src/src/dcc.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) Wolfgang Breyha 2005-2013
   6  * Vienna University Computer Center
   7  * wbreyha@gmx.net
   8  * See the file NOTICE for conditions of use and distribution.
   9  */
  10
  11 /* This patch is based on code from Tom Kistners exiscan (ACL integration) and
  12  * the DCC local_scan patch from Christopher Bodenstein */
  13
  14 /* Code for calling dccifd. Called from acl.c. */
  15
  16 #include "exim.h"
  17 #ifdef EXPERIMENTAL_DCC
  18 #include "dcc.h"
  19 #include "unistd.h"
  20
  21 uschar dcc_header_str[256];
  22 int dcc_ok = 0;
  23 int dcc_rc = 0;
  24
  25 /* This function takes a file descriptor and a buffer as input and
  26  * returns either 0 for success or errno in case of error. */
  27
  28 int flushbuffer (int socket, uschar *buffer)
  29  {
  30   int retval, rsp;
  31   rsp = write(socket, buffer, Ustrlen(buffer));
  32   DEBUG(D_acl)
  33     debug_printf("DCC: Result of the write() = %d\n", rsp);
  34   if(rsp < 0)
  35   {
  36     DEBUG(D_acl)
  37       debug_printf("DCC: Error writing buffer to socket: %s\n", strerror(errno));
  38     retval = errno;
  39   }
  40   else {
  41     DEBUG(D_acl)
  42       debug_printf("DCC: Wrote buffer to socket:\n%s\n", buffer);
  43     retval = 0;
  44   }
  45   return retval;
  46 }
  47
  48 int dcc_process(uschar **listptr) {
  49   int sep = 0;
  50   uschar *list = *listptr;
  51   FILE *data_file;
  52   uschar *dcc_default_ip_option = US"127.0.0.1";
  53   uschar *dcc_helo_option = US"localhost";
  54   uschar *dcc_reject_message = US"Rejected by DCC";
  55   uschar *xtra_hdrs = NULL;
  56   uschar *override_client_ip  = NULL;
  57
  58   /* from local_scan */
  59   int i, j, k, c, retval, sockfd, resp, line;
  60   unsigned int portnr;
  61   struct sockaddr_un  serv_addr;
  62   struct sockaddr_in  serv_addr_in;
  63   struct hostent *ipaddress;
  64   uschar sockpath[128];
  65   uschar sockip[40], client_ip[40];
  66   uschar opts[128];
  67   uschar rcpt[128], from[128];
  68   uschar sendbuf[4096];
  69   uschar recvbuf[4096];
  70   uschar dcc_return_text[1024];
  71   uschar mbox_path[1024];
  72   uschar message_subdir[2];
  73   struct header_line *dcchdr;
  74   uschar *dcc_acl_options;
  75   uschar dcc_acl_options_buffer[10];
  76   uschar dcc_xtra_hdrs[1024];
  77
  78   /* grep 1st option */
  79   if ((dcc_acl_options = string_nextinlist(&list, &sep,
  80                                            dcc_acl_options_buffer,
  81                                            sizeof(dcc_acl_options_buffer))) != NULL)
  82   {
  83     /* parse 1st option */
  84     if ( (strcmpic(dcc_acl_options,US"false") == 0) ||
  85          (Ustrcmp(dcc_acl_options,"0") == 0) ) {
  86       /* explicitly no matching */
  87       return FAIL;
  88     };
  89
  90     /* special cases (match anything except empty) */
  91     if ( (strcmpic(dcc_acl_options,US"true") == 0) ||
  92          (Ustrcmp(dcc_acl_options,"*") == 0) ||
  93          (Ustrcmp(dcc_acl_options,"1") == 0) ) {
  94       dcc_acl_options = dcc_acl_options;
  95     };
  96   }
  97   else {
  98     /* empty means "don't match anything" */
  99     return FAIL;
 100   };
 101
 102   sep = 0;
 103
 104   /* if we scanned this message last time, just return */
 105   if ( dcc_ok )
 106       return dcc_rc;
 107
 108   /* open the spooled body */
 109   message_subdir[1] = '\0';
 110   for (i = 0; i < 2; i++) {
 111     message_subdir[0] = (split_spool_directory == (i == 0))? message_id[5] : 0;
 112     sprintf(CS mbox_path, "%s/input/%s/%s-D", spool_directory, message_subdir, message_id);
