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