /* redraw line */
if (ECHOING) {
int i;
c_write(ldisc, "^R\r\n", 4);
for (i = 0; i < ldisc->buflen; i++)
pwrite(ldisc, ldisc->buf[i]);
}
break;
case CTRL('V'): /* quote next char */
ldisc->quotenext = true;
break;
case CTRL('D'): /* logout or send */
if (ldisc->buflen == 0) {
backend_special(ldisc->backend, SS_EOF, 0);
} else {
backend_send(ldisc->backend, ldisc->buf, ldisc->buflen);
ldisc->buflen = 0;
}
break;
/*
* This particularly hideous bit of code from RDB
* allows ordinary ^M^J to do the same thing as
* magic-^M when in Raw protocol. The line `case
* KCTRL('M'):' is _inside_ the if block. Thus:
*
* - receiving regular ^M goes straight to the
* default clause and inserts as a literal ^M.
* - receiving regular ^J _not_ directly after a
* literal ^M (or not in Raw protocol) fails the
* if condition, leaps to the bottom of the if,
* and falls through into the default clause
* again.
* - receiving regular ^J just after a literal ^M
* in Raw protocol passes the if condition,
* deletes the literal ^M, and falls through
* into the magic-^M code
* - receiving a magic-^M empties the line buffer,
* signals end-of-line in one of the various
* entertaining ways, and _doesn't_ fall out of
* the bottom of the if and through to the
* default clause because of the break.
*/
case CTRL('J'):
if (ldisc->protocol == PROT_RAW &&
ldisc->buflen > 0 && ldisc->buf[ldisc->buflen - 1] == '\r') {
if (ECHOING)
bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
ldisc->buflen--;
/* FALLTHROUGH */
case KCTRL('M'): /* send with newline */
if (ldisc->buflen > 0)
backend_send(ldisc->backend,
ldisc->buf, ldisc->buflen);
if (ldisc->protocol == PROT_RAW)
backend_send(ldisc->backend, "\r\n", 2);
else if (ldisc->protocol == PROT_TELNET && ldisc->telnet_newline)
backend_special(ldisc->backend, SS_EOL, 0);
else
backend_send(ldisc->backend, "\r", 1);
if (ECHOING)
c_write(ldisc, "\r\n", 2);
ldisc->buflen = 0;
break;
}
/* FALLTHROUGH */
default: /* get to this label from ^V handler */
default_case:
sgrowarray(ldisc->buf, ldisc->bufsiz, ldisc->buflen);
ldisc->buf[ldisc->buflen++] = c;
if (ECHOING)
pwrite(ldisc, (unsigned char) c);
ldisc->quotenext = false;
break;
}
}
} else {
if (ldisc->buflen != 0) {
backend_send(ldisc->backend, ldisc->buf, ldisc->buflen);
while (ldisc->buflen > 0) {
bsb(ldisc, plen(ldisc, ldisc->buf[ldisc->buflen - 1]));
ldisc->buflen--;
}
}
if (len > 0) {
if (ECHOING)
c_write(ldisc, buf, len);
if (keyflag && ldisc->protocol == PROT_TELNET && len == 1) {
switch (buf[0]) {
case CTRL('M'):
if (ldisc->protocol == PROT_TELNET && ldisc->telnet_newline)
backend_special(ldisc->backend, SS_EOL, 0);
else
backend_send(ldisc->backend, "\r", 1);
break;
case CTRL('?'):
case CTRL('H'):
if (ldisc->telnet_keyboard) {
backend_special(ldisc->backend, SS_EC, 0);
break;
}
case CTRL('C'):
if (ldisc->telnet_keyboard) {
backend_special(ldisc->backend, SS_IP, 0);
break;
}
case CTRL('Z'):
if (ldisc->telnet_keyboard) {
backend_special(ldisc->backend, SS_SUSP, 0);
break;
}
default:
backend_send(ldisc->backend, buf, len);
break;
}
} else
backend_send(ldisc->backend, buf, len);
}
}
}
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