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NetBSD/libexec/telnetd/state.c

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/* $NetBSD: state.c,v 1.34 2024/02/10 09:21:52 andvar Exp $ */
/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)state.c 8.5 (Berkeley) 5/30/95";
#else
__RCSID("$NetBSD: state.c,v 1.34 2024/02/10 09:21:52 andvar Exp $");
#endif
#endif /* not lint */
#include <ctype.h>
#include <stdarg.h>
#include "telnetd.h"
static int envvarok(char *);
int not42 = 1;
/*
* Buffer for sub-options, and macros
* for suboptions buffer manipulations
*/
unsigned char subbuffer[4096], *subpointer= subbuffer, *subend= subbuffer;
#define SB_CLEAR() subpointer = subbuffer
#define SB_TERM() { subend = subpointer; SB_CLEAR(); }
#define SB_ACCUM(c) if (subpointer < (subbuffer+sizeof subbuffer)) { \
*subpointer++ = (c); \
}
#define SB_GET() ((*subpointer++)&0xff)
#define SB_EOF() (subpointer >= subend)
#define SB_LEN() (subend - subpointer)
#ifdef ENV_HACK
unsigned char *subsave;
#define SB_SAVE() subsave = subpointer;
#define SB_RESTORE() subpointer = subsave;
#endif
/*
* State for recv fsm
*/
#define TS_DATA 0 /* base state */
#define TS_IAC 1 /* look for double IAC's */
#define TS_CR 2 /* CR-LF ->'s CR */
#define TS_SB 3 /* throw away begin's... */
#define TS_SE 4 /* ...end's (suboption negotiation) */
#define TS_WILL 5 /* will option negotiation */
#define TS_WONT 6 /* wont " */
#define TS_DO 7 /* do " */
#define TS_DONT 8 /* dont " */
void
telrcv(void)
{
int c;
static int state = TS_DATA;
while (ncc > 0) {
if ((&ptyobuf[BUFSIZ] - pfrontp) < 2)
break;
c = *netip++ & 0377, ncc--;
#ifdef ENCRYPTION
if (decrypt_input)
c = (*decrypt_input)(c);
#endif /* ENCRYPTION */
switch (state) {
case TS_CR:
state = TS_DATA;
#ifdef LINEMODE
/*
* If we are operating in linemode,
* convert to local end-of-line.
*/
if (linemode && (ncc > 0) && ((c == '\n') ||
((c == 0) && tty_iscrnl())) )
c = '\n';
else
#endif
{
/*
* We now map \r\n ==> \r for pragmatic reasons.
* Many client implementations send \r\n when
* the user hits the CarriageReturn key.
*
* We USED to map \r\n ==> \n, since \r\n says
* that we want to be in column 1 of the next
* printable line, and \n is the standard
* unix way of saying that (\r is only good
* if CRMOD is set, which it normally is).
*/
/* Strip off \n or \0 after a \r */
if ((c == 0) || (c == '\n'))
break;
}
/* FALL THROUGH */
case TS_DATA:
if (c == IAC) {
state = TS_IAC;
break;
}
if ((c == '\r') && his_state_is_wont(TELOPT_BINARY))
state = TS_CR;
*pfrontp++ = c;
break;
case TS_IAC:
gotiac: switch (c) {
/*
* Send the process on the pty side an
* interrupt. Do this with a NULL or
* interrupt char; depending on the tty mode.
*/
case IP:
DIAG(TD_OPTIONS,
printoption("td: recv IAC", c));
interrupt();
break;
case BREAK:
DIAG(TD_OPTIONS,
printoption("td: recv IAC", c));
sendbrk();
break;
/*
* Are You There?
*/
case AYT:
DIAG(TD_OPTIONS,
printoption("td: recv IAC", c));
recv_ayt();
break;
/*
* Abort Output
*/
case AO:
{
DIAG(TD_OPTIONS,
printoption("td: recv IAC", c));
ptyflush(); /* half-hearted */
init_termbuf();
if (slctab[SLC_AO].sptr &&
*slctab[SLC_AO].sptr != (cc_t)(_POSIX_VDISABLE)) {
*pfrontp++ =
(unsigned char)*slctab[SLC_AO].sptr;
}
netclear(); /* clear buffer back */
output_data("%c%c", IAC, DM);
neturg = nfrontp - 1; /* off by one XXX */
DIAG(TD_OPTIONS,
printoption("td: send IAC", DM));
break;
}
/*
* Erase Character and
* Erase Line
*/
case EC:
case EL:
{
cc_t ch;
DIAG(TD_OPTIONS,
printoption("td: recv IAC", c));
ptyflush(); /* half-hearted */
init_termbuf();
if (c == EC)
ch = *slctab[SLC_EC].sptr;
else
ch = *slctab[SLC_EL].sptr;
if (ch != (cc_t)(_POSIX_VDISABLE))
*pfrontp++ = (unsigned char)ch;
break;
}
/*
* Check for urgent data...
