ubus: add CORS header support

In order to support cross-domain AJAX requests to the /ubus endpoint
we need to implement the Cross-Origin Resource Sharing (CORS) spec
in the ubus plugin.

- Implement a new option "-X" to enable CORS support in ubus
- Implement rudimentary support for "OPTIONS" HTTP requests
- Implement essential CORS headers the ubus plugin

The current CORS response headers merely reflect the request headers
sent by the client, this way any requesting origin is automatically
allowed. Cross-domain cookies (Access-Control-Allow-Credentials) are
unconditionally enabled.

Restricting permitted origins and toggle the credential accepting can
be made configurable in a future commit to allow more fine grained
control over permitted AJAX clients.

Signed-off-by: Jo-Philipp Wich <jow@openwrt.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/utils.c b/utils.c
index b1d7d37..1c21fc5 100644
--- a/utils.c
+++ b/utils.c
@@ -25,7 +25,7 @@ bool uh_use_chunked(struct client *cl)
 	if (cl->request.version != UH_HTTP_VER_1_1)
 		return false;
 
-	if (cl->request.method == UH_HTTP_MSG_HEAD)
+	if (cl->request.method == UH_HTTP_MSG_HEAD || cl->request.method == UH_HTTP_MSG_OPTIONS)
 		return false;
 
 	return true;