int
main(int argc, char *argv[])
{
struct sockaddr_in from;
int on = 1;
socklen_t fromlen;
#ifndef REALLY_SMALL_TELNETD
register int ch;
#endif
#if defined(IPPROTO_IP) && defined(IP_TOS)
int tos = -1;
#endif
pfrontp = pbackp = ptyobuf;
netip = netibuf;
nfrontp = nbackp = netobuf;
#if defined(ENCRYPT)
nclearto = 0;
#endif
progname = *argv;
#ifdef CRAY
/*
* Get number of pty's before trying to process options,
* which may include changing pty range.
*/
highpty = getnpty();
#endif /* CRAY */
#ifndef REALLY_SMALL_TELNETD //通过Inetd启动都不定义该宏，因为0,1,2已经是accept之后的套接字
while ((ch = getopt(argc, argv, "d:a:e:lhnr:I:D:B:sS:a:X:L:")) != EOF) {
switch(ch) {
#ifdef AUTHENTICATE
case 'a':
/*
* Check for required authentication level
*/
if (strcmp(optarg, "debug") == 0) {
extern int auth_debug_mode;
auth_debug_mode = 1;
} else if (strcasecmp(optarg, "none") == 0) {
auth_level = 0;
} else if (strcasecmp(optarg, "other") == 0) {
auth_level = AUTH_OTHER;
} else if (strcasecmp(optarg, "user") == 0) {
auth_level = AUTH_USER;
} else if (strcasecmp(optarg, "valid") == 0) {
auth_level = AUTH_VALID;
} else if (strcasecmp(optarg, "off") == 0) {
/*
* This hack turns off authentication
*/
auth_level = -1;
} else {
fprintf(stderr,
"telnetd: unknown authorization level for -a\n");
}
break;
#endif /* AUTHENTICATE */
#ifdef BFTPDAEMON
case 'B':
bftpd++;
break;
#endif /* BFTPDAEMON */
case 'd':
if (strcmp(optarg, "ebug") == 0) {
debug++;
break;
}
usage();
/* NOTREACHED */
break;
#ifdef DIAGNOSTICS
case 'D':
/*
* Check for desired diagnostics capabilities.
*/
if (!strcmp(optarg, "report")) {
diagnostic |= TD_REPORT|TD_OPTIONS;
} else if (!strcmp(optarg, "exercise")) {
diagnostic |= TD_EXERCISE;
} else if (!strcmp(optarg, "netdata")) {
diagnostic |= TD_NETDATA;
} else if (!strcmp(optarg, "ptydata")) {
diagnostic |= TD_PTYDATA;
} else if (!strcmp(optarg, "options")) {
diagnostic |= TD_OPTIONS;
} else {
usage();
/* NOT REACHED */
}
break;
#endif /* DIAGNOSTICS */
#ifdef AUTHENTICATE
case 'e':
if (strcmp(optarg, "debug") == 0) {
extern int auth_debug_mode;
auth_debug_mode = 1;
break;
}
usage();
/* NOTREACHED */
break;
#endif /* AUTHENTICATE */
case 'h':
hostinfo = 0;
break;
#if defined(CRAY) && defined(NEWINIT)
case 'I':
{
extern char *gen_id;
gen_id = optarg;
break;
}
#endif /* defined(CRAY) && defined(NEWINIT) */
#ifdef LINEMODE
case 'l':
alwayslinemode = 1;
break;
#endif /* LINEMODE */
case 'L':
loginprg = optarg;
break;
case 'n':
keepalive = 0;
break;
#ifdef CRAY
case 'r':
{
char *strchr();
char *c;
/*
* Allow the specification of alterations
* to the pty search range. It is legal to
* specify only one, and not change the
* other from its default.
