Fix the "network" command in tinc shell.

src/names.c

@@ -137,4 +137,12 @@ void free_names(void) {
 	free(logfilename);
 	free(confbase);
 	free(confdir);
+
+	identname = NULL;
+	netname = NULL;
+	unixsocketname = NULL;
+	pidfilename = NULL;
+	logfilename = NULL;
+	confbase = NULL;
+	confdir = NULL;
 }

src/tincctl.c

@@ -2284,26 +2284,29 @@ static int cmd_exchange_all(int argc, char *argv[]) {
 }
 
 static int switch_network(char *name) {
+	if(strcmp(name, ".")) {
+		if(!check_netname(name, false)) {
+			fprintf(stderr, "Invalid character in netname!\n");
+			return 1;
+		}
+
+		if(!check_netname(name, true))
+			fprintf(stderr, "Warning: unsafe character in netname!\n");
+	}
+
 	if(fd >= 0) {
 		close(fd);
 		fd = -1;
 	}
 
-	free(confbase);
-	confbase = NULL;
-	free(pidfilename);
-	pidfilename = NULL;
-	free(logfilename);
-	logfilename = NULL;
-	free(unixsocketname);
-	unixsocketname = NULL;
+	free_names();
+	netname = strcmp(name, ".") ? xstrdup(name) : NULL;
+	make_names(false);
+
 	free(tinc_conf);
 	free(hosts_dir);
 	free(prompt);
 
-	free(netname);
-	netname = strcmp(name, ".") ? xstrdup(name) : NULL;
-
         xasprintf(&tinc_conf, "%s" SLASH "tinc.conf", confbase);
         xasprintf(&hosts_dir, "%s" SLASH "hosts", confbase);
 	xasprintf(&prompt, "%s> ", identname);