1 # include <errno.h> 2 # include "sendmail.h" 3 4 #ifndef DAEMON 5 SCCSID(@(#)daemon.c 3.22 08/08/82 (w/o daemon mode)); 6 #else 7 8 # include <sys/socket.h> 9 # include <net/in.h> 10 # include <wait.h> 11 12 SCCSID(@(#)daemon.c 3.22 08/08/82 (with daemon mode)); 13 14 /* 15 ** DAEMON.C -- routines to use when running as a daemon. 16 ** 17 ** This entire file is highly dependent on the 4.2 BSD 18 ** interprocess communication primitives. No attempt has 19 ** been made to make this file portable to Version 7, 20 ** Version 6, MPX files, etc. If you should try such a 21 ** thing yourself, I recommend chucking the entire file 22 ** and starting from scratch. Basic semantics are: 23 ** 24 ** getrequests() 25 ** Opens a port and initiates a connection. 26 ** Returns in a child. Must set InChannel and 27 ** OutChannel appropriately. 28 ** makeconnection(host, port, outfile, infile) 29 ** Make a connection to the named host on the given 30 ** port. Set *outfile and *infile to the files 31 ** appropriate for communication. Returns zero on 32 ** success, else an exit status describing the 33 ** error. 34 ** 35 ** The semantics of both of these should be clean. 36 */ 37 /* 38 ** GETREQUESTS -- open mail IPC port and get requests. 39 ** 40 ** Parameters: 41 ** none. 42 ** 43 ** Returns: 44 ** none. 45 ** 46 ** Side Effects: 47 ** Waits until some interesting activity occurs. When 48 ** it does, a child is created to process it, and the 49 ** parent waits for completion. Return from this 50 ** routine is always in the child. 51 */ 52 53 # define MAXCONNS 4 /* maximum simultaneous sendmails */ 54 55 getrequests() 56 { 57 union wait status; 58 int numconnections = 0; 59 60 for (;;) 61 { 62 register int pid; 63 register int port; 64 65 /* 66 ** Wait for a connection. 67 */ 68 69 while ((port = getconnection()) < 0) 70 { 71 syserr("getrequests: getconnection failed"); 72 finis(); 73 } 74 75 /* 76 ** Create a subprocess to process the mail. 77 */ 78 79 # ifdef DEBUG 80 if (tTd(15, 2)) 81 printf("getrequests: forking (port = %d)\n", port); 82 # endif DEBUG 83 84 pid = fork(); 85 if (pid < 0) 86 { 87 syserr("daemon: cannot fork"); 88 sleep(10); 89 (void) close(port); 90 continue; 91 } 92 93 if (pid == 0) 94 { 95 /* 96 ** CHILD -- return to caller. 97 ** Verify calling user id if possible here. 98 */ 99 100 InChannel = fdopen(port, "r"); 101 OutChannel = fdopen(port, "w"); 102 # ifdef DEBUG 103 if (tTd(15, 2)) 104 printf("getreq: returning\n"); 105 # endif DEBUG 106 return; 107 } 108 109 /* 110 ** PARENT -- wait for child to terminate. 111 ** Perhaps we should allow concurrent processing? 112 */ 113 114 # ifdef DEBUG 115 if (tTd(15, 2)) 116 { 117 sleep(2); 118 printf("getreq: parent waiting\n"); 119 } 120 # endif DEBUG 121 122 /* close the port so that others will hang (for a while) */ 123 (void) close(port); 124 125 /* pick up old zombies; implement load limiting */ 126 numconnections++; 127 while (wait3(&status, numconnections < MAXCONNS ? WNOHANG : 0, 0) > 0) 128 numconnections--; 129 } 130 } 131 /* 132 ** GETCONNECTION -- make a connection with the outside world 133 ** 134 ** Parameters: 135 ** none. 136 ** 137 ** Returns: 138 ** The port for mail traffic. 139 ** 140 ** Side Effects: 141 ** Waits for a connection. 