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 /*
 192  * Return open filehandle for combo of path and file.
 193  * Side-effect: set mime_decoded_filename, to copy in allocated mem
 194  */
 195 static FILE *
 196 mime_get_decode_file(uschar *pname, uschar *fname)
 197 {
 198 if (pname && fname)
 199   mime_decoded_filename = string_sprintf("%s/%s", pname, fname);
 200 else if (!pname)
 201   mime_decoded_filename = string_copy(fname);
 202 else if (!fname)
 203   {
 204   int file_nr = 0;
 205   int result = 0;
 206
 207   /* must find first free sequential filename */
 208   do
 209     {
 210     struct stat mystat;
 211     mime_decoded_filename = string_sprintf("%s/%s-%05u", pname, message_id, file_nr++);
 212     /* security break */
 213     if (file_nr >= 1024)
 214       break;
 215     result = stat(CS mime_decoded_filename, &mystat);
 216     } while(result != -1);
 217   }
 218
 219 return modefopen(mime_decoded_filename, "wb+", SPOOL_MODE);
 220 }
 221
 222
 223 int
 224 mime_decode(const uschar **listptr)
 225 {
 226 int sep = 0;
 227 const uschar *list = *listptr;
 228 uschar *option;
 229 uschar option_buffer[1024];
 230 uschar decode_path[1024];
 231 FILE *decode_file = NULL;
 232 long f_pos = 0;
 233 ssize_t size_counter = 0;
 234 ssize_t (*decode_function)(FILE*, FILE*, uschar*);
 235
 236 if (mime_stream == NULL)
 237   return FAIL;
 238
 239 f_pos = ftell(mime_stream);
 240
 241 /* build default decode path (will exist since MBOX must be spooled up) */
 242 (void)string_format(decode_path,1024,"%s/scan/%s",spool_directory,message_id);
 243
 244 /* try to find 1st option */
 245 if ((option = string_nextinlist(&list, &sep,
 246                                 option_buffer,
 247                                 sizeof(option_buffer))) != NULL)
 248   {
 249   /* parse 1st option */
 250   if ( (Ustrcmp(option,"false") == 0) || (Ustrcmp(option,"0") == 0) )
 251     /* explicitly no decoding */
 252     return FAIL;
 253
 254   if (Ustrcmp(option,"default") == 0)
 255     /* explicit default path + file names */
 256     goto DEFAULT_PATH;
 257
 258   if (option[0] == '/')
 259     {
 260     struct stat statbuf;
 261
 262     memset(&statbuf,0,sizeof(statbuf));
 263
 264     /* assume either path or path+file name */
 265     if ( (stat(CS option, &statbuf) == 0) && S_ISDIR(statbuf.st_mode) )
 266       /* is directory, use it as decode_path */
 267       decode_file = mime_get_decode_file(option, NULL);
 268     else
 269       /* does not exist or is a file, use as full file name */
 270       decode_file = mime_get_decode_file(NULL, option);
 271     }
 272   else
 273     /* assume file name only, use default path */
 274     decode_file = mime_get_decode_file(decode_path, option);
 275   }
 276 else
 277   {
 278   /* no option? patch default path */
 279 DEFAULT_PATH:
 280   decode_file = mime_get_decode_file(decode_path, NULL);
 281   }
 282
 283 if (!decode_file)
 284   return DEFER;
 285
 286 /* decode according to mime type */
 287 decode_function =
 288   !mime_content_transfer_encoding
 289   ? mime_decode_asis    /* no encoding, dump as-is */
 290   : Ustrcmp(mime_content_transfer_encoding, "base64") == 0
 291   ? mime_decode_base64
 292   : Ustrcmp(mime_content_transfer_encoding, "quoted-printable") == 0
 293   ? mime_decode_qp
 294   : mime_decode_asis;   /* unknown encoding type, just dump as-is */
 295
 296 size_counter = decode_function(mime_stream, decode_file, mime_current_boundary);
 297
 298 clearerr(mime_stream);
 299 if (fseek(mime_stream, f_pos, SEEK_SET))
 300   return DEFER;
 301
 302 if (fclose(decode_file) != 0 || size_counter < 0)
