1 | /* vi: set sw=4 ts=4: */
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2 | /* nc: mini-netcat - built from the ground up for LRP
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3 | *
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4 | * Copyright (C) 1998, 1999 Charles P. Wright
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5 | * Copyright (C) 1998 Dave Cinege
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6 | *
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7 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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8 | */
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9 |
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10 | #include "libbb.h"
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11 |
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12 | //config:config NC
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13 | //config: bool "nc"
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14 | //config: default y
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15 | //config: help
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16 | //config: A simple Unix utility which reads and writes data across network
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17 | //config: connections.
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18 | //config:
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19 | //config:config NC_SERVER
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20 | //config: bool "Netcat server options (-l)"
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21 | //config: default y
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22 | //config: depends on NC
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23 | //config: help
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24 | //config: Allow netcat to act as a server.
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25 | //config:
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26 | //config:config NC_EXTRA
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27 | //config: bool "Netcat extensions (-eiw and filename)"
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28 | //config: default y
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29 | //config: depends on NC
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30 | //config: help
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31 | //config: Add -e (support for executing the rest of the command line after
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32 | //config: making or receiving a successful connection), -i (delay interval for
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33 | //config: lines sent), -w (timeout for initial connection).
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34 | //config:
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35 | //config:config NC_110_COMPAT
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36 | //config: bool "Netcat 1.10 compatibility (+2.5k)"
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37 | //config: default n # off specially for Rob
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38 | //config: depends on NC
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39 | //config: help
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40 | //config: This option makes nc closely follow original nc-1.10.
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41 | //config: The code is about 2.5k bigger. It enables
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42 | //config: -s ADDR, -n, -u, -v, -o FILE, -z options, but loses
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43 | //config: busybox-specific extensions: -f FILE and -ll.
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44 |
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45 | #if ENABLE_NC_110_COMPAT
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46 | # include "nc_bloaty.c"
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47 | #else
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48 |
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49 | //usage:#if !ENABLE_NC_110_COMPAT
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50 | //usage:
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51 | //usage:#if ENABLE_NC_SERVER || ENABLE_NC_EXTRA
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52 | //usage:#define NC_OPTIONS_STR "\n\nOptions:"
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53 | //usage:#else
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54 | //usage:#define NC_OPTIONS_STR
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55 | //usage:#endif
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56 | //usage:
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57 | //usage:#define nc_trivial_usage
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58 | //usage: IF_NC_EXTRA("[-iN] [-wN] ")IF_NC_SERVER("[-l] [-p PORT] ")
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59 | //usage: "["IF_NC_EXTRA("-f FILE|")"IPADDR PORT]"IF_NC_EXTRA(" [-e PROG]")
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60 | //usage:#define nc_full_usage "\n\n"
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61 | //usage: "Open a pipe to IP:PORT" IF_NC_EXTRA(" or FILE")
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62 | //usage: NC_OPTIONS_STR
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63 | //usage: IF_NC_EXTRA(
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64 | //usage: "\n -e PROG Run PROG after connect"
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65 | //usage: IF_NC_SERVER(
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66 | //usage: "\n -l Listen mode, for inbound connects"
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67 | //usage: IF_NC_EXTRA(
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68 | //usage: "\n (use -l twice with -e for persistent server)")
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69 | //usage: "\n -p PORT Local port"
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70 | //usage: )
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71 | //usage: "\n -w SEC Timeout for connect"
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72 | //usage: "\n -i SEC Delay interval for lines sent"
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73 | //usage: "\n -f FILE Use file (ala /dev/ttyS0) instead of network"
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74 | //usage: )
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75 | //usage:
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76 | //usage:#define nc_notes_usage ""
