/*
* 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"
struct Ldisc_tag {
Terminal *term;
Backend *backend;
Seat *seat;
/*
* When the backend is not reporting true from sendok(), terminal
* input that comes here is stored in this bufchain instead. When
* the backend later decides it wants session input, we empty the
* queue in ldisc_check_sendok_callback(), passing its contents on
* to the backend. Before then, we also provide data from this
* queue to term_get_userpass_input() via ldisc_get_input_token(),
* to be interpreted as user responses to username and password
* prompts during authentication.
*
* Unfortunately, the data stored in this queue is not all of the
* same type: our output to the backend consists of both raw bytes
* sent to backend_send(), and also session specials such as
* SS_EOL and SS_EC. So we have to encode our queued data in a way
* that can represent both.
*
* The encoding is private to this source file, so we can change
* it if necessary and only have to worry about the encode and
* decode functions here. Currently, it is:
*
* - Bytes other than 0xFF are stored literally.
* - The byte 0xFF itself is stored as 0xFF 0xFF.
* - A session special (code, arg) is stored as 0xFF, followed by
* a big-endian 4-byte integer containing code, followed by
* another big-endian 4-byte integer containing arg.
*
* (This representation relies on session special codes being at
* most 0xFEFFFFFF when represented in 32 bits, so that the first
* byte of the 'code' integer can't be confused with the 0xFF
* followup byte indicating a literal 0xFF, But since session
* special codes are defined by an enum counting up from zero, and
* there are only a couple of dozen of them, that shouldn't be a
* problem! Even so, just in case, an assertion checks that at
* encode time.)
*/
bufchain input_queue;
IdempotentCallback input_queue_callback;
prompts_t *prompts;
/*
* Values cached out of conf.
*/
bool telnet_keyboard, telnet_newline;
int protocol, localecho, localedit;
char *buf;
size_t buflen, bufsiz;
bool quotenext;
};
#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);
}
static void ldisc_input_queue_callback(void *ctx);
#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;
bufchain_init(&ldisc->input_queue);
ldisc->prompts = NULL;
ldisc->input_queue_callback.fn = ldisc_input_queue_callback;
ldisc->input_queue_callback.ctx = ldisc;
ldisc->input_queue_callback.queued = false;
bufchain_set_callback(&ldisc->input_queue, &ldisc->input_queue_callback);
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)
{
bufchain_clear(&ldisc->input_queue);
if (ldisc->term)
ldisc->term->ldisc = NULL;
if (ldisc->backend)
backend_provide_ldisc(ldisc->backend, NULL);
if (ldisc->buf)
sfree(ldisc->buf);
if (ldisc->prompts && ldisc->prompts->ldisc_ptr_to_us == &ldisc->prompts)
ldisc->prompts->ldisc_ptr_to_us = NULL;
delete_callbacks_for_context(ldisc);
sfree(ldisc);
}
void ldisc_echoedit_update(Ldisc *ldisc)
{
seat_echoedit_update(ldisc->seat, ECHOING, EDITING);
}
void ldisc_enable_prompt_callback(Ldisc *ldisc, prompts_t *prompts)
{
/*
* Called by the terminal to indicate that there's a prompts_t
* currently in flight, or to indicate that one has just finished
* (by passing NULL). When ldisc->prompts is not null, we notify
* the terminal whenever new data arrives in our input queue, so
* that it can continue the interactive prompting process.
*/
ldisc->prompts = prompts;
if (prompts)
ldisc->prompts->ldisc_ptr_to_us = &ldisc->prompts;
}
static void ldisc_input_queue_callback(void *ctx)
{
/*
* Toplevel callback that is triggered whenever the input queue
* lengthens. If we're currently processing an interactive prompt,
* we call back the Terminal to tell it to do some more stuff with
* that prompt based on the new input.
*/
Ldisc *ldisc = (Ldisc *)ctx;
if (ldisc->term && ldisc->prompts) {
/*
* The integer return value from this call is discarded,
* because we have no channel to pass it on to the backend
* that originally wanted it. But that's OK, because if the
* return value is >= 0 (that is, the prompts are either
* completely filled in, or aborted by the user), then the
* terminal will notify the callback in the prompts_t, and
* when that calls term_get_userpass_input again, it will
* return the same answer again.
*/
term_get_userpass_input(ldisc->term, ldisc->prompts);
}
}
static void ldisc_to_backend_raw(
Ldisc *ldisc, const void *vbuf, size_t len)
{
if (backend_sendok(ldisc->backend)) {
backend_send(ldisc->backend, vbuf, len);
} else {
const char *buf = (const char *)vbuf;
while (len > 0) {
/*
* Encode raw data in input_queue, by storing large chunks
* as long as they don't include 0xFF, and pausing every
* time they do to escape it.
