ref: dc593372bfc4224c6cf91d2031d0ad0aeadaddfe
dir: /sys/src/cmd/ip/telnet.c/
#include <u.h>
#include <libc.h>
#include <bio.h>
#include "telnet.h"
int ctl = -1; /* control fd (for break's) */
int consctl = -1; /* consctl fd */
int ttypid; /* pid's if the 2 processes (used to kill them) */
int netpid;
int interrupted;
int localecho;
int notkbd;
int returns;
int stopped;
static char *srv;
int dodial(char*);
void fromkbd(int);
void fromnet(int);
int menu(Biobuf*, int);
void notifyf(void*, char*);
void rawoff(void);
void rawon(void);
void telnet(int);
char* system(int, char*);
int echochange(Biobuf*, int);
int termsub(Biobuf*, uchar*, int);
int xlocsub(Biobuf*, uchar*, int);
static int islikeatty(int);
void
usage(void)
{
fatal("usage: telnet [-Cdnr] [-s srv] net!host[!service]", 0, 0);
}
void
main(int argc, char *argv[])
{
returns = 1;
ARGBEGIN{
case 'C':
opt[Echo].noway = 1;
break;
case 'd':
debug = 1;
break;
case 'n':
notkbd = 1;
break;
case 'r':
returns = 0;
break;
case 's':
srv = EARGF(usage());
break;
default:
usage();
}ARGEND
if(argc != 1)
usage();
/* options we need routines for */
opt[Echo].change = echochange;
opt[Term].sub = termsub;
opt[Xloc].sub = xlocsub;
telnet(dodial(argv[0]));
}
/*
* dial and return a data connection
*/
int
dodial(char *dest)
{
char *name;
int data;
char devdir[NETPATHLEN];
name = netmkaddr(dest, "tcp", "telnet");
data = dial(name, 0, devdir, 0);
if(data < 0)
fatal("%s: %r", name, 0);
if(srv != nil){
if(rfork(RFPROC | RFNOWAIT | RFNOTEG) != 0)
exits("");
}
else
fprint(2, "connected to %s on %s\n", name, devdir);
return data;
}
void
post(char *srv, int fd)
{
int f;
char buf[32];
f = create(srv, OWRITE, 0666);
if(f < 0)
sysfatal("create %s: %r", srv);
snprint(buf, sizeof buf, "%d", fd);
if(write(f, buf, strlen(buf)) != strlen(buf))
sysfatal("write %s: %r", srv);
close(f);
}
/*
* two processes pass bytes back and forth between the
* terminal and the network.
*/
void
telnet(int net)
{
int pid;
int p[2];
char *svc;
rawoff();
svc = nil;
if (srv) {
if(pipe(p) < 0)
sysfatal("pipe: %r");
if (srv[0] != '/')
svc = smprint("/srv/%s", srv);
else
svc = srv;
post(svc, p[0]);
close(p[0]);
dup(p[1], 0);
dup(p[1], 1);
/* pipe is now std in & out */
}
ttypid = getpid();
switch(pid = rfork(RFPROC|RFFDG|RFMEM)){
case -1:
perror("con");
exits("fork");
case 0:
rawoff();
notify(notifyf);
fromnet(net);
if (svc)
remove(svc);
sendnote(ttypid, "die");
exits(0);
default:
netpid = pid;
notify(notifyf);
fromkbd(net);
if (notkbd)
while(waitpid() != pid)
sleep(0);
if (svc)
remove(svc);
sendnote(netpid, "die");
exits(0);
}
}
/*
* Read the keyboard and write it to the network. '^\' gets us into
* the menu.
*/
void
fromkbd(int net)
{
Biobuf ib, ob;
int c, likeatty;
int eofs;
Binit(&ib, 0, OREAD);
Binit(&ob, net, OWRITE);
likeatty = islikeatty(0);
eofs = 0;
for(;;){
c = Bgetc(&ib);
/*
* with raw off, all ^D's get turned into Eof's.
* change them back.
* 10 in a row implies that the terminal is really gone so
* just hang up.
*/
if(c < 0){
if(notkbd)
return;
if(eofs++ > 10)
return;
c = 004;
} else
eofs = 0;
/*
* if not in binary mode, look for the ^\ escape to menu.
* also turn \n into \r\n
*/
if(likeatty || !opt[Binary].local){
if(c == 0034){ /* CTRL \ */
if(Bflush(&ob) < 0)
return;
if(menu(&ib, net) < 0)
return;
continue;
}
}
if(!opt[Binary].local){
if(c == '\n'){
/*
* This is a very strange use of the SGA option.
* I did this because some systems that don't
* announce a willingness to supress-go-ahead
* need the \r\n sequence to recognize input.
* If someone can explain this to me, please
* send me mail. - presotto
*/
if(opt[SGA].remote){
c = '\r';
} else {
if(Bputc(&ob, '\r') < 0)
return;
}
}
}
if(Bputc(&ob, c) < 0)
return;
if(Bbuffered(&ib) == 0)
if(Bflush(&ob) < 0)
return;
}
}
/*
* Read from the network and write to the screen. If 'stopped' is set
* spin and don't read. Filter out spurious carriage returns.
