1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * telnet implementation for busybox
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4 | *
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5 | * Author: Tomi Ollila <too@iki.fi>
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6 | * Copyright (C) 1994-2000 by Tomi Ollila
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7 | *
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8 | * Created: Thu Apr 7 13:29:41 1994 too
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9 | * Last modified: Fri Jun 9 14:34:24 2000 too
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10 | *
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11 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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12 | *
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13 | * HISTORY
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14 | * Revision 3.1 1994/04/17 11:31:54 too
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15 | * initial revision
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16 | * Modified 2000/06/13 for inclusion into BusyBox by Erik Andersen <andersen@codepoet.org>
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17 | * Modified 2001/05/07 to add ability to pass TTYPE to remote host by Jim McQuillan
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18 | * <jam@ltsp.org>
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19 | * Modified 2004/02/11 to add ability to pass the USER variable to remote host
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20 | * by Fernando Silveira <swrh@gmx.net>
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21 | *
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22 | */
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23 |
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24 | #include <arpa/telnet.h>
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25 | #include <netinet/in.h>
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26 | #include "libbb.h"
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27 |
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28 | #ifdef DOTRACE
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29 | #define TRACE(x, y) do { if (x) printf y; } while (0)
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30 | #else
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31 | #define TRACE(x, y)
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32 | #endif
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33 |
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34 | enum {
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35 | DATABUFSIZE = 128,
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36 | IACBUFSIZE = 128,
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37 |
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38 | CHM_TRY = 0,
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39 | CHM_ON = 1,
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40 | CHM_OFF = 2,
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41 |
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42 | UF_ECHO = 0x01,
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43 | UF_SGA = 0x02,
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44 |
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45 | TS_NORMAL = 0,
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46 | TS_COPY = 1,
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47 | TS_IAC = 2,
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48 | TS_OPT = 3,
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49 | TS_SUB1 = 4,
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50 | TS_SUB2 = 5,
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51 | TS_CR = 6,
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52 | };
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53 |
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54 | typedef unsigned char byte;
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55 |
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56 | enum { netfd = 3 };
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57 |
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58 | struct globals {
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59 | int iaclen; /* could even use byte, but it's a loss on x86 */
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60 | byte telstate; /* telnet negotiation state from network input */
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61 | byte telwish; /* DO, DONT, WILL, WONT */
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62 | byte charmode;
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63 | byte telflags;
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64 | byte do_termios;
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65 | #if ENABLE_FEATURE_TELNET_TTYPE
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66 | char *ttype;
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67 | #endif
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68 | #if ENABLE_FEATURE_TELNET_AUTOLOGIN
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69 | const char *autologin;
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70 | #endif
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71 | #if ENABLE_FEATURE_AUTOWIDTH
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72 | unsigned win_width, win_height;
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73 | #endif
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74 | /* same buffer used both for network and console read/write */
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75 | char buf[DATABUFSIZE];
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76 | /* buffer to handle telnet negotiations */
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77 | char iacbuf[IACBUFSIZE];
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78 | struct termios termios_def;
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79 | struct termios termios_raw;
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80 | } FIX_ALIASING;
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81 | #define G (*(struct globals*)&bb_common_bufsiz1)
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82 | #define INIT_G() do { \
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83 | struct G_sizecheck { \
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84 | char G_sizecheck[sizeof(G) > COMMON_BUFSIZE ? -1 : 1]; \
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85 | }; \
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86 | } while (0)
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87 |
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88 |
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89 | static void rawmode(void);
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90 | static void cookmode(void);
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91 | static void do_linemode(void);
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92 | static void will_charmode(void);
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93 | static void telopt(byte c);
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94 | static void subneg(byte c);
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95 |
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96 | static void iac_flush(void)
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97 | {
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98 | write(netfd, G.iacbuf, G.iaclen);
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99 | G.iaclen = 0;
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100 | }
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101 |
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102 | #define write_str(fd, str) write(fd, str, sizeof(str) - 1)
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103 |
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104 | static void doexit(int ev) NORETURN;
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105 | static void doexit(int ev)
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106 | {
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107 | cookmode();
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108 | exit(ev);
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109 | }
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110 |
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111 | static void con_escape(void)
