src/src/dcc.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) Wolfgang Breyha 2005 - 2015
   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
  49 dcc_process(uschar **listptr)
  50 {
  51   int sep = 0;
  52   const uschar *list = *listptr;
  53   FILE *data_file;
  54   uschar *dcc_default_ip_option = US"127.0.0.1";
  55   uschar *dcc_helo_option = US"localhost";
  56   uschar *dcc_reject_message = US"Rejected by DCC";
  57   uschar *xtra_hdrs = NULL;
  58   uschar *override_client_ip  = NULL;
  59
  60   /* from local_scan */
  61   int i, j, k, c, retval, sockfd, resp, line;
  62   unsigned int portnr;
  63   struct sockaddr_un  serv_addr;
  64   struct sockaddr_in  serv_addr_in;
  65   struct hostent *ipaddress;
  66   uschar sockpath[128];
  67   uschar sockip[40], client_ip[40];
  68   uschar opts[128];
  69   uschar rcpt[128], from[128];
  70   uschar sendbuf[4096];
  71   uschar recvbuf[4096];
  72   uschar dcc_return_text[1024];
  73   uschar mbox_path[1024];
  74   uschar message_subdir[2];
  75   struct header_line *dcchdr;
  76   uschar *dcc_acl_options;
  77   uschar dcc_acl_options_buffer[10];
  78   uschar dcc_xtra_hdrs[1024];
  79
  80   /* grep 1st option */
  81   if ((dcc_acl_options = string_nextinlist(&list, &sep,
  82                                            dcc_acl_options_buffer,
  83                                            sizeof(dcc_acl_options_buffer))) != NULL)
  84   {
  85     /* parse 1st option */
  86     if ( (strcmpic(dcc_acl_options,US"false") == 0) ||
  87          (Ustrcmp(dcc_acl_options,"0") == 0) ) {
  88       /* explicitly no matching */
  89       return FAIL;
  90     };
  91
  92     /* special cases (match anything except empty) */
  93     if ( (strcmpic(dcc_acl_options,US"true") == 0) ||
  94          (Ustrcmp(dcc_acl_options,"*") == 0) ||
  95          (Ustrcmp(dcc_acl_options,"1") == 0) ) {
  96       dcc_acl_options = dcc_acl_options;
  97     };
  98   }
  99   else {
 100     /* empty means "don't match anything" */
 101     return FAIL;
 102   };
 103
 104   sep = 0;
 105
 106   /* if we scanned this message last time, just return */
 107   if ( dcc_ok )
 108       return dcc_rc;
 109
 110   /* open the spooled body */
 111   message_subdir[1] = '\0';
 112   for (i = 0; i < 2; i++) {
 113     message_subdir[0] = (split_spool_directory == (i == 0))? message_id[5] : 0;
 114     sprintf(CS mbox_path, "%s/input/%s/%s-D", spool_directory, message_subdir, message_id);
 115     data_file = Ufopen(mbox_path,"rb");
 116     if (data_file != NULL)
 117       break;
 118   };
 119
 120   if (data_file == NULL) {
 121     /* error while spooling */
 122     log_write(0, LOG_MAIN|LOG_PANIC,
 123            "dcc acl condition: error while opening spool file");
 124     return DEFER;
 125   };
 126
 127   /* Initialize the variables */
 128
 129   bzero(sockip,sizeof(sockip));
 130   if (dccifd_address) {
 131     if (dccifd_address[0] == '/')
 132       Ustrncpy(sockpath, dccifd_address, sizeof(sockpath));
 133     else
 134       if( sscanf(CS dccifd_address, "%s %u", sockip, &portnr) != 2) {
 135         log_write(0, LOG_MAIN,
 136           "dcc acl condition: warning - invalid dccifd address: '%s'", dccifd_address);
 137         (void)fclose(data_file);
 138         return DEFER;
 139       }
 140   }
 141
 142   /* opts is what we send as dccifd options - see man dccifd */
 143   /* We don't support any other option than 'header' so just copy that */
 144   bzero(opts,sizeof(opts));
 145   Ustrncpy(opts, dccifd_options, sizeof(opts)-1);
 146   /* if $acl_m_dcc_override_client_ip is set use it */
 147   if (((override_client_ip = expand_string(US"$acl_m_dcc_override_client_ip")) != NULL) &&
 148        (override_client_ip[0] != '\0')) {
 149     Ustrncpy(client_ip, override_client_ip, sizeof(client_ip)-1);
 150     DEBUG(D_acl)
 151       debug_printf("DCC: Client IP (overridden): %s\n", client_ip);
 152   }
 153   else if(sender_host_address) {
 154   /* else if $sender_host_address is available use that? */
 155     Ustrncpy(client_ip, sender_host_address, sizeof(client_ip)-1);
 156     DEBUG(D_acl)