 113     data_file = Ufopen(mbox_path,"rb");
 114     if (data_file != NULL)
 115       break;
 116   };
 117
 118   if (data_file == NULL) {
 119     /* error while spooling */
 120     log_write(0, LOG_MAIN|LOG_PANIC,
 121            "dcc acl condition: error while opening spool file");
 122     return DEFER;
 123   };
 124
 125   /* Initialize the variables */
 126
 127   bzero(sockip,sizeof(sockip));
 128   if (dccifd_address) {
 129     if (dccifd_address[0] == '/')
 130       Ustrncpy(sockpath, dccifd_address, sizeof(sockpath));
 131     else
 132       if( sscanf(CS dccifd_address, "%s %u", sockip, &portnr) != 2) {
 133         log_write(0, LOG_MAIN,
 134           "dcc acl condition: warning - invalid dccifd address: '%s'", dccifd_address);
 135         (void)fclose(data_file);
 136         return DEFER;
 137       }
 138   }
 139
 140   /* opts is what we send as dccifd options - see man dccifd */
 141   /* We don't support any other option than 'header' so just copy that */
 142   bzero(opts,sizeof(opts));
 143   Ustrncpy(opts, dccifd_options, sizeof(opts)-1);
 144   /* if $acl_m_dcc_override_client_ip is set use it */
 145   if (((override_client_ip = expand_string(US"$acl_m_dcc_override_client_ip")) != NULL) &&
 146        (override_client_ip[0] != '\0')) {
 147     Ustrncpy(client_ip, override_client_ip, sizeof(client_ip)-1);
 148     DEBUG(D_acl)
 149       debug_printf("DCC: Client IP (overridden): %s\n", client_ip);
 150   }
 151   else if(sender_host_address) {
 152   /* else if $sender_host_address is available use that? */
 153     Ustrncpy(client_ip, sender_host_address, sizeof(client_ip)-1);
 154     DEBUG(D_acl)
 155       debug_printf("DCC: Client IP (sender_host_address): %s\n", client_ip);
 156   }
 157   else {
 158     /* sender_host_address is NULL which means it comes from localhost */
 159     Ustrncpy(client_ip, dcc_default_ip_option, sizeof(client_ip)-1);
 160     DEBUG(D_acl)
 161       debug_printf("DCC: Client IP (default): %s\n", client_ip);
 162   }
 163   /* strncat(opts, my_request, strlen(my_request)); */
 164   Ustrcat(opts, "\n");
 165   Ustrncat(opts, client_ip, sizeof(opts)-Ustrlen(opts)-1);
 166   Ustrncat(opts, "\nHELO ", sizeof(opts)-Ustrlen(opts)-1);
 167   Ustrncat(opts, dcc_helo_option, sizeof(opts)-Ustrlen(opts)-2);
 168   Ustrcat(opts, "\n");
 169
 170   /* initialize the other variables */
 171   dcchdr = header_list;
 172   /* we set the default return value to DEFER */
 173   retval = DEFER;
 174
 175   bzero(sendbuf,sizeof(sendbuf));
 176   bzero(dcc_header_str,sizeof(dcc_header_str));
 177   bzero(rcpt,sizeof(rcpt));
 178   bzero(from,sizeof(from));
 179
 180   /* send a null return path as "<>". */
 181   if (Ustrlen(sender_address) > 0)
 182     Ustrncpy(from, sender_address, sizeof(from));
 183   else
 184     Ustrncpy(from, "<>", sizeof(from));
 185   Ustrncat(from, "\n", sizeof(from)-Ustrlen(from)-1);
 186
 187   /**************************************
 188    * Now creating the socket connection *
 189    **************************************/
 190
 191   /* If sockip contains an ip, we use a tcp socket, otherwise a UNIX socket */
 192   if(Ustrcmp(sockip, "")){
 193     ipaddress = gethostbyname((char *)sockip);
 194     bzero((char *) &serv_addr_in, sizeof(serv_addr_in));
 195     serv_addr_in.sin_family = AF_INET;
 196     bcopy((char *)ipaddress->h_addr, (char *)&serv_addr_in.sin_addr.s_addr, ipaddress->h_length);
 197     serv_addr_in.sin_port = htons(portnr);
 198     if ((sockfd = socket(AF_INET, SOCK_STREAM,0)) < 0){
 199       DEBUG(D_acl)
 200         debug_printf("DCC: Creating TCP socket connection failed: %s\n", strerror(errno));
