src/src/dcc.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) Wolfgang Breyha 2005 - 2019
   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 - 2019
  11  */
  12
  13 /* Code for calling dccifd. Called from acl.c. */
  14
  15 #include "exim.h"
  16 #ifdef EXPERIMENTAL_DCC
  17 #include "dcc.h"
  18 #include "unistd.h"
  19
  20 #define DCC_HEADER_LIMIT 120
  21
  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, gstring *buffer)
  29 {
  30   int retval, rsp;
  31   rsp = write(socket, buffer->s, buffer->ptr);
  32   DEBUG(D_acl)
  33     debug_printf("DCC: flushbuffer(): Result of the write() = %d\n", rsp);
  34   if(rsp < 0) {
  35     DEBUG(D_acl)
  36       debug_printf("DCC: flushbuffer(): Error writing buffer to socket: %s\n", strerror(errno));
  37     retval = errno;
  38   }
  39   else {
  40     DEBUG(D_acl)
  41       debug_printf("DCC: flushbuffer(): Wrote buffer to socket:\n%.*s\n", buffer->ptr, buffer->s);
  42     retval = 0;
  43   }
  44   return retval;
  45 }
  46
  47 int
  48 dcc_process(uschar **listptr)
  49 {
  50   int sep = 0;
  51   const uschar *list = *listptr;
  52   FILE *data_file;
  53   uschar *dcc_default_ip_option = US"127.0.0.1";
  54   uschar *dcc_helo_option = US"localhost";
  55   uschar *xtra_hdrs = NULL;
  56   uschar *override_client_ip  = NULL;
  57
  58   /* from local_scan */
  59   int dcc_resplen, retval, sockfd, resp;
  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   gstring *dcc_headers;
  67   gstring *sendbuf;
  68   uschar *dcc_return_text;
  69   struct header_line *mail_headers;
  70   uschar *dcc_acl_options;
  71   gstring *dcc_xtra_hdrs;
  72   gstring *dcc_header_str;
  73
  74   /* grep 1st option */
  75   if ((dcc_acl_options = string_nextinlist(&list, &sep, NULL, 0))) {
  76     /* parse 1st option */
  77     if (  strcmpic(dcc_acl_options, US"false") == 0
  78        || Ustrcmp(dcc_acl_options, "0") == 0)
  79       return FAIL;      /* explicitly no matching */
  80   }
  81   else
  82     return FAIL;        /* empty means "don't match anything" */
  83
  84   sep = 0;
  85
  86   /* if we scanned this message last time, just return */
  87   if (dcc_ok)
  88     return dcc_rc;
  89
  90   /* open the spooled body */
  91   for (int i = 0; i < 2; i++) {
  92     uschar message_subdir[2];
  93     set_subdir_str(message_subdir, message_id, i);
  94     if ((data_file = Ufopen(
  95             spool_fname(US"input", message_subdir, message_id, US"-D"), "rb")))
  96       break;
  97   }
  98
  99   if (!data_file) {
 100     /* error while spooling */
 101     log_write(0, LOG_MAIN|LOG_PANIC,
 102            "DCC: error while opening spool file");
 103     return DEFER;
 104   }
 105
 106   /* Initialize the variables */
 107
 108   bzero(sockip,sizeof(sockip));
 109   if (dccifd_address) {
 110     if (dccifd_address[0] == '/')
 111       Ustrncpy(sockpath, dccifd_address, sizeof(sockpath));
 112     else
 113       if( sscanf(CS dccifd_address, "%s %u", sockip, &portnr) != 2) {
 114         log_write(0, LOG_MAIN,
 115           "DCC: warning - invalid dccifd address: '%s'", dccifd_address);
 116         (void)fclose(data_file);
 117         return DEFER;
 118       }
 119   }
 120
 121   /* dcc_headers is what we send as dccifd options - see man dccifd */
 122   /* We don't support any other option than 'header' so just copy that */
 123   dcc_headers = string_cat(NULL, dccifd_options);
 124   /* if $acl_m_dcc_override_client_ip is set use it */
 125   if (((override_client_ip = expand_string(US"$acl_m_dcc_override_client_ip")) != NULL) &&
 126        (override_client_ip[0] != '\0')) {
 127     Ustrncpy(client_ip, override_client_ip, sizeof(client_ip)-1);
 128     DEBUG(D_acl)
 129       debug_printf("DCC: Client IP (overridden): %s\n", client_ip);
 130   }
 131   else if(sender_host_address) {
 132   /* else if $sender_host_address is available use that? */
