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1
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1 /***************************************************************************
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2 * Copyright (C) 2005 by 510 Software Group *
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3 * *
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4 * *
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5 * This program is free software; you can redistribute it and/or modify *
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6 * it under the terms of the GNU General Public License as published by *
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7 * the Free Software Foundation; either version 2 of the License, or *
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8 * (at your option) any later version. *
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9 * *
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10 * This program is distributed in the hope that it will be useful, *
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11 * but WITHOUT ANY WARRANTY; without even the implied warranty of *
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12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
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13 * GNU General Public License for more details. *
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14 * *
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15 * You should have received a copy of the GNU General Public License *
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16 * along with this program; if not, write to the *
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17 * Free Software Foundation, Inc., *
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18 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. *
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19 ***************************************************************************/
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20
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5
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21 // debug levels:
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22 // 4 - show syslog lines that match regex
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10
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23 // 3 - show iptables commands
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24 // 2 - show files open/close
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5
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25 // 1 - show config files loading
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1
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26
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9
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27 #include "includes.h"
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1
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28 #include <iostream>
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29 #include <cstdlib>
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30 #include <errno.h>
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31 #include <sysexits.h>
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32 #include <pthread.h>
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33 #include <syslog.h>
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34 #include <sys/wait.h> /* header for waitpid() and various macros */
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35 #include <signal.h> /* header for signal functions */
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36
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13
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37 static char* syslog2iptables_version = "$Id$";
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38
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2
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39 extern "C" {
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40 void sig_chld(int signo);
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41 }
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1
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42 int debug_syslog = 0;
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43 bool syslog_opened = false;
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44 bool use_syslog = true; // false to printf
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45 bool loader_run = true; // used to stop the config loader thread
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46 CONFIG *config = NULL; // protected by the config_mutex
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47 int generation = 0; // protected by the config_mutex
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48 const int maxlen = 1000; // used for snprintf buffers
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49
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50 pthread_mutex_t config_mutex;
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51 pthread_mutex_t syslog_mutex;
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52
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53
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54 ////////////////////////////////////////////////
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55 // syslog a message
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56 //
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57 void my_syslog(char *text) {
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58 if (use_syslog) {
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59 pthread_mutex_lock(&syslog_mutex);
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60 if (!syslog_opened) {
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5
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61 openlog("syslog2iptables", LOG_PID, LOG_AUTHPRIV);
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1
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62 syslog_opened = true;
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63 }
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64 syslog(LOG_NOTICE, "%s", text);
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65 pthread_mutex_unlock(&syslog_mutex);
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66 }
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67 else {
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3
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68 printf("%s\n", text);
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1
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69 }
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70 }
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71
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72 ////////////////////////////////////////////////
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73 // reload the config
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74 //
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75 CONFIG* new_conf();
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76 CONFIG* new_conf() {
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77 CONFIG *newc = new CONFIG;
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78 pthread_mutex_lock(&config_mutex);
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79 newc->generation = generation++;
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80 pthread_mutex_unlock(&config_mutex);
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81 if (debug_syslog) {
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82 char buf[maxlen];
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83 snprintf(buf, sizeof(buf), "loading configuration generation %d", newc->generation);
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84 my_syslog(buf);
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85 }
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86 if (load_conf(*newc, "syslog2iptables.conf")) {
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87 newc->load_time = time(NULL);
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88 return newc;
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89 }
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90 delete newc;
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91 return NULL;
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92 }
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93
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94
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95 ////////////////////////////////////////////////
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96 // thread to watch the old config files for changes
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97 // and reload when needed. we also cleanup old
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98 // configs whose reference count has gone to zero.
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99 //
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100 void* config_loader(void *arg);
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101 void* config_loader(void *arg) {
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102 typedef set<CONFIG *> configp_set;
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103 configp_set old_configs;
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104 while (loader_run) {
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105 sleep(180); // look for modifications every 3 minutes
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106 if (!loader_run) break;
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107 CONFIG &dc = *config;
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108 time_t then = dc.load_time;
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109 struct stat st;
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110 bool reload = false;
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111 for (string_set::iterator i=dc.config_files.begin(); i!=dc.config_files.end(); i++) {
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112 char *fn = *i;
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113 if (stat(fn, &st)) reload = true; // file disappeared
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114 else if (st.st_mtime > then) reload = true; // file modified
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115 if (reload) break;
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116 }
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117 if (reload) {
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118 CONFIG *newc = new_conf();
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119 if (newc) {
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120 // replace the global config pointer
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121 pthread_mutex_lock(&config_mutex);
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122 CONFIG *old = config;
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123 config = newc;
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124 pthread_mutex_unlock(&config_mutex);
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125 if (old) old_configs.insert(old);
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126 }
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127 else {
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128 // failed to load new config
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129 my_syslog("failed to load new configuration");
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130 system("echo 'failed to load new /etc/syslog2iptables.conf' | mail -s 'error in /etc/syslog2iptables.conf' root");
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131 // update the load time on the current config to prevent complaining every 3 minutes
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132 dc.load_time = time(NULL);
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133 }
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134 }
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135 // now look for old configs with zero ref counts
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136 for (configp_set::iterator i=old_configs.begin(); i!=old_configs.end(); ) {
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137 CONFIG *old = *i;
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138 if (!old->reference_count) {
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139 if (debug_syslog) {
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140 char buf[maxlen];
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141 snprintf(buf, sizeof(buf), "freeing memory for old configuration generation %d", old->generation);
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142 my_syslog(buf);
