| /* 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 |
| * |
| * Licensed under the GPL v2 or later, see the file LICENSE in this tarball. |
| * |
| * 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 <arpa/telnet.h> |
| #include <netinet/in.h> |
| #include "libbb.h" |
| |
| #ifdef DOTRACE |
| #define TRACE(x, y) do { if (x) printf y; } while (0) |
| #else |
| #define TRACE(x, y) |
| #endif |
| |
| enum { |
| DATABUFSIZE = 128, |
| IACBUFSIZE = 128, |
| |
| CHM_TRY = 0, |
| CHM_ON = 1, |
| CHM_OFF = 2, |
| |
| UF_ECHO = 0x01, |
| UF_SGA = 0x02, |
| |
| TS_0 = 1, |
| TS_IAC = 2, |
| TS_OPT = 3, |
| TS_SUB1 = 4, |
| TS_SUB2 = 5, |
| }; |
| |
| typedef unsigned char byte; |
| |
| enum { netfd = 3 }; |
| |
| struct globals { |
| int iaclen; /* could even use byte, but it's a loss on x86 */ |
| byte telstate; /* telnet negotiation state from network input */ |
| byte telwish; /* DO, DONT, WILL, WONT */ |
| byte charmode; |
| byte telflags; |
| byte do_termios; |
| #if ENABLE_FEATURE_TELNET_TTYPE |
| char *ttype; |
| #endif |
| #if ENABLE_FEATURE_TELNET_AUTOLOGIN |
| const char *autologin; |
| #endif |
| #if ENABLE_FEATURE_AUTOWIDTH |
| unsigned win_width, win_height; |
| #endif |
| /* same buffer used both for network and console read/write */ |
| char buf[DATABUFSIZE]; |
| /* buffer to handle telnet negotiations */ |
| char iacbuf[IACBUFSIZE]; |
| struct termios termios_def; |
| struct termios termios_raw; |
| }; |
| #define G (*(struct globals*)&bb_common_bufsiz1) |
| #define INIT_G() do { \ |
| struct G_sizecheck { \ |
| char G_sizecheck[sizeof(G) > COMMON_BUFSIZE ? -1 : 1]; \ |
| }; \ |
| } while (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); |
| |
| static void iac_flush(void) |
| { |
| write(netfd, G.iacbuf, G.iaclen); |
| G.iaclen = 0; |
| } |
| |
| #define write_str(fd, str) write(fd, str, sizeof(str) - 1) |
| |
| static void doexit(int ev) NORETURN; |
| static void doexit(int ev) |
| { |
| cookmode(); |
| exit(ev); |
| } |
| |
| static void con_escape(void) |
| { |
| char b; |
| |
| if (bb_got_signal) /* came from line mode... go raw */ |
| rawmode(); |
| |
| write_str(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(STDIN_FILENO, &b, 1) <= 0) |
| doexit(EXIT_FAILURE); |
| |
| switch (b) { |
| case 'l': |
| if (!bb_got_signal) { |
| do_linemode(); |
| goto ret; |
| } |
| break; |
| case 'c': |
| if (bb_got_signal) { |
| will_charmode(); |
| goto ret; |
| } |
| break; |
| case 'z': |
| cookmode(); |
| kill(0, SIGTSTP); |
| rawmode(); |
| break; |
| case 'e': |
| doexit(EXIT_SUCCESS); |
| } |
| |
| write_str(1, "continuing...\r\n"); |
| |
| if (bb_got_signal) |
| cookmode(); |
| ret: |
| bb_got_signal = 0; |
| |
| } |
| |
| static void handle_net_output(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 - why do you have to make 'many write()s'? |
| * I don't understand. |
| * So I implemented it. It's really useful for me. I hope that |
| * other people will find it interesting too. |
| */ |
| |
| int i, j; |
| byte *p = (byte*)G.buf; |
| byte outbuf[4*DATABUFSIZE]; |
| |
| for (i = len, j = 0; i > 0; i--, p++) { |
| if (*p == 0x1d) { |
| con_escape(); |
| return; |
| } |
| outbuf[j++] = *p; |
| if (*p == 0xff) |
| outbuf[j++] = 0xff; |
| else if (*p == 0x0d) |
| outbuf[j++] = 0x00; |
| } |
| if (j > 0) |
| write(netfd, outbuf, j); |
| } |
| |
| static void handle_net_input(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; |
| } |
| continue; |
| } |
| 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) |
