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putty-source/supdup.c

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Add support for the SUPDUP protocol. Based on work by Josh Dersch, with permission.
2019-04-02 10:16:25 +00:00
/*
* Supdup backend
*/
#include <stdio.h>
#include <stdlib.h>
#include <limits.h>
#include "putty.h"
/*
* TTYOPT FUNCTION BITS (36-bit bitmasks)
*/
#define TOALT 0200000000000LL // Characters 0175 and 0176 are converted to altmode (0033) on input
#define TOCLC 0100000000000LL // (user option bit) Convert lower-case input to upper-case
#define TOERS 0040000000000LL // Selective erase is supported
#define TOMVB 0010000000000LL // Backspacing is supported
#define TOSAI 0004000000000LL // Stanford/ITS extended ASCII graphics character set is supported
#define TOSA1 0002000000000LL // (user option bit) Characters 0001-0037 displayed using Stanford/ITS chars
#define TOOVR 0001000000000LL // Overprinting is supported
#define TOMVU 0000400000000LL // Moving cursor upwards is supported
#define TOMOR 0000200000000LL // (user option bit) System should provide **MORE** processing
#define TOROL 0000100000000LL // (user option bit) Terminal should scroll instead of wrapping
#define TOLWR 0000020000000LL // Lowercase characters are supported
#define TOFCI 0000010000000LL // Terminal can generate CONTROL and META characters
#define TOLID 0000002000000LL // Line insert/delete operations supported
#define TOCID 0000001000000LL // Character insert/delete operations supported
#define TPCBS 0000000000040LL // Terminal is using the "intelligent terminal protocol" (must be on)
#define TPORS 0000000000010LL // Server should process output resets
// Initialization words (36-bit constants)
#define WORDS 0777773000000 // Negative number of config words to send (6) in high 18 bits
#define TCTYP 0000000000007 // Defines the terminal type (MUST be 7)
#define TTYROL 0000000000001 // Scroll amount for terminal (1 line at a time)
// %TD opcodes
//
#define TDMOV 0200 // Cursor positioning
#define TDMV1 0201 // Internal cursor positioning
#define TDEOF 0202 // Erase to end of screen
#define TDEOL 0203 // Erase to end of line
#define TDDLF 0204 // Clear the character the cursor is on
#define TDCRL 0207 // Carriage return
#define TDNOP 0210 // No-op; should be ignored.
#define TDBS 0211 // Backspace (not in official SUPDUP spec)
#define TDLF 0212 // Linefeed (not in official SUPDUP spec)
#define TDCR 0213 // Carriage Return (ditto)
#define TDORS 0214 // Output reset
#define TDQOT 0215 // Quotes the following character
#define TDFS 0216 // Non-destructive forward space
#define TDMV0 0217 // General cursor positioning code
#define TDCLR 0220 // Erase the screen, home cursor
#define TDBEL 0221 // Generate an audio tone, bell, whatever
#define TDILP 0223 // Insert blank lines at the cursor
#define TDDLP 0224 // Delete lines at the cursor
#define TDICP 0225 // Insert blanks at cursor
#define TDDCP 0226 // Delete characters at cursor
#define TDBOW 0227 // Display black chars on white screen
#define TDRST 0230 // Reset %TDBOW
/* Maximum number of octets following a %TD code. */
#define TD_ARGS_MAX 4
typedef struct supdup_tag Supdup;
struct supdup_tag
{
Socket *s;
bool closed_on_socket_error;
Seat *seat;
LogContext *logctx;
int term_width, term_height;
long long ttyopt;
long tcmxv;
long tcmxh;
bool sent_location;
Conf *conf;
int bufsize;
enum {
CONNECTING, // waiting for %TDNOP from server after sending connection params
CONNECTED // %TDNOP received, connected.
