[FIX] http_routing: should redirect only for multilang

Define a route that is website but not multilang, e.g.

    @route('/example', website=True, multilang=False)

Login to the frontend, change the website lang to another (non-default)
lang (e.g. install french, keep english as default lang, log in the
french website) then access the '/example' controller by typing it
directly in your address bar.

You are being redirected to '/fr/example', you should not.

This commit restore the behavior pre-httpocalypse, that is the address
is kept as-is.

Note: in the comment, the 4th and 5th cases were inverted, we use this
commit as an opportunity to reorder the two.

closes odoo/odoo#105686

X-original-commit: be7a02917a66136a8d3b601d61a898b0419ff79d
Signed-off-by: Julien Castiaux <juc@odoo.com>

addons/http_routing/models/ir_http.py

@@ -369,14 +369,14 @@ class IrHttp(models.AbstractModel):
         3/ Use the URL as-is saving the requested lang when the user is
            a bot and that the lang is missing from the URL.
 
-        4/ Redirect the browser when the lang is missing from the URL
-           but another lang than the default one has been requested. The
-           requested lang is injected before the original path.
-
-        5) Use the url as-is when the lang is missing from the URL, that
+        4) Use the url as-is when the lang is missing from the URL, that
            another lang than the default one has been requested but that
            it is forbidden to redirect (e.g. POST)
 
+        5/ Redirect the browser when the lang is missing from the URL
+           but another lang than the default one has been requested. The
+           requested lang is injected before the original path.
+
         6/ Redirect the browser when the lang is present in the URL but
            it is the default lang. The lang is removed from the original
            URL.
@@ -415,7 +415,11 @@ class IrHttp(models.AbstractModel):
         else:
             url_lang_str = ''
             path_no_lang = path
-        allow_redirect = request.httprequest.method != 'POST'
+
+        allow_redirect = (
+            request.httprequest.method != 'POST'
+            and getattr(request, 'is_frontend_multilang', True)
+        )
 
         # There is no user on the environment yet but the following code
         # requires one to set the lang on the request. Temporary grant

addons/test_website/tests/test_is_multilang.py

@@ -57,6 +57,7 @@ class TestIsMultiLang(odoo.tests.HttpCase):
         it_href = body.find('./head/link[@rel="alternate"][@hreflang="it"]').get('href')
         fr_href = body.find('./head/link[@rel="alternate"][@hreflang="fr"]').get('href')
         en_href = body.find('./head/link[@rel="alternate"][@hreflang="en"]').get('href')
+
         self.assertEqual(urlparse(it_href).path, f'/{it.url_code}/test_lang_url/my-super-country-italia-{country1.id}')
         self.assertEqual(urlparse(fr_href).path, f'/{be.url_code}/test_lang_url/my-super-country-belgium-{country1.id}')
         self.assertEqual(urlparse(en_href).path, f'/test_lang_url/my-super-country-{country1.id}')
@@ -79,3 +80,18 @@ class TestIsMultiLang(odoo.tests.HttpCase):
         self.assertRegex(r.text, r'<link rel="alternate" hreflang="en" href="http://[^"]+/"/>')
         r = self.url_open(be_prefix + '/contactus')
         self.assertRegex(r.text, r'<link rel="alternate" hreflang="en" href="http://[^"]+/contactus"/>')
+
+    def test_04_multilang_false(self):
+        website = self.env['website'].search([], limit=1)
+        fr = self.env.ref('base.lang_fr').sudo()
+        en = self.env.ref('base.lang_en').sudo()
+        fr.active = True
+
+        website.default_lang_id = en
+        website.language_ids = en + fr
+        self.opener.cookies['frontend_lang'] = fr.iso_code
+
+        res = self.url_open('/get_post_nomultilang', allow_redirects=False)
+        res.raise_for_status()
+
+        self.assertEqual(res.status_code, 200, "Should not be redirected")