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  * Copyright (c) The Exim Maintainers 2015 - 2016
  11  */
  12
  13 /* This patch is based on code from Tom Kistners exiscan (ACL integration) and
  14  * the DCC local_scan patch from Christopher Bodenstein */
  15
  16 /* Code for calling dccifd. Called from acl.c. */
  17
  18 #include "exim.h"
  19 #ifdef EXPERIMENTAL_DCC
  20 #include "dcc.h"
  21 #include "unistd.h"
  22
  23 uschar dcc_header_str[256];
  24 int dcc_ok = 0;
  25 int dcc_rc = 0;
  26
  27 /* This function takes a file descriptor and a buffer as input and
  28  * returns either 0 for success or errno in case of error. */
  29
  30 int flushbuffer (int socket, uschar *buffer)
  31  {
  32   int retval, rsp;
  33   rsp = write(socket, buffer, Ustrlen(buffer));
  34   DEBUG(D_acl)
  35     debug_printf("DCC: Result of the write() = %d\n", rsp);
  36   if(rsp < 0)
  37   {
  38     DEBUG(D_acl)
  39       debug_printf("DCC: Error writing buffer to socket: %s\n", strerror(errno));
  40     retval = errno;
  41   }
  42   else {
  43     DEBUG(D_acl)
  44       debug_printf("DCC: Wrote buffer to socket:\n%s\n", buffer);
  45     retval = 0;
  46   }
  47   return retval;
  48 }
  49
  50 int
  51 dcc_process(uschar **listptr)
  52 {
  53   int sep = 0;
  54   const uschar *list = *listptr;
  55   FILE *data_file;
  56   uschar *dcc_default_ip_option = US"127.0.0.1";
  57   uschar *dcc_helo_option = US"localhost";
  58   uschar *dcc_reject_message = US"Rejected by DCC";
  59   uschar *xtra_hdrs = NULL;
  60   uschar *override_client_ip  = NULL;
  61
  62   /* from local_scan */
  63   int i, j, k, c, retval, sockfd, resp, line;
  64   unsigned int portnr;
  65   struct sockaddr_un  serv_addr;
  66   struct sockaddr_in  serv_addr_in;
  67   struct hostent *ipaddress;
  68   uschar sockpath[128];
  69   uschar sockip[40], client_ip[40];
  70   uschar opts[128];
  71   uschar rcpt[128], from[128];
  72   uschar sendbuf[4096];
  73   uschar recvbuf[4096];
  74   uschar dcc_return_text[1024];
  75   uschar message_subdir[2];
  76   struct header_line *dcchdr;
  77   uschar *dcc_acl_options;
  78   uschar dcc_acl_options_buffer[10];
  79   uschar dcc_xtra_hdrs[1024];
  80
  81   /* grep 1st option */
  82   if ((dcc_acl_options = string_nextinlist(&list, &sep,
  83                    dcc_acl_options_buffer, sizeof(dcc_acl_options_buffer))))
  84     {
  85     /* parse 1st option */
  86     if (  strcmpic(dcc_acl_options, US"false") == 0
  87        || Ustrcmp(dcc_acl_options, "0") == 0
  88        )
  89       return FAIL;      /* explicitly no matching */
  90     }
  91   else
  92     return FAIL;        /* empty means "don't match anything" */
  93
  94   sep = 0;
  95
  96   /* if we scanned this message last time, just return */
  97   if (dcc_ok)
  98     return dcc_rc;
  99
 100   /* open the spooled body */
 101   message_subdir[1] = '\0';
 102   for (i = 0; i < 2; i++)
 103     {
 104     message_subdir[0] = split_spool_directory == (i == 0) ? message_id[5] : 0;
 105
 106     if ((data_file = Ufopen(
 107             spool_fname(US"input", message_subdir, message_id, US"-D"),
 108             "rb")))
 109       break;
 110     }
 111
 112   if (!data_file)
 113     {
 114     /* error while spooling */
 115     log_write(0, LOG_MAIN|LOG_PANIC,
 116            "dcc acl condition: error while opening spool file");
 117     return DEFER;
 118     }
 119
 120   /* Initialize the variables */
 121
 122   bzero(sockip,sizeof(sockip));
 123   if (dccifd_address) {
