core: add NMUtilsShareRules API for handling IP tables rules

Currently, shared rules are tracked by NMActRequest. Add a small
type for tracking the shared rules.

src/NetworkManagerUtils.c

@@ -1636,3 +1636,127 @@ nm_utils_ip_routes_to_dbus(int                          addr_family,
     NM_SET_OUT(out_route_data, g_variant_builder_end(&builder_data));
     NM_SET_OUT(out_routes, g_variant_builder_end(&builder_legacy));
 }
+
+/*****************************************************************************/
+
+typedef struct {
+    char *table;
+    char *rule;
+} ShareRule;
+
+struct _NMUtilsShareRules {
+    GArray *rules;
+};
+
+static void
+_share_rule_clear(gpointer data)
+{
+    ShareRule *rule = data;
+
+    g_free(rule->table);
+    g_free(rule->rule);
+}
+
+NMUtilsShareRules *
+nm_utils_share_rules_new(void)
+{
+    NMUtilsShareRules *self;
+
+    self  = g_slice_new(NMUtilsShareRules);
+    *self = (NMUtilsShareRules){
+        .rules = g_array_sized_new(FALSE, FALSE, sizeof(ShareRule), 10),
+    };
+
+    g_array_set_clear_func(self->rules, _share_rule_clear);
+    return self;
+}
+
+void
+nm_utils_share_rules_free(NMUtilsShareRules *self)
+{
+    if (!self)
+        return;
+
+    g_array_unref(self->rules);
+    nm_g_slice_free(self);
+}
+
+void
+nm_utils_share_rules_add_rule_take(NMUtilsShareRules *self, const char *table, char *rule_take)
+{
+    ShareRule *rule;
+
+    g_return_if_fail(self);
+    g_return_if_fail(table);
+    g_return_if_fail(rule_take);
+
+    rule  = nm_g_array_append_new(self->rules, ShareRule);
+    *rule = (ShareRule){
+        .table = g_strdup(table),
+        .rule  = g_steal_pointer(&rule_take),
+    };
+}
+
+void
+nm_utils_share_rules_apply(NMUtilsShareRules *self, gboolean shared)
+{
+    guint i;
+
+    g_return_if_fail(self);
+
+    if (self->rules->len == 0)
+        return;
+
+    /* depending on whether we share or unshare, we add/remote the rules
+     * in opposite order. */
+    if (shared)
+        i = self->rules->len - 1;
+    else
+        i = 0;
+
+    for (;;) {
+        gs_free_error GError *error = NULL;
+        ShareRule *           rule;
+        gs_free const char ** argv = NULL;
+        gs_free char *        cmd  = NULL;
+        int                   status;
+
+        rule = &g_array_index(self->rules, ShareRule, i);
+
+        cmd  = g_strdup_printf("%s --table %s %s %s",
+                              IPTABLES_PATH,
+                              rule->table,
+                              shared ? "--insert" : "--delete",
+                              rule->rule);
+        argv = nm_utils_strsplit_set(cmd, " ");
+
+        nm_log_info(LOGD_SHARING, "Executing: %s", cmd);
+        if (!g_spawn_sync("/",
+                          (char **) argv,
+                          (char **) NM_PTRARRAY_EMPTY(const char *),
+                          G_SPAWN_STDOUT_TO_DEV_NULL | G_SPAWN_STDERR_TO_DEV_NULL,
+                          NULL,
+                          NULL,
+                          NULL,
+                          NULL,
+                          &status,
+                          &error)) {
+            nm_log_warn(LOGD_SHARING, "Error executing command: %s", error->message);
+            goto next;
+        }
+        if (WEXITSTATUS(status)) {
+            nm_log_warn(LOGD_SHARING, "** Command returned exit status %d.", WEXITSTATUS(status));
+        }
+
+next:
+        if (shared) {
+            if (i == 0)
+                break;
+            i--;
+        } else {
+            i++;
+            if (i >= self->rules->len)
+                break;
+        }
+    }
+}

src/NetworkManagerUtils.h

@@ -224,4 +224,26 @@ NM_AUTO_DEFINE_FCN(NMDhcpLease *, _nm_auto_unref_dhcplease, nm_dhcp_lease_unref)
 
 /*****************************************************************************/
 
+typedef struct _NMUtilsShareRules NMUtilsShareRules;
+
+NMUtilsShareRules *nm_utils_share_rules_new(void);
+
+void nm_utils_share_rules_free(NMUtilsShareRules *self);
+
+void
+nm_utils_share_rules_add_rule_take(NMUtilsShareRules *self, const char *table, char *rule_take);
+
+static inline void
+nm_utils_share_rules_add_rule(NMUtilsShareRules *self, const char *table, const char *rule)
+{
+    nm_utils_share_rules_add_rule_take(self, table, g_strdup(rule));
+}
+
+#define nm_utils_share_rules_add_rule_v(self, table, ...) \
+    nm_utils_share_rules_add_rule_take((self), (table), g_strdup_printf(__VA_ARGS__))
+
+void nm_utils_share_rules_apply(NMUtilsShareRules *self, gboolean shared);
+
+/*****************************************************************************/
+
 #endif /* __NETWORKMANAGER_UTILS_H__ */