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     {
  60     /* no username given, this means no scanning should be done */
  61     return FAIL;
  62     }
  63
  64   /* if username is "0" or "false", do not scan */
  65   if ( (Ustrcmp(user_name,"0") == 0) ||
  66        (strcmpic(user_name,US"false") == 0) )
  67     return FAIL;
  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   /* expand spamd_address if needed */
  75   if (*spamd_address == '$')
  76     {
  77     spamd_address_work = expand_string(spamd_address);
  78     if (spamd_address_work == NULL)
  79       {
  80       log_write(0, LOG_MAIN|LOG_PANIC,
  81         "spamassassin acl condition: spamd_address starts with $, but expansion failed: %s", expand_string_message);
  82       return DEFER;
  83       }
  84     }
  85   else
  86     spamd_address_work = spamd_address;
  87
  88   /* check if previous spamd_address was expanded and has changed. dump cached results if so */
  89   if (  spam_ok
  90      && prev_spamd_address_work != NULL
  91      && Ustrcmp(prev_spamd_address_work, spamd_address_work) != 0
  92      )
  93     spam_ok = 0;
  94
  95   /* if we scanned for this username last time, just return */
  96   if ( spam_ok && Ustrcmp(prev_user_name, user_name) == 0)
  97     if (override)
  98       return OK;
  99     else
 100       return spam_rc;
 101
 102   /* make sure the eml mbox file is spooled up */
 103   mbox_file = spool_mbox(&mbox_size, NULL);
 104
 105   if (mbox_file == NULL)
 106     {
 107     /* error while spooling */
 108     log_write(0, LOG_MAIN|LOG_PANIC,
 109            "spam acl condition: error while creating mbox spool file");
 110     return DEFER;
 111     }
 112
 113   start = time(NULL);
 114
 115   /* socket does not start with '/' -> network socket */
 116   if (*spamd_address_work != '/')
 117     {
 118     int num_servers = 0;
 119     int current_server;
 120     uschar *address = NULL;
 121     uschar *spamd_address_list_ptr = spamd_address_work;
 122     uschar address_buffer[256];
 123     spamd_address_container * spamd_address_vector[32];
 124
 125     /* Check how many spamd servers we have
 126        and register their addresses */
 127     while ((address = string_nextinlist(&spamd_address_list_ptr, &sep,
 128                                         address_buffer,
 129                                         sizeof(address_buffer))) != NULL)
 130       {
 131
 132       /* Potential memory leak as we never free the store. */
 133       spamd_address_container *this_spamd =
 134         (spamd_address_container *)store_get(sizeof(spamd_address_container));
 135
 136       /* grok spamd address and port */
 137       if (sscanf(CS address, "%23s %u", this_spamd->tcp_addr, &(this_spamd->tcp_port)) != 2)
 138         {
 139         log_write(0, LOG_MAIN,
 140           "spam acl condition: warning - invalid spamd address: '%s'", address);
 141         continue;
 142         }
 143
 144       spamd_address_vector[num_servers] = this_spamd;
 145       if (++num_servers > 31)
 146         break;
 147       }
 148
 149     /* check if we have at least one server */
 150     if (!num_servers)
 151       {
 152       log_write(0, LOG_MAIN|LOG_PANIC,
 153          "spam acl condition: no useable spamd server addresses in spamd_address configuration option.");
 154       (void)fclose(mbox_file);
 155       return DEFER;
 156       }
 157
 158     while ( num_servers > 0 )
 159       {
 160       int i;
 161
 162       /* Randomly pick a server to try */
 163       current_server = random_number( num_servers );
 164
 165       debug_printf("trying server %s, port %u\n",
 166                    spamd_address_vector[current_server]->tcp_addr,
 167                    spamd_address_vector[current_server]->tcp_port);
 168
 169       /* contact a spamd */
 170       if ( (spamd_sock = ip_socket(SOCK_STREAM, AF_INET)) < 0)
 171         {
 172         log_write(0, LOG_MAIN|LOG_PANIC,
 173            "spam acl condition: error creating IP socket for spamd");
 174         (void)fclose(mbox_file);
 175         return DEFER;
 176         }
 177
 178       if (ip_connect( spamd_sock,
 179                       AF_INET,
 180                       spamd_address_vector[current_server]->tcp_addr,
 181                       spamd_address_vector[current_server]->tcp_port,
 182                       5 ) > -1)
 183         /* connection OK */
 184         break;
 185
 186       log_write(0, LOG_MAIN|LOG_PANIC,
 187          "spam acl condition: warning - spamd connection to %s, port %u failed: %s",
 188          spamd_address_vector[current_server]->tcp_addr,
 189          spamd_address_vector[current_server]->tcp_port,
 190          strerror(errno));
 191
 192       (void)close(spamd_sock);
 193
 194       /* Remove the server from the list. XXX We should free the memory */
 195       num_servers--;
 196       for ( i = current_server; i < num_servers; i++ )
 197         spamd_address_vector[i] = spamd_address_vector[i+1];
 198       }
 199
