src/src/spam.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) Tom Kistner <tom@duncanthrax.net> 2003-???? */
   6 /* License: GPL */
   7
   8 /* Code for calling spamassassin's spamd. Called from acl.c. */
   9
  10 #include "exim.h"
  11 #ifdef WITH_CONTENT_SCAN
  12 #include "spam.h"
  13
  14 uschar spam_score_buffer[16];
  15 uschar spam_score_int_buffer[16];
  16 uschar spam_bar_buffer[128];
  17 uschar spam_report_buffer[32600];
  18 uschar prev_user_name[128] = "";
  19 int spam_ok = 0;
  20 int spam_rc = 0;
  21 uschar *prev_spamd_address_work = NULL;
  22
  23 int
  24 spam(uschar **listptr)
  25 {
  26   int sep = 0;
  27   uschar *list = *listptr;
  28   uschar *user_name;
  29   uschar user_name_buffer[128];
  30   unsigned long mbox_size;
  31   FILE *mbox_file;
  32   int spamd_sock = -1;
  33   uschar spamd_buffer[32600];
  34   int i, j, offset, result;
  35   uschar spamd_version[8];
  36   uschar spamd_score_char;
  37   double spamd_threshold, spamd_score;
  38   int spamd_report_offset;
  39   uschar *p,*q;
  40   int override = 0;
  41   time_t start;
  42   size_t read, wrote;
  43   struct sockaddr_un server;
  44 #ifndef NO_POLL_H
  45   struct pollfd pollfd;
  46 #else                               /* Patch posted by Erik ? for OS X */
  47   struct timeval select_tv;         /* and applied by PH */
  48   fd_set select_fd;
  49 #endif
  50   uschar *spamd_address_work;
  51
  52   /* stop compiler warning */
  53   result = 0;
  54
  55   /* find the username from the option list */
  56   if ((user_name = string_nextinlist(&list, &sep,
  57                                      user_name_buffer,
  58                                      sizeof(user_name_buffer))) == NULL) {
  59     /* no username given, this means no scanning should be done */
  60     return FAIL;
  61   };
  62
  63   /* if username is "0" or "false", do not scan */
  64   if ( (Ustrcmp(user_name,"0") == 0) ||
  65        (strcmpic(user_name,US"false") == 0) ) {
  66     return FAIL;
  67   };
  68
  69   /* if there is an additional option, check if it is "true" */
  70   if (strcmpic(list,US"true") == 0) {
  71     /* in that case, always return true later */
  72     override = 1;
  73   };
  74
  75   /* expand spamd_address if needed */
  76   if (*spamd_address == '$') {
  77     spamd_address_work = expand_string(spamd_address);
  78     if (spamd_address_work == NULL) {
  79       log_write(0, LOG_MAIN|LOG_PANIC,
  80         "spamassassin acl condition: spamd_address starts with $, but expansion failed: %s", expand_string_message);
  81       return DEFER;
  82     }
  83   }
  84   else
  85     spamd_address_work = spamd_address;
  86
  87   /* check if previous spamd_address was expanded and has changed. dump cached results if so */
  88   if ( spam_ok && ( prev_spamd_address_work != NULL) && (Ustrcmp(prev_spamd_address_work, spamd_address_work) != 0)) {
  89     spam_ok = 0;
  90   }
  91
  92   /* if we scanned for this username last time, just return */
  93   if ( spam_ok && ( Ustrcmp(prev_user_name, user_name) == 0 ) ) {
  94     if (override)
  95       return OK;
  96     else
  97       return spam_rc;
  98   };
  99
 100   /* make sure the eml mbox file is spooled up */
 101   mbox_file = spool_mbox(&mbox_size, NULL);
 102
 103   if (mbox_file == NULL) {
 104     /* error while spooling */
 105     log_write(0, LOG_MAIN|LOG_PANIC,
 106            "spam acl condition: error while creating mbox spool file");
 107     return DEFER;
 108   };
 109
 110   start = time(NULL);
 111
 112   /* socket does not start with '/' -> network socket */
 113   if (*spamd_address_work != '/') {
 114     int num_servers = 0;
 115     int current_server;
 116     uschar *address = NULL;
 117     uschar *spamd_address_list_ptr = spamd_address_work;
 118     uschar address_buffer[256];
 119     spamd_address_container * spamd_address_vector[32];