*/
case DM:
DIAG(TD_OPTIONS,
printoption("td: recv IAC", c));
SYNCHing = stilloob(net);
settimer(gotDM);
break;
/*
* Begin option subnegotiation...
*/
case SB:
state = TS_SB;
SB_CLEAR();
continue;
case WILL:
state = TS_WILL;
continue;
case WONT:
state = TS_WONT;
continue;
case DO:
state = TS_DO;
continue;
case DONT:
state = TS_DONT;
continue;
case EOR:
if (his_state_is_will(TELOPT_EOR))
doeof();
break;
/*
* Handle RFC 10xx Telnet linemode option additions
* to command stream (EOF, SUSP, ABORT).
*/
case xEOF:
doeof();
break;
case SUSP:
sendsusp();
break;
case ABORT:
sendbrk();
break;
case IAC:
*pfrontp++ = c;
break;
}
state = TS_DATA;
break;
case TS_SB:
if (c == IAC) {
state = TS_SE;
} else {
SB_ACCUM(c);
}
break;
case TS_SE:
if (c != SE) {
if (c != IAC) {
/*
* bad form of suboption negotiation.
* handle it in such a way as to avoid
* damage to local state. Parse
* suboption buffer found so far,
* then treat remaining stream as
* another command sequence.
*/
/* for DIAGNOSTICS */
SB_ACCUM(IAC);
SB_ACCUM(c);
subpointer -= 2;
SB_TERM();
suboption();
state = TS_IAC;
goto gotiac;
}
SB_ACCUM(c);
state = TS_SB;
} else {
/* for DIAGNOSTICS */
SB_ACCUM(IAC);
SB_ACCUM(SE);
subpointer -= 2;
SB_TERM();
suboption(); /* handle sub-option */
state = TS_DATA;
}
break;
case TS_WILL:
willoption(c);
state = TS_DATA;
continue;
case TS_WONT:
wontoption(c);
state = TS_DATA;
continue;
case TS_DO:
dooption(c);
state = TS_DATA;
continue;
case TS_DONT:
dontoption(c);
state = TS_DATA;
continue;
default:
syslog(LOG_ERR, "panic state=%d", state);
printf("telnetd: panic state=%d\n", state);
exit(1);
}
}
} /* end of telrcv */
/*
* 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
* acknowledgment 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 acknowledgment 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]++;
}
(void) output_data("%c%c%c", IAC, DO, option);
DIAG(TD_OPTIONS, printoption("td: send do", option));
}
#ifdef LINEMODE
extern void doclientstat(void);
#endif
#if 0
#ifdef AUTHENTICATION
extern void auth_request(void); /* libtelnet */
#endif
#ifdef ENCRYPTION
extern void encrypt_send_support(void);
#endif /* ENCRYPTION */
#endif
void
willoption(int option)
{
int changeok = 0;
void (*func)(void) = 0;
/*
* process input from peer.
*/
DIAG(TD_OPTIONS, printoption("td: recv will", option));
if (do_dont_resp[option]) {
do_dont_resp[option]--;
if (do_dont_resp[option] && his_state_is_will(option))
do_dont_resp[option]--;
}
if (do_dont_resp[option] == 0) {
if (his_want_state_is_wont(option)) {
switch (option) {
case TELOPT_BINARY:
init_termbuf();
tty_binaryin(1);
set_termbuf();
changeok++;
break;
case TELOPT_ECHO:
/*
* See comments below for more info.
*/
not42 = 0; /* looks like a 4.2 system */
break;
case TELOPT_TM:
#if defined(LINEMODE) && defined(KLUDGELINEMODE)
/*
* This telnetd implementation does not really
* support timing marks, it just uses them to
* support the kludge linemode stuff. If we
* receive a will or wont TM in response to our
* do TM request that may have been sent to
* determine kludge linemode support, process
* it, otherwise TM should get a negative
* response back.
*/
/*
* Handle the linemode kludge stuff.
