summaryrefslogtreecommitdiff
path: root/busybox/networking/telnet.c
diff options
context:
space:
mode:
Diffstat (limited to 'busybox/networking/telnet.c')
-rw-r--r--busybox/networking/telnet.c769
1 files changed, 769 insertions, 0 deletions
diff --git a/busybox/networking/telnet.c b/busybox/networking/telnet.c
new file mode 100644
index 0000000..6ad7712
--- /dev/null
+++ b/busybox/networking/telnet.c
@@ -0,0 +1,769 @@
+/* vi: set sw=4 ts=4: */
+/*
+ * telnet implementation for busybox
+ *
+ * Author: Tomi Ollila <too@iki.fi>
+ * Copyright (C) 1994-2000 by Tomi Ollila
+ *
+ * Created: Thu Apr 7 13:29:41 1994 too
+ * Last modified: Fri Jun 9 14:34:24 2000 too
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * HISTORY
+ * Revision 3.1 1994/04/17 11:31:54 too
+ * initial revision
+ * Modified 2000/06/13 for inclusion into BusyBox by Erik Andersen <andersen@codepoet.org>
+ * Modified 2001/05/07 to add ability to pass TTYPE to remote host by Jim McQuillan
+ * <jam@ltsp.org>
+ * Modified 2004/02/11 to add ability to pass the USER variable to remote host
+ * by Fernando Silveira <swrh@gmx.net>
+ *
+ */
+
+#include <termios.h>
+#include <unistd.h>
+#include <errno.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <string.h>
+#include <signal.h>
+#include <arpa/telnet.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include "busybox.h"
+
+#if 0
+static const int DOTRACE = 1;
+#endif
+
+#ifdef DOTRACE
+#include <arpa/inet.h> /* for inet_ntoa()... */
+#define TRACE(x, y) do { if (x) printf y; } while (0)
+#else
+#define TRACE(x, y)
+#endif
+
+#if 0
+#define USE_POLL
+#include <sys/poll.h>
+#else
+#include <sys/time.h>
+#endif
+
+#define DATABUFSIZE 128
+#define IACBUFSIZE 128
+
+static const int CHM_TRY = 0;
+static const int CHM_ON = 1;
+static const int CHM_OFF = 2;
+
+static const int UF_ECHO = 0x01;
+static const int UF_SGA = 0x02;
+
+enum {
+ TS_0 = 1,
+ TS_IAC = 2,
+ TS_OPT = 3,
+ TS_SUB1 = 4,
+ TS_SUB2 = 5,
+};
+
+#define WriteCS(fd, str) write(fd, str, sizeof str -1)
+
+typedef unsigned char byte;
+
+/* use globals to reduce size ??? */ /* test this hypothesis later */
+static struct Globalvars {
+ int netfd; /* console fd:s are 0 and 1 (and 2) */
+ /* same buffer used both for network and console read/write */
+ char buf[DATABUFSIZE]; /* allocating so static size is smaller */
+ byte telstate; /* telnet negotiation state from network input */
+ byte telwish; /* DO, DONT, WILL, WONT */
+ byte charmode;
+ byte telflags;
+ byte gotsig;
+ /* buffer to handle telnet negotiations */
+ char iacbuf[IACBUFSIZE];
+ short iaclen; /* could even use byte */
+ struct termios termios_def;
+ struct termios termios_raw;
+} G;
+
+#define xUSE_GLOBALVAR_PTR /* xUSE... -> don't use :D (makes smaller code) */
+
+#ifdef USE_GLOBALVAR_PTR
+struct Globalvars * Gptr;
+#define G (*Gptr)
+#endif
+
+static inline void iacflush(void)
+{
