| 1 | /* |
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| 2 | * Copyright (c) 2006-2009 Bjorn Andersson <flex@kryo.se>, Erik Ekman <yarrick@kryo.se> |
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| 3 | * |
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| 4 | * Permission to use, copy, modify, and distribute this software for any |
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| 5 | * purpose with or without fee is hereby granted, provided that the above |
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| 6 | * copyright notice and this permission notice appear in all copies. |
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| 7 | * |
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| 8 | * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES |
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| 9 | * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
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| 10 | * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR |
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| 11 | * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
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| 12 | * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
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| 13 | * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF |
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| 14 | * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
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| 15 | */ |
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| 16 | |
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| 17 | #include <stdio.h> |
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| 18 | #include <stdint.h> |
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| 19 | #include <stdlib.h> |
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| 20 | #include <string.h> |
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| 21 | #include <signal.h> |
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| 22 | #include <unistd.h> |
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| 23 | #include <sys/types.h> |
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| 24 | #include <sys/param.h> |
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| 25 | #include <sys/time.h> |
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| 26 | #include <fcntl.h> |
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| 27 | #include <time.h> |
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| 28 | |
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| 29 | #ifdef WINDOWS32 |
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| 30 | #include "windows.h" |
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| 31 | #include <winsock2.h> |
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| 32 | #else |
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| 33 | #include <grp.h> |
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| 34 | #include <pwd.h> |
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| 35 | #endif |
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| 36 | |
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| 37 | #include "common.h" |
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| 38 | #include "tun.h" |
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| 39 | #include "client.h" |
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| 40 | #include "util.h" |
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| 41 | |
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| 42 | #ifdef WINDOWS32 |
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| 43 | WORD req_version = MAKEWORD(2, 2); |
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| 44 | WSADATA wsa_data; |
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| 45 | #endif |
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| 46 | |
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| 47 | #if !defined(BSD) && !defined(__GLIBC__) |
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| 48 | static char *__progname; |
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| 49 | #endif |
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| 50 | |
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| 51 | #define PASSWORD_ENV_VAR "IODINE_PASS" |
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| 52 | |
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| 53 | static void |
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| 54 | sighandler(int sig) |
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| 55 | { |
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| 56 | client_stop(); |
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| 57 | } |
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| 58 | |
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| 59 | static void |
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| 60 | usage() { |
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| 61 | extern char *__progname; |
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| 62 | |
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| 63 | fprintf(stderr, "Usage: %s [-v] [-h] [-f] [-r] [-u user] [-t chrootdir] [-d device] " |
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| 64 | "[-P password] [-m maxfragsize] [-M maxlen] [-T type] [-O enc] [-L 0|1] [-I sec] " |
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| 65 | "[-z context] [-F pidfile] [nameserver] topdomain\n", __progname); |
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| 66 | exit(2); |
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| 67 | } |
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| 68 | |
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| 69 | static void |
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| 70 | help() { |
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| 71 | extern char *__progname; |
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| 72 | |
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| 73 | fprintf(stderr, "iodine IP over DNS tunneling client\n"); |
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| 74 | fprintf(stderr, "Usage: %s [-v] [-h] [-f] [-r] [-u user] [-t chrootdir] [-d device] " |
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| 75 | "[-P password] [-m maxfragsize] [-M maxlen] [-T type] [-O enc] [-L 0|1] [-I sec] " |
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| 76 | "[-z context] [-F pidfile] [nameserver] topdomain\n", __progname); |
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| 77 | fprintf(stderr, "Options to try if connection doesn't work:\n"); |
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| 78 | fprintf(stderr, " -T force dns type: NULL, TXT, SRV, MX, CNAME, A (default: autodetect)\n"); |
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| 79 | fprintf(stderr, " -O force downstream encoding for -T other than NULL: Base32, Base64, Base64u,\n"); |
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| 80 | fprintf(stderr, " Base128, or (only for TXT:) Raw (default: autodetect)\n"); |
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| 81 | fprintf(stderr, " -I max interval between requests (default 4 sec) to prevent DNS timeouts\n"); |
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| 82 | fprintf(stderr, " -L 1: use lazy mode for low-latency (default). 0: don't (implies -I1)\n"); |
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| 83 | fprintf(stderr, " -m max size of downstream fragments (default: autodetect)\n"); |
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| 84 | fprintf(stderr, " -M max size of upstream hostnames (~100-255, default: 255)\n"); |
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| 85 | fprintf(stderr, " -r to skip raw UDP mode attempt\n"); |
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| 86 | fprintf(stderr, " -P password used for authentication (max 32 chars will be used)\n"); |
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| 87 | fprintf(stderr, "Other options:\n"); |