 200     if ( num_servers == 0 )
 201       {
 202       log_write(0, LOG_MAIN|LOG_PANIC, "spam acl condition: all spamd servers failed");
 203       (void)fclose(mbox_file);
 204       return DEFER;
 205       }
 206     }
 207   else
 208     {
 209     /* open the local socket */
 210
 211     if ((spamd_sock = socket(AF_UNIX, SOCK_STREAM, 0)) < 0)
 212       {
 213       log_write(0, LOG_MAIN|LOG_PANIC,
 214                 "malware acl condition: spamd: unable to acquire socket (%s)",
 215                 strerror(errno));
 216       (void)fclose(mbox_file);
 217       return DEFER;
 218       }
 219
 220     server.sun_family = AF_UNIX;
 221     Ustrcpy(server.sun_path, spamd_address_work);
 222
 223     if (connect(spamd_sock, (struct sockaddr *) &server, sizeof(struct sockaddr_un)) < 0)
 224       {
 225       log_write(0, LOG_MAIN|LOG_PANIC,
 226                 "malware acl condition: spamd: unable to connect to UNIX socket %s (%s)",
 227                 spamd_address_work, strerror(errno) );
 228       (void)fclose(mbox_file);
 229       (void)close(spamd_sock);
 230       return DEFER;
 231       }
 232     }
 233
 234   if (spamd_sock == -1)
 235     {
 236     log_write(0, LOG_MAIN|LOG_PANIC,
 237         "programming fault, spamd_sock unexpectedly unset");
 238     (void)fclose(mbox_file);
 239     (void)close(spamd_sock);
 240     return DEFER;
 241     }
 242
 243   /* now we are connected to spamd on spamd_sock */
 244   (void)string_format(spamd_buffer,
 245            sizeof(spamd_buffer),
 246            "REPORT SPAMC/1.2\r\nUser: %s\r\nContent-length: %ld\r\n\r\n",
 247            user_name,
 248            mbox_size);
 249
 250   /* send our request */
 251   if (send(spamd_sock, spamd_buffer, Ustrlen(spamd_buffer), 0) < 0)
 252     {
 253     (void)close(spamd_sock);
 254     log_write(0, LOG_MAIN|LOG_PANIC,
 255          "spam acl condition: spamd send failed: %s", strerror(errno));
 256     (void)fclose(mbox_file);
 257     (void)close(spamd_sock);
 258     return DEFER;
 259     }
 260
 261   /* now send the file */
 262   /* spamd sometimes accepts conections but doesn't read data off
 263    * the connection.  We make the file descriptor non-blocking so
 264    * that the write will only write sufficient data without blocking
 265    * and we poll the desciptor to make sure that we can write without
 266    * blocking.  Short writes are gracefully handled and if the whole
 267    * trasaction takes too long it is aborted.
 268    * Note: poll() is not supported in OSX 10.2 and is reported to be
 269    *       broken in more recent versions (up to 10.4).
 270    */
 271 #ifndef NO_POLL_H
 272   pollfd.fd = spamd_sock;
 273   pollfd.events = POLLOUT;
 274 #endif
 275   (void)fcntl(spamd_sock, F_SETFL, O_NONBLOCK);
 276   do
 277     {
 278     read = fread(spamd_buffer,1,sizeof(spamd_buffer),mbox_file);
 279     if (read > 0)
 280       {
 281       offset = 0;
 282 again:
 283 #ifndef NO_POLL_H
 284       result = poll(&pollfd, 1, 1000);
 285
 286 /* Patch posted by Erik ? for OS X and applied by PH */
 287 #else
 288       select_tv.tv_sec = 1;
 289       select_tv.tv_usec = 0;
 290       FD_ZERO(&select_fd);
 291       FD_SET(spamd_sock, &select_fd);
 292       result = select(spamd_sock+1, NULL, &select_fd, NULL, &select_tv);
 293 #endif
 294 /* End Erik's patch */
 295
 296       if (result == -1 && errno == EINTR)
 297         goto again;
 298       else if (result < 1)
 299         {
 300         if (result == -1)
 301           log_write(0, LOG_MAIN|LOG_PANIC,
 302             "spam acl condition: %s on spamd socket", strerror(errno));
 303         else
 304           {
 305           if (time(NULL) - start < SPAMD_TIMEOUT)
 306             goto again;
 307           log_write(0, LOG_MAIN|LOG_PANIC,
 308             "spam acl condition: timed out writing spamd socket");
 309           }
 310         (void)close(spamd_sock);
 311         (void)fclose(mbox_file);
 312         return DEFER;
 313         }
 314
 315       wrote = send(spamd_sock,spamd_buffer + offset,read - offset,0);
 316       if (wrote == -1)
 317         {
 318         log_write(0, LOG_MAIN|LOG_PANIC,
 319             "spam acl condition: %s on spamd socket", strerror(errno));
 320         (void)close(spamd_sock);
 321         (void)fclose(mbox_file);
 322         return DEFER;
 323         }
 324       if (offset + wrote != read)
 325         {
 326         offset += wrote;
 327         goto again;
 328         }
 329       }
 330     }
 331   while (!feof(mbox_file) && !ferror(mbox_file));
 332
 333   if (ferror(mbox_file))
 334     {
 335     log_write(0, LOG_MAIN|LOG_PANIC,
 336       "spam acl condition: error reading spool file: %s", strerror(errno));
 337     (void)close(spamd_sock);
 338     (void)fclose(mbox_file);
 339     return DEFER;
 340     }
 341
 342   (void)fclose(mbox_file);
 343
 344   /* we're done sending, close socket for writing */
 345   shutdown(spamd_sock,SHUT_WR);
 346
 347   /* read spamd response using what's left of the timeout.
