src/src/mime.c

   1 /*************************************************
   2 *     Exim - an Internet mail transport agent    *
   3 *************************************************/
   4
   5 /* Copyright (c) Tom Kistner <tom@duncanthrax.net> 2004, 2015
   6  * License: GPL
   7  * Copyright (c) The Exim Maintainers 2016
   8  */
   9
  10 #include "exim.h"
  11 #ifdef WITH_CONTENT_SCAN        /* entire file */
  12 #include "mime.h"
  13 #include <sys/stat.h>
  14
  15 FILE *mime_stream = NULL;
  16 uschar *mime_current_boundary = NULL;
  17
  18 static mime_header mime_header_list[] = {
  19   { US"content-type:",              13, &mime_content_type },
  20   { US"content-disposition:",       20, &mime_content_disposition },
  21   { US"content-transfer-encoding:", 26, &mime_content_transfer_encoding },
  22   { US"content-id:",                11, &mime_content_id },
  23   { US"content-description:",       20, &mime_content_description }
  24 };
  25
  26 static int mime_header_list_size = nelem(mime_header_list);
  27
  28 static mime_parameter mime_parameter_list[] = {
  29   { US"name=",     5, &mime_filename },
  30   { US"filename=", 9, &mime_filename },
  31   { US"charset=",  8, &mime_charset  },
  32   { US"boundary=", 9, &mime_boundary }
  33 };
  34
  35
  36 /*************************************************
  37 * set MIME anomaly level + text                  *
  38 *************************************************/
  39
  40 /* Small wrapper to set the two expandables which
  41    give info on detected "problems" in MIME
  42    encodings. Indexes are defined in mime.h. */
  43
  44 void
  45 mime_set_anomaly(int idx)
  46 {
  47 struct anom {
  48   int level;
  49   const uschar * text;
  50 } anom[] = { {1, CUS"Broken Quoted-Printable encoding detected"},
  51              {2, CUS"Broken BASE64 encoding detected"} };
  52
  53 mime_anomaly_level = anom[idx].level;
  54 mime_anomaly_text =  anom[idx].text;
  55 }
  56
  57
  58 /*************************************************
  59 * decode quoted-printable chars                  *
  60 *************************************************/
  61
  62 /* gets called when we hit a =
  63    returns: new pointer position
  64    result code in c:
  65           -2 - decode error
  66           -1 - soft line break, no char
  67            0-255 - char to write
  68 */
  69
  70 static uschar *
  71 mime_decode_qp_char(uschar *qp_p, int *c)
  72 {
  73 uschar *initial_pos = qp_p;
  74
  75 /* advance one char */
  76 qp_p++;
  77
  78 /* Check for two hex digits and decode them */
  79 if (isxdigit(*qp_p) && isxdigit(qp_p[1]))
  80   {
  81   /* Do hex conversion */
  82   *c = (isdigit(*qp_p) ? *qp_p - '0' : toupper(*qp_p) - 'A' + 10) <<4;
  83   qp_p++;
  84   *c |= isdigit(*qp_p) ? *qp_p - '0' : toupper(*qp_p) - 'A' + 10;
  85   return qp_p + 1;
  86   }
  87
  88 /* tab or whitespace may follow just ignore it if it precedes \n */
  89 while (*qp_p == '\t' || *qp_p == ' ' || *qp_p == '\r')
  90   qp_p++;
  91
  92 if (*qp_p == '\n')      /* hit soft line break */
  93   {
  94   *c = -1;
  95   return qp_p;
  96   }
  97
  98 /* illegal char here */
  99 *c = -2;
 100 return initial_pos;
 101 }
 102
 103
 104 /* just dump MIME part without any decoding */
 105 static ssize_t
 106 mime_decode_asis(FILE* in, FILE* out, uschar* boundary)
 107 {
 108   ssize_t len, size = 0;
 109   uschar buffer[MIME_MAX_LINE_LENGTH];
 110
 111   while(fgets(CS buffer, MIME_MAX_LINE_LENGTH, mime_stream) != NULL)
 112     {
 113     if (boundary != NULL
 114        && Ustrncmp(buffer, "--", 2) == 0
 115        && Ustrncmp((buffer+2), boundary, Ustrlen(boundary)) == 0
 116        )
 117       break;
 118