*/
c = strchr(optarg, '-');
if (c) {
*c++ = '\0';
highpty = atoi(c);
}
if (*optarg != '\0')
lowpty = atoi(optarg);
if ((lowpty > highpty) || (lowpty < 0) ||
(highpty > 32767)) {
usage();
/* NOT REACHED */
}
break;
}
#endif /* CRAY */
#ifdef SecurID
case 's':
/* SecurID required */
require_SecurID = 1;
break;
#endif /* SecurID */
case 'S':
#ifdef HAS_GETTOS
if ((tos = parsetos(optarg, "tcp")) < 0)
fprintf(stderr, "%s%s%s\n",
"telnetd: Bad TOS argument '", optarg,
"'; will try to use default TOS");
#else
fprintf(stderr, "%s%s\n", "TOS option unavailable; ",
"-S flag not supported\n");
#endif
break;
#ifdef AUTHENTICATE
case 'X':
/*
* Check for invalid authentication types
*/
auth_disable_name(optarg);
break;
#endif /* AUTHENTICATE */
default:
fprintf(stderr, "telnetd: %c: unknown option\n", ch);
/* FALLTHROUGH */
case '?':
usage();
/* NOTREACHED */
}
}
argc -= optind;
argv += optind;
#endif
#ifndef REALLY_SMALL_TELNETD
if (debug) {//一般都不是调试方式
int s, ns;
size_t foo;
struct servent *sp;
static struct sockaddr_in sn = { AF_INET };
if (argc > 1) {
usage();
/* NOT REACHED */
} else if (argc == 1) {
if ((sp = getservbyname(*argv, "tcp"))!=NULL) {
sn.sin_port = sp->s_port;
}
else {
sn.sin_port = atoi(*argv);
if ((int)sn.sin_port <= 0) {
fprintf(stderr, "telnetd: %s: bad port #\n", *argv);
usage();
/* NOT REACHED */
}
sn.sin_port = htons((u_short)sn.sin_port);
}
} else {
sp = getservbyname("telnet", "tcp");
if (sp == 0) {
fprintf(stderr, "telnetd: tcp/telnet: unknown service\n");
exit(1);
}
sn.sin_port = sp->s_port;
}
s = socket(AF_INET, SOCK_STREAM, 0);
if (s < 0) {
perror("telnetd: socket");;
exit(1);
}
(void) setsockopt(s, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
if (bind(s, (struct sockaddr *)&sn, sizeof(sn)) < 0) {
perror("bind");
exit(1);
}
if (listen(s, 1) < 0) {
perror("listen");
exit(1);
}
foo = sizeof(sn);
ns = accept(s, (struct sockaddr *)&sn, &foo);
if (ns < 0) {
perror("accept");
exit(1);
}
(void) dup2(ns, 0);
(void) close(ns);
(void) close(s);
#ifdef convex
} else if (argc == 1) {
; /* VOID*/ /* Just ignore the host/port name */
#endif
} else if (argc > 0) {
usage();
/* NOT REACHED */
}
#endif
#ifndef REALLY_SMALL_TELNETD
openlog("telnetd", LOG_PID | LOG_ODELAY, LOG_DAEMON);
#endif
fromlen = sizeof (from);
if (getpeername(0, (struct sockaddr *)&from, &fromlen) < 0) {//获取对端地址
fprintf(stderr, "%s: ", progname);
perror("getpeername");
// _exit(1);
}
if (keepalive &&
setsockopt(0, SOL_SOCKET, SO_KEEPALIVE, &on, sizeof (on)) < 0) {
/*syslog(LOG_WARNING, "setsockopt (SO_KEEPALIVE): %m");*/
}
#if defined(IPPROTO_IP) && defined(IP_TOS)
{
# if defined(HAS_GETTOS)
struct tosent *tp;
if (tos < 0 && (tp = gettosbyname("telnet", "tcp")))
tos = tp->t_tos;
# endif
if (tos < 0)
tos = 020; /* Low Delay bit */
if (tos
&& (setsockopt(0, IPPROTO_IP, IP_TOS, &tos, sizeof(tos)) < 0)
&& (errno != ENOPROTOOPT) )
/*syslog(LOG_WARNING, "setsockopt (IP_TOS): %m")*/;
}
#endif /* defined(IPPROTO_IP) && defined(IP_TOS) */
net = 0;//telnetd从此描述符读取网络输入
doit(&from);
/* NOTREACHED */
return 0;
}
static void
doit(struct sockaddr_in *who)
{
const char *host;
#ifndef REALLY_SMALL_TELNETD
struct hostent *hp;
#endif
int level;
char user_name[256];
/*
* Find an available pty to use.
