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 | Copyright (C) 1998 Charles P. Wright
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4 |
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5 | 0.0.1 6K It works.
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6 | 0.0.2 5K Smaller and you can also check the exit condition if you wish.
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7 | 0.0.3 Uses select()
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8 |
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9 | 19980918 Busy Boxed! Dave Cinege
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10 | 19990512 Uses Select. Charles P. Wright
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11 | 19990513 Fixes stdin stupidity and uses buffers. Charles P. Wright
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12 |
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13 | Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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14 | */
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15 |
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16 | #include <stdio.h>
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17 | #include <stdlib.h>
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18 | #include <string.h>
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19 | #include <unistd.h>
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20 | #include <signal.h>
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21 |
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22 | #include <sys/types.h>
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23 | #include <sys/socket.h>
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24 | #include <netinet/in.h>
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25 | #include <arpa/inet.h>
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26 | #include <netdb.h>
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27 | #include <sys/ioctl.h>
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28 | #include "busybox.h"
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29 |
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30 | static void timeout(int signum)
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31 | {
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32 | bb_error_msg_and_die("Timed out");
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33 | }
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34 |
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35 | int nc_main(int argc, char **argv)
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36 | {
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37 | int do_listen = 0, lport = 0, delay = 0, wsecs = 0, tmpfd, opt, sfd, x;
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38 |
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39 | #ifdef CONFIG_NC_GAPING_SECURITY_HOLE
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40 | char *pr00gie = NULL;
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41 | #endif
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42 |
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43 | struct sockaddr_in address;
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44 | struct hostent *hostinfo;
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45 |
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46 | fd_set readfds, testfds;
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47 |
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48 | while ((opt = getopt(argc, argv, "lp:i:e:w:")) > 0) {
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49 | switch (opt) {
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50 | case 'l':
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51 | do_listen++;
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52 | break;
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53 | case 'p':
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54 | lport = bb_lookup_port(optarg, "tcp", 0);
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55 | break;
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56 | case 'i':
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57 | delay = atoi(optarg);
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58 | break;
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59 | #ifdef CONFIG_NC_GAPING_SECURITY_HOLE
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60 | case 'e':
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61 | pr00gie = optarg;
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62 | break;
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63 | #endif
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64 | case 'w':
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65 | wsecs = atoi(optarg);
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66 | break;
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67 | default:
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68 | bb_show_usage();
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69 | }
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70 | }
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71 |
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72 | if ((do_listen && optind != argc) || (!do_listen && optind + 2 != argc))
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73 | bb_show_usage();
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74 |
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75 | sfd = bb_xsocket(AF_INET, SOCK_STREAM, 0);
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76 | x = 1;
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77 | if (setsockopt(sfd, SOL_SOCKET, SO_REUSEADDR, &x, sizeof (x)) == -1)
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78 | bb_perror_msg_and_die("reuseaddr");
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79 | address.sin_family = AF_INET;
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80 |
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81 | if (wsecs) {
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82 | signal(SIGALRM, timeout);
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83 | alarm(wsecs);
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84 | }
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85 |
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86 | if (lport != 0) {
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87 | memset(&address.sin_addr, 0, sizeof(address.sin_addr));
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88 | address.sin_port = lport;
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89 |
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90 | bb_xbind(sfd, (struct sockaddr *) &address, sizeof(address));
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91 | }
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92 |
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93 | if (do_listen) {
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94 | socklen_t addrlen = sizeof(address);
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95 |
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96 | bb_xlisten(sfd, 1);
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97 | if ((tmpfd = accept(sfd, (struct sockaddr *) &address, &addrlen)) < 0)
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98 | bb_perror_msg_and_die("accept");
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99 |
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100 | close(sfd);
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101 | sfd = tmpfd;
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102 | } else {
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103 | hostinfo = xgethostbyname(argv[optind]);
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104 |
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105 | address.sin_addr = *(struct in_addr *) *hostinfo->h_addr_list;
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106 | address.sin_port = bb_lookup_port(argv[optind+1], "tcp", 0);
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107 |
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108 | if (connect(sfd, (struct sockaddr *) &address, sizeof(address)) < 0)
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109 | bb_perror_msg_and_die("connect");
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110 | }
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111 |
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112 | if (wsecs) {
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113 | alarm(0);
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114 | signal(SIGALRM, SIG_DFL);
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115 | }
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116 |
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117 | #ifdef CONFIG_NC_GAPING_SECURITY_HOLE
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118 | /* -e given? */
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119 | if (pr00gie) {
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120 | dup2(sfd, 0);
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121 | close(sfd);
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122 | dup2(0, 1);
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123 | dup2(0, 2);
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124 | execl(pr00gie, pr00gie, NULL);
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125 | /* Don't print stuff or it will go over the wire.... */
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126 | _exit(-1);
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127 | }
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128 | #endif /* CONFIG_NC_GAPING_SECURITY_HOLE */
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129 |
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130 | FD_ZERO(&readfds);
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131 | FD_SET(sfd, &readfds);
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132 | FD_SET(STDIN_FILENO, &readfds);
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133 |
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134 | while (1) {
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135 | int fd;
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136 | int ofd;
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137 | int nread;
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138 |
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139 | testfds = readfds;
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140 |
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141 | if (select(FD_SETSIZE, &testfds, NULL, NULL, NULL) < 0)
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142 | bb_perror_msg_and_die("select");
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143 |
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144 | for (fd = 0; fd < FD_SETSIZE; fd++) {
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145 | if (FD_ISSET(fd, &testfds)) {
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146 | if ((nread = safe_read(fd, bb_common_bufsiz1,
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147 | sizeof(bb_common_bufsiz1))) < 0)
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148 | {
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149 | bb_perror_msg_and_die(bb_msg_read_error);
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150 | }
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151 |
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152 | if (fd == sfd) {
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153 | if (nread == 0)
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154 | exit(0);
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155 | ofd = STDOUT_FILENO;
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156 | } else {
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157 | if (nread <= 0) {
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158 | shutdown(sfd, 1 /* send */ );
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159 | close(STDIN_FILENO);
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160 | FD_CLR(STDIN_FILENO, &readfds);
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161 | }
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162 | ofd = sfd;
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163 | }
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164 |
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165 | if (bb_full_write(ofd, bb_common_bufsiz1, nread) < 0)
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166 | bb_perror_msg_and_die(bb_msg_write_error);
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167 | if (delay > 0) {
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168 | sleep(delay);
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169 | }
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170 | }
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171 | }
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172 | }
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173 | }
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