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  */
  66 int CtdlDecodeQuotedPrintable(char *decoded, char *encoded, int sourcelen) {
  67         unsigned int ch;
  68         int destpos = 1;
  69         int sourcepos = 1;
  70         int ignore_last = 0;
  71         char *check;
  72
  73         decoded[0] = 0;
  74         if (sourcelen >0)
  75                 decoded[0] = encoded[0];
  76         while (destpos <= sourcelen){
  77                 check = &decoded[destpos];
  78                 decoded[destpos] = encoded[sourcepos];
  79                 if ((ignore_last == 0) && (decoded[destpos-1] == '='))
  80                 {
  81                         if ((*check == '\0') ||
  82                             (*check == '\n') ||
  83                             (*check == '\r'))
  84                         {
  85                                 decoded[destpos - 1] = '\r';
  86                                 decoded[destpos] = '\n';
  87                         }
  88                         else if (sourcelen - sourcepos > 2)
  89                         {
  90                                 sscanf(&encoded[sourcepos], "%02x", &ch);
  91                                 decoded[destpos - 1] = ch;
  92                                 sourcepos++;
  93                                 destpos --;
  94                                 ignore_last = 1;
  95                         }
  96                 }
  97                 else
  98                         ignore_last = 0;
  99                 destpos ++;
 100                 sourcepos ++;
 101         }
 102
 103         decoded[destpos] = 0;
 104         return(destpos - 1);
 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[SIZ];
 279
 280         ptr = content_start;
 281         content_length = 0;
 282
 283         boundary = malloc(SIZ);
 284         memset(boundary, 0, SIZ);
 285
 286         startary = malloc(SIZ);
 287         memset(startary, 0, SIZ);
 288
 289         endary = malloc(SIZ);
 290         memset(endary, 0, SIZ);
 291
 292         header = malloc(SIZ);
 293         memset(header, 0, SIZ);
 294
 295         content_type = malloc(SIZ);
 296         memset(content_type, 0, SIZ);
 297
 298         charset = malloc(SIZ);
 299         memset(charset, 0, SIZ);
 300
 301         encoding = malloc(SIZ);
 302         memset(encoding, 0, SIZ);
 303
 304         content_type_name = malloc(SIZ);
 305         memset(content_type_name, 0, SIZ);
 306
 307         content_disposition_name = malloc(SIZ);
 308         memset(content_disposition_name, 0, SIZ);
 309
 310         filename = malloc(SIZ);
 311         memset(filename, 0, SIZ);
 312
 313         disposition = malloc(SIZ);
 314         memset(disposition, 0, SIZ);
 315
 316         /* If the caller didn't supply an endpointer, generate one by measure */
 317         if (content_end == NULL) {
 318                 content_end = &content_start[strlen(content_start)];
 319         }
 320
 321         /* Learn interesting things from the headers */
 322         strcpy(header, "");
 323         do {
 324                 ptr = memreadline(ptr, buf, SIZ);
 325                 if (ptr >= content_end) {
 326                         goto end_parser;
 327                 }
 328
 329                 for (i = 0; i < strlen(buf); ++i) {
 330                         if (isspace(buf[i])) {
 331                                 buf[i] = ' ';
 332                         }
 333                 }
 334
 335                 if (!isspace(buf[0])) {
 336                         if (!strncasecmp(header, "Content-type: ", 14)) {
 337                                 strcpy(content_type, &header[14]);
 338                                 extract_key(content_type_name, content_type, "name");
 339                                 extract_key(charset, content_type, "charset");
 340                                 /* Deal with weird headers */
 341                                 if (strchr(content_type, ' '))
 342                                         *(strchr(content_type, ' ')) = '\0';
 343                                 if (strchr(content_type, ';'))
 344                                         *(strchr(content_type, ';')) = '\0';
 345                         }
 346                         if (!strncasecmp(header, "Content-Disposition: ", 21)) {
 347                                 strcpy(disposition, &header[21]);
 348                                 extract_key(content_disposition_name, disposition, "name");
 349                                 extract_key(filename, disposition, "filename");
 350                         }
 351                         if (!strncasecmp(header, "Content-length: ", 16)) {
 352                                 content_length = (size_t) atol(&header[16]);
 353                         }
 354                         if (!strncasecmp(header,
 355                                       "Content-transfer-encoding: ", 27))
 356                                 strcpy(encoding, &header[27]);
 357                         if (strlen(boundary) == 0)
 358                                 extract_key(boundary, header, "boundary");
 359                         strcpy(header, "");
 360                 }
 361                 if ((strlen(header) + strlen(buf) + 2) < SIZ)
 362                         strcat(header, buf);
 363         } while ((strlen(buf) > 0) && (*ptr != 0));
 364