 157       debug_printf("DCC: Client IP (sender_host_address): %s\n", client_ip);
 158   }
 159   else {
 160     /* sender_host_address is NULL which means it comes from localhost */
 161     Ustrncpy(client_ip, dcc_default_ip_option, sizeof(client_ip)-1);
 162     DEBUG(D_acl)
 163       debug_printf("DCC: Client IP (default): %s\n", client_ip);
 164   }
 165   /* strncat(opts, my_request, strlen(my_request)); */
 166   Ustrcat(opts, "\n");
 167   Ustrncat(opts, client_ip, sizeof(opts)-Ustrlen(opts)-1);
 168   Ustrncat(opts, "\nHELO ", sizeof(opts)-Ustrlen(opts)-1);
 169   Ustrncat(opts, dcc_helo_option, sizeof(opts)-Ustrlen(opts)-2);
 170   Ustrcat(opts, "\n");
 171
 172   /* initialize the other variables */
 173   dcchdr = header_list;
 174   /* we set the default return value to DEFER */
 175   retval = DEFER;
 176
 177   bzero(sendbuf,sizeof(sendbuf));
 178   bzero(dcc_header_str,sizeof(dcc_header_str));
 179   bzero(rcpt,sizeof(rcpt));
 180   bzero(from,sizeof(from));
 181
 182   /* send a null return path as "<>". */
 183   if (Ustrlen(sender_address) > 0)
 184     Ustrncpy(from, sender_address, sizeof(from));
 185   else
 186     Ustrncpy(from, "<>", sizeof(from));
 187   Ustrncat(from, "\n", sizeof(from)-Ustrlen(from)-1);
 188
 189   /**************************************
 190    * Now creating the socket connection *
 191    **************************************/
 192
 193   /* If sockip contains an ip, we use a tcp socket, otherwise a UNIX socket */
 194   if(Ustrcmp(sockip, "")){
 195     ipaddress = gethostbyname((char *)sockip);
 196     bzero((char *) &serv_addr_in, sizeof(serv_addr_in));
 197     serv_addr_in.sin_family = AF_INET;
 198     bcopy((char *)ipaddress->h_addr, (char *)&serv_addr_in.sin_addr.s_addr, ipaddress->h_length);
 199     serv_addr_in.sin_port = htons(portnr);
 200     if ((sockfd = socket(AF_INET, SOCK_STREAM,0)) < 0){
 201       DEBUG(D_acl)
 202         debug_printf("DCC: Creating TCP socket connection failed: %s\n", strerror(errno));
 203       log_write(0,LOG_PANIC,"DCC: Creating TCP socket connection failed: %s\n", strerror(errno));
 204       /* if we cannot create the socket, defer the mail */
 205       (void)fclose(data_file);
 206       return retval;
 207     }
 208     /* Now connecting the socket (INET) */
 209     if (connect(sockfd, (struct sockaddr *)&serv_addr_in, sizeof(serv_addr_in)) < 0){
 210       DEBUG(D_acl)
 211         debug_printf("DCC: Connecting to TCP socket failed: %s\n", strerror(errno));
 212       log_write(0,LOG_PANIC,"DCC: Connecting to TCP socket failed: %s\n", strerror(errno));
 213       /* if we cannot contact the socket, defer the mail */
 214       (void)fclose(data_file);
 215       return retval;
 216     }
 217   } else {
 218     /* connecting to the dccifd UNIX socket */
 219     bzero(&serv_addr, sizeof(serv_addr));
 220     serv_addr.sun_family = AF_UNIX;
 221     Ustrncpy(serv_addr.sun_path, sockpath, sizeof(serv_addr.sun_path));
 222     if ((sockfd = socket(AF_UNIX, SOCK_STREAM,0)) < 0){
 223       DEBUG(D_acl)
 224         debug_printf("DCC: Creating UNIX socket connection failed: %s\n", strerror(errno));
 225       log_write(0,LOG_PANIC,"DCC: Creating UNIX socket connection failed: %s\n", strerror(errno));
 226       /* if we cannot create the socket, defer the mail */
 227       (void)fclose(data_file);
 228       return retval;
 229     }
 230     /* Now connecting the socket (UNIX) */
 231     if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0){
 232       DEBUG(D_acl)
 233                             debug_printf("DCC: Connecting to UNIX socket failed: %s\n", strerror(errno));
 234       log_write(0,LOG_PANIC,"DCC: Connecting to UNIX socket failed: %s\n", strerror(errno));
 235       /* if we cannot contact the socket, defer the mail */
 236       (void)fclose(data_file);
 237       return retval;
 238     }
 239   }
 240   /* the socket is open, now send the options to dccifd*/
 241   DEBUG(D_acl)
 242     debug_printf("\nDCC: ---------------------------\nDCC: Socket opened; now sending input\nDCC: -----------------\n");
 243   /* First, fill in the input buffer */
