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 tarball for details.
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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 | #if ENABLE_DESKTOP
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13 | #include "nc_bloaty.c"
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14 | #else
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15 |
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16 | /* Lots of small differences in features
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17 | * when compared to "standard" nc
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18 | */
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19 |
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20 | static void timeout(int signum)
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21 | {
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22 | bb_error_msg_and_die("timed out");
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23 | }
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24 |
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25 | int nc_main(int argc, char **argv);
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26 | int nc_main(int argc, char **argv)
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27 | {
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28 | /* sfd sits _here_ only because of "repeat" option (-l -l). */
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29 | int sfd = sfd; /* for gcc */
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30 | int cfd = 0;
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31 | unsigned lport = 0;
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32 | SKIP_NC_SERVER(const) unsigned do_listen = 0;
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33 | SKIP_NC_EXTRA (const) unsigned wsecs = 0;
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34 | SKIP_NC_EXTRA (const) unsigned delay = 0;
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35 | SKIP_NC_EXTRA (const int execparam = 0;)
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36 | USE_NC_EXTRA (char **execparam = NULL;)
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37 | len_and_sockaddr *lsa;
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38 | fd_set readfds, testfds;
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39 | int opt; /* must be signed (getopt returns -1) */
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40 |
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41 | if (ENABLE_NC_SERVER || ENABLE_NC_EXTRA) {
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42 | /* getopt32 is _almost_ usable:
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43 | ** it cannot handle "... -e prog -prog-opt" */
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44 | while ((opt = getopt(argc, argv,
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45 | "" USE_NC_SERVER("lp:") USE_NC_EXTRA("w:i:f:e:") )) > 0
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46 | ) {
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47 | if (ENABLE_NC_SERVER && opt=='l') USE_NC_SERVER(do_listen++);
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48 | else if (ENABLE_NC_SERVER && opt=='p') {
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49 | USE_NC_SERVER(lport = bb_lookup_port(optarg, "tcp", 0));
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50 | }
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51 | else if (ENABLE_NC_EXTRA && opt=='w') USE_NC_EXTRA( wsecs = xatou(optarg));
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52 | else if (ENABLE_NC_EXTRA && opt=='i') USE_NC_EXTRA( delay = xatou(optarg));
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53 | else if (ENABLE_NC_EXTRA && opt=='f') USE_NC_EXTRA( cfd = xopen(optarg, O_RDWR));
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54 | else if (ENABLE_NC_EXTRA && opt=='e' && optind<=argc) {
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55 | /* We cannot just 'break'. We should let getopt finish.
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56 | ** Or else we won't be able to find where
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57 | ** 'host' and 'port' params are
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58 | ** (think "nc -w 60 host port -e prog"). */
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59 | USE_NC_EXTRA(
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60 | char **p;
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61 | // +2: one for progname (optarg) and one for NULL
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62 | execparam = xzalloc(sizeof(char*) * (argc - optind + 2));
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63 | p = execparam;
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64 | *p++ = optarg;
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65 | while (optind < argc) {
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66 | *p++ = argv[optind++];
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67 | }
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68 | )
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69 | /* optind points to argv[arvc] (NULL) now.