142 */ 143 144 #define IPPORT_PLAYPORT 3055 /* random number */ 145 146 struct sockaddr_in SendmailAddress = { AF_INET, IPPORT_SMTP }; 147 148 getconnection() 149 { 150 register int s; 151 struct sockaddr otherend; 152 153 /* 154 ** Set up the address for the mailer. 155 */ 156 157 SendmailAddress.sin_addr.s_addr = 0; 158 SendmailAddress.sin_port = IPPORT_SMTP; 159 # ifdef DEBUG 160 if (tTd(15, 15)) 161 SendmailAddress.sin_port = IPPORT_PLAYPORT; 162 # endif DEBUG 163 SendmailAddress.sin_port = htons(SendmailAddress.sin_port); 164 165 /* 166 ** Try to actually open the connection. 167 */ 168 169 # ifdef DEBUG 170 if (tTd(15, 1)) 171 printf("getconnection\n"); 172 # endif DEBUG 173 174 for (;;) 175 { 176 /* get a socket for the SMTP connection */ 177 s = socket(SOCK_STREAM, 0, &SendmailAddress, SO_ACCEPTCONN); 178 if (s < 0) 179 { 180 /* probably another daemon already */ 181 syserr("getconnection: can't create socket"); 182 break; 183 } 184 185 # ifdef DEBUG 186 if (tTd(15, 1)) 187 printf("getconnection: %d\n", s); 188 # endif DEBUG 189 190 /* wait for a connection */ 191 if (accept(s, &otherend) >= 0) 192 break; 193 194 /* probably innocuous -- retry */ 195 if (errno == ETIMEDOUT) 196 continue; 197 syserr("getconnection: accept"); 198 (void) close(s); 199 sleep(20); 200 } 201 202 return (s); 203 } 204 /* 205 ** MAKECONNECTION -- make a connection to an SMTP socket on another machine. 206 ** 207 ** Parameters: 208 ** host -- the name of the host. 209 ** port -- the port number to connect to. 210 ** outfile -- a pointer to a place to put the outfile 211 ** descriptor. 212 ** infile -- ditto for infile. 213 ** 214 ** Returns: 215 ** An exit code telling whether the connection could be 216 ** made and if not why not. 217 ** 218 ** Side Effects: 219 ** none. 220 */ 221 222 makeconnection(host, port, outfile, infile) 223 char *host; 224 u_short port; 225 FILE **outfile; 226 FILE **infile; 227 { 228 register int s; 229 230 /* 231 ** Set up the address for the mailer. 232 */ 233 234 if ((SendmailAddress.sin_addr.s_addr = rhost(&host)) == -1) 235 return (EX_NOHOST); 236 if (port == 0) 237 port = IPPORT_SMTP; 238 SendmailAddress.sin_port = htons(port); 239 240 /* 241 ** Try to actually open the connection. 242 */ 243 244 # ifdef DEBUG 245 if (tTd(16, 1)) 246 printf("makeconnection (%s)\n", host); 247 # endif DEBUG 248 249 s = socket(SOCK_STREAM, 0, (struct sockaddr_in *) 0, 0); 250 if (s < 0) 251 { 252 syserr("makeconnection: no socket"); 253 goto failure; 254 } 255 256 # ifdef DEBUG 257 if (tTd(16, 1)) 258 printf("makeconnection: %d\n", s); 259 # endif DEBUG 260 (void) fflush(Xscript); /* for debugging */ 261 if (connect(s, &SendmailAddress) < 0) 262 { 263 /* failure, decide if temporary or not */ 264 failure: 265 switch (errno) 266 { 267 case EISCONN: 268 case ETIMEDOUT: 269 case EINPROGRESS: 270 case EALREADY: 271 case EADDRINUSE: 272 case ENETDOWN: 273 case ENETRESET: 274 case ENOBUFS: 275 case ECONNREFUSED: 276 /* there are others, I'm sure..... */ 277 return (EX_TEMPFAIL); 278 279 default: 280 return (EX_UNAVAILABLE); 281 } 282 } 283 284 /* connection ok, put it into canonical form */ 285 *outfile = fdopen(s, "w"); 286 *infile = fdopen(s, "r"); 287 288 return (0); 289 } 290 291 #endif DAEMON 292