| /* 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 GPLv2 or later, see file LICENSE in this source tree. |
| * |
| * 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> |
| */ |
| //config:config TELNET |
| //config: bool "telnet (8.8 kb)" |
| //config: default y |
| //config: help |
| //config: Telnet is an interface to the TELNET protocol, but is also commonly |
| //config: used to test other simple protocols. |
| //config: |
| //config:config FEATURE_TELNET_TTYPE |
| //config: bool "Pass TERM type to remote host" |
| //config: default y |
| //config: depends on TELNET |
| //config: help |
| //config: Setting this option will forward the TERM environment variable to the |
| //config: remote host you are connecting to. This is useful to make sure that |
| //config: things like ANSI colors and other control sequences behave. |
| //config: |
| //config:config FEATURE_TELNET_AUTOLOGIN |
| //config: bool "Pass USER type to remote host" |
| //config: default y |
| //config: depends on TELNET |
| //config: help |
| //config: Setting this option will forward the USER environment variable to the |
| //config: remote host you are connecting to. This is useful when you need to |
| //config: log into a machine without telling the username (autologin). This |
| //config: option enables '-a' and '-l USER' options. |
| //config: |
| //config:config FEATURE_TELNET_WIDTH |
| //config: bool "Enable window size autodetection" |
| //config: default y |
| //config: depends on TELNET |
| |
| //applet:IF_TELNET(APPLET(telnet, BB_DIR_USR_BIN, BB_SUID_DROP)) |
| |
| //kbuild:lib-$(CONFIG_TELNET) += telnet.o |
| |
| //usage:#if ENABLE_FEATURE_TELNET_AUTOLOGIN |
| //usage:#define telnet_trivial_usage |
| //usage: "[-a] [-l USER] HOST [PORT]" |
| //usage:#define telnet_full_usage "\n\n" |
| //usage: "Connect to telnet server\n" |
| //usage: "\n -a Automatic login with $USER variable" |
| //usage: "\n -l USER Automatic login as USER" |
| //usage: |
| //usage:#else |
| //usage:#define telnet_trivial_usage |
| //usage: "HOST [PORT]" |
| //usage:#define telnet_full_usage "\n\n" |
| //usage: "Connect to telnet server" |
| //usage:#endif |
| |
| #include <arpa/telnet.h> |
| #include <netinet/in.h> |
| #include "libbb.h" |
| #include "common_bufsiz.h" |
| |
| #ifdef __BIONIC__ |
| /* should be in arpa/telnet.h */ |
| # define IAC 255 /* interpret as command: */ |
| # define DONT 254 /* you are not to use option */ |
| # define DO 253 /* please, you use option */ |
| # define WONT 252 /* I won't use option */ |
| # define WILL 251 /* I will use option */ |
| # define SB 250 /* interpret as subnegotiation */ |
| # define SE 240 /* end sub negotiation */ |
| # define TELOPT_ECHO 1 /* echo */ |
| # define TELOPT_SGA 3 /* suppress go ahead */ |
| # define TELOPT_TTYPE 24 /* terminal type */ |
| # define TELOPT_NAWS 31 /* window size */ |
| #endif |
| |
| enum { |
| DATABUFSIZE = 128, |
| IACBUFSIZE = 128, |
| |
| CHM_TRY = 0, |
| CHM_ON = 1, |
| CHM_OFF = 2, |
| |
| UF_ECHO = 0x01, |
| UF_SGA = 0x02, |
| |
| TS_NORMAL = 0, |
| TS_COPY = 1, |
| TS_IAC = 2, |
| TS_OPT = 3, |
| TS_SUB1 = 4, |
| TS_SUB2 = 5, |
| TS_CR = 6, |
| }; |
| |
| 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_TELNET_WIDTH |
| 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; |
| } FIX_ALIASING; |
| #define G (*(struct globals*)bb_common_bufsiz1) |
| #define INIT_G() do { \ |
| setup_common_bufsiz(); \ |