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| 88 | fprintf(stderr, " -v to print version info and exit\n"); |
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| 89 | fprintf(stderr, " -h to print this help and exit\n"); |
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| 90 | fprintf(stderr, " -f to keep running in foreground\n"); |
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| 91 | fprintf(stderr, " -u name to drop privileges and run as user 'name'\n"); |
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| 92 | fprintf(stderr, " -t dir to chroot to directory dir\n"); |
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| 93 | fprintf(stderr, " -d device to set tunnel device name\n"); |
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| 94 | fprintf(stderr, " -z context, to apply specified SELinux context after initialization\n"); |
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| 95 | fprintf(stderr, " -F pidfile to write pid to a file\n"); |
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| 96 | fprintf(stderr, "nameserver is the IP number/hostname of the relaying nameserver. if absent, /etc/resolv.conf is used\n"); |
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| 97 | fprintf(stderr, "topdomain is the FQDN that is delegated to the tunnel endpoint.\n"); |
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| 98 | |
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| 99 | exit(0); |
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| 100 | } |
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| 101 | |
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| 102 | static void |
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| 103 | version() { |
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| 104 | char *svnver; |
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| 105 | |
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| 106 | svnver = "$Rev$ from $Date$"; |
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| 107 | |
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| 108 | fprintf(stderr, "iodine IP over DNS tunneling client\n"); |
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| 109 | fprintf(stderr, "SVN version: %s\n", svnver); |
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| 110 | |
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| 111 | exit(0); |
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| 112 | } |
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| 113 | |
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| 114 | int |
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| 115 | main(int argc, char **argv) |
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| 116 | { |
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| 117 | char *nameserv_addr; |
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| 118 | char *topdomain; |
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| 119 | #ifndef WINDOWS32 |
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| 120 | struct passwd *pw; |
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| 121 | #endif |
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| 122 | char *username; |
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| 123 | char password[33]; |
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| 124 | int foreground; |
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| 125 | char *newroot; |
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| 126 | char *context; |
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| 127 | char *device; |
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| 128 | char *pidfile; |
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| 129 | int choice; |
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| 130 | int tun_fd; |
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| 131 | int dns_fd; |
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| 132 | int max_downstream_frag_size; |
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| 133 | int autodetect_frag_size; |
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| 134 | int retval; |
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| 135 | int raw_mode; |
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| 136 | int lazymode; |
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| 137 | int selecttimeout; |
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| 138 | int hostname_maxlen; |
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| 139 | int rtable = 0; |
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| 140 | |
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| 141 | nameserv_addr = NULL; |
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| 142 | topdomain = NULL; |
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| 143 | #ifndef WINDOWS32 |
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| 144 | pw = NULL; |
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| 145 | #endif |
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| 146 | username = NULL; |
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| 147 | memset(password, 0, 33); |
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| 148 | srand(time(NULL)); |
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| 149 | foreground = 0; |
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| 150 | newroot = NULL; |
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| 151 | context = NULL; |
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| 152 | device = NULL; |
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| 153 | pidfile = NULL; |
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| 154 | |
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| 155 | autodetect_frag_size = 1; |
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| 156 | max_downstream_frag_size = 3072; |
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| 157 | retval = 0; |
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| 158 | raw_mode = 1; |
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| 159 | lazymode = 1; |
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| 160 | selecttimeout = 4; |
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| 161 | hostname_maxlen = 0xFF; |
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| 162 | |
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| 163 | #ifdef WINDOWS32 |
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| 164 | WSAStartup(req_version, &wsa_data); |
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| 165 | #endif |
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| 166 | |
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| 167 | srand((unsigned) time(NULL)); |
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| 168 | client_init(); |
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| 169 | |
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| 170 | #if !defined(BSD) && !defined(__GLIBC__) |
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| 171 | __progname = strrchr(argv[0], '/'); |
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| 172 | if (__progname == NULL) |
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| 173 | __progname = argv[0]; |
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| 174 | else |
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| 175 | __progname++; |
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| 176 | #endif |
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| 177 | |
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| 178 | while ((choice = getopt(argc, argv, "vfhru:t:d:R:P:m:M:F:T:O:L:I:")) != -1) { |
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| 179 | switch(choice) { |
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| 180 | case 'v': |
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| 181 | version(); |
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| 182 | /* NOTREACHED */ |
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| 183 | break; |
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| 184 | case 'f': |
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| 185 | foreground = 1; |
