1 files changed, 87 insertions, 0 deletions
diff --git a/src/knot/common/unreachable.h b/src/knot/common/unreachable.h
new file mode 100644
index 0000000..40094f9
--- /dev/null
+++ b/src/knot/common/unreachable.h
@@ -0,0 +1,87 @@
+/*  Copyright (C) 2021 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <pthread.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+#include "contrib/sockaddr.h"
+#include "contrib/ucw/lists.h"
+
+typedef struct {
+	node_t n;
+	struct sockaddr_storage addr;
+	struct sockaddr_storage via;
+	uint32_t time_ms;
+} knot_unreachable_t;
+
+typedef struct {
+	pthread_mutex_t mutex;
+	uint32_t ttl_ms;
+	list_t urs;
+} knot_unreachables_t;
+
+extern knot_unreachables_t *global_unreachables;
+
+/*!
+ * \brief Allocate Unreachables structure.
+ *
+ * \param ttl   TTL for unreachable in milliseconds.
+ *
+ * \return Allocated structure, or NULL.
+ */
+knot_unreachables_t *knot_unreachables_init(uint32_t ttl_ms);
+
+/*!
+ * \brief Free Unreachables structure.
+ */
+void knot_unreachables_deinit(knot_unreachables_t **urs);
+
+/*!
+ * \brief Get and/or set the TTL.
+ *
+ * \param urs          Unreachables structure.
+ * \param new_ttl_ms   New TTL value in milliseconds.
+ *
+ * \return Previous value of TTL.
+ */
+uint32_t knot_unreachables_ttl(knot_unreachables_t *urs, uint32_t new_ttl_ms);
+
+/*!
+ * \brief Determine if given address is unreachable.
+ *
+ * \param urs     Unreachables structure.
+ * \param addr    Address and port in question.
+ * \param via     Local outgoing address.
+ *
+ * \return True iff unreachable within TTL.
+ */
+bool knot_unreachable_is(knot_unreachables_t *urs,
+                         const struct sockaddr_storage *addr,
+                         const struct sockaddr_storage *via);
+
+/*!
+ * \brief Add an unreachable into Unreachables structure.
+ *
+ * \param urs     Unreachables structure.
+ * \param addr    Address and port being unreachable.
+ * \param via     Local outgoing address.
+ */
+void knot_unreachable_add(knot_unreachables_t *urs,
+                          const struct sockaddr_storage *addr,
+                          const struct sockaddr_storage *via);