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, "%s %u", this_spamd->tcp_addr, &(this_spamd->tcp_port)) != 2 ) {
 133         log_write(0, LOG_MAIN,
 134           "spam acl condition: warning - invalid spamd address: '%s'", address);
 135         continue;
 136       };
 137
 138       spamd_address_vector[num_servers] = this_spamd;
 139       num_servers++;
 140       if (num_servers > 31)
 141         break;
 142     };
 143
 144     /* check if we have at least one server */
 145     if (!num_servers) {
 146       log_write(0, LOG_MAIN|LOG_PANIC,
 147          "spam acl condition: no useable spamd server addresses in spamd_address configuration option.");
 148       (void)fclose(mbox_file);
 149       return DEFER;
 150     };
 151
 152     while ( num_servers > 0 ) {
 153       int i;
 154
 155       /* Randomly pick a server to try */
 156       current_server = random_number( num_servers );
 157
 158       debug_printf("trying server %s, port %u\n",
 159                    spamd_address_vector[current_server]->tcp_addr,
 160                    spamd_address_vector[current_server]->tcp_port);
 161
 162       /* contact a spamd */
 163       if ( (spamd_sock = ip_socket(SOCK_STREAM, AF_INET)) < 0) {
 164         log_write(0, LOG_MAIN|LOG_PANIC,
 165            "spam acl condition: error creating IP socket for spamd");
 166         (void)fclose(mbox_file);
 167         return DEFER;
 168       };
 169
 170       if (ip_connect( spamd_sock,
 171                       AF_INET,
 172                       spamd_address_vector[current_server]->tcp_addr,
 173                       spamd_address_vector[current_server]->tcp_port,
 174                       5 ) > -1) {
 175         /* connection OK */
 176         break;
 177       };
 178
 179       log_write(0, LOG_MAIN|LOG_PANIC,
 180          "spam acl condition: warning - spamd connection to %s, port %u failed: %s",
 181          spamd_address_vector[current_server]->tcp_addr,
 182          spamd_address_vector[current_server]->tcp_port,
 183          strerror(errno));
 184
 185       (void)close(spamd_sock);
 186
 187       /* Remove the server from the list. XXX We should free the memory */
 188       num_servers--;
 189       for( i = current_server; i < num_servers; i++ )
 190         spamd_address_vector[i] = spamd_address_vector[i+1];
 191     }
 192
 193     if ( num_servers == 0 ) {
 194       log_write(0, LOG_MAIN|LOG_PANIC, "spam acl condition: all spamd servers failed");
 195       (void)fclose(mbox_file);
 196       return DEFER;
 197     }
 198
 199   }
 200   else {
 201     /* open the local socket */
 202
 203     if ((spamd_sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
 204       log_write(0, LOG_MAIN|LOG_PANIC,
 205                 "malware acl condition: spamd: unable to acquire socket (%s)",
 206                 strerror(errno));
 207       (void)fclose(mbox_file);
 208       return DEFER;
 209     }
 210
 211     server.sun_family = AF_UNIX;
 212     Ustrcpy(server.sun_path, spamd_address_work);
 213
 214     if (connect(spamd_sock, (struct sockaddr *) &server, sizeof(struct sockaddr_un)) < 0) {
 215       log_write(0, LOG_MAIN|LOG_PANIC,
 216                 "malware acl condition: spamd: unable to connect to UNIX socket %s (%s)",
 217                 spamd_address_work, strerror(errno) );
 218       (void)fclose(mbox_file);
 219       (void)close(spamd_sock);
 220       return DEFER;
 221     }
 222
 223   }
 224
 225   if (spamd_sock == -1) {
 226     log_write(0, LOG_MAIN|LOG_PANIC,
 227         "programming fault, spamd_sock unexpectedly unset");
 228     (void)fclose(mbox_file);
 229     (void)close(spamd_sock);
 230     return DEFER;
 231   }
 232
 233   /* now we are connected to spamd on spamd_sock */
 234   (void)string_format(spamd_buffer,
 235            sizeof(spamd_buffer),
 236            "REPORT SPAMC/1.2\r\nUser: %s\r\nContent-length: %ld\r\n\r\n",
 237            user_name,
 238            mbox_size);
 239
 240   /* send our request */
 241   if (send(spamd_sock, spamd_buffer, Ustrlen(spamd_buffer), 0) < 0) {
 242     (void)close(spamd_sock);
 243     log_write(0, LOG_MAIN|LOG_PANIC,
 244          "spam acl condition: spamd send failed: %s", strerror(errno));
 245     (void)fclose(mbox_file);
 246     (void)close(spamd_sock);
 247     return DEFER;
 248   };
 249
 250   /* now send the file */
 251   /* spamd sometimes accepts conections but doesn't read data off
 252    * the connection.  We make the file descriptor non-blocking so
 253    * that the write will only write sufficient data without blocking
 254    * and we poll the desciptor to make sure that we can write without
 255    * blocking.  Short writes are gracefully handled and if the whole
 256    * trasaction takes too long it is aborted.
