citadel/mime_parser.c

   1 /*
   2  * $Id$
   3  *
   4  * This is the MIME parser for Citadel.
   5  *
   6  * Copyright (c) 1998-2006 by Art Cancro
   7  * This code is distributed under the GNU General Public License v2.
   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 "citadel.h"
  22 #include "server.h"
  23 #include "serv_extensions.h"
  24 #include "sysdep_decls.h"
  25 #include "tools.h"
  26
  27 #include "mime_parser.h"
  28
  29
  30 void extract_key(char *target, char *source, char *key)
  31 {
  32         int a, b;
  33
  34         strcpy(target, source);
  35         for (a = 0; a < strlen(target); ++a) {
  36                 if ((!strncasecmp(&target[a], key, strlen(key)))
  37                     && (target[a + strlen(key)] == '=')) {
  38                         strcpy(target, &target[a + strlen(key) + 1]);
  39                         if (target[0] == 34)
  40                                 strcpy(target, &target[1]);
  41                         for (b = 0; b < strlen(target); ++b)
  42                                 if (target[b] == 34)
  43                                         target[b] = 0;
  44                         return;
  45                 }
  46         }
  47         strcpy(target, "");
  48 }
  49
  50
  51 /*
  52  * For non-multipart messages, we need to generate a quickie partnum of "1"
  53  * to return to callback functions.  Some callbacks demand it.
  54  */
  55 char *fixed_partnum(char *supplied_partnum) {
  56         if (supplied_partnum == NULL) return "1";
  57         if (strlen(supplied_partnum)==0) return "1";
  58         return supplied_partnum;
  59 }
  60
  61
  62
  63 /*
  64  * Convert "quoted-printable" to binary.  Returns number of bytes decoded.
  65  * according to RFC2045 section 6.7
  66  */
  67 int CtdlDecodeQuotedPrintable(char *decoded, char *encoded, int sourcelen) {
  68         unsigned int ch;
  69         int destpos = 1;
  70         int sourcepos = 1;
  71         int ignore_last = 0;
  72         char *check;
  73
  74         decoded[0] = 0;
  75         if (sourcelen >0)
  76                 decoded[0] = encoded[0];
  77         while (sourcepos <= sourcelen){
  78                 check = &decoded[destpos];
  79                 decoded[destpos] = encoded[sourcepos];
  80                 if ((ignore_last == 0) && (decoded[destpos-1] == '='))
  81                 {
  82                         if ((*check == '\0') ||
  83                             (*check == '\n') ||
  84                             (*check == '\r'))
  85                         {
  86                                 decoded[destpos - 1] = '\0';
  87                                 destpos-=2;
  88                         }
  89                         else if (sourcelen - sourcepos > 2)
  90                         {
  91                                 sscanf(&encoded[sourcepos], "%02x", &ch);
  92                                 decoded[destpos - 1] = ch;
  93                                 sourcepos++;
  94                                 destpos --;
  95                                 ignore_last = 1;
  96                         }
  97                 }
  98                 else
  99                         ignore_last = 0;
 100                 destpos ++;
 101                 sourcepos ++;
 102         }
 103
 104         decoded[destpos] = 0;
 105         return(destpos - 1);
 106 }
 107
 108
 109 /*
 110  * Given a message or message-part body and a length, handle any necessary
 111  * decoding and pass the request up the stack.
