# HG changeset patch
# User Kim Alvefur <zash@zash.se>
# Date 1683037420 -7200
# Node ID 1087f697c3f34f7750cc5770003fa4b5eb95f2b0
# Parent  c574aaaa4d573f2734ffc71f452b63c2d7761c55
mod_http_oauth2: Strip unknown extra fields from client registration

We shouldn't sign things we don't understand!

RFC 7591 section-2 states:
> The authorization server MUST ignore any client metadata sent by the
> client that it does not understand (for instance, by silently removing
> unknown metadata from the client's registration record during
> processing).

Prevents grandfathering in of unvalidated data that might become used
later, especially since the 'additionalProperties' schema keyword was
removed in 698fef74ce53

diff -r c574aaaa4d57 -r 1087f697c3f3 mod_http_oauth2/mod_http_oauth2.lua
--- a/mod_http_oauth2/mod_http_oauth2.lua	Tue May 02 16:23:05 2023 +0200
+++ b/mod_http_oauth2/mod_http_oauth2.lua	Tue May 02 16:23:40 2023 +0200
@@ -772,9 +772,13 @@
 		end
 	end
 
-	-- Localized URIs should be secure too
 	for k, v in pairs(client_metadata) do
-		if k:find"_uri#" then
+		local base_k = k:match"^([^#]+)#" or k;
+		if not registration_schema.properties[base_k] or k:find"^client_uri#" then
+			-- Ignore and strip unknown extra properties
+			client_metadata[k] = nil;
+		elseif k:find"_uri#" then
+			-- Localized URIs should be secure too
 			if not redirect_uri_allowed(v, client_uri, "web") then
 				return nil, oauth_error("invalid_client_metadata", "Invalid, insecure or inappropriate informative URI");
 			end