void send_wont(int option, int init) {
if (init) {
if ((will_wont_resp[option] == 0 && my_state_is_wont(option)) ||
my_want_state_is_wont(option))
return;
set_my_want_state_wont(option);
will_wont_resp[option]++;
}
netoprintf((char *)wont, option);
DIAG(TD_OPTIONS, printoption("td: send wont", option));
}
void send_dont(int option, int init) {
if (init) {
if ((do_dont_resp[option] == 0 && his_state_is_wont(option)) ||
his_want_state_is_wont(option))
return;
set_his_want_state_wont(option);
do_dont_resp[option]++;
}
netoprintf((char *) dont, option);
DIAG(TD_OPTIONS, printoption("td: send dont", option));
}
static void
_gettermname(void)
{
/*
* If the client turned off the option,
* we can't send another request, so we
* just return.
*/
if (his_state_is_wont(TELOPT_TTYPE))
return;
settimer(baseline);
netoprintf("%c%c%c%c%c%c", IAC, SB, TELOPT_TTYPE, TELQUAL_SEND, IAC, SE);
while (sequenceIs(ttypesubopt, baseline))
ttloop();
}
/*
* The will/wont/do/dont state machines are based on Dave Borman's
* Telnet option processing state machine.
*
* These correspond to the following states:
* my_state = the last negotiated state
* want_state = what I want the state to go to
* want_resp = how many requests I have sent
* All state defaults are negative, and resp defaults to 0.
*
* When initiating a request to change state to new_state:
*
* if ((want_resp == 0 && new_state == my_state) || want_state == new_state) {
* do nothing;
* } else {
* want_state = new_state;
* send new_state;
* want_resp++;
* }
*
* When receiving new_state:
*
* if (want_resp) {
* want_resp--;
* if (want_resp && (new_state == my_state))
* want_resp--;
* }
* if ((want_resp == 0) && (new_state != want_state)) {
* if (ok_to_switch_to new_state)
* want_state = new_state;
* else
* want_resp++;
* send want_state;
* }
* my_state = new_state;
*
* Note that new_state is implied in these functions by the function itself.
* will and do imply positive new_state, wont and dont imply negative.
*
* Finally, there is one catch. If we send a negative response to a
* positive request, my_state will be the positive while want_state will
* remain negative. my_state will revert to negative when the negative
* acknowlegment arrives from the peer. Thus, my_state generally tells
* us not only the last negotiated state, but also tells us what the peer
* wants to be doing as well. It is important to understand this difference
* as we may wish to be processing data streams based on our desired state
* (want_state) or based on what the peer thinks the state is (my_state).
*
* This all works fine because if the peer sends a positive request, the data
* that we receive prior to negative acknowlegment will probably be affected
* by the positive state, and we can process it as such (if we can; if we
* can't then it really doesn't matter). If it is that important, then the
* peer probably should be buffering until this option state negotiation
* is complete.
*
*/
void send_do(int option, int init) {
if (init) {
if ((do_dont_resp[option] == 0 && his_state_is_will(option)) ||
his_want_state_is_will(option))
return;
/*
* Special case for TELOPT_TM: We send a DO, but pretend
* that we sent a DONT, so that we can send more DOs if
* we want to.
*/
if (option == TELOPT_TM)
set_his_want_state_wont(option);
else
set_his_want_state_will(option);
do_dont_resp[option]++;
}
netoprintf((char *)doopt, option);
DIAG(TD_OPTIONS, printoption("td: send do", option));
}
/*
* clientstat
*
* Process linemode related requests from the client.
* Client can request a change to only one of linemode, editmode or slc's
* at a time, and if using kludge linemode, then only linemode may be
* affected.
*/
void clientstat(register int code, register int parm1, register int parm2)
{
/*
* Get a copy of terminal characteristics.
*/
init_termbuf();
/*
* Process request from client. code tells what it is.
*/
switch (code) {
#ifdef LINEMODE
case TELOPT_LINEMODE:
/*
* Don't do anything unless client is asking us to change
* modes.
