mod_negotiation: Do not send the qs parameter in the Content-Type.

changes-entries/negotiation-qs-content-type.txt

@@ -0,0 +1,2 @@
+  *) mod_negotiation: Do not send the "qs" source quality parameter of the selected
+     variant in the Content-Type of a response negotiated by MultiViews. PR 53595

modules/mappers/mod_negotiation.c

@@ -3068,6 +3068,41 @@ static int handle_map_file(request_rec *r)
     return OK;
 }
 
+/* The "qs" parameter of a variant's media type is only its source quality
+ * for the selection, see get_entry(), and does not belong in the
+ * Content-Type of the response.  Return content_type without it, all
+ * other parameters are kept as they are.
+ */
+static const char *strip_source_quality(apr_pool_t *p,
+                                        const char *content_type)
+{
+    const char *line = content_type;
+    char *stripped;
+    int found = 0;
+
+    if (!ap_strcasestr(content_type, "qs")) {
+        return content_type;
+    }
+
+    stripped = ap_get_token(p, &line, 0);
+    while (*line == ';') {
+        const char *param = line++;
+        const char *name = ap_get_token(p, &line, 1);
+        apr_size_t len = strcspn(name, "= \t");
+
+        if (len == 2 && name[len] && !ap_cstr_casecmpn(name, "qs", 2)) {
+            found = 1;
+        }
+        else {
+            stripped = apr_pstrcat(p, stripped,
+                                   apr_pstrmemdup(p, param, line - param),
+                                   NULL);
+        }
+    }
+
+    return found ? apr_pstrcat(p, stripped, line, NULL) : content_type;
+}
+
 static int handle_multi(request_rec *r)
 {
     negotiation_state *neg;
@@ -3124,6 +3159,14 @@ static int handle_multi(request_rec *r)
     /* now do a "fast redirect" ... promotes the sub_req into the main req */
     ap_internal_fast_redirect(sub_req, r);
 
+    if (r->content_type) {
+        const char *type = strip_source_quality(r->pool, r->content_type);
+
+        if (type != r->content_type) {
+            ap_set_content_type_ex(r, type, AP_REQUEST_IS_TRUSTED_CT(r));
+        }
+    }
+
     /* give no advise for time on this subrequest.  Perhaps we
      * should tally the last mtime among all variants, and date
      * the most recent, but that could confuse the proxies.

test/pytest_suite/t/conf/extra.conf.in

@@ -135,6 +135,15 @@
         LanguagePriority zh-TW fr fu en de 
     </Directory>
 
+    <Directory @SERVERROOT@/htdocs/modules/negotiation/qs>
+        Options +MultiViews
+        AddType text/html;qs=0.9 .html
+        AddType application/xhtml+xml;qs=1.0 .xhtml
+        AddType "text/html;charset=utf-8;qs=0.8" .qsafter
+        AddType "text/html;QS=0.8;charset=utf-8" .qsbefore
+        AddType "application/example;foo=\"a;b\";q=0.7;qs=0.5;bar=\"c, d\"" .quoted
+    </Directory>
+
    <IfDefine APACHE2>
        <IfModule @CGI_MODULE@>
             <Directory @SERVERROOT@/htdocs/modules/negotiation/query>

test/pytest_suite/t/htdocs/modules/negotiation/qs/after.qsafter

@@ -0,0 +1 @@
+after

test/pytest_suite/t/htdocs/modules/negotiation/qs/before.qsbefore

@@ -0,0 +1 @@
+before

test/pytest_suite/t/htdocs/modules/negotiation/qs/doc.html

@@ -0,0 +1 @@
+html

test/pytest_suite/t/htdocs/modules/negotiation/qs/doc.xhtml

@@ -0,0 +1 @@
+xhtml

test/pytest_suite/t/htdocs/modules/negotiation/qs/quoted.quoted

@@ -0,0 +1 @@
+quoted

test/pytest_suite/t/htdocs/modules/negotiation/qs/tm1.htm

@@ -0,0 +1 @@
+html

test/pytest_suite/t/htdocs/modules/negotiation/qs/tm2.xht

@@ -0,0 +1 @@
+xht

test/pytest_suite/t/htdocs/modules/negotiation/qs/typemap.var

@@ -0,0 +1,5 @@
+URI: tm1.htm
+Content-Type: text/html; qs=0.9
+
+URI: tm2.xht
+Content-Type: application/xhtml+xml; qs=1.0

test/pytest_suite/tests/t/modules/test_negotiation.py

@@ -3,12 +3,15 @@
 Covers default-language selection, explicit variant requests, Accept-Language
 obedience (plain + compressed + typemap), quality-rating preferences, a
 non-existent highest-quality fallback, a typemap query-string case, and
-Accept content-type negotiation (with 406 cases).
+Accept content-type negotiation (with 406 cases), and the source quality
+("qs") of a variant not showing up in the Content-Type of the response.
 
 Perl original used ``need_module('negotiation') && need_cgi &&
 need_module('mime')``.
 """
 
+import re
+
 import pytest
 
 from apache_pytest import need_cgi, need_module, t_cmp
@@ -153,3 +156,39 @@ def test_content_type(http, accept, expected):
     else:
         assert t_cmp(r.status_code, 406), \
             f"expect Not Acceptable for Accept: {accept}"
+
+
+XML = "application/xhtml+xml"
+
+# "qs" only decides between variants, the other parameters are kept
+QS_PARAMS = [
+    ("after", "text/html;charset=utf-8"),
+    ("before", "text/html;charset=utf-8"),
+    ("quoted", 'application/example;foo="a;b";q=0.7;bar="c, d"'),
+]
+
+
+def _content_type(resp):
+    assert resp.status_code == 200
+    return re.sub(r";\s+", ";", resp.headers["content-type"])
+
+
+@need_module("negotiation", "mime")
+@pytest.mark.parametrize("path", ["doc", "typemap.var"])
+@pytest.mark.parametrize("accept,expected", [
+    (f"text/html, {XML}", XML),
+    ("text/html", "text/html"),
+    (f"text/html, {XML};q=0.5", "text/html"),
+])
+def test_source_quality(http, path, accept, expected):
+    r = http.GET(f"/modules/negotiation/qs/{path}", headers={"Accept": accept})
+    assert t_cmp(_content_type(r), expected), \
+        "qs selects the variant but is not sent in Content-Type"
+
+
+@need_module("negotiation", "mime")
+@pytest.mark.parametrize("name,expected", QS_PARAMS, ids=[n for n, _ in QS_PARAMS])
+def test_source_quality_parameters(http, name, expected):
+    r = http.GET(f"/modules/negotiation/qs/{name}", headers={"Accept": "*/*"})
+    assert t_cmp(_content_type(r), expected), \
+        "only qs is removed from the Content-Type"