| BUILD_BUG_ON(sizeof(G) > COMMON_BUFSIZE); \ |
| } while (0) |
| |
| |
| static void rawmode(void); |
| static void cookmode(void); |
| static void do_linemode(void); |
| static void will_charmode(void); |
| static void telopt(byte c); |
| static void subneg(byte c); |
| |
| static void iac_flush(void) |
| { |
| full_write(netfd, G.iacbuf, G.iaclen); |
| G.iaclen = 0; |
| } |
| |
| 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(); |
| |
| full_write1_str("\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); |
| } |
| |
| full_write1_str("continuing...\r\n"); |
| |
| if (bb_got_signal) |
| cookmode(); |
| ret: |
| bb_got_signal = 0; |
| } |
| |
| static void handle_net_output(int len) |
| { |
| byte outbuf[2 * DATABUFSIZE]; |
| byte *dst = outbuf; |
| byte *src = (byte*)G.buf; |
| byte *end = src + len; |
| |
| while (src < end) { |
| byte c = *src++; |
| if (c == 0x1d) { |
| con_escape(); |
| return; |
| } |
| *dst = c; |
| if (c == IAC) |
| *++dst = c; /* IAC -> IAC IAC */ |
| else |
| if (c == '\r' || c == '\n') { |
| /* Enter key sends '\r' in raw mode and '\n' in cooked one. |
| * |
| * See RFC 1123 3.3.1 Telnet End-of-Line Convention. |
| * Using CR LF instead of other allowed possibilities |
| * like CR NUL - easier to talk to HTTP/SMTP servers. |
| */ |
| *dst = '\r'; /* Enter -> CR LF */ |
| *++dst = '\n'; |
| } |
| dst++; |
| } |
| if (dst - outbuf != 0) |
| full_write(netfd, outbuf, dst - outbuf); |
| } |
| |
| 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 == TS_NORMAL) { /* most typical state */ |
| if (c == IAC) { |
| cstart = i; |
| G.telstate = TS_IAC; |
| } |
| else if (c == '\r') { |
| cstart = i + 1; |
| G.telstate = TS_CR; |
| } |
| /* No IACs were seen so far, no need to copy |
| * bytes within G.buf: */ |
| continue; |
| } |
| |
| switch (G.telstate) { |
| case TS_CR: |
| /* Prev char was CR. If cur one is NUL, ignore it. |
| * See RFC 1123 section 3.3.1 for discussion of telnet EOL handling. |
| */ |
| G.telstate = TS_COPY; |
| if (c == '\0') |
| break; |
| /* else: fall through - need to handle CR IAC ... properly */ |
| |
| case TS_COPY: /* Prev char was ordinary */ |
| /* Similar to NORMAL, but in TS_COPY we need to copy bytes */ |
| if (c == IAC) |
| G.telstate = TS_IAC; |
| else |
| G.buf[cstart++] = c; |
| if (c == '\r') |
| G.telstate = TS_CR; |
| break; |
| |
| case TS_IAC: /* Prev char was IAC */ |
| if (c == IAC) { /* IAC IAC -> one IAC */ |
| G.buf[cstart++] = c; |
| G.telstate = TS_COPY; |
| 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; |
| /* DATA MARK must be added later */ |
| default: |
| G.telstate = TS_COPY; |
| } |
| break; |
| |
| case TS_OPT: /* Prev chars were IAC WILL/WONT/DO/DONT */ |
| telopt(c); |
| G.telstate = TS_COPY; |
| break; |
| |
| case TS_SUB1: /* Subnegotiation */ |
| case TS_SUB2: /* Subnegotiation */ |
| subneg(c); /* can change G.telstate */ |
| break; |
| } |
| } |
| |
| if (G.telstate != TS_NORMAL) { |
| /* We had some IACs, or CR */ |
| if (G.iaclen) |
| iac_flush(); |
| if (G.telstate == TS_COPY) /* we aren't in the middle of IAC */ |
| G.telstate = TS_NORMAL; |
| len = cstart; |
| } |
| |
| if (len) |
| full_write(STDOUT_FILENO, G.buf, len); |
| } |
| |
| static void put_iac(int c) |
| { |
| G.iacbuf[G.iaclen++] = c; |
| } |
| |
| static void put_iac2_merged(unsigned wwdd_and_c) |
| { |
| if (G.iaclen + 3 > IACBUFSIZE) |
| iac_flush(); |
| |
| put_iac(IAC); |
| put_iac(wwdd_and_c >> 8); |
| put_iac(wwdd_and_c & 0xff); |
