src/src/demime.c

   1 /* $Cambridge: exim/src/src/demime.c,v 1.5 2005/05/24 08:15:02 tom Exp $ */
   2
   3 /*************************************************
   4 *     Exim - an Internet mail transport agent    *
   5 *************************************************/
   6
   7 /* Copyright (c) Tom Kistner <tom@duncanthrax.net> 2003-???? */
   8 /* License: GPL */
   9
  10 /* Code for unpacking MIME containers. Called from acl.c. */
  11
  12 #include "exim.h"
  13 #ifdef WITH_OLD_DEMIME
  14
  15 #include "demime.h"
  16
  17 uschar demime_reason_buffer[1024];
  18 struct file_extension *file_extensions = NULL;
  19
  20 int demime(uschar **listptr) {
  21   int sep = 0;
  22   uschar *list = *listptr;
  23   uschar *option;
  24   uschar option_buffer[64];
  25   unsigned long mbox_size;
  26   FILE *mbox_file;
  27   uschar defer_error_buffer[1024];
  28   int demime_rc = 0;
  29
  30   /* reset found_extension variable */
  31   found_extension = NULL;
  32
  33   /* try to find 1st option */
  34   if ((option = string_nextinlist(&list, &sep,
  35                                   option_buffer,
  36                                   sizeof(option_buffer))) != NULL) {
  37
  38     /* parse 1st option */
  39     if ( (Ustrcmp(option,"false") == 0) || (Ustrcmp(option,"0") == 0) ) {
  40       /* explicitly no demimeing */
  41       return FAIL;
  42     };
  43   }
  44   else {
  45     /* no options -> no demimeing */
  46     return FAIL;
  47   };
  48
  49   /* make sure the eml mbox file is spooled up */
  50   mbox_file = spool_mbox(&mbox_size);
  51
  52   if (mbox_file == NULL) {
  53     /* error while spooling */
  54     log_write(0, LOG_MAIN|LOG_PANIC,
  55            "demime acl condition: error while creating mbox spool file");
  56     return DEFER;
  57   };
  58
  59   /* call demimer if not already done earlier */
  60   if (!demime_ok)
  61     demime_rc = mime_demux(mbox_file, defer_error_buffer);
  62
  63   fclose(mbox_file);
  64
  65   if (demime_rc == DEFER) {
  66     /* temporary failure (DEFER => DEFER) */
  67     log_write(0, LOG_MAIN,
  68         "demime acl condition: %s", defer_error_buffer);
  69     return DEFER;
  70   };
  71
  72   /* set demime_ok to avoid unpacking again */
  73   demime_ok = 1;
  74
  75   /* check for file extensions, if there */
  76   while (option != NULL) {
  77     struct file_extension *this_extension = file_extensions;
  78
  79     /* Look for the wildcard. If it is found, we always return true.
  80     The user must then use a custom condition to evaluate demime_errorlevel */
  81     if (Ustrcmp(option,"*") == 0) {
  82       found_extension = NULL;
  83       return OK;
  84     };
  85
  86     /* loop thru extension list */
  87     while (this_extension != NULL) {
  88       if (strcmpic(option, this_extension->file_extension_string) == 0) {
  89         /* found one */
  90         found_extension = this_extension->file_extension_string;
  91         return OK;
  92       };
  93       this_extension = this_extension->next;
  94     };
  95
  96     /* grab next extension from option list */
  97     option = string_nextinlist(&list, &sep,
  98                                option_buffer,
  99                                sizeof(option_buffer));
 100   };
 101
 102   /* nothing found */
 103   return FAIL;
 104 }
 105
 106
 107 /*************************************************
 108 * small hex_str -> integer conversion function   *
 109 *************************************************/
 110
 111 /* needed for quoted-printable
 112 */
 113
 114 unsigned int mime_hstr_i(uschar *cptr) {
 115   unsigned int i, j = 0;
 116
 117   while (cptr && *cptr && isxdigit(*cptr)) {
 118     i = *cptr++ - '0';
 119     if (9 < i) i -= 7;
 120     j <<= 4;
 121     j |= (i & 0x0f);
 122   }
 123
 124   return(j);
 125 }
 126
 127
 128 /*************************************************
 129 * decode quoted-printable chars                  *
 130 *************************************************/
 131
 132 /* gets called when we hit a =
 133    returns: new pointer position
 134    result code in c:
 135           -2 - decode error
 136           -1 - soft line break, no char
 137            0-255 - char to write
 138 */
 139
 140 uschar *mime_decode_qp(uschar *qp_p,int *c) {
 141   uschar hex[] = {0,0,0};
 142   int nan = 0;
 143   uschar *initial_pos = qp_p;
 144
 145   /* advance one char */
 146   qp_p++;
 147
 148   REPEAT_FIRST:
 149   if ( (*qp_p == '\t') || (*qp_p == ' ') || (*qp_p == '\r') )  {
