[u/mdw/putty] / telnet.c

#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <winsock.h>

#include "putty.h"

#ifndef FALSE
#define FALSE 0
#endif
#ifndef TRUE
#define TRUE 1
#endif

static SOCKET s = INVALID_SOCKET;

#define	IAC	255		/* interpret as command: */
#define	DONT	254		/* you are not to use option */
#define	DO	253		/* please, you use option */
#define	WONT	252		/* I won't use option */
#define	WILL	251		/* I will use option */
#define	SB	250		/* interpret as subnegotiation */
#define	SE	240		/* end sub negotiation */

#define GA      249             /* you may reverse the line */
#define EL      248             /* erase the current line */
#define EC      247             /* erase the current character */
#define	AYT	246		/* are you there */
#define	AO	245		/* abort output--but let prog finish */
#define	IP	244		/* interrupt process--permanently */
#define	BREAK	243		/* break */
#define DM      242             /* data mark--for connect. cleaning */
#define NOP     241             /* nop */
#define EOR     239             /* end of record (transparent mode) */
#define ABORT   238             /* Abort process */
#define SUSP    237             /* Suspend process */
#define xEOF    236             /* End of file: EOF is already used... */

#define TELOPT_BINARY	0	/* 8-bit data path */
#define TELOPT_ECHO	1	/* echo */
#define	TELOPT_RCP	2	/* prepare to reconnect */
#define	TELOPT_SGA	3	/* suppress go ahead */
#define	TELOPT_NAMS	4	/* approximate message size */
#define	TELOPT_STATUS	5	/* give status */
#define	TELOPT_TM	6	/* timing mark */
#define	TELOPT_RCTE	7	/* remote controlled transmission and echo */
#define TELOPT_NAOL 	8	/* negotiate about output line width */
#define TELOPT_NAOP 	9	/* negotiate about output page size */
#define TELOPT_NAOCRD	10	/* negotiate about CR disposition */
#define TELOPT_NAOHTS	11	/* negotiate about horizontal tabstops */
#define TELOPT_NAOHTD	12	/* negotiate about horizontal tab disposition */
#define TELOPT_NAOFFD	13	/* negotiate about formfeed disposition */
#define TELOPT_NAOVTS	14	/* negotiate about vertical tab stops */
#define TELOPT_NAOVTD	15	/* negotiate about vertical tab disposition */
#define TELOPT_NAOLFD	16	/* negotiate about output LF disposition */
#define TELOPT_XASCII	17	/* extended ascic character set */
#define	TELOPT_LOGOUT	18	/* force logout */
#define	TELOPT_BM	19	/* byte macro */
#define	TELOPT_DET	20	/* data entry terminal */
#define	TELOPT_SUPDUP	21	/* supdup protocol */
#define	TELOPT_SUPDUPOUTPUT 22	/* supdup output */
#define	TELOPT_SNDLOC	23	/* send location */
#define	TELOPT_TTYPE	24	/* terminal type */
#define	TELOPT_EOR	25	/* end or record */
#define	TELOPT_TUID	26	/* TACACS user identification */
#define	TELOPT_OUTMRK	27	/* output marking */
#define	TELOPT_TTYLOC	28	/* terminal location number */
#define	TELOPT_3270REGIME 29	/* 3270 regime */
#define	TELOPT_X3PAD	30	/* X.3 PAD */
#define	TELOPT_NAWS	31	/* window size */
#define	TELOPT_TSPEED	32	/* terminal speed */
#define	TELOPT_LFLOW	33	/* remote flow control */
#define TELOPT_LINEMODE	34	/* Linemode option */
#define TELOPT_XDISPLOC	35	/* X Display Location */
#define TELOPT_OLD_ENVIRON 36	/* Old - Environment variables */
#define	TELOPT_AUTHENTICATION 37/* Authenticate */
#define	TELOPT_ENCRYPT	38	/* Encryption option */
#define TELOPT_NEW_ENVIRON 39	/* New - Environment variables */
#define	TELOPT_EXOPL	255	/* extended-options-list */

#define	TELQUAL_IS	0	/* option is... */
#define	TELQUAL_SEND	1	/* send option */
#define	TELQUAL_INFO	2	/* ENVIRON: informational version of IS */
#define BSD_VAR 1
#define BSD_VALUE 0
#define RFC_VAR 0
#define RFC_VALUE 1

#define CR 13
#define LF 10
#define NUL 0

#define iswritable(x) ( (x) != IAC && (x) != CR )

static char *telopt(int opt) {
#define i(x) if (opt == TELOPT_ ## x) return #x;
    i(BINARY); i(ECHO); i(RCP); i(SGA); i(NAMS); i(STATUS); i(TM); i(RCTE);
    i(NAOL); i(NAOP); i(NAOCRD); i(NAOHTS); i(NAOHTD); i(NAOFFD); i(NAOVTS);
    i(NAOVTD); i(NAOLFD); i(XASCII); i(LOGOUT); i(BM); i(DET); i(SUPDUP);
    i(SUPDUPOUTPUT); i(SNDLOC); i(TTYPE); i(EOR); i(TUID); i(OUTMRK);
    i(TTYLOC); i(X3PAD); i(NAWS); i(TSPEED); i(LFLOW); i(LINEMODE);
    i(XDISPLOC); i(OLD_ENVIRON); i(AUTHENTICATION); i(ENCRYPT);
    i(NEW_ENVIRON); i(EXOPL);
#undef i
    return "<unknown>";
}

static void telnet_size(void);

struct Opt {
    int send;			       /* what we initially send */
    int nsend;			       /* -ve send if requested to stop it */
    int ack, nak;		       /* +ve and -ve acknowledgements */
    int option;			       /* the option code */
    enum {
	REQUESTED, ACTIVE, INACTIVE, REALLY_INACTIVE
    } state;
};

static struct Opt o_naws = {WILL, WONT, DO, DONT, TELOPT_NAWS, REQUESTED};
static struct Opt o_tspeed = {WILL, WONT, DO, DONT, TELOPT_TSPEED, REQUESTED};
static struct Opt o_ttype = {WILL, WONT, DO, DONT, TELOPT_TTYPE, REQUESTED};
static struct Opt o_oenv = {WILL, WONT, DO, DONT, TELOPT_OLD_ENVIRON,
    INACTIVE};
static struct Opt o_nenv = {WILL, WONT, DO, DONT, TELOPT_NEW_ENVIRON,
    REQUESTED};
static struct Opt o_echo = {DO, DONT, WILL, WONT, TELOPT_ECHO, REQUESTED};
static struct Opt o_we_sga = {WILL, WONT, DO, DONT, TELOPT_SGA, REQUESTED};
static struct Opt o_they_sga = {DO, DONT, WILL, WONT, TELOPT_SGA, REQUESTED};

static struct Opt *opts[] = {
    &o_naws, &o_tspeed, &o_ttype, &o_oenv, &o_nenv, &o_echo,
    &o_we_sga, &o_they_sga, NULL
};

