src/src/spam.c

   1 /* $Cambridge: exim/src/src/spam.c,v 1.18 2010/06/05 11:13:30 pdp Exp $ */
   2
   3 /*************************************************
   4 *     Exim - an Internet mail transport agent    *
   5 *************************************************/
   6
   7 /* Copyright (c) Tom Kistner <tom@duncanthrax.net> 2003-???? */
   8 /* License: GPL */
   9
  10 /* Code for calling spamassassin's spamd. Called from acl.c. */
  11
  12 #include "exim.h"
  13 #ifdef WITH_CONTENT_SCAN
  14 #include "spam.h"
  15
  16 uschar spam_score_buffer[16];
  17 uschar spam_score_int_buffer[16];
  18 uschar spam_bar_buffer[128];
  19 uschar spam_report_buffer[32600];
  20 uschar prev_user_name[128] = "";
  21 int spam_ok = 0;
  22 int spam_rc = 0;
  23 uschar *prev_spamd_address_work = NULL;
  24
  25 int spam(uschar **listptr) {
  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;
  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     time_t now = time(NULL);
 115     int num_servers = 0;
 116     int current_server = 0;
 117     int start_server = 0;
 118     uschar *address = NULL;
 119     uschar *spamd_address_list_ptr = spamd_address_work;
 120     uschar address_buffer[256];
 121     spamd_address_container * spamd_address_vector[32];
 122
 123     /* Check how many spamd servers we have
 124        and register their addresses */
 125     while ((address = string_nextinlist(&spamd_address_list_ptr, &sep,
 126                                         address_buffer,
 127                                         sizeof(address_buffer))) != NULL) {
 128
 129       spamd_address_container *this_spamd =
 130         (spamd_address_container *)store_get(sizeof(spamd_address_container));
 131
 132       /* grok spamd address and port */
 133       if( sscanf(CS address, "%s %u", this_spamd->tcp_addr, &(this_spamd->tcp_port)) != 2 ) {
 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     current_server = start_server = (int)now % num_servers;
 154
 155     while (1) {
 156
 157       debug_printf("trying server %s, port %u\n",
 158                    spamd_address_vector[current_server]->tcp_addr,
 159                    spamd_address_vector[current_server]->tcp_port);
 160
 161       /* contact a spamd */
 162       if ( (spamd_sock = ip_socket(SOCK_STREAM, AF_INET)) < 0) {
 163         log_write(0, LOG_MAIN|LOG_PANIC,
 164            "spam acl condition: error creating IP socket for spamd");
 165         (void)fclose(mbox_file);
 166         return DEFER;
 167       };
 168
 169       if (ip_connect( spamd_sock,
 170                       AF_INET,
 171                       spamd_address_vector[current_server]->tcp_addr,
 172                       spamd_address_vector[current_server]->tcp_port,
 173                       5 ) > -1) {
 174         /* connection OK */
 175         break;
 176       };
 177
 178       log_write(0, LOG_MAIN|LOG_PANIC,
 179          "spam acl condition: warning - spamd connection to %s, port %u failed: %s",
 180          spamd_address_vector[current_server]->tcp_addr,
 181          spamd_address_vector[current_server]->tcp_port,
 182          strerror(errno));
 183       current_server++;
 184       if (current_server >= num_servers)
 185         current_server = 0;
 186       if (current_server == start_server) {
 187         log_write(0, LOG_MAIN|LOG_PANIC, "spam acl condition: all spamd servers failed");
 188         (void)fclose(mbox_file);
 189         (void)close(spamd_sock);
 190         return DEFER;
 191       };
 192     };
 193
 194   }
 195   else {
 196     /* open the local socket */
 197
 198     if ((spamd_sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
 199       log_write(0, LOG_MAIN|LOG_PANIC,
 200                 "malware acl condition: spamd: unable to acquire socket (%s)",
 201                 strerror(errno));
 202       (void)fclose(mbox_file);
 203       return DEFER;
 204     }
 205
 206     server.sun_family = AF_UNIX;
 207     Ustrcpy(server.sun_path, spamd_address_work);
