1 | /* Copyright 1988, 1998 by the Massachusetts Institute of Technology. |
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2 | * |
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3 | * Permission to use, copy, modify, and distribute this |
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4 | * software and its documentation for any purpose and without |
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5 | * fee is hereby granted, provided that the above copyright |
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6 | * notice appear in all copies and that both that copyright |
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7 | * notice and this permission notice appear in supporting |
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8 | * documentation, and that the name of M.I.T. not be used in |
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9 | * advertising or publicity pertaining to distribution of the |
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10 | * software without specific, written prior permission. |
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11 | * M.I.T. makes no representations about the suitability of |
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12 | * this software for any purpose. It is provided "as is" |
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13 | * without express or implied warranty. |
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14 | */ |
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15 | |
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16 | static const char rcsid[] = "$Id: message_daemon.c,v 1.13 1998-12-03 19:38:32 ghudson Exp $"; |
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17 | |
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18 | #include "globalmessage.h" |
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19 | #ifndef GMS_SERVER_MESSAGE |
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20 | #define GMS_SERVER_MESSAGE "/var/gms/Message" |
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21 | #endif /* GMS_SERVER_MESSAGE */ |
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22 | |
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23 | #include <sys/types.h> |
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24 | #include <stdio.h> |
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25 | #include <fcntl.h> |
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26 | #include <errno.h> |
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27 | #include <sys/socket.h> |
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28 | #include <netinet/in.h> |
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29 | #include <sys/stat.h> |
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30 | #include <string.h> |
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31 | #include <syslog.h> |
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32 | #include <com_err.h> |
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33 | |
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34 | /* |
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35 | * This version of the daemon is run out of inetd, with a conf line of: |
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36 | * globalmessage dgram udp wait unswitched nobody /usr/athena/etc/messaged messaged |
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37 | */ |
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38 | |
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39 | #define saddr_list(sin) (unsigned)sin[0],(unsigned)sin[1],(unsigned)sin[2],(unsigned)sin[3] |
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40 | int main(argc,argv) |
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41 | int argc; |
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42 | char **argv; |
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43 | { |
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44 | char buf[BFSZ]; |
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45 | int readstat, readlen, msgfile; |
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46 | struct sockaddr from; |
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47 | /* these strange casts are so that I can print out the address of |
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48 | * the incoming packet. |
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49 | */ |
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50 | struct sockaddr_in *cast1 = (struct sockaddr_in *)&from; |
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51 | char *cast2 = (char *)(&(cast1->sin_addr.s_addr)); |
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52 | int fromlen = sizeof(from); |
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53 | time_t timestamp; |
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54 | int headerlen; |
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55 | |
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56 | /* initialize syslog connection for DAEMON */ |
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57 | /* log_pid has the side effect of forcing log messages to be unique, |
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58 | * not listed as ``message the same, repeated 6 times'' but that |
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59 | * shouldn't be a problem. |
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60 | */ |
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61 | openlog(argv[0], LOG_PID, LOG_DAEMON); |
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62 | |
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63 | /* gms is just return values; the other com_err tables used will |
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64 | * init themselves. |
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65 | */ |
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66 | init_gms_err_tbl(); |
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67 | |
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68 | /* read the packet from the socket (stdin, since we run from inetd) |
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69 | * and also record the from address so we can send a reply. |
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70 | */ |
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71 | readstat = recvfrom(0, buf, BFSZ, 0, &from, &fromlen); |
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72 | if(readstat == -1) { |
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73 | syslog(LOG_INFO, "GMS daemon recvfrom failure %s", error_message(errno)); |
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74 | exit(errno); |
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75 | } |
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76 | |
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77 | /* We got a packet successfully, so if logging is enabled record the |
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78 | * requesting address. |
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79 | */ |
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80 | if(argc>1 && !strcmp(argv[1],"-log")) { |
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81 | syslog(LOG_INFO, "GMS request succeeded [%s] from %ud.%ud.%ud.%ud", |
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82 | buf, saddr_list(cast2)); |
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83 | } |
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84 | |
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85 | /* Check the version number, and log if it is in error. */ |
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86 | if(strncmp(buf, GMS_VERSION_STRING, GMS_VERSION_STRING_LEN)) { |
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87 | syslog(LOG_INFO, "GMS bogus version [%s] from %ud.%ud.%ud.%ud", |
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88 | buf, saddr_list(cast2)); |
