1 | /* Based on netcat 1.10 RELEASE 960320 written by hobbit@avian.org.
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2 | * Released into public domain by the author.
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3 | *
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4 | * Copyright (C) 2007 Denys Vlasenko.
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5 | *
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6 | * Licensed under GPLv2, see file LICENSE in this source tree.
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7 | */
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8 |
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9 | /* Author's comments from nc 1.10:
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10 | * =====================
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11 | * Netcat is entirely my own creation, although plenty of other code was used as
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12 | * examples. It is freely given away to the Internet community in the hope that
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13 | * it will be useful, with no restrictions except giving credit where it is due.
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14 | * No GPLs, Berkeley copyrights or any of that nonsense. The author assumes NO
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15 | * responsibility for how anyone uses it. If netcat makes you rich somehow and
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16 | * you're feeling generous, mail me a check. If you are affiliated in any way
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17 | * with Microsoft Network, get a life. Always ski in control. Comments,
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18 | * questions, and patches to hobbit@avian.org.
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19 | * ...
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20 | * Netcat and the associated package is a product of Avian Research, and is freely
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21 | * available in full source form with no restrictions save an obligation to give
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22 | * credit where due.
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23 | * ...
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24 | * A damn useful little "backend" utility begun 950915 or thereabouts,
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25 | * as *Hobbit*'s first real stab at some sockets programming. Something that
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26 | * should have and indeed may have existed ten years ago, but never became a
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27 | * standard Unix utility. IMHO, "nc" could take its place right next to cat,
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28 | * cp, rm, mv, dd, ls, and all those other cryptic and Unix-like things.
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29 | * =====================
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30 | *
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31 | * Much of author's comments are still retained in the code.
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32 | *
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33 | * Functionality removed (rationale):
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34 | * - miltiple-port ranges, randomized port scanning (use nmap)
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35 | * - telnet support (use telnet)
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36 | * - source routing
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37 | * - multiple DNS checks
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38 | * Functionalty which is different from nc 1.10:
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39 | * - PROG in '-e PROG' can have ARGS (and options).
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40 | * Because of this -e option must be last.
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41 | //TODO: remove -e incompatibility?
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42 | * - we don't redirect stderr to the network socket for the -e PROG.
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43 | * (PROG can do it itself if needed, but sometimes it is NOT wanted!)
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44 | * - numeric addresses are printed in (), not [] (IPv6 looks better),
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45 | * port numbers are inside (): (1.2.3.4:5678)
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46 | * - network read errors are reported on verbose levels > 1
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47 | * (nc 1.10 treats them as EOF)
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48 | * - TCP connects from wrong ip/ports (if peer ip:port is specified
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49 | * on the command line, but accept() says that it came from different addr)
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50 | * are closed, but we don't exit - we continue to listen/accept.
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51 | * Since bbox 1.22:
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52 | * - nc exits when _both_ stdin and network are closed.
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53 | * This makes these two commands:
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54 | * echo "Yes" | nc 127.0.0.1 1234
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55 | * echo "no" | nc -lp 1234
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56 | * exchange their data _and exit_ instead of being stuck.
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57 | */
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58 |
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59 | /* done in nc.c: #include "libbb.h" */
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60 |
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61 | //usage:#if ENABLE_NC_110_COMPAT
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62 | //usage:
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63 | //usage:#define nc_trivial_usage
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64 | //usage: "[OPTIONS] HOST PORT - connect"
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65 | //usage: IF_NC_SERVER("\n"
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66 | //usage: "nc [OPTIONS] -l -p PORT [HOST] [PORT] - listen"
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67 | //usage: )
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68 | //usage:#define nc_full_usage "\n\n"
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69 | //usage: " -e PROG Run PROG after connect (must be last)"
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70 | //usage: IF_NC_SERVER(
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71 | //usage: "\n -l Listen mode, for inbound connects"
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72 | //usage: "\n -lk With -e, provides persistent server"
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73 | /* -ll does the same as -lk, but its our extension, while -k is BSD'd,
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74 | * presumably more widely known. Therefore we advertise it, not -ll.
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75 | * I would like to drop -ll support, but our "small" nc supports it,
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76 | * and Rob uses it.
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77 | */
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78 | //usage: )
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79 | //usage: "\n -p PORT Local port"
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80 | //usage: "\n -s ADDR Local address"
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81 | //usage: "\n -w SEC Timeout for connects and final net reads"
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82 | //usage: IF_NC_EXTRA(
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83 | //usage: "\n -i SEC Delay interval for lines sent" /* ", ports scanned" */
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84 | //usage: )
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85 | //usage: "\n -n Don't do DNS resolution"
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86 | //usage: "\n -u UDP mode"
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87 | //usage: "\n -v Verbose"
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88 | //usage: IF_NC_EXTRA(
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89 | //usage: "\n -o FILE Hex dump traffic"
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90 | //usage: "\n -z Zero-I/O mode (scanning)"
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91 | //usage: )
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92 | //usage:#endif
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93 |
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94 | /* "\n -r Randomize local and remote ports" */
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95 | /* "\n -g gateway Source-routing hop point[s], up to 8" */
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96 | /* "\n -G num Source-routing pointer: 4, 8, 12, ..." */
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97 | /* "\nport numbers can be individual or ranges: lo-hi [inclusive]" */
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98 |
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99 | /* -e PROG can take ARGS too: "nc ... -e ls -l", but we don't document it
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100 | * in help text: nc 1.10 does not allow that. We don't want to entice
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101 | * users to use this incompatibility */
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102 |
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103 | enum {
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104 | SLEAZE_PORT = 31337, /* for UDP-scan RTT trick, change if ya want */
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105 | BIGSIZ = 8192, /* big buffers */
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106 |
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107 | netfd = 3,
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108 | ofd = 4,
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109 | };
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110 |
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111 | struct globals {
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112 | /* global cmd flags: */
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113 | unsigned o_verbose;
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114 | unsigned o_wait;
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115 | #if ENABLE_NC_EXTRA
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116 | unsigned o_interval;
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117 | #endif
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118 |
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119 | /*int netfd;*/
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120 | /*int ofd;*/ /* hexdump output fd */
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121 | #if ENABLE_LFS
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122 | #define SENT_N_RECV_M "sent %llu, rcvd %llu\n"
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123 | unsigned long long wrote_out; /* total stdout bytes */
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124 | unsigned long long wrote_net; /* total net bytes */
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125 | #else
