libcitadel/lib/mime_parser.c

   1 /*
   2  * $Id$
   3  *
   4  * This is the MIME parser for Citadel.
   5  *
   6  * Copyright (c) 1998-2007 by the citadel.org development team.
   7  * This code is distributed under the GNU General Public License v3.
   8  *
   9  */
  10
  11 #include <stdlib.h>
  12 #include <unistd.h>
  13 #include <stdio.h>
  14 #include <signal.h>
  15 #include <sys/types.h>
  16 #include <ctype.h>
  17 #include <string.h>
  18 #include <sys/stat.h>
  19 #include <errno.h>
  20
  21 #include "libcitadel.h"
  22
  23 void extract_key(char *target, char *source, char *key)
  24 {
  25         char *ptr;
  26         char looking_for[256];
  27         int double_quotes = 0;
  28
  29         snprintf(looking_for, sizeof looking_for, "%s=", key);
  30
  31         ptr = bmstrcasestr(source, looking_for);
  32         if (ptr == NULL) {
  33                 strcpy(target, "");
  34                 return;
  35         }
  36         strcpy(target, (ptr + strlen(looking_for)));
  37
  38         for (ptr=target; (*ptr != 0); ++ptr) {
  39
  40                 /* A semicolon means we've hit the end of the key, unless we're inside double quotes */
  41                 if ( (double_quotes != 1) && (*ptr == ';')) {
  42                         *ptr = 0;
  43                 }
  44
  45                 /* if we find double quotes, we've got a great set of string boundaries */
  46                 if (*ptr == '\"') {
  47                         ++double_quotes;
  48                         if (double_quotes == 1) {
  49                                 strcpy(ptr, ptr+1);
  50                         }
  51                         else {
  52                                 *ptr = 0;
  53                         }
  54                 }
  55         }
  56 }
  57
  58
  59 /*
  60  * For non-multipart messages, we need to generate a quickie partnum of "1"
  61  * to return to callback functions.  Some callbacks demand it.
  62  */
  63 char *fixed_partnum(char *supplied_partnum) {
  64         if (supplied_partnum == NULL) return "1";
  65         if (strlen(supplied_partnum)==0) return "1";
  66         return supplied_partnum;
  67 }
  68
  69
  70
  71 /*
  72  * Convert "quoted-printable" to binary.  Returns number of bytes decoded.
  73  * according to RFC2045 section 6.7
  74  */
  75 int CtdlDecodeQuotedPrintable(char *decoded, char *encoded, int sourcelen) {
  76         unsigned int ch;
  77         int decoded_length = 0;
  78         int pos = 0;
  79
  80         while (pos < sourcelen)
  81         {
  82                 if (!strncmp(&encoded[pos], "=\r\n", 3))
  83                 {
  84                         pos += 3;
  85                 }
  86                 else if (!strncmp(&encoded[pos], "=\n", 2))
  87                 {
  88                         pos += 2;
  89                 }
  90                 else if (encoded[pos] == '=')
  91                 {
  92                         ch = 0;
  93                         sscanf(&encoded[pos+1], "%02x", &ch);
  94                         pos += 3;
  95                         decoded[decoded_length++] = ch;
  96                 }
  97                 else
  98                 {
  99                         decoded[decoded_length++] = encoded[pos];
 100                         pos += 1;
 101                 }
 102         }
 103         decoded[decoded_length] = 0;
 104         return(decoded_length);
 105 }
 106
 107
 108 /*
 109  * Given a message or message-part body and a length, handle any necessary
 110  * decoding and pass the request up the stack.