 133     Ustrncpy(client_ip, sender_host_address, sizeof(client_ip)-1);
 134     DEBUG(D_acl)
 135       debug_printf("DCC: Client IP (sender_host_address): %s\n", client_ip);
 136   }
 137   else {
 138     /* sender_host_address is NULL which means it comes from localhost */
 139     Ustrncpy(client_ip, dcc_default_ip_option, sizeof(client_ip)-1);
 140     DEBUG(D_acl)
 141       debug_printf("DCC: Client IP (default): %s\n", client_ip);
 142   }
 143   /* build options block */
 144   dcc_headers = string_append(dcc_headers, 5, US"\n", client_ip, US"\nHELO ", dcc_helo_option, US"\n");
 145
 146   /* initialize the other variables */
 147   mail_headers = header_list;
 148   /* we set the default return value to DEFER */
 149   retval = DEFER;
 150
 151   /* send a null return path as "<>". */
 152   dcc_headers = string_cat (dcc_headers, *sender_address ? sender_address : US"<>");
 153   dcc_headers = string_catn(dcc_headers, US"\n", 1);
 154
 155   /**************************************
 156    * Now creating the socket connection *
 157    **************************************/
 158
 159   /* If sockip contains an ip, we use a tcp socket, otherwise a UNIX socket */
 160   if(Ustrcmp(sockip, "")) {
 161     ipaddress = gethostbyname(CS sockip);
 162     bzero(CS  &serv_addr_in, sizeof(serv_addr_in));
 163     serv_addr_in.sin_family = AF_INET;
 164     bcopy(CS ipaddress->h_addr, CS &serv_addr_in.sin_addr.s_addr, ipaddress->h_length);
 165     serv_addr_in.sin_port = htons(portnr);
 166     if ((sockfd = socket(AF_INET, SOCK_STREAM,0)) < 0) {
 167       DEBUG(D_acl)
 168         debug_printf("DCC: Creating TCP socket connection failed: %s\n", strerror(errno));
 169       log_write(0,LOG_PANIC,"DCC: Creating TCP socket connection failed: %s\n", strerror(errno));
 170       /* if we cannot create the socket, defer the mail */
 171       (void)fclose(data_file);
 172       return retval;
 173     }
 174     /* Now connecting the socket (INET) */
 175     if (connect(sockfd, (struct sockaddr *)&serv_addr_in, sizeof(serv_addr_in)) < 0) {
 176       DEBUG(D_acl)
 177         debug_printf("DCC: Connecting to TCP socket failed: %s\n", strerror(errno));
 178       log_write(0,LOG_PANIC,"DCC: Connecting to TCP socket failed: %s\n", strerror(errno));
 179       /* if we cannot contact the socket, defer the mail */
 180       (void)fclose(data_file);
 181       return retval;
 182     }
 183   }
 184   else {
 185     /* connecting to the dccifd UNIX socket */
 186     bzero(&serv_addr, sizeof(serv_addr));
 187     serv_addr.sun_family = AF_UNIX;
 188     Ustrncpy(US serv_addr.sun_path, sockpath, sizeof(serv_addr.sun_path));
 189     if ((sockfd = socket(AF_UNIX, SOCK_STREAM,0)) < 0) {
 190       DEBUG(D_acl)
 191         debug_printf("DCC: Creating UNIX socket connection failed: %s\n", strerror(errno));
 192       log_write(0,LOG_PANIC,"DCC: Creating UNIX socket connection failed: %s\n", strerror(errno));
 193       /* if we cannot create the socket, defer the mail */
 194       (void)fclose(data_file);
 195       return retval;
 196     }
 197     /* Now connecting the socket (UNIX) */
 198     if (connect(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr)) < 0) {
 199       DEBUG(D_acl)
 200         debug_printf("DCC: Connecting to UNIX socket failed: %s\n", strerror(errno));
 201       log_write(0,LOG_PANIC,"DCC: Connecting to UNIX socket failed: %s\n", strerror(errno));
 202       /* if we cannot contact the socket, defer the mail */
 203       (void)fclose(data_file);
 204       return retval;
 205     }
 206   }
 207   /* the socket is open, now send the options to dccifd*/
 208   DEBUG(D_acl)
 209     debug_printf("DCC: -----------------------------------\nDCC: Socket opened; now sending input\n"
 210                  "DCC: -----------------------------------\n");
 211
 212   /* let's send each of the recipients to dccifd */