 119     len = Ustrlen(buffer);
 120     if (fwrite(buffer, 1, (size_t)len, out) < len)
 121       return -1;
 122     size += len;
 123     } /* while */
 124   return size;
 125 }
 126
 127
 128
 129 /* decode quoted-printable MIME part */
 130 static ssize_t
 131 mime_decode_qp(FILE* in, FILE* out, uschar* boundary)
 132 {
 133 uschar ibuf[MIME_MAX_LINE_LENGTH], obuf[MIME_MAX_LINE_LENGTH];
 134 uschar *ipos, *opos;
 135 ssize_t len, size = 0;
 136
 137 while (fgets(CS ibuf, MIME_MAX_LINE_LENGTH, in) != NULL)
 138   {
 139   if (boundary != NULL
 140      && Ustrncmp(ibuf, "--", 2) == 0
 141      && Ustrncmp((ibuf+2), boundary, Ustrlen(boundary)) == 0
 142      )
 143     break; /* todo: check for missing boundary */
 144
 145   ipos = ibuf;
 146   opos = obuf;
 147
 148   while (*ipos != 0)
 149     {
 150     if (*ipos == '=')
 151       {
 152       int decode_qp_result;
 153
 154       ipos = mime_decode_qp_char(ipos, &decode_qp_result);
 155
 156       if (decode_qp_result == -2)
 157         {
 158         /* Error from decoder. ipos is unchanged. */
 159         mime_set_anomaly(MIME_ANOMALY_BROKEN_QP);
 160         *opos = '=';
 161         ++opos;
 162         ++ipos;
 163         }
 164       else if (decode_qp_result == -1)
 165         break;
 166       else if (decode_qp_result >= 0)
 167         {
 168         *opos = decode_qp_result;
 169         ++opos;
 170         }
 171       }
 172     else
 173       {
 174       *opos = *ipos;
 175       ++opos;
 176       ++ipos;
 177       }
 178     }
 179   /* something to write? */
 180   len = opos - obuf;
 181   if (len > 0)
 182     {
 183     if (fwrite(obuf, 1, len, out) != len) return -1; /* error */
 184     size += len;
 185     }
 186   }
 187 return size;
 188 }
 189
 190
 191 static FILE *
 192 mime_get_decode_file(uschar *pname, uschar *fname)
 193 {
 194 FILE *f = NULL;
 195 uschar *filename;
 196
 197 filename = (uschar *)malloc(2048);
 198
 199 if (pname && fname)
 200   {
 201   (void)string_format(filename, 2048, "%s/%s", pname, fname);
 202   f = modefopen(filename,"wb+",SPOOL_MODE);
 203   }
 204 else if (!pname)
 205   f = modefopen(fname,"wb+",SPOOL_MODE);
 206 else if (!fname)
 207   {
 208   int file_nr = 0;
 209   int result = 0;
 210
 211   /* must find first free sequential filename */
 212   do
 213     {
 214     struct stat mystat;
 215     (void)string_format(filename, 2048,
 216       "%s/%s-%05u", pname, message_id, file_nr++);
 217     /* security break */
 218     if (file_nr >= 1024)
 219       break;
 220     result = stat(CS filename, &mystat);
 221     } while(result != -1);
 222
 223   f = modefopen(filename, "wb+", SPOOL_MODE);
 224   }
 225
 226 /* set expansion variable */
 227 mime_decoded_filename = filename;
 228
 229 return f;
 230 }
 231
 232
 233 int
 234 mime_decode(const uschar **listptr)
 235 {
 236 int sep = 0;
 237 const uschar *list = *listptr;
 238 uschar *option;
 239 uschar option_buffer[1024];
 240 uschar decode_path[1024];
 241 FILE *decode_file = NULL;
 242 long f_pos = 0;
 243 ssize_t size_counter = 0;
 244 ssize_t (*decode_function)(FILE*, FILE*, uschar*);
 245
 246 if (mime_stream == NULL)
 247   return FAIL;
 248
 249 f_pos = ftell(mime_stream);
 250
 251 /* build default decode path (will exist since MBOX must be spooled up) */
 252 (void)string_format(decode_path,1024,"%s/scan/%s",spool_directory,message_id);
 253
 254 /* try to find 1st option */
 255 if ((option = string_nextinlist(&list, &sep,
 256                                 option_buffer,
 257                                 sizeof(option_buffer))) != NULL)
 258   {
 259   /* parse 1st option */
 260   if ( (Ustrcmp(option,"false") == 0) || (Ustrcmp(option,"0") == 0) )