+ write(G.netfd, G.iacbuf, G.iaclen);
+ G.iaclen = 0;
+}
+
+/* Function prototypes */
+static void rawmode(void);
+static void cookmode(void);
+static void do_linemode(void);
+static void will_charmode(void);
+static void telopt(byte c);
+static int subneg(byte c);
+
+/* Some globals */
+static int one = 1;
+
+#ifdef CONFIG_FEATURE_TELNET_TTYPE
+static char *ttype;
+#endif
+
+#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
+static const char *autologin;
+#endif
+
+#ifdef CONFIG_FEATURE_AUTOWIDTH
+static int win_width, win_height;
+#endif
+
+static void doexit(int ev)
+{
+ cookmode();
+ exit(ev);
+}
+
+static void conescape(void)
+{
+ char b;
+
+ if (G.gotsig) /* came from line mode... go raw */
+ rawmode();
+
+ WriteCS(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");
+
+ if (read(0, &b, 1) <= 0)
+ doexit(1);
+
+ switch (b)
+ {
+ case 'l':
+ if (!G.gotsig)
+ {
+ do_linemode();
+ goto rrturn;
+ }
+ break;
+ case 'c':
+ if (G.gotsig)
+ {
+ will_charmode();
+ goto rrturn;
+ }
+ break;
+ case 'z':
+ cookmode();
+ kill(0, SIGTSTP);
+ rawmode();
+ break;
+ case 'e':
+ doexit(0);
+ }
+
+ WriteCS(1, "continuing...\r\n");
+
+ if (G.gotsig)
+ cookmode();
+
+ rrturn:
+ G.gotsig = 0;
+
+}
+static void handlenetoutput(int len)
+{
+ /* here we could do smart tricks how to handle 0xFF:s in output
+ * stream like writing twice every sequence of FF:s (thus doing
+ * many write()s. But I think interactive telnet application does
+ * not need to be 100% 8-bit clean, so changing every 0xff:s to
+ * 0x7f:s
+ *
+ * 2002-mar-21, Przemyslaw Czerpak (druzus@polbox.com)
+ * I don't agree.
+ * first - I cannot use programs like sz/rz
+ * second - the 0x0D is sent as one character and if the next
+ * char is 0x0A then it's eaten by a server side.
+ * third - whay doy you have to make 'many write()s'?
+ * I don't understand.
+ * So I implemented it. It's realy useful for me. I hope that
+ * others people will find it interesting to.
+ */
+
+ int i, j;
+ byte * p = G.buf;
+ byte outbuf[4*DATABUFSIZE];
+
+ for (i = len, j = 0; i > 0; i--, p++)
+ {
+ if (*p == 0x1d)
+ {
+ conescape();
+ return;
+ }
+ outbuf[j++] = *p;
+ if (*p == 0xff)
+ outbuf[j++] = 0xff;
+ else if (*p == 0x0d)
+ outbuf[j++] = 0x00;
+ }
+ if (j > 0 )
+ write(G.netfd, outbuf, j);
+}
+
+
+static void handlenetinput(int len)
+{
+ int i;
+ int cstart = 0;
+
+ for (i = 0; i < len; i++)
+ {
+ byte c = G.buf[i];
+
+ if (G.telstate == 0) /* most of the time state == 0 */
+ {
+ if (c == IAC)
+ {
+ cstart = i;
+ G.telstate = TS_IAC;
+ }
+ }
+ else
+ switch (G.telstate)
+ {
+ case TS_0:
+ if (c == IAC)
+ G.telstate = TS_IAC;
+ else
+ G.buf[cstart++] = c;
+ break;
+
+ case TS_IAC:
+ if (c == IAC) /* IAC IAC -> 0xFF */
+ {
+ G.buf[cstart++] = c;
+ G.telstate = TS_0;
+ break;
+ }
+ /* else */
+ switch (c)
+ {
+ case SB:
+ G.telstate = TS_SUB1;
+ break;
+ case DO:
+ case DONT:
+ case WILL:
+ case WONT:
+ G.telwish = c;
+ G.telstate = TS_OPT;
+ break;
+ default:
+ G.telstate = TS_0; /* DATA MARK must be added later */
+ }
+ break;
+ case TS_OPT: /* WILL, WONT, DO, DONT */
+ telopt(c);
+ G.telstate = TS_0;
+ break;
+ case TS_SUB1: /* Subnegotiation */
+ case TS_SUB2: /* Subnegotiation */
+ if (subneg(c))
+ G.telstate = TS_0;
+ break;
+ }
+ }
+ if (G.telstate)
+ {
+ if (G.iaclen) iacflush();
+ if (G.telstate == TS_0) G.telstate = 0;
+
+ len = cstart;
+ }
+
+ if (len)
+ write(1, G.buf, len);
+}
+
+
+/* ******************************* */
+
+static inline void putiac(int c)
+{
+ G.iacbuf[G.iaclen++] = c;
+}
+
+
+static void putiac2(byte wwdd, byte c)
+{
+ if (G.iaclen + 3 > IACBUFSIZE)
+ iacflush();
+
+ putiac(IAC);
+ putiac(wwdd);
+ putiac(c);
+}
+
+#if 0
+static void putiac1(byte c)
+{
+ if (G.iaclen + 2 > IACBUFSIZE)
+ iacflush();
+
+ putiac(IAC);
+ putiac(c);
+}
+#endif
+
+#ifdef CONFIG_FEATURE_TELNET_TTYPE
+static void putiac_subopt(byte c, char *str)
+{
+ int len = strlen(str) + 6; // ( 2 + 1 + 1 + strlen + 2 )
+
+ if (G.iaclen + len > IACBUFSIZE)
+ iacflush();
+
+ putiac(IAC);
+ putiac(SB);
+ putiac(c);
+ putiac(0);
+
+ while(*str)
+ putiac(*str++);
+
+ putiac(IAC);
+ putiac(SE);
+}
+#endif
+
+#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
+static void putiac_subopt_autologin(void)
+{
+ int len = strlen(autologin) + 6; // (2 + 1 + 1 + strlen + 2)
+ char *user = "USER";
+
+ if (G.iaclen + len > IACBUFSIZE)
+ iacflush();
+
+ putiac(IAC);
+ putiac(SB);
+ putiac(TELOPT_NEW_ENVIRON);
+ putiac(TELQUAL_IS);
+ putiac(NEW_ENV_VAR);
+
+ while(*user)
+ putiac(*user++);
+
+ putiac(NEW_ENV_VALUE);
+
+ while(*autologin)
+ putiac(*autologin++);
+
+ putiac(IAC);
+ putiac(SE);
+}
+#endif
+
+#ifdef CONFIG_FEATURE_AUTOWIDTH
+static void putiac_naws(byte c, int x, int y)
+{
+ if (G.iaclen + 9 > IACBUFSIZE)
+ iacflush();
+
+ putiac(IAC);
+ putiac(SB);
+ putiac(c);
+
+ putiac((x >> 8) & 0xff);
+ putiac(x & 0xff);
+ putiac((y >> 8) & 0xff);
+ putiac(y & 0xff);
+
+ putiac(IAC);
+ putiac(SE);
+}
+#endif
+
+/* void putiacstring (subneg strings) */
+
+/* ******************************* */
+
+static char const escapecharis[] = "\r\nEscape character is ";
+
+static void setConMode(void)
+{
+ if (G.telflags & UF_ECHO)
+ {
+ if (G.charmode == CHM_TRY) {
+ G.charmode = CHM_ON;
+ printf("\r\nEntering character mode%s'^]'.\r\n", escapecharis);
+ rawmode();
+ }
+ }
+ else
+ {
+ if (G.charmode != CHM_OFF) {
+ G.charmode = CHM_OFF;
+ printf("\r\nEntering line mode%s'^C'.\r\n", escapecharis);
+ cookmode();
+ }
+ }
+}
+
+/* ******************************* */
+
+static void will_charmode(void)
+{
+ G.charmode = CHM_TRY;
+ G.telflags |= (UF_ECHO | UF_SGA);
+ setConMode();
+
+ putiac2(DO, TELOPT_ECHO);
+ putiac2(DO, TELOPT_SGA);
+ iacflush();
+}
+
+static void do_linemode(void)
+{
+ G.charmode = CHM_TRY;
+ G.telflags &= ~(UF_ECHO | UF_SGA);
+ setConMode();
+