*/
#ifndef convex
pty = getpty();//打开一个tty，用于与login子进程通信
if (pty < 0)
fatal(net, "All network ports in use");
#else
for (;;) {
char *lp;
extern char *line, *getpty();
if ((lp = getpty()) == NULL)
fatal(net, "Out of ptys");
if ((pty = open(lp, 2)) >= 0) {
strcpy(line,lp);
line[5] = 't';
break;
}
}
#endif
#ifndef REALLY_SMALL_TELNETD
/* get name of connected client */
hp = gethostbyaddr((char *)&who->sin_addr, sizeof (struct in_addr),
who->sin_family);
if (hp)
host = hp->h_name;
else
#endif
host = inet_ntoa(who->sin_addr);
#ifndef REALLY_SMALL_TELNETD
/*
* We must make a copy because Kerberos is probably going
* to also do a gethost* and overwrite the static data...
*/
strncpy(remote_host_name, host, sizeof(remote_host_name)-1);
remote_host_name[sizeof(remote_host_name)-1] = 0;
host = remote_host_name;
{
struct hostent *h;
gethostname(host_name, sizeof(host_name));
h = gethostbyname(host_name);
if (h) {
strncpy(host_name, h->h_name, sizeof(host_name));
host_name[sizeof(host_name)-1] = 0;
}
}
#endif
#if defined(AUTHENTICATE) || defined(ENCRYPT)
auth_encrypt_init(host_name, host, "TELNETD", 1);
#endif
init_env();
/*
* get terminal type.
*/
*user_name = 0;
level = getterminaltype(user_name);
#ifdef ENV
setenv("TERM", terminaltype ? terminaltype : "network", 1);
#endif
/*
* Start up the login process on the slave side of the terminal
*/
#ifndef convex
startslave(host, level, user_name);//启动login子进程
telnet(net, pty); /* begin server processing *///父进程进行处理，其实就是login子进程把它的输出重定向到pty,然后父进程从pty读取的送到net输出，父进程把用户的输入从net读入，然后写到pty，供login使用。这样久完成了用户输入用户名和密码的过程。
#else
telnet(net, pty, host);
#endif
/*NOTREACHED*/
}
void startslave(const char *host, int autologin, char *autoname)
{
int i;
#ifdef NEWINIT
extern char *ptyip;
struct init_request request;
void nologinproc();
int n;
#endif /* NEWINIT */
#if defined(AUTHENTICATE)
if (!autoname || !autoname[0]) autologin = 0;
if (autologin < auth_level) {
fatal(net, "Authorization failed");
exit(1);
}
#endif
#ifndef NEWINIT
if ((i = vfork())) {//创建子进程
if (i<0)
fatalperror(net, "fork");
/* parent */
signal(SIGHUP,SIG_IGN);
} else {
/* child */
signal(SIGHUP,SIG_IGN);
getptyslave();//子进程把pty复制到0,1,2，这样子进程的标准输入输出就是刚才的伪终端
start_login(host, autologin, autoname);//让子进程执行login程序
_exit(0);
/*NOTREACHED*/
}
#else /* NEWINIT */
/*
* Init will start up login process if we ask nicely. We only wait
* for it to start up and begin normal telnet operation.
*/
if ((i = open(INIT_FIFO, O_WRONLY)) < 0) {
char tbuf[128];
sprintf(tbuf, "Can't open %s\n", INIT_FIFO);
fatalperror(net, tbuf);
}
memset(&request, 0, sizeof(request));
request.magic = INIT_MAGIC;
SCPYN(request.gen_id, gen_id);
SCPYN(request.tty_id, &line[8]);
SCPYN(request.host, host);
SCPYN(request.term_type, terminaltype ? terminaltype : "network");
#if !defined(UNICOS5)
request.signal = SIGCLD;
request.pid = getpid();
#endif
#ifdef BFTPDAEMON
/*
* Are we working as the bftp daemon?