*/
const char *ff = memchr(buf, '\xFF', len);
size_t this_len = ff ? ff - buf : len;
if (this_len > 0) {
bufchain_add(&ldisc->input_queue, buf, len);
} else {
bufchain_add(&ldisc->input_queue, "\xFF\xFF", 2);
this_len = 1;
}
buf += this_len;
len -= this_len;
}
}
}
static void ldisc_to_backend_special(
Ldisc *ldisc, SessionSpecialCode code, int arg)
{
if (backend_sendok(ldisc->backend)) {
backend_special(ldisc->backend, code, arg);
} else {
/*
* Encode a session special in input_queue.
*/
unsigned char data[9];
data[0] = 0xFF;
PUT_32BIT_MSB_FIRST(data+1, code);
PUT_32BIT_MSB_FIRST(data+5, arg);
assert(data[1] != 0xFF &&
"SessionSpecialCode encoding collides with FF FF escape");
bufchain_add(&ldisc->input_queue, data, 9);
}
}
bool ldisc_has_input_buffered(Ldisc *ldisc)
{
return bufchain_size(&ldisc->input_queue) > 0;
}
LdiscInputToken ldisc_get_input_token(Ldisc *ldisc)
{
assert(bufchain_size(&ldisc->input_queue) > 0 &&
"You're not supposed to call this unless there is buffered input!");
LdiscInputToken tok;
char c;
bufchain_fetch_consume(&ldisc->input_queue, &c, 1);
if (c != '\xFF') {
/* A literal non-FF byte */
tok.is_special = false;
tok.chr = c;
return tok;
} else {
char data[8];
/* See if the byte after the FF is also FF, indicating a literal FF */
bufchain_fetch_consume(&ldisc->input_queue, data, 1);
if (data[0] == '\xFF') {
tok.is_special = false;
tok.chr = '\xFF';
return tok;
}
/* If not, get the rest of an 8-byte chunk and decode a special */
bufchain_fetch_consume(&ldisc->input_queue, data+1, 7);
tok.is_special = true;
tok.code = GET_32BIT_MSB_FIRST(data);
tok.arg = toint(GET_32BIT_MSB_FIRST(data+4));
return tok;
}
}
static void ldisc_check_sendok_callback(void *ctx)
{
Ldisc *ldisc = (Ldisc *)ctx;
if (!(ldisc->backend && backend_sendok(ldisc->backend)))
return;
/*
* Flush the ldisc input queue into the backend, which is now
* willing to receive the data.
*/
while (bufchain_size(&ldisc->input_queue) > 0) {
/*
* Process either a chunk of non-special data, or an FF
* escape, depending on whether the first thing we see is an
* FF byte.
*/
ptrlen data = bufchain_prefix(&ldisc->input_queue);
const char *ff = memchr(data.ptr, '\xFF', data.len);
if (ff != data.ptr) {
/* Send a maximal block of data not containing any
* difficult bytes. */
if (ff)
data.len = ff - (const char *)data.ptr;
backend_send(ldisc->backend, data.ptr, data.len);
bufchain_consume(&ldisc->input_queue, data.len);
} else {
/* Decode either a special or an escaped FF byte. The
* easiest way to do this is to reuse the decoding code
* already in ldisc_get_input_token. */
LdiscInputToken tok = ldisc_get_input_token(ldisc);
if (tok.is_special)
backend_special(ldisc->backend, tok.code, tok.arg);
else
backend_send(ldisc->backend, &tok.chr, 1);
}
}
}
void ldisc_check_sendok(Ldisc *ldisc)
{
queue_toplevel_callback(ldisc_check_sendok_callback, ldisc);
}
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--;
}
ldisc_to_backend_special(ldisc, 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'))
ldisc_to_backend_special(ldisc, SS_IP, 0);
if (c == CTRL('Z'))
ldisc_to_backend_special(ldisc, SS_SUSP, 0);
if (c == CTRL('\\'))
ldisc_to_backend_special(ldisc, 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) {
ldisc_to_backend_special(ldisc, SS_EOF, 0);
} else {
ldisc_to_backend_raw(ldisc, 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)
ldisc_to_backend_raw(ldisc, ldisc->buf, ldisc->buflen);
if (ldisc->protocol == PROT_RAW)
ldisc_to_backend_raw(ldisc, "\r\n", 2);
else if (ldisc->protocol == PROT_TELNET && ldisc->telnet_newline)
ldisc_to_backend_special(ldisc, SS_EOL, 0);
else
ldisc_to_backend_raw(ldisc, "\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) {
ldisc_to_backend_raw(ldisc, 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)
ldisc_to_backend_special(ldisc, SS_EOL, 0);
else
ldisc_to_backend_raw(ldisc, "\r", 1);
break;
case CTRL('?'):
case CTRL('H'):
if (ldisc->telnet_keyboard) {
ldisc_to_backend_special(ldisc, SS_EC, 0);
break;
}
case CTRL('C'):
if (ldisc->telnet_keyboard) {
ldisc_to_backend_special(ldisc, SS_IP, 0);
break;
}
case CTRL('Z'):
if (ldisc->telnet_keyboard) {
ldisc_to_backend_special(ldisc, SS_SUSP, 0);
break;
}
default:
ldisc_to_backend_raw(ldisc, buf, len);
break;
}
} else
ldisc_to_backend_raw(ldisc, buf, len);
}
}
}