 303   return DEFER;
 304
 305 /* round up to the next KiB */
 306 mime_content_size = (size_counter + 1023) / 1024;
 307
 308 return OK;
 309 }
 310
 311
 312 static int
 313 mime_get_header(FILE *f, uschar *header)
 314 {
 315 int c = EOF;
 316 int done = 0;
 317 int header_value_mode = 0;
 318 int header_open_brackets = 0;
 319 int num_copied = 0;
 320
 321 while(!done)
 322   {
 323   if ((c = fgetc(f)) == EOF) break;
 324
 325   /* always skip CRs */
 326   if (c == '\r') continue;
 327
 328   if (c == '\n')
 329     {
 330     if (num_copied > 0)
 331       {
 332       /* look if next char is '\t' or ' ' */
 333       if ((c = fgetc(f)) == EOF) break;
 334       if ( (c == '\t') || (c == ' ') ) continue;
 335       (void)ungetc(c,f);
 336       }
 337     /* end of the header, terminate with ';' */
 338     c = ';';
 339     done = 1;
 340     }
 341
 342   /* skip control characters */
 343   if (c < 32) continue;
 344
 345   if (header_value_mode)
 346     {
 347     /* --------- value mode ----------- */
 348     /* skip leading whitespace */
 349     if ( ((c == '\t') || (c == ' ')) && (header_value_mode == 1) )
 350       continue;
 351
 352       /* we have hit a non-whitespace char, start copying value data */
 353       header_value_mode = 2;
 354
 355       if (c == '"')       /* flip "quoted" mode */
 356         header_value_mode = header_value_mode==2 ? 3 : 2;
 357
 358       /* leave value mode on unquoted ';' */
 359       if (header_value_mode == 2 && c == ';') {
 360         header_value_mode = 0;
 361       };
 362       /* -------------------------------- */
 363     }
 364   else
 365     {
 366     /* -------- non-value mode -------- */
 367     /* skip whitespace + tabs */
 368     if ( (c == ' ') || (c == '\t') )
 369       continue;
 370     if (c == '\\')
 371       {
 372       /* quote next char. can be used
 373       to escape brackets. */
 374       if ((c = fgetc(f)) == EOF) break;
 375       }
 376     else if (c == '(')
 377       {
 378       header_open_brackets++;
 379       continue;
 380       }
 381     else if ((c == ')') && header_open_brackets)
 382       {
 383       header_open_brackets--;
 384       continue;
 385       }
 386     else if ( (c == '=') && !header_open_brackets ) /* enter value mode */
 387       header_value_mode = 1;
 388
 389     /* skip chars while we are in a comment */
 390     if (header_open_brackets > 0)
 391       continue;
 392     /* -------------------------------- */
 393     }
 394
 395   /* copy the char to the buffer */
 396   header[num_copied++] = (uschar)c;
 397
 398   /* break if header buffer is full */
 399   if (num_copied > MIME_MAX_HEADER_SIZE-1)
 400     done = 1;
 401   }
 402
 403 if ((num_copied > 0) && (header[num_copied-1] != ';'))
 404   header[num_copied-1] = ';';
 405
 406 /* 0-terminate */
 407 header[num_copied] = '\0';
 408
 409 /* return 0 for EOF or empty line */
 410 if ((c == EOF) || (num_copied == 1))
 411   return 0;
 412 else
 413   return 1;
 414 }
 415
 416
 417 static void
 418 mime_vars_reset(void)
 419 {
 420 mime_anomaly_level     = 0;
 421 mime_anomaly_text      = NULL;
 422 mime_boundary          = NULL;
 423 mime_charset           = NULL;
 424 mime_decoded_filename  = NULL;
 425 mime_filename          = NULL;
 426 mime_content_description = NULL;
 427 mime_content_disposition = NULL;
 428 mime_content_id        = NULL;
 429 mime_content_transfer_encoding = NULL;
 430 mime_content_type      = NULL;
 431 mime_is_multipart      = 0;
 432 mime_content_size      = 0;
 433 }
 434
 435
 436 /* Grab a parameter value, dealing with quoting.