} state;
enum {
TD_TOPLEVEL,
TD_ARGS,
TD_ARGSDONE
} tdstate;
int td_code;
int td_argcount;
char td_args[TD_ARGS_MAX];
int td_argindex;
void (*print) (strbuf *outbuf, int c);
Pinger *pinger;
Plug plug;
Backend backend;
};
#define SUPDUP_MAX_BACKLOG 4096
static void c_write(Supdup *supdup, unsigned char *buf, int len)
{
size_t backlog = seat_stdout(supdup->seat, buf, len);
sk_set_frozen(supdup->s, backlog > SUPDUP_MAX_BACKLOG);
}
static void supdup_send_location(Supdup *supdup)
{
char locHeader[] = { 0300, 0302 };
char* locString = conf_get_str(supdup->conf, CONF_supdup_location);
sk_write(supdup->s, locHeader, sizeof(locHeader));
sk_write(supdup->s, locString, strlen(locString) + 1); // include NULL terminator
}
static void print_ascii(strbuf *outbuf, int c)
{
/* In ASCII mode, ignore control characters. The server shouldn't
send them. */
if (c >= 040 && c < 0177)
put_byte (outbuf, c);
}
static void print_its(strbuf *outbuf, int c)
{
/* The ITS character set is documented in RFC 734. */
static const char *map[] = {
"\xc2\xb7", "\342\206\223", "\316\261", "\316\262",
"\342\210\247", "\302\254", "\316\265", "\317\200",
"\316\273", "\xce\xb3", "\xce\xb4", "\xe2\x86\x91",
"\xc2\xb1", "\xe2\x8a\x95", "\342\210\236", "\342\210\202",
"\342\212\202", "\342\212\203", "\342\210\251", "\342\210\252",
"\342\210\200", "\342\210\203", "\xe2\x8a\x97", "\342\206\224",
"\xe2\x86\x90", "\342\206\222", "\xe2\x89\xa0", "\xe2\x97\x8a",
"\342\211\244", "\342\211\245", "\342\211\241", "\342\210\250",
" ", "!", "\"", "#", "$", "%", "&", "'",
"(", ")", "*", "+", ",", "-", ".", "/",
"0", "1", "2", "3", "4", "5", "6", "7",
"8", "9", ":", ";", "<", "=", ">", "?",
"@", "A", "B", "C", "D", "E", "F", "G",
"H", "I", "J", "K", "L", "M", "N", "O",
"P", "Q", "R", "S", "T", "U", "V", "W",
"X", "Y", "Z", "[", "\\", "]", "^", "_",
"`", "a", "b", "c", "d", "e", "f", "g",
"h", "i", "j", "k", "l", "m", "n", "o",
"p", "q", "r", "s", "t", "u", "v", "w",
"x", "y", "z", "{", "|", "}", "~", "\xe2\x88\xab"
};
put_data (outbuf, map[c], strlen(map[c]));
}
static void print_waits(strbuf *outbuf, int c)
{
/* The WAITS character set used at the Stanford AI Lab is documented
here: https://www.saildart.org/allow/sail-charset-utf8.html */
static const char *map[] = {
"", "\342\206\223", "\316\261", "\316\262",
"\342\210\247", "\302\254", "\316\265", "\317\200",
"\316\273", "", "", "",
"", "", "\342\210\236", "\342\210\202",
"\342\212\202", "\342\212\203", "\342\210\251", "\342\210\252",
"\342\210\200", "\342\210\203", "\xe2\x8a\x97", "\342\206\224",
"_", "\342\206\222", "~", "\xe2\x89\xa0",
"\342\211\244", "\342\211\245", "\342\211\241", "\342\210\250",
" ", "!", "\"", "#", "$", "%", "&", "'",
"(", ")", "*", "+", ",", "-", ".", "/",
"0", "1", "2", "3", "4", "5", "6", "7",
"8", "9", ":", ";", "<", "=", ">", "?",
"@", "A", "B", "C", "D", "E", "F", "G",
"H", "I", "J", "K", "L", "M", "N", "O",
"P", "Q", "R", "S", "T", "U", "V", "W",
"X", "Y", "Z", "[", "\\", "]", "\xe2\x86\x91", "\xe2\x86\x90",
"`", "a", "b", "c", "d", "e", "f", "g",
"h", "i", "j", "k", "l", "m", "n", "o",
"p", "q", "r", "s", "t", "u", "v", "w",
"x", "y", "z", "{", "|", "\xe2\x97\x8a", "}", ""
