Subject: Direct extension confirmation to the negotiated protocol's callback

Fixes #897

Notice this means if you want to globally ban an extension, you should
no longer include the extension at context creation time.

lib/libwebsockets.h

@@ -1016,8 +1016,7 @@ enum lws_callback_reasons {
 	 * and with in being the extension name, len is 0 and user is
 	 * valid.  Note though at this time the ESTABLISHED callback hasn't
 	 * happened yet so if you initialize user content there, user
-	 * content during this callback might not be useful for anything.
-	 * Notice this callback comes to protocols[0]. */
+	 * content during this callback might not be useful for anything. */
 	LWS_CALLBACK_CLIENT_CONFIRM_EXTENSION_SUPPORTED		= 26,
 	/**< When a client
 	 * connection is being prepared to start a handshake to a server,

lib/server-handshake.c

@@ -128,7 +128,7 @@ lws_extension_server_handshake(struct lws *wsi, char **p, int budget)
 			 * ask user code if it's OK to apply it on this
 			 * particular connection + protocol
 			 */
-			m = wsi->vhost->protocols[0].callback(wsi,
+			m = (wsi->protocol->callback)(wsi,
 				LWS_CALLBACK_CONFIRM_EXTENSION_OKAY,
 				wsi->user_space, ext_name, 0);
 

test-server/test-echo.c

@@ -168,11 +168,6 @@ do_rx:
 		}
 		break;
 #endif
-	case LWS_CALLBACK_CLIENT_CONFIRM_EXTENSION_SUPPORTED:
-		/* reject everything else except permessage-deflate */
-		if (strcmp(in, "permessage-deflate"))
-			return 1;
-		break;
 
 	default:
 		break;
@@ -203,11 +198,6 @@ static const struct lws_extension exts[] = {
 		lws_extension_callback_pm_deflate,
 		"permessage-deflate; client_no_context_takeover; client_max_window_bits"
 	},
-	{
-		"deflate-frame",
-		lws_extension_callback_pm_deflate,
-		"deflate_frame"
-	},
 	{ NULL, NULL, NULL /* terminator */ }
 };