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| 186 | break; |
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| 187 | case 'h': |
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| 188 | help(); |
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| 189 | /* NOTREACHED */ |
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| 190 | break; |
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| 191 | case 'r': |
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| 192 | raw_mode = 0; |
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| 193 | break; |
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| 194 | case 'u': |
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| 195 | username = optarg; |
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| 196 | break; |
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| 197 | case 't': |
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| 198 | newroot = optarg; |
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| 199 | break; |
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| 200 | case 'd': |
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| 201 | device = optarg; |
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| 202 | break; |
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| 203 | case 'R': |
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| 204 | rtable = atoi(optarg); |
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| 205 | break; |
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| 206 | case 'P': |
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| 207 | strncpy(password, optarg, sizeof(password)); |
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| 208 | password[sizeof(password)-1] = 0; |
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| 209 | |
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| 210 | /* XXX: find better way of cleaning up ps(1) */ |
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| 211 | memset(optarg, 0, strlen(optarg)); |
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| 212 | break; |
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| 213 | case 'm': |
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| 214 | autodetect_frag_size = 0; |
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| 215 | max_downstream_frag_size = atoi(optarg); |
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| 216 | break; |
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| 217 | case 'M': |
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| 218 | hostname_maxlen = atoi(optarg); |
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| 219 | if (hostname_maxlen > 255) |
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| 220 | hostname_maxlen = 255; |
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| 221 | if (hostname_maxlen < 10) |
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| 222 | hostname_maxlen = 10; |
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| 223 | break; |
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| 224 | case 'z': |
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| 225 | context = optarg; |
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| 226 | break; |
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| 227 | case 'F': |
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| 228 | pidfile = optarg; |
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| 229 | break; |
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| 230 | case 'T': |
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| 231 | set_qtype(optarg); |
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| 232 | break; |
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| 233 | case 'O': /* not -D, is Debug in server */ |
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| 234 | set_downenc(optarg); |
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| 235 | break; |
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| 236 | case 'L': |
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| 237 | lazymode = atoi(optarg); |
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| 238 | if (lazymode > 1) |
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| 239 | lazymode = 1; |
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| 240 | if (lazymode < 0) |
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| 241 | lazymode = 0; |
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| 242 | if (!lazymode) |
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| 243 | selecttimeout = 1; |
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| 244 | break; |
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| 245 | case 'I': |
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| 246 | selecttimeout = atoi(optarg); |
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| 247 | if (selecttimeout < 1) |
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| 248 | selecttimeout = 1; |
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| 249 | break; |
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| 250 | default: |
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| 251 | usage(); |
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| 252 | /* NOTREACHED */ |
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| 253 | } |
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| 254 | } |
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| 255 | |
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| 256 | check_superuser(usage); |
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| 257 | |
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| 258 | argc -= optind; |
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| 259 | argv += optind; |
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| 260 | |
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| 261 | switch (argc) { |
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| 262 | case 1: |
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| 263 | nameserv_addr = get_resolvconf_addr(); |
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| 264 | topdomain = strdup(argv[0]); |
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| 265 | break; |
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| 266 | case 2: |
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| 267 | nameserv_addr = argv[0]; |
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| 268 | topdomain = strdup(argv[1]); |
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| 269 | break; |
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| 270 | default: |
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| 271 | usage(); |
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| 272 | /* NOTREACHED */ |
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| 273 | } |
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| 274 | |
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| 275 | if (max_downstream_frag_size < 1 || max_downstream_frag_size > 0xffff) { |
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| 276 | warnx("Use a max frag size between 1 and 65535 bytes.\n"); |
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| 277 | usage(); |
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| 278 | /* NOTREACHED */ |
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| 279 | } |
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| 280 | |
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| 281 | if (nameserv_addr) { |
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| 282 | client_set_nameserver(nameserv_addr, DNS_PORT); |
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| 283 | } else { |
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| 284 | warnx("No nameserver found - not connected to any network?\n"); |
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| 285 | usage(); |
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| 286 | /* NOTREACHED */ |
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| 287 | } |
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| 288 | |
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| 289 | if (strlen(topdomain) <= 128) { |