* If we are not currently supporting any
* linemode at all, then we assume that this
* is the client telling us to use kludge
* linemode in response to our query. Set the
* linemode type that is to be supported, note
* that the client wishes to use linemode, and
* eat the will TM as though it never arrived.
*/
if (lmodetype < KLUDGE_LINEMODE) {
lmodetype = KLUDGE_LINEMODE;
clientstat(TELOPT_LINEMODE, WILL, 0);
send_wont(TELOPT_SGA, 1);
} else if (lmodetype == NO_AUTOKLUDGE) {
lmodetype = KLUDGE_OK;
}
#endif /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
/*
* We never respond to a WILL TM, and
* we leave the state WONT.
*/
return;
case TELOPT_LFLOW:
/*
* If we are going to support flow control
* option, then don't worry peer that we can't
* change the flow control characters.
*/
slctab[SLC_XON].defset.flag &= ~SLC_LEVELBITS;
slctab[SLC_XON].defset.flag |= SLC_DEFAULT;
slctab[SLC_XOFF].defset.flag &= ~SLC_LEVELBITS;
slctab[SLC_XOFF].defset.flag |= SLC_DEFAULT;
/* FALLTHROUGH */
case TELOPT_TTYPE:
case TELOPT_SGA:
case TELOPT_NAWS:
case TELOPT_TSPEED:
case TELOPT_XDISPLOC:
case TELOPT_NEW_ENVIRON:
case TELOPT_OLD_ENVIRON:
changeok++;
break;
#ifdef LINEMODE
case TELOPT_LINEMODE:
# ifdef KLUDGELINEMODE
/*
* Note client's desire to use linemode.
*/
lmodetype = REAL_LINEMODE;
# endif /* KLUDGELINEMODE */
func = doclientstat;
changeok++;
break;
#endif /* LINEMODE */
#ifdef AUTHENTICATION
case TELOPT_AUTHENTICATION:
func = auth_request;
changeok++;
break;
#endif
#ifdef ENCRYPTION
case TELOPT_ENCRYPT:
func = encrypt_send_support;
changeok++;
break;
#endif /* ENCRYPTION */
default:
break;
}
if (changeok) {
set_his_want_state_will(option);
send_do(option, 0);
} else {
do_dont_resp[option]++;
send_dont(option, 0);
}
} else {
/*
* Option processing that should happen when
* we receive conformation of a change in
* state that we had requested.
*/
switch (option) {
case TELOPT_ECHO:
not42 = 0; /* looks like a 4.2 system */
/*
* Egads, he responded "WILL ECHO". Turn
* it off right now!
*/
send_dont(option, 1);
/*
* "WILL ECHO". Kludge upon kludge!
* A 4.2 client is now echoing user input at
* the tty. This is probably undesireable and
* it should be stopped. The client will
* respond WONT TM to the DO TM that we send to
* check for kludge linemode. When the WONT TM
* arrives, linemode will be turned off and a
* change propagated to the pty. This change
* will cause us to process the new pty state
* in localstat(), which will notice that
* linemode is off and send a WILL ECHO
* so that we are properly in character mode and
* all is well.
*/
break;
#ifdef LINEMODE
case TELOPT_LINEMODE:
# ifdef KLUDGELINEMODE
/*
* Note client's desire to use linemode.
*/
lmodetype = REAL_LINEMODE;
# endif /* KLUDGELINEMODE */
func = doclientstat;
break;
#endif /* LINEMODE */
#ifdef AUTHENTICATION
case TELOPT_AUTHENTICATION:
func = auth_request;
break;
#endif
#ifdef ENCRYPTION
case TELOPT_ENCRYPT:
func = encrypt_send_support;
break;
#endif /* ENCRYPTION */
case TELOPT_LFLOW:
func = flowstat;
break;
}
}
}
set_his_state_will(option);
if (func)
(*func)();
} /* end of willoption */
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]++;
}
(void) output_data("%c%c%c", IAC, DONT, option);
DIAG(TD_OPTIONS, printoption("td: send dont", option));
}
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;
/* XXX double-check this --thorpej */
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
* achieve 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;
#ifdef AUTHENTICATION
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_OLD_ENVIRON:
settimer(oenvironsubopt);
break;
case TELOPT_NEW_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 < NO_AUTOKLUDGE) {
lmodetype = NO_LINEMODE;
clientstat(TELOPT_LINEMODE, WONT, 0);
send_will(TELOPT_SGA, 1);
send_will(TELOPT_ECHO, 1);
}
#endif /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
break;
#ifdef AUTHENTICATION
case TELOPT_AUTHENTICATION:
auth_finished(0, AUTH_REJECT);
break;
#endif
default:
break;
}
}
}
set_his_state_wont(option);
} /* end of wontoption */
void
send_will(int option, int init)
{
if (init) {
if ((will_wont_resp[option] == 0 && my_state_is_will(option))||
my_want_state_is_will(option))
return;
set_my_want_state_will(option);
will_wont_resp[option]++;
}
(void) output_data("%c%c%c", IAC, WILL, option);
DIAG(TD_OPTIONS, printoption("td: send will", option));
}
#if !defined(LINEMODE) || !defined(KLUDGELINEMODE)
/*
* When we get a DONT SGA, we will try once to turn it
* back on. If the other side responds DONT SGA, we
* leave it at that. This is so that when we talk to
* clients that understand KLUDGELINEMODE but not LINEMODE,
* we'll keep them in char-at-a-time mode.