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112 | {
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113 | char b;
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114 |
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115 | if (bb_got_signal) /* came from line mode... go raw */
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116 | rawmode();
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117 |
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118 | write_str(1, "\r\nConsole escape. Commands are:\r\n\n"
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119 | " l go to line mode\r\n"
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120 | " c go to character mode\r\n"
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121 | " z suspend telnet\r\n"
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122 | " e exit telnet\r\n");
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123 |
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124 | if (read(STDIN_FILENO, &b, 1) <= 0)
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125 | doexit(EXIT_FAILURE);
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126 |
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127 | switch (b) {
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128 | case 'l':
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129 | if (!bb_got_signal) {
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130 | do_linemode();
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131 | goto ret;
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132 | }
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133 | break;
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134 | case 'c':
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135 | if (bb_got_signal) {
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136 | will_charmode();
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137 | goto ret;
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138 | }
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139 | break;
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140 | case 'z':
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141 | cookmode();
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142 | kill(0, SIGTSTP);
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143 | rawmode();
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144 | break;
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145 | case 'e':
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146 | doexit(EXIT_SUCCESS);
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147 | }
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148 |
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149 | write_str(1, "continuing...\r\n");
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150 |
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151 | if (bb_got_signal)
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152 | cookmode();
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153 | ret:
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154 | bb_got_signal = 0;
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155 | }
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156 |
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157 | static void handle_net_output(int len)
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158 | {
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159 | /* here we could do smart tricks how to handle 0xFF:s in output
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160 | * stream like writing twice every sequence of FF:s (thus doing
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161 | * many write()s. But I think interactive telnet application does
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162 | * not need to be 100% 8-bit clean, so changing every 0xff:s to
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163 | * 0x7f:s
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164 | *
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165 | * 2002-mar-21, Przemyslaw Czerpak (druzus@polbox.com)
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166 | * I don't agree.
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167 | * first - I cannot use programs like sz/rz
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168 | * second - the 0x0D is sent as one character and if the next
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169 | * char is 0x0A then it's eaten by a server side.
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170 | * third - why do you have to make 'many write()s'?
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171 | * I don't understand.
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172 | * So I implemented it. It's really useful for me. I hope that
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173 | * other people will find it interesting too.
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174 | */
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175 | byte outbuf[2 * DATABUFSIZE];
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176 | byte *p = (byte*)G.buf;
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177 | int j = 0;
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178 |
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179 | for (; len > 0; len--, p++) {
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180 | byte c = *p;
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181 | if (c == 0x1d) {
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182 | con_escape();
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183 | return;
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184 | }
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185 | outbuf[j++] = c;
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186 | if (c == IAC)
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187 | outbuf[j++] = c; /* IAC -> IAC IAC */
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188 | else if (c == '\r')
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189 | outbuf[j++] = '\0'; /* CR -> CR NUL */
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190 | }
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191 | if (j > 0)
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192 | full_write(netfd, outbuf, j);
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193 | }
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194 |
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195 | static void handle_net_input(int len)
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196 | {
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197 | int i;
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198 | int cstart = 0;
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199 |
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200 | for (i = 0; i < len; i++) {
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201 | byte c = G.buf[i];
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202 |
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203 | if (G.telstate == TS_NORMAL) { /* most typical state */
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204 | if (c == IAC) {
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205 | cstart = i;
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206 | G.telstate = TS_IAC;
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207 | }
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208 | else if (c == '\r') {
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209 | cstart = i + 1;
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210 | G.telstate = TS_CR;
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211 | }
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212 | /* No IACs were seen so far, no need to copy
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213 | * bytes within G.buf: */
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214 | continue;
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215 | }
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216 |
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217 | switch (G.telstate) {
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218 | case TS_CR:
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219 | /* Prev char was CR. If cur one is NUL, ignore it.
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220 | * See RFC 1123 section 3.3.1 for discussion of telnet EOL handling.