 150     /* tab or whitespace may follow
 151        just ignore it, but remember
 152        that this is not a valid hex
 153        encoding any more */
 154     nan = 1;
 155     qp_p++;
 156     goto REPEAT_FIRST;
 157   }
 158   else if ( (('0' <= *qp_p) && (*qp_p <= '9')) || (('A' <= *qp_p) && (*qp_p <= 'F'))  || (('a' <= *qp_p) && (*qp_p <= 'f')) ) {
 159     /* this is a valid hex char, if nan is unset */
 160     if (nan) {
 161       /* this is illegal */
 162       *c = -2;
 163       return initial_pos;
 164     }
 165     else {
 166       hex[0] = *qp_p;
 167       qp_p++;
 168     };
 169   }
 170   else if (*qp_p == '\n') {
 171     /* hit soft line break already, continue */
 172     *c = -1;
 173     return qp_p;
 174   }
 175   else {
 176     /* illegal char here */
 177     *c = -2;
 178     return initial_pos;
 179   };
 180
 181   if ( (('0' <= *qp_p) && (*qp_p <= '9')) || (('A' <= *qp_p) && (*qp_p <= 'F')) || (('a' <= *qp_p) && (*qp_p <= 'f')) ) {
 182     if (hex[0] > 0) {
 183       hex[1] = *qp_p;
 184       /* do hex conversion */
 185       *c = mime_hstr_i(hex);
 186       qp_p++;
 187       return qp_p;
 188     }
 189     else {
 190       /* huh ? */
 191       *c = -2;
 192       return initial_pos;
 193     };
 194   }
 195   else {
 196     /* illegal char */
 197     *c = -2;
 198     return initial_pos;
 199   };
 200
 201 }
 202
 203
 204 /*************************************************
 205 * open new dump file                             *
 206 *************************************************/
 207
 208 /* open new dump file
 209    returns: -2 soft error
 210             or file #, FILE * in f
 211 */
 212
 213 int mime_get_dump_file(uschar *extension, FILE **f, uschar *info) {
 214   uschar file_name[1024];
 215   int result;
 216   unsigned int file_nr;
 217   uschar default_extension[] = ".com";
 218   uschar *p;
 219
 220   if (extension == NULL)
 221     extension = default_extension;
 222
 223   /* scan the proposed extension.
 224      if it is longer than 4 chars, or
 225      contains exotic chars, use the default extension */
 226
 227 /*  if (Ustrlen(extension) > 4) {
 228     extension = default_extension;
 229   };
 230 */
 231
 232   p = extension+1;
 233
 234   while (*p != 0) {
 235     *p = (uschar)tolower((uschar)*p);
 236     if ( (*p < 97) || (*p > 122) ) {
 237       extension = default_extension;
 238       break;
 239     };
 240     p++;
 241   };
 242
 243   /* find a new file to write to */
 244   file_nr = 0;
 245   do {
 246     struct stat mystat;
 247
 248     snprintf(CS file_name,1024,"%s/scan/%s/%s-%05u%s",spool_directory,message_id,message_id,file_nr,extension);
 249     file_nr++;
 250     if (file_nr >= MIME_SANITY_MAX_DUMP_FILES) {
 251       /* max parts reached */
 252       mime_trigger_error(MIME_ERRORLEVEL_TOO_MANY_PARTS);
 253       break;
 254     };
 255     result = stat(CS file_name,&mystat);
 256   }
 257   while(result != -1);
 258
 259   *f = fopen(CS file_name,"w+");
 260   if (*f == NULL) {
 261     /* cannot open new dump file, disk full ? -> soft error */
 262     snprintf(CS info, 1024,"unable to open dump file");
 263     return -2;
 264   };
 265
 266   return file_nr;
 267 }
 268
 269
 270 /*************************************************
 271 * Find a string in a mime header                 *
 272 *************************************************/
 273
 274 /* Find a string in a mime header, and optionally fill in
 275    the value associated with it into *value
 276
 277    returns: 0 - nothing found
 278             1 - found param
 279             2 - found param + value
 280 */
 281
 282 int mime_header_find(uschar *header, uschar *param, uschar **value) {
 283   uschar *needle;
 284
 285   needle = strstric(header,param,FALSE);
 286   if (needle != NULL) {
 287     if (value != NULL) {
 288       needle += Ustrlen(param);
 289       if (*needle == '=') {
 290         uschar *value_start;
 291         uschar *value_end;
 292
 293         value_start = needle + 1;
 294         value_end = strstric(value_start,US";",FALSE);
 295         if (value_end != NULL) {
 296           /* allocate mem for value */
 297           *value = (uschar *)malloc((value_end - value_start)+1);
 298           if (*value == NULL)
 299             return 0;
 300
 301           Ustrncpy(*value,value_start,(value_end - value_start));
 302           (*value)[(value_end - value_start)] = '\0';
 303           return 2;
 304         };
 305       };
 306     };
 307     return 1;
 308   };
 309   return 0;