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70 | ** FIXME: we assume that getopt will not count options
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71 | ** possibly present on "-e prog args" and will not
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72 | ** include them into final value of optind
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73 | ** which is to be used ... */
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74 | } else bb_show_usage();
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75 | }
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76 | argv += optind; /* ... here! */
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77 | argc -= optind;
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78 | // -l and -f don't mix
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79 | if (do_listen && cfd) bb_show_usage();
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80 | // Listen or file modes need zero arguments, client mode needs 2
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81 | if (do_listen || cfd) {
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82 | if (argc) bb_show_usage();
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83 | } else {
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84 | if (!argc || argc > 2) bb_show_usage();
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85 | }
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86 | } else {
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87 | if (argc != 3) bb_show_usage();
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88 | argc--;
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89 | argv++;
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90 | }
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91 |
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92 | if (wsecs) {
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93 | signal(SIGALRM, timeout);
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94 | alarm(wsecs);
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95 | }
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96 |
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97 | if (!cfd) {
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98 | if (do_listen) {
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99 | /* create_and_bind_stream_or_die(NULL, lport)
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100 | * would've work wonderfully, but we need
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101 | * to know lsa */
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102 | sfd = xsocket_stream(&lsa);
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103 | if (lport)
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104 | set_nport(lsa, htons(lport));
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105 | setsockopt_reuseaddr(sfd);
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106 | xbind(sfd, &lsa->sa, lsa->len);
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107 | xlisten(sfd, do_listen); /* can be > 1 */
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108 | /* If we didn't specify a port number,
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109 | * query and print it after listen() */
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110 | if (!lport) {
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111 | socklen_t addrlen = lsa->len;
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112 | getsockname(sfd, &lsa->sa, &addrlen);
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113 | lport = get_nport(&lsa->sa);
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114 | fdprintf(2, "%d\n", ntohs(lport));
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115 | }
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116 | fcntl(sfd, F_SETFD, FD_CLOEXEC);
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117 | accept_again:
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118 | cfd = accept(sfd, NULL, 0);
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119 | if (cfd < 0)
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120 | bb_perror_msg_and_die("accept");
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121 | if (!execparam)
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122 | close(sfd);
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123 | } else {
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124 | cfd = create_and_connect_stream_or_die(argv[0],
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125 | argv[1] ? bb_lookup_port(argv[1], "tcp", 0) : 0);
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126 | }
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127 | }
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128 |
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129 | if (wsecs) {
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130 | alarm(0);
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131 | signal(SIGALRM, SIG_DFL);
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132 | }
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133 |
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134 | /* -e given? */
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135 | if (execparam) {
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136 | signal(SIGCHLD, SIG_IGN);
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137 | // With more than one -l, repeatedly act as server.
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138 | if (do_listen > 1 && vfork()) {
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139 | /* parent */
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140 | // This is a bit weird as cleanup goes, since we wind up with no
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141 | // stdin/stdout/stderr. But it's small and shouldn't hurt anything.
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142 | // We check for cfd == 0 above.
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143 | logmode = LOGMODE_NONE;
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144 | close(0);
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145 | close(1);
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146 | close(2);
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147 | goto accept_again;
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148 | }
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149 | /* child (or main thread if no multiple -l) */
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150 | if (cfd) {
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151 | dup2(cfd, 0);
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152 | close(cfd);
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153 | }
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154 | dup2(0, 1);
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155 | dup2(0, 2);
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156 | USE_NC_EXTRA(BB_EXECVP(execparam[0], execparam);)
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157 | /* Don't print stuff or it will go over the wire.... */
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158 | _exit(127);
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159 | }
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160 |
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161 | // Select loop copying stdin to cfd, and cfd to stdout.
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162 |
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163 | FD_ZERO(&readfds);
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164 | FD_SET(cfd, &readfds);
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165 | FD_SET(STDIN_FILENO, &readfds);
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166 |
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167 | for (;;) {
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168 | int fd;
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169 | int ofd;
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170 | int nread;
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171 |
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172 | testfds = readfds;
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173 |
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174 | if (select(FD_SETSIZE, &testfds, NULL, NULL, NULL) < 0)
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175 | bb_perror_msg_and_die("select");
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176 |
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177 | #define iobuf bb_common_bufsiz1
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178 | for (fd = 0; fd < FD_SETSIZE; fd++) {
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179 | if (FD_ISSET(fd, &testfds)) {
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180 | nread = safe_read(fd, iobuf, sizeof(iobuf));
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181 | if (fd == cfd) {
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182 | if (nread < 1)
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183 | exit(0);
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184 | ofd = STDOUT_FILENO;
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185 | } else {
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186 | if (nread<1) {
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187 | // Close outgoing half-connection so they get EOF, but
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188 | // leave incoming alone so we can see response.
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189 | shutdown(cfd, 1);
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190 | FD_CLR(STDIN_FILENO, &readfds);
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191 | }
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192 | ofd = cfd;
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193 | }
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194 | xwrite(ofd, iobuf, nread);
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195 | if (delay > 0) sleep(delay);
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196 | }
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197 | }
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198 | }
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199 | }
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200 | #endif
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