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221 | */
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222 | G.telstate = TS_COPY;
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223 | if (c == '\0')
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224 | break;
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225 | /* else: fall through - need to handle CR IAC ... properly */
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226 |
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227 | case TS_COPY: /* Prev char was ordinary */
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228 | /* Similar to NORMAL, but in TS_COPY we need to copy bytes */
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229 | if (c == IAC)
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230 | G.telstate = TS_IAC;
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231 | else
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232 | G.buf[cstart++] = c;
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233 | if (c == '\r')
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234 | G.telstate = TS_CR;
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235 | break;
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236 |
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237 | case TS_IAC: /* Prev char was IAC */
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238 | if (c == IAC) { /* IAC IAC -> one IAC */
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239 | G.buf[cstart++] = c;
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240 | G.telstate = TS_COPY;
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241 | break;
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242 | }
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243 | /* else */
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244 | switch (c) {
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245 | case SB:
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246 | G.telstate = TS_SUB1;
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247 | break;
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248 | case DO:
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249 | case DONT:
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250 | case WILL:
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251 | case WONT:
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252 | G.telwish = c;
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253 | G.telstate = TS_OPT;
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254 | break;
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255 | /* DATA MARK must be added later */
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256 | default:
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257 | G.telstate = TS_COPY;
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258 | }
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259 | break;
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260 |
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261 | case TS_OPT: /* Prev chars were IAC WILL/WONT/DO/DONT */
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262 | telopt(c);
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263 | G.telstate = TS_COPY;
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264 | break;
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265 |
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266 | case TS_SUB1: /* Subnegotiation */
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267 | case TS_SUB2: /* Subnegotiation */
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268 | subneg(c); /* can change G.telstate */
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269 | break;
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270 | }
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271 | }
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272 |
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273 | if (G.telstate != TS_NORMAL) {
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274 | /* We had some IACs, or CR */
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275 | if (G.iaclen)
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276 | iac_flush();
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277 | if (G.telstate == TS_COPY) /* we aren't in the middle of IAC */
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278 | G.telstate = TS_NORMAL;
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279 | len = cstart;
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280 | }
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281 |
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282 | if (len)
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283 | full_write(STDOUT_FILENO, G.buf, len);
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284 | }
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285 |
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286 | static void put_iac(int c)
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287 | {
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288 | G.iacbuf[G.iaclen++] = c;
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289 | }
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290 |
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291 | static void put_iac2(byte wwdd, byte c)
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292 | {
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293 | if (G.iaclen + 3 > IACBUFSIZE)
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294 | iac_flush();
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295 |
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296 | put_iac(IAC);
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297 | put_iac(wwdd);
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298 | put_iac(c);
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299 | }
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300 |
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301 | #if ENABLE_FEATURE_TELNET_TTYPE
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302 | static void put_iac_subopt(byte c, char *str)