 201       log_write(0,LOG_PANIC,"DCC: Creating TCP socket connection failed: %s\n", strerror(errno));
 202       /* if we cannot create the socket, defer the mail */
 203       (void)fclose(data_file);
 204       return retval;
 205     }
 206     /* Now connecting the socket (INET) */
 207     if (connect(sockfd, (struct sockaddr *)&serv_addr_in, sizeof(serv_addr_in)) < 0){
 208       DEBUG(D_acl)
 209         debug_printf("DCC: Connecting to TCP socket failed: %s\n", strerror(errno));
 210       log_write(0,LOG_PANIC,"DCC: Connecting to TCP socket failed: %s\n", strerror(errno));
 211       /* if we cannot contact the socket, defer the mail */
 212       (void)fclose(data_file);
 213       return retval;
 214     }
 215   } else {
 216     /* connecting to the dccifd UNIX socket */
 217     bzero((char *)&serv_addr,sizeof(serv_addr));
 218     serv_addr.sun_family = AF_UNIX;
 219     Ustrcpy(serv_addr.sun_path, sockpath);
 220     if ((sockfd = socket(AF_UNIX, SOCK_STREAM,0)) < 0){
 221       DEBUG(D_acl)
 222         debug_printf("DCC: Creating UNIX socket connection failed: %s\n", strerror(errno));
 223       log_write(0,LOG_PANIC,"DCC: Creating UNIX socket connection failed: %s\n", strerror(errno));
 224       /* if we cannot create the socket, defer the mail */
 225       (void)fclose(data_file);
 226       return retval;
 227     }
 228     /* Now connecting the socket (UNIX) */
 229     if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0){
 230       DEBUG(D_acl)
 231                             debug_printf("DCC: Connecting to UNIX socket failed: %s\n", strerror(errno));
 232       log_write(0,LOG_PANIC,"DCC: Connecting to UNIX socket failed: %s\n", strerror(errno));
 233       /* if we cannot contact the socket, defer the mail */
 234       (void)fclose(data_file);
 235       return retval;
 236     }
 237   }
 238   /* the socket is open, now send the options to dccifd*/
 239   DEBUG(D_acl)
 240     debug_printf("\nDCC: ---------------------------\nDCC: Socket opened; now sending input\nDCC: -----------------\n");
 241   /* First, fill in the input buffer */
 242   Ustrncpy(sendbuf, opts, sizeof(sendbuf));
 243   Ustrncat(sendbuf, from, sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 244
 245   DEBUG(D_acl)
 246   {
 247     debug_printf("DCC: opts = %s\nDCC: sender = %s\nDCC: rcpt count = %d\n", opts, from, recipients_count);
 248     debug_printf("DCC: Sending options:\nDCC: ****************************\n");
 249   }
 250
 251   /* let's send each of the recipients to dccifd */
 252   for (i = 0; i < recipients_count; i++){
 253     DEBUG(D_acl)
 254       debug_printf("DCC: recipient = %s\n",recipients_list[i].address);
 255     if(Ustrlen(sendbuf) + Ustrlen(recipients_list[i].address) > sizeof(sendbuf))
 256     {
 257       DEBUG(D_acl)
 258         debug_printf("DCC: Writing buffer: %s\n", sendbuf);
 259       flushbuffer(sockfd, sendbuf);
 260       bzero(sendbuf, sizeof(sendbuf));
 261     }
 262     Ustrncat(sendbuf, recipients_list[i].address, sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 263     Ustrncat(sendbuf, "\r\n", sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 264   }
 265   /* send a blank line between options and message */
 266   Ustrncat(sendbuf, "\n", sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 267   /* Now we send the input buffer */
 268   DEBUG(D_acl)
 269     debug_printf("DCC: %s\nDCC: ****************************\n", sendbuf);
 270   flushbuffer(sockfd, sendbuf);
 271
 272   /* now send the message */
 273   /* Clear the input buffer */
 274   bzero(sendbuf, sizeof(sendbuf));
 275   /* First send the headers */
 276   /* Now send the headers */