 365         if (strchr(disposition, ';'))
 366                 *(strchr(disposition, ';')) = '\0';
 367         striplt(disposition);
 368         if (strchr(content_type, ';'))
 369                 *(strchr(content_type, ';')) = '\0';
 370         striplt(content_type);
 371
 372         if (strlen(boundary) > 0) {
 373                 is_multipart = 1;
 374         } else {
 375                 is_multipart = 0;
 376         }
 377
 378         /* If this is a multipart message, then recursively process it */
 379         part_start = NULL;
 380         if (is_multipart) {
 381
 382                 /* Tell the client about this message's multipartedness */
 383                 if (PreMultiPartCallBack != NULL) {
 384                         PreMultiPartCallBack("", "", partnum, "",
 385                                 NULL, content_type, charset,
 386                                 0, encoding, userdata);
 387                 }
 388
 389                 /* Figure out where the boundaries are */
 390                 snprintf(startary, SIZ, "--%s", boundary);
 391                 snprintf(endary, SIZ, "--%s--", boundary);
 392                 startary_len = strlen(startary);
 393
 394                 part_start = NULL;
 395                 do {
 396                         next_boundary = NULL;
 397                         for (srch=ptr; srch<content_end; ++srch) {
 398                                 if (!memcmp(srch, startary, startary_len)) {
 399                                         next_boundary = srch;
 400                                         srch = content_end;
 401                                 }
 402                         }
 403
 404                         if ( (part_start != NULL) && (next_boundary != NULL) ) {
 405                                 part_end = next_boundary;
 406                                 --part_end;
 407
 408                                 if (strlen(partnum) > 0) {
 409                                         snprintf(nested_partnum,
 410                                                  sizeof nested_partnum,
 411                                                  "%s.%d", partnum,
 412                                                  ++part_seq);
 413                                 }
 414                                 else {
 415                                         snprintf(nested_partnum,
 416                                                  sizeof nested_partnum,
 417                                                  "%d", ++part_seq);
 418                                 }
 419                                 the_mime_parser(nested_partnum,
 420                                             part_start, part_end,
 421                                                 CallBack,
 422                                                 PreMultiPartCallBack,
 423                                                 PostMultiPartCallBack,
 424                                                 userdata,
 425                                                 dont_decode);
 426                         }
 427
 428                         if (next_boundary != NULL) {
 429                                 /* If we pass out of scope, don't attempt to
 430                                  * read past the end boundary. */
 431                                 if (!strcmp(next_boundary, endary)) {
 432                                         ptr = content_end;
 433                                 }
 434                                 else {
 435                                         /* Set up for the next part. */
 436                                         part_start = strstr(next_boundary, "\n");
 437                                         ++part_start;
 438                                         ptr = part_start;
 439                                 }
 440                         }
 441                         else {
 442                                 /* Invalid end of multipart.  Bail out! */
 443                                 ptr = content_end;
 444                         }
 445                 } while ( (ptr < content_end) && (next_boundary != NULL) );
 446
 447                 if (PostMultiPartCallBack != NULL) {
 448                         PostMultiPartCallBack("", "", partnum, "", NULL,
 449                                 content_type, charset, 0, encoding, userdata);
 450                 }
 451                 goto end_parser;
 452         }
 453
 454         /* If it's not a multipart message, then do something with it */
 455         if (!is_multipart) {
 456                 part_start = ptr;
 457                 length = 0;
 458                 while (ptr < content_end) {
 459                         ++ptr;
 460                         ++length;
 461                 }
 462                 part_end = content_end;
 463                 /* fix an off-by-one error */
 464                 --part_end;
 465                 --length;
 466
 467                 /* Truncate if the header told us to */
 468                 if ( (content_length > 0) && (length > content_length) ) {
 469                         length = content_length;
 470                 }
 471
 472                 /* Sometimes the "name" field is tacked on to Content-type,
 473                  * and sometimes it's tacked on to Content-disposition.  Use
 474                  * whichever one we have.