*/
uselinemode = (parm1 == WILL);
if (uselinemode != linemode) {
#ifdef KLUDGELINEMODE
/*
* If using kludge linemode, make sure that
* we can do what the client asks.
* We can not turn off linemode if alwayslinemode
* and the ICANON bit is set.
*/
if (lmodetype == KLUDGE_LINEMODE) {
if (alwayslinemode && tty_isediting()) {
uselinemode = 1;
}
}
/*
* Quit now if we can't do it.
*/
if (uselinemode == linemode)
return;
/*
* If using real linemode and linemode is being
* turned on, send along the edit mode mask.
*/
if (lmodetype == REAL_LINEMODE && uselinemode)
#else /* KLUDGELINEMODE */
if (uselinemode)
#endif /* KLUDGELINEMODE */
{
useeditmode = 0;
if (tty_isediting())
useeditmode |= MODE_EDIT;
if (tty_istrapsig)
useeditmode |= MODE_TRAPSIG;
if (tty_issofttab())
useeditmode |= MODE_SOFT_TAB;
if (tty_islitecho())
useeditmode |= MODE_LIT_ECHO;
(void)netoprintf("%c%c%c%c%c%c%c", IAC,
SB, TELOPT_LINEMODE, LM_MODE,
useeditmode, IAC, SE);
editmode = useeditmode;
}
tty_setlinemode(uselinemode);
linemode = uselinemode;
}
break;
case LM_MODE: {
register int ack, changed;
/*
* Client has sent along a mode mask. If it agrees with
* what we are currently doing, ignore it; if not, it could
* be viewed as a request to change. Note that the server
* will change to the modes in an ack if it is different from
* what we currently have, but we will not ack the ack.
*/
useeditmode &= MODE_MASK;
ack = (useeditmode & MODE_ACK);
useeditmode &= ~MODE_ACK;
if (changed = (useeditmode ^ editmode)) {
/*
* This check is for a timing problem. If the
* state of the tty has changed (due to the user
* application) we need to process that info
* before we write in the state contained in the
* ack!!! This gets out the new MODE request,
* and when the ack to that command comes back
* we'll set it and be in the right mode.
*/
if (ack)
localstat();
if (changed & MODE_EDIT)
tty_setedit(useeditmode & MODE_EDIT);
if (changed & MODE_TRAPSIG)
tty_setsig(useeditmode & MODE_TRAPSIG);
if (changed & MODE_SOFT_TAB)
tty_setsofttab(useeditmode & MODE_SOFT_TAB);
if (changed & MODE_LIT_ECHO)
tty_setlitecho(useeditmode & MODE_LIT_ECHO);
set_termbuf();
if (!ack) {
(void)netoprintf("%c%c%c%c%c%c%c", IAC,
SB, TELOPT_LINEMODE, LM_MODE,
useeditmode | MODE_ACK,
IAC, SE);
}
editmode = useeditmode;
}
break;
} /* end of case LM_MODE */
#endif /* LINEMODE */
case TELOPT_NAWS:
#ifdef TIOCSWINSZ
{
struct winsize ws = {0};
def_col = parm1;
def_row = parm2;
#ifdef LINEMODE
/*
* Defer changing window size until after terminal is
* initialized.
*/
if (terminit() == 0)
return;
#endif /* LINEMODE */
/*
* Change window size as requested by client.
*/
ws.ws_col = parm1;
ws.ws_row = parm2;
(void)ioctl(pty, TIOCSWINSZ, (char*)&ws);
}
#endif /* TIOCSWINSZ */
break;
case TELOPT_TSPEED: {
def_tspeed = parm1;
def_rspeed = parm2;
#ifdef LINEMODE
/*
* Defer changing the terminal speed.
*/
if (terminit() == 0)
return;
#endif /* LINEMODE */
/*
* Change terminal speed as requested by client.
* We set the receive speed first, so that if we can't
* store seperate receive and transmit speeds, the transmit
* speed will take precedence.