 120
 121     /* Check how many spamd servers we have
 122        and register their addresses */
 123     while ((address = string_nextinlist(&spamd_address_list_ptr, &sep,
 124                                         address_buffer,
 125                                         sizeof(address_buffer))) != NULL) {
 126
 127       /* Potential memory leak as we never free the store. */
 128       spamd_address_container *this_spamd =
 129         (spamd_address_container *)store_get(sizeof(spamd_address_container));
 130
 131       /* grok spamd address and port */
 132       if (sscanf(CS address, "%23s %u", this_spamd->tcp_addr, &(this_spamd->tcp_port)) != 2)
 133         {
 134         log_write(0, LOG_MAIN,
 135           "spam acl condition: warning - invalid spamd address: '%s'", address);
 136         continue;
 137       };
 138
 139       spamd_address_vector[num_servers] = this_spamd;
 140       num_servers++;
 141       if (num_servers > 31)
 142         break;
 143     };
 144
 145     /* check if we have at least one server */
 146     if (!num_servers) {
 147       log_write(0, LOG_MAIN|LOG_PANIC,
 148          "spam acl condition: no useable spamd server addresses in spamd_address configuration option.");
 149       (void)fclose(mbox_file);
 150       return DEFER;
 151     };
 152
 153     while ( num_servers > 0 ) {
 154       int i;
 155
 156       /* Randomly pick a server to try */
 157       current_server = random_number( num_servers );
 158
 159       debug_printf("trying server %s, port %u\n",
 160                    spamd_address_vector[current_server]->tcp_addr,
 161                    spamd_address_vector[current_server]->tcp_port);
 162
 163       /* contact a spamd */
 164       if ( (spamd_sock = ip_socket(SOCK_STREAM, AF_INET)) < 0) {
 165         log_write(0, LOG_MAIN|LOG_PANIC,
 166            "spam acl condition: error creating IP socket for spamd");
 167         (void)fclose(mbox_file);
 168         return DEFER;
 169       };
 170
 171       if (ip_connect( spamd_sock,
 172                       AF_INET,
 173                       spamd_address_vector[current_server]->tcp_addr,
 174                       spamd_address_vector[current_server]->tcp_port,
 175                       5 ) > -1) {
 176         /* connection OK */
 177         break;
 178       };
 179
 180       log_write(0, LOG_MAIN|LOG_PANIC,
 181          "spam acl condition: warning - spamd connection to %s, port %u failed: %s",
 182          spamd_address_vector[current_server]->tcp_addr,
 183          spamd_address_vector[current_server]->tcp_port,
 184          strerror(errno));
 185
 186       (void)close(spamd_sock);
 187
 188       /* Remove the server from the list. XXX We should free the memory */
 189       num_servers--;
 190       for( i = current_server; i < num_servers; i++ )
 191         spamd_address_vector[i] = spamd_address_vector[i+1];
 192     }
 193
 194     if ( num_servers == 0 ) {
 195       log_write(0, LOG_MAIN|LOG_PANIC, "spam acl condition: all spamd servers failed");
 196       (void)fclose(mbox_file);
 197       return DEFER;
 198     }
 199
 200   }
 201   else {
 202     /* open the local socket */
 203
 204     if ((spamd_sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
 205       log_write(0, LOG_MAIN|LOG_PANIC,
 206                 "malware acl condition: spamd: unable to acquire socket (%s)",
 207                 strerror(errno));
 208       (void)fclose(mbox_file);
 209       return DEFER;
 210     }
 211
 212     server.sun_family = AF_UNIX;
 213     Ustrcpy(server.sun_path, spamd_address_work);
 214
 215     if (connect(spamd_sock, (struct sockaddr *) &server, sizeof(struct sockaddr_un)) < 0) {
 216       log_write(0, LOG_MAIN|LOG_PANIC,
 217                 "malware acl condition: spamd: unable to connect to UNIX socket %s (%s)",
 218                 spamd_address_work, strerror(errno) );