 111  */
 112 void mime_decode(char *partnum,
 113                  char *part_start, size_t length,
 114                  char *content_type, char *charset, char *encoding,
 115                  char *disposition,
 116                  char *name, char *filename,
 117                  void (*CallBack)
 118                   (char *cbname,
 119                    char *cbfilename,
 120                    char *cbpartnum,
 121                    char *cbdisp,
 122                    void *cbcontent,
 123                    char *cbtype,
 124                    char *cbcharset,
 125                    size_t cblength,
 126                    char *cbencoding,
 127                    void *cbuserdata),
 128                  void (*PreMultiPartCallBack)
 129                   (char *cbname,
 130                    char *cbfilename,
 131                    char *cbpartnum,
 132                    char *cbdisp,
 133                    void *cbcontent,
 134                    char *cbtype,
 135                    char *cbcharset,
 136                    size_t cblength,
 137                    char *cbencoding,
 138                    void *cbuserdata),
 139                  void (*PostMultiPartCallBack)
 140                   (char *cbname,
 141                    char *cbfilename,
 142                    char *cbpartnum,
 143                    char *cbdisp,
 144                    void *cbcontent,
 145                    char *cbtype,
 146                    char *cbcharset,
 147                    size_t cblength,
 148                    char *cbencoding,
 149                    void *cbuserdata),
 150                   void *userdata,
 151                   int dont_decode
 152 )
 153 {
 154
 155         char *decoded;
 156         size_t bytes_decoded = 0;
 157
 158         /* Some encodings aren't really encodings */
 159         if (!strcasecmp(encoding, "7bit"))
 160                 strcpy(encoding, "");
 161         if (!strcasecmp(encoding, "8bit"))
 162                 strcpy(encoding, "");
 163         if (!strcasecmp(encoding, "binary"))
 164                 strcpy(encoding, "");
 165
 166         /* If this part is not encoded, send as-is */
 167         if ( (strlen(encoding) == 0) || (dont_decode)) {
 168                 if (CallBack != NULL) {
 169                         CallBack(name, filename, fixed_partnum(partnum),
 170                                 disposition, part_start,
 171                                 content_type, charset, length, encoding, userdata);
 172                         }
 173                 return;
 174         }
 175
 176         /* Fail silently if we hit an unknown encoding. */
 177         if ((strcasecmp(encoding, "base64"))
 178             && (strcasecmp(encoding, "quoted-printable"))) {
 179                 return;
 180         }
 181
 182         /*
 183          * Allocate a buffer for the decoded data.  The output buffer is slightly
 184          * larger than the input buffer; this assumes that the decoded data
 185          * will never be significantly larger than the encoded data.  This is a
 186          * safe assumption with base64, uuencode, and quoted-printable.
 187          */
 188         decoded = malloc(length + 32768);
 189         if (decoded == NULL) {
 190                 return;
 191         }
 192
 193         if (!strcasecmp(encoding, "base64")) {
 194                 bytes_decoded = CtdlDecodeBase64(decoded, part_start, length);
 195         }
 196         else if (!strcasecmp(encoding, "quoted-printable")) {
 197                 bytes_decoded = CtdlDecodeQuotedPrintable(decoded, part_start, length);
 198         }
 199
 200         if (bytes_decoded > 0) if (CallBack != NULL) {
 201                 CallBack(name, filename, fixed_partnum(partnum),
 202                         disposition, decoded,
 203                         content_type, charset, bytes_decoded, "binary", userdata);
 204         }
 205
 206         free(decoded);
 207 }
 208
 209 /*
 210  * Break out the components of a multipart message
 211  * (This function expects to be fed HEADERS + CONTENT)
 212  * Note: NULL can be supplied as content_end; in this case, the message is
 213  * considered to have ended when the parser encounters a 0x00 byte.