};
put_data (outbuf, map[c], strlen(map[c]));
}
static void do_toplevel(Supdup *supdup, strbuf *outbuf, int c)
{
// Toplevel: Waiting for a %TD code or a printable character
if (c >= 0200) {
// Handle SUPDUP %TD codes (codes greater than or equal to 200)
supdup->td_argindex = 0;
supdup->td_code = c;
switch (c) {
case TDMOV:
// %TD codes using 4 arguments
supdup->td_argcount = 4;
supdup->tdstate = TD_ARGS;
break;
case TDMV0:
case TDMV1:
// %TD codes using 2 arguments
supdup->td_argcount = 2;
supdup->tdstate = TD_ARGS;
break;
case TDQOT:
case TDILP:
case TDDLP:
case TDICP:
case TDDCP:
// %TD codes using 1 argument
supdup->td_argcount = 1;
supdup->tdstate = TD_ARGS;
break;
case TDEOF:
case TDEOL:
case TDDLF:
case TDCRL:
case TDNOP:
case TDORS:
case TDFS:
case TDCLR:
case TDBEL:
case TDBOW:
case TDRST:
case TDBS:
case TDCR:
case TDLF:
// %TD codes using 0 arguments
supdup->td_argcount = 0;
supdup->tdstate = TD_ARGSDONE;
break;
default:
// Unhandled, ignore
break;
}
} else {
supdup->print(outbuf, c);
}
}
static void do_args(Supdup *supdup, strbuf *outbuf, int c)
{
// Collect up args for %TD code
if (supdup->td_argindex < TD_ARGS_MAX) {
supdup->td_args[supdup->td_argindex] = c;
supdup->td_argindex++;
if (supdup->td_argcount == supdup->td_argindex) {
// No more args, %TD code is ready to go.
supdup->tdstate = TD_ARGSDONE;
}
} else {
// Should never hit this state, if we do we will just
// return to TOPLEVEL.
supdup->tdstate = TD_TOPLEVEL;
}
}
static void do_argsdone(Supdup *supdup, strbuf *outbuf, int c)
{
char buf[4];
int x, y;
// Arguments for %TD code have been collected; dispatch based
// on the %TD code we're handling.
switch (supdup->td_code) {
case TDMOV:
/*
General cursor position code. Followed by four bytes;
the first two are the "old" vertical and horizontal
positions and may be ignored. The next two are the new
vertical and horizontal positions. The cursor should be
moved to this position.
*/
// We only care about the new position.
strbuf_catf(outbuf, "\033[%d;%dH", supdup->td_args[2]+1, supdup->td_args[3]+1);
break;
case TDMV0:
case TDMV1:
/*
General cursor position code. Followed by two bytes;
the new vertical and horizontal positions.
*/
strbuf_catf(outbuf, "\033[%d;%dH", supdup->td_args[0]+1, supdup->td_args[1]+1);
break;
case TDEOF:
/*
Erase to end of screen. This is an optional function
since many terminals do not support this. If the
terminal does not support this function, it should be
treated the same as %TDEOL.
%TDEOF does an erase to end of line, then erases all
lines lower on the screen than the cursor. The cursor
does not move.
*/
strbuf_catf(outbuf, "\033[J");
break;
case TDEOL:
/*
Erase to end of line. This erases the character
position the cursor is at and all positions to the right
on the same line. The cursor does not move.
*/
strbuf_catf(outbuf, "\033[K");
break;
case TDDLF:
/*
Clear the character position the cursor is on. The
cursor does not move.
*/
strbuf_catf(outbuf, "\033[X");
break;
case TDCRL:
/*
If the cursor is not on the bottom line of the screen,
move cursor to the beginning of the next line and clear
that line. If the cursor is at the bottom line, scroll
up.