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303 | {
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304 | int len = strlen(str) + 6; // ( 2 + 1 + 1 + strlen + 2 )
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305 |
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306 | if (G.iaclen + len > IACBUFSIZE)
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307 | iac_flush();
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308 |
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309 | put_iac(IAC);
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310 | put_iac(SB);
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311 | put_iac(c);
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312 | put_iac(0);
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313 |
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314 | while (*str)
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315 | put_iac(*str++);
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316 |
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317 | put_iac(IAC);
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318 | put_iac(SE);
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319 | }
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320 | #endif
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321 |
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322 | #if ENABLE_FEATURE_TELNET_AUTOLOGIN
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323 | static void put_iac_subopt_autologin(void)
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324 | {
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325 | int len = strlen(G.autologin) + 6; // (2 + 1 + 1 + strlen + 2)
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326 | const char *p = "USER";
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327 |
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328 | if (G.iaclen + len > IACBUFSIZE)
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329 | iac_flush();
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330 |
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331 | put_iac(IAC);
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332 | put_iac(SB);
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333 | put_iac(TELOPT_NEW_ENVIRON);
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334 | put_iac(TELQUAL_IS);
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335 | put_iac(NEW_ENV_VAR);
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336 |
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337 | while (*p)
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338 | put_iac(*p++);
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339 |
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340 | put_iac(NEW_ENV_VALUE);
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341 |
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342 | p = G.autologin;
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343 | while (*p)
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344 | put_iac(*p++);
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345 |
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346 | put_iac(IAC);
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347 | put_iac(SE);
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348 | }
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349 | #endif
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350 |
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351 | #if ENABLE_FEATURE_AUTOWIDTH
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352 | static void put_iac_naws(byte c, int x, int y)
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353 | {
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354 | if (G.iaclen + 9 > IACBUFSIZE)
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355 | iac_flush();
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356 |
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357 | put_iac(IAC);
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358 | put_iac(SB);
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359 | put_iac(c);
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360 |
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361 | put_iac((x >> 8) & 0xff);
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362 | put_iac(x & 0xff);
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363 | put_iac((y >> 8) & 0xff);
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364 | put_iac(y & 0xff);
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365 |
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366 | put_iac(IAC);
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367 | put_iac(SE);
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368 | }
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369 | #endif
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370 |
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371 | static char const escapecharis[] ALIGN1 = "\r\nEscape character is ";
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372 |
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373 | static void setConMode(void)
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374 | {
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375 | if (G.telflags & UF_ECHO) {
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376 | if (G.charmode == CHM_TRY) {
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377 | G.charmode = CHM_ON;
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378 | printf("\r\nEntering character mode%s'^]'.\r\n", escapecharis);
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379 | rawmode();
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380 | }
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381 | } else {
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382 | if (G.charmode != CHM_OFF) {
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383 | G.charmode = CHM_OFF;
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384 | printf("\r\nEntering line mode%s'^C'.\r\n", escapecharis);