 310 }
 311
 312
 313 /*************************************************
 314 * Read a line of MIME input                      *
 315 *************************************************/
 316 /* returns status code, one of
 317    MIME_READ_LINE_EOF 0
 318    MIME_READ_LINE_OK 1
 319    MIME_READ_LINE_OVERFLOW 2
 320
 321    In header mode, the line will be "cooked".
 322 */
 323
 324 int mime_read_line(FILE *f, int mime_demux_mode, uschar *buffer, long *num_copied) {
 325   int c = EOF;
 326   int done = 0;
 327   int header_value_mode = 0;
 328   int header_open_brackets = 0;
 329
 330   *num_copied = 0;
 331
 332   while(!done) {
 333
 334     c = fgetc(f);
 335     if (c == EOF) break;
 336
 337     /* --------- header mode -------------- */
 338     if (mime_demux_mode == MIME_DEMUX_MODE_MIME_HEADERS) {
 339
 340       /* always skip CRs */
 341       if (c == '\r') continue;
 342
 343       if (c == '\n') {
 344         if ((*num_copied) > 0) {
 345           /* look if next char is '\t' or ' ' */
 346           c = fgetc(f);
 347           if (c == EOF) break;
 348           if ( (c == '\t') || (c == ' ') ) continue;
 349           ungetc(c,f);
 350         };
 351         /* end of the header, terminate with ';' */
 352         c = ';';
 353         done = 1;
 354       };
 355
 356       /* skip control characters */
 357       if (c < 32) continue;
 358
 359       /* skip whitespace + tabs */
 360       if ( (c == ' ') || (c == '\t') )
 361         continue;
 362
 363       if (header_value_mode) {
 364         /* --------- value mode ----------- */
 365         /* skip quotes */
 366         if (c == '"') continue;
 367
 368         /* leave value mode on ';' */
 369         if (c == ';') {
 370           header_value_mode = 0;
 371         };
 372         /* -------------------------------- */
 373       }
 374       else {
 375         /* -------- non-value mode -------- */
 376         if (c == '\\') {
 377           /* quote next char. can be used
 378           to escape brackets. */
 379           c = fgetc(f);
 380           if (c == EOF) break;
 381         }
 382         else if (c == '(') {
 383           header_open_brackets++;
 384           continue;
 385         }
 386         else if ((c == ')') && header_open_brackets) {
 387           header_open_brackets--;
 388           continue;
 389         }
 390         else if ( (c == '=') && !header_open_brackets ) {
 391           /* enter value mode */
 392           header_value_mode = 1;
 393         };
 394
 395         /* skip chars while we are in a comment */
 396         if (header_open_brackets > 0)
 397           continue;
 398         /* -------------------------------- */
 399       };
 400     }
 401     /* ------------------------------------ */
 402     else {
 403     /* ----------- non-header mode -------- */
 404       /* break on '\n' */
 405       if (c == '\n')
 406         done = 1;
 407     /* ------------------------------------ */
 408     };
 409
 410     /* copy the char to the buffer */
 411     buffer[*num_copied] = (uschar)c;
 412     /* raise counter */
 413     (*num_copied)++;
 414
 415     /* break if buffer is full */
 416     if (*num_copied > MIME_SANITY_MAX_LINE_LENGTH-1) {
 417       done = 1;
 418     };
 419   }
 420
 421   /* 0-terminate */
 422   buffer[*num_copied] = '\0';
 423
 424   if (*num_copied > MIME_SANITY_MAX_LINE_LENGTH-1)
 425     return MIME_READ_LINE_OVERFLOW;
 426   else
 427     if (c == EOF)
 428       return MIME_READ_LINE_EOF;
 429     else
 430       return MIME_READ_LINE_OK;
 431 }
 432
 433
 434 /*************************************************
 435 * Check for a MIME boundary                      *
 436 *************************************************/
 437
 438 /* returns: 0 - no boundary found
 439             1 - start boundary found
 440             2 - end boundary found
 441 */
 442
 443 int mime_check_boundary(uschar *line, struct boundary *boundaries) {
 444   struct boundary *thisboundary = boundaries;
 445   uschar workbuf[MIME_SANITY_MAX_LINE_LENGTH+1];
 446   unsigned int i,j=0;
 447
 448   /* check for '--' first */
 449   if (Ustrncmp(line,"--",2) == 0) {
 450
 451     /* strip tab and space */
 452     for (i = 2; i < Ustrlen(line); i++) {
 453       if ((line[i] != ' ') && (line[i] != '\t')) {
 454         workbuf[j] = line[i];
 455         j++;
 456       };
 457     };
 458     workbuf[j+1]='\0';
 459
 460     while(thisboundary != NULL) {
 461       if (Ustrncmp(workbuf,thisboundary->boundary_string,Ustrlen(thisboundary->boundary_string)) == 0) {
 462         if (Ustrncmp(&workbuf[Ustrlen(thisboundary->boundary_string)],"--",2) == 0) {
 463           /* final boundary found */
 464           return 2;
 465         };
 466         return 1;
 467       };
 468       thisboundary = thisboundary->next;
 469     };
 470   };
 471
 472   return 0;
 473 }
 474
 475
 476 /*************************************************
 477 * Check for start of a UUENCODE block            *
 478 *************************************************/
 479
 480 /* returns 0 for no hit,
 481            >0 for hit
 482 */
 483
 484 int mime_check_uu_start(uschar *line, uschar *uu_file_extension, int *has_tnef) {
 485
 486   if ( (strncmpic(line,US"begin ",6) == 0)) {
 487     uschar *uu_filename = &line[6];
 488
 489     /* skip perms, if present */
 490     Ustrtoul(&line[6],&uu_filename,10);
 491
 492     /* advance one char */
 493     uu_filename++;
 494
 495     /* This should be the filename.