 213   for (int i = 0; i < recipients_count; i++) {
 214     DEBUG(D_acl)
 215       debug_printf("DCC: recipient = %s\n",recipients_list[i].address);
 216     dcc_headers = string_append(dcc_headers, 2, recipients_list[i].address, "\n");
 217   }
 218   /* send a blank line between options and message */
 219   dcc_headers = string_catn(dcc_headers, US"\n", 1);
 220   /* Now we send the input buffer */
 221   (void) string_from_gstring(dcc_headers);
 222   DEBUG(D_acl)
 223     debug_printf("DCC: ***********************************\nDCC: Sending options:\n%s"
 224                  "DCC: ***********************************\n", dcc_headers->s);
 225   if (flushbuffer(sockfd, dcc_headers) != 0) {
 226       (void)fclose(data_file);
 227       return retval;
 228   }
 229
 230   /* now send the message */
 231   /* First send the headers */
 232   DEBUG(D_acl)
 233     debug_printf("DCC: ***********************************\nDCC: Sending headers:\n");
 234   sendbuf = string_get(8192);
 235   sendbuf = string_catn(sendbuf, mail_headers->text, mail_headers->slen);
 236   while((mail_headers=mail_headers->next)) {
 237     sendbuf = string_catn(sendbuf, mail_headers->text, mail_headers->slen);
 238   }
 239
 240   /* a blank line separates header from body */
 241   sendbuf = string_catn(sendbuf, US"\r\n", 2);
 242   (void) string_from_gstring(sendbuf);
 243   gstring_release_unused(sendbuf);
 244   DEBUG(D_acl)
 245     debug_printf("%sDCC: ***********************************\n", sendbuf->s);
 246   if (flushbuffer(sockfd, sendbuf) != 0) {
 247       (void)fclose(data_file);
 248       return retval;
 249   }
 250
 251   /* now send the body */
 252   DEBUG(D_acl)
 253     debug_printf("DCC: ***********************************\nDCC: Writing body:\n");
 254   (void)fseek(data_file, SPOOL_DATA_START_OFFSET, SEEK_SET);
 255
 256   gstring filebuf = { .size = big_buffer_size, .ptr = 0, .s = big_buffer };
 257
 258   while((filebuf.ptr = fread(filebuf.s, 1, filebuf.size, data_file)) > 0) {
 259     if (flushbuffer(sockfd, &filebuf) != 0) {
 260         (void)fclose(data_file);
 261         return retval;
 262     }
 263   }
 264   DEBUG(D_acl)
 265     debug_printf("DCC: ***********************************\n");
 266
 267   /* shutdown() the socket */
 268   if(shutdown(sockfd, SHUT_WR) < 0) {
 269     DEBUG(D_acl)
 270       debug_printf("DCC: Couldn't shutdown socket: %s\n", strerror(errno));
 271     log_write(0,LOG_MAIN,"DCC: Couldn't shutdown socket: %s\n", strerror(errno));
 272     /* If there is a problem with the shutdown()
 273      * defer the mail. */
 274     (void)fclose(data_file);
 275     return retval;
 276   }
 277   DEBUG(D_acl)
 278     debug_printf("DCC: Input sent.\n"
 279                  "DCC: +++++++++++++++++++++++++++++++++++\n"
 280                  "DCC: Now receiving output from server\n"
 281                  "DCC: -----------------------------------\n");
 282
 283   /********************************
 284    * receiving output from dccifd *
 285    ********************************/
 286
 287   /******************************************************************
 288    * We should get 3 lines:                                         *
 289    * 1/ First line is overall result: either 'A' for Accept,        *
 290    *    'R' for Reject, 'S' for accept Some recipients or           *
 291    *    'T' for a Temporary error.                                  *
 292    * 2/ Second line contains the list of Accepted/Rejected          *
 293    *    recipients in the form AARRA (A = accepted, R = rejected).  *
 294    * 3/ Third line contains the X-DCC header.                       *
 295    ******************************************************************/
 296
 297   int line = 1;    /* we start at the first line of the output */
 298   int bufoffset;
 299
 300   dcc_header_str = string_get(DCC_HEADER_LIMIT + 2);
 301   /* Let's read from the socket until there's nothing left to read */