 124     if (dccifd_address[0] == '/')
 125       Ustrncpy(sockpath, dccifd_address, sizeof(sockpath));
 126     else
 127       if( sscanf(CS dccifd_address, "%s %u", sockip, &portnr) != 2) {
 128         log_write(0, LOG_MAIN,
 129           "dcc acl condition: warning - invalid dccifd address: '%s'", dccifd_address);
 130         (void)fclose(data_file);
 131         return DEFER;
 132       }
 133   }
 134
 135   /* opts is what we send as dccifd options - see man dccifd */
 136   /* We don't support any other option than 'header' so just copy that */
 137   bzero(opts,sizeof(opts));
 138   Ustrncpy(opts, dccifd_options, sizeof(opts)-1);
 139   /* if $acl_m_dcc_override_client_ip is set use it */
 140   if (((override_client_ip = expand_string(US"$acl_m_dcc_override_client_ip")) != NULL) &&
 141        (override_client_ip[0] != '\0')) {
 142     Ustrncpy(client_ip, override_client_ip, sizeof(client_ip)-1);
 143     DEBUG(D_acl)
 144       debug_printf("DCC: Client IP (overridden): %s\n", client_ip);
 145   }
 146   else if(sender_host_address) {
 147   /* else if $sender_host_address is available use that? */
 148     Ustrncpy(client_ip, sender_host_address, sizeof(client_ip)-1);
 149     DEBUG(D_acl)
 150       debug_printf("DCC: Client IP (sender_host_address): %s\n", client_ip);
 151   }
 152   else {
 153     /* sender_host_address is NULL which means it comes from localhost */
 154     Ustrncpy(client_ip, dcc_default_ip_option, sizeof(client_ip)-1);
 155     DEBUG(D_acl)
 156       debug_printf("DCC: Client IP (default): %s\n", client_ip);
 157   }
 158   /* strncat(opts, my_request, strlen(my_request)); */
 159   Ustrcat(opts, "\n");
 160   Ustrncat(opts, client_ip, sizeof(opts)-Ustrlen(opts)-1);
 161   Ustrncat(opts, "\nHELO ", sizeof(opts)-Ustrlen(opts)-1);
 162   Ustrncat(opts, dcc_helo_option, sizeof(opts)-Ustrlen(opts)-2);
 163   Ustrcat(opts, "\n");
 164
 165   /* initialize the other variables */
 166   dcchdr = header_list;
 167   /* we set the default return value to DEFER */
 168   retval = DEFER;
 169
 170   bzero(sendbuf,sizeof(sendbuf));
 171   bzero(dcc_header_str,sizeof(dcc_header_str));
 172   bzero(rcpt,sizeof(rcpt));
 173   bzero(from,sizeof(from));
 174
 175   /* send a null return path as "<>". */
 176   if (Ustrlen(sender_address) > 0)
 177     Ustrncpy(from, sender_address, sizeof(from));
 178   else
 179     Ustrncpy(from, "<>", sizeof(from));
 180   Ustrncat(from, "\n", sizeof(from)-Ustrlen(from)-1);
 181
 182   /**************************************
 183    * Now creating the socket connection *
 184    **************************************/
 185
 186   /* If sockip contains an ip, we use a tcp socket, otherwise a UNIX socket */
 187   if(Ustrcmp(sockip, "")){
 188     ipaddress = gethostbyname((char *)sockip);
 189     bzero((char *) &serv_addr_in, sizeof(serv_addr_in));
 190     serv_addr_in.sin_family = AF_INET;
 191     bcopy((char *)ipaddress->h_addr, (char *)&serv_addr_in.sin_addr.s_addr, ipaddress->h_length);
 192     serv_addr_in.sin_port = htons(portnr);
 193     if ((sockfd = socket(AF_INET, SOCK_STREAM,0)) < 0){
 194       DEBUG(D_acl)
 195         debug_printf("DCC: Creating TCP socket connection failed: %s\n", strerror(errno));
 196       log_write(0,LOG_PANIC,"DCC: Creating TCP socket connection failed: %s\n", strerror(errno));
 197       /* if we cannot create the socket, defer the mail */
 198       (void)fclose(data_file);
 199       return retval;
 200     }
 201     /* Now connecting the socket (INET) */