+ putiac2(DONT, TELOPT_ECHO);
+ putiac2(DONT, TELOPT_SGA);
+ iacflush();
+}
+
+/* ******************************* */
+
+static inline void to_notsup(char c)
+{
+ if (G.telwish == WILL) putiac2(DONT, c);
+ else if (G.telwish == DO) putiac2(WONT, c);
+}
+
+static inline void to_echo(void)
+{
+ /* if server requests ECHO, don't agree */
+ if (G.telwish == DO) { putiac2(WONT, TELOPT_ECHO); return; }
+ else if (G.telwish == DONT) return;
+
+ if (G.telflags & UF_ECHO)
+ {
+ if (G.telwish == WILL)
+ return;
+ }
+ else
+ if (G.telwish == WONT)
+ return;
+
+ if (G.charmode != CHM_OFF)
+ G.telflags ^= UF_ECHO;
+
+ if (G.telflags & UF_ECHO)
+ putiac2(DO, TELOPT_ECHO);
+ else
+ putiac2(DONT, TELOPT_ECHO);
+
+ setConMode();
+ WriteCS(1, "\r\n"); /* sudden modec */
+}
+
+static inline void to_sga(void)
+{
+ /* daemon always sends will/wont, client do/dont */
+
+ if (G.telflags & UF_SGA)
+ {
+ if (G.telwish == WILL)
+ return;
+ }
+ else
+ if (G.telwish == WONT)
+ return;
+
+ if ((G.telflags ^= UF_SGA) & UF_SGA) /* toggle */
+ putiac2(DO, TELOPT_SGA);
+ else
+ putiac2(DONT, TELOPT_SGA);
+
+ return;
+}
+
+#ifdef CONFIG_FEATURE_TELNET_TTYPE
+static inline void to_ttype(void)
+{
+ /* Tell server we will (or won't) do TTYPE */
+
+ if(ttype)
+ putiac2(WILL, TELOPT_TTYPE);
+ else
+ putiac2(WONT, TELOPT_TTYPE);
+
+ return;
+}
+#endif
+
+#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
+static inline void to_new_environ(void)
+{
+ /* Tell server we will (or will not) do AUTOLOGIN */
+
+ if (autologin)
+ putiac2(WILL, TELOPT_NEW_ENVIRON);
+ else
+ putiac2(WONT, TELOPT_NEW_ENVIRON);
+
+ return;
+}
+#endif
+
+#ifdef CONFIG_FEATURE_AUTOWIDTH
+static inline void to_naws(void)
+{
+ /* Tell server we will do NAWS */
+ putiac2(WILL, TELOPT_NAWS);
+ return;
+}
+#endif
+
+static void telopt(byte c)
+{
+ switch (c)
+ {
+ case TELOPT_ECHO: to_echo(); break;
+ case TELOPT_SGA: to_sga(); break;
+#ifdef CONFIG_FEATURE_TELNET_TTYPE
+ case TELOPT_TTYPE: to_ttype();break;
+#endif
+#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
+ case TELOPT_NEW_ENVIRON: to_new_environ(); break;
+#endif
+#ifdef CONFIG_FEATURE_AUTOWIDTH
+ case TELOPT_NAWS: to_naws();
+ putiac_naws(c, win_width, win_height);
+ break;
+#endif
+ default: to_notsup(c);
+ break;
+ }
+}
+
+
+/* ******************************* */
+
+/* subnegotiation -- ignore all (except TTYPE,NAWS) */
+
+static int subneg(byte c)
+{
+ switch (G.telstate)
+ {
+ case TS_SUB1:
+ if (c == IAC)
+ G.telstate = TS_SUB2;
+#ifdef CONFIG_FEATURE_TELNET_TTYPE
+ else
+ if (c == TELOPT_TTYPE)
+ putiac_subopt(TELOPT_TTYPE,ttype);
+#endif
+#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
+ else
+ if (c == TELOPT_NEW_ENVIRON)
+ putiac_subopt_autologin();
+#endif
+ break;
+ case TS_SUB2:
+ if (c == SE)
+ return TRUE;
+ G.telstate = TS_SUB1;
+ /* break; */
+ }
+ return FALSE;
+}
+
+/* ******************************* */
+