| iac_flush(); |
| if (G.telstate == TS_0) |
| G.telstate = 0; |
| len = cstart; |
| } |
| |
| if (len) |
| write(STDOUT_FILENO, G.buf, len); |
| } |
| |
| static void put_iac(int c) |
| { |
| G.iacbuf[G.iaclen++] = c; |
| } |
| |
| static void put_iac2(byte wwdd, byte c) |
| { |
| if (G.iaclen + 3 > IACBUFSIZE) |
| iac_flush(); |
| |
| put_iac(IAC); |
| put_iac(wwdd); |
| put_iac(c); |
| } |
| |
| #if ENABLE_FEATURE_TELNET_TTYPE |
| static void put_iac_subopt(byte c, char *str) |
| { |
| int len = strlen(str) + 6; // ( 2 + 1 + 1 + strlen + 2 ) |
| |
| if (G.iaclen + len > IACBUFSIZE) |
| iac_flush(); |
| |
| put_iac(IAC); |
| put_iac(SB); |
| put_iac(c); |
| put_iac(0); |
| |
| while (*str) |
| put_iac(*str++); |
| |
| put_iac(IAC); |
| put_iac(SE); |
| } |
| #endif |
| |
| #if ENABLE_FEATURE_TELNET_AUTOLOGIN |
| static void put_iac_subopt_autologin(void) |
| { |
| int len = strlen(G.autologin) + 6; // (2 + 1 + 1 + strlen + 2) |
| const char *user = "USER"; |
| |
| if (G.iaclen + len > IACBUFSIZE) |
| iac_flush(); |
| |
| put_iac(IAC); |
| put_iac(SB); |
| put_iac(TELOPT_NEW_ENVIRON); |
| put_iac(TELQUAL_IS); |
| put_iac(NEW_ENV_VAR); |
| |
| while (*user) |
| put_iac(*user++); |
| |
| put_iac(NEW_ENV_VALUE); |
| |
| while (*G.autologin) |
| put_iac(*G.autologin++); |
| |
| put_iac(IAC); |
| put_iac(SE); |
| } |
| #endif |
| |
| #if ENABLE_FEATURE_AUTOWIDTH |
| static void put_iac_naws(byte c, int x, int y) |
| { |
| if (G.iaclen + 9 > IACBUFSIZE) |
| iac_flush(); |
| |
| put_iac(IAC); |
| put_iac(SB); |
| put_iac(c); |
| |
| put_iac((x >> 8) & 0xff); |
| put_iac(x & 0xff); |
| put_iac((y >> 8) & 0xff); |
| put_iac(y & 0xff); |
| |
| put_iac(IAC); |
| put_iac(SE); |
| } |
| #endif |
| |
| static char const escapecharis[] ALIGN1 = "\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(); |
| |
| put_iac2(DO, TELOPT_ECHO); |
| put_iac2(DO, TELOPT_SGA); |
| iac_flush(); |
| } |
| |
| static void do_linemode(void) |
| { |
| G.charmode = CHM_TRY; |
| G.telflags &= ~(UF_ECHO | UF_SGA); |
| setConMode(); |
| |
| put_iac2(DONT, TELOPT_ECHO); |
| put_iac2(DONT, TELOPT_SGA); |
| iac_flush(); |
| } |
| |
| static void to_notsup(char c) |
| { |
| if (G.telwish == WILL) |
| put_iac2(DONT, c); |
| else if (G.telwish == DO) |
| put_iac2(WONT, c); |
| } |
| |
| static void to_echo(void) |
| { |
| /* if server requests ECHO, don't agree */ |
| if (G.telwish == DO) { |
| put_iac2(WONT, TELOPT_ECHO); |
| return; |
| } |
| 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) |
| put_iac2(DO, TELOPT_ECHO); |
| else |
| put_iac2(DONT, TELOPT_ECHO); |
| |
| setConMode(); |
| write_str(1, "\r\n"); /* sudden modec */ |
| } |
| |
| static 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; |
| |
| G.telflags ^= UF_SGA; /* toggle */ |
| if (G.telflags & UF_SGA) |
| put_iac2(DO, TELOPT_SGA); |
| else |
| put_iac2(DONT, TELOPT_SGA); |
| } |
| |
| #if ENABLE_FEATURE_TELNET_TTYPE |
| static void to_ttype(void) |
| { |
| /* Tell server we will (or won't) do TTYPE */ |
| |
| if (G.ttype) |
| put_iac2(WILL, TELOPT_TTYPE); |
| else |
| put_iac2(WONT, TELOPT_TTYPE); |
| } |
| #endif |
| |
| #if ENABLE_FEATURE_TELNET_AUTOLOGIN |
| static void to_new_environ(void) |
| { |
| /* Tell server we will (or will not) do AUTOLOGIN */ |
| |
| if (G.autologin) |
| put_iac2(WILL, TELOPT_NEW_ENVIRON); |
| else |
| put_iac2(WONT, TELOPT_NEW_ENVIRON); |
| } |
| #endif |
| |
| #if ENABLE_FEATURE_AUTOWIDTH |
| static void to_naws(void) |
| { |
| /* Tell server we will do NAWS */ |
| put_iac2(WILL, TELOPT_NAWS); |