 219       (void)fclose(mbox_file);
 220       (void)close(spamd_sock);
 221       return DEFER;
 222     }
 223
 224   }
 225
 226   if (spamd_sock == -1) {
 227     log_write(0, LOG_MAIN|LOG_PANIC,
 228         "programming fault, spamd_sock unexpectedly unset");
 229     (void)fclose(mbox_file);
 230     (void)close(spamd_sock);
 231     return DEFER;
 232   }
 233
 234   /* now we are connected to spamd on spamd_sock */
 235   (void)string_format(spamd_buffer,
 236            sizeof(spamd_buffer),
 237            "REPORT SPAMC/1.2\r\nUser: %s\r\nContent-length: %ld\r\n\r\n",
 238            user_name,
 239            mbox_size);
 240
 241   /* send our request */
 242   if (send(spamd_sock, spamd_buffer, Ustrlen(spamd_buffer), 0) < 0) {
 243     (void)close(spamd_sock);
 244     log_write(0, LOG_MAIN|LOG_PANIC,
 245          "spam acl condition: spamd send failed: %s", strerror(errno));
 246     (void)fclose(mbox_file);
 247     (void)close(spamd_sock);
 248     return DEFER;
 249   };
 250
 251   /* now send the file */
 252   /* spamd sometimes accepts conections but doesn't read data off
 253    * the connection.  We make the file descriptor non-blocking so
 254    * that the write will only write sufficient data without blocking
 255    * and we poll the desciptor to make sure that we can write without
 256    * blocking.  Short writes are gracefully handled and if the whole
 257    * trasaction takes too long it is aborted.
 258    * Note: poll() is not supported in OSX 10.2 and is reported to be
 259    *       broken in more recent versions (up to 10.4).
 260    */
 261 #ifndef NO_POLL_H
 262   pollfd.fd = spamd_sock;
 263   pollfd.events = POLLOUT;
 264 #endif
 265   (void)fcntl(spamd_sock, F_SETFL, O_NONBLOCK);
 266   do {
 267     read = fread(spamd_buffer,1,sizeof(spamd_buffer),mbox_file);
 268     if (read > 0) {
 269       offset = 0;
 270 again:
 271 #ifndef NO_POLL_H
 272       result = poll(&pollfd, 1, 1000);
 273
 274 /* Patch posted by Erik ? for OS X and applied by PH */
 275 #else
 276       select_tv.tv_sec = 1;
 277       select_tv.tv_usec = 0;
 278       FD_ZERO(&select_fd);
 279       FD_SET(spamd_sock, &select_fd);
 280       result = select(spamd_sock+1, NULL, &select_fd, NULL, &select_tv);
 281 #endif
 282 /* End Erik's patch */
 283
 284       if (result == -1 && errno == EINTR)
 285         goto again;
 286       else if (result < 1) {
 287         if (result == -1)
 288           log_write(0, LOG_MAIN|LOG_PANIC,
 289             "spam acl condition: %s on spamd socket", strerror(errno));
 290         else {
 291           if (time(NULL) - start < SPAMD_TIMEOUT)
 292             goto again;
 293           log_write(0, LOG_MAIN|LOG_PANIC,
 294             "spam acl condition: timed out writing spamd socket");
 295         }
 296         (void)close(spamd_sock);
 297         (void)fclose(mbox_file);
 298         return DEFER;
 299       }
 300
 301       wrote = send(spamd_sock,spamd_buffer + offset,read - offset,0);
 302       if (wrote == -1)
 303       {
 304           log_write(0, LOG_MAIN|LOG_PANIC,
 305             "spam acl condition: %s on spamd socket", strerror(errno));
 306         (void)close(spamd_sock);
 307         (void)fclose(mbox_file);
 308         return DEFER;
 309       }
 310       if (offset + wrote != read) {
 311         offset += wrote;
 312         goto again;
 313       }
 314     }
 315   }
 316   while (!feof(mbox_file) && !ferror(mbox_file));
 317   if (ferror(mbox_file)) {
 318     log_write(0, LOG_MAIN|LOG_PANIC,
 319       "spam acl condition: error reading spool file: %s", strerror(errno));
 320     (void)close(spamd_sock);
 321     (void)fclose(mbox_file);
 322     return DEFER;
 323   }
 324
 325   (void)fclose(mbox_file);
 326
 327   /* we're done sending, close socket for writing */
 328   shutdown(spamd_sock,SHUT_WR);
 329
 330   /* read spamd response using what's left of the timeout.
