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