 202     if (connect(sockfd, (struct sockaddr *)&serv_addr_in, sizeof(serv_addr_in)) < 0){
 203       DEBUG(D_acl)
 204         debug_printf("DCC: Connecting to TCP socket failed: %s\n", strerror(errno));
 205       log_write(0,LOG_PANIC,"DCC: Connecting to TCP socket failed: %s\n", strerror(errno));
 206       /* if we cannot contact the socket, defer the mail */
 207       (void)fclose(data_file);
 208       return retval;
 209     }
 210   } else {
 211     /* connecting to the dccifd UNIX socket */
 212     bzero(&serv_addr, sizeof(serv_addr));
 213     serv_addr.sun_family = AF_UNIX;
 214     Ustrncpy(serv_addr.sun_path, sockpath, sizeof(serv_addr.sun_path));
 215     if ((sockfd = socket(AF_UNIX, SOCK_STREAM,0)) < 0){
 216       DEBUG(D_acl)
 217         debug_printf("DCC: Creating UNIX socket connection failed: %s\n", strerror(errno));
 218       log_write(0,LOG_PANIC,"DCC: Creating UNIX socket connection failed: %s\n", strerror(errno));
 219       /* if we cannot create the socket, defer the mail */
 220       (void)fclose(data_file);
 221       return retval;
 222     }
 223     /* Now connecting the socket (UNIX) */
 224     if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0){
 225       DEBUG(D_acl)
 226                             debug_printf("DCC: Connecting to UNIX socket failed: %s\n", strerror(errno));
 227       log_write(0,LOG_PANIC,"DCC: Connecting to UNIX socket failed: %s\n", strerror(errno));
 228       /* if we cannot contact the socket, defer the mail */
 229       (void)fclose(data_file);
 230       return retval;
 231     }
 232   }
 233   /* the socket is open, now send the options to dccifd*/
 234   DEBUG(D_acl)
 235     debug_printf("\nDCC: ---------------------------\nDCC: Socket opened; now sending input\nDCC: -----------------\n");
 236   /* First, fill in the input buffer */
 237   Ustrncpy(sendbuf, opts, sizeof(sendbuf));
 238   Ustrncat(sendbuf, from, sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 239
 240   DEBUG(D_acl)
 241   {
 242     debug_printf("DCC: opts = %s\nDCC: sender = %s\nDCC: rcpt count = %d\n", opts, from, recipients_count);
 243     debug_printf("DCC: Sending options:\nDCC: ****************************\n");
 244   }
 245
 246   /* let's send each of the recipients to dccifd */
 247   for (i = 0; i < recipients_count; i++){
 248     DEBUG(D_acl)
 249       debug_printf("DCC: recipient = %s\n",recipients_list[i].address);
 250     if(Ustrlen(sendbuf) + Ustrlen(recipients_list[i].address) > sizeof(sendbuf))
 251     {
 252       DEBUG(D_acl)
 253         debug_printf("DCC: Writing buffer: %s\n", sendbuf);
 254       flushbuffer(sockfd, sendbuf);
 255       bzero(sendbuf, sizeof(sendbuf));
 256     }
 257     Ustrncat(sendbuf, recipients_list[i].address, sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 258     Ustrncat(sendbuf, "\r\n", sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 259   }
 260   /* send a blank line between options and message */
 261   Ustrncat(sendbuf, "\n", sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 262   /* Now we send the input buffer */
 263   DEBUG(D_acl)
 264     debug_printf("DCC: %s\nDCC: ****************************\n", sendbuf);
 265   flushbuffer(sockfd, sendbuf);
 266
 267   /* now send the message */
 268   /* Clear the input buffer */
 269   bzero(sendbuf, sizeof(sendbuf));
 270   /* First send the headers */
 271   /* Now send the headers */
 272   DEBUG(D_acl)
 273     debug_printf("DCC: Sending headers:\nDCC: ****************************\n");
 274   Ustrncpy(sendbuf, dcchdr->text, sizeof(sendbuf)-2);