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126 | #define SENT_N_RECV_M "sent %u, rcvd %u\n"
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127 | unsigned wrote_out; /* total stdout bytes */
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128 | unsigned wrote_net; /* total net bytes */
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129 | #endif
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130 | char *proggie0saved;
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131 | /* ouraddr is never NULL and goes through three states as we progress:
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132 | 1 - local address before bind (IP/port possibly zero)
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133 | 2 - local address after bind (port is nonzero)
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134 | 3 - local address after connect??/recv/accept (IP and port are nonzero) */
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135 | struct len_and_sockaddr *ouraddr;
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136 | /* themaddr is NULL if no peer hostname[:port] specified on command line */
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137 | struct len_and_sockaddr *themaddr;
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138 | /* remend is set after connect/recv/accept to the actual ip:port of peer */
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139 | struct len_and_sockaddr remend;
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140 |
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141 | jmp_buf jbuf; /* timer crud */
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142 |
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143 | char bigbuf_in[BIGSIZ]; /* data buffers */
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144 | char bigbuf_net[BIGSIZ];
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145 | };
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146 |
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147 | #define G (*ptr_to_globals)
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148 | #define wrote_out (G.wrote_out )
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149 | #define wrote_net (G.wrote_net )
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150 | #define ouraddr (G.ouraddr )
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151 | #define themaddr (G.themaddr )
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152 | #define remend (G.remend )
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153 | #define jbuf (G.jbuf )
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154 | #define bigbuf_in (G.bigbuf_in )
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155 | #define bigbuf_net (G.bigbuf_net)
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156 | #define o_verbose (G.o_verbose )
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157 | #define o_wait (G.o_wait )
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158 | #if ENABLE_NC_EXTRA
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159 | #define o_interval (G.o_interval)
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160 | #else
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161 | #define o_interval 0
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162 | #endif
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163 | #define INIT_G() do { \
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164 | SET_PTR_TO_GLOBALS(xzalloc(sizeof(G))); \
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165 | } while (0)
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166 |
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167 |
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168 | /* Must match getopt32 call! */
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169 | enum {
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170 | OPT_n = (1 << 0),
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171 | OPT_p = (1 << 1),
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172 | OPT_s = (1 << 2),
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173 | OPT_u = (1 << 3),
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174 | OPT_v = (1 << 4),
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175 | OPT_w = (1 << 5),
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176 | OPT_l = (1 << 6) * ENABLE_NC_SERVER,
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177 | OPT_k = (1 << 7) * ENABLE_NC_SERVER,
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178 | OPT_i = (1 << (6+2*ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
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179 | OPT_o = (1 << (7+2*ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
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180 | OPT_z = (1 << (8+2*ENABLE_NC_SERVER)) * ENABLE_NC_EXTRA,
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181 | };
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182 |
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183 | #define o_nflag (option_mask32 & OPT_n)
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184 | #define o_udpmode (option_mask32 & OPT_u)
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185 | #if ENABLE_NC_EXTRA
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186 | #define o_ofile (option_mask32 & OPT_o)
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187 | #define o_zero (option_mask32 & OPT_z)
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188 | #else
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189 | #define o_ofile 0
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190 | #define o_zero 0
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191 | #endif
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192 |
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193 | /* Debug: squirt whatever message and sleep a bit so we can see it go by. */
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194 | /* Beware: writes to stdOUT... */
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195 | #if 0
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196 | #define Debug(...) do { printf(__VA_ARGS__); printf("\n"); fflush_all(); sleep(1); } while (0)
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197 | #else
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198 | #define Debug(...) do { } while (0)
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199 | #endif
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200 |
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201 | #define holler_error(...) do { if (o_verbose) bb_error_msg(__VA_ARGS__); } while (0)
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202 | #define holler_perror(...) do { if (o_verbose) bb_perror_msg(__VA_ARGS__); } while (0)
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203 |
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204 | /* catch: no-brainer interrupt handler */
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205 | static void catch(int sig)
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206 | {
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207 | if (o_verbose > 1) /* normally we don't care */
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208 | fprintf(stderr, SENT_N_RECV_M, wrote_net, wrote_out);
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209 | fprintf(stderr, "punt!\n");
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210 | kill_myself_with_sig(sig);
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211 | }
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212 |
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213 | /* unarm */
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214 | static void unarm(void)
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215 | {
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216 | signal(SIGALRM, SIG_IGN);
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217 | alarm(0);
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218 | }
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219 |
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220 | /* timeout and other signal handling cruft */
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221 | static void tmtravel(int sig UNUSED_PARAM)
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222 | {
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223 | unarm();
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224 | longjmp(jbuf, 1);
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225 | }
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226 |
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227 | /* arm: set the timer. */
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228 | static void arm(unsigned secs)
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229 | {
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230 | signal(SIGALRM, tmtravel);
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231 | alarm(secs);
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232 | }
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233 |
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234 | /* findline:
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235 | find the next newline in a buffer; return inclusive size of that "line",
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236 | or the entire buffer size, so the caller knows how much to then write().
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237 | Not distinguishing \n vs \r\n for the nonce; it just works as is... */
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238 | static unsigned findline(char *buf, unsigned siz)
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239 | {
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240 | char * p;
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241 | int x;
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242 | if (!buf) /* various sanity checks... */
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243 | return 0;
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244 | if (siz > BIGSIZ)
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245 | return 0;
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246 | x = siz;
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247 | for (p = buf; x > 0; x--) {
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248 | if (*p == '\n') {
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249 | x = (int) (p - buf);
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250 | x++; /* 'sokay if it points just past the end! */
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251 | Debug("findline returning %d", x);
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252 | return x;
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253 | }
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254 | p++;
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255 | } /* for */
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256 | Debug("findline returning whole thing: %d", siz);
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257 | return siz;
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258 | } /* findline */
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259 |
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260 | /* doexec:
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261 | fiddle all the file descriptors around, and hand off to another prog. Sort
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262 | of like a one-off "poor man's inetd". This is the only section of code
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263 | that would be security-critical, which is why it's ifdefed out by default.