 112  */
 113 void mime_decode(char *partnum,
 114                  char *part_start, size_t length,
 115                  char *content_type, char *charset, char *encoding,
 116                  char *disposition,
 117                  char *name, char *filename,
 118                  void (*CallBack)
 119                   (char *cbname,
 120                    char *cbfilename,
 121                    char *cbpartnum,
 122                    char *cbdisp,
 123                    void *cbcontent,
 124                    char *cbtype,
 125                    char *cbcharset,
 126                    size_t cblength,
 127                    char *cbencoding,
 128                    void *cbuserdata),
 129                  void (*PreMultiPartCallBack)
 130                   (char *cbname,
 131                    char *cbfilename,
 132                    char *cbpartnum,
 133                    char *cbdisp,
 134                    void *cbcontent,
 135                    char *cbtype,
 136                    char *cbcharset,
 137                    size_t cblength,
 138                    char *cbencoding,
 139                    void *cbuserdata),
 140                  void (*PostMultiPartCallBack)
 141                   (char *cbname,
 142                    char *cbfilename,
 143                    char *cbpartnum,
 144                    char *cbdisp,
 145                    void *cbcontent,
 146                    char *cbtype,
 147                    char *cbcharset,
 148                    size_t cblength,
 149                    char *cbencoding,
 150                    void *cbuserdata),
 151                   void *userdata,
 152                   int dont_decode
 153 )
 154 {
 155
 156         char *decoded;
 157         size_t bytes_decoded = 0;
 158
 159         /* Some encodings aren't really encodings */
 160         if (!strcasecmp(encoding, "7bit"))
 161                 strcpy(encoding, "");
 162         if (!strcasecmp(encoding, "8bit"))
 163                 strcpy(encoding, "");
 164         if (!strcasecmp(encoding, "binary"))
 165                 strcpy(encoding, "");
 166
 167         /* If this part is not encoded, send as-is */
 168         if ( (strlen(encoding) == 0) || (dont_decode)) {
 169                 if (CallBack != NULL) {
 170                         CallBack(name, filename, fixed_partnum(partnum),
 171                                 disposition, part_start,
 172                                 content_type, charset, length, encoding, userdata);
 173                         }
 174                 return;
 175         }
 176
 177         /* Fail silently if we hit an unknown encoding. */
 178         if ((strcasecmp(encoding, "base64"))
 179             && (strcasecmp(encoding, "quoted-printable"))) {
 180                 return;
 181         }
 182
 183         /*
 184          * Allocate a buffer for the decoded data.  The output buffer is slightly
 185          * larger than the input buffer; this assumes that the decoded data
 186          * will never be significantly larger than the encoded data.  This is a
 187          * safe assumption with base64, uuencode, and quoted-printable.
 188          */
 189         decoded = malloc(length + 32768);
 190         if (decoded == NULL) {
 191                 return;
 192         }
 193
 194         if (!strcasecmp(encoding, "base64")) {
 195                 bytes_decoded = CtdlDecodeBase64(decoded, part_start, length);
 196         }
 197         else if (!strcasecmp(encoding, "quoted-printable")) {
 198                 bytes_decoded = CtdlDecodeQuotedPrintable(decoded, part_start, length);
 199         }
 200
 201         if (bytes_decoded > 0) if (CallBack != NULL) {
 202                 CallBack(name, filename, fixed_partnum(partnum),
 203                         disposition, decoded,
 204                         content_type, charset, bytes_decoded, "binary", userdata);
 205         }
 206
 207         free(decoded);
 208 }
 209
 210 /*
 211  * Break out the components of a multipart message
 212  * (This function expects to be fed HEADERS + CONTENT)
 213  * Note: NULL can be supplied as content_end; in this case, the message is
 214  * considered to have ended when the parser encounters a 0x00 byte.
