src/src/spam.c

   1 /* $Cambridge: exim/src/src/spam.c,v 1.17 2008/07/18 17:55:42 fanf2 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
  24 int spam(uschar **listptr) {
  25   int sep = 0;
  26   uschar *list = *listptr;
  27   uschar *user_name;
  28   uschar user_name_buffer[128];
  29   unsigned long mbox_size;
  30   FILE *mbox_file;
  31   int spamd_sock;
  32   uschar spamd_buffer[32600];
  33   int i, j, offset, result;
  34   uschar spamd_version[8];
  35   uschar spamd_score_char;
  36   double spamd_threshold, spamd_score;
  37   int spamd_report_offset;
  38   uschar *p,*q;
  39   int override = 0;
  40   time_t start;
  41   size_t read, wrote;
  42   struct sockaddr_un server;
  43 #ifndef NO_POLL_H
  44   struct pollfd pollfd;
  45 #else                               /* Patch posted by Erik ? for OS X */
  46   struct timeval select_tv;         /* and applied by PH */
  47   fd_set select_fd;
  48 #endif
  49   uschar *spamd_address_work;
  50
  51   /* stop compiler warning */
  52   result = 0;
  53
  54   /* find the username from the option list */
  55   if ((user_name = string_nextinlist(&list, &sep,
  56                                      user_name_buffer,
  57                                      sizeof(user_name_buffer))) == NULL) {
  58     /* no username given, this means no scanning should be done */
  59     return FAIL;
  60   };
  61
  62   /* if username is "0" or "false", do not scan */
  63   if ( (Ustrcmp(user_name,"0") == 0) ||
  64        (strcmpic(user_name,US"false") == 0) ) {
  65     return FAIL;
  66   };
  67
  68   /* if there is an additional option, check if it is "true" */
  69   if (strcmpic(list,US"true") == 0) {
  70     /* in that case, always return true later */
  71     override = 1;
  72   };
  73
  74   /* if we scanned for this username last time, just return */
  75   if ( spam_ok && ( Ustrcmp(prev_user_name, user_name) == 0 ) ) {
  76     if (override)
  77       return OK;
  78     else
  79       return spam_rc;
  80   };
  81
  82   /* make sure the eml mbox file is spooled up */
  83   mbox_file = spool_mbox(&mbox_size);
  84
  85   if (mbox_file == NULL) {
  86     /* error while spooling */
  87     log_write(0, LOG_MAIN|LOG_PANIC,
  88            "spam acl condition: error while creating mbox spool file");
  89     return DEFER;
  90   };
  91
  92   start = time(NULL);
  93
  94   if (*spamd_address == '$') {
  95     spamd_address_work = expand_string(spamd_address);
  96     if (spamd_address_work == NULL) {
  97       log_write(0, LOG_MAIN|LOG_PANIC,
  98         "spamassassin acl condition: spamd_address starts with $, but expansion failed: %s", expand_string_message);
  99       return DEFER;
 100     }
 101   }
 102   else
 103     spamd_address_work = spamd_address;
 104
 105   /* socket does not start with '/' -> network socket */
 106   if (*spamd_address_work != '/') {
 107     time_t now = time(NULL);
 108     int num_servers = 0;
 109     int current_server = 0;
 110     int start_server = 0;
 111     uschar *address = NULL;
 112     uschar *spamd_address_list_ptr = spamd_address_work;
 113     uschar address_buffer[256];
 114     spamd_address_container * spamd_address_vector[32];
 115
 116     /* Check how many spamd servers we have
 117        and register their addresses */
 118     while ((address = string_nextinlist(&spamd_address_list_ptr, &sep,
 119                                         address_buffer,
 120                                         sizeof(address_buffer))) != NULL) {
 121
 122       spamd_address_container *this_spamd =
 123         (spamd_address_container *)store_get(sizeof(spamd_address_container));
 124
 125       /* grok spamd address and port */
 126       if( sscanf(CS address, "%s %u", this_spamd->tcp_addr, &(this_spamd->tcp_port)) != 2 ) {
 127         log_write(0, LOG_MAIN,
 128           "spam acl condition: warning - invalid spamd address: '%s'", address);
 129         continue;
 130       };
 131
 132       spamd_address_vector[num_servers] = this_spamd;
