Merge r1884505, r1915625 from trunk:

The Microsoft OOXML format uses xml packaged into a zip file, and has
mimetypes like:

application/vnd.openxmlformats-officedocument.spreadsheetml.sheet

This mimetypes contains 'xml', but is unfortunately not an xml file.

xml2enc processes these files (in particular, when mod_proxy_html is
used), typically resulting in them being corrupted as it seems to
attempt to perform a ISO-8859-1 to UTF-8 conversion on them.

* modules/filters/mod_xml2enc.c (xml2enc_ffunc): Restrict test for XML
  types to matching "+xml".

Submitted by: Joseph Heenan <joseph.heenan fintechlabs.io>, jorton
PR: 64339
Reviewed by: jorton, ylavic, gbechis
Github: closes #410


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1916412 13f79535-47bb-0310-9956-ffa450edef68

Author: notroj

changes-entries/pr64339.txt

@@ -0,0 +1,4 @@
+  *) mod_xml2enc: Update check to accept any text/ media type
+     or any XML media type per RFC 7303, avoiding
+     corruption of Microsoft OOXML formats.  PR 64339.
+     [Joseph Heenan <joseph.heenan fintechlabs.io>, Joe Orton]

modules/filters/mod_xml2enc.c

@@ -323,7 +323,7 @@ static apr_status_t xml2enc_ffunc(ap_filter_t* f, apr_bucket_brigade* bb)
     apr_bucket* bstart;
     apr_size_t insz = 0;
     int pending_meta = 0;
-    char *ctype;
+    char *mtype;
     char *p;
 
     if (!ctx || !f->r->content_type) {
@@ -332,13 +332,17 @@ static apr_status_t xml2enc_ffunc(ap_filter_t* f, apr_bucket_brigade* bb)
         return ap_pass_brigade(f->next, bb) ;
     }
 
-    ctype = apr_pstrdup(f->r->pool, f->r->content_type);
-    for (p = ctype; *p; ++p)
-        if (isupper(*p))
-            *p = tolower(*p);
-
-    /* only act if starts-with "text/" or contains "xml" */
-    if (strncmp(ctype, "text/", 5) && !strstr(ctype, "xml"))  {
+    /* Extract the media type, ignoring parameters in content-type. */
+    mtype = apr_pstrdup(f->r->pool, f->r->content_type);
+    if ((p = ap_strchr(mtype, ';')) != NULL) *p = '\0';
+    ap_str_tolower(mtype);
+
+    /* Accept text/ types, plus any XML media type per RFC 7303. */
+    if (!(strncmp(mtype, "text/", 5) == 0
+          || strcmp(mtype, "application/xml") == 0
+          || (strlen(mtype) > 7 /* minimum 'a/b+xml' length */
+              && (p = strstr(mtype, "+xml")) != NULL
+              && strlen(p) == 4 /* ensures +xml is a suffix */))) {
         ap_remove_output_filter(f);
         return ap_pass_brigade(f->next, bb) ;
     }