 496     Check if winmail.dat is present,
 497     which indicates TNEF. */
 498     if (strncmpic(uu_filename,US"winmail.dat",11) == 0) {
 499       *has_tnef = 1;
 500     };
 501
 502     /* reverse to dot if present,
 503     copy up to 4 chars for the extension */
 504     if (Ustrrchr(uu_filename,'.') != NULL)
 505       uu_filename = Ustrrchr(uu_filename,'.');
 506
 507     return sscanf(CS uu_filename, "%4[.0-9A-Za-z]",CS uu_file_extension);
 508   }
 509   else {
 510     /* nothing found */
 511     return 0;
 512   };
 513 }
 514
 515
 516 /*************************************************
 517 * Decode a uu line                               *
 518 *************************************************/
 519
 520 /* returns number of decoded bytes
 521          -2 for soft errors
 522 */
 523
 524 int warned_about_uudec_line_sanity_1 = 0;
 525 int warned_about_uudec_line_sanity_2 = 0;
 526 long uu_decode_line(uschar *line, uschar **data, long line_len, uschar *info) {
 527   uschar *p;
 528   long num_decoded = 0;
 529   uschar tmp_c;
 530   uschar *work;
 531   int uu_decoded_line_len, uu_encoded_line_len;
 532
 533   /* allocate memory for data and work buffer */
 534   *data = (uschar *)malloc(line_len);
 535   if (*data == NULL) {
 536     snprintf(CS info, 1024,"unable to allocate %lu bytes",line_len);
 537     return -2;
 538   };
 539
 540   work = (uschar *)malloc(line_len);
 541   if (work == NULL) {
 542     snprintf(CS info, 1024,"unable to allocate %lu bytes",line_len);
 543     return -2;
 544   };
 545
 546   memcpy(work,line,line_len);
 547
 548   /* First char is line length
 549   This is microsofts way of getting it. Scary. */
 550   if (work[0] < 32) {
 551     /* ignore this line */
 552     return 0;
 553   }
 554   else {
 555     uu_decoded_line_len = uudec[work[0]];
 556   };
 557
 558   p = &work[1];
 559
 560   while (*p > 32) {
 561     *p = uudec[*p];
 562     p++;
 563   };
 564
 565   uu_encoded_line_len = (p - &work[1]);
 566   p = &work[1];
 567
 568   /* check that resulting line length is a multiple of 4 */
 569   if ( ( uu_encoded_line_len % 4 ) != 0) {
 570     if (!warned_about_uudec_line_sanity_1) {
 571       mime_trigger_error(MIME_ERRORLEVEL_UU_MISALIGNED);
 572       warned_about_uudec_line_sanity_1 = 1;
 573     };
 574     return -1;
 575   };
 576
 577   /* check that the line length matches */
 578   if ( ( (((uu_encoded_line_len/4)*3)-2) > uu_decoded_line_len ) || (((uu_encoded_line_len/4)*3) < uu_decoded_line_len) ) {
 579     if (!warned_about_uudec_line_sanity_2) {
 580       mime_trigger_error(MIME_ERRORLEVEL_UU_LINE_LENGTH);
 581       warned_about_uudec_line_sanity_2 = 1;
 582     };
 583     return -1;
 584   };
 585
 586   while ( ((p - &work[1]) < uu_encoded_line_len) && (num_decoded < uu_decoded_line_len)) {
 587
 588     /* byte 0 ---------------------- */
 589     if ((p - &work[1] + 1) >= uu_encoded_line_len) {
 590       return 0;
 591     }
 592
 593     (*data)[num_decoded] = *p;
 594     (*data)[num_decoded] <<= 2;
 595
 596     tmp_c = *(p+1);
 597     tmp_c >>= 4;
 598     (*data)[num_decoded] |= tmp_c;
 599
 600     num_decoded++;
 601     p++;
 602
 603     /* byte 1 ---------------------- */
 604     if ((p - &work[1] + 1) >= uu_encoded_line_len) {
 605       return 0;
 606     }
 607
 608     (*data)[num_decoded] = *p;
 609     (*data)[num_decoded] <<= 4;
 610
 611     tmp_c = *(p+1);
 612     tmp_c >>= 2;
 613     (*data)[num_decoded] |= tmp_c;
 614
 615     num_decoded++;
 616     p++;
 617
 618     /* byte 2 ---------------------- */
 619     if ((p - &work[1] + 1) >= uu_encoded_line_len) {
 620       return 0;
 621     }
 622
 623     (*data)[num_decoded] = *p;
 624     (*data)[num_decoded] <<= 6;
 625
 626     (*data)[num_decoded] |= *(p+1);
 627
 628     num_decoded++;
 629     p+=2;
 630
 631   };
 632
 633   return uu_decoded_line_len;
 634 }
 635
 636
 637 /*************************************************
 638 * Decode a b64 or qp line                        *
 639 *************************************************/
 640
 641 /* returns number of decoded bytes
 642          -1 for hard errors
 643          -2 for soft errors
 644 */
 645
 646 int warned_about_b64_line_length = 0;
 647 int warned_about_b64_line_sanity = 0;
 648 int warned_about_b64_illegal_char = 0;
 649 int warned_about_qp_line_sanity = 0;
 650 long mime_decode_line(int mime_demux_mode,uschar *line, uschar **data, long max_data_len, uschar *info) {
 651   uschar *p;
 652   long num_decoded = 0;
 653   int offset = 0;
 654   uschar tmp_c;
 655
 656   /* allocate memory for data */
 657   *data = (uschar *)malloc(max_data_len);
 658   if (*data == NULL) {
 659     snprintf(CS info, 1024,"unable to allocate %lu bytes",max_data_len);
 660     return -2;
 661   };
 662
 663   if (mime_demux_mode == MIME_DEMUX_MODE_BASE64) {
 664     /* ---------------------------------------------- */
 665
 666     /* NULL out trailing '\r' and '\n' chars */
 667     while (Ustrrchr(line,'\r') != NULL) {
 668       *(Ustrrchr(line,'\r')) = '\0';