 244   Ustrncpy(sendbuf, opts, sizeof(sendbuf));
 245   Ustrncat(sendbuf, from, sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 246
 247   DEBUG(D_acl)
 248   {
 249     debug_printf("DCC: opts = %s\nDCC: sender = %s\nDCC: rcpt count = %d\n", opts, from, recipients_count);
 250     debug_printf("DCC: Sending options:\nDCC: ****************************\n");
 251   }
 252
 253   /* let's send each of the recipients to dccifd */
 254   for (i = 0; i < recipients_count; i++){
 255     DEBUG(D_acl)
 256       debug_printf("DCC: recipient = %s\n",recipients_list[i].address);
 257     if(Ustrlen(sendbuf) + Ustrlen(recipients_list[i].address) > sizeof(sendbuf))
 258     {
 259       DEBUG(D_acl)
 260         debug_printf("DCC: Writing buffer: %s\n", sendbuf);
 261       flushbuffer(sockfd, sendbuf);
 262       bzero(sendbuf, sizeof(sendbuf));
 263     }
 264     Ustrncat(sendbuf, recipients_list[i].address, sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 265     Ustrncat(sendbuf, "\r\n", sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 266   }
 267   /* send a blank line between options and message */
 268   Ustrncat(sendbuf, "\n", sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 269   /* Now we send the input buffer */
 270   DEBUG(D_acl)
 271     debug_printf("DCC: %s\nDCC: ****************************\n", sendbuf);
 272   flushbuffer(sockfd, sendbuf);
 273
 274   /* now send the message */
 275   /* Clear the input buffer */
 276   bzero(sendbuf, sizeof(sendbuf));
 277   /* First send the headers */
 278   /* Now send the headers */
 279   DEBUG(D_acl)
 280     debug_printf("DCC: Sending headers:\nDCC: ****************************\n");
 281   Ustrncpy(sendbuf, dcchdr->text, sizeof(sendbuf)-2);
 282   while((dcchdr=dcchdr->next)) {
 283     if(dcchdr->slen > sizeof(sendbuf)-2) {
 284       /* The size of the header is bigger than the size of
 285        * the input buffer, so split it up in smaller parts. */
 286        flushbuffer(sockfd, sendbuf);
 287        bzero(sendbuf, sizeof(sendbuf));
 288        j = 0;
 289        while(j < dcchdr->slen)
 290        {
 291         for(i = 0; i < sizeof(sendbuf)-2; i++) {
 292           sendbuf[i] = dcchdr->text[j];
 293           j++;
 294         }
 295         flushbuffer(sockfd, sendbuf);
 296         bzero(sendbuf, sizeof(sendbuf));
 297        }
 298     } else if(Ustrlen(sendbuf) + dcchdr->slen > sizeof(sendbuf)-2) {
 299       flushbuffer(sockfd, sendbuf);
 300       bzero(sendbuf, sizeof(sendbuf));
 301       Ustrncpy(sendbuf, dcchdr->text, sizeof(sendbuf)-2);
 302     } else {
 303       Ustrncat(sendbuf, dcchdr->text, sizeof(sendbuf)-Ustrlen(sendbuf)-2);
 304     }
 305   }
 306
 307   /* a blank line seperates header from body */
 308   Ustrncat(sendbuf, "\n", sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 309   flushbuffer(sockfd, sendbuf);
 310   DEBUG(D_acl)
 311     debug_printf("\nDCC: ****************************\n%s", sendbuf);
 312
 313   /* Clear the input buffer */
 314   bzero(sendbuf, sizeof(sendbuf));
 315
 316   /* now send the body */
 317   DEBUG(D_acl)
 318     debug_printf("DCC: Writing body:\nDCC: ****************************\n");
 319   (void)fseek(data_file, SPOOL_DATA_START_OFFSET, SEEK_SET);
 320   while((fread(sendbuf, 1, sizeof(sendbuf)-1, data_file)) > 0) {
 321     flushbuffer(sockfd, sendbuf);
 322     bzero(sendbuf, sizeof(sendbuf));
 323   }
 324   DEBUG(D_acl)
 325     debug_printf("\nDCC: ****************************\n");
 326
 327   /* shutdown() the socket */
 328   if(shutdown(sockfd, 1) < 0){
 329     DEBUG(D_acl)
 330       debug_printf("DCC: Couldn't shutdown socket: %s\n", strerror(errno));
 331     log_write(0,LOG_MAIN,"DCC: Couldn't shutdown socket: %s\n", strerror(errno));
 332     /* If there is a problem with the shutdown()
 333      * defer the mail. */
 334     (void)fclose(data_file);
 335     return retval;
 336   }
 337   DEBUG(D_acl)
 338     debug_printf("\nDCC: -------------------------\nDCC: Input sent.\nDCC: -------------------------\n");
 339
 340     /********************************
 341    * receiving output from dccifd *