 277   DEBUG(D_acl)
 278     debug_printf("DCC: Sending headers:\nDCC: ****************************\n");
 279   Ustrncpy(sendbuf, dcchdr->text, sizeof(sendbuf)-2);
 280   while((dcchdr=dcchdr->next)) {
 281     if(dcchdr->slen > sizeof(sendbuf)-2) {
 282       /* The size of the header is bigger than the size of
 283        * the input buffer, so split it up in smaller parts. */
 284        flushbuffer(sockfd, sendbuf);
 285        bzero(sendbuf, sizeof(sendbuf));
 286        j = 0;
 287        while(j < dcchdr->slen)
 288        {
 289         for(i = 0; i < sizeof(sendbuf)-2; i++) {
 290           sendbuf[i] = dcchdr->text[j];
 291           j++;
 292         }
 293         flushbuffer(sockfd, sendbuf);
 294         bzero(sendbuf, sizeof(sendbuf));
 295        }
 296     } else if(Ustrlen(sendbuf) + dcchdr->slen > sizeof(sendbuf)-2) {
 297       flushbuffer(sockfd, sendbuf);
 298       bzero(sendbuf, sizeof(sendbuf));
 299       Ustrncpy(sendbuf, dcchdr->text, sizeof(sendbuf)-2);
 300     } else {
 301       Ustrncat(sendbuf, dcchdr->text, sizeof(sendbuf)-Ustrlen(sendbuf)-2);
 302     }
 303   }
 304
 305   /* a blank line seperates header from body */
 306   Ustrncat(sendbuf, "\n", sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 307   flushbuffer(sockfd, sendbuf);
 308   DEBUG(D_acl)
 309     debug_printf("\nDCC: ****************************\n%s", sendbuf);
 310
 311   /* Clear the input buffer */
 312   bzero(sendbuf, sizeof(sendbuf));
 313
 314   /* now send the body */
 315   DEBUG(D_acl)
 316     debug_printf("DCC: Writing body:\nDCC: ****************************\n");
 317   (void)fseek(data_file, SPOOL_DATA_START_OFFSET, SEEK_SET);
 318   while((fread(sendbuf, 1, sizeof(sendbuf)-1, data_file)) > 0) {
 319     flushbuffer(sockfd, sendbuf);
 320     bzero(sendbuf, sizeof(sendbuf));
 321   }
 322   DEBUG(D_acl)
 323     debug_printf("\nDCC: ****************************\n");
 324
 325   /* shutdown() the socket */
 326   if(shutdown(sockfd, 1) < 0){
 327     DEBUG(D_acl)
 328       debug_printf("DCC: Couldn't shutdown socket: %s\n", strerror(errno));
 329     log_write(0,LOG_MAIN,"DCC: Couldn't shutdown socket: %s\n", strerror(errno));
 330     /* If there is a problem with the shutdown()
 331      * defer the mail. */
 332     (void)fclose(data_file);
 333     return retval;
 334   }
 335   DEBUG(D_acl)
 336     debug_printf("\nDCC: -------------------------\nDCC: Input sent.\nDCC: -------------------------\n");
 337
 338     /********************************
 339    * receiving output from dccifd *
 340    ********************************/
 341   DEBUG(D_acl)
 342     debug_printf("\nDCC: -------------------------------------\nDCC: Now receiving output from server\nDCC: -----------------------------------\n");
 343
 344   /******************************************************************
 345    * We should get 3 lines:                                         *
 346    * 1/ First line is overall result: either 'A' for Accept,        *
 347    *    'R' for Reject, 'S' for accept Some recipients or           *
 348    *    'T' for a Temporary error.                                  *
 349    * 2/ Second line contains the list of Accepted/Rejected          *
 350    *    recipients in the form AARRA (A = accepted, R = rejected).  *
 351    * 3/ Third line contains the X-DCC header.                       *
 352    ******************************************************************/
 353
 354   line = 1;    /* we start at the first line of the output */
 355   j = 0;       /* will be used as index for the recipients list */
 356   k = 0;       /* initializing the index of the X-DCC header: dcc_header_str[k] */