 208
 209     if (connect(spamd_sock, (struct sockaddr *) &server, sizeof(struct sockaddr_un)) < 0) {
 210       log_write(0, LOG_MAIN|LOG_PANIC,
 211                 "malware acl condition: spamd: unable to connect to UNIX socket %s (%s)",
 212                 spamd_address_work, strerror(errno) );
 213       (void)fclose(mbox_file);
 214       (void)close(spamd_sock);
 215       return DEFER;
 216     }
 217
 218   }
 219
 220   /* now we are connected to spamd on spamd_sock */
 221   (void)string_format(spamd_buffer,
 222            sizeof(spamd_buffer),
 223            "REPORT SPAMC/1.2\r\nUser: %s\r\nContent-length: %ld\r\n\r\n",
 224            user_name,
 225            mbox_size);
 226
 227   /* send our request */
 228   if (send(spamd_sock, spamd_buffer, Ustrlen(spamd_buffer), 0) < 0) {
 229     (void)close(spamd_sock);
 230     log_write(0, LOG_MAIN|LOG_PANIC,
 231          "spam acl condition: spamd send failed: %s", strerror(errno));
 232     (void)fclose(mbox_file);
 233     (void)close(spamd_sock);
 234     return DEFER;
 235   };
 236
 237   /* now send the file */
 238   /* spamd sometimes accepts conections but doesn't read data off
 239    * the connection.  We make the file descriptor non-blocking so
 240    * that the write will only write sufficient data without blocking
 241    * and we poll the desciptor to make sure that we can write without
 242    * blocking.  Short writes are gracefully handled and if the whole
 243    * trasaction takes too long it is aborted.
 244    * Note: poll() is not supported in OSX 10.2 and is reported to be
 245    *       broken in more recent versions (up to 10.4).
 246    */
 247 #ifndef NO_POLL_H
 248   pollfd.fd = spamd_sock;
 249   pollfd.events = POLLOUT;
 250 #endif
 251   (void)fcntl(spamd_sock, F_SETFL, O_NONBLOCK);
 252   do {
 253     read = fread(spamd_buffer,1,sizeof(spamd_buffer),mbox_file);
 254     if (read > 0) {
 255       offset = 0;
 256 again:
 257 #ifndef NO_POLL_H
 258       result = poll(&pollfd, 1, 1000);
 259
 260 /* Patch posted by Erik ? for OS X and applied by PH */
 261 #else
 262       select_tv.tv_sec = 1;
 263       select_tv.tv_usec = 0;
 264       FD_ZERO(&select_fd);
 265       FD_SET(spamd_sock, &select_fd);
 266       result = select(spamd_sock+1, NULL, &select_fd, NULL, &select_tv);
 267 #endif
 268 /* End Erik's patch */
 269
 270       if (result == -1 && errno == EINTR)
 271         goto again;
 272       else if (result < 1) {
 273         if (result == -1)
 274           log_write(0, LOG_MAIN|LOG_PANIC,
 275             "spam acl condition: %s on spamd socket", strerror(errno));
 276         else {
 277           if (time(NULL) - start < SPAMD_TIMEOUT)
 278           goto again;
 279           log_write(0, LOG_MAIN|LOG_PANIC,
 280             "spam acl condition: timed out writing spamd socket");
 281         }
 282         (void)close(spamd_sock);
 283         (void)fclose(mbox_file);
 284         return DEFER;
 285       }
 286
 287       wrote = send(spamd_sock,spamd_buffer + offset,read - offset,0);
 288       if (wrote == -1)
 289       {
 290           log_write(0, LOG_MAIN|LOG_PANIC,
 291             "spam acl condition: %s on spamd socket", strerror(errno));
 292         (void)close(spamd_sock);
 293         (void)fclose(mbox_file);
 294         return DEFER;
 295       }
 296       if (offset + wrote != read) {
 297         offset += wrote;
 298         goto again;
 299       }
 300     }
 301   }
 302   while (!feof(mbox_file) && !ferror(mbox_file));
 303   if (ferror(mbox_file)) {
 304     log_write(0, LOG_MAIN|LOG_PANIC,
 305       "spam acl condition: error reading spool file: %s", strerror(errno));
 306     (void)close(spamd_sock);
 307     (void)fclose(mbox_file);
 308     return DEFER;
 309   }
 310
 311   (void)fclose(mbox_file);
 312
 313   /* we're done sending, close socket for writing */
 314   shutdown(spamd_sock,SHUT_WR);
 315
 316   /* read spamd response using what's left of the timeout.
