/* * 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. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. 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. */ #ifndef lint static char sccsid[] = "@(#)state.c 8.1 (Berkeley) 6/4/93"; #endif /* not lint */ /* This is a gutted version of the telnet option negotiation state machine code from the 4.4BSD-Lite libexec/telnetd/state.c. */ #include "tndefs.h" #include "tnext.h" unsigned char doopt[] = { IAC, DO, '%', 'c', 0 }; unsigned char dont[] = { IAC, DONT, '%', 'c', 0 }; unsigned char will[] = { IAC, WILL, '%', 'c', 0 }; unsigned char wont[] = { IAC, WONT, '%', 'c', 0 }; int not42 = 1; /* * Buffer for sub-options, and macros * for suboptions buffer manipulations */ unsigned char subbuffer[512], *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() { register int c; static int state = TS_DATA; #if defined(CRAY2) && defined(UNICOS5) char *opfrontp = pfrontp; #endif 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; /* Strip off \n or \0 after a \r */ if (his_state_is_wont(TELOPT_BINARY) && (c == 0) || (c == '\n')) { break; } /* FALL THROUGH */ case TS_DATA: if (c == IAC) { state = TS_IAC; break; } /* Get ready to strip of trailing \0 or \n. */ if (his_state_is_wont(TELOPT_BINARY) && (c == '\r')) { 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)); 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)); 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)); break; } /* * Check for urgent data... */ case DM: DIAG(TD_OPTIONS, printoption("td: recv IAC", c)); 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: break; case ABORT: 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, "telnetd: panic state=%d\n", state); printf("telnetd: panic state=%d\n", state); cleanup (); 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 * 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(option, init) int option, 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) sprintf(nfrontp, (char *)doopt, option); nfrontp += sizeof (dont) - 2; DIAG(TD_OPTIONS, printoption("td: send do", option)); } void willoption(option) int option; { int changeok = 0; void (*func)() = 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: changeok++; break; case TELOPT_ECHO: /* * See comments below for more info. */ not42 = 0; /* looks like a 4.2 system */ break; case TELOPT_TM: /* * 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; case TELOPT_TSPEED: changeok++; break; case TELOPT_TTYPE: case TELOPT_SGA: case TELOPT_NAWS: case TELOPT_XDISPLOC: case TELOPT_NEW_ENVIRON: case TELOPT_OLD_ENVIRON: 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 propogated 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; case TELOPT_LFLOW: /* func = flowstat; */ break; } } } set_his_state_will(option); if (func) (*func)(); } /* end of willoption */ void send_dont(option, init) int option, 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) sprintf(nfrontp, (char *)dont, option); nfrontp += sizeof (doopt) - 2; DIAG(TD_OPTIONS, printoption("td: send dont", option)); } void wontoption(option) 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: break; 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; /* * 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: break; default: break; } } } set_his_state_wont(option); } /* end of wontoption */ void send_will(option, init) int option, 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) sprintf(nfrontp, (char *)will, option); nfrontp += sizeof (doopt) - 2; DIAG(TD_OPTIONS, printoption("td: send will", option)); } void dooption(option) 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_BINARY: changeok++; break; case TELOPT_STATUS: changeok++; break; 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; case TELOPT_TM: case TELOPT_SGA: case TELOPT_LINEMODE: case TELOPT_TTYPE: case TELOPT_NAWS: case TELOPT_TSPEED: case TELOPT_LFLOW: case TELOPT_XDISPLOC: case TELOPT_OLD_ENVIRON: case TELOPT_ECHO: 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(option, init) int option, 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) sprintf(nfrontp, (char *)wont, option); nfrontp += sizeof (wont) - 2; DIAG(TD_OPTIONS, printoption("td: send wont", option)); } void dontoption(option) 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: break; 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 */ /* * 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() { register int subchar; DIAG(TD_OPTIONS, {netflush(); printsub('<', subpointer, SB_LEN()+2);}); subchar = SB_GET(); switch (subchar) { case TELOPT_TSPEED: { register 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); break; } /* end of case TELOPT_TSPEED */ 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 */ default: break; } /* end of switch */ } /* end of suboption */ #define ADD(c) *ncp++ = c #define ADD_DATA(c) { *ncp++ = c; if (c == SE || c == IAC) *ncp++ = c; } void send_status() { unsigned char statusbuf[256]; register unsigned char *ncp; register unsigned char i; ncp = 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); } } ADD(IAC); ADD(SE); writenet(statusbuf, ncp - statusbuf); netflush(); /* Send it on its way */ DIAG(TD_OPTIONS, {printsub('>', statusbuf, ncp - statusbuf); netflush();}); }