*/
if (bftpd) {
SCPYN(request.exec_name, BFTPPATH);
}
#endif /* BFTPDAEMON */
if (write(i, (char *)&request, sizeof(request)) < 0) {
char tbuf[128];
sprintf(tbuf, "Can't write to %s\n", INIT_FIFO);
fatalperror(net, tbuf);
}
close(i);
signal(SIGALRM, nologinproc);
for (i = 0; ; i++) {
char tbuf[128];
alarm(15);
n = read(pty, ptyip, BUFSIZ);
if (i == 3 || n >= 0 || !gotalarm) break;
gotalarm = 0;
sprintf(tbuf, "telnetd: waiting for /etc/init to start login process on %s\r\n", line);
write(net, tbuf, strlen(tbuf));
}
if (n < 0 && gotalarm) fatal(net, "/etc/init didn't start login process");
pcc += n;
alarm(0);
signal(SIGALRM, SIG_DFL);
return;
#endif /* NEWINIT */
}
static int getptyslave(void)
{
#ifdef USE_OPENPTY
struct winsize ws;
int t = ptyslavefd;
init_termbuf();
if (def_row || def_col) {
memset((char *)&ws, 0, sizeof(ws));
ws.ws_col = def_col;
ws.ws_row = def_row;
ioctl(t, TIOCSWINSZ, (char *)&ws);
}
set_termbuf();
tty_rspeed((def_rspeed > 0) ? def_rspeed : 9600);
tty_tspeed((def_tspeed > 0) ? def_tspeed : 9600);
if (login_tty(t) == -1)
fatalperror(net, "login_tty");
if (net > 2)
close(net);
if (pty > 2)
close(pty);
return t;
#else /* ! USE_OPENPTY */
register int t = -1;
#if !defined(CRAY) || !defined(NEWINIT)
# ifdef LINEMODE
int waslm;
# endif
# ifdef TIOCGWINSZ
struct winsize ws;
# endif
/*
* Opening the slave side may cause initilization of the
* kernel tty structure. We need remember the state of
* if linemode was turned on
* terminal window size
* terminal speed
* so that we can re-set them if we need to.
*/
# ifdef LINEMODE
waslm = tty_linemode();
# endif
/*
* Make sure that we don't have a controlling tty, and
* that we are the session (process group) leader.
*/
# ifdef TIOCNOTTY
t = open(_PATH_TTY, O_RDWR);
if (t >= 0) {
ioctl(t, TIOCNOTTY, (char *)0);
close(t);
}
# endif
# ifdef CRAY
/*
* Wait for our parent to get the utmp stuff to get done.
*/
utmp_sig_wait();
# endif
t = cleanopen(line);
if (t < 0) fatalperror(net, line);
/*
* set up the tty modes as we like them to be.
*/
init_termbuf();
# ifdef TIOCGWINSZ
if (def_row || def_col) {
bzero((char *)&ws, sizeof(ws));
ws.ws_col = def_col;
ws.ws_row = def_row;
ioctl(t, TIOCSWINSZ, (char *)&ws);
}
# endif
/*
* Settings for sgtty based systems
*/
# ifndef USE_TERMIO
termbuf.sg.sg_flags |= CRMOD|ANYP|ECHO|XTABS;
# endif /* USE_TERMIO */
/*
* Settings for UNICOS
*/
# ifdef CRAY
termbuf.c_oflag = OPOST|ONLCR|TAB3;
termbuf.c_iflag = IGNPAR|ISTRIP|ICRNL|IXON;
termbuf.c_lflag = ISIG|ICANON|ECHO|ECHOE|ECHOK;
termbuf.c_cflag = EXTB|HUPCL|CS8;
# endif
/*
* Settings for all other termios/termio based
* systems, other than 4.4BSD. In 4.4BSD the
* kernel does the initial terminal setup.
*/
# if defined(USE_TERMIO) && !defined(CRAY) && (BSD <= 43)
# ifndef OXTABS
# define OXTABS 0
# endif
termbuf.c_lflag |= ECHO;
termbuf.c_oflag |= ONLCR|OXTABS;
termbuf.c_iflag |= ICRNL;
termbuf.c_iflag &= ~IXOFF;
# endif /* defined(USE_TERMIO) && !defined(CRAY) && (BSD <= 43) */
tty_rspeed((def_rspeed > 0) ? def_rspeed : 9600);
tty_tspeed((def_tspeed > 0) ? def_tspeed : 9600);
# ifdef LINEMODE
if (waslm) tty_setlinemode(1);
# endif /* LINEMODE */
/*
* Set the tty modes, and make this our controlling tty.