*/
strbuf_catf(outbuf, "\015\012");
break;
case TDNOP:
/*
No-op; should be ignored.
*/
break;
case TDORS:
/*
Output reset. This code serves as a data mark for
aborting output much as IAC DM does in the ordinary
TELNET protocol.
*/
outbuf->len = 0;
if (!seat_get_cursor_position(supdup->seat, &x, &y))
x = y = 0;
buf[0] = 034;
buf[1] = 020;
buf[2] = y;
buf[3] = x;
sk_write(supdup->s, buf, 4);
break;
case TDQOT:
/*
Quotes the following character. This is used when
sending 8-bit codes which are not %TD codes, for
instance when loading programs into an intelligent
terminal. The following character should be passed
through intact to the terminal.
*/
put_byte(outbuf, supdup->td_args[0]);
break;
case TDFS:
/*
Non-destructive forward space. The cursor moves right
one position; this code will not be sent at the end of a
line.
*/
strbuf_catf(outbuf, "\033[C");
break;
case TDCLR:
/*
Erase the screen. Home the cursor to the top left hand
corner of the screen.
*/
strbuf_catf(outbuf, "\033[2J\033[H");
break;
case TDBEL:
/*
Generate an audio tone, bell, whatever.
*/
strbuf_catf(outbuf, "\007");
break;
case TDILP:
/*
Insert blank lines at the cursor; followed by a byte
containing a count of the number of blank lines to
insert. The cursor is unmoved. The line the cursor is
on and all lines below it move down; lines moved off the
bottom of the screen are lost.
*/
strbuf_catf(outbuf, "\033[%dL", supdup->td_args[0]);
break;
case TDDLP:
/*
Delete lines at the cursor; followed by a count. The
cursor is unmoved. The first line deleted is the one
the cursor is on. Lines below those deleted move up.
Newly- created lines at the bottom of the screen are
blank.
*/
strbuf_catf(outbuf, "\033[%dM", supdup->td_args[0]);
break;
case TDICP:
/*
Insert blank character positions at the cursor; followed
by a count. The cursor is unmoved. The character the
cursor is on and all characters to the right on the
current line move to the right; characters moved off the
end of the line are lost.
*/
strbuf_catf(outbuf, "\033[%d@", supdup->td_args[0]);
break;
case TDDCP:
/*
Delete characters at the cursor; followed by a count.
The cursor is unmoved. The first character deleted is
the one the cursor is on. Newly-created characters at
the end of the line are blank.
*/
strbuf_catf(outbuf, "\033[%dP", supdup->td_args[0]);
break;
case TDBOW:
case TDRST:
/*
Display black characters on white screen.
HIGHLY OPTIONAL.
*/
// Since this is HIGHLY OPTIONAL, I'm not going
// to implement it yet.
break;
/*
* Non-standard (whatever "standard" means here) SUPDUP
* commands. These are used (at the very least) by
* Genera's SUPDUP implementation. Cannot find any
* official documentation, behavior is based on UNIX
* SUPDUP implementation from MIT.
*/
case TDBS:
/*
* Backspace -- move cursor back one character (does not
* appear to wrap...)
*/
put_byte(outbuf, '\010');
break;
case TDLF:
/*
* Linefeed -- move cursor down one line (again, no wrapping)
*/
put_byte(outbuf, '\012');
break;
case TDCR:
/*
* Carriage return -- move cursor to start of current line.
