webcit/mime_parser.c

   1 /*
   2  * $Id$
   3  */
   4 /**
   5  * \defgroup MIME This is the MIME parser for Citadel.
   6  *
   7  * Copyright (c) 1998-2005 by Art Cancro
   8  * This code is distributed under the terms of the GNU General Public License.
   9  * \ingroup WebcitHttpServer
  10  */
  11 /*@{*/
  12 #include "webcit.h"
  13 #include "webserver.h"
  14 #include "mime_parser.h"
  15
  16
  17 void extract_key(char *target, char *source, char *key)
  18 {
  19         int a, b;
  20
  21         strcpy(target, source);
  22         for (a = 0; a < strlen(target); ++a) {
  23                 if ((!strncasecmp(&target[a], key, strlen(key)))
  24                     && (target[a + strlen(key)] == '=')) {
  25                         strcpy(target, &target[a + strlen(key) + 1]);
  26                         if (target[0] == 34)
  27                                 strcpy(target, &target[1]);
  28                         for (b = 0; b < strlen(target); ++b)
  29                                 if (target[b] == 34)
  30                                         target[b] = 0;
  31                         return;
  32                 }
  33         }
  34         strcpy(target, "");
  35 }
  36
  37
  38 /*
  39  * For non-multipart messages, we need to generate a quickie partnum of "1"
  40  * to return to callback functions.  Some callbacks demand it.
  41  */
  42 char *fixed_partnum(char *supplied_partnum) {
  43         if (supplied_partnum == NULL) return "1";
  44         if (strlen(supplied_partnum)==0) return "1";
  45         return supplied_partnum;
  46 }
  47
  48
  49
  50 /*
  51  * Convert "quoted-printable" to binary.  Returns number of bytes decoded.
  52  * according to RFC2045 section 6.7
  53  */
  54 int CtdlDecodeQuotedPrintable(char *decoded, char *encoded, int sourcelen) {
  55         unsigned int ch;
  56         int destpos = 1;
  57         int sourcepos = 1;
  58         int ignore_last = 0;
  59         char *check;
  60
  61         decoded[0] = 0;
  62         if (sourcelen >0)
  63                 decoded[0] = encoded[0];
  64         while (sourcepos <= sourcelen){
  65                 check = &decoded[destpos];
  66                 decoded[destpos] = encoded[sourcepos];
  67                 if ((ignore_last == 0) && (decoded[destpos-1] == '='))
  68                 {
  69                         if ((*check == '\0') ||
  70                             (*check == '\n') ||
  71                             (*check == '\r'))
  72                         {
  73                                 decoded[destpos - 1] = '\0';
  74                                 destpos-=2;
  75                         }
  76                         else if (sourcelen - sourcepos > 2)
  77                         {
  78                                 sscanf(&encoded[sourcepos], "%02x", &ch);
  79                                 decoded[destpos - 1] = ch;
  80                                 sourcepos++;
  81                                 destpos --;
  82                                 ignore_last = 1;
  83                         }
  84                 }
  85                 else
  86                         ignore_last = 0;
  87                 destpos ++;
  88                 sourcepos ++;
  89         }
  90
  91         decoded[destpos] = 0;
  92         return(destpos - 1);
  93 }
  94
  95 /*
  96  * Given a message or message-part body and a length, handle any necessary
  97  * decoding and pass the request up the stack.