 357
 358   /* Let's read from the socket until there's nothing left to read */
 359   bzero(recvbuf, sizeof(recvbuf));
 360   while((resp = read(sockfd, recvbuf, sizeof(recvbuf)-1)) > 0) {
 361     /* How much did we get from the socket */
 362     c = Ustrlen(recvbuf) + 1;
 363     DEBUG(D_acl)
 364       debug_printf("DCC: Length of the output buffer is: %d\nDCC: Output buffer is:\nDCC: ------------\nDCC: %s\nDCC: -----------\n", c, recvbuf);
 365
 366     /* Now let's read each character and see what we've got */
 367     for(i = 0; i < c; i++) {
 368       /* First check if we reached the end of the line and
 369        * then increment the line counter */
 370       if(recvbuf[i] == '\n') {
 371         line++;
 372       }
 373       else {
 374         /* The first character of the first line is the
 375          * overall response. If there's another character
 376          * on that line it is not correct. */
 377         if(line == 1) {
 378           if(i == 0) {
 379             /* Now get the value and set the
 380              * return value accordingly */
 381             if(recvbuf[i] == 'A') {
 382               DEBUG(D_acl)
 383                 debug_printf("DCC: Overall result = A\treturning OK\n");
 384               Ustrcpy(dcc_return_text, "Mail accepted by DCC");
 385               dcc_result = US"A";
 386               retval = OK;
 387             }
 388             else if(recvbuf[i] == 'R') {
 389               DEBUG(D_acl)
 390                 debug_printf("DCC: Overall result = R\treturning FAIL\n");
 391               dcc_result = US"R";
 392               retval = FAIL;
 393               if(sender_host_name) {
 394                 log_write(0, LOG_MAIN, "H=%s [%s] F=<%s>: rejected by DCC", sender_host_name, sender_host_address, sender_address);
 395               }
 396               else {
 397                 log_write(0, LOG_MAIN, "H=[%s] F=<%s>: rejected by DCC", sender_host_address, sender_address);
 398               }
 399               Ustrncpy(dcc_return_text, dcc_reject_message, Ustrlen(dcc_reject_message) + 1);
 400             }
 401             else if(recvbuf[i] == 'S') {
 402               DEBUG(D_acl)
 403                 debug_printf("DCC: Overall result  = S\treturning OK\n");
 404               Ustrcpy(dcc_return_text, "Not all recipients accepted by DCC");
 405               /* Since we're in an ACL we want a global result
 406                * so we accept for all */
 407               dcc_result = US"A";
 408               retval = OK;
 409             }
 410             else if(recvbuf[i] == 'G') {
 411               DEBUG(D_acl)
 412                 debug_printf("DCC: Overall result  = G\treturning FAIL\n");
 413               Ustrcpy(dcc_return_text, "Greylisted by DCC");
 414               dcc_result = US"G";
 415               retval = FAIL;
 416             }
 417             else if(recvbuf[i] == 'T') {
 418               DEBUG(D_acl)
 419                 debug_printf("DCC: Overall result = T\treturning DEFER\n");
 420               retval = DEFER;
 421               log_write(0,LOG_MAIN,"Temporary error with DCC: %s\n", recvbuf);
 422               Ustrcpy(dcc_return_text, "Temporary error with DCC");
 423               dcc_result = US"T";
 424             }
 425             else {
 426               DEBUG(D_acl)
 427                 debug_printf("DCC: Overall result = something else\treturning DEFER\n");
 428               retval = DEFER;
 429               log_write(0,LOG_MAIN,"Unknown DCC response: %s\n", recvbuf);
 430               Ustrcpy(dcc_return_text, "Unknown DCC response");
 431               dcc_result = US"T";
 432             }
