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