webcit/html2html.c

   1 /*
   2  * $Id$
   3  */
   4 /**
   5  * \defgroup HTML2HTML Output an HTML message, modifying it slightly to make sure it plays nice
   6  * with the rest of our web framework.
   7  * \ingroup WebcitHttpServer
   8  */
   9 /*@{*/
  10 #include "webcit.h"
  11 #include "webserver.h"
  12
  13
  14 /**
  15  * \brief       Strip surrounding single or double quotes from a string.
  16  *
  17  * \param s     String to be stripped.
  18  */
  19 void stripquotes(char *s)
  20 {
  21         int len;
  22
  23         if (!s) return;
  24
  25         len = strlen(s);
  26         if (len < 2) return;
  27
  28         if ( ( (s[0] == '\"') && (s[len-1] == '\"') ) || ( (s[0] == '\'') && (s[len-1] == '\'') ) ) {
  29                 s[len-1] = 0;
  30                 strcpy(s, &s[1]);
  31         }
  32 }
  33
  34
  35 /**
  36  * \brief Check to see if a META tag has overridden the declared MIME character set.
  37  *
  38  * \param charset               Character set name (left unchanged if we don't do anything)
  39  * \param meta_http_equiv       Content of the "http-equiv" portion of the META tag
  40  * \param meta_content          Content of the "content" portion of the META tag
  41  */
  42 void extract_charset_from_meta(char *charset, char *meta_http_equiv, char *meta_content)
  43 {
  44         char *ptr;
  45         char buf[64];
  46
  47         if (!charset) return;
  48         if (!meta_http_equiv) return;
  49         if (!meta_content) return;
  50
  51
  52         if (strcasecmp(meta_http_equiv, "Content-type")) return;
  53
  54         ptr = strchr(meta_content, ';');
  55         if (!ptr) return;
  56
  57         safestrncpy(buf, ++ptr, sizeof buf);
  58         striplt(buf);
  59         if (!strncasecmp(buf, "charset=", 8)) {
  60                 strcpy(charset, &buf[8]);
  61
  62                 /*
  63                  * The brain-damaged webmail program in Microsoft Exchange declares
  64                  * a charset of "unicode" when they really mean "UTF-8".  GNU iconv
  65                  * treats "unicode" as an alias for "UTF-16" so we have to manually
  66                  * fix this here, otherwise messages generated in Exchange webmail
  67                  * show up as a big pile of weird characters.
  68                  */
  69                 if (!strcasecmp(charset, "unicode")) {
  70                         strcpy(charset, "UTF-8");
  71                 }
  72
  73         }
  74 }
  75
  76
  77
  78 /**
  79  * \brief Sanitize and enhance an HTML message for display.
  80  *        Also convert weird character sets to UTF-8 if necessary.
  81  *
  82  * \param supplied_charset the input charset as declared in the MIME headers
  83  */
  84 void output_html(char *supplied_charset, int treat_as_wiki) {
  85         char buf[SIZ];
  86         char *msg;
  87         char *ptr;
  88         char *msgstart;
  89         char *msgend;
  90         char *converted_msg;
  91         size_t converted_alloc = 0;
  92         int buffer_length = 1;
  93         int line_length = 0;
  94         int content_length = 0;
  95         int output_length = 0;
  96         char new_window[SIZ];
  97         int brak = 0;
  98         int alevel = 0;
  99         int scriptlevel = 0;
 100         int script_start_pos = (-1);
 101         int i;
 102         int linklen;
 103         char charset[128];
 104 #ifdef HAVE_ICONV
 105         iconv_t ic = (iconv_t)(-1) ;
 106         char *ibuf;                   /**< Buffer of characters to be converted */
 107         char *obuf;                   /**< Buffer for converted characters      */
 108         size_t ibuflen;               /**< Length of input buffer               */
 109         size_t obuflen;               /**< Length of output buffer              */
 110         char *osav;                   /**< Saved pointer to output buffer       */
 111 #endif
 112
 113         safestrncpy(charset, supplied_charset, sizeof charset);
 114         msg = strdup("");
 115         sprintf(new_window, "<a target=\"%s\" href=", TARGET);
 116
 117         while (serv_getln(buf, sizeof buf), strcmp(buf, "000")) {
 118                 line_length = strlen(buf);
 119                 buffer_length = content_length + line_length + 2;
 120                 ptr = realloc(msg, buffer_length);
 121                 if (ptr == NULL) {
 122                         wprintf("<b>");
 123                         wprintf(_("realloc() error! couldn't get %d bytes: %s"),
 124                                 buffer_length + 1,
 125                                 strerror(errno));
 126                         wprintf("</b><br /><br />\n");
 127                         while (serv_getln(buf, sizeof buf), strcmp(buf, "000")) {
 128                                 /** flush */
 129                         }
 130                         free(msg);
 131                         return;
 132                 }
 133                 msg = ptr;
 134                 strcpy(&msg[content_length], buf);
 135                 content_length += line_length;
 136                 strcpy(&msg[content_length], "\n");
 137                 content_length += 1;
 138         }
 139
 140         /** Do a first pass to isolate the message body */
 141         ptr = msg + 1;
 142         msgstart = msg;
 143         msgend = &msg[content_length];
 144
 145         while (ptr < msgend) {
 146
 147                 /** Advance to next tag */
 148                 ptr = strchr(ptr, '<');
 149                 if ((ptr == NULL) || (ptr >= msgend)) break;
 150                 ++ptr;
 151                 if ((ptr == NULL) || (ptr >= msgend)) break;
 152
 153                 /**
 154                  *  Look for META tags.  Some messages (particularly in
 155                  *  Asian locales) illegally declare a message's character
 156                  *  set in the HTML instead of in the MIME headers.  This
 157                  *  is wrong but we have to work around it anyway.