#if 0
static int in_synch;
#endif

static int sb_opt, sb_len;
static char *sb_buf = NULL;
static int sb_size = 0;
#define SB_DELTA 1024

static void try_write (void) {
    while (outbuf_head != outbuf_reap) {
	int end = (outbuf_reap < outbuf_head ? outbuf_head : OUTBUF_SIZE);
	int len = end - outbuf_reap;
	int ret;

	ret = send (s, outbuf+outbuf_reap, len, 0);
	if (ret > 0)
	    outbuf_reap = (outbuf_reap + ret) & OUTBUF_MASK;
	if (ret < len)
	    return;
    }
}

static void s_write (void *buf, int len) {
    unsigned char *p = buf;
    while (len--) {
	int new_head = (outbuf_head + 1) & OUTBUF_MASK;
	if (new_head != outbuf_reap) {
	    outbuf[outbuf_head] = *p++;
	    outbuf_head = new_head;
	}
    }
    try_write();
}

static void c_write (char *buf, int len) {
    while (len--) {
	int new_head = (inbuf_head + 1) & INBUF_MASK;
	if (new_head != inbuf_reap) {
	    inbuf[inbuf_head] = *buf++;
	    inbuf_head = new_head;
	}
    }
}

static void log_option (char *sender, int cmd, int option) {
    char buf[50];
    sprintf(buf, "%s:\t%s %s", sender,
	    (cmd == WILL ? "WILL" : cmd == WONT ? "WONT" :
	     cmd == DO ? "DO" : cmd == DONT ? "DONT" : "<??>"),
	    telopt(option));
    lognegot(buf);
}

static void send_opt (int cmd, int option) {
    unsigned char b[3];

    b[0] = IAC; b[1] = cmd; b[2] = option;
    s_write (b, 3);
    log_option("client", cmd, option);
}

static void deactivate_option (struct Opt *o) {
    if (o->state == REQUESTED || o->state == ACTIVE)
	send_opt (o->nsend, o->option);
    o->state = REALLY_INACTIVE;
}

static void activate_option (struct Opt *o) {
    if (o->send == WILL && o->option == TELOPT_NAWS)
	telnet_size();
    if (o->send == WILL &&
	(o->option == TELOPT_NEW_ENVIRON ||
	 o->option == TELOPT_OLD_ENVIRON)) {
	/*
	 * We may only have one kind of ENVIRON going at a time.
	 * This is a hack, but who cares.
	 */
	deactivate_option (o->option==TELOPT_NEW_ENVIRON ? &o_oenv : &o_nenv);
    }
}

static void refused_option (struct Opt *o) {
    if (o->send == WILL && o->option == TELOPT_NEW_ENVIRON &&
	o_oenv.state == INACTIVE) {
	send_opt (WILL, TELOPT_OLD_ENVIRON);
	o_oenv.state = REQUESTED;
    }
}

static void proc_rec_opt (int cmd, int option) {
    struct Opt **o;

    log_option ("server", cmd, option);
    for (o = opts; *o; o++) {
	if ((*o)->option == option && (*o)->ack == cmd) {
	    switch ((*o)->state) {
	      case REQUESTED:
		(*o)->state = ACTIVE;
		activate_option (*o);
		break;
	      case ACTIVE:
		break;
	      case INACTIVE:
		(*o)->state = ACTIVE;
		send_opt ((*o)->send, option);
		activate_option (*o);
		break;
	      case REALLY_INACTIVE:
		send_opt ((*o)->nsend, option);
		break;
	    }
	    return;
	} else if ((*o)->option == option && (*o)->nak == cmd) {
	    switch ((*o)->state) {
	      case REQUESTED:
		(*o)->state = INACTIVE;
		refused_option (*o);
		break;
	      case ACTIVE:
		(*o)->state = INACTIVE;
		send_opt ((*o)->nsend, option);
		break;
	      case INACTIVE:
	      case REALLY_INACTIVE:
		break;
	    }
	    return;
	}
    }
    /*
     * If we reach here, the option was one we weren't prepared to
     * cope with. So send a negative ack.
     */
    send_opt ((cmd == WILL ? DONT : WONT), option);
}

static void process_subneg (void) {
    unsigned char b[2048], *p, *q;
    int var, value, n;
    char *e;

    switch (sb_opt) {
      case TELOPT_TSPEED:
	if (sb_len == 1 && sb_buf[0] == TELQUAL_SEND) {
	    char logbuf[sizeof(cfg.termspeed)+80];
	    b[0] = IAC; b[1] = SB; b[2] = TELOPT_TSPEED;
	    b[3] = TELQUAL_IS;
	    strcpy(b+4, cfg.termspeed);
	    n = 4 + strlen(cfg.termspeed);
	    b[n] = IAC; b[n+1] = SE;
	    s_write (b, n+2);
	    lognegot("server:\tSB TSPEED SEND");
	    sprintf(logbuf, "client:\tSB TSPEED IS %s", cfg.termspeed);
	    lognegot (logbuf);
	} else
	    lognegot ("server:\tSB TSPEED <something weird>");
	break;
      case TELOPT_TTYPE:
	if (sb_len == 1 && sb_buf[0] == TELQUAL_SEND) {
	    char logbuf[sizeof(cfg.termtype)+80];
	    b[0] = IAC; b[1] = SB; b[2] = TELOPT_TTYPE;
	    b[3] = TELQUAL_IS;
	    for (n = 0; cfg.termtype[n]; n++)
		b[n+4] = (cfg.termtype[n] >= 'a' && cfg.termtype[n] <= 'z' ?
			  cfg.termtype[n] + 'A'-'a' : cfg.termtype[n]);
	    b[n+4] = IAC; b[n+5] = SE;
	    s_write (b, n+6);
	    b[n+4] = 0;
	    lognegot("server:\tSB TTYPE SEND");
	    sprintf(logbuf, "client:\tSB TTYPE IS %s", b+4);
	    lognegot(logbuf);
	} else
	    lognegot("server:\tSB TTYPE <something weird>\r\n");
	break;
      case TELOPT_OLD_ENVIRON:
      case TELOPT_NEW_ENVIRON:	
	p = sb_buf;
	q = p + sb_len;
	if (p < q && *p == TELQUAL_SEND) {
	    char logbuf[50];
	    p++;
	    sprintf (logbuf, "server:\tSB %s SEND", telopt(sb_opt));
	    lognegot (logbuf);
	    if (sb_opt == TELOPT_OLD_ENVIRON) {
		if (cfg.rfc_environ) {
		    value = RFC_VALUE;
		    var = RFC_VAR;
		} else {
		    value = BSD_VALUE;
		    var = BSD_VAR;
		}
		/*
		 * Try to guess the sense of VAR and VALUE.
		 */
		while (p < q) {
		    if (*p == RFC_VAR) {
			value = RFC_VALUE;
			var = RFC_VAR;
		    } else if (*p == BSD_VAR) {
			value = BSD_VALUE;
			var = BSD_VAR;
		    }
		    p++;
		}
	    } else {
		/*
		 * With NEW_ENVIRON, the sense of VAR and VALUE
		 * isn't in doubt.
		 */
		value = RFC_VALUE;
		var = RFC_VAR;
	    }
	    b[0] = IAC; b[1] = SB; b[2] = sb_opt;
	    b[3] = TELQUAL_IS;
	    n = 4;
          e = cfg.environmt;
	    while (*e) {
		b[n++] = var;
		while (*e && *e != '\t') b[n++] = *e++;
		if (*e == '\t') e++;
		b[n++] = value;
		while (*e) b[n++] = *e++;
		e++;
	    }
	    if (*cfg.username) {
		b[n++] = var; b[n++] = 'U'; b[n++] = 'S';
		b[n++] = 'E'; b[n++] = 'R'; b[n++] = value;
		e = cfg.username;
		while (*e) b[n++] = *e++;
	    }
	    b[n++] = IAC; b[n++] = SE;
	    s_write (b, n);
	    sprintf(logbuf, "client:\tSB %s IS %s", telopt(sb_opt),
		    n==6 ? "<nothing>" : "<stuff>");
	    lognegot (logbuf);
	}
	break;
    }
}