 214  */
 215 void the_mime_parser(char *partnum,
 216                      char *content_start, char *content_end,
 217                      void (*CallBack)
 218                       (char *cbname,
 219                        char *cbfilename,
 220                        char *cbpartnum,
 221                        char *cbdisp,
 222                        void *cbcontent,
 223                        char *cbtype,
 224                        char *cbcharset,
 225                        size_t cblength,
 226                        char *cbencoding,
 227                        void *cbuserdata),
 228                      void (*PreMultiPartCallBack)
 229                       (char *cbname,
 230                        char *cbfilename,
 231                        char *cbpartnum,
 232                        char *cbdisp,
 233                        void *cbcontent,
 234                        char *cbtype,
 235                        char *cbcharset,
 236                        size_t cblength,
 237                        char *cbencoding,
 238                        void *cbuserdata),
 239                      void (*PostMultiPartCallBack)
 240                       (char *cbname,
 241                        char *cbfilename,
 242                        char *cbpartnum,
 243                        char *cbdisp,
 244                        void *cbcontent,
 245                        char *cbtype,
 246                        char *cbcharset,
 247                        size_t cblength,
 248                        char *cbencoding,
 249                        void *cbuserdata),
 250                       void *userdata,
 251                       int dont_decode
 252 )
 253 {
 254
 255         char *ptr;
 256         char *srch = NULL;
 257         char *part_start, *part_end = NULL;
 258         char buf[SIZ];
 259         char *header;
 260         char *boundary;
 261         char *startary;
 262         size_t startary_len = 0;
 263         char *endary;
 264         char *next_boundary;
 265         char *content_type;
 266         char *charset;
 267         size_t content_length;
 268         char *encoding;
 269         char *disposition;
 270         char *name = NULL;
 271         char *content_type_name;
 272         char *content_disposition_name;
 273         char *filename;
 274         int is_multipart;
 275         int part_seq = 0;
 276         int i;
 277         size_t length;
 278         char nested_partnum[256];
 279         int crlf_in_use = 0;
 280         char *evaluate_crlf_ptr = NULL;
 281         int buflen = 0;
 282         int headerlen = 0;
 283
 284         ptr = content_start;
 285         content_length = 0;
 286
 287         boundary = malloc(SIZ);
 288         memset(boundary, 0, SIZ);
 289
 290         startary = malloc(SIZ);
 291         memset(startary, 0, SIZ);
 292
 293         endary = malloc(SIZ);
 294         memset(endary, 0, SIZ);
 295
 296         header = malloc(SIZ);
 297         memset(header, 0, SIZ);
 298
 299         content_type = malloc(SIZ);
 300         memset(content_type, 0, SIZ);
 301
 302         charset = malloc(SIZ);
 303         memset(charset, 0, SIZ);
 304
 305         encoding = malloc(SIZ);
 306         memset(encoding, 0, SIZ);
 307
 308         content_type_name = malloc(SIZ);
 309         memset(content_type_name, 0, SIZ);
 310
 311         content_disposition_name = malloc(SIZ);
 312         memset(content_disposition_name, 0, SIZ);
 313
 314         filename = malloc(SIZ);
 315         memset(filename, 0, SIZ);
 316
 317         disposition = malloc(SIZ);
 318         memset(disposition, 0, SIZ);
 319
 320         /* If the caller didn't supply an endpointer, generate one by measure */
 321         if (content_end == NULL) {
 322                 content_end = &content_start[strlen(content_start)];
 323         }
 324
 325         /* Learn interesting things from the headers */
 326         strcpy(header, "");
 327         headerlen = 0;
 328         do {
 329                 ptr = memreadlinelen(ptr, buf, SIZ, &buflen);
 330                 if (ptr >= content_end) {
 331                         goto end_parser;
 332                 }
 333
 334                 for (i = 0; i < buflen; ++i) {
 335                         if (isspace(buf[i])) {
 336                                 buf[i] = ' ';
 337                         }
 338                 }
 339
 340                 if (!isspace(buf[0])) {
 341                         if (!strncasecmp(header, "Content-type:", 13)) {
 342                                 strcpy(content_type, &header[13]);
 343                                 striplt(content_type);
 344                                 extract_key(content_type_name, content_type, "name");
 345                                 extract_key(charset, content_type, "charset");
 346                                 extract_key(boundary, header, "boundary");
 347                                 /* Deal with weird headers */
 348                                 if (strchr(content_type, ' '))
 349                                         *(strchr(content_type, ' ')) = '\0';
 350                                 if (strchr(content_type, ';'))
 351                                         *(strchr(content_type, ';')) = '\0';
 352                         }
 353                         if (!strncasecmp(header, "Content-Disposition:", 20)) {
 354                                 strcpy(disposition, &header[20]);
 355                                 striplt(disposition);
 356                                 extract_key(content_disposition_name, disposition, "name");