 261     /* explicitly no decoding */
 262     return FAIL;
 263
 264   if (Ustrcmp(option,"default") == 0)
 265     /* explicit default path + file names */
 266     goto DEFAULT_PATH;
 267
 268   if (option[0] == '/')
 269     {
 270     struct stat statbuf;
 271
 272     memset(&statbuf,0,sizeof(statbuf));
 273
 274     /* assume either path or path+file name */
 275     if ( (stat(CS option, &statbuf) == 0) && S_ISDIR(statbuf.st_mode) )
 276       /* is directory, use it as decode_path */
 277       decode_file = mime_get_decode_file(option, NULL);
 278     else
 279       /* does not exist or is a file, use as full file name */
 280       decode_file = mime_get_decode_file(NULL, option);
 281     }
 282   else
 283     /* assume file name only, use default path */
 284     decode_file = mime_get_decode_file(decode_path, option);
 285   }
 286 else
 287   {
 288   /* no option? patch default path */
 289 DEFAULT_PATH:
 290   decode_file = mime_get_decode_file(decode_path, NULL);
 291   }
 292
 293 if (!decode_file)
 294   return DEFER;
 295
 296 /* decode according to mime type */
 297 decode_function =
 298   !mime_content_transfer_encoding
 299   ? mime_decode_asis    /* no encoding, dump as-is */
 300   : Ustrcmp(mime_content_transfer_encoding, "base64") == 0
 301   ? mime_decode_base64
 302   : Ustrcmp(mime_content_transfer_encoding, "quoted-printable") == 0
 303   ? mime_decode_qp
 304   : mime_decode_asis;   /* unknown encoding type, just dump as-is */
 305
 306 size_counter = decode_function(mime_stream, decode_file, mime_current_boundary);
 307
 308 clearerr(mime_stream);
 309 if (fseek(mime_stream, f_pos, SEEK_SET))
 310   return DEFER;
 311
 312 if (fclose(decode_file) != 0 || size_counter < 0)
 313   return DEFER;
 314
 315 /* round up to the next KiB */
 316 mime_content_size = (size_counter + 1023) / 1024;
 317
 318 return OK;
 319 }
 320
 321
 322 static int
 323 mime_get_header(FILE *f, uschar *header)
 324 {
 325 int c = EOF;
 326 int done = 0;
 327 int header_value_mode = 0;
 328 int header_open_brackets = 0;
 329 int num_copied = 0;
 330
 331 while(!done)
 332   {
 333   if ((c = fgetc(f)) == EOF) break;
 334
 335   /* always skip CRs */
 336   if (c == '\r') continue;
 337
 338   if (c == '\n')
 339     {
 340     if (num_copied > 0)
 341       {
 342       /* look if next char is '\t' or ' ' */
 343       if ((c = fgetc(f)) == EOF) break;
 344       if ( (c == '\t') || (c == ' ') ) continue;
 345       (void)ungetc(c,f);
 346       }
 347     /* end of the header, terminate with ';' */
 348     c = ';';
 349     done = 1;
 350     }
 351
 352   /* skip control characters */
 353   if (c < 32) continue;
 354
 355   if (header_value_mode)
 356     {
 357     /* --------- value mode ----------- */
 358     /* skip leading whitespace */
 359     if ( ((c == '\t') || (c == ' ')) && (header_value_mode == 1) )
 360       continue;
 361
 362       /* we have hit a non-whitespace char, start copying value data */
 363       header_value_mode = 2;
 364
 365       if (c == '"')       /* flip "quoted" mode */
 366         header_value_mode = header_value_mode==2 ? 3 : 2;
 367
 368       /* leave value mode on unquoted ';' */
 369       if (header_value_mode == 2 && c == ';') {
 370         header_value_mode = 0;
 371       };
 372       /* -------------------------------- */
 373     }
 374   else
 375     {
 376     /* -------- non-value mode -------- */
 377     /* skip whitespace + tabs */
 378     if ( (c == ' ') || (c == '\t') )
 379       continue;
 380     if (c == '\\')
 381       {
 382       /* quote next char. can be used
 383       to escape brackets. */
 384       if ((c = fgetc(f)) == EOF) break;
 385       }
 386     else if (c == '(')