*/
tty_rspeed(parm2);
tty_tspeed(parm1);
set_termbuf();
break;
} /* end of case TELOPT_TSPEED */
default:
/* What? */
break;
} /* end of switch */
netflush();
} /* end of clientstat */
/*
* localstat
*
* This function handles all management of linemode.
*
* Linemode allows the client to do the local editing of data
* and send only complete lines to the server. Linemode state is
* based on the state of the pty driver. If the pty is set for
* external processing, then we can use linemode. Further, if we
* can use real linemode, then we can look at the edit control bits
* in the pty to determine what editing the client should do.
*
* Linemode support uses the following state flags to keep track of
* current and desired linemode state.
* alwayslinemode : true if -l was specified on the telnetd
* command line. It means to have linemode on as much as
* possible.
*
* lmodetype: signifies whether the client can
* handle real linemode, or if use of kludgeomatic linemode
* is preferred. It will be set to one of the following:
* REAL_LINEMODE : use linemode option
* KLUDGE_LINEMODE : use kludge linemode
* NO_LINEMODE : client is ignorant of linemode
*
* linemode, uselinemode : linemode is true if linemode
* is currently on, uselinemode is the state that we wish
* to be in. If another function wishes to turn linemode
* on or off, it sets or clears uselinemode.
*
* editmode, useeditmode : like linemode/uselinemode, but
* these contain the edit mode states (edit and trapsig).
*
* The state variables correspond to some of the state information
* in the pty.
* linemode:
* In real linemode, this corresponds to whether the pty
* expects external processing of incoming data.
* In kludge linemode, this more closely corresponds to the
* whether normal processing is on or not. (ICANON in
* system V, or COOKED mode in BSD.)
* If the -l option was specified (alwayslinemode), then
* an attempt is made to force external processing on at
* all times.
*
* The following heuristics are applied to determine linemode
* handling within the server.
* 1) Early on in starting up the server, an attempt is made
* to negotiate the linemode option. If this succeeds
* then lmodetype is set to REAL_LINEMODE and all linemode
* processing occurs in the context of the linemode option.
* 2) If the attempt to negotiate the linemode option failed,
* then we try to use kludge linemode. We test for this
* capability by sending "do Timing Mark". If a positive
* response comes back, then we assume that the client
* understands kludge linemode (ech!) and the
* lmodetype flag is set to KLUDGE_LINEMODE.
* 3) Otherwise, linemode is not supported at all and
* lmodetype remains set to NO_LINEMODE (which happens
* to be 0 for convenience).
* 4) At any time a command arrives that implies a higher
* state of linemode support in the client, we move to that
* linemode support.
*
* A short explanation of kludge linemode is in order here.
* 1) The heuristic to determine support for kludge linemode
* is to send a do timing mark. We assume that a client
* that supports timing marks also supports kludge linemode.
* A risky proposition at best.
* 2) Further negotiation of linemode is done by changing the
* the server's state regarding SGA. If server will SGA,
* then linemode is off, if server won't SGA, then linemode
* is on.
*/
void localstat()
{
void netflush();
int need_will_echo = 0;
/*
* Check for state of BINARY options.
*/
if (tty_isbinaryin()) {
if (his_want_state_is_wont(TELOPT_BINARY))
send_do(TELOPT_BINARY, 1);
}
else {
if (his_want_state_is_will(TELOPT_BINARY))
send_dont(TELOPT_BINARY, 1);
}
if (tty_isbinaryout()) {
if (my_want_state_is_wont(TELOPT_BINARY))
send_will(TELOPT_BINARY, 1);
}
else {
if (my_want_state_is_will(TELOPT_BINARY))
send_wont(TELOPT_BINARY, 1);
}
/*
* Check for changes to flow control if client supports it.
*/
if (his_state_is_will(TELOPT_LFLOW)) {
if (tty_flowmode() != flowmode) {
flowmode = tty_flowmode();
(void)netoprintf("%c%c%c%c%c%c", IAC, SB,
TELOPT_LFLOW, flowmode, IAC, SE);
}
}
/*
* Check linemode on/off state
*/
uselinemode = tty_linemode();
/*
* If alwayslinemode is on, and pty is changing to turn it off, then
* force linemode back on.
