res/ari: Register Stasis application on WebSocket attempt

Prior to this patch, when a WebSocket connection is made, ARI would not
be informed of the connection until after the WebSocket layer had
accepted the connection. This created a brief race condition where the
ARI client would be notified that it was connected, a channel would be
sent into the Stasis dialplan application, but ARI would not yet have
registered the Stasis application presented in the HTTP request that
established the WebSocket.

This patch resolves this issue by doing the following:
 * When a WebSocket attempt is made, a callback is made into the ARI
   application layer, which verifies and registers the apps presented in
   the HTTP request. Because we do not yet have a WebSocket, we cannot
   have an event session for the corresponding applications. Some
   defensive checks were thus added to make the application objects
   tolerant to a NULL event session.
 * When a WebSocket connection is made, the registered application is
   updated with the newly created event session that wraps the WebSocket
   connection.

ASTERISK-24988 #close
Reported by: Joshua Colp

Change-Id: Ia5dc60dc2b6bee76cd5aff0f69dd53b36e83f636

2 files changed, 78 insertions, 11 deletions

diff --git a/rest-api-templates/ari_resource.h.mustache b/rest-api-templates/ari_resource.h.mustache
index 3a20776a7..d3f40b6bd 100644
--- a/rest-api-templates/ari_resource.h.mustache
+++ b/rest-api-templates/ari_resource.h.mustache
@@ -89,6 +89,23 @@ int ast_ari_{{c_name}}_{{c_nickname}}_parse_body(
 void ast_ari_{{c_name}}_{{c_nickname}}(struct ast_variable *headers, struct ast_ari_{{c_name}}_{{c_nickname}}_args *args, struct ast_ari_response *response);
 {{/is_req}}
 {{#is_websocket}}
+
+/*!
+ * \brief {{summary}}
+{{#notes}}
+ *
+ * {{{notes}}}
+{{/notes}}
+ *
+ * \param ser HTTP TCP/TLS Server Session
+ * \param headers HTTP headers
+ * \param args Swagger parameters
+ *
+ * \retval 0 success
+ * \retval non-zero error
+ */
+int ast_ari_websocket_{{c_name}}_{{c_nickname}}_attempted(struct ast_tcptls_session_instance *ser, struct ast_variable *headers, struct ast_ari_{{c_name}}_{{c_nickname}}_args *args);
+
 /*!
  * \brief {{summary}}
 {{#notes}}
@@ -100,7 +117,7 @@ void ast_ari_{{c_name}}_{{c_nickname}}(struct ast_variable *headers, struct ast_
  * \param headers HTTP headers.
  * \param args Swagger parameters.
  */
-void ast_ari_websocket_{{c_name}}_{{c_nickname}}(struct ast_ari_websocket_session *session, struct ast_variable *headers, struct ast_ari_{{c_name}}_{{c_nickname}}_args *args);
+void ast_ari_websocket_{{c_name}}_{{c_nickname}}_established(struct ast_ari_websocket_session *session, struct ast_variable *headers, struct ast_ari_{{c_name}}_{{c_nickname}}_args *args);
 {{/is_websocket}}
 {{/operations}}
 {{/apis}}
diff --git a/rest-api-templates/res_ari_resource.c.mustache b/rest-api-templates/res_ari_resource.c.mustache
index 7d138b7af..7fe360e89 100644
--- a/rest-api-templates/res_ari_resource.c.mustache
+++ b/rest-api-templates/res_ari_resource.c.mustache
@@ -137,7 +137,52 @@ fin: __attribute__((unused))
 }
 {{/is_req}}
 {{#is_websocket}}
-static void ast_ari_{{c_name}}_{{c_nickname}}_ws_cb(struct ast_websocket *ws_session,
+static int ast_ari_{{c_name}}_{{c_nickname}}_ws_attempted_cb(struct ast_tcptls_session_instance *ser, struct ast_variable *get_params, struct ast_variable *headers)
+{
+	struct ast_ari_{{c_name}}_{{c_nickname}}_args args = {};
+{{#has_parameters}}
+	int res = 0;
+	RAII_VAR(struct ast_ari_response *, response, NULL, ast_free);
+	struct ast_variable *i;
+{{/has_parameters}}
+
+{{#has_parameters}}
+	response = ast_calloc(1, sizeof(*response));
+	if (!response) {
+		ast_log(LOG_ERROR, "Failed to create response.\n");
+		goto fin;
+	}
+{{/has_parameters}}
+
+{{> param_parsing}}
+
+	res = ast_ari_websocket_{{c_name}}_{{c_nickname}}_attempted(ser, headers, &args);
+
+fin: __attribute__((unused))
+	if (!response) {
+		ast_http_error(ser, 500, "Server Error", "Memory allocation error");
+		res = -1;
+	} else if (response->response_code != 0) {
+		/* Param parsing failure */
+		RAII_VAR(char *, msg, NULL, ast_json_free);
+		if (response->message) {
+			msg = ast_json_dump_string(response->message);
+		} else {
+			ast_log(LOG_ERROR, "Missing response message\n");
+		}
+
+		if (msg) {
+			ast_http_error(ser, response->response_code, response->response_text, msg);
+		}
+		res = -1;
+	}
+{{> param_cleanup}}
+{{#has_parameters}}
+	return res;
+{{/has_parameters}}
+}
+
+static void ast_ari_{{c_name}}_{{c_nickname}}_ws_established_cb(struct ast_websocket *ws_session,
 	struct ast_variable *get_params, struct ast_variable *headers)
 {
 	struct ast_ari_{{c_name}}_{{c_nickname}}_args args = {};
@@ -175,16 +220,11 @@ static void ast_ari_{{c_name}}_{{c_nickname}}_ws_cb(struct ast_websocket *ws_ses
 