 158                  */
 159                 if (!strncasecmp(ptr, "META", 4)) {
 160
 161                         char *meta_start;
 162                         char *meta_end;
 163                         int meta_length;
 164                         char *meta;
 165                         char *meta_http_equiv;
 166                         char *meta_content;
 167                         char *spaceptr;
 168
 169                         meta_start = &ptr[4];
 170                         meta_end = strchr(ptr, '>');
 171                         if ((meta_end != NULL) && (meta_end <= msgend)) {
 172                                 meta_length = meta_end - meta_start + 1;
 173                                 meta = malloc(meta_length + 1);
 174                                 safestrncpy(meta, meta_start, meta_length);
 175                                 meta[meta_length] = 0;
 176                                 striplt(meta);
 177                                 if (!strncasecmp(meta, "HTTP-EQUIV=", 11)) {
 178                                         meta_http_equiv = strdup(&meta[11]);
 179                                         spaceptr = strchr(meta_http_equiv, ' ');
 180                                         if (spaceptr != NULL) {
 181                                                 *spaceptr = 0;
 182                                                 meta_content = strdup(++spaceptr);
 183                                                 if (!strncasecmp(meta_content, "content=", 8)) {
 184                                                         strcpy(meta_content, &meta_content[8]);
 185                                                         stripquotes(meta_http_equiv);
 186                                                         stripquotes(meta_content);
 187                                                         extract_charset_from_meta(charset,
 188                                                                 meta_http_equiv, meta_content);
 189                                                 }
 190                                                 free(meta_content);
 191                                         }
 192                                         free(meta_http_equiv);
 193                                 }
 194                                 free(meta);
 195                         }
 196                 }
 197
 198                 /**
 199                  * Any of these tags cause everything up to and including
 200                  * the tag to be removed.
 201                  */
 202                 if ( (!strncasecmp(ptr, "HTML", 4))
 203                    ||(!strncasecmp(ptr, "HEAD", 4))
 204                    ||(!strncasecmp(ptr, "/HEAD", 5))
 205                    ||(!strncasecmp(ptr, "BODY", 4)) ) {
 206                         ptr = strchr(ptr, '>');
 207                         if ((ptr == NULL) || (ptr >= msgend)) break;
 208                         ++ptr;
 209                         if ((ptr == NULL) || (ptr >= msgend)) break;
 210                         msgstart = ptr;
 211                 }
 212
 213                 /**
 214                  * Any of these tags cause everything including and following
 215                  * the tag to be removed.
 216                  */
 217                 if ( (!strncasecmp(ptr, "/HTML", 5))
 218                    ||(!strncasecmp(ptr, "/BODY", 5)) ) {
 219                         --ptr;
 220                         msgend = ptr;
 221                         strcpy(ptr, "");
 222
 223                 }
 224
 225                 ++ptr;
 226         }
 227         if (msgstart > msg) {
 228                 strcpy(msg, msgstart);
 229         }
 230
 231         /** Convert foreign character sets to UTF-8 if necessary. */
 232 #ifdef HAVE_ICONV
 233         if ( (strcasecmp(charset, "us-ascii"))
 234            && (strcasecmp(charset, "UTF-8"))
 235            && (strcasecmp(charset, ""))
 236         ) {
 237                 lprintf(9, "Converting %s to UTF-8\n", charset);
 238                 ic = ctdl_iconv_open("UTF-8", charset);
 239                 if (ic == (iconv_t)(-1) ) {
 240                         lprintf(5, "%s:%d iconv_open() failed: %s\n",
 241                                 __FILE__, __LINE__, strerror(errno));
 242                 }
 243         }
 244         if (ic != (iconv_t)(-1) ) {
 245                 ibuf = msg;
 246                 ibuflen = content_length;
 247                 obuflen = content_length + (content_length / 2) ;
 248                 obuf = (char *) malloc(obuflen);
 249                 osav = obuf;
 250                 iconv(ic, &ibuf, &ibuflen, &obuf, &obuflen);
 251                 content_length = content_length + (content_length / 2) - obuflen;
 252                 osav[content_length] = 0;
 253                 free(msg);
 254                 msg = osav;
 255                 iconv_close(ic);
 256         }
 257 #endif
 258
 259         /**
 260          *      At this point, the message has been stripped down to
 261          *      only the content inside the <BODY></BODY> tags, and has
 262          *      been converted to UTF-8 if it was originally in a foreign
 263          *      character set.  The text is also guaranteed to be null
 264          *      terminated now.