*/
void
fromnet(int net)
{
int c;
int crnls = 0, freenl = 0, eofs;
Biobuf ib, ob;
Binit(&ib, net, OREAD);
Binit(&ob, 1, OWRITE);
eofs = 0;
for(;;){
if(Bbuffered(&ib) == 0)
Bflush(&ob);
if(interrupted){
interrupted = 0;
send2(net, Iac, Interrupt);
}
c = Bgetc(&ib);
if(c < 0){
if(eofs++ >= 2)
return;
continue;
}
eofs = 0;
switch(c){
case '\n': /* skip nl after string of cr's */
if(!opt[Binary].local && !returns){
++crnls;
if(freenl == 0)
break;
freenl = 0;
continue;
}
break;
case '\r': /* first cr becomes nl, remainder dropped */
if(!opt[Binary].local && !returns){
if(crnls++ == 0){
freenl = 1;
c = '\n';
break;
}
continue;
}
break;
case 0: /* remove nulls from crnl string */
if(crnls)
continue;
break;
case Iac:
crnls = 0;
freenl = 0;
c = Bgetc(&ib);
if(c == Iac)
break;
if(Bflush(&ob) < 0)
return;
if(control(&ib, c) < 0)
return;
continue;
default:
crnls = 0;
freenl = 0;
break;
}
if(Bputc(&ob, c) < 0)
return;
}
}
void
consctlcmd(char *s)
{
if(srv != nil || notkbd)
return;
if(debug)
fprint(2, "consctl: %s\n", s);
if(consctl < 0)
consctl = open("/dev/consctl", OWRITE);
if(consctl < 0){
fprint(2, "can't open consctl: %r\n");
return;
}
write(consctl, s, strlen(s));
}
/*
* turn keyboard raw mode on
*/
void
rawon(void)
{
consctlcmd("rawon");
}
/*
* turn keyboard raw mode off
*/
void
rawoff(void)
{
consctlcmd("rawoff");
}
/*
* control menu
*/
#define STDHELP "\t(b)reak, (i)nterrupt, (q)uit, (r)eturns, (!cmd), (.)continue\n"
int
menu(Biobuf *bp, int net)
{
char *cp;
int done;
stopped = 1;
rawoff();
fprint(2, ">>> ");
for(done = 0; !done; ){
cp = Brdline(bp, '\n');
if(cp == 0){
stopped = 0;
return -1;
}
cp[Blinelen(bp)-1] = 0;
switch(*cp){
case '!':
system(Bfildes(bp), cp+1);
done = 1;
break;
case '.':
done = 1;
break;
case 'q':
stopped = 0;
return -1;
case 'o':
switch(*(cp+1)){
case 'd':
send3(net, Iac, Do, atoi(cp+2));
break;
case 'w':
send3(net, Iac, Will, atoi(cp+2));
break;
}
break;
case 'r':
returns = !returns;
done = 1;
break;
case 'i':
send2(net, Iac, Interrupt);
break;
case 'b':
send2(net, Iac, Break);
break;
default:
fprint(2, STDHELP);
break;
}
if(!done)
fprint(2, ">>> ");
}
rawon();
stopped = 0;
return 0;
}
/*
* ignore interrupts
*/
void
notifyf(void *a, char *msg)
{
USED(a);
if(strcmp(msg, "interrupt") == 0){
interrupted = 1;
noted(NCONT);
}
if(strcmp(msg, "hangup") == 0)
noted(NCONT);
noted(NDFLT);
}
/*
* run a command with the network connection as standard IO
*/
char *
system(int fd, char *cmd)
{
int pid;
int p;
static Waitmsg msg;
if((pid = fork()) == -1){
perror("con");
return "fork failed";
}
else if(pid == 0){
dup(fd, 0);
close(ctl);
close(fd);
if(*cmd)
execl("/bin/rc", "rc", "-c", cmd, nil);
else
execl("/bin/rc", "rc", nil);
perror("con");
exits("exec");
}
for(p = waitpid(); p >= 0; p = waitpid()){
if(p == pid)
return msg.msg;
}
return "lost child";
}
/*
* suppress local echo if the remote side is doing it
*/
int
echochange(Biobuf *bp, int cmd)
{
USED(bp);
switch(cmd){
case Will:
rawon();
break;
case Wont:
rawoff();
break;
}
return 0;
}
/*
* send terminal type to the other side
*/
int
termsub(Biobuf *bp, uchar *sub, int n)
{
char buf[64];
char *term;
char *p = buf;
if(n < 1)
return 0;
if(sub[0] == 1){
*p++ = Iac;
*p++ = Sb;
*p++ = opt[Term].code;
*p++ = 0;
term = getenv("TERM");
if(term == 0 || *term == 0)
term = "p9win";
strncpy(p, term, sizeof(buf) - (p - buf) - 2);
buf[sizeof(buf)-2] = 0;
p += strlen(p);
*p++ = Iac;
*p++ = Se;
return iwrite(Bfildes(bp), buf, p-buf);
}
return 0;
}
/*
* send an x display location to the other side
*/
int
xlocsub(Biobuf *bp, uchar *sub, int n)
{
char buf[64];
char *term;
char *p = buf;
if(n < 1)
return 0;
if(sub[0] == 1){
*p++ = Iac;
*p++ = Sb;
*p++ = opt[Xloc].code;
*p++ = 0;
term = getenv("XDISP");
if(term == 0 || *term == 0)
term = "unknown";
strncpy(p, term, p - buf - 2);
p += strlen(term);
*p++ = Iac;
*p++ = Se;
return iwrite(Bfildes(bp), buf, p-buf);
}
return 0;
}
static int
islikeatty(int fd)
{
char buf[64];
if(fd2path(fd, buf, sizeof buf) != 0)
return 0;
/* might be /mnt/term/dev/cons */
return strlen(buf) >= 9 && strcmp(buf+strlen(buf)-9, "/dev/cons") == 0;
}