 669     };
 670     while (Ustrrchr(line,'\n') != NULL) {
 671       *(Ustrrchr(line,'\n')) = '\0';
 672     };
 673
 674     /* check maximum base 64 line length */
 675     if (Ustrlen(line) > MIME_SANITY_MAX_B64_LINE_LENGTH ) {
 676       if (!warned_about_b64_line_length) {
 677         mime_trigger_error(MIME_ERRORLEVEL_B64_LINE_LENGTH);
 678         warned_about_b64_line_length = 1;
 679       };
 680     };
 681
 682     p = line;
 683     offset = 0;
 684     while (*(p+offset) != '\0') {
 685       /* hit illegal char ? */
 686       if (b64[*(p+offset)] == 128) {
 687         if (!warned_about_b64_illegal_char) {
 688           mime_trigger_error(MIME_ERRORLEVEL_B64_ILLEGAL_CHAR);
 689           warned_about_b64_illegal_char = 1;
 690         };
 691         offset++;
 692       }
 693       else {
 694         *p = b64[*(p+offset)];
 695         p++;
 696       };
 697     };
 698     *p = 255;
 699
 700     /* check that resulting line length is a multiple of 4 */
 701     if ( ( (p - &line[0]) % 4 ) != 0) {
 702       if (!warned_about_b64_line_sanity) {
 703         mime_trigger_error(MIME_ERRORLEVEL_B64_MISALIGNED);
 704         warned_about_b64_line_sanity = 1;
 705       };
 706     };
 707
 708     /* line is translated, start bit shifting */
 709     p = line;
 710     num_decoded = 0;
 711
 712     while(*p != 255) {
 713
 714       /* byte 0 ---------------------- */
 715       if (*(p+1) == 255) {
 716         break;
 717       }
 718
 719       (*data)[num_decoded] = *p;
 720       (*data)[num_decoded] <<= 2;
 721
 722       tmp_c = *(p+1);
 723       tmp_c >>= 4;
 724       (*data)[num_decoded] |= tmp_c;
 725
 726       num_decoded++;
 727       p++;
 728
 729       /* byte 1 ---------------------- */
 730       if (*(p+1) == 255) {
 731         break;
 732       }
 733
 734       (*data)[num_decoded] = *p;
 735       (*data)[num_decoded] <<= 4;
 736
 737       tmp_c = *(p+1);
 738       tmp_c >>= 2;
 739       (*data)[num_decoded] |= tmp_c;
 740
 741       num_decoded++;
 742       p++;
 743
 744       /* byte 2 ---------------------- */
 745       if (*(p+1) == 255) {
 746         break;
 747       }
 748
 749       (*data)[num_decoded] = *p;
 750       (*data)[num_decoded] <<= 6;
 751
 752       (*data)[num_decoded] |= *(p+1);
 753
 754       num_decoded++;
 755       p+=2;
 756
 757     };
 758     return num_decoded;
 759     /* ---------------------------------------------- */
 760   }
 761   else if (mime_demux_mode == MIME_DEMUX_MODE_QP) {
 762     /* ---------------------------------------------- */
 763     p = line;
 764
 765     while (*p != 0) {
 766       if (*p == '=') {
 767         int decode_qp_result;
 768
 769         p = mime_decode_qp(p,&decode_qp_result);
 770
 771         if (decode_qp_result == -2) {
 772           /* Error from decoder. p is unchanged. */
 773           if (!warned_about_qp_line_sanity) {
 774             mime_trigger_error(MIME_ERRORLEVEL_QP_ILLEGAL_CHAR);
 775             warned_about_qp_line_sanity = 1;
 776           };
 777           (*data)[num_decoded] = '=';
 778           num_decoded++;
 779           p++;
 780         }
 781         else if (decode_qp_result == -1) {
 782           /* End of the line with soft line break.
 783           Bail out. */
 784           goto QP_RETURN;
 785         }
 786         else if (decode_qp_result >= 0) {
 787           (*data)[num_decoded] = decode_qp_result;
 788           num_decoded++;
 789         };
 790       }
 791       else {
 792         (*data)[num_decoded] = *p;
 793         num_decoded++;
 794         p++;
 795       };
 796     };
 797     QP_RETURN:
 798     return num_decoded;
 799     /* ---------------------------------------------- */
 800   };
 801
 802   return 0;
 803 }
 804
 805
 806
 807 /*************************************************
 808 * Log demime errors and set mime error level     *
 809 *************************************************/
 810
 811 /* This sets the global demime_reason expansion
 812 variable and the demime_errorlevel gauge. */
 813
 814 void mime_trigger_error(int level, uschar *format, ...) {
 815   char *f;
 816   va_list ap;
 817
 818   if( (f = malloc(16384+23)) != NULL ) {
 819     /* first log the incident */
 820     sprintf(f,"demime acl condition: ");
 821     f+=22;
 822     va_start(ap, format);
 823     vsnprintf(f, 16383,(char *)format, ap);
 824     va_end(ap);
 825     f-=22;
 826     log_write(0, LOG_MAIN, f);
 827     /* then copy to demime_reason_buffer if new
 828     level is greater than old level */
 829     if (level > demime_errorlevel) {
 830       demime_errorlevel = level;
 831       Ustrcpy(demime_reason_buffer, US f);
 832       demime_reason = demime_reason_buffer;
 833     };
 834     free(f);
 835   };
 836 }
 837
 838 /*************************************************
 839 * Demultiplex MIME stream.                       *
 840 *************************************************/
 841
 842 /* We can handle BASE64, QUOTED-PRINTABLE, and UUENCODE.
