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