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html: Ignore ASCII-incompatible encoding in meta tag

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After successfully parsing an ASCII-encoded meta tag, switching to an
encoding that isn't ASCII-compatible cannot work.
This commit is contained in:
Nick Wellnhofer
2025-06-05 21:06:11 +02:00
parent 2b6b3945f2
commit c6206c9387
1 changed files with 60 additions and 7 deletions
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67
HTMLparser.c
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@@ -3614,6 +3614,50 @@ htmlParseAttribute(htmlParserCtxtPtr ctxt, xmlChar **value) {
return(hname);
}
static int
htmlCharEncCheckAsciiCompatible(htmlParserCtxt *ctxt,
const xmlChar *encoding) {
xmlCharEncodingHandler *handler;
xmlChar in[9] = "<a A=\"/>";
xmlChar out[9];
int inlen, outlen;
int res;
res = xmlCreateCharEncodingHandler(
(const char *) encoding,
XML_ENC_INPUT | XML_ENC_HTML,
ctxt->convImpl, ctxt->convCtxt,
&handler);
/*
* TODO: Unlike the XML parser, we shouldn't raise a fatal
* if the encoding is unsupported.
*/
if (res != XML_ERR_OK) {
xmlFatalErr(ctxt, res, (const char *) encoding);
return(-1);
}
/* UTF-8 */
if (handler == NULL)
return(0);
inlen = 8;
outlen = 8;
res = xmlEncInputChunk(handler, out, &outlen, in, &inlen, /* flush */ 1);
xmlCharEncCloseFunc(handler);
if ((res != XML_ENC_ERR_SUCCESS) ||
(inlen != 8) || (outlen != 8) ||
(memcmp(in, out, 8) != 0)) {
htmlParseErr(ctxt, XML_ERR_UNSUPPORTED_ENCODING,
"Encoding %s isn't ASCII-compatible", encoding, NULL);
return(-1);
}
return(0);
}
/**
* Handle charset encoding in meta tag.
*
@@ -3626,6 +3670,7 @@ htmlCheckMeta(htmlParserCtxtPtr ctxt, const xmlChar **atts) {
const xmlChar *att, *value;
int isContentType = 0;
const xmlChar *content = NULL;
xmlChar *encoding = NULL;
if ((ctxt == NULL) || (atts == NULL))
return;
@@ -3639,12 +3684,10 @@ htmlCheckMeta(htmlParserCtxtPtr ctxt, const xmlChar **atts) {
(!xmlStrcasecmp(value, BAD_CAST "Content-Type"))) {
isContentType = 1;
} else if (!xmlStrcasecmp(att, BAD_CAST "charset")) {
xmlChar *encoding;
encoding = xmlStrdup(value);
if (encoding == NULL)
htmlErrMemory(ctxt);
xmlSetDeclaredEncoding(ctxt, encoding);
break;
} else if (!xmlStrcasecmp(att, BAD_CAST "content")) {
content = value;
}
@@ -3652,18 +3695,28 @@ htmlCheckMeta(htmlParserCtxtPtr ctxt, const xmlChar **atts) {
att = atts[i++];
}
if ((isContentType) && (content != NULL)) {
if ((encoding == NULL) && (isContentType) && (content != NULL)) {
htmlMetaEncodingOffsets off;
if (htmlParseContentType(content, &off)) {
xmlChar *encoding;
encoding = xmlStrndup(content + off.start, off.end - off.start);
if (encoding == NULL)
htmlErrMemory(ctxt);
xmlSetDeclaredEncoding(ctxt, encoding);
}
}
if (encoding != NULL) {
if (htmlCharEncCheckAsciiCompatible(ctxt, encoding) < 0) {
xmlFree(encoding);
return;
}
/*
* TODO: Unlike the XML parser, we shouldn't raise a fatal
* if the encoding is unsupported.
*/
xmlSetDeclaredEncoding(ctxt, encoding);
}
}
/**