  98  */
  99 void mime_decode(char *partnum,
 100                  char *part_start, size_t length,
 101                  char *content_type, char *charset, char *encoding,
 102                  char *disposition,
 103                  char *name, char *filename,
 104                  void (*CallBack)
 105                   (char *cbname,
 106                    char *cbfilename,
 107                    char *cbpartnum,
 108                    char *cbdisp,
 109                    void *cbcontent,
 110                    char *cbtype,
 111                    char *cbcharset,
 112                    size_t cblength,
 113                    char *cbencoding,
 114                    void *cbuserdata),
 115                  void (*PreMultiPartCallBack)
 116                   (char *cbname,
 117                    char *cbfilename,
 118                    char *cbpartnum,
 119                    char *cbdisp,
 120                    void *cbcontent,
 121                    char *cbtype,
 122                    char *cbcharset,
 123                    size_t cblength,
 124                    char *cbencoding,
 125                    void *cbuserdata),
 126                  void (*PostMultiPartCallBack)
 127                   (char *cbname,
 128                    char *cbfilename,
 129                    char *cbpartnum,
 130                    char *cbdisp,
 131                    void *cbcontent,
 132                    char *cbtype,
 133                    char *cbcharset,
 134                    size_t cblength,
 135                    char *cbencoding,
 136                    void *cbuserdata),
 137                   void *userdata,
 138                   int dont_decode
 139 )
 140 {
 141
 142         char *decoded;
 143         size_t bytes_decoded = 0;
 144
 145         /* Some encodings aren't really encodings */
 146         if (!strcasecmp(encoding, "7bit"))
 147                 strcpy(encoding, "");
 148         if (!strcasecmp(encoding, "8bit"))
 149                 strcpy(encoding, "");
 150         if (!strcasecmp(encoding, "binary"))
 151                 strcpy(encoding, "");
 152
 153         /* If this part is not encoded, send as-is */
 154         if ( (strlen(encoding) == 0) || (dont_decode)) {
 155                 if (CallBack != NULL) {
 156                         CallBack(name, filename, fixed_partnum(partnum),
 157                                 disposition, part_start,
 158                                 content_type, charset, length, encoding, userdata);
 159                         }
 160                 return;
 161         }
 162
 163         /* Fail silently if we hit an unknown encoding. */
 164         if ((strcasecmp(encoding, "base64"))
 165             && (strcasecmp(encoding, "quoted-printable"))) {
 166                 return;
 167         }
 168
 169         /*
 170          * Allocate a buffer for the decoded data.  The output buffer is slightly
 171          * larger than the input buffer; this assumes that the decoded data
 172          * will never be significantly larger than the encoded data.  This is a
 173          * safe assumption with base64, uuencode, and quoted-printable.
 174          */
 175         decoded = malloc(length + 32768);
 176         if (decoded == NULL) {
 177                 return;
 178         }
 179
 180         if (!strcasecmp(encoding, "base64")) {
 181                 bytes_decoded = CtdlDecodeBase64(decoded, part_start, length);
 182         }
 183         else if (!strcasecmp(encoding, "quoted-printable")) {
 184                 bytes_decoded = CtdlDecodeQuotedPrintable(decoded, part_start, length);
 185         }
 186
 187         if (bytes_decoded > 0) if (CallBack != NULL) {
 188                 CallBack(name, filename, fixed_partnum(partnum),
 189                         disposition, decoded,
 190                         content_type, charset, bytes_decoded, "binary", userdata);
 191         }
 192
 193         free(decoded);
 194 }
 195
 196 /*
 197  * Break out the components of a multipart message
 198  * (This function expects to be fed HEADERS + CONTENT)
 199  * Note: NULL can be supplied as content_end; in this case, the message is
 200  * considered to have ended when the parser encounters a 0x00 byte.