 357                                 extract_key(filename, disposition, "filename");
 358                         }
 359                         if (!strncasecmp(header, "Content-length: ", 15)) {
 360                                 char clbuf[10];
 361                                 safestrncpy(clbuf, &header[15], sizeof clbuf);
 362                                 striplt(clbuf);
 363                                 content_length = (size_t) atol(clbuf);
 364                         }
 365                         if (!strncasecmp(header, "Content-transfer-encoding: ", 26)) {
 366                                 strcpy(encoding, &header[26]);
 367                                 striplt(encoding);
 368                         }
 369                         strcpy(header, "");
 370                         headerlen = 0;
 371                 }
 372                 if ((headerlen + buflen + 2) < SIZ) {
 373                         memcpy(&header[headerlen], buf, buflen);
 374                         headerlen += buflen;
 375                         header[headerlen] = '\0';
 376                 }
 377         } while ((!IsEmptyStr(buf)) && (*ptr != 0));
 378
 379         if (strchr(disposition, ';'))
 380                 *(strchr(disposition, ';')) = '\0';
 381         striplt(disposition);
 382         if (strchr(content_type, ';'))
 383                 *(strchr(content_type, ';')) = '\0';
 384         striplt(content_type);
 385
 386         if (!IsEmptyStr(boundary)) {
 387                 is_multipart = 1;
 388         } else {
 389                 is_multipart = 0;
 390         }
 391
 392         /* If this is a multipart message, then recursively process it */
 393         part_start = NULL;
 394         if (is_multipart) {
 395
 396                 /* Tell the client about this message's multipartedness */
 397                 if (PreMultiPartCallBack != NULL) {
 398                         PreMultiPartCallBack("", "", partnum, "",
 399                                 NULL, content_type, charset,
 400                                 0, encoding, userdata);
 401                 }
 402
 403                 /* Figure out where the boundaries are */
 404                 snprintf(startary, SIZ, "--%s", boundary);
 405                 snprintf(endary, SIZ, "--%s--", boundary);
 406                 startary_len = strlen(startary);
 407
 408                 part_start = NULL;
 409                 do {
 410                         next_boundary = NULL;
 411                         for (srch=ptr; srch<content_end; ++srch) {
 412                                 if (!memcmp(srch, startary, startary_len)) {
 413                                         next_boundary = srch;
 414                                         srch = content_end;
 415                                 }
 416                         }
 417
 418                         if ( (part_start != NULL) && (next_boundary != NULL) ) {
 419                                 part_end = next_boundary;
 420                                 --part_end;             /* omit the trailing LF */
 421                                 if (crlf_in_use) {
 422                                         --part_end;     /* omit the trailing CR */
 423                                 }
 424
 425                                 if (!IsEmptyStr(partnum)) {
 426                                         snprintf(nested_partnum,
 427                                                  sizeof nested_partnum,
 428                                                  "%s.%d", partnum,
 429                                                  ++part_seq);
 430                                 }
 431                                 else {
 432                                         snprintf(nested_partnum,
 433                                                  sizeof nested_partnum,
 434                                                  "%d", ++part_seq);
 435                                 }
 436                                 the_mime_parser(nested_partnum,
 437                                             part_start, part_end,
 438                                                 CallBack,
 439                                                 PreMultiPartCallBack,
 440                                                 PostMultiPartCallBack,
 441                                                 userdata,
 442                                                 dont_decode);
 443                         }
 444
 445                         if (next_boundary != NULL) {
 446                                 /* If we pass out of scope, don't attempt to
 447                                  * read past the end boundary. */
 448                                 if (!strcmp(next_boundary, endary)) {
 449                                         ptr = content_end;
 450                                 }
 451                                 else {
 452                                         /* Set up for the next part. */
 453                                         part_start = strstr(next_boundary, "\n");
 454
 455                                         /* Determine whether newlines are LF or CRLF */
 456                                         evaluate_crlf_ptr = part_start;
 457                                         --evaluate_crlf_ptr;
 458                                         if (!memcmp(evaluate_crlf_ptr, "\r\n", 2)) {
 459                                                 crlf_in_use = 1;
 460                                         }
 461                                         else {