 342    ********************************/
 343   DEBUG(D_acl)
 344     debug_printf("\nDCC: -------------------------------------\nDCC: Now receiving output from server\nDCC: -----------------------------------\n");
 345
 346   /******************************************************************
 347    * We should get 3 lines:                                         *
 348    * 1/ First line is overall result: either 'A' for Accept,        *
 349    *    'R' for Reject, 'S' for accept Some recipients or           *
 350    *    'T' for a Temporary error.                                  *
 351    * 2/ Second line contains the list of Accepted/Rejected          *
 352    *    recipients in the form AARRA (A = accepted, R = rejected).  *
 353    * 3/ Third line contains the X-DCC header.                       *
 354    ******************************************************************/
 355
 356   line = 1;    /* we start at the first line of the output */
 357   j = 0;       /* will be used as index for the recipients list */
 358   k = 0;       /* initializing the index of the X-DCC header: dcc_header_str[k] */
 359
 360   /* Let's read from the socket until there's nothing left to read */
 361   bzero(recvbuf, sizeof(recvbuf));
 362   while((resp = read(sockfd, recvbuf, sizeof(recvbuf)-1)) > 0) {
 363     /* How much did we get from the socket */
 364     c = Ustrlen(recvbuf) + 1;
 365     DEBUG(D_acl)
 366       debug_printf("DCC: Length of the output buffer is: %d\nDCC: Output buffer is:\nDCC: ------------\nDCC: %s\nDCC: -----------\n", c, recvbuf);
 367
 368     /* Now let's read each character and see what we've got */
 369     for(i = 0; i < c; i++) {
 370       /* First check if we reached the end of the line and
 371        * then increment the line counter */
 372       if(recvbuf[i] == '\n') {
 373         line++;
 374       }
 375       else {
 376         /* The first character of the first line is the
 377          * overall response. If there's another character
 378          * on that line it is not correct. */
 379         if(line == 1) {
 380           if(i == 0) {
 381             /* Now get the value and set the
 382              * return value accordingly */
 383             if(recvbuf[i] == 'A') {
 384               DEBUG(D_acl)
 385                 debug_printf("DCC: Overall result = A\treturning OK\n");
 386               Ustrcpy(dcc_return_text, "Mail accepted by DCC");
 387               dcc_result = US"A";
 388               retval = OK;
 389             }
 390             else if(recvbuf[i] == 'R') {
 391               DEBUG(D_acl)
 392                 debug_printf("DCC: Overall result = R\treturning FAIL\n");
 393               dcc_result = US"R";
 394               retval = FAIL;
 395               if(sender_host_name) {
 396                 log_write(0, LOG_MAIN, "H=%s [%s] F=<%s>: rejected by DCC", sender_host_name, sender_host_address, sender_address);
 397               }
 398               else {
 399                 log_write(0, LOG_MAIN, "H=[%s] F=<%s>: rejected by DCC", sender_host_address, sender_address);
 400               }
 401               Ustrncpy(dcc_return_text, dcc_reject_message, Ustrlen(dcc_reject_message) + 1);
 402             }
 403             else if(recvbuf[i] == 'S') {
 404               DEBUG(D_acl)
 405                 debug_printf("DCC: Overall result  = S\treturning OK\n");
 406               Ustrcpy(dcc_return_text, "Not all recipients accepted by DCC");
 407               /* Since we're in an ACL we want a global result
 408                * so we accept for all */
 409               dcc_result = US"A";
 410               retval = OK;
 411             }
 412             else if(recvbuf[i] == 'G') {
 413               DEBUG(D_acl)
 414                 debug_printf("DCC: Overall result  = G\treturning FAIL\n");
 415               Ustrcpy(dcc_return_text, "Greylisted by DCC");
 416               dcc_result = US"G";
 417               retval = FAIL;
 418             }
 419             else if(recvbuf[i] == 'T') {
 420               DEBUG(D_acl)
 421                 debug_printf("DCC: Overall result = T\treturning DEFER\n");
