res_ari: Add support for channel variables in ARI events.

This works the same as for AMI manager variables. Set
"channelvars=foo,bar" in your ari.conf general section, and then the
channel variables "foo" and "bar" (along with their values), will
appear in every Stasis websocket channel event.

ASTERISK-26492 #close
patches:
  ari_vars.diff submitted by Mark Michelson

Change-Id: I5609ba239259577c0948645df776d7f3bc864229

res/ari/config.c

@@ -26,6 +26,8 @@
 
 #include "asterisk/config_options.h"
 #include "asterisk/http_websocket.h"
+#include "asterisk/app.h"
+#include "asterisk/channel.h"
 #include "internal.h"
 
 /*! \brief Locking container for safe configuration access. */
@@ -316,6 +318,22 @@ static int process_config(int reload)
 	return 0;
 }
 
+#define MAX_VARS 128
+
+static int channelvars_handler(const struct aco_option *opt, struct ast_variable *var, void *obj)
+{
+	char *parse = NULL;
+	AST_DECLARE_APP_ARGS(args,
+		AST_APP_ARG(vars)[MAX_VARS];
+	);
+
+	parse = ast_strdupa(var->value);
+	AST_STANDARD_APP_ARGS(args, parse);
+
+	ast_channel_set_ari_vars(args.argc, args.vars);
+	return 0;
+}
+
 int ast_ari_config_init(void)
 {
 	if (aco_info_init(&cfg_info)) {
@@ -339,6 +357,8 @@ int ast_ari_config_init(void)
 	aco_option_register(&cfg_info, "websocket_write_timeout", ACO_EXACT, general_options,
 		AST_DEFAULT_WEBSOCKET_WRITE_TIMEOUT_STR, OPT_INT_T, PARSE_IN_RANGE,
 		FLDSET(struct ast_ari_conf_general, write_timeout), 1, INT_MAX);
+	aco_option_register_custom(&cfg_info, "channelvars", ACO_EXACT, general_options,
+		"", channelvars_handler, 0);
 
 	/* ARI type=user category options */
 	aco_option_register(&cfg_info, "type", ACO_EXACT, user, NULL,