 133       num_servers++;
 134       if (num_servers > 31)
 135         break;
 136     };
 137
 138     /* check if we have at least one server */
 139     if (!num_servers) {
 140       log_write(0, LOG_MAIN|LOG_PANIC,
 141          "spam acl condition: no useable spamd server addresses in spamd_address configuration option.");
 142       (void)fclose(mbox_file);
 143       return DEFER;
 144     };
 145
 146     current_server = start_server = (int)now % num_servers;
 147
 148     while (1) {
 149
 150       debug_printf("trying server %s, port %u\n",
 151                    spamd_address_vector[current_server]->tcp_addr,
 152                    spamd_address_vector[current_server]->tcp_port);
 153
 154       /* contact a spamd */
 155       if ( (spamd_sock = ip_socket(SOCK_STREAM, AF_INET)) < 0) {
 156         log_write(0, LOG_MAIN|LOG_PANIC,
 157            "spam acl condition: error creating IP socket for spamd");
 158         (void)fclose(mbox_file);
 159         return DEFER;
 160       };
 161
 162       if (ip_connect( spamd_sock,
 163                       AF_INET,
 164                       spamd_address_vector[current_server]->tcp_addr,
 165                       spamd_address_vector[current_server]->tcp_port,
 166                       5 ) > -1) {
 167         /* connection OK */
 168         break;
 169       };
 170
 171       log_write(0, LOG_MAIN|LOG_PANIC,
 172          "spam acl condition: warning - spamd connection to %s, port %u failed: %s",
 173          spamd_address_vector[current_server]->tcp_addr,
 174          spamd_address_vector[current_server]->tcp_port,
 175          strerror(errno));
 176       current_server++;
 177       if (current_server >= num_servers)
 178         current_server = 0;
 179       if (current_server == start_server) {
 180         log_write(0, LOG_MAIN|LOG_PANIC, "spam acl condition: all spamd servers failed");
 181         (void)fclose(mbox_file);
 182         (void)close(spamd_sock);
 183         return DEFER;
 184       };
 185     };
 186
 187   }
 188   else {
 189     /* open the local socket */
 190
 191     if ((spamd_sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
 192       log_write(0, LOG_MAIN|LOG_PANIC,
 193                 "malware acl condition: spamd: unable to acquire socket (%s)",
 194                 strerror(errno));
 195       (void)fclose(mbox_file);
 196       return DEFER;
 197     }
 198
 199     server.sun_family = AF_UNIX;
 200     Ustrcpy(server.sun_path, spamd_address_work);
 201
 202     if (connect(spamd_sock, (struct sockaddr *) &server, sizeof(struct sockaddr_un)) < 0) {
 203       log_write(0, LOG_MAIN|LOG_PANIC,
 204                 "malware acl condition: spamd: unable to connect to UNIX socket %s (%s)",
 205                 spamd_address_work, strerror(errno) );
 206       (void)fclose(mbox_file);
 207       (void)close(spamd_sock);
 208       return DEFER;
 209     }
 210
 211   }
 212
 213   /* now we are connected to spamd on spamd_sock */
 214   (void)string_format(spamd_buffer,
 215            sizeof(spamd_buffer),
 216            "REPORT SPAMC/1.2\r\nUser: %s\r\nContent-length: %ld\r\n\r\n",
 217            user_name,
 218            mbox_size);
 219
 220   /* send our request */
 221   if (send(spamd_sock, spamd_buffer, Ustrlen(spamd_buffer), 0) < 0) {
 222     (void)close(spamd_sock);
 223     log_write(0, LOG_MAIN|LOG_PANIC,
 224          "spam acl condition: spamd send failed: %s", strerror(errno));
 225     (void)fclose(mbox_file);
 226     (void)close(spamd_sock);
 227     return DEFER;
 228   };
 229
 230   /* now send the file */
 231   /* spamd sometimes accepts conections but doesn't read data off
 232    * the connection.  We make the file descriptor non-blocking so
 233    * that the write will only write sufficient data without blocking
 234    * and we poll the desciptor to make sure that we can write without
 235    * blocking.  Short writes are gracefully handled and if the whole
 236    * trasaction takes too long it is aborted.