| } |
| #endif |
| |
| static void telopt(byte c) |
| { |
| switch (c) { |
| case TELOPT_ECHO: |
| to_echo(); break; |
| case TELOPT_SGA: |
| to_sga(); break; |
| #if ENABLE_FEATURE_TELNET_TTYPE |
| case TELOPT_TTYPE: |
| to_ttype(); break; |
| #endif |
| #if ENABLE_FEATURE_TELNET_AUTOLOGIN |
| case TELOPT_NEW_ENVIRON: |
| to_new_environ(); break; |
| #endif |
| #if ENABLE_FEATURE_AUTOWIDTH |
| case TELOPT_NAWS: |
| to_naws(); |
| put_iac_naws(c, G.win_width, G.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; |
| #if ENABLE_FEATURE_TELNET_TTYPE |
| else |
| if (c == TELOPT_TTYPE) |
| put_iac_subopt(TELOPT_TTYPE, G.ttype); |
| #endif |
| #if ENABLE_FEATURE_TELNET_AUTOLOGIN |
| else |
| if (c == TELOPT_NEW_ENVIRON) |
| put_iac_subopt_autologin(); |
| #endif |
| break; |
| case TS_SUB2: |
| if (c == SE) |
| return TRUE; |
| G.telstate = TS_SUB1; |
| /* break; */ |
| } |
| return FALSE; |
| } |
| |
| static void rawmode(void) |
| { |
| if (G.do_termios) |
| tcsetattr(0, TCSADRAIN, &G.termios_raw); |
| } |
| |
| static void cookmode(void) |
| { |
| if (G.do_termios) |
| tcsetattr(0, TCSADRAIN, &G.termios_def); |
| } |
| |
| /* poll gives smaller (-70 bytes) code */ |
| #define USE_POLL 1 |
| |
| int telnet_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; |
| int telnet_main(int argc UNUSED_PARAM, char **argv) |
| { |
| char *host; |
| int port; |
| int len; |
| #ifdef USE_POLL |
| struct pollfd ufds[2]; |
| #else |
| fd_set readfds; |
| int maxfd; |
| #endif |
| |
| INIT_G(); |
| |
| #if ENABLE_FEATURE_AUTOWIDTH |
| get_terminal_width_height(0, &G.win_width, &G.win_height); |
| #endif |
| |
| #if ENABLE_FEATURE_TELNET_TTYPE |
| G.ttype = getenv("TERM"); |
| #endif |
| |
| if (tcgetattr(0, &G.termios_def) >= 0) { |
| G.do_termios = 1; |
| G.termios_raw = G.termios_def; |
| cfmakeraw(&G.termios_raw); |
| } |
| |
| #if ENABLE_FEATURE_TELNET_AUTOLOGIN |
| if (1 & getopt32(argv, "al:", &G.autologin)) |
| G.autologin = getenv("USER"); |
| argv += optind; |
| #else |
| argv++; |
| #endif |
| if (!*argv) |
| bb_show_usage(); |
| host = *argv++; |
| port = bb_lookup_port(*argv ? *argv++ : "telnet", "tcp", 23); |
| if (*argv) /* extra params?? */ |
| bb_show_usage(); |
| |
| xmove_fd(create_and_connect_stream_or_die(host, port), netfd); |
| |
| setsockopt(netfd, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1)); |
| |
| signal(SIGINT, record_signo); |
| |
| #ifdef USE_POLL |
| ufds[0].fd = 0; ufds[1].fd = netfd; |
| ufds[0].events = ufds[1].events = POLLIN; |
| #else |
| FD_ZERO(&readfds); |
| FD_SET(STDIN_FILENO, &readfds); |
| FD_SET(netfd, &readfds); |
| maxfd = 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 (bb_got_signal) |
| con_escape(); |
| else |
| sleep(1); |
| break; |
| default: |
| |
| #ifdef USE_POLL |
| if (ufds[0].revents) /* well, should check POLLIN, but ... */ |
| #else |
| if (FD_ISSET(STDIN_FILENO, &rfds)) |
| #endif |
| { |
| len = read(STDIN_FILENO, G.buf, DATABUFSIZE); |
| if (len <= 0) |
| doexit(EXIT_SUCCESS); |
| TRACE(0, ("Read con: %d\n", len)); |
| handle_net_output(len); |
| } |
| |
| #ifdef USE_POLL |
| if (ufds[1].revents) /* well, should check POLLIN, but ... */ |
| #else |
| if (FD_ISSET(netfd, &rfds)) |
| #endif |
| { |
| len = read(netfd, G.buf, DATABUFSIZE); |
| if (len <= 0) { |
| write_str(1, "Connection closed by foreign host\r\n"); |
| doexit(EXIT_FAILURE); |
| } |
| TRACE(0, ("Read netfd (%d): %d\n", netfd, len)); |
| handle_net_input(len); |
| } |
| } |
| } /* while (1) */ |
| } |