static enum {
    TOPLEVEL, SEENIAC, SEENWILL, SEENWONT, SEENDO, SEENDONT,
    SEENSB, SUBNEGOT, SUBNEG_IAC, SEENCR
} telnet_state = TOPLEVEL;

static void do_telnet_read (char *buf, int len) {
    unsigned char b[10];

    while (len--) {
	int c = (unsigned char) *buf++;

	switch (telnet_state) {
	  case TOPLEVEL:
	  case SEENCR:
	    if (c == NUL && telnet_state == SEENCR)
		telnet_state = TOPLEVEL;
	    else if (c == IAC)
		telnet_state = SEENIAC;
	    else {
		b[0] = c;
#if 0
		if (!in_synch)
#endif
		    c_write (b, 1);
		if (c == CR)
		    telnet_state = SEENCR;
		else
		    telnet_state = TOPLEVEL;
	    }
	    break;
	  case SEENIAC:
	    if (c == DO) telnet_state = SEENDO;
	    else if (c == DONT) telnet_state = SEENDONT;
	    else if (c == WILL) telnet_state = SEENWILL;
	    else if (c == WONT) telnet_state = SEENWONT;
	    else if (c == SB) telnet_state = SEENSB;
	    else telnet_state = TOPLEVEL;/* ignore _everything_ else! */
	    break;
	  case SEENWILL:
	    proc_rec_opt (WILL, c);
	    telnet_state = TOPLEVEL;
	    break;
	  case SEENWONT:
	    proc_rec_opt (WONT, c);
	    telnet_state = TOPLEVEL;
	    break;
	  case SEENDO:
	    proc_rec_opt (DO, c);
	    telnet_state = TOPLEVEL;
	    break;
	  case SEENDONT:
	    proc_rec_opt (DONT, c);
	    telnet_state = TOPLEVEL;
	    break;
	  case SEENSB:
	    sb_opt = c;
	    sb_len = 0;
	    telnet_state = SUBNEGOT;
	    break;
	  case SUBNEGOT:
	    if (c == IAC)
		telnet_state = SUBNEG_IAC;
	    else {
		subneg_addchar:
		if (sb_len >= sb_size) {
		    char *newbuf;
		    sb_size += SB_DELTA;
		    newbuf = (sb_buf ?
			      realloc(sb_buf, sb_size) :
			      malloc(sb_size));
		    if (newbuf)
			sb_buf = newbuf;
		    else
			sb_size -= SB_DELTA;
		}
		if (sb_len < sb_size)
		    sb_buf[sb_len++] = c;
		telnet_state = SUBNEGOT;/* in case we came here by goto */
	    }
	    break;
	  case SUBNEG_IAC:
	    if (c != SE)
		goto subneg_addchar;   /* yes, it's a hack, I know, but... */
	    else {
		process_subneg();
		telnet_state = TOPLEVEL;
	    }
	    break;
	}
    }
}

/*
 * Called to set up the Telnet connection. Will arrange for
 * WM_NETEVENT messages to be passed to the specified window, whose
 * window procedure should then call telnet_msg().
 *
 * Returns an error message, or NULL on success.
 *
 * Also places the canonical host name into `realhost'.
 */
static char *telnet_init (HWND hwnd, char *host, int port, char **realhost) {
    SOCKADDR_IN addr;
    struct hostent *h;
    unsigned long a;

    /*
     * Try to find host.
     */
    if ( (a = inet_addr(host)) == (unsigned long) INADDR_NONE) {
	if ( (h = gethostbyname(host)) == NULL)
	    switch (WSAGetLastError()) {
	      case WSAENETDOWN: return "Network is down";
	      case WSAHOST_NOT_FOUND: case WSANO_DATA:
		return "Host does not exist";
	      case WSATRY_AGAIN: return "Host not found";
	      default: return "gethostbyname: unknown error";
	    }
	memcpy (&a, h->h_addr, sizeof(a));
	*realhost = h->h_name;
    } else
	*realhost = host;
    a = ntohl(a);

    if (port < 0)
	port = 23;		       /* default telnet port */

    /*
     * Open socket.
     */
    s = socket(AF_INET, SOCK_STREAM, 0);
    if (s == INVALID_SOCKET)
	switch (WSAGetLastError()) {
	  case WSAENETDOWN: return "Network is down";
	  case WSAEAFNOSUPPORT: return "TCP/IP support not present";
	  default: return "socket(): unknown error";
	}

#if 0
    {
	BOOL b = TRUE;
	setsockopt (s, SOL_SOCKET, SO_OOBINLINE, (void *)&b, sizeof(b));
    }
#endif

    /*
     * Bind to local address.
     */
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = htonl(INADDR_ANY);
    addr.sin_port = htons(0);
    if (bind (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
	switch (WSAGetLastError()) {
	  case WSAENETDOWN: return "Network is down";
	  default: return "bind(): unknown error";
	}

    /*
     * Connect to remote address.
     */
    addr.sin_addr.s_addr = htonl(a);
    addr.sin_port = htons((short)port);
    if (connect (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
	switch (WSAGetLastError()) {
	  case WSAENETDOWN: return "Network is down";
	  case WSAECONNREFUSED: return "Connection refused";
	  case WSAENETUNREACH: return "Network is unreachable";
	  case WSAEHOSTUNREACH: return "No route to host";
	  default: return "connect(): unknown error";
	}

    if (WSAAsyncSelect (s, hwnd, WM_NETEVENT, FD_READ |
			FD_WRITE | FD_OOB | FD_CLOSE) == SOCKET_ERROR)
	switch (WSAGetLastError()) {
	  case WSAENETDOWN: return "Network is down";
	  default: return "WSAAsyncSelect(): unknown error";
	}