*/
if (alwayslinemode && linemode && !uselinemode) {
uselinemode = 1;
tty_setlinemode(uselinemode);
}
/*
* Do echo mode handling as soon as we know what the
* linemode is going to be.
* If the pty has echo turned off, then tell the client that
* the server will echo. If echo is on, then the server
* will echo if in character mode, but in linemode the
* client should do local echoing. The state machine will
* not send anything if it is unnecessary, so don't worry
* about that here.
*
* If we need to send the WILL ECHO (because echo is off),
* then delay that until after we have changed the MODE.
* This way, when the user is turning off both editing
* and echo, the client will get editing turned off first.
* This keeps the client from going into encryption mode
* and then right back out if it is doing auto-encryption
* when passwords are being typed.
*/
if (uselinemode) {
if (tty_isecho())
send_wont(TELOPT_ECHO, 1);
else
need_will_echo = 1;
}
/*
* If linemode is being turned off, send appropriate
* command and then we're all done.
*/
if (!uselinemode && linemode) {
#ifdef KLUDGELINEMODE
if (lmodetype == REAL_LINEMODE) {
#endif /* KLUDGELINEMODE */
send_dont(TELOPT_LINEMODE, 1);
#ifdef KLUDGELINEMODE
}
else if (lmodetype == KLUDGE_LINEMODE)
send_will(TELOPT_SGA, 1);
#endif /* KLUDGELINEMODE */
send_will(TELOPT_ECHO, 1);
linemode = uselinemode;
goto done;
}
#ifdef KLUDGELINEMODE
/*
* If using real linemode check edit modes for possible later use.
* If we are in kludge linemode, do the SGA negotiation.
*/
if (lmodetype == REAL_LINEMODE) {
#endif /* KLUDGELINEMODE */
useeditmode = 0;
if (tty_isediting())
useeditmode |= MODE_EDIT;
if (tty_istrapsig())
useeditmode |= MODE_TRAPSIG;
if (tty_issofttab())
useeditmode |= MODE_SOFT_TAB;
if (tty_islitecho())
useeditmode |= MODE_LIT_ECHO;
#ifdef KLUDGELINEMODE
}
else if (lmodetype == KLUDGE_LINEMODE) {
if (tty_isediting() && uselinemode)
send_wont(TELOPT_SGA, 1);
else
send_will(TELOPT_SGA, 1);
}
#endif /* KLUDGELINEMODE */
/*
* Negotiate linemode on if pty state has changed to turn it on.
* Send appropriate command and send along edit mode, then all done.
*/
if (uselinemode && !linemode) {
#ifdef KLUDGELINEMODE
if (lmodetype == KLUDGE_LINEMODE) {
send_wont(TELOPT_SGA, 1);
}
else if (lmodetype == REAL_LINEMODE) {
#endif /* KLUDGELINEMODE */
send_do(TELOPT_LINEMODE, 1);
/* send along edit modes */
(void)netoprintf("%c%c%c%c%c%c%c", IAC, SB,
TELOPT_LINEMODE, LM_MODE, useeditmode,
IAC, SE);
editmode = useeditmode;
#ifdef KLUDGELINEMODE
}
#endif /* KLUDGELINEMODE */
linemode = uselinemode;
goto done;
}
#ifdef KLUDGELINEMODE
/*
* None of what follows is of any value if not using
* real linemode.
*/
if (lmodetype < REAL_LINEMODE)
goto done;
#endif /* KLUDGELINEMODE */
if (linemode && his_state_is_will(TELOPT_LINEMODE)) {
/*
* If edit mode changed, send edit mode.
*/
if (useeditmode != editmode) {
/*
* Send along appropriate edit mode mask.
*/
(void)netoprintf("%c%c%c%c%c%c%c", IAC, SB,
TELOPT_LINEMODE, LM_MODE, useeditmode,
IAC, SE);
editmode = useeditmode;
}
/*
* Check for changes to special characters in use.