 462                                                 crlf_in_use = 0;
 463                                         }
 464
 465                                         /* Advance past the LF ... now we're in the next part */
 466                                         ++part_start;
 467                                         ptr = part_start;
 468                                 }
 469                         }
 470                         else {
 471                                 /* Invalid end of multipart.  Bail out! */
 472                                 ptr = content_end;
 473                         }
 474                 } while ( (ptr < content_end) && (next_boundary != NULL) );
 475
 476                 if (PostMultiPartCallBack != NULL) {
 477                         PostMultiPartCallBack("", "", partnum, "", NULL,
 478                                 content_type, charset, 0, encoding, userdata);
 479                 }
 480                 goto end_parser;
 481         }
 482
 483         /* If it's not a multipart message, then do something with it */
 484         if (!is_multipart) {
 485                 part_start = ptr;
 486                 length = 0;
 487                 while (ptr < content_end) {
 488                         ++ptr;
 489                         ++length;
 490                 }
 491                 part_end = content_end;
 492
 493                 /******
 494                  * I thought there was an off-by-one error here, but there isn't.
 495                  * This probably means that there's an off-by-one error somewhere
 496                  * else ... or maybe only in certain messages?
 497                 --part_end;
 498                 --length;
 499                 ******/
 500
 501                 /* Truncate if the header told us to */
 502                 if ( (content_length > 0) && (length > content_length) ) {
 503                         length = content_length;
 504                 }
 505
 506                 /* Sometimes the "name" field is tacked on to Content-type,
 507                  * and sometimes it's tacked on to Content-disposition.  Use
 508                  * whichever one we have.
 509                  */
 510                 if (strlen(content_disposition_name) > strlen(content_type_name)) {
 511                         name = content_disposition_name;
 512                 }
 513                 else {
 514                         name = content_type_name;
 515                 }
 516
 517                 /* Ok, we've got a non-multipart part here, so do something with it.
 518                  */
 519                 mime_decode(partnum,
 520                         part_start, length,
 521                         content_type, charset, encoding, disposition,
 522                         name, filename,
 523                         CallBack, NULL, NULL,
 524                         userdata, dont_decode
 525                 );
 526
 527                 /*
 528                  * Now if it's an encapsulated message/rfc822 then we have to recurse into it
 529                  */
 530                 if (!strcasecmp(content_type, "message/rfc822")) {
 531
 532                         if (PreMultiPartCallBack != NULL) {
 533                                 PreMultiPartCallBack("", "", partnum, "",
 534                                         NULL, content_type, charset,
 535                                         0, encoding, userdata);
 536                         }
 537                         if (CallBack != NULL) {
 538                                 if (strlen(partnum) > 0) {
 539                                         snprintf(nested_partnum,
 540                                                  sizeof nested_partnum,
 541                                                  "%s.%d", partnum,
 542                                                  ++part_seq);
 543                                 }
 544                                 else {
 545                                         snprintf(nested_partnum,
 546                                                  sizeof nested_partnum,
 547                                                  "%d", ++part_seq);
 548                                 }
 549                                 the_mime_parser(nested_partnum,
 550                                         part_start, part_end,
 551                                         CallBack,
 552                                         PreMultiPartCallBack,
 553                                         PostMultiPartCallBack,
 554                                         userdata,
 555                                         dont_decode
 556                                 );
 557                         }
 558                         if (PostMultiPartCallBack != NULL) {
 559                                 PostMultiPartCallBack("", "", partnum, "", NULL,
 560                                         content_type, charset, 0, encoding, userdata);
 561                         }
 562
 563
 564                 }
 565
 566         }
 567
 568 end_parser:     /* free the buffers!  end the oppression!! */
 569         free(boundary);
 570         free(startary);
 571         free(endary);
 572         free(header);
 573         free(content_type);
 574         free(charset);
 575         free(encoding);
 576         free(content_type_name);
 577         free(content_disposition_name);
 578         free(filename);
 579         free(disposition);
 580 }
 581
 582
 583
 584 /*
 585  * Entry point for the MIME parser.