*/
int turn_on_sga = 0;
#endif
void
dooption(int option)
{
int changeok = 0;
/*
* Process client input.
*/
DIAG(TD_OPTIONS, printoption("td: recv do", option));
if (will_wont_resp[option]) {
will_wont_resp[option]--;
if (will_wont_resp[option] && my_state_is_will(option))
will_wont_resp[option]--;
}
if ((will_wont_resp[option] == 0) && (my_want_state_is_wont(option))) {
switch (option) {
case TELOPT_ECHO:
#ifdef LINEMODE
# ifdef KLUDGELINEMODE
if (lmodetype == NO_LINEMODE)
# else
if (his_state_is_wont(TELOPT_LINEMODE))
# endif
#endif
{
init_termbuf();
tty_setecho(1);
set_termbuf();
}
changeok++;
break;
case TELOPT_BINARY:
init_termbuf();
tty_binaryout(1);
set_termbuf();
changeok++;
break;
case TELOPT_SGA:
#if defined(LINEMODE) && defined(KLUDGELINEMODE)
/*
* If kludge linemode is in use, then we must
* process an incoming do SGA for linemode
* purposes.
*/
if (lmodetype == KLUDGE_LINEMODE) {
/*
* Receipt of "do SGA" in kludge
* linemode is the peer asking us to
* turn off linemode. Make note of
* the request.
*/
clientstat(TELOPT_LINEMODE, WONT, 0);
/*
* If linemode did not get turned off
* then don't tell peer that we did.
* Breaking here forces a wont SGA to
* be returned.
*/
if (linemode)
break;
}
#else
turn_on_sga = 0;
#endif /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
changeok++;
break;
case TELOPT_STATUS:
changeok++;
break;
case TELOPT_TM:
/*
* Special case for TM. We send a WILL, but
* pretend we sent a WONT.
*/
send_will(option, 0);
set_my_want_state_wont(option);
set_my_state_wont(option);
return;
case TELOPT_LOGOUT:
/*
* When we get a LOGOUT option, respond
* with a WILL LOGOUT, make sure that
* it gets written out to the network,
* and then just go away...
*/
set_my_want_state_will(TELOPT_LOGOUT);
send_will(TELOPT_LOGOUT, 0);
set_my_state_will(TELOPT_LOGOUT);
(void)netflush();
cleanup(0);
/* NOT REACHED */
break;
#ifdef ENCRYPTION
case TELOPT_ENCRYPT:
changeok++;
break;
#endif /* ENCRYPTION */
case TELOPT_LINEMODE:
case TELOPT_TTYPE:
case TELOPT_NAWS:
case TELOPT_TSPEED:
case TELOPT_LFLOW:
case TELOPT_XDISPLOC:
case TELOPT_OLD_ENVIRON:
default:
break;
}
if (changeok) {
set_my_want_state_will(option);
send_will(option, 0);
} else {
will_wont_resp[option]++;
send_wont(option, 0);
}
}
set_my_state_will(option);
} /* end of dooption */
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]++;
}
(void) output_data("%c%c%c", IAC, WONT, option);
DIAG(TD_OPTIONS, printoption("td: send wont", option));
}
void
dontoption(int option)
{
/*
* Process client input.
