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TELNET.C
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C/C++ Source or Header
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1992-06-03
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9KB
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403 lines
/* Internet Telnet client
* Copyright 1991 Phil Karn, KA9Q
*/
#include <stdio.h>
#ifdef __TURBOC__
#include <io.h>
#include <fcntl.h>
#endif
#include "global.h"
#include "mbuf.h"
#include "socket.h"
#include "telnet.h"
#include "session.h"
#include "proc.h"
#include "tty.h"
#include "commands.h"
#include "internet.h"
#include "netuser.h"
int Refuse_echo = 0;
int Tn_cr_mode = 0; /* if true turn <cr> to <cr-nul> */
#ifdef DEBUG
char *T_options[] = {
"Transmit Binary",
"Echo",
"",
"Suppress Go Ahead",
"",
"Status",
"Timing Mark"
};
#endif
/* Execute user telnet command */
int
dotelnet(argc,argv,p)
int argc;
char *argv[];
void *p;
{
struct session *sp;
struct sockaddr_in fsocket;
int s;
/* Allocate a session descriptor */
if((sp = newsession(argv[1],TELNET,1)) == NULLSESSION){
printf("Too many sessions\n");
return 1;
}
fsocket.sin_family = AF_INET;
if(argc < 3)
fsocket.sin_port = IPPORT_TELNET;
else
fsocket.sin_port = atoi(argv[2]);
printf("Resolving %s... ",sp->name);
if((fsocket.sin_addr.s_addr = resolve(sp->name)) == 0){
printf(Badhost,sp->name);
keywait(NULLCHAR,1);
freesession(sp);
return 1;
}
if((s = socket(AF_INET,SOCK_STREAM,0)) == -1){
printf("Can't create socket\n");
keywait(NULLCHAR,1);
freesession(sp);
return 1;
}
settos(s,LOW_DELAY);
sp->network = fdopen(s,"r+t");
setvbuf(sp->network,NULLCHAR,_IOLBF,BUFSIZ);
return tel_connect(sp,(char *)&fsocket,SOCKSIZE);
}
/* Generic interactive connect routine, used by Telnet, AX.25, NET/ROM */
int
tel_connect(sp,fsocket,len)
struct session *sp;
char *fsocket;
int len;
{
struct telnet tn;
memset((char *)&tn,0,sizeof(tn));
tn.eolmode = Tn_cr_mode;
tn.session = sp; /* Upward pointer */
sp->cb.telnet = &tn; /* Downward pointer */
printf("Trying %s...\n",psocket((struct sockaddr *)fsocket));
if(connect(fileno(sp->network),fsocket,len) == -1){
printf("%s session %u ",Sestypes[sp->type], sp->index);
perror("connect failed");
keywait(NULLCHAR,1);
freesession(sp);
return 1;
}
printf("%s session ",Sestypes[sp->type]);
printf("%u connected to %s\n",sp->index,sp->name);
tnrecv(&tn);
return 0;
}
/* Telnet input routine, common to both telnet and ttylink */
void
tnrecv(tn)
struct telnet *tn;
{
int c;
struct session *sp;
char *cp;
FILE *network;
sp = tn->session;
network = sp->network;
/* Fork off the transmit process */
sp->proc1 = newproc("tel_out",1024,tel_output,0,tn,NULL,0);
/* Process input on the connection */
while((c = getc(network)) != EOF){
if(c != IAC){
/* Ordinary character */
if(!tn->remote[TN_TRANSMIT_BINARY])
c &= 0x7f;
putchar((char)c);
continue;
}
/* IAC received, get command sequence */
c = getc(network);
switch(c){
case WILL:
c = getc(network);
willopt(tn,c);
break;
case WONT:
c = getc(network);
wontopt(tn,c);
break;
case DO:
c = getc(network);
doopt(tn,c);
break;
case DONT:
c = getc(network);
dontopt(tn,c);
break;
case IAC: /* Escaped IAC */
putchar(IAC);
break;
}
}
quit: /* A close was received from the remote host.
* Notify the user, kill the output task and wait for a response
* from the user before freeing the session.
*/
log(-1,"out of telnet receive loop");
fmode(sp->output,STREAM_ASCII); /* Restore newline translation */
setvbuf(sp->output,NULLCHAR,_IOLBF,BUFSIZ);
cp = sockerr(fileno(network));
printf("%s session %u", Sestypes[sp->type],sp->index);
printf(" closed: %s\n", cp != NULLCHAR ? cp : "EOF");
log(-1,"telnet did closing printf");
killproc(sp->proc1);
sp->proc1 = NULLPROC;
log(-1,"telnet killed sender");
fclose(sp->network);
sp->network = NULLFILE;
log(-1,"telnet closed network");
keywait(NULLCHAR,1);
freesession(sp);
}
/* User telnet output task, started by user telnet command */
void
tel_output(unused,tn1,p)
int unused;
void *tn1;
void *p;
{
struct session *sp;
int c;
struct telnet *tn;
tn = (struct telnet *)tn1;
sp = tn->session;
/* Send whatever's typed on the terminal */
while((c = getc(sp->input)) != EOF){
putc(c,sp->network);
if(!tn->remote[TN_ECHO] && sp->record != NULLFILE)
putc(c,sp->record);
/* By default, output is transparent in remote echo mode.
* If eolmode is set, turn a cr into cr-null.