 586  * (This function expects to be fed HEADERS + CONTENT)
 587  * Note: NULL can be supplied as content_end; in this case, the message is
 588  * considered to have ended when the parser encounters a 0x00 byte.
 589  */
 590 void mime_parser(char *content_start,
 591                 char *content_end,
 592
 593                  void (*CallBack)
 594                   (char *cbname,
 595                    char *cbfilename,
 596                    char *cbpartnum,
 597                    char *cbdisp,
 598                    void *cbcontent,
 599                    char *cbtype,
 600                    char *cbcharset,
 601                    size_t cblength,
 602                    char *cbencoding,
 603                    void *cbuserdata),
 604
 605                  void (*PreMultiPartCallBack)
 606                   (char *cbname,
 607                    char *cbfilename,
 608                    char *cbpartnum,
 609                    char *cbdisp,
 610                    void *cbcontent,
 611                    char *cbtype,
 612                    char *cbcharset,
 613                    size_t cblength,
 614                    char *cbencoding,
 615                    void *cbuserdata),
 616
 617                  void (*PostMultiPartCallBack)
 618                   (char *cbname,
 619                    char *cbfilename,
 620                    char *cbpartnum,
 621                    char *cbdisp,
 622                    void *cbcontent,
 623                    char *cbtype,
 624                    char *cbcharset,
 625                    size_t cblength,
 626                    char *cbencoding,
 627                    void *cbuserdata),
 628
 629                   void *userdata,
 630                   int dont_decode
 631 )
 632 {
 633
 634         the_mime_parser("", content_start, content_end,
 635                         CallBack,
 636                         PreMultiPartCallBack,
 637                         PostMultiPartCallBack,
 638                         userdata, dont_decode);
 639 }
 640
 641
 642
 643
 644
 645
 646 typedef struct _MimeGuess {
 647         const char *Pattern;
 648         size_t PatternLen;
 649         long PatternOffset;
 650         const char *MimeString;
 651 } MimeGuess;
 652
 653 MimeGuess MyMimes [] = {
 654         {
 655                 "GIF",
 656                 3,
 657                 0,
 658                 "image/gif"
 659         },
 660         {
 661                 "\xff\xd8",
 662                 2,
 663                 0,
 664                 "image/jpeg"
 665         },
 666         {
 667                 "\x89PNG",
 668                 4,
 669                 0,
 670                 "image/png"
 671         },
 672         { // last...
 673                 "",
 674                 0,
 675                 0,
 676                 ""
 677         }
 678 };
 679
 680
 681 const char *GuessMimeType(char *data, size_t dlen)
 682 {
 683         int MimeIndex = 0;
 684
 685         while (MyMimes[MimeIndex].PatternLen != 0)
 686         {
 687                 if ((MyMimes[MimeIndex].PatternLen +
 688                      MyMimes[MimeIndex].PatternOffset < dlen) &&
 689                     strncmp(MyMimes[MimeIndex].Pattern,
 690                             &data[MyMimes[MimeIndex].PatternOffset],
 691                             MyMimes[MimeIndex].PatternLen) == 0)
 692                 {
 693                         break;
 694                 }
 695                 MimeIndex ++;
 696         }
 697         return MyMimes[MimeIndex].MimeString;
 698
 699 }