 275   while((dcchdr=dcchdr->next)) {
 276     if(dcchdr->slen > sizeof(sendbuf)-2) {
 277       /* The size of the header is bigger than the size of
 278        * the input buffer, so split it up in smaller parts. */
 279        flushbuffer(sockfd, sendbuf);
 280        bzero(sendbuf, sizeof(sendbuf));
 281        j = 0;
 282        while(j < dcchdr->slen)
 283        {
 284         for(i = 0; i < sizeof(sendbuf)-2; i++) {
 285           sendbuf[i] = dcchdr->text[j];
 286           j++;
 287         }
 288         flushbuffer(sockfd, sendbuf);
 289         bzero(sendbuf, sizeof(sendbuf));
 290        }
 291     } else if(Ustrlen(sendbuf) + dcchdr->slen > sizeof(sendbuf)-2) {
 292       flushbuffer(sockfd, sendbuf);
 293       bzero(sendbuf, sizeof(sendbuf));
 294       Ustrncpy(sendbuf, dcchdr->text, sizeof(sendbuf)-2);
 295     } else {
 296       Ustrncat(sendbuf, dcchdr->text, sizeof(sendbuf)-Ustrlen(sendbuf)-2);
 297     }
 298   }
 299
 300   /* a blank line separates header from body */
 301   Ustrncat(sendbuf, "\n", sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 302   flushbuffer(sockfd, sendbuf);
 303   DEBUG(D_acl)
 304     debug_printf("\nDCC: ****************************\n%s", sendbuf);
 305
 306   /* Clear the input buffer */
 307   bzero(sendbuf, sizeof(sendbuf));
 308
 309   /* now send the body */
 310   DEBUG(D_acl)
 311     debug_printf("DCC: Writing body:\nDCC: ****************************\n");
 312   (void)fseek(data_file, SPOOL_DATA_START_OFFSET, SEEK_SET);
 313   while((fread(sendbuf, 1, sizeof(sendbuf)-1, data_file)) > 0) {
 314     flushbuffer(sockfd, sendbuf);
 315     bzero(sendbuf, sizeof(sendbuf));
 316   }
 317   DEBUG(D_acl)
 318     debug_printf("\nDCC: ****************************\n");
 319
 320   /* shutdown() the socket */
 321   if(shutdown(sockfd, 1) < 0){
 322     DEBUG(D_acl)
 323       debug_printf("DCC: Couldn't shutdown socket: %s\n", strerror(errno));
 324     log_write(0,LOG_MAIN,"DCC: Couldn't shutdown socket: %s\n", strerror(errno));
 325     /* If there is a problem with the shutdown()
 326      * defer the mail. */
 327     (void)fclose(data_file);
 328     return retval;
 329   }
 330   DEBUG(D_acl)
 331     debug_printf("\nDCC: -------------------------\nDCC: Input sent.\nDCC: -------------------------\n");
 332
 333     /********************************
 334    * receiving output from dccifd *
 335    ********************************/
 336   DEBUG(D_acl)
 337     debug_printf("\nDCC: -------------------------------------\nDCC: Now receiving output from server\nDCC: -----------------------------------\n");
 338
 339   /******************************************************************
 340    * We should get 3 lines:                                         *
 341    * 1/ First line is overall result: either 'A' for Accept,        *
 342    *    'R' for Reject, 'S' for accept Some recipients or           *
 343    *    'T' for a Temporary error.                                  *
 344    * 2/ Second line contains the list of Accepted/Rejected          *
 345    *    recipients in the form AARRA (A = accepted, R = rejected).  *
 346    * 3/ Third line contains the X-DCC header.                       *
 347    ******************************************************************/
 348
 349   line = 1;    /* we start at the first line of the output */
 350   j = 0;       /* will be used as index for the recipients list */
 351   k = 0;       /* initializing the index of the X-DCC header: dcc_header_str[k] */
 352
