devtools/gossipwith: expose the INIT messages.

Usually we send a canned INIT message and ignore theirs.  This adds
an option to not do that.

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

devtools/gossipwith.c

@@ -19,6 +19,7 @@
 #define io_read_ simple_read
 #define io_close simple_close
 static bool stream_stdin = false;
+static bool no_init = false;
 
 static struct io_plan *simple_write(struct io_conn *conn,
 				    const void *data, size_t len,
@@ -130,11 +131,13 @@ static struct io_plan *handshake_success(struct io_conn *conn,
 	} else
 		localfeatures = NULL;
 
+	if (!no_init) {
 		msg = towire_init(NULL, NULL, localfeatures);
 
 		sync_crypto_write(pps, take(msg));
 		/* Ignore their init message. */
 		tal_free(sync_crypto_read(NULL, pps));
+	}
 
 	if (stream_stdin)
 		pollfd[0].fd = STDIN_FILENO;
@@ -220,6 +223,8 @@ int main(int argc, char *argv[])
 			 "Terminate after reading this many messages (> 0)");
 	opt_register_noarg("--stdin", opt_set_bool, &stream_stdin,
 			   "Stream gossip messages from stdin.");
+	opt_register_noarg("--no-init", opt_set_bool, &no_init,
+			   "Don't send or swallow init messages.");
 	opt_register_arg("--privkey", opt_set_secret, opt_show_secret,
 			 &notsosecret,
 			 "Secret key to use for our identity");