+static void fgotsig(int sig)
+{
+ G.gotsig = sig;
+}
+
+
+static void rawmode(void)
+{
+ tcsetattr(0, TCSADRAIN, &G.termios_raw);
+}
+
+static void cookmode(void)
+{
+ tcsetattr(0, TCSADRAIN, &G.termios_def);
+}
+
+extern int telnet_main(int argc, char** argv)
+{
+ int len;
+ struct sockaddr_in s_in;
+#ifdef USE_POLL
+ struct pollfd ufds[2];
+#else
+ fd_set readfds;
+ int maxfd;
+#endif
+
+#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
+ int opt;
+#endif
+
+#ifdef CONFIG_FEATURE_AUTOWIDTH
+ get_terminal_width_height(0, &win_width, &win_height);
+#endif
+
+#ifdef CONFIG_FEATURE_TELNET_TTYPE
+ ttype = getenv("TERM");
+#endif
+
+ memset(&G, 0, sizeof G);
+
+ if (tcgetattr(0, &G.termios_def) < 0)
+ exit(1);
+
+ G.termios_raw = G.termios_def;
+ cfmakeraw(&G.termios_raw);
+
+ if (argc < 2)
+ bb_show_usage();
+
+#ifdef CONFIG_FEATURE_TELNET_AUTOLOGIN
+ autologin = NULL;
+ while ((opt = getopt(argc, argv, "al:")) != EOF) {
+ switch (opt) {
+ case 'l':
+ autologin = optarg;
+ break;
+ case 'a':
+ autologin = getenv("USER");
+ break;
+ case '?':
+ bb_show_usage();
+ break;
+ }
+ }
+ if (optind < argc) {
+ bb_lookup_host(&s_in, argv[optind++]);
+ s_in.sin_port = bb_lookup_port((optind < argc) ? argv[optind++] :
+ "telnet", "tcp", 23);
+ if (optind < argc)
+ bb_show_usage();
+ } else
+ bb_show_usage();
+#else
+ bb_lookup_host(&s_in, argv[1]);
+ s_in.sin_port = bb_lookup_port((argc == 3) ? argv[2] : "telnet", "tcp", 23);
+#endif
+
+ G.netfd = xconnect(&s_in);
+
+ setsockopt(G.netfd, SOL_SOCKET, SO_KEEPALIVE, &one, sizeof one);
+
+ signal(SIGINT, fgotsig);
+
+#ifdef USE_POLL
+ ufds[0].fd = 0; ufds[1].fd = G.netfd;
+ ufds[0].events = ufds[1].events = POLLIN;
+#else
+ FD_ZERO(&readfds);
+ FD_SET(0, &readfds);
+ FD_SET(G.netfd, &readfds);
+ maxfd = G.netfd + 1;
+#endif
+
+ while (1)
+ {
+#ifndef USE_POLL
+ fd_set rfds = readfds;
+
+ switch (select(maxfd, &rfds, NULL, NULL, NULL))
+#else
+ switch (poll(ufds, 2, -1))
+#endif
+ {
+ case 0:
+ /* timeout */
+ case -1:
+ /* error, ignore and/or log something, bay go to loop */
+ if (G.gotsig)
+ conescape();
+ else
+ sleep(1);
+ break;
+ default:
+
+#ifdef USE_POLL
+ if (ufds[0].revents) /* well, should check POLLIN, but ... */
+#else
+ if (FD_ISSET(0, &rfds))
+#endif
+ {
+ len = read(0, G.buf, DATABUFSIZE);
+
+ if (len <= 0)
+ doexit(0);
+
+ TRACE(0, ("Read con: %d\n", len));
+
+ handlenetoutput(len);
+ }
+
+#ifdef USE_POLL
+ if (ufds[1].revents) /* well, should check POLLIN, but ... */
+#else
+ if (FD_ISSET(G.netfd, &rfds))
+#endif
+ {
+ len = read(G.netfd, G.buf, DATABUFSIZE);
+
+ if (len <= 0)
+ {
+ WriteCS(1, "Connection closed by foreign host.\r\n");
+ doexit(1);
+ }
+ TRACE(0, ("Read netfd (%d): %d\n", G.netfd, len));
+
+ handlenetinput(len);
+ }
+ }
+ }
+}
+
+/*
+Local Variables:
+c-file-style: "linux"
+c-basic-offset: 4
+tab-width: 4
+End:
+*/
generated by cgit v1.1 at 2025-04-02 05:34:31 +0000