*/
put_byte(outbuf, '\015');
break;
}
// Return to top level to pick up the next %TD code or
// printable character.
supdup->tdstate = TD_TOPLEVEL;
}
static void term_out_supdup(Supdup *supdup, strbuf *outbuf, int c)
{
if (supdup->tdstate == TD_TOPLEVEL) {
do_toplevel (supdup, outbuf, c);
} else if (supdup->tdstate == TD_ARGS) {
do_args (supdup, outbuf, c);
}
// If all arguments for a %TD code are ready, we will execute the code now.
if (supdup->tdstate == TD_ARGSDONE) {
do_argsdone (supdup, outbuf, c);
}
}
static void do_supdup_read(Supdup *supdup, const char *buf, size_t len)
{
strbuf *outbuf = strbuf_new();
while (len--) {
int c = (unsigned char)*buf++;
switch (supdup->state) {
case CONNECTING:
// "Following the transmission of the terminal options by
// the user, the server should respond with an ASCII
// greeting message, terminated with a %TDNOP code..."
if (TDNOP == c) {
// Greeting done, switch to the CONNECTED state.
supdup->state = CONNECTED;
supdup->tdstate = TD_TOPLEVEL;
} else {
// Forward the greeting message (which is straight
// ASCII, no controls) on so it gets displayed TODO:
// filter out only printable chars?
put_byte(outbuf, c);
}
break;
case CONNECTED:
// "All transmissions from the server after the %TDNOP
// [see above] are either printing characters or virtual
// terminal display codes." Forward these on to the
// frontend which will decide what to do with them.
term_out_supdup(supdup, outbuf, c);
/*
* Hack to make Symbolics Genera SUPDUP happy: Wait until
* after we're connected (finished the initial handshake
* and have gotten additional data) before sending the
* location string. For some reason doing so earlier
* causes the Symbolics SUPDUP to end up in an odd state.
*/
if (!supdup->sent_location) {
supdup_send_location(supdup);
supdup->sent_location = true;
}
break;
}
if (outbuf->len >= 4096) {
c_write(supdup, outbuf->u, outbuf->len);
outbuf->len = 0;
}
}
if (outbuf->len)
c_write(supdup, outbuf->u, outbuf->len);
strbuf_free(outbuf);
}
static void supdup_log(Plug *plug, PlugLogType type, SockAddr *addr, int port,
const char *error_msg, int error_code)
{
Supdup *supdup = container_of(plug, Supdup, plug);
backend_socket_log(supdup->seat, supdup->logctx, type, addr, port,
error_msg, error_code,
supdup->conf, supdup->state != CONNECTING);
}
static void supdup_closing(Plug *plug, const char *error_msg, int error_code,
bool calling_back)
{
Supdup *supdup = container_of(plug, Supdup, plug);
/*
* We don't implement independent EOF in each direction for Telnet
* connections; as soon as we get word that the remote side has
* sent us EOF, we wind up the whole connection.
*/
if (supdup->s) {
sk_close(supdup->s);
supdup->s = NULL;
if (error_msg)
supdup->closed_on_socket_error = true;
seat_notify_remote_exit(supdup->seat);
}
if (error_msg) {
logevent(supdup->logctx, error_msg);
seat_connection_fatal(supdup->seat, "%s", error_msg);
}
/* Otherwise, the remote side closed the connection normally. */
}
static void supdup_receive(Plug *plug, int urgent, const char *data, size_t len)
{
Supdup *supdup = container_of(plug, Supdup, plug);
do_supdup_read(supdup, data, len);
}
static void supdup_sent(Plug *plug, size_t bufsize)
{
Supdup *supdup = container_of(plug, Supdup, plug);
supdup->bufsize = bufsize;
}
static void supdup_send_36bits(Supdup *supdup, unsigned long long thirtysix)
{
//
// From RFC734:
// "Each word is sent through the 8-bit connection as six
// 6-bit bytes, most-significant first."
//
// Split the 36-bit word into 6 6-bit "bytes", packed into
// 8-bit bytes and send, most-significant byte first.
//
for (int i = 5; i >= 0; i--) {
char sixBits = (thirtysix >> (i * 6)) & 077;
sk_write(supdup->s, &sixBits, 1);
}
}
static void supdup_send_config(Supdup *supdup)
{
supdup_send_36bits(supdup, WORDS); // negative length
supdup_send_36bits(supdup, TCTYP); // terminal type
supdup_send_36bits(supdup, supdup->ttyopt); // options
supdup_send_36bits(supdup, supdup->tcmxv); // height
supdup_send_36bits(supdup, supdup->tcmxh); // width
supdup_send_36bits(supdup, TTYROL); // scroll amount
}
/*
* Called to set up the Supdup connection.
