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