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143 }
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144 delete old; // destructor does all the work
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145 old_configs.erase(i++);
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146 }
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147 else i++;
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148 }
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149 }
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150 return NULL;
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151 }
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152
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153
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154 ////////////////////////////////////////////////
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155 // The signal handler function -- only gets called when a SIGCHLD
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156 // is received, ie when a child terminates
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157 //
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158 void sig_chld(int signo)
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159 {
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160 int status;
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161 /* Wait for any child without blocking */
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162 while (waitpid(-1, &status, WNOHANG) > 0) {
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163 // ignore child exit status, we only do this to cleanup zombies
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164 }
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165 }
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166
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167
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168 void usage(char *prog);
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169 void usage(char *prog)
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170 {
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5
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171 fprintf(stderr, "Usage: %s [-d [level]] [-c]\n", prog);
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172 fprintf(stderr, "-c will load and dump the config to stdout\n");
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173 fprintf(stderr, "-d will set the syslog message level, currently 0 to 3\n");
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174 }
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175
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176
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177 void worker();
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178 void worker()
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179 {
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180 time_t t = time(NULL);
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181 CONFIG *c;
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182 pthread_mutex_lock(&config_mutex);
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183 c = config;
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184 c->reference_count++;
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185 pthread_mutex_unlock(&config_mutex);
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186 while (true) {
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187 if (c != config) {
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188 pthread_mutex_lock(&config_mutex);
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189 c->reference_count--;
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190 c = config;
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191 c->reference_count++;
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192 pthread_mutex_unlock(&config_mutex);
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193 }
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194 c->read();
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195 c->sleep(10, t);
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196 }
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1
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197 }
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198
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199
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200 int main(int argc, char *argv[])
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201 {
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202 token_init();
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5
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203 bool check = false;
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1
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204 int c;
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5
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205 const char *args = "d:ch";
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1
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206 extern char *optarg;
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207
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208 // Process command line options
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209 while ((c = getopt(argc, argv, args)) != -1) {
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210 switch (c) {
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211 case 'c':
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212 check = true;
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213 break;
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214
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5
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215 case 'd':
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216 if (optarg == NULL || *optarg == '\0') debug_syslog = 1;
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217 else debug_syslog = atoi(optarg);
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218 break;
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219
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1
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220 case 'h':
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221 default:
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222 usage(argv[0]);
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223 exit(EX_USAGE);
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224 }
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225 }
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226
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227 if (check) {
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228 use_syslog = false;
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229 debug_syslog = 10;
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4
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230 config = new_conf();
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231 if (config) {
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232 config->dump();
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233 delete config;
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1
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234 return 0;
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235 }
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236 else {
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237 return 1; // config failed to load
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238 }
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239 }
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240
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241 // switch to background mode
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242 if (daemon(1,0) < 0) {
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243 fprintf(stderr, "daemon() call failed\n");
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244 exit(EX_UNAVAILABLE);
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245 }
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246
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247 // write the pid
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248 const char *pidpath = "/var/run/syslog2iptables.pid";
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249 unlink(pidpath);
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250 FILE *f = fopen(pidpath, "w");
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251 if (f) {
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252 #ifdef linux
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253 // from a comment in the DCC source code:
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254 // Linux threads are broken. Signals given the
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255 // original process are delivered to only the
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256 // thread that happens to have that PID. The
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257 // sendmail libmilter thread that needs to hear
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258 // SIGINT and other signals does not, and that breaks
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259 // scripts that need to stop milters.
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260 // However, signaling the process group works.
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261 fprintf(f, "-%d\n", (u_int)getpgrp());
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262 #else
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263 fprintf(f, "%d\n", (u_int)getpid());
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264 #endif
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265 fclose(f);
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266 }
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267
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268 // initialize the thread sync objects
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269 pthread_mutex_init(&config_mutex, 0);
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270 pthread_mutex_init(&syslog_mutex, 0);
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271
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272 // load the initial config
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273 config = new_conf();
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274 if (!config) {
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275 my_syslog("failed to load initial configuration, quitting");
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276 exit(1);
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277 }
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278
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2
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279 // setup sigchld handler to prevent zombies
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280 struct sigaction act;
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281 act.sa_handler = sig_chld; // Assign sig_chld as our SIGCHLD handler
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282 sigemptyset(&act.sa_mask); // We don't want to block any other signals in this example
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283 act.sa_flags = SA_NOCLDSTOP; // only want children that have terminated
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284 if (sigaction(SIGCHLD, &act, NULL) < 0) {
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285 my_syslog("failed to setup SIGCHLD handler");
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286 exit(1);
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287 }
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288
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1
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289 // only create threads after the fork() in daemon
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290 pthread_t tid;
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291 if (pthread_create(&tid, 0, config_loader, 0))
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292 my_syslog("failed to create config loader thread");
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293 if (pthread_detach(tid))
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294 my_syslog("failed to detach config loader thread");
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295
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5
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296 worker();
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297
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1
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298 return EXIT_SUCCESS;
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299 }
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