blob: b4d5c72f228e4560770b9c1b3e799dbfe5a8decc [file] [log] [blame]
/* telnet.c - Telnet client.
*
* Copyright 2012 Madhur Verma <mad.flexi@gmail.com>
* Copyright 2013 Kyungwan Han <asura321@gmail.com>
* Modified by Ashwini Kumar <ak.ashwini1981@gmail.com>
*
* Not in SUSv4.
USE_TELNET(NEWTOY(telnet, "<1>2", TOYFLAG_BIN))
config TELNET
bool "telnet"
default n
help
usage: telnet HOST [PORT]
Connect to telnet server
*/
#define FOR_telnet
#include "toys.h"
#include <arpa/telnet.h>
#include <netinet/in.h>
GLOBALS(
int port;
int sfd;
char buff[128];
int pbuff;
char iac[256];
int piac;
char *ttype;
struct termios def_term;
struct termios raw_term;
uint8_t term_ok;
uint8_t term_mode;
uint8_t flags;
unsigned win_width;
unsigned win_height;
)
#define DATABUFSIZE 128
#define IACBUFSIZE 256
#define CM_TRY 0
#define CM_ON 1
#define CM_OFF 2
#define UF_ECHO 0x01
#define UF_SGA 0x02
// sets terminal mode: LINE or CHARACTER based om internal stat.
static char const es[] = "\r\nEscape character is ";
static void set_mode(void)
{
if (TT.flags & UF_ECHO) {
if (TT.term_mode == CM_TRY) {
TT.term_mode = CM_ON;
printf("\r\nEntering character mode%s'^]'.\r\n", es);
if (TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.raw_term);
}
} else {
if (TT.term_mode != CM_OFF) {
TT.term_mode = CM_OFF;
printf("\r\nEntering line mode%s'^C'.\r\n", es);
if (TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term);
}
}
}
// flushes all data in IAC buff to server.
static void flush_iac(void)
{
int wlen = write(TT.sfd, TT.iac, TT.piac);
if(wlen <= 0) error_msg("IAC : send failed.");
TT.piac = 0;
}
// puts DATA in iac buff of length LEN and updates iac buff pointer.
static void put_iac(int len, ...)
{
va_list va;
if(TT.piac + len >= IACBUFSIZE) flush_iac();
va_start(va, len);
for(;len > 0; TT.iac[TT.piac++] = (uint8_t)va_arg(va, int), len--);
va_end(va);
}
// puts string STR in iac buff and updates iac buff pointer.
static void str_iac(char *str)
{
int len = strlen(str);
if(TT.piac + len + 1 >= IACBUFSIZE) flush_iac();
strcpy(&TT.iac[TT.piac], str);
TT.piac += len+1;
}
static void handle_esc(void)
{
char input;
if(toys.signal && TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.raw_term);
xwrite(1,"\r\nConsole escape. Commands are:\r\n\n"
" l go to line mode\r\n"
" c go to character mode\r\n"
" z suspend telnet\r\n"
" e exit telnet\r\n", 114);
if (read(0, &input, 1) <= 0) {
if(TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term);
exit(0);
}
switch (input) {
case 'l':
if (!toys.signal) {
TT.term_mode = CM_TRY;
TT.flags &= ~(UF_ECHO | UF_SGA);
set_mode();
put_iac(6, IAC,DONT,TELOPT_ECHO,IAC,DONT, TELOPT_SGA);
flush_iac();
goto ret;
}
break;
case 'c':
if (toys.signal) {
TT.term_mode = CM_TRY;
TT.flags |= (UF_ECHO | UF_SGA);
set_mode();
put_iac(6, IAC,DO,TELOPT_ECHO,IAC,DO,TELOPT_SGA);
flush_iac();
goto ret;
}
break;
case 'z':
if(TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term);
kill(0, SIGTSTP);
if(TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.raw_term);
break;
case 'e':
if(TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term);
exit(0);
default: break;
}
xwrite(1, "continuing...\r\n", 15);
if (toys.signal && TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term);
ret:
toys.signal = 0;
}
/*
* handles telnet SUB NEGOTIATIONS
* only terminal type is supported.
*/
static void handle_negotiations(void)
{
char opt = TT.buff[TT.pbuff++];
switch(opt) {
case TELOPT_TTYPE:
opt = TT.buff[TT.pbuff++];
if(opt == TELQUAL_SEND) {
put_iac(4, IAC,SB,TELOPT_TTYPE,TELQUAL_IS);
str_iac(TT.ttype);
put_iac(2, IAC,SE);
}
break;
default: break;
}
}
/*
* handles server's DO DONT WILL WONT requests.