 215  */
 216 void the_mime_parser(char *partnum,
 217                      char *content_start, char *content_end,
 218                      void (*CallBack)
 219                       (char *cbname,
 220                        char *cbfilename,
 221                        char *cbpartnum,
 222                        char *cbdisp,
 223                        void *cbcontent,
 224                        char *cbtype,
 225                        char *cbcharset,
 226                        size_t cblength,
 227                        char *cbencoding,
 228                        void *cbuserdata),
 229                      void (*PreMultiPartCallBack)
 230                       (char *cbname,
 231                        char *cbfilename,
 232                        char *cbpartnum,
 233                        char *cbdisp,
 234                        void *cbcontent,
 235                        char *cbtype,
 236                        char *cbcharset,
 237                        size_t cblength,
 238                        char *cbencoding,
 239                        void *cbuserdata),
 240                      void (*PostMultiPartCallBack)
 241                       (char *cbname,
 242                        char *cbfilename,
 243                        char *cbpartnum,
 244                        char *cbdisp,
 245                        void *cbcontent,
 246                        char *cbtype,
 247                        char *cbcharset,
 248                        size_t cblength,
 249                        char *cbencoding,
 250                        void *cbuserdata),
 251                       void *userdata,
 252                       int dont_decode
 253 )
 254 {
 255
 256         char *ptr;
 257         char *srch = NULL;
 258         char *part_start, *part_end = NULL;
 259         char buf[SIZ];
 260         char *header;
 261         char *boundary;
 262         char *startary;
 263         size_t startary_len = 0;
 264         char *endary;
 265         char *next_boundary;
 266         char *content_type;
 267         char *charset;
 268         size_t content_length;
 269         char *encoding;
 270         char *disposition;
 271         char *name = NULL;
 272         char *content_type_name;
 273         char *content_disposition_name;
 274         char *filename;
 275         int is_multipart;
 276         int part_seq = 0;
 277         int i;
 278         size_t length;
 279         char nested_partnum[SIZ];
 280
 281         ptr = content_start;
 282         content_length = 0;
 283
 284         boundary = malloc(SIZ);
 285         memset(boundary, 0, SIZ);
 286
 287         startary = malloc(SIZ);
 288         memset(startary, 0, SIZ);
 289
 290         endary = malloc(SIZ);
 291         memset(endary, 0, SIZ);
 292
 293         header = malloc(SIZ);
 294         memset(header, 0, SIZ);
 295
 296         content_type = malloc(SIZ);
 297         memset(content_type, 0, SIZ);
 298
 299         charset = malloc(SIZ);
 300         memset(charset, 0, SIZ);
 301
 302         encoding = malloc(SIZ);
 303         memset(encoding, 0, SIZ);
 304
 305         content_type_name = malloc(SIZ);
 306         memset(content_type_name, 0, SIZ);
 307
 308         content_disposition_name = malloc(SIZ);
 309         memset(content_disposition_name, 0, SIZ);
 310
 311         filename = malloc(SIZ);
 312         memset(filename, 0, SIZ);
 313
 314         disposition = malloc(SIZ);
 315         memset(disposition, 0, SIZ);
 316
 317         /* If the caller didn't supply an endpointer, generate one by measure */
 318         if (content_end == NULL) {
 319                 content_end = &content_start[strlen(content_start)];
 320         }
 321
 322         /* Learn interesting things from the headers */
 323         strcpy(header, "");
 324         do {
 325                 ptr = memreadline(ptr, buf, SIZ);
 326                 if (ptr >= content_end) {
 327                         goto end_parser;
 328                 }
 329
 330                 for (i = 0; i < strlen(buf); ++i) {
 331                         if (isspace(buf[i])) {
 332                                 buf[i] = ' ';
 333                         }
 334                 }
 335
 336                 if (!isspace(buf[0])) {
 337                         if (!strncasecmp(header, "Content-type: ", 14)) {
 338                                 strcpy(content_type, &header[14]);
 339                                 extract_key(content_type_name, content_type, "name");
 340                                 extract_key(charset, content_type, "charset");
 341                                 /* Deal with weird headers */
 342                                 if (strchr(content_type, ' '))
 343                                         *(strchr(content_type, ' ')) = '\0';
 344                                 if (strchr(content_type, ';'))
 345                                         *(strchr(content_type, ';')) = '\0';
 346                         }
 347                         if (!strncasecmp(header, "Content-Disposition: ", 21)) {
 348                                 strcpy(disposition, &header[21]);
 349                                 extract_key(content_disposition_name, disposition, "name");
 350                                 extract_key(filename, disposition, "filename");
 351                         }
 352                         if (!strncasecmp(header, "Content-length: ", 16)) {
 353                                 content_length = (size_t) atol(&header[16]);
 354                         }
 355                         if (!strncasecmp(header,
 356                                       "Content-transfer-encoding: ", 27))
 357                                 strcpy(encoding, &header[27]);