 387       {
 388       header_open_brackets++;
 389       continue;
 390       }
 391     else if ((c == ')') && header_open_brackets)
 392       {
 393       header_open_brackets--;
 394       continue;
 395       }
 396     else if ( (c == '=') && !header_open_brackets ) /* enter value mode */
 397       header_value_mode = 1;
 398
 399     /* skip chars while we are in a comment */
 400     if (header_open_brackets > 0)
 401       continue;
 402     /* -------------------------------- */
 403     }
 404
 405   /* copy the char to the buffer */
 406   header[num_copied++] = (uschar)c;
 407
 408   /* break if header buffer is full */
 409   if (num_copied > MIME_MAX_HEADER_SIZE-1)
 410     done = 1;
 411   }
 412
 413 if ((num_copied > 0) && (header[num_copied-1] != ';'))
 414   header[num_copied-1] = ';';
 415
 416 /* 0-terminate */
 417 header[num_copied] = '\0';
 418
 419 /* return 0 for EOF or empty line */
 420 if ((c == EOF) || (num_copied == 1))
 421   return 0;
 422 else
 423   return 1;
 424 }
 425
 426
 427 static void
 428 mime_vars_reset(void)
 429 {
 430 mime_anomaly_level     = 0;
 431 mime_anomaly_text      = NULL;
 432 mime_boundary          = NULL;
 433 mime_charset           = NULL;
 434 mime_decoded_filename  = NULL;
 435 mime_filename          = NULL;
 436 mime_content_description = NULL;
 437 mime_content_disposition = NULL;
 438 mime_content_id        = NULL;
 439 mime_content_transfer_encoding = NULL;
 440 mime_content_type      = NULL;
 441 mime_is_multipart      = 0;
 442 mime_content_size      = 0;
 443 }
 444
 445
 446 /* Grab a parameter value, dealing with quoting.
 447
 448 Arguments:
 449  str    Input string.  Updated on return to point to terminating ; or NUL
 450
 451 Return:
 452  Allocated string with parameter value
 453 */
 454 static uschar *
 455 mime_param_val(uschar ** sp)
 456 {
 457 uschar * s = *sp;
 458 uschar * val = NULL;
 459 int size = 0, ptr = 0;
 460
 461 /* debug_printf("   considering paramval '%s'\n", s); */
 462
 463 while (*s && *s != ';')         /* ; terminates */
 464   if (*s == '"')
 465     {
 466     s++;                        /* skip opening " */
 467     while (*s && *s != '"')     /* " protects ; */
 468       val = string_cat(val, &size, &ptr, s++, 1);
 469     if (*s) s++;                /* skip closing " */
 470     }
 471   else
 472     val = string_cat(val, &size, &ptr, s++, 1);
 473 if (val) val[ptr] = '\0';
 474 *sp = s;
 475 return val;
 476 }
 477
 478 static uschar *
 479 mime_next_semicolon(uschar * s)
 480 {
 481 while (*s && *s != ';')         /* ; terminates */
 482   if (*s == '"')
 483     {
 484     s++;                        /* skip opening " */
 485     while (*s && *s != '"')     /* " protects ; */
 486       s++;
 487     if (*s) s++;                /* skip closing " */
 488     }
 489   else
 490     s++;
 491 return s;
 492 }
 493
 494
 495 static uschar *
 496 rfc2231_to_2047(const uschar * fname, const uschar * charset, int * len)
 497 {
 498 int size = 0, ptr = 0;
 499 uschar * val = string_cat(NULL, &size, &ptr, US"=?", 2);
 500 uschar c;
 501
 502 if (charset)
 503   val = string_cat(val, &size, &ptr, charset, Ustrlen(charset));
 504 val = string_cat(val, &size, &ptr, US"?Q?", 3);
 505
 506 while ((c = *fname))
 507   if (c == '%' && isxdigit(fname[1]) && isxdigit(fname[2]))
 508     {
 509     val = string_cat(val, &size, &ptr, US"=", 1);
 510     val = string_cat(val, &size, &ptr, ++fname, 2);
 511     fname += 2;
 512     }
 513   else
 514     val = string_cat(val, &size, &ptr, fname++, 1);
 515
 516 val = string_cat(val, &size, &ptr, US"?=", 2);
 517 val[*len = ptr] = '\0';
 518 return val;
 519 }
 520
 521
 522 int
