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