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 - 2018
  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 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   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   for (int i = 0; i < 2; i++)
 101     {
 102     uschar message_subdir[2];
 103     set_subdir_str(message_subdir, message_id, i);
 104     if ((data_file = Ufopen(
 105             spool_fname(US"input", message_subdir, message_id, US"-D"),
 106             "rb")))
 107       break;
 108     }
 109
 110   if (!data_file)
 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, US"\n");
 158   Ustrncat(opts, client_ip, sizeof(opts)-Ustrlen(opts)-1);
 159   Ustrncat(opts, US"\nHELO ", sizeof(opts)-Ustrlen(opts)-1);
 160   Ustrncat(opts, dcc_helo_option, sizeof(opts)-Ustrlen(opts)-2);
 161   Ustrcat(opts, US"\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, US"<>", sizeof(from));
 178   Ustrncat(from, US"\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(CS sockip);
 187     bzero(CS  &serv_addr_in, sizeof(serv_addr_in));
 188     serv_addr_in.sin_family = AF_INET;
 189     bcopy(CS ipaddress->h_addr, CS &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(US 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 (int 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, US"\r\n", sizeof(sendbuf)-Ustrlen(sendbuf)-1);
 257   }
 258   /* send a blank line between options and message */
 259   Ustrncat(sendbuf, US"\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(int 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 separates header from body */
 299   Ustrncat(sendbuf, US"\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(int 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       else {
 366         /* The first character of the first line is the
 367          * overall response. If there's another character
 368          * on that line it is not correct. */
 369         if(line == 1) {
 370           if(i == 0) {
 371             /* Now get the value and set the
 372              * return value accordingly */
 373             if(recvbuf[i] == 'A') {
 374               DEBUG(D_acl)
 375                 debug_printf("DCC: Overall result = A\treturning OK\n");
 376               Ustrcpy(dcc_return_text, US"Mail accepted by DCC");
 377               dcc_result = US"A";
 378               retval = OK;
 379             }
 380             else if(recvbuf[i] == 'R') {
 381               DEBUG(D_acl)
 382                 debug_printf("DCC: Overall result = R\treturning FAIL\n");
 383               dcc_result = US"R";
 384               retval = FAIL;
 385               if(sender_host_name) {
 386                 log_write(0, LOG_MAIN, "H=%s [%s] F=<%s>: rejected by DCC", sender_host_name, sender_host_address, sender_address);
 387               }
 388               else {
 389                 log_write(0, LOG_MAIN, "H=[%s] F=<%s>: rejected by DCC", sender_host_address, sender_address);
 390               }
 391               Ustrncpy(dcc_return_text, dcc_reject_message, Ustrlen(dcc_reject_message) + 1);
 392             }
 393             else if(recvbuf[i] == 'S') {
 394               DEBUG(D_acl)
 395                 debug_printf("DCC: Overall result  = S\treturning OK\n");
 396               Ustrcpy(dcc_return_text, US"Not all recipients accepted by DCC");
 397               /* Since we're in an ACL we want a global result
 398                * so we accept for all */
 399               dcc_result = US"A";
 400               retval = OK;
 401             }
 402             else if(recvbuf[i] == 'G') {
 403               DEBUG(D_acl)
 404                 debug_printf("DCC: Overall result  = G\treturning FAIL\n");
 405               Ustrcpy(dcc_return_text, US"Greylisted by DCC");
 406               dcc_result = US"G";
 407               retval = FAIL;
 408             }
 409             else if(recvbuf[i] == 'T') {
 410               DEBUG(D_acl)
 411                 debug_printf("DCC: Overall result = T\treturning DEFER\n");
 412               retval = DEFER;