 523 mime_acl_check(uschar *acl, FILE *f, struct mime_boundary_context *context,
 524     uschar **user_msgptr, uschar **log_msgptr)
 525 {
 526 int rc = OK;
 527 uschar * header = NULL;
 528 struct mime_boundary_context nested_context;
 529
 530 /* reserve a line buffer to work in */
 531 header = store_get(MIME_MAX_HEADER_SIZE+1);
 532
 533 /* Not actually used at the moment, but will be vital to fixing
 534  * some RFC 2046 nonconformance later... */
 535 nested_context.parent = context;
 536
 537 /* loop through parts */
 538 while(1)
 539   {
 540   /* reset all per-part mime variables */
 541   mime_vars_reset();
 542
 543   /* If boundary is null, we assume that *f is positioned on the start of
 544   headers (for example, at the very beginning of a message.  If a boundary is
 545   given, we must first advance to it to reach the start of the next header
 546   block.  */
 547
 548   /* NOTE -- there's an error here -- RFC2046 specifically says to
 549    * check for outer boundaries.  This code doesn't do that, and
 550    * I haven't fixed this.
 551    *
 552    * (I have moved partway towards adding support, however, by adding
 553    * a "parent" field to my new boundary-context structure.)
 554    */
 555   if (context) for (;;)
 556     {
 557     if (!fgets(CS header, MIME_MAX_HEADER_SIZE, f))
 558       {
 559       /* Hit EOF or read error. Ugh. */
 560       DEBUG(D_acl) debug_printf("MIME: Hit EOF ...\n");
 561       return rc;
 562       }
 563
 564     /* boundary line must start with 2 dashes */
 565     if (  Ustrncmp(header, "--", 2) == 0
 566        && Ustrncmp(header+2, context->boundary, Ustrlen(context->boundary)) == 0
 567        )
 568       {                 /* found boundary */
 569       if (Ustrncmp((header+2+Ustrlen(context->boundary)), "--", 2) == 0)
 570         {
 571         /* END boundary found */
 572         DEBUG(D_acl) debug_printf("MIME: End boundary found %s\n",
 573           context->boundary);
 574         return rc;
 575         }
 576
 577       DEBUG(D_acl) debug_printf("MIME: Next part with boundary %s\n",
 578         context->boundary);
 579       break;
 580       }
 581     }
 582
 583   /* parse headers, set up expansion variables */
 584   while (mime_get_header(f, header))
 585     {
 586     struct mime_header * mh;
 587
 588     /* look for interesting headers */
 589     for (mh = mime_header_list;
 590          mh < mime_header_list + mime_header_list_size;
 591          mh++) if (strncmpic(mh->name, header, mh->namelen) == 0)
 592       {
 593       uschar * p = header + mh->namelen;
 594       uschar * q;
 595
 596       /* grab the value (normalize to lower case)
 597       and copy to its corresponding expansion variable */
 598
 599       for (q = p; *q != ';' && *q; q++) ;
 600       *mh->value = string_copynlc(p, q-p);
 601       DEBUG(D_acl) debug_printf("MIME: found %s header, value is '%s'\n",
 602         mh->name, *mh->value);
 603
 604       if (*(p = q)) p++;                        /* jump past the ; */
 605
 606         {
 607         uschar * mime_fname = NULL;
 608         uschar * mime_fname_rfc2231 = NULL;
 609         uschar * mime_filename_charset = NULL;
 610         BOOL decoding_failed = FALSE;
 611
 612         /* grab all param=value tags on the remaining line,
 613         check if they are interesting */
 614
 615         while (*p)
 616           {
 617           mime_parameter * mp;
 618
 619           DEBUG(D_acl) debug_printf("MIME:   considering paramlist '%s'\n", p);
 620
 621           if (  !mime_filename
 622              && strncmpic(CUS"content-disposition:", header, 20) == 0
 623              && strncmpic(CUS"filename*", p, 9) == 0
 624              )
