lightningd: --deprecated-api option to turn off deprecated APIs.

This can be used for upgrades to make sure you're not using deprecated
options, JSON commands, JSON fields, etc.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

lightningd/jsonrpc.c

@@ -16,6 +16,7 @@
 #include <lightningd/jsonrpc.h>
 #include <lightningd/lightningd.h>
 #include <lightningd/log.h>
+#include <lightningd/options.h>
 #include <stdio.h>
 #include <sys/socket.h>
 #include <sys/stat.h>
@@ -526,6 +527,13 @@ static void parse_request(struct json_connection *jcon, const jsmntok_t tok[])
 			     jcon->buffer + method->start);
 		return;
 	}
+	if (cmd->deprecated && !deprecated_apis) {
+		command_fail(jcon->current,
+			     "command '%.*s' is deprecated",
+			     (int)(method->end - method->start),
+			     jcon->buffer + method->start);
+		return;
+	}
 
 	if (params->type != JSMN_ARRAY && params->type != JSMN_OBJECT) {
 		command_fail(jcon->current,

lightningd/jsonrpc.h

@@ -53,6 +53,7 @@ struct json_command {
 			 const char *buffer, const jsmntok_t *params);
 	const char *description;
 	const char *help;
+	bool deprecated;
 };
 
 struct json_result *null_response(const tal_t *ctx);

lightningd/options.c

@@ -29,6 +29,8 @@
 #include <unistd.h>
 #include <wire/wire.h>
 
+bool deprecated_apis = true;
+
 /* Tal wrappers for opt. */
 static void *opt_allocfn(size_t size)
 {
@@ -269,6 +271,9 @@ static void config_register_opts(struct lightningd *ld)
 			       ld,
 			       "Select the network parameters (bitcoin, testnet,"
 			       " regtest, or litecoin)");
+	opt_register_arg("--deprecated-apis", opt_set_bool_arg, opt_show_bool,
+			 &deprecated_apis,
+			 "Enable deprecated options, JSONRPC commands, fields, etc.");
 }
 
 #if DEVELOPER

lightningd/options.h

@@ -15,4 +15,7 @@ bool handle_opts(struct lightningd *ld, int argc, char *argv[]);
 
 /* Derive default color and alias from the pubkey. */
 void setup_color_and_alias(struct lightningd *ld);
+
+/* Global to allow deprecated options. */
+extern bool deprecated_apis;
 #endif /* LIGHTNING_LIGHTNINGD_OPTIONS_H */