*/
set_termbuf();
if (login_tty(t) == -1) fatalperror(net, "login_tty");//调用login_tty复制描述符到0，1,2
#endif /* !defined(CRAY) || !defined(NEWINIT) */
if (net > 2) close(net);
if (pty > 2) close(pty);
return t; /* ? was nothing here... */
#endif /* USE_OPENPTY */
}
int login_tty(int t) {
if (setsid() < 0) fatalperror(net, "setsid()");
# ifdef TIOCSCTTY
if (ioctl(t, TIOCSCTTY, (char *)0) < 0) {
fatalperror(net, "ioctl(sctty)");
}
# if defined(CRAY) && defined(SESS_CTTY) /* SESS_CTTY is in param.h */
/*
* Close the hard fd to /dev/ttypXXX, and re-open through
* the indirect /dev/tty interface.
*/
close(t);
if ((t = open("/dev/tty", O_RDWR)) < 0) {
fatalperror(net, "open(/dev/tty)");
}
# endif
# else
close(open(lyne, O_RDWR));
# endif
if (t != 0) dup2(t, 0);
if (t != 1) dup2(t, 1);
if (t != 2) dup2(t, 2);
if (t > 2) close(t);
return 0;
}
#ifndef convex
void telnet(int f, int p)
#else
void telnet(int f, int p, char *host)
#endif
{
int on = 1;
#ifdef EDIT_HOST_STUFF
char *HE;
const char *IM;
#endif
/*
* 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,
{sprintf(nfrontp, "td: simulating recv\r\n");
nfrontp += strlen(nfrontp);});
willoption(TELOPT_ECHO);
}
/*
* Finally, to clean things up, we turn on our echo. This
* will break stupid 4.2 telnets out of local terminal echo.
*/
if (my_state_is_wont(TELOPT_ECHO))
send_will(TELOPT_ECHO, 1);
/*
* Turn on packet mode
*/
ioctl(p, TIOCPKT, (char *)&on);
#if defined(LINEMODE) && defined(KLUDGELINEMODE)
/*
* Continuing line mode support. If client does not support
* real linemode, attempt to negotiate kludge linemode by sending
* the do timing mark sequence.
*/
if (lmodetype < REAL_LINEMODE)
send_do(TELOPT_TM, 1);
#endif /* defined(LINEMODE) && defined(KLUDGELINEMODE) */
/*
* Call telrcv() once to pick up anything received during
* terminal type negotiation, 4.2/4.3 determination, and
* linemode negotiation.
*/
telrcv();
ioctl(f, FIONBIO, (char *)&on);
ioctl(p, FIONBIO, (char *)&on);
#if defined(CRAY2) && defined(UNICOS5)
init_termdriver(f, p, interrupt, sendbrk);
#endif
#if defined(SO_OOBINLINE)
setsockopt(net, SOL_SOCKET, SO_OOBINLINE, &on, sizeof on);
#endif /* defined(SO_OOBINLINE) */
#ifdef SIGTSTP
signal(SIGTSTP, SIG_IGN);
#endif
#ifdef SIGTTOU
/*
* Ignoring SIGTTOU keeps the kernel from blocking us
* in ttioct() in /sys/tty.c.
*/
signal(SIGTTOU, SIG_IGN);
#endif
signal(SIGCHLD, cleanup);
#if defined(CRAY2) && defined(UNICOS5)
/*
* Cray-2 will send a signal when pty modes are changed by slave
* side. Set up signal handler now.
*/
if ((int)signal(SIGUSR1, termstat) < 0)
perror("signal");
else if (ioctl(p, TCSIGME, (char *)SIGUSR1) < 0)
perror("ioctl:TCSIGME");
/*
* Make processing loop check terminal characteristics early on.
*/
termstat();
#endif
#ifdef TIOCNOTTY
{
register int t;
t = open(_PATH_TTY, O_RDWR);
if (t >= 0) {
(void) ioctl(t, TIOCNOTTY, (char *)0);
(void) close(t);
}
}
#endif
#if defined(CRAY) && defined(NEWINIT) && defined(TIOCSCTTY)
setsid();
ioctl(p, TIOCSCTTY, 0);
#endif
/*
* Show banner that getty never gave.