 843  UUENCODE does not need to have a proper
 844  transfer-encoding header, we detect it with "begin"
 845
 846  This function will report human parsable errors in
 847  *info.
 848
 849  returns DEFER -> soft error (see *info)
 850          OK    -> EOF hit, all ok
 851 */
 852
 853 int mime_demux(FILE *f, uschar *info) {
 854   int mime_demux_mode = MIME_DEMUX_MODE_MIME_HEADERS;
 855   int uu_mode = MIME_UU_MODE_OFF;
 856   FILE *mime_dump_file = NULL;
 857   FILE *uu_dump_file = NULL;
 858   uschar *line;
 859   int mime_read_line_status = MIME_READ_LINE_OK;
 860   long line_len;
 861   struct boundary *boundaries = NULL;
 862   struct mime_part mime_part_p;
 863   int has_tnef = 0;
 864   int has_rfc822 = 0;
 865
 866   /* allocate room for our linebuffer */
 867   line = (uschar *)malloc(MIME_SANITY_MAX_LINE_LENGTH);
 868   if (line == NULL) {
 869     snprintf(CS info, 1024,"unable to allocate %u bytes",MIME_SANITY_MAX_LINE_LENGTH);
 870     return DEFER;
 871   };
 872
 873   /* clear MIME header structure */
 874   memset(&mime_part_p,0,sizeof(mime_part));
 875
 876   /* ----------------------- start demux loop --------------------- */
 877   while (mime_read_line_status == MIME_READ_LINE_OK) {
 878
 879     /* read a line of input. Depending on the mode we are in,
 880     the returned format will differ. */
 881     mime_read_line_status = mime_read_line(f,mime_demux_mode,line,&line_len);
 882
 883     if (mime_read_line_status == MIME_READ_LINE_OVERFLOW) {
 884       mime_trigger_error(MIME_ERRORLEVEL_LONG_LINE);
 885       /* despite the error, continue  .. */
 886       mime_read_line_status = MIME_READ_LINE_OK;
 887       continue;
 888     }
 889     else if (mime_read_line_status == MIME_READ_LINE_EOF) {
 890       break;
 891     };
 892
 893     if (mime_demux_mode == MIME_DEMUX_MODE_MIME_HEADERS) {
 894       /* -------------- header mode --------------------- */
 895
 896       /* Check for an empty line, which is the end of the headers.
 897        In HEADER mode, the line is returned "cooked", with the
 898        final '\n' replaced by a ';' */
 899       if (line_len == 1) {
 900         int tmp;
 901
 902         /* We have reached the end of the headers. Start decoding
 903         with the collected settings. */
 904         if (mime_part_p.seen_content_transfer_encoding > 1) {
 905           mime_demux_mode = mime_part_p.seen_content_transfer_encoding;
 906         }
 907         else {
 908           /* default to plain mode if no specific encoding type found */
 909           mime_demux_mode = MIME_DEMUX_MODE_PLAIN;
 910         };
 911
 912         /* open new dump file */
 913         tmp = mime_get_dump_file(mime_part_p.extension, &mime_dump_file, info);
 914         if (tmp < 0) {
 915           return DEFER;
 916         };
 917
 918         /* clear out mime_part */
 919         memset(&mime_part_p,0,sizeof(mime_part));
 920       }
 921       else {
 922         /* Another header to check for file extensions,
 923         encoding type and boundaries */
 924         if (strncmpic(US"content-type:",line,Ustrlen("content-type:")) == 0) {
 925           /* ---------------------------- Content-Type header ------------------------------- */
 926           uschar *value = line;
 927
 928           /* check for message/partial MIME type and reject it */
 929           if (mime_header_find(line,US"message/partial",NULL) > 0)
 930             mime_trigger_error(MIME_ERRORLEVEL_MESSAGE_PARTIAL);
 931
 932           /* check for TNEF content type, remember to unpack TNEF later. */
 933           if (mime_header_find(line,US"application/ms-tnef",NULL) > 0)
 934             has_tnef = 1;
 935
 936           /* check for message/rfcxxx attachments */
 937           if (mime_header_find(line,US"message/rfc822",NULL) > 0)
 938             has_rfc822 = 1;
 939
 940           /* find the file extension, but do not fill it in
 941           it is already set, since content-disposition has
 942           precedence. */
 943           if (mime_part_p.extension == NULL) {
 944             if (mime_header_find(line,US"name",&value) == 2) {
 945               if (Ustrlen(value) > MIME_SANITY_MAX_FILENAME)
 946                 mime_trigger_error(MIME_ERRORLEVEL_FILENAME_LENGTH);
 947               mime_part_p.extension = value;
 948               mime_part_p.extension = Ustrrchr(value,'.');
 949               if (mime_part_p.extension == NULL) {
 950                 /* file without extension, setting
 951                 NULL will use the default extension later */
 952                 mime_part_p.extension = NULL;
 953               }
 954               else {
 955                 struct file_extension *this_extension =
 956                   (struct file_extension *)malloc(sizeof(file_extension));
 957