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385 | cookmode();
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386 | }
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387 | }
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388 | }
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389 |
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390 | static void will_charmode(void)
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391 | {
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392 | G.charmode = CHM_TRY;
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393 | G.telflags |= (UF_ECHO | UF_SGA);
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394 | setConMode();
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395 |
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396 | put_iac2(DO, TELOPT_ECHO);
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397 | put_iac2(DO, TELOPT_SGA);
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398 | iac_flush();
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399 | }
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400 |
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401 | static void do_linemode(void)
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402 | {
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403 | G.charmode = CHM_TRY;
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404 | G.telflags &= ~(UF_ECHO | UF_SGA);
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405 | setConMode();
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406 |
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407 | put_iac2(DONT, TELOPT_ECHO);
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408 | put_iac2(DONT, TELOPT_SGA);
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409 | iac_flush();
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410 | }
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411 |
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412 | static void to_notsup(char c)
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413 | {
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414 | if (G.telwish == WILL)
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415 | put_iac2(DONT, c);
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416 | else if (G.telwish == DO)
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417 | put_iac2(WONT, c);
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418 | }
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419 |
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420 | static void to_echo(void)
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421 | {
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422 | /* if server requests ECHO, don't agree */
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423 | if (G.telwish == DO) {
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424 | put_iac2(WONT, TELOPT_ECHO);
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425 | return;
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426 | }
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427 | if (G.telwish == DONT)
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428 | return;
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429 |
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430 | if (G.telflags & UF_ECHO) {
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431 | if (G.telwish == WILL)
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432 | return;
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433 | } else if (G.telwish == WONT)
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434 | return;
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435 |
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436 | if (G.charmode != CHM_OFF)
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437 | G.telflags ^= UF_ECHO;
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438 |
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439 | if (G.telflags & UF_ECHO)
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440 | put_iac2(DO, TELOPT_ECHO);
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441 | else
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442 | put_iac2(DONT, TELOPT_ECHO);
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443 |
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444 | setConMode();
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445 | full_write1_str("\r\n"); /* sudden modec */
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446 | }
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447 |
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448 | static void to_sga(void)
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449 | {
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450 | /* daemon always sends will/wont, client do/dont */
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451 |
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452 | if (G.telflags & UF_SGA) {
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453 | if (G.telwish == WILL)
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454 | return;
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455 | } else if (G.telwish == WONT)
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456 | return;
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457 |
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458 | G.telflags ^= UF_SGA; /* toggle */
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459 | if (G.telflags & UF_SGA)
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460 | put_iac2(DO, TELOPT_SGA);
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461 | else
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462 | put_iac2(DONT, TELOPT_SGA);
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463 | }
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464 |
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465 | #if ENABLE_FEATURE_TELNET_TTYPE
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466 | static void to_ttype(void)
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467 | {