 433           }
 434           else {
 435           /* We're on the first line but not on the first character,
 436            * there must be something wrong. */
 437             DEBUG(D_acl)
 438               debug_printf("DCC: Line = %d but i = %d != 0  character is %c - This is wrong!\n", line, i, recvbuf[i]);
 439               log_write(0,LOG_MAIN,"Wrong header from DCC, output is %s\n", recvbuf);
 440           }
 441         }
 442         else if(line == 2) {
 443           /* On the second line we get a list of
 444            * answers for each recipient. We don't care about
 445            * it because we're in an acl and take the
 446            * global result. */
 447         }
 448         else if(line > 2) {
 449           /* The third and following lines are the X-DCC header,
 450            * so we store it in dcc_header_str. */
 451           /* check if we don't get more than we can handle */
 452           if(k < sizeof(dcc_header_str)) {
 453             dcc_header_str[k] = recvbuf[i];
 454             k++;
 455           }
 456           else {
 457             DEBUG(D_acl)
 458               debug_printf("DCC: We got more output than we can store in the X-DCC header. Truncating at 120 characters.\n");
 459           }
 460         }
 461         else {
 462           /* Wrong line number. There must be a problem with the output. */
 463           DEBUG(D_acl)
 464             debug_printf("DCC: Wrong line number in output. Line number is %d\n", line);
 465         }
 466       }
 467     }
 468     /* we reinitialize the output buffer before we read again */
 469     bzero(recvbuf,sizeof(recvbuf));
 470   }
 471   /* We have read everything from the socket */
 472
 473   /* We need to terminate the X-DCC header with a '\n' character. This needs to be k-1
 474    * since dcc_header_str[k] contains '\0'. */
 475   dcc_header_str[k-1] = '\n';
 476
 477   /* Now let's sum up what we've got. */
 478   DEBUG(D_acl)
 479     debug_printf("\nDCC: --------------------------\nDCC: Overall result = %d\nDCC: X-DCC header: %sReturn message: %s\nDCC: dcc_result: %s\n", retval, dcc_header_str, dcc_return_text, dcc_result);
 480
 481   /* We only add the X-DCC header if it starts with X-DCC */
 482   if(!(Ustrncmp(dcc_header_str, "X-DCC", 5))){
 483     dcc_header = dcc_header_str;
 484     if(dcc_direct_add_header) {
 485       header_add(' ' , "%s", dcc_header_str);
 486   /* since the MIME ACL already writes the .eml file to disk without DCC Header we've to erase it */
 487       unspool_mbox();
 488     }
 489   }
 490   else {
 491     DEBUG(D_acl)
 492       debug_printf("DCC: Wrong format of the X-DCC header: %s\n", dcc_header_str);
 493   }
 494
 495   /* check if we should add additional headers passed in acl_m_dcc_add_header */
 496   if(dcc_direct_add_header) {
 497     if (((xtra_hdrs = expand_string(US"$acl_m_dcc_add_header")) != NULL) && (xtra_hdrs[0] != '\0')) {
 498       Ustrncpy(dcc_xtra_hdrs, xtra_hdrs, sizeof(dcc_xtra_hdrs) - 2);
 499       if (dcc_xtra_hdrs[Ustrlen(dcc_xtra_hdrs)-1] != '\n')
 500         Ustrcat(dcc_xtra_hdrs, "\n");
 501       header_add(' ', "%s", dcc_xtra_hdrs);
 502       DEBUG(D_acl)
 503         debug_printf("DCC: adding additional headers in $acl_m_dcc_add_header: %s", dcc_xtra_hdrs);
 504     }
 505   }
 506
 507   dcc_ok = 1;
 508   /* Now return to exim main process */
 509   DEBUG(D_acl)
 510     debug_printf("DCC: Before returning to exim main process:\nDCC: return_text = %s - retval = %d\nDCC: dcc_result = %s\n", dcc_return_text, retval, dcc_result);
 511
 512   (void)fclose(data_file);
 513   dcc_rc = retval;
 514   return dcc_rc;
 515 }
 516
 517 #endif