 475                  */
 476                 if (strlen(content_disposition_name) > strlen(content_type_name)) {
 477                         name = content_disposition_name;
 478                 }
 479                 else {
 480                         name = content_type_name;
 481                 }
 482
 483                 /* lprintf(CTDL_DEBUG, "mime_decode part=%s, len=%d, type=%s, charset=%s, encoding=%s\n",
 484                         partnum, length, content_type, charset, encoding); */
 485
 486                 /* Ok, we've got a non-multipart part here, so do something with it.
 487                  */
 488                 mime_decode(partnum,
 489                         part_start, length,
 490                         content_type, charset, encoding, disposition,
 491                         name, filename,
 492                         CallBack, NULL, NULL,
 493                         userdata, dont_decode
 494                 );
 495
 496                 /*
 497                  * Now if it's an encapsulated message/rfc822 then we have to recurse into it
 498                  */
 499                 if (!strcasecmp(content_type, "message/rfc822")) {
 500
 501                         if (PreMultiPartCallBack != NULL) {
 502                                 PreMultiPartCallBack("", "", partnum, "",
 503                                         NULL, content_type, charset,
 504                                         0, encoding, userdata);
 505                         }
 506                         if (CallBack != NULL) {
 507                                 if (strlen(partnum) > 0) {
 508                                         snprintf(nested_partnum,
 509                                                  sizeof nested_partnum,
 510                                                  "%s.%d", partnum,
 511                                                  ++part_seq);
 512                                 }
 513                                 else {
 514                                         snprintf(nested_partnum,
 515                                                  sizeof nested_partnum,
 516                                                  "%d", ++part_seq);
 517                                 }
 518                                 the_mime_parser(nested_partnum,
 519                                         part_start, part_end,
 520                                         CallBack,
 521                                         PreMultiPartCallBack,
 522                                         PostMultiPartCallBack,
 523                                         userdata,
 524                                         dont_decode
 525                                 );
 526                         }
 527                         if (PostMultiPartCallBack != NULL) {
 528                                 PostMultiPartCallBack("", "", partnum, "", NULL,
 529                                         content_type, charset, 0, encoding, userdata);
 530                         }
 531
 532
 533                 }
 534
 535         }
 536
 537 end_parser:     /* free the buffers!  end the oppression!! */
 538         free(boundary);
 539         free(startary);
 540         free(endary);
 541         free(header);
 542         free(content_type);
 543         free(charset);
 544         free(encoding);
 545         free(content_type_name);
 546         free(content_disposition_name);
 547         free(filename);
 548         free(disposition);
 549 }
 550
 551
 552
 553 /*
 554  * Entry point for the MIME parser.
 555  * (This function expects to be fed HEADERS + CONTENT)
 556  * Note: NULL can be supplied as content_end; in this case, the message is
 557  * considered to have ended when the parser encounters a 0x00 byte.
 558  */
 559 void mime_parser(char *content_start,
 560                 char *content_end,
 561
 562                  void (*CallBack)
 563                   (char *cbname,
 564                    char *cbfilename,
 565                    char *cbpartnum,
 566                    char *cbdisp,
 567                    void *cbcontent,
 568                    char *cbtype,
 569                    char *cbcharset,
 570                    size_t cblength,
 571                    char *cbencoding,
 572                    void *cbuserdata),
 573
 574                  void (*PreMultiPartCallBack)
 575                   (char *cbname,
 576                    char *cbfilename,
 577                    char *cbpartnum,
 578                    char *cbdisp,
 579                    void *cbcontent,
 580                    char *cbtype,
 581                    char *cbcharset,
 582                    size_t cblength,
 583                    char *cbencoding,
 584                    void *cbuserdata),
 585
 586                  void (*PostMultiPartCallBack)
 587                   (char *cbname,
 588                    char *cbfilename,
 589                    char *cbpartnum,
 590                    char *cbdisp,
 591                    void *cbcontent,
 592                    char *cbtype,
 593                    char *cbcharset,
 594                    size_t cblength,
 595                    char *cbencoding,
 596                    void *cbuserdata),
 597
 598                   void *userdata,
 599                   int dont_decode
 600 )
 601 {
 602
 603         the_mime_parser("", content_start, content_end,
 604                         CallBack,
 605                         PreMultiPartCallBack,
 606                         PostMultiPartCallBack,
 607                         userdata, dont_decode);
 608 }