src/src/demime.c

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