 353   /* Let's read from the socket until there's nothing left to read */
 354   bzero(recvbuf, sizeof(recvbuf));
 355   while((resp = read(sockfd, recvbuf, sizeof(recvbuf)-1)) > 0) {
 356     /* How much did we get from the socket */
 357     c = Ustrlen(recvbuf) + 1;
 358     DEBUG(D_acl)
 359       debug_printf("DCC: Length of the output buffer is: %d\nDCC: Output buffer is:\nDCC: ------------\nDCC: %s\nDCC: -----------\n", c, recvbuf);
 360
 361     /* Now let's read each character and see what we've got */
 362     for(i = 0; i < c; i++) {
 363       /* First check if we reached the end of the line and
 364        * then increment the line counter */
 365       if(recvbuf[i] == '\n') {
 366         line++;
 367       }
 368       else {
 369         /* The first character of the first line is the
 370          * overall response. If there's another character
 371          * on that line it is not correct. */
 372         if(line == 1) {
 373           if(i == 0) {
 374             /* Now get the value and set the
 375              * return value accordingly */
 376             if(recvbuf[i] == 'A') {
 377               DEBUG(D_acl)
 378                 debug_printf("DCC: Overall result = A\treturning OK\n");
 379               Ustrcpy(dcc_return_text, "Mail accepted by DCC");
 380               dcc_result = US"A";
 381               retval = OK;
 382             }
 383             else if(recvbuf[i] == 'R') {
 384               DEBUG(D_acl)
 385                 debug_printf("DCC: Overall result = R\treturning FAIL\n");
 386               dcc_result = US"R";
 387               retval = FAIL;
 388               if(sender_host_name) {
 389                 log_write(0, LOG_MAIN, "H=%s [%s] F=<%s>: rejected by DCC", sender_host_name, sender_host_address, sender_address);
 390               }
 391               else {
 392                 log_write(0, LOG_MAIN, "H=[%s] F=<%s>: rejected by DCC", sender_host_address, sender_address);
 393               }
 394               Ustrncpy(dcc_return_text, dcc_reject_message, Ustrlen(dcc_reject_message) + 1);
 395             }
 396             else if(recvbuf[i] == 'S') {
 397               DEBUG(D_acl)
 398                 debug_printf("DCC: Overall result  = S\treturning OK\n");
 399               Ustrcpy(dcc_return_text, "Not all recipients accepted by DCC");
 400               /* Since we're in an ACL we want a global result
 401                * so we accept for all */
 402               dcc_result = US"A";
 403               retval = OK;
 404             }
 405             else if(recvbuf[i] == 'G') {
 406               DEBUG(D_acl)
 407                 debug_printf("DCC: Overall result  = G\treturning FAIL\n");
 408               Ustrcpy(dcc_return_text, "Greylisted by DCC");
 409               dcc_result = US"G";
 410               retval = FAIL;
 411             }
 412             else if(recvbuf[i] == 'T') {
 413               DEBUG(D_acl)
 414                 debug_printf("DCC: Overall result = T\treturning DEFER\n");
 415               retval = DEFER;
 416               log_write(0,LOG_MAIN,"Temporary error with DCC: %s\n", recvbuf);
 417               Ustrcpy(dcc_return_text, "Temporary error with DCC");
 418               dcc_result = US"T";
 419             }
 420             else {
 421               DEBUG(D_acl)
 422                 debug_printf("DCC: Overall result = something else\treturning DEFER\n");
 423               retval = DEFER;
 424               log_write(0,LOG_MAIN,"Unknown DCC response: %s\n", recvbuf);