*
* We put the banner in the pty input buffer. This way, it
* gets carriage return null processing, etc., just like all
* other pty --> client data.
*/
#if !defined(CRAY) || !defined(NEWINIT)
/* if (getenv("USER"))
hostinfo = 0;*/
#endif
#ifdef EDIT_HOST_STUFF
IM = DEFAULT_IM;
HE = 0;
edithost(HE, host_name);
if (hostinfo && *IM)
putf(IM, ptyibuf2);
if (pcc) strncat(ptyibuf2, ptyip, pcc+1);
#endif
ptyip = ptyibuf2;
pcc = strlen(ptyip);
#ifdef LINEMODE
/*
* Last check to make sure all our states are correct.
*/
init_termbuf();
localstat();
#endif /* LINEMODE */
DIAG(TD_REPORT,
{sprintf(nfrontp, "td: Entering processing loop\r\n");
nfrontp += strlen(nfrontp);});
#ifdef convex
startslave(host);
#endif
for (;;) {
fd_set ibits, obits, xbits;
int c, hifd;
if (ncc < 0 && pcc < 0)
break;
#if defined(CRAY2) && defined(UNICOS5)
if (needtermstat) _termstat();
#endif /* defined(CRAY2) && defined(UNICOS5) */
FD_ZERO(&ibits);
FD_ZERO(&obits);
FD_ZERO(&xbits);
hifd=0;
/*
* Never look for input if there's still
* stuff in the corresponding output buffer
*/
if (nfrontp - nbackp || pcc > 0) {
FD_SET(f, &obits);
if (f >= hifd) hifd = f+1;
}
else {
FD_SET(p, &ibits);
if (p >= hifd) hifd = p+1;
}
if (pfrontp - pbackp || ncc > 0) {
FD_SET(p, &obits);
if (p >= hifd) hifd = p+1;
}
else {
FD_SET(f, &ibits);
if (f >= hifd) hifd = f+1;
}
if (!SYNCHing) {
FD_SET(f, &xbits);
if (f >= hifd) hifd = f+1;
}
if ((c = select(hifd, &ibits, &obits, &xbits,
(struct timeval *)0)) < 1) {//在net,pty上等待输入，中转login过程
if (c == -1) {
if (errno == EINTR) {
continue;
}
}
sleep(5);
continue;
}
/*
* Any urgent data?
*/
if (FD_ISSET(net, &xbits)) {
SYNCHing = 1;
}
/*
* Something to read from the network...
*/
if (FD_ISSET(net, &ibits)) {
#if !defined(SO_OOBINLINE)
/*
* In 4.2 (and 4.3 beta) systems, the
* OOB indication and data handling in the kernel
* is such that if two separate TCP Urgent requests
* come in, one byte of TCP data will be overlaid.
* This is fatal for Telnet, but we try to live
* with it.
*
* In addition, in 4.2 (and...), a special protocol
* is needed to pick up the TCP Urgent data in
* the correct sequence.
*
* What we do is: if we think we are in urgent
* mode, we look to see if we are "at the mark".
* If we are, we do an OOB receive. If we run
* this twice, we will do the OOB receive twice,
* but the second will fail, since the second
* time we were "at the mark", but there wasn't
* any data there (the kernel doesn't reset
* "at the mark" until we do a normal read).
* Once we've read the OOB data, we go ahead
* and do normal reads.
*
* There is also another problem, which is that
* since the OOB byte we read doesn't put us
* out of OOB state, and since that byte is most
* likely the TELNET DM (data mark), we would
* stay in the TELNET SYNCH (SYNCHing) state.
* So, clocks to the rescue. If we've "just"
* received a DM, then we test for the
* presence of OOB data when the receive OOB
* fails (and AFTER we did the normal mode read
* to clear "at the mark").
