mod_dav: Do not advertise disabled TRACE

dav_method_options() builds its own Allow field and unconditionally
advertised TRACE for existing DAV resources, even when TraceEnable was
off.

Respect TraceEnable when constructing the DAV Allow field.

PR: 70264
GitHub: closes #827


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1939146 13f79535-47bb-0310-9956-ffa450edef68

changes-entries/dav-options-trace.txt

@@ -0,0 +1,2 @@
+  *) mod_dav: Do not list TRACE in the Allow field of an OPTIONS response when
+     TraceEnable is off. PR 70264

modules/dav/main/mod_dav.c

@@ -1844,6 +1844,8 @@ static int dav_method_search(request_rec *r)
 /* handle the OPTIONS method */
 static int dav_method_options(request_rec *r)
 {
+    core_server_config *conf =
+        ap_get_core_module_config(r->server->module_config);
     const dav_hooks_locks *locks_hooks = DAV_GET_HOOKS_LOCKS(r);
     const dav_hooks_vsn *vsn_hooks = DAV_GET_HOOKS_VSN(r);
     const dav_hooks_binding *binding_hooks = DAV_GET_HOOKS_BINDING(r);
@@ -1975,7 +1977,9 @@ static int dav_method_options(request_rec *r)
         apr_table_addn(methods, "HEAD", "");
         apr_table_addn(methods, "POST", "");
         apr_table_addn(methods, "DELETE", "");
-        apr_table_addn(methods, "TRACE", "");
+        if (conf->trace_enable != AP_TRACE_DISABLE) {
+            apr_table_addn(methods, "TRACE", "");
+        }
         apr_table_addn(methods, "PROPFIND", "");
         apr_table_addn(methods, "PROPPATCH", "");
         apr_table_addn(methods, "COPY", "");

test/modules/dav/test_002_options_trace.py

@@ -0,0 +1,75 @@
+import os
+
+import pytest
+
+from pyhttpd.conf import HttpdConf
+
+DAV_METHODS = {"OPTIONS", "GET", "HEAD", "POST", "DELETE", "PROPFIND",
+               "PROPPATCH", "COPY", "MOVE", "LOCK", "UNLOCK"}
+
+
+def _setup(env, trace):
+    dav_dir = os.path.join(env.gen_dir, 'dav')
+    os.makedirs(os.path.join(dav_dir, 'col'), exist_ok=True)
+    with open(os.path.join(dav_dir, 'file.txt'), 'w') as fd:
+        fd.write('hello\n')
+    conf = HttpdConf(env, extras={
+        'base': f"""
+        DavLockDB "{env.gen_dir}/davlock"
+        TraceEnable {trace}
+        """,
+        f"test1.{env.http_tld}": f"""
+        Alias /dav "{dav_dir}"
+        <Directory "{dav_dir}">
+            Dav On
+            Require all granted
+        </Directory>
+        """,
+    })
+    conf.add_vhost_test1()
+    conf.install()
+    assert env.apache_restart() == 0
+
+
+def _request(env, method, path):
+    r = env.curl_raw(env.mkurl("https", "test1", path),
+                     options=['-X', method])
+    assert r.response, f"no response: {r.stderr}"
+    allow = r.response["header"].get("allow", "")
+    return r.response["status"], {m.strip() for m in allow.split(',') if m.strip()}
+
+
+class TestOptionsTraceDisabled:
+
+    @pytest.fixture(autouse=True, scope='class')
+    def _class_scope(self, env):
+        _setup(env, "off")
+
+    # TRACE is not offered while the server refuses it
+    @pytest.mark.parametrize("path", ["/dav/file.txt", "/dav/col/"])
+    def test_dav_002_001(self, env, path):
+        status, allow = _request(env, "OPTIONS", path)
+        assert status == 200
+        assert "TRACE" not in allow, f"Allow: {allow}"
+        assert DAV_METHODS <= allow, f"Allow: {allow}"
+
+    def test_dav_002_002(self, env):
+        assert _request(env, "TRACE", "/dav/file.txt")[0] == 405
+
+
+class TestOptionsTraceEnabled:
+
+    @pytest.fixture(autouse=True, scope='class',
+                    params=["on", "extended"])
+    def _class_scope(self, env, request):
+        _setup(env, request.param)
+
+    # unchanged: TRACE is offered and works
+    @pytest.mark.parametrize("path", ["/dav/file.txt", "/dav/col/"])
+    def test_dav_002_101(self, env, path):
+        status, allow = _request(env, "OPTIONS", path)
+        assert status == 200
+        assert (DAV_METHODS | {"TRACE"}) <= allow, f"Allow: {allow}"
+
+    def test_dav_002_102(self, env):
+        assert _request(env, "TRACE", "/dav/file.txt")[0] == 200