* supports ECHO, SGA, TTYPE, NAWS
*/
static void handle_ddww(char ddww)
{
char opt = TT.buff[TT.pbuff++];
switch (opt) {
case TELOPT_ECHO: /* ECHO */
if (ddww == DO) put_iac(3, IAC,WONT,TELOPT_ECHO);
if(ddww == DONT) break;
if (TT.flags & UF_ECHO) {
if (ddww == WILL) return;
} else if (ddww == WONT) return;
if (TT.term_mode != CM_OFF) TT.flags ^= UF_ECHO;
(TT.flags & UF_ECHO)? put_iac(3, IAC,DO,TELOPT_ECHO) :
put_iac(3, IAC,DONT,TELOPT_ECHO);
set_mode();
printf("\r\n");
break;
case TELOPT_SGA: /* Supress GO Ahead */
if (TT.flags & UF_SGA){ if (ddww == WILL) return;
} else if (ddww == WONT) return;
TT.flags ^= UF_SGA;
(TT.flags & UF_SGA)? put_iac(3, IAC,DO,TELOPT_SGA) :
put_iac(3, IAC,DONT,TELOPT_SGA);
break;
case TELOPT_TTYPE: /* Terminal Type */
(TT.ttype)? put_iac(3, IAC,WILL,TELOPT_TTYPE):
put_iac(3, IAC,WONT,TELOPT_TTYPE);
break;
case TELOPT_NAWS: /* Window Size */
put_iac(3, IAC,WILL,TELOPT_NAWS);
put_iac(9, IAC,SB,TELOPT_NAWS,(TT.win_width >> 8) & 0xff,
TT.win_width & 0xff,(TT.win_height >> 8) & 0xff,
TT.win_height & 0xff,IAC,SE);
break;
default: /* Default behaviour is to say NO */
if(ddww == WILL) put_iac(3, IAC,DONT,opt);
if(ddww == DO) put_iac(3, IAC,WONT,opt);
break;
}
}
/*
* parses data which is read from server of length LEN.
* and passes it to console.
*/
static int read_server(int len)
{
int i = 0;
char curr;
TT.pbuff = 0;
do {
curr = TT.buff[TT.pbuff++];
if (curr == IAC) {
curr = TT.buff[TT.pbuff++];
switch (curr) {
case DO: /* FALLTHROUGH */
case DONT: /* FALLTHROUGH */
case WILL: /* FALLTHROUGH */
case WONT:
handle_ddww(curr);
break;
case SB:
handle_negotiations();
break;
case SE:
break;
default: break;
}
} else {
toybuf[i++] = curr;
if (curr == '\r') { curr = TT.buff[TT.pbuff++];
if (curr != '\0') TT.pbuff--;
}
}
} while (TT.pbuff < len);
if (i) xwrite(0, toybuf, i);
return 0;
}
/*
* parses data which is read from console of length LEN
* and passes it to server.
*/
static void write_server(int len)
{
char *c = (char*)TT.buff;
int i = 0;
for (; len > 0; len--, c++) {
if (*c == 0x1d) {
handle_esc();
return;
}
toybuf[i++] = *c;
if (*c == IAC) toybuf[i++] = *c; /* IAC -> IAC IAC */
else if (*c == '\r') toybuf[i++] = '\0'; /* CR -> CR NUL */
}
if(i) xwrite(TT.sfd, toybuf, i);
}
void telnet_main(void)
{
char *port = "23";
int set = 1, len;
struct pollfd pfds[2];
TT.win_width = 80; //columns
TT.win_height = 24; //rows
if (toys.optc == 2) port = toys.optargs[1];
TT.ttype = getenv("TERM");
if(!TT.ttype) TT.ttype = "";
if(strlen(TT.ttype) > IACBUFSIZE-1) TT.ttype[IACBUFSIZE - 1] = '\0';
if (!tcgetattr(0, &TT.def_term)) {
TT.term_ok = 1;
TT.raw_term = TT.def_term;
cfmakeraw(&TT.raw_term);
}
terminal_size(&TT.win_width, &TT.win_height);
TT.sfd = xconnectany(xgetaddrinfo(*toys.optargs, port, 0, SOCK_STREAM,
IPPROTO_TCP, 0));
setsockopt(TT.sfd, SOL_SOCKET, SO_REUSEADDR, &set, sizeof(set));
setsockopt(TT.sfd, SOL_SOCKET, SO_KEEPALIVE, &set, sizeof(set));
pfds[0].fd = 0;
pfds[0].events = POLLIN;
pfds[1].fd = TT.sfd;
pfds[1].events = POLLIN;
signal(SIGINT, generic_signal);
while(1) {
if(TT.piac) flush_iac();
if(poll(pfds, 2, -1) < 0) {
if (toys.signal) handle_esc();
else sleep(1);
continue;
}
if(pfds[0].revents) {
len = read(0, TT.buff, DATABUFSIZE);
if(len > 0) write_server(len);
else return;
}
if(pfds[1].revents) {
len = read(TT.sfd, TT.buff, DATABUFSIZE);
if(len > 0) read_server(len);
else {
printf("Connection closed by foreign host\r\n");
if(TT.term_ok) tcsetattr(0, TCSADRAIN, &TT.def_term);
exit(1);
}
}
}
}