 265          */
 266
 267         /** Now go through the message, parsing tags as necessary. */
 268         converted_alloc = content_length + 8192;
 269         converted_msg = malloc(converted_alloc);
 270         if (converted_msg == NULL) {
 271                 wprintf("Error %d: %s<br />%s:%s", errno, strerror(errno), __FILE__, __LINE__);
 272                 goto BAIL;
 273         }
 274
 275         strcpy(converted_msg, "");
 276         ptr = msg;
 277         msgend = strchr(msg, 0);
 278         while (ptr < msgend) {
 279
 280                 /** Try to sanitize the html of any rogue scripts */
 281                 if (!strncasecmp(ptr, "<script", 7)) {
 282                         if (scriptlevel == 0) {
 283                                 script_start_pos = output_length;
 284                         }
 285                         ++scriptlevel;
 286                 }
 287                 if (!strncasecmp(ptr, "</script", 8)) {
 288                         --scriptlevel;
 289                 }
 290
 291                 /**
 292                  * Change mailto: links to WebCit mail, by replacing the
 293                  * link with one that points back to our mail room.  Due to
 294                  * the way we parse URL's, it'll even handle mailto: links
 295                  * that have "?subject=" in them.
 296                  */
 297                 if (!strncasecmp(ptr, "<a href=\"mailto:", 16)) {
 298                         content_length += 64;
 299                         if (content_length >= converted_alloc) {
 300                                 converted_alloc += 8192;
 301                                 converted_msg = realloc(converted_msg, converted_alloc);
 302                                 if (converted_msg == NULL) {
 303                                         abort();
 304                                 }
 305                         }
 306                         sprintf(&converted_msg[output_length],
 307                                 "<a href=\"display_enter?force_room=_MAIL_&recp=");
 308                         output_length += 46;
 309                         ptr = &ptr[16];
 310                         ++alevel;
 311                         ++brak;
 312                 }
 313                 /** Make external links open in a separate window */
 314                 else if (!strncasecmp(ptr, "<a href=\"", 9)) {
 315                         ++alevel;
 316                         ++brak;
 317                         if ( ((strchr(ptr, ':') < strchr(ptr, '/')))
 318                              &&  ((strchr(ptr, '/') < strchr(ptr, '>')))
 319                              ) {
 320                                 /* open external links to new window */
 321                                 content_length += 64;
 322                                 if (content_length >= converted_alloc) {
 323                                         converted_alloc += 8192;
 324                                         converted_msg = realloc(converted_msg, converted_alloc);
 325                                         if (converted_msg == NULL) {
 326                                                 abort();
 327                                         }
 328                                 }
 329                                 sprintf(&converted_msg[output_length], new_window);
 330                                 output_length += strlen(new_window);
 331                                 ptr = &ptr[8];
 332                         }
 333                         else if ( (treat_as_wiki) && (strncasecmp(ptr, "<a href=\"wiki?", 14)) ) {
 334                                 content_length += 64;
 335                                 if (content_length >= converted_alloc) {
 336                                         converted_alloc += 8192;
 337                                         converted_msg = realloc(converted_msg, converted_alloc);
 338                                         if (converted_msg == NULL) {
 339                                                 abort();
 340                                         }
 341                                 }
 342                                 sprintf(&converted_msg[output_length], "<a href=\"wiki?page=");
 343                                 output_length += 19;
 344                                 ptr = &ptr[9];
 345                         }
 346                         else {
 347                                 sprintf(&converted_msg[output_length], "<a href=\"");
 348                                 output_length += 9;
 349                                 ptr = &ptr[9];
 350                         }
 351                 }
 352
 353                 /**
 354                  * Turn anything that looks like a URL into a real link, as long
 355                  * as it's not inside a tag already
 356                  */
 357                 else if ( (brak == 0) && (alevel == 0)
 358                      && (!strncasecmp(ptr, "http://", 7))) {
 359                                 /** Find the end of the link */
 360                                 int strlenptr;
 361                                 linklen = 0;
 362
 363                                 strlenptr = strlen(ptr);
 364                                 for (i=0; i<=strlenptr; ++i) {
 365                                         if ((ptr[i]==0)
 366                                            ||(isspace(ptr[i]))
 367                                            ||(ptr[i]==10)
 368                                            ||(ptr[i]==13)
 369                                            ||(ptr[i]=='(')
 370                                            ||(ptr[i]==')')
 371                                            ||(ptr[i]=='<')
 372                                            ||(ptr[i]=='>')
 373                                            ||(ptr[i]=='[')
 374                                            ||(ptr[i]==']')
 375                                            ||(ptr[i]=='"')