    /*
     * Initialise option states.
     */
    {
	struct Opt **o;

	for (o = opts; *o; o++)
	    if ((*o)->state == REQUESTED)
		send_opt ((*o)->send, (*o)->option);
    }

#if 0
    /*
     * Set up SYNCH state.
     */
    in_synch = FALSE;
#endif

    return NULL;
}

/*
 * Process a WM_NETEVENT message. Will return 0 if the connection
 * has closed, or <0 for a socket error.
 */
static int telnet_msg (WPARAM wParam, LPARAM lParam) {
    int ret;
    char buf[256];

    if (s == INVALID_SOCKET)	       /* how the hell did we get here?! */
	return -5000;

    if (WSAGETSELECTERROR(lParam) != 0)
	return -WSAGETSELECTERROR(lParam);

    switch (WSAGETSELECTEVENT(lParam)) {
      case FD_READ:
	ret = recv(s, buf, sizeof(buf), 0);
	if (ret < 0 && WSAGetLastError() == WSAEWOULDBLOCK)
	    return 1;
	if (ret < 0)		       /* any _other_ error */
	    return -10000-WSAGetLastError();
	if (ret == 0) {
	    s = INVALID_SOCKET;
	    return 0;		       /* can't happen, in theory */
	}
#if 0
	if (in_synch) {
	    BOOL i;
	    if (ioctlsocket (s, SIOCATMARK, &i) < 0) {
		return -20000-WSAGetLastError();
	    }
	    if (i)
		in_synch = FALSE;
	}
#endif
	do_telnet_read (buf, ret);
	return 1;
      case FD_OOB:
	do {
	    ret = recv(s, buf, sizeof(buf), 0);
	} while (ret > 0);
	telnet_state = TOPLEVEL;
	do {
	    ret = recv(s, buf, 1, MSG_OOB);
	    if (ret > 0)
		do_telnet_read (buf, ret);
	} while (ret > 0);
	if (ret < 0 && WSAGetLastError() != WSAEWOULDBLOCK)
	    return -30000-WSAGetLastError();
	return 1;
      case FD_WRITE:
	if (outbuf_head != outbuf_reap)
	    try_write();
	return 1;
      case FD_CLOSE:
	s = INVALID_SOCKET;
	return 0;
    }
    return 1;			       /* shouldn't happen, but WTF */
}

/*
 * Called to send data down the Telnet connection.
 */
static void telnet_send (char *buf, int len) {
    char *p;
    static unsigned char iac[2] = { IAC, IAC };
    static unsigned char cr[2] = { CR, NUL };

    if (s == INVALID_SOCKET)
	return;

    p = buf;
    while (p < buf+len) {
	char *q = p;

	while (iswritable((unsigned char)*p) && p < buf+len) p++;
	s_write (q, p-q);

	while (p < buf+len && !iswritable((unsigned char)*p)) {
	    s_write ((unsigned char)*p == IAC ? iac : cr, 2);
	    p++;
	}
    }
}

/*
 * Called to set the size of the window from Telnet's POV.
 */
static void telnet_size(void) {
    unsigned char b[16];
    char logbuf[50];

    if (s == INVALID_SOCKET || o_naws.state != ACTIVE)
	return;
    b[0] = IAC; b[1] = SB; b[2] = TELOPT_NAWS;
    b[3] = cols >> 8; b[4] = cols & 0xFF;
    b[5] = rows >> 8; b[6] = rows & 0xFF;
    b[7] = IAC; b[8] = SE;
    s_write (b, 9);
    sprintf(logbuf, "client:\tSB NAWS %d,%d",
	    ((unsigned char)b[3] << 8) + (unsigned char)b[4],
	    ((unsigned char)b[5] << 8) + (unsigned char)b[6]);
    lognegot (logbuf);
}

/*
 * Send Telnet special codes.
 */
static void telnet_special (Telnet_Special code) {
    unsigned char b[2];

    if (s == INVALID_SOCKET)
	return;

    b[0] = IAC;
    switch (code) {
      case TS_AYT: b[1] = AYT; s_write (b, 2); break;
      case TS_BRK: b[1] = BREAK; s_write (b, 2); break;
      case TS_EC: b[1] = EC; s_write (b, 2); break;
      case TS_EL: b[1] = EL; s_write (b, 2); break;
      case TS_GA: b[1] = GA; s_write (b, 2); break;
      case TS_NOP: b[1] = NOP; s_write (b, 2); break;
      case TS_ABORT: b[1] = ABORT; s_write (b, 2); break;
      case TS_AO: b[1] = AO; s_write (b, 2); break;
      case TS_IP: b[1] = IP; s_write (b, 2); break;
      case TS_SUSP: b[1] = SUSP; s_write (b, 2); break;
      case TS_EOR: b[1] = EOR; s_write (b, 2); break;
      case TS_EOF: b[1] = xEOF; s_write (b, 2); break;
      case TS_SYNCH:
	outbuf_head = outbuf_reap = 0;
	b[0] = DM;
	send (s, b, 1, MSG_OOB);
	break;
    }
}