 237    * Note: poll() is not supported in OSX 10.2 and is reported to be
 238    *       broken in more recent versions (up to 10.4).
 239    */
 240 #ifndef NO_POLL_H
 241   pollfd.fd = spamd_sock;
 242   pollfd.events = POLLOUT;
 243 #endif
 244   (void)fcntl(spamd_sock, F_SETFL, O_NONBLOCK);
 245   do {
 246     read = fread(spamd_buffer,1,sizeof(spamd_buffer),mbox_file);
 247     if (read > 0) {
 248       offset = 0;
 249 again:
 250 #ifndef NO_POLL_H
 251       result = poll(&pollfd, 1, 1000);
 252
 253 /* Patch posted by Erik ? for OS X and applied by PH */
 254 #else
 255       select_tv.tv_sec = 1;
 256       select_tv.tv_usec = 0;
 257       FD_ZERO(&select_fd);
 258       FD_SET(spamd_sock, &select_fd);
 259       result = select(spamd_sock+1, NULL, &select_fd, NULL, &select_tv);
 260 #endif
 261 /* End Erik's patch */
 262
 263       if (result == -1 && errno == EINTR)
 264         goto again;
 265       else if (result < 1) {
 266         if (result == -1)
 267           log_write(0, LOG_MAIN|LOG_PANIC,
 268             "spam acl condition: %s on spamd socket", strerror(errno));
 269         else {
 270           if (time(NULL) - start < SPAMD_TIMEOUT)
 271           goto again;
 272           log_write(0, LOG_MAIN|LOG_PANIC,
 273             "spam acl condition: timed out writing spamd socket");
 274         }
 275         (void)close(spamd_sock);
 276         (void)fclose(mbox_file);
 277         return DEFER;
 278       }
 279
 280       wrote = send(spamd_sock,spamd_buffer + offset,read - offset,0);
 281       if (wrote == -1)
 282       {
 283           log_write(0, LOG_MAIN|LOG_PANIC,
 284             "spam acl condition: %s on spamd socket", strerror(errno));
 285         (void)close(spamd_sock);
 286         (void)fclose(mbox_file);
 287         return DEFER;
 288       }
 289       if (offset + wrote != read) {
 290         offset += wrote;
 291         goto again;
 292       }
 293     }
 294   }
 295   while (!feof(mbox_file) && !ferror(mbox_file));
 296   if (ferror(mbox_file)) {
 297     log_write(0, LOG_MAIN|LOG_PANIC,
 298       "spam acl condition: error reading spool file: %s", strerror(errno));
 299     (void)close(spamd_sock);
 300     (void)fclose(mbox_file);
 301     return DEFER;
 302   }
 303
 304   (void)fclose(mbox_file);
 305
 306   /* we're done sending, close socket for writing */
 307   shutdown(spamd_sock,SHUT_WR);
 308
 309   /* read spamd response using what's left of the timeout.