*/
start_slc(0);
check_slc();
(void)end_slc(0);
}
done:
if (need_will_echo)
send_will(TELOPT_ECHO, 1);
/*
* Some things should be deferred until after the pty state has
* been set by the local process. Do those things that have been
* deferred now. This only happens once.
*/
if (_terminit == 0) {
_terminit = 1;
defer_terminit();
}
netflush();
set_termbuf();
return;
} /* end of localstat */
/*
* Main loop. Select from pty and network, and
* hand data to telnet receiver finite state machine.
*/
void telnet(int f, int p)
{
int on = 1;
char *HE;
const char *IM;
/*
* Initialize the slc mapping table.
*/
get_slc_defaults();
/*
* Do some tests where it is desireable to wait for a response.
* Rather than doing them slowly, one at a time, do them all
* at once.
*/
if (my_state_is_wont(TELOPT_SGA))
send_will(TELOPT_SGA, 1);
/*
* Is the client side a 4.2 (NOT 4.3) system? We need to know this
* because 4.2 clients are unable to deal with TCP urgent data.
*
* To find out, we send out a "DO ECHO". If the remote system
* answers "WILL ECHO" it is probably a 4.2 client, and we note
* that fact ("WILL ECHO" ==> that the client will echo what
* WE, the server, sends it; it does NOT mean that the client will
* echo the terminal input).
*/
send_do(TELOPT_ECHO, 1);
#ifdef LINEMODE
if (his_state_is_wont(TELOPT_LINEMODE)) {
/*
* Query the peer for linemode support by trying to negotiate
* the linemode option.
*/
linemode = 0;
editmode = 0;
send_do(TELOPT_LINEMODE, 1); /* send do linemode */
}
#endif /* LINEMODE */
/*
* Send along a couple of other options that we wish to negotiate.
*/
send_do(TELOPT_NAWS, 1);
send_will(TELOPT_STATUS, 1);
flowmode = 1; /* default flow control state */
send_do(TELOPT_LFLOW, 1);
/*
* Spin, waiting for a response from the DO ECHO. However,
* some REALLY DUMB telnets out there might not respond
* to the DO ECHO. So, we spin looking for NAWS, (most dumb
* telnets so far seem to respond with WONT for a DO that
* they don't understand...) because by the time we get the
* response, it will already have processed the DO ECHO.
* Kludge upon kludge.
*/
while (his_will_wont_is_changing(TELOPT_NAWS)) {
ttloop();
}
/*
* But...
* The client might have sent a WILL NAWS as part of its
* startup code; if so, we'll be here before we get the
* response to the DO ECHO. We'll make the assumption
* that any implementation that understands about NAWS
* is a modern enough implementation that it will respond
* to our DO ECHO request; hence we'll do another spin
* waiting for the ECHO option to settle down, which is
* what we wanted to do in the first place...
*/
if (his_want_state_is_will(TELOPT_ECHO) &&
his_state_is_will(TELOPT_NAWS)) {
while (his_will_wont_is_changing(TELOPT_ECHO))
ttloop();
}
/*
* On the off chance that the telnet client is broken and does not
* respond to the DO ECHO we sent, (after all, we did send the
* DO NAWS negotiation after the DO ECHO, and we won't get here
* until a response to the DO NAWS comes back) simulate the
* receipt of a will echo. This will also send a WONT ECHO
* to the client, since we assume that the client failed to
* respond because it believes that it is already in DO ECHO
* mode, which we do not want.
*/
if (his_want_state_is_will(TELOPT_ECHO)) {
DIAG(TD_OPTIONS, netoprintf("td: simulating recv\r\n"););
willoption(TELOPT_ECHO);
}
static
int
getterminaltype(char *name)
{
int retval = -1;
(void)name;
settimer(baseline);
#if defined(AUTHENTICATE)
/*
* Handle the Authentication option before we do anything else.