 958                 this_extension->file_extension_string =
 959                   (uschar *)malloc(Ustrlen(mime_part_p.extension)+1);
 960                 Ustrcpy(this_extension->file_extension_string,
 961                         mime_part_p.extension+1);
 962                 this_extension->next = file_extensions;
 963                 file_extensions = this_extension;
 964               };
 965             };
 966           };
 967
 968           /* find a boundary and add it to the list, if present */
 969           value = line;
 970           if (mime_header_find(line,US"boundary",&value) == 2) {
 971             struct boundary *thisboundary;
 972
 973             if (Ustrlen(value) > MIME_SANITY_MAX_BOUNDARY_LENGTH) {
 974               mime_trigger_error(MIME_ERRORLEVEL_BOUNDARY_LENGTH);
 975             }
 976             else {
 977               thisboundary = (struct boundary*)malloc(sizeof(boundary));
 978               thisboundary->next = boundaries;
 979               thisboundary->boundary_string = value;
 980               boundaries = thisboundary;
 981             };
 982           };
 983
 984           if (mime_part_p.seen_content_type == 0) {
 985             mime_part_p.seen_content_type = 1;
 986           }
 987           else {
 988             mime_trigger_error(MIME_ERRORLEVEL_DOUBLE_HEADERS);
 989           };
 990           /* ---------------------------------------------------------------------------- */
 991         }
 992         else if (strncmpic(US"content-transfer-encoding:",line,Ustrlen("content-transfer-encoding:")) == 0) {
 993           /* ---------------------------- Content-Transfer-Encoding header -------------- */
 994
 995          if (mime_part_p.seen_content_transfer_encoding == 0) {
 996             if (mime_header_find(line,US"base64",NULL) > 0) {
 997               mime_part_p.seen_content_transfer_encoding = MIME_DEMUX_MODE_BASE64;
 998             }
 999             else if (mime_header_find(line,US"quoted-printable",NULL) > 0) {
1000               mime_part_p.seen_content_transfer_encoding = MIME_DEMUX_MODE_QP;
1001             }
1002             else {
1003               mime_part_p.seen_content_transfer_encoding = MIME_DEMUX_MODE_PLAIN;
1004             };
1005           }
1006           else {
1007             mime_trigger_error(MIME_ERRORLEVEL_DOUBLE_HEADERS);
1008           };
1009           /* ---------------------------------------------------------------------------- */
1010         }
1011         else if (strncmpic(US"content-disposition:",line,Ustrlen("content-disposition:")) == 0) {
1012           /* ---------------------------- Content-Disposition header -------------------- */
1013           uschar *value = line;
1014
1015           if (mime_part_p.seen_content_disposition == 0) {
1016             mime_part_p.seen_content_disposition = 1;
1017
1018             if (mime_header_find(line,US"filename",&value) == 2) {
1019               if (Ustrlen(value) > MIME_SANITY_MAX_FILENAME)
1020                 mime_trigger_error(MIME_ERRORLEVEL_FILENAME_LENGTH);
1021               mime_part_p.extension = value;
1022               mime_part_p.extension = Ustrrchr(value,'.');
1023               if (mime_part_p.extension == NULL) {
1024                 /* file without extension, setting
1025                 NULL will use the default extension later */
1026                 mime_part_p.extension = NULL;
1027               }
1028               else {
1029                 struct file_extension *this_extension =
1030                   (struct file_extension *)malloc(sizeof(file_extension));
1031
1032                 this_extension->file_extension_string =
1033                   (uschar *)malloc(Ustrlen(mime_part_p.extension)+1);
1034                 Ustrcpy(this_extension->file_extension_string,
1035                         mime_part_p.extension+1);
1036                 this_extension->next = file_extensions;
1037                 file_extensions = this_extension;
1038               };
1039             };
1040           }
1041           else {
1042             mime_trigger_error(MIME_ERRORLEVEL_DOUBLE_HEADERS);
1043           };
1044           /* ---------------------------------------------------------------------------- */
1045         };
1046       };    /* End of header checks */
1047       /* ------------------------------------------------ */
1048     }
1049     else {
1050       /* -------------- non-header mode ----------------- */
1051       int tmp;
1052
1053       if (uu_mode == MIME_UU_MODE_OFF) {
1054         uschar uu_file_extension[5];
1055         /* We are not currently decoding UUENCODE
1056         Check for possible UUENCODE start tag. */
1057         if (mime_check_uu_start(line,uu_file_extension,&has_tnef)) {
1058           /* possible UUENCODING start detected.