 201  */
 202 void the_mime_parser(char *partnum,
 203                      char *content_start, char *content_end,
 204                      void (*CallBack)
 205                       (char *cbname,
 206                        char *cbfilename,
 207                        char *cbpartnum,
 208                        char *cbdisp,
 209                        void *cbcontent,
 210                        char *cbtype,
 211                        char *cbcharset,
 212                        size_t cblength,
 213                        char *cbencoding,
 214                        void *cbuserdata),
 215                      void (*PreMultiPartCallBack)
 216                       (char *cbname,
 217                        char *cbfilename,
 218                        char *cbpartnum,
 219                        char *cbdisp,
 220                        void *cbcontent,
 221                        char *cbtype,
 222                        char *cbcharset,
 223                        size_t cblength,
 224                        char *cbencoding,
 225                        void *cbuserdata),
 226                      void (*PostMultiPartCallBack)
 227                       (char *cbname,
 228                        char *cbfilename,
 229                        char *cbpartnum,
 230                        char *cbdisp,
 231                        void *cbcontent,
 232                        char *cbtype,
 233                        char *cbcharset,
 234                        size_t cblength,
 235                        char *cbencoding,
 236                        void *cbuserdata),
 237                       void *userdata,
 238                       int dont_decode
 239 )
 240 {
 241
 242         char *ptr;
 243         char *srch = NULL;
 244         char *part_start, *part_end = NULL;
 245         char buf[SIZ];
 246         char *header;
 247         char *boundary;
 248         char *startary;
 249         size_t startary_len = 0;
 250         char *endary;
 251         char *next_boundary;
 252         char *content_type;
 253         char *charset;
 254         size_t content_length;
 255         char *encoding;
 256         char *disposition;
 257         char *name = NULL;
 258         char *content_type_name;
 259         char *content_disposition_name;
 260         char *filename;
 261         int is_multipart;
 262         int part_seq = 0;
 263         int i;
 264         size_t length;
 265         char nested_partnum[SIZ];
 266
 267         ptr = content_start;
 268         content_length = 0;
 269
 270         boundary = malloc(SIZ);
 271         memset(boundary, 0, SIZ);
 272
 273         startary = malloc(SIZ);
 274         memset(startary, 0, SIZ);
 275
 276         endary = malloc(SIZ);
 277         memset(endary, 0, SIZ);
 278
 279         header = malloc(SIZ);
 280         memset(header, 0, SIZ);
 281
 282         content_type = malloc(SIZ);
 283         memset(content_type, 0, SIZ);
 284
 285         charset = malloc(SIZ);
 286         memset(charset, 0, SIZ);
 287
 288         encoding = malloc(SIZ);
 289         memset(encoding, 0, SIZ);
 290
 291         content_type_name = malloc(SIZ);
 292         memset(content_type_name, 0, SIZ);
 293
 294         content_disposition_name = malloc(SIZ);
 295         memset(content_disposition_name, 0, SIZ);
 296
 297         filename = malloc(SIZ);
 298         memset(filename, 0, SIZ);
 299
 300         disposition = malloc(SIZ);
 301         memset(disposition, 0, SIZ);
 302
 303         /* If the caller didn't supply an endpointer, generate one by measure */
 304         if (content_end == NULL) {
 305                 content_end = &content_start[strlen(content_start)];
 306         }
 307
 308         /* Learn interesting things from the headers */
 309         strcpy(header, "");
 310         do {
 311                 ptr = memreadline(ptr, buf, SIZ);
 312                 if (ptr >= content_end) {
 313                         goto end_parser;
 314                 }
 315
 316                 for (i = 0; i < strlen(buf); ++i) {
 317                         if (isspace(buf[i])) {
 318                                 buf[i] = ' ';
 319                         }
 320                 }
 321
 322                 if (!isspace(buf[0])) {
 323                         if (!strncasecmp(header, "Content-type: ", 14)) {
 324                                 strcpy(content_type, &header[14]);
 325                                 extract_key(content_type_name, content_type, "name");
 326                                 extract_key(charset, content_type, "charset");
 327                                 /* Deal with weird headers */
 328                                 if (strchr(content_type, ' '))
 329                                         *(strchr(content_type, ' ')) = '\0';
 330                                 if (strchr(content_type, ';'))
 331                                         *(strchr(content_type, ';')) = '\0';
 332                         }
 333                         if (!strncasecmp(header, "Content-Disposition: ", 21)) {
 334                                 strcpy(disposition, &header[21]);
 335                                 extract_key(content_disposition_name, disposition, "name");
 336                                 extract_key(filename, disposition, "filename");
 337                         }
 338                         if (!strncasecmp(header, "Content-length: ", 16)) {
 339                                 content_length = (size_t) atol(&header[16]);
 340                         }
 341                         if (!strncasecmp(header,
 342                                       "Content-transfer-encoding: ", 27))
 343                                 strcpy(encoding, &header[27]);
 344                         if (strlen(boundary) == 0)
 345                                 extract_key(boundary, header, "boundary");
 346                         strcpy(header, "");
 347                 }
 348                 if ((strlen(header) + strlen(buf) + 2) < SIZ)
 349                         strcat(header, buf);