 437
 438 Arguments:
 439  str    Input string.  Updated on return to point to terminating ; or NUL
 440
 441 Return:
 442  Allocated string with parameter value
 443 */
 444 static uschar *
 445 mime_param_val(uschar ** sp)
 446 {
 447 uschar * s = *sp;
 448 uschar * val = NULL;
 449 int size = 0, ptr = 0;
 450
 451 /* debug_printf("   considering paramval '%s'\n", s); */
 452
 453 while (*s && *s != ';')         /* ; terminates */
 454   if (*s == '"')
 455     {
 456     s++;                        /* skip opening " */
 457     while (*s && *s != '"')     /* " protects ; */
 458       val = string_catn(val, &size, &ptr, s++, 1);
 459     if (*s) s++;                /* skip closing " */
 460     }
 461   else
 462     val = string_catn(val, &size, &ptr, s++, 1);
 463 if (val) val[ptr] = '\0';
 464 *sp = s;
 465 return val;
 466 }
 467
 468 static uschar *
 469 mime_next_semicolon(uschar * s)
 470 {
 471 while (*s && *s != ';')         /* ; terminates */
 472   if (*s == '"')
 473     {
 474     s++;                        /* skip opening " */
 475     while (*s && *s != '"')     /* " protects ; */
 476       s++;
 477     if (*s) s++;                /* skip closing " */
 478     }
 479   else
 480     s++;
 481 return s;
 482 }
 483
 484
 485 static uschar *
 486 rfc2231_to_2047(const uschar * fname, const uschar * charset, int * len)
 487 {
 488 int size = 0, ptr = 0;
 489 uschar * val = string_catn(NULL, &size, &ptr, US"=?", 2);
 490 uschar c;
 491
 492 if (charset)
 493   val = string_cat(val, &size, &ptr, charset);
 494 val = string_catn(val, &size, &ptr, US"?Q?", 3);
 495
 496 while ((c = *fname))
 497   if (c == '%' && isxdigit(fname[1]) && isxdigit(fname[2]))
 498     {
 499     val = string_catn(val, &size, &ptr, US"=", 1);
 500     val = string_catn(val, &size, &ptr, ++fname, 2);
 501     fname += 2;
 502     }
 503   else
 504     val = string_catn(val, &size, &ptr, fname++, 1);
 505
 506 val = string_catn(val, &size, &ptr, US"?=", 2);
 507 val[*len = ptr] = '\0';
 508 return val;
 509 }
 510
 511
 512 int
 513 mime_acl_check(uschar *acl, FILE *f, struct mime_boundary_context *context,
 514     uschar **user_msgptr, uschar **log_msgptr)
 515 {
 516 int rc = OK;
 517 uschar * header = NULL;
 518 struct mime_boundary_context nested_context;
 519
 520 /* reserve a line buffer to work in */
 521 header = store_get(MIME_MAX_HEADER_SIZE+1);
 522
 523 /* Not actually used at the moment, but will be vital to fixing
 524  * some RFC 2046 nonconformance later... */
 525 nested_context.parent = context;
 526
 527 /* loop through parts */
 528 while(1)
 529   {
 530   /* reset all per-part mime variables */
 531   mime_vars_reset();
 532
 533   /* If boundary is null, we assume that *f is positioned on the start of
 534   headers (for example, at the very beginning of a message.  If a boundary is
 535   given, we must first advance to it to reach the start of the next header
 536   block.  */
 537
 538   /* NOTE -- there's an error here -- RFC2046 specifically says to
 539    * check for outer boundaries.  This code doesn't do that, and
 540    * I haven't fixed this.
 541    *
 542    * (I have moved partway towards adding support, however, by adding
 543    * a "parent" field to my new boundary-context structure.)
 544    */
 545   if (context) for (;;)
 546     {
 547     if (!fgets(CS header, MIME_MAX_HEADER_SIZE, f))
 548       {
 549       /* Hit EOF or read error. Ugh. */
 550       DEBUG(D_acl) debug_printf("MIME: Hit EOF ...\n");
 551       return rc;
 552       }
 553
 554     /* boundary line must start with 2 dashes */
 555     if (  Ustrncmp(header, "--", 2) == 0
 556        && Ustrncmp(header+2, context->boundary, Ustrlen(context->boundary)) == 0
 557        )
 558       {                 /* found boundary */
 559       if (Ustrncmp((header+2+Ustrlen(context->boundary)), "--", 2) == 0)
 560         {
 561         /* END boundary found */
 562         DEBUG(D_acl) debug_printf("MIME: End boundary found %s\n",
 563           context->boundary);
 564         return rc;
 565         }
 566
 567       DEBUG(D_acl) debug_printf("MIME: Next part with boundary %s\n",
 568         context->boundary);
 569       break;
 570       }
 571     }
 572
 573   /* parse headers, set up expansion variables */
 574   while (mime_get_header(f, header))
 575     {
 576     struct mime_header * mh;
 577
 578     /* look for interesting headers */
 579     for (mh = mime_header_list;
 580          mh < mime_header_list + mime_header_list_size;
 581          mh++) if (strncmpic(mh->name, header, mh->namelen) == 0)
 582       {
 583       uschar * p = header + mh->namelen;
 584       uschar * q;
 585
 586       /* grab the value (normalize to lower case)