1059           Set unconfirmed mode first. */
1060           uu_mode = MIME_UU_MODE_UNCONFIRMED;
1061           /* open new uu dump file */
1062           tmp = mime_get_dump_file(uu_file_extension, &uu_dump_file, info);
1063           if (tmp < 0) {
1064             free(line);
1065             return DEFER;
1066           };
1067         };
1068       }
1069       else {
1070         uschar *data;
1071         long data_len = 0;
1072
1073         if (uu_mode == MIME_UU_MODE_UNCONFIRMED) {
1074          /* We are in unconfirmed UUENCODE mode. */
1075
1076          data_len = uu_decode_line(line,&data,line_len,info);
1077
1078          if (data_len == -2) {
1079            /* temp error, turn off uudecode mode */
1080            if (uu_dump_file != NULL) {
1081             fclose(uu_dump_file); uu_dump_file = NULL;
1082            };
1083            uu_mode = MIME_UU_MODE_OFF;
1084            return DEFER;
1085          }
1086          else if (data_len == -1) {
1087            if (uu_dump_file != NULL) {
1088             fclose(uu_dump_file); uu_dump_file = NULL;
1089            };
1090            uu_mode = MIME_UU_MODE_OFF;
1091            data_len = 0;
1092          }
1093          else if (data_len > 0) {
1094            /* we have at least decoded a valid byte
1095            turn on confirmed mode */
1096            uu_mode = MIME_UU_MODE_CONFIRMED;
1097          };
1098         }
1099         else if (uu_mode == MIME_UU_MODE_CONFIRMED) {
1100           /* If we are in confirmed UU mode,
1101           check for single "end" tag on line */
1102           if ((strncmpic(line,US"end",3) == 0) && (line[3] < 32)) {
1103             if (uu_dump_file != NULL) {
1104               fclose(uu_dump_file); uu_dump_file = NULL;
1105             };
1106             uu_mode = MIME_UU_MODE_OFF;
1107           }
1108           else {
1109             data_len = uu_decode_line(line,&data,line_len,info);
1110             if (data_len == -2) {
1111                /* temp error, turn off uudecode mode */
1112                if (uu_dump_file != NULL) {
1113                  fclose(uu_dump_file); uu_dump_file = NULL;
1114                };
1115                uu_mode = MIME_UU_MODE_OFF;
1116                return DEFER;
1117              }
1118              else if (data_len == -1) {
1119                /* skip this line */
1120                data_len = 0;
1121              };
1122           };
1123         };
1124
1125         /* write data to dump file, if available */
1126         if (data_len > 0) {
1127           if (fwrite(data,1,data_len,uu_dump_file) < data_len) {
1128             /* short write */
1129             snprintf(CS info, 1024,"short write on uudecode dump file");
1130             free(line);
1131             return DEFER;
1132           };
1133         };
1134       };
1135
1136       if (mime_demux_mode != MIME_DEMUX_MODE_SCANNING) {
1137         /* Non-scanning and Non-header mode. That means
1138         we are currently decoding data to the dump
1139         file. */
1140
1141         /* Check for a known boundary. */
1142         tmp = mime_check_boundary(line,boundaries);
1143         if (tmp == 1) {
1144           /* We have hit a known start boundary.
1145           That will put us back in header mode. */
1146           mime_demux_mode = MIME_DEMUX_MODE_MIME_HEADERS;
1147           if (mime_dump_file != NULL) {
1148             /* if the attachment was a RFC822 message, recurse into it */
1149             if (has_rfc822) {
1150               has_rfc822 = 0;
1151               rewind(mime_dump_file);
1152               mime_demux(mime_dump_file,info);
1153             };
1154
1155             fclose(mime_dump_file); mime_dump_file = NULL;
1156           };
1157         }
1158         else if (tmp == 2) {
1159           /* We have hit a known end boundary.
1160           That puts us into scanning mode, which will end when we hit another known start boundary */
1161           mime_demux_mode = MIME_DEMUX_MODE_SCANNING;
1162           if (mime_dump_file != NULL) {
1163             /* if the attachment was a RFC822 message, recurse into it */
1164             if (has_rfc822) {
1165               has_rfc822 = 0;
1166               rewind(mime_dump_file);
1167               mime_demux(mime_dump_file,info);
1168             };
1169
1170             fclose(mime_dump_file); mime_dump_file = NULL;
1171           };
1172         }
1173         else {
1174           uschar *data;
1175           long data_len = 0;
1176
1177           /* decode the line with the appropriate method */
1178           if (mime_demux_mode == MIME_DEMUX_MODE_PLAIN) {
1179             /* in plain mode, just dump the line */
1180             data = line;
1181             data_len = line_len;
1182           }
1183           else if ( (mime_demux_mode == MIME_DEMUX_MODE_QP) || (mime_demux_mode == MIME_DEMUX_MODE_BASE64) ) {
1184             data_len = mime_decode_line(mime_demux_mode,line,&data,line_len,info);
1185             if (data_len < 0) {
1186               /* Error reported from the line decoder. */
1187               data_len = 0;
1188             };
1189           };
1190
1191           /* write data to dump file */
1192           if (data_len > 0) {
1193             if (fwrite(data,1,data_len,mime_dump_file) < data_len) {
1194               /* short write */
1195               snprintf(CS info, 1024,"short write on dump file");
1196               free(line);
1197               return DEFER;
1198             };
1199           };
1200
1201         };
1202       }
1203       else {
1204         /* Scanning mode. We end up here after a end boundary.
1205         This will usually be at the end of a message or at
1206         the end of a MIME container.
1207         We need to look for another start boundary to get
1208         back into header mode. */
1209         if (mime_check_boundary(line,boundaries) == 1) {
1210           mime_demux_mode = MIME_DEMUX_MODE_MIME_HEADERS;
1211         };
1212
1213       };
1214       /* ------------------------------------------------ */
1215     };
1216   };
1217   /* ----------------------- end demux loop ----------------------- */
1218
1219   /* close files, they could still be open */
1220   if (mime_dump_file != NULL)
1221     fclose(mime_dump_file);
1222   if (uu_dump_file != NULL)
1223     fclose(uu_dump_file);
1224
1225   /* release line buffer */
1226   free(line);
1227
1228   /* FIXME: release boundary buffers.
1229   Not too much of a problem since
1230   this instance of exim is not resident. */
1231
1232   if (has_tnef) {
1233     uschar file_name[1024];
1234     /* at least one file could be TNEF encoded.
1235     attempt to send all decoded files thru the TNEF decoder */
1236
1237     snprintf(CS file_name,1024,"%s/scan/%s",spool_directory,message_id);
1238     /* Removed FTTB. We need to decide on TNEF inclusion */
1239     /* mime_unpack_tnef(file_name); */
1240   };
1241
1242   return 0;
1243 }
1244
1245 #endif