int
getconnmode(void)
{
int mode = 0;
if (my_want_state_is_dont(TELOPT_ECHO))
mode |= MODE_ECHO;
if (localflow)
mode |= MODE_FLOW;
if ((eight & 1) || my_want_state_is_will(TELOPT_BINARY))
mode |= MODE_INBIN;
if (eight & 2)
mode |= MODE_OUT8;
if (his_want_state_is_will(TELOPT_BINARY))
mode |= MODE_OUTBIN;
#ifdef KLUDGELINEMODE
if (kludgelinemode) {
if (my_want_state_is_dont(TELOPT_SGA)) {
mode |= (MODE_TRAPSIG|MODE_EDIT);
if (dontlecho && (clocks.echotoggle > clocks.modenegotiated)) {
mode &= ~MODE_ECHO;
}
}
return(mode);
}
#endif
if (my_want_state_is_will(TELOPT_LINEMODE))
mode |= linemode;
return(mode);
}
/*
* 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));
}
/*
* 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
* NO_KLUDGE : don't initiate kludge linemode.
* 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,
* and the "-k" (don't initiate kludge linemode) isn't set,
* 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)
{
int need_will_echo = 0;
/*
* Check for changes to flow control if client supports it.
*/
flowstat();
/*
* 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);
}
if (uselinemode) {
/*
* Check for state of BINARY options.
*
* We only need to do the binary dance if we are actually going
* to use linemode. As this confuses some telnet clients
* that don't support linemode, and doesn't gain us
* anything, we don't do it unless we're doing linemode.
* -Crh ([email protected])
*/
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);
}
}
#ifdef ENCRYPTION
/*
* If the terminal is not echoing, but editing is enabled,
* something like password input is going to happen, so
* if we the other side is not currently sending encrypted
* data, ask the other side to start encrypting.
*/
if (his_state_is_will(TELOPT_ENCRYPT)) {
static int enc_passwd = 0;
if (uselinemode && !tty_isecho() && tty_isediting()
&& (enc_passwd == 0) && !decrypt_input) {
encrypt_send_request_start();
enc_passwd = 1;
} else if (enc_passwd) {
encrypt_send_request_end();
enc_passwd = 0;
}
}
#endif /* ENCRYPTION */
/*
* 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;
#ifdef KLUDGELINEMODE
if (lmodetype == KLUDGE_OK)
lmodetype = KLUDGE_LINEMODE;
#endif
}
/*
* 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 */
output_data("%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.
*/
output_data("%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 */
void wontoption(int option) {
/*
* Process client input.
*/
DIAG(TD_OPTIONS, printoption("td: recv wont", option));
if (do_dont_resp[option]) {
do_dont_resp[option]--;
if (do_dont_resp[option] && his_state_is_wont(option))
do_dont_resp[option]--;
}
if (do_dont_resp[option] == 0) {
if (his_want_state_is_will(option)) {
/* it is always ok to change to negative state */
switch (option) {
case TELOPT_ECHO:
not42 = 1; /* doesn't seem to be a 4.2 system */
break;
case TELOPT_BINARY:
init_termbuf();
tty_binaryin(0);
set_termbuf();
break;
#ifdef LINEMODE
case TELOPT_LINEMODE:
#ifdef KLUDGELINEMODE
/*
* If real linemode is supported, then client is
* asking to turn linemode off.
*/
if (lmodetype != REAL_LINEMODE)
break;
lmodetype = KLUDGE_LINEMODE;
# endif /* KLUDGELINEMODE */
clientstat(TELOPT_LINEMODE, WONT, 0);
break;
#endif /* LINEMODE */
case TELOPT_TM:
/*
* If we get a WONT TM, and had sent a DO TM,
* don't respond with a DONT TM, just leave it
* as is. Short circut the state machine to
* achive this.
*/
set_his_want_state_wont(TELOPT_TM);
return;
case TELOPT_LFLOW:
/*
* If we are not going to support flow control
* option, then let peer know that we can't
* change the flow control characters.
*/
slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
slctab[SLC_XON].defset.flag |= SLC_CANTCHANGE;
slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
slctab[SLC_XOFF].defset.flag |= SLC_CANTCHANGE;
break;
#if defined(AUTHENTICATE)
case TELOPT_AUTHENTICATION:
auth_finished(0, AUTH_REJECT);
break;
#endif
/*
* For options that we might spin waiting for
* sub-negotiation, if the client turns off the
* option rather than responding to the request,
* we have to treat it here as if we got a response
* to the sub-negotiation, (by updating the timers)
* so that we'll break out of the loop.
*/
case TELOPT_TTYPE:
settimer(ttypesubopt);
break;
case TELOPT_TSPEED:
settimer(tspeedsubopt);
break;
case TELOPT_XDISPLOC:
settimer(xdisplocsubopt);
break;
case TELOPT_ENVIRON:
settimer(environsubopt);
break;
default:
break;
}
set_his_want_state_wont(option);
if (his_state_is_will(option)) send_dont(option, 0);
}
else {
switch (option) {
case TELOPT_TM:
#if defined(LINEMODE) && defined(KLUDGELINEMODE)
if (lmodetype < REAL_LINEMODE) {
lmodetype = NO_LINEMODE;
clientstat(TELOPT_LINEMODE, WONT, 0);
send_will(TELOPT_SGA, 1);
send_will(TELOPT_ECHO, 1);
}
#endif /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
break;
#if defined(AUTHENTICATE)
case TELOPT_AUTHENTICATION:
auth_finished(0, AUTH_REJECT);
break;
#endif
default:
break;
}
}
}
} /* end of wontoption */
/*
* 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
* NO_KLUDGE : don't initiate kludge linemode.
* 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,
* and the "-k" (don't initiate kludge linemode) isn't set,
* 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()
{
int need_will_echo = 0;
#if defined(CRAY2) && defined(UNICOS5)
/*
* Keep track of that ol' CR/NL mapping while we're in the
* neighborhood.
*/
newmap = tty_isnewmap();
#endif /* defined(CRAY2) && defined(UNICOS5) */
/*
* 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.
*/
flowstat();
/*
* 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;
#ifdef KLUDGELINEMODE
if (lmodetype == KLUDGE_OK)
lmodetype = KLUDGE_LINEMODE;
#endif
}
/*
* 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) sprintf(nfrontp, "%c%c%c%c%c%c%c", IAC, SB,
TELOPT_LINEMODE, LM_MODE, useeditmode,
IAC, SE);
nfrontp += 7;
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) sprintf(nfrontp, "%c%c%c%c%c%c%c", IAC, SB,
TELOPT_LINEMODE, LM_MODE, useeditmode,
IAC, SE);
nfrontp += 7;
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);
}