 257    * Note: poll() is not supported in OSX 10.2 and is reported to be
 258    *       broken in more recent versions (up to 10.4).
 259    */
 260 #ifndef NO_POLL_H
 261   pollfd.fd = spamd_sock;
 262   pollfd.events = POLLOUT;
 263 #endif
 264   (void)fcntl(spamd_sock, F_SETFL, O_NONBLOCK);
 265   do {
 266     read = fread(spamd_buffer,1,sizeof(spamd_buffer),mbox_file);
 267     if (read > 0) {
 268       offset = 0;
 269 again:
 270 #ifndef NO_POLL_H
 271       result = poll(&pollfd, 1, 1000);
 272
 273 /* Patch posted by Erik ? for OS X and applied by PH */
 274 #else
 275       select_tv.tv_sec = 1;
 276       select_tv.tv_usec = 0;
 277       FD_ZERO(&select_fd);
 278       FD_SET(spamd_sock, &select_fd);
 279       result = select(spamd_sock+1, NULL, &select_fd, NULL, &select_tv);
 280 #endif
 281 /* End Erik's patch */
 282
 283       if (result == -1 && errno == EINTR)
 284         goto again;
 285       else if (result < 1) {
 286         if (result == -1)
 287           log_write(0, LOG_MAIN|LOG_PANIC,
 288             "spam acl condition: %s on spamd socket", strerror(errno));
 289         else {
 290           if (time(NULL) - start < SPAMD_TIMEOUT)
 291             goto again;
 292           log_write(0, LOG_MAIN|LOG_PANIC,
 293             "spam acl condition: timed out writing spamd socket");
 294         }
 295         (void)close(spamd_sock);
 296         (void)fclose(mbox_file);
 297         return DEFER;
 298       }
 299
 300       wrote = send(spamd_sock,spamd_buffer + offset,read - offset,0);
 301       if (wrote == -1)
 302       {
 303           log_write(0, LOG_MAIN|LOG_PANIC,
 304             "spam acl condition: %s on spamd socket", strerror(errno));
 305         (void)close(spamd_sock);
 306         (void)fclose(mbox_file);
 307         return DEFER;
 308       }
 309       if (offset + wrote != read) {
 310         offset += wrote;
 311         goto again;
 312       }
 313     }
 314   }
 315   while (!feof(mbox_file) && !ferror(mbox_file));
 316   if (ferror(mbox_file)) {
 317     log_write(0, LOG_MAIN|LOG_PANIC,
 318       "spam acl condition: error reading spool file: %s", strerror(errno));
 319     (void)close(spamd_sock);
 320     (void)fclose(mbox_file);
 321     return DEFER;
 322   }
 323
 324   (void)fclose(mbox_file);
 325
 326   /* we're done sending, close socket for writing */
 327   shutdown(spamd_sock,SHUT_WR);
 328
 329   /* read spamd response using what's left of the timeout.