 331    */
 332   memset(spamd_buffer, 0, sizeof(spamd_buffer));
 333   offset = 0;
 334   while((i = ip_recv(spamd_sock,
 335                      spamd_buffer + offset,
 336                      sizeof(spamd_buffer) - offset - 1,
 337                      SPAMD_TIMEOUT - time(NULL) + start)) > 0 ) {
 338     offset += i;
 339   }
 340
 341   /* error handling */
 342   if((i <= 0) && (errno != 0)) {
 343     log_write(0, LOG_MAIN|LOG_PANIC,
 344          "spam acl condition: error reading from spamd socket: %s", strerror(errno));
 345     (void)close(spamd_sock);
 346     return DEFER;
 347   }
 348
 349   /* reading done */
 350   (void)close(spamd_sock);
 351
 352   /* dig in the spamd output and put the report in a multiline header, if requested */
 353   if( sscanf(CS spamd_buffer,"SPAMD/%7s 0 EX_OK\r\nContent-length: %*u\r\n\r\n%lf/%lf\r\n%n",
 354              spamd_version,&spamd_score,&spamd_threshold,&spamd_report_offset) != 3 ) {
 355
 356     /* try to fall back to pre-2.50 spamd output */
 357     if( sscanf(CS spamd_buffer,"SPAMD/%7s 0 EX_OK\r\nSpam: %*s ; %lf / %lf\r\n\r\n%n",
 358                spamd_version,&spamd_score,&spamd_threshold,&spamd_report_offset) != 3 ) {
 359       log_write(0, LOG_MAIN|LOG_PANIC,
 360          "spam acl condition: cannot parse spamd output");
 361       return DEFER;
 362     };
 363   };
 364
 365   /* Create report. Since this is a multiline string,
 366   we must hack it into shape first */
 367   p = &spamd_buffer[spamd_report_offset];
 368   q = spam_report_buffer;
 369   while (*p != '\0') {
 370     /* skip \r */
 371     if (*p == '\r') {
 372       p++;
 373       continue;
 374     };
 375     *q = *p;
 376     q++;
 377     if (*p == '\n') {
 378       /* add an extra space after the newline to ensure
 379       that it is treated as a header continuation line */
 380       *q = ' ';
 381       q++;
 382     };
 383     p++;
 384   };
 385   /* NULL-terminate */
 386   *q = '\0';
 387   q--;
 388   /* cut off trailing leftovers */
 389   while (*q <= ' ') {
 390     *q = '\0';
 391     q--;
 392   };
 393   spam_report = spam_report_buffer;
 394
 395   /* create spam bar */
 396   spamd_score_char = spamd_score > 0 ? '+' : '-';
 397   j = abs((int)(spamd_score));
 398   i = 0;
 399   if( j != 0 ) {
 400     while((i < j) && (i <= MAX_SPAM_BAR_CHARS))
 401        spam_bar_buffer[i++] = spamd_score_char;
 402   }
 403   else{
 404     spam_bar_buffer[0] = '/';
 405     i = 1;
 406   }
 407   spam_bar_buffer[i] = '\0';
 408   spam_bar = spam_bar_buffer;
 409
 410   /* create "float" spam score */
 411   (void)string_format(spam_score_buffer, sizeof(spam_score_buffer),"%.1f", spamd_score);
 412   spam_score = spam_score_buffer;
 413
 414   /* create "int" spam score */
 415   j = (int)((spamd_score + 0.001)*10);
 416   (void)string_format(spam_score_int_buffer, sizeof(spam_score_int_buffer), "%d", j);
 417   spam_score_int = spam_score_int_buffer;
 418
 419   /* compare threshold against score */
 420   if (spamd_score >= spamd_threshold) {
 421     /* spam as determined by user's threshold */
 422     spam_rc = OK;
 423   }
 424   else {
 425     /* not spam */
 426     spam_rc = FAIL;
 427   };
 428
 429   /* remember expanded spamd_address if needed */
 430   if (spamd_address_work != spamd_address) {
 431     prev_spamd_address_work = string_copy(spamd_address_work);
 432   }
 433   /* remember user name and "been here" for it */
 434   Ustrcpy(prev_user_name, user_name);
 435   spam_ok = 1;
 436
 437   if (override) {
 438     /* always return OK, no matter what the score */
 439     return OK;
 440   }
 441   else {
 442     return spam_rc;
 443   };
 444 }
 445
 446 #endif