 625             {                                   /* RFC 2231 filename */
 626             uschar * q;
 627
 628             /* find value of the filename */
 629             p += 9;
 630             while(*p != '=' && *p) p++;
 631             if (*p) p++;                        /* p is filename or NUL */
 632             q = mime_param_val(&p);             /* p now trailing ; or NUL */
 633
 634             if (q && *q)
 635               {
 636               uschar * temp_string, * err_msg;
 637               int slen;
 638
 639               /* build up an un-decoded filename over successive
 640               filename*= parameters (for use when 2047 decode fails) */
 641
 642               mime_fname_rfc2231 = string_sprintf("%#s%s",
 643                 mime_fname_rfc2231, q);
 644
 645               if (!decoding_failed)
 646                 {
 647                 int size;
 648                 if (!mime_filename_charset)
 649                   {
 650                   uschar * s = q;
 651
 652                   /* look for a ' in the "filename" */
 653                   while(*s != '\'' && *s) s++;  /* s is 1st ' or NUL */
 654
 655                   if ((size = s-q) > 0)
 656                     mime_filename_charset = string_copyn(q, size);
 657
 658                   if (*(p = s)) p++;
 659                   while(*p == '\'') p++;        /* p is after 2nd ' */
 660                   }
 661                 else
 662                   p = q;
 663
 664                 DEBUG(D_acl) debug_printf("MIME:    charset %s fname '%s'\n",
 665                   mime_filename_charset ? mime_filename_charset : US"<NULL>", p);
 666
 667                 temp_string = rfc2231_to_2047(p, mime_filename_charset, &slen);
 668                 DEBUG(D_acl) debug_printf("MIME:    2047-name %s\n", temp_string);
 669
 670                 temp_string = rfc2047_decode(temp_string, FALSE, NULL, ' ',
 671                   NULL, &err_msg);
 672                 DEBUG(D_acl) debug_printf("MIME:    plain-name %s\n", temp_string);
 673
 674                 size = Ustrlen(temp_string);
 675
 676                 if (size == slen)
 677                   decoding_failed = TRUE;
 678                 else
 679                   /* build up a decoded filename over successive
 680                   filename*= parameters */
 681
 682                   mime_filename = mime_fname = mime_fname
 683                     ? string_sprintf("%s%s", mime_fname, temp_string)
 684                     : temp_string;
 685                 }
 686               }
 687             }
 688
 689           else
 690             /* look for interesting parameters */
 691             for (mp = mime_parameter_list;
 692                  mp < mime_parameter_list + nelem(mime_parameter_list);
 693                  mp++
 694                 ) if (strncmpic(mp->name, p, mp->namelen) == 0)
 695               {
 696               uschar * q;
 697               uschar * dummy_errstr;
 698
 699               /* grab the value and copy to its expansion variable */
 700               p += mp->namelen;
 701               q = mime_param_val(&p);           /* p now trailing ; or NUL */
 702
 703               *mp->value = q && *q
 704                 ? rfc2047_decode(q, check_rfc2047_length, NULL, 32, NULL,
 705                     &dummy_errstr)
 706                 : NULL;
 707               DEBUG(D_acl) debug_printf(
 708                 "MIME:  found %s parameter in %s header, value '%s'\n",
 709                 mp->name, mh->name, *mp->value);
 710
 711               break;                    /* done matching param names */
 712               }
 713
 714
 715           /* There is something, but not one of our interesting parameters.