 587       and copy to its corresponding expansion variable */
 588
 589       for (q = p; *q != ';' && *q; q++) ;
 590       *mh->value = string_copynlc(p, q-p);
 591       DEBUG(D_acl) debug_printf("MIME: found %s header, value is '%s'\n",
 592         mh->name, *mh->value);
 593
 594       if (*(p = q)) p++;                        /* jump past the ; */
 595
 596         {
 597         uschar * mime_fname = NULL;
 598         uschar * mime_fname_rfc2231 = NULL;
 599         uschar * mime_filename_charset = NULL;
 600         BOOL decoding_failed = FALSE;
 601
 602         /* grab all param=value tags on the remaining line,
 603         check if they are interesting */
 604
 605         while (*p)
 606           {
 607           mime_parameter * mp;
 608
 609           DEBUG(D_acl) debug_printf("MIME:   considering paramlist '%s'\n", p);
 610
 611           if (  !mime_filename
 612              && strncmpic(CUS"content-disposition:", header, 20) == 0
 613              && strncmpic(CUS"filename*", p, 9) == 0
 614              )
 615             {                                   /* RFC 2231 filename */
 616             uschar * q;
 617
 618             /* find value of the filename */
 619             p += 9;
 620             while(*p != '=' && *p) p++;
 621             if (*p) p++;                        /* p is filename or NUL */
 622             q = mime_param_val(&p);             /* p now trailing ; or NUL */
 623
 624             if (q && *q)
 625               {
 626               uschar * temp_string, * err_msg;
 627               int slen;
 628
 629               /* build up an un-decoded filename over successive
 630               filename*= parameters (for use when 2047 decode fails) */
 631
 632               mime_fname_rfc2231 = string_sprintf("%#s%s",
 633                 mime_fname_rfc2231, q);
 634
 635               if (!decoding_failed)
 636                 {
 637                 int size;
 638                 if (!mime_filename_charset)
 639                   {
 640                   uschar * s = q;
 641
 642                   /* look for a ' in the "filename" */
 643                   while(*s != '\'' && *s) s++;  /* s is 1st ' or NUL */
 644
 645                   if ((size = s-q) > 0)
 646                     mime_filename_charset = string_copyn(q, size);
 647
 648                   if (*(p = s)) p++;
 649                   while(*p == '\'') p++;        /* p is after 2nd ' */
 650                   }
 651                 else
 652                   p = q;
 653
 654                 DEBUG(D_acl) debug_printf("MIME:    charset %s fname '%s'\n",
 655                   mime_filename_charset ? mime_filename_charset : US"<NULL>", p);
 656
 657                 temp_string = rfc2231_to_2047(p, mime_filename_charset, &slen);
 658                 DEBUG(D_acl) debug_printf("MIME:    2047-name %s\n", temp_string);
 659
 660                 temp_string = rfc2047_decode(temp_string, FALSE, NULL, ' ',
 661                   NULL, &err_msg);
 662                 DEBUG(D_acl) debug_printf("MIME:    plain-name %s\n", temp_string);
 663
 664                 size = Ustrlen(temp_string);
 665
 666                 if (size == slen)
 667                   decoding_failed = TRUE;
 668                 else
 669                   /* build up a decoded filename over successive
 670                   filename*= parameters */
 671
 672                   mime_filename = mime_fname = mime_fname
 673                     ? string_sprintf("%s%s", mime_fname, temp_string)
 674                     : temp_string;
 675                 }
 676               }
 677             }
 678
 679           else
 680             /* look for interesting parameters */
 681             for (mp = mime_parameter_list;
 682                  mp < mime_parameter_list + nelem(mime_parameter_list);
 683                  mp++
 684                 ) if (strncmpic(mp->name, p, mp->namelen) == 0)
 685               {
 686               uschar * q;
 687               uschar * dummy_errstr;
 688
 689               /* grab the value and copy to its expansion variable */
 690               p += mp->namelen;
 691               q = mime_param_val(&p);           /* p now trailing ; or NUL */
 692
 693               *mp->value = q && *q
 694                 ? rfc2047_decode(q, check_rfc2047_length, NULL, 32, NULL,
 695                     &dummy_errstr)
 696                 : NULL;
 697               DEBUG(D_acl) debug_printf(
 698                 "MIME:  found %s parameter in %s header, value '%s'\n",
 699                 mp->name, mh->name, *mp->value);
 700
 701               break;                    /* done matching param names */
 702               }
 703
 704
 705           /* There is something, but not one of our interesting parameters.