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264 | Use at your own hairy risk; if you leave shells lying around behind open
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265 | listening ports you deserve to lose!! */
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266 | static int doexec(char **proggie) NORETURN;
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267 | static int doexec(char **proggie)
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268 | {
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269 | if (G.proggie0saved)
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270 | proggie[0] = G.proggie0saved;
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271 | xmove_fd(netfd, 0);
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272 | dup2(0, 1);
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273 | /* dup2(0, 2); - do we *really* want this? NO!
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274 | * exec'ed prog can do it yourself, if needed */
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275 | BB_EXECVP_or_die(proggie);
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276 | }
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277 |
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278 | /* connect_w_timeout:
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279 | return an fd for one of
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280 | an open outbound TCP connection, a UDP stub-socket thingie, or
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281 | an unconnected TCP or UDP socket to listen on.
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282 | Examines various global o_blah flags to figure out what to do.
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283 | lad can be NULL, then socket is not bound to any local ip[:port] */
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284 | static int connect_w_timeout(int fd)
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285 | {
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286 | int rr;
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287 |
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288 | /* wrap connect inside a timer, and hit it */
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289 | arm(o_wait);
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290 | if (setjmp(jbuf) == 0) {
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291 | rr = connect(fd, &themaddr->u.sa, themaddr->len);
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292 | unarm();
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293 | } else { /* setjmp: connect failed... */
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294 | rr = -1;
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295 | errno = ETIMEDOUT; /* fake it */
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296 | }
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297 | return rr;
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298 | }
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299 |
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300 | /* dolisten:
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301 | listens for
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302 | incoming and returns an open connection *from* someplace. If we were
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303 | given host/port args, any connections from elsewhere are rejected. This
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304 | in conjunction with local-address binding should limit things nicely... */
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305 | static void dolisten(int is_persistent, char **proggie)
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306 | {
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307 | int rr;
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308 |
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309 | if (!o_udpmode)
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310 | xlisten(netfd, 1); /* TCP: gotta listen() before we can get */
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311 |
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312 | /* Various things that follow temporarily trash bigbuf_net, which might contain
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313 | a copy of any recvfrom()ed packet, but we'll read() another copy later. */
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314 |
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315 | /* I can't believe I have to do all this to get my own goddamn bound address
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316 | and port number. It should just get filled in during bind() or something.
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317 | All this is only useful if we didn't say -p for listening, since if we
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318 | said -p we *know* what port we're listening on. At any rate we won't bother
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319 | with it all unless we wanted to see it, although listening quietly on a
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320 | random unknown port is probably not very useful without "netstat". */
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321 | if (o_verbose) {
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322 | char *addr;
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323 | getsockname(netfd, &ouraddr->u.sa, &ouraddr->len);
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324 | //if (rr < 0)
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325 | // bb_perror_msg_and_die("getsockname after bind");
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326 | addr = xmalloc_sockaddr2dotted(&ouraddr->u.sa);
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327 | fprintf(stderr, "listening on %s ...\n", addr);
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328 | free(addr);
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329 | }
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330 |
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331 | if (o_udpmode) {
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332 | /* UDP is a speeeeecial case -- we have to do I/O *and* get the calling
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333 | party's particulars all at once, listen() and accept() don't apply.
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334 | At least in the BSD universe, however, recvfrom/PEEK is enough to tell
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335 | us something came in, and we can set things up so straight read/write
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336 | actually does work after all. Yow. YMMV on strange platforms! */
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337 |
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338 | /* I'm not completely clear on how this works -- BSD seems to make UDP
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339 | just magically work in a connect()ed context, but we'll undoubtedly run
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340 | into systems this deal doesn't work on. For now, we apparently have to
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341 | issue a connect() on our just-tickled socket so we can write() back.
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342 | Again, why the fuck doesn't it just get filled in and taken care of?!
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343 | This hack is anything but optimal. Basically, if you want your listener
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344 | to also be able to send data back, you need this connect() line, which
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345 | also has the side effect that now anything from a different source or even a
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346 | different port on the other end won't show up and will cause ICMP errors.
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347 | I guess that's what they meant by "connect".
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348 | Let's try to remember what the "U" is *really* for, eh? */
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349 |
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350 | /* If peer address is specified, connect to it */
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351 | remend.len = LSA_SIZEOF_SA;
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352 | if (themaddr) {
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353 | remend = *themaddr;
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354 | xconnect(netfd, &themaddr->u.sa, themaddr->len);
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355 | }
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356 | /* peek first packet and remember peer addr */
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357 | arm(o_wait); /* might as well timeout this, too */
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358 | if (setjmp(jbuf) == 0) { /* do timeout for initial connect */
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359 | /* (*ouraddr) is prefilled with "default" address */
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360 | /* and here we block... */
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361 | rr = recv_from_to(netfd, NULL, 0, MSG_PEEK, /*was bigbuf_net, BIGSIZ*/
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362 | &remend.u.sa, &ouraddr->u.sa, ouraddr->len);
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363 | if (rr < 0)
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364 | bb_perror_msg_and_die("recvfrom");
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365 | unarm();
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366 | } else
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367 | bb_error_msg_and_die("timeout");
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368 | /* Now we learned *to which IP* peer has connected, and we want to anchor
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369 | our socket on it, so that our outbound packets will have correct local IP.