* This can only happen when in remote echo (raw) mode, since
* the tty driver normally maps \r to \n in cooked mode.
*/
if(c == '\r' && tn->eolmode)
putc('\0',sp->network);
if(tn->remote[TN_ECHO])
fflush(sp->network);
}
/* Make sure our parent doesn't try to kill us after we exit */
sp->proc1 = NULLPROC;
}
int
doecho(argc,argv,p)
int argc;
char *argv[];
void *p;
{
if(argc < 2){
if(Refuse_echo)
printf("Refuse\n");
else
printf("Accept\n");
} else {
if(argv[1][0] == 'r')
Refuse_echo = 1;
else if(argv[1][0] == 'a')
Refuse_echo = 0;
else
return -1;
}
return 0;
}
/* set for unix end of line for remote echo mode telnet */
int
doeol(argc,argv,p)
int argc;
char *argv[];
void *p;
{
if(argc < 2){
if(Tn_cr_mode)
printf("null\n");
else
printf("standard\n");
} else {
if(argv[1][0] == 'n')
Tn_cr_mode = 1;
else if(argv[1][0] == 's')
Tn_cr_mode = 0;
else {
printf("Usage: %s [standard|null]\n",argv[0]);
return -1;
}
}
return 0;
}
/* The guts of the actual Telnet protocol: negotiating options */
void
willopt(tn,opt)
struct telnet *tn;
int opt;
{
int ack;
#ifdef DEBUG
printf("recv: will ");
if(uchar(opt) <= NOPTIONS)
printf("%s\n",T_options[opt]);
else
printf("%u\n",opt);
#endif
switch(uchar(opt)){
case TN_TRANSMIT_BINARY:
case TN_ECHO:
case TN_SUPPRESS_GA:
if(tn->remote[uchar(opt)] == 1)
return; /* Already set, ignore to prevent loop */
if(uchar(opt) == TN_ECHO){
if(Refuse_echo){
/* User doesn't want to accept */
ack = DONT;
break;
} else {
/* Put tty into raw mode */
tn->session->ttystate.edit = 0;
tn->session->ttystate.echo = 0;
fmode(tn->session->network,STREAM_BINARY);
setvbuf(tn->session->network,NULLCHAR,_IONBF,0);
fmode(stdout,STREAM_BINARY);
setvbuf(stdout,NULLCHAR,_IONBF,0);
}
}
tn->remote[uchar(opt)] = 1;
ack = DO;
break;
default:
ack = DONT; /* We don't know what he's offering; refuse */
}
answer(tn,ack,opt);
}
void
wontopt(tn,opt)
struct telnet *tn;
int opt;
{
#ifdef DEBUG
printf("recv: wont ");
if(uchar(opt) <= NOPTIONS)
printf("%s\n",T_options[uchar(opt)]);
else
printf("%u\n",uchar(opt));
#endif
if(uchar(opt) <= NOPTIONS){
if(tn->remote[uchar(opt)] == 0)
return; /* Already clear, ignore to prevent loop */
tn->remote[uchar(opt)] = 0;
if(uchar(opt) == TN_ECHO){
/* Put tty into cooked mode */
tn->session->ttystate.edit = 1;
tn->session->ttystate.echo = 1;
fmode(tn->session->network,STREAM_ASCII);
setvbuf(tn->session->network,NULLCHAR,_IOLBF,BUFSIZ);
fmode(stdout,STREAM_ASCII);
setvbuf(stdout,NULLCHAR,_IOLBF,BUFSIZ);
}
}
answer(tn,DONT,opt); /* Must always accept */
}
void
doopt(tn,opt)
struct telnet *tn;
int opt;
{
int ack;
#ifdef DEBUG
printf("recv: do ");
if(uchar(opt) <= NOPTIONS)
printf("%s\n",T_options[uchar(opt)]);
else
printf("%u\n",uchar(opt));
#endif
switch(uchar(opt)){
case TN_SUPPRESS_GA:
if(tn->local[uchar(opt)] == 1)
return; /* Already set, ignore to prevent loop */
tn->local[uchar(opt)] = 1;
ack = WILL;
break;
default:
ack = WONT; /* Don't know what it is */
}
answer(tn,ack,opt);
}
void
dontopt(tn,opt)
struct telnet *tn;
int opt;
{
#ifdef DEBUG
printf("recv: dont ");
if(uchar(opt) <= NOPTIONS)
printf("%s\n",T_options[uchar(opt)]);
else
printf("%u\n",uchar(opt));
#endif
if(uchar(opt) <= NOPTIONS){
if(tn->local[uchar(opt)] == 0){
/* Already clear, ignore to prevent loop */
return;
}
tn->local[uchar(opt)] = 0;
}
answer(tn,WONT,opt);
}
void
answer(tn,r1,r2)
struct telnet *tn;
int r1,r2;
{
#ifdef DEBUG
switch(r1){
case WILL:
printf("sent: will ");
break;
case WONT:
printf("sent: wont ");
break;
case DO:
printf("sent: do ");
break;
case DONT:
printf("sent: dont ");
break;
}
if(r2 <= NOPTIONS)
printf("%s\n",T_options[r2]);
else
printf("%u\n",r2);
#endif
fprintf(tn->session->network,"%c%c%c",IAC,r1,r2);
fflush(tn->session->network);
}