 330    */
 331   memset(spamd_buffer, 0, sizeof(spamd_buffer));
 332   offset = 0;
 333   while((i = ip_recv(spamd_sock,
 334                      spamd_buffer + offset,
 335                      sizeof(spamd_buffer) - offset - 1,
 336                      SPAMD_TIMEOUT - time(NULL) + start)) > 0 ) {
 337     offset += i;
 338   }
 339
 340   /* error handling */
 341   if((i <= 0) && (errno != 0)) {
 342     log_write(0, LOG_MAIN|LOG_PANIC,
 343          "spam acl condition: error reading from spamd socket: %s", strerror(errno));
 344     (void)close(spamd_sock);
 345     return DEFER;
 346   }
 347
 348   /* reading done */
 349   (void)close(spamd_sock);
 350
 351   /* dig in the spamd output and put the report in a multiline header, if requested */
 352   if( sscanf(CS spamd_buffer,"SPAMD/%7s 0 EX_OK\r\nContent-length: %*u\r\n\r\n%lf/%lf\r\n%n",
 353              spamd_version,&spamd_score,&spamd_threshold,&spamd_report_offset) != 3 ) {
 354
 355     /* try to fall back to pre-2.50 spamd output */
 356     if( sscanf(CS spamd_buffer,"SPAMD/%7s 0 EX_OK\r\nSpam: %*s ; %lf / %lf\r\n\r\n%n",
 357                spamd_version,&spamd_score,&spamd_threshold,&spamd_report_offset) != 3 ) {
 358       log_write(0, LOG_MAIN|LOG_PANIC,
 359          "spam acl condition: cannot parse spamd output");
 360       return DEFER;
 361     };
 362   };
 363
 364   /* Create report. Since this is a multiline string,
 365   we must hack it into shape first */
 366   p = &spamd_buffer[spamd_report_offset];
 367   q = spam_report_buffer;
 368   while (*p != '\0') {
 369     /* skip \r */
 370     if (*p == '\r') {
 371       p++;
 372       continue;
 373     };
 374     *q = *p;
 375     q++;
 376     if (*p == '\n') {
 377       /* add an extra space after the newline to ensure
 378       that it is treated as a header continuation line */
 379       *q = ' ';
 380       q++;
 381     };
 382     p++;
 383   };
 384   /* NULL-terminate */
 385   *q = '\0';
 386   q--;
 387   /* cut off trailing leftovers */
 388   while (*q <= ' ') {
 389     *q = '\0';
 390     q--;
 391   };
 392   spam_report = spam_report_buffer;
 393
 394   /* create spam bar */
 395   spamd_score_char = spamd_score > 0 ? '+' : '-';
 396   j = abs((int)(spamd_score));
 397   i = 0;
 398   if( j != 0 ) {
 399     while((i < j) && (i <= MAX_SPAM_BAR_CHARS))
 400        spam_bar_buffer[i++] = spamd_score_char;
 401   }
 402   else{
 403     spam_bar_buffer[0] = '/';
 404     i = 1;
 405   }
 406   spam_bar_buffer[i] = '\0';
 407   spam_bar = spam_bar_buffer;
 408
 409   /* create "float" spam score */
 410   (void)string_format(spam_score_buffer, sizeof(spam_score_buffer),"%.1f", spamd_score);
 411   spam_score = spam_score_buffer;
 412
 413   /* create "int" spam score */
 414   j = (int)((spamd_score + 0.001)*10);
 415   (void)string_format(spam_score_int_buffer, sizeof(spam_score_int_buffer), "%d", j);
 416   spam_score_int = spam_score_int_buffer;
 417
 418   /* compare threshold against score */
 419   if (spamd_score >= spamd_threshold) {
 420     /* spam as determined by user's threshold */
 421     spam_rc = OK;
 422   }
 423   else {
 424     /* not spam */
 425     spam_rc = FAIL;
 426   };
 427
 428   /* remember expanded spamd_address if needed */
 429   if (spamd_address_work != spamd_address) {
 430     prev_spamd_address_work = string_copy(spamd_address_work);
 431   }
 432   /* remember user name and "been here" for it */
 433   Ustrcpy(prev_user_name, user_name);
 434   spam_ok = 1;
 435
 436   if (override) {
 437     /* always return OK, no matter what the score */
 438     return OK;
 439   }
 440   else {
 441     return spam_rc;
 442   };
 443 }
 444
 445 #endif