*
* Returns an error message, or NULL on success.
*
* Also places the canonical host name into `realhost'. It must be
* freed by the caller.
*/
static const char *supdup_init(const BackendVtable *x, Seat *seat,
Backend **backend_handle,
LogContext *logctx, Conf *conf,
const char *host, int port, char **realhost,
bool nodelay, bool keepalive)
{
static const PlugVtable fn_table = {
supdup_log,
supdup_closing,
supdup_receive,
supdup_sent
};
SockAddr *addr;
const char *err;
Supdup *supdup;
char *loghost;
int addressfamily;
const char *utf8 = "\033%G";
supdup = snew(struct supdup_tag);
supdup->plug.vt = &fn_table;
supdup->backend.vt = &supdup_backend;
supdup->logctx = logctx;
supdup->conf = conf_copy(conf);
supdup->s = NULL;
supdup->closed_on_socket_error = false;
supdup->seat = seat;
supdup->term_width = conf_get_int(supdup->conf, CONF_width);
supdup->term_height = conf_get_int(supdup->conf, CONF_height);
supdup->pinger = NULL;
supdup->sent_location = false;
*backend_handle = &supdup->backend;
switch (conf_get_int(supdup->conf, CONF_supdup_ascii_set)) {
case SUPDUP_CHARSET_ASCII:
supdup->print = print_ascii;
break;
case SUPDUP_CHARSET_ITS:
supdup->print = print_its;
break;
case SUPDUP_CHARSET_WAITS:
supdup->print = print_waits;
break;
}
/*
* Try to find host.
*/
{
char *buf;
addressfamily = conf_get_int(supdup->conf, CONF_addressfamily);
buf = dupprintf("Looking up host \"%s\"%s", host,
(addressfamily == ADDRTYPE_IPV4 ? " (IPv4)" :
(addressfamily == ADDRTYPE_IPV6 ? " (IPv6)" :
"")));
logevent(supdup->logctx, buf);
sfree(buf);
}
addr = name_lookup(host, port, realhost, supdup->conf, addressfamily, NULL, "");
if ((err = sk_addr_error(addr)) != NULL) {
sk_addr_free(addr);
return err;
}
if (port < 0)
port = 0137; /* default supdup port */
/*
* Open socket.
*/
supdup->s = new_connection(addr, *realhost, port, false, true,
nodelay, keepalive, &supdup->plug, supdup->conf);
if ((err = sk_socket_error(supdup->s)) != NULL)
return err;
supdup->pinger = pinger_new(supdup->conf, &supdup->backend);
/*
* We can send special commands from the start.
*/
seat_update_specials_menu(supdup->seat);
/*
* loghost overrides realhost, if specified.
*/
loghost = conf_get_str(supdup->conf, CONF_loghost);
if (*loghost) {
char *colon;
sfree(*realhost);
*realhost = dupstr(loghost);
colon = host_strrchr(*realhost, ':');
if (colon)
*colon++ = '\0';
}
/*
* Set up TTYOPTS based on config
*/
int ascii_set = conf_get_int(supdup->conf, CONF_supdup_ascii_set);
int more_processing = conf_get_bool(supdup->conf, CONF_supdup_more);
int scrolling = conf_get_bool(supdup->conf, CONF_supdup_scroll);
supdup->ttyopt =
TOERS |
TOMVB |
(ascii_set == SUPDUP_CHARSET_ASCII ? 0 : TOSAI | TOSA1) |
TOMVU |
TOLWR |
TOLID |
TOCID |
TPCBS |
(scrolling ? TOROL : 0) |
(more_processing ? TOMOR : 0) |
TPORS;
supdup->tcmxh = supdup->term_width - 1; // -1 "..one column is used to indicate line continuation."