 706              Advance past the next semicolon */
 707           p = mime_next_semicolon(p);
 708           if (*p) p++;
 709           }                             /* param scan on line */
 710
 711         if (strncmpic(CUS"content-disposition:", header, 20) == 0)
 712           {
 713           if (decoding_failed) mime_filename = mime_fname_rfc2231;
 714
 715           DEBUG(D_acl) debug_printf(
 716             "MIME:  found %s parameter in %s header, value is '%s'\n",
 717             "filename", mh->name, mime_filename);
 718           }
 719         }
 720       }
 721     }
 722
 723   /* set additional flag variables (easier access) */
 724   if (  mime_content_type
 725      && Ustrncmp(mime_content_type,"multipart",9) == 0
 726      )
 727     mime_is_multipart = 1;
 728
 729   /* Make a copy of the boundary pointer.
 730      Required since mime_boundary is global
 731      and can be overwritten further down in recursion */
 732   nested_context.boundary = mime_boundary;
 733
 734   /* raise global counter */
 735   mime_part_count++;
 736
 737   /* copy current file handle to global variable */
 738   mime_stream = f;
 739   mime_current_boundary = context ? context->boundary : 0;
 740
 741   /* Note the context */
 742   mime_is_coverletter = !(context && context->context == MBC_ATTACHMENT);
 743
 744   /* call ACL handling function */
 745   rc = acl_check(ACL_WHERE_MIME, NULL, acl, user_msgptr, log_msgptr);
 746
 747   mime_stream = NULL;
 748   mime_current_boundary = NULL;
 749
 750   if (rc != OK) break;
 751
 752   /* If we have a multipart entity and a boundary, go recursive */
 753   if ( (mime_content_type != NULL) &&
 754        (nested_context.boundary != NULL) &&
 755        (Ustrncmp(mime_content_type,"multipart",9) == 0) )
 756     {
 757     DEBUG(D_acl)
 758       debug_printf("MIME: Entering multipart recursion, boundary '%s'\n",
 759         nested_context.boundary);
 760
 761     nested_context.context =
 762       context && context->context == MBC_ATTACHMENT
 763       ? MBC_ATTACHMENT
 764       :    Ustrcmp(mime_content_type,"multipart/alternative") == 0
 765         || Ustrcmp(mime_content_type,"multipart/related") == 0
 766       ? MBC_COVERLETTER_ALL
 767       : MBC_COVERLETTER_ONESHOT;
 768
 769     rc = mime_acl_check(acl, f, &nested_context, user_msgptr, log_msgptr);
 770     if (rc != OK) break;
 771     }
 772   else if ( (mime_content_type != NULL) &&
 773           (Ustrncmp(mime_content_type,"message/rfc822",14) == 0) )
 774     {
 775     const uschar *rfc822name = NULL;
 776     uschar filename[2048];
 777     int file_nr = 0;
 778     int result = 0;
 779
 780     /* must find first free sequential filename */
 781     do
 782       {
 783       struct stat mystat;
 784       (void)string_format(filename, 2048,
 785         "%s/scan/%s/__rfc822_%05u", spool_directory, message_id, file_nr++);
 786       /* security break */
 787       if (file_nr >= 128)
 788         goto NO_RFC822;
 789       result = stat(CS filename,&mystat);
 790       } while (result != -1);
 791
 792     rfc822name = filename;
 793
 794     /* decode RFC822 attachment */
 795     mime_decoded_filename = NULL;
 796     mime_stream = f;
 797     mime_current_boundary = context ? context->boundary : NULL;
 798     mime_decode(&rfc822name);
 799     mime_stream = NULL;
 800     mime_current_boundary = NULL;
 801     if (!mime_decoded_filename)         /* decoding failed */
 802       {
 803       log_write(0, LOG_MAIN,
 804            "MIME acl condition warning - could not decode RFC822 MIME part to file.");
 805       rc = DEFER;
 806       goto out;
 807       }
 808     mime_decoded_filename = NULL;
 809     }
 810
 811 NO_RFC822:
 812   /* If the boundary of this instance is NULL, we are finished here */
 813   if (!context) break;
 814
 815   if (context->context == MBC_COVERLETTER_ONESHOT)
 816     context->context = MBC_ATTACHMENT;
 817   }
 818
 819 out:
 820 mime_vars_reset();
 821 return rc;
 822 }
 823
 824 #endif  /*WITH_CONTENT_SCAN*/
 825
 826 /* vi: sw ai sw=2
 827 */