 302   while((dcc_resplen = read(sockfd, big_buffer, big_buffer_size-1)) > 0) {
 303     /* fail on read error */
 304     if(dcc_resplen < 0) {
 305       DEBUG(D_acl)
 306         debug_printf("DCC: Error reading from socket: %s\n", strerror(errno));
 307       (void)fclose(data_file);
 308       return retval;
 309     }
 310     /* make the answer 0-terminated. only needed for debug_printf */
 311     DEBUG(D_acl)
 312       debug_printf("DCC: Length of the output buffer is: %d\nDCC: Output buffer is:\n"
 313                    "DCC: -----------------------------------\n%.*s\n"
 314                    "DCC: -----------------------------------\n", dcc_resplen, dcc_resplen, big_buffer);
 315
 316     /* Now let's read each character and see what we've got */
 317     for(bufoffset = 0; bufoffset < dcc_resplen, line <= 2; bufoffset++) {
 318       /* First check if we reached the end of the line and
 319        * then increment the line counter */
 320       if(big_buffer[bufoffset] == '\n')
 321         line++;
 322       else {
 323         /* The first character of the first line is the
 324          * overall response. If there's another character
 325          * on that line it is not correct. */
 326         if(line == 1) {
 327           if(bufoffset == 0) {
 328             /* Now get the value and set the
 329              * return value accordingly */
 330             switch(big_buffer[bufoffset]) {
 331               case 'A':
 332                 DEBUG(D_acl)
 333                   debug_printf("DCC: Overall result = A\treturning OK\n");
 334                 dcc_return_text = US"Mail accepted by DCC";
 335                 dcc_result = US"A";
 336                 retval = OK;
 337                 break;
 338               case 'R':
 339                 DEBUG(D_acl)
 340                   debug_printf("DCC: Overall result = R\treturning FAIL\n");
 341                 dcc_return_text = US"Rejected by DCC";
 342                 dcc_result = US"R";
 343                 retval = FAIL;
 344                 if(sender_host_name)
 345                   log_write(0, LOG_MAIN, "H=%s [%s] F=<%s>: rejected by DCC",
 346                              sender_host_name, sender_host_address, sender_address);
 347                 else
 348                   log_write(0, LOG_MAIN, "H=[%s] F=<%s>: rejected by DCC",
 349                              sender_host_address, sender_address);
 350                 break;
 351               case 'S':
 352                 DEBUG(D_acl)
 353                   debug_printf("DCC: Overall result  = S\treturning OK\n");
 354                 dcc_return_text = US"Not all recipients accepted by DCC";
 355                 /* Since we're in an ACL we want a global result
 356                  * so we accept for all */
 357                 dcc_result = US"A";
 358                 retval = OK;
 359                 break;
 360               case 'G':
 361                 DEBUG(D_acl)
 362                   debug_printf("DCC: Overall result  = G\treturning FAIL\n");
 363                 dcc_return_text = US"Greylisted by DCC";
 364                 dcc_result = US"G";
 365                 retval = FAIL;
 366                 break;
 367               case 'T':
 368                 DEBUG(D_acl)
 369                   debug_printf("DCC: Overall result = T\treturning DEFER\n");
 370                 dcc_return_text = US"Temporary error with DCC";
 371                 dcc_result = US"T";
 372                 retval = DEFER;
 373                 log_write(0,LOG_MAIN,"Temporary error with DCC: %s\n", big_buffer);
 374                 break;
 375               default:
 376                 DEBUG(D_acl)
 377                   debug_printf("DCC: Overall result = something else\treturning DEFER\n");
 378                 dcc_return_text = US"Unknown DCC response";
 379                 dcc_result = US"T";
 380                 retval = DEFER;