 {{> param_parsing}}
 
-	ast_ari_websocket_{{c_name}}_{{c_nickname}}(session, headers, &args);
+	ast_ari_websocket_{{c_name}}_{{c_nickname}}_established(session, headers, &args);
 
 fin: __attribute__((unused))
 	if (response && response->response_code != 0) {
 		/* Param parsing failure */
-		/* TODO - ideally, this would return the error code to the
-		 * HTTP client; but we've already done the WebSocket
-		 * negotiation. Param parsing should happen earlier, but we
-		 * need a way to pass it through the WebSocket code to the
-		 * callback */
 		RAII_VAR(char *, msg, NULL, ast_json_free);
 		if (response->message) {
 			msg = ast_json_dump_string(response->message);
@@ -211,16 +251,26 @@ static int load_module(void)
 {
 	int res = 0;
 {{#apis}}
+{{#operations}}
 {{#has_websocket}}
+	struct ast_websocket_protocol *protocol;
+
 	{{full_name}}.ws_server = ast_websocket_server_create();
 	if (!{{full_name}}.ws_server) {
 		return AST_MODULE_LOAD_FAILURE;
 	}
+
+	protocol = ast_websocket_sub_protocol_alloc("{{websocket_protocol}}");
+	if (!protocol) {
+		ao2_ref({{full_name}}.ws_server, -1);
+		{{full_name}}.ws_server = NULL;
+		return AST_MODULE_LOAD_FAILURE;
+	}
+	protocol->session_attempted = ast_ari_{{c_name}}_{{c_nickname}}_ws_attempted_cb;
+	protocol->session_established = ast_ari_{{c_name}}_{{c_nickname}}_ws_established_cb;
 {{/has_websocket}}
-{{#operations}}
 {{#is_websocket}}
-	res |= ast_websocket_server_add_protocol({{full_name}}.ws_server,
-		"{{websocket_protocol}}", ast_ari_{{c_name}}_{{c_nickname}}_ws_cb);
+	res |= ast_websocket_server_add_protocol2({{full_name}}.ws_server, protocol);
 {{/is_websocket}}
 {{/operations}}
 {{/apis}}