Backend telnet_backend = {
    telnet_init,
    telnet_msg,
    telnet_send,
    telnet_size,
    telnet_special
};
Commit	Line	Data
374330e2	1	#include <windows.h>
	2	#include <stdio.h>
	3	#include <stdlib.h>
	4	#include <winsock.h>
	5
	6	#include "putty.h"
	7
	8	#ifndef FALSE
	9	#define FALSE 0
	10	#endif
	11	#ifndef TRUE
	12	#define TRUE 1
	13	#endif
	14
	15	static SOCKET s = INVALID_SOCKET;
	16
	17	#define IAC 255 /* interpret as command: */
	18	#define DONT 254 /* you are not to use option */
	19	#define DO 253 /* please, you use option */
	20	#define WONT 252 /* I won't use option */
	21	#define WILL 251 /* I will use option */
	22	#define SB 250 /* interpret as subnegotiation */
	23	#define SE 240 /* end sub negotiation */
	24
	25	#define GA 249 /* you may reverse the line */
	26	#define EL 248 /* erase the current line */
	27	#define EC 247 /* erase the current character */
	28	#define AYT 246 /* are you there */
	29	#define AO 245 /* abort output--but let prog finish */
	30	#define IP 244 /* interrupt process--permanently */
	31	#define BREAK 243 /* break */
	32	#define DM 242 /* data mark--for connect. cleaning */
	33	#define NOP 241 /* nop */
	34	#define EOR 239 /* end of record (transparent mode) */
	35	#define ABORT 238 /* Abort process */
	36	#define SUSP 237 /* Suspend process */
	37	#define xEOF 236 /* End of file: EOF is already used... */
	38
	39	#define TELOPT_BINARY 0 /* 8-bit data path */
	40	#define TELOPT_ECHO 1 /* echo */
	41	#define TELOPT_RCP 2 /* prepare to reconnect */
	42	#define TELOPT_SGA 3 /* suppress go ahead */
	43	#define TELOPT_NAMS 4 /* approximate message size */
	44	#define TELOPT_STATUS 5 /* give status */
	45	#define TELOPT_TM 6 /* timing mark */
	46	#define TELOPT_RCTE 7 /* remote controlled transmission and echo */
	47	#define TELOPT_NAOL 8 /* negotiate about output line width */
	48	#define TELOPT_NAOP 9 /* negotiate about output page size */
	49	#define TELOPT_NAOCRD 10 /* negotiate about CR disposition */
	50	#define TELOPT_NAOHTS 11 /* negotiate about horizontal tabstops */
	51	#define TELOPT_NAOHTD 12 /* negotiate about horizontal tab disposition */
	52	#define TELOPT_NAOFFD 13 /* negotiate about formfeed disposition */
	53	#define TELOPT_NAOVTS 14 /* negotiate about vertical tab stops */
	54	#define TELOPT_NAOVTD 15 /* negotiate about vertical tab disposition */
	55	#define TELOPT_NAOLFD 16 /* negotiate about output LF disposition */
	56	#define TELOPT_XASCII 17 /* extended ascic character set */
	57	#define TELOPT_LOGOUT 18 /* force logout */
	58	#define TELOPT_BM 19 /* byte macro */
	59	#define TELOPT_DET 20 /* data entry terminal */
	60	#define TELOPT_SUPDUP 21 /* supdup protocol */
	61	#define TELOPT_SUPDUPOUTPUT 22 /* supdup output */
	62	#define TELOPT_SNDLOC 23 /* send location */
	63	#define TELOPT_TTYPE 24 /* terminal type */
	64	#define TELOPT_EOR 25 /* end or record */
65	#define TELOPT_TUID 26 /* TACACS user identification */
66	#define TELOPT_OUTMRK 27 /* output marking */
67	#define TELOPT_TTYLOC 28 /* terminal location number */
68	#define TELOPT_3270REGIME 29 /* 3270 regime */
69	#define TELOPT_X3PAD 30 /* X.3 PAD */
70	#define TELOPT_NAWS 31 /* window size */
71	#define TELOPT_TSPEED 32 /* terminal speed */
72	#define TELOPT_LFLOW 33 /* remote flow control */
73	#define TELOPT_LINEMODE 34 /* Linemode option */
74	#define TELOPT_XDISPLOC 35 /* X Display Location */
75	#define TELOPT_OLD_ENVIRON 36 /* Old - Environment variables */
76	#define TELOPT_AUTHENTICATION 37/* Authenticate */
77	#define TELOPT_ENCRYPT 38 /* Encryption option */
78	#define TELOPT_NEW_ENVIRON 39 /* New - Environment variables */
79	#define TELOPT_EXOPL 255 /* extended-options-list */
80
81	#define TELQUAL_IS 0 /* option is... */
82	#define TELQUAL_SEND 1 /* send option */
83	#define TELQUAL_INFO 2 /* ENVIRON: informational version of IS */
84	#define BSD_VAR 1
85	#define BSD_VALUE 0
86	#define RFC_VAR 0
87	#define RFC_VALUE 1
88
89	#define CR 13
90	#define LF 10
91	#define NUL 0
92
93	#define iswritable(x) ( (x) != IAC && (x) != CR )
94
95	static char *telopt(int opt) {
96	#define i(x) if (opt == TELOPT_ ## x) return #x;
97	i(BINARY); i(ECHO); i(RCP); i(SGA); i(NAMS); i(STATUS); i(TM); i(RCTE);
98	i(NAOL); i(NAOP); i(NAOCRD); i(NAOHTS); i(NAOHTD); i(NAOFFD); i(NAOVTS);
99	i(NAOVTD); i(NAOLFD); i(XASCII); i(LOGOUT); i(BM); i(DET); i(SUPDUP);
100	i(SUPDUPOUTPUT); i(SNDLOC); i(TTYPE); i(EOR); i(TUID); i(OUTMRK);
101	i(TTYLOC); i(X3PAD); i(NAWS); i(TSPEED); i(LFLOW); i(LINEMODE);
102	i(XDISPLOC); i(OLD_ENVIRON); i(AUTHENTICATION); i(ENCRYPT);
103	i(NEW_ENVIRON); i(EXOPL);
104	#undef i
105	return "<unknown>";
106	}
107
108	static void telnet_size(void);
109
110	struct Opt {
111	int send; /* what we initially send */
112	int nsend; /* -ve send if requested to stop it */
113	int ack, nak; /* +ve and -ve acknowledgements */
114	int option; /* the option code */
115	enum {
116	REQUESTED, ACTIVE, INACTIVE, REALLY_INACTIVE
117	} state;
118	};
119
120	static struct Opt o_naws = {WILL, WONT, DO, DONT, TELOPT_NAWS, REQUESTED};
121	static struct Opt o_tspeed = {WILL, WONT, DO, DONT, TELOPT_TSPEED, REQUESTED};
122	static struct Opt o_ttype = {WILL, WONT, DO, DONT, TELOPT_TTYPE, REQUESTED};