 317    */
 318   memset(spamd_buffer, 0, sizeof(spamd_buffer));
 319   offset = 0;
 320   while((i = ip_recv(spamd_sock,
 321                      spamd_buffer + offset,
 322                      sizeof(spamd_buffer) - offset - 1,
 323                      SPAMD_TIMEOUT - time(NULL) + start)) > 0 ) {
 324     offset += i;
 325   }
 326
 327   /* error handling */
 328   if((i <= 0) && (errno != 0)) {
 329     log_write(0, LOG_MAIN|LOG_PANIC,
 330          "spam acl condition: error reading from spamd socket: %s", strerror(errno));
 331     (void)close(spamd_sock);
 332     return DEFER;
 333   }
 334
 335   /* reading done */
 336   (void)close(spamd_sock);
 337
 338   /* dig in the spamd output and put the report in a multiline header, if requested */
 339   if( sscanf(CS spamd_buffer,"SPAMD/%7s 0 EX_OK\r\nContent-length: %*u\r\n\r\n%lf/%lf\r\n%n",
 340              spamd_version,&spamd_score,&spamd_threshold,&spamd_report_offset) != 3 ) {
 341
 342     /* try to fall back to pre-2.50 spamd output */
 343     if( sscanf(CS spamd_buffer,"SPAMD/%7s 0 EX_OK\r\nSpam: %*s ; %lf / %lf\r\n\r\n%n",
 344                spamd_version,&spamd_score,&spamd_threshold,&spamd_report_offset) != 3 ) {
 345       log_write(0, LOG_MAIN|LOG_PANIC,
 346          "spam acl condition: cannot parse spamd output");
 347       return DEFER;
 348     };
 349   };
 350
 351   /* Create report. Since this is a multiline string,
 352   we must hack it into shape first */
 353   p = &spamd_buffer[spamd_report_offset];
 354   q = spam_report_buffer;
 355   while (*p != '\0') {
 356     /* skip \r */
 357     if (*p == '\r') {
 358       p++;
 359       continue;
 360     };
 361     *q = *p;
 362     q++;
 363     if (*p == '\n') {
 364       /* add an extra space after the newline to ensure
 365       that it is treated as a header continuation line */
 366       *q = ' ';
 367       q++;
 368     };
 369     p++;
 370   };
 371   /* NULL-terminate */
 372   *q = '\0';
 373   q--;
 374   /* cut off trailing leftovers */
 375   while (*q <= ' ') {
 376     *q = '\0';
 377     q--;
 378   };
 379   spam_report = spam_report_buffer;
 380
 381   /* create spam bar */
 382   spamd_score_char = spamd_score > 0 ? '+' : '-';
 383   j = abs((int)(spamd_score));
 384   i = 0;
 385   if( j != 0 ) {
 386     while((i < j) && (i <= MAX_SPAM_BAR_CHARS))
 387        spam_bar_buffer[i++] = spamd_score_char;
 388   }
 389   else{
 390     spam_bar_buffer[0] = '/';
 391     i = 1;
 392   }
 393   spam_bar_buffer[i] = '\0';
 394   spam_bar = spam_bar_buffer;
 395
 396   /* create "float" spam score */
 397   (void)string_format(spam_score_buffer, sizeof(spam_score_buffer),"%.1f", spamd_score);
 398   spam_score = spam_score_buffer;
 399
 400   /* create "int" spam score */
 401   j = (int)((spamd_score + 0.001)*10);
 402   (void)string_format(spam_score_int_buffer, sizeof(spam_score_int_buffer), "%d", j);
 403   spam_score_int = spam_score_int_buffer;
 404
 405   /* compare threshold against score */
 406   if (spamd_score >= spamd_threshold) {
 407     /* spam as determined by user's threshold */
 408     spam_rc = OK;
 409   }
 410   else {
 411     /* not spam */
 412     spam_rc = FAIL;
 413   };
 414
 415   /* remember expanded spamd_address if needed */
 416   if (spamd_address_work != spamd_address) {
 417     prev_spamd_address_work = string_copy(spamd_address_work);
 418   }
 419   /* remember user name and "been here" for it */
 420   Ustrcpy(prev_user_name, user_name);
 421   spam_ok = 1;
 422
 423   if (override) {
 424     /* always return OK, no matter what the score */
 425     return OK;
 426   }
 427   else {
 428     return spam_rc;
 429   };
 430 }
 431
 432 #endif