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370 | Unfortunately, bind() on already bound socket will fail now (EINVAL):
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371 | xbind(netfd, &ouraddr->u.sa, ouraddr->len);
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372 | Need to read the packet, save data, close this socket and
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373 | create new one, and bind() it. TODO */
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374 | if (!themaddr)
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375 | xconnect(netfd, &remend.u.sa, ouraddr->len);
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376 | } else {
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377 | /* TCP */
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378 | another:
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379 | arm(o_wait); /* wrap this in a timer, too; 0 = forever */
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380 | if (setjmp(jbuf) == 0) {
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381 | again:
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382 | remend.len = LSA_SIZEOF_SA;
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383 | rr = accept(netfd, &remend.u.sa, &remend.len);
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384 | if (rr < 0)
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385 | bb_perror_msg_and_die("accept");
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386 | if (themaddr) {
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387 | int sv_port, port, r;
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388 |
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389 | sv_port = get_nport(&remend.u.sa); /* save */
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390 | port = get_nport(&themaddr->u.sa);
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391 | if (port == 0) {
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392 | /* "nc -nl -p LPORT RHOST" (w/o RPORT!):
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393 | * we should accept any remote port */
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394 | set_nport(&remend.u.sa, 0); /* blot out remote port# */
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395 | }
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396 | r = memcmp(&remend.u.sa, &themaddr->u.sa, remend.len);
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397 | set_nport(&remend.u.sa, sv_port); /* restore */
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398 | if (r != 0) {
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399 | /* nc 1.10 bails out instead, and its error message
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400 | * is not suppressed by o_verbose */
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401 | if (o_verbose) {
|
---|
402 | char *remaddr = xmalloc_sockaddr2dotted(&remend.u.sa);
|
---|
403 | bb_error_msg("connect from wrong ip/port %s ignored", remaddr);
|
---|
404 | free(remaddr);
|
---|
405 | }
|
---|
406 | close(rr);
|
---|
407 | goto again;
|
---|
408 | }
|
---|
409 | }
|
---|
410 | unarm();
|
---|
411 | } else
|
---|
412 | bb_error_msg_and_die("timeout");
|
---|
413 |
|
---|
414 | if (is_persistent && proggie) {
|
---|
415 | /* -l -k -e PROG */
|
---|
416 | signal(SIGCHLD, SIG_IGN); /* no zombies please */
|
---|
417 | if (xvfork() != 0) {
|
---|
418 | /* parent: go back and accept more connections */
|
---|
419 | close(rr);
|
---|
420 | goto another;
|
---|
421 | }
|
---|
422 | /* child */
|
---|
423 | signal(SIGCHLD, SIG_DFL);
|
---|
424 | }
|
---|
425 |
|
---|
426 | xmove_fd(rr, netfd); /* dump the old socket, here's our new one */
|
---|
427 | /* find out what address the connection was *to* on our end, in case we're
|
---|
428 | doing a listen-on-any on a multihomed machine. This allows one to
|
---|
429 | offer different services via different alias addresses, such as the
|
---|
430 | "virtual web site" hack. */
|
---|
431 | getsockname(netfd, &ouraddr->u.sa, &ouraddr->len);
|
---|
432 | //if (rr < 0)
|
---|
433 | // bb_perror_msg_and_die("getsockname after accept");
|
---|
434 | }
|
---|
435 |
|
---|
436 | if (o_verbose) {
|
---|
437 | char *lcladdr, *remaddr, *remhostname;
|
---|
438 |
|
---|
439 | #if ENABLE_NC_EXTRA && defined(IP_OPTIONS)
|
---|
440 | /* If we can, look for any IP options. Useful for testing the receiving end of
|
---|
441 | such things, and is a good exercise in dealing with it. We do this before
|
---|
442 | the connect message, to ensure that the connect msg is uniformly the LAST
|
---|
443 | thing to emerge after all the intervening crud. Doesn't work for UDP on
|
---|
444 | any machines I've tested, but feel free to surprise me. */
|
---|
445 | char optbuf[40];
|
---|
446 | socklen_t x = sizeof(optbuf);
|
---|
447 |
|
---|
448 | rr = getsockopt(netfd, IPPROTO_IP, IP_OPTIONS, optbuf, &x);
|
---|
449 | if (rr >= 0 && x) { /* we've got options, lessee em... */
|
---|
450 | *bin2hex(bigbuf_net, optbuf, x) = '\0';
|
---|
451 | fprintf(stderr, "IP options: %s\n", bigbuf_net);
|
---|
452 | }
|
---|
453 | #endif
|
---|
454 |
|
---|
455 | /* now check out who it is. We don't care about mismatched DNS names here,
|
---|
456 | but any ADDR and PORT we specified had better fucking well match the caller.
|
---|
457 | Converting from addr to inet_ntoa and back again is a bit of a kludge, but
|
---|
458 | gethostpoop wants a string and there's much gnarlier code out there already,
|
---|
459 | so I don't feel bad.
|
---|
460 | The *real* question is why BFD sockets wasn't designed to allow listens for
|
---|
461 | connections *from* specific hosts/ports, instead of requiring the caller to
|
---|
462 | accept the connection and then reject undesireable ones by closing.
|
---|
463 | In other words, we need a TCP MSG_PEEK. */
|
---|
464 | /* bbox: removed most of it */
|
---|
465 | lcladdr = xmalloc_sockaddr2dotted(&ouraddr->u.sa);
|
---|
466 | remaddr = xmalloc_sockaddr2dotted(&remend.u.sa);
|
---|
467 | remhostname = o_nflag ? remaddr : xmalloc_sockaddr2host(&remend.u.sa);
|
---|
468 | fprintf(stderr, "connect to %s from %s (%s)\n",
|
---|
469 | lcladdr, remhostname, remaddr);
|
---|
470 | free(lcladdr);
|
---|
471 | free(remaddr);
|
---|
472 | if (!o_nflag)
|
---|
473 | free(remhostname);
|
---|
474 | }
|
---|
475 |
|
---|
476 | if (proggie)
|
---|
477 | doexec(proggie);
|
---|
478 | }
|
---|
479 |
|
---|
480 | /* udptest:
|
---|
481 | fire a couple of packets at a UDP target port, just to see if it's really
|
---|
482 | there. On BSD kernels, ICMP host/port-unreachable errors get delivered to
|
---|
483 | our socket as ECONNREFUSED write errors. On SV kernels, we lose; we'll have
|
---|
484 | to collect and analyze raw ICMP ourselves a la satan's probe_udp_ports
|
---|
485 | backend. Guess where one could swipe the appropriate code from...
|
---|
486 |
|
---|
487 | Use the time delay between writes if given, otherwise use the "tcp ping"
|
---|
488 | trick for getting the RTT. [I got that idea from pluvius, and warped it.]