 348    */
 349   memset(spamd_buffer, 0, sizeof(spamd_buffer));
 350   offset = 0;
 351   while ((i = ip_recv(spamd_sock,
 352                      spamd_buffer + offset,
 353                      sizeof(spamd_buffer) - offset - 1,
 354                      SPAMD_TIMEOUT - time(NULL) + start)) > 0 )
 355     offset += i;
 356
 357   /* error handling */
 358   if (i <= 0 && errno != 0)
 359     {
 360     log_write(0, LOG_MAIN|LOG_PANIC,
 361          "spam acl condition: error reading from spamd socket: %s", strerror(errno));
 362     (void)close(spamd_sock);
 363     return DEFER;
 364     }
 365
 366   /* reading done */
 367   (void)close(spamd_sock);
 368
 369   /* dig in the spamd output and put the report in a multiline header, if requested */
 370   if (sscanf(CS spamd_buffer,
 371               "SPAMD/%7s 0 EX_OK\r\nContent-length: %*u\r\n\r\n%lf/%lf\r\n%n",
 372               spamd_version, &spamd_score, &spamd_threshold,
 373               &spamd_report_offset) != 3)
 374     {
 375
 376     /* try to fall back to pre-2.50 spamd output */
 377     if (sscanf(CS spamd_buffer,
 378                 "SPAMD/%7s 0 EX_OK\r\nSpam: %*s ; %lf / %lf\r\n\r\n%n",
 379                 spamd_version, &spamd_score, &spamd_threshold,
 380                 &spamd_report_offset) != 3 )
 381       {
 382       log_write(0, LOG_MAIN|LOG_PANIC,
 383          "spam acl condition: cannot parse spamd output");
 384       return DEFER;
 385       }
 386     }
 387
 388   /* Create report. Since this is a multiline string,
 389   we must hack it into shape first */
 390   p = &spamd_buffer[spamd_report_offset];
 391   q = spam_report_buffer;
 392   while (*p != '\0')
 393     {
 394     /* skip \r */
 395     if (*p == '\r')
 396       {
 397       p++;
 398       continue;
 399       }
 400     *q++ = *p;
 401     if (*p++ == '\n')
 402       {
 403       /* add an extra space after the newline to ensure
 404       that it is treated as a header continuation line */
 405       *q++ = ' ';
 406       }
 407     }
 408   /* NULL-terminate */
 409   *q-- = '\0';
 410   /* cut off trailing leftovers */
 411   while (*q <= ' ')
 412     *q-- = '\0';
 413
 414   spam_report = spam_report_buffer;
 415
 416   /* create spam bar */
 417   spamd_score_char = spamd_score > 0 ? '+' : '-';
 418   j = abs((int)(spamd_score));
 419   i = 0;
 420   if (j != 0)
 421     while ((i < j) && (i <= MAX_SPAM_BAR_CHARS))
 422        spam_bar_buffer[i++] = spamd_score_char;
 423   else
 424     {
 425     spam_bar_buffer[0] = '/';
 426     i = 1;
 427     }
 428   spam_bar_buffer[i] = '\0';
 429   spam_bar = spam_bar_buffer;
 430
 431   /* create "float" spam score */
 432   (void)string_format(spam_score_buffer, sizeof(spam_score_buffer),"%.1f", spamd_score);
 433   spam_score = spam_score_buffer;
 434
 435   /* create "int" spam score */
 436   j = (int)((spamd_score + 0.001)*10);
 437   (void)string_format(spam_score_int_buffer, sizeof(spam_score_int_buffer), "%d", j);
 438   spam_score_int = spam_score_int_buffer;
 439
 440   /* compare threshold against score */
 441   if (spamd_score >= spamd_threshold)
 442     {
 443     /* spam as determined by user's threshold */
 444     spam_rc = OK;
 445     }
 446   else
 447     {
 448     /* not spam */
 449     spam_rc = FAIL;
 450     }
 451
 452   /* remember expanded spamd_address if needed */
 453   if (spamd_address_work != spamd_address)
 454     prev_spamd_address_work = string_copy(spamd_address_work);
 455
 456   /* remember user name and "been here" for it */
 457   Ustrcpy(prev_user_name, user_name);
 458   spam_ok = 1;
 459
 460   if (override) /* always return OK, no matter what the score */
 461     return OK;
 462   else
 463     return spam_rc;
 464 }
 465
 466 #endif