 358                         if (strlen(boundary) == 0)
 359                                 extract_key(boundary, header, "boundary");
 360                         strcpy(header, "");
 361                 }
 362                 if ((strlen(header) + strlen(buf) + 2) < SIZ)
 363                         strcat(header, buf);
 364         } while ((strlen(buf) > 0) && (*ptr != 0));
 365
 366         if (strchr(disposition, ';'))
 367                 *(strchr(disposition, ';')) = '\0';
 368         striplt(disposition);
 369         if (strchr(content_type, ';'))
 370                 *(strchr(content_type, ';')) = '\0';
 371         striplt(content_type);
 372
 373         if (strlen(boundary) > 0) {
 374                 is_multipart = 1;
 375         } else {
 376                 is_multipart = 0;
 377         }
 378
 379         /* If this is a multipart message, then recursively process it */
 380         part_start = NULL;
 381         if (is_multipart) {
 382
 383                 /* Tell the client about this message's multipartedness */
 384                 if (PreMultiPartCallBack != NULL) {
 385                         PreMultiPartCallBack("", "", partnum, "",
 386                                 NULL, content_type, charset,
 387                                 0, encoding, userdata);
 388                 }
 389
 390                 /* Figure out where the boundaries are */
 391                 snprintf(startary, SIZ, "--%s", boundary);
 392                 snprintf(endary, SIZ, "--%s--", boundary);
 393                 startary_len = strlen(startary);
 394
 395                 part_start = NULL;
 396                 do {
 397                         next_boundary = NULL;
 398                         for (srch=ptr; srch<content_end; ++srch) {
 399                                 if (!memcmp(srch, startary, startary_len)) {
 400                                         next_boundary = srch;
 401                                         srch = content_end;
 402                                 }
 403                         }
 404
 405                         if ( (part_start != NULL) && (next_boundary != NULL) ) {
 406                                 part_end = next_boundary;
 407                                 --part_end;
 408
 409                                 if (strlen(partnum) > 0) {
 410                                         snprintf(nested_partnum,
 411                                                  sizeof nested_partnum,
 412                                                  "%s.%d", partnum,
 413                                                  ++part_seq);
 414                                 }
 415                                 else {
 416                                         snprintf(nested_partnum,
 417                                                  sizeof nested_partnum,
 418                                                  "%d", ++part_seq);
 419                                 }
 420                                 the_mime_parser(nested_partnum,
 421                                             part_start, part_end,
 422                                                 CallBack,
 423                                                 PreMultiPartCallBack,
 424                                                 PostMultiPartCallBack,
 425                                                 userdata,
 426                                                 dont_decode);
 427                         }
 428
 429                         if (next_boundary != NULL) {
 430                                 /* If we pass out of scope, don't attempt to
 431                                  * read past the end boundary. */
 432                                 if (!strcmp(next_boundary, endary)) {
 433                                         ptr = content_end;
 434                                 }
 435                                 else {
 436                                         /* Set up for the next part. */
 437                                         part_start = strstr(next_boundary, "\n");
 438                                         ++part_start;
 439                                         ptr = part_start;
 440                                 }
 441                         }
 442                         else {
 443                                 /* Invalid end of multipart.  Bail out! */
 444                                 ptr = content_end;
 445                         }
 446                 } while ( (ptr < content_end) && (next_boundary != NULL) );
 447
 448                 if (PostMultiPartCallBack != NULL) {
 449                         PostMultiPartCallBack("", "", partnum, "", NULL,
 450                                 content_type, charset, 0, encoding, userdata);
 451                 }
 452                 goto end_parser;
 453         }
 454
 455         /* If it's not a multipart message, then do something with it */
 456         if (!is_multipart) {
 457                 part_start = ptr;
 458                 length = 0;
 459                 while (ptr < content_end) {
 460                         ++ptr;
 461                         ++length;
 462                 }
 463                 part_end = content_end;
 464                 /* fix an off-by-one error */
 465                 --part_end;
 466                 --length;
 467
 468                 /* Truncate if the header told us to */
 469                 if ( (content_length > 0) && (length > content_length) ) {
 470                         length = content_length;
 471                 }
 472
 473                 /* Sometimes the "name" field is tacked on to Content-type,
 474                  * and sometimes it's tacked on to Content-disposition.  Use
 475                  * whichever one we have.