|
---|
489 | Return either the original fd, or clean up and return -1. */
|
---|
490 | #if ENABLE_NC_EXTRA
|
---|
491 | static int udptest(void)
|
---|
492 | {
|
---|
493 | int rr;
|
---|
494 |
|
---|
495 | rr = write(netfd, bigbuf_in, 1);
|
---|
496 | if (rr != 1)
|
---|
497 | bb_perror_msg("udptest first write");
|
---|
498 |
|
---|
499 | if (o_wait)
|
---|
500 | sleep(o_wait); // can be interrupted! while (t) nanosleep(&t)?
|
---|
501 | else {
|
---|
502 | /* use the tcp-ping trick: try connecting to a normally refused port, which
|
---|
503 | causes us to block for the time that SYN gets there and RST gets back.
|
---|
504 | Not completely reliable, but it *does* mostly work. */
|
---|
505 | /* Set a temporary connect timeout, so packet filtration doesnt cause
|
---|
506 | us to hang forever, and hit it */
|
---|
507 | o_wait = 5; /* enough that we'll notice?? */
|
---|
508 | rr = xsocket(ouraddr->u.sa.sa_family, SOCK_STREAM, 0);
|
---|
509 | set_nport(&themaddr->u.sa, htons(SLEAZE_PORT));
|
---|
510 | connect_w_timeout(rr);
|
---|
511 | /* don't need to restore themaddr's port, it's not used anymore */
|
---|
512 | close(rr);
|
---|
513 | o_wait = 0; /* restore */
|
---|
514 | }
|
---|
515 |
|
---|
516 | rr = write(netfd, bigbuf_in, 1);
|
---|
517 | return (rr != 1); /* if rr == 1, return 0 (success) */
|
---|
518 | }
|
---|
519 | #else
|
---|
520 | int udptest(void);
|
---|
521 | #endif
|
---|
522 |
|
---|
523 | /* oprint:
|
---|
524 | Hexdump bytes shoveled either way to a running logfile, in the format:
|
---|
525 | D offset - - - - --- 16 bytes --- - - - - # .... ascii .....
|
---|
526 | where "which" sets the direction indicator, D:
|
---|
527 | 0 -- sent to network, or ">"
|
---|
528 | 1 -- rcvd and printed to stdout, or "<"
|
---|
529 | and "buf" and "n" are data-block and length. If the current block generates
|
---|
530 | a partial line, so be it; we *want* that lockstep indication of who sent
|
---|
531 | what when. Adapted from dgaudet's original example -- but must be ripping
|
---|
532 | *fast*, since we don't want to be too disk-bound... */
|
---|
533 | #if ENABLE_NC_EXTRA
|
---|
534 | static void oprint(int direction, unsigned char *p, unsigned bc)
|
---|
535 | {
|
---|
536 | unsigned obc; /* current "global" offset */
|
---|
537 | unsigned x;
|
---|
538 | unsigned char *op; /* out hexdump ptr */
|
---|
539 | unsigned char *ap; /* out asc-dump ptr */
|
---|
540 | unsigned char stage[100];
|
---|
541 |
|
---|
542 | if (bc == 0)
|
---|
543 | return;
|
---|
544 |
|
---|
545 | obc = wrote_net; /* use the globals! */
|
---|
546 | if (direction == '<')
|
---|
547 | obc = wrote_out;
|
---|
548 | stage[0] = direction;
|
---|
549 | stage[59] = '#'; /* preload separator */
|
---|
550 | stage[60] = ' ';
|
---|
551 |
|
---|
552 | do { /* for chunk-o-data ... */
|
---|
553 | x = 16;
|
---|
554 | if (bc < 16) {
|
---|
555 | /* memset(&stage[bc*3 + 11], ' ', 16*3 - bc*3); */
|
---|
556 | memset(&stage[11], ' ', 16*3);
|
---|
557 | x = bc;
|
---|
558 | }
|
---|
559 | sprintf((char *)&stage[1], " %8.8x ", obc); /* xxx: still slow? */
|
---|
560 | bc -= x; /* fix current count */
|
---|
561 | obc += x; /* fix current offset */
|
---|
562 | op = &stage[11]; /* where hex starts */
|
---|
563 | ap = &stage[61]; /* where ascii starts */
|
---|
564 |
|
---|
565 | do { /* for line of dump, however long ... */
|
---|
566 | *op++ = 0x20 | bb_hexdigits_upcase[*p >> 4];
|
---|
567 | *op++ = 0x20 | bb_hexdigits_upcase[*p & 0x0f];
|
---|
568 | *op++ = ' ';
|
---|
569 | if ((*p > 31) && (*p < 127))
|
---|
570 | *ap = *p; /* printing */
|
---|
571 | else
|
---|
572 | *ap = '.'; /* nonprinting, loose def */
|
---|
573 | ap++;
|
---|
574 | p++;
|
---|
575 | } while (--x);
|
---|
576 | *ap++ = '\n'; /* finish the line */
|
---|
577 | xwrite(ofd, stage, ap - stage);
|
---|
578 | } while (bc);
|
---|
579 | }
|
---|
580 | #else
|
---|
581 | void oprint(int direction, unsigned char *p, unsigned bc);
|
---|
582 | #endif
|
---|
583 |
|
---|
584 | /* readwrite:
|
---|
585 | handle stdin/stdout/network I/O. Bwahaha!! -- the select loop from hell.