*/
DIAG(TD_OPTIONS, printoption("td: recv dont", option));
if (will_wont_resp[option]) {
will_wont_resp[option]--;
if (will_wont_resp[option] && my_state_is_wont(option))
will_wont_resp[option]--;
}
if ((will_wont_resp[option] == 0) && (my_want_state_is_will(option))) {
switch (option) {
case TELOPT_BINARY:
init_termbuf();
tty_binaryout(0);
set_termbuf();
break;
case TELOPT_ECHO: /* we should stop echoing */
#ifdef LINEMODE
# ifdef KLUDGELINEMODE
if ((lmodetype != REAL_LINEMODE) &&
(lmodetype != KLUDGE_LINEMODE))
# else
if (his_state_is_wont(TELOPT_LINEMODE))
# endif
#endif
{
init_termbuf();
tty_setecho(0);
set_termbuf();
}
break;
case TELOPT_SGA:
#if defined(LINEMODE) && defined(KLUDGELINEMODE)
/*
* If kludge linemode is in use, then we
* must process an incoming do SGA for
* linemode purposes.
*/
if ((lmodetype == KLUDGE_LINEMODE) ||
(lmodetype == KLUDGE_OK)) {
/*
* The client is asking us to turn
* linemode on.
*/
lmodetype = KLUDGE_LINEMODE;
clientstat(TELOPT_LINEMODE, WILL, 0);
/*
* If we did not turn line mode on,
* then what do we say? Will SGA?
* This violates design of telnet.
* Gross. Very Gross.
*/
}
break;
#else
set_my_want_state_wont(option);
if (my_state_is_will(option))
send_wont(option, 0);
set_my_state_wont(option);
if (turn_on_sga ^= 1)
send_will(option, 1);
return;
#endif /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
default:
break;
}
set_my_want_state_wont(option);
if (my_state_is_will(option))
send_wont(option, 0);
}
set_my_state_wont(option);
} /* end of dontoption */
#ifdef ENV_HACK
int env_ovar = -1;
int env_ovalue = -1;
#else /* ENV_HACK */
# define env_ovar OLD_ENV_VAR
# define env_ovalue OLD_ENV_VALUE
#endif /* ENV_HACK */
/* envvarok(char*) */
/* check that variable is safe to pass to login or shell */
static int
envvarok(char *varp)
{
if (strcmp(varp, "TERMCAP") && /* to prevent a security hole */
strcmp(varp, "TERMINFO") && /* with tgetent */
strcmp(varp, "TERMPATH") &&
strcmp(varp, "HOME") && /* to prevent the tegetent bug */
strncmp(varp, "LD_", strlen("LD_")) && /* most systems */
strncmp(varp, "_RLD_", strlen("_RLD_")) && /* IRIX */
strcmp(varp, "LIBPATH") && /* AIX */
strcmp(varp, "ENV") &&
strcmp(varp, "BASH_ENV") &&
strcmp(varp, "IFS") &&
strncmp(varp, "KRB5", strlen("KRB5")) && /* Krb5 */
/*
* The above case is a catch-all for now. Here are some of
* the specific ones we must avoid passing, at least until
* we can prove it can be done safely. Keep this list
* around un case someone wants to remove the catch-all.
*/
strcmp(varp, "KRB5_CONFIG") && /* Krb5 */
strcmp(varp, "KRB5CCNAME") && /* Krb5 */
strcmp(varp, "KRB5_KTNAME") && /* Krb5 */
strcmp(varp, "KRBTKFILE") && /* Krb4 */
strcmp(varp, "KRB_CONF") && /* CNS 4 */
strcmp(varp, "KRB_REALMS") && /* CNS 4 */
strcmp(varp, "RESOLV_HOST_CONF")) /* Linux */
return (1);
else {
syslog(LOG_INFO, "Rejected the attempt to modify the "
"environment variable \"%s\"", varp);
return (0);
}
}
/*
* suboption()
*
* Look at the sub-option buffer, and try to be helpful to the other
* side.
