properly send close_notify after the response

This is already mandated by the TLS spec, but has been made explicit as
well for Gemini servers[1]:

> As per RFCs 5246 and 8446, Gemini servers MUST send a TLS
> `close_notify` prior to closing the connection after sending a
> complete response. This is essential to disambiguate completed
> responses from responses closed prematurely due to network error or
> attack.

We want to be well-behaved, therefore we now send close_notify properly
after writing a response.

You can verify this easily using [2].

[1] https://gemini.circumlunar.space/docs/specification.html
[2] https://portal.mozz.us/

1 files changed, 6 insertions, 1 deletions

diff --git a/src/Cana.hs b/src/Cana.hs
index 2e616ac..4d5c4d2 100644
--- a/src/Cana.hs
+++ b/src/Cana.hs
@@ -171,8 +171,13 @@ canaClient socket = do
         }
 
 -- | Render a response and write it to the TLS encrypted socket.
+--
+-- Note that this function also sends the TLS @close_notify@, as mandated by
+-- the TLS and the Gemini specifications.
 writeResponse :: TLS.Context -> GeminiResponse -> Cana ()
-writeResponse context = TLS.sendData context . renderResponse
+writeResponse context response = do
+  TLS.sendData context $ renderResponse response
+  TLS.bye context
 
 -- | Find the fitting route for the given request.
 findRoute :: GeminiRequest -> Cana (Maybe Handler)