123	static struct Opt o_oenv = {WILL, WONT, DO, DONT, TELOPT_OLD_ENVIRON,
124	INACTIVE};
125	static struct Opt o_nenv = {WILL, WONT, DO, DONT, TELOPT_NEW_ENVIRON,
126	REQUESTED};
127	static struct Opt o_echo = {DO, DONT, WILL, WONT, TELOPT_ECHO, REQUESTED};
128	static struct Opt o_we_sga = {WILL, WONT, DO, DONT, TELOPT_SGA, REQUESTED};
129	static struct Opt o_they_sga = {DO, DONT, WILL, WONT, TELOPT_SGA, REQUESTED};
130
131	static struct Opt *opts[] = {
132	&o_naws, &o_tspeed, &o_ttype, &o_oenv, &o_nenv, &o_echo,
133	&o_we_sga, &o_they_sga, NULL
134	};
135
136	#if 0
137	static int in_synch;
138	#endif
139
140	static int sb_opt, sb_len;
141	static char *sb_buf = NULL;
142	static int sb_size = 0;
143	#define SB_DELTA 1024
144
145	static void try_write (void) {
146	while (outbuf_head != outbuf_reap) {
147	int end = (outbuf_reap < outbuf_head ? outbuf_head : OUTBUF_SIZE);
148	int len = end - outbuf_reap;
149	int ret;
150
151	ret = send (s, outbuf+outbuf_reap, len, 0);
152	if (ret > 0)
153	outbuf_reap = (outbuf_reap + ret) & OUTBUF_MASK;
154	if (ret < len)
155	return;
156	}
157	}
158
159	static void s_write (void *buf, int len) {
160	unsigned char *p = buf;
161	while (len--) {
162	int new_head = (outbuf_head + 1) & OUTBUF_MASK;
163	if (new_head != outbuf_reap) {
164	outbuf[outbuf_head] = *p++;
165	outbuf_head = new_head;
166	}
167	}
168	try_write();
169	}
170
171	static void c_write (char *buf, int len) {
172	while (len--) {
173	int new_head = (inbuf_head + 1) & INBUF_MASK;
374330e2	174	if (new_head != inbuf_reap) {
	175	inbuf[inbuf_head] = *buf++;
	176	inbuf_head = new_head;
	177	}
	178	}
	179	}
	180
	181	static void log_option (char *sender, int cmd, int option) {
	182	char buf[50];
	183	sprintf(buf, "%s:\t%s %s", sender,
	184	(cmd == WILL ? "WILL" : cmd == WONT ? "WONT" :
	185	cmd == DO ? "DO" : cmd == DONT ? "DONT" : "<??>"),
	186	telopt(option));
	187	lognegot(buf);
	188	}
	189
	190	static void send_opt (int cmd, int option) {
	191	unsigned char b[3];
	192
	193	b[0] = IAC; b[1] = cmd; b[2] = option;
	194	s_write (b, 3);
	195	log_option("client", cmd, option);
	196	}
	197
	198	static void deactivate_option (struct Opt *o) {
	199	if (o->state == REQUESTED \|\| o->state == ACTIVE)
	200	send_opt (o->nsend, o->option);
	201	o->state = REALLY_INACTIVE;
	202	}
	203
	204	static void activate_option (struct Opt *o) {
	205	if (o->send == WILL && o->option == TELOPT_NAWS)
	206	telnet_size();
	207	if (o->send == WILL &&
	208	(o->option == TELOPT_NEW_ENVIRON \|\|
	209	o->option == TELOPT_OLD_ENVIRON)) {
	210	/*
	211	* We may only have one kind of ENVIRON going at a time.
	212	* This is a hack, but who cares.
	213	*/
	214	deactivate_option (o->option==TELOPT_NEW_ENVIRON ? &o_oenv : &o_nenv);
	215	}
	216	}
	217
	218	static void refused_option (struct Opt *o) {
	219	if (o->send == WILL && o->option == TELOPT_NEW_ENVIRON &&
	220	o_oenv.state == INACTIVE) {
	221	send_opt (WILL, TELOPT_OLD_ENVIRON);
	222	o_oenv.state = REQUESTED;
	223	}
	224	}
	225
	226	static void proc_rec_opt (int cmd, int option) {
	227	struct Opt **o;
	228
	229	log_option ("server", cmd, option);
	230	for (o = opts; *o; o++) {
	231	if ((o)->option == option && (o)->ack == cmd) {
	232	switch ((*o)->state) {
	233	case REQUESTED:
	234	(*o)->state = ACTIVE;
	235	activate_option (*o);
	236	break;
	237	case ACTIVE:
238	break;
239	case INACTIVE:
240	(*o)->state = ACTIVE;
241	send_opt ((*o)->send, option);
242	activate_option (*o);
243	break;
244	case REALLY_INACTIVE:
245	send_opt ((*o)->nsend, option);
246	break;
247	}
248	return;
249	} else if ((o)->option == option && (o)->nak == cmd) {
250	switch ((*o)->state) {
251	case REQUESTED:
252	(*o)->state = INACTIVE;
253	refused_option (*o);
254	break;
255	case ACTIVE:
256	(*o)->state = INACTIVE;
257	send_opt ((*o)->nsend, option);
258	break;
259	case INACTIVE:
260	case REALLY_INACTIVE:
261	break;
262	}
263	return;
264	}
265	}
266	/*
267	* If we reach here, the option was one we weren't prepared to
268	* cope with. So send a negative ack.
269	*/
270	send_opt ((cmd == WILL ? DONT : WONT), option);
271	}
272
273	static void process_subneg (void) {
274	unsigned char b[2048], p, q;
275	int var, value, n;
276	char *e;
277
278	switch (sb_opt) {
279	case TELOPT_TSPEED:
280	if (sb_len == 1 && sb_buf[0] == TELQUAL_SEND) {
281	char logbuf[sizeof(cfg.termspeed)+80];
282	b[0] = IAC; b[1] = SB; b[2] = TELOPT_TSPEED;
283	b[3] = TELQUAL_IS;
284	strcpy(b+4, cfg.termspeed);
285	n = 4 + strlen(cfg.termspeed);
286	b[n] = IAC; b[n+1] = SE;
287	s_write (b, n+2);
288	lognegot("server:\tSB TSPEED SEND");
289	sprintf(logbuf, "client:\tSB TSPEED IS %s", cfg.termspeed);
290	lognegot (logbuf);
291	} else
292	lognegot ("server:\tSB TSPEED <something weird>");
293	break;
294	case TELOPT_TTYPE:
295	if (sb_len == 1 && sb_buf[0] == TELQUAL_SEND) {
296	char logbuf[sizeof(cfg.termtype)+80];
297	b[0] = IAC; b[1] = SB; b[2] = TELOPT_TTYPE;
298	b[3] = TELQUAL_IS;
299	for (n = 0; cfg.termtype[n]; n++)
300	b[n+4] = (cfg.termtype[n] >= 'a' && cfg.termtype[n] <= 'z' ?
301	cfg.termtype[n] + 'A'-'a' : cfg.termtype[n]);
302	b[n+4] = IAC; b[n+5] = SE;
303	s_write (b, n+6);
304	b[n+4] = 0;
305	lognegot("server:\tSB TTYPE SEND");
306	sprintf(logbuf, "client:\tSB TTYPE IS %s", b+4);