 350         } while ((strlen(buf) > 0) && (*ptr != 0));
 351
 352         if (strchr(disposition, ';'))
 353                 *(strchr(disposition, ';')) = '\0';
 354         striplt(disposition);
 355         if (strchr(content_type, ';'))
 356                 *(strchr(content_type, ';')) = '\0';
 357         striplt(content_type);
 358
 359         if (strlen(boundary) > 0) {
 360                 is_multipart = 1;
 361         } else {
 362                 is_multipart = 0;
 363         }
 364
 365         /* If this is a multipart message, then recursively process it */
 366         part_start = NULL;
 367         if (is_multipart) {
 368
 369                 /* Tell the client about this message's multipartedness */
 370                 if (PreMultiPartCallBack != NULL) {
 371                         PreMultiPartCallBack("", "", partnum, "",
 372                                 NULL, content_type, charset,
 373                                 0, encoding, userdata);
 374                 }
 375
 376                 /* Figure out where the boundaries are */
 377                 snprintf(startary, SIZ, "--%s", boundary);
 378                 snprintf(endary, SIZ, "--%s--", boundary);
 379                 startary_len = strlen(startary);
 380
 381                 part_start = NULL;
 382                 do {
 383                         next_boundary = NULL;
 384                         for (srch=ptr; srch<content_end; ++srch) {
 385                                 if (!memcmp(srch, startary, startary_len)) {
 386                                         next_boundary = srch;
 387                                         srch = content_end;
 388                                 }
 389                         }
 390
 391                         if ( (part_start != NULL) && (next_boundary != NULL) ) {
 392                                 part_end = next_boundary;
 393                                 --part_end;
 394
 395                                 if (strlen(partnum) > 0) {
 396                                         snprintf(nested_partnum,
 397                                                  sizeof nested_partnum,
 398                                                  "%s.%d", partnum,
 399                                                  ++part_seq);
 400                                 }
 401                                 else {
 402                                         snprintf(nested_partnum,
 403                                                  sizeof nested_partnum,
 404                                                  "%d", ++part_seq);
 405                                 }
 406                                 the_mime_parser(nested_partnum,
 407                                             part_start, part_end,
 408                                                 CallBack,
 409                                                 PreMultiPartCallBack,
 410                                                 PostMultiPartCallBack,
 411                                                 userdata,
 412                                                 dont_decode);
 413                         }
 414
 415                         if (next_boundary != NULL) {
 416                                 /* If we pass out of scope, don't attempt to
 417                                  * read past the end boundary. */
 418                                 if (!strcmp(next_boundary, endary)) {
 419                                         ptr = content_end;
 420                                 }
 421                                 else {
 422                                         /* Set up for the next part. */
 423                                         part_start = strstr(next_boundary, "\n");
 424                                         ++part_start;
 425                                         ptr = part_start;
 426                                 }
 427                         }
 428                         else {
 429                                 /* Invalid end of multipart.  Bail out! */
 430                                 ptr = content_end;
 431                         }
 432                 } while ( (ptr < content_end) && (next_boundary != NULL) );
 433
 434                 if (PostMultiPartCallBack != NULL) {
 435                         PostMultiPartCallBack("", "", partnum, "", NULL,
 436                                 content_type, charset, 0, encoding, userdata);
 437                 }
 438                 goto end_parser;
 439         }
 440
 441         /* If it's not a multipart message, then do something with it */
 442         if (!is_multipart) {
 443                 part_start = ptr;
 444                 length = 0;
 445                 while (ptr < content_end) {
 446                         ++ptr;
 447                         ++length;
 448                 }
 449                 part_end = content_end;
 450                 /* fix an off-by-one error */
 451                 --part_end;
 452                 --length;
 453
 454                 /* Truncate if the header told us to */
 455                 if ( (content_length > 0) && (length > content_length) ) {
 456                         length = content_length;
 457                 }
 458
 459                 /* Sometimes the "name" field is tacked on to Content-type,
 460                  * and sometimes it's tacked on to Content-disposition.  Use
 461                  * whichever one we have.
 462                  */
 463                 if (strlen(content_disposition_name) > strlen(content_type_name)) {
 464                         name = content_disposition_name;
 465                 }
 466                 else {
 467                         name = content_type_name;
 468                 }
 469
 470                 /* lprintf(CTDL_DEBUG, "mime_decode part=%s, len=%d, type=%s, charset=%s, encoding=%s\n",
 471                         partnum, length, content_type, charset, encoding); */
 472
 473                 /* Ok, we've got a non-multipart part here, so do something with it.