 425               Ustrcpy(dcc_return_text, "Unknown DCC response");
 426               dcc_result = US"T";
 427             }
 428           }
 429           else {
 430             /* We're on the first line but not on the first character,
 431              * there must be something wrong. */
 432             DEBUG(D_acl) debug_printf("DCC: Line = %d but i = %d != 0"
 433                 "  character is %c - This is wrong!\n", line, i, recvbuf[i]);
 434             log_write(0,LOG_MAIN,"Wrong header from DCC, output is %s\n", recvbuf);
 435           }
 436         }
 437         else if(line == 2) {
 438           /* On the second line we get a list of
 439            * answers for each recipient. We don't care about
 440            * it because we're in an acl and take the
 441            * global result. */
 442         }
 443         else if(line > 2) {
 444           /* The third and following lines are the X-DCC header,
 445            * so we store it in dcc_header_str. */
 446           /* check if we don't get more than we can handle */
 447           if(k < sizeof(dcc_header_str)) {
 448             dcc_header_str[k] = recvbuf[i];
 449             k++;
 450           }
 451           else {
 452             DEBUG(D_acl) debug_printf("DCC: We got more output than we can store"
 453                 " in the X-DCC header. Truncating at 120 characters.\n");
 454           }
 455         }
 456         else {
 457           /* Wrong line number. There must be a problem with the output. */
 458           DEBUG(D_acl)
 459             debug_printf("DCC: Wrong line number in output. Line number is %d\n", line);
 460         }
 461       }
 462     }
 463     /* we reinitialize the output buffer before we read again */
 464     bzero(recvbuf,sizeof(recvbuf));
 465   }
 466   /* We have read everything from the socket */
 467
 468   /* We need to terminate the X-DCC header with a '\n' character. This needs to be k-1
 469    * since dcc_header_str[k] contains '\0'. */
 470   dcc_header_str[k-1] = '\n';
 471
 472   /* Now let's sum up what we've got. */
 473   DEBUG(D_acl)
 474     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);
 475
 476   /* We only add the X-DCC header if it starts with X-DCC */
 477   if(!(Ustrncmp(dcc_header_str, "X-DCC", 5))){
 478     dcc_header = dcc_header_str;
 479     if(dcc_direct_add_header) {
 480       header_add(' ' , "%s", dcc_header_str);
 481   /* since the MIME ACL already writes the .eml file to disk without DCC Header we've to erase it */
 482       unspool_mbox();
 483     }
 484   }
 485   else {
 486     DEBUG(D_acl)
 487       debug_printf("DCC: Wrong format of the X-DCC header: %s\n", dcc_header_str);
 488   }
 489
 490   /* check if we should add additional headers passed in acl_m_dcc_add_header */
 491   if(dcc_direct_add_header) {
 492     if (((xtra_hdrs = expand_string(US"$acl_m_dcc_add_header")) != NULL) && (xtra_hdrs[0] != '\0')) {
 493       Ustrncpy(dcc_xtra_hdrs, xtra_hdrs, sizeof(dcc_xtra_hdrs) - 2);
 494       if (dcc_xtra_hdrs[Ustrlen(dcc_xtra_hdrs)-1] != '\n')
 495         Ustrcat(dcc_xtra_hdrs, "\n");
 496       header_add(' ', "%s", dcc_xtra_hdrs);
 497       DEBUG(D_acl)
 498         debug_printf("DCC: adding additional headers in $acl_m_dcc_add_header: %s", dcc_xtra_hdrs);
 499     }
 500   }
 501
 502   dcc_ok = 1;
 503   /* Now return to exim main process */
 504   DEBUG(D_acl)
 505     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);
 506
 507   (void)fclose(data_file);
 508   dcc_rc = retval;
 509   return dcc_rc;
 510 }
 511
 512 #endif