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89 | exit(GMS_CLIENT_VERSION); |
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90 | } |
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91 | |
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92 | /* Open the message file to read it in. Note that even were we to |
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93 | * want to cache the data for efficiency, we must stat the file to |
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94 | * make sure it hasn't changed under us. Since we're running, we |
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95 | * must open it because we have no state. |
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96 | */ |
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97 | msgfile = open(GMS_SERVER_MESSAGE, O_RDONLY, 0); |
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98 | |
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99 | if(msgfile == -1) { |
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100 | /* no file, special case of 0 timestamp indicating to also delete |
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101 | * the remote cached copy. If the error is ENOENT, then we just |
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102 | * assume it is an expected disappearance; all other errors are |
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103 | * `interesting' and are logged. In any case, the tester can see |
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104 | * that there is no new message. |
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105 | */ |
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106 | if(errno == ENOENT) { |
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107 | /* it didn't exist, we can deal with that... */ |
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108 | timestamp = 0; |
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109 | } else { |
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110 | /* something went wrong, but we can't do much about it; |
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111 | * let's not trash the remote state -- just don't answer the |
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112 | * connection. |
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113 | */ |
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114 | syslog(LOG_INFO, "GMS daemon open error [%s] reading message file <%s>", |
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115 | error_message(errno), GMS_SERVER_MESSAGE); |
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116 | exit(errno); |
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117 | } |
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118 | } else { |
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119 | struct stat sbuf; |
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120 | |
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121 | fstat(msgfile, &sbuf); |
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122 | if(sbuf.st_size == 0) { |
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123 | /* an empty file means the same to the remote as a missing one. */ |
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124 | timestamp = 0; |
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125 | } else { |
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126 | /* for convenient maintenance, use the real timestamp as version |
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127 | * number. */ |
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128 | timestamp = sbuf.st_mtime; |
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129 | } |
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130 | } |
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131 | strcpy(buf,GMS_VERSION_STRING); |
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132 | { |
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133 | char tsbuf[GMS_TIMESTAMP_LEN]; |
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134 | |
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135 | /* sprintf (and _doprnt in general) are slow memory hogs. However, |
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136 | * syslog is already including _doprnt, so it's already over; it |
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137 | * is cheaper just to use sprintf here instead of coding or |
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138 | * linking in the fast integer one. |
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139 | * It is almost readable, too... |
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140 | */ |
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141 | sprintf(tsbuf, " %lu\n", timestamp); |
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142 | strcat(buf,tsbuf); |
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143 | headerlen = strlen(buf); |
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144 | } |
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145 | |
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146 | /* Now that we have the header, we have to read the rest of the file |
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147 | * into the packet after it. The length-1 specification is to |
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148 | * preserve a NUL at the end of the buffer. Use msgfile to remember |
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149 | * that we couldn't open it. |
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150 | */ |
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151 | if(msgfile != -1) { |
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152 | readlen = read(msgfile, buf + headerlen, BFSZ-headerlen-1); |
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153 | if(readlen == -1) { |
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154 | /* read failed but open didn't, so record the error */ |
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155 | syslog(LOG_INFO, "GMS daemon read error [%s] reading message file <%s>", |
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156 | error_message(errno), GMS_SERVER_MESSAGE); |
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157 | exit(errno); |
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158 | } |
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159 | /* protect the fencepost... */ |
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160 | buf[BFSZ-1] = '\0'; |
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161 | close(msgfile); |
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162 | } else { |
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163 | readlen = 0; |
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164 | } |
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165 | /* send the packet back where it came from */ |
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166 | if(-1 == sendto(0, buf, readlen+headerlen, 0, &from, sizeof(from))) { |
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167 | /* the send failed (probably a local error, or bad address or |
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168 | * something so log the attempt. |
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169 | */ |
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170 | syslog(LOG_INFO, "GMS daemon sendto failure [%s] to %d.%d.%d.%d", |
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171 | error_message(errno), saddr_list(cast2)); |
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172 | exit(errno); |
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173 | } |
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174 | /* everything worked, die happy... */ |
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175 | exit(0); |
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176 | } |
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