|
---|
586 | In this instance, return what might become our exit status. */
|
---|
587 | static int readwrite(void)
|
---|
588 | {
|
---|
589 | int rr;
|
---|
590 | char *zp = zp; /* gcc */ /* stdin buf ptr */
|
---|
591 | char *np = np; /* net-in buf ptr */
|
---|
592 | unsigned rzleft;
|
---|
593 | unsigned rnleft;
|
---|
594 | unsigned netretry; /* net-read retry counter */
|
---|
595 | unsigned fds_open;
|
---|
596 |
|
---|
597 | /* if you don't have all this FD_* macro hair in sys/types.h, you'll have to
|
---|
598 | either find it or do your own bit-bashing: *ding1 |= (1 << fd), etc... */
|
---|
599 | fd_set ding1; /* for select loop */
|
---|
600 | fd_set ding2;
|
---|
601 | FD_ZERO(&ding1);
|
---|
602 | FD_SET(netfd, &ding1);
|
---|
603 | FD_SET(STDIN_FILENO, &ding1);
|
---|
604 | fds_open = 2;
|
---|
605 |
|
---|
606 | netretry = 2;
|
---|
607 | rzleft = rnleft = 0;
|
---|
608 | if (o_interval)
|
---|
609 | sleep(o_interval); /* pause *before* sending stuff, too */
|
---|
610 |
|
---|
611 | /* and now the big ol' select shoveling loop ... */
|
---|
612 | /* nc 1.10 has "while (FD_ISSET(netfd)" here */
|
---|
613 | while (fds_open) {
|
---|
614 | unsigned wretry = 8200; /* net-write sanity counter */
|
---|
615 |
|
---|
616 | ding2 = ding1; /* FD_COPY ain't portable... */
|
---|
617 | /* some systems, notably linux, crap into their select timers on return, so
|
---|
618 | we create a expendable copy and give *that* to select. */
|
---|
619 | if (o_wait) {
|
---|
620 | struct timeval tmp_timer;
|
---|
621 | tmp_timer.tv_sec = o_wait;
|
---|
622 | tmp_timer.tv_usec = 0;
|
---|
623 | /* highest possible fd is netfd (3) */
|
---|
624 | rr = select(netfd+1, &ding2, NULL, NULL, &tmp_timer);
|
---|
625 | } else
|
---|
626 | rr = select(netfd+1, &ding2, NULL, NULL, NULL);
|
---|
627 | if (rr < 0 && errno != EINTR) { /* might have gotten ^Zed, etc */
|
---|
628 | holler_perror("select");
|
---|
629 | close(netfd);
|
---|
630 | return 1;
|
---|
631 | }
|
---|
632 | /* if we have a timeout AND stdin is closed AND we haven't heard anything
|
---|
633 | from the net during that time, assume it's dead and close it too. */
|
---|
634 | if (rr == 0) {
|
---|
635 | if (!FD_ISSET(STDIN_FILENO, &ding1)) {
|
---|
636 | netretry--; /* we actually try a coupla times. */
|
---|
637 | if (!netretry) {
|
---|
638 | if (o_verbose > 1) /* normally we don't care */
|
---|
639 | fprintf(stderr, "net timeout\n");
|
---|
640 | /*close(netfd); - redundant, exit will do it */
|
---|
641 | return 0; /* not an error! */
|
---|
642 | }
|
---|
643 | }
|
---|
644 | } /* select timeout */
|
---|
645 | /* xxx: should we check the exception fds too? The read fds seem to give
|
---|
646 | us the right info, and none of the examples I found bothered. */
|
---|
647 |
|
---|
648 | /* Ding!! Something arrived, go check all the incoming hoppers, net first */
|
---|
649 | if (FD_ISSET(netfd, &ding2)) { /* net: ding! */
|
---|
650 | rr = read(netfd, bigbuf_net, BIGSIZ);
|
---|
651 | if (rr <= 0) {
|
---|
652 | if (rr < 0 && o_verbose > 1) {
|
---|
653 | /* nc 1.10 doesn't do this */
|
---|
654 | bb_perror_msg("net read");
|
---|
655 | }
|
---|
656 | FD_CLR(netfd, &ding1); /* net closed */
|
---|
657 | fds_open--;
|
---|
658 | rzleft = 0; /* can't write anymore: broken pipe */
|
---|
659 | } else {
|
---|
660 | rnleft = rr;
|
---|
661 | np = bigbuf_net;
|
---|
662 | }
|
---|
663 | Debug("got %d from the net, errno %d", rr, errno);
|
---|
664 | } /* net:ding */
|
---|
665 |
|
---|
666 | /* if we're in "slowly" mode there's probably still stuff in the stdin
|
---|
667 | buffer, so don't read unless we really need MORE INPUT! MORE INPUT! */
|
---|
668 | if (rzleft)
|
---|
669 | goto shovel;
|
---|
670 |
|
---|
671 | /* okay, suck more stdin */
|
---|
672 | if (FD_ISSET(STDIN_FILENO, &ding2)) { /* stdin: ding! */
|
---|
673 | rr = read(STDIN_FILENO, bigbuf_in, BIGSIZ);
|
---|
674 | /* Considered making reads here smaller for UDP mode, but 8192-byte
|
---|
675 | mobygrams are kinda fun and exercise the reassembler. */
|
---|
676 | if (rr <= 0) { /* at end, or fukt, or ... */
|
---|
677 | FD_CLR(STDIN_FILENO, &ding1); /* disable stdin */
|
---|
678 | /*close(STDIN_FILENO); - not really necessary */
|
---|
679 | /* Let peer know we have no more data */
|
---|
680 | /* nc 1.10 doesn't do this: */
|
---|
681 | shutdown(netfd, SHUT_WR);
|
---|
682 | fds_open--;
|
---|
683 | } else {
|
---|
684 | rzleft = rr;
|
---|
685 | zp = bigbuf_in;
|
---|
686 | }
|
---|
687 | } /* stdin:ding */
|
---|
688 | shovel:
|
---|
689 | /* now that we've dingdonged all our thingdings, send off the results.
|
---|
690 | Geez, why does this look an awful lot like the big loop in "rsh"? ...