307	lognegot(logbuf);
308	} else
309	lognegot("server:\tSB TTYPE <something weird>\r\n");
310	break;
311	case TELOPT_OLD_ENVIRON:
312	case TELOPT_NEW_ENVIRON:
313	p = sb_buf;
314	q = p + sb_len;
315	if (p < q && *p == TELQUAL_SEND) {
316	char logbuf[50];
317	p++;
318	sprintf (logbuf, "server:\tSB %s SEND", telopt(sb_opt));
319	lognegot (logbuf);
320	if (sb_opt == TELOPT_OLD_ENVIRON) {
321	if (cfg.rfc_environ) {
322	value = RFC_VALUE;
323	var = RFC_VAR;
324	} else {
325	value = BSD_VALUE;
326	var = BSD_VAR;
327	}
328	/*
329	* Try to guess the sense of VAR and VALUE.
330	*/
331	while (p < q) {
332	if (*p == RFC_VAR) {
333	value = RFC_VALUE;
334	var = RFC_VAR;
335	} else if (*p == BSD_VAR) {
336	value = BSD_VALUE;
337	var = BSD_VAR;
338	}
339	p++;
340	}
341	} else {
342	/*
343	* With NEW_ENVIRON, the sense of VAR and VALUE
344	* isn't in doubt.
345	*/
346	value = RFC_VALUE;
347	var = RFC_VAR;
348	}
349	b[0] = IAC; b[1] = SB; b[2] = sb_opt;
350	b[3] = TELQUAL_IS;
351	n = 4;
37508af4	352	e = cfg.environmt;
374330e2	353	while (*e) {
	354	b[n++] = var;
	355	while (e && e != '\t') b[n++] = *e++;
	356	if (*e == '\t') e++;
	357	b[n++] = value;
	358	while (e) b[n++] = e++;
	359	e++;
	360	}
	361	if (*cfg.username) {
	362	b[n++] = var; b[n++] = 'U'; b[n++] = 'S';
	363	b[n++] = 'E'; b[n++] = 'R'; b[n++] = value;
	364	e = cfg.username;
	365	while (e) b[n++] = e++;
	366	}
	367	b[n++] = IAC; b[n++] = SE;
	368	s_write (b, n);
	369	sprintf(logbuf, "client:\tSB %s IS %s", telopt(sb_opt),
	370	n==6 ? "<nothing>" : "<stuff>");
	371	lognegot (logbuf);
	372	}
	373	break;
	374	}
	375	}
	376
	377	static enum {
	378	TOPLEVEL, SEENIAC, SEENWILL, SEENWONT, SEENDO, SEENDONT,
	379	SEENSB, SUBNEGOT, SUBNEG_IAC, SEENCR
	380	} telnet_state = TOPLEVEL;
	381
	382	static void do_telnet_read (char *buf, int len) {
	383	unsigned char b[10];
	384
	385	while (len--) {
	386	int c = (unsigned char) *buf++;
	387
	388	switch (telnet_state) {
	389	case TOPLEVEL:
	390	case SEENCR:
	391	if (c == NUL && telnet_state == SEENCR)
	392	telnet_state = TOPLEVEL;
	393	else if (c == IAC)
	394	telnet_state = SEENIAC;
	395	else {
	396	b[0] = c;
	397	#if 0
	398	if (!in_synch)
	399	#endif
	400	c_write (b, 1);
	401	if (c == CR)
	402	telnet_state = SEENCR;
	403	else
	404	telnet_state = TOPLEVEL;
	405	}
	406	break;
	407	case SEENIAC:
	408	if (c == DO) telnet_state = SEENDO;
	409	else if (c == DONT) telnet_state = SEENDONT;
	410	else if (c == WILL) telnet_state = SEENWILL;
	411	else if (c == WONT) telnet_state = SEENWONT;
	412	else if (c == SB) telnet_state = SEENSB;
	413	else telnet_state = TOPLEVEL;/* ignore _everything_ else! */
	414	break;
	415	case SEENWILL:
	416	proc_rec_opt (WILL, c);
417	telnet_state = TOPLEVEL;
418	break;
419	case SEENWONT:
420	proc_rec_opt (WONT, c);
421	telnet_state = TOPLEVEL;
422	break;
423	case SEENDO:
424	proc_rec_opt (DO, c);
425	telnet_state = TOPLEVEL;
426	break;
427	case SEENDONT:
428	proc_rec_opt (DONT, c);
429	telnet_state = TOPLEVEL;
430	break;
431	case SEENSB:
432	sb_opt = c;
433	sb_len = 0;
434	telnet_state = SUBNEGOT;
435	break;
436	case SUBNEGOT:
437	if (c == IAC)
438	telnet_state = SUBNEG_IAC;
439	else {
440	subneg_addchar:
441	if (sb_len >= sb_size) {
442	char *newbuf;
443	sb_size += SB_DELTA;
444	newbuf = (sb_buf ?
445	realloc(sb_buf, sb_size) :
446	malloc(sb_size));
447	if (newbuf)
448	sb_buf = newbuf;
449	else
450	sb_size -= SB_DELTA;
451	}
452	if (sb_len < sb_size)
453	sb_buf[sb_len++] = c;
454	telnet_state = SUBNEGOT;/* in case we came here by goto */
455	}
456	break;
457	case SUBNEG_IAC:
458	if (c != SE)
459	goto subneg_addchar; /* yes, it's a hack, I know, but... */
460	else {
461	process_subneg();
462	telnet_state = TOPLEVEL;
463	}
464	break;
465	}
466	}
467	}
468
469	/*
470	* Called to set up the Telnet connection. Will arrange for
471	* WM_NETEVENT messages to be passed to the specified window, whose
472	* window procedure should then call telnet_msg().
473	*
474	* Returns an error message, or NULL on success.
475	*
476	* Also places the canonical host name into `realhost'.
477	*/
478	static char telnet_init (HWND hwnd, char host, int port, char **realhost) {
479	SOCKADDR_IN addr;
480	struct hostent *h;
481	unsigned long a;
482
483	/*
484	* Try to find host.
485	*/
486	if ( (a = inet_addr(host)) == (unsigned long) INADDR_NONE) {
487	if ( (h = gethostbyname(host)) == NULL)
488	switch (WSAGetLastError()) {
489	case WSAENETDOWN: return "Network is down";
490	case WSAHOST_NOT_FOUND: case WSANO_DATA:
491	return "Host does not exist";
492	case WSATRY_AGAIN: return "Host not found";
493	default: return "gethostbyname: unknown error";
494	}
495	memcpy (&a, h->h_addr, sizeof(a));
496	*realhost = h->h_name;
497	} else
498	*realhost = host;
499	a = ntohl(a);
500
501	if (port < 0)
502	port = 23; /* default telnet port */
503
504	/*
505	* Open socket.
506	*/
507	s = socket(AF_INET, SOCK_STREAM, 0);
508	if (s == INVALID_SOCKET)
509	switch (WSAGetLastError()) {
510	case WSAENETDOWN: return "Network is down";
511	case WSAEAFNOSUPPORT: return "TCP/IP support not present";
512	default: return "socket(): unknown error";
513	}
514
515	#if 0
516	{
517	BOOL b = TRUE;
518	setsockopt (s, SOL_SOCKET, SO_OOBINLINE, (void *)&b, sizeof(b));