*/
if (SYNCHing) {
int atmark;
ioctl(net, SIOCATMARK, (char *)&atmark);
if (atmark) {
ncc = recv(net, netibuf, sizeof (netibuf), MSG_OOB);
if ((ncc == -1) && (errno == EINVAL)) {
ncc = read(net, netibuf, sizeof (netibuf));
if (sequenceIs(didnetreceive, gotDM)) {
SYNCHing = stilloob(net);
}
}
}
else {
ncc = read(net, netibuf, sizeof (netibuf));
}
}
else {
ncc = read(net, netibuf, sizeof (netibuf));
}
settimer(didnetreceive);
#else /* !defined(SO_OOBINLINE)) */
ncc = read(net, netibuf, sizeof (netibuf));
#endif /* !defined(SO_OOBINLINE)) */
if (ncc < 0 && errno == EWOULDBLOCK)
ncc = 0;
else {
if (ncc <= 0) {
break;
}
netip = netibuf;
}
DIAG((TD_REPORT | TD_NETDATA),
{sprintf(nfrontp, "td: netread %d chars\r\n", ncc);
nfrontp += strlen(nfrontp);});
DIAG(TD_NETDATA, printdata("nd", netip, ncc));
}
/*
* Something to read from the pty...
*/
if (FD_ISSET(p, &ibits)) {
pcc = read(p, ptyibuf, BUFSIZ);
/*
* On some systems, if we try to read something
* off the master side before the slave side is
* opened, we get EIO.
*/
if (pcc < 0 && (errno == EWOULDBLOCK || errno == EIO)) {
pcc = 0;
}
else {
if (pcc <= 0)
break;
#if !defined(CRAY2) || !defined(UNICOS5)
#ifdef LINEMODE
/*
* If ioctl from pty, pass it through net
*/
if (ptyibuf[0] & TIOCPKT_IOCTL) {
copy_termbuf(ptyibuf+1, pcc-1);
localstat();
pcc = 1;
}
#endif /* LINEMODE */
if (ptyibuf[0] & TIOCPKT_FLUSHWRITE) {
netclear(); /* clear buffer back */
#ifndef NO_URGENT
/*
* There are client telnets on some
* operating systems get screwed up
* royally if we send them urgent
* mode data.
*/
*nfrontp++ = IAC;
*nfrontp++ = DM;
neturg = nfrontp-1; /* off by one XXX */
#endif
}
if (his_state_is_will(TELOPT_LFLOW) &&
(ptyibuf[0] &
(TIOCPKT_NOSTOP|TIOCPKT_DOSTOP))) {
(void) sprintf(nfrontp, "%c%c%c%c%c%c",
IAC, SB, TELOPT_LFLOW,
ptyibuf[0] & TIOCPKT_DOSTOP ? 1 : 0,
IAC, SE);
nfrontp += 6;
}
pcc--;
ptyip = ptyibuf+1;
#else /* defined(CRAY2) && defined(UNICOS5) */
if (!uselinemode) {
unpcc = pcc;
unptyip = ptyibuf;
pcc = term_output(&unptyip, ptyibuf2,
&unpcc, BUFSIZ);
ptyip = ptyibuf2;
}
else ptyip = ptyibuf;
#endif /* defined(CRAY2) && defined(UNICOS5) */
}
}
while (pcc > 0) {
if ((&netobuf[BUFSIZ] - nfrontp) < 2)
break;
c = *ptyip++ & 0377, pcc--;
if (c == IAC)
*nfrontp++ = c;
#if defined(CRAY2) && defined(UNICOS5)
else if (c == '\n' &&
my_state_is_wont(TELOPT_BINARY) && newmap)
*nfrontp++ = '\r';
#endif /* defined(CRAY2) && defined(UNICOS5) */
*nfrontp++ = c;
if ((c == '\r' ) && (my_state_is_wont(TELOPT_BINARY))) {
if (pcc > 0 && ((*ptyip & 0377) == '\n')) {
*nfrontp++ = *ptyip++ & 0377;
pcc--;
}
else *nfrontp++ = '\0';
}
}
#if defined(CRAY2) && defined(UNICOS5)
/*
* If chars were left over from the terminal driver,
* note their existence.
*/
if (!uselinemode && unpcc) {
pcc = unpcc;
unpcc = 0;
ptyip = unptyip;
}
#endif /* defined(CRAY2) && defined(UNICOS5) */
if (FD_ISSET(f, &obits) && (nfrontp - nbackp) > 0)
netflush();
if (ncc > 0)
telrcv();
if (FD_ISSET(p, &obits) && (pfrontp - pbackp) > 0)
ptyflush();
}
cleanup(0);
}
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