 422               retval = DEFER;
 423               log_write(0,LOG_MAIN,"Temporary error with DCC: %s\n", recvbuf);
 424               Ustrcpy(dcc_return_text, "Temporary error with DCC");
 425               dcc_result = US"T";
 426             }
 427             else {
 428               DEBUG(D_acl)
 429                 debug_printf("DCC: Overall result = something else\treturning DEFER\n");
 430               retval = DEFER;
 431               log_write(0,LOG_MAIN,"Unknown DCC response: %s\n", recvbuf);
 432               Ustrcpy(dcc_return_text, "Unknown DCC response");
 433               dcc_result = US"T";
 434             }
 435           }
 436           else {
 437             /* We're on the first line but not on the first character,
 438              * there must be something wrong. */
 439             DEBUG(D_acl) debug_printf("DCC: Line = %d but i = %d != 0"
 440                 "  character is %c - This is wrong!\n", line, i, recvbuf[i]);
 441             log_write(0,LOG_MAIN,"Wrong header from DCC, output is %s\n", recvbuf);
 442           }
 443         }
 444         else if(line == 2) {
 445           /* On the second line we get a list of
 446            * answers for each recipient. We don't care about
 447            * it because we're in an acl and take the
 448            * global result. */
 449         }
 450         else if(line > 2) {
 451           /* The third and following lines are the X-DCC header,
 452            * so we store it in dcc_header_str. */
 453           /* check if we don't get more than we can handle */
 454           if(k < sizeof(dcc_header_str)) {
 455             dcc_header_str[k] = recvbuf[i];
 456             k++;
 457           }
 458           else {
 459             DEBUG(D_acl) debug_printf("DCC: We got more output than we can store"
 460                 " in the X-DCC header. Truncating at 120 characters.\n");
 461           }
 462         }
 463         else {
 464           /* Wrong line number. There must be a problem with the output. */
 465           DEBUG(D_acl)
 466             debug_printf("DCC: Wrong line number in output. Line number is %d\n", line);
 467         }
 468       }
 469     }
 470     /* we reinitialize the output buffer before we read again */
 471     bzero(recvbuf,sizeof(recvbuf));
 472   }
 473   /* We have read everything from the socket */
 474
 475   /* We need to terminate the X-DCC header with a '\n' character. This needs to be k-1
 476    * since dcc_header_str[k] contains '\0'. */
 477   dcc_header_str[k-1] = '\n';
 478
 479   /* Now let's sum up what we've got. */
 480   DEBUG(D_acl)
 481     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);
 482
 483   /* We only add the X-DCC header if it starts with X-DCC */
 484   if(!(Ustrncmp(dcc_header_str, "X-DCC", 5))){
 485     dcc_header = dcc_header_str;
 486     if(dcc_direct_add_header) {
 487       header_add(' ' , "%s", dcc_header_str);
 488   /* since the MIME ACL already writes the .eml file to disk without DCC Header we've to erase it */
 489       unspool_mbox();
 490     }
 491   }
 492   else {
 493     DEBUG(D_acl)
 494       debug_printf("DCC: Wrong format of the X-DCC header: %s\n", dcc_header_str);
 495   }
 496
 497   /* check if we should add additional headers passed in acl_m_dcc_add_header */
 498   if(dcc_direct_add_header) {
 499     if (((xtra_hdrs = expand_string(US"$acl_m_dcc_add_header")) != NULL) && (xtra_hdrs[0] != '\0')) {
 500       Ustrncpy(dcc_xtra_hdrs, xtra_hdrs, sizeof(dcc_xtra_hdrs) - 2);
 501       if (dcc_xtra_hdrs[Ustrlen(dcc_xtra_hdrs)-1] != '\n')
 502         Ustrcat(dcc_xtra_hdrs, "\n");
 503       header_add(' ', "%s", dcc_xtra_hdrs);
 504       DEBUG(D_acl)
 505         debug_printf("DCC: adding additional headers in $acl_m_dcc_add_header: %s", dcc_xtra_hdrs);
 506     }
 507   }
 508
 509   dcc_ok = 1;
 510   /* Now return to exim main process */
 511   DEBUG(D_acl)
 512     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);
 513
 514   (void)fclose(data_file);
 515   dcc_rc = retval;
 516   return dcc_rc;
 517 }
 518
 519 #endif