 716              Advance past the next semicolon */
 717           p = mime_next_semicolon(p);
 718           if (*p) p++;
 719           }                             /* param scan on line */
 720
 721         if (strncmpic(CUS"content-disposition:", header, 20) == 0)
 722           {
 723           if (decoding_failed) mime_filename = mime_fname_rfc2231;
 724
 725           DEBUG(D_acl) debug_printf(
 726             "MIME:  found %s parameter in %s header, value is '%s'\n",
 727             "filename", mh->name, mime_filename);
 728           }
 729         }
 730       }
 731     }
 732
 733   /* set additional flag variables (easier access) */
 734   if (  mime_content_type
 735      && Ustrncmp(mime_content_type,"multipart",9) == 0
 736      )
 737     mime_is_multipart = 1;
 738
 739   /* Make a copy of the boundary pointer.
 740      Required since mime_boundary is global
 741      and can be overwritten further down in recursion */
 742   nested_context.boundary = mime_boundary;
 743
 744   /* raise global counter */
 745   mime_part_count++;
 746
 747   /* copy current file handle to global variable */
 748   mime_stream = f;
 749   mime_current_boundary = context ? context->boundary : 0;
 750
 751   /* Note the context */
 752   mime_is_coverletter = !(context && context->context == MBC_ATTACHMENT);
 753
 754   /* call ACL handling function */
 755   rc = acl_check(ACL_WHERE_MIME, NULL, acl, user_msgptr, log_msgptr);
 756
 757   mime_stream = NULL;
 758   mime_current_boundary = NULL;
 759
 760   if (rc != OK) break;
 761
 762   /* If we have a multipart entity and a boundary, go recursive */
 763   if ( (mime_content_type != NULL) &&
 764        (nested_context.boundary != NULL) &&
 765        (Ustrncmp(mime_content_type,"multipart",9) == 0) )
 766     {
 767     DEBUG(D_acl)
 768       debug_printf("MIME: Entering multipart recursion, boundary '%s'\n",
 769         nested_context.boundary);
 770
 771     nested_context.context =
 772       context && context->context == MBC_ATTACHMENT
 773       ? MBC_ATTACHMENT
 774       :    Ustrcmp(mime_content_type,"multipart/alternative") == 0
 775         || Ustrcmp(mime_content_type,"multipart/related") == 0
 776       ? MBC_COVERLETTER_ALL
 777       : MBC_COVERLETTER_ONESHOT;
 778
 779     rc = mime_acl_check(acl, f, &nested_context, user_msgptr, log_msgptr);
 780     if (rc != OK) break;
 781     }
 782   else if ( (mime_content_type != NULL) &&
 783           (Ustrncmp(mime_content_type,"message/rfc822",14) == 0) )
 784     {
 785     const uschar *rfc822name = NULL;
 786     uschar filename[2048];
 787     int file_nr = 0;
 788     int result = 0;
 789
 790     /* must find first free sequential filename */
 791     do
 792       {
 793       struct stat mystat;
 794       (void)string_format(filename, 2048,
 795         "%s/scan/%s/__rfc822_%05u", spool_directory, message_id, file_nr++);
 796       /* security break */
 797       if (file_nr >= 128)
 798         goto NO_RFC822;
 799       result = stat(CS filename,&mystat);
 800       } while (result != -1);
 801
 802     rfc822name = filename;
 803
 804     /* decode RFC822 attachment */
 805     mime_decoded_filename = NULL;
 806     mime_stream = f;
 807     mime_current_boundary = context ? context->boundary : NULL;
 808     mime_decode(&rfc822name);
 809     mime_stream = NULL;
 810     mime_current_boundary = NULL;
 811     if (!mime_decoded_filename)         /* decoding failed */
 812       {
 813       log_write(0, LOG_MAIN,
 814            "mime_regex acl condition warning - could not decode RFC822 MIME part to file.");
 815       rc = DEFER;
 816       goto out;
 817       }
 818     mime_decoded_filename = NULL;
 819     }
 820
 821 NO_RFC822:
 822   /* If the boundary of this instance is NULL, we are finished here */
 823   if (!context) break;
 824
 825   if (context->context == MBC_COVERLETTER_ONESHOT)
 826     context->context = MBC_ATTACHMENT;
 827   }
 828
 829 out:
 830 mime_vars_reset();
 831 return rc;
 832 }
 833
 834 #endif  /*WITH_CONTENT_SCAN*/
 835
 836 /* vi: sw ai sw=2
 837 */