|
---|
691 | not sure if the order of this matters, but write net -> stdout first. */
|
---|
692 |
|
---|
693 | if (rnleft) {
|
---|
694 | rr = write(STDOUT_FILENO, np, rnleft);
|
---|
695 | if (rr > 0) {
|
---|
696 | if (o_ofile) /* log the stdout */
|
---|
697 | oprint('<', (unsigned char *)np, rr);
|
---|
698 | np += rr;
|
---|
699 | rnleft -= rr;
|
---|
700 | wrote_out += rr; /* global count */
|
---|
701 | }
|
---|
702 | Debug("wrote %d to stdout, errno %d", rr, errno);
|
---|
703 | } /* rnleft */
|
---|
704 | if (rzleft) {
|
---|
705 | if (o_interval) /* in "slowly" mode ?? */
|
---|
706 | rr = findline(zp, rzleft);
|
---|
707 | else
|
---|
708 | rr = rzleft;
|
---|
709 | rr = write(netfd, zp, rr); /* one line, or the whole buffer */
|
---|
710 | if (rr > 0) {
|
---|
711 | if (o_ofile) /* log what got sent */
|
---|
712 | oprint('>', (unsigned char *)zp, rr);
|
---|
713 | zp += rr;
|
---|
714 | rzleft -= rr;
|
---|
715 | wrote_net += rr; /* global count */
|
---|
716 | }
|
---|
717 | Debug("wrote %d to net, errno %d", rr, errno);
|
---|
718 | } /* rzleft */
|
---|
719 | if (o_interval) { /* cycle between slow lines, or ... */
|
---|
720 | sleep(o_interval);
|
---|
721 | continue; /* ...with hairy select loop... */
|
---|
722 | }
|
---|
723 | if (rzleft || rnleft) { /* shovel that shit till they ain't */
|
---|
724 | wretry--; /* none left, and get another load */
|
---|
725 | /* net write retries sometimes happen on UDP connections */
|
---|
726 | if (!wretry) { /* is something hung? */
|
---|
727 | holler_error("too many output retries");
|
---|
728 | return 1;
|
---|
729 | }
|
---|
730 | goto shovel;
|
---|
731 | }
|
---|
732 | } /* while (fds_open) */
|
---|
733 |
|
---|
734 | /* XXX: maybe want a more graceful shutdown() here, or screw around with
|
---|
735 | linger times?? I suspect that I don't need to since I'm always doing
|
---|
736 | blocking reads and writes and my own manual "last ditch" efforts to read
|
---|
737 | the net again after a timeout. I haven't seen any screwups yet, but it's
|
---|
738 | not like my test network is particularly busy... */
|
---|
739 | close(netfd);
|
---|
740 | return 0;
|
---|
741 | } /* readwrite */
|
---|
742 |
|
---|
743 | /* main: now we pull it all together... */
|
---|
744 | int nc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
|
---|
745 | int nc_main(int argc UNUSED_PARAM, char **argv)
|
---|
746 | {
|
---|
747 | char *str_p, *str_s;
|
---|
748 | IF_NC_EXTRA(char *str_i, *str_o;)
|
---|
749 | char *themdotted = themdotted; /* for compiler */
|
---|
750 | char **proggie;
|
---|
751 | int x;
|
---|
752 | unsigned cnt_l = 0;
|
---|
753 | unsigned o_lport = 0;
|
---|
754 |
|
---|
755 | INIT_G();
|
---|
756 |
|
---|
757 | /* catch a signal or two for cleanup */
|
---|
758 | bb_signals(0
|
---|
759 | + (1 << SIGINT)
|
---|
760 | + (1 << SIGQUIT)
|
---|
761 | + (1 << SIGTERM)
|
---|
762 | , catch);
|
---|
763 | /* and suppress others... */
|
---|
764 | bb_signals(0
|
---|
765 | #ifdef SIGURG
|
---|
766 | + (1 << SIGURG)
|
---|
767 | #endif
|
---|
768 | + (1 << SIGPIPE) /* important! */
|
---|
769 | , SIG_IGN);
|
---|
770 |
|
---|
771 | proggie = argv;
|
---|
772 | while (*++proggie) {
|
---|
773 | if (strcmp(*proggie, "-e") == 0) {
|
---|
774 | *proggie = NULL;
|
---|
775 | proggie++;
|
---|
776 | goto e_found;
|
---|
777 | }
|
---|
778 | /* -<other_opts>e PROG [ARGS] ? */
|
---|
779 | /* (aboriginal linux uses this form) */
|
---|
780 | if (proggie[0][0] == '-') {
|
---|
781 | char *optpos = *proggie + 1;
|
---|
782 | /* Skip all valid opts w/o params */
|
---|
783 | optpos = optpos + strspn(optpos, "nuv"IF_NC_SERVER("lk")IF_NC_EXTRA("z"));
|
---|
784 | if (*optpos == 'e' && !optpos[1]) {
|
---|
785 | *optpos = '\0';
|
---|
786 | proggie++;
|
---|
787 | G.proggie0saved = *proggie;
|
---|
788 | *proggie = NULL; /* terminate argv for getopt32 */
|
---|
789 | goto e_found;
|
---|
790 | }
|
---|
791 | }
|
---|
792 | }
|
---|
793 | proggie = NULL;
|
---|
794 | e_found:
|
---|
795 |
|
---|
796 | // -g -G -t -r deleted, unimplemented -a deleted too
|
---|
797 | opt_complementary = "?2:vv:ll:w+"; /* max 2 params; -v and -l are counters; -w N */
|
---|
798 | getopt32(argv, "np:s:uvw:" IF_NC_SERVER("lk")
|
---|
799 | IF_NC_EXTRA("i:o:z"),
|
---|
800 | &str_p, &str_s, &o_wait
|
---|
801 | IF_NC_EXTRA(, &str_i, &str_o), &o_verbose IF_NC_SERVER(, &cnt_l));
|
---|
802 | argv += optind;
|
---|
803 | #if ENABLE_NC_EXTRA
|
---|
804 | if (option_mask32 & OPT_i) /* line-interval time */
|
---|
805 | o_interval = xatou_range(str_i, 1, 0xffff);
|
---|
806 | #endif
|
---|
807 | #if ENABLE_NC_SERVER
|
---|
808 | //if (option_mask32 & OPT_l) /* listen mode */
|
---|
809 | if (option_mask32 & OPT_k) /* persistent server mode */
|
---|