*
* Currently we recognize:
*
* Terminal type is
* Linemode
* Window size
* Terminal speed
*/
void
suboption(void)
{
int subchar;
DIAG(TD_OPTIONS, {netflush(); printsub('<', subpointer, SB_LEN()+2);});
subchar = SB_GET();
switch (subchar) {
case TELOPT_TSPEED: {
int xspeed, rspeed;
if (his_state_is_wont(TELOPT_TSPEED)) /* Ignore if option disabled */
break;
settimer(tspeedsubopt);
if (SB_EOF() || SB_GET() != TELQUAL_IS)
return;
xspeed = atoi((char *)subpointer);
while (SB_GET() != ',' && !SB_EOF());
if (SB_EOF())
return;
rspeed = atoi((char *)subpointer);
clientstat(TELOPT_TSPEED, xspeed, rspeed);
break;
} /* end of case TELOPT_TSPEED */
case TELOPT_TTYPE: { /* Yaaaay! */
char *p;
if (his_state_is_wont(TELOPT_TTYPE)) /* Ignore if option disabled */
break;
settimer(ttypesubopt);
if (SB_EOF() || SB_GET() != TELQUAL_IS) {
return; /* ??? XXX but, this is the most robust */
}
p = terminaltype;
while ((p < (terminaltype + sizeof terminaltype-1)) &&
!SB_EOF()) {
int c;
c = SB_GET();
if (isupper(c)) {
c = tolower(c);
}
*p++ = c; /* accumulate name */
}
*p = 0;
break;
} /* end of case TELOPT_TTYPE */
case TELOPT_NAWS: {
int xwinsize, ywinsize;
if (his_state_is_wont(TELOPT_NAWS)) /* Ignore if option disabled */
break;
if (SB_EOF())
return;
xwinsize = SB_GET() << 8;
if (SB_EOF())
return;
xwinsize |= SB_GET();
if (SB_EOF())
return;
ywinsize = SB_GET() << 8;
if (SB_EOF())
return;
ywinsize |= SB_GET();
clientstat(TELOPT_NAWS, xwinsize, ywinsize);
break;
} /* end of case TELOPT_NAWS */
#ifdef LINEMODE
case TELOPT_LINEMODE: {
int request;
if (his_state_is_wont(TELOPT_LINEMODE)) /* Ignore if option disabled */
break;
/*
* Process linemode suboptions.
*/
if (SB_EOF())
break; /* garbage was sent */
request = SB_GET(); /* get will/wont */
if (SB_EOF())
break; /* another garbage check */
if (request == LM_SLC) { /* SLC is not preceded by WILL or WONT */
/*
* Process suboption buffer of slc's
*/
start_slc(1);
do_opt_slc(subpointer, SB_LEN());
(void) end_slc(0);
break;
} else if (request == LM_MODE) {
if (SB_EOF())
return;
useeditmode = SB_GET(); /* get mode flag */
clientstat(LM_MODE, 0, 0);
break;
}
if (SB_EOF())
break;
switch (SB_GET()) { /* what suboption? */
case LM_FORWARDMASK:
/*
* According to spec, only server can send request for
* forwardmask, and client can only return a positive response.
* So don't worry about it.
*/
default:
break;
}
break;
} /* end of case TELOPT_LINEMODE */
#endif
case TELOPT_STATUS: {
int mode;
if (SB_EOF())
break;
mode = SB_GET();
switch (mode) {
case TELQUAL_SEND:
if (my_state_is_will(TELOPT_STATUS))
send_status();
break;
case TELQUAL_IS:
break;
default:
break;
}
break;
} /* end of case TELOPT_STATUS */
case TELOPT_XDISPLOC: {
if (SB_EOF() || SB_GET() != TELQUAL_IS)
return;
settimer(xdisplocsubopt);
subpointer[SB_LEN()] = '\0';
(void)setenv("DISPLAY", (char *)subpointer, 1);
break;
} /* end of case TELOPT_XDISPLOC */
case TELOPT_NEW_ENVIRON:
case TELOPT_OLD_ENVIRON: {
int c;
char *cp, *varp, *valp;
if (SB_EOF())
return;
c = SB_GET();
if (c == TELQUAL_IS) {
if (subchar == TELOPT_OLD_ENVIRON)
settimer(oenvironsubopt);
else
settimer(environsubopt);
} else if (c != TELQUAL_INFO) {
return;
}
if (subchar == TELOPT_NEW_ENVIRON) {
while (!SB_EOF()) {
c = SB_GET();
if ((c == NEW_ENV_VAR) || (c == ENV_USERVAR))
break;
}
} else
{
#ifdef ENV_HACK
/*
* We only want to do this if we haven't already decided
* whether or not the other side has its VALUE and VAR
* reversed.
*/
if (env_ovar < 0) {
int last = -1; /* invalid value */
int empty = 0;
int got_var = 0, got_value = 0, got_uservar = 0;
/*
* The other side might have its VALUE and VAR values
* reversed. To be interoperable, we need to determine
* which way it is. If the first recognized character
* is a VAR or VALUE, then that will tell us what
* type of client it is. If the first recognized
* character is a USERVAR, then we continue scanning
* the suboption looking for two consecutive
* VAR or VALUE fields. We should not get two
* consecutive VALUE fields, so finding two
* consecutive VALUE or VAR fields will tell us
* what the client is.