 376                                            ||(ptr[i]=='\'')
 377                                         ) linklen = i;
 378                                         /* did s.b. send us an entity? */
 379                                         if (ptr[i] == '&') {
 380                                                 if ((ptr[i+2] ==';') ||
 381                                                     (ptr[i+3] ==';') ||
 382                                                     (ptr[i+5] ==';') ||
 383                                                     (ptr[i+6] ==';') ||
 384                                                     (ptr[i+7] ==';'))
 385                                                         linklen = i;
 386                                         }
 387                                         if (linklen > 0) break;
 388                                 }
 389                                 if (linklen > 0) {
 390                                         char *ltreviewptr;
 391                                         char *nbspreviewptr;
 392                                         char linkedchar;
 393                                         int len = linklen;
 394
 395                                         len = linklen;
 396                                         linkedchar = ptr[len];
 397                                         ptr[len] = '\0';
 398                                         /* spot for some subject strings tinymce tends to give us. */
 399                                         ltreviewptr = strchr(ptr, '<');
 400                                         if (ltreviewptr != NULL) {
 401                                                 *ltreviewptr = '\0';
 402                                                 linklen = ltreviewptr - ptr;
 403                                         }
 404
 405                                         nbspreviewptr = strstr(ptr, "&nbsp;");
 406                                         if (nbspreviewptr != NULL) {
 407                                                 ///*nbspreviewptr = '\0';
 408                                                 linklen = nbspreviewptr - ptr;
 409                                         }
 410                                         if (ltreviewptr != 0)
 411                                                 *ltreviewptr = '<';
 412
 413                                         ptr[len] = linkedchar;
 414
 415                                         content_length += (32 + linklen);
 416                                         if (content_length >= converted_alloc) {
 417                                                 converted_alloc += 8192;
 418                                                 converted_msg = realloc(converted_msg, converted_alloc);
 419                                                 if (converted_msg == NULL) {
 420                                                         abort();
 421                                                 }
 422                                         }
 423                                         sprintf(&converted_msg[output_length], new_window);
 424                                         output_length += strlen(new_window);
 425                                         converted_msg[output_length] = '\"';
 426                                         converted_msg[++output_length] = 0;
 427                                         for (i=0; i<linklen; ++i) {
 428                                                 converted_msg[output_length] = ptr[i];
 429                                                 converted_msg[++output_length] = 0;
 430                                         }
 431                                         sprintf(&converted_msg[output_length], "\">");
 432                                         output_length += 2;
 433                                         for (i=0; i<linklen; ++i) {
 434                                                 converted_msg[output_length] = *ptr++;
 435                                                 converted_msg[++output_length] = 0;
 436                                         }
 437                                         sprintf(&converted_msg[output_length], "</A>");
 438                                         output_length += 4;
 439                                 }
 440                 }
 441                 else {
 442                         converted_msg[output_length] = *ptr++;
 443                         converted_msg[++output_length] = 0;
 444                 }
 445
 446                 /**
 447                  * We need to know when we're inside a tag,
 448                  * so we don't turn things that look like URL's into
 449                  * links, when they're already links - or image sources.
 450                  */
 451                 if (*(ptr-1) == '<') {
 452                         ++brak;
 453                 }
 454                 if (*(ptr-1) == '>') {
 455                         --brak;
 456                         if ((scriptlevel == 0) && (script_start_pos >= 0)) {
 457                                 output_length = script_start_pos;
 458                                 converted_msg[output_length] = 0;
 459                                 script_start_pos = (-1);
 460                         }
 461                 }
 462                 if (!strncasecmp(ptr, "</A>", 3)) --alevel;
 463         }
 464
 465         /**     uncomment these two lines to override conversion        */
 466         /**     memcpy(converted_msg, msg, content_length);             */
 467         /**     output_length = content_length;                         */
 468
 469         /** Output our big pile of markup */
 470         client_write(converted_msg, output_length);
 471
 472 BAIL:   /** A little trailing vertical whitespace... */
 473         wprintf("<br /><br />\n");
 474
 475         /** Now give back the memory */
 476         if (converted_msg != NULL) free(converted_msg);
 477         if (msg != NULL) free(msg);
 478 }
 479
 480 /*@}*/