 476                  */
 477                 if (strlen(content_disposition_name) > strlen(content_type_name)) {
 478                         name = content_disposition_name;
 479                 }
 480                 else {
 481                         name = content_type_name;
 482                 }
 483
 484                 /* lprintf(CTDL_DEBUG, "mime_decode part=%s, len=%d, type=%s, charset=%s, encoding=%s\n",
 485                         partnum, length, content_type, charset, encoding); */
 486
 487                 /* Ok, we've got a non-multipart part here, so do something with it.
 488                  */
 489                 mime_decode(partnum,
 490                         part_start, length,
 491                         content_type, charset, encoding, disposition,
 492                         name, filename,
 493                         CallBack, NULL, NULL,
 494                         userdata, dont_decode
 495                 );
 496
 497                 /*
 498                  * Now if it's an encapsulated message/rfc822 then we have to recurse into it
 499                  */
 500                 if (!strcasecmp(content_type, "message/rfc822")) {
 501
 502                         if (PreMultiPartCallBack != NULL) {
 503                                 PreMultiPartCallBack("", "", partnum, "",
 504                                         NULL, content_type, charset,
 505                                         0, encoding, userdata);
 506                         }
 507                         if (CallBack != NULL) {
 508                                 if (strlen(partnum) > 0) {
 509                                         snprintf(nested_partnum,
 510                                                  sizeof nested_partnum,
 511                                                  "%s.%d", partnum,
 512                                                  ++part_seq);
 513                                 }
 514                                 else {
 515                                         snprintf(nested_partnum,
 516                                                  sizeof nested_partnum,
 517                                                  "%d", ++part_seq);
 518                                 }
 519                                 the_mime_parser(nested_partnum,
 520                                         part_start, part_end,
 521                                         CallBack,
 522                                         PreMultiPartCallBack,
 523                                         PostMultiPartCallBack,
 524                                         userdata,
 525                                         dont_decode
 526                                 );
 527                         }
 528                         if (PostMultiPartCallBack != NULL) {
 529                                 PostMultiPartCallBack("", "", partnum, "", NULL,
 530                                         content_type, charset, 0, encoding, userdata);
 531                         }
 532
 533
 534                 }
 535
 536         }
 537
 538 end_parser:     /* free the buffers!  end the oppression!! */
 539         free(boundary);
 540         free(startary);
 541         free(endary);
 542         free(header);
 543         free(content_type);
 544         free(charset);
 545         free(encoding);
 546         free(content_type_name);
 547         free(content_disposition_name);
 548         free(filename);
 549         free(disposition);
 550 }
 551
 552
 553
 554 /*
 555  * Entry point for the MIME parser.
 556  * (This function expects to be fed HEADERS + CONTENT)
 557  * Note: NULL can be supplied as content_end; in this case, the message is
 558  * considered to have ended when the parser encounters a 0x00 byte.
 559  */
 560 void mime_parser(char *content_start,
 561                 char *content_end,
 562
 563                  void (*CallBack)
 564                   (char *cbname,
 565                    char *cbfilename,
 566                    char *cbpartnum,
 567                    char *cbdisp,
 568                    void *cbcontent,
 569                    char *cbtype,
 570                    char *cbcharset,
 571                    size_t cblength,
 572                    char *cbencoding,
 573                    void *cbuserdata),
 574
 575                  void (*PreMultiPartCallBack)
 576                   (char *cbname,
 577                    char *cbfilename,
 578                    char *cbpartnum,
 579                    char *cbdisp,
 580                    void *cbcontent,
 581                    char *cbtype,
 582                    char *cbcharset,
 583                    size_t cblength,
 584                    char *cbencoding,
 585                    void *cbuserdata),
 586
 587                  void (*PostMultiPartCallBack)
 588                   (char *cbname,
 589                    char *cbfilename,
 590                    char *cbpartnum,
 591                    char *cbdisp,
 592                    void *cbcontent,
 593                    char *cbtype,
 594                    char *cbcharset,
 595                    size_t cblength,
 596                    char *cbencoding,
 597                    void *cbuserdata),
 598
 599                   void *userdata,
 600                   int dont_decode
 601 )
 602 {
 603
 604         the_mime_parser("", content_start, content_end,
 605                         CallBack,
 606                         PreMultiPartCallBack,
 607                         PostMultiPartCallBack,
 608                         userdata, dont_decode);
 609 }