supdup->tcmxv = supdup->term_height;
/*
* Send our configuration words to the server
*/
supdup_send_config(supdup);
/*
* We next expect a connection message followed by %TDNOP from the server
*/
supdup->state = CONNECTING;
seat_set_trust_status(supdup->seat, false);
/* Make sure the terminal is in UTF-8 mode. */
c_write(supdup, (unsigned char *)utf8, strlen(utf8));
return NULL;
}
static void supdup_free(Backend *be)
{
Supdup *supdup = container_of(be, Supdup, backend);
if (supdup->s)
sk_close(supdup->s);
if (supdup->pinger)
pinger_free(supdup->pinger);
conf_free(supdup->conf);
sfree(supdup);
}
/*
* Reconfigure the Supdup backend.
*/
static void supdup_reconfig(Backend *be, Conf *conf)
{
/* Nothing to do; SUPDUP cannot be reconfigured while running. */
}
/*
* Called to send data down the Supdup connection.
*/
static size_t supdup_send(Backend *be, const char *buf, size_t len)
{
Supdup *supdup = container_of(be, Supdup, backend);
char c;
int i;
if (supdup->s == NULL)
return 0;
for (i = 0; i < len; i++) {
if (buf[i] == 034)
supdup->bufsize = sk_write(supdup->s, "\034\034", 2);
else {
c = buf[i] & 0177;
supdup->bufsize = sk_write(supdup->s, &c, 1);
}
}
return supdup->bufsize;
}
/*
* Called to query the current socket sendability status.
*/
static size_t supdup_sendbuffer(Backend *be)
{
Supdup *supdup = container_of(be, Supdup, backend);
return supdup->bufsize;
}
/*
* Called to set the size of the window from Supdup's POV.
*/
static void supdup_size(Backend *be, int width, int height)
{
Supdup *supdup = container_of(be, Supdup, backend);
supdup->term_width = width;
supdup->term_height = height;
//
// SUPDUP does not support resizing the terminal after connection
// establishment.
//
}
/*
* Send Telnet special codes.
*/
static void supdup_special(Backend *be, SessionSpecialCode code, int arg)
{
}
static const SessionSpecial *supdup_get_specials(Backend *be)
{
return NULL;
}
static bool supdup_connected(Backend *be)
{
Supdup *supdup = container_of(be, Supdup, backend);
return supdup->s != NULL;
}
static bool supdup_sendok(Backend *be)
{
return 1;
}
static void supdup_unthrottle(Backend *be, size_t backlog)
{
Supdup *supdup = container_of(be, Supdup, backend);
sk_set_frozen(supdup->s, backlog > SUPDUP_MAX_BACKLOG);
}
static bool supdup_ldisc(Backend *be, int option)
{
/* No support for echoing or local editing. */
return false;
}
static void supdup_provide_ldisc(Backend *be, Ldisc *ldisc)
{
}
static int supdup_exitcode(Backend *be)
{
Supdup *supdup = container_of(be, Supdup, backend);
if (supdup->s != NULL)
return -1; /* still connected */
else if (supdup->closed_on_socket_error)
return INT_MAX; /* a socket error counts as an unclean exit */
else
/* Supdup doesn't transmit exit codes back to the client */
return 0;
}
/*
* cfg_info for Dupdup does nothing at all.
*/
static int supdup_cfg_info(Backend *be)
{
return 0;
}
const struct BackendVtable supdup_backend = {
supdup_init,
supdup_free,
supdup_reconfig,
supdup_send,
supdup_sendbuffer,
supdup_size,
supdup_special,
supdup_get_specials,
supdup_connected,
supdup_exitcode,
supdup_sendok,
supdup_ldisc,
supdup_provide_ldisc,
supdup_unthrottle,
supdup_cfg_info,
NULL /* test_for_upstream */,
"supdup",
"SUPDUP",
PROT_SUPDUP,
0137,
BACKEND_RESIZE_FORBIDDEN | BACKEND_NEEDS_TERMINAL
};
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