Terminate OPTIONS request without sending it to the backend.

[aleskiontherun]

Fixes #6

[NickMRamirez]

Thanks for the pull request @Dizeee. Unfortunately, in its current state, this does not work because it doesn't send back the Access-Control-Allow-Methods response header for an OPTIONS request.

[aleskiontherun]

@NickMRamirez I tested with HAProxy 2.1.4, and it does. Access-Control-Allow-Methods header is added by preflight_request function, which is executed before returning the response.

[erolg]

@Dizeee

It works but I got the following alert:

haproxy[1414]: [ALERT] 226/212022 (7638) : Lua applet http '<lua.empty-response>': runtime error: /var/lib/haproxy/cors.lua:91: bad argument #1 to 'send' (string expected, got nil) from [C] method 'send', /var/lib/haproxy/cors.lua:91 C function line 87.

Alert gone when I changed send function like that: applet:send("")

[NickMRamirez]

I've updated the module to terminate preflight requests using the new Reply object in the HAProxy Lua library, but it does require HAProxy 2.2. #15