810 | cnt_l = 2;
|
---|
811 | #endif
|
---|
812 | //if (option_mask32 & OPT_n) /* numeric-only, no DNS lookups */
|
---|
813 | //if (option_mask32 & OPT_o) /* hexdump log */
|
---|
814 | if (option_mask32 & OPT_p) { /* local source port */
|
---|
815 | o_lport = bb_lookup_port(str_p, o_udpmode ? "udp" : "tcp", 0);
|
---|
816 | if (!o_lport)
|
---|
817 | bb_error_msg_and_die("bad local port '%s'", str_p);
|
---|
818 | }
|
---|
819 | //if (option_mask32 & OPT_r) /* randomize various things */
|
---|
820 | //if (option_mask32 & OPT_u) /* use UDP */
|
---|
821 | //if (option_mask32 & OPT_v) /* verbose */
|
---|
822 | //if (option_mask32 & OPT_w) /* wait time */
|
---|
823 | //if (option_mask32 & OPT_z) /* little or no data xfer */
|
---|
824 |
|
---|
825 | /* We manage our fd's so that they are never 0,1,2 */
|
---|
826 | /*bb_sanitize_stdio(); - not needed */
|
---|
827 |
|
---|
828 | if (argv[0]) {
|
---|
829 | themaddr = xhost2sockaddr(argv[0],
|
---|
830 | argv[1]
|
---|
831 | ? bb_lookup_port(argv[1], o_udpmode ? "udp" : "tcp", 0)
|
---|
832 | : 0);
|
---|
833 | }
|
---|
834 |
|
---|
835 | /* create & bind network socket */
|
---|
836 | x = (o_udpmode ? SOCK_DGRAM : SOCK_STREAM);
|
---|
837 | if (option_mask32 & OPT_s) { /* local address */
|
---|
838 | /* if o_lport is still 0, then we will use random port */
|
---|
839 | ouraddr = xhost2sockaddr(str_s, o_lport);
|
---|
840 | #ifdef BLOAT
|
---|
841 | /* prevent spurious "UDP listen needs !0 port" */
|
---|
842 | o_lport = get_nport(ouraddr);
|
---|
843 | o_lport = ntohs(o_lport);
|
---|
844 | #endif
|
---|
845 | x = xsocket(ouraddr->u.sa.sa_family, x, 0);
|
---|
846 | } else {
|
---|
847 | /* We try IPv6, then IPv4, unless addr family is
|
---|
848 | * implicitly set by way of remote addr/port spec */
|
---|
849 | x = xsocket_type(&ouraddr,
|
---|
850 | (themaddr ? themaddr->u.sa.sa_family : AF_UNSPEC),
|
---|
851 | x);
|
---|
852 | if (o_lport)
|
---|
853 | set_nport(&ouraddr->u.sa, htons(o_lport));
|
---|
854 | }
|
---|
855 | xmove_fd(x, netfd);
|
---|
856 | setsockopt_reuseaddr(netfd);
|
---|
857 | if (o_udpmode)
|
---|
858 | socket_want_pktinfo(netfd);
|
---|
859 | if (!ENABLE_FEATURE_UNIX_LOCAL
|
---|
860 | || cnt_l != 0 /* listen */
|
---|
861 | || ouraddr->u.sa.sa_family != AF_UNIX
|
---|
862 | ) {
|
---|
863 | xbind(netfd, &ouraddr->u.sa, ouraddr->len);
|
---|
864 | }
|
---|
865 | #if 0
|
---|
866 | setsockopt_SOL_SOCKET_int(netfd, SO_RCVBUF, o_rcvbuf);
|
---|
867 | setsockopt_SOL_SOCKET_int(netfd, SO_SNDBUF, o_sndbuf);
|
---|
868 | #endif
|
---|
869 |
|
---|
870 | #ifdef BLOAT
|
---|
871 | if (OPT_l && (option_mask32 & (OPT_u|OPT_l)) == (OPT_u|OPT_l)) {
|
---|
872 | /* apparently UDP can listen ON "port 0",
|
---|
873 | but that's not useful */
|
---|
874 | if (!o_lport)
|
---|
875 | bb_error_msg_and_die("UDP listen needs nonzero -p port");
|
---|
876 | }
|
---|
877 | #endif
|
---|
878 |
|
---|
879 | if (proggie) {
|
---|
880 | close(STDIN_FILENO); /* won't need stdin */
|
---|
881 | option_mask32 &= ~OPT_o; /* -o with -e is meaningless! */
|
---|
882 | }
|
---|
883 | #if ENABLE_NC_EXTRA
|
---|
884 | if (o_ofile)
|
---|
885 | xmove_fd(xopen(str_o, O_WRONLY|O_CREAT|O_TRUNC), ofd);
|
---|
886 | #endif
|
---|
887 |
|
---|
888 | if (cnt_l != 0) {
|
---|
889 | dolisten((cnt_l - 1), proggie);
|
---|
890 | /* dolisten does its own connect reporting */
|
---|
891 | x = readwrite(); /* it even works with UDP! */
|
---|
892 | } else {
|
---|
893 | /* Outbound connects. Now we're more picky about args... */
|
---|
894 | if (!themaddr)
|
---|
895 | bb_show_usage();
|
---|
896 |
|
---|
897 | remend = *themaddr;
|
---|
898 | if (o_verbose)
|
---|
899 | themdotted = xmalloc_sockaddr2dotted(&themaddr->u.sa);
|
---|
900 |
|
---|
901 | x = connect_w_timeout(netfd);
|
---|
902 | if (o_zero && x == 0 && o_udpmode) /* if UDP scanning... */
|
---|
903 | x = udptest();
|
---|
904 | if (x == 0) { /* Yow, are we OPEN YET?! */
|
---|
905 | if (o_verbose)
|
---|
906 | fprintf(stderr, "%s (%s) open\n", argv[0], themdotted);
|
---|
907 | if (proggie) /* exec is valid for outbound, too */
|
---|
908 | doexec(proggie);
|
---|
909 | if (!o_zero)
|
---|
910 | x = readwrite();
|
---|
911 | } else { /* connect or udptest wasn't successful */
|
---|
912 | x = 1; /* exit status */
|
---|
913 | /* if we're scanning at a "one -v" verbosity level, don't print refusals.
|
---|
914 | Give it another -v if you want to see everything. */
|
---|
915 | if (o_verbose > 1 || (o_verbose && errno != ECONNREFUSED))
|
---|
916 | bb_perror_msg("%s (%s)", argv[0], themdotted);
|
---|
917 | }
|
---|
918 | }
|
---|
919 | if (o_verbose > 1) /* normally we don't care */
|
---|
920 | fprintf(stderr, SENT_N_RECV_M, wrote_net, wrote_out);
|
---|
921 | return x;
|
---|
922 | }
|
---|