 413               log_write(0,LOG_MAIN,"Temporary error with DCC: %s\n", recvbuf);
 414               Ustrcpy(dcc_return_text, US"Temporary error with DCC");
 415               dcc_result = US"T";
 416             }
 417             else {
 418               DEBUG(D_acl)
 419                 debug_printf("DCC: Overall result = something else\treturning DEFER\n");
 420               retval = DEFER;
 421               log_write(0,LOG_MAIN,"Unknown DCC response: %s\n", recvbuf);
 422               Ustrcpy(dcc_return_text, US"Unknown DCC response");
 423               dcc_result = US"T";
 424             }
 425           }
 426           else {
 427             /* We're on the first line but not on the first character,
 428              * there must be something wrong. */
 429             DEBUG(D_acl) debug_printf("DCC: Line = %d but i = %d != 0"
 430                 "  character is %c - This is wrong!\n", line, i, recvbuf[i]);
 431             log_write(0,LOG_MAIN,"Wrong header from DCC, output is %s\n", recvbuf);
 432           }
 433         }
 434         else if(line == 2) {
 435           /* On the second line we get a list of
 436            * answers for each recipient. We don't care about
 437            * it because we're in an acl and take the
 438            * global result. */
 439         }
 440         else if(line > 2) {
 441           /* The third and following lines are the X-DCC header,
 442            * so we store it in dcc_header_str. */
 443           /* check if we don't get more than we can handle */
 444           if(k < sizeof(dcc_header_str)) {
 445             dcc_header_str[k] = recvbuf[i];
 446             k++;
 447           }
 448           else {
 449             DEBUG(D_acl) debug_printf("DCC: We got more output than we can store"
 450                 " in the X-DCC header. Truncating at 120 characters.\n");
 451           }
 452         }
 453         else {
 454           /* Wrong line number. There must be a problem with the output. */
 455           DEBUG(D_acl)
 456             debug_printf("DCC: Wrong line number in output. Line number is %d\n", line);
 457         }
 458       }
 459     }
 460     /* we reinitialize the output buffer before we read again */
 461     bzero(recvbuf,sizeof(recvbuf));
 462   }
 463   /* We have read everything from the socket */
 464
 465   /* We need to terminate the X-DCC header with a '\n' character. This needs to be k-1
 466    * since dcc_header_str[k] contains '\0'. */
 467   dcc_header_str[k-1] = '\n';
 468
 469   /* Now let's sum up what we've got. */
 470   DEBUG(D_acl)
 471     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);
 472
 473   /* We only add the X-DCC header if it starts with X-DCC */
 474   if(!(Ustrncmp(dcc_header_str, "X-DCC", 5))){
 475     dcc_header = dcc_header_str;
 476     if(dcc_direct_add_header) {
 477       header_add(' ' , "%s", dcc_header_str);
 478   /* since the MIME ACL already writes the .eml file to disk without DCC Header we've to erase it */
 479       unspool_mbox();
 480     }
 481   }
 482   else {
 483     DEBUG(D_acl)
 484       debug_printf("DCC: Wrong format of the X-DCC header: %s\n", dcc_header_str);
 485   }
 486
 487   /* check if we should add additional headers passed in acl_m_dcc_add_header */
 488   if(dcc_direct_add_header) {
 489     if (((xtra_hdrs = expand_string(US"$acl_m_dcc_add_header")) != NULL) && (xtra_hdrs[0] != '\0')) {
 490       Ustrncpy(dcc_xtra_hdrs, xtra_hdrs, sizeof(dcc_xtra_hdrs) - 2);
 491       if (dcc_xtra_hdrs[Ustrlen(dcc_xtra_hdrs)-1] != '\n')
 492         Ustrcat(dcc_xtra_hdrs, US"\n");
 493       header_add(' ', "%s", dcc_xtra_hdrs);
 494       DEBUG(D_acl)
 495         debug_printf("DCC: adding additional headers in $acl_m_dcc_add_header: %s", dcc_xtra_hdrs);
 496     }
 497   }
 498
 499   dcc_ok = 1;
 500   /* Now return to exim main process */
 501   DEBUG(D_acl)
 502     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);
 503
 504   (void)fclose(data_file);
 505   dcc_rc = retval;
 506   return dcc_rc;
 507 }
 508
 509 #endif