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77 | //usage: IF_NC_EXTRA(
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78 | //usage: "To use netcat as a terminal emulator on a serial port:\n\n"
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79 | //usage: "$ stty 115200 -F /dev/ttyS0\n"
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80 | //usage: "$ stty raw -echo -ctlecho && nc -f /dev/ttyS0\n"
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81 | //usage: )
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82 | //usage:
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83 | //usage:#define nc_example_usage
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84 | //usage: "$ nc foobar.somedomain.com 25\n"
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85 | //usage: "220 foobar ESMTP Exim 3.12 #1 Sat, 15 Apr 2000 00:03:02 -0600\n"
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86 | //usage: "help\n"
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87 | //usage: "214-Commands supported:\n"
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88 | //usage: "214- HELO EHLO MAIL RCPT DATA AUTH\n"
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89 | //usage: "214 NOOP QUIT RSET HELP\n"
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90 | //usage: "quit\n"
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91 | //usage: "221 foobar closing connection\n"
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92 | //usage:
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93 | //usage:#endif
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94 |
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95 | /* Lots of small differences in features
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96 | * when compared to "standard" nc
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97 | */
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98 |
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99 | static void timeout(int signum UNUSED_PARAM)
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100 | {
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101 | bb_error_msg_and_die("timed out");
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102 | }
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103 |
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104 | int nc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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105 | int nc_main(int argc, char **argv)
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106 | {
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107 | /* sfd sits _here_ only because of "repeat" option (-l -l). */
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108 | int sfd = sfd; /* for gcc */
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109 | int cfd = 0;
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110 | unsigned lport = 0;
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111 | IF_NOT_NC_SERVER(const) unsigned do_listen = 0;
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112 | IF_NOT_NC_EXTRA (const) unsigned wsecs = 0;
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113 | IF_NOT_NC_EXTRA (const) unsigned delay = 0;
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114 | IF_NOT_NC_EXTRA (const int execparam = 0;)
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115 | IF_NC_EXTRA (char **execparam = NULL;)
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116 | fd_set readfds, testfds;
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117 | int opt; /* must be signed (getopt returns -1) */
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118 |
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119 | if (ENABLE_NC_SERVER || ENABLE_NC_EXTRA) {
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120 | /* getopt32 is _almost_ usable:
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121 | ** it cannot handle "... -e PROG -prog-opt" */
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122 | while ((opt = getopt(argc, argv,
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123 | "" IF_NC_SERVER("lp:") IF_NC_EXTRA("w:i:f:e:") )) > 0
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124 | ) {
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125 | if (ENABLE_NC_SERVER && opt == 'l')
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126 | IF_NC_SERVER(do_listen++);
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127 | else if (ENABLE_NC_SERVER && opt == 'p')
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128 | IF_NC_SERVER(lport = bb_lookup_port(optarg, "tcp", 0));
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129 | else if (ENABLE_NC_EXTRA && opt == 'w')
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130 | IF_NC_EXTRA( wsecs = xatou(optarg));
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131 | else if (ENABLE_NC_EXTRA && opt == 'i')
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132 | IF_NC_EXTRA( delay = xatou(optarg));
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133 | else if (ENABLE_NC_EXTRA && opt == 'f')
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134 | IF_NC_EXTRA( cfd = xopen(optarg, O_RDWR));
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135 | else if (ENABLE_NC_EXTRA && opt == 'e' && optind <= argc) {
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136 | /* We cannot just 'break'. We should let getopt finish.
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137 | ** Or else we won't be able to find where
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138 | ** 'host' and 'port' params are
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139 | ** (think "nc -w 60 host port -e PROG"). */
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140 | IF_NC_EXTRA(
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141 | char **p;
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142 | // +2: one for progname (optarg) and one for NULL
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143 | execparam = xzalloc(sizeof(char*) * (argc - optind + 2));
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144 | p = execparam;
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145 | *p++ = optarg;
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146 | while (optind < argc) {
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147 | *p++ = argv[optind++];
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148 | }
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149 | )
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150 | /* optind points to argv[arvc] (NULL) now.