519	}
520	#endif
521
522	/*
523	* Bind to local address.
524	*/
525	addr.sin_family = AF_INET;
526	addr.sin_addr.s_addr = htonl(INADDR_ANY);
527	addr.sin_port = htons(0);
528	if (bind (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
529	switch (WSAGetLastError()) {
530	case WSAENETDOWN: return "Network is down";
531	default: return "bind(): unknown error";
532	}
533
534	/*
535	* Connect to remote address.
536	*/
537	addr.sin_addr.s_addr = htonl(a);
538	addr.sin_port = htons((short)port);
539	if (connect (s, (struct sockaddr *)&addr, sizeof(addr)) == SOCKET_ERROR)
540	switch (WSAGetLastError()) {
541	case WSAENETDOWN: return "Network is down";
542	case WSAECONNREFUSED: return "Connection refused";
543	case WSAENETUNREACH: return "Network is unreachable";
544	case WSAEHOSTUNREACH: return "No route to host";
545	default: return "connect(): unknown error";
546	}
547
548	if (WSAAsyncSelect (s, hwnd, WM_NETEVENT, FD_READ \|
549	FD_WRITE \| FD_OOB \| FD_CLOSE) == SOCKET_ERROR)
550	switch (WSAGetLastError()) {
551	case WSAENETDOWN: return "Network is down";
552	default: return "WSAAsyncSelect(): unknown error";
553	}
554
555	/*
556	* Initialise option states.
557	*/
558	{
559	struct Opt **o;
560
561	for (o = opts; *o; o++)
562	if ((*o)->state == REQUESTED)
563	send_opt ((o)->send, (o)->option);
564	}
565
566	#if 0
567	/*
568	* Set up SYNCH state.
569	*/
570	in_synch = FALSE;
571	#endif
572
573	return NULL;
574	}
575
576	/*
577	* Process a WM_NETEVENT message. Will return 0 if the connection
578	* has closed, or <0 for a socket error.
579	*/
580	static int telnet_msg (WPARAM wParam, LPARAM lParam) {
581	int ret;
582	char buf[256];
583
584	if (s == INVALID_SOCKET) /* how the hell did we get here?! */
585	return -5000;
586
587	if (WSAGETSELECTERROR(lParam) != 0)
588	return -WSAGETSELECTERROR(lParam);
589
590	switch (WSAGETSELECTEVENT(lParam)) {
591	case FD_READ:
592	ret = recv(s, buf, sizeof(buf), 0);
593	if (ret < 0 && WSAGetLastError() == WSAEWOULDBLOCK)
594	return 1;
595	if (ret < 0) /* any _other_ error */
596	return -10000-WSAGetLastError();
597	if (ret == 0) {
598	s = INVALID_SOCKET;
599	return 0; /* can't happen, in theory */
600	}
601	#if 0
602	if (in_synch) {
603	BOOL i;
604	if (ioctlsocket (s, SIOCATMARK, &i) < 0) {
605	return -20000-WSAGetLastError();
606	}
607	if (i)
608	in_synch = FALSE;
609	}
610	#endif
611	do_telnet_read (buf, ret);
612	return 1;
613	case FD_OOB:
614	do {
615	ret = recv(s, buf, sizeof(buf), 0);
616	} while (ret > 0);
617	telnet_state = TOPLEVEL;
618	do {
619	ret = recv(s, buf, 1, MSG_OOB);
620	if (ret > 0)
621	do_telnet_read (buf, ret);
622	} while (ret > 0);
623	if (ret < 0 && WSAGetLastError() != WSAEWOULDBLOCK)
624	return -30000-WSAGetLastError();
625	return 1;
626	case FD_WRITE:
627	if (outbuf_head != outbuf_reap)
628	try_write();
629	return 1;
630	case FD_CLOSE:
631	s = INVALID_SOCKET;
632	return 0;
633	}
634	return 1; /* shouldn't happen, but WTF */
635	}
636
637	/*
638	* Called to send data down the Telnet connection.
639	*/
640	static void telnet_send (char *buf, int len) {
641	char *p;
642	static unsigned char iac[2] = { IAC, IAC };
643	static unsigned char cr[2] = { CR, NUL };
644
645	if (s == INVALID_SOCKET)
646	return;
647
648	p = buf;
649	while (p < buf+len) {
650	char *q = p;
651
652	while (iswritable((unsigned char)*p) && p < buf+len) p++;
653	s_write (q, p-q);
654
655	while (p < buf+len && !iswritable((unsigned char)*p)) {
656	s_write ((unsigned char)*p == IAC ? iac : cr, 2);
657	p++;
658	}
659	}
660	}
661
662	/*
663	* Called to set the size of the window from Telnet's POV.
664	*/
665	static void telnet_size(void) {
666	unsigned char b[16];
667	char logbuf[50];
668
669	if (s == INVALID_SOCKET \|\| o_naws.state != ACTIVE)
670	return;
671	b[0] = IAC; b[1] = SB; b[2] = TELOPT_NAWS;
672	b[3] = cols >> 8; b[4] = cols & 0xFF;
673	b[5] = rows >> 8; b[6] = rows & 0xFF;
674	b[7] = IAC; b[8] = SE;
675	s_write (b, 9);
676	sprintf(logbuf, "client:\tSB NAWS %d,%d",
677	((unsigned char)b[3] << 8) + (unsigned char)b[4],
678	((unsigned char)b[5] << 8) + (unsigned char)b[6]);
679	lognegot (logbuf);
680	}
681
682	/*
683	* Send Telnet special codes.
684	*/
685	static void telnet_special (Telnet_Special code) {
686	unsigned char b[2];
687
688	if (s == INVALID_SOCKET)
689	return;
690
691	b[0] = IAC;
692	switch (code) {
693	case TS_AYT: b[1] = AYT; s_write (b, 2); break;
694	case TS_BRK: b[1] = BREAK; s_write (b, 2); break;
695	case TS_EC: b[1] = EC; s_write (b, 2); break;
696	case TS_EL: b[1] = EL; s_write (b, 2); break;
697	case TS_GA: b[1] = GA; s_write (b, 2); break;
698	case TS_NOP: b[1] = NOP; s_write (b, 2); break;
699	case TS_ABORT: b[1] = ABORT; s_write (b, 2); break;
700	case TS_AO: b[1] = AO; s_write (b, 2); break;
701	case TS_IP: b[1] = IP; s_write (b, 2); break;
702	case TS_SUSP: b[1] = SUSP; s_write (b, 2); break;
703	case TS_EOR: b[1] = EOR; s_write (b, 2); break;
704	case TS_EOF: b[1] = xEOF; s_write (b, 2); break;
705	case TS_SYNCH:
706	outbuf_head = outbuf_reap = 0;
707	b[0] = DM;
708	send (s, b, 1, MSG_OOB);
709	break;
710	}
711	}
712
713	Backend telnet_backend = {
714	telnet_init,
715	telnet_msg,
716	telnet_send,
717	telnet_size,
718	telnet_special
719	};