 310    */
 311   memset(spamd_buffer, 0, sizeof(spamd_buffer));
 312   offset = 0;
 313   while((i = ip_recv(spamd_sock,
 314                      spamd_buffer + offset,
 315                      sizeof(spamd_buffer) - offset - 1,
 316                      SPAMD_TIMEOUT - time(NULL) + start)) > 0 ) {
 317     offset += i;
 318   }
 319
 320   /* error handling */
 321   if((i <= 0) && (errno != 0)) {
 322     log_write(0, LOG_MAIN|LOG_PANIC,
 323          "spam acl condition: error reading from spamd socket: %s", strerror(errno));
 324     (void)close(spamd_sock);
 325     return DEFER;
 326   }
 327
 328   /* reading done */
 329   (void)close(spamd_sock);
 330
 331   /* dig in the spamd output and put the report in a multiline header, if requested */
 332   if( sscanf(CS spamd_buffer,"SPAMD/%7s 0 EX_OK\r\nContent-length: %*u\r\n\r\n%lf/%lf\r\n%n",
 333              spamd_version,&spamd_score,&spamd_threshold,&spamd_report_offset) != 3 ) {
 334
 335     /* try to fall back to pre-2.50 spamd output */
 336     if( sscanf(CS spamd_buffer,"SPAMD/%7s 0 EX_OK\r\nSpam: %*s ; %lf / %lf\r\n\r\n%n",
 337                spamd_version,&spamd_score,&spamd_threshold,&spamd_report_offset) != 3 ) {
 338       log_write(0, LOG_MAIN|LOG_PANIC,
 339          "spam acl condition: cannot parse spamd output");
 340       return DEFER;
 341     };
 342   };
 343
 344   /* Create report. Since this is a multiline string,
 345   we must hack it into shape first */
 346   p = &spamd_buffer[spamd_report_offset];
 347   q = spam_report_buffer;
 348   while (*p != '\0') {
 349     /* skip \r */
 350     if (*p == '\r') {
 351       p++;
 352       continue;
 353     };
 354     *q = *p;
 355     q++;
 356     if (*p == '\n') {
 357       /* add an extra space after the newline to ensure
 358       that it is treated as a header continuation line */
 359       *q = ' ';
 360       q++;
 361     };
 362     p++;
 363   };
 364   /* NULL-terminate */
 365   *q = '\0';
 366   q--;
 367   /* cut off trailing leftovers */
 368   while (*q <= ' ') {
 369     *q = '\0';
 370     q--;
 371   };
 372   spam_report = spam_report_buffer;
 373
 374   /* create spam bar */
 375   spamd_score_char = spamd_score > 0 ? '+' : '-';
 376   j = abs((int)(spamd_score));
 377   i = 0;
 378   if( j != 0 ) {
 379     while((i < j) && (i <= MAX_SPAM_BAR_CHARS))
 380        spam_bar_buffer[i++] = spamd_score_char;
 381   }
 382   else{
 383     spam_bar_buffer[0] = '/';
 384     i = 1;
 385   }
 386   spam_bar_buffer[i] = '\0';
 387   spam_bar = spam_bar_buffer;
 388
 389   /* create "float" spam score */
 390   (void)string_format(spam_score_buffer, sizeof(spam_score_buffer),"%.1f", spamd_score);
 391   spam_score = spam_score_buffer;
 392
 393   /* create "int" spam score */
 394   j = (int)((spamd_score + 0.001)*10);
 395   (void)string_format(spam_score_int_buffer, sizeof(spam_score_int_buffer), "%d", j);
 396   spam_score_int = spam_score_int_buffer;
 397
 398   /* compare threshold against score */
 399   if (spamd_score >= spamd_threshold) {
 400     /* spam as determined by user's threshold */
 401     spam_rc = OK;
 402   }
 403   else {
 404     /* not spam */
 405     spam_rc = FAIL;
 406   };
 407
 408   /* remember user name and "been here" for it unless spamd_socket was expanded */
 409   if (spamd_address_work == spamd_address) {
 410     Ustrcpy(prev_user_name, user_name);
 411     spam_ok = 1;
 412   }
 413
 414   if (override) {
 415     /* always return OK, no matter what the score */
 416     return OK;
 417   }
 418   else {
 419     return spam_rc;
 420   };
 421 }
 422
 423 #endif