*/
SB_SAVE();
while (!SB_EOF()) {
c = SB_GET();
switch(c) {
case OLD_ENV_VAR:
if (last < 0 || last == OLD_ENV_VAR
|| (empty && (last == OLD_ENV_VALUE)))
goto env_ovar_ok;
got_var++;
last = OLD_ENV_VAR;
break;
case OLD_ENV_VALUE:
if (last < 0 || last == OLD_ENV_VALUE
|| (empty && (last == OLD_ENV_VAR)))
goto env_ovar_wrong;
got_value++;
last = OLD_ENV_VALUE;
break;
case ENV_USERVAR:
/* count strings of USERVAR as one */
if (last != ENV_USERVAR)
got_uservar++;
if (empty) {
if (last == OLD_ENV_VALUE)
goto env_ovar_ok;
if (last == OLD_ENV_VAR)
goto env_ovar_wrong;
}
last = ENV_USERVAR;
break;
case ENV_ESC:
if (!SB_EOF())
c = SB_GET();
/* FALL THROUGH */
default:
empty = 0;
continue;
}
empty = 1;
}
if (empty) {
if (last == OLD_ENV_VALUE)
goto env_ovar_ok;
if (last == OLD_ENV_VAR)
goto env_ovar_wrong;
}
/*
* Ok, the first thing was a USERVAR, and there
* are not two consecutive VAR or VALUE commands,
* and none of the VAR or VALUE commands are empty.
* If the client has sent us a well-formed option,
* then the number of VALUEs received should always
* be less than or equal to the number of VARs and
* USERVARs received.
*
* If we got exactly as many VALUEs as VARs and
* USERVARs, the client has the same definitions.
*
* If we got exactly as many VARs as VALUEs and
* USERVARS, the client has reversed definitions.
*/
if (got_uservar + got_var == got_value) {
env_ovar_ok:
env_ovar = OLD_ENV_VAR;
env_ovalue = OLD_ENV_VALUE;
} else if (got_uservar + got_value == got_var) {
env_ovar_wrong:
env_ovar = OLD_ENV_VALUE;
env_ovalue = OLD_ENV_VAR;
DIAG(TD_OPTIONS, {output_data(
"ENVIRON VALUE and VAR are reversed!\r\n");});
}
}
SB_RESTORE();
#endif
while (!SB_EOF()) {
c = SB_GET();
if ((c == env_ovar) || (c == ENV_USERVAR))
break;
}
}
if (SB_EOF())
return;
cp = varp = (char *)subpointer;
valp = 0;
while (!SB_EOF()) {
c = SB_GET();
if (subchar == TELOPT_OLD_ENVIRON) {
if (c == env_ovar)
c = NEW_ENV_VAR;
else if (c == env_ovalue)
c = NEW_ENV_VALUE;
}
switch (c) {
case NEW_ENV_VALUE:
*cp = '\0';
cp = valp = (char *)subpointer;
break;
case NEW_ENV_VAR:
case ENV_USERVAR:
*cp = '\0';
if (envvarok(varp)) {
if (valp)
(void)setenv(varp, valp, 1);
else
unsetenv(varp);
}
cp = varp = (char *)subpointer;
valp = 0;
break;
case ENV_ESC:
if (SB_EOF())
break;
c = SB_GET();
/* FALL THROUGH */
default:
*cp++ = c;
break;
}
}
*cp = '\0';
if (envvarok(varp)) {
if (valp)
(void)setenv(varp, valp, 1);
else
unsetenv(varp);
}
break;
} /* end of case TELOPT_NEW_ENVIRON */
#ifdef AUTHENTICATION
case TELOPT_AUTHENTICATION:
if (SB_EOF())
break;
switch(SB_GET()) {
case TELQUAL_SEND:
case TELQUAL_REPLY:
/*
* These are sent by us and cannot be sent by
* the client.
*/
break;
case TELQUAL_IS:
auth_is(subpointer, SB_LEN());
break;
case TELQUAL_NAME:
auth_name(subpointer, SB_LEN());
break;
}
break;
#endif
#ifdef ENCRYPTION
case TELOPT_ENCRYPT:
if (SB_EOF())
break;
switch(SB_GET()) {
case ENCRYPT_SUPPORT:
encrypt_support(subpointer, SB_LEN());
break;
case ENCRYPT_IS:
encrypt_is(subpointer, SB_LEN());
break;
case ENCRYPT_REPLY:
encrypt_reply(subpointer, SB_LEN());
break;
case ENCRYPT_START:
encrypt_start(subpointer, SB_LEN());
break;
case ENCRYPT_END:
encrypt_end();
break;
case ENCRYPT_REQSTART:
encrypt_request_start(subpointer, SB_LEN());
break;
case ENCRYPT_REQEND:
/*
* We can always send an REQEND so that we cannot
* get stuck encrypting. We should only get this
* if we have been able to get in the correct mode
* anyhow.