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468 | /* Tell server we will (or won't) do TTYPE */
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469 | if (G.ttype)
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470 | put_iac2(WILL, TELOPT_TTYPE);
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471 | else
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472 | put_iac2(WONT, TELOPT_TTYPE);
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473 | }
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474 | #endif
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475 |
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476 | #if ENABLE_FEATURE_TELNET_AUTOLOGIN
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477 | static void to_new_environ(void)
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478 | {
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479 | /* Tell server we will (or will not) do AUTOLOGIN */
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480 | if (G.autologin)
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481 | put_iac2(WILL, TELOPT_NEW_ENVIRON);
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482 | else
|
---|
483 | put_iac2(WONT, TELOPT_NEW_ENVIRON);
|
---|
484 | }
|
---|
485 | #endif
|
---|
486 |
|
---|
487 | #if ENABLE_FEATURE_AUTOWIDTH
|
---|
488 | static void to_naws(void)
|
---|
489 | {
|
---|
490 | /* Tell server we will do NAWS */
|
---|
491 | put_iac2(WILL, TELOPT_NAWS);
|
---|
492 | }
|
---|
493 | #endif
|
---|
494 |
|
---|
495 | static void telopt(byte c)
|
---|
496 | {
|
---|
497 | switch (c) {
|
---|
498 | case TELOPT_ECHO:
|
---|
499 | to_echo(); break;
|
---|
500 | case TELOPT_SGA:
|
---|
501 | to_sga(); break;
|
---|
502 | #if ENABLE_FEATURE_TELNET_TTYPE
|
---|
503 | case TELOPT_TTYPE:
|
---|
504 | to_ttype(); break;
|
---|
505 | #endif
|
---|
506 | #if ENABLE_FEATURE_TELNET_AUTOLOGIN
|
---|
507 | case TELOPT_NEW_ENVIRON:
|
---|
508 | to_new_environ(); break;
|
---|
509 | #endif
|
---|
510 | #if ENABLE_FEATURE_AUTOWIDTH
|
---|
511 | case TELOPT_NAWS:
|
---|
512 | to_naws();
|
---|
513 | put_iac_naws(c, G.win_width, G.win_height);
|
---|
514 | break;
|
---|
515 | #endif
|
---|
516 | default:
|
---|
517 | to_notsup(c);
|
---|
518 | break;
|
---|
519 | }
|
---|
520 | }
|
---|
521 |
|
---|
522 | /* subnegotiation -- ignore all (except TTYPE,NAWS) */
|
---|
523 | static void subneg(byte c)
|
---|
524 | {
|
---|
525 | switch (G.telstate) {
|
---|
526 | case TS_SUB1:
|
---|
527 | if (c == IAC)
|
---|
528 | G.telstate = TS_SUB2;
|
---|
529 | #if ENABLE_FEATURE_TELNET_TTYPE
|
---|
530 | else
|
---|
531 | if (c == TELOPT_TTYPE && G.ttype)
|
---|
532 | put_iac_subopt(TELOPT_TTYPE, G.ttype);
|
---|
533 | #endif
|
---|
534 | #if ENABLE_FEATURE_TELNET_AUTOLOGIN
|
---|
535 | else
|
---|
536 | if (c == TELOPT_NEW_ENVIRON && G.autologin)
|
---|
537 | put_iac_subopt_autologin();
|
---|
538 | #endif
|
---|
539 | break;
|
---|
540 | case TS_SUB2:
|
---|
541 | if (c == SE) {
|
---|
542 | G.telstate = TS_COPY;
|
---|
543 | return;
|
---|
544 | }
|
---|
545 | G.telstate = TS_SUB1;
|
---|
546 | break;
|
---|
547 | }
|
---|
548 | }
|
---|
549 |
|
---|
550 | static void rawmode(void)
|
---|
551 | {
|
---|
552 | if (G.do_termios)
|
---|
553 | tcsetattr(0, TCSADRAIN, &G.termios_raw);
|
---|
554 | }
|
---|
555 |
|
---|
556 | static void cookmode(void)
|
---|
557 | {
|
---|
558 | if (G.do_termios)
|
---|
559 | tcsetattr(0, TCSADRAIN, &G.termios_def);
|
---|
560 | }
|
---|
561 |
|
---|
562 | int telnet_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
|
---|
563 | int telnet_main(int argc UNUSED_PARAM, char **argv)
|
---|
564 | {
|
---|
565 | char *host;
|
---|
566 | int port;
|
---|
567 | int len;
|
---|
568 | struct pollfd ufds[2];
|
---|
569 |
|
---|
570 | INIT_G();
|
---|
571 |
|
---|
572 | #if ENABLE_FEATURE_AUTOWIDTH
|
---|
573 | get_terminal_width_height(0, &G.win_width, &G.win_height);
|
---|
574 | #endif
|
---|
575 |
|
---|
576 | #if ENABLE_FEATURE_TELNET_TTYPE
|
---|
577 | G.ttype = getenv("TERM");
|
---|
578 | #endif
|
---|
579 |
|
---|
580 | if (tcgetattr(0, &G.termios_def) >= 0) {
|
---|
581 | G.do_termios = 1;
|
---|
582 | G.termios_raw = G.termios_def;
|
---|
583 | cfmakeraw(&G.termios_raw);
|
---|
584 | }
|
---|
585 |
|
---|
586 | #if ENABLE_FEATURE_TELNET_AUTOLOGIN
|
---|
587 | if (1 & getopt32(argv, "al:", &G.autologin))
|
---|
588 | G.autologin = getenv("USER");
|
---|
589 | argv += optind;
|
---|
590 | #else
|
---|
591 | argv++;
|
---|
592 | #endif
|
---|
593 | if (!*argv)
|
---|
594 | bb_show_usage();
|
---|
595 | host = *argv++;
|
---|
596 | port = bb_lookup_port(*argv ? *argv++ : "telnet", "tcp", 23);
|
---|
597 | if (*argv) /* extra params?? */
|
---|
598 | bb_show_usage();
|
---|
599 |
|
---|
600 | xmove_fd(create_and_connect_stream_or_die(host, port), netfd);
|
---|
601 |
|
---|
602 | setsockopt(netfd, SOL_SOCKET, SO_KEEPALIVE, &const_int_1, sizeof(const_int_1));
|
---|
603 |
|
---|
604 | signal(SIGINT, record_signo);
|
---|
605 |
|
---|
606 | ufds[0].fd = STDIN_FILENO;
|
---|
607 | ufds[0].events = POLLIN;
|
---|
608 | ufds[1].fd = netfd;
|
---|
609 | ufds[1].events = POLLIN;
|
---|
610 |
|
---|
611 | while (1) {
|
---|
612 | if (poll(ufds, 2, -1) < 0) {
|
---|
613 | /* error, ignore and/or log something, bay go to loop */
|
---|
614 | if (bb_got_signal)
|
---|
615 | con_escape();
|
---|
616 | else
|
---|
617 | sleep(1);
|
---|
618 | continue;
|
---|
619 | }
|
---|
620 |
|
---|
621 | // FIXME: reads can block. Need full bidirectional buffering.
|
---|
622 |
|
---|
623 | if (ufds[0].revents) {
|
---|
624 | len = safe_read(STDIN_FILENO, G.buf, DATABUFSIZE);
|
---|
625 | if (len <= 0)
|
---|
626 | doexit(EXIT_SUCCESS);
|
---|
627 | TRACE(0, ("Read con: %d\n", len));
|
---|
628 | handle_net_output(len);
|
---|
629 | }
|
---|
630 |
|
---|
631 | if (ufds[1].revents) {
|
---|
632 | len = safe_read(netfd, G.buf, DATABUFSIZE);
|
---|
633 | if (len <= 0) {
|
---|
634 | full_write1_str("Connection closed by foreign host\r\n");
|
---|
635 | doexit(EXIT_FAILURE);
|
---|
636 | }
|
---|
637 | TRACE(0, ("Read netfd (%d): %d\n", netfd, len));
|
---|
638 | handle_net_input(len);
|
---|
639 | }
|
---|
640 | } /* while (1) */
|
---|
641 | }
|
---|