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151 | ** FIXME: we assume that getopt will not count options
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152 | ** possibly present on "-e PROG ARGS" and will not
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153 | ** include them into final value of optind
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154 | ** which is to be used ... */
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155 | } else bb_show_usage();
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156 | }
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157 | argv += optind; /* ... here! */
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158 | argc -= optind;
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159 | // -l and -f don't mix
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160 | if (do_listen && cfd) bb_show_usage();
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161 | // File mode needs need zero arguments, listen mode needs zero or one,
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162 | // client mode needs one or two
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163 | if (cfd) {
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164 | if (argc) bb_show_usage();
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165 | } else if (do_listen) {
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166 | if (argc > 1) bb_show_usage();
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167 | } else {
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168 | if (!argc || argc > 2) bb_show_usage();
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169 | }
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170 | } else {
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171 | if (argc != 3) bb_show_usage();
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172 | argc--;
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173 | argv++;
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174 | }
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175 |
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176 | if (wsecs) {
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177 | signal(SIGALRM, timeout);
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178 | alarm(wsecs);
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179 | }
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180 |
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181 | if (!cfd) {
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182 | if (do_listen) {
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183 | sfd = create_and_bind_stream_or_die(argv[0], lport);
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184 | xlisten(sfd, do_listen); /* can be > 1 */
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185 | #if 0 /* nc-1.10 does not do this (without -v) */
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186 | /* If we didn't specify a port number,
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187 | * query and print it after listen() */
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188 | if (!lport) {
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189 | len_and_sockaddr lsa;
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190 | lsa.len = LSA_SIZEOF_SA;
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191 | getsockname(sfd, &lsa.u.sa, &lsa.len);
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192 | lport = get_nport(&lsa.u.sa);
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193 | fdprintf(2, "%d\n", ntohs(lport));
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194 | }
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195 | #endif
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196 | close_on_exec_on(sfd);
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197 | accept_again:
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198 | cfd = accept(sfd, NULL, 0);
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199 | if (cfd < 0)
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200 | bb_perror_msg_and_die("accept");
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201 | if (!execparam)
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202 | close(sfd);
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203 | } else {
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204 | cfd = create_and_connect_stream_or_die(argv[0],
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205 | argv[1] ? bb_lookup_port(argv[1], "tcp", 0) : 0);
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206 | }
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207 | }
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208 |
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209 | if (wsecs) {
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210 | alarm(0);
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211 | /* Non-ignored signals revert to SIG_DFL on exec anyway */
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212 | /*signal(SIGALRM, SIG_DFL);*/
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213 | }
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214 |
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215 | /* -e given? */
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216 | if (execparam) {
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217 | pid_t pid;
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218 | /* With more than one -l, repeatedly act as server */
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219 | if (do_listen > 1 && (pid = xvfork()) != 0) {
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220 | /* parent */
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221 | /* prevent zombies */
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222 | signal(SIGCHLD, SIG_IGN);
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223 | close(cfd);
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224 | goto accept_again;
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225 | }
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226 | /* child, or main thread if only one -l */
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227 | xmove_fd(cfd, 0);
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228 | xdup2(0, 1);
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229 | xdup2(0, 2);
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230 | IF_NC_EXTRA(BB_EXECVP(execparam[0], execparam);)
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231 | /* Don't print stuff or it will go over the wire... */
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232 | _exit(127);
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233 | }
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234 |
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235 | /* Select loop copying stdin to cfd, and cfd to stdout */
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236 |
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237 | FD_ZERO(&readfds);
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238 | FD_SET(cfd, &readfds);
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239 | FD_SET(STDIN_FILENO, &readfds);
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240 |
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241 | for (;;) {
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242 | int fd;
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243 | int ofd;
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244 | int nread;
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245 |
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246 | testfds = readfds;
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247 |
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248 | if (select(cfd + 1, &testfds, NULL, NULL, NULL) < 0)
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249 | bb_perror_msg_and_die("select");
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250 |
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251 | #define iobuf bb_common_bufsiz1
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252 | fd = STDIN_FILENO;
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253 | while (1) {
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254 | if (FD_ISSET(fd, &testfds)) {
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255 | nread = safe_read(fd, iobuf, sizeof(iobuf));
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256 | if (fd == cfd) {
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257 | if (nread < 1)
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258 | exit(EXIT_SUCCESS);
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259 | ofd = STDOUT_FILENO;
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260 | } else {
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261 | if (nread < 1) {
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262 | /* Close outgoing half-connection so they get EOF,
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263 | * but leave incoming alone so we can see response */
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264 | shutdown(cfd, 1);
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265 | FD_CLR(STDIN_FILENO, &readfds);
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266 | }
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267 | ofd = cfd;
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268 | }
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269 | xwrite(ofd, iobuf, nread);
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270 | if (delay > 0)
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271 | sleep(delay);
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272 | }
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273 | if (fd == cfd)
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274 | break;
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275 | fd = cfd;
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276 | }
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277 | }
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278 | }
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279 | #endif
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