*/
encrypt_request_end();
break;
case ENCRYPT_ENC_KEYID:
encrypt_enc_keyid(subpointer, SB_LEN());
break;
case ENCRYPT_DEC_KEYID:
encrypt_dec_keyid(subpointer, SB_LEN());
break;
default:
break;
}
break;
#endif /* ENCRYPTION */
default:
break;
} /* end of switch */
} /* end of suboption */
#ifdef LINEMODE
void
doclientstat(void)
{
clientstat(TELOPT_LINEMODE, WILL, 0);
}
#endif /* LINEMODE */
void
send_status(void)
{
#define ADD(c) \
do { \
if (ep > ncp) \
*ncp++ = c; \
else \
goto trunc; \
} while (0)
#define ADD_DATA(c) \
do { \
ADD(c); if (c == SE || c == IAC) ADD(c); \
} while (0)
unsigned char statusbuf[256];
unsigned char *ep;
unsigned char *ncp;
unsigned char i;
ncp = statusbuf;
ep = statusbuf + sizeof(statusbuf);
netflush(); /* get rid of anything waiting to go out */
ADD(IAC);
ADD(SB);
ADD(TELOPT_STATUS);
ADD(TELQUAL_IS);
/*
* We check the want_state rather than the current state,
* because if we received a DO/WILL for an option that we
* don't support, and the other side didn't send a DONT/WONT
* in response to our WONT/DONT, then the "state" will be
* WILL/DO, and the "want_state" will be WONT/DONT. We
* need to go by the latter.
*/
for (i = 0; i < (unsigned char)NTELOPTS; i++) {
if (my_want_state_is_will(i)) {
ADD(WILL);
ADD_DATA(i);
}
if (his_want_state_is_will(i)) {
ADD(DO);
ADD_DATA(i);
}
}
if (his_want_state_is_will(TELOPT_LFLOW)) {
ADD(SB);
ADD(TELOPT_LFLOW);
if (flowmode) {
ADD(LFLOW_ON);
} else {
ADD(LFLOW_OFF);
}
ADD(SE);
if (restartany >= 0) {
ADD(SB);
ADD(TELOPT_LFLOW);
if (restartany) {
ADD(LFLOW_RESTART_ANY);
} else {
ADD(LFLOW_RESTART_XON);
}
ADD(SE);
}
}
#ifdef LINEMODE
if (his_want_state_is_will(TELOPT_LINEMODE)) {
unsigned char *cp, *cpe;
int len;
ADD(SB);
ADD(TELOPT_LINEMODE);
ADD(LM_MODE);
ADD_DATA(editmode);
ADD(SE);
ADD(SB);
ADD(TELOPT_LINEMODE);
ADD(LM_SLC);
start_slc(0);
send_slc();
len = end_slc(&cp);
for (cpe = cp + len; cp < cpe; cp++)
ADD_DATA(*cp);
ADD(SE);
}
#endif /* LINEMODE */
ADD(IAC);
ADD(SE);
writenet(statusbuf, ncp - statusbuf);
netflush(); /* Send it on its way */
DIAG(TD_OPTIONS,
{printsub('>', statusbuf, ncp - statusbuf); netflush();});
return;
trunc:
/* XXX bark? */
return;
#undef ADD
#undef ADD_DATA
}
int
output_data(const char *format, ...)
{
va_list args;
size_t remaining, ret;
va_start(args, format);
remaining = BUFSIZ - (nfrontp - netobuf);
/* try a netflush() if the room is too low */
if (strlen(format) > remaining || BUFSIZ / 4 > remaining) {
netflush();
remaining = BUFSIZ - (nfrontp - netobuf);
}
ret = vsnprintf(nfrontp, remaining, format, args);
nfrontp += ((ret < remaining - 1) ? ret : remaining - 1);
va_end(args);
return ret;
}
int
output_datalen(const char *buf, size_t l)
{
size_t remaining;
remaining = BUFSIZ - (nfrontp - netobuf);
if (remaining < l) {
netflush();
remaining = BUFSIZ - (nfrontp - netobuf);
}
if (remaining < l)
return -1;
memmove(nfrontp, buf, l);
nfrontp += l;
return (int)l;
}
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