*/
send_do(TELOPT_AUTHENTICATION, 1);
while (his_will_wont_is_changing(TELOPT_AUTHENTICATION))
ttloop();
if (his_state_is_will(TELOPT_AUTHENTICATION)) {
retval = auth_wait(name);
}
#endif
#if defined(ENCRYPT)
send_will(TELOPT_ENCRYPT, 1);
#endif
send_do(TELOPT_TTYPE, 1);
send_do(TELOPT_TSPEED, 1);
send_do(TELOPT_XDISPLOC, 1);
send_do(TELOPT_ENVIRON, 1);
while (
#if defined(ENCRYPT)
his_do_dont_is_changing(TELOPT_ENCRYPT) ||
#endif
his_will_wont_is_changing(TELOPT_TTYPE) ||
his_will_wont_is_changing(TELOPT_TSPEED) ||
his_will_wont_is_changing(TELOPT_XDISPLOC) ||
his_will_wont_is_changing(TELOPT_ENVIRON)) {
ttloop();
}
#if defined(ENCRYPT)
/*
* Wait for the negotiation of what type of encryption we can
* send with. If autoencrypt is not set, this will just return.
*/
if (his_state_is_will(TELOPT_ENCRYPT)) {
encrypt_wait();
}
#endif
if (his_state_is_will(TELOPT_TSPEED)) {
netoprintf("%c%c%c%c%c%c",
IAC, SB, TELOPT_TSPEED, TELQUAL_SEND, IAC, SE);
}
if (his_state_is_will(TELOPT_XDISPLOC)) {
netoprintf("%c%c%c%c%c%c",
IAC, SB, TELOPT_XDISPLOC, TELQUAL_SEND, IAC, SE);
}
if (his_state_is_will(TELOPT_ENVIRON)) {
netoprintf("%c%c%c%c%c%c",
IAC, SB, TELOPT_ENVIRON, TELQUAL_SEND, IAC, SE);
}
if (his_state_is_will(TELOPT_TTYPE)) {
netoprintf("%c%c%c%c%c%c",
IAC, SB, TELOPT_TTYPE, TELQUAL_SEND, IAC, SE);
}
if (his_state_is_will(TELOPT_TSPEED)) {
while (sequenceIs(tspeedsubopt, baseline))
ttloop();
}
if (his_state_is_will(TELOPT_XDISPLOC)) {
while (sequenceIs(xdisplocsubopt, baseline))
ttloop();
}
if (his_state_is_will(TELOPT_ENVIRON)) {
while (sequenceIs(environsubopt, baseline))
ttloop();
}
if (his_state_is_will(TELOPT_TTYPE)) {
char first[256], last[256];
while (sequenceIs(ttypesubopt, baseline))
ttloop();
/*
* If the other side has already disabled the option, then
* we have to just go with what we (might) have already gotten.
*/
if (his_state_is_will(TELOPT_TTYPE) && !terminaltypeok(terminaltype)) {
/*
* Due to state.c, terminaltype points to a static char[41].
* Therefore, this assert cannot fail, and therefore, strings
* arising from "terminaltype" can be safely strcpy'd into
* first[] or last[].
*/
assert(strlen(terminaltype) < sizeof(first));
strcpy(first, terminaltype);
for(;;) {
/*
* Save the unknown name, and request the next name.
*/
strcpy(last, terminaltype);
_gettermname();
assert(strlen(terminaltype) < sizeof(first));
if (terminaltypeok(terminaltype))
break;
if (!strcmp(last, terminaltype) ||
his_state_is_wont(TELOPT_TTYPE)) {
/*
* We've hit the end. If this is the same as
* the first name, just go with it.
*/
if (!strcmp(first, terminaltype))
break;
/*
* Get the terminal name one more time, so that
* RFC1091 compliant telnets will cycle back to
* the start of the list.
*/
_gettermname();
assert(strlen(terminaltype) < sizeof(first));
if (strcmp(first, terminaltype)) {
/*
* first[] came from terminaltype, so it must fit
* back in.
*/
strcpy(terminaltype, first);
}
break;
}
}
}
}
return(retval);
} /* end of getterminaltype */