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| 290 | if(check_topdomain(topdomain)) { |
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| 291 | warnx("Topdomain contains invalid characters.\n"); |
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| 292 | usage(); |
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| 293 | /* NOTREACHED */ |
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| 294 | } |
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| 295 | } else { |
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| 296 | warnx("Use a topdomain max 128 chars long.\n"); |
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| 297 | usage(); |
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| 298 | /* NOTREACHED */ |
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| 299 | } |
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| 300 | |
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| 301 | client_set_selecttimeout(selecttimeout); |
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| 302 | client_set_lazymode(lazymode); |
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| 303 | client_set_topdomain(topdomain); |
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| 304 | client_set_hostname_maxlen(hostname_maxlen); |
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| 305 | |
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| 306 | if (username != NULL) { |
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| 307 | #ifndef WINDOWS32 |
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| 308 | if ((pw = getpwnam(username)) == NULL) { |
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| 309 | warnx("User %s does not exist!\n", username); |
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| 310 | usage(); |
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| 311 | /* NOTREACHED */ |
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| 312 | } |
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| 313 | #endif |
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| 314 | } |
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| 315 | |
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| 316 | if (strlen(password) == 0) { |
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| 317 | if (NULL != getenv(PASSWORD_ENV_VAR)) |
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| 318 | snprintf(password, sizeof(password), "%s", getenv(PASSWORD_ENV_VAR)); |
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| 319 | else |
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| 320 | read_password(password, sizeof(password)); |
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| 321 | } |
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| 322 | |
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| 323 | client_set_password(password); |
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| 324 | |
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| 325 | if ((tun_fd = open_tun(device)) == -1) { |
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| 326 | retval = 1; |
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| 327 | goto cleanup1; |
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| 328 | } |
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| 329 | if ((dns_fd = open_dns(0, INADDR_ANY)) == -1) { |
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| 330 | retval = 1; |
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| 331 | goto cleanup2; |
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| 332 | } |
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| 333 | #ifdef OPENBSD |
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| 334 | if (rtable > 0) |
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| 335 | socket_setrtable(dns_fd, rtable); |
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| 336 | #endif |
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| 337 | |
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| 338 | signal(SIGINT, sighandler); |
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| 339 | signal(SIGTERM, sighandler); |
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| 340 | |
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| 341 | fprintf(stderr, "Sending DNS queries for %s to %s\n", |
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| 342 | topdomain, nameserv_addr); |
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| 343 | |
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| 344 | if (client_handshake(dns_fd, raw_mode, autodetect_frag_size, max_downstream_frag_size)) { |
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| 345 | retval = 1; |
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| 346 | goto cleanup2; |
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| 347 | } |
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| 348 | |
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| 349 | if (client_get_conn() == CONN_RAW_UDP) { |
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| 350 | fprintf(stderr, "Sending raw traffic directly to %s\n", client_get_raw_addr()); |
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| 351 | } |
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| 352 | |
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| 353 | fprintf(stderr, "Connection setup complete, transmitting data.\n"); |
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| 354 | |
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| 355 | if (foreground == 0) |
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| 356 | do_detach(); |
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| 357 | |
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| 358 | if (pidfile != NULL) |
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| 359 | do_pidfile(pidfile); |
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| 360 | |
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| 361 | if (newroot != NULL) |
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| 362 | do_chroot(newroot); |
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| 363 | |
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| 364 | if (username != NULL) { |
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| 365 | #ifndef WINDOWS32 |
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| 366 | gid_t gids[1]; |
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| 367 | gids[0] = pw->pw_gid; |
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| 368 | if (setgroups(1, gids) < 0 || setgid(pw->pw_gid) < 0 || setuid(pw->pw_uid) < 0) { |
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| 369 | warnx("Could not switch to user %s!\n", username); |
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| 370 | usage(); |
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| 371 | /* NOTREACHED */ |
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| 372 | } |
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| 373 | #endif |
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| 374 | } |
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| 375 | |
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| 376 | if (context != NULL) |
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| 377 | do_setcon(context); |
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| 378 | |
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| 379 | client_tunnel(tun_fd, dns_fd); |
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| 380 | |
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| 381 | cleanup2: |
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| 382 | close_dns(dns_fd); |
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| 383 | close_tun(tun_fd); |
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| 384 | cleanup1: |
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| 385 | |
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| 386 | return retval; |
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| 387 | } |
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| 388 | |
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