 381                 log_write(0,LOG_MAIN,"Unknown DCC response: %s\n", big_buffer);
 382                 break;
 383             }
 384           }
 385           else {
 386             /* We're on the first line but not on the first character,
 387              * there must be something wrong. */
 388             DEBUG(D_acl) debug_printf("DCC: Line = %d but bufoffset = %d != 0"
 389                 "  character is %c - This is wrong!\n", line, bufoffset, big_buffer[bufoffset]);
 390             log_write(0,LOG_MAIN,"Wrong header from DCC, output is %s\n", big_buffer);
 391           }
 392         }
 393         else if(line == 2) {
 394           /* On the second line we get a list of
 395            * answers for each recipient. We don't care about
 396            * it because we're in an acl and take the
 397            * global result. */
 398         }
 399       }
 400     }
 401     if(line > 2) {
 402       /* The third and following lines are the X-DCC header,
 403        * so we store it in dcc_header_str up to our limit. */
 404       /* check if buffer contains the end of the header .."\n\n" and truncate it */
 405       if ((big_buffer[dcc_resplen-1] == '\n') &&
 406           (big_buffer[dcc_resplen-2] == '\n'))
 407         dcc_resplen -= 2;
 408       dcc_resplen -= bufoffset;
 409       if (dcc_header_str->ptr + dcc_resplen > DCC_HEADER_LIMIT) {
 410         dcc_resplen = DCC_HEADER_LIMIT - dcc_header_str->ptr;
 411         DEBUG(D_acl) debug_printf("DCC: We got more output than we can store"
 412                            "in the X-DCC header. Truncating at 120 characters.\n");
 413       }
 414       dcc_header_str = string_catn(dcc_header_str, &big_buffer[bufoffset], dcc_resplen);
 415     }
 416   }
 417   /* We have read everything from the socket. make sure the header ends with "\n" */
 418   dcc_header_str = string_catn(dcc_header_str, US"\n", 1);
 419
 420   (void) string_from_gstring(dcc_header_str);
 421   /* Now let's sum up what we've got. */
 422   DEBUG(D_acl)
 423     debug_printf("\nDCC: --------------------------\nDCC: Overall result = %d\n"
 424                  "DCC: X-DCC header: %sReturn message: %s\nDCC: dcc_result: %s\n",
 425                    retval, dcc_header_str->s, dcc_return_text, dcc_result);
 426
 427   /* We only add the X-DCC header if it starts with X-DCC */
 428   if(!(Ustrncmp(dcc_header_str->s, "X-DCC", 5))) {
 429     dcc_header = dcc_header_str->s;
 430     if(dcc_direct_add_header) {
 431       header_add(' ' , "%s", dcc_header_str->s);
 432   /* since the MIME ACL already writes the .eml file to disk without DCC Header we've to erase it */
 433       unspool_mbox();
 434     }
 435   }
 436   else {
 437     DEBUG(D_acl)
 438       debug_printf("DCC: Wrong format of the X-DCC header: %.*s\n", dcc_header_str->ptr, dcc_header_str->s);
 439   }
 440
 441   /* check if we should add additional headers passed in acl_m_dcc_add_header */
 442   if(dcc_direct_add_header) {
 443     if (((xtra_hdrs = expand_string(US"$acl_m_dcc_add_header")) != NULL) && (xtra_hdrs[0] != '\0')) {
 444       dcc_xtra_hdrs = string_cat(NULL, xtra_hdrs);
 445       if (dcc_xtra_hdrs->s[dcc_xtra_hdrs->ptr - 1] != '\n')
 446         dcc_xtra_hdrs = string_catn(dcc_xtra_hdrs, US"\n", 1);
 447       header_add(' ', "%s", string_from_gstring(dcc_xtra_hdrs));
 448       DEBUG(D_acl)
 449         debug_printf("DCC: adding additional headers in $acl_m_dcc_add_header: %.*s", dcc_xtra_hdrs->ptr, dcc_xtra_hdrs->s);
 450     }
 451   }
 452
 453   dcc_ok = 1;
 454   /* Now return to exim main process */
 455   DEBUG(D_acl)
 456     debug_printf("DCC: Before returning to exim main process:\nDCC: return_text = %s - retval = %d\n"
 457                  "DCC: dcc_result = %s\n", dcc_return_text, retval, dcc_result);
 458
 459   (void)fclose(data_file);
 460   dcc_rc = retval;
 461   return dcc_rc;
 462 }
 463
 464 #endif