 474                  */
 475                 mime_decode(partnum,
 476                         part_start, length,
 477                         content_type, charset, encoding, disposition,
 478                         name, filename,
 479                         CallBack, NULL, NULL,
 480                         userdata, dont_decode
 481                 );
 482
 483                 /*
 484                  * Now if it's an encapsulated message/rfc822 then we have to recurse into it
 485                  */
 486                 if (!strcasecmp(content_type, "message/rfc822")) {
 487
 488                         if (PreMultiPartCallBack != NULL) {
 489                                 PreMultiPartCallBack("", "", partnum, "",
 490                                         NULL, content_type, charset,
 491                                         0, encoding, userdata);
 492                         }
 493                         if (CallBack != NULL) {
 494                                 if (strlen(partnum) > 0) {
 495                                         snprintf(nested_partnum,
 496                                                  sizeof nested_partnum,
 497                                                  "%s.%d", partnum,
 498                                                  ++part_seq);
 499                                 }
 500                                 else {
 501                                         snprintf(nested_partnum,
 502                                                  sizeof nested_partnum,
 503                                                  "%d", ++part_seq);
 504                                 }
 505                                 the_mime_parser(nested_partnum,
 506                                         part_start, part_end,
 507                                         CallBack,
 508                                         PreMultiPartCallBack,
 509                                         PostMultiPartCallBack,
 510                                         userdata,
 511                                         dont_decode
 512                                 );
 513                         }
 514                         if (PostMultiPartCallBack != NULL) {
 515                                 PostMultiPartCallBack("", "", partnum, "", NULL,
 516                                         content_type, charset, 0, encoding, userdata);
 517                         }
 518
 519
 520                 }
 521
 522         }
 523
 524 end_parser:     /* free the buffers!  end the oppression!! */
 525         free(boundary);
 526         free(startary);
 527         free(endary);
 528         free(header);
 529         free(content_type);
 530         free(charset);
 531         free(encoding);
 532         free(content_type_name);
 533         free(content_disposition_name);
 534         free(filename);
 535         free(disposition);
 536 }
 537
 538
 539
 540 /*
 541  * Entry point for the MIME parser.
 542  * (This function expects to be fed HEADERS + CONTENT)
 543  * Note: NULL can be supplied as content_end; in this case, the message is
 544  * considered to have ended when the parser encounters a 0x00 byte.
 545  */
 546 void mime_parser(char *content_start,
 547                 char *content_end,
 548
 549                  void (*CallBack)
 550                   (char *cbname,
 551                    char *cbfilename,
 552                    char *cbpartnum,
 553                    char *cbdisp,
 554                    void *cbcontent,
 555                    char *cbtype,
 556                    char *cbcharset,
 557                    size_t cblength,
 558                    char *cbencoding,
 559                    void *cbuserdata),
 560
 561                  void (*PreMultiPartCallBack)
 562                   (char *cbname,
 563                    char *cbfilename,
 564                    char *cbpartnum,
 565                    char *cbdisp,
 566                    void *cbcontent,
 567                    char *cbtype,
 568                    char *cbcharset,
 569                    size_t cblength,
 570                    char *cbencoding,
 571                    void *cbuserdata),
 572
 573                  void (*PostMultiPartCallBack)
 574                   (char *cbname,
 575                    char *cbfilename,
 576                    char *cbpartnum,
 577                    char *cbdisp,
 578                    void *cbcontent,
 579                    char *cbtype,
 580                    char *cbcharset,
 581                    size_t cblength,
 582                    char *cbencoding,
 583                    void *cbuserdata),
 584
 585                   void *userdata,
 586                   int dont_decode
 587 )
 588 {
 589
 590         the_mime_parser("", content_start, content_end,
 591                         CallBack,
 592                         PreMultiPartCallBack,
 593                         PostMultiPartCallBack,
 594                         userdata, dont_decode);
 595 }
 596
 597
 598 /*@}*/