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Fix recovery from invalid HTML start tags

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Only try to parse a start tag if there's a '<' followed by an ASCII
letter. This is more in line with HTML5 and the old behavior in
recovery mode. Emit a literal '<' if the following character is
invalid.

Fixes #101.
Fixes #339.
This commit is contained in:
Nick Wellnhofer
2022-02-22 18:15:53 +01:00
parent b057239b3f
commit 4fd69f3e27
1 changed files with 21 additions and 23 deletions
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44
HTMLparser.c
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@ -3960,26 +3960,6 @@ htmlParseStartTag(htmlParserCtxtPtr ctxt) {
htmlParseErr(ctxt, XML_ERR_NAME_REQUIRED,
"htmlParseStartTag: invalid element name\n",
NULL, NULL);
/*
* The recovery code is disabled for now as it can result in
* quadratic behavior with the push parser. htmlParseStartTag
* must consume all content up to the final '>' in order to avoid
* rescanning for this terminator.
*
* For a proper fix in line with HTML5, htmlParseStartTag and
* htmlParseElement should only be called when there's an ASCII
* alpha character following the initial '<'. Otherwise, the '<'
* should be emitted as text (unless followed by '!', '/' or '?').
*/
#if 0
/* if recover preserve text on classic misconstructs */
if ((ctxt->recovery) && ((IS_BLANK_CH(CUR)) || (CUR == '<') ||
(CUR == '=') || (CUR == '>') || (((CUR >= '0') && (CUR <= '9'))))) {
htmlParseCharDataInternal(ctxt, '<');
return(-1);
}
#endif
/* Dump the bogus tag like browsers do */
while ((CUR != 0) && (CUR != '>') &&
(ctxt->instate != XML_PARSER_EOF))
@ -4432,9 +4412,15 @@ htmlParseContent(htmlParserCtxtPtr ctxt) {
/*
* Third case : a sub-element.
*/
else if (CUR == '<') {
else if ((CUR == '<') && IS_ASCII_LETTER(NXT(1))) {
htmlParseElement(ctxt);
}
else if (CUR == '<') {
if ((ctxt->sax != NULL) && (!ctxt->disableSAX) &&
(ctxt->sax->characters != NULL))
ctxt->sax->characters(ctxt->userData, BAD_CAST "<", 1);
NEXT;
}
/*
* Fourth case : a reference. If if has not been resolved,
@ -4831,13 +4817,19 @@ htmlParseContentInternal(htmlParserCtxtPtr ctxt) {
/*
* Third case : a sub-element.
*/
else if (CUR == '<') {
else if ((CUR == '<') && IS_ASCII_LETTER(NXT(1))) {
htmlParseElementInternal(ctxt);
if (currentNode != NULL) xmlFree(currentNode);
currentNode = xmlStrdup(ctxt->name);
depth = ctxt->nameNr;
}
else if (CUR == '<') {
if ((ctxt->sax != NULL) && (!ctxt->disableSAX) &&
(ctxt->sax->characters != NULL))
ctxt->sax->characters(ctxt->userData, BAD_CAST "<", 1);
NEXT;
}
/*
* Fourth case : a reference. If if has not been resolved,
@ -6004,7 +5996,7 @@ htmlParseTryOrFinish(htmlParserCtxtPtr ctxt, int terminate) {
"HPP: entering END_TAG\n");
#endif
break;
} else if (cur == '<') {
} else if ((cur == '<') && IS_ASCII_LETTER(next)) {
if ((!terminate) && (next == 0))
goto done;
ctxt->instate = XML_PARSER_START_TAG;
@ -6014,6 +6006,12 @@ htmlParseTryOrFinish(htmlParserCtxtPtr ctxt, int terminate) {
"HPP: entering START_TAG\n");
#endif
break;
} else if (cur == '<') {
if ((ctxt->sax != NULL) && (!ctxt->disableSAX) &&
(ctxt->sax->characters != NULL))
ctxt->sax->characters(ctxt->userData,
BAD_CAST "<", 1);
NEXT;
} else {
/*
* check that the text sequence is complete