| } |
| #define put_iac2(wwdd,c) put_iac2_merged(((wwdd)<<8) + (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 *p = "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 (*p) |
| put_iac(*p++); |
| |
| put_iac(NEW_ENV_VALUE); |
| |
| p = G.autologin; |
| while (*p) |
| put_iac(*p++); |
| |
| put_iac(IAC); |
| put_iac(SE); |
| } |
| #endif |
| |
| #if ENABLE_FEATURE_TELNET_WIDTH |
| 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); |
| |
| /* "... & 0xff" implicitly done below */ |
| put_iac(x >> 8); |
| put_iac(x); |
| put_iac(y >> 8); |
| put_iac(y); |
| |
| put_iac(IAC); |
| put_iac(SE); |
| } |
| #endif |
| |
| static void setConMode(void) |
| { |
| if (G.telflags & UF_ECHO) { |
| if (G.charmode == CHM_TRY) { |
| G.charmode = CHM_ON; |
| printf("\r\nEntering %s mode" |
| "\r\nEscape character is '^%c'.\r\n", "character", ']'); |
| rawmode(); |
| } |
| } else { |
| if (G.charmode != CHM_OFF) { |
| G.charmode = CHM_OFF; |
| printf("\r\nEntering %s mode" |
| "\r\nEscape character is '^%c'.\r\n", "line", 'C'); |
| 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(); |
| full_write1_str("\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_TELNET_WIDTH |
| 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_TELNET_WIDTH |
| 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 void 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 && G.ttype) |
| put_iac_subopt(TELOPT_TTYPE, G.ttype); |
| #endif |
| #if ENABLE_FEATURE_TELNET_AUTOLOGIN |
| else |
| if (c == TELOPT_NEW_ENVIRON && G.autologin) |
| put_iac_subopt_autologin(); |
| #endif |
| break; |
| case TS_SUB2: |
| if (c == SE) { |
| G.telstate = TS_COPY; |
| return; |
| } |
| G.telstate = TS_SUB1; |
| break; |
| } |
| } |
| |
| 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); |
| } |
| |
| 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; |
| struct pollfd ufds[2]; |
| |
| INIT_G(); |
| |
| #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)) { |
| /* Only -a without -l USER picks $USER from envvar */ |
| G.autologin = getenv("USER"); |
| } |
| argv += optind; |
| #else |
| argv++; |
| #endif |
| if (!*argv) |
| bb_show_usage(); |
| host = *argv++; |
| port = *argv ? bb_lookup_port(*argv++, "tcp", 23) |
| : bb_lookup_std_port("telnet", "tcp", 23); |
| if (*argv) /* extra params?? */ |
| bb_show_usage(); |
| |
| xmove_fd(create_and_connect_stream_or_die(host, port), netfd); |
| |
| setsockopt_keepalive(netfd); |
| |
| #if ENABLE_FEATURE_TELNET_WIDTH |
| get_terminal_width_height(0, &G.win_width, &G.win_height); |
| //TODO: support dynamic resize? |
| #endif |
| |
| signal(SIGINT, record_signo); |
| |
| ufds[0].fd = STDIN_FILENO; |
| ufds[0].events = POLLIN; |
| ufds[1].fd = netfd; |
| ufds[1].events = POLLIN; |
| |
| while (1) { |
| if (poll(ufds, 2, -1) < 0) { |
| /* error, ignore and/or log something, bay go to loop */ |
| if (bb_got_signal) |
| con_escape(); |
| else |
| sleep(1); |
| continue; |
| } |
| |
| // FIXME: reads can block. Need full bidirectional buffering. |
| |
| if (ufds[0].revents) { |
| len = safe_read(STDIN_FILENO, G.buf, DATABUFSIZE); |
| if (len <= 0) |
| doexit(EXIT_SUCCESS); |
| handle_net_output(len); |
| } |
| |
| if (ufds[1].revents) { |
| len = safe_read(netfd, G.buf, DATABUFSIZE); |
| if (len <= 0) { |
| full_write1_str("Connection closed by foreign host\r\n"); |
| doexit(EXIT_FAILURE); |
| } |
| handle_net_input(len); |
| } |
| } /* while (1) */ |
| } |